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Engineered for Tomorrow
Introduction
The MVJCE-Journal (ISSN 2394-6156) is an
online scholarly refereed research journal
which aims to promote the theory and
practice of engineering, science, innovation,
and technology management. The journal links engineering, science, and
technology management disciplines. It
addresses the issues involved in the
understanding, conceptualizing, planning,
development, and implementation of
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accomplish the strategic and operational
objectives of an organization. It covers not only
the activities of R&D in engineering, science and
management, but also the entire spectrum of
technical challenges, issues and concerns in
technologically intensive programs in
academics, industry and many organizations.
This includes issues relating to new areas of
research, core Engineering product and process
development, Technology management,
Innovation Process Management, and Strategic
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engineering, science and management with
technological advancement, real life
innovations and information management. Its
ultimate goal is to make a profound
contribution to theory development, research
and practice by serving as a leading forum for
the publication of scholarly research on all
aspects of Engineering, Science & Engineering
Management.
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College Vision and Mission
Vision: To become an Institute of Academic
Excellence with International standards.
Mission: The Mission of the college is to:
1. Impart quality education along with industrial
exposure.
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research activities relevant to industrial and
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benefits.
Foreward
The erstwhile journal of Engineering, Science, Technology and Management has
been renamed as MVJCE Journal, though it will contain articles covering all the above said
fields. This is the first release of MVJCE Journal after the name change. I am happy to write
few words as a part Foreward message.
Research is an important component for economic and social development in tune
with this emphasis is given to research and development activities all across.
From academic institutions stand point, this will enhance quality of engineering
education that is required to face the challenges of 21st century.
I am happy to see articles covering Science, engineering and management
disciplines. Though presently the journal is covering articles on in-house activities, we
should encourage articles from outside institutions as well, since knowledge sharing will
help grow faster.
I am told that further publications will include, section on inventions made globally
to provide encouragement to do more research leading to innovation.
I wish good luck to the contributors and editorial board.
K Thyagarajan
Director R & D
MVJCE, Bangalore.
TABLE OF CONTENTS
Sl. No.
Title Author Page
No
1 Performance of bonding layer on the repairing of concrete structure
K.Kumar1 & T Soumya2 01-10
2 Recent developments in mica-epoxy-glass composites and their application in HV rotating machines
A.K.Shukla1 and A.K.Basu2 11-15
3 Room Temperature Preparation of Nanocrystalline Tin Oxide
Sharanya S Nair1 & Ramdas Balan2
16-18
4 A planar UWB antenna with notched bands for WIMAX and WLAN applications
Benjamin I 19-23
5 Smart Wearable Obstetric Assistant and Reminder Manoranjan Kumar1 & Divya.P.K2
24-30
6 Study of Color and Gray Image Denoising using Different Filter Techniques
Aruna Dore 31-36
7 A Survey on Human Sensing Applications using UWB Radar
PrashantSGhulappanavar1 & Kavya B M2
37-42
8 Graphene: A Wonder Material Poornima R 43-50
9 Ethical issues of monitoring alzheimer’s patients Bindiya Patil1, Shruthi B.R2 & Roopashree B.G3
51-54
10 Study of Diode, Bipolar Junction Transistor and Op-amp using MATLAB
Divyashree1 & Shivakanth2
55-59
1 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
PERFORMANCE OF BONDING LAYER ON THE
REPAIRING OF CONCRETE STRUCTURE
K.Kumar,
Dept. of Civil engineering, MVJ College of Engineering, Bangalore 560067
T.Soumya,
Dept. of Civil engineering, MVJ College of Engineering, Bangalore 560 067
Corresponding Author: Dr. Krishnan Kumar, Ph.D, Phone :+918971301227,
Email: [email protected]
Abstract: The durability of concrete structure
depends upon the deterioration of concrete,
corrosion of steel and other mechanical
behavior. Cracking and delamination of the
concrete gives alarm to failure of structure.
Deterioration of reinforced concrete
structures is generally manifested in the form
of cracking, spalling, scaling, loss of strength
etc. A proper rehabilitation measure
enhances the trouble free life of the structure.
The selection of material is the most
important step in the repair programme.
Different generic materials were studied for
their performance on the bonding strength
between existing concrete and new overlay is
of major concern to decide the efficiency of
the rehabilitation measures. The bond
performances were evaluated by slant shear,
splitting tensile and flexural tests. Bonding
layer based on epoxy shows efficient
performance.
Keywords: Concrete structures,
deterioration, corrosion, repair, bonding
layer
INTRODUCTION
High quality concrete provides the ideal
environment for reinforcing steel. Steel in
concrete does not corrode due to tightly
adhering protective oxide film formed in the
alkaline environment. This is known as
passive protection. However, iron, the
principal component of steel has a persistent
tendency to return to its natural state, generally
iron oxide or rust, wherever the opportunity
arises. However, if the alkalinity of the
concrete is reduced through carbonation or the
passivity of the steel is destroyed by
aggressive ions like chlorides the structure
starts deterioration. The increase in volume
due to corrosion process causes high radial
bursting stresses around the reinforcing bar
and results in local radial cracks. These
splitting cracks can propagate along the bar,
resulting in the formation of longitudinal
cracks parallel to the bar.
These cracks provide easy access for oxygen,
moisture and chlorides creating a condition in
which corrosion continues and causes further
cracking and spalling. Exposed concrete
surfaces may accelerate corrosion by
providing entry points for moisture and other
corrosive ions. Remedial action must be taken
so that progressive deterioration does not
ultimately threaten the structural adequacy.
While facing the challenge on durable concrete
structures, we are also encountering with the
task of providing durable repairs to the
deteriorating/damaged structures. Many
architects, engineers and contractors in the
country execute concrete repair/rehabilitation
by patch repairs and consider it as an artisan
3 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
job. This approach is dangerous and has to be
eschewed. In fact the assessment, design and
implementation of repairs to existing
structures are indeed more complex than those
for new construction
Failure of repair works in most cases will be
due to inadequate bond between parent
concrete and new material. Normally a
bonding layer is applied for better bond
between old and new concrete. There are many
case studies for bond failure due to moisture
entrapment at the bonding layer [G.D.
Shanbag, 2000]. A systematic evaluation of
different bonding layers were carried out based
on the international standard specifications and
other literatures. The cement mortar slurry on
the old concrete substrate and steel surface
offered excellent protection to the bar in the
repair zone [R.W, Lambe, 1990]. However
corrosion of the steel adjacent to the repair in
the surrounding concrete may be accelerated.
This effect is thought to be due to the highly
alkaline mortar making the bar in the repair
zone cathodic to the surrounding concrete
which could become a corroding area by way
of forming macrocell. [Cavalier,P.G, 1982].
The selection of material is the most important
step in the repairs and rehabilitation
programme. The proprietary materials
available in the market has been compared
based on the manufacturer’s literature
normally highlights the composition of the
materials rather than performance
characteristics. In this paper three different
generic material such as cement slurry, acrylic,
epoxy and SBR based bonding layers were
studied for their bond performance as a
bonding layer.
MATERIALS
Sl
No
Description Details
Concrete
1 Cement Ordinary Portland
cement conforming to
IS-456-2000
2 Course
aggregate
Graded coarse
aggregates conforming
to graded aggregates of
normal size greater than
4.75 mm and less than
10 mm of IS-456-20
3 Fine
aggregate
Clean river sand used
as graded fine
aggregates (fineness
modulus of medium
sand equal to 2.6)
conforming to grading
Zone III of IS-383-
1970.
Bonding materials
1 Cement
Slurry
System - Cs
2 Acrylic
resin
System - A
3 Epoxy
resin-two
pack
System - B
4 Acrylic &
Epoxy
System - C
5 Styrene
Butadiene
Rubber
System - E
6 Epoxy &
Hardener
one coat
with sand
sprinkling
System - Ey
The bonding materials were applied on the
prepared surfaces of the old concrete. The
4 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
surface preparation was carried out in
accordance with ASTM D 4259 – 88
(Reapproved 1992).
METHODS
Slant Shear test [ASTM c882-91]
The bond strength of old to new concrete is
determined by using two equal sections of
76.2*152.4mm Portland mortar cylinder, each
section of which has a diagonally cast bonding
area at a 30 angle from vertical axis. The
specimens were subjected to cure for 28 days.
After 28 days of curing the slanting phase of
the specimens were taken out and air dried for
24 hrs. The dry surface was sand blasted in
order to get perfect adhesion between the
concrete and the bonding layer. Bonding
layers as in material selection were applied on
the slanting (elliptical) portion of sand blasted
surface. The new concrete was poured over
the elliptical surface immediately after
application of bonding layer. The new
concrete was subjected to curing for a fixed
time depending upon the type of system. After
curing, the specimens were subjected to
compression test. The tested specimen for
slant shear is as shown in Fig 1. The bond
strength was calculated by dividing the load
carried by the specimen at failure by the area
of the bonded surface.
Tensile Strength Test
The tensile strength of concrete is measured
indirectly by finding the tensile strength of
cement, sand and mortar to which standard
briquettes are prepared using 1:1.14 cement
mortar with W/C ratio of 0.45 and the having
standard dimensions and allowed for curing.
For each experiment six specimens were used.
The pure mortar specimens were subjected to
tensile test, and the breaking load was noted.
After the specimens were split into two pieces
the split specimens were joined with each
other using different bonding layers and the
test results were compared with the original
mortar specimen without any bonding layer.
The tensile strength of the specimen was
calculated using the formula
Tensile strength Tensile Load (N)
(N/mm2) = Area of the specimen (mm
2)
Flexure Test [BIS 516-1959, ASTM C78-94]
Flexural strength of the concrete beam of size
500*100*100 mm was cast and tested by third
point loading at a rate of 1.2 KN/min.
Flexural strength is expressed in terms of the
modulus of rupture at the beams were cast
using (1:1.18:2.77) M30 concrete with the W/C
ratio of 0.45 and subjected to curing for 28
days. Cured specimens were subjected to third
point loading, and the load at failure was noted
(before repair). After the specimens were
broken into two, the two pieces were joined
with different systems of bonding layers then
tested for flexural strength.
RESULTS AND DISCUSSIONS
Slant Shear test
One of the critical factors governing the
achievement of an effective repair is good
adhesion at the interface of the repair material
and the concrete substrate. Good adhesion is
imperative for structural repairs where
monolithic character is required for the
transfer of load. Bonding agents play a
significant role where it is critical to ensure
bond at the interface [Noel P. Mailvaganam,
1997]. The performance of different bonding
5 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
layers in slant shear test is given in Table. 1 in
which the nature of failure represented by
bond failure is the failure occurred at the shear
plane. The monolithic failure is represented by
cracking other than shear plan.
The result shows that epoxy-bonding layer
exhibited better performance with average
slant shear strength of 5.5 N/mm2. Bonding
layer with cement slurry has shown slant shear
strength of 3.00 0.2 N/mm2.
System A and C
have performed in the same manner. Other
systems have shown inferior performance.
While comparing the nature of failure, epoxy
based system has a monolithic failure, which
indicates the system has superior performance
compared to all other systems. It is observed
that in the bond failure the new concrete mass
separated from the old concrete. The bonding
layer thickness shall be optimum. When the
thickness of binder is thinner it will perform
better. The stiffness of the aggregate-binder-
aggregate system increases as the bonding
layer gets thinner [Dong wang, 2013]. System
E performed almost like cement-based system.
Monolithic failure observed in epoxy System
and bond failure observed in system – Cs & C
which is the typical bonding layer failure.
However the system – Cs & C performed for
higher shear strength. System A shown
bonding failure elucidate acrylic resin is not
suitable for bonding old and new overlay.
System – B performed as like system Ey but
failed lesser in shear strength.
Direct Tension
Triplicate standard briquettes were made and
cured for 28 days. The cured specimens were
tested for direct tensile strength. The split
portions of the tested briquettes were coated
with system B and epoxy and bonded together.
After the curing of the bond coat again these
specimens were tested for direct tension.
Results of the bonded briquettes with different
bonding materials were shown in Table 2.
This results shows better performance for
epoxy based system. None of the specimen
bonded with epoxy system failed at the bonded
plane. In the case of System B bonding layer
specimen, out of three failed very near to the
bonded plane. The system – B has an
advantage of epoxy.
Flexure
Flexural specimens of standard size (100
mm*100 mm*500 mm) were cast and cured.
These specimens initially tested for the
flexural strength by applying point loads at
middle third position. Tested specimens were
joined with System-B and System-Ey and
allowed for 24 hours of curing period.
After the curing is over these specimens were
tested again for flexural strength. Test results
were shown in Table 3 which shows both the
systems performed as original beams. System-
Ey slightly reduced the flexural value than the
System-B. This may be due to improper
wetting of the bonding portions or improper
sealing of the bonding material.
Repaired Beam
To prove the efficacy of the bonded materials,
these systems were imparted actually in the
affected beams for rehabilitation work. Two
affected beams reinforced with nominal design
were selected is shown in Fig. 2. Middle
portion of the tensile zone has been provided
with untied lapping arrangement. These
beams were initially loaded at the middle third
points and tested for its bonding behavior at
the lapped portion.
The beams under test have been coated with
both epoxy bonding and cement slurry
bonding layer and the results of which are
6 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
shown in Table 4. These beams were
subjected for the flexural behavior, where the
cement slurry system failed at the lapped
portion indicating a bond failure. The load
taken was less than the original. In the case of
epoxy based bonding system the failure
occurred at the adjacent place of the bonding
area. The visual observation has shown that
the new material is intact with the bonding
layer along with old concrete, which is shown
in the Fig. 3. The load taken has exceeded the
original.
Liquid epoxy in tacky conditions has been
found to be an excellent bonding coat. When
large area is to be concreted the time lag
between application of the epoxy bond coat
and subsequent placement of new concrete
may increase. This results in the epoxy being
partially or fully set and consequently it acts as
a de-bonding agent rather than a bonding
agent. This is not because of the failure of the
material but due to the two-pack epoxy not
being utilized properly. Hence, precautionary
measures must be considered while selecting a
bonding material and method of application.
Conclusion
Thus the comparative performance study
determined the use of several bonding
materials for repair / rehabilitation work has
derived the following conclusions.
Bond between old and new concrete is an
essential factor to be considered for the better
repair methods.
A bonding agent with better bond strength will
show the monolithic failure in slant shear
strength test.
Proper surface preparation is necessary before
application of any bonding layer.
Before casting new concrete an additional wet
of bonding layer shall be provided for better
adhesion.
Epoxy based systems are proved better in bond
strength under slant shear, splitting tensile and
flexural beams evaluations.
REFERENCES
1. Dong wang et al, “Experimental Evaluation of a
Simple Contact Model Containing Two Elastic
Particles Bonded by a Thin Layer of Viscoelastic
Binder”, Journal of Nanomechanics and
Micromechanics, Volume 3, Issue 4 (December
2013).
2. G.D. Shanbag, P.G. Gokhale and B.V.
Bhedasgaonkar, “Restoration of hammer
foundations in forging industry – a case study” The
Indian Concrete Journal, January(2000), pp 46-48
3. Noel P. Mailvaganam, “Effective Use of Bonding
Agents”, Construction Technology Updates,
National Research Council of Canada, December
1997
4. R.W,Lambe, M.J.Aumphrey, T.F.Watkins,
“Development of materials for repair and protection
of reinforced concrete”, “corrosion of
reinforcement in concrete”, edited by C.L.Page
(1990), pp 471 – 485.
5. Cavalier,P.G, and Vassie.P.R, “Investigation and
repair of reinforcement corrosion in a bridge deck”,
proc., Instn., of civil engg., part I, (1982), 72, 401 –
419.
6. ASTM D4259-88 (Reapproved 1992) - “Standard
Practice for Abrading Concrete”.
7. ASTM c882-91, “Standard Test Method for Bond
Strength of Epoxy Resin systems used with
concrete by slant shear.
BIS 516-1959, Indian Standard Methods of
tests for strength of concrete.
ASTM C78-94, Standard Test Method for
Flexural strength of concrete (using single
beams with third point loading)
7 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
Figure 1: Slant shear tested specimen
Figure 2: Beam before repair
Figure 3: Beam repaired with bonding layer
8 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
Figure 4: Performance of bonding layer in repaired beam
Table: 1 Slant shear behavior comparison of bonding layer
Batch No.
Type of
Bonding
Layer
Load at
failure KN
Bond
stress MPa
Nature of failure
I System-Cs 25.22
29.13
28.54
2.77
3.19
3.13
Bond failure
Bond failure
Bond failure
II System-A
24.69
25.07
14.34
2.71
2.75
1.57
Bond failure & cracking at new
concrete.
Bond failure & cracking of upper
layer.
Bond failure
III System-B
26.36
15.66
2.89
1.72
Cracking failure, No bond failure
Shear failure
IV System-C
29.13
24.32
22.00
3.19
2.67
2.41
Bond failure
Bond failure
Combined failure
VI System-E
09.53
10.28
07.23
1.04
1.13
0.79
Bond failure
Bond failure
Bond failure
9 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
VII System-Ey 27.57
51.62
54.84
3.02
5.66
6.01
Monolithic failure
Monolithic failure
Monolithic failure
Table 2: Performance of bonding layer in direct tension
Before Repair
After Repair
Batch No.
Load at failure
in KN
Direct
tension
N/mm2
Type of
Bonding
Layer
Load at
failure in
KN
Direct
tension
N/mm2
I
2.240
1.930
1.689
3.58
3.09
2.50
System Ey
1.612
2.387
1.086
2.48
3.27
1.67
II
1.889
1.973
1.488
3.02
3.16
2.38
System B
1.965
1.391
1.735
2.91
3.02
2.31
Table 3: Performance of bonding layer in flexure
BEFORE REPAIR
AFTER REPAIR
Specimen
No.
Load at
failure in
KN
“a” in
Cm
Fb
N/mm2
Bonding
Layer
Load at
failure in
KN
“a” in
Cm
Fb
N/mm2
1
13.5
16.10
6.52
System Ey
9.5
17.00
4.84
2
11.0
17.85
5.89
System B
12.0
17.00
6.12
10 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
K.Kumar, T.Soumya
Table 4: Bonding layer performance on the repaired RCC beam
BEFORE REPAIR
AFTER REPAIR
Beam No.
Load at failure in
KN
Bonding Layer
Load at First
Crack in KN
1.
25.50
Cement Slurry
22.50
2.
32.50
Epoxy
61.00
11 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
A.K.Shukla and A.K. Basu
RECENT DEVELOPMENTS IN MICA-EPOXY-
GLASS COMPOSITES AND THEIR APPLICATION
IN HV ROTATING MACHINES
A.K.Shukla and A.K. Basu
Dept. of Chemistry, MVJ College of Engineering, Bengaluru-560 067.
Lakshmanan Isola Pvt. Ltd., Quality and R&D, Bengaluru-560 025
Corresponding author: e-mail : [email protected]
Abstract:By virtue of high corona resistance
Reconstituted mica constitutes the most
important component of insulation in high
voltage motors and generators. The paper
describes the recent developments in
processing, characterization, and application
of the state-of-art dielectric composite
insulating materials based on reconstituted
mica and epoxy resin reinforced with glass
fabric (MEG). MEG composites in the form
of folium/tapes after curing show high
dielectric strength >35 kV/mm, very low
dissipation factor (Tan δ) value 0.075 at 1 kV
at 25°C and very little increase in Tan δ with
rise in temperature upto 155°C and voltage
upto 12kV. Thermal aging studies conducted
at 180, 200 and 220°C for 28 days on mica-
epoxy-glass laminate after curing show fairly
good retention of dielectric strength,
indicating their suitability for application in
thermal class 155 motors and generators.
Keywords: Mica paper, epoxy resin,
reconstituted mica, electrical insulation,
dielectric composites
1.0 INTRODUCTION
Use of mica is essential in the main insulation
of electrical rotating machines operating at 2.5
kV or above owing to its unique resistance to
corona discharges[1-5]
. Being a brittle and sheet
like mineral, mica has limited scope for
application. However by virtue of its unique
property of splitting into thinest flakes, it is
converted into a thin paper-like material called
reconstituted mica using thermal, chemical
and mechanical processes. To enhance the
inherently low mechanical strength (6-12
N/cm) of such a paper it is reinforced with a
layer of glass fabric or a polymer film and
bonded with a synthetic thermosetting resin[6-8]
.
Application of resin-rich mica paper-epoxy
based composites involves thermo
compression of insulated copper bars till
consolidation in the hydraulic press followed
by post curing in the oven[9]
. During the
process the bonding epoxy resin initially
softens on heating in the press and under high
pressure the fluid resin fills all the voids and
the excess resin oozes out from the sides, thus
producing a void-free insulation. The ultimate
objective of this insulation technology is to
incorporate maximum quantity of mica in the
void-free insulation[3-5]
.
In this paper the authors have presented the
development, processing and characterization
of state of the art reconstituted mica – epoxy-
glass reinforced composites suitable for resin-
rich technology. Results of cured composites
after their respective processing and after heat
ageing are also discussed. Recommendations
for their application in high voltage rotating
machines have also been given.
2.0 EXPERIMENTAL
2.1 MATERIALS USED:
2.1.1 Reconstituted Mica: Muscovite mica,
general formula, KH2Al3(SiO4). 2H2O,
available from Jharkhand, India is processed
into reconstituted mica papers of different
grades depending upon thickness, unit weight,
porosity and impregnation time. Following
12 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
A.K.Shukla and A.K. Basu
two grades of mica paper complying with the
requirements of IEC 60371-3-2 and
manufactured by m/s Lakshmanan Isola,
Bangalore were used in preparation of
composites.
TABLE 1: Characteristics of reconstituted mica
Mica paper
grades→
Characteristics↓
11/21-75
(MMc)
11/21-
150
(MMc)
Mica grade Muscovi
te
calcined
Muscovi
te
calcined
Thickness, mm 0.060 0.115
Unit weight, g/m2
75 150
Tensile strength,
N/cm
5 - 10 6 - 12
Porosity
(Gurleyhill),
s/100ml
3000-
6000
5000-
10000
Impregnating time,
s
20 - 60 150 -
300
2.1.2 Calcined mica paper: Mica is calcined
in rotary kiln at 770-830°C and after chemical
and mechanical treatments converted into pulp.
Specific particle size fractions separated by
vibro-screening are mixed and processed into
a paper like material. Calcined grades 11/21-
75 and 11/21-150 (MMc) with characteristics
as given in Table-1, has been used in MEG
composites.
2.2 Resin binder: Unmodified Epoxy
Novolac Resin EPN 1138 having epoxy
equivalent 176-181 g/equiv and viscosity
35000-70000 cP from Huntsman High
Performance Polymers was used for
preparation of composite folium.
2.3 Accelerator: Lekutherm- Accelerator
KU-6519 based on Boron trifluoride-amino
complex from Rhein Chemie, Germany was
used for catalytic curing of epoxy resin.
2.4 Reinforcement: Electrical grade glass
cloth having low alkali content (Na2O
<0.05%), low sizing content (<2%) and unit
weight 25 and 35 g/m² manufactured by
K.E.Technical Textiles, Kharagpur, have been
used as reinforcement in the composites.
3.0 DEVELOPMENT OF MEG
COMPOSITES
3.1 Processing of Mica-Epoxy-Glass
Composites:
Process involves application of pre-accelerated
epoxy-novolac varnish on to the glass cloth
and the calcined mica paper, lamination of the
two layers followed by drying & partial
polymerization in a horizontal drying
machines having four temperature zones
ranging from 70-150°C. Important process
parameters to be controlled are varnish
composition, viscosity, temperature and
machine speed in order to achieve the
specified characteristics in the product.
3.2 Control of Process parameters:
(a) Resin content and composition: Epoxy-novolac resin is dissolved in a suitable
proprietary solvent keeping the resin content
in the range 15-30% by weight. Recommended
quantity of the accelerator is dissolved in the
varnish and the solid content are verified by
drying a portion of the varnish in the oven and
measuring the weight after cooling.
(b) Viscosity of the composition: Viscosity of the above varnish is measured
using LG (DIN) cup and is maintained in the
range 8-18 sec.
(c) Machine speed: Speed of movement of
glass fabric and the mica paper is maintained
in the range 1-6 M/min as required according
to the temperature in drying chamber zones.
(d) Temperature : Temperatures in the 4
zones of the horizontal drying chamber are
maintained in the range 60-160°C according to
the resin flow required in the B-stage product.
3.3 Characterisation of the B-stage folium :
The product obtained in B-stage in the form of
folium is characterized for thickness, unit
weight, mica and resin content, resin flow and
stiffness. Resin Flow is an important
characteristic and is measured by placing 4
layers of 4” x 4” size after weighing, between
13 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
A.K.Shukla and A.K. Basu
the hot platens of the hydraulic press at a
temperature of 130-150°C and pressure of 5-
10Kg/cm2. Stiffness of the folium specimen is
measured by using Stiffness Tester according
to the standard IEC method.
3.4 Curing of the composite folium: Curing
conditions have been optimized and
recommended as 4-6 hrs at 150-180°C.
4.0 CHARACTERISATION
4.1 MEG Composites in B-stage : They are
characterised for thickness, total substance,
mica, glass and resin content, tensile and
electrical strength (BDV). Typical
characteristics of MEG composite tapes of the
grades 180:75 and 305:150 are presented in
Table-2.
TABLE-2: Characteristics of MEG composites in
B-stage
Characteristics MEG
(180:75)
MEG
(305:150)
Thickness, mm 0.13 0.22
Total substance,
g/m2
181 306
Mica content, % 41.5 49.5
Resin content, % 38.8 38.5
Glass content, % 19.3 11.5
Resin flow,% 19.5 20.2
Tensile strength,
N/cm width
221 235
Breakdown
voltage, KV
> 5.0 > 6.0
4.2 MEG Composites after cure :
a) Dielectric Strength : Laminate specimens
were prepared from the B-stage MEG
composite folium, cured and subjected to
dielectric strength measurements using
„Temaco‟ make BDV Tester. The values are
plotted against the temperature at which the
test was conducted, and shown in fig. 1
b) Dissipation Factor (Tan δ) : „Tettex‟
Schering Bridge model 2801 was used to
measure Tan δ at normal as well as at elevated
temperatures i.e. 25 and 155°C. Effect of rise
in voltage at 50Hz on Tan δ was studied and
the comparative results are plotted in Fig.3.
c) Stiffness/Flexibility Study : This
characteristic was studied on both the grades
of MEG composites using Stiffness Tester
conforming to JIS C2116-1992 supplied by
VonRoll Isola. To check the storage life of the
MEG composite tapes, the bending stiffness
values are plotted against storage period at
room temperature in fig.5.
d) Thermal Aging Study: Thermal aging
was conducted at 180, 200 and 220°C for 28
days on insulated copper bars with both grades
of the MEG composite tapes and BDV was
measured at different intervals. Results are
plotted in Fig.6.
Fig.2 : Dielectric strength vs. Testing temp.
5.0 RESULTS AND DISCUSSION
5.1 Dielectric strength : The plot of
dielectric strength values of the cured MEG
laminate specimens measured at different
temperatures, as shown in fig.1, indicates a
reduction in the dielectric strength with
increase in the testing temperature. However,
the actual value at 155°C still remains quite
high at 38kV/mm indicating its suitability as
insulation at the machine operating
temperature of 155°C.
5.2 Dissipation Factor vs. Voltage: Plots of
Tan δ against voltage (Fig.3) show little
increase with voltage upto 12 kV at 25°C
temperature and also at 155°C indicating good
14 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
A.K.Shukla and A.K. Basu
resistance to corona in the insulation under
these conditions.
Fig.3: Plot of Tan δ vs. Voltage
5.3 Dissipation Factor vs. Temperature:
Plots of Tan δ at 1 kV, 50Hz frequency against
temperature up to 180°C shown in Fig.4 show
very low values which do not increase
appreciably with the rise in temperature. It is
to be noted that Tan δ values for the cured
MEG tape having higher mica content are
lower as compared to MEG with less mica.
Fig.4: Plot of Tan δ vs. Temperature
5.4 Stiffness of MEG composite tapes: The plot of Bending stiffness values (Fig.5) of
MEG tapes show significant increase in
stiffness starting from 20 N/m before curing
and rising to above 100 N/m, after 60 minutes
of curing at 160°C. This is due to
consolidation of the epoxy resin.
Fig.5: Plot of Stiffness vs. Curing time
5.5 Thermal aging study: Plots of dielectric
strength of MEG laminate versus Aging period
in days, (Fig.6) show the deterioration in
dielectric strength during aging at 180, 200
and 220°C. After 28 days of thermal aging the
dielectric strength has fallen to 39, 26 and
20kV/mm respectively.
Fig.6: Plot of Dielectric strength vs. Aging time
6.0 RECOMMENDATIONS FOR
APPLICATION IN ROTATING
MACHINES
6.1 As Conductor Insulation: Lower
thickness (0.13 mm) tapes of MEG composite
(grade 180:75) in B-stage are suitable for
application as half lap, conforming to the
copper bars to act as conductor insulation.
They have shown very high dielectric strength
and very low dissipation factor after curing.
6.2 As Main Insulation : MEG tapes of
higher thicknesses (0.18 or 0.22 mm) are
suitable for application as one and half lap on
the straight portion of the coils and should be
hot-compressed (2.0-3.0 MPa) in the
15 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
A.K.Shukla and A.K. Basu
hydraulic press for consolidation. After
cooling while in the press, they are removed
and subjected to curing & post curing in the
oven at 160°C.
6.3 Curing Conditions : Curing : 4-6 hrs at
150-180°C ; Post curing : 8-12 hrs at 140-
160°C
7.0 CONCLUSION
Following conclusions can be drawn from the
above studies. Cured MEG composites, show
a very little increase in Tan δ with rise in
temperature and voltage. At 25°C it rises from
0.008 to 0.032, while at 155°C Tan δ rises
from 0.042 to 0.110, as the voltage increases
from 1 kV to 12 kV in both the cases,
indicating their suitability as conductor and
main insulation. MEG composite having
higher mica content, after cure has lower
values of Tan δ at elevated temperatures than
those for the MEG laminate containing lower
mica content.
Good retention of dielectric strength of MEG
composites (originally 45 kV/mm) after
thermal aging for 28 days at 180, 200 and
220°C showing the
residual dielectric strength values at 39, 26 and
20 kV/mm respectively has been observed.
Mica-Epoxy-
Glass composites have shown the suitability
for application as conductor insulation and
also main insulation for thermal class 155
rotating machines.
ACKNOWLEDGEMENT
The authors are grateful to the Managements
of The MVJ College of Engineering and m/s
Lakshmanan Isola Pvt. Ltd., Bangalore for
constant support in the research work and
permission for presentation of this
developmental work.
REFERENCES: [1] A.K. Shukla & A.K. Basu, “Advanced micaceous
composite materials and their application in high
voltage rotating machines and fire resistant cable
insulation”, Proceedings of International Conference on
Polymeric Materials for Power Engineering, CPRI,
Bangalore, October 6-8, (2007).
[2] A.K.Shukla & M. Surekha, “Advanced silicone
bonded micaceous composites and their application in
traction motors”, National Conf. on Futuristic Polymer
Materials (FPM-2008), R.V.College of Engineering,
Bangalore, 26th
& 27th
Sept‟(2008).
[3] A.K.Shukla , “Processing, Characteristics and
Applications of Dielectric Composites based on
Reconstituted Mica for High Voltage Rotating
Machines”, ISAMPE National Conference on
Composites ( INCCOM-7), National Aerospace
Laboratories, Bangalore-17, Dec. 4-5, 2008.
[4] A.K.Shukla & A.K.Basu, “ Advanced Dielectric
Materials based on Mica for High Voltage generators,
Motors and Cable Insulation”, National Seminar on
maintenance of Generators and Motors, Indian Institute
of Plant Engineers, Karnataka Chapter, Bangalore,
July‟2007.
[5] H. Yoshida and H. Mitsui ,”Rotating machine
Insulation”, IEEE Trans. on Electrical Insulation Vol.
EI- 21, No.6, December 1986.
[6] Aleksandrov N.N., et.al., “Electrophysical
properties of mica papers differing in fractional
composition.”, Elektrotekhnika, vol.53, No.10, pp.31-
33, 1982.
[7] Mitsui H., et.al., “Improvement of Rotating
Machinary Insulation characteristics by using Mica
Paper containing Aramid Fibrid.” , IEEE Trans. on
Electrical Insulation Vol. EI-18, No.6, December 1983.
[8] Kenzo Kadotani, “Effect of Mica Paper on
Properties of Coil Insulation”, Electrical Engineering in
Japan, Vol.102, No.6, pp.1-8, 1982.
[9] Nurse J.A., “Development of modern high-voltage
insulation systems for large motors and generators”,
Power Engineering Journal, pp.125-130, June‟ 1998.
16 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Sharanya S Nair, Ramdas Balan
ROOM TEMPERATURE PREPARATION OF
NANOCRYSTALLINE TIN OXIDE
Sharanya S Nair
Department of Chemical Engineering
MVJ College of Engineering
Bangalore, India
Ramdas Balan
Nano Research Lab, Department of Physics
MVJ College of Engineering
Bangalore, India
Abstract— Nanocrystalline SnO2 was
prepared at room temperature by acid
treatment of precipitation method prepared
precursor, CaSn(OH)6 using NaOH as
precipitant. The precursor and acid washed
compounds were characterized by X-Ray
Diffraction (XRD), Brunauer – Emmett –
Teller (BET) and Scanning Electron
Microscope (SEM) analysis. X-ray
diffraction confirms single phase SnO2
dissolute from Brutite structured
CaSn(OH)6 by acid treatment. The
crystallite size was calculated using
Scherrer equation found to be in the range
of 10 - 20 nm. SEM micrograph and BET
confirms the porous nature of the prepared
SnO2.
Keywords— Tin oxide ; Nanocrystalline;
Scanning electron microscope; BET
I. Introduction
Tin Oxide (SnO2) is an important n type
wide band gap (Eg=3.6eV at 300K)
semiconducting oxide, studied as a potential
candidate for transparent conducting oxide
(TCO) [1], dye sensitizer solar cells (DSSC)
[2], lithium rechargeable batteries [3], gas
sensor [4, 5], catalysis [6 ,7] and antistatic
coatings [8] due to its physiochemical
properties. Many of its applications are
surface dependent which required large
surface area and porous nature. In this
regard, there are many reports on
conventional techniques to prepare porous
SnO2 with high surface area [9, 10]. Also,
there are few reports on preparation of
porous SnO2 by non conventional technique
by dissolution of complex oxide obtained by
heat treatment of the hydroxides such as
CoSn(OH)6 [11], CuSn(OH)6 [12] and
CaSn(OH)6 [13].In this paper, we report
the preparation of porous nanocrystalline
SnO2 by direct dissolution from the
prepared hydroxide i,e CaSn(OH)6 in
single step.
II. Experiment
A. Preparation of CaSn(OH)6
All chemical reagents used in this
experiment were analytical grade. 1M of
aqueous solutions of each CaCl2.5H2O and
SnCl4.2H2O were added to 500 ml of 2M
NaOH solution with constant stirring. A
white precipitate was formed. The precipitate
was then washed using distilled water to
remove all chloride ions and filtered. Then
the precipitate was dried in hot air oven at 80
oC for 12 h. The resultant white powder is
called as precursor.
B. Preparation of SnO2
The precursor was mixed with addition of 50
mL of 1.0 M HCl with constant stirring for
1h. Then, the product was rinsed with
distilled water until the pH of the solution
was neutral. And finally, centrifuged and
dried in hot air oven for overnight.
The precursor and acid treated products were
characterized by Powder X-ray diffraction
(PAN analytical X’Pert Pro) with CuK
radiation, Brunauer – Emmett – Teller (BET)
nitrogen adsorption–desorption (Nova
2000E) and Scanning electron microscopy
(HITACHI Model S-3000H) for phase
identification, purity and morphological
studies.
17 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Sharanya S Nair, Ramdas Balan
III. Results and Discussion
A. X-ray Diffraction studies
Fig. 1 shows the XRD pattern of the precursor prepared by precipitation method. The pattern matches well with the standard data (JCPDS card No. 09-0030) of CaSn(OH)6 with no additional peak confirms single phase formation, crystallizing in cubic structure with lattice parameter a = 0.814(0) nm calculated using least square method.
Fig. 2 shows the XRD pattern of acid treated product, confirms single phase SnO2 matching with the standard data (JCPDS card No. 041-1445). Broadened XRD peaks concludes the nanocrystalline nature of the prepared SnO2 compounds, crystallite size was calculated to be 10 - 20 nm using
Scherrer equation, d = (0.9 )/ BCos .
B. Surface Area Analysis
Fig. 3 adsorption and desorption isotherm of
prepared SnO2 clearly shows type IV kind,
revealing the presence of mesoporous. BET
surface area of the prepared SnO2 was
measured to be 160.55 m2/g.
C. Morphological studies
Fig. 4 shows the SEM micrograph of SnO2.
The particles were in the size range of 100
nm – 500 nm with porous nature.
IV. Conclusion
SnO2 was prepared at room temperature by
dissolution of CaSn(OH)6. Powder - XRD
and BET characterization confirms single
phase, porous, nanocrystalline nature of the
prepared SnO2.
References [1] M.J. Van Bommmel, W.A. Groen, H.A.M.
Vanhal, W.C. Keur, T.N.M. Bernards, J. Mater. Sci.
34 (1999) 4803.
[2] Ferrere S, Zaban A, Gregg B A. Dye sensitization
of nanocrystalline tin oxide by perylene derivatives. J
Phys Chem B 101(1997) 4490.
[3] Lou X W, Wang Y, Yuan CL, Lee J Y, Archer L
A . Template-free synthesis of SnO2 hollow
Figure 1: Powder XRD pattern of the precursor
Figure 2: Powder X -Ray Diffraction
pattern of acid washed precursor
Figure 3: Nitrogen adsorption and desorption plot of
prepared SnO2
300 nm 500 nm
18 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Sharanya S Nair, Ramdas Balan
nanostructures with high lithium storage capacity.
Adv. Mater 18 ( 2006) 2325.
[4] Yin X M ,LiC C, Zhang M, Hao Q Y, Liu S, LiQ .
SnO2 monolayer porous hollow spheres as a gas
sensor. Nanotechnology 20 (2009) 455503
[5] Wang Y L, Jiang X C, Xia Y N. A solution-phase,
precursor route to poly-crystalline SnO2 nanowires
that can be used for gas sensing under ambient
conditions. J. Am. Chem Soc. 125 (2003) 16176.
[6] Zhang Y, Kolmakov A, Lilach Y and Moskovits
M, J. Phys. Chem. B,109 ( 2005)1923.
[7] C. P. Nicholas and T. J. Marks, Nano Lett., 2004,
4, 1557.
[8] A. Tischner, T. Maier, C. Stepper and A. Kock,
Sens. Actuators, B, 134 (2008) 796.
[9] W. Wei, et al., SnO2 hollow nanospheres
assembled by single layer nanocrystals as anode
material for high performance Li ion batteries, Chin.
Chem. Lett. 26 (2015) 124.
[10] Jian-Ping Ge, Jin Wang, Hao-Xu Zhang, Xun
Wang, Qing Peng, Ya-Dong Li, High ethanol
sensitive SnO2 microspheres, Sensors and Actuators
B 113 (2006) 937.
[11] Jiarui H, Liyou W, Gu C, Zhai M and Liu J,
Preparation of hollow porous Co-doped SnO2
microcubes and their enhanced gas sensing property,
Cryst Eng Comm, 15 ( 2013) 7515.
[12] Huang J, Xu X, Gu C, Yao S, Sun Y and Liu J,
Large-scale selective preparation of porous SnO2 3D
architectures and their gas-sensing property, Cryst
Eng Comm, 14 ( 2012), 3283.
[13] Wei W, Gao S , Yang Z , Wu Y, Chen C, Guo L
and Li J, Porous SnO2 nanocubes with controllable
pore volume and their Li storage performance, RSC
Adv., 4 (2014) 13250
Acknowledgement
The authors thank MVJCE, management and
VGST, Grant in aid scheme, Government of
Karnataka, for financial support.
19 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
I. Benjamin
A PLANAR UWB ANTENNA WITH NOTCHED
BANDS FOR WiMAX AND WLAN APPLICATIONS
I. Benjamin
Dept. of ECE MVJCE, Bangalore
Abstract— A planar UWB antenna with
notching at two various frequency ranges is
designed and analyzed. This antenna consists
of a radiating patch and a partial ground
plane. The dual notching characteristics in
the antenna are brought about by the
inclusion of a T-shaped stub in the square
patch and a couple of U-shaped parasitic
strips along the feedline. This design works in
the well in the 3.1-10.6 GHz with the VSWR
< 2 and band notching at 3.26-3.9 GHz
(WiMAX) and 5.16-5.4 GHz (LOWER
WLAN). Hence this antenna will serve a good
candidate for various UWB applications.
Index Terms—Planar antenna, ultrawide-
band (UWB) antenna, dual notching.
I. INTRODUCTION
IN RECENT p a s t , the need for
antennas that work in various multiband
applications in the latest wireless
communication systems have interested
many researches in the ultrawideband (UWB)
systems. The range of operation of UWB
antenna is 3.1-10.6 GHz and it has significant
advantages such as low cost, low spectral
power density, high precision ranging, low
complexity, resistant to jamming and
multipath, works well for short range high
speed wireless communication purposes etc.
[1].
There are many number of antennas
with notched band property have been
introduced, and various methods have
been proposed to obtain the desired
characteristics. The widely used techniques
are bring about slots on the patch or on the
ground plane in shapes such as H-shaped
slot [2], U-shaped slot [3], C-shaped slot
[4], etc. Making use of parasitic strips [5]
near the radiation elements or the ground
plane is another method to form notched
bands. So far, most of the before models were
intended to bring about single-notched-band
design and there have been few works on the
dual notched band designs. Dual-notched-
bands antennas have been recently reported
[6]–[8]. In these models, by inserting the
proper slits in the interior of the radiation
element and the ground plane, two rejected
bands have been obtained.
Most of these before mentioned models
have the same dis-advantage of poor voltage
standing wave ratio (VSWR) of the dual
notched bands. In this letter, a novel UWB
planar antenna with dual notched bands a t
t h e W i M A X an d l o w er W LA N
b an d s is proposed. A T-shaped stub in the
radiation patch and two U-shaped stubs
beside the feeding line are used to realize
dual-band-notch characteristic.
20 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
I. Benjamin
Fig. 1. Configuration and parameters of the UWB
antenna (unit: millimeters).
There are designs which use two T-shaped
stubs to achieve a notched band [9], and in
this design two U-shaped stubs along sides
of the feeding line are first used in the
UWB antenna to achieve a notched band.
The parametrical analyses of these filtering
structures are carried out. An antenna
prototype is designed and fabricated to
demonstrate the proposed strategy. The
proposed antenna structure is designed
using the CST Microwave Studio and
simulation results are obtained. The
simulation indicates dual bands rejection
with central frequencies of 3.6 and 5.3
GHz respectively, and significant notched
band characteristics.
II. ANTENNA DESIGN AND
RESULTS A.UWB Monopole Antenna
Fig. 1 shows the design specifications of a
UWB monopole antenna. The antenna is
fabricated on FR-4 substrate with dielectric
constant of 4.3 and i ts thickness is taken as
0.8 mm. The radiating square patch and
feeding line are printed on the top side of
the substrate and the partial ground plane on
the bottom side. The width of the microstrip
feedline is taken to be 1.6 mm to obtain a
characteristic impedance of 50. The thickness
of the annealed copper material for the
conducting part is 0.018mm. The optimization
is carried out and the final design
specifications of the various parameters are
listed out as follows: a = 2mm, b = 2mm, f =
13.5mm, s = 14.5mm, l = 32mm, w = 26mm,
m = 14mm, n =13mm.
In the presented design, an equivalent
dipole antenna is obtained between the top
monopole antenna and the bottom partial
ground plane [9]. Thus the characteristic
impedance of the antenna is affected by the
current distribution on the design. By cutting
the two notches of suitable dimensions at the
two lower corners of the patch, it is the
same with [10]
Fig. 2. VSWR plot of the proposed antenna without notched bands.
that the impedance bandwidth can be
improved to a considerable extent. This
phenomenon occurs because the two notches
affect the electromagnetic coupling between
the rectangular r a d i a t i n g patch and the
ground plane is affected by the two notches
which cause the improvement in the
impedance bandwidth.
The distance between the rectangular
21 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
I. Benjamin
radiation patch and ground plane is taken to
be 1mm, which is also a significant
parameter to control the impedance
bandwidth. The patch and the ground plane
form an equivalent dipole antenna. The
ground plane is a partial plane. The proposed
antenna can obtain high gain at low and high
frequency with partial ground plane.
B. UWB Monopole Antenna with Two
Notched Bands
To obtain dual notched bands, a T-shaped
stub on the rectangular radiating patch and a
pair of U-shaped stubs along sides the
feeding line are implemented to generate
notched bands at the desired central
frequencies of 3.6 and 5.3 GHz, respectively.
The configuration is shown in Fig. 2.
Fig. 3. Configuration and parameters of the UWB antenna with dual notched bands.
We may note that the currents will be
mainly distributed around the filter
structures and will be guided in opposite
directions between the interior and exterior
edge. Thus increased attenuation occurs
near the resonant frequency because of the
resultant radiation fields which cancels
each other and this phenomenon results in
the notched bands.
In order to do a detailed study on the
design of this antenna, some parametric
investigation and analysis is done to
optimize and get the inference of the
variations in the results. The T1, T2, U1
and U2 are the vital parameters which
determine the characteristics and operations
of the notched bands. Changing these
parametric values changes the position or
shifts the central frequency of the notch
bands to either higher or lower values.
Fig. 4. VSWR plot of the proposed antenna with T-shaped stub
Fig. 5. VSWR plot of the proposed antenna
with U-shaped parasitic strips.
22 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
I. Benjamin
The notch for the first coming WiMAX
band is significantly controlled by the T-
shaped stubs in the rectangular radiating
patch. The optimized values for the T1 and T2
are obtained as 6mm and 7.5mm respectively.
It was found that increasing T1 value shifted
the central notch frequency towards lower
values and decreasing its value shifted the
central notch frequency towards higher
frequency value. Similarly when increasing
the T2 value the centre notch frequency
shifted towards lower values and decreasing
the T2 value shifted the centre notch
frequency value towards higher frequency
values. Optimization of these values is
obtained by varying these values.
The parameters U1 and U2 significantly
controls the lower WLAN notched band. The
optimized values for the U1 and U2 are
obtained to be 7mm and 2.6mm. Increasing the
U1 and U2 value shifts the centre frequency
towards lower values of frequency and
increasing these parameters shifts the centre
frequency towards the higher values of the
frequency. The final design parameter
specifications are as follows: T1 = 6mm, T2 =
7mm, U1 = 7mm, U2 = 2.6mm, Ut = 0.2mm
(Thickness of U-shaped strips), Tt = 0.8mm
(Thickness of T-stub), h = 9.9mm, Uh = 6mm
(distance of the U-shaped strips from the
bottom), hh = 2mm.
Fig. 6. VSWR plot with dual notched bands in case of final integrated design.
The Fig. 4, 5 and 6 shows the VSWR plot
when only T-stubs, only U-shaped parasitic
strips and when both the T-stub and U-shaped
strips are present.
From results obtained through the
simulation, it is clear that the antenna
characteristics are highly dependent on the
thickness of the substrate material and it
affects the width of the feed line in order to
obtain desired bandwidth impedance of 50Ω.
The proposed metal for the patch and ground
planes is annealed copper and its thickness
during fabrication will be 0.018mm. The
fabricated antenna has the frequency range
from 2.7 to 9.6 GHz with VSWR < 2,
covering the entire UWB band with dual
notched band of 3.2–3.9 GHz and 5.14–5.45
GHz, respectively.
In addition, the comparisons for
several different dual-notched-band UWB
antennas are studied. Compared to [6] and
[8], the proposed UWB antenna with dual
notched bands has better band-notch
characteristics and when compared to that
of the [11] the cost of the substrate is
considerably low and hence it commercially
efficient. And in it the band notch is for the
entire 5-6 GHz of bandwidth which causes
loss of data in between the upper and lower
WLAN frequency bands. But this proposed
design notches only the lower WLAN
bandwidth.
III. CONCLUSION
In this paper, a monopole printed antenna is
presented analyzed and designed for
operation in the UWB bandwidth range.
Adjusting the gap between the radiation
patch and partial ground plane, a wide
impedance bandwidth is obtained. Moreover
23 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
I. Benjamin
this antenna is proposed to be fabricated on
FR-4 substrate and hence the design
parameters have been reconfigured
accordingly. Hence this antenna is much cost
efficient than those which are present earlier
as they were fabricated in Rogers 4003
substrates [11] which is much costlier than
FR-4 substrate. Thus the total fabrication cost
of the design increases considerably.
By implementing a T-shaped stub in the
rectangular radiation patch and a pair of U-
shaped parasitic strip elements besides the
feed line, dual stop bands for applications
of WiMAX and lower WLAN are
achieved. The interference of the WiMAX
and the lower WLAN applications in the
desired UWB range for applications using
this antenna is appreciatively reduced and
performance is desirably obtained.
The radiation pattern of this antenna
shows good omni-directional performance
throughout the UWB frequency range and
good gain in the UWB band is obtained.
Accordingly, the proposed antenna is
expected to be a good candidate in various
UWB systems.
REFERENCES [1] I. Oppermann, M. Hamalainen, and J. Iinatti,
UWB Theory and Appli- cations. New York: Wiley, 2004, ch. 1, pp. 3–4.
[2] S. R. Branch, “Band-notched elliptical slot
UWB microstrip antenna with elliptical stub filled by the H-shaped slot,” J. Electromagn. Waves Appl., vol. 22, pp. 1993–2002, 2008. [3] Y. J. Cho, K. H. Kim, D. H. Choi, S. S. Lee, and
S. O. Park, “A minia- ture UWB planar monopole antenna with 5-GHz band-rejection filter and the time-domain characteristics,” IEEE Trans. Antennas Propag., vol. 54, no. 5, pp. 1453–1460, May 2006. [4] Y. C. Lin and K. J. Hung, “Compact ultra-
wideband rectangular aperture antenna and band-notched designs,” IEEE Trans Antennas Propag., vol. 54, no. 11, pp. 3075–3081, Nov. 2006. [5] K. H. Kim and S. O. Park, “Analysis of the small
band-rejected antenna with the parasitic strip for UWB,” IEEE Trans. Antennas Propag., vol. 54, no. 6, pp. 1688–1692, Jun. 2006. [6] J. Liu, S. Gong, Y. Xu, X. Zhang, C. Feng, and N.
Qi, “Compact printed ultra-wideband monopole antenna with dual band-notched characteris- tics,” Electron. Lett., vol. 44, no. 12, pp. 710–711, Jun. 2008. [7] M. Abdollahvand, G. Dadashzadeh, and D.
Mostafa, “Compact dual band-notched printed monopole antenna for UWB application,” IEEE Antennas Wireless Propag, Lett., vol. 9, pp. 1148–1151, 2010. [8] Q. X. Chu and Y. Y. Yang, “A compact
ultrawideband antenna 3.4/5.5 GHz dual band-notched characteristics,” IEEE Trans. Antennas Propag., vol. 56, no. 12, pp. 3637–3644, Dec. 2008. [9] C. Y. Hong, C. W. Ling, I. Y. Tarn, and S. J.
Chung, “Design of a planar ultra-wideband antenna with a new band-notch structure,” IEEE Trans. Antennas Propag., vol. 55, no. 12, pp. 3391–3396, Dec. 2007. [10] J. Jung, W. Choi, and J. Choi, “A small
wideband microstrip-fed monopole antenna,” IEEE Microw, Wireless Compon. Lett., vol. 15, no. 10, pp. 703–705, Oct. 2005. [11] Wen Jiang and Wenquan Che, ”A Novel UWB
Antenna With Dual No-tched Bands for WiMAX and
WLAN Applications”IEEE Antennas and Wireless
Propagation Letters, vol.11, pp. 1536-1125, 2012.
24 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr.Manoranjan Kumar, Ms. Divya.P.K
SMART WEARABLE OBSTETRIC ASSISTANT
AND REMINDER
Mr.Manoranjan Kumar Ms. Divya.P.K
Department of ME Department of ME
MVJCE ,Bangalore MVJCE,Bangalore
Abstract—The purpose of this project is to
design a smart system that uses noninvasive
techniques in recording the frequency and
duration of labor pain during pregnancy so
as to assist the expectant person in
determining the time when she must start
from home to go to the hospital and for
how long the doctor can safely delay the
delivery after arriving at the hospital.
There are various other difficulties faced by
the women during pregnancy. Here we
wish to outline few of these difficulties and
through this project we would try to suggest
few remedies for them. The device will be
synchronized with the concerned doctors
system using the concept of Tele-medicine
and thus it will provide the user with a
friendly interface through which the
exchange of important information can
occur between the user and the doctor at
several instances during the gestation
period. The device will also measure the
pulse rate and the temperature of the user’s
body and regularly update the information
to the doctor’s system which can be
analyzed for any abnormalities. We also
have the GSM modem embedded in the
system that can send various indications
such as emergency, panic, slip/fall etc., in
the form of a text message onto the
expectant women husband or on any other
family member’s number as fed in the
system so that they can aid her in case of
need. It will also aid in calling for an
ambulance service in case of emergency.
With the help of the GPS antenna used in
the device we can also be able to track the
location of the user on the Google maps
application. Apart from being used by the
women during the pregnancy, this device
can be used by old-age people for similar
problems such as emergency, panic, fall,
temperature and pulse rate measurement,
etc.
Keywords- Pregnancy, Tele-medicine,
gestation period, GSM modem, GPS
antenna, Google maps application.
I. INTRODUCTION
In the past few decades we have witnessed a
rapid growth in the field of science and
technology, and evidently there has been a
tremendous advancement in the Health Care
Systems. Technology now provides us with
various innovative methodologies to carry
out the most complex operations in a simple
and sophisticated manner. Few such
methodologies in the field of health-care
include wearable technology like Google
glass, Optogenetics, Digestible sensors,
Tele-medicine, Intra-operative surgeries, etc.
Due to busy lifestyle and different
sort of involvements in today’s world, it is
difficult to commune frequently from one
place to another. Pregnancy is an important
phase in a woman’s life. During these 9
months gestation period, she may have to get
routinely checked up by the doctor. This
check up might be as often as every 15 days.
25 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr.Manoranjan Kumar, Ms. Divya.P.K
Considering the difficulties that might be
faced by a woman in taking an appointment
from the doctor and in travelling all the way
to hospital, we try to design a smart system,
that will avoid unnecessary travelling of the
pregnant woman to the hospital, by using the
concept of Tele-medicine.
Tele-medicine is defined as the
delivery and sharing of medical information
of patient over a distance using
communication over networks. Thus, using
this concept the distance barrier between the
doctor and the patient can be reduced.
Existing Tele-medicine systems only
exchange the information in the real time
with fixed location, or with a bounded
location or pre-configured location. Using
portable devices, Tele-medicine service is
feasible even on the move.
We propose a wearable mechanism
that would be preferable when the user is
actively working or when he/she is on the
move. The system is designed using less
expensive and user friendly components, as
will be discussed in the following sections.
II. BLOCK DIAGRAM
Block diagram is as shown in the above
figure. The device is intended to perform
different kind of functions. It involves a
number of hardware parts which are
operated in a sophisticated manner using the
software’s developed for the respective
purposes.
The hardware and the software parts can be
listed as follows:
Hardware Part:
PIC 18 Microcontroller
GPS Modem
GPS Antenna
GSM Modem
1:2 MUX
Antenna
GPS
MODEM
Antenna
GSM
MODEM
Multiplexing
Logic
Keypad for Distress
switch Pressing
1. Pain
2. Pain Intensity
3. Emergency
4. Cancel
Microchip’s
8 Bit Micro-
Controller
PIC18
LCD
Pulse
Counter
Accelerometer
2 Axis
ADC 0809 National
Semiconductor
Temperature
LM35
Buzzer
PC with
VB6
with
API
Runnin
g
Antenn
a
GSM
MODE
M
26 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr.Manoranjan Kumar, Ms. Divya.P.K
Software Part:
PIC 18 Embedded C coding for
MPLAB
Visual Basic6 for the GUI on the
front end of the system.
Google Map API connectivity.
We are making use of a PIC18
microcontroller. It has various advantages
over the low cost 8051 microcontroller and
the most expensive Raspberry Pi. Few
advantages can be listed out as follows,
It is inexpensive,
Has built in oscillators,
Has a small instruction set to learn,
Allows for wide range of interfaces
including SPI, USB, USART, A/D,
etc,
Availability of processors
in DIL package makes them easy to
handle for hobby use.
The pin diagram and the block diagram of
the PIC 18 microcontroller is as shown in the
following figures,
Figure 1: PIC Microcontroller
Figure 2: Pin diagram of PIC 18 Microcontroller
Figure 3: Block diagram of PIC 18 Microcontroller
III. WORKING
The following are the components and their
use in our design:
1. The accelerometer is used for fall
detection. This device basically
measures the deviation angle from
the free fall direction. If the direction
of the axis of the device is
perpendicular to the ground, the
deviation will be 0. Fall can be
detected whenever there is a
deviation measured.
2. LM35 temperature sensor is used to
measure the temperature of the user’s
body. This will be an analog input
which will be converted into digital
information using the ADC and
further transferred to the doctor’s
system through GSM.
3. Pulse counter is used to check for any
deviation in the heart rate which is
resulted from any abnormality in the
body.
4. LCD is used to display the text
messages sent from the doctor. This
can also be used to indicate the
medicines prescribed by the doctor,
any changes to be done in the
dosages, alarm about the exercise
timings, etc.
27 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr.Manoranjan Kumar, Ms. Divya.P.K
5. There can be a BUZZER which can
indicate the people around the user in
case the patient is in a panicky situation.
6. The GPS modem helps in locating the
user on the map. If the user is in a trouble
and is not in a condition to contact any
family member, in such cases, on just
one key press the pre stored message
along with the location of the user is sent
to one or more of her family members.
7. The GSM modem is used to
communicate with the dear ones over the
network of their phones. Any messages
to be sent by the user, in case of need,
panic or any emergency can be sent over
by using the GSM modem. This also aids
in calling an ambulance in emergency
situation.
IV. APPLICATIONS
1. Periodic recording and transfer of the
users information:
As indicated by the block diagram, the
device will include a pulse counter and a
temperature sensor.
These devices will measure the pulse rate
and the temperature respectively, of the
user. This information is then sent on to
the doctor’s system by employing the
Tele-medicine concepts.
2. Reminder about the medications:
The device will also have a LCD display,
thus the doctor can transfer information,
such as the medicines to be take, dosage
of the medicines, time of consumption of
that medicine, etc. This feature is of great
importance when the patient has to be
prescribed a different medicine after a
certain amount of time. For example,
during the first few months of pregnancy
folic acid dosage is prescribed, later this
medicine is changed to a different one.
3. Important messages from the doctor:
Many a times it becomes urgent to inform
the pregnant woman about the
appointments with the doctor, and
sometimes about the tests to be
conducted. At such times the doctor can
immediately send an SMS to the mother.
Since it is a wearable device the message
is always flashed on the on-board LCD
screen and goes away only when the
“Message Seen” Button is pressed.
4. Reminder about the exercises:
During the Pregnancy the mother has to take
care of her body so that she is fit and
ready for the final day. Further the body
generates a lot of aches and pains during
the term of pregnancy. To ease all these
pains the mother has to do a lot of yoga
and stretching exercises which needs to
reminded to be done at predefined
timings. The system can be used to
remind the same.
5. Indicating when the Pregnant woman
needs to start moving to the hospital:
As we all know, timing of labor pain is of
great importance in indicating the proper
time of delivery and is relied upon to a
great extent in determining when the
pregnant woman should start moving to
the hospital and for how long the doctor
may safely delay the delivery after
arriving at the hospital . By accurately
determining the frequency and duration
of the labor pains the expectant mother
can be prevented from admitting in a
hospital too much in advance based on
some false indications. The timing of
these pains is also important in the labor
room, for various reasons.
The standard rule in the hospitals
seems to be that, the expectant mother
tells the nurse when she experiences a
28 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr.Manoranjan Kumar, Ms. Divya.P.K
pain and the nurse makes a written note
of the time of occurrence of the recurrent
pains. In this manner the progressive
shortening of the period between pains is
ascertained. If the doctor is not present at
the hospital at that time then he will be
informed that the delivery is approaching
and needs his attention. But, the nurse is
not always at hand when the pain recurs
and sometimes due to some disturbance,
the pattern of frequency of the pains is
interrupted and it may become
insignificant to some extent. An
experienced nurse can detect the periodic
contraction of the uterus by placing her
hand over the abdomen of the patient, but
this method requires that the nurse be
present by the side of the patient at all the
times. Due to these difficulties we
propose the use of the contraction timer
calculator, which basically consist of a
indicative scale with switches, that will
act as a programmable stop watch and
will need the patients input to note the
time between the contractions and the
intensity of the pain. Depending on this
measurement, the device will indicate if
it is the time to move on to the hospital.
6. Any distress to be informed to the nearby
people:
Any kind of breathlessness, heaviness in the
stomach might also start cramps and
might pose difficulty to call. In such
cases a simple switch press might be able
to start a Buzzer.
7. Automatic ambulance to be called in case
of emergency:
In case of acute emergencies, the press of a
button may enable the message or call to
be made for requesting the service of
ambulance at the present location of the
user.
8. Automatic SMS to be sent with location
in case of emergency:
Detection of a fall as will be defined later or
on a press of a switch or the body
temperature going above the normal or
pulse count irregularities will all initiate
an SOS SMS which can be used to call
and alert an Ambulance. The SMS may
also be sent to any of the family
members of the user indicating that the
user is in some sort of emergency.
9. Fall detection in case of a slip.
Any accidental slips of mother can cause
major accidents, which may even lead to
involuntarily termination of pregnancy;
sometimes it can even be fatal for mother
and the child. In such cases, using an
Accelerometer, the tilt of the body can be
detected which can indeed indicate the
fall. Immediate attention may save the
mother and the child from the dangers.
10. Mapping the location of the user on the
map with relevant details.
The system will employ another GSM
MODEM connected to the Google Map
where the exact co-ordinates of the
mother can be located. The information
from the GPS will then be transferred in
the NMEA format to the Base station
(which might be at Home/ Police Station/
Hospital etc) (some predefined Numbers)
so that the information can then be
mapped on the Google Earth and the
approximate location can directly be
obtained on a real time Map. For this we
will be using the Google Map API on
which we will be able to plot the real
time location of the user.
V. EXPERIMENTATION AND
TESTING
1. The model is tested by using a webcam
of 5MP resolution.
29 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr.Manoranjan Kumar, Ms. Divya.P.K
2. MATLAB proves to be a very good tool
in extracting the features and in
classifying the emotions. The
development of the MATLAB code was
also easy when compared to the
development in any other image
processing software.
3. Capturing of the video and extraction of
the expression is found to be working
well. But, since it is designed to work in
real time, the model does not provide us
with 100% accuracy.
4. The device was also experimented with
the pre recorded video as the input. Even
in this case the same procedure was
carried out for the extraction of emotion,
classification and transmission. When
tested with numerous trails, the
classification is found to be nearly 100%
accurate.
5. The transmission of the serial codes and
the operations over the home automation
model does work to a very accurate level,
once the correct expression is detected.
6. The current model that has been
developed is made to play one song for
every emotion. This song is stored into
the database, by the user. In case of
android profiling, any one song on the
android device can be chosen to be
played, as required by the user.
7. The autism rehabilitation application
works well in training the patients. The
training accuracy is dependent on the
subject, i.e. the user. The level of
understanding of the user and the stage of
this abnormality will also affect the
efficiency of the application. Thus, the
efficiency of working of the application
cannot be determined quantitatively.
8. The drowsiness detection is also
subjective to various restrictions. The
plot will usually be wearing a Head gear.
This may cause interruption in capturing
the image of the pilot’s face. Once
captured, the processing of the image and
working of the alarm poses no much
complication.
Figure 3: Working model
VI. CONCLUSION The developed system helps a pregnant
woman in communicating with her
consulting doctor easily and effortlessly.
Unnecessary cost of staying over at the
hospital before the time that the delivery
is due can be avoided. It may help us to
prevent any adverse situations from
occurring in the course of pregnancy.
VII. REFERENCES [1] Dr. Conrad Zapanta , Kenneth Varner,
Android based tocodynamometer and fetal heart
rate monitor, Carnegie Mellon University press.
30 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr.Manoranjan Kumar, Ms. Divya.P.K
[2] Orlin Patric O Brien, Intrauterine muscle
activity measuring system, United States Patents.
[3] Yusimi Sobrino Bonilla,T Caring for
Laboring Women with Amyotrophic Lateral
Sclerosis: A case report, The American
Journal of Maternal/Child Nursing(2004)
[4] Simpson KR, The context and clinical
evidence for common nursing practices during
labor, asrn.org(2005).
[5] Mazidi, Pic Microcontroller and Embedded
Systems: Using Assembly And C For Pic 18,
Pearson education, 2009
[6] Ahmed Al-Rabbany, Introduction to GPS:
The Global Positioning System, Artech House,
2002.
[7] Asha Mehrotra, GSM system engineering,
Artech House, 1997.
31 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mrs. Aruna Dore
STUDY OF COLOR AND GRAY IMAGE
DENOISING USING DIFFERENT FILTER
TECHNIQUESMrs. Aruna Dore
Department of Telecommunication Engineering
MVJ college of Engineering, Bangalore, India
Email id: [email protected]
Abstract— Image is a collection of
information and the occurrence of noises
in the image causes degradation in the
quality of the images. So the information
associated with an image tends to loss or
damage. It should be important to restore
the image from noises for acquiring
maximum information from images. As a
remedy, the quality and the information
from the noised image can be retrieved
using different types of filters such as
Gaussian Filter, Mean Filter, Median
Filter etc. In this paper, how different
types of noise (Gaussian, salt and pepper
noise) will affect the quality of the images
and the information in it is studied and
image de-noising is performed for different
noise by Mean filter, Median filter and
Wiener filter . Further results have been
compared for all noises using MATALAB
Software.
Keywords—Image Processing, Gaussian
filter, Mean Filter, Median filter, noise
I. INTRODUCTION
Image denoising is one of the most
important concepts in digital image
processing. It is widely used in various
image related applications like, Magnetic
Resonance Imaging [MRI] analysis, 3-D
object detection etc. The digital images
contain some degree of noise. The goal of
image denoising is to restore the details of
an image by removing unwanted noise.
Noise may be classified as substitutive noise
(impulsive noise: e.g., salt and pepper noise,
random valued impulse noise, etc.), additive
noise (e.g., additive white Gaussian noise)
and multiplicative noise (e.g. speckle noise).
In this work different types of noise such as
salt & pepper, Gaussian noise, poisson noise
& speckle noise are considered. There are
different methods of removing noise from
original image. In common there are two
types of image denoising model, linear
model and nonlinear model. Linear model
[2] are being considered for image
denoising, the main benefits of using linear
noise removing models is the speed and the
limitations of the linear models is the models
are not able to preserve edges of the images
in an efficient manner. Non-linear models
[3] can preserve edges in a much better way
than linear models but very slow. The main
aim of noise removal scheme is to suppress
noise as well as to preserve details and edges
of image as much as possible. Figure [1]
shows the basic model for denoising of
image.
In this model first image is taken and some
noise is added to image to make it as noisy
image and then noisy image is decomposed
by applying different filter to decomposed
image to remove noise from noisy image
and at last denoised image is obtained. The
performance parameter between the noisy
image and denoised image can be calculated
in terms of Peak Signal Noise –Ratio
(PSNR) and Root Mean Square Error
(RMSE).
32 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mrs. Aruna Dore
Figure 1: Basic model for Denoising Image
II. DIFFERENT TYPES OF FILTERS
A. Median Filter
Median filtering [1] is a nonlinear method used to remove noise from images. Widely used method to preserve edges. It is particularly effective at removing salt and pepper noise. Median filter works by moving through the image pixel by pixel, replacing each value with the median value of neighbouring pixels. The pixel is calculated by first sorting all the pixel values from the pattern of neighbours into numerical order, and then replacing the pixel being considered with median pixel value. Median filter is better able to remove noise without reducing the sharpness of the image.
B. Mean Filter
Mean filter is type linear filtering scheme.
Mean filter is also known as averaging filter
[1]. The Mean Filter applies mask over each
pixel in the signal. Each of the components
of the pixels comes under the mask are being
averaged together to form a single pixel
that‟s why the filter is otherwise known as
average filter. Edge preserving criteria is
poor in mean filter. Mean filter is defined by
Mean Filter
…………….. (1)
Where (x1 ….. xN) is image pixel range.
Mean filter is useful for removing grain
noise from the photography image. As each
pixel gets summed the average of the pixels
in its neighborhood is found out, local
variations caused by grain noise are reduced
considerably by replacing it with average
value.
C. Wiener Filter
The main aim of the Wiener filter is to filter
out the image that has been corrupted by
noise. Wiener filter is based on a statistical
approach. Desired frequency response can
be acquired using this filter. Approaches
followed by wiener filtering are of different
angle. For performing filtering operation it is
must to have knowledge of the spectral
properties of the original signal and the
noise, in achieving the criteria one can get
the LTI filter whose output will be as close
as original signal as possible. Wiener filters
[1] possess characterized by the following:
a. Assumption: signal and (additive) noise
are stationary linear random processes with
known spectral characteristics.
b. Requirement: the filter must be causal
where this requirement is failed it resulting
in a non-causal solution Periodic noise can
be effectively removed by correcting the
amplitude spectrum components altered by
the noise, and two frequency filtering
methods are currently available, i.e., Wiener
filtering and notch filtering. However, a
Wiener filter requires an accurate noise
model, which may be difficult to obtain in
various practical cases. In addition, a Wiener
filter is also complicated in computation.
D. Gaussian Filter
The Gaussian filtering scheme is based on
the peak detection. The peak detection is
based on the fact that peaks are to be
impulses. The key point is that this filter
corrects not only the spectral coefficient of
interest, but all the amplitude spectrum
coefficients within the filter window. Some
properties of Gaussian filter are [2]:
1. The weights give higher significance to
pixels near the edge (reduces edge blurring).
2. They are linear low pass filters.
3. Computationally efficient (large filters are
implemented using small 1D filters).
4. Rotationally symmetric (perform the same
in all directions).
5. The degree of smoothing is controlled by
σ (larger σ for more intensive smoothing).
III. IMAGE NOISE
Noise in images is caused by the random
fluctuations in brightness or color
information. Noise represents unwanted
information which degrades the image
quality. Noise is defined as a process which
affects the acquired image quality that is
33 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mrs. Aruna Dore
being not a part of the original image
content. Digital image noise may occur due
to various sources. During acquisition
process, digital images convert optical
signals into electrical one and then to digital
signals and are one process by which the
noise is introduced in digital images. Due to
natural phenomena at conversion process
each stage experiences a fluctuation that
adds a random value to the intensity of a
pixel in a resulting image. In general image
noise is regarded as an undesirable by-
product of image capture. The types of
Noise [2] are following:-
• Amplifier noise (Gaussian noise)
• Salt-and-pepper noise
• Shot noise (Poisson noise) • Speckle noise
A. Gaussian Noise
Gaussian noise is statistical in nature. Its
probability density function equal to that of
normal distribution, which is otherwise
called as Gaussian distribution. In this type
of noise, values of that the noise are being
Gaussian-distributed. A special case of
Gaussian noise is white Gaussian noise, in
which the values always are statistically
independent. For application purpose,
Gaussian noise is also used as additive white
noise [6] to produce additive white Gaussian
noise. Gaussian noise is commonly defined
as the noise with a Gaussian amplitude
distribution, which states that nothing the
correlation of the noise in time or the
spectral density of noise. Gaussian noise is
otherwise said as white noise which
describes the correlation of noise. Gaussian
noise is sometimes equated to be of white
Gaussian noise, but it may not necessarily
the case.
B. Salt and Pepper Noise
Salt & Pepper noise mode [4], there is only
two possible values „a‟ and „b‟. The
probability of getting each of them is less
than 0.1 (else, the noise would greatly
dominate the image). For 8 bit/pixel image,
the intensity value for pepper noise typically
found nearer to 0 and for salt noise it is near
to 255. Salt and pepper noise is a
generalized form of noise typically seen in
images. In image criteria the noise itself
represents as randomly occurring white and
black pixels. An effective noise reduction
algorithm for this type of noise involves the
usage of a median filter, morphological
filter. Salt and pepper noise occurs in images
under situations where quick transients, such
as faulty switching take place. This type of
noise can be caused by malfunctioning of
analog-to-digital converter in cameras, bit
errors in transmission, etc.
IV. SIMULATION RESULTS
Different Image Noise Characteristics for Color and Gray Image:
(a) Original Color Image
(b) Image affected by Salt and Pepper noise
34 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mrs. Aruna Dore
(c) Image affected by Gaussian noise
(d) Original Gray Image
(e) Image affected by Salt and Pepper noise
(f) Image affected by Gaussian noise
Figure 2: Image affected by different types of noise
Figure 2 (a) represents the original image
being taken for experimental purpose. Figure
2 (b) represents the image being affected by
Salt and Pepper noise for color image.
Figure 2(c) represents the image affected by
Gaussian noise for color image. Figure 2 (e)
represents the image being affected by Salt
and Pepper noise for gray image. Figure 2
(f) represents the image being affected by
Gaussian noise for gray image. The above
results shows Noise in images causes
degradation in image quality. So the
information associated with the images is
damaged and it is must to restore the image
from noises for acquiring maximum
information from images. As a remedy, the
quality and the information from the noised
image can be retrieved using different types
of filters.
(a) Salt and Pepper noised image is filtered
by Wiener Filter
(c) Gaussian noised image is filtered
by Wiener Filter
35 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mrs. Aruna Dore
(e) Salt and Pepper noised image is filtered
by Mean Filter
(b) Salt and Pepper noised image is filtered
by Median Filter
(d) Gaussian noised image is filtered
by Median Filter
(f) Salt and Pepper noised image is filtered
by Median Filter
(g) Salt and Pepper noised image is filtered
by Wiener Filter
(h) Gaussian noised image is filtered
by Mean Filter
(i) Gaussian noised image is filtered
by Median Filter
(j) Gaussian noised image is filtered
by Wiener Filter
36 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mrs. Aruna Dore
Figure 3:Denoised Image by different types of Filters
IV. CONCLUSION & FUTUERE WORK
In this paper two types of noises (Salt and
Pepper, Gaussian) had been added to the
original image and observed that all noise
causes degradation in the image quality
which results in loss of information. The
denoising of degraded image is performed
using Wiener, Mean and Median filter. From
the simulation results its confirmed that
Median filter works well for Salt and Pepper
noise than Mean and Wiener filter whereas
Wiener filter works well for removing
Gaussian compared to that of Mean and
Median filter.
In Future this test can be performed on
different other noises and performance
parameter between the noisy image and
denoised image can be calculated in terms of
PSNR and RMSE.
REFERENCES
[1] Rafael c. Gonzalez and Richard E. Woods,
“Digital Image Processing,”. third edition.Prentice-Hall ,Englewood,Cliffs,NJ.2001.
[2] Charles Boncelet, “Image Noise Models” in Alan C.Bovik, Handbook of Image and Video Processing, 2005.
[3] Astola, J., Kuosmanen, P., “Fundamentals of Non-linear Digital Filtering”, CRC Press, NewYork, Boca Raton, 1997.
[4] Changhong Wang, Taoyi Chen, and Zhenshen Qu, “A novel improved median filter for salt-and-pepper noise from highly corrupted images”, IEEE 2010, pp. 718-722.
[5] Shu-tao LI, Yao-nan WANG, “Non-Linear Adaptive Removal of Salt and Pepper Noise from Images” , Journal of Images and Graphics, Vol. 5(A), No. 12, Dec 2000.
[6] JianhuaLuo, Yuemin Zhu, and Isabelle E. Magnin, “Denoising byAveraging Reconstructed Images: Application to MagneticResonance Images”, IEEE transactions on biomedical engineering,vol. 56, pp 666 - 674 , March 2009.
[7] KrishnanNallaperumal,JustinVarghese,S.Saudia,K.Krishnaveni,Sri.S.Ramasamy,Santhosh.P.Mathew,P.Kumar “An efficient Switching Median Filter for Salt & Pepper Impulse Noise Reduction”, IEEE 2006, pp. 160-166.
37 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr. Prashant S Ghulappanavar , Ms. Kavya B M
A SURVEY ON HUMAN SENSING
APPLICATIONS USING UWB RADAR
Mr. Prashant S Ghulappanavar Ms. Kavya B M
MVJCE Bangalore, India VVCE Mysore, India
[email protected] [email protected]
Abstract— Ultra wideband (UWB)
technology has become a very popular topic
in industry and academia. UWB signals have
an excellent spatial resolution and good
penetration into many materials which
makes them very interesting for radar
applications [04]. The paper [02] covers the
two important parameters related to the
“through the wall imagery” which include
quality and reliability. The smears and the
flaws in the walls may produce a blur image
or may shift the imaged target position. An
auto focusing technique based on higher
order statistics corrects errors under
unknown walls. The paper [01] describes the
use of the finite difference time domain
method to investigate the capabilities and
limitations in the use of radar system to
determine the human model target inside the
realistic room.
Keywords- UWB, “through the wall
imagery”, back projection, Auto focusing,
high-order statistics.
I. INTRODUCTION
The UWB radar system is used for scanning of the objects behind a wall. An electromagnetic wave is transmitted via antenna system, penetrates through the Wall, it is reflected by the investigated object. The UWB radar has been used in several applications which include military applications low altitude missile detection, minefield detection etc. The radio waves have inherent capability to penetrate and detect the target on the other side of the wall. A time pulse of 0.8 ns at a center frequency of about
1.1 GHz is used. The performance of the UWB radar is the examined by taking the 2 dimensional images of a room with the human body model included. This is done by considered by the data given by the monostatic scenarios radar scenarios where the responses are collected and processed by using by time domain back projection method.
II. ROOM AND UWB RADAR COMPUTER
MONITORING
The electromagnetic phenomenon involving the illumination of the realistic room environment by UWB radar is modeled using the FDTD method [01].
A. Room Geometry
The room used in the experiment is made up of brick walls, concrete floor, and wooden ceiling .the components in the room include water pipes, metallic electrical outlets, water conduits, metallic barred window. A computer aided design (CAD file) of the room is sketched using AutoCAD.
Figure 1. 3D view of the modeled room and its
components
38 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr. Prashant S Ghulappanavar , Ms. Kavya B M
The paper [01] specifies for the accurate electromagnetic interaction with the geometries of the room the physical parameters of the materials analyzed thoroughly. These physical parameters are the electrical conductivity and electrical permittivity. Table below lists the parameters at the center frequency fc = 1.1 GHz.
Material Conductivity Permittivity
Brick 0.001 s/m 4.44
Concrete 0.015 s/m 15
Wood 0 5
Glass 0 5
Plastic 0 5
Metal 58000000 -
Table 1. Parameters of materials in the modeled room
B. Radar Modeling
In the paper [01], mono-static configuration is used, where single Antenna element is used for transmitting and receiving the pulses. In case of mono-static configuration, prior knowledge of the object angle to the antenna plane is not necessary for determining distance of the object, this is suitable for determination of buried objects inside another material. Mono-static configuration is reduced in size, and suitable for antenna array.
C. UWB Excitation Pulse
To model the EM illumination of the modeled room and its contents with an UWB short pulse, the transmitter dipole antenna is fed by a 0.8 ns Gaussian pulse modulated by a 1.1 GHz sine wave below show the figure of time and frequency response of the UWB pulse Figure 2.
Figure 2. Time and frequency response of UWB
excitation pulse using simulation
III. HUMAN PHANTOM
MODEL
To include a human subject in modeling [01], a human phantom model is imported into the FDTD simulation space. Below Figure 3 shows the model geometry of the human body model standing inside the modeled room. The FDTD meshed geometry of the human body consists of twenty three tissue groups representing most of the anatomical human body organs and tissues. Then each of these twenty three material groups is assigned a material density (kg/m3), conductivity (s/m) and relative permittivity .these physical parameters are frequency dependent and their values are set for fc = 1.1 GHZ, the center frequency of the UWB pulse used.
Figure 3. Human model inside the room with the
radar setup dimensions and location in front of the room
39 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr. Prashant S Ghulappanavar , Ms. Kavya B M
IV. LIFE DETECTION SYSTEM
The paper [03] presents the life detection system. The main component is bi-static continuous wave (CW) radar consisting of a local oscillator which produces a sinusoidal signal of 10.45 GHz, a low noise amplifier, and a two patches array as transmitting antenna. The radar irradiates an electromagnetic wave and collects the reflected signal that contains the breathing and the heartbeat information coming from a human detected target. The backscattered signal is received by a two patches antenna, amplified and led to an I/Q detector. The orthogonal detector is mandatory because the ICA [06] requires a number of Observation points equal to the number of the original signals and we exploit I/Q signals as two independent sources of information. Then the output I/Q signals are given as input to a remote elaboration system by means of a low frequency wireless channel. As stated previously the amplitude and the phase of the received backscattered wave are modulated in accordance with the movement of breathing and heartbeat. The information associated to amplitude is generally Negligible [07] and only the phase variation is considered.
The signal at the receiving antenna can be
expressed considering the following relation.
(1)
Where ὼ0 is the angular frequency and v is
the propagation velocity of the radio waves, Ax, Aj are the amplitudes associated to life signals and rubble respectively. Rs(t) and Rj are the round trip distance of the survivor and rubble from the radar system. The second term describes the constant contributes due to the rubble and it can be easily removed with a simple filtering procedure while the first term contains information related to life-signals. The small movement of the survivor body caused by breathing and heartbeat can be seen as a fluctuation around a mean distance Rs and modeled at the output of the orthogonal phase
detector as ‘x (t) = (ὼ0 v (Rs + Ab cos(ὼbt) + Ah cos(ὼht))), where ὼb and ὼh are the frequencies due to the breathing and the heartbeat respectively. Ab, Ah are the amplitudes due to the movement of the chest and heart respectively.
The weak received backscattered field, which is a mixture of vital signals, noise and clutter contribute, is amplified down-converted with an orthogonal detector, and processed with an analog-to-digital converter. The I/Q signals at the output of the orthogonal detector are led to a remote elaboration unit by means of a low frequency transmission module. The received signals must be post-processed to separate the life signals from the noise and the clutters contribute. ICA algorithm has been chosen to accomplish this task. The ICA is a method for separating mixed data (such as MRI images [08], biomedical data [09], sounds, Telecommunication channels or signals into underlying informational components.
The ICA belongs to a class of methods called blind sources separation (BBS). The classical example is two people speak at the same time in a room. Two microphones, placed in different points inside the room collect a mixture of the two voice signals. From these two signal mixtures, ICA can recover the two original source signals. One of the most important facts about standard BSS methods like ICA is that the number of independent source of information (i.e., the receivers) must be greater than the number of overlapped source signals. For the problem at hands this implies that there must be at least two probes to detect the life signals and for this reason we use an orthogonal detector generating EI and EQ these two signal mixtures collected at the output of the orthogonal phase detector and sent to the remote elaboration system for the post-processing could be expressed
= (2)
40 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr. Prashant S Ghulappanavar , Ms. Kavya B M
Figure 4. Diagram of the life detection system.
where EI (t) = AI cos('x(t))+N(t) and EQ(t)
= AQ cos('x(t))+N(t) represents the noise contribution due to the clutter and other interfering sources. The terms a11, a12, a21, and a22, are parameters that depend from the phase shift. The two original signals N(t) and 'x(t) are assumed to be statistically independent at each time instant: for this reason it is possible to estimate the original signals processing the mixed signals EI (t), EQ(t) observed at the orthogonal detector.
Let us consider the following matricial representation
(3)
After estimating the coefficients matrix [A] and its inverse [A]¡1, it is possible to obtain the original signals as shown in the following equation
This goal is accomplished by using the ICA
algorithm. After the ICA application, the cleaned signals N(t) and 'x(t) are separated. Only ‘x(t) contains information related to the weak life signal while N(t) is negligible. ‘x (t)
is then further processed with a FFT algorithm in order to estimate the heartbeat and the breath rate.
Figure 5. Photography of the experimental setup.
V. ULTRA WIDE BAND STTW
[SEE THROUGH THE WALL]
In paper [05], the long term goal of military field imaging technology is the rapid detection of enemies' maneuvering; through acquiring relatively high-resolution images using advanced multidimensional image processing, pattern recognition techniques, and fast data processing. An example block diagram of such a radar system, developed at the University of Tennessee, is shown in Fig. 6. The system consists of an RF T/R board, UWB antennas, a digital timing and control board, and an imaging processing software module [10]. Capturing the data is the most challenging task for a system with a 1 GHz bandwidth, as Nyquist's sampling theorem requires a sampling rate of over 2 GS/s. In order to resolve distances on the order of one centimeter, rates exceeding 10 GS/s are required. Individual components at these rates are either not yet offered or very expensive. Hence, field programmable gate-arrays (FPGA)-based system was developed here, to implement a hybrid sampling scheme using Real-time and equivalent-time sampling techniques. Where, for a 10 MHz radar pulse repetition rate, the waveform is digitized at a 100 MHz rate. 10 samples are taken during each cycle, and then a 200 ps delay is placed
41 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr. Prashant S Ghulappanavar , Ms. Kavya B M
on the ADC triggering signal for the next 10 samples. The total time to collect the data comes out to 100 x 50 ns, i.e. 5 Fts. In general, intense wideband signal processing would normally require an entire custom VLSI or an ASIC implementation. After taking redundancy into account, this system achieves a 2.4ms/frame rate, with an averaging factor of 8 to improve S/N ratio. FPGA-based equivalent time sampling and control network provides a low-cost and high- performance solution for a practical UWB radar system. For image formation, algorithms such as back projection methods can be used given that wall effects are considered.
Figure 6. Typical system block diagram for
a UWB STTW radar.
CONCLUSION
UWB radar have shown effectiveness
detecting human presence in -- applications.
UWB radar system uses a unique Pulse
Frequency Repetition (PRF) for each human
body layer. Similarly, an antenna’s position
that enables to capture the echo reflected by
human body tissue is computed. The
performance of the system depends on
sampling rate and number of antenna array
elements. It was found that sampling rates
greater than 10 GHz were required for better
classification.
For human recognition, system estimates
vital signs specifically breathing rate and
heartbeat frequency. However, the level of
breath displacement is one order of magnitude
larger than heart displacement.
As the breath rate and its intensity can
depend on the person and the situation, in
some cases the frequency of breath harmonics
are close to the frequency of the heart signal,
which makes it difficult to locate and detect,
and leads to possible confusion. Future systems seek enhance this drawback,
and go beyond to isolate subjects, map structures, and exploit signals of opportunity.
REFERENCES
[1] FDTD modelling of a realistic room for the
through the wall radar applications, Walid. A
chamma,2007 ieee,1-4244-1170-x/07
[2] Auto focusing of the through the wall imagery
under unknown wall characteristics, fauzia ahmad,
senior member ieee, moeness g.amin fellow ieee
and govindaraju, ieee transactions on image
processing,vol.16,july 2007
[3] A rescue radar system for the detection of victims
trapped under rubble based on the independent
component analysis algorithm, Progress In
Electromagnetic Research M, Vol. 19, 173181,
2011,M.Donelli.
[4] Ultra Wideband Radar for Micro Aerial Vehicles,
Dario Brescianini
[5] Through-the-Wall Radar Life Detection and
Monitoring,Victor M. Lubecke, Olga Boric-
Lubecke, Anders Host-Madsen, and Aly E.
Fathy*,1-4244-0688-9/07/$20.00 C 2007 IEEE.
[6] Lee, T. W., Independent Component Analysis:
Theory and Applications, Kluwer academic
Publishers, 1999.
[7] Chen, K. M., D. Misra, H. Wang, H. R. Chuang,
and E. Postow, \An X-band microwave life-
detection system," IEEE Trans. Biomed. Eng., Vol.
57, No. 6, 607702, 1986.
[8] Molgedey, L. and H. G. Schuster, \Separation of a
mixture of independent signals using time delayed
correlations," Physical Review Letters, 36343637,
1994.
[9] Bell, A. J., T. P. Jung, and T. J. Sejonowski,
\Independent component analysis of
42 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Mr. Prashant S Ghulappanavar , Ms. Kavya B M
electroencephalographic data," Advances in Neural
Information Processing Systems, Vol. 1, 145151,
1996.
[10] Y. Yang, S. Liu, J. Wang, A.E. Fathy, "FPGA-
Based Data Acquisition and Beam forming System
for UWB See-Through- Wall Imaging Radar,"
IEEE AP-S Intl. Symp. On Antennas and
Propagation and USNC/URSI Nat. Radio Sci.
Meeting, 2006.
43 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Poornima R
GRAPHENE: A WONDER MATERIAL
Poornima R
Department of IEM MVJCE
Whitefield Bangalore, Karnataka, India
Abstract: Graphene, a two-dimensional
carbon allotrope, has emerged as one of the
most fascinating nano materials of the
century. Its distinct qualities have attracted
great interest in the fields of chemistry,
biology, and physics. Graphene has
stimulated interest among scientists in
various fields because of its exceptional
electronic, optical, mechanical, thermal, and
magnetic properties. The unique nature of
graphene makes it stand out and applicable
to various technologies and other purposes.
One application in particular is using
graphene’s outstanding electronic properties
for future electronic devices, possibly
replacing the silicon and indium tin oxide
used in current electronics. Computers,
computer chips, and other technological
products made from graphene will be more
flexible and will function faster because of
graphene’s transparency, light weight, and
flexibility. With modifications to graphene’s
structure and electrical properties, scientists
will be able to manufacture these new
technological appliances. However, its
applicability cannot be effectively realised
unless facile techniques to synthesize high
quality, large area graphene are developed in
a cost effective way. Considerable research
has been carried out for synthesizing
graphene and related materials by a variety
of processes.
Key Words: Graphene, electronic, silicon,
transparency, light weight, flexibility, facile.
I. INTRODUCTION
Graphene is a two-dimensional crystal of
carbon hexagonal crystal lattice. Its thickness
is equal to one atom, so that graphene belongs
to a class of nonmaterial‟s. Currently subject
of graphene taken a leading position in the
number of publications in leading international
journals in the field of surface physics and
nanosystems. This interest is due to its unusual
properties. There are several key factors that
make graphene a unique set of nanomaterials.
Despite the fact that its thickness is only one
atom, graphene is a stable form that can
maintain its crystalline structure, both in
vacuum and in a wide variety of surfaces. He
is not prone to oxidation under normal
conditions, allowing its use in air and even in
more aggressive environments. The crystal
graphene is very flexible. Carbon is a well-
known element and is contained in a great
many things in this world such as organic
materials that constitute organisms. Carbon is
an interesting element because, even if some
material is made of carbon atoms only, it can
have various morphologies and characteristics
depending on how carbon atoms bind together.
while both diamond and graphite (which is
used in pencil lead ) are made of carbon their
characteristics are different. Graphite is a layer
material and its monolayer is called garphene.
Grapheme has a honeycomb structure
44 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Poornima R
consisting of carbon atoms. It is an ideal two
dimensional material as it is an thin as the
thickness of the monolayer atoms. When
grphene is given a round geometry , it forms a
carbon nanotube (CNT), which are nothing
more than a rolled graphene sheets. Graphene
has a large conductance, where as no other
film of this thickness is not a good conductor
of electric current. In the "Advanced
Experiments with a two-dimensional graphene
material," A. K. Geim and K. S. Novoselov
was awarded the Nobel Prize in Physics for
2010.
II. BACKGROUND
Discoveries of carbon allotropes have
punctuated scientific and technological
advances at the interface of the 2nd and 3rd
millennia. One can argue that nanoscale
science as a field has emerged at the end of the
20th century largely as a result of these
discoveries. Every decade over the past 30
years saw a new formof carbon created in a
lab, giving birth to an exponentially growing
number of studies. In 1985 Kroto, Heath,
O'Brien, Curl, and Smalley obtained fullerenes
[1]. Then, in 1991 Sumio Iijima clearly
identified carbon nanotubes within the
prepared material [2]. Finally, in 2004
Novoselov, Geim, Morozov, Jiang, Zhang,
Dubonos, Grigorieva and Firsov prepared
electrically isolated, singlelayer graphene [3].
Within extraordinary short periods of time the
seminal importance of these works was
awarded with two Nobel prizes. The 1996
Nobel Prize in Chemistry was awarded jointly
to Robert F. Curl, Jr., Sir HaroldW. Kroto, and
Richard E. Smalley “for their discovery of
fullerenes”. The 2010 Nobel Prize in Physics
was given to Andre Geim and Konstantin
Novoselov “for groundbreaking experiments
regarding the two-dimensional material
graphene”. As far back as in 1947, graphene
was predicted to have extraordinary electronic
properties, if it could be isolated. For years,
grapheme was considered an academic
material that existed only in theory and
presumed not to exist as a free standing
material, due to its unstable nature. A. Geim,
K. Novoselov, and co-workers were among the
first to successfully obtain the elusive free-
standing graphene films,4 which wasa
remarkable achievement. Thus, the 2010
Nobel Prize for Physics awarded to Geim and
Novoselov for “groundbreaking experiments
regarding the two-dimensional material
graphene” must be celebrated as recognition of
remarkable ingenuity in experimental physics.
The International Union of Pure and Applied
Chemistry (IUPAC) defines graphene as a
single carbon layer of the graphite structure,
describing its nature by analogy to a
polycyclic aromatic hydrocarbon of quasi
infinite size.5 Thus, the term graphene should
be used only when the reactions, structural
relations, or other properties of a single layer
are discussed. Previously, descriptions such as
graphite layers, carbon layers, or carbon sheets
have been used for the term graphene.
III. GRAPHENE AND ITS
PROPERTIES
The pencil hasn‟t been innovative technology
since the 19th century. But graphene, the one-
atom thick sheet of carbon that, when stacked,
forms graphite, the “lead” in pencils, may be
the key to future electronic applications.
Graphene‟s electrons have also been known to
demonstrate different phenomena, such as, the
Klein effect and the quantum Hall effect. The
Klein effect takes place when charge carriers
are able to pass right through high potential
barriers as if they were nonexistent.
Graphene‟s electrons have this potential to
pass through barriers. Graphene also
demonstrates an unfamiliar version of the
quantum Hall effect. The quantum Hall effect
is a quantum-mechanical version of the Hall
45 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Poornima R
effect that occurs in two-dimensional electron
systems, such as graphene [2]. The Hall Effect
occurs when a magnetic field is applied
perpendicular to a thin sheet of conducting or
semiconducting material through which a
current is flowing [9]. A potential difference
will be created on opposite edges of the
conducting or semiconducting material. The
Hall effect offered the first real proof that
electric currents in metals are carried by
moving electrons, not by protons. It also
demonstrated that in some substances,
especially semiconductors, that it is more
appropriate to imagine the electric current as
positive “holes” instead of negative electrons
[9]. Graphene‟s electronic current is often
described as a current of positive holes as well.
The quantum Hall effect usually takes place in
high magnetic fields and low temperatures.
However, graphene performs the quantum Hall
effect at room temperature and at even higher
temperatures; this is due to the unusual nature
of graphene‟s electrons to imitate massless
particles.
Graphene also portrays extraordinary optical
properties. Graphene only has 2.3% cloudiness
on its honeycomb surface. This leaves an over
98% visual transmission rate, which makes
graphene almost completely transparent
(Figure1) [5]. To make graphene even more
transparent, scientists use a method called
electrical gating, which is made possible by
the limit of electrons in the monolayer and the
low density of states near a Dirac point.
Graphene‟s photoluminescence abilities are
demonstrated first by using chemical or
physical methods to weaken the connection of
the pi-electron network [5].
In future electronics, graphene‟s transparency
and photoluminescence is hoped to be
demonstrated by being placed as the surfaces
of flat-screen computers and televisions.
Figure 1- Graphene‟s incredible transparency
is shown in this figure.
Graphene is the thinnest and strongest material
yet discovered. Its theoretical tensile strength
is 150,000,000 kPa, and its Young‟s modulus
is 1,000,000,000 kPa; therefore, grapheme has
Figure 1- Graphene‟s incredible transparency
is shown in this figure
incredible bending strength and a high
elasticity measurement [5]. Scientists have
proven that
graphene is several times stronger than
diamond and 200 times stronger than steel
[11]. Graphene is so strong that if a coffee
mug was wrapped with a single layer of
graphene, it could withstand the weight of a
car, a weight of approximately 4,000 pounds.
Better yet, a single layer of graphene can
support the weight of an elephant, a weight of
at least 2.6 tons. If one wanted to break
through a single sheet of graphene, an elephant
would need to balance on a pencil to
penetrate graphene‟s surface [12]. Graphene is
also known for its outstanding heat
46 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
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conductivity. It is the best heat conductor at
room temperature yet discovered. In graphene
and other carbon materials, heat conduction is
controlled by phonons, which are quantized
modes of vibration occurring in a crystal
lattice [8]. Graphene also conducts heat very
well because of its unique electron
arrangement. As a result of each carbon atom‟s
bond with only three other carbon atoms, a 2pz
orbital is left free. As graphene‟s honeycomb
lattice vibrates, the electrons in the 2pz orbitals
jump from atom to atom along the strong
covalent sp2 bonds [10]. These electrons
easily navigate through graphene‟s honeycomb
lattice and carry heat throughout graphene‟s
structure. In other words, the reason why
graphene is an excellent conductor of heat and
electricity is because it has so many mobile
electrons in its structure. After
experimentation on graphene, scientists found
that the room temperature thermal
conductivity of single layer graphene is in the
range of K~ 3000-5300 W/mK depending on
the graphene flake size[5].
Graphene also has magnetic properties as a
result of its unique band structure. Although
pure graphene is not magnetic, scientists can
manipulate it structure that allow graphene to
become magnetic. Scientists remove carbon
atoms from the graphene sheet in order to
promote its magnetism, since magnetism can
be achieved by moving electrically charged
particles [14].
Graphene‟s magnetic field is a result of those
missing carbon atoms which act as tiny
magnets. These tiny magnets strongly
intermingle with graphene‟s electrons. The
electrical current the electrons carry leads to
an extra electrical resistance at low
temperature [14]. After the manipulation of
graphene‟s structure, it becomes an excellent
magnet. When placed in the cold temperatures
of liquid nitrogen, graphene still maintains its
magnetic properties.
IV. SYNTHESIS METHODS Various techniques have been found for
producing thin graphitic films However as
mentioned earlier never were their electronic
properties investigated because of the
difficulty in isolating and transferring them
onto insulating substrates. But in the late 90‟s
Ruoff and co workers tried isolating thin
graphitic flakes on SiO2 substrates by
mechanical rubbing of patterned islands on
HOPG22. However there was no report on
their electrical property characterization.
Using a similar method this was later achieved
in 2005 by Kim and co workers and the
electrical properties were reported. However
the real gold rush in graphene research began
after Geim and co workers first published their
work of isolating graphene onto SiO2 substrate
and measuring its electrical properties. After
discovery of graphene in 2004 various
techniques were developed to produce thin
graphitic films and few layer graphene. They
will be discussed in detail below.
1. Epitaxial growth on metals
2. Mechanical exfoliation
3. Wet Chemical synthesis
4. Epitaxial growth on carbides.
5. Chemical Vapor Deposition
6. Miscellaneous methods.
V. CHEMICAL VAPOUR
DEPOSTION
A scheme of a CVD installation used for
synthesis of
graphene films is shown in Figure 2. Inside the
chamber filled with hydrogen and argon (at
pressures of 500 mbar) a nickel foil (with a
thickness of 25 _m and size of 20×30 mm)
was squeezed between two electrodes. When
an electric current (about 70 A) was applied to
the electrodes, the foil was heated up to a
temperature of about 1000 _C. At this
temperature, the oxide escape from the nickel
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foil. After that the foil was cooled down to a
temperature of 800 _C and methane was
injected into the chamber, and then the
temperature was gradually increased to the
desired value. A methane gas decomposed and
the
carbon atoms deposited on the foil surface and
then their diffusion inside the bulk of substrate
started. After that the foil was cooled down to
room temperature with the different cooling
rates, and carbon atoms were pushed to the
surface due to a thermal decompression the
nickel crystalline lattice forming a graphene
film.16 To obtain the required film thickness it
is necessary to control all parameters of the
synthesis process, but the main parameters
deternining the number of formed layers are
the growth temperature, the concentration of
methane and the cooling rate.
Fig. 2. A scheme of installation for CVD synthesis of
grapheme
Fig. 3. Graphene films (a) on a glass substrate, (b) on a
silicon substrate.
Hydrogen. Hydrogen is needed primarily
during annealing to get rid out of the oxide.
Hydrogen is also necessary to reduce the
concentration of methane in the chamber; it is
used simply to dilute the mixture. It did not
significantly affect the results of the
experiment, but completely remove it anyway
is not possible, because the injected methane
then decomposes into carbon and hydrogen.
Fig. 4. The optical images of graphene samples on a
silicon substrate synthesized (a) with argon, (b) without
argon.
Argon. Argon significantly affects the
technical process of synthesis. The argon
thermal conductivity equals to 0.0177 W/(m·
K), which is almost 10 times less than this
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value for hydrogen (0.1815 W/(m · K)). This
results in accumulation of the heat near the
substrate and does not allow to loss the energy
of the electrode heating. Due to the nickel foil
is heated by applying of DC, the reduction of
the heat loss makes it possible to heat the foil
of the large size with a low current. In
addition, since the sample itself has a size of
20×30 mm, there is a temperature gradient
from the center to the edges between
electrodes along the nickel foil and it has a
value of 80–100 degrees without the
introduction of argon. But the gradient reduces
to 10–30 degrees if the argon is introduced in
the chamber. Figures 3(a), (b) show the images
of samples on a silicon substrate synthesized
with and without argon. Figures 4(a), (b) show
the Raman spectra for these samples
demonstrating quite a high quality of
graphene.
Fig. 5. The Raman spectra of graphene samples on a
silicon substrate synthesized (a) with argon, (b) without
argon
Methane. Methane is introduced as a source of
carbon atoms. Its concentration is one of the
essential parameters of the process. The more
methane (this means the more carbon atoms) is
introduced into the chamber with the other
fixed parameters, the more number of
graphene layers will be grown. We have
prepared a series of experiments with different
concentrations of methane and on this basis
plotted the dependences of the number of
layers of synthesized graphene on the growth
temperature (Figs. 6(a, b)). An approximate
amount of layers was estimated from the
optical transmission spectra on the basis of the
fact that a single graphene layer absorbs 2.3%
of the incident light. (The inhomogenuity of a
single layer due to the temperature gradient
over the foil should be taken into account.)
Some combination of concentration and
pressure are critical for the process of
synthesis. At concentrations being lower than
2% methane under the pressure of 100 mbar
and less, we have not been able to obtain
graphene. (a)
(b)
VI. FUTURE
APPLICATIONS
49 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Poornima R
Graphene has a number of properties which
makes it interesting for several different
applications. It is an ultimately thin,
mechanically very strong, transparent and
flexible conductor. Its conductivity can be
modified over a large range either by chemical
doping or by an electric field. The mobility of
graphene is very high which makes the
material very interesting for electronic high
frequency applications. Recently it has become
possible to fabricate large sheets of graphene.
Using near-industrial methods, sheets with a
width of 70 cm have been produced. Since
graphene is a transparent conductor it can be
used in applications such as touch screens,
light panels and solar cells, where it can
replace the rather fragile and expensive
Indium-Tin-Oxide (ITO). Flexible electronics
and gas sensors4 are other potential
applications. The quantum Hall effect in
graphene could also possibly contribute to an
even more accurate resistance standard in
metrology. New types of composite materials
based on graphene with great strength and low
weight could also become interesting for use
in satellites and aircraft.
VII. CHALLENGES
Synthesizing large area high quality single
layer graphene is one of the major challenges.
Recent developments, particularly in CVD
synthesis of graphene on metal substrates have
proved to be major breakthroughs in
overcoming this challenge. Currently,
applications for graphene are limited because
it is too expensive to mass produce [13]. Not
only is it expensive, it is also difficult to
isolate multiple layers of graphene. Graphene
synthesis by exfoliation and other methods
take a while to complete, and they do not
produce a high yield of graphene. Another
disadvantage of using graphene is that until
now, graphene-related materials existed only
as conductors or insulators, never as semi-
conductors that are necessary for electronic
applications [13]. Since graphene is a
relatively new nonmaterial, its safety is
unknown when exposed to different
environments and living systems Because
graphene has an efficient, fast, and mass less
flow of electrons, scientists are having a
difficult time turning off its electrical current,
which delays and prevents graphene research.
CONCLUSION
The development of this new material, opens
new exiting possibilities. It is the first
crystalline 2D-material and it has unique
properties, which makes it interesting both for
fundamental science and for future
applications. The ideal graphene based
technology would be high definition
televisions and computers as thin as wallpaper,
or cell phones that you can wrap around your
wrist and fold into your pocket. Despite being
the smallest material known to
mankind, it is the strongest material in the
world. After evaluating graphene‟s various
properties, it is no wonder that graphene is
called the “wonder material.” With slight
modification to graphene‟s structure, scientists
will be able to make graphene an even better
conductor of heat and electricity, which will
improve and stimulate the manufacturing of
the
electronic devices and technology of the
future.
REFERENCES
[1] H.W. Kroto, J.R. Heath, S.C. Obrien, R.F. Curl, R.E.
Smalley, Nature 318 (1985) 162.
[2] S. Iijima, Nature 354 (1991) 56.
50 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Poornima R
[3] K.S. Novoselov, A.K. Geim, S.V. Morozov, D.
Jiang, Y. Zhang, S.V. Dubonos, I.V. Grigorieva, A.A.
Firsov, Science 306 (2004) 666.
4. Gerstner, Ed. “Nobel Prize 2010: Geim and
Novoselov.” Nature Physics October 5, 2010
5. Yao, Jun; Sun, Yu; Yang, Mei; Duan, Yixiang.
“Chemistry, physics, and biology of
graphene-based nanomaterials: new horizons for
sensing, imaging, and medicine” Journal of Materials
Chemistry 14313/22 (2012)
6. Sarkar, Santanu; Bekyarova, Elena; Haddon, Robert
C. “Covalent chemistry in graphene electronics”
Materials Today 6/15 (2012)
7. Zhan, Da; Yan, Jiaxu; Lai, Linfei; Ni, Zhenhua; Liu,
Lei; Shen, Zexiang. “Engineering the Electronic
Structure of Graphene” Materials Views (2012)
8. Shahil, Khan M.F.; Balandin, Alexander A. “Thermal
Properties of graphene and multilayer graphene:
Applications in thermal interface materials” Solid State
Communications (2012)
9. Jiang, Z.; Zhang, Y; Tan, Y.-W.; Stormer, H.L.; Kim,
P. “Quantum Hall effect in graphene” Solid State
Communications (2007)
10. A. Reina, X. Jia, J. Ho, D. Nezich, H. Son, V.
Bulovic, M. S. Dresselhaus, and J. Kong, Nano Lett. 9,
30 (2009).
11. A. L. Vázquez de Parga, F. Calleja, B. Borca, M. C.
G. Passeggi, J. J. Hinarejos, F. Guinea, and R. Miranda,
Phys. Rev. Lett. 100, 056807 (2008).
12. K. S. Kim, Y. Zhao, H. Jang, S. Y. Lee, J. M. Kim,
K. S. Kim, J.-H. Ahn, P. Kim, J.-Y. Choi, and B. H.
Hong, Nature 457, 706 (2009).
13. “Graphene-Based Electronics: Entirely New
Carbon-Based Material Synthesized from Graphene”
Science Daily April 16, 2012
14. X. Li, W. Cai, J. An, S. Kim, J. Nah, D. Yang, R.
Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K.
Banerjee, L. Colombo, and R. S. Ruoff, Science 117,
1245 (2009).
15. A. Reina, S. Thiele, X. Jia, S. Bhaviripudi, M. S.
Dresselhaus, J. A. Schaefer, and J. Kong, Nano Res. 2,
509 (2009).
16. M. G. Rybin, A. S. Pozharov, and E. D. Obraztsova,
Phys. Status Solidi C 7, 2785 (2010).
[17] M. Luleva. (2013). “Graphene Can Be Harmful to
Human Cells, Scientists Say.” The Green Optimistic.
(Online article).
http://www.greenoptimistic.com/2013/07/15/researchers
discover-properties-of-graphene-harmful-to-
humancells/#. Um3GyPk_vpp
[18] “Graphene „miracle material‟ could be toxic to
humans.” io9. (Online article). http://io9.com/i-can-see-
how-thismight-be-a-problem-i-often-enjoy-ea-
789664034
51 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Bindiya Patil, Shruthi B.R, Roopashree B.G
ETHICAL ISSUES OF MONITORING ALZHEIMER‘S
PATIENTS
Bindiya Patil, Shruthi B.R, Roopashree B.G
MVJ College OF Engineering, Bangalore, India
Abstract— Alzheimer's disease (AD), also
known in medical literature as Alzheimer
disease, is the most common form of
dementia. There is no cure for the disease,
which worsens as it progresses, and
eventually leads to death. Recently, numerous
systems for geo-tracking Alzheimer’s patients
with dementia are developed and reported to
be functional for the purposes of security and
data collection. However, it was also reported
that use of such systems had generated
ethical issues. Studies stated possible loss of
freedom and autonomy for patients, along
with violations of their privacy, which may
lead to loss of prestige/dignity. In this project
we are developing a geo-tracking system that
aims to balance patients’ security and their
need for privacy and autonomy is proposed. It
simply tries to maintain patients’
independence while assuring they are secure.
INTRODUCTION
In this project we are designing and
developing a system which will continuously
track the position of the patient and send the
location information to home. We are using
RF communication technology to track the
patient location and send this information to
home. To track the location of the patient, we
are placing a RF ID tag in the device that the
patient can wear. The Antennas placing at
different locations will receive the signal from
the RF ID tag of the patient and send the
location information to home.
In this project we are also continuously
monitoring the biomedical parameters like
sweating and body muscle movement of the
patient which will help the care taker to
understand the health condition of the patient
and to take necessary action. We are placing a
sweat detector and an EMG Stimulator on the
device that the patient can wear. The sweat
detector is using to find whether the patient
body is sweating due to high blood pressure
and EMG Stimulator to find if the patient is
having shivering. If this system detects any
change in these parameters, then immediately
it will send the information to home via RF
technology.
This project is also designed to send a
message to care taker or family member via
GSM. This project will help to improve the
freedom, privacy and security of the patient
along with that it will help the care taker to
monitor the patient movement and health
condition without being with them.
I. PROCEDURE
A. Review Stage
EMG Sensor
Electromyography (EMG) is an
electrodiagnostic medicine technique for
evaluating and recording the electrical activity
produced by skeletal muscles. EMG is
performed using an instrument called an
electromyograph, to produce a record called an
electromyogram. An electromyograph detects
the electrical potential generated by muscle
52 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Bindiya Patil, Shruthi B.R, Roopashree B.G
cells when these cells are electrically or
neurologically activated. The signals can be
analyzed to detect medical abnormalities,
activation level, or recruitment order or to
analyze the biomechanics of human or animal
movement.
EMG signals have a variety of clinical
and biomedical applications. EMG is used as a
diagnostics tool for identifying neuromuscular
diseases, or as a research tool for studying
kinesiology, and disorders of motor control.
EMG signals are sometimes used to guide
botulinum toxin or phenol injections into
muscles. EMG signals are also used as a
control signal for prosthetic devices such as
prosthetic hands, arms, and lower limbs.
Electrical activity is recorded extracellularly
from muscle fibres that are embedded in the
tissue. This is used the detect the body muscle
movements. EMG sensor is preferred over
vibration sensor since the latter detects even
the smallest muscle movements whereas in the
former cut off frequency can be set.
Sweat Detector
Galvanic skin resistance (GSR) - This is also
called electro-dermal activity, and is basically
a measure of the sweat on your fingertips. The
finger tips are one of the most porous areas on
the body and so are a good place to look for
sweat. The idea is that we sweat more when
we are placed under stress. Fingerplates, called
galvanometers, are attached to two of the
subject's fingers. These plates measure the
skin's ability to conduct electricity. When the
skin is hydrated (as with sweat), it conducts
electricity much more easily than when it is
dry.
In this project, we use sweat detector which
consists of two electrodes which conduct in the
presence of salt content in sweat. The distance
between the two electrodes is directly
proportional to the sensitivity of sweat
detector.
.
B. Final Stage
MONOSTABLE MULTIVIBRATOR
The timer comprises two operational
amplifiers (used as comparators) together with
an RS Bistable element. In addition, an
inverting output buffer is incorporated so that a
considerable current can be sourced or sunk
to/from a load. A single transistor switch,
TR1, is also provided as a means of rapidly
discharging the external timing capacitor.
The standard 555 timer is housed in an 8-pin
DIL package and operates from supply rail
voltages of between 4.5V and 15V. This
encompasses the normal range for TTL
devices and thus the device is ideally suited for
use in conjunction with TTL circuitry.
MICROCONTROLLER
The general definition of a microcontroller is a
single chip computer, which refers to the fact
that they contain all of the functional sections
(CPU, RAM, ROM, I/O, ports and timers) of a
traditionally defined computer on a single
integrated circuit. Some experts even describe
them as special purpose computers with
several qualifying distinctions that separate
them from other computers.
Microcontrollers are "embedded" inside some
other device (often a consumer product) so that
they can control the features or actions of the
product. Another name for a microcontroller,
therefore, is "embedded controller."
Microcontrollers are dedicated to one task and
run one specific program. The program is
stored in ROM (read-only memory) and
generally does not change.
HEX BUFFER / CONVERTER [NON-
INVERTER] IC 4050: Buffers does not affect
the logical state of a digital signal (i.e. logic 1
input results into logic 1 output where as logic
0 input results into logic 0 output). Buffers are
normally used to provide extra voltage drive at
the output, but can also be used to regularize
the logic present at an interface. And Inverters
are used to complement the logical state (i.e.
logic 1 input results into logic 0 output and
53 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Bindiya Patil, Shruthi B.R, Roopashree B.G
vice versa). Also Inverters are used to provide
extra voltage drive and, like buffers, are used
in interfacing applications. This 16-pin DIL
packaged IC 4050 acts as Buffer as-well-as a
Converter. The input signals may be of 2.5 to
5V digital TTL compatible or DC analogue the
IC gives 5V constant signal output. The IC acts
as buffer and provides isolation to the main
circuit from varying input signals. The
working voltage of IC is 4 to 16 Volts and
propagation delay is 30 nanoseconds. It
consumes 0.01 mill Watt power with noise
immunity of 3.7 V and toggle speed of 3
Megahertz.
RADIO FREQUENCY ID
Radio must surely be one of the most
fascinating aspects of electronics. This part of
explanation provides a brief introduction to
radio communication before describing the
circuitry of RF receivers and transmitters. The
aim has been to provide the user with
sufficient information to what his or her
appetite for a subject which has a broad appeal
to a large number of dedicated enthusiasts all
over the world.
Radio frequency signals are generally
understood to occupy a frequency range, which
extends from a few tens of kilohertz to several
hundred giga-hertz. The lowest part of radio
frequency range, which is of practical use
(below 30 kHz), is only suitable for narrow-
band communications. At this frequency,
signals propagate as ground waves (following
the curvature of the earth) over very long
distance. At the other extreme, the highest
frequency range, which is of practical
importance, extends above 30GHz. At these
‗microwave‘ frequencies, considerable
bandwidths are available (sufficient to transmit
many television channel using point-to-point
links or to permit very high definition radar
systems) and signals tend to propagate strictly
along ‗line-of-sight‘ paths.
C.Figures
II. CONCLUSION
The project report has shown various ethical
issues faced by a person with Alzheimer‘s
disease and the remedy for these issues. This
project aims at providing a person his/her
privacy or independent life style without
depending on other person for help.
In this project the device designed is capable
of tracking both the blood pressure and
epilepsy. When there are any changes in the
parameters such as temperature, blood
pressure, occurring of epilepsy etc, the device
will detect these signals using various sensors
built in the device and inform the care taker
about the changes in patient‘s medical status
and location of the patient. Because of which
the patient is free to go wherever he wants
within limited range of some meters.
54 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Bindiya Patil, Shruthi B.R, Roopashree B.G
Here, we fix various sensors on the body of the
patient (arm) which will detect various
changes in the patient‘s medical status. These
signals are then amplified to confirm the
existence of problem or emergency in patient‘s
status and then the signals are sent to the care
taker.
In this project we use RF and GSM
technologies to provide the communication
channel or path. It is advantages to use both of
them as the message can be sent to the care
taker by either of the way and in some cases if
one connections break or doesn‘t support we
can send the message by the other
communication device.
Hence, in this project we can solve some of the
ethical issues faced by the patient with
Alzheimer‘s disease.
REFERENCES
[1] G. O. Young, ―Synthetic structure of industrial
plastics (Book style with paper title and editor),‖
in Plastics, 2nd ed. vol. 3, J. Peters, Ed. New
York: McGraw-Hill, 1964, pp. 15–64.
[2] W.-K. Chen, Linear Networks and Systems (Book
style). Belmont, CA: Wadsworth, 1993, pp. 123–
135.
[3] H. Poor, An Introduction to Signal Detection and
Estimation. New York: Springer-Verlag, 1985, ch.
4.
[4] B. Smith, ―An approach to graphs of linear forms
(Unpublished work style),‖ unpublished.
[5] E. H. Miller, ―A note on reflector arrays (Periodical
style—Accepted for publication),‖ IEEE Trans.
Antennas Propagat., to be published.
[6] J. Wang, ―Fundamentals of erbium-doped fiber
amplifiers arrays (Periodical style—Submitted for
publication),‖ IEEE J. Quantum Electron.,
submitted for publication.
[7] C. J. Kaufman, Rocky Mountain Research Lab.,
Boulder, CO, private communication, May 1995.
55 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Divyashree M, Shivakanth
STUDY OF DIODE, BIPOLAR JUNCTION
TRANSISTOR AND OP-AMP USING MATLAB
Divyashree M, Shivakanth
Telecommunication Engineering Department,
MVJ College of Engineering, Bangalore, India
E-mail id1: [email protected]
E-mail id2:[email protected]
Abstract— MATLAB (Matrix Laboratory)
is a numeric computation software for
engineering and scientific calculations.
It is being used to teach circuit theory, filter
design, random processes, control system
and communication theory. Matrix
functions are shown to be versatile in doing
analysis of data obtained from electronics
experiments. In this paper the graphical
features of MATLAB are especially useful
for display of characteristics of a diode,
temperature effects on diode, input and
output characteristics of transistor for CB
configuration and the input and output
voltages of the inverting op-amp.
Keywords— MATLAB, CB configuration,
diode, transistor, op-amp.
I. INTRODUCTION
MATLAB is a high level language whose
basic data type is a matrix that does not
require dimensioning. There is no
compilation and linking of programs as it is
normally done in other high level languages,
such as C or FORTRAN. In MATLAB, all
computations are done in complex valued
double precision arithmetic to guarantee high
accuracy. MATLAB has a rich set of plotting
capabilities. The graphics are integrated into
MATLAB. Since MATLAB is also a
programming environment, a user can extend
the functional capabilities of MATLAB by
writing new modules. MATLAB has a large
collection of toolboxes for variety of
applications. A toolbox consists of functions
that can be used to perform some
computations in the toolbox domain.
In this paper, the following topics of
electronics will be discussed: diodes, bipolar
junction transistors, operational amplifier and
its characteristics are studied using
MATLAB.
II. DIODES
In this chapter the characteristics of diodes
and temperature effects on the diodes will be
discussed using MATLAB.
A. Diode Characteristics
Diode is a two-terminal device. The
electronic symbol of a diode is shown in Fig.
1. Ideally, the diode conducts current in one
direction. The current versus voltage
characteristics of an ideal diode are shown in
Fig. 2.
Fig. 1 Electronic symbol of diode.
Fig. 2 Ideal diode I-V characteristic
The I-V characteristic of a semiconductor
junction diode is shown in Fig. 3. The
characteristic is divided into three regions:
56 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Divyashree M, Shivakanth
forward-biased, reversed biased and the
breakdown.
Fig. 3 I-V characteristic of a semiconductor
junction diode.
In the forward-biased and reversed-biased
regions, the current i and the voltage v, of a
semiconductor diode are related by the diode
equation
Where IS is reverse saturation current or
leakage current, n is an empirical constant
between 1 and 2,
VT is thermal voltage, given by
k is Boltzmann’s constant = 1.38e−23 J /oK
q is the electronic charge = 1.6e−19
Coulombs
T is the absolute temperature in oK
At room temperature (25 oC), the thermal
voltage is about 25.7 mV.
-0.05 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05-1
0
1
2
3
4
5
6
7x 10
-6 Characteristic of semiconductor diode
Voltage v, V
Curr
ent
i, m
A
Fig. 4 I-V characteristic of a forward
biassemiconductor junction diode.
The I-V characteristic of a forward biased
semiconductor junction diode using
MATLAB is shown in Fig. 4.
B. Temperature effects on diode
From the diode equation (1), the thermal
voltage and the reverse saturation current are
temperature dependent. The thermal voltage
is directly proportional to temperature. This
is expressed in equation (2). The reverse
saturation current IS increases approximately
7.2% /oC for both silicon and germanium
diodes. The expression for the reverse
saturation current as a function of
temperature is
(3)
Where kS = 0.072 / o C. T1 and T2 are two
different temperatures. Since e0.72
is
approximately equal to 2, equation (3) can be
simplified and rewritten as
The variation in temperature causes the
change in behavior of the diodes. For
forward biased junction, as temperature is
increased, the forward current increases for a
57 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Divyashree M, Shivakanth
given forward voltage. Temperature can have
remarkable effect on the V-I characteristics
of a diode. The saturation current of a diode
at 25 oC is 10
-12 A. Assuming that the
emission constant of the diode is 1.9, Fig 5
shows plotting of the I-V characteristic of the
diode at the following temperatures: T1 = 0 oC, T2 = 100
oC using MATLAB.
0.45 0.5 0.55 0.6 0.65 0.7 0.750
1
2
3
4
5
6
7
8
9
10Diode I-V Curve at two Temperatures
Voltage (V)
Curr
ent
(A)
o is for 100 degrees C
+ is for 0 degree C
Fig. 5 Temperature Effects on the Diode Forward
Characteristics.
III. BIPOLAR JUNCTION
TRANSISTORS
Transistor is a three terminal device: Base,
emitter and collector, can be operated in
three configurations common base, common
emitter and common collector. Bipolar
junction transistor (BJT) consists of two p-n
junctions connected back to back. The
operation of the BJT depends on the flow of
both majority and minority carriers. There
are two types of BJT: NPN and PNP
transistors. The electronic symbols of the two
types of transistors are shown in Fig. 6.
(a)
(b)
Fig. 6 (a) NPN Transistor (b) PNP Transistor
A. Common base configuration
Fig. 7 shows NPN transistor in common base
configuration. In this circuit arrangement,
input is applied between emitter and base
terminals and output is taken from collector
and base terminals. In this circuit, base
terminal is common to both input and output
hence the common base (CB) configuration.
Fig. 7 Common base configuration of NPN
Transistor
1. Input Characteristics
Input characteristics are obtained between
input current and input voltage with constant
output voltage. First keep the output voltage
VCB constant and vary the input voltage
VEB for different points then at each point
record the input current IE value. Repeat the
same process at different output voltage
levels. Now with these values we need to plot
the graph between IE and VEB parameters.
The below figure show the input
characteristics of common base
configuration. The equation to calculate the
input resistance Rin value is given below.
2. Output Characteristics
The output characteristics of common base
configuration are obtained between output
current and output voltage with constant
input current. First keep the emitter current
constant and vary the VCB value for different
points, now record the IC values at each point.
58 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Divyashree M, Shivakanth
Repeat the same process at different IE values.
Finally we need to draw the plot between
VCB and IC at constant IE. The below figure
show the output characteristics of common
base configuration. The equation to calculate
the output resistance value is given below.
0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.650
5
10
15
20
25
30
35Input characteristics
Base-emitter voltage, V
Em
itte
r curr
ent,
A
Fig. 8 Input Characteristics of CB configuration
0 1 2 3 4 5 60
1
2
3
4x 10
-4 Output Characteristic
Collector-base Voltage, V
Collecto
r curr
ent,
A
Fig. 9 Output Characteristics of CB configuration
Thus in this chapter input and output
characteristics of CB configuration of NPN
transistor are studied using MATLAB as
shown in Fig 8 and Fig 9 respectively.
IV. OPERATIONAL AMPLIFIERS
The op amp is one of the basic building
blocks of linear design. The name “op amp”
is the standard abbreviation for operational
amplifier. In its classic form it consists of
two input terminals, one of which inverts the
phase of the signal, the other preserves the
phase, and an output terminal. The standard
symbol for the op amp is given in Fig 10.
Fig. 10 Op-amp Symbol
There are two configurations. An op amp
connected in a non-inverting configuration is
shown in Fig 11. An op amp circuit
connected in an inverted closed loop
configuration is shown in Fig. 12.
Fig. 11 Non-inverting configuration
Fig. 12 Inverting configuration
Model the operational amplifier as an ideal
op amp. Then the output voltage of the
inverting amplifier is
related to the input voltage by
59 MVJCE-JOURNAL- Vol 4, Issue 2, Dec-2015
Divyashree M, Shivakanth
When voltage saturation is included in the
model of the operational amplifier, the
inverting amplifier is described by
(8)
Where Vsat denotes the saturation voltage of
the operational amplifier. Equation 8 is a
more accurate, but more complicated, model
of the inverting amplifier than Equation 7. Of
course, we prefer the simpler model, and we
use the more complicated model only when
we have reason to believe that answers based
on the simpler model are not accurate.
Fig. 13 illustrate the use of MATLAB to
analyze the inverting amplifier when the
operational amplifier model includes voltage
saturation and it shows the MATLAB input
file, corresponding to the circuit shown in
Fig.12.
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
x 10-3
-20
-15
-10
-5
0
5
10
15
20
time, s
vo(t
), V
Fig. 13 The input and output voltages of the inverting
amplifier.
V. CONCLUSIONS AND FUTURE
ENHANCEMENT
Areas in electronics where MATLAB can be
used to teach electronics principles and
concepts to engineering students are
discussed. In this paper MATLAB has been
used to examine the characteristics of diode,
transistor and op-amp. The versatile nature of
MATLAB allows "what-if'' analysis that can
be used to strengthen students understanding
of electronics. MATLAB is useful in
analysing data obtained from electronics
laboratory experiments.
Future work can be done for the AC circuit
analysis, DC circuit analysis and transient
analysis of a electrical network can be
studied using MATLAB.
REFERENCES
[1] “Electronic Devices and Circuit Theory”, Robert
L. Boylestad and Louis Nashelsky, PHI/Pearson
Education, 9th
Edition.
[2] “Electronic Devices and Circuits”, David A. Bell,
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[3] David, McMahon, “MATLAB Demystified”,
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[4] J. A. Gow, C. D. Manning “Development of a
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[5] D. Nelson , S. Evans . A new approach to op
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[6] A. Sedra , K.C. Smith . A second generation
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[7] H. K. Gummel "A self-consistent iterative
scheme for one dimensional steady state
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[8] Ruben Rojas-Oviedo, Dr. X. Cathy Qian,
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in Engineering through Freshman Courses”,
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[9] Andrew Kline, Betsy M. Aller, and Dr. Edmund
Tsang, “Improving student retention in STEM
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