Why computer programming

CIV1900

Dr Sam Clarke

Introduction

Civil Engineering Skills

Computer programming

Have you programmed before?

A. Yes (C++, Java)B. Yes (Html, CSS)C. Yes (Fortran,

Matlab)D. No

A. B. C. D.

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There are 5 weeks of material that combine a short lecture (~ 30 mins), with a 2 hour computer class and a short quiz

Today’s intro lecture & variables

There will be two sessions (Wks10 & 11) that explain how to accomplish particular programming tasks

The final session is more about computer graphics and introduces the programming assessment.

How this fits in...

1. Final quiz is worth 10% (wk12)Portfolio elements (printed graphics & code) 10%

2. 4 online tests (weeks 8-11) Unlimited attempts, 70% to pass.Each worth 1.25%You will not be allowed to proceed to the next Quiz without successful completion

Assessment

What is Computer Programming?

Why engineers need to program

Computer modelling and its importance for engineering problems

How to write an algorithm to solve an engineering task

Contents for Lecture 1

Why engineers need to program

Computer modelling and its importance for engineering problems

How to write an algorithm to solve an engineering task

Contents for Lecture 1

What is an Algorithm?

A. A step-by-step procedure for calculations

B. A random computer process

C. The music of algaeD. The principle of

how a computer works

A. B. C. D.

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What is an Algorithm?

How a computer executes a process

OrderInstructionsRules

On famous physicist Richard Feynman’s blackboard at the time of his death was the following statement:

“What I cannot create I do not understand.”

Hence, an ability to program or, at the very least, an ability to understand how programs work, is today a vital engineering skill that greatly enhances employability.

Simple Physics

We will have a look at this later…

Beam Stress

Finite Element Analysis

You will learn about this in 3rd year

Fluid Dynamics

You will learn about this in 3rd year

Groundwater flow

Many of the examples we have just seen involve computer models of engineering structures.

Modelling is a very important application of programming.

Programming can be used to streamline a series of repeated tasks.(such as routine design)

Uses

Uses

Geotechnics

Uses

Resistance

Force

Angle 1

Angle 2

Uses

Can you imagine how long this would take by hand!!

Uses

Uses

Angle 1: 0-90° in 0.1° increments (900)Angle 2: 0-90° in 0.1° increments (900)810000 combinations...

Uses

Each pixel represents a calculationAutomated using computer programming

We can only formulate a model for a process if we have some understanding of the relevant physics.

This will be a simplification of reality because we are unable to include all possible factors – we try to include those that our engineering judgement deem to be the most relevant.

This is closure – we choose to close out some aspects of reality to focus on others.

Limitations

Verification is our checking to see that our model contains the relevant physics and that we solve the equations that we formulate for the processes in an appropriate way.

Validation is our checking that the outputs from our model match our expectations of the behaviour of the real system.

Verification & Validation

In order to determine the specification for a new bridge you need to estimate the probable 200 year discharge on a river.

The traditional method to do this involves finding the largest event in a year and fitting a statistical distribution to these annual maxima.

The raw data that your firm have been given are daily discharge maxima.

Example

Data

By hand, the procedure that we would follow to construct the annual maxima is something like:

(1) Scroll down through the data finding the first and last values in a particular year;

(2) Sort these data in descending order of discharge and isolate the top value (the annual maximum);

(3) Write this value into a column in a new file with the year in an adjacent column;

(4) Move on to the next year and repeat.

All programming involves is the writing of an algorithm such as that just given into a language that the computer can process and understand.

The particular language we will be using is that for the Matlab software.

Other computer languages tend to work in similar basic ways.

Programming

Known as loops

For…. loops

While… loops

For… loops repeat a set of statements a set number of times.

While… loops keep repeating WHILE some condition holds.

We will cover this more in Week 11

Repeating Stuff

For our example from the discharge dataset, imagine we have 32 years of data, with either 365 or 366 days in a year.

Illustrating algorithms with flow diagrams

Process

Decision

Data

Loop through

NumDays

Currentvalue

Is this > Maximum?

Set Maximum to 0

No

Leap year data

Is current year a leap year?

NumDays = 366

Yes

No

NumDays = 365

Yes

Set Maximum to this new value

On completion of the inner loop write out Maximum for this year

All of the statements that we have written are themselves embedded in a For loop where the counter runs from 1 to 32, meaning that the annual maximum for each year is written out.

Over the next few weeks you will:

• Be taught how to use Matlab and gain an experience in writing Matlab code.

• Be given an engineering problem which you will have to solve using Matlab

Thus, by week 12 you should be able to code up an algorithm yourself.

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Next Week…

Guest lecture on Civil Engineering design

Peer Assessment period