Problem Solving for Engineers

432 Pages·2013·3.966 MB·English

by  Carmichael, David G.

Civil Engineering C Problem
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“Problem solving and systems are given a very broad perspective, encompassing m
key engineering tasks such as design, investigation, decision making, and ic
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optimization. ...the examples and exercises make it an easy-to-read book. The
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exercises are not merely drill-type ones, but also ones that make the reader e
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think—this is to be commended...” for
—Priyan Dias, Senior Professor, University of Moratuwa, Sri Lanka,
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Associate Editor, Civil Engineering and Environmental Systems
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o Engineers
Whatever their discipline, engineers are routinely called upon to develop solutions
to all kinds of problems. To do so effectively, they need a systematic and disciplined b
approach that considers a range of alternatives, taking into account all relevant l
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factors, before selecting the best solution. In Problem Solving for Engineers, David
Carmichael demonstrates just such an approach involving problem definition, m
generation of alternative solutions, and, ultimately, the analysis and selection of a
preferred solution.
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David Carmichael introduces the fundamental concepts needed to think o
David G. Carmichael
systematically and undertake methodical problem solving. He argues that the most l
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rational way to develop a framework for problem solving is by using a systems
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studies viewpoint. He then outlines systems methodology, modeling, and the n
various configurations for analysis, synthesis, and investigation. Building on this,
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the book details a systematic process for problem solving and demonstrates how

problem solving and decision making lie within a systems synthesis configuration.
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Carefully designed as a self-learning resource, the book contains exercises

throughout that reinforce the material and encourage readers to think and apply the E
concepts. It covers decision making in the presence of uncertainty and multiple cri- n
teria, including that involving sustainability with its blend of economic, social, and
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environmental considerations. It also characterizes and tackles the specific prob-
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lem solving of management, planning, and design. The book provides, for the first n
time, a rational framework for problem solving with an engineering orientation.
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K16494
s
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A SPON PRESS BOOK
K16494 cvr mech.indd 1 5/2/13 8:42 AM
Problem
Solving

for
Engineers

Problem
Solving

for
Engineers
David G. Carmichael
A SPON PRESS BOOK
CRC Press
Taylor & Francis Group
6000 Broken Sound Parkway NW, Suite 300
Boca Raton, FL 33487-2742
© 2013 by Taylor & Francis Group, LLC
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Version Date: 20130220
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To my mother and father:
Edna K. Carmichael and A. Fraser Carmichael

Contents
Preface ..................................................................................................................xvii
Author .................................................................................................................xxiii
1. Systems Methodology ...................................................................................1
1.1 Introduction ...........................................................................................1
1.2 Terminology ...........................................................................................2
1.2.1 Abuse of Terminology .............................................................2
1.2.2 Probabilistic, Deterministic ....................................................3
1.2.3 Dynamic, Static ........................................................................3
1.2.4 Discrete, Continuous ...............................................................4
1.3 Origin ......................................................................................................4
1.4 System .....................................................................................................5
1.4.1 Relation between Parts ............................................................6
1.5 Fundamental Variables ........................................................................8
1.5.1 Output, State .............................................................................8
1.5.2 Input, Control .........................................................................10
1.5.3 Disturbance .............................................................................11
1.6 Subsystems ...........................................................................................11
1.7 Environment ........................................................................................14
1.8 System Boundary ................................................................................15
1.8.1 Open and Closed Systems ....................................................15
1.9 System and Behavior Characterization ............................................16
1.9.1 Transient and Steady States ..................................................17
1.9.2 Equilibrium .............................................................................18
1.9.3 Equifinality .............................................................................18
1.9.4 Stability ....................................................................................18
2. Models and Modeling ..................................................................................21
2.1 Introduction .........................................................................................21
2.1.1 Terminology............................................................................23
2.2 Formalism ............................................................................................23
2.3 Hierarchical Multilevel Systems .......................................................25
2.3.1 States, Controls, and Outputs...............................................32
2.3.2 Single Level .............................................................................33
2.4 Staged Systems ....................................................................................34
2.4.1 Project Phases .........................................................................34
vii
viii Contents
2.5 Model Development ...........................................................................40
2.5.1 Scientific Method ...................................................................42
2.5.1.1 Nonrigorous and Management Models ..............47
2.5.2 False Causality .......................................................................50
2.5.3 Adages, Truisms .....................................................................52
2.6 Classification ........................................................................................54
2.7 System Model Terminology ...............................................................67
2.7.1 Terminology............................................................................71
2.7.2 Automatic Control .................................................................72
2.7.3 Fundamental Configurations ...............................................75
3. Some Common System Models .................................................................77
3.1 Introduction .........................................................................................77
3.2 Block Diagrams ...................................................................................77
3.2.1 Junctions ..................................................................................78
3.2.2 Series Subsystems ..................................................................79
3.2.3 Parallel Subsystems ...............................................................79
3.2.4 Feedback ..................................................................................80
3.3 Black Box ..............................................................................................82
3.4 State Equation Models ........................................................................85
3.4.1 Differential Equation Models ...............................................85
3.4.2 Difference Equation Models .................................................89
3.4.3 Partial Differential Equation Models ..................................92
3.4.4 Algebraic (Nondifference) Equation Models .....................93
3.5 Other Forms .........................................................................................94
3.5.1 Networks .................................................................................94
3.5.2 Queuing Models ....................................................................94
3.5.3 Trees .........................................................................................94
3.5.4 Simulation ...............................................................................94
4. Fundamental Configurations Relating to Systems ................................97
4.1 Introduction .........................................................................................97
4.2 Analysis ................................................................................................99
4.2.1 Simulation ...............................................................................99
4.2.2 Prediction, Forecasting .........................................................99
4.2.3 Stability ..................................................................................100
4.2.4 Sensitivity ..............................................................................100
4.2.5 Economic Appraisal ............................................................100
4.2.6 Critical Path Method (CPM) ...............................................101
4.2.7 Reliability ..............................................................................101
4.2.8 Queuing Theory ...................................................................101
4.2.9 Fault Trees, Event Trees .......................................................101
4.2.10 Other Forms of Analysis .....................................................102
4.2.11 Garbage In–Garbage Out ....................................................102
4.2.12 Modeling and Analysis .......................................................102
Contents ix
4.3 Synthesis .............................................................................................103
4.3.1 Confusion in Terminology Usage ......................................104
4.3.2 Conversion to an Iterative Analysis Form ........................105
4.3.3 On-Line/Off-Line .................................................................106
4.4 Investigation ......................................................................................106
4.4.1 State Estimation ....................................................................107
4.4.2 Natural/Artificial Input ......................................................107
4.4.3 Roots ......................................................................................107
4.4.4 On-Line/Off-Line .................................................................108
4.5 Controllability and Observability ..................................................109
4.5.1 Controllability ......................................................................109
4.5.2 Observability ........................................................................109
5. The Synthesis Configuration ...................................................................113
5.1 Introduction .......................................................................................113
5.1.1 Objective ................................................................................113
5.1.2 Constraints ............................................................................114
5.1.3 Variables ................................................................................114
5.1.4 Decision Support ..................................................................115
5.2 Conversion to Iterative Analysis .....................................................115
5.2.1 Steps .......................................................................................117
5.2.2 Planning ................................................................................117
5.2.3 Systems Engineering ...........................................................119
5.2.4 Direct Synthesis ...................................................................120
5.2.5 Theory of Optimal Control Systems .................................120
5.3 Optimal Form of Synthesis ..............................................................121
5.3.1 (Optimal) Synthesis Components ......................................122
5.3.2 Constraints ............................................................................123
5.3.3 Objective ................................................................................123
5.3.4 Probabilistic Systems ...........................................................124
5.3.5 Multiple Objectives ..............................................................125
5.3.6 Alternative Terminology.....................................................125
5.4 Design Examples ...............................................................................126
5.4.1 Structural Design .................................................................126
5.4.2 Earthmoving Operation ......................................................127
5.5 Optimization Techniques ................................................................129
5.5.1 “Gut Feel” Considerations ..................................................129
5.5.2 Numerical Approaches .......................................................130
5.5.3 Calculus .................................................................................130
5.5.4 Pontryagin’s Maximum Principle ......................................130
5.5.5 Dynamic Programming ......................................................130
5.5.6 Mathematical Programming ..............................................130
5.6 Project Planning ................................................................................131
5.6.1 As Synthesis ..........................................................................131
5.6.2 As Iterative Analysis............................................................132