This document proposes optimizing subcontractor selection using a branch and bound algorithm. It reviews existing literature on subcontractor selection models and their limitations. The proposed methodology incorporates new performance indices for cost and time (CPI and TPI) based on subcontractors' past project performances to quantify risk. The objective is to select an optimal combination of subcontractors to minimize overall project time and cost. A numerical example illustrates how the proposed indices would adjust subcontractors' estimated time and cost values.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Factors Influencing Contractors Selection in Construction Projectsijtsrd
Contractor selection is a critical decision that is undertaken by client organizations and is central to the success of any construction project. The process should be conducted prior to the award of contract, characterized by many factors such as contactor’s skills, experience on similar projects, track record in the industry, and financial stability. Selection of the best contractor is a vital process in construction projects. This paper identifies the most important factors that influence the selection of contractors. A questionnaire was distributed to experts in the construction domain to determine the importance of factors that are taken into consideration by the main contractor to select the most suitable contractor. A survey was carried out which was conducted with many experts in the construction field to determine the score of each factor. Dr. V. Sathish Kumar | Dr. P. R. Dhevasena "Factors Influencing Contractors Selection in Construction Projects" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-2 , February 2021, URL: https://www.ijtsrd.com/papers/ijtsrd38262.pdf Paper Url: https://www.ijtsrd.com/engineering/civil-engineering/38262/factors-influencing-contractors-selection-in-construction-projects/dr-v-sathish-kumar
Time-Cost Trade-Off Analysis in a Construction Project Problem: Case Studyijceronline
In construction project, cost and time reduction is crucial in today’s competitive market respect. Cost and time along with quality of the project play vital role in construction project’s decision. Reduction in cost and time of projects has increased the demand of construction project in the recent years. Trade-off between different conflicting aspects of projects is one of the challenging problems often faced by construction companies. Time, cost and quality of project delivery are the important aspects of each project which lead researchers in developing time-cost trade-off model. These models are serving as important management tool for overcoming the limitation of critical path methods frequently used by company. The objective of time-cost trade-off analysis is to reduce the original project duration with possible least total cost. In this paper critical path method with a heuristic method is used to find out the crash durations and crash costs. A regression analysis is performed to identify the relationship between the times and costs in order to formulize an optimization problem model. The problem is then solved by Matlab program which yields a least cost of $60937 with duration 129.50 ≈130 days. Applying this approach, the result obtained is satisfactory, which is an indication of usefulness of this approach in construction project problems.
Negative Total Float to Improve a Multi-objective Integer Non-linear Program...IJECEIAES
This paper presents Multi-Objective Integer Non-Linear Programming (MOINLP) involving Negative Total Float (NTF) for improving the basic model of Multi-Objective Programming (MOP) in case the optimization of the additional cost for Project Scheduling Compression (PSC). Using the basic MOP to solve the more complex problems is a challenging task. We suspect that Negative Total Float (NTF) having an indication to make the basic MOP to solve the more general case, both simple and complex of PSC. The purpose of this research is identifying the conflicting objectives in PSC problem using NTF and improving MOINLP by involving the NTF parameter to solve the PSC problem. The Solver Application, which is an add-in of MS Excel, is used to perform optimization process to the model developed. The results show that NTF has an important role to identify the conflicting objectives in PSC. We define NTF is an automatic maximum value of the activity duration reduction to achieve due date of PSC. Furthermore, the use of NTF as a constraint in MOINLP can solve the more general case for both simple and complex PSC problem. Base on the condition, we state that the basic MOP is still significant to solve the PSC complex problems using MOINLP as a sophisticated MOP technique.
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Factors Influencing Contractors Selection in Construction Projectsijtsrd
Contractor selection is a critical decision that is undertaken by client organizations and is central to the success of any construction project. The process should be conducted prior to the award of contract, characterized by many factors such as contactor’s skills, experience on similar projects, track record in the industry, and financial stability. Selection of the best contractor is a vital process in construction projects. This paper identifies the most important factors that influence the selection of contractors. A questionnaire was distributed to experts in the construction domain to determine the importance of factors that are taken into consideration by the main contractor to select the most suitable contractor. A survey was carried out which was conducted with many experts in the construction field to determine the score of each factor. Dr. V. Sathish Kumar | Dr. P. R. Dhevasena "Factors Influencing Contractors Selection in Construction Projects" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-5 | Issue-2 , February 2021, URL: https://www.ijtsrd.com/papers/ijtsrd38262.pdf Paper Url: https://www.ijtsrd.com/engineering/civil-engineering/38262/factors-influencing-contractors-selection-in-construction-projects/dr-v-sathish-kumar
Time-Cost Trade-Off Analysis in a Construction Project Problem: Case Studyijceronline
In construction project, cost and time reduction is crucial in today’s competitive market respect. Cost and time along with quality of the project play vital role in construction project’s decision. Reduction in cost and time of projects has increased the demand of construction project in the recent years. Trade-off between different conflicting aspects of projects is one of the challenging problems often faced by construction companies. Time, cost and quality of project delivery are the important aspects of each project which lead researchers in developing time-cost trade-off model. These models are serving as important management tool for overcoming the limitation of critical path methods frequently used by company. The objective of time-cost trade-off analysis is to reduce the original project duration with possible least total cost. In this paper critical path method with a heuristic method is used to find out the crash durations and crash costs. A regression analysis is performed to identify the relationship between the times and costs in order to formulize an optimization problem model. The problem is then solved by Matlab program which yields a least cost of $60937 with duration 129.50 ≈130 days. Applying this approach, the result obtained is satisfactory, which is an indication of usefulness of this approach in construction project problems.
Negative Total Float to Improve a Multi-objective Integer Non-linear Program...IJECEIAES
This paper presents Multi-Objective Integer Non-Linear Programming (MOINLP) involving Negative Total Float (NTF) for improving the basic model of Multi-Objective Programming (MOP) in case the optimization of the additional cost for Project Scheduling Compression (PSC). Using the basic MOP to solve the more complex problems is a challenging task. We suspect that Negative Total Float (NTF) having an indication to make the basic MOP to solve the more general case, both simple and complex of PSC. The purpose of this research is identifying the conflicting objectives in PSC problem using NTF and improving MOINLP by involving the NTF parameter to solve the PSC problem. The Solver Application, which is an add-in of MS Excel, is used to perform optimization process to the model developed. The results show that NTF has an important role to identify the conflicting objectives in PSC. We define NTF is an automatic maximum value of the activity duration reduction to achieve due date of PSC. Furthermore, the use of NTF as a constraint in MOINLP can solve the more general case for both simple and complex PSC problem. Base on the condition, we state that the basic MOP is still significant to solve the PSC complex problems using MOINLP as a sophisticated MOP technique.
AN APPROACH FOR SOFTWARE EFFORT ESTIMATION USING FUZZY NUMBERS AND GENETIC AL...csandit
One of the most critical tasks during the software development life cycle is that of estimating the effort and time involved in the development of the software product. Estimation may be performed by many ways such as: Expert judgments, Algorithmic effort estimation, Machine
learning and Analogy-based estimation. In which Analogy-based software effort estimation is the process of identifying one or more historical projects that are similar to the project being developed and then using the estimates from them. Analogy-based estimation is integrated with Fuzzy numbers in order to improve the performance of software project effort estimation during
the early stages of a software development lifecycle. Because of uncertainty associated with attribute measurement and data availability, fuzzy logic is introduced in the proposed model.But hardly a historical project is exactly same as the project being estimated due to some distance associated in similarity distance. This means that the most similar project still has a
similarity distance with the project being estimated in most of the cases. Therefore, the effort needs to be adjusted when the most similar project has a similarity distance with the project being estimated. To adjust the reused effort, we build an adjustment mechanism whose
algorithm can derive the optimal adjustment on the reused effort using Genetic Algorithm. The proposed model Combine the fuzzy logic to estimate software effort in early stages with Genetic algorithm based adjustment mechanism may result to near the correct effort estimation.
An approach for software effort estimation using fuzzy numbers and genetic al...csandit
One of the most critical tasks during the software development life cycle is that of estimating the
effort and time involved in the development of the software product. Estimation may be
performed by many ways such as: Expert judgments, Algorithmic effort estimation, Machine
learning and Analogy-based estimation. In which Analogy-based software effort estimation is
the process of identifying one or more historical projects that are similar to the project being
developed and then using the estimates from them. Analogy-based estimation is integrated with
Fuzzy numbers in order to improve the performance of software project effort estimation during
the early stages of a software development lifecycle. Because of uncertainty associated with
attribute measurement and data availability, fuzzy logic is introduced in the proposed model.
But hardly a historical project is exactly same as the project being estimated due to some
distance associated in similarity distance. This means that the most similar project still has a
similarity distance with the project being estimated in most of the cases. Therefore, the effort
needs to be adjusted when the most similar project has a similarity distance with the project
being estimated. To adjust the reused effort, we build an adjustment mechanism whose
algorithm can derive the optimal adjustment on the reused effort using Genetic Algorithm. The
proposed model Combine the fuzzy logic to estimate software effort in early stages with Genetic
algorithm based adjustment mechanism may result to near the correct effort estimation.
Specific experience criteria in contractor selectionAjay Adhikari
Assessment of specific experience of the contractor through qualification criteria in bidding documents plays a crucial role in the selection of qualified contractor. Prevailing procurement Act and Regulation of the Government of Nepal requires that two items, i.e. projects of similar size and nature and production capacity of key activities of the contractor are examined under this criterion. Though, both the items have their own specific meanings, these are interpreted in many ways as per the evaluator of different public entities. This paper tries to define the meanings of both items and to briefly discuss about how these are interpreted in evaluation by public organizations in Nepal. For this, example of technical evaluation in irrigation project has been taken in this paper. It comes up with some suggestions to harmonize the meaning of these items and their interpretation during evaluation for the selection of qualified contractors.
call for papers, research paper publishing, where to publish research paper, journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJEI, call for papers 2012,journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, research and review articles, engineering journal, International Journal of Engineering Inventions, hard copy of journal, hard copy of certificates, journal of engineering, online Submission, where to publish research paper, journal publishing, international journal, publishing a paper, hard copy journal, engineering journal
QUESTION :
Taylor’s University is intending to build a branch campus in Kota Kinabalu, Sabah. Based on Taylor’s University plan they require the branch campus to be operational in mid-2019. Your quantity surveying firm, Innovative Cost Consultant Sdn. Bhd., of which you are a director, has been appointed to provide advice on the procurement system and the tendering methods that are to be adopted in carrying out the project.
The management of the University has informed you that the following requirements are of priority:
i) Cost to completion to be within the budget fixed.
ii) Timely delivery of the facility in order to commence operation in mid- 2019.
You are required to prepare a report to Taylor’s University recommending the procurement system and the tendering method to be adopted.
In your report you shall consider the procurement systems commonly used. You shall list out and explain the advantages and disadvantages of each system before making your recommendation.
As for the tendering methods, you shall consider all the three methods; i.e. open, selective and direct negotiation methods. Similarly you are to describe the advantages and disadvantages of each method before arriving at your recommendation.
Your report shall clearly explain your reasons for your recommendations.
Based on the above recommendations you are also required to prepare a simple programme or schedule in a form of bar chart showing the various activities commencing from the confirmation of the procurement system until completion of the project.
AN APPROACH FOR SOFTWARE EFFORT ESTIMATION USING FUZZY NUMBERS AND GENETIC AL...csandit
One of the most critical tasks during the software development life cycle is that of estimating the effort and time involved in the development of the software product. Estimation may be performed by many ways such as: Expert judgments, Algorithmic effort estimation, Machine
learning and Analogy-based estimation. In which Analogy-based software effort estimation is the process of identifying one or more historical projects that are similar to the project being developed and then using the estimates from them. Analogy-based estimation is integrated with Fuzzy numbers in order to improve the performance of software project effort estimation during
the early stages of a software development lifecycle. Because of uncertainty associated with attribute measurement and data availability, fuzzy logic is introduced in the proposed model.But hardly a historical project is exactly same as the project being estimated due to some distance associated in similarity distance. This means that the most similar project still has a
similarity distance with the project being estimated in most of the cases. Therefore, the effort needs to be adjusted when the most similar project has a similarity distance with the project being estimated. To adjust the reused effort, we build an adjustment mechanism whose
algorithm can derive the optimal adjustment on the reused effort using Genetic Algorithm. The proposed model Combine the fuzzy logic to estimate software effort in early stages with Genetic algorithm based adjustment mechanism may result to near the correct effort estimation.
An approach for software effort estimation using fuzzy numbers and genetic al...csandit
One of the most critical tasks during the software development life cycle is that of estimating the
effort and time involved in the development of the software product. Estimation may be
performed by many ways such as: Expert judgments, Algorithmic effort estimation, Machine
learning and Analogy-based estimation. In which Analogy-based software effort estimation is
the process of identifying one or more historical projects that are similar to the project being
developed and then using the estimates from them. Analogy-based estimation is integrated with
Fuzzy numbers in order to improve the performance of software project effort estimation during
the early stages of a software development lifecycle. Because of uncertainty associated with
attribute measurement and data availability, fuzzy logic is introduced in the proposed model.
But hardly a historical project is exactly same as the project being estimated due to some
distance associated in similarity distance. This means that the most similar project still has a
similarity distance with the project being estimated in most of the cases. Therefore, the effort
needs to be adjusted when the most similar project has a similarity distance with the project
being estimated. To adjust the reused effort, we build an adjustment mechanism whose
algorithm can derive the optimal adjustment on the reused effort using Genetic Algorithm. The
proposed model Combine the fuzzy logic to estimate software effort in early stages with Genetic
algorithm based adjustment mechanism may result to near the correct effort estimation.
Specific experience criteria in contractor selectionAjay Adhikari
Assessment of specific experience of the contractor through qualification criteria in bidding documents plays a crucial role in the selection of qualified contractor. Prevailing procurement Act and Regulation of the Government of Nepal requires that two items, i.e. projects of similar size and nature and production capacity of key activities of the contractor are examined under this criterion. Though, both the items have their own specific meanings, these are interpreted in many ways as per the evaluator of different public entities. This paper tries to define the meanings of both items and to briefly discuss about how these are interpreted in evaluation by public organizations in Nepal. For this, example of technical evaluation in irrigation project has been taken in this paper. It comes up with some suggestions to harmonize the meaning of these items and their interpretation during evaluation for the selection of qualified contractors.
call for papers, research paper publishing, where to publish research paper, journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJEI, call for papers 2012,journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, research and review articles, engineering journal, International Journal of Engineering Inventions, hard copy of journal, hard copy of certificates, journal of engineering, online Submission, where to publish research paper, journal publishing, international journal, publishing a paper, hard copy journal, engineering journal
QUESTION :
Taylor’s University is intending to build a branch campus in Kota Kinabalu, Sabah. Based on Taylor’s University plan they require the branch campus to be operational in mid-2019. Your quantity surveying firm, Innovative Cost Consultant Sdn. Bhd., of which you are a director, has been appointed to provide advice on the procurement system and the tendering methods that are to be adopted in carrying out the project.
The management of the University has informed you that the following requirements are of priority:
i) Cost to completion to be within the budget fixed.
ii) Timely delivery of the facility in order to commence operation in mid- 2019.
You are required to prepare a report to Taylor’s University recommending the procurement system and the tendering method to be adopted.
In your report you shall consider the procurement systems commonly used. You shall list out and explain the advantages and disadvantages of each system before making your recommendation.
As for the tendering methods, you shall consider all the three methods; i.e. open, selective and direct negotiation methods. Similarly you are to describe the advantages and disadvantages of each method before arriving at your recommendation.
Your report shall clearly explain your reasons for your recommendations.
Based on the above recommendations you are also required to prepare a simple programme or schedule in a form of bar chart showing the various activities commencing from the confirmation of the procurement system until completion of the project.
This presentation is about Clean Development Mechanism and focus is on power sector. key aspects covered are CDM world statistics, Indian scenario, CER prices, CDM project management, etc.
The Ultimate Review of Construction Project Management Methodologies Capterra
Want to know all the different ways managers can approach construction projects? Here's our massive guide to construction project management methodologies.
For more project management articles, check out Catperra's blog here: http://bit.ly/2azJk19
Estimating is a complex process involving collection of available and pertinent information relating to the scope of a project, expected resource consumption, and future changes in resource costs. This process is required in all stages of the project life-cycle.
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The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
11822, 1017 AM Estimating and Managing CostshttpsleoSantosConleyha
1/18/22, 10:17 AM Estimating and Managing Costs
https://leocontent.umgc.edu/content/scor/uncurated/mba/2218-mba670/learning-resourcelist/estimating-and-managing-costs.html?ou=622272 1/27
Estimating and Managing Costs
An important part of a project manager’s job is managing money. All types of
organizations must manage their money well in order to fulfill their mission, including not-
for-profit and government organizations. The tools and methods used to manage money
on a project vary depending on the phase and complexity of the project. This chapter
describes the methods used to estimate the cost of a project, create a budget, and
manage the cost of activities while the project is being executed.
Estimating Costs
Estimating Costs to Compare and Select Projects
During the conceptual phase when project selection occurs, economic factors are an
important consideration when choosing between competing projects. To compare the
simple paybacks or internal rates of return between projects, an estimate of the cost of
each project is made. The estimates must be accurate enough so that the comparisons are
meaningful, but the amount of time and resources used to make the estimates should be
appropriate to the size and complexity of the project. The methods used to estimate the
cost of the project during the selection phase are generally faster and consume fewer
resources than those used to create detailed estimates in later phases. They rely more on
the expert judgment of experienced managers who can make accurate estimates with less
detailed information. Estimates in the earliest stages of project selection are usually made
using estimates based from previous projects that can be adjusted—scaled—to match the
size and complexity of the current project or by applying standardized formulas.
Analogous Estimate
An estimate that is based on other project estimates is an analogous estimate. If a similar
project costs a certain amount, then it is reasonable to assume that the current project
will cost about the same. Few projects are exactly the same size and complexity, so the
estimate must be adjusted upward or downward to account for the difference. The
Learning Resource
1/18/22, 10:17 AM Estimating and Managing Costs
https://leocontent.umgc.edu/content/scor/uncurated/mba/2218-mba670/learning-resourcelist/estimating-and-managing-costs.html?ou=622272 2/27
selection of projects that are similar and the amount of adjustment needed is up to the
judgment of the person who makes the estimate. Normally, this judgment is based on
many years of experience estimating projects, including incorrect estimates that were
learning experiences for the expert.
Analogous Estimate for John’s Move
For example, John asked a friend for advice about the cost of moving. His friend
replied, “I moved from an apartment a little smaller than yours last year and the
distance was about the same. I did it with a fourteen-foot truck. It cost about ...
11822, 1017 AM Estimating and Managing CostshttpsleoBenitoSumpter862
1/18/22, 10:17 AM Estimating and Managing Costs
https://leocontent.umgc.edu/content/scor/uncurated/mba/2218-mba670/learning-resourcelist/estimating-and-managing-costs.html?ou=622272 1/27
Estimating and Managing Costs
An important part of a project manager’s job is managing money. All types of
organizations must manage their money well in order to fulfill their mission, including not-
for-profit and government organizations. The tools and methods used to manage money
on a project vary depending on the phase and complexity of the project. This chapter
describes the methods used to estimate the cost of a project, create a budget, and
manage the cost of activities while the project is being executed.
Estimating Costs
Estimating Costs to Compare and Select Projects
During the conceptual phase when project selection occurs, economic factors are an
important consideration when choosing between competing projects. To compare the
simple paybacks or internal rates of return between projects, an estimate of the cost of
each project is made. The estimates must be accurate enough so that the comparisons are
meaningful, but the amount of time and resources used to make the estimates should be
appropriate to the size and complexity of the project. The methods used to estimate the
cost of the project during the selection phase are generally faster and consume fewer
resources than those used to create detailed estimates in later phases. They rely more on
the expert judgment of experienced managers who can make accurate estimates with less
detailed information. Estimates in the earliest stages of project selection are usually made
using estimates based from previous projects that can be adjusted—scaled—to match the
size and complexity of the current project or by applying standardized formulas.
Analogous Estimate
An estimate that is based on other project estimates is an analogous estimate. If a similar
project costs a certain amount, then it is reasonable to assume that the current project
will cost about the same. Few projects are exactly the same size and complexity, so the
estimate must be adjusted upward or downward to account for the difference. The
Learning Resource
1/18/22, 10:17 AM Estimating and Managing Costs
https://leocontent.umgc.edu/content/scor/uncurated/mba/2218-mba670/learning-resourcelist/estimating-and-managing-costs.html?ou=622272 2/27
selection of projects that are similar and the amount of adjustment needed is up to the
judgment of the person who makes the estimate. Normally, this judgment is based on
many years of experience estimating projects, including incorrect estimates that were
learning experiences for the expert.
Analogous Estimate for John’s Move
For example, John asked a friend for advice about the cost of moving. His friend
replied, “I moved from an apartment a little smaller than yours last year and the
distance was about the same. I did it with a fourteen-foot truck. It cost about ...
CHAPTER Modeling and Analysis Heuristic Search Methods .docxtiffanyd4
CHAPTER
Modeling and Analysis: Heuristic
Search Methods and Simulation
LEARNING OBJECTIVES
• Explain the basic concepts of simulation
and heuristics, and when to use them
• Understand how search methods are
used to solve some decision support
models
• Know the concepts behind and
applications of genetic algorithms
• Explain the differences among
algorithms, blind search, and heuristics
• Understand the concepts and
applications of different types of
simulation
• Explain what is meant by system
dynamics, agent-based modeling, Monte
Carlo, and discrete event simulation
• Describe the key issues of model
management
I n this chapter, we continue to explore some additional concepts related to the model base, one of the major components of decision support systems (DSS). As pointed out in the last chapter, we present this material with a note of caution: The purpose
of this chapter is not necessarily for you to master the topics of modeling and analysis.
Rather, the material is geared toward gaining familiarity with the important concepts
as they relate to DSS and their use in decision making. We discuss the structure and
application of some successful time-proven models and methodologies: search methods,
heuristic programming, and simulation. Genetic algorithms mimic the natural process of
evolution to help find solutions to complex problems. The concepts and motivating appli-
cations of these advanced techniques are described in this chapter, which is organized
into the following sections:
10.1 Opening Vignette: System Dynamics Allows Fluor Corporation to Better Plan
for Project and Change Management 436
10.2 Problem-Solving Search Methods 437
10.3 Genetic Algorithms and Developing GA Applications 441
10.4 Simulation 446
435
436 Pan IV • Prescriptive Analytics
10.5 Visu al Interactive Simulatio n 453
10.6 System Dynamics Modeling 458
10.7 Agents-Based Mode ling 461
10.1 OPENING VIGNETTE: System Dynamics Allows Fluor
Corporation to Better Plan for Project and Change
Management
INTRODUCTION
Fluor is an engineering and construction company with over 36,000 employers spread
over several countries worldwide . The company's net income in 2009 amounted to
about $680 million based on total revenue o f $22 b illion. As part of its operations, Fluor
manages varying sizes of projects that are subject to scope changes, design changes, and
schedule changes.
PRESENTATION OF PROBLEM
Fluor estimated that changes accounted for about 20 to 30 percent of revenue . Most
changes were due to secondary impacts like ripple effects, disruptions, and p roductivity
loss. Previously, the changes were collated and reported at a later period and the burden
of cost allocated to the stakeholder responsible. In certain instances when late su rprises
abou t cost and project schedule are attributed to clients, it causes friction between
clients and Fluor, w hich eventually affect future business dealings. .
CHAPTER Modeling and Analysis Heuristic Search Methods .docxmccormicknadine86
CHAPTER
Modeling and Analysis: Heuristic
Search Methods and Simulation
LEARNING OBJECTIVES
• Explain the basic concepts of simulation
and heuristics, and when to use them
• Understand how search methods are
used to solve some decision support
models
• Know the concepts behind and
applications of genetic algorithms
• Explain the differences among
algorithms, blind search, and heuristics
• Understand the concepts and
applications of different types of
simulation
• Explain what is meant by system
dynamics, agent-based modeling, Monte
Carlo, and discrete event simulation
• Describe the key issues of model
management
I n this chapter, we continue to explore some additional concepts related to the model base, one of the major components of decision support systems (DSS). As pointed out in the last chapter, we present this material with a note of caution: The purpose
of this chapter is not necessarily for you to master the topics of modeling and analysis.
Rather, the material is geared toward gaining familiarity with the important concepts
as they relate to DSS and their use in decision making. We discuss the structure and
application of some successful time-proven models and methodologies: search methods,
heuristic programming, and simulation. Genetic algorithms mimic the natural process of
evolution to help find solutions to complex problems. The concepts and motivating appli-
cations of these advanced techniques are described in this chapter, which is organized
into the following sections:
10.1 Opening Vignette: System Dynamics Allows Fluor Corporation to Better Plan
for Project and Change Management 436
10.2 Problem-Solving Search Methods 437
10.3 Genetic Algorithms and Developing GA Applications 441
10.4 Simulation 446
435
436 Pan IV • Prescriptive Analytics
10.5 Visu al Interactive Simulatio n 453
10.6 System Dynamics Modeling 458
10.7 Agents-Based Mode ling 461
10.1 OPENING VIGNETTE: System Dynamics Allows Fluor
Corporation to Better Plan for Project and Change
Management
INTRODUCTION
Fluor is an engineering and construction company with over 36,000 employers spread
over several countries worldwide . The company's net income in 2009 amounted to
about $680 million based on total revenue o f $22 b illion. As part of its operations, Fluor
manages varying sizes of projects that are subject to scope changes, design changes, and
schedule changes.
PRESENTATION OF PROBLEM
Fluor estimated that changes accounted for about 20 to 30 percent of revenue . Most
changes were due to secondary impacts like ripple effects, disruptions, and p roductivity
loss. Previously, the changes were collated and reported at a later period and the burden
of cost allocated to the stakeholder responsible. In certain instances when late su rprises
abou t cost and project schedule are attributed to clients, it causes friction between
clients and Fluor, w hich eventually affect future business dealings. ...
COMPARATIVE STUDY OF SOFTWARE ESTIMATION TECHNIQUES ijseajournal
Many information technology firms among other organizations have been working on how to perform estimation of the sources such as fund and other resources during software development processes. Software development life cycles require lot of activities and skills to avoid risks and the best software estimation technique is supposed to be employed. Therefore, in this research, a comparative study was conducted, that consider the accuracy, usage, and suitability of existing methods. It will be suitable for the project managers and project consultants during the whole software project development process. In this project technique such as linear regression; both algorithmic and non-algorithmic are applied. Model, composite and regression techniques are used to derive COCOMO, COCOMO II, SLIM and linear multiple respectively. Moreover, expertise-based and linear-based rules are applied in non-algorithm methods. However, the technique needs some advancement to reduce the errors that are experienced during the software development process. Therefore, this paper in relation to software estimation techniques has proposed a model that can be helpful to the information technology firms, researchers and other firms that use information technology in the processes such as budgeting and decision-making processes.
Optimizing Time and Effort Parameters of COCOMO II Using Fuzzy Multi-objectiv...TELKOMNIKA JOURNAL
Estimating the efforts, costs, and schedules of software projects is a frequent challenge to software development projects. A bad estimation will result in bad management of a project. Various models of estimation have been defined to complete this estimate. The Constructive Cost Model II (COCOMO II) is one of the most famous models as a model for estimating efforts, costs, and schedules. To estimate the effort, cost, and schedule in project of software, the COCOMO II uses inputs: Effort Multiplier (EM), Scale Factor (SF), and Source Line of Code (SLOC). Evidently, this model is still lack in terms of accuracy rates in both efforts estimated and time of development. In this paper, we introduced to use Gaussian Membership Function (GMF) of Fuzzy Logic and Multi-Objective Particle Swarm Optimization (MOPSO) method to calibrate and optimize the parameters of COCOMO II. It is to achieve a new level of accuracy better on COCOMO II. The Nasa93 dataset is used to implement the method proposed. The experimental results of the method proposed have reduced the error downto 11.89% and 8.08% compared to the original COCOMO II. This method proposed has achieved better results than previous studies.
1. 1
OPTIMIZING SUB-CONTRACTOR SELECTION
BY BRANCH AND BOUND ALGORITHM
Bowen Deng
Bhanu Pratap Singh Sandu
(Group 33)
Graduate Students, Department of Civil and Environmental Engineering,
University of Illinois, Urbana-Champaign
Email: bowend3@illinois.edu , bsandu2@illinois.edu
Khaled A El-Rayes
Professor
University of Illinois, Urbana-Champaign
Email: elrayes@illinois.edu
2. 2
ABSTRACT
Obviously it is a good news for a construction company to win the bid for a huge potential amount
of profit. However, when they lack the capability to finish the construction activities by themselves
it would be another story. Usually they have to choose appropriate subcontractors to do the
unfinished job. Subcontractors may be various from experience, cost, time, quality and many other
factors which can have impacts on the selection by a main contractor on a certain project. How to
choose subcontractors wisely has become a hotspot issue to many construction companies. Many
literatures have recorded the attempts to select subcontractors with a consideration of as many
possible factors as they can. Some of them are connected with mathematical models and algorithms.
This paper is on the purpose of optimizing the selection of subcontractors on the basis of existing
methods---the Branch and Bound algorithm. So a literature review is given after stating the
problem. And a numerical example is also included to better explain the optimization process.
PROBLEM STATEMENT
Nowadays construction companies are working so hard to make a living through the fierce
competition. It is always a good news for a construction company to win a bid by defeating all the
3. 3
competitors. However, as the rapid development of construction industry, construction projects
nowadays are becoming bigger and harder than before.
Main contractors in today’s construction industry cannot complete the entire construction projects
on their own. Some projects are so complicated that they need contractors with specific previous
working experience. So it is necessary to subcontract some parts of the construction projects to
competitive subcontractors.
Here comes the question, how to choose subcontractors wisely? Many literatures have already
recorded attempts to assisting the selection of subcontractors by using various mathematical
algorithms and computer models. But they all have their limitations. Some of them are not as
accurate as people think. So in this paper, the main purpose is to optimize the existing method by
doing literature review and modifications.
To optimize the selection process is so important that it should catch people’s attention. It is known
that there are so many candidates in the market with different construction background and
experience. If the main contractor chooses an appropriate subcontractor, the construction activity
could be completed ahead of schedule and under the budget. Instead, a wrong candidate may result
4. 4
in various possible troubles like short of experience, poor construction quality or some other
potential conflicts. Therefore, the optimization of subcontractor selection is of great significance
to all the main contractors.
This paper selects a branch and bond algorithm as a basis to explore the further optimization of
subcontractors in construction industry. The issue is to review the original models and equations,
and find out which part of the original model can be improved. Although there are many possible
factors which may have impacts on the selection like the relationship between contractors, the
working experience and construction quality, the paper only chooses the most important factors to
do the optimization, project schedule and overall cost. Construction quality is not discussed here
because it is too subjective to get a quantitative measure.
OBJECTIVES
The objective of this paper is to study the existing subcontractor selection method by doing
literature review. After that try to optimize it by make some modifications to the original models
and develop a new model to solve the problem.
5. 5
BRANCH AND BOUND ALGORITHM (BB)
In this paper, a Branch and Bound algorithm is selected as the basis of optimization. The Branch
and Bound algorithm (BB) is an algorithm designed for optimization problems. As it is named, the
Branch and Bound algorithm (BB) is used to present all the feasible solutions of a problem into
branches of a tree. And the optimal solution could be found through those branches. The basic idea
of the Branch and Bound algorithm (BB) is the solution space reduction. A problem which has
several constraints can be treated like a certain space. The solution is in that space. To find out the
solution among other options rapidly, the space should be reduced. When operating the Branch
and Bound algorithm (BB), the space of all the feasible solutions is divided into many subsets like
branches. And calculate the thresholds or the upper and lower bounds for those feasible solutions
in each branch. After that, abandon those branches whose bonds are already out of the range. Then
the solution space will be decreased. Keep doing this until find out the optimal solution.
The selection of subcontractors can be transferred into this Branch and Bound algorithm (BB)
problem. Each subcontractor has a construction time and project cost. They are put into the Space.
After solution space reduction, the optimal subcontractor can be found by using different bonds.
6. 6
LITERATURE REVIEW
1. The paper by (Talluri, Baker, & Sarkis, 1999) first realize the importance of selecting
appropriate partner for the job and propose a two phase quantitative framework to optimize
the partner selection problems. In the first phase, data envelopment analysis is utilized to
determine possible candidates for each type of work. Then in the second phase, an integer
goal programming model is introduced to select which possible candidate is the most
appropriate. But there are some limitations exposed during the optimization process. When
imputing initial data, the data may not be that accurate because it is obtained via an
optimization which makes the solution a sub-optimal one. Also when considering the
factors affecting the partner selection, the realistic situation seems more complicated than
the assumptions. So this model needs further modifications to be applied to the current
situation.
2. The paper by (Ip, Yung, & Wang, 2003) presents a branch and bound algorithm solution
for sub-contractor selection in agile manufacturing environment. They embed the project
7. 7
schedule into the branch and bound algorithm models. To solve this problem, they separate
it into two levels. The first level is to use branch and bonds to choose optimal
subcontractors. Then the second level is to schedule the project and minimize the loan
interest.
At the beginning they define a concept called objective value Z(x) considering both money
requirement and project completion time. Then they sequence the activities according to
the means of the bid costs. After initial bounds and search index are set, they start to use
Branch and Bound Algorithm to search for the optimal solution. The principle of Branch
and Bound Algorithm (BB) is the solution space reduction by cutting branches. In each
branch, one activity is assigned to a candidate contractor. After calculating the objective
value Z(x) they compare it with the Bound. The branch would be abandoned if the objective
value Z(x) is more than the Bound. If it is not, the branch would go on and go to the next
step.
8. 8
PROPOSED METHODOLOGY
The proposed methodology incorporates two new performance indices for cost and time namely
Cost performance index (Cpi) and Time performance index (Tpi).
The way these indices would be quantified is purely based on past performances of the
subcontractors. Now this past information is really important for our factors. Generally, if a
contractor has a working experience with multiple subs, the contractor can easily acquire this
information. Even if there is a sub-contractor who is working for the first time with the contractor,
this would not necessarily mean that the sub-contractor is new to the field, just that it is the first
time the duo is working together. Even for sub-contractors like this the historical data can be
obtained by analyzing their past construction works. This way no assumptions would have to be
made and all the data would be easily available too. But if a sub-contractor is however new to the
construction field, this model cannot be applied to them. But it is very unlikely that a contractor
will even consider an inexperienced sub-contractor for such a huge project, almost all the sub-
contractors considered would be highly experienced professionals. And therefore we do not need
to worry about applying our model to brand new sub-contractors.
9. 9
The concept is that, for every 1% increase or decrease in the scheduled cost or time of the
subcontractors, based on the past performances, we would assign them an increased or decreased
Cpi and Tpi. Now these past records taken would be averaged and used. For example, if the
subcontractor has been delayed by 10% time for one project and 5% time for another, the average
taken would be 7.5%. And thus an increase in the bid time for this subcontractor would be made
by 7.5%. The same would be done for the cost aspect based on their cost performances.
The main objective here is to select the optimal combination of subcontractors so that we can
minimize the time and cost for all the jobs in the project.
For example, if we were to select one of three subcontractors for an activity (say excavation) we
would have the following information:
Subcontractor 1 2 3
Job Excavation Excavation Excavation
Time 5 days 4 days 3 days
Cost $20,000 $22,500 $25,000
10. 10
However, after applying Cpi and Tpi, these numbers will change:
Subcontractor 1 2 3
Job Excavation Excavation Excavation
Time 5 days 4 days 3 days
Cost $20,000 $22,500 $25,000
Past performances
Avg time delay of
10%
Avg cost increase by
10%
Avg time cut short by
5%
Avg cost increase by
5%
Avg time cut short by
10%
On average always on
budget
Cpi influenced Cost
value
20k x Cpi =
20k x 1.1 = 22k
22k x Cpi =
22k x 1.05 = 23.1k
25k x Cpi =
25k x 1 = 25k
Tpi influence Time
value
5 x Tpi =
5 x 1.1 = 5.5 days
4 x Tpi =
4 x 0.95 = 3.8 days
3 x Tpi =
3 x 0.9 = 2.7 days
Now that we have seen what the factors are about, we will look into the existing model
proposed by Ip, Yung and Wang and how we influence and further optimize it.
Since sub-projects contracted by partners consist of an activity network with precedence, each
partner works in the project as a ring in a chain (Elmaghraby, 1977). Because the main contractor
11. 11
gets paid in installments, this can be considered as the cash flow. This investment cannot always
meet the requirements from the sub-project contractors and thus the main contractor often takes a
loan of certain amount from the bank and pay them interest. Because of the complexity of the
selection of the sub-contractor, it is not easily solved by general mathematical programming
methods. However, Branch and Bound method is powerful tool to solve this kind of combinatorial
optimizations (Taha, 1975).
The model proposed by Ip, Yung and Wang is described as follows:
1. Problem and model of sub-contractor selection
2. Inefficient and ideal candidates
3. Branch and bound algorithm embedded project scheduling
4. Numerical analysis
Problem and model of sub-contractor selection:
All the notations are listed below:
n = number of jobs included in project
D = due-date of project
12. 12
b = penalty cost for tardiness of a period
a = rate of first payment to sub-contractors
r = interest rate of loan from bank
f(t) = cash flow paid to the main contractor by the project owner in period t
F = total investment for the project from owner
(i.k) = connected job pair
H = set of all connected job pairs
mi = number of candidates bidding for job i
bij = bid cost of candidate j for job i
pij = bid completion time of candidate j for job i
Cpij = cost performance index of candidate j for job i
Tpij = time performance index of candidate j for job i
(The above mentioned factors are what we plan to introduce to the model).
cn = completion time of final job, i.e. the completion time of the project
xij = 0–1 assignment variable. xij = 1 means the job i is contracted to j
13. 13
x = matrix variable for all xij: It is a completed selection
Z(x) = objective value achieved by selection x
si = beginning time of job i in selection x
ci = completion time of job i in selection x
Ok = index of job sequenced at kth place with the kth larger mean cost
I(Ok) = assigned candidate index of job Ok (the job at the k-place in the sequence)
(Ip, Yung, & Wang, 2003)
The sub-contractor selection problem is stated as: say the main contractor wins a bid for a big
project and is not able to complete the whole project by its own capacity and resources, therefore
subcontracting a number of sub projects. The objective here is to select an optimal combination of
sub-contractors for all the jobs such as to minimize the total cost and time.
Defining the variables,
xij(t) =
1, job i is contracted to candidate j and begins at period t
0, otherwise
14. 14
Then the problem can be described by the following model (adding Cpij and Tpij where needed)
(Ip, Yung, & Wang, 2003)
The factors Cpij and Tpij have been added to the existing models and were not a part of the model
before.
So whenever the model uses a cost factor, we multiply the cost performance index to modify and
further optimize the solution. Same is done for the time factor.
Inefficient and ideal candidates:
Since the size of the solution space is,
It clearly shows that even for a small scale problem with 10 jobs and 3 candidates the solution
min
x
Z(x) = bijCpij xij
t=1
cn
∑
j=1
mi
∑
i=1
n
∑ (t)
+r α bijCpij xij (τ )+ (1−α) bijCpij xij (τ − pijTpij )− f (τ )
τ =1
t
∑
τ =1
t
∑
j=1
mi
∑
i=1
n
∑
τ =1
t
∑
j=1
mi
∑
i=1
n
∑
⎡
⎣
⎢
⎤
⎦
⎥
t=1
cn
∑
+
+ β cn − D[ ]+
s.t.
xij (t) = 1,i = 1,2,...,n,
t=1
cn
∑
j=1
mi
∑
(t + pijTpij )xij (t)
t=1
cn
∑
j=1
mi
∑
≤ txkj (t),∀(i,k) ∈H
t=1
cn
∑
j=1
mk
∑
(t + pnjTpij )xnj (t) = cn
t=1
cn
∑
j=1
mn
∑ ,
xij (t) = 1or0,∀i, j,t,
N =
i=1
n
Πmi
15. 15
space is very large, 310
= 59,049. This is too high a number and therefore a reduction in the solution
space is required. This reduction comes in the format of a theorem used by Ip et al, which says,
the candidate j of job I is inefficient if there exists a candidate k for the same job with,
bik £ bij, pik < pij or bik < bij, pik £ pij (Ip, Yung, & Wang, 2003).
Using this theorem, we can ignore all inefficient candidates without the loss of an optimal solution
and thus the solution space is reduced considerably.
Branch and bound algorithm embedded project scheduling:
The idea of the proposed branch and bound algorithm is to select the optimal partner combination
by branch and bound at the first level of algorithm and to schedule all jobs with a fixed partner
combination at the second level (Ip, Yung, & Wang, 2003).
Numerical Analysis:
The algorithm was coded by Ip et al on FORTRAN and run on a Pentium II/366 machine and
satisfactory results were achieved. The example they took was a real life construction problem of
the construction of a coal-fire power station. Atotal of 16 jobs were set and a due date of 36 months
was also set. Additional details are: loan interest rate = 0.6% per month, 55% payment for all jobs
16. 16
will be made in advance and the rest of the payment when the job was done. A total investment of
$72.75 million was to be made.
Table 1: The job list and the cost and time values for each job
Number Job Cost (million $) Time (months)
1 Total design of system 2.75 6
2 Design of railway for coal 0.3 4
3 Construction of railway 3.75 10
4 Design of boiler system 1.75 6
5 Manufacturing of boilers 18.5 12
6 Design of buildings 2 6
7 Construction of buildings 6.5 10
8 Design of generators 1.5 6
9 Design of electric transmission 1.5 6
10 Manufacturing of generators 13.5 12
11 Assembling of boilers 1 3
12 Manufacturing of transmission equipment 6.75 12
13
Design and assembly of computer control
system 7 16
14 Assembling of generators 1.25 3
15 Assembling of transmission system 1.75 3
16 System inspection and test running 3 5
17. 17
Table 2: Number of candidates for the job
Job Number of candidates
1 4
2 6
3 5
4 2
5 2
6 7
7 4
8 8
9 3
10 4
11 5
12 3
13 6
14 3
15 4
16 2
Table 3: List of candidates for each job
Job number
Candidate
code Cost (million $)
Time
(months)
A1 2.7 4
A2 2.4 5
1 A3 2.175 5
A4 1.8 6
20. 20
L3 7.2 10
M1 4.5 18
M2 5.7 17
M3 7.5 12
13 M4 8.25 10
M5 9 8
M6 7.2 15
N1 1.2 4
14 N2 1.8 2
N3 1.5 3
P1 1.8 2
15 P2 1.5 3
P3 1.2 3
P4 0.9 5
16 Q1 2.4 6
Q2 3 5
Now, the model runs the mentioned values and tries to optimize the sub-contractor selection based
on the values of their individual cost and time of completion. We can clearly see here how much
focused this model is on these time-cost values.
So when run by the model, an optimal selection of sub-contractors for respective jobs is achieved.
21. 21
Table 4: The sub-contractors of optimal solution
The solution by Ip et al of above data set with the model resulted in the following optimal solution:
Job
number
Sub-
contractor
Cost
(million $) Proc. Time
Beginning
time
Time of
completion
1 A1 2.7 4 1 5
2 B2 0.3 3 1 4
3 C5 2.775 13 4 17
4 D2 1.8 4 5 9
5 E1 18 12 13 25
6 F7 1.05 8 9 17
7 G2 2.1 4 9 13
8 H6 6.75 8 17 25
9 I3 1.8 4 13 17
10 J3 12 13 14 27
11 K3 1.05 2 25 27
12 L1 6 12 17 29
13 M3 7.5 12 19 31
14 N2 1.8 2 27 29
15 P1 1.8 2 29 31
16 Q2 3 5 31 36
In this solution we can see that the optimal selection of sub-contractors is satisfactory since all the
jobs are completed within the duration of 36 months and with a budget of $70.5 million. So the
contractor makes a profit of $2.25 million.
22. 22
But imagine if some of these sub-contractors fail to deliver on time or within the budget. If that
happens, and there is a reasonable probability that it could happen, the contractor’s profit will end
up being reduced and he might have to pay the tardiness penalty as well. This would seriously
impact the profit of the project and make the entire project a failed venture.
Now here is where our factors for cost and time performance (Cpi and Tpi) come in. We multiply
the existing time and cost promised by each sub-contractor by their individual cost and time
performance index. This gives us their updated cost and time for completion of the activity.
For example, for job 1 four sub-contractors had submitted their cost and time values as below:
Job number
Candidate
code Cost (million $)
Time
(months)
A1 2.7 4
A2 2.4 5
1 A3 2.175 5
A4 1.8 6
But this model did not consider their past performance, and now if we do, suppose for example,
all four candidates have the following past performances:
23. 23
Candidate code Time performance Cost performance
A1
On average the candidate has
been 5% behind schedule;
Tpi = 1.05
On average the candidate has
always been on budget;
Cpi = 1
A2
On average the candidate has
been 10% behind schedule;
Tpi = 1.10
On average the candidate has been
5% over budget;
Cpi = 1.05
A3
On average the candidate has
been 5% ahead of schedule;
Tpi = 0.95
On average the candidate has been
3% over budget;
Cpi = 1.03
A4
On average the candidate has
been 10% ahead of schedule;
Tpi = 0.9
On average the candidate has been
10% over budget;
Cpi = 1
And thus the new values for time and cost of the four candidates will be:
Job number
Candidate
code
Cost (million $)
Cpi Influenced cost
Time (months)
Tpi influenced time
A1 2.7 x 1 = 2.7 4 x 1.05 = 4.2
1 A2 2.4 x 1.05 = 2.52 5 x 1.10 = 5.5
A3 2.175 x 1.03 = 2.24 5 x 0.95 = 4.75
A4 1.8 x 1.1 = 1.98 6 x 0.9 = 5.4
24. 24
Now if these values are used to optimize the selection, it will definitely influence the results and
new sub-contractors may get selected based on their efficient past performances.
This is because the model heavily focuses on the cost and time performance of each candidate, and
if those values are influenced, the result will undoubtedly be influenced and further optimized
because these new values would be more realistic and accurate. By using these factors to update
the model, we somewhat eliminate any surprises that might come from the sub-contractors and
make sure that our end profit is secure and maximum. This is the whole idea behind our updated
model. Because the model is so heavily focused on the values of cost and time, if we influence
those values, we will influence the result. Similarly, if we can further optimize the time and cost
values, we will further optimize the model and thus the final solution.
25. 25
EXPECTED CONTRIBUTION
The existing model is designed to select an optimal group of sub-contractors based on their time
and cost bids for the job. However, the model doesn’t take into account the historical data of the
past performances of these individual candidates. That is what this paper proposes. The
contribution we expect to impart is that when optimizing such models to get such a group of sub-
contractors, each of them be judged on the past performances too. This way many judgmental
errors and time delays can be avoided even before the construction starts.
If we look at the industry at large, this would be beneficial to any party which tries to optimize its
sub-contractor selection by updating their model with cost and time performance indices. It would
result in a huge amount of cost savings and more importantly the saving of time.
26. 26
References
Elmaghraby, S. E. (1977). Activity Networks - Project Planning and control by Network
Models. New York, NY, USA: Wiley, New York.
Ip, W., Yung, K., & Wang, D. (2003). Branch and Bound algorithm for sub-contractor selection
in agile manufacturing environment. The Hong Kong Polytechnic Unversity ,
Department of Manufacturing Engineering. Hong Kong: Elsevier.
Taha, H. (1975). Integer Programming Theory, Applications and Computations. New York,
NY, USA: Academic Press.
Talluri, S., Baker, R., & Sarkis, J. (1999). A framework for designing efficient value chain
networks. International Journal of Production Economics, Elsevier.