Minimum Project Cost Research Articles

A Local Line Optimization Model for Urban Rail Considering Passenger Flow Allocation

It is important to strengthen the research on urban rail transit (URT) existing line renovation strategies. In this paper, we investigate the optimization of bottlenecks that are less attractive but have strong travel demand in existing URT networks. A URT local line optimization model is constructed. The maximum passenger flow and minimum project cost are chosen as the optimization objective for the benefit of both passengers and operators, and several actual constraints are considered in the proposed model, such as the station interval. In order to obtain higher computational efficiency and accuracy, a passenger flow allocation method is embedded in a genetic algorithm with elitist preservation. Taking the local network of the Beijing URT as a case study, the calculation results show that the designed algorithm can quickly and effectively obtain the optimal solution, and the generated local line scheme is able not only to meet the regional travel demand, but also to optimize the connection relationship of the existing URT network. This study can provide a reference method for increasing the attraction of URT and optimization of existing URT networks.

Multi-objective Stochastic Time-cost-quality Optimization for Construction Projects Based on the Reliability Theory

The management problem of projects has received more attention in recent years due to the trend towards increasing complexity in the construction industry. Time, cost and quality are three important aspects of project management. Thus, achieving a balance among the minimum project time, minimum project cost and maximum project quality can determine the success of a construction project. Moreover, the time of a project not only affects the cost but also the quality of the project. However, most research usually ignores the influence of the stochastic environments and considers the time of the project as a constant. Thus, this paper explores a new method to measure the stochastic time based on system reliability theory. Two stochastic time-cost-quality tradeoff optimization models are formulated for two construction projects with considering crossover operations or not, respectively. The optimization of the time reliability-cost-quality tradeoff for the project is achieved by using the particle swarm optimization algorithm. Finally, two illustrative examples are used to demonstrate the effectiveness of the two proposed models for a construction project with four activities.

AN ANALYSIS OF GREEN BUILDING COSTS USING A MINIMUM COST CONCEPT

Green buildings are known for yielding a better indoor habitat, saving energy and protecting the environment. However, they require greater investment than conventional buildings. Green buildings can be classified at different levels ranging through certified, silver, gold and platinum. The classification chosen is likely to affect project costs. Adopting a platinum level of green building specifications tends to incur the highest project costs. While with gold, silver and certified levels expenditure will be reduced accordingly. The actual degree of project cost differences also depends on additional factors, such as site location, design specifications, construction condition, material and equipment selection and LEED consultant expertise. Construction budgeting represents a crucial factor for project owners developing green buildings. This research presents a method for determining the minimum project costs of green building developments. The processes and steps to be completed in determining such minimum project costs are presented based on a case study of a learning centre building which received LEED platinum certification. It was found that choosing certified and silver levels has an indifferent effect on project costs, whereas expenditure increases exponentially with gold and platinum levels of certification.

Time-cost optimization model proposal for construction projects with genetic algorithm and fuzzy logic approach

DOI: 10.7764/RDLC.18.3.554 Considering the construction industry holds ten percent on average in the gross national product over the world, the importance of efficient use of resources emerges. To alleviate the possibility of the risk factors and various uncertainties' negative impact on the project, the usage of the scheduling tools should be supported for planning as well as risk management. In today's construction perspective, the quality is not a primary objective; construction projects have to be completed within the cost and duration limits. During the construction progress, the inserting of extra activities affects to construction delays. Project success; from the planning stage to the completion of the building, it is possible to plan the resources, use them efficiently, and realize the determined time and cost objectives. In this study, a model is developed by using a fuzzy logic approach and genetic algorithm in order to provide time-cost optimization in construction projects under uncertainties. Firstly, fuzzy sets are used to take into account the effects of time and cost uncertainties on construction works. Fuzzy sets are used to model uncertainties, and the genetic algorithm is used to acquire minimum Project cost and duration. Thus, by establishing a fuzzy time-cost optimization model, optimum time-cost results are obtained according to different risk levels determined by the decision-makers. At the final stage, Pareto fronts from different risk levels that contain both minimum costs and durations are obtained and plotted.

Modelo difuso de apoyo para la selección de contratistas en obras de construcción

The major employer in Turkish construction sector is the public and the selection of contractor within the public sector is implemented in accordance with the regulations. Sound utilization of public resources in developing countries with certain development plans is very important; also the establishment of transparency and competition in public procurement increases saving and encourages the correct usage of tax revenues. Within this context, keeping the quality while increasing the level of competition and having successful public investments will be possible by selecting the most ideal contractor. The key for success in public investments on construction projects is to provide the minimum project cost with the ability to reach at the required quality level within the determined period; and therefore some criteria other than the amount of bid should be determined for construction tenders and the evaluation should be one within the scope of such criteria in order to select the contractor. A fuzzy logic methodology is used within the scope of this study, in which the criteria except the price are evaluated with the help of a model and the verbal terms are modeled.

Analisis Waktu Pelaksanaan Proyek Konstruksi dengan Variasi Penambahan Jam Kerja

Time and cost greatly affect the success and failure of a project. Measure of the success of a project is usually seen short turnaround time at minimal cost without leaving the quality of result. Systematic project management is required to ensure the project implementation time in accordance with the contract or even faster that the cost could provide benefits. And also avoid any penalties due to delays in project completion. Purpose of this study is to calculate the change of cost and time of implementation project with variations additional hours of 1 hour to 4 hours of overtime by using microsoft project programs. And to compare the results between the cost of fines with changes in costs before and after the addition of working hours (overtime). The results of this study have shown that (1) The minimum project cost was obtained at the time of normal conditions without the addition of overtime hours Rp 25,923,636,641.50 while for the minimum time the project was obtained on the addition of 4 hours is 197.84 days of normal duration of 217 days with the addition of cost of Rp 215,838,008.94 from the normal total cost of Rp. 25,923,636,641.50 to Rp 26,139,474,650.44 (2) Additional hours worked best option is additional three hours of work, in this condition the costs Rp 139,469,427.19 with profits generated Rp 327 156 .032,35.

Feasible Task Schedules With Minimum Project Cost Solved By A Genetic Algorithm

Suppose that a project consists of n separate tasks and one and only one task can be completed in one time period. However, since some tasks can be started only before others have been completed, only feasible task schedules are considered. There is a cost associated with the time at which a task is completed and the project cost is equal to the sum of all the task costs. How can a feasible task schedule with minimum project cost be found for completing the entire project? This research proposes using a genetic algorithm to solve this problem efficiently.

Assessing the Time-Cost Trade-Off of Construction Projects

By using Genetic Algorithms (GAs), a resource-integrated model is presented to identify the relationships between project time and cost in consideration of the changes in resource efficiency under different working durations. Under the assumption of a non-linear quadratic relationship between resource efficiency and working duration, the minimum and maximum project costs for different project completion times are easily identified and the trade-off relationships between the project time and cost are clearly presented by using the proposed model and a case study. The research results logically suggest that the greater the adjustable range of activity durations, the lower the minimum project cost for a specific project’s completion time will be, and the greater the value of an activity is, the later the activity will be adjusted.

Aircraft parameter estimation using output-error methods

Certification requirements, optimization and minimum project costs, design of flight control laws and the implementation of flight simulators are among the principal applications of inverse problem applications in the aeronautical industry. The problem of aircraft identification and parameter estimation demands for accurate mathematical model of the aerodynamics and adequate experimental flight data gathering and processing. The aircraft dynamic modeling is characterized by aerodynamic and control derivatives whose values can be directly determined from flight test data. This work describes the application of the output-error method using the Nelder–Mead (NM) and Levenberg–Marquardt (LM) algorithms to obtain the aerodynamic and control derivatives of a regional jet aircraft. Unlike others identification methods based on equation-error the output-error method gives unbiased parameter estimation in the presence of measurement noise. In this work, experimental results for estimation of the lateral directional aerodynamic derivatives, using flight test data provided by EMBRAER, are presented.

Optimal Use of Budget Reserves to Minimize Technical and Management Failure Risks During Complex Project Development

Project managers are recognizing that adequate resource reserves are a critical success factor in a project development environment that is complex and uncertain. Yet, justifying the need for project reserves is still a challenge, as is the optimal allocation of any available resources to minimize development uncertainties. This paper presents a multiperiod decision model designed to support the management of reserves considering the risks of failures including technical, managerial, i.e., exceeding budget and schedule, or strategic, i.e., meeting budget, schedule, and technical specifications but not achieving the full strategic value of the project. In this paper, we examine the tradeoffs among these risks and their implications for resource allocation during a project's development phase. This decision support model is referred to as Dynamic Advanced Probabilistic Risk Analysis Model. It provides decision makers with a quantitative tool to allocate reserves (beyond the bare-bone minimum project costs) among project reserves, technical reinforcements of the engineered system, and product enhancements, with the advantage of flexibility over time. The model yields first, coarse estimates of the value of deferring some commitments about the product's design until critical uncertainties are resolved and second, an estimate of the optimal amount to be invested in testing and reviews. We show that the greater the uncertainties at the onset of the development phase, the greater the value of this information.

OPTIMIZATION MODEL FOR CONSTRUCTION PROJECT DURATIONS USING A MULTISTAGE DECISION PROCESS

The optimization of project duration is often performed during the planning stage of a construction project. Though there are four types of activity time-cost functions used in the optimization of project duration, most of the methods used in the optimization of project duration are only appropriate for a particular type of activity time-cost function. In order to overcome this limitation, this paper constructs an analytical model for optimizing project duration which is applicable to various types of activity time-cost functions. Based on the concept of a multistage decision process, the objective function and the expressions of both serial recurrence and parallel recurrence are established. In addition, the computation algorithms for both recurrence expressions which can reduce the computer memory space used and unnecessary computation are also developed. Finally, every optimal combination of project duration and its corresponding minimum project cost can be computed efficiently. The optima] allocation of activity time and its corresponding cost from each recurrence stage for the specific project duration can also be obtained.

A Theoretical Study on Resource Allocation Problem for Determination of Total Resources Amount Allocated to Construction Project

In this study, it is aimed to develop a new type mathematical model to obtain optimal planning and scheduling with the minimum project cost for construction project and a new type network planning and scheduling model for solving optimal resource allocation problem through determining total amount allocated to construction project is developed as follows: At first stage an optimal scheduling problem with the minimum idle cost consumed by operations of construction resources is formulated through the topological analysis based on the theory of graph and network structure. After formulating scheduling model a mathematical model formulation and an algorithm to solve it effectively is established from the different viewpoint from existing PERT-type network planning scheduling method based on the analysis of topological characteristics of construction project network. At the second stage the scheduling model formulated above is transformed to equivalent optimization model formulated utilizing the cut set structure and the route set structure, and an effective algorithm is developed adopting DP procedure in which the algorithm is established as optimal resources allocation problem in cut-network which is transformed topologically from original project network.

The use of integer linear programming for modelling project control information

The time and cost parameters are considered to be of paramount importance in the management of construction projects. This paper is concerned with the problem of optimizing the relationship between time and cost thus determining the minimum project and activity costs associated with each feasible duration of a multiactivity project. The problem is considered in two parts. The first part explores methods ofinding minimum project cost associated with given project duration, when the time-cost relationship for each activity is only assumed to be continuous and totally defined in the feasible interval but not necessarily linear. A mathematical solution is explored relating earlier work of Meyer and Shaffer (1965), based on integer linear programming, to the analysis ofprecedence networks. In the second part the methods of integer linear programming are also used to consider the more general problem offnding minimum cost for a project when, for some of the activities, the time-cost relationship may only be par...

Extending CPM for Multiform Project Time-Cost Curves

The time-cost phase of CPM is extended with Integer Linear Programming techniques. Using the mathematical models developed, it is possible to determine the minimum project cost for each feasible project duration irrespective of the types of duration-cost relationships associated with the operations in the project. The types of operation duration-cost relationships that are considered are: (1) Non-increasing, bounded, piece-wise linear, continuous, and non-convex; (2) bounded but defined only at discrete points; and (3) bounded but discontinuous. An example project composed of nine operations is included to demonstrate that the formulations describing these relationships can be combined in any number of ways to describe any conceivable operation, duration-cost relationship. The formulations of the example are solved using a large scale computer, and the results are presented and analyzed. The conclusions indicate that while the models developed are sound and completely general, the required computer solution process needs a considerable degree of development. Present (1965) computer programs are capable of solving only projects with less than 50 operations.