scholarly journals Problem minimalizacji przestojów w pracy brygad generalnego wykonawcy w harmonogramowaniu przedsięwzięć budowlanych

2017 ◽  
Vol 26 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Piotr Jaśkowski ◽  
Michał Tomczak
Keyword(s):  
Mathematical Model ◽  
Project Scheduling ◽  
Construction Projects ◽  
Construction Project ◽  
Time Constraints ◽  
Production Capability ◽  
General Contractor ◽  
High Level ◽  
The Mathematical Model ◽  
Construction Project Scheduling

During executing of construction projects enterprises seek for high level of coordinating engaged resources. This seeking evinces in providing continuity and levelling production. It enables making of entire production capability. This paper analyses scheduling work of general contractor crews, which carry out unrhytmic, noncyclic and inhomogeneous processes in deterministic conditions. The mathematical model of work gaps for general contractor crews in construction project scheduling is formulated. This model also counts crews availability limits, cost and time constraints and possibility of tasks outsourcing for subcontractors.

scholarly journals Scheduling Optimization of Prefabricated Construction Projects by Genetic Algorithm

2021 ◽  
Vol 11 (12) ◽  
pp. 5531
Author(s):  
Linlin Xie ◽  
Yajiao Chen ◽  
Ruidong Chang
Keyword(s):  
Project Scheduling ◽  
Construction Projects ◽  
Resource Constraints ◽  
Construction Project ◽  
Engineering Application ◽  
Project Schedule ◽  
Scheduling Optimization ◽  
Implementation Method ◽  
Traditional Construction ◽  
Construction Project Scheduling

Prefabricated buildings are the direction of the future development of the construction industry and have received widespread attention. The effective execution of prefabricated construction project scheduling should consider resource constraints and the supply arrangement of prefabricated components. However, the traditional construction resource-constrained project scheduling implementation method cannot simultaneously consider the characteristics of the linkage between component production and on-site assembly construction. It cannot also fully adapt to the scheduling implementation method of the prefabricated construction projects. It is difficult to work out a reasonable project schedule and resource allocation table. In order to determine the relevant schedule parameters that can reflect the actual construction situation of the prefabricated building and meet the scheduling requirements of the prefabricated project, this study proposes a prefabricated construction project scheduling model that considers project resource constraints and prefabricated component supply constraints. Additionally, it improves the design of traditional genetic algorithms (GAs). Research results of the experimental calculation and engineering application show that the proposed project scheduling optimization model and GA are effective and practical, which can help project managers in effectively formulating prefabricated construction project scheduling plans, reasonably allocating resources, reducing completion time, and improving project performance.

scholarly journals Trading off Time–Cost–Quality in Construction Project Scheduling Problems with Fuzzy SWARA–TOPSIS Approach

Buildings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 387
Author(s):  
Sayyid Ali Banihashemi ◽  
Mohammad Khalilzadeh ◽  
Jurgita Antucheviciene ◽  
Jonas Šaparauskas
Keyword(s):  
Decision Making ◽  
Project Scheduling ◽  
Construction Projects ◽  
Construction Project ◽  
Solution Technique ◽  
Time Cost ◽  
Trade Off ◽  
Project Activity ◽  
Project Objectives ◽  
Construction Project Scheduling

The increasing number of construction projects together with the limited resources of organizations led to tough competition for achieving project goals. Time, cost, and quality have been known as the project iron triangle. Project managers attempt to allocate the appropriate resources and make the best decisions for accomplishing projects with the shortest durations, lowest costs, and the highest quality. No study has examined the time–cost–quality trade-off problem with decision-making approaches. In this study, the fuzzy multi-criteria decision-making (MCDM) methods are exploited to choose the best mode for performing each activity. For this purpose, the SWARA method is applied to determine the importance weights of time, cost, and quality. In addition, the TOPSIS (Technique for the Order Preference by Similarity to Ideal Solution) technique is used to rank and select the best activity execution modes. The proposed model is implemented on two medium- and large-size construction projects to evaluate its efficiency. Several execution modes with fuzzy duration, cost, and quality are considered for each project activity. Finally, sensitivity analysis is conducted taking three different conditions into account: the shortest duration of the execution modes, the lowest cost of the execution modes, and the highest quality of execution modes for each activity. The solution of each trade-off is compared with the solution obtained from the fuzzy SWARA–TOPSIS method. The schedule is developed according to the best execution mode for each project activity. The obtained results in two different construction projects show significant improvements in the overall project objectives so that the projects can be completed in fewer durations and costs along with higher quality. Because of the higher importance of cost, the cost of each activity is closer to the lowest cost. The activity duration is also closer to the most likely duration, and quality is closer to the high-quality level. The application of this approach can create new opportunities for research and knowledge development in the field of construction project scheduling.

Determination of Plasticity for Pre-Deformed Billet

2019 ◽  
Vol 291 ◽  
pp. 110-120
Author(s):  
Olena Solona ◽  
Iryna Derevenko ◽  
Igor Kupchuk
Keyword(s):  
Mathematical Model ◽  
Damage Accumulation ◽  
Mechanical Characteristics ◽  
Calculation Procedure ◽  
Fracture Model ◽  
Pipe Extrusion ◽  
High Level ◽  
The Mathematical Model ◽  
Extrusion Method

The calculation procedure for determining the plasticity of pre-deformed metals during their processing by pressure has been developed. The calculation procedure is based on a fracture model, which in turn is based on the tensor description of damage accumulation. With known mechanical characteristics, as well as with known plasticity diagrams, the fracture model makes it possible to evaluate the plasticity of pre-deformed bend for any kind of stress state. When manufacturing steeply curved branches using the pipe extrusion method, the procedure was tested. Verification of the mathematical model has shown a high level of its adequacy, and it can be used in assessing the plasticity of pre-deformed billet.

Research on Optimization Model of Vehicle Routing for Emergent Relief Supplies of Multi-Reserves

2010 ◽  
Vol 171-172 ◽  
pp. 205-210
Author(s):  
Tong Zhao ◽  
Hou Ming Fan ◽  
Gui Lin Wang
Keyword(s):  
Mathematical Model ◽  
Natural Disasters ◽  
Vehicle Routing ◽  
Optimization Model ◽  
Ant Colony Algorithm ◽  
Well Being ◽  
The World ◽  
High Level ◽  
The Mathematical Model ◽  
Improved Ant Colony Algorithm

In the world today, science and technology in natural disasters forecasting is changing with each passing day and is built up to a rather high level. But local, territorial, even just national or worldwide scope natural disasters have also posed a grave menace to human well-being and development. Therefore, researching on optimizing problem of vehicle routing for emergent relief supplies of multi-reserves, it is vital significant to quickly send relief supplies to the sufferers after sudden natural disasters. Then, we draw out the mathematical model and solve the problem reasonably based on the improved ant colony algorithm, at last, we obtain the satisfy results through an empirical exemple.

scholarly journals MATHEMATICAL MODELING OF A THREE-PHASE TRANSFORMER TAKING INTO ACCOUNT A MAGNETIC CORE ASYMMETRY

2021 ◽  
Vol 295 (2) ◽  
pp. 165-171
Author(s):  
O. KIMSTACH ◽  
◽  
I. ILLIASHENKO ◽  
A. ZHEZHELO ◽  
◽  
...  
Keyword(s):  
Mathematical Model ◽  
Magnetic System ◽  
Short Circuit ◽  
Magnetic Core ◽  
Transient Processes ◽  
Three Phase ◽  
Significant Difference ◽  
The Asymmetry ◽  
High Level ◽  
The Mathematical Model

The paper analyses the aspects of modelling the operation of a three-phase core-type transformer. The features of the magnetic system construction of the transformer, which generate asymmetry, are disclosed. The fundamentals and methods for modelling a transformer in dynamic modes are considered. The main purpose of the paper is to research the influence of taking into account the asymmetry of the transformer magnetic core on its dynamic model. The paper proposes the mathematical model of a three-phase planar core-type transformer, which takes into account the asymmetry of the magnetic core. The mathematical model is based on the model of a generalized electric machine in the ABC axes, which is widely recognized and characterized by a high level of adequacy. A refined model, which takes into account the power losses in the magnetic core, has used. As is well known, such a model is characterized by higher accuracy and adequacy in the calculation of transient processes. For the proposed mathematical model, a comparative analysis of the calculated curves of transient processes for a 63 kVA transformer with a voltage of 6 / 0.4 kV is made. To disclose the effect of taking into account the magnetic core asymmetry of the transformer in the mathematical model, the current differences were calculated in pu for the modes of switching on at full power and three-phase short circuit. These modes are the most common and indicative in the analysis of the operability and stability of transformers. It was found that the most significant difference, which is obtained by taking into account the magnetic system asymmetry of the transformer, is 5…6% when it is switched on at full load. Thus, the relatively simple transformations and updating of the mathematical model of the transformer allow significantly increase its adequacy. The proposed mathematical model can be more effectively used when the non-typical design of three-phase transformers or reactors with significant asymmetry of the magnetic core is considered.

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