Sharif Digital Repository

Minimizing completion time of tasks in a flowshops has always attracted attention of researchers since it was introduced by Johnson, 1954. If all jobs are processed in the same order, the sequence is called a permutation sequence. Tardiness factor is one of important factors in permutation flowshop sequencing problem. Minimizing this factor brings about increase in service level of the shop and is helpful in meeting customer’s needs. Since, minimizing tardiness in PFSP in among NP-hard problems, computational efforts in this area has focused on heuristic approaches. However, the researches has always considered due dates only on the last machine. It means, always it has been assumed that due... 

Among various types of resources defined in the project scheduling literature, the most studies have been conducted on the renewable and nonrenewable resource types. Definition of different resources in the project scheduling literature is based on the specification of the resources in the real projects. Yet there are some sort of nonrenewable resources in the real projects that are not exactly similar to the type defined in the project scheduling literature. The difference stems from this fact that in the project scheduling literature, it is supposed that the nonrenewable resources required for the execution of the project activities are available in full amount at the beginning of the... 

Origin-Destination (OD) demand is one of the important requirements in transportation planning. Estimating OD demand could be an expensive and time consuming procedure. These days using vehicle identification sensors for OD estimation has become very common because of its low cost and high accuracy. In this study, we focus on solving location problems of these sensors with the aim of observe and estimate path flows. These problems have only been solved for small-scale networks until recently due to being computationally expensive. These years two basic models have been introduced : one, without considering time of vehicle ID detection and one, with considering that information. In this... 

The field of microrobotics has seen tremendous advances in recent years. Potential high impact applications of untethered microrobots such as minimally invasive diagnosis and treatment inside the human body, biological studies or bioengineering, microfluidics, desktop micromanufacturing, and mobile sensor networks for environmental and health monitoring are reported. However, There are significant challenges in microrobotic technology, including energy resources, control systems, reliability and safety, design and manufacturing of micromotors and localization. In this work, overall size scale being micron scale is emphasized where mobile robots able to fit in spaces smaller than a millimeter... 

In previous decades, easy access to material and low cost human power allow the product process to be performed in a preferred way. The limit in amount of material, economy, and the efficiency of the model has not been influential like these days. Today, the effective use of material and consideration of an economic model have great importance. It is obvious that a process of designing implies optimizing which the range of its using is also continuing in many engineering sciences. Many optimization issues contain discrete nature. Many of searching spaces that we encounter in the real world applications are not necessarily continuous as a condition which has crucial importance for classic... 

This paper is concerned with the Vehicle Routing Problem (VRP) in a fleet with customer loyalty. In this work, we consider priority for customers according to their loyalty and try to declare an objective function which concerns customers' satisfaction along other normal VRP objectives like route optimization  

This study examines how imperfect advance load information (IALI) can improve profits and vacancies for a trucking company. To evaluate the value of IALI, first, a deterministic mathematical model is created. Next, we propose a Markov decision programming approach that can use this IALI.Due to exponential size of the state space the problem cannot be solved to optimality it in polynomial time so we suggest a heuristic algorithm.After designing a comprehensive set of experiments, we use both models using a dynamic implementation mechanism to evaluate the benefits of using this information. Statistical analysis and literature show that, firstly, the use of IALI can significantly improve the... 

One of the most important issues that an organization faced with is resource management. The proper resource management has the great rule in organization cost reduction. One of the most efficient processes in resource allocation is auction and there is different auction with different mechanism and goals. In an auction there is a set of items and a set of bids, and the task of auctioneer is matching items with suitable bids. Each bid consist of desirable items and the bidder value of that items. In an auction process, after mechanism design of auction and auction implementation we must identify the winners of auction and this is a hard problem even in simple auction.
In this study we...