Sharif Digital Repository

Mixed-model production Lines manufacture or assemble more than one product with similar production characteristics or different models of a product on the same line. This level of flexibility in commodities is very important to face diverse customers' expectations. In this article, U-shaped, mixed-model, synchronous lines with stochastic task times are discussed in a cost-oriented perspective. In U-shaped, mixed-model, Simultaneous consideration of line balancing and model sequencing is essential because different models require different tasks with different task times and the sequence of models determine the models which is produced in each station in each cycle. This sequence affects the... 

This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems and issues arising in its applications. The new electric utility environment has an immedi-ate consequence of emphasis on reliability and secure operation of power systems. This requires faster and more precise methods to assess the dynamic aspect of se-curity. On the other hand, this issue is becoming challenging when the determined dispatch might not be accommodated due to violation of the limits.This thesis addresses the problem of dynamic security assessment in power sys-tems with an emphasis on its application in restructured power systems... 

Considering the special importance of network flow problems in human life, as well as the complexity of solving these problems in very large scales, there are numerous methods to solve them and the interior point methods are the most important approaches among them. In a number of methods, a preconditioned conjugate gradient solver has been applied for the solution of the Karush-Kuhn-Tucker (KKT) system, in each interior point iteration; therefore, the selection of an appropriate preconditioner is a special issue. In spite of presenting different preconditioners in recent years, discussion and implementation of a particular class of triangulated graph-based preconditioners is our main... 

e main purpose of this resear is to provide an estimate of the short-run slope of the Phillips curve (or the output-inflation trade-off) in Iran. e subject is important, first, because, it reveals the relation between the real and the nominal sectors of economy, and second, because, it has crucial policy implications. We especially investigate whether this relationship has anged during the last five decades following the anges in economic environment and structure. Our findings represent a strong relationship between the real output and the nominal demand before the ’s. is connection, however, starts weakening at the beginning of the ’s, and almost diminishes aer the ’s. As... 

This research enlarges the content of the literature related to the business switching behavior by examining why dissatisfied customers remain in relationship with their existing service provider and do not exit, in the business to business context in Iran. The study develops and tests a model investigating the factors which potentially affect on dissatisfied customers to stay in relationship and also perform upon their repurchase intention. The proposed model specifies a set of propositions among dimensions of switching barriers, switching cost, interpersonal relationship, lack of attractive of alternative, dependence, calculative commitment, service recovery, inertia, lower price, method... 

Due to the intensive competition in the markets and high risk of other strategies, in recent decades, Strategic Alliances (SA’s) have been widely used as a frequent strategy by industries and service sectors especially tourism industry and travel agencies. In this research, using Transaction Cost Theory (TCT), we tried to determine the appropriate types of strategic alliances for Iranian Travel Agencies with regard to the expansion of such inter firm relationships among Iranian travel agencies. Using both qualitative strategy through depth interviews and qualitative strategy through survey and statistical tests, the results of research were determined according to the four main constructs of... 

Cost Estimation plays an essential and role in UAV (Unmanned Aerial Vehicles) Projects. By increasing the complexity of new unmanned systems, the importance of this task augments. Additionally, up to now, a comprehensive approach has not been adopted internationally. But in parallel a number of international companies and organizations has developed specific methods by themselves; confined to their corporate.
This project pursues developing a complexity-based model for cost estimation of unmanned aerial vehicles, especially Jet UAVs. However, it’s anticipated that this model may be utilized for all kind of systems, but it seems that jet UAVs use it with a better and more reliable... 

Resource sharing is one of the most interesting features of grid computing. These resources can include CPU, main memory, secondry memory, network bandwith, or data. How to allocate these resources to the tasks remains a complex problem in this domain. The concentration of this thesis is on workflow scheduling. In this case, the works are composed of several tasks, in the way that some tasks have control or data dependency with others. In other words, we have to schedule a DAG (Directed Acyclic Graph) representation of tasks on limited proceccing units. The principle of workflow scheduling optimization is to minimize the makespan, but in the economic scheduling, cost reduction beside... 

The intermediary between Consumer and market of Natural gas is long transportation pipeline. Analysis of different dimension is a prerequisite for constructing these infrastructures. This study has been done in the fields of economics, environment and energy security. The proposed pipeline, which is called Islamic pipeline, passes through different countries, Iraq, Syria, Greece and Italy. It carries natural gas and feeds Europe gas requirements, also passes the Mediterranean Sea, which includes underwater pipe-laying technology that has been considered. Economic analysis of this project calculated, using Cost-Benefit analysis. Environmental issues has been identified and classified,... 

Futures exchanges require a margin requirement that ensures their competitiveness and protects against default risk. The purpose of a margin requirement is to protect a clearinghouse from members’ defaults resulting from big losses due to adverse movement of futures prices. Extreme movements are central to the margin setting problem, because only a large price variation may cause brokers to incur losses. So in this study according to recent default in gold futures in Iran Mercantile Exchange we apply extreme value theory for computing unconditional and conditional optimal margin levels based on Block-Maxima and Peak over threshold approaches.The results show that at very high confidence... 

After restructuring in power systems, Independent System Operators (ISO's) are looked for an appropriate auction mechanism to find the market operation point. In deregulated electricity markets, Offer Cost Minimization (OCM) auction is used to minimize the total bid cost for selecting offer and demand bids. But a uniform market clearing price (MCP) or Locational Marginal Price (LMP) is used for consumer payments. Hence, the minimized bid cost is different from settlement cost. The used mechanisms are for manufactures offer and their cost functions optimization. The Payment Cost Minimization (PCM) is one of the mechanims that affect directly on the consumers payment and lead to reduction of... 

In this research a mathematical formulation is presented for project scheduling problem subject to non-renewable perishable resources where the objective is minimize the cost of ordering and maintenance of resources. We use the framework of a resource constrained project scheduling problem (RCPSP) with finish-start precedence relations between activities and resources will be perished after a determined duration and must be procured. Resource procurement have ordering and purchasing costs and excess resources must be stored and have maintenance cost. There is a unique way to perform the activities and preemption is not allowed.
This work employs Genetics Algorithms to solve the problem... 

Under volatile economic conditions, where inflation is high and market prices of materials, labor, and equipment change unexpectedly, construction cost rise. To avoid the disruption of work, the owner may be required to compensate the contractors in a way that the excess construction cost is partially or completely covered. This compensation should be provided to the contractors in a way that is authorized by the laws and regulations under which the contract is stipulated. Hence it is essential to have the proper mechanism, for sharing the burden of cost overruns caused by unforeseen economic conditions.
In Iran, the payment scheme for the majority of the medium-and large-scale contracts... 

Verification of timed systems is concerned by many researchers in the last decades because of using these systems in critical applications. So, several models such as Timed Automat (TA) and Time Petri Nets (TPN) have been proposed for modeling these systems and variety of logics and abstraction methods are defined. One of the significant problems in timed system is cost-optimal reachability problem where, given an initial state and a target state, the task is to comput a path with infimum cost from initial state to the target state. Priced Timed Automat (PTA) introduce for solving cost-optimal reachability problems such as optimal scheduling and planing in timed systems. PTA is defined as an... 

In the process of industrial and economic development and in the competitive environment in the world, reducing the cost of industrial products is an important factor for more customers' satisfaction, more revenue acquisition, and stability and success in the business. Cost engineering is the area of engineering practice concerned with the application of scientific principles and techniques to problems of cost estimating, cost control, business planning, management science, profitability analysis, project management, planning and scheduling. In this research through the studying the structures and models of cost engineering, in addition to consider this dimensions of cost engineering, the... 

Nowadays, high reliability requirements for commercial and industrial loads, make it necessary to install microgrids for supplying the loads during power outages. Due to the fact that solar energy is clean, free of noise pullotion and also it benefits from the governmental obligations, it is a wealthy choice for supplying the load in microgrid. Designing and operation of the photovoltaic microgrid are the two important steps that should be considered. In this thesis, these two steps have been investigated by integrating a battery system into a solar PV plant and control of PV mictrorid in islanded mode. In the designing step, the optimum battery bank is calculated. For calculating the... 

The Dynamic Maximal Covering Location Problem (DMCLP), is one of the classes of Facility Location Problem (FLP) with a wide raneg of applications in real-life situations. In order to solve this problem, this research presents a sufficient greedy heuristic algorithm, which is capable of solving the DMCLP in large scales of 2500 demand nodes and potential facilities of 200 in 5 periods in a negligible computation time in comparison to those with exact algorithms such as branch and cut. Furthermore, in this research DMCLP is also modified to reach reach a more realistic model. In this new model, a cost behaviour is defined according to the number of facilities located. Subsequently, the new... 

Nowadays, increasing of difficulties in production and procurement conditions such as competitiveness among manufacturing firms, variety of products, rapidly changing of customer tastes, shortening of product lifetime and complexity of demand forecasting on one hand, and key role of consumers and deteriorating products on countries revenue on the other hand, make replenishment policies of deteriorating products challenging and also interesting for both researchers and corporate managers.In this dissertation several novel models on replenishment policies for deteriorating products are proposed under uncertainty by the help of single or multi objective mathematical models. One important... 

Successful Cost Management in projects has a key role in projects’ final success. Earned Value Management methodology (EVM) as a known management tool especially for cost control and cost management, provides for effective planning, controlling, evaluation and corrective actions in the projects through integration of scope, cost and time. Existing budgeting and cost control structures in local projects based mainly upon manufacturing companies’ models has continuously proved inefficient. The current effort has intended to find an appropriate solution based on EVM for cost management in Iranian Offshore Engineering and Construction Company (IOEC). Since September 2008 a planned activity... 

In recent decades, large economic losses and social impacts following earthquakes and hurricanes have revealed the need for improved design criteria intended to reduce consequences including economic impacts to an acceptable level along with life protection. So, it is tried to express the expected performance of structures as financial and social criteria. Any assessment on earthquake consequences requires estimations of structural responses to seismic excitations. Endurance Time (ET) method as a dynamic procedure requiring reasonably reduced computational effort compared to other common time-history based procedures, is used to estimate the response of the structure in all levels of hazard...