مقالههای Ahmad Sadeghi
توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.
۱Simultaneous Coordinated Design of Two–Level UPFC Damping Controller and PSS to Damping Oscillation in Multi–Machine Power System
اطلاعات انتشار: بیست و ششمین کنفرانس بین المللی برق، سال ۱۳۹۰
تعداد صفحات: ۱۳
This paper describes a new UPFC controller design for damping power system oscillations focusing on inter–area modes. Proposed controller for power oscillation damping is a two–level controller that first level of control is derived from local signals and the second level of control is supplied from global signals as additional measuring information from suitable remote network locations, where oscillations are well observable. In order to damping local modes, the conventional PSS (CPSS) is used that choice of CPSSs location is based on modal analysis. Since uncoordinated proposed controller for UPFC and CPSSs may cause unwanted interactions, it is necessary to simultaneous coordinated tune the controller parameters. The problem of coordinated design is formulated as an optimization problem and particle swarm optimization (PSO) algorithm is employed to search for optimal parameters of controllers. A time delay introduced by remote signal transmission and processing in wide–area damping controller (WADC) may be harmful to system stability and may degrade system robustness. The investigation of delay–dependent stability of power system equipped with a WADC is carried out using lyapunov theory and model reduction technique. The effectiveness and robustness of the designed controllers are tested on a typical four–machine two–area benchmark power system.<\div>
اطلاعات انتشار: اولین همایش ملی حسابداری، حسابرسی و مدیریت، سال ۱۳۹۳
تعداد صفحات: ۸
An insurance service supply chain consists of all parties involved directly and indirectly in fulfilling a policyholder’s request. In property–liability insurance contract the major alternatives in selecting an insurer include: availability of coverage, cost of coverage, financial stability of insurer, quality and quantity of service offered. The success of its supply chain mainly is due to the recognition of the importance degree of these alternatives. Finding a differential advantage in the market place to support the supply chain is a major management challenge requiring both creative and analytical skills. This paper has provided an analytical model to deal with the importance degree calculation of the four main factors which are considered by a property–liability insurance policy buyer in selecting insurer by Analytic Network Process (ANP) from the view of policy holders. As these factors are all interrelated we utilized ANP model to prioritize them and help decision makers how to allocate their resources in order to support the supply chain so as to increase their market share. In this research property and liability insurance buyers’ views were analyzed by an analytical algorithm to improve the competitive managerial skills which is the core aim of this research. Results from the limit super matrix revealed that the quantity and quality of services offered weighted as the most important factor amongst the others<\div>
۳A parameter–tuned genetic algorithm for vendor managed inventory model for a case single–vendor single–retailer with multi–product and multi–constraint
اطلاعات انتشار: Journal of Optimization in Industrial Engineering، چهارم،شماره۹، ۲۰۱۱، سال ۰
تعداد صفحات: ۱۱
This paper develops a single–vendor single–retailer supply chain for multi–product. The proposed model is based on Vendor Managed Inventory (VMI) approach and vendor uses the retailer''s data for better decision making. Number of orders and available capital are the constraints of the model. In this system, shortages are backordered; therefore, the vendor’s warehouse capacity is another limitation of the problem. After the model formulation, an Integer Nonlinear Programming problem will be provided; hence, a genetic algorithm has been used to solve the model. Consequently, order quantities, number of shipments received by a retailer and maximum backorder levels for products have been determined with regard to cost consideration. Finally, a numerical example is presented to describe the sufficiency of the proposed strategy with respect to parameter–tuned by response surface methodology (RSM).
۴Measuring and Analyzing the Bullwhip Effect in a Two–Product and Two Echelon Supply Chain Using Control Theory Approach
نویسنده(ها): Ahmad Sadeghi
اطلاعات انتشار: Journal of Optimization in Industrial Engineering، هفتم،شماره۱۵، ۲۰۱۴، سال ۰
تعداد صفحات: ۹
Coordination is very important in supply chain management and it is one of the main factors in supply chain profitability. Bullwhip effect is one of the basic obstacles to achieve coordination in supply chains and reduction of this phenomenon has an important role in supply chain harmony. The other side, costs of supply chain can be mitigated and customer service level can be increased by reducing of bullwhip effect. Because measurement of bullwhip effect is very important in analysing and controlling of it, providing equations to investigate bullwhip effect behaviour based on real world supply chain conditions is necessary. The previous studies mostly concentrate on single product supply chain and few studies have been done on supply chains with more than one product. Here we quantify and investigate the bullwhip effect in a two–echelon supply chain with two products using control theory approach. Due to the relationship between demands of two products in our proposed supply chain, first order vector auto regressive model is used as demand process of the products. We also apply moving average method for lead–time demand forecasting within the «order up to» replenishment policy. We derive a closed form bullwhip measure and then bullwhip effect in a two–product supply chain is discussed and illustrated through a numerical example.
۵A Benders Decomposition Method to Solve an Integrated Logistics Network Designing Problem with Multiple Capacities
اطلاعات انتشار: Journal of Optimization in Industrial Engineering، هشتم،شماره۱۸، ۲۰۱۵، سال ۰
تعداد صفحات: ۱۵
In this paper, a new model is proposed for the integrated logistics network designing problem. In many research papers in this area, it is assumed that there is only one option for the capacity of each facility in the network. However, this is not a realistic assumption because generally there may be many possible options for the capacity of the facility that is being established. Usually the cost of establishing a facility depends on its capacity. Moreover, of the majority of the research done in the field of logistics network designing problem only a limited number of options for product recovery is addressed. Specifically, in most of the research papers only one option, i.e. remanufacturing, has been considered. Therefore, a mathematical formulation with multiple options for capacities and product recovery is addressed in this research to obviate this gap. Afterwards a benders decomposition method is developed to efficiently solve the problem. The computational results introduce several random generated problems to be solved with benders algorithm and demonstrate that this algorithm can efficiently solve the proposed model.
نمایش نتایج ۱ تا ۵ از میان ۵ نتیجه