Sharif Digital Repository

Risk aversion is a prevalent phenomenon when sufficiently large amounts are at risk. In this paper, we introduce a new prescriptive approach for coping with risk in sequential decision problems with discrete scenario space. We use Conditional Value-at-Risk (CVaR) risk measure as optimization criterion and prove that there is an explicit linear representation of the proposed model for the problem  

In this research, we investigate a three-stage supply chain with one supplier, several manufacturers and multiple retailers where the supplier provides a common raw material to each manufacturer, who in turn uses a single stage production facility to convert it into final products that are delivered at fixed lot sizes to retailers. An integrated economic procurement, production, and delivery model is developed whose objective is to find the common production cycle length, production sequences of final products at manufacturers and delivery frequencies of final products to retailers minimizing the total costs of considered supply chain. We propose an analytical solution procedure and an... 

Trying to find the most efficient and cost-effective decisions on the maintenance of different component types in power distribution systems is an increasingly challenging concern largely driven by the current financial constraints in distribution utilities worldwide. In regard to deal with this challenge, the paper presents a practical application of the Delphi method and the Modified Analytical Hierarchical Process (MAHP) that can be used to find the most critical component types of the system in order to assist in accordingly allocating the available maintenance budget. The proposed approach involves the experience and knowledge held by experts and the historical empirical performance... 

Although demand response (DR) potentially brings miscellaneous advantages, it is currently faced with challenges in its implementation due to customers' difficulty in manually responding to the time-varying prices. This paper presents an optimal and automatic residential load commitment (LC) framework to achieve the household minimum payment. Problem decision variables are the operating status of responsive appliances and charging/discharging cycles of battery storage and plug-in hybrid electric vehicles (PHEVs). Storage capability in residential centers provide the customers with this opportunity to not only supply the local demand during the high price hours but also sell the energy back... 

With increment in the penetration of wind energy in power systems, the necessity of considering its impacts on transmission expansion planning (TEP) studies, especially for large scale wind farms, is inevitable. A new multi-objective (MO) optimization transmission expansion planning algorithm considering wind farm generation is presented in this two-paper set. Part I is mainly devoted to derivation of the theory and algorithm. The objective functions used in the TEP studies take into account investment cost, risk cost and congestion cost. The combination of Monte Carlo simulation (MCS) and Point Estimation Method (PEM) is implemented to investigate the effects of network uncertainties. Due... 

Automation is acknowledged by distribution utilities as a successful investment strategy to enhance reliability and operation efficiency. However, practical approaches that can handle the complex decision-making process faced by decision makers to justify the long-term financial effects of distribution automation have remained scarce. An automated and remote-controlled sectionalizing switch play a fundamental role in an automated distribution network. This paper introduces a new optimization approach for distribution automation in terms of automated and remotely controlled sectionalizing switch placement. Mixed-integer linear programming (MILP) is utilized to model the problem. The proposed... 

The concerns of regulatory authority for the cost efficiency and service quality of distribution utilities has led them to implement monetary schemes, such as penalty/reward mechanism (PRM). PRM provides explicit financial incentives for distribution system operators (DSO) to maintain or improve their efficiency and quality of service. Although the effectiveness of the PRM is proven, analytical tools that can handle the complex decision-making process faced by decision makers to respond to PRM are scarce. This paper presents an approach for distribution system maintenance management in the presence of the PRM. The proposed approach tailors the maintenance plans by taking into account the... 

Distribution automation (DA) application for fault management in the electricity distribution networks is one of the main potential remedial actions to reduce customers' outage times and hence improve service reliability. As a result, various automation schemes have been developed and introduced in different countries and by different venders. The impacts of implementing a specific automation scheme on reliability indices of a given distribution system can be different from other available automation schemes. For this reason, when comparing the available automation schemes with each other or with the other reliability improvement measures, it is necessary to perform a course of reliability... 

An algorithm for determining optimal reserve capacity in a power market is presented in this paper. Optimization process in the proposed algorithm is based on the cost-benefit trade off. Market clearance is executed with consideration of uncertainties of power system components in an aggregated environment. It is assumed that both generating units and interruptible loads participate in the reserve market. In addition, customers' reliability requirements are considered as constraints for decision making process of ISO. The rendered method considers random outages of generating units and transmission lines and determined outage of interruptible loads and employs Monte Carlo Simulation (MCS)... 

The knowledge of the conductivity across the reservoir that is based on the swept fraction controls the recoverable rates of the hydrocarbon in the secondary displacement processes. Most of the time, we need a fast estimation of the conductivity for decision making during field development. Percolation theory is a very useful tool to get this goal. According to this fact that the results of this method are universal, they could be used widely. In this study connectivity and conductivity percolation models are developed and the universal exponents for connectivity and conductivity in fractured reservoir as well as their dependency on the correlation length are investigated. For L< ξ the... 

Gas injection is the second largest enhanced oil recovery process being applied in many reservoirs around the world. Simulation of these processes is necessary for implementation, management, and decision making. Relative permeability is one of the most important factors in numerical reservoir simulation. In this study, several core flood experiments are done and the relative permeability in carbon dioxide (CO2) injection is compared with nitrogen (N2) injection. Oil relative permeability in CO 2 injection is found to be higher than in N2 injection, but gas relative permeability in CO2 injection is found to be lower than in N2 injection. Higher oil relative permeability in CO 2 injection... 

Evaluation of a project and its contractors has considerable importance in gas well-drilling projects due to their high investments and worth. In this paper, the quality of some gas well-drilling projects is analyzed in order to evaluate and grade project tasks. A neuro-fuzzy network is utilized to learn the grading process and generate models. To select among these models, a ranking method, namely technique for order of preference by similarity to ideal solution (TOPSIS) is employed. During seven gas well-drilling projects, 77 tasks are studied based on quality practitioners[U+05F3] points of view. After generating the primary models, three indices namely, root mean square error (RMSE),... 

Roadmapping, a tool of strategic planning, visualize where and how an organization will be in the future. Visualization of strategic programs assists people in the organization to understand the strategy which is a key for implementing strategy successfully. A generic roadmap is included of three main layers such as; market, product and technology. Decision making in each layer are done separately because of the nature of each layer. Therefore, decisions in roadmapping can be done with different tools. Whiles, decisions in each layer of the roadmap cannot be done without considering the upper or lower layer decisions. In this study we propose Fuzzy PROMETHEE method for integrating decisions... 

The optimal design of complex systems in engineering requires pursuing rigorous mathematical modeling of the system's behavior as a function of a set of design variables to achieve goal-oriented design. Despite the success of current knee implants, the limited life span remains the main concern of this complex system. The mismatch between the properties of engineered biomaterials and those of biological materials leads to insufficient bonding with bone, stress shielding effects and wear problems (i.e. aseptic loosening). The use of a functionally graded material (FGM) for the femoral component of knee implants is attractive because the properties can be designed to vary in a certain pattern... 

Data Envelopment Analysis (DEA) is a method to measure the efficiency of a DMU (Decision Making Unit, e.g. school, public agencies and banks). One of the ways for determining rank of DMUs is efficient score of each DMU. An interesting research issues is to discriminate between efficient DMUs. In literatures, supper efficiency is an applicable method for ranking efficient DMUs. The main drawback of this method is an inability of this method to rank non-extreme efficient DMUs. Therefore, this issue reduces the usefulness of this method. In this paper we propose a new ranking system for non-extreme efficient DMUs (Decision Making Units) based upon the omission of DMUs from reference set of the... 

In this paper a finite volume (FV) numerical method is implemented to solve a Biot consolidation model with discontinuous coefficients. Our studies show that the FV scheme leads to a locally mass conservative approach which removes pressure oscillations especially along the interface between materials with different properties and yields higher accuracy for the flow and mechanics parameters. Then this numerical discretization is utilized to investigate different sequential strategies with various degrees of coupling including: iteratively, explicitly and loosely coupled methods. A comprehensive study is performed on the stability, accuracy and rate of convergence of all of these sequential... 

Global economic expansion and increasing concentration of people in the large cities, especially in developing countries leads to some environmental issues such as air pollution. Relocation of the firms as a great air pollutant can be an appropriate alternative for diminishing these pollutions. Yet, there is a lack of research about factors precluding firm relocation with respect to decision making factors when determining whether or not to relocate. Thus, the purpose of this case study is to examine firm relocation decision-making factors and to apprehend the role of environment issues in making them using a combination of SWOT matrix and Analytic Hierarchy Process (AHP). The combination... 

A multi-item multiperiod inventory control model is developed for known-deterministic variable demands under limited available budget. Assuming the order quantity is more than the shortage quantity in each period, the shortage in combination of backorder and lost sale is considered. The orders are placed in batch sizes and the decision variables are assumed integer. Moreover, all unit discounts for a number of products and incremental quantity discount for some other items are considered. While the objectives are to minimize both the total inventory cost and the required storage space, the model is formulated into a fuzzy multicriteria decision making (FMCDM) framework and is shown to be a... 

Automatic image annotation has emerged as an important research topic due to the existence of the semantic gap and in addition to its potential application on image retrieval and management. In this paper we present an approach which combines regional contexts and visual topics to automatic image annotation. Regional contexts model the relationship between the regions, whereas visual topics provide the global distribution of topics over an image. Conventional image annotation methods neglected the relationship between the regions in an image, while these regions are exactly explanation of the image semantics, therefore considering the relationship between them are helpful to annotate the... 

Ways to reduce an airline's cost has been studied for years. In fact, in order to achieve this goal, ones need to know different types of airline's costs including; fuel and oil, maintenance, Ticketing, passenger services, etc. and their impact on the total cost of an airline. According to announcement of ICAO [1], "maintenance cost (about 11% of total cost) is the second major cost after fuel and oil". Therefore, this may attract airline owners' attention to find ways to control maintenance cost and eventually the total cost of an airline. Though, there are many systematic approaches to analyze cost reduction and making policies, in this article, SD modeling is applied to develop a...