Sharif Digital Repository

One of the most important issues in planning the reservoir type of Medium Hydro-Power Plants (MHPP) is to determine the optimal installation capacity of the MHPP and estimate its optimal annual energy value. In this paper, a method is presented to calculate the annual energy. A computer program has been developed to analyse energy calculation and estimation of the most important economic indices of an MHPP using the sensitivity analysis method. Another program, developed by Matlab software, calculates the reliability indices for a number of units of an MHPP with a specified load duration curve using the Monte Carlo method. Ultimately, comparing the technical, economic and reliability indices... 

This paper considers a two-level supply chain consisting of one warehouse and one retailer. Unlike the most similar models which determine the optimal ordering policy according to inventory cost only, in this model, we also consider the transportation cost. We assume that the demand rate at the retailer is known and the demand is confined to a single item. Shortages are allowed neither at the retailer nor at the warehouse. The objective is to find the economic order quantities for both the retailer and the warehouse which minimize the total cost. That is. the sum of the holding and ordering cost at the retailer and warehouse as well as the transportation cost from warehouse to retailer.... 

Construction industry is one of the most important fractions of economy in developing countries. This industry consumes enormous amounts of raw materials and produces considerable waste. The optimization of construction material usage not only saves costs but also can significantly contribute towards Sustainable Development. This article addresses Construction Waste Management as an approach to improve construction productivity, with a focus on its application in developing countries. The status of construction waste production and management in Tehran metropolitan, Iran-as a developing country-is investigated and compared with the status of developed countries. Subsequently, barriers to... 

We propose a method for analyzing the data for the rates of exchange of various currencies versus the U.S. dollar. The method analyzes the return time series of the data as a Markov process, and develops an effective equation which reconstructs it. We find that the Markov time scale, i.e., the time scale over which the data are Markov-correlated, is one day for the majority of the daily exchange rates that we analyze. We derive an effective Langevin equation to describe the fluctuations in the rates. The equation contains two quantities, D(1) and D(2), representing the drift and diffusion coefficients, respectively. We demonstrate how the two coefficients are estimated directly from the... 

In this study, two methods for solving economic dispatch problems, namely Hopfield neural network and X iteration method are compared. Three sample of power system with 3, 6 and 20 units have been considered. The time required for CPU, for solving economic dispatch of these two systems has been calculated. It has been shown that for on-line economic dispatch, Hopfield neural network is more efficient and the time required for convergence is considerably smaller compared to classical methods. © 2006 IEEE  

The physicochemical techniques presently available for treatment of H2S containing gases are many and varied. In near future small gas reservoirs with high concentration of H2S will be explored, therefore the gas processing industry is seeking novel, cost effective, environmentally compatible and operator friendly technologies applicable to the small volume producrs. The continuing search for more economical methods has led to investigations into microbiological processes. The biological process which has been studied in this research is Bio-SR process. Bio-SR process uses thiobacillus ferroxidans bacteria to regenerate gas treating solution (ferrous sulfate). In this way, the effects of... 

The techno-economic and environmental performance of hybrid solar hydrogen energy systems was investigated to provide combined cooling, heating and power (CCHP) demands of a standalone greenhouse in Iran to achieve sustainable agriculture based on an optimization procedure. From the environmental point of view, by deploying hybrid energy systems, 83%, to 100% of emissions can be avoided. Also a sensitivity analysis was performed on the hybrid energy systems in order to study the effect of major parameter variation on the systems justification. It was concluded that hybrid solar systems are economically competitive with conventional systems, for high solar intensity locations with high diesel... 

One of the most important issues in planning the "reservoir" type of hydro-power plants (HPP) is to determine the installation capacity of the HPPs and estimate its annual energy value. In this paper, a method is presented. A computer program has been developed to analyze energy calculation and estimation of the most important economic indices of an HPP using the sensitivity analysis method. Another program, developed by Matlab software, calculates the reliability indices for a number of units of an HPP with a specified load duration curve using the Monte Carlo method. Ultimately, comparing the technical, economic and reliability indices will determine the installation capacity of an HPP. By... 

We describe a general method for analyzing a nonstationary stochastic process X (t) which, unlike many of the previous analysis methods, does not require X (t) to have any scaling feature. The method is used to study the fluctuations in the daily price of oil. It is shown that the returns time series, y (t) =ln [X (t+1) X (t)], is a stationary and Markov process, characterized by a Markov time scale tM. The coefficients of the Kramers-Moyal expansion for the probability density function P (y,t y0, t0) are computed. P (y,t, y0, t0) satisfies a Fokker-Planck equation, which is equivalent to a Langevin equation for y (t) that provides quantitative predictions for the oil price over times that... 

Under-voltage load shedding is one of the most important tools for avoiding voltage instability. In this paper, an optimal load-shedding algorithm is developed. This approach is based on the concept of the static voltage stability margin and its sensitivity at the maximum loading point or the collapse point. The traditional load-shedding objective is extended to incorporate both technical and economic effects of load shedding. The voltage stability criterion is modeled directly into the load-shedding scheme. The proposed methodology is implemented over the IEEE 14 and 118 bus test systems and solved using a mathematical (GAMS/CONOPT) and two heuristic (PSO and GA) methods. The heuristic... 

This paper presents a new method to analyze the bidding strategies of Generating Companies (GENCOs) with regard to demand elasticity. It is assumed that the available information of each GENCO about its opponents is incomplete and only the minimum and maximum generation levels of their opponents, as well as their fuel type, are known. In the proposed methodology, GENCOs prepare their strategic bids according to a Supply Function Equilibrium (SFE) model. GENCOs will change their bidding strategies until Nash equilibrium points are obtained. The general Algebraic Modeling System (GAMS) has been used to solve the maximization modules using the MINOS optimization software with non Linear...