Sharif Digital Repository

In a comparative analysis performance and capacity of DECT, PACS, and PHS for wireless local loop applications have been investigated. This article reports the results of both qualitative and quantitative analyses. The qualitative evaluation consists of a detailed comparison of the parameters of each standard and their relevance in WLL applications. In the quantitative analysis detailed simulations were performed covering diverse sets of conditions. The results of both types of analysis are presented. A major conclusion is that all three standards provide satisfactory performance for WLL applications. For low traffic environments PACS, which can employ larger cells, performs better than the... 

In a comparative analysis performance and capacity of DECT, PACS, and PHS for WLL applications have been investigated. This article reports the results of both qualitative and quantitative analysis. The qualitative evaluation consists of a detailed comparison of the parameters of each standard and their relevance in WLL applications. In the quantitative analysis detailed simulations have been performed covering diversified sets of conditions. The results of both types of analysis are presented. A major conclusion is that all three standards provide satisfactory performance for WLL applications. For low-traffic environments PACS, which can employ larger cells, performs better than the other... 

The present paper focuses on medium-term effects of alternative windfall management strategies for a resource abundant country where the resource revenues are expected to last over a prolonged period. In particular, the trade-off between spending and saving is analyzed within the framework of a recursive dynamic computable general equilibrium model. The model is further validated against historical data available for 2001-2010. The total factor productivity is calculated endogenously in the model based on a function that reflects the changes in factor productivity. The results suggest that saving oil revenues, whether in an oil fund or through physical investment in domestic sectors, leads... 

In the natural gas transmission network, from supply points to demand nods there are various technological options that include processing, transportation, conversion and gas distribution. Comprehensive analysis of natural gas network requires evaluation of different chains of gas flow through various levels based on economical and environmental criteria subject to technical and operational constraints such as feasibility, operability and reliability of different alternatives. To aid decision-making process in the sector of natural gas, a generic optimization-based model has been developed for assessing long term energy issues related to planning and design of natural gas supply systems. The... 

This study presents economic and formation investigations on hydration effects by looking at natural gas hydrate (NGH) storage and transportation processes and formation conditions. The investigation includes experiments with methane. The obtained results show that the methane formation time increased linearly as the subcooling temperature decreased. Furthermore, the economic result indicates that the energy consumption parameter is appropriate for examining resource consumption for a system that, in turn, results in optimal capital investment through the storage and transportation process of NGH. The results also show that energy consumption increases logarithmically as the hydrate... 

In this article, a solar absorption chiller used in MehrAbad region of Tehran, Iran is optimized with exergoeconomic principles and genetic algorithm. After optimizing, a storage system with Phase Change Material technique (PCM) is designed for this optimum configuration for supporting system when sunshine is not received adequately, especially at night. Exergoeconomic analysis is based on finding some ways to improving the performance of a thermal system considering economic constrains. In this study, the exergoeconomic optimization is applied for LiBr-water absorption. The results show that total investment cost of main system, the whole of system except storage system, has increased... 

In Iran, there are more than 15,000. MW of wind power potential, but only about 90. MW have been installed since 2009. Because fuel costs are the main part of fuel-consumed power generation costs and fossil resource costs are highly subsidized in Iran, renewable energies such as wind power have yet to be fully developed. This analysis sets out to evaluate the total generating costs of wind power and conventional power plants in Iran. A levelized cost approach was conducted that included investment costs, O&M costs, fuel costs and external costs of emissions for each type of technology. Comparison of cost assessments of power generation show that by taking into account global fuel prices and... 

Distributed Generation (DG) has received increasing attention during the last decade. Advantage and constraints of DG application are well known to both DG owner and electric utility. Various technologies are available for DG units among them gas GenSet is, in particular, more attractive to the investors as the technology provides the control on DG generation. However, there are various financial risks associated with dispatchable DG units that prohibit wide private investment in such technologies. This paper examines the use of financial tools to manage dispatchable DG economic risks. A comprehensive framework has been proposed to consider various economic risks to DG owner. Suitable models... 

The main propose of this research is providing a tool for suitable modeling, increase efficiency and decrease construction cost of solar absorption chiller. At first, the solar absorption chiller is modeled by the thermodynamic laws. Then, this model is converted to the new standard mathematical programming model with considering all technical and economic constrains. This mathematical model is optimized by Genetic algorithm (GA). After applying GA, optimized parameters of chiller heat exchanger designing and its electricity consumption are calculated. These parameters consist of heat exchanger effectiveness, heat transfer cross section area, heat transfer coefficient, efficiency of pump and... 

In the past decades, remote control switches have been broadly integrated into distribution systems to achieve a certain level of service reliability. To take utmost benefits of them, a cost-benefit analysis should be conducted. In this regard, the budget restriction plays a crucial role in remote control switch placement. This paper is aimed at proposing a model to determine the optimal number and location of remote control switches in a distribution system. As the main contribution of the paper, the model is developed in multistage planning format to address the issue of budget limitation. To this end, the model is formulated in mixed integer linear programming format, which tries to... 

Using plant level panel data of manufacturing firms in Iran from 2003 to 2013, we test the Dutch disease predictions, including the impact of a rise in oil prices on intensive and extensive margins of trade. Our findings indicate that during periods of high oil prices domestic currency appreciates, but contrary to resource curse theories, domestic firms export more, and new firms enter foreign markets. We reconcile this paradox by proposing a new channel, which we call “subsidy disease.” Despite rising oil prices, the government of Iran kept domestic energy prices at low levels, which increased the implicit subsidy accruing to energy intensive firms. In effect, these firms gain a competitive... 

The facility location problem and its related financial issues have a significant impact on the configuration of a supply chain structure (SCS). Although affording the setup cost of facilities requires a huge financial investment, a meticulous planning to recoup it has been neglected by an overwhelming majority of previous studies. To fill this gap, an economical investment plan of facilities is determined by striking a trade-off between the contribution of the stockholders’ capital and the loan arrangement. In the context of a multiperiod three-echelon SCS, the model also determines the optimum location of plants and the best supply and distribution patterns. The model maximizes the fill... 

Exergy and exergoeconomic analyses have been used to set out weaknesses of the postcombustion CO2 capture unit of Besat power plant that uses an ammonia absorption refrigeration system for CO2 liquefaction. The energy required for the absorption system is provided by the flue gas. The liquefied CO2 is used for beverage and food industries. The exergoeconomic costs of all utility streams and processes are calculated through a systematic method of assigning exergetic cost relations to the streams. The results point out that the exergy destruction of the CO2 stripper and absorber columns are the highest, and according to the cost-based information, potential locations for the process... 

Remote controlled switch deployment in distribution networks is usually justified via comparing the required investment with the expected decrease in interruption costs. Although the investment is known prior to the implementation, the stochastic nature of contingencies imposes significant uncertainty on interruption costs. The uncertainty may impose substantial financial risks on the distribution company. This paper aims at evaluating the financial risk and key affecting parameters. For doing so, a step-by-step method is presented to evaluate the risk. The method captures the stochastic nature of contingencies through a sequential Monte Carlo simulation approach. A mathematical formulation... 

A rapid wax injection tool of a gearbox shift fork was designed, simulated, and manufactured using rapid prototyping and rapid tooling technology to save time and cost of producing wax models used for the investment casting process. CAE simulation softwares, in particular, MoldFlow, are used to get wax injection moulding parameters such as filling parameters, temperature profiles, freeze time, speed, and pressure. The results of this research were compared with conventional wax model production methods. The criteria of such comparison were based upon parameters such as time, cost, and other related characteristics, which resulted in saving of 50% in time and 60% in cost. In this research,... 

Limited access to energy resources and increasing demand for mitigation of the environmental impacts have necessitated higher production efficiencies. Therefore, the promotion of R&D activities has been one of the main parts of national energy policies. In this research work, two methods are used for assessing the effectiveness of the R&D capital on resource conservation. First, by developing the resource-included knowledge production function of the energy sector and second, through direct assessment of the functionality of resource productivity from R&D capital. Based on official data provided by national statistical centers, a comparative analysis has been conducted to examine the... 

Increasing the intermittent outputs of renewable energy sources (RESs) has forced planners to define a new concept named flexibility. In this regard, some short- and long-term solutions, such as transmission expansion planning (TEP) and energy storage systems (ESSs) have been suggested to improve the flexibility amount. A proper optimization procedure is required to choose an optimal solution to improve flexibility. Therefore, a mixed-integer linear programming (MILP) direct-optimization TEP versus ESSs co-planning model is presented in this paper to enhance power system flexibility. In doing so, a novel RES-BESS-based grid-scale system flexibility metric is proposed to investigate the... 

Optimal planning of residential complex energy systems requires thorough mathematical modelling to address the interconnections between all the energy installations from the largest ones, shared by all the residents, to the smallest ones in each distinct unit. Besides, conflicting desires of investors and residents in various aspects such as reliability index make this problem more challenging. In response, this paper presents a thorough framework to obtain the optimum design and operation of a residential complex energy system from scratch. To address the appropriate interconnection between various components of such an energy system, a multi-layer energy hub structure is proposed. Besides,... 

In this paper, a robust distribution system expansion planning (DSP) approach is presented to supply the load growth locally and move toward nearly zero energy local distribution areas (LDAs). In the proposed approach, a distribution system operator (DSO) is responsible for secure and optimum operation of LDAs. Therefore, investors on distribution system upgrades use this approach to maximize the profit on investments by determining the installation year of new distribution feeders and energy resources, distributed energy resource (DER) placements and sizes considered by corresponding DSOs. The accurate AC power flow solution is used and mathematical methods are developed to model the DSP as...