Sharif Digital Repository

Linear sampling of sparse vectors via sensing matrices has been a much investigated problem in the past decade. The nonlinear sampling methods, such as quadratic forms are also studied marginally to include undesired effects in data acquisition devices (e.g., Taylor series expansion up to two terms). In this paper, we introduce customized nonlinear sampling techniques that provide possibility of sparse signal recovery. The main advantage of the nonlinear method over the conventional linear schemes is the reduction in the number of required samples to 2k for recovery of k-sparse signals. We also introduce a low-complexity reconstruction method similar to the annihilating filter in the... 

In this paper, an innovative method is proposed for material selection. This method is based on the well-known weighting properties approach while integrating a new exponential function in the method to overcome the deficiencies of previously proposed methods. Using a maximum and minimum, in each significant aspect of the problem, for scaling, the values of material properties and achieving more realistic results by not emphasizing on any of the high and low extremes and using an exponential function that ranks the candidates regardless of their number, for improving the performance of the methodology and obtaining more absolute rankings, are some of the advantages of this method. The... 

There are a lot of parameters which are decisive in distribution loss management, such as demand value, energy price, etc. In this paper the cause-and-effect relationships among some of these variables are clearly described. The study demonstrates how a variable in the model will change, if an alteration in one of the other variables occurs. The power system variables considered in this study include energy and loss prices, generation and demand values, distribution loss, distribution system age, number of customers connected to the smart grid, distribution network revenue, and so forth. The smart grid impacts can be studied from two different aspects: 1) the communication infrastructure... 

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... 

In this paper, we study a pricing-inventory model with multiple interdependent products and stochastic demand. In the relevant literature, there are many researches that try to optimize the inventory or price independently and also optimizing joint inventory and pricing problems for single product. But joint optimization of inventory and pricing for multiple interdependent products is relatively new and still there are many potential research gaps in this area. We show that the multiplicative demand form problem, that we develop, is a convex nonlinear programming (NLP) model or is convertible to it. We also provide upper and lower bounds for the additive demand form model  

In this paper, some models have been introduced for dynamic thermal modeling of cast-resin transformers which are based on genetic algorithm. A typical 400kVA cast-resin transformer has been selected and the model parameters are estimated and validated with the help of experimental data extracted from different load cycles. The estimated models are used to generate a reliability model for cast-resin dry-type transformers and the effects of variation in load, ambient temperature and atmosphere conditions on the reliability of castresin transformer are illustrated. As it will be shown in this paper, the effects of working conditions on the life-time of insulation in dry-type transformers is... 

Lack of demand response has always been the main reason for price increasing, shortage of production capacity and system risk increasing as the electricity markets have been greatly involved during the past years. In Electricity market, the exchanges are profitable for producers and consumers when both can participate freely. Based on this new environment, we are currently facing with a new concept as demand-side participation or demand response. There are several demand response programs that accurate pricing of each them is the major challenge that retailers and market operators are facing with. In this article the day-ahead real time pricing contract (DA-RTP) based on two different... 

The accuracy of static neutronic parameters in the nuclear reactors depends upon the determination of group constants of the diffusion equation in the desired geometry. Although several methods have been proposed for calculating these parameters, there is still the need for more reliable methods. In this paper a powerful and innovative method based on Spatial Homogenization and Temperature Variation (SHTV) of physical properties of a WWER-1000 nuclear reactor core for calculating the relative power distribution of Fuel Assemblies (FA) and the hot fuel rod, is presented. The method is based on replacing the heterogeneous lattices of materials with different properties by an equivalent... 

Gelcasting is a novel forming method in fabricating complex three dimensional ceramic parts, and has many parameters and characteristics required to be specified. Up to now, few articles have been published on determination of the idle time of gelation precisely. In this work the chemorheology of gelation in aqueous solution of acrylamide and N, N′ methylenebisacrylamide monomer, and zirconia (PSZ) suspensions of this solution was investigated. As the viscosity of gel system increases abruptly in gelation point, idle time can be determined precisely by measurement of viscosity against time. Idle time can also be determined through temperature measurement against time since the reaction of... 

Depending on the type of dopant metal, many kinds of zircon based pigments are produced and blue vanadium pigment is the most important one of them. In this study, blue zircon ceramic pigments were synthesized from intermediate product, resulting from decomposition of zircon sand with NaOH. In this regard, various amounts of sulfuric acid, water, NH4VO3 as colorant, NaF as mineralizer and extra quartz were added to the prepared Na 2ZrSiO5. Role of quartz was to omit the repercussions of presence of free zirconia in the composition. The main objective of this work is to assess various reactions at different temperatures during blue pigment synthesis. Phase analysis was done by X ray... 

This article studies effects of webpage layout in an online retailer on buyer behavior towards new products and is a sequel to a study performed by authors in department stores. Webpage layout -in terms of parameters which influence buyer behavior- is formulated by two variables; pattern of prices and pattern of popularity. A novel method based on above-mentioned study, has been developed to measure these two factors, so that they can be compared against retailer sales statistics. Investigating this relationship helps both online retailers and marketing agents to better understand effect of webpage layout in promoting a newly developed product. Results show that correlation between price... 

This article studies effects of store layout in a department store on buyer behavior towards new products. Shelf layout -in terms of parameters which influence buyer behavior- is formulated by two variables; pattern of prices and pattern of popularity. A novel method based on previous works of authors has been developed to measure these two factors, so that they can be compared against shares of department sales statistics. Investigating this relationship helps both retailers and marketing agents to better understand effect of shelf layout in promoting a newly developed product. Results show that correlation between price difference and department share is strong. There is also a weaker... 

Next generation wideband and ultra-wideband radar antenna arrays need efficient true-time delay networks for array control. Following the great interest for optical control of antenna array beam steering, performance analysis of optical beam-formers is a must. In this paper signal to noise ratio and dynamic range of simple optical beamforming structures with components off the shelf are investigated theoretically. Especially the effects of certain power combining components such as arrayed wave guide gratings, broadband passive optical combiners and microwave combiners inspected. It turns up that an efficient microwave combiner would surpass the optical combiners in both SNR and dynamic... 

Nature has always been a source of great inspiration for engineers and mathematicians. Evolutionary Algorithms are the latest in a line of natural-based innovations which have had a profound effect on the application of optimization in science and engineering. Although based on nature, Evolutionary Algorithms are nonetheless distinctly different from natural evolution in several areas. This paper outlines early and recent developments of Evolutionary Algorithms while covering those areas of difference. Practical issues related to the use of Evolutionary Algorithms, key parameters that affect the quality of the search and impact of user choices in problem formulation are also covered in this... 

A novel closed form expression is derived for spatial Green's functions of microstrip structures by expanding the spectral Green's function into a Gaussian series. This innovative method is called the Gaussian Green's function (GGF) method due to the Gaussian form in the closed form Green's function representation. The main advantage of the GGF method lies in its precision as well as rapid convergence. To demonstrate the versatility of this method, the current distribution of a microstrip antenna is achieved via the combination of the method of moments (MoM) and GGF method. It is shown that this method can be computationally very efficient with less than 1% error compared to the numerical... 

Modern computer systems require fast, large and reliable memories to handle information explosion. With this goal in mind, not only deployment of main memories with new technologies are necessary, but also adopting innovative solutions for addressing newfound challenges must be considered as a priority. Recently, phase change memory (PCM) appeared as a preferred candidate for substituting DRAM. PCM with non-volatility, low static power consumption and storing multiple level cells (MLC) capability has opened a new way to the future of memories. Although PCM presents considerable potentials, its short lifetime is a critical concern. Worse still, adopting multiple bits per cell capability... 

We present a sampling theory for a class of binary images with finite rate of innovation (FRI). Every image in our model is the restriction of 1{p le; 0} to the image plane, where 1 denotes the indicator function and p is some real bivariate polynomial. This particularly means that the boundaries in the image form a subset of an algebraic curve with the implicit polynomial p. We show that the image parameters - i.e., the polynomial coefficients'satisfy a set of linear annihilation equations with the coefficients being the image moments. The inherent sensitivity of the moments to noise makes the reconstruction process numerically unstable and narrows the choice of the sampling kernels to... 

In the last decade, technological innovations have resulted in considering distributed generation with heat recovery capability in addition to centralised generation. This work aims to develop a comprehensive model analysing techno-economic parameters of energy supply in an office building. The energy model is developed on the basis of the reference energy system with the linear programming technique. The objective function is the annual value of total costs of the energy supply system. The results of the model for the building of Sharif Energy Research Institute indicate that the most appropriate generation technology is an internal combustion engine of 461 kW and a water boiler of 152 kW.... 

The application of the renewable energy sources, especially solar energy, for thermal enhanced oil recovery methods as an economical and environmental valuable technique has received many attractions recently. Concentrated Solar Power systems are capable of producing substantial quantities of steam by means of focused sunlight as the heat source for steam generation. This paper aims to investigate viability of using this innovative technology in fractured reservoirs to generate steam instead of using conventional steam generators. A synthetic fractured reservoir with properties similar to those of giant carbonate oil reserves in the Middle East was designed by using commercial thermal... 

Disease association study is of great importance among various fields of study in bioinformatics. Computational methods happen to be advantageous specifically when experimental approaches fail to obtain accurate results. Haplotypes are believed to be the most responsible biological data for genetic diseases. In this paper, the problem of reconstructing haplotypes from error-containing SNP fragments is discussed For this purpose, two new methods have been proposed by a combination of k-means clustering and particle swarm optimization algorithm. The methods and their implementation results on real biological and simulation datasets are represented which shows that they outperform the methods...