Sharif Digital Repository

New advances in mobile computer technology,along with rapid growth of quality and quantity of wireless networks, introduce new capabilities, applications, and concerns to computer science and industry. Mobile payment, in which mobile customers use their phones for performing financial transactions,is a promising and exciting domain that has been rapidly developing recently. Although different mobile payment schemes has been designed and deployed worldwide, there is still a lack of research in achieving efficient and global mobile payment systems. Different business players and various technologies make the situation more complex. In this paper, we present MPaySmart, a secure and... 

New Advances in mobile computer technology, along with rapid growth of quality and quantity of wireless networks, introduce new capabilities, applications, and concerns to computer science and industry. Unique requirements and constraints of mobile systems bring new challenges to software development for such environments. It demands reconsidering the traditional approaches of information access, software design, and performance evaluation. Despite the various constraints and problems, research endeavors aimed at ameliorating the status quo through enhancing/devising software design and performance evaluation techniques for mobile software systems have been relatively few and far in between.... 

New Advances in mobile computer technology and the rapid growth of wireless networks in quality and quantity has introduced new applications and concerns in computer science and industry. The unique requirements and constraints associated with mobile systems have brought new challenges to software development for such environments, as it demands extensive improvements to traditional systems development methodologies in order to fulfill the special needs of this field. We examine the challenges of developing software for mobile systems, starting by reviewing mobile systems' characteristics and investigating the status quo of mobile software development methods. It has been shown that Agile... 

In this paper we offer a tuning method for the design of stabilizing PI controllers that utilizes the stability region centroid in the controller parameter space. To this end, analytical formulas are derived to describe the stability boundaries of a class of relative-degree-one linear time invariant second-order systems, the stability region of which has a closed convex shape. The so-called centroid stable point is then calculated analytically and the resultant set of algebraic formulas are utilized to tune the controller parameters. The freedom to choose the surface density function in the calculation of centroid stable point provides the designer with the possibility to incorporate optimal... 

The problem of latency in data acquisition, which is specific to the case of mobile wireless sensor networks, has been introduced and investigated. In this regard, the properties of the so-called Data Acquisition Latency Error, and the way it affects the performance of the respective localization schemes in a mobile network were discussed through both theoretical analysis and simulations. Moreover, a weighted version of lateration scheme was introduced and shown to outperform the traditional one, while tracking a mobile node. This work is to the best of our knowledge the first to have addressed the aforementioned problem in mobile wireless sensor networks, and to have offered a solution for... 

In this paper, an algebraic rule for tuning the integer realizations of fractional-order PI controllers is developed, with an integral square error performance index, which outperforms that of an optimal ordinary PI controller. To this end, the PIλ control structure is used in conjunction with a third-order integer approximating filter to provide a three parameter fixed-structure extension of the ordinary PI controller. Next, the extra degree of freedom in setting the order of integration λ is leveraged to introduce a steepest descent direction in the extended controller parameter space. It is then stated that shifting the parameters of an ordinary PI controller along the proposed descent... 

This paper offers a systematic framework for the design of suboptimal integer-order controllers based on fractional-order structures. The proposed approach is built upon the integer-order approximations that are traditionally used to implement fractional-order controllers after they are designed. Accordingly, the fractional-order structures are exploited to derive a suitable parameterization for a fixed-structure integer-order controller. The parameters, which describe the structure of the fixed-order integer controller, are the same as those used to describe the original fractional structure. Optimal tuning is then performed in the parameter space of the fractional structure and the... 

The problem of tuning a two-parameter controller has been formulated as finding the centroid of the admissible region specified by the set of constraints that the controller should satisfy. The constraints can be as general as the closed-loop system stability or they may include several requirements on various stability, sensitivity, or performance measures. The design of stabilizing proportional-derivative (PD) controllers using the centroid of the stability region in the controller parameter space is considered as a case study. To this end, analytical formulas are derived to describe the stability boundaries of a class of integrating time delay systems, the stability region of which has a... 

This paper proposes a scheme for computing the stable regions from which the parameters of a fractional-order PI controller can be selected. In particular, we extend a previously investigated method for plotting the stability regions of PIλ controllers to their integer-order approximations. Next we compare the two stability regions and derive their overlapping sections, which is referred to as the implementable stability region. In order for the final closed-loop system to be stable, the designer must choose the controller parameters from the overlapping section of the two stability regions. The devised scheme we believe can facilitate the design procedure for fractional-order PI... 

This paper proposes a scheme for computing the stable regions from which the parameters of fractional-order proportional-integral (PI) and proportional-derivative (PD) controllers can be selected. In particular, a previously investigated method for plotting the stability regions of PI λ and PDμ controllers is extended to their integer-order approximations. Next, the two stability regions are compared and their overlapping sections, referred to as the implementable stability region, are derived. In order for the final closed-loop system to be stable, the designer must choose the controller parameters from the overlapping section of the two stability regions. Simulation results for two example... 

This paper is seeking to design a dynamic cellular manufacturing system (DCMS). Area of multi-objective optimization is attractive not only for offering new opportunities for defining problem, but it helps us to extend and solve the anonymous problem. So a new multi-objective mixed integer model is presented for DCMS. The proposed model considers some real-world critical conditions in lean production which are neglected in similar studies in the literature. This model solves the part and machine grouping simultaneously with labor assignment to minimize the cost of various terms like reassignment cost of human resource, over time cost of equipments and labors, and maximize utilization rate of... 

The general goal of the facility layout problem is to arrange a given number of facilities to minimize the total cost associated with the known or projected interactions between them. One of the special classes of the facility layout problem is the Single Row Facility Layout Problem (SRFLP), which consists of finding an optimal linear placement of rectangular facilities with varying dimensions on a straight line. This paper first presents and proves a theorem to find the optimal solution of a special case of SRFLP. The results obtained by this theorem prove to be very useful in reducing the computational efforts when a new algorithm based on tabu search for the SRFLP is proposed in this... 

In this paper, we have discussed the results of sensitivity analysis in a payoff matrix of the Matching Pennies game. After representing the game as a LP model, the sensitivity analysis of the elements of the payoff matrix is presented. The game value and the optimal strategies for different values of parameters are determined and compared  

By locating a steel shear panel on the intersection point of the X-braces, concentrically or eccentrically braced shear panel (CBFSP or EBFSP) is formed. In this paper, to perform parametric study, 1-story CBFSP and EBFSP models with span length greater or less than height are considered. Using linear static analyses, the effects of size and location of the shear panel on the lateral stiffness of the frame with respect to the moment resisting frame with the same member sections are investigated. Next, for 1- And 3-story models, maximum displacement, along with base shear, and the ratio between the dissipated energy and input energy are examined under 4 ground motion records. Behavior of the...