Sharif Digital Repository

Performance evaluation and efficiency analysis is considered to be one of the critical responsibilities of the management department. This paper investigates and assesses the efficiency and performance of Iranian insurance companies through nonparametric frontier analysis (FA) models. The two well-known nonparametric FA models, data envelopment analysis (DEA) and free disposal hull, are utilized to separate the efficient companies from the inefficient companies, and two well-known super-efficiency analysis models are utilized to rank the efficient units. For the further analysis, critical inputs are also identified for inefficient companies using DEA sensitivity analysis which is a powerful... 

While the transistor density continues to grow exponentially in Field-Programmable Gate Arrays (FPGAs), the increased leakage current of CMOS transistors act as a power wall for the aggressive integration of transistors in a single die. One recently trend to alleviate the power wall in FPGAs is to turn off inactive regions of the silicon die, referred to as dark silicon. This paper presents a reconfigurable architecture to enable effective fine-grained power gating of unused Logic Blocks (LBs) in FPGAs. In the proposed architecture, the traditional soft logic is replaced with Mega Cells (MCs), each consists of a set of complementary Generic Reconfigurable Hard Logic (GRHL) and a conventional... 

An information system network (ISN) can be modeled as a stochastic-flow network (SFN). There are several algorithms to evaluate reliability of an SFN in terms of Minimal Cuts (MCs). The existing algorithms commonly first find all the upper boundary points (called d-MCs) in an SFN, and then determine the reliability of the network using some approaches such as inclusion-exclusion method, sum of disjoint products, etc. However, most of the algorithms have been compared via complexity results or through one or two benchmark networks. Thus, comparing those algorithms through random test problems can be desired. Here, the authors first state a simple improved algorithm. Then, by generating a... 

Accurate description of wall-bounded turbulent flows requires a fine grid near walls to fully resolve the boundary layers. We consider a locally simplified transport model using an assumed near-wall viscosity profile to project the wall boundary conditions using the boundary transfer method. Related coefficients are obtained numerically. By choosing a near-wall viscosity profile, we derive an analytic wall function, which significantly reduces the CPU costs. The performance of this wall function is compared to other near-wall treatments proposed in the literature for two frequently used benchmark cases: near-equilibrium channel flow and flow over a backward-facing step with separation and... 

Ensemble Kalman filter, EnKF, as a Monte Carlo sequential data assimilation method has emerged promisingly for subsurface media characterization during past decade. Due to high computational cost of large ensemble size, EnKF is limited to small ensemble set in practice. This results in appearance of spurious correlation in covariance structure leading to incorrect or probable divergence of updated realizations. In this paper, a universal/adaptive thresholding method is presented to remove and/or mitigate spurious correlation problem in the forecast covariance matrix. This method is, then, extended to regularize Kalman gain directly. Four different thresholding functions have been considered... 

This paper introduces an alternative Fault-Tolerant Power-Aware Hybrid Adder (or simply FARHAD). FARHAD is a highly power efficient protection solution against errors in application with high number of additions. FARHAD, similar to earlier studies, relies on performing add operations twice to detect errors. Unlike previous studies, FARHAD uses an aggressive adder to produce the initial outcome and a low-power adder to generate the second outcome, referred to as the checker. FARHAD uses checkpointing, a feature already available to high-performance processors, to recover from errors. FARHAD achieves the high energy-efficiency of timeredundant solutions and the high performance of... 

Application of advanced process control methods in a chemical plant requires a model which represents the transient behaviour of the plant. However, only a few plant-wide identification methods have been proposed for chemical processes. In this paper, an objectoriented process identifier (OPI) framework has been introduced for plant-wide identification to show how using object-oriented design can provide a general plant-wide modelling framework for various systems including chemical processes. The interactions between units are considered in plant-wide identification methods. As a result, the obtained models can predict the system behaviour in new operating conditions better than those... 

A mixed binary integer mathematical programming model is developed in this paper for ordering items in multi-item multi-period inventory control systems, in which unit and incremental quantity discounts as well as interest and inflation factors are considered. Although the demand rates are assumed deterministic, they may vary in different periods. The situation considered for the problem at hand is similar to a seasonal inventory control model in which orders and sales happen in a given season. To make the model more realistic, three types of constraints including storage space, budget, and order quantity are simultaneously considered. The goal is to find optimal order quantities of the... 

Synthesis of the optimum distillation column sequence (DCS), which incorporates a huge search space composed of both conventional and complex arrangements, is a highly complicated combinatorial problem in the field of chemical process design and optimisation. In this study, a novel procedure for the synthesis of optimum DCS proposed by Boozarjomehry et al. [Boozarjomehry et al., Can. J. Chem. Eng. 87, 477-492 (2009)] is expanded to include the complex distillation arrangements. The method is based on evolutionary algorithms, and the total annual cost (TAC) is the main criterion used to screen alternatives. Efficient procedure has been proposed for encoding mechanism to include and classify... 

In this work we introduce power optimizations relying on partial tag comparison (PTC) in snoop-based chip multiprocessors. Our optimizations rely on the observation that detecting tag mismatches in a snoop-based chip multiprocessor does not require aggressively processing the entire tag. In fact, a high percentage of cache mismatches could be detected by utilizing a small subset but highly informative portion of the tag bits. Based on this, we introduce a source-based snoop filtering mechanism referred to as S-PTC. In S-PTC possible remote tag mismatches are detected prior to sending the request. We reduce power as S-PTC prevents sending unnecessary snoops and avoids unessential tag lookups... 

This paper presents a low cost fault-tolerant technique so called OWHR (Operand Width Aware Hardware Reuse) to ALU design in embedded processors. The OWHR technique is motivated by two facts: (1) Many of the produced and consumed values are narrow-width values in the embedded processors, i.e. they have leading zeros or ones in their most significant bits. This indicates that only a fraction of the circuit is performing useful operations when a particular arithmetic or logic circuit in the ALU is operating on narrow-width values; (2) other circuits of the ALU are not used, when a particular arithmetic or logic circuit is being utilized to perform a specific operation in the ALU in the... 

Many of the physical macroscopic quantities could be explained as the result of a collection of microscopic particles which act independent of each-other, in a linear fashion. Since the physical laws of the interaction of these particles with their surrounding medium are non-deterministic, one could think of these particles as the generators of a linear stochastic field. In this paper, we have introduced a derivation which has yielded an equation for the spatiotemporal correlations in such a field. The derivation is simple and extendable to include the behavior of many physical particles. A simple numerical algorithm has been devised to solve the obtained initial value integrodifferential... 

In a gas transmission network (GTN), faults can easily propagate due to the interconnections of streams. The main objective of this paper is to develop a systematic framework for an online decision support system (DSS) in order to make the right decisions to get the GTN out of critical conditions (which cannot be handled by the plant controllers) smoothly. One of the key features of the proposed scheme is its lack of dependence on prior knowledge of the fault signals (e.g., number of faults, and their origin). In this article, the GTN is modeled by a fuzzy directed graph (FDG). The proposed approach utilizes a reasoning algorithm based on the deviations that exist in the process variables... 

Normal basis multiplication in finite fields is vastly utilized in different applications, including error control coding and the like due to its advantageous characteristics and the fact that squaring of elements can be obtained without hardware complexity. In this brief, we present decomposition algorithms to develop novel systolic structures for digit-level Gaussian normal basis multiplication over GF (2m). The proposed architectures are suitable for high-performance applications, which require fast computations in finite fields with high throughputs. We also present the results of our application-specific integrated circuit synthesis using a 65-nm standard-cell library to benchmark the... 

In this study, cell-centered (CC) and cell-vertex (CV) finite volume (FV) approaches are applied and assessed for the simulation of two-dimensional structural dynamics on arbitrary quadrilateral grids. For the calculation of boundary nodes displacement in the CC FV approach, three methods are employed. The first method is a simple linear regression of displacement of boundary nodes from the displacement of interior cell centers. In the second method, an extrapolation technique is applied for this purpose and, in the third method; the line boundary cell technique is incorporated into the solution algorithm in an explicit manner. To study the effects of grid irregularity on the results of CC... 

Process variation has already emerged as a major concern in design of multi-processor system on chips (MPSoC). In recent years, there have been several attempts to bring variability awareness into the task scheduling process of embedded MPSoCs to improve performance yield. This study attempts to provide a comparative study of the current variation-aware design-time task and communication scheduling techniques that target embedded MPSoCs. To this end, the authors first use a sign-off variability modelling framework to accurately estimate the frequency distribution of MPSoC components. The task scheduling methods are then compared in terms of both the quality of the final solution and the... 

In this paper, a framework for distributed and decentralized state estimation in high-pressure and long-distance gas transmission networks (GTNs) is proposed. The non-isothermal model of the plant including mass, momentum and energy balance equations are used to simulate the dynamic behavior. Due to several disadvantages of implementing a centralized Kalman filter for large-scale systems, the continuous/discrete form of extended Kalman filter for distributed and decentralized estimation (DDE) has been extended for these systems. Accordingly, the global model is decomposed into several subsystems, called local models. Some heuristic rules are suggested for system decomposition in gas pipeline... 

Delay in communication wires causes design iterations in system-on-chip. Latency-insensitive design copes with this issue by encapsulating each core in a shell wrapper and inserting buffers in the wires to separate the design of core from that of communication wires. Scheduling-based latency-insensitive protocol is a methodology which employs shift registers for periodic clock gating of blocks instead of the shell wrappers. In many cases, the bit sequences inside the shift registers are too long and therefore consume a large area. This study presents a heuristic algorithm that optimises the bit sequences and produces them with shorter lengths compared with the existing method. The algorithm... 

In today's competitive world, having an effective business intelligent (BI) system for monitoring and evaluation of industrial and product oriented organizations is vital. A perfect BI must help managers not only to speed up his decision making process; but also to increase quality of their decision. But how? One of the main specifications of an effective BI system is providing managers by correct format of information and at the correct time. Critical Success Factors (CSFs) are a kind of significant factors that must be considered in attaining an organization's goal; and key performance indicators (KPIs) are a type of quantitative and measurable CSF; and one character of an effective BI is...