Sharif Digital Repository

In this paper, we have proposed a fast and easy-to-develop FPGA-based fault injection technique. This technique uses the Altera FPGAs debugging facilities in order to inject SEU fault model in both flip-flops and memory units. Since this method uses the FPGAs built-in facilities, it imposes a negligible performance and area overhead on the system. The experimental results on Leon2 processor shows that the proposed technique is on average four orders of magnitude faster than a simulation-based fault injection  

In the current paper, a general theoretical model for the problem of micromirrors under the effect of capillary forces is presented. The presented model considers the coupling effect between torsion and bending of the torsion beams supporting the micromirror. First, the energy method, the principal of minimum potential energy is utilized for finding the equations governing the micromirror rotation and its deflection. Then using the implicit functions theorem, the equations governing the pull-in angle and pull-in displacement of the micromirror is derived. The results, shows that ignoring the bending effect in micromirrors under the effect of capillary forces, can cause a significant (up to... 

In this paper we evaluate the performance of a spectrally-phase-encoded-OCDMA system using a receiver structure based on second harmonic generation effect. We approximate the decision variable moment generating function and obtain the error probability using saddle-point approximation. The impact of different parameters, e.g., code length, and photodetectors' speed, is studied. © 2009 OSA/ACP 2009  

We unify virtual-method despatch (polymorphism implementation) and network packet-routing operations; virtual-method calls correspond to network packets, and network addresses are allocated such that routing the packet corresponds to dispatching the call. As the run-time routing structure is inherent in Network-on-Chip platforms, this unification implements polymorphism/or free.1  

This paper presents the most frequently used maintenance concerns and challenges in distribution utilities of Iran. A questionnaire is devised and distributed among the maintenance experts in more than 30 distribution utilities all over Iran and their responses have been taken under consideration in this paper. The aim is to get the most out of the successful maintenance experiences within the utilities, to find the solutions on the current common challenges on the distribution system maintenance policies, and eventually to enlighten the way on the transition to the more efficient maintenance approaches such as reliability-centered maintenance (RCM) in distribution systems  

Smart grids are envisioned to support large penetrations of electrical vehicles driven by economical and environmental signals. Nevertheless, distribution system operators are becoming concerned about distribution congestion that may occur in the network with multiple domestic plug-in hybrid electric vehicles (PHEVs) charging. Therefore, investigating the impacts of high PHEV penetration levels on the performance of distribution networks seems to be essential for system operators and planners. Doing so, in this paper, PHEV characteristics are precisely extracted from valid published reports and surveys. Accordingly, a comprehensive model for investigating the impacts of different PHEV... 

The design process always has some known or unknown uncertainties in the design variables and parameters. The aim of robust design is minimization of performance sensitivity to uncertainties. Tolerance allocation process can significantly affect quality and robustness of the product. In this paper, a methodology to minimize a product's sensitivity to uncertainties by allocating manufacturing tolerances is presented. The robust tolerance design problem is formulated as a multi-objective optimization based on the combined function-uncertainty-cost model. Genetic algorithm is utilized to solve the multi-objective optimization and a case study is presented to illustrate the methodology  

In this research an analytical model for performance prediction of centrifugal compressors is developed. The loss mechanisms are investigated in impeller, diffuser and volute separately for wide operating rotational speeds of the compressor. The contributions of compressor components in total entropy generation are further studied using different experimental correlations and methods. The results are verified using experimental test results, carried out at Sharif University of technology Turbocharger laboratory which has been designed to derive performance curves of turbocharger compressors. The test rig is equipped to measure static and stagnation pressures at inlet and outlet of each... 

The objective of this work is to study the effects of harmonics on energy meters. This study is canied out based on IEEE 1459 standard through extensive tests on some energy meters installed at Gil an utility consumers. First, a review on IEEE 1459 standard on power definitions will be given. The definitions are then ervaluated for a compact Fluorescent Lamp (CFL) as a harmonic generating load. Then, the results of the performance e-alnation of two energy meters are presented for different linear and nonlinear loads based on IEEE1459 standard power definitions. Two different test procedures are performed for this putpose. In the first series of tests, a harmonic polluted voltage is applied... 

This paper aims to quantitatively evaluate and compare the reliability impact of employing an automatic loop restoration scheme in a typical distribution system, with and without pulse closing technology. Sustained interruptions, momentary interruptions and voltage sags are the three major attributes of the service reliability that are taken into account in the reliability case studies  

This paper presents the most frequently used maintenance concerns and challenges in distribution utilities of Iran. A questionnaire is devised and distributed among the maintenance experts in more than 30 distribution utilities all over Iran and their responses have been taken under consideration in this paper. The aim is to get the most out of the successful maintenance experiences within the utilities, to find the solutions on the current common challenges on the distribution system maintenance policies, and eventually to enlighten the way on the transition to the more efficient maintenance approaches such as reliability-centered maintenance (RCM) in distribution systems  

Movement and transportation of fine particles in formations leads to clogging the pores and reduction in permeability. This type of formation damage is stronglycontingent upon water salinity and ionic conditions in the formation. The main parameters which control the particle release are the interactions and forces between particles and porous medium surfaces. Changing salinity which leads to pH alteration, affects these interactions and subsequently the fine migration process. Hence, pH and salinity variations should be considered to study and evaluate the portion of fine migration in formation damage. The principal challenge in this research therefore, is to try to change the surface... 

Whole level of the erosion and the resistance of rocks which were composed closured have been studied, besides, the impact of temperature and laser irradiation for more investigation about this issue has been involved before all. This subject more reveals the matter which laser absorption on the laboratory scale using laser to what extent can cause the augment of the relative permeability and secondary porosity of reservoir rock, that of the vertical and horizontal useful connectivity and eventually that of the positive transferability. This research has been carried out in the form of case study on one of Iranian south west formations in north east of Behbahan city in Iran, either the rate... 

We propose an all-optical arbitration architecture to resolve end-point contention in the optical networks-on-chip. The proposed architecture reduces on-chip optical power and energy losses by 37% and 21%, respectively, compared to Corona's token-based control plane  

In this paper, the static pull-in phenomenon is investigated in circular micro-plates subjected to capillary force. The capillary force appears in micro-scale structures due to presence of a liquid bridge. The governing equation of a circular micro-plate subjected to capillary force is presented and the static deflection of a fully-clamped circular plate is evaluated. Moreover, the effect of the normalized adhesion tension caused due to the capillary force on the static pull-in of the micro-plate is assessed  

Scale formation is one of the major problems in oilfields. Removal of scales is a difficult process due to their relative hardness and low solubility. Therefore it is valuable to find a method which can remove damages caused by scales. Ultrasonic radiation is known have the sufficient energy to remove the scales. Our purpose is to investigate the role of ultrasound on permeability increments due to scale removal. Some experiments were carried out to find these effects and observed that ultrasound has increased volumetric mass transfer, concentration and solubility limits. We also worked on a model presented by Tahmasebi et. al[2010] and applied changes on it to make it able to predict... 

Surface registration is a necessary step and widely used in medical image-aided surgery. It's relevance to medical imaging is that there is much useful anatomical information in the form of collected surface points which originate from complimentary modalities. In this study, the kinematic relations between two point clouds with different coordinate definitions have been generated. Using Influence Method of surface modeling for extracting point clouds functions, the transformation matrix would be resulted. The proposed method was applied for an experimental femur data points(651 points) using the MRI images. These data points were transformed in a 30 degrees flexion of knee. This... 

Ornamental stone sawability is important in predicting the prime cost of production and planning of the stone quarries and factories. Ornamental stone sawability with two standard methods, wire and circular sawing, is dependent on many parameters including; the stone that be sawn and machine characteristics and saw operating characteristic. The investigation of these parameters and the determination of the optimum working conditions for sawing machines in the stone industry is significant for establishing the most suitable and economic usage of the sawing method in the future. Up to now, various attempts have been made to determine these parameters. In this review paper, the important... 

This paper presents stability analysis of a distributed generation (DG) controller [1], in an islanded mode, based on the Mapping Theorem and the Zero Exclusion Condition, and validates the results based on a laboratory scale experimental setup. The DG unit is interfaced to the host system through a voltage-sourced converter (VSC). The control strategy regulates the load voltage at the desired value in the islanded mode, despite uncertainties in the load parameters. The frequency of the island is controlled in an open loop manner by an internal oscillator. The experimental results show that the controller provides robust voltage control for a wide range of load parameters, and even maintains... 

Till now, no mathematical model is presented to model the flow under sonic field be applied in fractured reservoirs. This will be more noticeable when we bear in mind that several reservoirs in Middle East region are fractured. In this work the effects of elastic waves on capillary trapping and mobility of Bingham plastic fluids in fractures have been investigated. Eventually, a model for predicting the influence range of the wave in fractured reservoirs is presented. The results of this study clarified that radiation of wave with low frequency and intensity extremely increases the flow rate and decreases the minimum pressure gradient required for flow of Bingham plastic fluids in fractured...