Sharif Digital Repository

Although the fractional delay filtering literature is full of design methods and implementation techniques for fractional sample interpolators, a fundamental need for the proposition of low-order efficient designs still strongly exists. Proposed is such a system for half-sample interpolation. In contrast to the typical systems studied in the literature for fractional delay filtering, the system proposed continuously adapts its interpolation kernel to the statistical variations of the input signal, and this is in fact the reason for it being needless of having a high order. Satisfactory performance of the proposed structure has been demonstrated via simulation  

In performance-based geotechnical earthquake engineering, the required degree and spatial extent of ground densification for mitigation of liquefaction beneath a structure should be determined based on the acceptable levels of performance of foundation. Currently, there is no solution for evaluation of the amount of settlement and tilt of footings constructed on a densified ground which is surrounded by a liquefiable soil. This implies the need for numerical procedures for simulation of seismic behavior of shallow foundations supported on both liquefiable and densified subsoil. In this paper, the dynamic response of shallow foundations on a densified ground is studied using a 3D fully... 

High reliability, low power consumption and high performance are key objectives in the design of NoCs. These three design objectives should be considered simultaneously in order to have an optimal design. This paper proposes a method to reduce power consumption of an application specific NoC. This is done in two steps: 1) Extra virtual channels are used in the router architecture to increase the performance in an application specific NoC, and 2) The amount of the performance gain is then set to the initial point using frequency scaling technique, hence reducing the power consumption, without corruption of reliability. The simulation results show that the method can reduce the power... 

This paper presents a SEU-mitigative placement and route of circuits in the FPGAs which is based on the popular placement and route tool The tool is modified so that during placement and routing, decisions are taken with awareness of SEU-mitigation and no redundancies during the placement and routing are used but the algorithms are based on the SEU avoidance. We have investigated the effect of this tool on several MCNC benchmarks and the results of the placement and routing have been compared to the traditional one. The evaluations of results show that placement and routing can decrease the SEU rate of circuits implemented on FPGAs about 22%. However, it increases critical path delay and... 

New advances in mobile-computer technology, together with the advent of wireless networking, introduce new requirements, capabilities and concerns to the computer science and industry. In this paper, we discuss the special requirements of file sharing in mobile environments. Then our proposed architecture for mobile file sharing (MobFish) is presented. Finally, we present an implementation of the proposed architecture based on its special design tactics. © 2006 by Knowledge Systems Institute Graduate School. All rights reserved  

We present an embedded-system design flow, discuss its details, and demonstrate its advantages. We adopt the object-oriented methodology for the system-level model because software dominates hardware in embedded systems and the object-oriented methodology is already established for software design and reuse. As the building-block of system implementation, we synthesise application-specific processors that are reusable, through programming, for several related applications. This addresses the high cost and risk of manufacturing specialised hardware tailored to only a single application. Both the processor and its software are generated from the model of the system by the synthesis and... 

Purpose - This paper aims to present the design and implementation of VirSense, a novel six-DOF haptic interface system, with an emphasis on its gravity compensation and fixed-base motors. Design/methodology/approach - In this paper, the design and manufacture of the VirSense robot and its comparison with the existing haptic devices are presented. The kinematic analysis of the robot, design of the components, and manufacturing of the robot are explained as well. Findings - The proposed system is employed to generate a Virtual Sense (VirSense) with fixed-base motors and a spring compensation system for counterbalancing the torques generated by the weight of the links. The fixed bases of the... 

This paper is an attempt to develop a design methodology for a special deployable structure for potential use in micro-satellites. The basic form of this structure is a hexagonal prismatic tensegrity structure, which, after being rigidified, is used as the supporting structure of a mesh-like antenna. Here, the objectives of presenting the design methodology are to prevent structural elements from failure, while maintaining the structural natural frequency and mesh tension above an intended value and in addition, to minimize the overall mass. Here, the suggested design strategy combines the need for a behavioral study (i.e. fast and wide range evaluation) at the beginning of the design, with... 

Interactive and integrated design and manufacturing can be a useful strategy for designers to reach the efficient design through the cognitive or physical interactions. Process tolerance design is a key tool in the integrated design and manufacturing to reach a product with high quality and low cost. Since the optimal tolerance allocation involves several aspects of the design, manufacturing and quality issues, it is always a time consuming and difficult procedure, especially for complex products. Therefore, to overcome these difficulties, a computer-aided approach for optimal tolerance design of manufacturing process is needed in the design stage. In this paper, a novel interactive... 

New penalty functions, which have better convergence properties, as compared to the commonly used exterior and interior penalty functions, have been proposed in this paper. The convergence behavior and accuracy of ordinary penalty functions depend on the selection of appropriate penalty parameters. The optimization of ordinary penalty functions is accomplished after several rounds of optimization where, at each round a different but fixed value of penalty parameter is used. While some useful hints and rules for the selection of suitable penalty parameter values have been provided by different authors, the objective of this paper has been to improve this procedure by including the penalty... 

Simulation and prediction of gas turbine performance is a very important issue in design process or in actual behavior analysis. In these models physical behavior of components such as compressors, combustion chambers and turbines are simulated related to each other. The compressor is the most important part of simulation. This paper presents a model for simulating a compressor using stage stacking procedure with the aid of a genetic algorithm. The most important feature of the proposed method is that qualitative and quantitative rules based on turbo-machinery knowledge of compressors are used as constraints to the genetic algorithm to find the corrected situations of design. This knowledge... 

This study introduces a simple and efficient method to determine the peak floor acceleration (PFA) at different performance levels for three types of plane reinforced concrete (RC) structures: moment-resisting frames (MRFs), infilled–moment-resisting frames (I-MRFs), and wall-frame dual systems (WFDSs). By associating the structural maximum PFA response with the deformation response, the acceleration-sensitive nonstructural components, and the building contents, can be designed to adhere to the performance-based seismic design of the supporting structure. Thus, the proposed method can accompany displacement-based seismic design methods to design acceleration-sensitive nonstructural elements... 

The water-gas shift reaction occurs competitively to the main reaction of the Ir-catalysed methanol carbonylation process. To study the effect of seven factors including temperature, pressure, iridium, ruthenium, methyl iodide, methyl acetate and water concentrations on the formation of hydrogen and carbon dioxide as a result of the water-gas shift reaction and other side reactions in the carbonylation of methanol to acetic acid, the experimental design method combined with response surface methodology (RSM) was utilised. Central composite design at five levels (with α=1.63) was used to design experiments. A quadratic model that included the main and interaction effects of variables for H 2... 

Rehabilitation is the best approach for patients who suffer physical disability of their upper-limbs. Maintaining the intensity of exercise during treatment is the main factor that makes the robots suitable for rehabilitation since robots do not get tired and do the exercises with constant intensity under supervision of the doctor. Two main categories of rehabilitation robots are End-Effector based robots and wearable robots. According to the fact that most problems occur in need of rehabilitation for hand wrist area, in this paper a wearable rehabilitation robot has been developed for the wrist. Nowadays, wearable robots attract more attention than the other group. Wearable robots are... 

In the conceptual design phase of a turbocharger, where emphasis is mainly on parametric studies, before manufacturing and tests, a generalized and robust model that applies over a wide range properly, is unavoidable. 12The critical inputs such as turbine maps are not available during the conceptual design phase. Hence, generalized turbine models use alternate methods that work without any supplementary tests and can operate over wide ranges. One of the common and applicable modeling methods in design process is 'Dimensionless Modeling' using the constant coefficient scaling (CCS). This method can almost predict the turbine characteristics at the design point. However, at off-design... 

Most seismic design codes accept heavy damages to buildings in case of large earthquakes, provided that they are prevented against collapse. However, this leads to unacceptable consequences, such as very large volume of the required reconstruction works, in large populated cities. One way to get rid of these adverse consequences is using the idea of combining rocking/seesaw motion of the building's structure and energy dissipation at base level to create buildings easily repairable even after a large earthquake. In the present study, this idea has been employed for designing steel buildings with seesaw motion capability by using a central massive column at ground floor, with elastic behavior... 

In the conventional seismic design methods, heightwise distribution of equivalent seismic loads seems to be related implicitly on the elastic vibration modes. Therefore, the employment of such a load pattern does not guarantee the optimum use of materials in the nonlinear range of behavior. Here a method based on the concept of uniform distribution of deformation is implemented in optimization of the dynamic response of structures subjected to seismic excitation. In this approach, the structural properties are modified so that inefficient material is gradually shifted from strong to weak areas of a structure. It is shown that the seismic performance of such a structure is better than those... 

It is important to understand the flow characteristics and performance of wings for designers who want to have an efficient thrust in a land yacht. In this paper, a comparison of aerodynamic forces obtained by testing the land yacht model in a wind tunnel and by the Velocity Prediction Program (VPP) is presented. The wind tunnel testing of a land yacht is an effective design tool, but at present it is mainly used for VPP validation, which allows for a faster and more efficient design process. The rigid wing land yacht model, which is a radio controlled model, is tested in the national open jet wind tunnel of the Malek Ashtar University of Technology in Iran. The wing data, which is obtained... 

Interactive and integrated design and manufacturing can be a useful strategy for designers to reach the efficient design through the cognitive or physical interactions. Process tolerance design is a key tool in the integrated design and manufacturing to reach a product with high quality and low cost. Since the optimal tolerance allocation involves several aspects of the design, manufacturing and quality issues, it is always a time consuming and difficult procedure, especially for complex products. Therefore, to overcome these difficulties, a computer-aided approach for optimal tolerance design of manufacturing process is needed in the design stage. In this paper, a novel interactive... 

IP core reuse is popular for designing and implementing complex systems, because reuse of already provided blocks decreases design time and so diminishes productivity gap. Moreover, as system-level design methodologies and tools emerge for embedded system design, it is useful to have a shift from Register Transfer Level to system-level models for IP cores employed for implementation of hardware parts of the system. In this paper, we propose a C++ model for hardware IP cores that can be adopted as a standard for delivering IPs at a high level of abstraction, suitable for object-oriented system-level design methodologies. Next, we extend our system-level synthesizer in order to integrate IP...