Sharif Digital Repository

A new method for the robust estimation of target orientation using measured radar cross section is proposed. The method is based on a Generalized Regression Neural Network (GRNN) scheme. The network is trained by the FFT modulus of bistatic radar cross section data sampled at the receiver positions. The target value to be trained is the angle between a defined target orientation and the incident wave. Results based on actual measurements are presented  

We present a new method for the robust estimation of a two-dimensional conducting target orientation using measured radar cross-section data. The method is based on a Generalized Regression Neural Network (GRNN) scheme, which belongs to the family of radial basis neural networks  

We have constructed the Koch array factor using decomposition of the array factor and solving it with matrix methods, rather than regular inverse Fourier transform method. With the aid of non-uniform sampling we have made some improvements in the main beam while the array elements are reduced significantly. We have also consider the Fibonnaci Sierpinski gasket  

The orientation of a conducting target was estimated with a generalized regression neural network (GRNN) network using back-scattered data. Steps made to provide the training data sets by a computer code using method of moments were investigated. Noisy data sets were provided to improve the system generalization. The GRNN target orientation estimation and its performance was evaluated and the robustness was verified against target scaling, target deformation, sensor misplacements and introduction of noise with different S/N into sensor measurements  

This book present the lecture notes used in two courses that the late Professor Kasra Barkeshli had offered at Sharif University of Technology, namely, . The prerequisite for the sequence is vector calculus and electromagnetic fields and waves. Some familiarity with Green's functions and integral equations is desirable but not necessary.
The book provides a brief but concise introduction to classical topics in the field. It is divided into three parts including annexes. Part I covers principle of electromagnetic theory. The discussion starts with a review of the Maxwell's equations in differential and integral forms and basic boundary conditions. The solution of inhomogeneous wave... 

The bandwidth of the E-shaped microstrip antenna is optimized using the genetic algorithm (GA) based on fuzzy decision-making, The method of moments is employed for the analysis of the microstrip antenna at the frequency band of 1.8GHz to 2.6GHz by the optimization parameters of supply locations and slot dimensions. Fuzzy inference system is used for the control of the parameters of the genetic algorithm. In the implemented fuzzy system, inputs are parameters like population, and outputs are parameters such as crossover and mutation rates. Simulation results show the genetic algorithm to optimize the bandwidth of the E-shaped microstrip patch by 33.3%. The measured results of the optimized... 

In this paper a novel form of the familiar E-shaped patch antenna is presented. In the presented approach, by using the genetic algorithm (GA) based on fuzzy decision-making, some modifications have been implemented to the incorporated slots which lead to even more enhancement in the antenna bandwidth. The MOM (Method of Moment) is employed for analysis at the frequency band of 1.8GHz-2.6GHz by the optimization parameters of supply locations and slot dimensions. In the implemented fuzzy system, inputs are parameters like population, and outputs are parameters like recombination to produce the next generation. Fuzzy inference system (FIS) is used for the control of GA parameters. The design... 

An efficient hybrid method for the analysis of the interference phenomenon in high frequency communication circuits is presented. This method is based on the Transmission Line Matrix (TLM) method augmented with a time-domain integral equation formulation to account for the radiation of equivalent sources on boundary surfaces. As such, wide band effects are easily and accurately modeled since its formulation is in the time domain  

In this paper an optimized E-shaped patch antenna is presented, the bandwidth of the E-shaped microstrip antenna is optimized using the genetic algorithm (GA) based on fuzzy decision-making. In the implemented fuzzy system, inputs are parameters like population, and outputs are parameters such as recombination to produce the next generation. Fuzzy inference system is used for the control of the parameters of the genetic algorithm. Simulation results show the high ability of genetic optimization based on fuzzy system for about 33% BW. Dimensions of the slots have been optimized with the novel design approach presented herein. A prototype element is also constructed in order to validate the... 

Electromagnetic scattering from thin resistive strips is formulated using an integral equation approach. Analytical expressions for the electric current density over wide and narrow strips are derived based on the physical optics and quasistatic approximation of the pertinent integral equations, respectively. The solutions are used to find closed form expressions for the echo width of the strip  

Electromagnetic scattering from thin resistive strips is formulated using an integral equation approach. The formulation is then specialized to strips of constant curvature and arbitrary size allowing the employment of the method of moments to solve the scattering problem  

A new method for the far field pattern synthesis of parabolic reflector antennas that can virtually optimize all major design parameters simultaneously is presented. This method optimizes the gain and the cross-polarization of the radiation pattern of the reflector antenna. It also satisfies the FCC standard limits on the sidelobe level envelope  

A new method for the shape reconstruction of conducting cylinders from the measured data based on the cubic uniform B-splines was discussed. B-Spline was defined by an ordered set of control points which determined the shape of the curve. A direct problem was formulated using standard integral equations that were solved using method of moments. Principal polarization were treated separately. The method was found less sensitive to noise than those using Fourier expansions  

Al-Zn-Mg-Cu alloys (7xxx series Al alloys) are extensively used for their superior mechanical and corrosion performance. These properties are microstructure-sensitive and highly dependent on the formation, growth and coarsening of precipitates. To date, a wide variety of ageing procedures have been developed to tailor the evolved microstructures so as to yield a good combination of mechanical capacity and corrosion resistance of 7xxx series Al alloys. Among these methods, isothermal ageing, multi-stage ageing, non-isothermal ageing, retrogression and re-ageing (RRA), and stress ageing (i.e. creep ageing) are the most significant. In the present review, all of these approaches are... 

After an earthquake, the residual stiffness and strength of structural elements are typically estimated based on a qualitative visual inspection of cracks that is prone to error. In this paper a new approach is proposed to automatically estimate the updated stiffness and strength of damaged unreinforced masonry walls by characterization of crack patterns by a mathematical index. It is shown that structural and textural fractal dimensions of a crack pattern reflect the extent of cracking and the type of cracking or crushing, i.e., whether the cracks pass through joints or whether bricks have been damaged and crushed. Using results of six quasi-static cyclic tests on unreinforced brick masonry... 

In order to optimize the aging treatment of Mg-1.8Zn-0.7Si-0.4Ca alloy, different times and temperatures of solid solution and age hardening were applied to the alloy specimens. Microstructures and mechanical properties of the specimens were investigated using the optical microscopy, field emission scanning electron microscopy equipped with an energy dispersive x-ray spectrometer, x-ray diffraction, hardness, and shear punch tests. The lowest hardness and strength were achieved by solution treating of the alloy at 500 °C for 8 h, presenting the optimal condition for solution treatment of the alloy. The microstructural examinations revealed three different precipitates consisting of CaMgSi,... 

The concept of a nonlinear transfer function of a fibre-optic communication link is reviewed. Also an approximation of the nonlinear transfer function is introduced, which allows to define an equivalent single-span model of a dispersion-managed multi-span system. In this paper we will show its limits of validity and try to extent these limits by enhancing the theoretical model. In this respect we will discuss the impact of dispersion precompensation and show the influence of residual dispersion per span, number of spans and local dispersion on transmission systems with on-off keying and differential phase-shift keying modulation formats. This approach allows fast assessment of the... 

Hydrogen technology through water electrolyzer systems has attracted a great attention to overcome the energy crisis. So, rationally designed non-noble metal based-electrocatalysts with high activity and durability can lead to high performance water electrolyzer systems and high purity hydrogen generation. Herein, a facile two-step method: hydrothermal and electrodeposition, respectively, are developed to decorate highly porous three-dimensional binder-free structure NiFeO/NiO nanosheets array on Ni foam (NiFeO/NiO/NF) with robust adhesion as a high-performance electrode for Hydrogen Evolution Reaction (HER). The electrodeposition process applied after the initial hydrothermal process... 

New techniques for Class-AB Operational Transconductance Amplifiers (OTAs) are presented. These new techniques are two topologies based on current boosting in class-AB stage which achieve considerable improvement of Slew Rate and Gain-Bandwidth while maintaining the same power consumption as the conventional design. Circuit level analysis and simulation results of proposed circuits in 0.18μm CMOS technology for gain, GBW, slew rate, and settling time are presented to prove the effectiveness of the proposed design method  

In this paper, first we shall define a list of technology transfer barriers in the biotechnology field through interviews and literature reviews. Next, we shall categorize them into four major categories of technology, and at last introduce all of the hypotheses on the existence of relationship between each part of technology and failure in the technology transfer process. Questionnaires consisting of two parts were created and handed out to all of the specialists and biotechnology idea-holders in the Iranian National Research center of Biotechnology, Lidco Co, Iran Pastor Institute, Biotechnology Department of University of Tehran, etc. Going on, we've evaluated the factors' validity...