DANESHVAR MEDICINE
Year:2002 | Volume:9 | Issue:37|Papers Count:9

Nowadays planar structures which include array of conductor strips or periodic windows have been taken into consideration for the reason of their application in macrowave industry. These structures that have been known as frequency selective surfaces, having a duty as RF circuits frequency filters against the waves and upon the kind of applied element, show the specific spectrum behaviour. In this paper, first of all periodic structures and their applications are presented and then general analysis method apart from the form of structures are presented in order to bring out reflexion coefficient and transmit them when they are radiated by a plate wave and at the end some FSS structures and their results are presented by the analysis method.    

This paper presents a new method for implementation of CMOS digital Fuzzy Logic Controller (FLC), which adds many analog design advantages such as low die area, high speed, and simplicity to the digital system. It also provides using more accurate methods such as product-sum for inference, center of area for defuzzifying and exploiting parallel strategy in digital FLC with no digital complexity and unchanged digital properties. For implementing this idea, a programmable fuzzifier circuit has been designed based on a new strategy for a five-bit digital input signal and membership degree as an analog current with five-bit resolution in the range of 58uA. Membership functions which are generated by this membership function generator are trapezoidal and triangular capable of changing their ascending and descending slops arbitrarily, by controlling input digital parameters. The inputs and single output of all system is digital while the interior blocks are mainly current-mode circuits. It has also been presented a new high-accurate simple current-mode circuit for Min-Max block. The systematical MATLAB simulations of the controller model and HSPICE circuit simulation in 0.35um CMOS standard process for a two-input one-singleton-output fuzzy controller with nine-rules have been presented. At last, the obtained characters are compared with the last previous works.      

A new method for crystallization of silicon at low temperatures is reported which is suitable for realization of thin film transistors on glass substrates. In this technique the Crystallization initiates into the localized seeds of nickel-silicide and progresses towards the area under the gate of the transistors. The lateral growth is enhanced in the presence of ultra-violet illumination during annealing and allowing growth at reduced temperatures. The Crystallinity of the samples has been verified by using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and optical microscopy- Transistor fabrication has been achieved in ordinmy glass substrates at temperatures below 400°C. A hole mobility of 50cm2/Vs has been extracted from the electrical characteristics and further confirming the Crystallinity of the layer,      

Interpolation and especially thin plate spline is a popularly and widely used algorithm for warping and registration of medical images. This interpolation function is established based on certain relationship between two sets of landmark points in source and destination planes. Sensitivity analysis of mapping function to source and/or target points has not been carefully analyzed before. In this article, sensitivity analysis using analytical approach is performed on source and destination deviation. The method is applied to synthetic data, real and simulated Magnetic Resonance (MR) images. Our results demonstrate that sensitivity is highly related to landmark distribution in the source and target plane and the type of radial basis function (RBF) of the geometrical mapping. Particularly, we have shown that sensitivity is very high near landmarks that are close together and sensitivity approaches to zero near precisely extracted landmark.      

The distinguishing of defective elements in planar phased array antennas and compensation of undesired effects on radiation pattern is very important. Specially in real time of the connection applications, after determination of the relative phase and amplitude of neighboring elements with the aid of six ports passive microwave circuits and compare them with ideal Gaye, defective elements will be distinguished. The making changes in phase and amplitude of the sound neighboring elements, difference between ideal and defective radiation patterns will be decreased and effect of failed elements will be compensated.    

Detection networks have received attention recently, but most researches have been focused on cases where each local sensor makes a binary secision based on its own observation and then trasmits the decision to the fussion center. The restriction of the sensor outputs to one investigates optimal decision rules in a multi-bit decision network. A multi-bit decision is equivalent to multi-level quantization of the Likelihood Ratio. In this paper, we develop an iterative algorithm to determine the quantization levels in each independent local sensor. We demonstrate the feasibility of the proposed approach through the application to a radar detection problem which is CFAR detection of Rayleigh fluctuating in Gaussian noise. Simulation results are presented to show how the additional bits from local sensors could result in a better detection performance.

A large class of nonlinear dynamical systems can be presented by polynomial nonlinear systems. Necessary conditions for optimal control of nonlinear systems are reduced to solve nonlinear differential equations with boundary conditions which their solutions in general can not be analytically obtained. Numerical solutions and spectral methods have been used in order to solve these systems. In this paper a numerical method is presented by using spectral hybrid functions for solving polynominal nonlinear, systems A numerical example is included to demonstrate the validity and applicability of the method and a comparison is made by existing results.        

A Radiation of wire antennas has been of considerable concern. The equations which describe the behavior of the wire antennas are given by Pocklington and Hallen integral equations. These equations are in from of the first kind Fredholm integral equations with singular kernel. In this paper, we use the Haar wavelet for solving Hallen integral equations. The method is based on constructing the Haar wavelet to approximate the required solution for the wire antennas. The integral expressions that arise in the Hallen equations are converted into some algebric equations, thus greatly simplify the problem. The method yields to accurate results. As compared to the classical techniques, our method is simple and consumes less computer time. Numerical examples are included to demonstrate the validity and applicability of the method and a comparison is made by the classical method of moments.