Characteristics of a longitudinal/transverse coupling slot incrossed rectangular waveguides

A rigorous analysis of a broad-wall slot coupler between two crossed rectangular waveguides is presented. The slot is longitudinal and offset from the center line in the main guide and is centered transverse in the branch guide. Integral equations are developed, taking into account finite wall thickness. The integral equations are then solved for the aperture electric field. Coupling slot characteristics are obtained, including the resonant length and dominant mode scattering. Numerical results for resonant length and scattering parameters are presented over a range of offsets, waveguide dimensions, and frequencies     

Investigation on Different Crystal Grains from the Multi-crystalline Silicon (mc-Si) Wafer

Silicon - We have studied the mc-Si wafers with different (hkl) planes. Initially, the wafer was chemically etched by the KOH (20wt%) and IPA (2%) in the Millipore water at 60 °C for...     

A real-time hardware fault detector using an artificial neuralnetwork for distance protection

A real-time fault detector for the distance protection application, based on artificial neural networks, is described. Previous researchers in this field report use of complex filters and artificial neural networks with large structure or long training times. An optimum neural network structure with a short training time is presented. Hardware implementation of the neural network is addressed with a view to improve the performance in terms of speed of operation. By having a smaller network structure the hardware complexity of implementation reduces considerably. Two preprocessors are described for the distance protection application which enhance the training performance of the artificial neural network many fold. The preprocessors also enable real-time functioning of the artificial neural network for the distance protection application. Design of an object oriented software simulator, which was developed to identify the hardware complexity of implementation, and the results of the analysis are discussed. The hardware implementation aspects of the preprocessors and of the neural network are briefly discussed     

在双镶嵌铜互联中O.13微米器件生成用的基于PVD和ALD阻挡层的先进技术

1. Introduction The requirement of minimal bottom coverageand thick sidewall coverage for PVD-based films forlow via resistance and improved stress migration isnot easy to achieve with traditional depositionmethods. Modern I-PVD techniques give high bot-tom coverage, due to the ionized component of thedeposition flux. Sidewall coverage tends to be low,which is mainly due to off-normal deposition fluxand a less than unity sticking coefficient.     

Influence of Process Parameters on Cu–Fly Ash Composite by Powder Metallurgy Technique

In this study influence of compaction pressure, sintering temperature, and sintering time on mechanical and wear behavior of the fly ash reinforced copper-based composites are analyzed. The composites were prepared by powder metallurgy (P/M) technique with copper as matrix, 5 and 10 wt% of fly ash as reinforcement. The green compacts were prepared at three different pressures such as 350, 400, and 450 MPa. The prepared green composites were sintered at 700, 800, and 900 °C for the time period of 30, 60, and 90 min, respectively. From the results it is observed that when the process parameter increases the density, hardness, compression strength, and wear resistance increases.     

Synthesis,bioactivity and preliminary biocompatibility studies of glasses in the system CaO–MgO–SiO<Subscript>2</Subscript>–Na<Subscript>2</Subscript>O–P<Subscript>2</Subscript>O<Subscript>5</Subscript>–CaF<Subscript>2</Subscript>

New compositions of bioactive glasses are proposed in the CaO–MgO–SiO₂–Na₂O–P₂O₅–CaF₂ system. Mineralization tests with immersion of the investigated glasses in simulated body fluid (SBF) at 37°C showed that the glasses favour the surface formation of hydroxyapatite (HA) from the early stages of the experiments. In the case of daily renewable SBF, monetite (CaHPO₄) formation competed with the formation of HA. The influence of structural features of the glasses on their mineralization (bioactivity) performance is discussed. Preliminary in vitro experiments with osteoblasts’ cell-cultures showed that the glasses are biocompatible and there is no evidence of toxicity. Sintering and devitrification studies of glass powder compacts were also performed. Glass-ceramics with attractive properties were obtained after heat treatment of the glasses at relatively low temperatures (up to 850°C).     

Compact analytical model for single gate AlInSb/InSb high electron mobility transistors

We have developed a 2D analytical model for the single gate Al In Sb/In Sb HEMT device by solving the Poisson equation using the parabolic approximation method.The developed model analyses the device performance by calculating the parameters such as surface potential,electric field distribution and drain current.The high mobility of the Al In Sb/In Sb quantum makes this HEMT ideal for high frequency,high power applications.The working of the single gate Al In Sb/In Sb HEMT device is studied by considering the variation of gate source voltage,drain source voltage,and channel length under the gate region and temperature.The carrier transport efficiency is improved by uniform electric field along the channel and the peak values near the source and drain regions.The results from the analytical model are compared with that of numerical simulations(TCAD) and a good agreement between them is achieved.     

Resonance frequency of elliptical microstrip antennas

A simple and accurate technique is presented for obtaining the resonance frequency of the dominant odd and even modes of elliptical microstrip antennas and resonators. This method is validated by experiment. A previously published method is found to be inaccurate.<>     

Asymptotic approximations in radome analysis

A detailed analysis is presented of assumptions and limitations of physical optics and stationary phase techniques for radome analysis. A two-dimensional ogival structure with an electric or magnetic line source inside is investigated. A method-of-moments analysis using J.H. Richmond's (1965) polarization current technique is performed to obtain reference results. Physical optics, uniform geometrical theory of diffraction, and stationary phase techniques of order 1 and 2 are analyzed     

Application of genetic algorithms and simulated annealing techniquein optimising the aperture distributions of antenna array patterns

Simulated annealing and genetic algorithms are used for finding optimum excitations for patterns with null-filling. These methods have the advantage that the optimum aperture distribution with a minimal variation between excitations of adjacent elements is found without searching the entire solution space. A comparison between the performance of both methods shows that genetic algorithms are faster than simulated annealing, for this problem