Engineering Seminar Topics and Seminar Topics

Download Full Article  Free Space Optics

        Communication, as it has always been relied and simply depended upon speed. The faster the means !  the more popular, the more effective the communication is !

        Presently in the twenty-first centaury wireless networking is gaining because of speed and ease of deployment and relatively high network robustness. Modern era of optical communication originated with the invention of LASER in 1958 and fabrication of low-loss optical fiber in 1970.

        When we hear of optical communications we all think of optical fibers, what I have for u today is AN OPTICAL COMMUNICATION SYSTEM WITHOUT FIBERS or in other words WIRE FREE OPTICS.

        Free space optics or FSO –Although it only recently and rather suddenly sprang in to public awareness, free space optics is not a new idea. It has roots that 90 back over 30 years-to the era before fiber optic cable became  the preferred transport medium for high speed communication. FSO technology has been revived to offer high band width last mile connectivity for today’s converged network requirements.

FSO ! FREE SPACE OPTICS

        Free space optics or FSO, free space photonics or optical wireless, refers to the transmission of modulated visible or infrared beams  through the atmosphere to obtain optical communication. FSO systems can function over distances of several kilometers.

        FSO is a line-of-sight technology, which enables optical transmission up to 2.5 Gbps of data, voice and video communications,  allowing optical connectivity without deploying fiber optic cable or  securing spectrum licenses. Free space optics require light, which can be  focused by using either light emitting diodes (LED) or LASERS(light  amplification by stimulated emission of radiation). The use of lasers is a simple concept similar to optical transmissions using fiber-optic cables, the only difference being the medium.                                           

        As long as there is a clear line of sight between the source and the destination and enough transmitter power, communication is possible virtually at the speed of light. Because light travels through air faster than it  does through glass, so it is fair to classify FSO as optical communications at the speed of light. FSO works on the same basic principle as infrared television remote controls, wireless keyboards or wireless palm devices.

 Download Full Article  Free Space Optics

Download Full Article Integrated Power Electronics Module

IPEM is an improved power processing technology through advanced integration of power electronics components. It provides high frequency synthesis, resulting in important improvements in performance, size, and cost.

Currently, assemblies of power semiconductor switches and their associated drive circuitry are available in modules. Though the module contains a small size power switching part, the associated control, sensing, electro magnetic power passives and inter connect structures are very bulky. In IPEM, the reduction in size and weight is provided by planar metalization that allows 3-D integration of power devices and power passives to increase the power density.

This paper addresses the improvements of power processing technology through advanced integration of power electronics. The fundamental functions in electronic power processing, the materials, processes, and integration approaches and future concepts are explained.

INTRODUCTION

In power electronics, solid-state electronics is used for the control and conversion of electric power .The goal of power electronics is to realize power conversion from electrical source to an electrical load in a highly efficient, highly reliable and cost effective way. Power electronics modules are key units in a power electronics system. These modules contain integration of power switches and associated electronic circuitry for drive control and protection and other passive components.

During the past decades, power devices underwent generation-by-generation improvements and can now handle significant power density. On the other hand power electronics packaging has not kept pace with the development of semiconductor devices. This is due to the limitations of power electronics circuits. The integration of power electronics circuit is quite different from that of other electronics circuits. The objective of power electronics circuits is electronics energy processing and hence require high power handling capability and proper thermal management.

Most of the currently used power electronic modules are made by using wire-bonding technology [1,2]. In these packages power semi conductor dies are mounted on a common substrate and interconnected with wire bonds. Other associated electronic circuitries are mounted on a multi layer PCB and connected to the power devices by vertical pins. These wire bonds are prone to resistance, parasitic and fatigue failure. Due to its two dimensional structure the package has large size. Another disadvantage is the ringing produced by parasitic associated with the wire bonds.

To improve the performance and reliability of power electronics packages, wire bonds must be replaced. The researches in power electronic packaging have resulted in the development of an advanced packaging technique that can replace wire bonds. This new generation package is termed as ‘Integrated Power Electronics Module’ (IPEM) [1].  In this, planar metallization is used instead of conventional wire bonds. It uses a three-dimensional integration technique that can provide low profile high-density systems. It offers high frequency operation and improved performance. It also reduces the size, weight and cost of the power modules.

 Download Full Article Integrated Power Electronics Module

Download Full Article Voice Morphing

        Voice morphing means the transition of one speech signal into another. The new morphed signal will have the same information content as the two input speech signals but a different pitch, which is determined by the morphing algorithm. To do this, each signal’s information has to be converted into another representation, which enables the pitch and spectral envelope to be encoded on orthogonal axes. Individual components of the speech signal are then matched and the signal’s amplitudes are then interpolated to produce a new speech signal. This new signal’s representation then has to be converted back to an acoustic waveform. This project vividly describes the representations of the signals required to affect the morph and also the techniques required to match the signal components, interpolate the amplitudes and invert the new signal’s representation back to an acoustic waveform.

Introduction

        Voice morphing means the transition of one speech signal into another. Like image morphing, speech morphing aims to preserve the shared characteristics of the starting and final signals, while generating a smooth transition between them. Speech morphing is analogous to image morphing. In image morphing the in-between images all show one face smoothly changing its shape and texture until it turns into the target face. It is this feature that a speech morph should possess. One speech signal should smoothly change into another, keeping the shared characteristics of the starting and ending signals but smoothly changing the other properties. The major properties of concern as far as a speech signal is concerned are its pitch and envelope information. These two reside in a convolved form in a speech signal. Hence some efficient method for extracting each of these is necessary. We have adopted an uncomplicated approach namely cepstral analysis to do the same. Pitch and formant information in each signal is extracted using the cepstral approach. Necessary processing to obtain the morphed speech signal include methods like Cross fading of envelope information, Dynamic Time Warping to match the major signal features (pitch) and Signal Re-estimation to convert the morphed speech signal back into the acoustic waveform.

 Download Full Article Voice Morphing