Electrical and Electronics

This paper presents the comparison of hybrid multilevel inverters for different voltage and power applications. Hybrid multilevel inverters improve the number of the output voltage level based on a hybrid connection of power cells. Therefore, a given number of levels can be synthesized by several multilevel configurations, significantly increasing flexibility and complexity in the design of hybrid multilevel inverter. The purpose of the circuits presented here is to minimize the reverse voltage stress and the harmonic distortion of the voltage applied to the load. As a characteristic of the proposed cells, some of the switches operate at low frequency while others are switched at high frequency. Different topologies are discussed and reviewed in brief. Voltage sharing and low output-voltage distortion are achieved. This paper presents a survey of different topologies, control strategies and modulation techniques used by these inverters.

An available gas fired diffusion-absorption heat pump 150 liter (5ft) refrigerator has been modified by substituting the original heat input by transferring solar thermal energy from solar collector to the generator. At the beginning, a pipe with 90cm height, filled with hot water (97oC) is used as a generator heat input but the Ammonia vapor does not generate because the temperature is low to allow Ammonia-Water mixture to boil. Therefore the Water is replaced by high boiling point fluid (liquid paraffin wax), boiling point 310°C), and the generator with pipe with 30cm height and 5cm in diameter. Then Ammonia vapor generates at fluid temperature of 140oC up to 190oC where the pipe near the condenser becomes hot. This mean that the Ammonia vapor generate up to the condenser. The flow rate required to supply heat input to generator, the solar collector receiver area and the volume of hot fluid storage required to operate the refrigerator for 24 hours has been calculated.

The proposed system presents power-control strategies of a grid-connected hybrid generation system with versatile power transfer. This hybrid system allows maximum utilization of freely available renewable energy sources like wind and photovoltaic energies. For this, an adaptive MPPT algorithm along with standard perturbs and observes method will be used for the system. Also, this configuration allows the two sources to supply the load separately or simultaneously depending on the availability of the energy sources. The turbine rotor speed is the main determinant of mechanical output from DG energy and Solar cell operating voltage in the case of output power from solar energy.The inverter converts the DC output from non-conventional energy into useful AC power for the connected load. In order to utilization distributed generation (DG) unit interfacing converters to actively compensate harmonics, this paper proposes an enhanced current control approach, which seamlessly integrates system harmonic mitigation capabilities with the primary DG power generation function. As the proposed current controller has two well- decoupled control branches to independently control fundamental and harmonic DG currents, local nonlinear load harmonic current detection and distribution system harmonic voltage detection are not necessary for the proposed harmonic compensation method. Moreover, a closed-loop power control scheme is employed to directly derive the fundamental current reference without using any phase-locked loops (PLL). The proposed power control scheme effectively eliminates the impacts of steady-state fundamental current tracking errors in the DG units. Thus, an accurate power control is realized even when the harmonic compensation functions are activated hybrid system operates under normal conditions which include normal room temperature in the case of solar. The simulation results are presented to illustrate the operating principle, feasibility and reliability of this proposed system.

Relevant background material about speech recognition is presented, along with a critical review of previous hardware implementations. Accurate real-time speech recognition is not currently possible in the mobile embedded space where the need for natural voice interfaces is clearly important. The continuous nature of speech recognition coupled with an inherently large working set creates significant cache interference with other processes. Hence, real-time recognition is problematic even on high-performance general-purpose platforms. This paper provides a detailed analysis of CMU's latest speech recognizer (Sphinx 3.2.). Several optimizations are then described which expose parallelism and drastically reduce the bandwidth and power requirements for real-time recognition. A special-purpose accelerator for the dominant Gaussian probability phase is developed for a 0:25_ CMOS process which is then analyzed and compared with Sphinx's measured energy and performance on a 0:13_ 2.4 GHz Pentium 4 system. The results show an improvement in power consumption by a factor of 29 at equivalent processing throughput. However after normalizing the process, the special-purpose approach has twice the throughput, and consumes 104 times less energy than the general-purpose processor. The energy-delay product is a better comparison metric due to the inherent design trade-offs between energy consumption and performance. The energy-delay product of the special-purpose approach is 196 times better than the Pentium 4. These results provide strong evidence that real-time large vocabulary speech recognition can be done within a power budget commensurate with embedded processing using today's technology.

The main contributions of the present work include the design of a computer-aided detection (CAD) system for the segmentation and classification of breast cancer. A comparison of segmentation and classification methods of both masses and micro-calcifications, tapping of a new entropy function called Hanmandlu and Anirban entropy function. The new entropy function outperforms over the Shannon’s entropy and drastically improved the classification accuracy by 5%. Next is development of a modified rough set quick reduct algorithm for the reduction of dimensionality in the feature selection prior to the classification. On the average the reader’s sensitivity can be increased by 10% with the assistance of our CAD system. Our finding indicated the potential of CAD to reduce the false negative rates by 50-75%. The average execution time is 5 seconds per image.

This paper presents an advanced step to the concept of car black-box in developing a comprehensive vehicle safety system which would not only record the video and audio, but also try to prevent a possible collision by limiting the speed of the vehicle in accident-prone areas. In case of an accident, the time and location (co-ordinates) is sent through GSM to a preset number for immediate rescue and treatment of accident, also recorded data can be used for forensics which would reveal law enforcement authority about the failure that caused accident, and give manufacturer an idea for improvement. So the motto is to develop an embedded integrated system consisting of microcontroller, power supply unit, sensors, memory, motor driver unit and GPS/GSM modem.

MIMO technology plays a vital role in wireless communication which uses multiple antennas at both transmitter and receiver side. As the demand of data rate is increasing day by day, there is a need of high throughput, wide coverage, capacity and improved reliability. Integration of OFDM with MIMO holds the potential to drastically increase the data rate in future wireless communication system without increasing the transmit power and bandwidth. In this paper we mainly focus on the advantage of using MIMO-OFDM system and the drawback of using SISO, SIMO, MISO systems which have been verified using simulation. Performance of the systems is measured with respect to BER, capacity and finally the data rate is determined. The simulation results are obtained using MATLAB/SIMULINK software.

Image compression is a widely addressed researched area. Image compression is a key technology in transmission and storage of digital images because of vast data associated with them. Various types of compression methods are present in place. The performance analysis of various schemes to compress a True image in graphical user interface is discussed in this paper. True images can be compressed with the help of same scheme as grayscale images by applying them to each of the three color components. Experimental results demonstrate that the STW wavelet algorithm is more efficient for PSNR while EZW method provides the better compression ratio.

This report emphasises the economic impact of four optional approaches to dealing with the Copyright Act as it relates to the issue of copyright viability and liability for Internet service providers (ISPs). The report commences by signifying the options under consideration and the important stakeholders, and then proceeds to profile the Nigeria ISP industry. The ISP industry is designated to serve consumer and business subscribers, to make provisions of broad access to both dial-up and broadband Internet access services at prices that will be classify among the lowest in the world. This report is to make provision for ecomomic analysis for propose amendments to copyright legislative in Nigeria. It is also to concentrate on the impact of these proposed reforms on the ISP industries in Nigeria, the effect on the stakeholder (e.g consumers, content producers). The problems facing content producing industries as a result of the Internet and piracy are briefly discussed, with the primary threat being the free digital distribution of copyright contents over the Internet through peer-to-peer (P2P) networks and illegal duplication of copy right contents. The number of digitally encoded music files (MP3/MP4) distributed has no definite estimation on yearly basis because there is no extent that piracy and downloads cannibalize sales do not go to. It is likely that the net effect of digital music downloads on CD sales is negative. The economic impact of each of the proposed copyright reform options is emphasised. The options as follows; the standing quo on significat economic cost to effect of law on outdated and complexity of internet services. Also on benefit clarification of legal matters and subjects ISPs to explicits condition on exemption from copyright liability. Practice of “Notice and Takedown” and “Notice and Notice” adoption to guide ISPs to work with content providers after recieving “Notice” of copyright infringement. Levying a mandatory licensing “tariff on ISPs, base on the magnitude of the tariff and its implimentation. It is recommended that the copyright be reformed to give explicit boundry on ISP copyright dependence for transmission, linking, production and detecting of copyrightd content by employing Notice and Notice or Notice and Takedown method.

This paper describes three phase bi-directional battery charger widely used in Energy storage application. The full bridge scheme is widely used for the high power application. The high-frequency transformer is used for the isolation purpose. This paper describes the design and simulation of a 7.75-kW, full-bridge, bi-directional isolated dc-dc converter with active front-end converter (AFC). The AFC is connected with the 3-phase ac system, which provides 650 to 700 dc voltage to dc-dc converter with lower value of THD (according to IEEE- 915) and improve power factor at input side. The dc-dc converter converts 310V from 650V for charging the battery. Software tool PSIM is used to obtain the simulation result of the converter. The closed loop system is simulated to achieved voltage and current ripple at output side less than 1% rms of rated voltage.