Application of natural commutation technique to an improved cycloconverter type high-frequency link inverter with center-tapped transformer

This thesis presents a new isolated cycloconverter type high frequency (HF) link dc to ac power converter (inverter) that consists of three arms of bidirectional switches at transformer secondary. This topology has the advantage of light weight and reduced switch count, compared to other types of HF link inverter. However, like all HF link inverter topologies, this topology also suffer high voltage surge problem and power device switching loss. In order to overcome these problems, two sets of switching technique, namely the asymmetric bipolar PWM control and edgealigned unipolar PWM control, are introduced. These switching techniques utilize natural commutation technique that enables total soft switching operation and voltage surge reduction. Furthermore, the proposed switching techniques are able to reduce the transistor conduction loss due to the existence of freewheeling period. The research work verifies of the proposed topology and switching techniques by means of SPICE simulations. It also describes the natural commutation mechanism for HF link inverter in detail. An open loop laboratory prototype based on the Infineon C167 fixed-point microcontroller was constructed. The results obtained from the experimental rig were found to be in very close agreement with the theoretical prediction and simulation. The laboratory prototype was able to supply output voltage 340Vrms as well as 120Vrms, with THD less than 2.5%. The total power conversion efficiency reaches 86% when the output power was beyond 300

Z-Score Model in Predicting Corporate Financial Distress of PETONE

At the night on 15 January 2013, when the ticking clock on the office wall had sounded eight times, Arifin, the financial advisor of Petrol One Resources Berhad (PETONE) realised that it was 8 p.m. then. Arifin was still in his office cracking his head thinking of a method that he could use to examine the financial health of PETONE.This was the task assigned to him after meeting with PETONE’s chairman, Azmin, at 5.30 pm.During the meeting which lasted for half an hour, Arifin was assigned a task which he had to present the findings the following Tuesday on 22 January 2013 regarding the financial health of PETONE to identify (i) the first warning sign indicating that the company was getting into financial trouble, and (ii) the major causes that had led the company into distressed financial situation. This assignment was in response to the announcement made on 30 August 2012 to classify PETONE as a Practice Note 17 (PN17) company when PETONE had triggered one of the prescribed criteria under the main market listing requirements of Bursa Malaysia Securities Berhad (Bursa Securities).After thinking hard for two hours, finally he had decided to apply z-score model to analyse the financial health of PETONE. As such he could leave office now and the next day when he came in to work, he could start going through the financial reports of PETONE to collect the required data for the z-score model he intended to use to assess the financial health of PETONE

Demographic Characteristics, Need For Achievement And Entrepreneurial Attitude Among Women Entrepreneurs And Women Managers In Malaysia

The present study investigated the demographic characteristics need for achievement and entrepreneurial attitude among women entrepreneurs and women managers in Malaysia. Specifically, it aimed to provide answers to the following research questions: (1) Will women entrepreneurs differ from women managers demographic characteristics, need for achievement and entrepreneurial attitude? (2) Will the demographic characteristics significantly explain the variance in need for achievement and entrepreneurial attitude? (3) What demographic characteristics will best predict need for achievement and entrepreneurial attitude among women entrepreneurs and women managers under study?To answer the research questions, a descriptie quantitative study was conducted. The units of analysis women entrepreneurs and women managers in Malaysia. Forty five (45) women entrepreneurs and 45 women managers were included in the study through snowballing or "referred participants" due to the absence of a systematic listing of women entrepreneurs and women managers. Questionnaires were distributed to target respondents either personally or by mail. The response rate was 31.3%. The instrument used consisted of three parts: the Demographic Survey to gather personal information, the Rosen Scale and the Entrepreneurial Attitude Scale developed by Nieves (198.5) to measure need for achievement and entrepreneurial attitude among women entrepreneurs and women managers respectively. The last two yielded reliability coefficiently of 0.89 and 0.85 respectively. data were analyzed using the T-test to test differences; Multiple Regression Analysis to determine the relationships between demographic characteristics, on the one hand, and for achievement and entrepreneurial attitude on the other hand; and Stepwise Regression Analysis (Best Fit Model) to determine the demographic characteristics that best predict need for achievement and entrepreneurial attitude. The 0.05 level of significance was used as critical level for decision-making regarding the hypotheses. The major findings of the study are as follows: (1) Women entrepreneurs did not differ significantly form women managers in demographic characteristics (except for age, marital status, level of education and family size), need for achievement and entrepreneurial attitude. (2) The thirteen demographic characteristics did not significantly explain the variance in need for achievement and entrepreneurial attitude. Demographic characteristics explained only 15.00% in the variance for need for achievement and only 13.82% in the variance for entrepreneurial attitude. (3) The best fit model showed that the demographic characteristics which are good predictors of need for achievement are: (i) age, (ii) aggregate annual family income (iii) family size (iv) relationship with the father (v) realtionship with the mother, and (vi) frequency of rewards received from parents. Meanwhile, the entrepreneurial attitude, the good predictors are (i) family size, (ii)level of education of the father, (iii) relationship with the mother, and (iv) place of residence during childhood. (4)The best predictor for need for achievement is socio-economic status measured by aggregate annual family income while the best predictor for entrepreneurial attitude is level of education of the father. Based on the findings, recommendations for further studies, policies formulation and programs/ trainings towards entrepreneurship development are forwarded

The delay of stock price adjustment to information: A country-level analysis

This study measures the speed with which the aggregate stock market in 49 countries responds to global market-wide public information. Our empirical results show that there are wide variations in the aggregate price delay values over time and across countries. Subsequent panel analysis confirms previous firm-level evidence that market size, trading volume, short sales restrictions and the degree of investability are significant determinants of price delay even at the country level.Informational efficiency, speed of adjustment, price delay, aggregate stock market

A preliminary study on the relationship between psycho graphic factors and the purchase of life insurance

This was a preliminary study conducted to examine the relationship between psycho graphic factors (i.e., personal value, risk attitude, and trust) and the purchase of life insurance among Alor Setar city folks.A non-probability convenience sampling technique was used to collect data from early February to mid-March 2015.A sample comprising 108 respondents were subjected to binary logistic regression analysis. The major finding of this study showed that risk attitude has a significant and negative relationship with the purchase of life insurance.Respondents in Alor Setar who are more likely to involve in risky behaviours or activities tend not to buy life insurance.Risk taking individuals do not behave like risk averse individuals who tend to seek protection by buying life insurance as a method to cover their personal risks.Meanwhile, personal value and trust were found to have no significant relationship with the purchase of life insurance among respondents in Alor Setar.It is recommended that a comprehensive study covering wider areas with larger sample sizes be included in future studies to obtain more reliable results that would enable the generalisation of finding

Design and Development of Artificial Intelligence (Al)-Based Desicion Support System For Manufacturing Applications

In this report, the research on welding defect detection and classification using radiograph images is presented. The first part of the report describes work on collection of digital radiograph images while the second part covers work on image processing and analysis using the collected images. The radiograph images from the Fuji DynamIX DynaView Workstation are custom-exported with the help of the NDT specialist. The collection of interpreted images is diverted from radiograph images captured using the old X-ray tube {Tube A) to the new X-ray tube (Tube B). Tube B images are needed to evaluate the performance of the developed defect detection algorithm under different radiography conditions. However, the total number of requested images remains approximately the same so that no extra workload is imposed to the NDT specialist. In the image processing stage, a flaw map, as described in the previous report, is used. Six welding defect types, namely Porosity{POR), Drop Through{DT), and Lack of Fusion{LOF), Lack of Penetration{LOP), Linear Indication{LI) and Undercut{UC), have been investigated. DT is detected using the background subtraction technique along with some heuristic rules as described in the previous report. For other detects, a set of image features including shape and texture information is extracted to characterize the welding defect flaws at the regions of interest (ROl). For POR, a series of sub-regions are further segmented in order to better represent the characteristics of POR at different locations in the ROl. To perform classification of the welding defects, an artificial intelligence (AI) technique, i.e., the Fuzzy ARTMAP (FAM) neural network, is applied. A series of experiments has been conducted by using the sample images collected from Tubes A and B. The overall performance is around 73% for accuracy, sensitivity, and specificity for both CF6-80 Connector Weld and Cover Weld programs. The only exception is that the sensitivity rate of the Connector Weld program stands around 63%. Further work will focus on ascertaining the stability of the FAM network in defect classification, as well as on improving the overall performance of the defect detection algorithms developed in this project. Il