Justifying threshold voltage definition for undoped body transistors through ``crossover point'' concept

Two different definitions, one is potential based and the other is charge based, are used in the literatures to define the threshold voltage of undoped body symmetric double gate transistors. This paper, by introducing a novel concept of crossover point, proves that the charge based definition is more accurate than the potential based definition. It is shown that for a given channel length the potential based definition predicts anomalous change in threshold voltage with body thickness variation while the charge based definition results in monotonous change. The threshold voltage is then extracted from drain current versus gate voltage characteristics using linear extrapolation, transconductance and match-point methods. In all the three cases it is found that trend of threshold voltage variation support the charge based definition.

A Combination of Hexagonal and 12-Sided Polygonal Voltage Space Vector PWM Control for IM Drives Using Cascaded Two-Level Inverters

This paper proposes a multilevel inverter configuration which produces a hexagonal voltage space vector structure in the lower modulation region and a 12-sided polygonal space vector structure in the overmodulation region. A conventional multilevel inverter produces 6n plusmn 1 (n = odd) harmonics in the phase voltage during overmodulation and in the extreme square-wave mode of operation. However, this inverter produces a 12-sided polygonal space vector location, leading to the elimination of 6n plusmn 1 (n = odd) harmonics in the overmodulation region extending to a final 12-step mode of operation with a smooth transition. The benefits of this arrangement are lower losses and reduced torque pulsation in an induction motor drive fed from this converter at higher modulation indexes. The inverter is fabricated by using three conventional cascaded two-level inverters with asymmetric dc-bus voltages. A comparative simulation study of the harmonic distortion in the phase voltage and associated losses in conventional multilevel inverters and that of the proposed inverter is presented in this paper. Experimental validation on a prototype shows that the proposed converter is suitable for high-power applications because of low harmonic distortion and low losses.

Breakdown voltage and V-Z characteristics of sodium vapour using coaxial cylindrical electrodes

Experimental results for breakdown voltage of sodium vapour measured for the first time using coaxial cylindrical electrodes of fixed gap distance (5 mm) and pressure (corrected to2 0 "C) in the range2 1 to 652 Pa are reported, and are founfdo l ltoow Paschen's Law. The investigations also reveal that V th-Ie characteristics are pressure dependent; the current during the breakdown and the buoifl dc-uurpre nt after a breakdoiws nei ther positive or negative. in spite of the central cylinder being always maintained at a positive potential

A DC-link Capacitor Voltage Balancing with CMV Elimination using only the Switching State Redundancies for a Reduced Switch Count Multi-Level Inverter fed IM Drive

Common mode voltage (CMV) variations in PWM inverter-fed drives generate unwanted shaft and bearing current resulting in early motor failure. Multilevel inverters reduce this problem to some extent, with higher number of levels. But the complexity of the power circuit increases with an increase in the number of inverter voltage levels. In this paper a five-level inverter structure is proposed for open-end winding induction motor (IM) drives, by cascading only two conventional two-level and three-level inverters, with the elimination of the common mode voltage over the entire modulation range. The DC link power supply requirement is also optimized by means of DC link capacitor voltage balancing, with PWM control., using only inverter switching state redundancies. The proposed power circuit gives a simple power bits structure.

Achievements in forest tree improvement in Australia and New Zealand 6: Genetic improvement and conservation of Araucaria cunninghamii in Queensland

Araucaria cunninghamii (hoop pine) typically occurs as an emergent tree over subtropical and tropical rainforests, in a discontinuous distribution that extends from West Irian Jaya at about 0°30'S, through the highlands of Indonesian New Guinea and Papua New Guinea, along the east coast of Australia from 11°39'S in Queensland to 30°35'S in northern New South Wales. Plantations established in Queensland since the 1920s now total about 44000 ha, and constitute the primary source for the continuing supply of hoop pine quality timber and pulpwood, with a sustainable harvest exceeding 440 000 m3 y-1. Establishment of these managed plantations allowed logging of all native forests of Araucaria species (hoop pine and bunya pine, A. bidwillii) on state-owned lands to cease in the late 1980s, and the preservation of large areas of araucarian forest types within a system of state-owned and managed reserves. The successful plantation program with this species has been strongly supported by genetic improvement activities since the late 1940s - through knowledge of provenance variation and reproductive biology, the provision of reliable sources of improved seed, and the capture of substantial genetic gains in traits of economic importance (for example growth, stem straightness, internode length and spiral grain). As such, hoop pine is one of the few tropical tree species that, for more than half a century, has been the subject of continuous genetic improvement. The history of commercialisation and genetic improvement of hoop pine provides an excellent example of the dual economic and conservation benefits that may be obtained in tropical tree species through the integration of gene conservation and genetic improvement with commercial plantation development. This paper outlines the natural distribution and reproductive biology of hoop pine, describes the major achievements of the genetic improvement program in Queensland over the past 50+ y, summarises current understanding of the genetic variation and control of key selection traits, and outlines the means by which genetic diversity in the species is being conserved.

Domestication to crop improvement: Genetic resources for Sorghum and Saccharum (Andropogoneae).

Background: Both sorghum (Sorghum bicolor) and sugarcane (Saccharum officinarum) are members of the Andropogoneae tribe in the Poaceae and are each other's closest relatives amongst cultivated plants. Both are relatively recent domesticates and comparatively little of the genetic potential of these taxa and their wild relatives has been captured by breeding programmes to date. This review assesses the genetic gains made by plant breeders since domestication and the progress in the characterization of genetic resources and their utilization in crop improvement for these two related species. Genetic Resources: The genome of sorghum has recently been sequenced providing a great boost to our knowledge of the evolution of grass genomes and the wealth of diversity within S. bicolor taxa. Molecular analysis of the Sorghum genus has identified close relatives of S. bicolor with novel traits, endosperm structure and composition that may be used to expand the cultivated gene pool. Mutant populations (including TILLING populations) provide a useful addition to genetic resources for this species. Sugarcane is a complex polyploid with a large and variable number of copies of each gene. The wild relatives of sugarcane represent a reservoir of genetic diversity for use in sugarcane improvement. Techniques for quantitative molecular analysis of gene or allele copy number in this genetically complex crop have been developed. SNP discovery and mapping in sugarcane has been advanced by the development of high-throughput techniques for ecoTILLING in sugarcane. Genetic linkage maps of the sugarcane genome are being improved for use in breeding selection. The improvement of both sorghum and sugarcane will be accelerated by the incorporation of more diverse germplasm into the domesticated gene pools using molecular tools and the improved knowledge of these genomes.

Development of innovative robust stability enhancement algorithms for distribution systems containing distributed generators

This project was a step forward in improving the voltage profile of traditional low voltage distribution networks with high photovoltaic generation or high peak demand. As a practical and economical solution, the developed methods use a Dynamic Voltage Restorer or DVR, which is a series voltage compensator, for continuous and communication-less power quality enhancement. The placement of DVR in the network is optimised in order to minimise its power rating and cost. In addition, new approaches were developed for grid synchronisation and control of DVR which are integrated with the voltage quality improvement algorithm for stable operation.

Harmonics in voltage-source PWM inverters

he performance of an induction motor fed by PWM inverters is mainly determined by the harmonic contents of the output voltage. This paper presents a method of numerically calculating the harmonics in the output voltage waveform. Equal pulse-width modulation and siunsoidal PWM are studied. Analysis has been done for single-phase and three-phase bridge inverters. A systematic procedure is given for computing the harmonics and the results are. tabulated.

Achievements in forest tree genetic improvement in Australia and New Zealand 2: Development of Corymbia species and hybrids for plantations in eastern Australia

This paper describes the establishment of provenance seedling seed orchards of three spotted gums and cadaga (all species of Corymbia ex Eucalyptus). It also discusses the limitations of growing the spotted gums as pure species including: lack of mass flowering, susceptibility to a fungal shoot blight and low amenability to vegetative propagation. These limitations, together with observation of putative natural hybrids of the spotted gums with cadaga, and the early promise of manipulated hybrids, led to an intensive breeding and testing program. Many hybrid families have significant advantages in growth and tolerance to disease, insects and frost, and can be vegetatively propagated. They also exhibit broad environmental plasticity, allowing the best varieties to be planted across a wider range of sites than the spotted gums, resulting in more land being suitable for plantation development.

Past, current and future approaches to mango genetic improvement in Australia

Improving the genetic base of cultivars that underpin commercial mango production is generally recognized as necessary for long term industry stability. Genetic improvement can take many approaches to improve cultivars, each with their own advantages and disadvantages. This paper will discuss several approaches used in the genetic improvement of mangoes in Australia, including varietal introductions, selection of monoembryonic progeny, selection within polyembryonic populations, assisted open pollination and controlled closed pollination. The current activities of the Australian National Mango Breeding Program will be outlined, and the analysis and use of hybrid phenotype data from the project for selection of next generation parents will be discussed. Some of the important traits that will enhance the competitiveness of future cultivars will be introduced and the challenges in achieving them discussed. The use of a genomics approach and its impact on future mango breeding is examined.

A Pulsewidth Modulated Control of Induction Motor Drive Using Multilevel 12-Sided Polygonal Voltage Space Vectors

In this paper, a novel 12-sided polygonal space vector structure is proposed for an induction motor drive. The space vector pattern presented in this paper consists of two 12-sided concentric polygons with the outer polygon having a radius double the inner one. As compared to previously reported 12-sided polygonal space vector structures, this paper subdivides the space vector plane into smaller sized triangles. This helps in reducing the switching frequency of the inverters without deteriorating the output voltage quality. It also reduces the device ratings and dv/dt stress on the devices to half. At the same time, other benefits obtained from the existing 12-sided space vector structure, such as increased linear modulation range and complete elimination of 5th and 7th order harmonics in the phase voltage, are also retained in this paper. The space vector structure is realized by feeding an open-end induction motor with two conventional three-level neutral point clamped (NPC) inverters with asymmetric isolated dc link voltage sources. The neutral point voltage fluctuations in the three-level NPC inverters are eliminated by utilizing the switching state multiplicities for a space vector point. The pulsewidth modulation timings are calculated using sampled reference waveform amplitudes and are explained in detail in this paper. Experimental verification on a laboratory prototype shows that this configuration may be considered suitable for high power drives.

Teacher Education, School Effectiveness and Improvement : A Study of Academic and Professional Qualification on Teachers' Job Effectiveness in Nigerian Secondary Schools

This academic work begins with a compact presentation of the general background to the study, which also includes an autobiography for the interest in this research. The presentation provides readers who know little of the topic of this research and of the structure of the educational system as well as of the value given to education in Nigeria. It further concentrates on the dynamic interplay of the effect of academic and professional qualification and teachers' job effectiveness in secondary schools in Nigeria in particular, and in Africa in general. The aim of this study is to produce a systematic analysis and rich theoretical and empirical description of teachers' teaching competencies. The theoretical part comprises a comprehensive literature review that focuses on research conducted in the areas of academic and professional qualification and teachers' job effectiveness, teaching competencies, and the role of teacher education with particular emphasis on school effectiveness and improvement. This research benefits greatly from the functionalist conception of education, which is built upon two emphases: the application of the scientific method to the objective social world, and the use of an analogy between the individual 'organism' and 'society'. To this end, it offers us an opportunity to define terms systematically and to view problems as always being interrelated with other components of society. The empirical part involves describing and interpreting what educational objectives can be achieved with the help of teachers' teaching competencies in close connection to educational planning, teacher training and development, and achieving them without waste. The data used in this study were collected between 2002 and 2003 from teachers, principals, supervisors of education from the Ministry of Education and Post Primary Schools Board in the Rivers State of Nigeria (N=300). The data were collected from interviews, documents, observation, and questionnaires and were analyzed using both qualitative and quantitative methods to strengthen the validity of the findings. The data collected were analyzed to answer the specific research questions and hypotheses posited in this study. The data analysis involved the use of multiple statistical procedures: Percentages Mean Point Value, T-test of Significance, One-Way Analysis of Variance (ANOVA), and Cross Tabulation. The results obtained from the data analysis show that teachers require professional knowledge and professional teaching skills, as well as a broad base of general knowledge (e.g., morality, service, cultural capital, institutional survey). Above all, in order to carry out instructional processes effectively, teachers should be both academically and professionally trained. This study revealed that teachers are not however expected to have an extraordinary memory, but rather looked upon as persons capable of thinking in the right direction. This study may provide a solution to the problem of teacher education and school effectiveness in Nigeria. For this reason, I offer this treatise to anyone seriously committed in improving schools in developing countries in general and in Nigeria in particular to improve the lives of all its citizens. In particular, I write this to encourage educational planners, education policy makers, curriculum developers, principals, teachers, and students of education interested in empirical information and methods to conceptualize the issue this study has raised and to provide them with useful suggestions to help them improve secondary schooling in Nigeria. Though, multiple audiences exist for any text. For this reason, I trust that the academic community will find this piece of work a useful addition to the existing literature on school effectiveness and school improvement. Through integrating concepts from a number of disciplines, I aim to describe as holistic a representation as space could allow of the components of school effectiveness and quality improvement. A new perspective on teachers' professional competencies, which not only take into consideration the unique characteristics of the variables used in this study, but also recommend their environmental and cultural derivation. In addition, researchers should focus their attention on the ways in which both professional and non-professional teachers construct and apply their methodological competencies, such as their grouping procedures and behaviors to the schooling of students. Keywords: Professional Training, Academic Training, Professionally Qualified, Academically Qualified, Professional Qualification, Academic Qualification, Job Effectiveness, Job Efficiency, Educational Planning, Teacher Training and Development, Nigeria.

Integrated lean six sigma approach for patient flow improvement in hospital emergency department

This research aims to develop an Integrated Lean Six Sigma approach to investigate and resolve the patient flow problems in hospital emergency departments. It was proposed that the voice of the customer and the voice of the process should be considered simultaneously to investigate the current process of patient flow. Statistical analysis, visual process mapping with A3 problem solving sheet, and cause and effect diagrams have been used to identify the major patient flow issues. This research found that engaged frontline workers, long-term leadership obligation, an understanding of patients' requirements and the implementation of a systematic integration of lean strategies could continuously improve patient flow, health care service and growth in the emergency departments.

Environment characterization as an aid to wheat improvement: interpreting genotype-environment interactions by modelling water-deficit patterns in North-Eastern Australia.

Genotype-environment interactions (GEI) limit genetic gain for complex traits such as tolerance to drought. Characterization of the crop environment is an important step in understanding GEI. A modelling approach is proposed here to characterize broadly (large geographic area, long-term period) and locally (field experiment) drought-related environmental stresses, which enables breeders to analyse their experimental trials with regard to the broad population of environments that they target. Water-deficit patterns experienced by wheat crops were determined for drought-prone north-eastern Australia, using the APSIM crop model to account for the interactions of crops with their environment (e.g. feedback of plant growth on water depletion). Simulations based on more than 100 years of historical climate data were conducted for representative locations, soils, and management systems, for a check cultivar, Hartog. The three main environment types identified differed in their patterns of simulated water stress around flowering and during grain-filling. Over the entire region, the terminal drought-stress pattern was most common (50% of production environments) followed by a flowering stress (24%), although the frequencies of occurrence of the three types varied greatly across regions, years, and management. This environment classification was applied to 16 trials relevant to late stages testing of a breeding programme. The incorporation of the independently-determined environment types in a statistical analysis assisted interpretation of the GEI for yield among the 18 representative genotypes by reducing the relative effect of GEI compared with genotypic variance, and helped to identify opportunities to improve breeding and germplasm-testing strategies for this region.