Population inversion of a driven two-level system in a structureless bath

We derive a master equation for a driven double quantum dot damped by an unstructured phonon bath, and calculate the spectral density. We find that bath-mediated photon absorption is important at relatively strong driving, and may even dominate the dynamics, inducing population inversion of the double-dot system. This phenomenon is consistent with recent experimental observations.

Power system sensitivity analysis for probabilistic small signal stability assessment in a deregulated environment

Deregulations and market practices in power industry have brought great challenges to the system planning area. In particular, they introduce a variety of uncertainties to system planning. New techniques are required to cope with such uncertainties. As a promising approach, probabilistic methods are attracting more and more attentions by system planners. In small signal stability analysis, generation control parameters play an important role in determining the stability margin. The objective of this paper is to investigate power system state matrix sensitivity characteristics with respect to system parameter uncertainties with analytical and numerical approaches and to identify those parameters have great impact on system eigenvalues, therefore, the system stability properties. Those identified parameter variations need to be investigated with priority. The results can be used to help Regional Transmission Organizations (RTOs) and Independent System Operators (ISOs) perform planning studies under the open access environment.

Focused, eight-element transceive phased array coil for parallel magnetic resonance imaging of the chest-theoretical considerations

A new transceive system for chest imaging for MRI applications is presented. A focused, eight-element transceive torso phased array coil is designed to investigate transmitting a focused radiofrequency field deep within the torso and to enhance signal homogeneity in the heart region. The system is used in conjunction with the SENSE reconstruction technique to enable focused parallel imaging. A hybrid finite-difference-time-domain/method-of-moments method is used to accurately predict the radiofrequency behavior inside the human torso. The simulation results reported herein demonstrate the feasibility of the design concept, which shows that radiofrequency field focusing with SENSE reconstruction is theoretically achievable. (c) 2005 Wiley-Liss, Inc.

Predictors of young dating adults' inclination to engage in extradyadic sexual activities: A multi-perspective study

Using a multi-perspective vignette design, we explored predictors of young peoples' (N = 119) propensity to engage in unfaithful activities while dating. Demographic measures, a datding investment model, and measures of functional and dysfunctional impulsivity were used to predict inclination to engage in each of two extradyadic activities (kissing and sexual activity). The results of moderated multiple regression analyses revealed that a respondent's number of sexual partners, level of dysfunctional impulsivity, satisfaction with current relationship, and quality of relationship alternatives significantly predicted inclination to engage in both of the extradyadic activities. Consistent with previous findings, gender only showed significant predictive value in relation to extradyadic sex inclination. Moreover, the association between sex, love, and marriage interacted with gender in the prediction of both extradyadic activities and interacted with commitment in the prediction of extradyadic sex inclination. Suggestions for future research in this area are offered in light of these new findings.

Balancing curriculum processes and content in a project centred curriculum - In pursuit of graduate attributes

Chemical engineering education is challenged around the world by demands and rapid changes encompassing a wide range of technical and social drivers. Graduates must be prepared for practice in increasingly diverse workplace environments in which generic or transferable attributes such as communication and teamwork together with technical excellence are mandated by prospective employers and society at large. If academe is to successfully deliver on these graduate attributes, effective curriculum design needs to include appropriate educational processes as well as course content. Conventional teacher centred approaches, stand-alone courses and retro-fitted remedial modules have not delivered the desired outcomes. Development of the broader spectrum of attributes is more likely when students are engaged with realistic and relevant experiences that demand the integration and practice of these attributes in contexts that the students find meaningful. This paper describes and evaluates The University of Queensland's Project Centred Curriculum in Chemical Engineering (PCC), a programme-wide approach to meeting these requirements. PCC strategically integrates project-based learning with more traditional instruction. Data collected shows improved levels of student attainment of generic skills with institutional and nationally benchmarked indicators showing significant increases in student perceptions of teaching quality, and overall satisfaction with the undergraduate experience. Endorsements from Australian academic, professional and industry bodies also support the approach as more effectively aligning engineering education with professional practice requirements.

CONTRIBUIÇÃO DOS CURSOS SUPERIORES DE TECNOLOGIA NA EDUCAÇÃO PROFISSIONAL DO TRABALHADOR BRASILEIRO

Os Cursos Superiores de Tecnologia são um tipo específico de graduação (tecnólogo), com características próprias, entre as quais, a focalização na especialização dos seus currículos e duração mais curta objetivando uma formação mais rápida. A graduação tecnológica vem sendo amplamente difundida no país desde a segunda metade da década de 1990, após a promulgação da lei no 9.394/96 LDB, e por uma série de decretos, portarias e pareceres do MEC/CNE. Entre as principais metas e objetivos do PNE para a educação superior, se destacam: diversificação do sistema superior de ensino para atender clientelas com demandas específicas de formação; articulação entre currículo e mercado de trabalho; financiamento e gestão; criação de políticas de acesso à educação superior que facilitem o ingresso de alunos provenientes de grupos de maior vulnerabilidade educacional; crescimento da oferta de educação superior para a faixa etária de 18 a 24 anos. O presente estudo tem por objetivo refletir e debater a contribuição dos CSTs na educação profissional do trabalhador brasileiro dentro das perspectivas do PNE. O estudo se fundamenta no método qualitativo, com base numa pesquisa exploratória e descritiva, caracterizada como estudo de caso único, através da pesquisa de campo realizada com alunos em formação e com egressos do Curso de Eletrônica Industrial da Faculdade de Tecnologia Senai Anchieta, na cidade de São Paulo. Para alcançar seus objetivos, o estudo foi dividido em duas etapas: a primeira faz uma análise das variáveis que caracterizam o perfil do aluno em formação buscando identificar sua percepção quanto à escolha pelo CST, conhecimento sobre essa modalidade de ensino e as expectativas futuras da profissão. Na segunda parte, o estudo faz uma análise da percepção do egresso acerca das habilidades e competências adquiridas durante a formação, o grau de satisfação com salário e plano de carreira, e a aceitação profissional do tecnólogo pelo mercado de trabalho. No estudo realizado com alunos em formação constatou-se que os índices de evasão escolar das primeiras turmas do curso foram elevados, sendo apontadas como principais causas as dificuldades de conciliação entre o horário de estudo com a do trabalho e as dificuldades econômicas familiares. O perfil do aluno em formação na IES em estudo é majoritariamente da faixa etária entre 18 e 24 anos; do gênero masculino; egresso do ensino médio feito em escola pública; morador em bairro periférico e natural de cidade da RMSP; o próprio aluno é responsável pelo pagamento das mensalidades; não houve interferência de terceiros na sua escolha pelo CST; tem percepção favorável quanto à empregabilidade futura como tecnólogo. A pesquisa com egressos apontou que os mesmos tem percepção favorável quanto à formação profissional recebida, exceto o fato de não terem atendido disciplinas que desenvolvessem competências gerenciais e de negócios; quanto à empregabilidade e perspectivas de carreira mostraram preocupação na valorização profissional do tecnólogo pelo mercado de trabalho; declararam estar insatisfeitos quanto ao salário recebido; quanto à educação continuada reconheceram ser esse o processo que os manterão atualizados profissionalmente. Como conclusão da pesquisa, há recomendação para estudos futuros na sondagem de outras possíveis causas da evasão escolar com alunos dos cursos com outros eixos temáticos e de IES públicas. Igualmente, aponta-se para a necessidade da proposta curricular da IES em estudo oferecer, além das disciplinas técnicas, outras que desenvolvam competências e habilidade em gestão de pessoas e negócios.

An assessment of the learning benefits of using a web-based learning environment when teaching accounting

The impact and use of information and communication technology on learning outcomes for accounting students is not well understood. This study investigates the impact of design features of Blackboard 1 used as aWeb-based Learning Environment (WBLE) in teaching undergraduate accounting students. Specifically, this investigation reports on a number of Blackboard design features (e.g. delivery of lecture notes, announcements, online assessment and model answers) used to deliver learning materials regarded as necessary to enhance learning outcomes. Responses from 369 on-campus students provided data to develop a regression model that seeks to explain enhanced participation and mental effort. The final regression shows that student satisfaction with the use of a WBLE is associated with five design features or variables. These include usefulness and availability of lecture notes, online assessment, model answers, and online chat.

Mathematical methods in power system stability studies

In this thesis various mathematical methods of studying the transient and dynamic stabiIity of practical power systems are presented. Certain long established methods are reviewed and refinements of some proposed. New methods are presented which remove some of the difficulties encountered in applying the powerful stability theories based on the concepts of Liapunov. Chapter 1 is concerned with numerical solution of the transient stability problem. Following a review and comparison of synchronous machine models the superiority of a particular model from the point of view of combined computing time and accuracy is demonstrated. A digital computer program incorporating all the synchronous machine models discussed, and an induction machine model, is described and results of a practical multi-machine transient stability study are presented. Chapter 2 reviews certain concepts and theorems due to Liapunov. In Chapter 3 transient stability regions of single, two and multi~machine systems are investigated through the use of energy type Liapunov functions. The treatment removes several mathematical difficulties encountered in earlier applications of the method. In Chapter 4 a simple criterion for the steady state stability of a multi-machine system is developed and compared with established criteria and a state space approach. In Chapters 5, 6 and 7 dynamic stability and small signal dynamic response are studied through a state space representation of the system. In Chapter 5 the state space equations are derived for single machine systems. An example is provided in which the dynamic stability limit curves are plotted for various synchronous machine representations. In Chapter 6 the state space approach is extended to multi~machine systems. To draw conclusions concerning dynamic stability or dynamic response the system eigenvalues must be properly interpreted, and a discussion concerning correct interpretation is included. Chapter 7 presents a discussion of the optimisation of power system small sjgnal performance through the use of Liapunov functions.

Estimating ECAP threshold from the variability of the response

Electrical compound action potentials (ECAPs) of the cochlear nerve are used clinically for quick and efficient cochlear implant parameter setting. The ECAP is the aggregate response of nerve fibres at various distances from the recording electrode, and the magnitude of the ECAP is therefore related to the number of fibres excited by a particular stimulus. Current methods, such as the masker-probe or alternating polarity methods, use the ECAP magnitude at various stimulus levels to estimate the neural threshold, from which the parameters are calculated. However, the correlation between ECAP threshold and perceptual threshold is not always good, with ECAP threshold typically being much higher than perceptual threshold. The lower correlation is partly due to the very different pulse rates used for ECAPs (below 100 Hz) and clinical programs (hundreds of Hz up to several kHz). Here we introduce a new method of estimating ECAP threshold for cochlear implants based upon the variability of the response. At neural threshold, where some but not all fibers respond, there is a different response each trial. This inter-trial variability can be detected overlaying the constant variability of the system noise. The large stimulus artefact, which requires additional trials for artefact rejection in the standard ECAP magnitude methods, is not consequential, as it has little variability. The variability method therefore consists of simply presenting a pulse and recording the ECAP, and as such is quicker than other methods. It also has the potential to be run at high rates like clinical programs, potentially improving the correlation with behavioural threshold. Preliminary data is presented that shows a detectable variability increase shortly after probe offset, at probe levels much lower than those producing a detectable ECAP magnitude. Care must be taken, however, to avoid saturation of the recording amplifier saturation; in our experiments we found a gain of 300 to be optimal.

Accessibility, deprivation and rural planning policies.

Since the Second World War a range of policies have been implemented by central and local government agencies, with a view to improving accessibility to facilities, housing and employment opportunities within rural areas. It has been suggested that a lack of reasonable access to a range of such facilities and opportunities constitutes a key aspect of deprivation or disadvantage for rural residents. Despite considerable interest, very few attempts have been made to assess the nature and incidence of this disadvantage or the reaction of different sections of the population of rural areas to it. Moreover, almost all previous assessments have relied on so-called 'objective' measures of accessibility and disadvantage and failed to consider the relationship between such measures and 'subjective' measures such as individual perceptions. It is this gap in knowledge that the research described in this thesis has addressed. Following a critical review of relevant literature the thesis describes the way in which data on 'objective' and 'subjective' indicators of accessibility and behavioural responses to accessibility problems was collected, in six case study areas in Shropshire. Analysis of this data indicates that planning and other government policies have failed to significantly improve rural resident's accessibility to their basic requirements, and may in some cases have exacerbated it, and that as a result certain sections of the rural population are relatively disadvantaged. Moreover, analysis shows that .certain aspects of individual subjective' assessments of such accessibility disadvantage are significantly associated with more easily-obtained 'objective' measures. By using discriminant analysis the research demonstrates that it is possible to predict the likely levels of satisfaction with access to facilities from a range of 'objective' measures. The research concludes by highlighting the potential practical applications of such indicators in policy formulation, policy appraisal and policy evaluation.

Evaluation and measurement of multiprocessor systems with shared memory

This study is concerned with several proposals concerning multiprocessor systems and with the various possible methods of evaluating such proposals. After a discussion of the advantages and disadvantages of several performance evaluation tools, the author decides that simulation is the only tool powerful enough to develop a model which would be of practical use, in the design, comparison and extension of systems. The main aims of the simulation package developed as part of this study are cost effectiveness, ease of use and generality. The methodology on which the simulation package is based is described in detail. The fundamental principles are that model design should reflect actual systems design, that measuring procedures should be carried out alongside design that models should be well documented and easily adaptable and that models should be dynamic. The simulation package itself is modular, and in this way reflects current design trends. This approach also aids documentation and ensures that the model is easily adaptable. It contains a skeleton structure and a library of segments which can be added to or directly swapped with segments of the skeleton structure, to form a model which fits a user's requirements. The study also contains the results of some experimental work carried out using the model, the first part of which tests• the model's capabilities by simulating a large operating system, the ICL George 3 system; the second part deals with general questions and some of the many proposals concerning multiprocessor systems.

Managerial job satisfaction:a longitudinal study

The study examines the job satisfaction of supervisors and managers in four organisations over time. It also considers the importance which they attached to different facets of their job. The major objectives were: To examine the constituent dimensions of job satisfaction at intervals over one year. To examine reasons for change inthe level of job satisfaction at intervals over one year. To provide information on job satisfaction for those concerned with job satisfaction policies. The sample consisted of one hundred and eight people. Each was interviewed on at least three occasions over the course of a year. Interviews took place at predetermined time intervals. The study shows that job satisfaction is dynamic over a relatively short period of time. The ratings which supervisors and managers gave to aspects of their job did not, however, all change by equal amounts or in the same direction. Changes in job satisfaction were associated with events experienced but it was the meaning of those events to correspondents which appeared to be particularly important. People tended to adopt a localised frame of reference when considering their work situation. Certain job variables, such as variety, were consistently and positively correlated with job satisfaction. With some other variables, the relationship varied across time. Frequently, age and job level moderated the association between independent variables and job satisfaction. Links were found between the quality of life and job satisfaction. There was a consistent positive association between job satisfaction and life satisfaction. However, the job was rarely considered to be the main factor contributing to a person's quality of life. The research highlights the difficulties and desirability of introducing standardised job satisfaction policies in the light of individual differences. In addition, it demonstrates that merely correlating variables with job satisfaction at one point in time may conceal complex relationships and meanings. A new measure of job satisfaction - whereby facets are assessed and rated relative to each other was also developed as part of this study.

Development of an electric heat pump for domestic use

This thesis records the design and development of an electrically driven, air to water, vapour compression heat pump of nominally 6kW heat output, for residential space heating. The study was carried out on behalf of GEC Research Ltd through the Interdisciplinary Higher Degrees Scheme at Aston University. A computer based mathematical model of the vapour compression cycle was produced as a design aid, to enable the effects of component design changes or variations in operating conditions to be predicted. This model is supported by performance testing of the major components, which revealed that improvements in the compressor isentropic efficiency offer the greatest potential for further increases in cycle COPh. The evaporator was designed from first principles, and is based on wire-wound heat transfer tubing. Two evaporators, of air side area 10.27 and 16.24m2, were tested in a temperature and humidity controlled environment, demonstrating that the benefits of the large coil are greater heat pump heat output and lower noise levels. A systematic study of frost growth rates suggested that this problem is most severe at the conditions of saturated air at 0oC combined with low condenser water temperature. A dynamic simulation model was developed to predict the in-service performance of the heat pump. This study confirmed the importance of an adequate radiator area for heat pump installations. A prototype heat pump was designed and manufactured, consisting of a hermetic reciprocating compressor, a coaxial tube condenser and a helically coiled evaporator, using Refrigerant 22. The prototype was field tested in a domestic environment for one and a half years. The installation included a comprehensive monitoring system. Initial problems were encountered with defrosting and compressor noise, both of which were solved. The unit then operated throughout the 1985/86 heating season without further attention, producing a COPh of 2.34.

Vibration analysis of submerged rectangular microplates with distributed mass loading

This paper investigates the vibration characteristics of the coupling system of a microscale fluid-loaded rectangular isotropic plate attached to a uniformly distributed mass. Previous literature has, respectively, studied the changes in the plate vibration induced by an acoustic field or by the attached mass loading. This paper investigates the issue of involving these two types of loading simultaneously. Based on Lamb's assumption of the fluid-loaded structure and the Rayleigh–Ritz energy method, this paper presents an analytical solution for the natural frequencies and mode shapes of the coupling system. Numerical results for microplates with different types of boundary conditions have also been obtained and compared with experimental and numerical results from previous literature. The theoretical model and novel analytical solution are of particular interest in the design of microplate-based biosensing devices.