951 resultados para CIRCUIT BOARDS
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Reliability of power converters is of crucial importance in switched reluctance motor drives used for safety-critical applications. Open-circuit faults in power converters will cause the motor to run in unbalanced states, and if left untreated, they will lead to damage to the motor and power modules, and even cause a catastrophic failure of the whole drive system. This study is focused on using a single current sensor to detect open-circuit faults accurately. An asymmetrical half-bridge converter is considered in this study and the faults of single-phase open and two-phase open are analysed. Three different bus positions are defined. On the basis of a fast Fourier transform algorithm with Blackman window interpolation, the bus current spectrums before and after open-circuit faults are analysed in details. Their fault characteristics are extracted accurately by the normalisations of the phase fundamental frequency component and double phase fundamental frequency component, and the fault characteristics of the three bus detection schemes are also compared. The open-circuit faults can be located by finding the relationship between the bus current and rotor position. The effectiveness of the proposed diagnosis method is validated by the simulation results and experimental tests.
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This study examined the acceptability and utility of the content of an extensive automobile tort voir dire questionnaire in Florida Circuit Civil Court. The ultimate purpose was to find questionnaire items from established measures that have demonstrated utility in uncovering biases that were at the same time not objectionable to the courts. The survey instrument included a venireperson questionnaire that used case-specific attitudinal and personality measures as well as typical information asked about personal history. The venireperson questionnaire incorporated measures that have proven reliable in other personal injury studies (Hans, & Lofquist, 1994). In order to examine judges' ratings, the questionnaire items were grouped into eight categories. Claims Consciousness scale measures general attitudes towards making claims based on one's legal rights. Belief in a Just World measures how sympathetic the juror would be to people who have suffered injuries. Political Efficacy is another general attitude scale that identifies attitudes towards the government. Litigation Crisis scales elicits attitudes about civil litigation. Case Specific Beliefs about Automobile Accidents and Litigation were taken from questionnaires developed and used in auto torts and other personal injury cases. Juror's personal history was divided into Demographics and Trial Relevant Attitudes. Ninety-seven circuit civil judges critiqued the questionnaire for acceptability, relevance to the type of case presented, and usefulness to attorneys for determining peremptories. ^ The majority of judges' responses confirmed that the central dimension in judicial thinking is juror qualification rather than juror partiality. Only three of the eight voir dire categories were considered relevant by more than 50 percent of the judges: Trial Relevant Experiences, Juror Demographics, and Tort Reform. Additionally, several acceptable items from generally disapproved categories were identified among the responses. These were general and case specific attitudinal items that are related to tort reform. We discuss the utility of voir dire items for discerning juror partiality. ^
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The Balmis expedition, sent to America by the Spanish monarch Charles IV in 1803, was a watershed in the history of Medicine as it made smallpox vaccination available for the first time, effectively prevented the disease from spreading, and saved thousands of lives. Immunization required complex administrative measures and political decisions including the creation of Vaccination Boards, all of which involved different sectors of Spanish American society. This dissertation argues that at the beginning of the nineteenth century the Spanish American colonial state had reached some level of maturity and cohesion that made it capable of executing this complex project in public health. The significance of this mobilization and the every-day experience in implementing this new public health measure is the center of this work. It is situated geographically in Venezuela and Cuba, entities which took different evolutionary paths in the nineteenth century. The organization and functioning of Vaccination Boards in these two areas are used to illustrate the state formation process, and sharp political differences in this critical period.
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This research deals with the development of a dynamic job quotation system for printed circuit board (PCB) fabrication, which can estimate the price and completion time of a job based on customer preference and current capacity of the shop floor. The primary purpose of building a dynamic quotation system is to maximize the company's profit by quoting optimum lead-time and competitive price for the day-to-day orders received from different customers and original equipment manufacturers. The system was developed using MS-Access relational database. Evaluating the output of the system it was observed that the dynamic system provided more reliable estimation of the lead-time needed for fabricating new jobs. The overall price quoted by the system was competitive with higher profit margin when compared to traditional static systems. This system would therefore provide a vital link between the job quoting and scheduling system of the firm enabling better utilization of the available resources.
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To the apparent surprise of policy makers at the provincial and school board levels, Ontario’s public schools are about to experience a massive exodus of principals and vice principals. This report, funded by a grant from the Ontario Principals’ Council, details the scale of the retirement wave currently hitting Ontario’s public school boards. Data collected from 946 practicing school administrators suggest that the retirement rates will be almost 20 per cent higher than provincial estimates. Anecdotal evidence suggests that the pool of qualified candidates for these positions is also shrinking. Already, fewer individuals are applying for each available vacancy. The study examines the major dissatisfiers in the current role of school principal as experienced by incumbents. Interviews were also conducted with 92 individuals identified as exceptional candidates for the principalship who had opted not to follow that career path in order to determine what factors they found most important in their decision making. The report concludes with recommendations for the province, school boards and principals' organizations.
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Densification is a key to greater throughput in cellular networks. The full potential of coordinated multipoint (CoMP) can be realized by massive multiple-input multiple-output (MIMO) systems, where each base station (BS) has very many antennas. However, the improved throughput comes at the price of more infrastructure; hardware cost and circuit power consumption scale linearly/affinely with the number of antennas. In this paper, we show that one can make the circuit power increase with only the square root of the number of antennas by circuit-aware system design. To this end, we derive achievable user rates for a system model with hardware imperfections and show how the level of imperfections can be gradually increased while maintaining high throughput. The connection between this scaling law and the circuit power consumption is established for different circuits at the BS.
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As an important component in collaborative natural resource management and nonprofit governance, social capital is expected to be related to variations in the performance of land trusts. Land trusts are charitable organizations that work to conserve private land locally, regionally, or nationally. The purpose of this paper is to identify the level of structural and cognitive social capital among local land trusts, and how these two types of social capital relate to the perceived success of land trusts. The analysis integrates data for land trusts operating in the U.S. south-central Appalachian region, which includes western North Carolina, southwest Virginia, and east Tennessee. We use factor analysis to elicit different dimensions of cognitive social capital, including cooperation among board members, shared values, common norms, and communication effectiveness. Measures of structural social capital include the size and diversity of organizational networks of both land trusts and their board members. Finally, a hierarchical linear regression model is employed to estimate how cognitive and structural social capital measures, along with other organizational and individual-level attributes, relate to perceptions of land trust success, defined here as achievement of the land trusts’ mission, conservation, and financial goals. Results show that the diversity of organizational partnerships, cooperation, and shared values among land trust board members are associated with higher levels of perceived success. Organizational capacity, land trust accreditation, volunteerism, and financial support are also important factors influencing perceptions of success among local, nonprofit land trusts.
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Abstract not available
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Languages based upon binary relations offer an appealing setting for constructing programs from specifications. For example, working with relations rather than functions allows specifications to be more abstract (for example, many programs have a natural specification using the converse operator on relations), and affords a natural treatment of non-determinism in specifications. In this paper we present a novel pictorial interpretation of relational terms as simple pictures of circuits, and a soundness/completeness result that allows relational equations to be proved by pictorial reasoning.
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The focus of this research is to explore the applications of the finite difference formulation based on the latency insertion method (LIM) to the analysis of circuit interconnects. Special attention is devoted to addressing the issues that arise in very large networks such as on-chip signal and power distribution networks. We demonstrate that the LIM has the power and flexibility to handle various types of analysis required at different stages of circuit design. The LIM is particularly suitable for simulations of very large scale linear networks and can significantly outperform conventional circuit solvers (such as SPICE).
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This report gives a summary of common pleas cases broken down by county and circuit.
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This gives the criminal records summary of activity by circuit/county.
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In this article I deal with extending the ethical principles of research to include communities through the establishment of Community Advisory Boards (CABs). The aim of the project on which this article is based demonstrates the need for protecting communities that participate in research in order to stimulate ethical conduct in research in Malawi. In the article, I provide an overview on the role and functions of CABs. I discuss the establishment of CABs in Malawi and present descriptions of the processes and challenges involved. I conclude by sharing experiences of some of the key lessons learnt from the establishment of CABs.
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National audience