777 research outputs found

    Embedded finite-element solver for computation of brushless permanent-magnet motors

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    This paper describes the theory underlying the formulation of a “minimum set” of finite-element solutions to be used in the design and analysis of saturated brushless permanent-magnet motors. The choice of finite-element solutions is described in terms of key points on the flux–MMF diagram. When the diagram has a regular shape, a huge reduction in finite-element analysis is possible with no loss of accuracy. If the loop is irregular, many more solutions are needed. This paper describes an efficient technique in which a finite-element solver is associated with a classical ddqq-axis circuit model in such a way that the number of finite-element solutions in one electrical half-cycle can be varied between 1 and 360. The finite-element process is used to determine not only the average torque but also the saturated inductances as the rotor rotates

    Information Sharing and Rating Manipulation

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    Natural and anthropogenic changes in atmospheric greenhouse gases over the past 2 millennia

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    Millennial changes in atmospheric trace gas composition are best determined from air enclosed in ice sheets. Air extracted from the open pores in firn and the bubbles in ice is measured to derive the past concentrations and isotopic ratios of the long lived trace gases. The significant increases observed in CO2, CH4 and N2O since about 1750 and the more recent appearance of synthetic gases such as the CFCs in the atmosphere are a key feature of the anthropocene. The millennia preceding the anthropocene, the Late Pre-Industrial Holocene (LPIH), show evidence of natural changes in trace gases that can be used to constrain models and improve their ability to predict future changes under scenarios of anthropogenic emissions and climate change. Precise measurements and ice core air samples that are accurately dated and highly resolved in time are required to record the small and rapid trace gas signals of this period. The atmospheric composition records produced by CSIRO and collaborators using the Law Dome, Antarctica ice cores are widely used in models of climate, atmospheric chemistry and the carbon cycle over the anthropocene and the LPIH. Results from these studies have been influential in informing global policies, including the Montreal and Kyoto Protocols. We will present the recently revised trace gas records from Law Dome and new measurements of tracers from these and other ice sites that reveal the causes of atmospheric changes over the anthropocene and the LPIH

    How Do Laws and Institutions Affect Recovery Rates for Collateral?

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    Using unique internal bank data on ex ante appraised liquidation and market values of assets pledged as collateral in sixteen countries, we show that laws and institutions that strengthen creditor protection increase expected recovery rates for collateral. Stronger creditor protection increases expected recovery rates for movable collateral relative to immovable collateral and shifts the composition of collateral toward movable assets, thereby increasing debt capacity through both higher loan-to-values and attenuating the creditor's liquidation bias. Our results suggest that the recovery rate for collateral is an important first-stage mechanism through which creditor protection can improve contracting efficiency and enhance access to credit

    Broader impacts of an intervention to transform school environments on student behaviour and school functioning: post hoc analyses from the INCLUSIVE cluster randomised controlled trial.

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    BACKGROUND: We have previously reported benefits for reduced bullying, smoking, alcohol and other drug use and mental health from a trial of 'Learning Together', an intervention that aimed to modify school environments and implement restorative practice and a social and emotional skill curriculum. OBJECTIVES: To conduct post hoc theory-driven analyses of broader impacts. DESIGN: Cluster randomised trial. SETTINGS: 40 state secondary schools in southern England. PARTICIPANTS: Students aged 11/12 years at baseline. OUTCOMES: Student self-reported measures at 24 and 36 months of: cyberbullying victimisation and perpetration; observations of other students perpetrating aggressive behaviours at school; own perpetration of aggressive behaviours in and outside school; perceived lack of safety at school; participation in school disciplinary procedures; truancy and e-cigarette use. RESULTS: We found evidence of multiple impacts on other health (reduced e-cigarette use, cyberbullying perpetration, perpetration of aggressive behaviours) and educational (reduced participation in school disciplinary procedures and truancy) outcomes. CONCLUSION: These analyses suggested that the intervention was effective in bringing about a broader range of beneficial outcomes, adding to the evidence that the intervention is a promising approach to promote adolescent health via an intervention that is attractive to schools. TRIAL REGISTRATION NUMBER: ISRCTN10751359
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