Analytical calculation of resonant inductance for zero voltage switching in phase-shifted full-bridge converters

The phase shift full bridge (PSFB) converter allows high efficiency power conversion at high frequencies through zero voltage switching (ZVS); the parasitic drain-to-source capacitance of the MOSFET is discharged by a resonant inductance before the switch is gated resulting in near zero turn-on switching losses. Typically, an extra inductance is added to the leakage inductance of a transformer to form the resonant inductance necessary to charge and discharge the parasitic capacitances of the PSFB converter. However, many PSFB models do not consider the effects of the magnetizing inductance or dead-time in selecting the resonant inductance required to achieve ZVS. The choice of resonant inductance is crucial to the ZVS operation of the PSFB converter. Incorrectly sized resonant inductance will not achieve ZVS or will limit the load regulation ability of the converter. This paper presents a unique and accurate equation for calculating the resonant inductance required to achieve ZVS over a wide load range incorporating the effects of the magnetizing inductance and dead-time. The derived equations are validated against PSPICE simulations of a PSFB converter and extensive hardware experimentations.

Sustainable urban metabolism as a link between bio-physical sciences and urban planning: the BRIDGE project

Urban metabolism considers a city as a system with flows of energy and material between it and the environment. Recent advances in bio-physical sciences provide methods and models to estimate local scale energy, water, carbon and pollutant fluxes. However, good communication is required to provide this new knowledge and its implications to endusers (such as urban planners, architects and engineers). The FP7 project BRIDGE (sustainaBle uRban plannIng Decision support accountinG for urban mEtabolism) aimed to address this gap by illustrating the advantages of considering these issues in urban planning. The BRIDGE Decision Support System (DSS) aids the evaluation of the sustainability of urban planning interventions. The Multi Criteria Analysis approach adopted provides a method to cope with the complexity of urban metabolism. In consultation with targeted end-users, objectives were defined in relation to the interactions between the environmental elements (fluxes of energy, water, carbon and pollutants) and socioeconomic components (investment costs, housing, employment, etc.) of urban sustainability. The tool was tested in five case study cities: Helsinki, Athens, London, Florence and Gliwice; and sub-models were evaluated using flux data selected. This overview of the BRIDGE project covers the methods and tools used to measure and model the physical flows, the selected set of sustainability indicators, the methodological framework for evaluating urban planning alternatives and the resulting DSS prototype.

Implementation rules to bridge the theory/practice divide in market segmentation

Despite an extensive market segmentation literature, applied academic studies which bridge segmentation theory and practice remain a priority for researchers. The need for studies which examine the segmentation implementation barriers faced by organisations is particularly acute. We explore segmentation implementation through the eyes of a European utilities business, by following its progress through a major segmentation project. The study reveals the character and impact of implementation barriers occurring at different stages in the segmentation process. By classifying the barriers, we develop implementation "rules" for practitioners which are designed to minimise their occurrence and impact. We further contribute to the literature by developing a deeper understanding of the mechanisms through which these implementation rules can be applied.

A newly discovered portrait of Napoleon by Jacques-Louis David

This article establishes the authenticity of a half length portrait of Napoleon, long thought to be a copy.

An enhanced model for small-signal analysis of the phase-shifted full-bridge converter

This paper presents an in-depth critical discussion and derivation of a detailed small-signal analysis of the Phase-Shifted Full-Bridge (PSFB) converter. Circuit parasitics, resonant inductance and transformer turns ratio have all been taken into account in the evaluation of this topology’s open-loop control-to-output, line-to-output and load-to-output transfer functions. Accordingly, the significant impact of losses and resonant inductance on the converter’s transfer functions is highlighted. The enhanced dynamic model proposed in this paper enables the correct design of the converter compensator, including the effect of parasitics on the dynamic behavior of the PSFB converter. Detailed experimental results for a real-life 36V-to-14V/10A PSFB industrial application show excellent agreement with the predictions from the model proposed herein.1

Bridge-localized HOMO-binding character of divinylanthracene-bridged dinuclear ruthenium carbonyl complexes: spectroscopic, spectroelectrochemical, and computational studies

The electronic properties of four divinylanthracene-bridged diruthenium carbonyl complexes [{RuCl(CO)(PMe3)3}2(μ[BOND]CH[DOUBLE BOND]CHArCH[DOUBLE BOND]CH)] (Ar=9,10-anthracene (1), 1,5-anthracene (2), 2,6-anthracene (3), 1,8-anthracene (4)) obtained by molecular spectroscopic methods (IR, UV/Vis/near-IR, and EPR spectroscopy) and DFT calculations are reported. IR spectroelectrochemical studies have revealed that these complexes are first oxidized at the noninnocent bridging ligand, which is in line with the very small ν(C[TRIPLE BOND]O) wavenumber shift that accompanies this process and also supported by DFT calculations. Because of poor conjugation in complex 1, except oxidized 1+, the electronic absorption spectra of complexes 2+, 3+, and 4+ all display the characteristic near-IR band envelopes that have been deconvoluted into three Gaussian sub-bands. Two of the sub-bands belong mainly to metal-to-ligand charge-transfer (MLCT) transitions according to results from time-dependent DFT calculations. EPR spectroscopy of chemically generated 1+–4+ proves largely ligand-centered spin density, again in accordance with IR spectra and DFT calculations results.

Secondary school teachers' perspectives on teaching about topics that bridge science and religion

The question of where to locate teaching about the relationships between science and religion has produced a long-running debate. Currently, Science and Religious Education (RE) are statutory subjects in England and are taught in secondary schools by different teachers. This paper reports on an interview study in which 16 teachers gave their perceptions of their roles and responsibilities when teaching topics that bridge science and religion and the extent to which they collaborated with teachers in the other subject area. We found that in this sample, teachers reported very little collaboration between the curriculum areas. Although the science curriculum makes no mention of religion, all the science teachers said that their approaches to such topics were affected by their recognition that some pupils hold religious beliefs. All the RE teachers reported struggling to ensure students know of a range of views about how science and religion relate. The paper concludes with a discussion about implications for curriculum design and teacher training.

Tystnaden i ljudfilm : En studie i Jacques Tatis ”Mon Uncle”

Hellström, Staffan. Tystnaden i ljudfilm - En studie i Jacques Tatis ”Mon Uncle”. C-uppsats. Falun: Institutionen för kultur & medier, Högskolan Dalarna. HT-2008Denna uppsats undersöker Jacques Tatis användning av tystnaden i samspel med ljud och hur de komiska situationerna uppkommer genom detta. Dess syfte är att öka kunskapen för ljudläggare hur man kan använda tystnaden i samverkan med ljud för att uppnå önskat resultat. Den har även som syfte att visa hur specifikt Jacques Tati åstadkommer detta. Uppsatsen innehåller en kvalitativ närläsning, analys och personlig tolkning av fyra scener ur Tatis film ”Mon Uncle” från 1958. Undersökningen är genomförd med ett hermeneutiskt synsätt. Tystnaden definieras som något som endast kan förekomma när ljud existerar.Utredningen genomförs med teoretiskt stöd av Bela Balázs teorier om ljud i film samt Robert Bressons anteckningar om filmkonsten. Bressons filmer är väldigt liknande Tatis filmer på det tekniska planet och är därför relevanta för jämförelser.Sammanfattningsvis kan det sägas att Tati ljudmässigt skapar sina komiska situationer genom ett samspel mellan ljud, tystnad och ett repeterande av monotona ljud. I likhet med Bresson är han intresserad att lyfta fram det osedda och göra oss uppmärksamma på tystnaden.

Being a bridge : Swedish antenatal care midwives’ encounters with Somali-born women and questions of violence; a qualitative study

Background: Violence against women is associated with serious health problems, including adverse maternal and child health. Antenatal care (ANC) midwives are increasingly expected to implement the routine of identifying exposure to violence. An increase of Somali born refugee women in Sweden, their reported adverse childbearing health and possible links to violence pose a challenge to the Swedish maternity health care system. Thus, the aim was to explore ways ANC midwives in Sweden work with Somali born women and the questions of exposure to violence. Methods: Qualitative individual interviews with 17 midwives working with Somali-born women in nine ANC clinics in Sweden were analyzed using thematic analysis. Results: The midwives strived to focus on the individual woman beyond ethnicity and cultural differences. In relation to the Somali born women, they navigated between different definitions of violence, ways of handling adversities in life and social contexts, guided by experience based knowledge and collegial support. Seldom was ongoing violence encountered. The Somali-born women’s’ strengths and contentment were highlighted, however, language skills were considered central for a Somali-born woman’s access to rights and support in the Swedish society. Shared language, trustful relationships, patience, and networking were important aspects in the work with violence among Somali-born women. Conclusion: Focus on the individual woman and skills in inter-cultural communication increases possibilities of overcoming social distances. This enhances midwives’ ability to identify Somali born woman’s resources and needs regarding violence disclosure and support. Although routine use of professional interpretation is implemented, it might not fully provide nuances and social safety needed for violence disclosure. Thus, patience and trusting relationships are fundamental in work with violence among Somali born women. In collaboration with social networks and other health care and social work professions, the midwife can be a bridge and contribute to increased awareness of rights and support for Somali-born women in a new society.

Provenance: The Bridge Between Experiments and Data

Current scientific applications are often structured as workflows and rely on workflow systems to compile abstract experiment designs into enactable workflows that utilise the best available resources. The automation of this step and of the workflow enactment, hides the details of how results have been produced. Knowing how compilation and enactment occurred allows results to be reconnected with the experiment design. We investigate how provenance helps scientists to connect their results with the actual execution that took place, their original experiment and its inputs and parameters.

Des mots, des figures, des personnages : une étude de quelques aspects de paroles de Jacques Prévert

A presente dissertação tem por objetivo estudar alguns aspectos de Paroles, conjunto de poemas de Jacques Prévert (1900-1977). Ela começa com um primeiro capítulo de introdução à retórica: uma breve história da retórica ou de seu lugar na sociedade ocidental, em seguida uma apresentação do sistema retórico. O segundo capítulo estuda a trajetória da vida e da escrita de Jacques Prévert até a publicação de Paroles. O terceiro capítulo estuda alguns aspectos de Paroles. Ele começa por perguntar qual o tipo de linguagem utilizada por Prévert: ela é tão simples e popular quanto parece? Depois, ele se debruça sobre a questão do jogo de palavras. Em seguida ele tenta fazer um levantamento bastante completo, um inventário das figuras de retórica presentes em Paroles. Para evitar que a leitura do capítulo se tornasse excessivamente pesada e indigesta, foi organizado um anexo que recebeu todo o inventário quantitativo; ele se encontra após o texto propriamente dito da dissertação. Enfim, o capítulo apresenta algumas considerações de ordem temática, sobre a questão da população: quais espécies de personagens povoam Paroles? Um breve léxico dos principais termos da retórica se encontra no fim da dissertação, antes da bibliografia.

Os fundamentos do consenso prático em Jacques Maritain : a construção do consenso, a lei natural, o conhecimento por intuição e a caridade

Um rol de Direitos Fundamentais é ficção, como afirma MacIntyre ou MacInerny. Jacques Maritain estabelece uma resposta crítica a estes autores construindo uma fundamentação por meio de um “consenso prático”. O que gera este consenso entre pessoas de concepções de vida diferentes? Para Jacques Maritain o consenso é estabelecido pela Lei Natural, o Conhecimento por Intuição e a Caridade. A presente dissertação aborda estes elementos, mostrando que Jacques Maritain busca-os em Santo Tomás de Aquino, completando o sentido destes conceitos e incorporando-os na Modernidade, como, por exemplo, a dignidade da pessoa humana.