Determining vibration signature of a defective planet bearing in a wind turbine epicyclic gearbox

Planet bearings of wind turbine epicyclic gearboxes are considered as one of the most critical components due to their high failure rate. In order to develop effective vibration based detection algorithms for these bearings, a thorough understanding of their vibration signature is required. In this paper, we investigate the vibration behaviour of an epicyclic gearbox in the presence of a defective planet bearing both theoretically and experimentally. We also identify different sources of modulation sidebands using an analytical model which includes ring gear flexibility and planet bearing defects. The findings from this work will help engineers to develop more effective fault detection algorithms.

Effects of Cu-Wire Surface Fluctuations on Early Failures

Different chemical mechanical polishing （CMP） slurries are used to obtain single-damascene Cu-wires with different surface fluctuations as well as pre-existing surface-defects in wires with rougher surfaces. The presence of such pre-existing defects strongly increases the rate of early failures to almost 100%, reduces electromigration lifetime rapidly to the level of early failures, and changes the multimodal failure distribution into monomodal. The activation energy （0. 74±0.02eV） for the failure mechanism associated with these pre-existing defects confirms a dominant surface diffusion. It shows how a weakest link approximation analysis can he applied to a single wire by dividing the wire into relevant segments and assigning different failure mechanisms to the various segments. The analysis confirms that, although surface-defects are not the fastest early failure mechanism, the ten times higher surface-defectdensity in the rougher wires is responsible for the observed high early-failure rate and unreliable performance.

具有随机机器故障的制造过程建模与性能分析

为研究机器故障和维修活动对制造过程性能的影响,提出一种基于广义随机Petri网的制造过程建模与性能分析方法。分析了随机机器故障特征;定义了两种故障发现模式和两种中断作业处理策略;给出具有随机机器故障的制造过程的不同模型方法;通过对模型结构特征的分析,证明了其有效性。针对不同策略和参数设置进行了性能仿真。分别以平均产量和平均过程流时间等性能指标,分析了单个工作站的性能;采用平均产量,分析了具有两个工作站的流水线的性能。仿真结果表明,故障率、平均维修时间、缓存数量配置、维修工人数量、故障发现模式和中断作业处理策略是影响具有随机机器故障的制造过程性能的主要因素。

高可靠性红外车辆分离器设计与应用

本文给出了一种针对公路自动收费系统的车辆分离检测而设计的,利用红外线发射和接收所形成的光幕,完全消除跟车现象,并能将半挂车、全挂车、单车可靠分离的红外车辆分离器。高可靠性红外车辆分离器的设计很好克服了传统红外车辆分离器环境适应性差、故障率高等缺点。本文还介绍了光幕形成的基本原理,并阐述了硬件关键点及实现方法,给出了系统硬件原理图、软件基本设计思想。

A critical realist examination of the inhibitors of double loop learning in an agile adoption

The original solution to the high failure rate of software development projects was the imposition of an engineering approach to software development, with processes aimed at providing a repeatable structure to maintain a consistency in the ‘production process’. Despite these attempts at addressing the crisis in software development, others have argued that the rigid processes of an engineering approach did not provide the solution. The Agile approach to software development strives to change how software is developed. It does this primarily by relying on empowered teams of developers who are trusted to manage the necessary tasks, and who accept that change is a necessary part of a development project. The use of, and interest in, Agile methods in software development projects has expanded greatly, yet this has been predominantly practitioner driven. There is a paucity of scientific research on Agile methods and how they are adopted and managed. This study aims at addressing this paucity by examining the adoption of Agile through a theoretical lens. The lens used in this research is that of double loop learning theory. The behaviours required in an Agile team are the same behaviours required in double loop learning; therefore, a transition to double loop learning is required for a successful Agile adoption. The theory of triple loop learning highlights that power factors (or power mechanisms in this research) can inhibit the attainment of double loop learning. This study identifies the negative behaviours - potential power mechanisms - that can inhibit the double loop learning inherent in an Agile adoption, to determine how the Agile processes and behaviours can create these power mechanisms, and how these power mechanisms impact on double loop learning and the Agile adoption. This is a critical realist study, which acknowledges that the real world is a complex one, hierarchically structured into layers. An a priori framework is created to represent these layers, which are categorised as: the Agile context, the power mechanisms, and double loop learning. The aim of the framework is to explain how the Agile processes and behaviours, through the teams of developers and project managers, can ultimately impact on the double loop learning behaviours required in an Agile adoption. Four case studies provide further refinement to the framework, with changes required due to observations which were often different to what existing literature would have predicted. The study concludes by explaining how the teams of developers, the individual developers, and the project managers, working with the Agile processes and required behaviours, can inhibit the double loop learning required in an Agile adoption. A solution is then proposed to mitigate these negative impacts. Additionally, two new research processes are introduced to add to the Information Systems research toolkit.

Outcomes After Total Ankle Replacement in Association With Ipsilateral Hindfoot Arthrodesis.

BACKGROUND: Ipsilateral hindfoot arthrodesis in combination with total ankle replacement (TAR) may diminish functional outcome and prosthesis survivorship compared to isolated TAR. We compared the outcome of isolated TAR to outcomes of TAR with ipsilateral hindfoot arthrodesis. METHODS: In a consecutive series of 404 primary TARs in 396 patients, 70 patients (17.3%) had a hindfoot fusion before, after, or at the time of TAR; the majority had either an isolated subtalar arthrodesis (n = 43, 62%) or triple arthrodesis (n = 15, 21%). The remaining 334 isolated TARs served as the control group. Mean patient follow-up was 3.2 years (range, 24-72 months). RESULTS: The SF-36 total, AOFAS Hindfoot-Ankle pain subscale, Foot and Ankle Disability Index, and Short Musculoskeletal Function Assessment scores were significantly improved from preoperative measures, with no significant differences between the hindfoot arthrodesis and control groups. The AOFAS Hindfoot-Ankle total, function, and alignment scores were significantly improved for both groups, albeit the control group demonstrated significantly higher scores in all 3 scales. Furthermore, the control group demonstrated a significantly greater improvement in VAS pain score compared to the hindfoot arthrodesis group. Walking speed, sit-to-stand time, and 4-square step test time were significantly improved for both groups at each postoperative time point; however, the hindfoot arthrodesis group completed these tests significantly slower than the control group. There was no significant difference in terms of talar component subsidence between the fusion (2.6 mm) and control groups (2.0 mm). The failure rate in the hindfoot fusion group (10.0%) was significantly higher than that in the control group (2.4%; p < 0.05). CONCLUSION: To our knowledge, this study represents the first series evaluating the clinical outcome of TARs performed with and without hindfoot fusion using implants available in the United States. At follow-up of 3.2 years, TAR performed with ipsilateral hindfoot arthrodesis resulted in significant improvements in pain and functional outcome; in contrast to prior studies, however, overall outcome was inferior to that of isolated TAR. LEVEL OF EVIDENCE: Level II, prospective comparative series.

An analysis of the passenger to cabin crew ratio and exit reliability based on past survivable aviation accidents

A hotly debated issue in the area of aviation safety is the number of cabin crew members required to evacuate an aircraft in the event of an emergency. Most countries regulate the minimum number required for the safe operation of an aircraft, but these rulings are based on little if any scientific evidence. Another issue of concern is the failure rate of exits and slides. This paper examines these issues using the latest version of Aircraft Accident Statistics and Knowledge database AASK V4.0, which contains information from 105 survivable crashes and more than 2,000 survivors, including accounts from 155 cabin crew members.

Multicamera sport player tracking with Bayesian estimation of measurements

We propose a complete application capable of tracking multiple objects in an environment monitored by multiple cameras. The system has been specially developed to be applied to sport games, and it has been evaluated in a real association-football stadium. Each target is tracked using a local importance-sampling particle filter in each camera, but the final estimation is made by combining information from the other cameras using a modified unscented Kalman filter algorithm. Multicamera integration enables us to compensate for bad measurements or occlusions in some cameras thanks to the other views it offers. The final algorithm results in a more accurate system with a lower failure rate. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3114605]

Long-Term Follow-Up of a Large Active Surveillance Cohort of Patients With Prostate Cancer

PURPOSE: Active surveillance is increasingly accepted as a treatment option for favorable-risk prostate cancer. Long-term follow-up has been lacking. In this study, we report the long-term outcome of a large active surveillance protocol in men with favorable-risk prostate cancer.

PATIENTS AND METHODS: In a prospective single-arm cohort study carried out at a single academic health sciences center, 993 men with favorable- or intermediate-risk prostate cancer were managed with an initial expectant approach. Intervention was offered for a prostate-specific antigen (PSA) doubling time of less than 3 years, Gleason score progression, or unequivocal clinical progression. Main outcome measures were overall and disease-specific survival, rate of treatment, and PSA failure rate in the treated patients.

RESULTS: Among the 819 survivors, the median follow-up time from the first biopsy is 6.4 years (range, 0.2 to 19.8 years). One hundred forty-nine (15%) of 993 patients died, and 844 patients are alive (censored rate, 85.0%). There were 15 deaths (1.5%) from prostate cancer. The 10- and 15-year actuarial cause-specific survival rates were 98.1% and 94.3%, respectively. An additional 13 patients (1.3%) developed metastatic disease and are alive with confirmed metastases (n = 9) or have died of other causes (n = 4). At 5, 10, and 15 years, 75.7%, 63.5%, and 55.0% of patients remained untreated and on surveillance. The cumulative hazard ratio for nonprostate-to-prostate cancer mortality was 9.2:1.

CONCLUSION: Active surveillance for favorable-risk prostate cancer is feasible and seems safe in the 15-year time frame. In our cohort, 2.8% of patients have developed metastatic disease, and 1.5% have died of prostate cancer. This mortality rate is consistent with expected mortality in favorable-risk patients managed with initial definitive intervention.

Holding Shareholders to Account: British Banking Stability and Contingent Capital

This chapter seeks to explain the relative stability of the British banking system in terms of its capital structure. From 1826 joint-stock banking was allowed, but shareholder liability was jointly and severally unlimited. Limited liability banks were allowed from 1857–8, but these banks issued partly paid shares with an obligation on shareholders to subscribe for uncalled capital. Contingent capital meant that shareholders and managers would suffer losses in the event of failure and this discouraged risk shifting at the expense of note-holders and depositors. Although individual banks collapsed, the failure rate of banks (in terms of number or capital) did not reach a critical level—10 per cent—beyond which the payments system might have been threatened. This chapter argues that agency problems and systemic risk rose after the abolition of contingent share capital in 1958 and the deregulation of the banking sector in the 1970s.

Insucesso escolar: causas e consequências no contexto do Agrupamento Vertical de Ourique (período 1999/2000 a 2007/2008)

O presente estudo, de carácter quantitativo e qualitativo, assenta na temática do insucesso escolar. O mesmo foi orientado pela questão de partida que o perspectivou: “Quais as causas, consequências e dimensão do fenómeno do insucesso escolar nos alunos que iniciaram, em 1999/2000, a sua escolaridade, no concelho de Ourique? Baseados no quadro conceptual de um estudo de caso, seleccionámos uma “coorte” de alunos, que entrevistámos, com vista a inteirarmo-nos das experiências e situações reais que os conduziram a situações de insucesso escolar procurando dar resposta aos seguintes objectivos: 1) avaliar, quantitativamente, o insucesso escolar na população discente seleccionada; 2) identificar as, eventuais, causas do insucesso escolar verificado; 3) identificar as, eventuais, consequências do insucesso escolar verificado; 4) avaliar possíveis intervenções no sentido de mitigar o fenómeno do insucesso escolar. Para tal, analisámos o percurso escolar de um universo de 46 alunos, entre 1999/2000 e 2007/08, tendo verificado que 24 desses alunos vivenciaram episódios de insucesso escolar, ao longo do seu trajecto académico. Destes, entrevistámos 12 alunos, tendo essa abordagem possibilitado ir de encontro aos nossos objectivos. Através da análise e interpretação dos dados recolhidos, concluímos que: 1) a taxa de insucesso escolar é superior a 50%, na coorte de alunos que iniciaram a sua escolaridade, no ano lectivo 1999/00, no concelho de Ourique; 2) há uma forte participação dos pais e encarregados de educação nas vivências escolares dos alunos (80% do total da amostra); 3) o número médio de retenções, nos alunos com episódios de insucesso escolar, é de 1,5 retenções; 4) o 7.º ano de escolaridade é o ano em que se verifica um maior número de retenções, seguido do 4.º ano de escolaridade; 5) a maioria dos alunos (58,3%) encontra-se relativamente distante do seu meio familiar; 6) um número significativo de alunos com episódios de insucesso escolar (83,3%) referiu que recebe apoio da família; 7) a incapacidade individual foi a causa do insucesso escolar mais referida/inferida pelos entrevistados; 8) evidenciou-se que retenções precoces induzem a retenções posteriores; 9) a importância do 1.º Ciclo é relevante, quando os entrevistados indicam que a falta de apoio no 1.º Ciclo terá induzido a situações futuras de insucesso escolar. No final deste trabalho são efectuadas propostas que possam potenciar futuras investigações, nomeadamente de investigação acção, promovendo intervenção; ### Abstract: The schools failure: The causes of consequences in context the Agrupamento Vertical de Ourique The present study, of quantitative and qualitative content, is based on the thematic of the failure rate in schools. The study was oriented towards the fundamental issue which has been put in perspective: “What are the causes, consequences and dimension of the phenomena of the failure rate in schools that can be seen in the students that started in 1999/2000 their school education in the municipality of Ourique?” Based on the conceptual framework of a study case, we selected a group of students, which we interviewed, in order to know about the real experiences and situations that led them to situations of school failure, trying to give answers and to achieve the following goals: 1) to evaluate quantitatively the school failure of the selected students population; 2) to identify the eventual causes of the verified school failure; 3) to identify the eventual consequences of the verified school failure; 4) to evaluate the possible interventions in order to minimize the school failure phenomena. Therefore, we analysed the school path of an amount of 46 students between 1999/2000 and 2007/2008 and we reached the conclusion that 24 of those students experienced episodes of school failure. We interviewed 12 of those 24 and that approach permitted us to reach our goals. Through the analysis and the interpretation of the collected data we conclude that: 1) the rate of school failure is over 50% in the group of students that started their schooling in the school year 1999/2000 in the municipality of Ourique; 2) there is a strong participation of parents and tutors in the students’ school life( 80% of the sample); 3) the average number of retention in the students with episodes of school failure is 1, 5 retentions; 4) the 7th grade is the one in which we verify the highest number of retentions followed by the 4th grade ; 5) the majority of the students (53,8%) are far away from their family environment; 6) a significant number of students with episodes of school failure (83,3%) referred that they get support from their family; 7) the individual incapacity was the most referred/inferred cause of school failure by the ones who were interviewed ; 8) it became an evidence that early retentions lead to future retentions; 9) the importance of the basic education is relevant when the interviewed students show that the lack of support in the basic education should have led to future situations of school failure. At the end of this work we present some proposals that can lead to future investigation, namely of investigation/action promoting intervention.

Ofício: ser professora - do projeto educativo ao sucesso escolar

O Despacho n.º 40/2011, de 20 de maio, ponto 3., da Universidade de Évora, prevê a possibilidade de elaboração de um relatório sobre a atividade profissional para aquisição do grau académico de mestre. Essa foi a minha opção. Este relatório reporta-se aos anos letivos de 2007/2012, correspondentes aos últimos cinco anos de trabalho. É uma reflexão sobre as medidas desenvolvidas no Agrupamento de Escolas de Alvalade, com vista a melhorar os níveis de sucesso escolar e a importância do projeto educativo para alcançar tal objetivo, apresentando ainda dados sobre o sucesso/insucesso. Enquanto diretora de um agrupamento de escolas cuja taxa de insucesso à data da tomada de posse rondava os 18%, abracei como objetivo principal, mobilizar toda a comunidade educativa, para reverter essa situação calamitosa. Após várias medidas implementadas, os resultados melhoraram para 5,98%, em 2011/2012. Muito trabalho foi feito e muitos projetos foram adotados; ABSTRACT: The University Dispatch n. º 40/2011 of may 20th, paragraph 3., University of Évora, provides for the possibility of drafting a report about my professional activity in order to acquire a master's degree. That was my choice. This report refers to the work that I have been developing in the last academic years of 2007/2012. It is a reflection on action in the Alvalade Group of Schools, about the measures that were implemented to improve levels of educational attainment and educational importance of the project to achieve this goal, presenting, nevertheless, data on the success/failure. When I became director of a group of schools, which failure rate at the date of inauguration was around 18%, I decided to delineate as my main goal, to mobilize the entire educational community, to reverse this calamitous situation. After several measures implemented, the students’ failure decreased up to 5,98% in 2011/2012. Much work has been done and many projects were adopted.

O desenvolvimento do raciocínio dedutivo ao nível do ensino secundário : recurso a geometrias planas

Este trabalho, no âmbito da Didáctica da Matemática, foca-se no estudo de abordagens alternativas de ensino e aprendizagem da Geometria Euclidiana, no Ensino Secundário, no sentido de promover níveis estruturados do pensamento matemático. Em particular, as potencialidades do recurso a outros modelos de Geometria Plana (e.g. Geometria Hiperbólica, Geometria do Motorista de Táxi) em relação a este problema serão investigadas. A opção pelo Ensino Secundário deve-se ao facto de se tratar de um nível de ensino onde se regista uma elevada taxa de insucesso escolar (especialmente no 10º ano) e onde é notório o abismo existente, entre o ensino Secundário e Universitário, no âmbito do raciocínio lógico - dedutivo. O trabalho a desenvolver pretende aprofundar o estudo de questões ligadas à natureza do conhecimento envolvido que estarão na base de decisões, tais como: Quais os processos que vão ser ensinados? Que processos queremos que os alunos dominem? E, por outro lado, ter em conta que se pretende desenvolver capacidades de ordem superior, significando que o ensino da Matemática deve dirigir-se para níveis elevados de pensamento, tais como: resolução de problemas; comunicar matematicamente; raciocínio e demonstração. No currículo de matemática para o Ensino Básico e Secundário tem-se negligenciado a demonstração matemática, contribuindo para que exista uma desconformidade entre os graus de ensino, secundário e universitário. Muitas vezes as abordagens de ensino centram-se na verificação de resultados e desvalorizam a exploração e explicação (Villiers, 1998). Actualmente, assiste-se a uma tendência para retomar o raciocínio lógico - dedutivo. O principal objectivo desta investigação é analisar ambientes de aprendizagem em que os alunos sejam solicitados a resolver problemas de prova em contextos diversificados e, de uma forma mais geral promover o desenvolvimento do raciocínio dedutivo e uma visão mais alargada do conhecimento matemático. Em particular, a abordagem de problemas de prova num contexto de geometria não Euclidiana, com recurso a artefactos e a software de geometria dinâmica, será investigada.

L’élaboration d’un programme d’Enseignement à distance par radio (EADR) pour l’amélioration des résultats d’examens officiels du baccalauréat 1ère partie en Haïti

Ce mémoire de maîtrise porte sur la contribution que pourrait apporter l’Enseignement à distance par radio (EADR) dans la réduction du taux d’échec aux examens du baccalauréat 1ère partie en Haïti. De manière spécifique, nous souhaitions élaborer un programme d’ « Enseignement à distance par radio » (EADR) afin d’aider l’ensemble des candidats bacheliers des classes de Rhéto à préparer les examens du bac 1ère partie. En Haïti, l’Enseignement à distance (EAD) est pratiquement absent. De nombreux pays ayant eu des situations similaires à Haïti ont mis en place des programmes de « Formations ouvertes et à distance » (FOAD) en complémentarité avec le mode d’enseignement classique ou en mode présentiel. La complexité de la situation exige d’envisager diverses pistes pour sortir le système éducatif haïtien de cette léthargie. Si l’on ne peut considérer l’EAD comme l’unique perspective, il est par contre pertinent et souhaitable de l’envisager comme une alternative non négligeable (Lubérisse, 2003). En nous appuyant sur les principales conditions d’efficacité des FOAD définies par Karsenti (2003), les principes théoriques de type R & D (Van der Maren, 2003?), le cadre théorique de la méthodologie de l’évaluation des besoins de Chagnon et Paquette (Institut universitaire des Centres Jeunesses de Montréal, 2005) et de Roegiers, Wouters & Gerard (1992), nous avons élaboré les grandes lignes générales de ce programme d’EADR et les avons soumises à douze (12) acteurs clés du système éducatif haïtien (4 élèves, 3 parents, 2 enseignants et 3 spécialistes de la radio ou de l’EADR). Cette ébauche de programme comportait principalement les objectifs du programme d’EADR, la méthode pédagogique, le contenu et les conditions de mise en œuvre. Des données recueillies par le biais d’entrevues individuelles il ressort que l’implantation d’un programme d’EADR peut être bénéfique au système éducatif haïtien, particulièrement sur les résultats d’examens officiels du baccalauréat 1ère partie. Les douze participants à notre recherche, croient que l’objectif poursuivi par le programme d’EADR est tout à fait réalisable et important pour le public cible. Tout en notant l’aspect positif du programme d’EADR proposé, les participants réclament certaines modifications quant à la méthode pédagogique, au contenu et aux conditions de mise en œuvre. Ainsi, les recommandations faites par les douze acteurs clés du système éducatif, jointes à notre recension nous ont permis d’élaborer un nouveau programme d’EADR revu et corrigé qui pourra servir de base à une évaluation plus large.

Fibrillation auriculaire et insuffisance cardiaque : une analyse de coût comparant la stratégie de contrôle de la fréquence à celle du contrôle du rythme

Contexte : La fibrillation auriculaire est commune chez les insuffisants cardiaques. L’efficacité des stratégies de contrôle de la fréquence et du rythme s’équivalent. Nous avons comparé l’impact économique des deux stratégies de traitement chez les patients avec fibrillation auriculaire et insuffisance cardiaque. Méthode : Dans cette sous-étude de l’essai Atrial Fibrillation and Congestive Heart Failure, la consommation de soins de santé des patients Québécois ainsi que leurs coûts ont été quantifiés grâce aux banques de données de la Régie de l’assurance-maladie du Québec et de l’Ontario Case Costing Initiative. Résultats : Trois cent quatre patients ont été inclus, âgés de 68±9 ans, fraction d’éjection de 26±6%. Les caractéristiques de base étaient bien réparties entre le contrôle du rythme (N=149) et de la fréquence (N=155). Les patients soumis au contrôle de la fréquence ont eu moins de procédures cardiovasculaires (146 versus 238, P<0.001) en raison du plus faible nombre de cardioversions et de moindres coûts reliés aux antiarythmiques (48 $±203 versus 1319 $±1058 par patient, P<0.001). Ces différences ont été compensées par un surplus de dépenses dues aux hospitalisations non-cardiovasculaires, aux dispositifs cardiaques implantables et aux médicaments non-cardiovasculaires dans le groupe du contrôle de la fréquence. Au total, les coûts par patient avec les stratégies du contrôle de la fréquence et du rythme s’élèvent à 78 767 $±79 568 et 72 764 $±72 800 (P=0.49). Interprétation : Chez les patients avec fibrillation auriculaire et insuffisance cardiaque, le contrôle de la fréquence est associé avec moins de procédures cardiovasculaires et une pharmacothérapie cardiovasculaire moins coûteuse. Toutefois, les coûts associés aux arythmies représentent moins de la moitié des dépenses de santé et le total des coûts s’équilibre entre les 2 stratégies.