842 resultados para performance-based engineering
Resumo:
Exergy analysis is applied to assess the energy conversion processes that take place in the human body, aiming at developing indicators of health and performance based on the concepts of exergy destroyed rate and exergy efficiency. The thermal behavior of the human body is simulated by a model composed of 15 cylinders with elliptical cross section representing: head, neck, trunk, arms, forearms, hands, thighs, legs, and feet. For each, a combination of tissues is considered. The energy equation is solved for each cylinder, being possible to obtain transitory response from the body due to a variation in environmental conditions. With this model, it is possible to obtain heat and mass flow rates to the environment due to radiation, convection, evaporation and respiration. The exergy balances provide the exergy variation due to heat and mass exchange over the body, and the exergy variation over time for each compartments tissue and blood, the sum of which leads to the total variation of the body. Results indicate that exergy destroyed and exergy efficiency decrease over lifespan and the human body is more efficient and destroys less exergy in lower relative humidities and higher temperatures. (C) 2012 Elsevier Ltd. All rights reserved.
Resumo:
Background: We aimed to investigate the effect of rest interval, between successive contractions, on muscular fatigue. Methods: Eighteen subjects performed elbow flexion and extension (30 repetitions) on an isokinetic dynamometer with 80 degrees of range of motion. The flexion velocity was 120 degrees/s, while for elbow extension we used 5 different velocities (30, 75, 120, 240, 360 degrees/s), producing 5 different rest intervals (2.89, 1.28, 0.85, 0.57 and 0.54 s). Results: We observed that when the rest interval was 2.89 s there was a reduction in fatigue. On the other hand, when the rest interval was 0.54 s the fatigue was increased. Conclusions: When the resting time was lower (0.54 s) the decline of work in the flexor muscle group was higher compared with different rest interval duration.
Resumo:
Ziel war die Entwicklung und Erprobung von Varianten des emotionalen Strooptests zur Analyse angstbezogener Aufmerksamkeitsprozesse bei Grundschulkindern. Dabei wurde überprüft, ob dieses kognitiv-experimentelle Verfahren zukünftig als objektives Testverfahren zur Diagnostik von Ängstlichkeit im Kindesalter geeignet ist. Ausgangspunkt waren zahlreiche Befunde für die Gruppe Erwachsener, wonach die Zuwendung auf bedrohliche Situationsmerkmalen für Ängstliche charakteristisch ist. Für das Kindesalter liegen hierzu nur wenige Studien mit zudem inkonsistenten Befundmuster vor. In insgesamt drei Studien wurde der emotionale Strooptest für das Grundschulalter adaptiert, indem Bilder bzw. altersentsprechendes Wortmaterial als Stimuli eingesetzt wurden. An den Studien nahmen nicht-klinische, nicht-ausgelesene Stichproben mit Kindern der zweiten bis vierten Grundschulklassen teil. Sowohl Ängstlichkeit als auch Zustandsangst der Kinder wurden jeweils über Selbst- und Fremdeinschätzungen (Eltern, Klassenlehrer, Versuchsleiter) erhoben. Die Ergebnisse sprechen für eine nur unzureichende Reliabilität emotionaler Interferenzeffekte. Auch ergaben sich (möglichenfalls infolge) keine substantiellen Hinweise auf differentielle angstbezogene Interferenzeffekte. Die Befunde sprechen vielmehr dafür, dass alle Kinder unabhängig von der Ängstlichkeit höhere Benennungszeiten für bedrohliche Stimuli im Vergleich zur Kontrollbedingung mit neutralen oder freundlichen Stimuli zeigten, wobei zugleich methodische Einflussfaktoren des Strooptests von Relevanz waren. Die Diskussion konzentriert sich auf entwicklungspsychologische Überlegungen sowie mögliche Bedingungen emotionaler Interferenzeffekte unter kritischer Berücksichtigung der Reliabilität emotionaler Stroopinterferenz.
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Nella presente tesi è stato esaminato il comportamento di un sistema di dissipazione isteretica denominato CSB, costituito da un elemento metallico realizzato partendo da profili di tipo standard, la cui peculiarità consiste nella particolare forma geometrica a boomerang che consente di dimensionare la rigidezza laterale e la forza di snervamento in maniera indipendente. I CSB posso essere utilizzati sia come alternativa ai controventi diagonali tradizionali, sia come sistema resistente alle azioni orizzontali dimensionato per ottenere un comportamento di soft-storey “controllato” (cosiddetto isolamento di piano) nell’ambito della progettazione di tipo PBSD (Performance Based Seismic Design). Il comportamento del dispositivo CSB è stato studiato dapprima attraverso una prima campagna sperimentale che è stata poi validata con l’utilizzo di modelli analitici e numerici.
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A partire dalle caratteristiche chiave dell’inquinamento acustico, lo scopo della tesi è stato quello di valutare quantitativamente l’entità del rumore aeronautico prodotto dall'aeroporto Marconi e di analizzare le soluzioni tecniche e gestionali disponibili per definire misure adeguate alle caratteristiche infrastrutturali e operative dello scalo e capaci di mitigare il disturbo subito dalla popolazione. Si è tenuto conto delle profonde modificazioni in atto nel mondo dell’aviazione, il quale, avendo come obiettivo quello di fornire un servizio di trasporto sempre più sostenibile, efficace, competitivo e omogeneo sul territorio europeo, sollecita profonde innovazioni nei requisiti funzionali e tecnici. Inizialmente l’attenzione è stata rivolta alla descrizione del rumore aeronautico e del contesto in cui è inserito, soffermandosi sul concetto di sostenibilità di un’infrastruttura di trasporto. Si è proseguito con un'analisi dettagliata della normativa vigente, italiana ed europea, al fine di affrontare gli aspetti legislativi del problema e di delineare le line guida per la valutazione del rumore. Segue uno studio, dal punto di vista tecnico e infrastrutturale, dell’evoluzione della navigazione aerea e del concetto innovativo di performance based navigation, focalizzando l’interesse sul curved approach, procedura di avvicinamento non convenzionale. L'attenzione è stata, poi, dedicata alla descrizione del caso di studio e alla presentazione della metodologia usata. Mediante il supporto dell’INM, sono state determinate le curve isofoniche, quantificando la popolazione esposta a specifici livelli di rumore aeronautico per lo scenario consuntivo dell’anno 2015. Infine, sono state eseguite simulazioni future, sulla base delle previsioni di crescita del volume di traffico aereo, per definire un limite massimo per lo sfruttamento del sistema ILS in testata 30 e per valutare il beneficio generato dall’introduzione del curved approach.
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Reducing Emissions from Deforestation and Forest Degradation and enhancing forest carbon stocks (REDD+) is a performance-based payment mechanism currently being debated in international and national environmental policy and planning forums. As the mechanism is based on conditionality, payments must reflect land stewards’ level of compliance with carbon-efficient management practices. However, lack of clarity in land governance and carbon rights could undermine REDD+ implementation. Strategies are needed to avoid perverse incentives resulting from the commoditization of forest carbon stocks and, importantly, to identify and secure the rights of legitimate recipients of future REDD+ payments. We propose a landscape-level approach to address potential conflicts related to carbon tenure and REDD+ benefit sharing. We explore various land-tenure scenarios and their implications for carbon ownership in the context of a research site in northern Laos. Our case study shows that a combination of relevant scientific tools, knowledge, and participatory approaches can help avoid the marginalization of rural communities during the REDD+ process. The findings demonstrate that participatory land-use planning is an important step in ensuring that local communities are engaged in negotiating REDD+ schemes and that such negotiations are transparent. Local participation and agreements on land-use plans could provide a sound basis for developing efficient measurement, reporting, and verification systems for REDD+.
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En la práctica habitual, para la elaboración de morteros se recomienda la utilización de granulometrías continuas. El requisito de continuidad y que los tamaños de partícula se encuentren dentro de los límites establecidos por “husos granulométricos” surge de las teorías clásicas de Fuller – Thompson y se apoya en la necesidad de obtener mezclas con adecuada docilidad en el estado fresco. Sin embargo, las distribuciones continuas de árido no representan las únicas alternativas para obtener mezclas que tengan una adecuada docilidad en estado fresco y mediante nuevos criterios de interferencia de partículas es posible demostrar que las distribuciones discontinuas aun siendo más compactas y con menor requerimientos de volumen de pasta pueden ser igual de dóciles en estado fresco. Aunque el volumen mínimo de pasta está condicionado por su fluidez y viscosidad estos parámetros pueden modificarse mediante la incorporación de filler de distinta naturaleza y aditivos químicos de reciente desarrollo. En consecuencia, se propone analizar la posibilidad de minimizar el contenido de pasta de morteros de base cemento, manteniendo las prestaciones en el estado fresco, con el objetivo de obtener una mejor estabilidad volumétrica, posibilitando mejor control de la retracción y de la fisuración. Para ello se emplearán criterios de interferencia de partículas, combinados con el uso de filler de distinta naturaleza La reducción del contenido de pasta conducirá también a mejorar el perfil sostenible de los morteros. El proceso de optimización tiene una base racional y, por lo tanto, será aplicable a distintos tipos de mortero, y las proporciones óptimas podrán adecuarse según las prestaciones requeridas para el material. SUMMARY In common practice, continuous sand gradings are recommended to produce ordinary mortars. This requirement, along with grading limits are based on classical theories, such as Fuller, aimed at achieving a reasonable packing density without compromising workability at the fresh state. Nevertheless, there are other alternatives, such as discontinuous curves based on particle interference criteria, which are capable of having even higher packing density. The less the content of voids in the granular skeleton, the less the amount of cement paste required to fill in these voids and coating the particles. Yet, the minimum volume of paste in a mortar is determined by requirements associated to the fresh state and thus, fluidity and viscosity of the paste play a significant role on the matter. These two properties can be modified by the use of suitable fillers and by the use of last-generation chemical admixtures. As a result, it is proposed to analyse the possibility of combining current particle interference criteria with the use of different types of filler and chemical admixtures to optimise cement-based mortar formulations. This optimisation is aimed at reducing the paste content while maintaining a suitable performance at the fresh state. The reduction in paste content would lead to a better dimensional stability, with better control of shrinkage and cracking behaviour. The foreseen optimisation process will have a strong rational basis and thus, it should be potentially useful to optimise mortar proportions according to a performance-based approach.
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A Kuhnian approach to research assessment requires us to consider that the important scientific breakthroughs that drive scientific progress are infrequent and that the progress of science does not depend on normal research. Consequently, indicators of research performance based on the total number of papers do not accurately measure scientific progress. Similarly, those universities with the best reputations in terms of scientific progress differ widely from other universities in terms of the scale of investments made in research and in the higher concentrations of outstanding scientists present, but less so in terms of the total number of papers or citations. This study argues that indicators for the 1% high-citation tail of the citation distribution reveal the contribution of universities to the progress of science and provide quantifiable justification for the large investments in research made by elite research universities. In this tail, which follows a power low, the number of the less frequent and highly cited important breakthroughs can be predicted from the frequencies of papers in the upper part of the tail. This study quantifies the false impression of excellence produced by multinational papers, and by other types of papers that do not contribute to the progress of science. Many of these papers are concentrated in and dominate lists of highly cited papers, especially in lower-ranked universities. The h-index obscures the differences between higher- and lower-ranked universities because the proportion of h-core papers in the 1% high-citation tail is not proportional to the value of the h-index.
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Public Private Partnerships (PPPs) are mostly implemented for three reasons: to circumvent budgetary constraints, encourage efficiency and improvement of quality in the provision of public infrastructure. One of the ways of reaching the latter objective is by the introduction of performance-based standards tied to bonuses and penalties to reward or punish the performance of the contractor. These performance based standards often refer to different aspects such as technical, environmental and safety issues. This paper focuses on the implementation of safety based incentives in PPPs. The main aim of this paper is to analyze whether the incentives to improve road safety in PPPs are effective in improving safety ratios in Spain. To this end, negative binomial regression models have been applied using information from the Spanish high capacity network in 2006. The findings indicate that even though road safety is highly influenced by variables that are not much controllable by the contractor such as the Average Annual Daily Traffic and the percentage of heavy vehicles in the highway, the implementation of safety incentives in PPPs has a positive influence in the reduction of fatalities, injuries and accidents.
Resumo:
Process mineralogy provides the mineralogical information required by geometallurgists to address the inherent variation of geological data. The successful benefitiation of ores mostly depends on the ability of mineral processing to be efficiently adapted to the ore characteristics, being liberation one of the most relevant mineralogical parameters. The liberation characteristics of ores are intimately related to mineral texture. Therefore, the characterization of liberation necessarily requieres the identification and quantification of those textural features with a major bearing on mineral liberation. From this point of view grain size, bonding between mineral grains and intergrowth types are considered as the most influential textural attributes. While the quantification of grain size is a usual output of automated current technologies, information about grain boundaries and intergrowth types is usually descriptive and difficult to quantify to be included in the geometallurgical model. Aiming at the systematic and quantitative analysis of the intergrowth type within mineral particles, a new methodology based on digital image analysis has been developed. In this work, the ability of this methodology to achieve a more complete characterization of liberation is explored by the analysis of chalcopyrite in the rougher concentrate of the Kansanshi copper-gold mine (Zambia). Results obtained show that the method provides valuable textural information to achieve a better understanding of mineral behaviour during concentration processes. The potential of this method is enhanced by the fact that it provides data unavailable by current technologies. This opens up new perspectives on the quantitative analysis of mineral processing performance based on textural attributes.
Resumo:
Public Private Partnerships (PPPs) are mostly implemented for three reasons: to circumvent budgetary constraints, encourage efficiency and improvement of quality in the provision of public infrastructure. One of the ways of reaching the latter objective is by the introduction of performance-based standards tied to bonuses and penalties to reward or punish the performance of the contractor. These performance based standards often refer to different aspects such as technical, environmental and safety issues. This paper focuses on the implementation of safety based incentives in PPPs. The main aim of this paper is to analyze whether the incentives to improve road safety in PPPs are effective in improving safety ratios in Spain. To this end, negative binomial regression models have been applied using information from the Spanish high capacity network in 2006. The findings indicate that even though road safety is highly influenced by variables that are not much controllable by the contractor such as the Average Annual Daily Traffic and the percentage of heavy vehicles in the highway, the implementation of safety incentives in PPPs has a positive influence in the reduction of fatalities, injuries and accidents.
Resumo:
European Universities are involved in series of great changes regarding teaching and education organization during the last few years. The origin of these changes is the creation of the so-called European Higher Education Area (EHEA), which main target is to harmonize the different University studies throughout Europe. As a consequence, most of the programs of studies in all degrees are suffering changes in order to converge to common structures. Taking advantage of the actual process, some European universities are moving from traditional Agricultural Engineering programs to a more wide discipline named recently as Biosystems Engineering, which is a science- based engineering discipline that integrates engineering science and design with applied biological, environmental and agricultural sciences, broadening in this way the area of application of Engineering sciences not strictly to agricultural sciences, but to the biologic al sciences in general, including the agricultural sciences. This paper presents a comparative study of different Bachelor of Science degrees offered by American and European Universities in the field of Agricultural/Biosystems Engineering. To carry out the analysis 40 programs accredited by ABET in American Universities and 50 European programs. Among other questions, the total number of credits, the number of semesters, the kind of modules and the distribution of subjects in groups (Basic Sciences, Engineering Fundamentals, Agricultural/Biological Sciences, Humanities & Economic Sciences, Applied Agricultural/Biological Engineering and electives) are discussed in the paper. The information provided can be an useful starting point in future definitions of new or renewed degrees with the aim of advancing in internationalization of the programs and helping student’s mobility.
Resumo:
Building-integrated Photovoltaics (BIPV) is one of the most promising technologies enabling buildings to generate on-site part of their electricity needs while performing architectural functionalities. A clear example of BIPV products consists of semi-transparent photovoltaic modules (STPV), designed to replace the conventional glazing solutions in building façades. Accordingly, the active building envelope is required to perform multiple requirements such as provide solar shading to avoid overheating, supply solar gains and thermal insulation to reduce heat loads and improve daylight utilization. To date, various studies into STPV systems have focused on their energy performance based on existing simulation programs, or on the modelling, normally validated by limited experimental data, of the STPV modules thermal behaviour. Taking into account that very limited experimental research has been conducted on the energy performance of STPV elements and that the characterization in real operation conditions is necessary to promote an energetically efficient integration of this technology in the building envelope, an outdoor testing facility has been designed, developed and built at the Solar Energy Institute of the Technical University of Madrid. In this work, the methodology used in the definition of the testing facility, its capability and limitations are presented and discussed.
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La usabilidad es un atributo de calidad de un sistema software que llega a ser crítico en sistemas altamente interactivos. Desde el campo de la Interacción Persona-Ordenador se proponen recomendaciones que permiten alcanzar un nivel adecuado de usabilidad en un sistema. En la disciplina de la Ingeniería de Software se ha establecido que algunas de estas recomendaciones afectan a la funcionalidad principal de los sistemas y no solo a la interfaz de usuario. Este tipo de recomendaciones de usabilidad se deben tener en cuenta desde las primeras actividades y durante todo el proceso de desarrollo, así como se hace con atributos tales como la seguridad, la facilidad de mantenimiento o el rendimiento. Desde la Ingeniería de Software se han hecho estudios y propuestas para abordar la usabilidad en las primeras actividades del desarrollo. En particular en la educción de requisitos y diseño de la arquitectura. Estas propuestas son de un alto nivel de abstracción. En esta investigación se aborda la usabilidad en actividades avanzadas del proceso de desarrollo: el diseño detallado y la programación. El objetivo de este trabajo es obtener, formalizar y validar soluciones reutilizables para la usabilidad en estas actividades. En este estudio se seleccionan tres funcionalidades de usabilidad identificadas como de alto impacto en el diseño: Abortar Operación, Retroalimentación de Progreso y Preferencias. Para la obtención de elementos reutilizables se utiliza un método inductivo. Se parte de la construcción de aplicaciones web particulares y se induce una solución general. Durante la construcción de las aplicaciones se mantiene la trazabilidad de los elementos relacionados con cada funcionalidad de usabilidad. Al finalizar se realiza un análisis de elementos comunes, y los hallazgos se formalizan como patrones de diseño orientados a la implementación y patrones de programación en cada uno de los lenguajes utilizados: PHP, VB .NET y Java. Las soluciones formalizadas como patrones se validan usando la metodología de estudio de casos. Desarrolladores independientes utilizan los patrones para la inclusión de las tres funcionalidades de usabilidad en dos nuevas aplicaciones web. Como resultado, los desarrolladores pueden usar con éxito las soluciones propuestas para dos de las funcionalidades: Abortar Operación y Preferencias. La funcionalidad Retroalimentación de Progreso no puede ser implementada completamente. Se concluye que es posible obtener elementos reutilizables para la implementación de cada funcionalidad de usabilidad. Estos elementos incluyen: escenarios de aplicación, que son la combinación de casuísticas que generan las funcionalidades de usabilidad, responsabilidades comunes necesarias para cubrir los escenarios, componentes comunes para cumplir con las responsabilidades, elementos de diseño asociados a los componentes y el código que implementa el diseño. Formalizar las soluciones como patrones resulta útil para comunicar los hallazgos a otros desarrolladores y los patrones se mejoran a través de su utilización en nuevos desarrollos. La implementación de funcionalidades de usabilidad presenta características que condicionan su reutilización, en particular, el nivel de acoplamiento de la funcionalidad de usabilidad con las funcionalidades de la aplicación, y la complejidad interna de la solución. ABSTRACT Usability is a critical quality attribute of highly interactive software systems. The humancomputer interaction field proposes recommendations for achieving an acceptable system usability level. The discipline of software engineering has established that some of these recommendations affect not only the user interface but also the core system functionality. This type of usability recommendations must be taken into account as of the early activities and throughout the software development process as in the case of attributes like security, ease of maintenance or performance. Software engineering has conducted studies and put forward proposals for tackling usability in the early development activities, particularly requirements elicitation and architecture design. These proposals have a high level of abstraction. This research addresses usability in later activities of the development process: detailed design and programming. The goal of this research is to discover, specify and validate reusable usability solutions for detailed design and programming. Abort Operation, Feedback and Preferences, three usability functionalities identified as having a high impact on design, are selected for the study. An inductive method, whereby a general solution is induced from particular web applications built for the purpose, is used to discover reusable elements. During the construction of the applications, the traceability of the elements related to each usability functionality is maintained. At the end of the process, the common and possibly reusable elements are analysed. The findings are specified as implementation-oriented design patterns and programming patterns for each of the languages used: PHP, VB .NET and Java. The solutions specified as patterns are validated using the case study methodology. Independent developers use the patterns in order to build the three usability functionalities into two new web applications. As a result, the developers successfully use the proposed solutions for two of the functionalities: Abort Operation and Preferences. The Progress Feedback functionality cannot be fully implemented. We conclude that it is possible to discover reusable elements for implementing each usability functionality. These elements include: application scenarios, which are combinations of cases that generate usability functionalities, common responsibilities to cover the scenarios, common components to fulfil the responsibilities, design elements associated with the components and code implementing the design. It is useful to specify solutions as patterns in order to communicate findings to other developers, and patterns improve through further use in other development projects. Reusability depends on the features of usability functionality implementation, particularly the level of coupling of the usability functionality with the application functionalities and the internal complexity of the solution.
Resumo:
Este trabajo contiene el estudio de las tecnologías que se están usando actualmente en web, tratando de explicar cuáles son sus principales componentes, su objetivo y funcionamiento. En base a un supuesto teórico de un montaje para un servicio web con un número muy alto de usuarios, y basándose en las tecnologías estudiadas, se propone un posible montaje completo de un sistema, que sería capaz de gestionar correctamente todas las peticiones, evitando fallos y tiempos de indisponibilidad. Se a~nade un análisis teórico de los costes deribados de la implantación del sistema, comparándolo con un sistema web convencional, y otro análisis con el funcionamiento de una caché y los benéficos, en carga, derivados de su uso.---ABSTRACT---This work contains a study about new web technologies. Its objective is to explain the web technologies componentes with their particular usage and performance. Based on a theorical postulation about a preparation of a web service with a large number of users, and working with the studied technologies, a complete system assembling is proposed. This system will be able to attend all the incoming requests, without failures nor downtimes. It is attached a theorical study of the derivative costs associated to the system implementation, compared to a traditional one. In addition, another study is included with the work ow of a cache and the benefits derived of its usage in work terms.