1,720,961 research outputs found
Nova formulação analítica para especificação de torque de uniões aparafusadas considerando rosca métrica externa cônica e rosca interna paralela
Full text linkSpecifying and applying the correct tightening torque to achieve the required tightening force is essential for obtaining a reliable tensile bolted joint. In order to avoid failure of any component and/or self-loosening, the effective length of engagement between the threads plays a major role. The analytical procedures available for these applications concern the assembly of internal and external parallel threads. However, there is not analytical procedure for an external taper thread with an internal metric parallel thread. So, the present work develops an analytical procedure for calculating the length of engagement, the number of threads effective engaged, the percentage of the maximum assembly preload supported by the first screw thread and thus the tightening torque to be applied during assembly of an external taper thread with an internal metric parallel thread. Results showed that, in this case, just a few threads effectively engage and the 1th engaged thread supports the major part of the clamp load (approximately 35%). To clarify this procedure, there is a solved example at the end of the article.Especificar y aplicar el torque de apriete correcto para alcanzar la fuerza de tracción requerida es esencial para obtener una unión atornillada por fricción confiable. Para evitar la falla de cualquier componente y/o el auto-desatornillado, la longitud efectiva de los filetes enganchados es de suma importancia. Las formulaciones analíticas disponibles para estas aplicaciones contemplan la unión de roscas métricas paralelas, internas y externas. Sin embargo, no hay formulación analítica para rosca externa cónica con rosca interna paralela. Por lo tanto, el presente trabajo desarrolla un procedimiento analítico para determinar la longitud mínima de los filetes enganchados, el porcentaje de la máxima fuerza de montaje que soporta el primer filete enganchado y, así, determinar el torque de montaje de rosca externa métrica cónica con rosca interna paralela. Los resultados mostraron que, en este caso, solo un pequeño número de filetes se conecta efectivamente y el primer filete soporta la mayor parte de la fuerza de tracción requerida (aproximadamente 35%). Para ilustrar este procedimiento, se presenta un ejemplo resuelto al final del artículo.Especificar e aplicar o torque de aperto correto para se atingir a força de tração requerida é essencial para se obter uma união aparafusada por atrito confiável. Para evitar falha de qualquer componente e/ou o auto-desaparafusamento, o comprimento efetivo de filetes engajados é de suma importância. As formulações analíticas disponíveis para essas aplicações contemplam a união de roscas métricas paralelas, internas e externas. Entretanto, não há formulação analítica para rosca externa cônica com rosca interna paralela. Sendo assim, o presente trabalho desenvolve um procedimento analítico para determinar o comprimento mínimo de filetes engajados, a porcentagem da máxima força de montagem que o primeiro filete engajado suporta e, assim, determinar o torque de montagem de rosca externa métrica cônica com rosca interna paralela. Os resultados mostraram que, nesse caso, somente um pequeno número de filetes efetivamente se conecta e o 1º filete suporta a maior parte da força de tração requerida (aproximadamente 35%). Para ilustrar esse procedimento, um exemplo resolvido é apresentado no final do artigo
Anteprojeto de Hibridização em uma Picape Média do Mercado Brasileiro com um Motor Elétrico Acoplado ao Diferencial Mecânico no Eixo Traseiro
No full textThis work consists of the preliminary hybridization design of a mid-size pickup truck in the Brazilian market. In this sense, it is studied the technical feasibility of implementing an electric motor on the vehicle’s rear axle coupled to a mechanical differential. To this end, performance calculations for the vehicle, including climbing and overtaking are carried out, in addition to selecting a suitable electric motor, battery pack and designing the differential.
Subsequently, preliminary design conditions were analyzed. Regarding packaging, it was observed that the system's dimensions are compatible with the vehicle's size and do not encroach upon the cabin. A mass estimate indicated that the proposed hybrid pickup truck is approximately 90 kilograms lighter than a similar 4x4 Diesel pickup. Finally, by analyzing a hill climbing scenario on wet dirt terrain, it was concluded that the proposed vehicle possesses off-road capabilities.Este trabalho consiste no anteprojeto de hibridização de uma picape média do mercado brasileiro. Nesse sentido, estuda-se a viabilidade técnica da implementação de um motor elétrico no eixo traseiro do veículo, acoplado a um diferencial mecânico. Para tal, são realizados cálculos de desempenho do veículo, incluindo situações de subida em rampa e ultrapassagem, além da seleção de um motor elétrico adequado e do dimensionamento do diferencial.
Posteriormente, foram analisadas condições preliminares de projeto. Em relação ao empacotamento, observou-se que o sistema apresenta dimensões compatíveis com o tamanho do veículo, além de não invadir seu habitáculo. Por meio de uma estimativa de massa, constatou-se que a picape híbrida proposta é cercada 90 quilos mais leve que uma picape 4x4 Diesel similar. Por fim, ao analisar uma situação de subida em aclive em terreno de terra molhada, concluiu-se que o veículo proposto possui características favoráveis para o uso fora de estrada
Anteprojeto de powertrain híbrido hidráulico para veículos de passeio
No full textIn this study, an analysis is carried out on the transmission systems of current hybrid vehicles and the presentation of a preliminary transmission design for a hybrid passenger vehicle with an internal combustion engine combined with a hydraulic pressure accumulator. This second system allows the kinetic energy dissipated by conventional vehicles to be stored and reused, increasing the vehicle's efficiency. The environmental impacts caused by the increase in polluting gases in the atmosphere have pressured governments in several countries to demand greater efficiency from passenger cars. The response from automakers has been the electrification of their fleets, whether complete or hybridization, which has proven to be a more feasible and cheaper alternative in the short term. However, electric batteries are still expensive and lose efficiency significantly with charge and discharge cycles. Thus, the proposal for an innovative hybrid could be another alternative to reduce the impacts of vehicles and passenger transport on the environment. To achieve the objectives of this work, a study was carried out on current hybrids with a focus on transmission, different hybrid powertrain architectures were defined, proposals for vehicles that use a hydraulic pressure accumulator were analyzed and a preliminary design of a propulsion system for a vehicle was presented. In the end, in addition to compiling several studies on the subject, a hybrid propulsion system configuration was proposed for a passenger vehicle based on the Jeep Commander 2022.Neste estudo, realiza-se uma análise sobre os sistemas de transmissões dos veículos híbridos atuais e a apresentação de um anteprojeto de transmissão para um veículo híbrido de passeio com motor de combustão interna aliado a um acumulador de pressão hidráulico. Este segundo sistema permite armazenar e reutilizar a energia cinética normalmente dissipada pelos carros convencionais, aumentando a eficiência do automóvel. Os impactos ambientais causados pelo aumento de gases poluentes na atmosfera têm pressionado os governos de diversos países a exigirem maior eficiência dos carros de passeio. A resposta das montadoras tem sido a eletrificação de suas frotas, seja ela completa ou a hibridização, a qual tem se demonstrado uma alternativa mais factível e barata no curto prazo. Todavia, as baterias elétricas ainda são muito custosas e perdem eficiência de modo significativo com os ciclos de carga e descarga. Assim, a proposta de um híbrido inovador pode ser mais uma alternativa para reduzir os impactos dos carros e transportes de passeio no meio ambiente. Para alcançar os objetivos deste trabalho foi realizado um estudo sobre os híbridos atuais com foco na transmissão, foram definidas diferentes arquiteturas de powertrains híbridos, analisadas as propostas de veículos que utilizam acumulador de pressão hidráulico e foi apresentado um anteprojeto de um sistema de propulsão para um veículo desse tipo. Ao final, além da compilação de diversos estudos sobre o tema, foi proposta uma configuração de sistema de propulsão híbrido para um veículo de passeio baseado no Jeep Commander 2022
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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