1,720,965 research outputs found
Developed an Innovative Handbike Fork Made of Composite Material
No full textIn this research, the design of a new competitive handbike fork, made of a composite material, is presented. The study is based both on an early finite element analysis and on a CFD analysis of the characteristics and performance of a standard fork made of aluminum, allowing to define the loading and the flux conditions and to provide a design optimization of the fork. The model was later implemented iteratively with the properties of a carbon-fiber composite material. The results obtained show that the new model allows a weight and a drag force reduction and a downforce improvement, with a stiffness and a safety coefficient comparable to the standard aluminum fork
Dynamic Analysis of a Quay Crane Using Lumped Parameter Models
No full textThe objective of this research activity is to evaluate the extent to which models with lumped parameters might be appropriate for the development of lifting devices. The models we used have only one or two degrees of freedom, but the parameters of the crane were derived by a FEM analysis of its structure, while the viscoelastic parameters of the ropes took into account their time-varying behavior. The results showed that it is useful to consider the length of the ropes in order to calculate more accurately the dynamics of the crane, since the stiffness and the damping change during the load movement. According to the results, higher stress values were also obtained using the model with one degree of freedom for the ropes. This implies that the model can be useful for rope selection as it ensures a conservative estimate of their coefficient of safety. In the case of the two-degree-of-freedom model, the same is true for the structure
Embedded Payload Solutions in UAVs for Medium and Small Package Delivery
Full text linkInvestigations about the feasibility of delivery systems with unmanned aerial vehicles (UAVs) or drones have been recently expanded, owing to the exponential demand for goods to be delivered in the recent years, which has been further increased by the COVID-19 pandemic. UAV delivery can provide new contactless delivery strategies, in addition to applications for medical items, such as blood, medicines, or vaccines. The safe delivery of goods is paramount for such applications, which is facilitated if the payload is embedded in the main drone body. In this paper, we investigate payload solutions for medium and small package delivery (up to 5 kg) with a medium-sized UAV (maximum takeoff of less than 25 kg), focusing on (i) embedded solutions (packaging hosted in the drone fuselage), (ii) compatibility with transportation of medical items, and (iii) user-oriented design (usability and safety). We evaluate the design process for possible payload solutions, from an analysis of the package design (material selection, shape definition, and product industrialization) to package integration with the drone fuselage (possible solutions and comparison of quick-release systems). We present a prototype for an industrialized package, a right prism with an octagonal section made of high-performance double-wall cardboard, and introduce a set of concepts for a quick-release system, which are compared with a set of six functional parameters (mass, realization, accessibility, locking, protection, and resistance). Further analyses are already ongoing, with the aim of integrating monitoring and control capabilities into the package design to assess the condition of the delivered goods during transportation
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
Study of the Vibrations in a Rotary Weight Filling Machine
No full textObjective: this paper presents an experimental study of the vibration phenomena in the dynamic weighing system of an automatic rotary filling machine for fluids. The study aims at the sensitivity analysis of the environmental vibrations when the operating conditions of the machine vary and at the identification of the principal causes of excitation. Methods: numerous experimental tests have been carried out on a dedicated test bench and on a complete machine with sixteen stations. For a filling station the load cell signal and the acceleration of the plate that supports the bottle have been acquired and studied. A one-degree of freedom model with varying mass has been implemented in a dedicated software in Delphi language for the vibration modelling. Results: a detailed sensitivity analysis has been developed. The model has allowed a deeper understanding of the phenomena that occur. It also showed the potentiality to be used for the vibration prediction in a compensation process
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
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