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Ivan Cuk Dragan Mirkov Aleksandar Nedeljkovic Milos Kukolj Dusan Ugarkovic 《Sports biomechanics / International Society of Biomechanics in Sports》2016,15(2):207-219
The present study explored the method of testing muscle mechanical properties through the linear force–velocity (F–V) relationships obtained from loaded vertical jumps. Specifically, we hypothesised that the F–V relationship parameters depicting the force, power, and velocity of the tested muscles will differ among individuals of different physical fitness. Strength trained, physically active, and sedentary male participants (N = 10 + 10 + 10; age 20–29 years) were tested on maximum countermovement and squat jumps where manipulation of external loads provided a range of F and V data. The observed F–V relationships of the tested leg muscles were approximately linear and mainly strong (median correlation coefficients ranged from 0.77 to 0.92; all p < 0.05), independently of either the tested group or the jump type. The maximum power revealed higher values in the strength trained than in the physically active and sedentary participants. This difference originated from the differences in F-intercepts, rather than from the V-intercepts. We conclude that the observed parameters could be sensitive enough to detect the differences among both the individuals of different physical fitness and various jump types. The present findings support using loaded vertical jumps and, possibly, other maximum performance multi-joint movements for the assessment of mechanical properties of active muscles. 相似文献
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In most communication networks, error probabilities 1?→?0 and 0?→?1 are equally likely to occur. However, in some optical networks, such as local and access networks, this is not the case. In these networks, the number of received photons never exceeds the number of transmitted ones. Hence, if the receiver operates correctly, only 1?→?0 errors can occur. Motivated by this fact, in this paper, we present a class of integer codes capable of correcting burst and random asymmetric (1?→?0) errors within a b-bit byte. Unlike classical codes, the proposed codes are defined over the ring of integers modulo 2b ?1. As a result, they have the potential to be implemented in software without any hardware assist. 相似文献
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In professional cricket, where bowlers can bowl balls that reach speeds of up to 160 km h-1, effective head protection is vital. Current head protection equipment typically consists of a helmet with a high impact
grade polypropylene shell, a high density EPS liner, and a metal face guard. Most of the weight in existing helmets is attributed
to the steel grill used as the face guard. We present a virtual design approach to the development and evaluation of new face
guards made from alternative materials. In particular, we investigate a face guard design for cricket made from polycarbonate
rather than steel using an explicit dynamic finite element analysis (FEA) approach. The FEA model developed for this purpose
incorporates the headform, helmet, polycarbonate face guard and the impacting ball. ABAQUS CAE was used for FEA. HyperMesh
and SolidWorks were used to develop the geometric model. This work identifies appropriate modelling and simulation strategies,
and key design attributes for the development of new face guards using alternative materials. A preliminary study shows that
by using polycarbonates it is possible to reduce the mass of the face guard by 20%, thus contributing to greater comfort of
the players without compromising their safety. The key criteria for reduction of ball deceleration by at least 25% at each
test site were satisfied, with deceleration reduction values ranging from 44% to 87% from those due to ball impact with the
bare head. 相似文献
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The flying classroom – a cost effective integrated approach to learning and teaching flight dynamics
Michael A. Bromfield Aleksandar Belberov 《European Journal of Engineering Education》2017,42(6):1174-1195
In the UK, the Royal Aeronautical Society recommends the inclusion of practical flight exercises for accredited undergraduate aerospace engineering programmes to enhance learning and student experience. The majority of academic institutions teaching aerospace in the UK separate the theory and practice of flight dynamics with students attending a series of lectures supplemented by an intensive one-day flight exercise. Performance and/or handling qualities flight tests are performed in a dedicated aircraft fitted with specialist equipment for the recording and presentation of flight data. This paper describes an innovative approach to better integrate theory and practice and the use of portable Commercial-off-The-Shelf (COTS) technologies to enable a range of standard, unmodified aircraft to be used. The integration of theory and practice has enriched learning and teaching, improved coursework grades and the student experience. The use of COTS and unmodified aircraft has reduced costs and enabled increased student participation. 相似文献
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Ljiljana?Kolonja Ranka?Stankovi?Email author Ivan?Obradovi? Olivera?Kitanovi? Aleksandar?Cvjeti? 《知识管理研究与实践》2016,14(4):445-456
In this paper we outline an approach to application of ontology in knowledge management. The University of Belgrade Faculty of Mining and Geology research team has developed a terminological resource to support knowledge management in mining engineering. Mining engineering, like all other engineering disciplines, needs comprehensive, consistent and standardized definitions of terms for efficient knowledge management and interoperability among various related IT applications. This goal can best be reached by terminological resources in electronic form organized as thesauruses or ontologies. The resource used to illustrate this approach, RudOnto, is a system of ontologies developed for mining engineering and their application in mining equipment and mine safety domains. Key benefits of applying ontologies in knowledge management, aside from securing interoperability, are enhancement of browsing/searching functions, and reuse and structuring capabilities. Through export to several specific formats, RudOnto ontologies offer the possibility of generating stand-alone terminological resources or ontologies in specific sub-fields, such as mining equipment, mine safety and geostatistics. 相似文献
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Problem-based learning (PBL) is a student-centered instructional strategy in which students solve problems and reflect on their experiences. Different domains need different approaches in the design of PBL systems. Therefore, we present one case study in this article: A Java Programming PBL. The application is developed as an additional module for the Learning Management System (LMS). This way the LMS is extended by PBL functionality and the LMS learning resources can be used in PBL. 相似文献
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The purpose of the study was to develop an evidence-based method for identification and classification of wheelchair sports (rugby) activities and performance during a match using fractal dimensions. The approach involves five wheelchair rugby athletes of different classifications who were monitored during six different matches using mobile devices with in-built accelerometers. The linear acceleration signals were processed using two different approaches based on calculating fractal dimensions. One was based on Rényi’s entropy, which produced the probability dimension (S 0), and the other was based on Hausdorff’s definition, resulting in the Hausdorff dimension (D H). When both dimensions were individually plotted as cumulative distribution plots, they offered two approaches to analyze the performance of a wheelchair rugby athlete. Combining the two dimensions produced a two-dimensional (2D) mapping that identified five different activities of each athlete during a wheelchair rugby match—(1) no activities, (2) low activities, (3) high-speed coasting, (4) high-speed pushing, and (5) extreme collisions. In the 2D mapping, four boundary lines separate the five different activities, which produced a template for each athlete. It was found in this research that the classification and skill level of the athlete had an effect on the boundary line values that form the template. The outcome of the activity identification was also verified by comparing with video footage of the athletes. The method developed in this research has possible applications for coaching, match analysis, and talent identification. 相似文献