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991.
目的:本研究旨在凸显热效应在离合系统动态摩擦分析中的重要性以及将其拓展到制动系统的可能性。创新点:采用一种未被报道过的新方法从根本上整合摩擦特性、微结构组分、产热机理、摩擦片磨损和传热机制。方法:基于能量守恒原理,针对由飞轮、摩擦片和压力板构成的离合系统提出一种适用于工业应用的热分区网络解析模型。结论:1.通过实测得到的μ-ν特性表明,新的摩擦片具有磨损片子所不具备的温度敏感性。2.通过对磨损片子的微结构分析以及热导率变化的测量显示,晶格结构中铜颗粒损耗会导致其导热性能减弱。3.使用摩擦计的测量结果显示新的摩擦片相对于磨损片子具有更高的摩擦系数;较高的摩擦系数减轻了离合器啮合时产生的界面滑移的程度,从而减小了由于产热导致的摩擦功率损耗。4.根据本文发展的热学模型,新的摩擦片可通过其优良的导热性将摩擦产生的热量释放出去。 相似文献
992.
This paper analyses how knowledge-based practices adopted by innovation intermediaries enable them to generate value for themselves when collaborating with their clients. While the literature focuses on value creation for their client organisations, little is known about how innovation intermediaries create internal value even though this is essential for ensuring their long-term survival and sustaining their key facilitating role in the innovation system. This understudied issue is explored using empirical evidence from a sub-set of innovation intermediaries, Research and Technology Organisations (RTOs). The results indicate that by capitalising on existing knowledge vested in employees and collaborators as well as understanding and shaping the knowledge base of the innovation ecosystem, innovation intermediaries generate internal value from their involvement in collaborative innovation, which range from different financial to non-financial types of value. Implications for intermediaries, their collaborators and for policymakers are then discussed. 相似文献
993.
Arpita Ghosh Sara Rieder Bennett Juanita K. Martin 《Journal of College Student Psychotherapy》2018,32(2):151-162
The purpose of this initial, exploratory study was to examine the utility of the Counseling Center Assessment of Psychological Symptoms-62 (CCAPS-62) as a repeated measure tool at one university counseling center. This study investigated whether clients engaged in individual counseling changed in symptomology while in treatment and when (e.g., session) changes in symptomology occurred. To answer these research questions, reliable change indexes (RCIs) were calculated for each subscale of the CCAPS-62. Results indicated that all eight of the CCAPS-62 subscales demonstrated reliable changes from initial to subsequent administrations, and that changes occurred between sessions 3 and 6 at this specific university counseling center. Findings suggest the importance of incorporating CCAPS-62 information into counseling sessions to inform treatment and assessment. 相似文献
994.
Michael J. Mazzoleni Claudio L. Battaglini Kerry J. Martin Erin M. Coffman Jordan A. Ekaidat William A. Wood Brian P. Mann 《Sports Engineering》2018,21(1):31-41
This study examines the viability of utilizing a dynamical system model and heuristic parameter estimation algorithm to make predictions for maximum heart rate (\(\mathrm {HR_{max}}\)) and maximal oxygen uptake (\(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\)) using data collected from a submaximal testing protocol. \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) is widely considered to be the best single measurement of overall fitness in humans. When a \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) assessment is not available, \(\mathrm {HR_{max}}\) is often used to prescribe exercise intensities for training and rehabilitation. In the absence of maximal cardiopulmonary exercise testing (CPET), \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) are typically estimated using traditional submaximal prediction methods with well-known limitations and inaccuracies. For this study, 12 regularly exercising healthy young adult males performed a bout of maximal CPET on a cycle ergometer to determine their true \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\). Participants also performed a submaximal bout of exercise at varied intensities. A dynamical system model and heuristic parameter estimation algorithm were applied to the submaximal data to estimate the participants’ \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\). The submaximal predictions were evaluated by computing the coefficient of determination \({R^2}\) and the standard error of the estimate (SEE) through comparisons with the true maximal values for \(\mathrm {HR_{max}}\) (\({R^2 = 0.96}\), SEE = 2.4 bpm) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) (\({R^2 = 0.93}\), SEE = 2.1 mL kg\(^{-1}\) min\(^{-1}\)). The results from this study suggest that a dynamical system model and heuristic parameter estimation algorithm can provide accurate predictions for \(\mathrm {HR_{max}}\) and \(\dot{\mathrm {V}}{\mathrm {O_{2max}}}\) using data collected from a submaximal testing protocol. 相似文献
995.
996.
The aim of this study was to define the incidence and nature of match injuries sustained in men’s international under-20 rugby. The study comprised an 8-season prospective study of 16 international under-20 rugby tournaments. Procedures complied with the consensus statement for epidemiological studies in rugby. Outputs included players’ mean age, stature and body mass and incidence, severity, location, type and cause of match injuries. The overall incidence of injury was 49.7 injuries/1000 player-match-hours (backs: 48.3; forwards: 50.9) with a mean severity of 32.2 days-absence (backs: 29.4; forwards: 34.4). There were no significant changes in incidence or severity of injury over the study period. Shoulder/clavicle (18.3%), head/face (16.4%), knee (13.7%) and ankle (13.7%) were the most common injury locations and ligament sprain (35.4%), haematoma/bruise (15.9%), concussion (12.5%) and muscle strain (11.2%) the most common types of injury. Being-tackled (29.2%), tackling (24.0%) and collisions (14.3%) were the most common events leading to injury. The results confirm that international under-20 rugby has a high incidence and severity of injury but the incidence is half that reported for senior international players. There was no significant change in the overall incidence of injury at the Under-20 level in the period 2008 to 2016. 相似文献
997.
Tobias Vogt Simon Gassen Sören Wrede Jan Spielmann Martin Jedrusiak-Jung Sascha Härtel Jan Mayer 《Sportwissenschaft》2018,48(3):341-348
In today’s leading football training centres, state-of-the-art performance diagnostic systems such as the “Footbonaut” allow controlled and standardized assessments of physical and mental components of agility, e.g. speed of action and ball control, that are considered to be decisive for talent identification and development. However, effects of induced physical and mental strain on performing football-specific practice patterns remain to be elucidated, particularly in youth players, and, thus, characterize the purpose of this study. 33 randomly assigned competitive football players (U14 to U16) performed a standardized Footbonaut practice pattern (i.e. 20 balls randomly drawn at 50?km/h each), prior to and immediately after either mentally demanding tasks (MDT; n?=?11; continuous Vienna Test System’s Stroop task and determination test), physically demanding tasks (PDT; n?=?11; consisted of 4?×?4?min of football-specific high-intensity intervals with 3?min of active recovery in between) or a control condition (CON; n?=?11). Continuous heart rates (HR) as well as self-perceptions of fatigue were assessed. Main findings revealed performances for speed of action (p?=?0.44; f?=?0.01) and ball control (p?=?0.15; f?=?0.03) that were not modulated in the face of induced physical and mental strain as indicated by increased HR following PDT (p?<?0.001; d?>?0.8), or in the face of increased self-perceptions of fatigue following PDT and MDT (both p?<?0.001; both d?>?0.8) compared to CON. This is in line with a suggested talent factor and previous reports on motivational trade-off aspects in youth players. However, the present study’s short-timed practice patterns make it difficult to reliably compare a measuring sensitivity to complex football-specific movement behavioural and technical proficiencies with respect to mental and physical strain of longer-lasting football games and, thus, need further investigation in favour of improving talent identification and development using the Footbonaut. 相似文献
998.
Christiane Lösch Nico Nitzsche Christian Maiwald Daniel Zschäbitz Martin Weigert Henry Schulz 《Sportwissenschaft》2018,48(3):428-437
In the context of strength training in rehabilitation, visual movement control can be helpful to ensure correct movements. However, there are only a few studies that deal with the effectiveness of feedback during resistance exercises. To investigate the effect of feedback during guided exercise, 18 young adults (28.8?±?5.5 years) and 12 senior citizens (67.9?±?4.1 years) were tested. Subjects performed shoulder press exercises (3 sets, 15 repetitions) with and without visual movement control in a randomized order. On day 1, the subjects trained without load, and on day 2 they trained at 50% of their single repetition maximum. Joint articulation at the elbow was recorded using elbow extension and flexion. Autocorrelation was used to determine the reproducibility of movements. Subjects achieved better reproducibility of the movement with feedback than without (χ2?=?19.73; p?<?0.001). There was no effect of the load on motion accuracy (p?>?0.05), but the age group showed a significant effect (χ2?=?6.00; p?=?0.014). The younger group shows a higher degree of movement accuracy. In summary, visual movement control is useful in guided exercises to control movement execution. In clinical setting, this may be a way to control the motion performance of guided strength exercises and to ensure purposeful muscle work. Further studies should clarify the effect of visual feedback on the movement quality in unguided strength exercises. 相似文献
999.
This interpretive study of change in Australian book publishing, included a survey of book publishers and the conduct of 14
case studies in five categories of publisher: general trade, academic, professional, specialist and university. This paper
reports in detail on the experience on one general trade publisher as it sought to face the challenges of globalization and
of organizational and technological change. The major finding was that digitization is indeed, impacting on business models
for book publishing, with current models comprising something of a hybrid between the traditional and the innovative. Reflecting
the presence in Australia of similar trends and issues that are affecting book publishing around the world, the findings are
of relevance both to book publishers and to researchers. The work is original in that relatively little recent academic research
has been conducted into book publishing in Australia, particularly as regards the implications of digitization for business
models. 相似文献
1000.