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91.
Martino Colonna Nicola Pazi Matteo Moncalero Claudio Gioia Federico De Bon Davide Giovanelli Elisabetta Farella 《Sports Engineering》2017,20(4):275-282
We have performed a study on the thermo-formation process of plastic shells of boots for winter sports. The aim of the work has been to determine how the process parameters can improve the ergonomic and thermal comfort for athletes and winter sports participants. We have found that the initial deformation and memory effect are strongly influenced by the type of thermoplastic material used, heating time and cooling procedure. We have also found that the ovens currently used for this process are not correctly designed to obtain an efficient heat transfer and, therefore, a heating time of at least 12 min is necessary to achieve an average deformation of more than 2 mm. The measure of the boot flexural stiffness has shown that there are no changes in the load–deflection behavior after the thermo-formation process of a ski boot made of thermoplastic polyurethane. We have also found that the thermo-formation process decreases the pressure on skier’s feet of more than five times and, therefore, improves the comfort of the skier. 相似文献
92.
Most of the peer-to-peer search techniques proposed in the recent years have focused on the single-key retrieval. However, similarity search in metric spaces represents an important paradigm for content-based retrieval in many applications. In this paper we introduce an extension of the well-known Content-Addressable Network paradigm to support storage and retrieval of more generic metric space objects. In particular we address the problem of executing the nearest neighbors queries, and propose three different algorithms of query propagation. An extensive experimental study on real-life data sets explores the performance characteristics of the proposed algorithms by showing their advantages and disadvantages. 相似文献
93.
Claudio Di Lorito Annabelle Long Adrian Byrne Rowan H.Harwood John R.F.Gladman Stefan Schneider Pip Logan Alessandro Bosco Veronika van der Wardt 《运动与健康科学(英文)》2021,10(1):29-47
Background:The evidence concerning which physical exercise characteristics are most effective for older adults is fragmented.We aimed to characterize the extent of this diversity and inconsistency and identify future directions for research by undertaking a systematic review of metaanalyses of exercise interventions in older adults.Methods:We searched the Cochrane Database of Systematic Reviews,PsycInfo,MEDLINE,Embase,CINAHL,AMED,SPORTDiscus,and Web of Science for articles that met the following criteria:(1)meta-analyses that synthesized measures of improvement(e.g.,effect sizes)on any outcome identified in studies of exercise interventions;(2)participants in the studies meta-analyzed were adults aged 65+or had a mean age of 70+;(3)meta-analyses that included studies of any type of exercise,including its duration,frequency,intensity,and mode of delivery;(4)interventions that included multiple components(e.g.,exercise and cognitive stimulation),with effect sizes that were computed separately for the exercise component;and(5)meta-analyses that were published in any year or language.The characteristics of the reviews,of the interventions,and of the parameters improved through exercise were reported through narrative synthesis.Identification of the interventions linked to the largest improvements was carried out by identifying the highest values for improvement recorded across the reviews.The study included 56 meta-analyses that were heterogeneous in relation to population,sample size,settings,outcomes,and intervention characteristics.Results:The largest effect sizes for improvement were found for resistance training,meditative movement interventions,and exercise-based active videogames.Conclusion:The review identified important gaps in research,including a lack of studies investigating the benefits of group interventions,the characteristics of professionals delivering the interventions associated with better outcomes,and the impact of motivational strategies and of significant others(e.g.,carers)on intervention delivery and outcomes. 相似文献
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96.
The aim of this study was to examine the impact of emotions on athletic performance within the frameworks of the Individual Zones of Optimal Functioning (IZOF) model and the directional perception approach. Intensity, functional impact, and hedonic tone of trait and state anxiety, self-confidence, idiosyncratic emotions, and bodily symptoms were assessed in high-level Italian swimmers and track and field athletes (N = 56). Three standards of performance (poor, average, and good), derived from retrospective self-ratings across one to three competitions (a total of 90 observations), were used as independent variables in the analysis of variance of intensity, intra-individual, and direction scores of anxiety, self-confidence, idiosyncratic emotions, and bodily symptoms. Subsequently, intra-individual scores were categorized as near to or distant from optimal/dysfunctional zones and entered as the independent variable in the analysis of direction scores. The results provided support for the predictions stemming from both the IZOF model and the directional approach, as well as help in interpreting direction of anxiety and other idiosyncratic emotions within the IZOF framework. Athletes tended to perceive emotional levels approximating an individual's optimal zone as facilitative-pleasant, and emotional levels approximating an individual's dysfunctional zone as debilitative-unpleasant. 相似文献
97.
To address the inability of current ranking systems to support subtopic retrieval, two main post-processing techniques of search results have been investigated: clustering and diversification. In this paper we present a comparative study of their performance, using a set of complementary evaluation measures that can be applied to both partitions and ranked lists, and two specialized test collections focusing on broad and ambiguous queries, respectively. The main finding of our experiments is that diversification of top hits is more useful for quick coverage of distinct subtopics whereas clustering is better for full retrieval of single subtopics, with a better balance in performance achieved through generating multiple subsets of diverse search results. We also found that there is little scope for improvement over the search engine baseline unless we are interested in strict full-subtopic retrieval, and that search results clustering methods do not perform well on queries with low divergence subtopics, mainly due to the difficulty of generating discriminative cluster labels. 相似文献
98.
Claudio De Moura Castro 《比较教育学》2002,38(4):387-399
To some, the World Bank is the all-powerful arm of imperialism. Others regret that it is powerless, incapable of influencing policies in the countries in which it operates. This paper discusses these issues, as seen by the author, a former employee both of the World Bank and the Inter-American Development Bank, as well as a civil servant and consultant at the receiving end of the loans. This experience provides an inside view but the reader has to be warned of the biases that might have resulted from it. 相似文献
99.
Mean or median student growth percentiles (MGPs) are a popular measure of educator performance, but they lack rigorous evaluation. This study investigates the error in MGP due to test score measurement error (ME). Using analytic derivations, we find that errors in the commonly used MGP are correlated with average prior latent achievement: Teachers with low prior achieving students have MGPs that underestimate true teacher performance and vice versa for teachers with high achieving students. We evaluate alternative MGP estimators, showing that aggregates of SGP that correct for ME only contain errors independent of prior achievement. The alternatives are thus more fair because they are not biased by prior mean achievement and have smaller overall variance and larger marginal reliability than the Standard MGP approach. In addition, the mean estimators always outperform their median counterparts. 相似文献
100.
Michael J. Mazzoleni Claudio L. Battaglini Kerry J. Martin Erin M. Coffman Brian P. Mann 《Sports Engineering》2016,19(2):117-127
Prior studies have investigated heart rate dynamics from a variety of perspectives, but are often inadequate for predicting heart rate responses across a broad range of transient exercise intensities. The aim of this study was to develop a nonlinear model to describe the heart rate response of an individual during cycling and to investigate whether heart rate is more accurately predicted by a combination of power output and cadence than by power output alone. The proposed model can account for the transient fluctuations of an individual’s heart rate while they participate in exercise that varies in intensity. The participants for this study each performed a fifty minute bout of cycling on an electric-braked cycle ergometer in the laboratory. The testing protocol for the cycling bout was designed to challenge the predictive capabilities of the model and the participants therefore abruptly changed their power outputs and cadences throughout the tests, which resulted in significant transient fluctuations in their heart rate responses. Due to the nonlinear nature of the proposed heart rate model, a heuristic algorithm was developed to perform the parameter estimation. The model predictions for heart rate matched very well with the experimental heart rate responses for each of the participants, especially when considering the challenges inherent to predicting abrupt transient behavior in the heart rate response. Model comparisons also indicated that heart rate is more accurately predicted by a combination of power output and cadence than by power output alone. 相似文献