半定规划的齐次不可行内点算法

为降低半定规划(SDP)问题的迭代复杂度,并且有更好的数值实验结果,提出一种新的宽邻域上的齐次不可行内点算法.半定规划的KKT条件是单调互补问题(MCP),通过构造齐次模型(HMCP)以及提出新的宽邻域来解这个齐次模型,得到半定规划问题的最优解.这种算法容易判定原问题是否可行.在NT方向,证明迭代点在新的宽邻域内是收敛的,且迭代复杂度为O(√nlogL),其中n是SDP问题的维数,L=Tr(X⁰S⁰)/ε,其中ε是需要的精度,(X⁰,S⁰)是迭代起始点.这个复杂度比一般的半定规划不可行算法的迭代复杂度低.提供了数值实验,证明此算法比其他不可行算法具有更好的数值实验结果.     

基于多目标的大型体育场馆 PPP项目的融资性研究

PPP模式已成为我国公共产品或服务提供的重要方式。PPP 项目的融资性是公私双方合作的关键因素之一。PPP项目中主要合作方的融资目标既有共同点又存在差异点。研究在文献回顾的基础上,依据利益相关理论,分析了我国大型体育场馆政府、社会资本和公众对 PPP项目融资目标的不同诉求和体育场馆融资要素结构,运用多目标规划模型,以重庆市某体育场馆为例对伙伴各方接受的融资性进行方案对比,探讨了假设条件下实现体育场馆PPP项目融资的最佳伙伴合作方式。     

公共体育场馆经营管理年限交接的程序化设计及其操作模式——以浙江省典型场馆为例

委托型公共体育场馆的成功运作为体育场馆的发展提供了空阔的空间,场馆的年限交接是场馆改革重要环节,是民营化模式的完善主要步骤,关系到改革的成败。通过文献资料、实地考察、理论分析等研究方法,从而得出年限交接程序化设计及第三方操作的可行性。     

基于概念格的企业群体创新偏好挖掘研究

为精准捕捉各类企业创新偏好信息,提出一种专利数据驱动下基于模糊三支概念格对企业创新偏好进行群体画像的模型,以专利IPC信息为切入点层次化抽取企业群体创新偏好共性特征,实现领导型、稳定型、潜力型、危险型四类企业创新偏好的差异化多粒度刻画。在此基础上提出模糊三支概念格相似度定义,构建带有相似度的创新偏好模糊三支概念格,揭示各企业间创新偏好关联关系。以中国集成电路设计行业数据为例实证验证模型有效性,结果表明模型可以清晰展现各类企业差异化创新偏好领域布局以及结构布局,为企业竞争战略制定及政府创新决策提供理论依据及参考。     

Optimal sampling frequency in recording of resistance training exercises

The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f_99.9 = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality.     

Digital Module 16: Longitudinal Data Analysis

In this digital ITEMS module, Dr. Jeffrey Harring and Ms. Tessa Johnson introduce the linear mixed effects (LME) model as a flexible general framework for simultaneously modeling continuous repeated measures data with a scientifically defensible function that adequately summarizes both individual change as well as the average response. The module begins with a nontechnical overview of longitudinal data analyses drawing distinctions with cross-sectional analyses in terms of research questions to be addressed. Nuances of longitudinal designs, timing of measurements, and the real possibility of missing data are then discussed. The three interconnected components of the LME model—(1) a model for individual and mean response profiles, (2) a model to characterize the covariation among the time-specific residuals, and (3) a set of models that summarize the extent that individual coefficients vary—are discussed in the context of the set of activities comprising an analysis. Finally, they demonstrate how to estimate the linear mixed effects model within an open-source environment (R). The digital module contains sample R code, diagnostic quiz questions, hands-on activities in R, curated resources, and a glossary.     

Predicting ground reaction forces in running using micro-sensors and neural networks

Measurement of ground reaction force (GRF) in running provides a direct indication of the loads to which the body is subjected at each foot-ground contact, and can provide an objective explanation for performance outcomes. Traditionally, the collection of three orthogonal component GRF data in running requires an athlete to complete a series of return loops along a laboratory based runway, within which a force platform is embedded, in order to collect data from a discrete footfall. The major disadvantages associated with this GRF data collection methodology include the inability to assess multiple consecutive foot contacts and the fact that measurements are typically confined to the laboratory. The objective of this research was to investigate the potential for wearable instrumentation to be employed, in conjunction with artificial neural network (ANN) and multiple linear regression (MLR) models, for the estimation of GRF in middle distance running. A modular wearable data acquisition system was developed to acquire in-shoe force (ISF) data. Matched data sets from wearable instrumentation (source data) and force plate (target data) records were collected from elite middle-distance runners under controlled laboratory conditions for the purposes of ANN and MLR model development (MD) and model validation (MV). In terms of statistical measures of prediction accuracy the MLR model was found to provide a superior level of accuracy for the prediction of the vertical and medio-lateral components of GRF and alternatively, the ANN model provided the most accurate predictions of the anterior-posterior component of GRF. The prediction accuracy of each component of GRF was found to be governed by the inherent signal variability, in which case the vertical and anterior-posterior components were more reliable and subsequently predicted significantly more accurately than the medio-lateral component. The emerging capability for obtaining continuous GRF records from wearable instrumentation has the potential to permit unprecedented quantification of training stress and competition demands in running.     

模糊数学及层次分析法在体育课评估中的应用及比较

本文根据体育课教学的特点 ,建立了对教学质量综合评估的指标体系 ,制订了体育课教学质量评定表 ,并利用模糊数学及层次分析的方法 ,建立了简单、可靠的综合评估计算方法 ,解决了课程指标的量化困难。     

Home advantage in speed skating: Evidence from individual data

Home advantage is a well-documented phenomenon in many sports. Home advantage has been shown to exist for team sports (soccer, hockey, football, baseball, basketball) and for countries organizing sports tournaments like the Olympics and World Cup Soccer. There is also some evidence for home advantage in some individual sports, but there is a much more limited literature. This paper addresses the issue of home advantage in speed skating. From a methodological point of view, it is difficult to identify home advantage, because skaters vary in their abilities and the conditions of tournaments vary. There is a small but significant home advantage using a generalized linear mixed model, with random effects for skaters and fixed effects for skating rinks and seasons. Even though the home advantage effect exists, it is very small when compared to variation in skating times due to differences of rinks and individual abilities.     

Programming Time as a Function of Movement Constraint

Abstract

Although the benefits of exercise are well documented, an international problem of physical inactivity exists. More research, especially theory based, has been recommended. One promising approach for studying exercise behavior is that proposed in the Transtheoretical Model (TTM) of behavior change. This model, however, has received minimal cross-cultural attention and, relative to the current study, measurement instruments have only recently been translated into the Finnish language. The purpose of this study was to assess American and Finnish college students' exercise behaviors on the basis of TTM. Participants were American (n = 169) and Finnish (n = 168) college students who completed language-specific measures of exercise behavior, stage of change, processes of change, decisional balance, self-efficacy, and temptation. The only cultural difference observed was that the American participants rated themselves higher on barrier self-efficacy relative to the Finnish participants. Regardless of nationality or gender, participants classified by their stage of change differed on all the core constructs assessed. These results generally support the utility of TTM for understanding American and Finnish college students' exercise behavior.