Equivalent formulations of the Müntz-Szász completeness condition for systems of complex exponentials     

Luc Knockaert 《Journal of The Franklin Institute》2002,339(1):103-109

New results pertaining to the completeness of a system of complex exponentials in L_p spaces are presented. It is shown that the well-known Müntz-Szász condition can be interpreted in terms of an equivalence relation, thereby proving that the standard Müntz-Szász formulation is equivalent with certain alternative formulations.  相似文献   

正弦永磁同步电机转矩脉动抑制     

周志斌  谢卫  Luc LORON 《上海海事大学学报》2009,30(2):65-71

为研究永磁同步电机中非正弦气隙磁链分布及其对转矩脉动的影响,用Matlab/Simulink对磁链非正弦、且存在较大齿槽转矩的永磁同步电机及其控制系统进行仿真.采用迭代学习控制算法抑制永磁同步电机转速和转矩的脉动.对转速环和转矩环下两种不同的迭代学习控制方案进行比较.仿真结果表明,两种不同的迭代学习控制方案均可以抑制转矩和转速的脉动.  相似文献   

Transactional Links Between Social Anxiety Symptoms and Parenting Across Adolescence: Between- and Within-Person Associations     

Stefanie A. Nelemans  Loes Keijsers  Hilde Colpin  Karla van Leeuwen  Patricia Bijttebier  Karine Verschueren  Luc Goossens 《Child development》2020,91(3):814-828

This 4-year longitudinal multi-informant study examined between- and within-person associations between adolescent social anxiety symptoms and parenting (parental psychological control and autonomy support). A community sample of 819 adolescents (46.1% girls; M_ageT₁ = 13.4 years) reported annually on social anxiety symptoms and both adolescents and mothers reported on parenting. Between-person associations suggested that adolescent social anxiety symptoms were associated with higher adolescent- and mother-reported psychological control and lower mother-reported autonomy support. At the within-person level, however, mothers reported lower psychological control and higher autonomy support after periods with higher adolescent social anxiety symptoms. Our findings illustrate the importance of distinguishing among between-person and within-person associations and including perceptions of both dyad members in longitudinal research concerning parenting and adolescent mental health.  相似文献   

The Validity of the Interpersonal Behaviors Questionnaire (IBQ) in Sport   总被引：1，自引：1，他引：0  

Meredith Rocchi  Luc Pelletier  Philippe Desmarais 《Measurement in physical education and exercise science》2017,21(1):15-25

According to Self-Determination Theory (SDT), basic psychological needs will be influenced by other individuals’ interpersonal behaviors. The objective of the present research is to extend the validity of the Interpersonal Behaviors Questionnaire (IBQ and IBQ-Self) to the sport context. The measure was designed to assess perceptions of interpersonal behaviors of others (IBQ) or self-reports of interpersonal behaviors (IBQ-Self) in the context of SDT. This measure consists of 24 items and six subscales looking at autonomy-supportive, autonomy-thwarting (controlling), competence-supportive, competence-thwarting, relatedness-supportive, and relatedness-thwarting interpersonal behaviors. In Study 1, athletes were asked to report on their perceptions of their coaches’ interpersonal behaviors (IBQ). In Study 2, coaches were asked to report on their interpersonal behaviors when they coach their athletes (IBQ-Self). The results supported that the scale had a strong factor structure, internal consistency, and validity. Overall, the results supported the IBQ and IBQ-Self are valid measures of interpersonal behaviors in sport.  相似文献   

Worldwide variation in the performance of children and adolescents: an analysis of 109 studies of the 20-m shuttle run test in 37 countries   总被引：1，自引：1，他引：0  

Olds T  Tomkinson G  Léger L  Cazorla G 《Journal of sports sciences》2006,24(10):1025-1038

This study is a meta-analysis of 109 reports of the performance of children and adolescents on the 20-m shuttle run test (20-mSRT). The studies were performed in 37 countries and included data on 418,026 children, tested between 1981 and 2003. Results were expressed as running speed (km x h(-1)) at the final completed stage of the 20-mSRT. Raw data were combined with pseudodata using Monte Carlo simulation. The 20-mSRT performances were expressed as z-scores relative to all children of the same age and sex from all countries. An overall "performance index" was derived for each country as the average of the age- and sex-specific z-scores for all children from that country. Factorial analysis of variance was used to compare scores among countries and regions, and between boys and girls of the same age. There was wide and significant (P < 0.0001) global variability in the performance of children. The best performing children were from the Northern European countries Estonia, Iceland, Lithuania, and Finland (0.6 - 0.9 standard deviations above the global average). The worst performing children were from Singapore, Brazil, USA, Italy, Portugal, and Greece (0.4 - 0.9 standard deviations below the global average). There is evidence that performance was negatively related to being overweight, as well as to a country's average temperature.  相似文献   

Validation of the Child Sport Cohesion Questionnaire     

Luc J. Martin  Albert V. Carron  Mark A. Eys  Todd Loughead 《Measurement in physical education and exercise science》2013,17(2):105-119

This article challenges measurement specialists and other physical education and exercise science professionals to explore alternative models that are not based on classical test theory. Examples illustrate how the many-facet Rasch model has been used to solve measurement problems associated with performance assessments in the fields of medicine, business, and sport. A second challenge calls for more collaborative research efforts that address measurement problems in physical education and exercise science. The measurement subdiscipline will advance in the 21st century if these challenges are met.  相似文献   

Low-dose exercise training does not influence cardiac autonomic control in healthy sedentary men aged 55 – 75 years     

Bart Verheyden  Bert O. Eijnde  Frank Beckers  Luc Vanhees  André E. Aubert 《Journal of sports sciences》2013,31(11):1137-1147

Abstract

The purpose of this study was to evaluate the effects of a realistic, feasible, and commonly used fitness training programme on cardiac autonomic control in 14 sedentary men aged 62.0 ± 6.1 years (mean ± s). All participants performed a one-year fitness training programme in which training intensity and frequency were specifically chosen to be compliant for the majority of the participants (2 – 3 sessions per week at moderate intensity). At the same time, a reference group consisting of 15 sedentary age-matched men (age 64.2 ± 6.5 years) did not change their habitual physical activity. Measurements were performed before and after the training intervention. Cardiac autonomic control was inferred from resting values (supine and standing) of heart rate variability (HRV) computed in the frequency domain over 10-min intervals. Endurance capacity was evaluated during a maximal incremental bicycle ergometer test. In spite of an increase in peak oxygen consumption ([Vdot]O_2peak) by 6.4% after training, heart rate in the training group remained unchanged at rest and at the same metabolic demand. No changes in resting parameters of HRV were shown for either groups or positions. Results from this study provide no evidence of a clinically meaningful increase in the vagal modulation to the sinus node at rest after one year of low-volume and moderate-intensity fitness training in men aged 55 – 75 years.  相似文献   

Sport to the Rescue of the Suburbs: Sport to Educate? Sport to Reassure? When Politicians Respond to the Signs of Disturbance of Law and Order     

Dominique Bodin  Luc Robène 《国际体育史杂志》2014,31(16):1993-2012

Since the beginning of the 1980s, sport has appeared to be the last recourse against the worsening of living conditions, lack of job security and the ghettoisation of certain boroughs that stand out mostly because of continuing urban riots and juvenile violence. All of this is continually exaggerated by the media and politicians in their continual desire to dramatise and exaggerate. Certain sub-issues immediately emerge: what are the theoretical or ideological foundations on which this concept of making sport a lever for preventive policies is based? And what sport are we talking about? Is it the physical activities and sport (PAS) practised in the schools and institutes, civil sport or sport in the streets? Why do young people increasingly abandon civil/federated sport to practise ‘adventure sports’ or self-organised sports? Can self-organised sports and, more precisely, sport played outside the tower blocks favour the ‘self-control of impulses’? And if they can, under what conditions can they favour socialisation and contribute to preventing vandalism or violent acts? If it must be admitted that the links between sport and education, sport and prevention, sport and insertion, etc., are considered to be self-evident, they are rarely analysed or questioned.  相似文献   

Sport and Civilisation: Violence Mastered? From Civilising Functions to Pacifying Functions     

Dominique Bodin  Luc Robène 《国际体育史杂志》2014,31(16):2079-2099

Explaining that it is not possible to divide human activity (political, economic, social, sport, etc.) into different sectors, as they all originate from the same actors, Norbert Elias and Eric Dunning thus came to formulate the central hypothesis of a network which linked the process of pacification of customs, the development of a parliamentary system for society, the state monopoly of violence, the euphemisation of violence in the aristocracy, the genesis of sport and, by recursion, the roles and functions of modern sports in the state control of violence and the learning of self-control. Elias and Dunning contrast modern sports with the ancient games, euphemisation and the persistence of violence, ‘sport’ leisure characteristic of ‘modern’ societies and traditional games in the ‘ancient’ societies, which accompanied the religious calendars and rites of passage. But do they really question society? This paper shows how the problems posed by Elias' theory are, essentially, of three types: first, those linked to the methodology used; second, those related to the limits imposed by the notion of self-constraint; and, finally, those concerning the pacifying function attributed to sport.  相似文献   

Forecasts of primary-education expenditure in developing countries in the year 2000     

Gérard Lassibille  María Lucía Navarro Gómez 《Prospects》1990,20(4):513-524

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