二次曲线拟合算法的统计性能分析与改进     

杨忠根  姜桂祥  陈红亮 《上海海事大学学报》2003,24(1):46-51

传统的二次曲线拟合使用标准特征值分析算法。通过统计分析技术 ,可知该技术在拟合数字二次曲线时 ,存在估计偏差大、均方误差大的缺点。其产生原因是数据噪声的有色性和自相关函数矩阵的条件数过大 ,因此白化数据噪声和正则化变换是提高曲线拟合的有效措施。这从理论上有力地支持了Hartley提出的正则化算法。通过理论分析和计算机仿真实验 ,表明了降维EVD技术固有地同时具备噪声预白化功能和数据正则化功能 ,因此它能给出均方误差相当小的无偏估计。由于它无须进行预白化变换或正则化变换 ,并把最优化过程的维数从 6降为 2 ,所以它还具有计算快速、实现简单方便的优点。  相似文献   

对不同项群运动员运动负荷前后左心室舒张功能的观察   总被引：2，自引：0，他引：2  

宋信勇  周全  张维珂  杨俊峰 《北京体育大学学报》2003,26(1):43-44

为了评价不同项群运动员左心室舒张功能,对12名耐力项目运动员和12名速度力量项目运动员12min前后二尖瓣血流频谱进行了检测。结果表明:12min跑后耐力组血流速度积分和E/A明显减小,速度力量组血流速度积分、E峰值和E/A减小十分明显,A峰值减小明显,两组运动员血流速度积分、E峰值和E/A存在显著差异。说明,耐力组左心室舒张主动松驰及被动充盈能力均好于速度力量组。  相似文献   

动态运动诱发腰部脊竖肌疲劳过程中sEMG信号变化特征   总被引：17，自引：1，他引：16  

王健 《中国体育科技》2001,37(4):9-11

本研究的目的在于观察动态运动诱发腰部脊竖肌疲劳过程中sEMG信号线性分析指标MPF和非线性分析指标Lempel-Ziv复杂度和近似熵的动态变化规律，确定能够较好地运用于脊竖肌功能评价的sEMG指标。研究结果表明，动态运动过程中，腰部脊竖肌sEMG信号的MPF和Lempel-Ziv复杂度均呈明显的线性规律下降；70%的受试者的近似熵呈先升后降型变化;以MPF下降来预测腰部脊竖肌功能水平的外部效度优于Lempel-Ziv复杂度。研究结果提示，sEMG信号的上述变化可能是神经肌肉系统自组织调节活动的表现。  相似文献   

体育科研三维方法述要(上)   总被引：1，自引：0，他引：1  

张洪潭 《体育与科学》2003,24(2):34-39

将常规的体育科研方法区分为三个相互关联的维度，其中，取材维含括观察、实验、假设三层阶，分别强调思考、目标、理论的不可或缺性；程序维依循一般思辨、专一选题、采集素材、整理素材、推理判断，验察修正六环节；课题维则从生物性学科和社会性学科两大方面寻求变革。最后还论及撰写文章十要点和缩减文字三要诀。  相似文献   

高频心电图和频谱心电图的进展及其在体育运动中的应用   总被引：1，自引：0，他引：1  

李爽 《成都体育学院学报》1995,21(4):67-70

心电图高频成分分析以及心电信号的频谱分析，是近年来在国内外发展的一种新型心电检测技术，尤其是９０年代初此种技术研究临床医学中发展甚速，已形成了一种全新的无创技术。笔者综述了此技术之历史沿革和目前进展，尤其是在体育运动中的应用。  相似文献   

基于深度强化学习的低轨卫星下行功率分配方案     

张华明  李强 《中国科学院大学学报》2022,39(4):543-550

当前的卫星资源分配方案大多为同步轨道卫星设计,针对低轨卫星的高动态特性,以及存在频率和功率资源受限的问题,提出一种基于深度强化学习的功率分配算法。首先对低轨卫星功率分配场景进行建模,引入一种时隙划分方案来简化低轨卫星的动态特性模型,进一步提出一种基于深度强化学习算法的功率分配策略,该策略通过调节单颗低轨卫星各个波束中子载波的功率值,降低同频干扰,能达到提升低轨卫星频谱效率的目的。仿真结果表明,所提算法能够在较短时间内收敛并达到稳定状态,在总功率一定的条件下,该方案能有效提升单颗低轨卫星的吞吐量,其频谱效率明显高于注水算法和Q学习算法。  相似文献   

Proximal advantage in knowledge diffusion: The time dimension     

Jue Wang  Liwei Zhang 《Journal of Informetrics》2018,12(3):858-867

This paper intends to explore the impact of geographic proximity on the diffusion of knowledge in the form of publication citations, and argues that codified knowledge is transmitted faster in proximity and is subject to similar geographic constraints as tacit knowledge. The geographic proximity advantage would be particularly relevant in the early stage of dissemination. We collected three sets of research articles published in 1990, 2000 and 2010 and compared the longitudinal citations they received domestically and from abroad. The study found that domestic citations accumulate faster and reach their peak much earlier than foreign citations, and the difference is most evident in the first few years after publication. The result shows that geographic proximity does play a role in the speed of knowledge diffusion and points to the network effect for citations. Those located closer to the knowledge origin would be exposed and react to publications faster due to the additional opportunities of research exchange and network.  相似文献   

The deployment,training and teacher relationships of teaching assistants supporting pupils with autistic spectrum disorders (ASD) in mainstream secondary schools     

Wendy Symes  Neil Humphrey 《British Journal of Special Education》2011,38(2):57-64

Growing numbers of pupils with autistic spectrum disorders (ASD) are attending mainstream schools, and increasing numbers of additional staff are being deployed to support them. Recent research has cast doubt on the effectiveness of this support, by highlighting issues relating to deployment and training, and to relationships with class teachers. This study, conducted by Wendy Symes, who is a Research Associate at the University of Manchester, and Neil Humphrey, who is Professor of Education in the same university, interviewed 15 teaching assistants supporting pupils with ASD in four mainstream secondary schools in the north‐west of England to explore these issues. Analysis yielded several key findings. The majority of teaching assistants worked with just one pupil at a time and worked in a variety of lessons. Their role primarily involved helping pupils to stay focused and follow instructions. Many teaching assistants had no experience of ASD prior to starting their job. The amount of training received varied, but all felt that generic training about ASD was not helpful. A lack of time for joint planning with teachers was raised as a key concern. These findings are discussed in relation to the growing literature on inclusive education for pupils with ASD.  相似文献   

Mapping the educational experiences of children with pathological demand avoidance     

Emma Gore Langton  Norah Frederickson 《Journal of Research in Special Educational Needs》2016,16(4):254-263

‘Pathological demand avoidance’ (PDA) describes a pattern of difficulties increasingly recognised as forming part of the autistic spectrum. Although clinical reports suggest that children with PDA are likely to experience considerable difficulties in education, their educational experiences have not yet been explored in any systematic way. In the current study, 42 parents of children with PDA completed a questionnaire about their child's educational experiences. Parents' responses indicated that this group of children displays high levels of problem behaviours in school, and receives corresponding high levels of special educational need support and professional involvement. Despite this support, the group had experienced high rates of exclusion and placement breakdown, with only 48% now in mainstream education. Parents reported relatively high satisfaction in their children's educational placements, with success defined by parents in terms of child outcomes, school characteristics and PDA‐specific factors. Findings are discussed with reference to what is known about the educational experiences of children with more typical autism spectrum conditions and in terms of the implications for the inclusion of this group of children with complex needs.  相似文献   

Pedagogically bereft! Improving learning outcomes for children with foetal alcohol spectrum disorders     

Barry Carpenter 《British Journal of Special Education》2011,38(1):37-43

Foetal alcohol spectrum disorder (FASD) is the most common non‐genetic cause of learning disability, affecting around 1% of live births in Europe, and costing an estimated $2.9 million per individual across their lifespan. In adulthood, non‐reversible brain damage is often compounded by secondary disabilities in adulthood, such as mental health problems and drug addiction. The challenge for today's educators is: ‘How do we teach children with FASD?’ Their unusual style of learning and their extreme challenging behaviour is out of the experience of many teachers. This article, written by Professor Barry Carpenter, OBE, National Director of the Specialist Schools & Academies Trust Complex Learning Difficulties and Disabilities Research Project, considers the status of FASD in the UK, and provides an overview of the author's recent research into effective educational strategies within the framework of Every Child Matters. Only government‐led approaches can lead to improvements in the quality of teaching and learning for children with FASD and their future life chances.  相似文献