科技评价指标值与评价属性背离及修正研究——基于多属性评价视角     

周娟美  郭强华  王作功  俞立平 《图书情报工作》2018,62(22):100-108

[目的/意义] 分析科技评价中指标区分度异常、数据分布有偏的深层次原因,认为本质上这是评价指标值与评价属性的背离现象,即评价指标值不能较好地体现评价属性的本质含义。[方法/过程] 提出一种新的降低评价指标值与评价属性背离的方法--对数中位数标准化,并以JCR2016数学期刊为例进行实证分析。[结果/结论] 研究结果表明：引文指标更容易出现评价指标值与评价属性背离问题;可以从多角度判定评价指标值与评价属性背离问题,如指标内涵分析、及格率、离散系数、中位数极大值比、集中度指数HHI等;采用对数中位数标准化可以大幅降低评价指标值与评价属性背离问题;建议评价中如出现指标值与属性背离,采用对数中位数处理后的数据进行评价。  相似文献   

基于多视角分析的跆拳道横踢技术研究     

王鸣骏 《体育科技》2013,(6):50-52

通过对跆拳道运动发展的现状具体分析,从这种运动的动作特性出发,从生物力学、安全性、运动学等角度对横踢技术进行深入研究,对揭示其内在规律,探究适合国人的跆拳道运动方针政策,具有重要的意义;在跆拳道教学实践当中,为跆拳道横踢技术的训练方式、教学指导方法的确定,提供相应的理论依据.  相似文献   

学生评教成绩与教师教学质量之间的关系研究     

逯凯萍  樊顺厚 《中国科教创新导刊》2012,(32):45-46,48

本文应用秩检验以及中位数检验对学生评教成绩与学生考试成绩之间的关系进行了研究,并分析了评教成绩与评教指标之间的关系,得到教师的学生评教成绩与学生考试成绩之间存在显著的正线性相关关系,从而否定了部分教师因害怕影响评教得分而采取放任学生的做法.  相似文献   

数字图像噪声抑制算法比较研究   总被引：1，自引：0，他引：1  

关雪梅 《廊坊师范学院学报(自然科学版)》2012,12(5):40-42

图像噪声抑制是图像处理的一个不能忽视的重要步骤,对图像处理的后续工作有着不可忽视的影响。为此,介绍三种经典的图像噪声抑制滤波方法,并讨论均值滤波方法、中值滤波方法及维纳滤波方法的典型运用,同时进行对比分析,最后得出这三种方法各自的自适应特点。  相似文献   

足球前场80个成功任意球战术初探   总被引：1，自引：0，他引：1  

马连芳 《体育科研》1999,(4)

通过对15届世界杯足球赛、'96欧洲足球锦标赛和意大利、英国、德国、西班牙、荷兰、巴西等国国内联赛共100多场高水平比赛中所收集到的80个前场任意球成功战例战术进行分析研究。结果表明:距离球门30米左右的中间区域是任意球得分的最佳区域;任意球进攻的战术方法以简练实用为宜,若情况允许尽可能直接射门;一次配合战术以中路一拨后射门和左、右两区域的传中后头球射门为主要配合方法。  相似文献   

Three-dimensional kinematics and ground reaction forces during the instep and outstep soccer kicks in pubertal players     

Athanasios Katis  Eleftherios Kellis 《Journal of sports sciences》2013,31(11):1233-1241

Abstract

The purpose of the present study was to compare the three-dimensional kinematics of the lower extremities and ground reaction forces between the instep kick and the kick with the outside area of the foot (outstep kick) in pubertal soccer players. Ten pubertal soccer players performed consecutive kicking trials in random order after a two-step angled approach with the instep and the outstep portion of the foot. Three-dimensional data and ground reaction forces were measured during kicking. Paired t-tests indicated significantly higher (P < 0.05) ball speeds and ball/foot speed ratios for the instep kick compared with the outstep kick. Non-significant differences in angular and linear sagittal plane kinematic parameters, temporal characteristics, and ground reaction forces between the instep and outstep soccer kicks were observed (P > 0.05). In contrast, analysis of variance indicated that the outstep kick displayed higher hip internal rotation and abduction, knee internal rotation, and ankle inversion than the instep kick (P < 0.05). Our results suggest that the instep kick is more powerful than the outstep kick and that different types of kick require different types of skill training.  相似文献   

利用微分法证明不等式     

夏必腊  田玉敏  许道军 《佳木斯教育学院学报》2012,(1):120-120

在理工科的《数学分析》中,不等式的证明是至关重要的。本文结合教学案例从利用函数的单调性、利用极值方法、利用拉格朗日中值定理、利用泰勒公式等方面给出了用微分法证明不等式的几种常用方法和技巧。  相似文献   

A systematic review of propulsion from the flutter kick – What can we learn from the dolphin kick?     

Jordan T. Andersen  Ross H. Sanders 《Journal of sports sciences》2018,36(18):2068-2075

Propulsion, one of the most important factors in front crawl swimming performance, is generated from both the upper and lower limbs, yet little is known about the mechanisms of propulsion from the alternating movements of the lower limbs in the flutter kick (FK). The purpose of this systematic review was to review the literature relating to the mechanisms of propulsion from FK in front crawl. There was limited information about the mechanisms of propulsion in FK. Since movements of the lower limbs are similar between FK and the dolphin kick (DK), mechanisms of propulsion from DK were reviewed to better understand propulsion from FK. Recent evidence suggests that propulsion in DK is generated in conjunction with formation and shedding of vortices. Similar vortex structures have been observed in FK. Visualisation and simulation techniques, such as particle image velocimetry (PIV) and computational fluid dynamics (CFD), are non-invasive tools that can effectively model water flow without impacting swimming technique. These technologies allow researchers to estimate the acceleration of water and, consequently, the propulsive reaction forces acting on the swimmer. Future research should use these technologies to investigate propulsion from FK.  相似文献   

可见光视频图像中的船舶目标自适应检测     

张恒  杨家轩  周洋宇  姜苗苗  王毓玮 《上海海事大学学报》2021,42(1):33-38

为降低海事监控视频图像背景中运动物体引起的杂波和噪声对船舶目标检测的影响,根据采集的可见光视频图像特性,提出一种海天背景下船舶目标自适应检测算法。将待检测图像进行预处理,使用自适应中值滤波和均值漂移(mean-shift)滤波对图像进行滤波去噪。采用密度峰聚类对传统K均值聚类算法进行改进,自适应确定初始聚类中心及其数量。对海面船舶进行自适应聚类分割。仿真实验显示:该算法的检测准确率为90.3%,验证了其准确性和可靠性;单帧视频图像的船舶目标检测用时可控制在100 ms以内,满足实时检测的要求。结果表明:该算法可以实现海天背景下船舶目标的准确、快速检测,为海上船舶目标跟踪奠定了可靠的基础。  相似文献   

Windows应用程序的自动登录     

余永武 《绵阳师范学院学报》2010,29(2):94-98

针对目前计算机应用越来越多,需要记忆大量登录密码的问题,利用Delphi编程,使用DLL导出函数和Windows鼠标钩子消息处理等技术,实现了Windows应用程序的自动登录。采用本方法可以提高工作效率及安全性。  相似文献