Zero-voltage switching converter absorbing parasitic parameters for super high frequency induction heating

This paper presents a novel mega-Hz-level super high frequency zero-voltage soft-switching converter for induction heating power supplies. The prominent advantage of this topology is that it can absorb both inductive and capacitive parasitic components in the converter. The switch devices operate in a zero-voltage soft-switching mode. Consequently, the high voltage and high current spikes caused by parasitic inductors or capacitors oscillation do not occur in this circuit, and the high power loss caused by high frequency switching can be greatly reduced. A large value inductor is adopted between the input capacitor and the switches, thus, this novel converter shares the benefits of both voltage-type and current-type circuits simultaneously, and there are no needs of dead time between two switches. The working principles in different modes are introduced. Results of simulation and experiments operated at around 1 MHz frequency verify the validity of parasitic components absorption and show that this convener is competent for super high frequency applications.     

一种新的径向导热界面参数插值格式

以变系数径向导热问题为研究对象,由傅里叶导热定律提出了较之文献更为合理的热导计算方法.根据流的相容性原理分别推导得出极坐标、柱坐标和球坐标系下新的界面半径和界面导热系数插值格式.通过几个变系数和非线性导热问题对插值格式进行考核,并与文献中的插值格式进行对比.结果表明,推导的格式充分考虑了变截面和变物性的综合影响,对于非线性和变系数导热问题能得到更精确的结果.     

Information-governing dynamics of attacker–defender interactions in youth rugby union

Abstract

Previous work on dynamics of interpersonal interactions in 1 vs. 1 sub-phases of basketball has identified changes in interpersonal distance between an attacker and defender as a potential control parameter for influencing organizational states of attacker–defender dyads. Other studies have reported the constraining effect of relative velocity between an attacker and defender in 1 vs. 1 dyads. To evaluate the relationship between these candidate control parameters, we compared the impact of both interpersonal distance and relative velocity on the pattern-forming dynamics of attacker–defender dyads in the sport of rugby union. Results revealed that when interpersonal distance achieved a critical value of less than 4 m, and relative velocity values increased or were maintained above 1 m · s^?1, a successful outcome (i.e. clean attempt) for an attacker was predicted. Alternatively, when values of relative velocity suddenly decreased below this threshold, at the same critical value of interpersonal distance, a successful outcome for the defender was predicted. Data demonstrated how the coupling of these two potential, nested control parameters moved the dyadic system to phase transitions, characterized as a try or a tackle. Observations suggested that relative velocity increased its influence on the organization of attacker–defender dyads in rugby union over time as spatial proximity to the try line increased.     

一阶随机系数模型一阶平稳的条件

本文给出了时序模型:X_1=ε_1+((?)+η)X_(1-1)一阶平稳的条件,并提出了随机格林函数的概念.     

氢氘原子光谱实验最优参数的确定

为了获得了清晰的氢氘原子光谱谱线,首先确定了对光谱谱线有影响的负高压及狭缝宽度2个实验参量。先选定氢原子的一条谱线,在一定的负高压下,通过改变狭缝宽度来获取不同组光谱谱线,经分析得到理想的狭缝宽度范围。在该范围内选取几条狭缝宽度,分别通过改变负高压来得到理想的最优参数组。实验发现,对于不同的波长最优参数组参数不同,因此又用同样的方法对其他的谱线进行了探究,找到不同谱线的公共最优参数区间,最终获得了清晰的氢原子光谱谱线。     

椭球封头卧式储油罐的变位影响

探讨椭球封头卧式储油罐的纵向变位对罐容表的影响。本文分别建立了椭球封头卧式储油罐的无偏模型V=V0（H）和纵向偏转模型V=Vα（H）,对比研究纵向变位参数α对椭球封头卧式储油罐的罐容表的影响。对于给定的一组椭球封头卧式储油罐数据和较小的纵向变位参数α,分析误差并证明了模型的可靠性。     

对我国部分优秀女子背越式跳高运动员最后4步助跑技术的运动学分析

采用高速摄影法对我国4名优秀女子跳高运动员的最后4步助跑技术进行三维运动学分析。结果表明：我国运动员身体重心水平速度偏低,助跑角度合理,助跑曲线符合跳高技术要求,2名研究对象内倾角在合理范围之内,顾碧威倒数第4、3步内倾角偏大,沈勤莉最后1步内倾角偏大。     

锚注支护在软岩巷道中的应用

叙述了潘三矿软岩巷道的特征，锚注支护设计参数的确定与工程应用情况，表明锚注支护是软岩支护的一种有效方案。     

2007年田径冠军赛男子跳高运动员起跳技术的运动学分析

对2007年全国田径冠军赛男子跳高项目前六名运动员最好一次试跳起跳技术进行三维运动学分析,结果表明：被试H2远低于世界优秀选手;根据起跳时运动员质心降低的方式,将本次跳高运动员起跳技术分为三类：低-高型、高-低型、低-平型;助跑平均水平速度和起跳垂直速度分量小;起跳阶段水平速度损失值与起跳离地瞬间重心垂直速度呈显著性正相关性;起跳腿离地瞬间膝关节蹬伸较充分。     

排球单、双脚起跳扣球人体重心的运动学特征比较分析

通过三维高速摄像和图像解析法,分析排球后排单、双脚起跳扣半快球起跳阶段人体重心速度、位移和时间特征。结果表明,单脚起跳运用到后排快攻可有效提高人体重心垂直速度,增加垂直位移,明显地缩短缓冲时间,有利于快速蹬伸。