散打鞭腿与泰拳横扫踢技术动作对比分析

多年来,散打和泰拳经历了多次较量,互有胜负,同时在比赛中也看到许多要相互学习的很多地方,总体上泰拳更凶猛,而散打则是技巧性更强。本文通过对二者的腿法中常用的鞭腿和横扫提的训练方法、技术特点以及在比赛中的运用等情况进行对比分析,为两者以后的发展提供借鉴。     

扫描光屏法在PIV技术测量自由剪切层中的应用

ＰＩＶ技术是九十年代实验流体力学的重大成就。它能够提供瞬时整个流场的定量信息，而且具有很高的空间分辨率和很好的精度。为了获得清晰可靠的ＰＩＶ底片，人们对实验方法作了很多改进。本文讨论了近年使用较多的扫描光屏法，提出了该方法在使用中特别注意的一些问题，并给出了用该方法测量自由剪切流场的结果。     

提高对雷达隐蔽扫描角跟踪系统干扰性能的研究

分析了对隐蔽扫描雷达角跟踪系统实施匀速扫频式干扰的缺点。提出了一种实现快速一慢速扫频的方法，即先快速扫描以捕捉雷达角扫描频率范围，再在此小范围内进行慢扫。以确定敌方雷达的角扫描频率。文中还给出了改进的系统结构和主要电路框图，并结合该系统的改进内容针对研究中的主要技术难点作了详细的分析。     

基于DDS的毫米波汽车防撞雷达扫频源设计

利用直接数字频率合成(DDS)分辨率高、转换速度快的特点,设计了一种基于DDS芯 片AD9910的毫米波汽车防撞雷达扫频信号源。通过DDS芯片产生调频、调幅、调相等各 种调制信号,实现了在短距离内快速捕捉目标、处理信息、发出告警的功能。所 设计的扫频源输出信号中心频率为8.6 GHz,幅度为-16 dBm,相噪为-70 dBc/Hz@ 1 kHz,满 足了在多目标检测时对信号源的幅度、稳定度和相噪的要求,从而使DDS技术得以在微波检 测领域获得应用。     

清仓机安全操作防范措施

物料在仓内较长时间储存时,有可能产生板结、结拱以及仓壁挂粮现象,需人工对此破除后,清仓机才能进行正常清仓作业。在板结、结拱和仓壁挂粮破除作业中,有些企业由于管理者和操作人员缺乏安全防范意识和必要的安全操作措施,常出现人员伤亡事故发生。针对这些问题进行探讨并提出相应的防范措施。     

Comparison of littoral and deep water sampling methods for assessing macroinvertebrate assemblages along the longitudinal profile of a very large river (the Danube River,Europe)

We comparatively examined the role of littoral and deep water sampling methods in assessing macroinvertebrate assemblages and in characterizing longitudinal changes in assemblage structure along >2,500‐km–long course of the Danube River, Europe. The effectiveness of detecting taxa corresponded well with an inshore–offshore gradient in sampling (i.e., distance from shore). Nevertheless, each method (i.e., littoral multihabitat sampling, kick and sweep sampling, and deep water dredging) contributed to some degree to overall taxa richness and species composition. Sampling in different depth zones characterized different assemblages, and consequently, inshore–offshore position was at least as important determinant of assemblage structure as longitudinal position of sampling sites in the river. Although we found significant congruency in the spatial variability of assemblages among the sampling methods, the relationships were only moderate. Our study on the large Danube River confirms studies from smaller rivers in other geographic regions that littoral monitoring provides higher taxa richness and more responsive changes to longitudinal gradients than deep water samples. Nevertheless, it also shows that sampling in different depth zones provides supplementary information on assemblage structure. Understanding changes in macroinvertebrate assemblages related to differences in sampling method is crucial to improve the bioassessment and environmental management of large rivers.     

一种改进的物流配送车辆调度启发式算法

针对物流配送中的车辆调度问题,提出了一种改进的启发式算法。该算法基于sweep算法和用于解决旅行商问题(TSP)的Cheapest Insertion算法,是一种二阶段算法。这种启发式算法首先使用sweep算法将所有顾客分派给运输车辆,然后对每辆车按照TSP的解决方法解决该车上的TSP问题。本算法比较有效的解决了有时间窗的车辆调度问题,可以用来构造某些业启发式算法的初始解。     

基于流管法的面积波及效率计算方法研究

中国已开发的大多数油田,经过多年的加密调整和注水开发,目前已处于高含水或高采出程度阶段,开采和稳产难度越来越大。因此,对注水开发油田进行水驱面积波及系数的研究意义重大。根据注水油田的基本特点,基于流管法建模基本原理,建立了五点法流管模型,利用BeckleyLeverett方程,结合单元分析法和流线积分法,对注水油田五点法井网面积波及效率的计算公式进行了详细推导,绘制并分析了面积波及系数和采出程度随时间的变化曲线。结果表明:当无流管突破时,注水油田的面积波及系数随时间的增加而线性增大;当主流管突破见水后,波及系数增大程度越来越慢,最后趋于平缓。当油田被注入水完全波及后,继续利用注水提高采收效果的作用很小,水驱效率明显降低。研究结果对于注水油田面积波及系数的求解及水驱动态开发规律的研究具有借鉴意义。     

Intermarket sweep order trade size clustering around corporate announcements

Investors have different trade size preferences depending on their information advantage. Using intermarket sweep orders (ISOs), we find that investors appear to prefer using small, round lot trades around corporate events with higher announcement frequency and more predictable timing, such as earnings announcements. Around these corporate events, information is revealed, and analyst estimates are confirmed or rejected. Conversely, share repurchase announcements happen less frequently and the timing of these announcements are unpredictable. Relative to earnings announcements, share repurchase announcements create more uncertainty than they resolve. We find that when investors have less information, they tend to use costlier, larger trade size multiples. We further support the extant finding that trade sizes are smaller with the advent of high-frequency trading.     

冯家山一级电站水轮发电机扫膛事故的处理方法

针对冯家山一级电站1#水轮发电机的扫膛事故,分析了事故原因,介绍了事故处理方法.由于在机组解体、修理、回装三个方面采取了合理的工艺措施,保证了水轮发电机的检修质量