基于磁钉技术的集装箱码头AGV 定位精度分析

为解决自动导引车（Automated Guided Vehicle, AGV）的定位精度问题,以国内某在建的自动化集装箱码头为工程背景,研究与基于磁钉技术的AGV定位误差相关的因素.通过给出AGV惯性导航系统的运动方程和误差方程,按照工程实况,在忽略陀螺仪影响的基础上,得到AGV惯性导航系统位置误差的理论计算式.依此指出,基于磁钉技术的AGV组合导航系统定位精度与加速度计精度、AGV 运行方向的余弦、磁钉数据更新时间的平方成正比例关系.最后,对某工程算例进行数值仿真,验证了理论分析的正确性.该方法对磁钉排布、惯性导航系统传感器选型等有参考意义.     

跳远运动员助跑速度感知能力训练对踏板准确性影响的实验研究

通过问卷调查和实验法对跳远运动员助跑踏板准确性和影响跳远运动员助跑速度感知能力的主要因素进行理论与逻辑分析,根据跳远专项特点优选出9种训练方法,实验组采用优选训练手段,对照组采用常用普通训练手段。在严格控制训练过程及训练条件下,进行为期16周的速度感知能力的训练,保证两组只在训练内容方面不同外,其余方面保持一致。实验后对实验组和对照组再次进行踏板准确性和跳远成绩的测定,结果表明:实验后实验组与对照组的跳远成绩与踏板准确性具有明显的差异性。     

单源三站外辐射源雷达目标探测性能

论述全向外辐射源雷达空中目标探测系统的主要问题及系统体制损失。针对单源单站（SISO）和单源三站（SITO）两种工作方式,在接收天线阵元数相同的情况下分析探测距离和定位精度。在单源三站条件下推导直角坐标系中的目标速度矢量表达式,并分析速度测量精度。研究结果表明,在一定条件下,单源三站组网方式的空间覆盖范围与单源单站相当,且具有平面定位精度较高,可获得目标速度矢量和技术实现难度小的特点。     

Systematic Comparison of Decision Accuracy of Complex Compensatory Decision Rules Combining Multiple Tests in a Higher Education Context

This real‐data‐guided simulation study systematically evaluated the decision accuracy of complex decision rules combining multiple tests within different realistic curricula. Specifically, complex decision rules combining conjunctive aspects and compensatory aspects were evaluated. A conjunctive aspect requires a minimum level of performance, whereas a compensatory aspect requires an average level of performance. Simulations were performed to obtain students' true and observed score distributions and to manipulate several factors relevant to a higher education curriculum in practice. The results showed that the decision accuracy depends on the conjunctive (required minimum grade) and compensatory (required grade point average) aspects and their combination. Overall, within a complex compensatory decision rule the false negative rate is lower and the false positive rate higher compared to a conjunctive decision rule. For a conjunctive decision rule the reverse is true. Which rule is more accurate also depends on the average test reliability, average test correlation, and the number of reexaminations. This comparison highlights the importance of evaluating decision accuracy in high‐stake decisions, considering both the specific rule as well as the selected measures.     

The science and medicine of cricket: an overview and update

Abstract

Research into the science and medicine underlying cricket performance and injury has progressed since the First World Congress of Science and Medicine in Cricket in 1999. This review covers material on the physiological and psychological demands of the game and preparation for it, the biomechanics and motor control of cricket skills, the psychology of team dynamics, performance analysis and cricket injuries. Technological aspects of cricket equipment are also covered, where such research could influence injury risk or player performance. Fielding remains the least studied of the skills. Much more research needs to be done before we can gain a full understanding of the scientific aspects of the game. There is a need to address common definitions of injury, along with more research into injury mechanisms. Research on batting needs to bring together motor control and biomechanics more fully. The fitness demands of the game are still poorly understood, along with the mechanisms causing fatigue. Evaluation of the efficacy of intervention strategies needs to continue and to develop. The applications of research need to be communicated more to coaches and players — for example, in team dynamics — so that they can be applied, and tested further, in international matches.     

浅谈系统误差的发现与消除

系统误差是影响测量结果精确度的主要因素,然而它又常不明显的表现出来。当它被忽视时,有时会对实验结果带来严重的影响,因此找出系统误差,算出它对结果的影响,设法修正或消除它的影响,是误差分析的一个重要内容。总结系统误差可能出现的几种类型,针对这几个类型,给出发现与消除系统误差的方法。     

钢筋混凝土框架结构的改进模态分析

本文利用有限元分析软件SAP2000对一座十五层钢筋混凝土框架结构进行改进模态Pushover分析,并将其结果与动力时程方法进行比较。由于该方法所得结果考虑了高阶振型的影响,其结果有较高的准确性。     

BP神经网络预测边坡稳定性

利用BP神经网络对边坡稳定性进行预测,考虑到岩土体的物理力学性质、边坡参数等对边坡稳定性有影响的各种因素,通过训练和检验的对比,证明该方法可以满足精度要求,进一步验证了该方法在预测边坡稳定性方面的可靠性,具有一定的推广价值。     

管理层业绩预告与分析师盈余预测的相互影响：研究现状与启示

统计模型以外,关于公司未来业绩的信息主要来自两个方面：管理层业绩预告和分析师盈余预测。现有研究发现,管理层可以通过业绩预告的发布时间、精度、准确度以及以往的预告声誉等因素影响分析师盈余预测;分析师则可以通过其对市场预期的影响力促使管理层及时披露准确的业绩预告。本文回顾了中美两国关于管理层和分析师互相影响的主要文献,指出了中国现有研究存在的差距,借以发现未来的研究机会。     

研究平抛物运动实验成功之关键

在研究平抛物运动的实验中，只要注意做好关键的六点，实验就会成功，描出的平抛物运动轨迹比较准确，求出的初速度误差较小。