田径短跑摆腿技术动作分析与训练方法研究

短跑是一项竞争激烈且成绩提高缓慢的田径运动项目,现代短跑理论的侧重点已经从后蹬向摆腿进行转移。作为提高跑步速度的重要一环,如何提高运动员的摆腿速度和幅度,成为提升短跑运动员成绩的关键。因此,通过对传统和现代田径短跑理论的对比分析,阐述了现代短跑摆腿技术的特征,并从生物力学的角度分析了短跑摆腿训练方法,提出了切实可行的摆腿技术训练方法,为田径短跑运动员的摆腿技术训练提供参考。     

地埋式垃圾收集系统研究进展

地埋式垃圾收集系统将垃圾回收系统的部分或全部过程转移到地下,可解决现有垃圾回收系统中的误投、拾荒 者翻动、占地面积大、异味四散和二次污染等问题,改善了居住环境并降低了垃圾回收成本。分别从投放装置、容器装置 和安全保护装置等方面对其国内外研究现状进行了论述,介绍了地埋式垃圾收集系统的新型结构方案,方案通过起重臂 控制垃圾收集容器的下开门结构,在地坑中设置混凝土决驱动的安全保护装置及其他辅助装置。地埋式垃圾收集系统 在城市居民垃圾收集领域具有广阔发展空间,垃圾压缩装置等将成为今后垃圾收集系统中不可缺少的部分。     

Citizenship Acquisition of Post-1965 Asian Immigrants

This article examines the citizenship acquisition of major post-1965 Asian immigrant groups including Chinese, Filipinos, Japanese, Asian Indians, Koreans, and Vietnamese, using the PUMS data from the 1990 U.S. Census and an INS longitudinal data set. The analysis of data reveals a very high average naturalization rate of post-1965 Asian immigrants and a bifurcated pattern in citizenship acquisition among the six Asian immigrant groups. Furthermore, the results of a pooled logistic regression model indicate that the characteristics of Asian immigrants, ethnic communities, and countries of origin largely explain the naturalization of these Asian immigrants. Separate logistic regression models for the six groups further uncover similarities and differences in determinants of naturalization across groups. The findings suggest that in terms of naturalization rates new Asian immigrants are more assimilable than most immigrant groups, including European immigrants, and that in the foreseeable future Asian Americans are likely to become a swing vote at the local and possibly state levels and perhaps in presidential elections under some special circumstances. The findings also point to commonality and diversity in determinants of citizenship acquisition among post-1965 Asian immigrants.     

自动穿鞋带机的机械夹爪多目标优化设计

为满足灵活穿鞋带过程中无空间干涉及较大的拉扯力需求,夹鞋带的机械夹爪需刚度足够且结构尽可能小巧, 为此,文中用有限元分析软件ANSYS Workbench对夹爪和连接件进行了静力分析,获取了夹爪和连接件的受力和变形情 况。为尽可能避免机械手与鞋面、夹具之间的干涉,运用优化模块Design Exploration,对夹爪和连接件进行了多目标优 化,在夹爪与连接件满足许用应力和最大位移变形的要求下,缩小了夹爪和连接件的结构尺寸。机械手静力分析表明： 机械手满足许用应力和最大位移变形的要求。     

T形刚构桥转体施工技术

结合某工程，详细介绍了T型刚构桥水平转体施工技术，包括转盘设计改进，转体箱梁现浇施工和转体施工过程。本工程的顺利合龙证明所采用的各项技术措施可行，为今后同类桥梁施工积累了经验。     

降低挠性剑杆织机剑带消耗的几个途径

本文在分析了剑带易损的主要原因的基础上，提出了一些避免不必要损耗的方法。     

证券内部人员短线交易认定与选择性研究

内幕交易中的短线交易是一个新问题 ,涉及到交易主体、非法所得的处理、股东请求权的行使等一系列问题 ,特别是对法人与自然人从事短线交易的资格认定上 ,理论界和司法界的认识与看法均存在分歧。首先我们应该对短线交易中的许多关键问题有一个正确的选择 ,才能在司法实践中行之有效地打击短线交易行为。     

谈短跑技术专门性练习

短跑技术的发展,已变"后蹬型"为"摆动型"跑法,加快前摆的速度,充分地利用塑胶跑道弹性,是当代短跑技术的主要特征.     

Throughput Optimization in Constant Travel‐Time Dual Gripper Robotic Cells with Parallel Machines

Constant travel‐time robotic cells with a single gripper robot and with one or more machines at each processing stage have been studied in the literature. By contrast, cells with a dual gripper robot, although more productive, have so far received scant attention, perhaps due to their inherent complexity. We consider the problem of scheduling operations in dual gripper robotic cells that produce identical parts. The objective is to find a cyclic sequence of robot moves that minimizes the long‐run average time to produce a part or, equivalently, maximizes the throughput. We provide a structural analysis of cells with one or more machines per processing stage to obtain first a lower bound on the throughput and, subsequently, an optimal solution under conditions that are common in practice. We illustrate our analysis on two cells implemented at a semiconductor equipment manufacturer and offer managerial insights for assessing the potential productivity gains from the use of dual gripper robots.     

人行天桥钢斜塔整体竖转提升施工技术

天津泰达人行天桥是一座单斜塔密索钢结构斜拉桥，由于施工过程中泰达大街不能断交，所以钢斜塔的安装就成为本工程的重难点，经过比选分析，采用整体竖转提升法施工，实现了施工不中断交通的目标，避免了高空作业安装，保证了安装精度和安装质量。详细介绍了钢斜塔的构造、提升设计、主要施工过程和施工方法，对今后同类工程施工有一定的借鉴意义。