科创中国

Quadruped robots consume a lot of energy,which is one of the factors restricting their application.Energy efficiency is one of the key evaluating indicators for walking robots.The relationship between energy and elastic elements of walking robots have been studied,but different walking gait patterns and contact status have important influences on locomotion energy efficiency,and the energy efficiency considering the foot-end trajectory has not been reported.Therefore,the energy consumption and energy efficiency of quadruped robot with trot gait and combined cycloid foot trajectory are studied.The forward and inverse kinematics of quadruped robot is derived.The combined cycloid function is proposed to generate horizontal and vertical foot trajectory respectively,which can ensure the acceleration curve of the foot-end smoother and more successive,and reduce the contact force between feet and environment.Because of the variable topology mechanism characteristic of quadruped robot,the leg state is divided into three different phases which are swing phase,transition phase and stance phase during one trot gait cycle.The non-continuous variable constraint between feet and environment of quadruped robot is studied.The dynamic model of quadruped robot is derived considering the variable topology mechanism characteristic,the periodic contact and elastic elements of the robot.The total energy consumption of walking robot during one gait cycle is analyzed based on the dynamic model.The specific resistance is used to evaluate energy efficiency of quadruped robot.The calculation results show the relationships between specific resistance and gait parameters,which can be used to determine the reasonable gait parameters.

For planning optimum multiple stresses accelerated life test plans, a commonly followed guiding principle is that all parameters of the life-stress relationship should be estimated, and the number of the stress level combinations must be no less than the number of parameters of the life-stress relationship. However, the general objective of an accelerated life test(ALT) is to assess the p-th quantile of the product life distribution under normal stress. For this objective, estimating all model parameters is not necessary, and this will increase the cost of test. Based on the theoretical conclusion that the stress level combinations of the optimum multiple stresses ALT plan locate on a straight line through the origin of coordinate, it is proposed that a design idea of planning the optimum multiple stresses ALT plan through transforming the problem of designing an optimum multiple stresses ALT plan to designing an optimum single stress ALT plan. Moreover, a method of planning the optimum multiple stresses ALT plan which can avoid estimating all model parameters is established. An example shows that, the proposed plan which only has two stress level combinations could achieve an accuracy no less than the traditional plan, and save the test time and cost on one stress level combination at least; when the actual product life is less than the design value, even the deviation of the model initial parameters value is up to 20%, the variance of the estimation of the p-th quantile of the proposed plan is still smaller than the traditional plans approximately 25%. A design method is provided for planning the optimum multiple stresses ALT which uses the statistical optimum degenerate test plan as the optimum multiple stresses accelerated life test plan.

通过对系统平面布置方法SLP的分析,阐述了SLP方法在粮食物流中心内部规划布局中的应用,证明了SLP方法在粮食物流中心规划设计中的可行性.通过对假设模拟物流中心的分析,最终得出了粮食物流中心的基本布局图,旨在对以后粮食物流中心的规划设计起到指导作用.

目的 调查实习男护生职业生涯规划现状,为其职业规划指导提供依据.方法 采用一般资料调查表和护理专业大学生个人职业生涯规划问卷对67名临床实习的男护生进行凋查.结果 67名实习男护生职业生涯规划总均分为(89.37±13.62)分处于中等偏下水平,其中就业信心因子得分最低为(11.62±1.52)分.学历、学生干部经历、是否第一志愿报考护理专业、职业生涯指导课程经历等因素是实习男护生职业生涯规划的影响因素.结论 护理专业学生工作中应该制订针对男护生的职业指导体系,从而帮助男护生科学规划、合理就业和个人在职业生涯中的全面、可持续发展.

糯扎渡水电站绿色水电工程建设规划从生态环境保护和修复、环境保护管理、关键技术问题研究3个方面展开.介绍了糯扎渡绿色水电工程建设规划的意义、概念、指标和主要内容,并且概要说明了糯扎渡水电站建设过程中实施绿色水电工程建设规划的基本情况.实践表明,规划及其实施对于糯扎渡水电站和澜沧江流域水电开发实现可持续发展目标提供了支持,也可以为我国水电行业生态环境保护工作的深入开展提供有益的借鉴.

Wear is a major factor of disc cutters' failure. No current theory offers a standard for the prediction of disc cutter wear yet. In the field the wear prediction method commonly used is based on the excavation length of tunnel boring machine(TBM) to predict the disc cutter wear and its wear law, considering the location number of each disc cutter on the cutterhead(radius for installation); in theory, there is a prediction method of using arc wear coefficient. However, the preceding two methods have their own errors, with their accuracy being 40% or so and largely relying on the technicians' experience. Therefore, radial wear coefficient, axial wear coefficient and trajectory wear coefficient are defined on the basis of the operating characteristics of TBM. With reference to the installation and characteristics of disc cutters, those coefficients are modified according to penetration, which gives rise to the presentation of comprehensive axial wear coefficient, comprehensive radial wear coefficient and comprehensive trajectory wear coefficient. Calculation and determination of wear coefficients are made with consideration of data from a segment of TBM project(excavation length 173 m). The resulting wear coefficient values, after modification, are adopted to predict the disc cutter wear in the follow-up segment of the TBM project(excavation length of 5621 m). The prediction results show that the disc cutter wear predicted with comprehensive radial wear coefficient and comprehensive trajectory wear coefficient are not only accurate(accuracy 16.12%) but also highly congruous, whereas there is a larger deviation in the prediction with comprehensive axial wear coefficient(accuracy 41%, which is in agreement with the prediction of disc cutters' life in the field). This paper puts forth a new method concerning prediction of life span and wear of TBM disc cutters as well as timing for replacing disc cutters.

利用广州南沙区气象探测基地2010年O3浓度和常规气象观测资料,分析了O3浓度变化特征及其气象因子的关系.结果表明,广州南沙区2010年O3浓度最高时均值的最大值出现在8月,超标时数最多的是9月;O3浓度日变化呈单峰型分布,O3浓度日变化最大的季节是秋季,其次为夏季、春季、冬季;O3浓度呈现秋季〉春季〉夏季〉冬季的变化特征.气温、相对湿度、日照时数和云量与O3浓度相关系数大,是影响南沙O3浓度的主要气象因子.秋季O3浓度高,O3主要以局地光化学反应生成为主;春季、夏季和冬季O3主要以外来源的输送为主.气团后向轨迹分析表明南沙区秋季气团主要来自污染的大陆地区,春季、夏季和冬季气团主要是来自东南沿海附近或较为清洁的南海.