Dexterous workspace optimization of an asymmetric six-degree of freedom Stewart–Gough platform type manipulator

In this paper, an asymmetric Generalized Stewart–Gough Platform (GSP) type parallel manipulator is designed by considering the type synthesis approach. The asymmetric six-Degree Of Freedom (DOF) manipulator optimized in this paper is selected among the GSPs classified under the name of 6D. The dexterous workspace optimization of Asymmetric parallel Manipulator with tEn Different Linear Actuator Lengths (AMEDLAL) subject to kinematics and geometric constraints is performed by using the Particle Swarm Optimization (PSO). The condition number and Minimum Singular Value (MSV) of homogenized Jacobian matrix are employed to obtain the dexterous workspace of AMEDLAL. Finally, the six-DOF AMEDLAL is also compared with the optimized Traditional Stewart–Gough Platform Manipulator (TSPM) considering the volume of the dexterous workspace in order to demonstrate its kinematic performance. Comparisons show that the manipulator proposed in this study illustrates better kinematic performance than TSPM.     

石英热释光年代测定中测量条件优化研究

本文基于石英热释光特性分析,通过实验方法分析石英在不同辐照剂量下375 ℃热释光峰的最佳预热温度和校正石英热释光灵敏度变化的最佳试验剂量,并依据实验结果对常规流程加以改进。最终,验证基于最优测量参数的改进流程对等效剂量测量准确度的提升。实验结果表明,若等效剂量较小,325 ℃热释光峰的信号较弱,选取较低的预热温度即可压制其对375 ℃热释光峰的影响。若等效剂量较大,则石英测片应先通过预热温度测试,根据再生剂量和试验剂量的最优预热温度进行等效剂量测量。石英测片再生剂量的取值处于0～1 000 Gy范围内时,200 Gy的试验剂量能对石英测片的热灵敏度变化起到校正作用,且10次重复测量结果的相对偏差小于5%。通过上述最优预热温度和试验剂量设置,分别降低325 ℃热释光峰残余信号干扰和校正石英热灵敏度变化。改进流程下400 Gy和700 Gy等效剂量测量值的相对偏差由常规流程的14.74%～47.15%和33.47%～197.71%均降低到±4%以内。本文为石英的375 ℃热释光峰年代测定准确度和年代测定范围的提升提供了重要参考依据。     

自动化汽车灯色度测试仪的原理与结构

介绍了一种自动测试汽车车灯色度仪器的设计原理、结构框图和精度分析。仪器采用微机控制、数据采集、标准判别和表格打印, 是车灯行业理想的测试仪器。     

Acid/base and hydrogen bonding effects on the proton-coupled electron transfer of quinones and hydroquinones in acetonitrile: Mechanistic investigation by voltammetry, H NMR and computation

This report seeks to address the role of hydrogen bonding with Brønsted acids and bases in proton-coupled electron transfer (PCET) as it pertains to concerted or stepwise pathways of quinone (Q) and hydroquinone (QH₂) electrochemistry. This study was performed using a series of techniques that included cyclic voltammetry (CV), digital simulations, computational chemistry and ¹H NMR. Hydrogen bonding was inferred by a decrease in diffusion coefficient (D) values measured using a pulsed gradient echo- (PGE-) ¹H NMR technique. Changes of 40.8% and 37.9% in D values were only noted after the addition of two equivalents of acetate to 1,4-hydroquinone (1,4-QH₂) and catechol (1,2-QH₂), respectively. In contrast, the D values for the addition of selected amines (pyridine, N,N-diisopropylethylamine and triethylamine) changed only 3.2% on average. Quantum mechanical calculations were conducted to determine the pK_a of all quinoid species to serve as a starting point for the determination of equilibrium constants in voltammetric simulations. Simulations indicate that 1,4-benzoquinone undergoes stepwise electron-proton transfer upon addition of acetic acid, N-ethyldiisopropylammonium perchlorate and pyridinium nitrate and were simulated without the presence of hydrogen bonds. The QH₂ compounds show stepwise proton-electron transfers after addition of the both the conjugate amines and acetate.     

Multiple steady states in combined buoyancy and wind driven natural ventilation: The conditions for multiple solutions and the critical point for initial conditions

Natural ventilation systems may have multiple steady states in the combined buoyancy and wind driven mode in a single space. In this paper, dynamical system analysis is applied both graphically and quantitatively to investigate the multiple steady state behavior of such a natural ventilation system.     

基于改进GSO的裂解炉原料切换策略研究(英文)

The scheduling process of cracking furnace feedstock is important in an ethylene plant. In this paper it is described as a constraint optimization problem. The constraints consist of the cycle of operation, maximum tube metal temperature, process time of each feedstock, and flow rate. A modified group search optimizer is pro-posed to deal with the optimization problem. Double fitness values are defined for every group. First, the factor of penalty function should be changed adaptively by the ratio of feasible and general solutions. Second, the“excel-lent”infeasible solution should be retained to guide the search. Some benchmark functions are used to evaluate the new algorithm. Final y, the proposed algorithm is used to optimize the scheduling process of cracking furnace feedstock. And the optimizing result is obtained.     

智能电网评估指标体系的构建方法

智能电网评估指标体系是科学评估智能电网发展水平和效用、指导智能电网趋优运营的载体,是智能电网建设的基础。文中将指标体系划分为战略指标集和过程指标集2个层次,其中,战略指标集是智能电网的宏观表象,过程指标集则表征其中的微观因素,两者形成紧密的指标链。从智能电网利益相关者的需求出发,建立多层、多级的需求体系结构,在此基础上...     

谈我国企业核心竞争力的培育

核心竞争力是当前的一个热点研究课题，也是企业生存和发展的永续之道。本文仅从微观管理角度，既借鉴国外学者的研究成果，又联系企业的实际，对我国企业核心竞争力的培育问题，展开研讨。核心竞争力是企业逐步形成的一种战胜竞争对手的根本能力。它是别的企业不可能学会或模仿的深层能力。开展核心竞争力培育的研究，不仅关系到企业的生存与发展，而且关系到一个国家的综合国力的强弱。     

谈谈马克思主义理论课教师世界观与价值观修养问题

马克思主义理论课教师世界观的要求就是辩证唯物主义和历史唯物主义的思想体系和方法论；其价值观的要求就是以大公无私为特征的价值判断标准。马克思主义理论课所具有的知识性和思想性、科学性和实践性相统一的特点，要求马克思主义理论课教师，不仅要有扎实的化知识，而且必须加强其世界观和价值观的修养。许多事实证明，只有这样才能真正提高马克思主义理论课的教学实效。     

英汉互译中的文化差异

语言和文化有着密不可分的关系,文化需要通过语言加以传承和表达,语言更受到文化的影响。因此翻译既是语言的翻译又是文化的翻译,文化差异对英汉互译具有重要影响。中西方文化差异大都涉及到文化核心成份,即价值观念--亲属关系及称谓、伦理道德、宗教信仰和思维方式等,英汉两种语言处处烙上了价值观的印记。针对上述文化差异,本文通过典型译例探讨应如何避免误译。