Modeling and analysis of Earth’s gravity field measurement performance by inner-formation flying system

The Earth’s gravity field can be measured with high precision by constructing the purely gravitational orbit of the inner-satellite in Inner-formation Flying System (IFS), which is independently proposed by Chinese scholars and offers a new way to carry out gravity field measurement by satellite without accelerometers. In IFS, for the purpose of quickly evaluating the highest degree of recovered gravity field model and geoid error as well as analyzing the influence of system parameters on gravity field measurement, an analytical formula was established by spectral analysis method. The formula can reflect the analytical relationship between gravity field measurement performance and system parameters such as orbit altitude, the inner-satellite orbit determination error, the inner-satellite residual disturbances, data sampling interval and total measurement time. This analytical formula was then corrected by four factors introduced from numerical simulation of IFS gravity field measurement. By comparing computation results from corrected analytical formula and the actual gravity field measurement performance by CHAMP, the correctness and rationality of this analytical formula were verified. Based on this analytical formula, the influences of system parameters on IFS gravity field measurement were analyzed. It is known that gravity field measurement performance is a monotone decreasing function of orbit altitude, the inner-satellite orbit determination error, the inner-satellite residual disturbances, data sampling interval and the reciprocal of total measurement time. There is a match relationship between the inner-satellite orbit determination error and residual disturbances, in other words, the change rate of gravity field measurement performance with one of them is seriously restricted by their relative size. The analytical formula can be used to quantitatively evaluate gravity field measurement performance fast and design IFS parameters optimally. It is noted that the analytical formula and corresponding conclusions are applied to any gravity satellite which measures gravity field by satellite perturbation orbit.     

浅析提高投篮命中率的技术因素

本文分析了影响投篮命中率的各种技术因素,并提出了相应的提高命中率的方法,为篮球教学工作提供有益的参考。     

产品的设计色彩与人的情感心理

本文讨论了色彩在工业设计中的应用，并通过色彩构成的色相，明度，纯度等概念的探讨，说明了不同的色彩给人以不同的感觉，产生不同的情绪，并进一步说明了色彩在产品设计上的作用与人的心理情感的关系。     

Transcultural group performance in extreme environment: Issues, concepts and emerging theory

A simulation for flight of international crew on space station took place in Moscow from July 1999 to April 2000 (SFINCS) at the State Biomedical Institute of Russia (IBMP) isolation chambers. Objectives of this study were to identify concepts of psychosocial adaptation and of social interactions to develop an explanation of the transcultural group performance. Method: constructivist epistemology with grounded theory research and fourth generation evaluation were used. Data on processes and interactions were gathered during 110 days of confinement as a subject and extended to 240 days as an outside scientist. Results indicate that coping is influenced by usual coping strategies and coping behaviors inside. Several stresses and human factor issues were identified altering well being and performance inside the chambers. Enabling and limiting forces are discussed. A theory on transcultural group performance is proposed. Issues are raised that appear critical to selection, training and group performance.     

档案信息深层次加工的影响因素及对策

根据社会发展对档案工作的客观要求以及档案工作自身生存、发展的需要，对影响档案信息深层次加工的因素进行了分析，提出了关于档案信息进行深层次加工的对策。     

翼型动态失速影响因素及流动控制研究进展

深入认识翼型动态失速，结合有效流动控制手段，对解决直升机、风力机桨叶等动态失速引起的高阻力、大低头力矩等气动问题具有重要意义。本文首先介绍了翼型动态失速的流场特点和危害，进而分析了缩减频率、雷诺数、马赫数以及翼型型面等参数对动态失速的影响，并在此基础上总结了常见的动态失速流动控制方法及其研究进展。等离子体气动激励易于产生快速、可控的宽频带气动激励，在动态失速控制领域具有潜力，本文着重介绍了等离子体气动激励动态失速控制的概念和流动控制原理，总结了近来年等离子体激励在翼型动态失速控制上的进展。     

Identification of key factors affecting the failure of aviation piston engine turbochargers based on an improved correspondence analysis-polar angle-based classification

Turbocharging is an efficient approach for addressing power reduction and oil consumption increase in aviation piston engines during high-altitude flights. However, a turbocharger significantly increases the complexity of a power system, and its considerably complex matching relation with the engine results in a coupling of failure modes. Conventional analytical methods are hard to identify failure-inducing factors. Consequently, safety issues are becoming increasingly prominent. This study focuses on methods for identifying failure-inducing factors. A whole-machine system model is established and validated through experimentation. The response surface method is employed to further abstract the system simulation model to a surrogate model (average error: ~ 3%) in order to reduce the computational cost while ensuring accuracy. On this basis, an improved Correspondence Analysis (CA)-Polar Angle (PA)-based Classification (PAC) is proposed to identify the key factors affecting the failure mode of turbochargers. This identification method is based on the row profile coordinates G varying with the numerical deviations of the key factors, and is capable of effectively identifying the key factors affecting the failure. In a validation example, this method identifies the diameter of the exhaust valve (e₂) as the primary factor affecting the safety margin for each work boundary.     

卫星电源系统短路暂态特性分析及对策

针对卫星电源系统短路故障导致母线电压跌落、业务中断甚至整星失效的问题,分别采用电路模型和数学模型的方法对短路后母线电压的暂态特性进行分析,指出故障持续过程经历母线电容放电、太阳电池阵动作、放电调节器动作、蓄电池经二极管直接供电这4个阶段,分析了各阶段母线电压的暂态响应及转换条件。随后,研究了发生稳态电压跌落的条件及其影响因素。针对航天器通常使用的快速熔断器保护,分析了母线电压跌落受熔断I~2T、短路通路阻抗、蓄电池内阻、蓄电池开路电压的影响程度。依据暂态特性的分析,提出接地优化方法以及蓄电池开路电压、短路通路阻抗和欠压保护点的配合设计方法,使得短路暂态过程母线电压跌落程度满足系统关键单机运行的需求。     

High cycle fatigue failure with radial cracks in gears of aero-engines

The gears in aero-engines perform energy and motion transfer between the High-Pressure Rotor (HPR) and accessories. Firstly, an occurred fault with radial cracks in the driven gear disk was diagnosed as High Cycle Fatigue (HCF) failure through necessary examinations. Analysis of fault tree and test signals indicated that the fracture was relevant to the swing vibration of the driven gear excited by the unbalance excitation on HPR. Secondly, a corresponding mechanism model was established, in which the gear meshing effect was considered, with lateral and swing vibration mode. The Governing Equations (GEs) and the Finite Element Model (FEM) were established and verified. Then, the modal shapes, harmonic response, and transient response were analyzed, indicating that the swing vibration of the driven gear could be significantly excited by the unbalance on HPR, which induced the cracks in the driven gear disk to extend radially. Furthermore, influences of factors on the unbalance response were obtained, in which the unbalance response appeared local minimum points and maximum points. Meanwhile, 1# and 2# bearing stiffness had rather significant influences on the response. Thus it is efficient to modify them to achieve vibration control.     

影响城乡劳动者就业的因素与对策研究——以湖南省为例

当前,在我省城乡劳动者就业问题上,既存在宏观经济、法律政策、竞争意识等一些积极因素,也存在金融危机、政策制度、就业结构等一些消极因素。要促进我省城乡劳动者就业发展,必须从就业规划、就业政策、就业管理服务体系、职业培训、社会保险和创业文化宣传等方面采取措施。