双齿气体循环泵基本几何理论和容积计算

以数学几何理论为基础,通过坐标变换和包络条件推导了阴阳转子的基本型线方程,建立了双齿气体循环泵的数学模型。研究了阴阳转子相互啮合时啮合点位置随阴转子转角的变化关系。采用了线积分的计算方法推导出工作容积的基元面积随转角的变化关系,可简化工作容积的计算难度。结果表明:在转角为0和π的时候,阴阳转子会形成一个封闭的无效区域导致了工作腔的基元面积随转角变化过程中的突升和突降。在吸气结束时,由于吸气腔相较于排气腔多了一个与吸气口相连的部分导致了基元面积的突降。这些基本几何理论的建立可为双齿气体循环泵的应用打下一定的理论基础。     

变拓扑多臂航天器高效统一动力学建模

针对多臂航天器在轨操控过程中可能存在的多链、闭环、环链混合等多种拓扑构型及相应的动力学模型变化,提出基于空间算子代数理论(SOA)的高效统一动力学建模方法。首先,提出了描述多臂航天器部件连接关系的构型参数,并基于构型参数提出了多臂航天器拓扑构型描述矩阵的自主生成方法。其次,基于空间算子代数理论,将通路矩阵与空间转移算子相结合,提出了变拓扑多臂航天器统一动力学建模方法。最后,将数值仿真结果与多体动力学仿真软件的仿真结果进行比对,验证所提方法的有效性。仿真结果表明,对于不同的拓扑结构,所提出的O(n)阶统一动力学建模方法能准确描述变拓扑情况下的多臂航天器动力学响应。     

Optimal multi-site selection for a PV-based lunar settlement based on a novel method to estimate sun illumination profiles

Recently, space organizations have considered the Moon to host lunar bases. Such bases require power and energy to function. However, the efficient and safe use of the energy resources on the Moon is a huge challenge. Space photovoltaic (PV) power systems are appealing technologies due to their maturity and high solar energy availability at some locations on the Moon. The effectiveness of these PV systems depends on their selenographic location, which might necessitate the deployment of energy storage technologies to cover the base’s energy demand. Some analysts have proposed the installation of PV modules on kilometers-tall towers near the lunar poles to harvest more solar energy and limit the need for energy storage systems (ESSs). Alternatively, this paper proposes to harvest the energy from multiple sites in the lunar South Pole region using a novel technique to compute the Sun illumination profile and the LOLA topographic databases to compute the terrain elevations. The proposed algorithm seeks the most optimal configuration of sites and tower heights to minimize the longest night period and total distance between the sites. This study assesses groups of 1 to 6 sites assuming the use of towers having heights of 10, 100, and 500 [m]. The time horizon for the analysis is one Axial Precession Cycle, which is approximately 18.6 years. According to the results, a system of two sites with a separation of 42.05 [km] and towers of 500 [m] height has a maximum darkness period of only 3 [h] while another solution proposes a system of three sites with towers of 10 [m] that removes the need of EES (solar eclipse periods by the Earth are not considered). The proposed technique is suitable for engineering applications, such as base planning and operation management.     

刍议军人婚姻保护

经济、社会的发展和多元化,使军人婚姻和家庭稳定面对越来越多的现实挑战,这直接关系和影响到部队日常训练和作战能力.因此,加强和完善必要的法律和措施,切实保护军人在婚姻家庭方面的合法权益对于稳定部队、提升部队作战能力有着重要的现实意义.本文主要从军婚概念的界定、军婚现状及保护军婚的意义、措施方面入手,对这一问题进行分析和探...     

论社会保险法中企业角色的定位

现代企业在促进效率的同时，却也为社会带来了诸多不公平的因素，社会保险法的推行有利于弥补这一缺失。文章结合中国社会保险模式的选择论述了企业在社会保险的角色定位，并对此角色定位的依据进行了理论上探讨。     

运输机尾部布局气动特性研究

在运输机布局设计研究中,为了满足起飞和着陆时的擦地角以及方便装卸货物,往往机身后体会进行上翘,从而损失了部分气动效率,同时,改善静稳定性也是设计中需要考虑的重要因素.为更好地兼顾结构设计原则、静稳定性能和气动性能,通过对某运输机尾部进行修型设计,提出了三种不同的修型方案.通过建模计算,分析了不同修型方案升阻特性及静稳定性的变化,从而得出提高升阻特性、增加静稳定性的有效方法.     

民用飞机平尾气动载荷计算方法研究

水平尾翼的主要功能是保证飞机具有纵向静稳定性和俯仰可操纵性。民用飞机由于起飞重量大、重心变化范围广,对平尾的操纵性要求很高,为了提高平尾的操纵效率,民用飞机一般采用平尾安定面可微动的设计手段,加上升降舵偏转以及翼身洗流等因素的影响,使得飞行中平尾处的流场变得非常复杂,如何准确或偏保守地确定平尾上的气动载荷一直是民用飞机飞行载荷计算中的一个难点。介绍了民用飞机平尾气动总载荷和载荷分布的计算原理和方法,并提出了如何协调基于测力、测压试验得到的载荷,以及平尾弦向分布载荷的修正方法。     

中国股票市场中的现状偏好现象研究

理性人假设历来饱受诟病,现状偏好现象在成熟资本市场广泛存在.西方行为金融学学者提出了现状偏好理论,而该理论在我国鲜有实证支持.尝试提出了以中国股票市场的正负收益率对换手率的不对称影响来衡量现状偏好现象的理论,选择了我国2011年1月4日至2012年9月28日之间上交所和深交所挂牌的主板A股的数据进行实证分析,发现中国股票市场存在明显的现状偏好现象,并计算出该时期上交所主板A股的现状偏好系数为9.61％,上交所主板A股的现状偏好系数为11.11％.     

Validation of the in-flight calibration procedures for the MICROSCOPE space mission

The MICROSCOPE space mission aims to test the Equivalence Principle with an accuracy of 10^-15${10}^{-15}$. The drag-free micro-satellite will orbit around the Earth and embark a differential electrostatic accelerometer including two cylindrical test masses submitted to the same gravitational field and made of different materials. The experience consists in testing the equality of the electrostatic acceleration applied to the masses to maintain them relatively motionless. The accuracy of the measurements exploited for the test of the Equivalence Principle is limited by our a priori knowledge of several physical parameters of the instrument. These parameters are partially estimated on-ground, but with an insufficient accuracy, and an in-orbit calibration is therefore required to correct the measurements. The calibration procedures have been defined and their analytical performances have been evaluated. In addition, a simulator software including the dynamics model of the instrument, the satellite drag-free system and the perturbing environment has been developed to numerically validate the analytical results. After an overall presentation of the MICROSCOPE mission, this paper will describe the calibration procedures and focus on the simulator. Such an in-flight calibration is mandatory for similar space missions taking advantage of a drag-free system.