多重分形及其在地形特征分析中的应用

采用多重分形谱进行地形特征的分析,多重分形谱参数分层次地刻画了空间内部的精细结构,突出了异常局部变化特征,因而能够获得准确的地形特征信息,并从复杂的地形数据中选出具有明显个性特征的区域,可与分形维数结合进行地形地貌的区域分类和路径选取.实验结果表明,多重分形的奇异谱函数比简单的分形维数能提供更多的信息,克服了分形维数相同情况下区域无法区分的困难,地形的提取特征结果更为符合实际情况,可被有效地用于导航和航迹规划过程中.      

国外空间用三反离轴相机发展分析与思考

空间用三反离轴光学系统自20世纪70年代提出,从90年代开始在多个国家的卫星光学有效载荷中已经或计划得到应用并快速发展,技术基本成熟,领域涉及到对地观测、空间目标探测、天文观测、多光谱热成像、立体测绘等,但是普遍认为制造装调技术比较难.文章通过广泛调研国外三反离轴系统在空间的应用和发展现状,并按应用情况、系统参数和系统构型进行了分类比较,分析其发展趋势,为中国空间相机发展三反离轴光学系统提供借鉴.     

基于改进Jacobian-Torsor理论的转子组件装配精度控制方法

转子装配是航空发动机制造过程的核心环节，防止同心度超差是转子组件装配需要解决的重要问题。传统方法以千分表人工手动测试为主，依赖制造经验，缺乏系统、定量的结构精度设计理论方法支撑。针对转子的回转特性和多级装配特点，提出了基于改进的雅可比旋量理论的三维偏差建模方法和组合堆叠同心度控制策略，通过引入回转副有效表征了航空发动机转子零件的回转特性，确定了雅可比扩展矩阵和同心度偏差传递函数及其控制方程。结合该方程，对某4级涡轮转子装配进行验证，当各级安装角度分别为3.513 rad、5.206 rad和0.953 rad时，可获得最高同心度0.042 mm。结果表明该模型可以有效预测组件整体精度和确定最佳装配方案，具备较强现实指导意义。     

Resonant motion, ballistic escape, and their applications in astrodynamics

A special set of solutions governing the motion of a particle, subject to the gravitational attractions of the Earth, the Moon, and, eventually, the Sun, is discussed in this paper. These solutions, called resonant orbits, correspond to a special motion where the particle is in resonance with the Moon. For a restricted set of initial conditions the particle performs a resonance transition in the vicinity of the Moon. In this paper, the nature of the resonance transition is investigated under the perspective of the dynamical system theory and the energy approach. In particular, using a new definition of weak stability boundary, we show that the resonance transition mechanism is strictly related to the concept of weak capture. This is shown through a carefully computed set of Poincaré surfaces, at different energy levels, on which both the weak stability boundary and the resonant orbits are represented. It is numerically demonstrated that resonance transitioning orbits pass through the weak stability boundaries. In the second part of the paper the solar perturbation is taken into account, and the motion of the resonant orbits is studied within a four-body dynamics. We show that, for a wide class of initial conditions, the particle escapes from the Earth–Moon system and targets an heliocentric orbit. This is a free ejection called a ballistic escape. Astrodynamical applications are discussed.     

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。     

引用形定义与图像控件菜单交互标注形位公差

实现形位公差交互标注的方法有多种，但基本上都是用ＡｕｔｏＬＩＳＰ语言和菜单文件结合编程实现的，本文介绍的方法是在ＡｕｔｏＣＡＤ１４．０中，用引形定义与图像控件菜单交互标注形位公差。     

Verb Semantics Affects the Interpretation of Spatial Prepositions

Abstract

Spatial prepositions, more specifically projective prepositions, such as in front of or behind can be interpreted in different ways. Their interpretation depends on the spatial perspective taken as the basis for determining the reference frame's orientation. In 3 series of placement experiments with German speakers, we examined whether the interpretation of projective prepositions in a motion context is affected by the verb used in a spatial instruction. Results suggest that verb semantics is a factor accounting for previously observed seemingly social-situational differences in the interpretation of projective prepositions. Specifically, the findings indicate that, relative to a car as reference object, the semantic aspect of motion interruption associated with some verbs leads to a higher proportion of deictic interpretations determined by the direction from which one is approaching the car. This verb effect on the interpretation of spatial prepositions can be explained by an activation of the temporal dimension through stop-implying verbs, which is integrated into the spatial situation model of the perceived dynamic scene making the deictic frame of reference more compatible. The experimental evidence also shows that verb semantics can account for previously unexplained cross-linguistic differences, and is related to patterns concerning the prepositional inventory of languages.     

三轮涡轮冷却器应用研究

本文通过对涡轮冷却器和飞机地面环控系统工作原理的分析，提出了将三轮涡轮冷却器用于飞机地面环控系统的设计方案。并给出了系统主要性能参数的计算结果。     

载人地月混合轨道一次脉冲应急返回轨道分析

对于载人地月转移任务，应急返回轨道是航天员安全返回地球的保障。针对载人混合轨道地月转移对安全性要求高的特点，基于载人地月混合轨道，提出了3种一次脉冲的应急返回轨道，即直接返回、即刻机动绕月返回及绕月后机动返回等模式。研究了不同时刻发生故障后，利用3种应急模式返回地球的转移时间和速度增量等特性，研究了载人地月转移全过程出现故障后的应急方式，总结了3种应急模式的应用特点及优劣，可为载人月球探测任务顶层任务分析与设计提供参考。     

一种点扫描形貌测量系统的现场标定方法

针对三角法点扫描形貌测量系统结构参数标定的非线性问题,提出并实现了一种简单易行的系统结构参数现场标定方法.利用二维靶标在测量空间内自由摆放,根据靶标上特征点及其像点间的位置关系,基于坐标系转换实现了点扫描形貌测量系统结构参数的精确标定.通过对平面及已知直径圆柱面进行测量,利用测量点到拟合平面或圆柱面的距离评价了系统标定的精度.所提标定方法无需精密调整靶标位置,具有较高的可靠性与实用性;也可用于其它基于三角法原理的三维形貌测量系统结构参数的标定.