浅析团委工作在职业学校学风建设中的作用

在职业学校的学风建设中共青团委起着举足轻重的作用。本文分析了当前职业学校学风建设中存在的主要问题,并有针对性地提出在改进学风建设中,发挥共青团委作用的有效途径和方法。     

Halo orbits in the vicinity of the L 2 libration point in the Sun-Earth system

Methods are proposed for constructing the orbits of spacecraft remaining for long periods of time in the vicinity of the L ₂ libration point in the Sun-Earth system (so-called halo orbits), and the trajectories of uncontrolled flights from low near-Earth orbits to halo orbits. Halo orbits and flight trajectories are constructed in two stages: A suitable solution to a circular restricted three-body problem is first constructed and then transformed into the solution for a restricted four-body problem in view of the real motions of the Sun, Earth, and Moon. For a halo orbit, its prototype in the first stage is a combination of a periodic Lyapunov solution in the vicinity of the L ₂ point and lying in the plane of large-body motion, with the solution for the linear second-order system describing small deviations of the spacecraft from this plane along the periodic solution. The desired orbit is found as the solution to the three-body problem best approximating the prototype in the mean square. The constructed orbit serves as a similar prototype in the second stage. In both stages, the approximating solution is constructed by continuation along a parameter that is the length of the approximation interval. Flight trajectories are constructed in a similar manner. The prototype orbit in the first stage is a combination of a solution lying in the plane of large-body motion and a solution for a linear second-order system describing small deviations of the spacecraft from this plane. The planar solution begins near the Earth and over time tends toward the Lyapunov solution existing in the vicinity of the L ₂ point. The initial conditions of both prototypes and the approximating solutions correspond to the spacecraft’s departure from a low near-Earth orbit at a given distance, perigee, and inclination.     

模糊聚类辨识在导弹自动驾驶仪横滚通道设计中的应用

在建立模糊逻辑系统的一般数学模型后，利用聚类方法推导出了模糊聚类辨识算法，从而使被辨识出的某型规导弹横滚通道时变气动参数c1、c3能够较准确的反映出在具有某些典型特征飞行条件下与导弹在飞行过程中各个主要特征参数之间的非线性关系。然后在此基础上设计了横滚通道自动驾驶仪。     

飞艇气囊压力与蒙皮张力的估算

平流层飞艇的研制开发近年来成了世界各国的研究热点,由于平流层飞艇的滞空高度高,在上升和下降时飞艇气囊的体积和压力变化动态范围很大,其气囊的设计与低空飞艇有很大的不同。为了给飞艇的气囊结构设计、强度设计提供依据,采用微元受力分析的方法,对气囊蒙皮内张力的进行了分析,得出了飞艇气囊内外压差、曲率半径、气囊蒙皮内张力的关系。该关系还可以应用于各种充气囊体的张力分析,并利用此关系对飞艇的蒙皮张力进行了计算。     

考试作弊行为的分析与对策

考试作弊行为作为存在于高校考试过程中的一种不正常现象,干扰了高校正常的教学秩序,影响教学质量的提高.本文通过对考试作弊行为产生原因的分析,阐述了杜绝考试作弊行为的有效途径.     

考试作弊行为的分析与对策

考试作弊行为作为存在于高校考试过程中的一种不正常现象，干扰了高校正常的教学秩序，影响教学质量的提高。本文通过对考试作弊行为产生原因的分析，阐述了杜绝考试作弊行为的有效途径。     

浅论中西悼亡诗死亡意义的实现

一直以来,探求悼亡诗作的人已不少,然较少有人从悼亡诗的死亡意义进行研究。论文从死亡美学的角度出发,探求中西悼亡诗的死亡意义如何实现的问题。文章分为三个部分展开论述:一、悼亡诗的界定;二、概括中西悼亡诗共同的情感表达;三、中西悼亡诗死亡意义的实现。     

On the one-body problem in the field of a tall cylinder in orbit

We describe the motion of a material point that is attracted by a tall, homogeneous cylinder. The cylinder moves on a circular orbit and points in the radial direction. The finite solution can be expanded in powers of two small parameters: the initial eccentricity of the orbital motion about the cylinder and the coupling parameter of the Coriolis force. Such expansions are given for the case of the indifferent longitudinal location. Solutions periodic in the polar angle are constructed. We do not find resonance effects or other large cumulative amplitude variations that might be due to the gravity-gradient and Coriolis force.     

构建靶场区域CORS及其靶场应用初探

连续运行卫星定位综合服务系统(CORS)是集GNSS卫星导航定位、计算机、数据通信和互联网等技术于一体,在一个区域或一个国家根据需求按一定方案建立的常年运行的由若干个固定GNSS基准站组成的网络系统,为用户提供测量等多项相关技术服务。提出在靶场建立区域CORS,构建一个网络时代的靶场测量系统的方案设想,为实现靶场信息化提供一条思路。     

动态系统仿真软件System view及其在信号与电子系统中的应用

本文介绍了Elanix公司的开发研制的动态系统仿真软件System view及其工作流程,并在此基础上着重分析了 System view在<信号与系统>和<通信原理>两门课程中的应用.进而阐明了这类课程引入仿真技术的重要性.     

动态系统仿真软件System view及其在信号与电子系统中的应用

本文介绍了E1anix公司的开发研制的动态系统仿真软件System view及其工作流程，并在此基础上着重分析了System view在《信号与系统》和《通信原理》两门课程中的应用。进而阐明了这类课程引入仿真技术的重要性。     

论《喧嚣与愤怒》中杰森叙述的不可靠性

在小说<喧嚣与愤怒>中,福克纳通过多种叙述技巧揭露了美国南部的日趋衰落.本文的主要论述点在于杰森叙述的不可靠性及这种不可靠的叙述揭露并增强了故事所要表达的主题.     

On the structure of the floating zone in melting

Floating zone melting is used in crystal growth and purification of high melting materials. The use of a reduced gravity environment will remove the constraint imposed on the length of the zone by the hydrostatic pressure. The equilibrium of the floating zone may involve, (1) Hydrostatic forces, when the zone rotates as a whole. (2) Convective driving forces, when the zone is stationary but fluid property gradients appear. (3) Hydrodynamic forces, when some parts of the zone are set into motion with respect to others. The last effects are considered in this paper. The flow pattern of a floating zone held between two discs in relative motion is complicated, and thence the solution of the problem is difficult even assuming a constant property-newtonian liquid. Nevertheless, when a small parameter appears in the problem, the complete flow field can be split into zones where simple solutions are found. To illustrate this approach, the spin-up from rest of an initially cylindrical floating zone is considered with detail. Here the small parameter is the time elapsed from the impulsive starting of motion. Since the problem which has been considered, as well as some others which can be tackled by use of similar methods, concern the viscous layer close to either plate, they can be simulated experimentally in the ground laboratory with short floating zones. Procedures to produce these zones are indicated.     

多孔介质隔热材料中的辐射热传递分析

新型的多孔材料以其重量轻、强度高备受航天工程设计人员的亲睐,尤其是作为隔热材料使用,可以说是航天工程热防护系统的热门材料.多孔介质在辐射热传递方面具有吸收发射和散射的功能,这些功能在其接受外来热流的作用下,于内部达到热能量平衡,求解这一平衡方程就可以求出辐射热流在材料中的分布.由于求解这一方程的困难,许多学者对材料特性...     

Watersheds in the modern world: the space viewpoint

A new world order has begun to appear since the early 1990s. The simplicity of interaction between individual states, based on the rivalry between the two superpowers, is gradually being replaced by new attitudes formed in a complex, uncertain and risky context. States still have a role, discussing, negotiating, legislating, creating infrastructures and issuing directives. However, political power, with its laws, its order and its reasoning, is being supplemented and often dominated by other forms of power: economic, financial or influence. Space policies follow or sometimes precede political trends. They were the spearhead of the ‘glory years’ and still bear the imprint of the simple rules which applied twenty years ago. However, amid the current uncertainty, it is possible to perceive the outline of the space policies of the future, which may contribute to the definition of new watersheds in the modern world.     

论《喧嚣与愤怒》中杰森叙述的不可靠性

在小说《喧嚣与愤怒》中，福克纳通过多种叙述技巧揭露了美国南部的日趋衰落。本文的主要论述点在于杰森叙述的不可靠性及这种不可靠的叙述揭露并增强了故事所要表达的主题。     

美军现径部队编制情况

美军现役部队分为陆军、空 军和海军三个军种，分属陆军部、 空军部和海军部领导。 １．陆军编制 陆军部队分为诸兵种合成军团 （兵团）和独立的军种部队（分队）。 集团军群是美军在战时才设 立的合成军团，平时不设这一级 部队。战时设立的数量根据战区 作战任务、作战范围而定。美军在 第二二次世界大战中曾组建过３个集团军群，在欧洲作战的第１２集团军群编有４个集团军。集团军是美军实施战役作战的基本军团，其编制不固定，通常辖３个军、９至１５个师以及战斗支援和勤务支援部队。 军是美军陆军中负有战斗、支援、后勤保障职责的最…     

QPS信号在大气空间中的衰减特性分析

量子定位系统（QPS）是一种高精度安全的定位技术。阐述了量子定位原理,重点分析了QPS信号在大气空间中的传输特性,得出不同波长在不同通信距离下信号的衰减,计算了一定波长不同能见度下实现QPS定位的通信距离。根据研究,可选择合适的波长以减小大气的吸收、散射及湍流对信号的影响,设计合适的卫星高度和基线长度提高其定位精度。所做的研究可为实际设计QPS定位系统提供理论参考依据。