Opportunities search of transfer between interplanetary halo orbits in ephemeris model

In this paper,a two-level search method for searching transfer opportunities between interplanetary halo orbits,exploiting the invariant manifolds of the restricted three-body problem,is proposed.In the method,the first-level search procedure is performed under the conditions of the initial time of escape manifold trajectory of the Sun-Earth halo orbit and the terminal time of capture manifold of the target planet fixed,by solving the optimal two-impulsive heliocentric trajectory to connect the two manifold trajectories.The contour map,helpful to the understanding of the global characteristics of the transfer opportunities,taking the initial time of escape manifold and the terminal time of capture manifold as variables,the optimal velocity increment of the first-level search as objective function,is used for the second-level search.Finally,taking the Earth-Mars and Earth-Venus halo to halo transfers for example,the transfer opportunities in 2015-2017 are searched.The results show the effectiveness of the proposed method and reveal the property of quasi-period of transfer opportunities between interplanetary halo orbits.     

Concept of the solar ring mission: An overview

The concept of the Solar Ring mission was gradually formed from L5/L4 mission concept, and the proposal of its pre-phase study was funded by the National Natural Science Foundation of China in November 2018 and then by the Strategic Priority Program of Chinese Academy of Sciences in space sciences in May 2019. Solar Ring mission will be the first attempt to routinely monitor and study the Sun and inner heliosphere from a full 360-degree perspective in the ecliptic plane. The current preliminary design of the Solar Ring mission is to deploy six spacecraft, grouped in three pairs, on a sub-AU orbit around the Sun. The two spacecraft in each group are separated by about 30° and every two groups by about 120°. This configuration with necessary science payloads will allow us to establish three unprecedented capabilities: (1) determine the photospheric vector magnetic field with unambiguity, (2) provide 360-degree maps of the Sun and the inner heliosphere routinely, and (3) resolve the solar wind structures at multiple scales and multiple longitudes. With these capabilities, the Solar Ring mission aims to address the origin of solar cycle, the origin of solar eruptions, the origin of solar wind structures and the origin of severe space weather events. The successful accomplishment of the mission will advance our understanding of the star and the space environment that hold our life and enhance our capability of expanding the next new territory of human.

     

采用离子渗氮技术提高H13热挤压齿轮模寿命

对H13热挤压齿轮模的表面失效进行了分析，为提高H13热挤压齿轮模的寿命对其进行了离子渗氮。介绍了离子渗氮的工艺流程以及离子渗氮的最佳温度、最佳渗氮时间、最佳渗氮压力等工艺参数。     

Concept of the Solar Ring mission: Preliminary design and mission profile

The Solar Ring mission, a concept to monitor the Sun and inner heliosphere from multiple perspectives, has been funded for prephase study by the Strategic Priority Program of Chinese Academy of Sciences in space sciences. The Solar Ring is comprised of 6 spacecraft, grouped in three pairs, moving around the Sun in an elliptical orbit in the ecliptic plane. The mission costs,including launch fee, deep-space maneuvers, and deployment time of the ring, are highly relevant to the working orbit, deepspace transfer, and phase angle within a group. The preliminary mission profile is analyzed and designed in this paper. The launch way, two spacecraft with one rocket, is adopted. The deployment time, phasing maneuvers, and C_3 of launch energy are evaluated for the elliptical orbits with the perihelion between 0.7 and 0.9 AU using the rockets of Long March(LM) 3A and 3B.Numerical simulations show two candidate trajectories: fast deployment within 4 years by LM-3B, medium deployment more than 6 years by cheaper rocket of LM-3A. In order to obtain both fast deployment and low launch cost, another orbit profile is proposed by shortening the phase angle within a group. The suggested working orbits and the corresponding costs of launch,deployment time, and phasing maneuvers will strongly support the science objectives.     

花键轴轴向挤压工艺及模具设计中的几个关键问题

本文主要介绍了国内已经研发生产的矩形花键和各种渐开线齿形花键,如摩托车起动机构主轴和副轴,农用车、轿车、微型车半轴和变速器传动轴及轴承体花键等,叙述了花键轴轴向挤压工艺及模具设计中的几个关键问题。     

光纤光栅传感器在桥梁应变测量中叉敏感问题的研究

本文从理论上介绍了布喇格光栅传感器传感原理及交叉敏感问题的物理机制,并针对桥梁结构这一复杂环境的内部应变,提出了一种解决交叉敏感问题的新颖方案.     

确定多跨连续梁精确影响线的简便方法

建立多跨连续粱精确影响线的简便方法,不仅可以克服用静力法或机动法求多跨连续粱某一量值（反力、内力）的影响线的麻烦和不够精确,而且用很简单的数学方法可求得任一量值的影响线精确方程。     

入侵检测系统中告警相关部件的设计与实现

随着网络的迅猛发展,管理入侵检测系统产生的大量告警变得越来越重要。本文基于因果相关的思想,设计并实现了一个入侵检测系统中的告警相关部件。实验表明,该部件能有效减少告警数量,其告警减少率达到83．26％。     

基于产学研结合的毕业设计运作新模式及实践

论述了“产、学、研”结合在指导教师的遴选、毕业设计题目的确定、毕业设计指导工作,以及毕业答辩等毕业设计各环节中的重要作用和具体的运作方法．