共查询到20条相似文献，搜索用时 78 毫秒
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本文是针对卫星和飞船的跟踪测控而建立的数学模型。在问题1中,建立了地心张角与监控器张角及飞船高度关系模型、估算法模型、对椭圆实际监控的迭代算法模型,并以神舟六号飞船为例算出建站个数。在问题2中,建立了监控器斜穿飞船轨道下方时,地心张角与监控器在地球自转情况下的实际监测张角关系及建站模型,并以神舟六号飞船为例算出建站个数。在问题3中,分析了各监控站在飞船升空监控的阶段及范围。 相似文献
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为了确定全程跟踪卫星或飞船的测控站数量,在不考虑地球自转影响和考虑地球自转影响的情况下,使用几何方法分别建立了对卫星或飞船进行全程测控时所需要的最少测控站数量模型,并针对＂神舟七号＂飞船给出了所需最少测控站数量,估算出＂神舟七号＂飞船所能测控的有效范围。 相似文献
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这位年近古稀、头发花白的资深航天专家表示,中国开展载人航天工程,飞船本身不是目的,研制、发射飞船都是为将来的空间站服务。“中国的空间站建成后,‘神舟’飞船将发挥两大作用。”戚发轫称,一是作为“公共汽车”往返于天地之间,将地球上的人和设备送上太空,再把太空中的人和实验成果送回地球;二是成为空间站的应急救生系统,飞船停靠、守候于空间站旁,相当于一艘救生艇,必要时可将空间站的工作人员及时送回地球。谈起已成功发射并回收的“神舟”三号飞船,爽朗随和的戚发轫就像在说自己孩子,亲切而自然。他介绍道,“神舟”三号飞船拥有13个… 相似文献
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为了提高仿真系统的可重用性,提出采用HLA作为仿真体系框架,利用HLA把航天测控训练仿真系统设计为一个联邦,分析其系统组成并按功能划分为若干联邦成员,以便进行分布式仿真。阐述了基于HLA的航天测控训练仿真系统联邦的设计方法和思路,深入探讨了联邦成员的划分及对象模型的设计,并给出了仿真流程与三维显示的实现过程。 相似文献
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吴佳颖 《英语大王(小学)》2014,(3):34-34
In spring, it＇s always warm and sunny. People like to go outing. ff＇s sunny today. The Blacks have a picnic in a park. There are many big trees and flowers in the park. They take lots of food with them. There is fruit, drinks, bread and so on. 相似文献
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This article has no direct link with academics, children, students or those who teach: I severed almost all such connections several years ago. It describes the rewards and challenges of leading a reminiscence group of elderly people, all of whom suffer some level of memory loss and/or severe physical disability; most are wheelchair-bound. It contains examples of their autobiographical talk which I recorded separately from group meetings and transcribed, exclusively for the satisfaction of each individual concerned. Ours is not a society which cherishes its aged members. What becomes of their identity? Who are they now? They are, of course, people – as interesting as those in our classrooms. They too need to know their own worth. 相似文献
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程俊杰 《英语大王(小学)》2013,(5):3+39
Marty and Father go to a party in a park.The park is near a farm and very, very far.So Marty and Father go to the park in a car.After the party they count* the stars in the dark*. 相似文献
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In this article, we explain the idea of Rees [1] to utilize the inverses of partial one-one functions on a cancellative monoid S to embed S into a group. 相似文献
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The experiment in which a candle is burned inside an inverted vessel partially immersed in water has a history of more than
2,200 years, but even nowadays it is common that students and teachers relate the change in volume of the enclosed air to
its oxygen content. Contrary to what many people think, Lavoisier concluded that any change in volume in this experiment is
negligible; moreover, the explanation relating oxygen consumption in the air with its change in volume is known to be wrong.
In this work we briefly review the history behind the candle experiment and its relationship with some typical erroneous explanations.
One of the key factors behind Lavoisier’s success was the use of experiments carefully designed to test different hypotheses.
Following these steps, we performed several closed volume experiments where the candle wick was replaced by a capillary stainless
steel cylinder supported and heated by a nichrome filament connected to an external power supply. Our recorded experiments
are displayed as web pages, designed with the purpose that the reader can easily visualize and analyze modern versions of
Lavoisier’s experiments. These experiments clearly show an initial phase of complete combustion, followed by a phase of incomplete
combustion with elemental carbon or soot rising to the top of the vessel, and a final phase where the hot artificial wick
only evaporates a white steam of wax that cannot ignite because no oxygen is left in the closed atmosphere. After either a
complete or incomplete combustion of the oxygen, our experiments show that the final gas volume is nearly equal to the initial
air volume. 相似文献
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萧庆媛 《天津职业院校联合学报》2003,5(1):63-66
作为主要承担德育教育工作的班主任 ,除具有一般教师的基本业务素质外 ,还应具备有较高的政治思想素质和职业道德修养 ,要有广博的知识和善于开展工作的能力。学校要为教师学习深造和开展教改活动积极创造条件。应通过不断加强学习 ,对班主任教师进行实践锻炼和培养 相似文献
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Chia Wei Tang 《Journal of Higher Education Policy & Management》2019,41(3):275-291
This study aimed to investigate and compare the impact of pursuing top university status on the management and academic practices of two departments in a top-ranked institution in Taiwan. Qualitative interviews, official policy documents, website resources and relevant documents were the main sources of empirical data. Interview data were collected from 10 interviewees, the department heads and four full-time academics in both departments. This study found that departments and academics were required to plan and work in accordance with the university’s overall development plan and the two departments played different roles in contributing to various aspects of the university managers’ idea of what a world-class university is. This should be understood within the unique and complex academic tribes of different subject fields and the deeply rooted dimensions of Chinese culture in Taiwan. 相似文献
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