共查询到20条相似文献,搜索用时 0 毫秒
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Olivier Ferrandon 《Space Policy》1997,13(2):97-107
A reusable launch vehicle could be developed early next century if the X-33 program is successful. Its development will be funded by industry, and the vehicle will be operated privately. A critical task is to assess the future market for such a vehicle. The total number of commercial payloads could range between 40 and 60 satellites per year, taking into account the market elasticity due to the launch price reduction. The RLV would face important competition from expendable launch vehicles. However, the RLV could capture two-thirds of this market, or 26–33 commercial payloads per year. 相似文献
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A major paradigm shift in space exploration is at hand. While great discipline must be exercised, we can reinstitute the exploration of the Moon and Mars through use of current systems and technology. These early initiatives will require coupling available or growth boosters with evolving upper stages and spacecraft that employ new emerging technologies and subsystems to characterize the resources, topography, gravity and sites for future manned expeditions. We have the opportunity to perform first-rate scientific research while also serving the needs of the unfolding Space Exploration Initiative. These early programs can be pursued within limited budgets if management techniques, best described as “fast track”, are applied. Examples of such efforts that met all federal regulations, yet achieved significant returns in 1- to 2-year spans, are given. 相似文献
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Olof Lundberg 《Space Policy》1985,1(3):318-322
The International Maritime Satellite Organization's (INMARSAT) success in operating the world's maritime satellite communications system has led to moves for it to expand its activities into other related areas. A vital role for INMARSAT in the Future Global Maritime Distress and Safety System has already been acknowledged and moves are currently being made to alter the organization's Convention to enable it to provide a range of aeronautical services. 相似文献
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今天我们在这里召开集团公司第一次工艺工作会。会议的目的是:全面总结集团公司工艺工作所取得的成绩,认真分析存在的问题和薄弱环节,针对形势和任务的特点,明确集团公司工艺工作的总体思路和发展目标,制定切实可行的措施,以提高集团公司工艺管理和技术水平,增强集团公司的核心竞争力,促进集团公司产业化发展,加速实现铸造国际一流宇航公司的目标。一、形势与任务集团公司成立以来,型号科研生产取得了举世瞩目的成就。这些成绩的取得离不开工艺水平的大幅度提高,离不开广大工艺工作者的奋力拼搏,正是由于工艺强有力的支撑作用,我们才具备了… 相似文献
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引言春季(3~5月)是大气环流由冬季向夏季转换的季节。气温回升,空气干燥,扬沙、浮尘等造成恶劣能见度。烟台机场平均相对湿度为53%,远低于年平均相对湿度64%。本场春季降水量少,多西南大风、西北大风。并时有南来平流海雾、低云。俗语:"春天孩儿面,一天脸三变"指的就是春季天气的 相似文献
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应用蒙特卡罗数值模拟与二项分布累积概率评定方程相结合的方法,对某燃气源点火器的性能可靠性进行评定。计算结果表明,该方法能充分利用试验信息,减少试验的样本量,提高可靠度评定的精度和置信度,节减经费,缩短研制周期。 相似文献
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Watson AJ 《Astrobiology》2008,8(1):175-185
Structurally complex life and intelligence evolved late on Earth; models for the evolution of global temperature suggest that, due to the increasing solar luminosity, the future life span of the (eukaryote) biosphere will be "only" about another billion years, a short time compared to the approximately 4 Ga since life began. A simple stochastic model (Carter, 1983) suggests that this timing might be governed by the necessity to pass a small number, n, of very difficult evolutionary steps, with n < 10 and a best guess of n = 4, in order for intelligent observers like ourselves to evolve. Here I extend the model analysis to derive probability distributions for each step. Past steps should tend to be evenly spaced through Earth's history, and this is consistent with identification of the steps with some of the major transitions in the evolution of life on Earth. A complementary approach, identifying the critical steps with major reorganizations in Earth's biogeochemical cycles, suggests that the Archean-Proterozoic and Proterozoic-Phanerozoic transitions might be identified with critical steps. The success of the model lends support to a "Rare Earth" hypothesis (Ward and Brownlee, 2000): structurally complex life is separated from prokaryotes by several very unlikely steps and, hence, will be much less common than prokaryotes. Intelligence is one further unlikely step, so it is much less common still. 相似文献
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V. A. Fedorov 《Cosmic Research》2011,49(4):374-381
We studied the process of electrification of a rocket during launch and flight in the atmosphere at the active part of its trajectory. The values of charge, field strength, and rocket potential at the launch are estimated. Charging and discharging currents are determined for a rocket flying through clouds and precipitation, and solutions expressing the time variation of the rocket’s charge are found. The values of charge, field strength, and rocket potential are obtained as functions of time, together with the engine plume represented as a charged plasma structure. The rocket’s charge is shown to tend to an equilibrium state, and the time of reaching it is found. Mechanisms limiting the charge value are considered, and the conditions of origination of an electric breakdown (lightning) between the rocket and atmosphere are determined. 相似文献
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2008年10月9日19时30分,太原机场航管楼等重要保障部门发生断电。断电带来的影响是突然的,但山西空管分局并没有慌乱,而是在第一时间内启动了应急预案。设备部门马上开启了供电油机,UPS迅速进行切换,整个设备在UPS和油机供电下没有受到丝毫的影响。航管楼虽然没有了照明灯,但是所有应急灯全部启动。空中飞行保障顺畅。后勤保障部门及时询问检查断电的原因。十分钟后,供电恢复正常。 相似文献
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引言我国各机场均建有负责空管运行、指挥的航管楼,特别是各省会城市机场的航管楼,几乎都设有塔台管制室、区域管制室、运行管理、飞行服务、技术保障和气象服务等多个运行单位,共有设备200余台,担负着航管雷达信号处理与显示、地空通信、航行电报收发与处理、气象信息发布、航情通告转发等重要工作。 相似文献
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Discussions of future human expeditions into the solar system generally focus on whether the next explorers ought to go to the Moon or to Mars. The only mission scenario developed in any detail within NASA is an expedition to Mars with a 500-day stay at the surface. The technological capabilities and the operational experience base required for such a mission do not now exist nor has any self-consistent program plan been proposed to acquire them. In particular, the lack of an Abort-to-Earth capability implies that critical mission systems must perform reliably for 3 years or must be maintainable and repairable by the crew. As has been previously argued, a well-planned program of human exploration of the Moon would provide a context within which to develop the appropriate technologies because a lunar expedition incorporates many of the operational elements of a Mars expedition. Initial lunar expeditions can be carried out at scales consistent with the current experience base but can be expanded in any or all operational phases to produce an experience base necessary to successfully and safely conduct human exploration of Mars. 相似文献
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持续是安全工作的本质规律。民航局持续安全理念的提出,不仅给民航系统树立了更为艰巨更为长远的安全目标,而且为民航安全工作者重新审视行业规律、切实转变管理思维、管理模式提供了理论指导。在持续安全理念的学习过程中我们领悟到:完成阶段性的安全任务与持续安全是两回事,过去工作上的一些偏差,是我们在用保阶段性安全的方式,试图去完成持续的安全目标。本文试图结合华东空管实际情况, 相似文献
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We consider possible stages of constructing complex models of the circumterrestrial plasma including both neutral and charged components in their interaction. At the initial stage it is suggested to use as a basis the empirical models of the upper atmosphere and ionosphere. These models have concentrated fundamental data about the near-Earth space (NES) accumulated for several decades of space exploration. The final goal is to construct a prognostic model which would allow one to calculate both long-periodic variations of the NES structure (they can occur over several decades of years and more) and short-period disturbances with a characteristic time of about a day. In order to predict the results of anthropogenic effects it is proposed to construct imitation mathematical models that should allow one to calculate NES variations which can proceed at various model scenarios of anthropogenic actions. 相似文献
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An experimental psycho-physiological method is presented for the evaluation of visual-cognitive performance preconditions and operational reliability of pilots and cosmonauts. As visual-cognitive stress are used tachistoscopically presented instrument symbols under conditions of individual speed of work and time pressure. The results of the compared extreme groups consisting of pilots with good and insufficient flight performance showed that the pilots with impairments to the quality of flight activity differ already before the test in their individual habitual characteristics and actual motivation, during the stress in their operational parameters, in the dimensions of their cardiorespiratory activation as well as in their efficiency and after the stress in their subjective experience of the stress. Conclusions are drawn for the evaluation of the aptitude of pilots and cosmonauts. 相似文献