共查询到20条相似文献,搜索用时 312 毫秒
1.
《IEEE transactions on aerospace and electronic systems》1989,25(6):786-827
The author describes the avionic equipment for manned spacecraft, past, present, and future. He treats the four classic avionic systems-crew interface, flight control, navigation, and communication-and adds a fifth called subsystem management which refers to the monitoring and reconfiguration of equipment when faults occur. He starts by describing the functions of spacecraft avionics in general. He then discusses what he considers to have been the first manned spacecraft, the X-15. He continues with the early US and Soviet spacecraft (including their space stations), the US shuttle, and the European Spacelab. He concludes with projections for the avionics in future manned spacecraft, such as the US Space Station, a lunar base, and planetary explorers 相似文献
2.
《Aerospace and Electronic Systems Magazine, IEEE》2002,17(1):4-12
President Bush has declared his desire for early deployment of a US National Missile Defense or NMD system to protect the nation against an attack of one or a dozen ICBMs carrying nuclear or, possibly, other weapons of mass destruction (WMDs). He has the support of the Secretary of Defense, sizeable groups in Congress and the public who feel strongly that the US should have a means to provide protection against that threat, and the US has the technology to create that means. The author presents an overview of the perceived need for deploying such an NMD system which would entail the scrapping of existing ABM treaties 相似文献
3.
《Aerospace and Electronic Systems Magazine, IEEE》1991,6(12):10-11
The author reminisces about the use of radar by the US Army in Hawaii and the detection of Japanese aircraft as they approached Oahu on December 7, 1941. He briefly discusses post-Pearl-Harbor radar activity 相似文献
4.
The development of pulse compression radar at Sperry is related on the basis of the author's personal recollections. He discusses the first experiments, concept improvements, demonstration of the concept, system implementations, dealings with the US Patent Office, and finishing touches 相似文献
5.
《Aerospace and Electronic Systems Magazine, IEEE》1991,6(12):12-15
The author discusses some aspects of the role of electronic combat (EC) in the success of the Gulf War. He suggests several areas for possible action by the EC community. One is to think through how the fieldable brassboard/prototype approach applies to electronic warfare. Another is to determine the impact on the EC world if an opponent acquired some or all of US capabilities 相似文献
6.
We report on our continuing efforts to determine 3He abundances in H II regions and planetary nebulae. Our detections of 3He in some PNe show that some stars produce large amounts of 3He. However the H II region abundances show no evidence for this production. From our sample of > 40 H II regions, the subsample which should yield the most reliable abundances has 3He/H abundances which scatter between 1-2 × 10-5. There is no trend with either galactocentric distance or metallicity. Even if we do not understand the underlying mechanisms, we see empirically that stars neither produce nor destroy 3He in a major way. We thus suggest that the level of the "3He Plateau" (3He/H = 1.5
-0.5
+1.0
× 10-5) is a reasonable estimate for the primordial 3He. 相似文献
7.
The High Energy Telescope for STEREO 总被引:1,自引:0,他引:1
T. T. von Rosenvinge D. V. Reames R. Baker J. Hawk J. T. Nolan L. Ryan S. Shuman K. A. Wortman R. A. Mewaldt A. C. Cummings W. R. Cook A. W. Labrador R. A. Leske M. E. Wiedenbeck 《Space Science Reviews》2008,136(1-4):391-435
The IMPACT investigation for the STEREO Mission includes a complement of Solar Energetic Particle instruments on each of the two STEREO spacecraft. Of these instruments, the High Energy Telescopes (HETs) provide the highest energy measurements. This paper describes the HETs in detail, including the scientific objectives, the sensors, the overall mechanical and electrical design, and the on-board software. The HETs are designed to measure the abundances and energy spectra of electrons, protons, He, and heavier nuclei up to Fe in interplanetary space. For protons and He that stop in the HET, the kinetic energy range corresponds to ~13 to 40 MeV/n. Protons that do not stop in the telescope (referred to as penetrating protons) are measured up to ~100 MeV/n, as are penetrating He. For stopping He, the individual isotopes 3He and 4He can be distinguished. Stopping electrons are measured in the energy range ~0.7–6 MeV. 相似文献
8.
美元汇率的走势是分析各种期货品种价格如何波动的风向标。文章首先探讨美元疲软的两个原因:经常账户赤字、财政赤字和次级债危机;进而尝试利用巨无霸指数和蒙特卡罗模拟构筑一个经济学模型对美元未来几年的走势作出预测;最后根据预测结果给出了美元汇率持续走低下现阶段的黄金期货投资的策略。 相似文献
9.
We first recall the observational and theoretical facts that constitute the so-called 3He problem. We then review the chemical anomalies that could be related to the destruction of 3He in red giants stars. We show how a simple consistent mechanism can lead to the destruction of 3He in low mass stars and simultaneously account for the low 12C/13C ratios and low lithium abundances observed in giant stars of different populations. This process should both naturally account for the recent measurements of 3He/H in galactic HII regions and allow for high values of 3He observed in some planetary nebulae. We propose a simple statistical estimation of the fraction of stars that may be affected by this process. 相似文献
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《Aerospace and Electronic Systems Magazine, IEEE》1993,8(6):54-59
It is argued that the procurement of weapons by the US armed services is in crisis. Even before the bribery scandals, there was ample evidence that the whole process was in disarray. The author, a retired civil service electronics engineer, offers his personal opinion of how this happened. Two unsuccessful programs are discussed: an airborne radar designed for the US Air Force to search for vehicles moving on the ground and the Sergeant York, the US Army's attempt to build a radar-pointed, long-range, anti-aircraft gun 相似文献
13.
The mass spectrometric determinations of the isotopic composition of helium in the solar wind obtained from (1) the Apollo Solar Wind Composition (SWC) experiment, (2) the Ion Composition Instrument (ICI) on the International Sun Earth Explorer 3 (ISEE-3), and (3) the Solar Wind Composition Spectrometer (SWICS) on Ulysses are reviewed and discussed, including new data given by Gloeckler and Geiss (1998). Averages of the 3He/4He ratio in the slow wind and in fast streams are given. Taking account of separation and fractionation processes in the corona and chromosphere, 3He/4He = (3.8 ± 0.5) × 10-4 is derived as the best estimate for the present-day Outer Convective Zone (OCZ) of the sun. After corrections of this ratio for secular changes caused by diffusion, mixing and 3He production by incomplete H-burning (Vauclair, 1998), we obtain (D + 3He)/H = (3.6±0.5) × 10-5 for the Protosolar Cloud (PSC). Adopting 3He/H = (1.5±0.2) × 10-5 for the PSC, as is indicated from the 3He/4He ratio in the planetary gas component of meteorites and in Jupiter (Mahaffy et al., 1998), we obtain (D/H)protosolar = (2.1 ± 0.5) × 10-5. Galactic evolution studies (Tosi, 1998) show that the measured D and 3He abundances in the Protosolar Cloud and the Local Interstellar Cloud (Linsky, 1998; Gloeckler and Geiss, 1998), lead to (D/H)primordial = (2 - 5) × 10-5. This range corresponds to a universal baryon/photon ratio of (6.0 ± 0.8) × 10-10, and to b = 0.075 ± 0.015. 相似文献
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15.
The author describes the MLS installation on runway 19L at Mid-Continent Airport, Wichita, Kansas, which has been operational since mid-1987. He describes the MLS equipment installation in his aircraft, which is one of a number of aircraft in the Wichita area that have been equipped with MLS equipment and routinely utilize the system. He summarizes his operational experience with the system. He reports complete satisfaction and increased versatility as a result of the guidance information provided 相似文献
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The author identifies societal needs that the engineer can help fulfil, and things that the engineer must do to accomplish this. He examines anti-engineering biases experienced by Galileo, the Challenger engineers, in the health effects of EMF fields, and in the economics of engineering-based activities. He proposes a number of corrective actions 相似文献
18.
The author examines a systems approach to automation that the printed circuit board (PCB) manufacturer can use in order to adapt today's technology for his or her individual needs. He begins with an overview of production functions. He then describes the subsystems approach, the steps leading to computerization, implementation, the bare board test system, and preprocessing 相似文献
19.
《Aerospace and Electronic Systems Magazine, IEEE》1992,7(1):51-53
The operations of the US Army Corps of Engineers' Manhattan Project, started on September 17, 1942, are examined as an example of US success in R&D 相似文献
20.
张康叶叶沛 《民用飞机设计与研究》2012,(3):41-48,65
首先阐述了当前背景下研究美国市场民用飞机运营成本的目的和意义,进而分析了民用飞机运营经济性领域不同研究主体关注的侧重点差异;然后归纳总结了美国市场多种飞机直接运营成本的构成要素和计算方法;最后,通过算例进行比较分析,确定出一种符合现今美国市场情况的DOC计算方法用于型号初步设计和市场推广。 相似文献