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831.
A. V. Tavrov O. I. Korablev A. V. Rodin I. I. Vinogradov A. Yu. Trokhimovsky A. Yu. Ivanov L. V. Ksanfomaliti D. A. Orlov 《Cosmic Research》2011,49(2):99-109
In order to observe exoplanets we propose a space-based achromatic stellar coronagraph combined with a 0.8–1.5 m telescope.
We develop an achromatic common path interferometer for observing an exoplanet (a faint off-axis source) on the background
of a hoste star (bright axial source). An image of the star and its copy acquire an achromatic phase shift by 180° and interfere
in antiphase. The achromatic phase shift is caused by geometric phase in the scheme of a three-dimensional interferometer.
The interference process divides spatially the dark and light fields of the star image redirecting them to the opposite sides
of a beam splitter. The interference process does not weaken the image of a planet, with equal intensities it is redirected
to both sides of a beam splitter. The suggested scheme of common path interferometer ensures mechanical stability. The background
signal is experimentally demonstrated to be reduced by six orders of magnitude. 相似文献
832.
回顾了利用大功率的高频电磁波调制电离层自然电流产生ELF/VLF电磁辐射的发展情况.介绍了典型加热设备的系统参数配置情况以及地面和卫星上检测ELF/VLF信号的实验结果.总结了提高ELF/VLF产生效率等问题的进展情况,尤其是"波束扫描"技术的理论研究和应用发展.提出了该技术下一步需要研究及解决的问题. 相似文献
833.
王宇 《郑州航空工业管理学院学报(管理科学版)》2008,26(5):103-108
通过金融深化增加农村家庭参与金融市场的机会,提高农村家庭的福利,让金融为广大农村家庭服务,改善其资源配置,解决农村金融抑制的问题,是当前金融改革与发展的一个重要内容。文章将农村家庭的实物资产分为生活型与生产投资型,将金融资产分为安全型和风险型,根据问卷调查获取的数据建立Logistic回归模型,对东部地区农村家庭实物资产配置和参与金融市场的决定因素进行研究,探讨当前农村的金融深化与金融发展路径。 相似文献
834.
介绍一种以线性调频半导体激光为光源的衍射光栅干涉仪。激光与光栅上衍射的±1级衍射波会合,由于有光程差而发生光拍频,测量拍频信号的相位移则可测得光栅的位移。设计了一种克服激光波长漂移和空气折射率变化影响的对称差动光路,使这种方法达到实用化的程度,分辨力达到纳米级。此外,还介绍了应用于接触干涉仪的实验情况。 相似文献
835.
H. Fuke J.E. Koglin T. Yoshida T. Aramaki W.W. Craig L. Fabris F. Gahbauer C.J. Hailey F.J. Jou N. Madden K. Mori H.T. Yu K.P. Ziock 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(12):2056-2060
We discuss current progress and future plans for the general antiparticle spectrometer experiment (GAPS). GAPS detects antideuterons through the X-rays and pions emitted during the deexcitation of exotic atoms formed when the antideuterons are slowed down and stopped in targets. GAPS provides an exceptionally sensitive means to detect cosmic-ray antideuterons. Cosmic-ray antideuterons can provide indirect evidence for the existence of dark matter in such form as neutralinos or Kaluza–Klein particles. We describe results of accelerator testing of GAPS prototypes, tentative design concepts for a flight GAPS detector, and near-term plans for flying a GAPS prototype on a balloon. 相似文献
836.
Yu. A. Kovalev V. I. Vasil’kov M. V. Popov V. A. Soglasnov P. A. Voitsik M. M. Lisakov A. M. Kut’kin N. Ya. Nikolaev N. A. Nizhel’skii G. V. Zhekanis P. G. Tsybulev 《Cosmic Research》2014,52(5):393-402
The results of a large number of the antenna radiometric measurements at bands of 92, 18, 6.2, 1.35, and 1.7-1.2 cm are presented by the data of the standard telemetry system of the Spektr-R spacecraft. Both special sessions of calibration object observations in the mode of a single space radio telescope (SRT) operation and numerous observations of researched sources in the mode of the ground-space interferometer were used. The obtained results agree with the first results of Kardashev et al. (2013), i.e., within 10–15% at bands of 92, 18, and 6.2 cm and 20–25% at the band of 1.35 cm. In the main, the measurements for the eight subbands at wavelengths of 1.7-1.2 cm indicate a monotonic increase in the spectral system equivalent flux density (SEFD) of noise radiation with a frequency consistent with the calculated estimates for the discussed model. The sensitivity of the ground-space interferometer for the five subbands at wavelengths from 1.35 to 1.7 cm can be higher by a factor of 1.5, and for the three subbands from 1.35 to 1.2 cm lower by a factor of 1.5 than at the band of 1.35 cm. The SRT contribution to the interferometer sensitivity proportional to the square root of SEFD is close to the design one at the bands of 92 and 18 cm and decreases the design sensitivity approximately by a factor of 1.5 and 2 at the bands of 6.2 and 1.35 cm, respectively. These differences of implemented values from the design ones were not significantly affected the scientific program implementation. 相似文献
837.
G. Krymsky P. Krymsky Yu. Romaschenko 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(4):15-18
The aim of this paper is to investigate processes in the magnetosphere and in particular the problems of the interaction of the solar wind with the Earth's magnetic field to produce large-scale convection, electric fields and longitudinal currents in the magnetosphere. The investigation is carried out in the frame of magnetic hydrodynamics. The reason for such an approach can be found in /1/. When calculating the transfer coefficients, the Böhm approximation is used, i.e. it is considered that the plasma in the near-equatorial part of the magnetosphere (quasiplanar geometry is used in the problem for simplification) is sufficiently turbulent that the condition ωτ ≈ 1 is valid (ω is the Larmor frequency of electrons, τ is effective time between two Quasi-collisions). The main subjects of investigation in this paper are the input near the equatorial boundary layer and the plasma layer of the magnetosphere tail. 相似文献
838.
导弹武器系统中有很多是多次使用的可修复杂系统。对于这种复杂系统,尤其是其寿命周期,预防维修时间及事后维修时间为离散分布时,其最佳预防维修周期难以用一般方法求得。针对这种情况,本文利用蒙特卡罗随机模拟法建立了系统计算模型,并通过模拟计算,得出了最佳预防维修周期的数字仿真结果。此结果可为制定导弹武器最佳修复策略提供依据。 相似文献
839.
Yu.K. Chasovitin V.B. Shushkova T.N. Sykilinda P.F. Denisenko V.V. Sotsky N.E. Shejdakov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(7):21-24
Our empirical model of electron density (ne) for quiet and weakly disturbed geomagnetic conditions (Kp not greater 4) takes account of comparative analysis of existing models and of experimental data obtained by rockets and incoherent scatter radar. The model describes the ne distribution in the 80 to 200 km height range at low and middle latitudes, and to some extent, in the subauroral region. It is presented in analytical form thus allowing one to calculate electron density profiles for any time. The electron density distribution at 140 km depends on the season (day of the year) and on the solar zenith angle. Profile variations during the day are for one season shown. Different from other models, ours specifies the variations during sunrise and sunset and reflects the particular profile shape at night admitting the occurrence of an intermediate layer. 相似文献
840.