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951.
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
952.
介绍了一种其电路原理与脉冲计数式仪表不同的数字转速表电路。它将输入脉冲经频率一电压转换器(PVC)变换成与之成正比的直流电压,采用数字电压表显示测量结果。文中详细地论述了FVC的工作原理,分析了整机电路,最后给出了实验结果。 相似文献
953.
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
954.
Control Moment Gyroscope (CMG) is an effective candidate for agile satellites and large spacecraft attitude control because of its powerful torque amplification capability. The most serious situation, however, in using CMG is the inherent geometric singularity problem, where there’s no torque output along a particular direction. Space expansion method has been proposed in this work for the singularity analysis. Based on inverse mapping transformation, an expanded Jacobian matrix which is a full rank square matrix is obtained. The singular angle sets of the 3-parallel cluster and pyramid cluster are distinguished using space expansion method. An effective hybrid steering strategy, able to deal with the elliptic singularity, is further proposed. Simulation results demonstrate the excellent performance of the proposed steering logic compared to the generalized singular robust logic and pseudo inverse logic in terms of energy consumption and torque error. 相似文献
955.
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
956.
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
957.
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
958.
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
959.
960.
本文介绍了一种新的试件栅拷贝技术,结合空间虑波,条纹倍增及光学图像处理技术,可以测定轴、旋翼、柱壳及锥壳等曲表面裂纹尖端附近弹塑性应变场。该方法甚至还可以适用于转动的轴、飞轮和旋翼等表面应变场的测量。 相似文献