An X-ray study of M51 (NGC 5194) and its companion (NGC 5195)

Observations of NGC 5194/95 with the Einstein HRI show a very strong nuclear X-ray source, surrounded by a diffuse flux, three point sources and the companion. The diffuse flux, which correlates well with the radio continuum, is likely to originate from the disk population with age 2·10⁹ yrs. The large luminosity from the nuclear source, together with optical and radio observations, shows that it belongs to the low luminosity active nuclei, thus extending this class to luminosities less than 10⁴⁰ erg/s.     

Some crucial X-ray observations — One or two SNR(s) in Crux?

A new EXOSAT (LE/CMA) observation of the region in Crux (R.A. 11h 45m, Dec. -62°) where Markert et al. (1981) reported the existence of two x-ray SNR's is presented. After cleaning the CMA field from the point source component, due to the UV emission of the numerous stars in the field, the smoothed x-ray contours are compared to the 408 MHz radio map of Caswell et al. (1983). The existence of two, well-separate x-ray emission regions is confirmed by EXOSAT, and the current x-ray/radio picture is not sufficent to distinguish clearly between the assumption of one or two (possibly interacting) SNR's in the region.     

X-ray scattering by intergalactic dust

The imaging capabilities of the Exosat and Einstein satellites at soft X-ray wavelengths have begun to show that suitable Galactic X-ray sources have extended ( 10 arcmin) haloes due to scattering of soft X-rays by interstellar dust. A simple argument suggests that similar haloes, due to scattering by intergalactic dust, should exist around distant (z 1) quasars and detailed analysis confirms this conclusion. A search for such haloes around suitable X-ray quasars could provide valuable, model-independent, constraints on the amount and origin of intergalactic dust.     

基于自联想网络的发动机传感器解析余度技术

本文提出了一种基于自联想神经网络的传感器解析余度技术。在这种网络中,冗余传感器的信息被压缩、重组进入网络的第一部分,网络的第二部分将压缩信息恢复出来。基于数据融合原理,若一个传感器发生故障,其它传感器仍可提供足够的信息代替发生故障的传感器。理论分析和用于涡轴发动机的仿真结果表明,这种特殊结构的自联想网络具有良好的过滤噪声和故障信号的作用,特别适合于用作不易建模的复杂对象的传感器信号重构     

A study of some interplanetary shock wave tendencies

The configuration, and the structure of shock waves from isolated solar flares and from a series of flares are discussed and classified.An invited paper presented at STIP Workshop on Shock Waves in the Solar Corona and Interplanetary Space, 15–19 June, 1980, Smolenice, Czechoslovakia.     

Electromechanical Actuation Technology for the All-Electric Aircraft

Electromechanical actuation is a critical element that must be developed and verified to make the all-electric aircraft a viable concept. For several years the Flight Control Division of the Air Force Wright Aeronautical Laboratories has sponsored activities to demonstrate the credibility of electromechanical actuation systems (EMAS) for primary flight control actuation functions. The foundation for these EMAS activities and several electromechanical actuation development programs are described here. One involves the design, fabrication, and laboratory test of a rotary, hingeline electromechanical actuator. Another involves the development and flight test demonstration of a linear electromechanical actuator for controlling an aileron of a C-141 aircraft. A third involves the design and development of a linear electromechanical actuator for missiles having severe performance, temperature, and volumetric requirements. In addition, a brief summary of the results from two aircraft actuation trade studies compare the baseline (conventional) hydraulic flight control system with an all-electric airplane concept including quantitative comparisons of weight, reliability and maintainability, and life cycle costs.     

Initial observations of low energy charged particles near the Earth's bow shock on ISEE-1

We report initial measurements from the ULECA sensor of the Max-Planck-Institut/University of Maryland experiment on ISEE-1. ULECA is an electrostatic deflection — total energy sensor consisting of a collimator, deflection analyzer and an array of solid state detectors. The position of a given detector, which determines the energy per charge of an incident particle, together with the measured energy determine the particle's charge state. We find that a rich variety of phenomena are operative in the transthermal energy regime (10 keV/Q to 100 keV/Q) covered by ULECA. Specifically, we present observations of locally accelerated protons, alpha particles, and heavier ions in the magnetosheath and upstream of the Earth's bow shock. Preliminary analysis indicates that the behavior of these locally accelerated particles is most similar at the same energy per charge.     

Design of a Correlator for Real-Time Video Comparisons

The problem of locating a reference image within a larger image using a correlation technique is discussed. Although the particular application discussed is that of locating a reference image obtained from one video sensor or a photograph, within the larger field of view obtained from a second video sensor in real time (i.e., at the TV field rate), the results are general and useful for a number of applications. The tradeoffs necessary to obtain real time correlat are discussed and their effect on correlation accuracy is given.     

Bounds on Elevation Error Estimates of a Target in Multipath

The Cramer-Rao bound for an unbiased estimate of the elevation angle of a target in the presence of multipath is calculated for the symmetric (target and image symmetric about the elevation symmetry plane of antenna) and nonsymmetric cases for an antenna consisting of 21 elements. These bounds are compared to the maximum likelihood estimates and it is found that the rms error of the maximum likelihood estimate (which has a bias) is below the Cramer-Rao bound for unbiased estimates.     

Planetary radio astronomy experiment for Voyager missions

The planetary radio astronomy experiment will measure radio spectra of planetary emissions in the range 1.2 kHz to 40.5 MHz. These emissions result from wave-particle-plasma interactions in the magnetospheres and ionospheres of the planets. At Jupiter, they are strongly modulated by the Galilean satellite Io.As the spacecraft leave the Earth's vicinity, we will observe terrestrial kilometric radiation, and for the first time, determine its polarization (RH and LH power separately). At the giant planets, the source of radio emission at low frequencies is not understood, but will be defined through comparison of the radio emission data with other particles and fields experiments aboard Voyager, as well as with optical data. Since, for Jupiter, as for the Earth, the radio data quite probably relate to particle precipitation, and to magnetic field strength and orientation in the polar ionosphere, we hope to be able to elucidate some characteristics of Jupiter auroras.Together with the plasma wave experiment, and possibly several optical experiments, our data can demonstrate the existence of lightning on the giant planets and on the satellite Titan, should it exist. Finally, the Voyager missions occur near maximum of the sunspot cycle. Solar outburst types can be identified through the radio measurements; when the spacecraft are on the opposite side of the Sun from the Earth we can identify solar flare-related events otherwise invisible on the Earth.