共查询到20条相似文献,搜索用时 15 毫秒
1.
We report Ariel V(SSI) observations of three X-ray pulsars A0535+26, 2S1145-619 and GX301-2 (2S1223-624). These sources exhibit X-ray outbursts which appear, on the basis of observations extending over 5 years, to have recurrence periods of 110 days, 187.5 days and 41.4 days respectively. If these periods are orbital in origin, the observed X-ray modulation may be explained in terms of an appreciable orbital eccentricity giving rise to time variable accretion. (In the case of GX301-2 published pulse timing data already provide independent evidence for a 41.4 day orbital period and an eccentricity e 0.4). The optical counterparts are all early-type stars; A0535+26 and 2S1145-619 are identified with Be main sequence stars and GX301-2 with a B2 supergiant which also shows an emission line spectrum. The implications of the observations in relation to possible mass transfer mechanisms in such systems are discussed. 相似文献
2.
We present the results of the spectral and timing analysis of an observation of GX9+1/4U1758-205 performed with the Medium Energy Experiment aboard EXOSAT. During our observation the source flux varied irregularly in time scales from minutes to hours. No periodic emission in the period range from 16 msec to 2000 sec was found with an upper limit of around 1% (3 ) for the pulsed fraction. The hardness ratio shows a correlated change with the flux intensity (Sco X-1 behaviour). The spectrum could be fitted by a double component model, a black body component (kT=1.16–1.26 keV) together with a thermal bremsstrahlung law (kT=13–15keV). The black-body temperature-black-body flux relation follows a Stefan Boltzmann law with RBB=15.3 km*D/10 kpc. No iron line was detected. The upper limit for the line equivalent width of a 6.7 keV iron emission line is 40 eV (1). The X-ray spectral behaviour of GX9+1 indicates, that this source belongs to the class of Low-Mass X-ray Binaries (LMXB). 相似文献
3.
L. Chiappetti 《Space Science Reviews》1981,30(1-4):447-449
Observations of GX 339-4 with the Ariel 5 spectrometer are reported. The spectrum of the source is very steep, possibily a low temperature blackbody or Bremsstrahlung distribution. Differences and similarities with the related sources Cyg X-1 and Cir X-1 are discussed. 相似文献
4.
X-ray source GX301-2 was observed with scintillation proportional counters in binary phase 0.90 to 0.05. Intense iron fluorescent emission and sharp iron K absorption edge appeared in all spectrum including flare, which occured on JD 2445814.6. The equivalent width are linearly correlated with column density and this can be interpreted by a simple model that cold isotropic gas surround compact source. Pulse fraction also changed inversely correlated way with column density which suggest smearing by scattering of x-rays in the reprocessing medium. Averaged iron K absorption edge energy was 7.36±0.02 keV. 相似文献
5.
6.
E. Kendziorra W. Collmar H. Brunner R. Staubert W. Pietsch 《Space Science Reviews》1985,40(3-4):361-365
From a short observation of GX 5-1 with EXOSAT we have derived information on spectral and temporal behaviour in the energy range 1–20 keV. The source was found to be variable on time scales from 10 s to 1 h. Describing the spectrum one is forced to assume at least two spectral components. The best fit is reached using a spectrum composed of two blackbody functions with typical temperatures 1 keV and 2 keV, corresponding to apparent blackbody radii of 43 km and 11 km, respectively (for a distance of 10 kpc). With respect to the hot component there is evidence for variability in temperature as well as in apparent blackbody radius. No periodic variability has been found over the period range 0.25 s to 2000 s. There is no evidence for an iron emission line. 相似文献
7.
利用OLYMPUS GX71金相显微镜及EDS对Al-15%Mg热压烧结样品进行金相显微组织观察与成分分析,探讨烧结过程中组织演变过程。实验结果表明:热压烧结过程中两种粉体发生互扩散,首先在Mg颗粒边缘形成γ(Al12Mg17)相,而后随扩散的进行γ相转变为β(Al3Mg2)相,Mg颗粒由外向内不断的形成γ相,而后不断的转变为β相,直到全部生成β相。随温度的降低,β相会以极其细小的颗粒形式析出;利用真空热压烧结方法在420℃,150Mpa下保压3—4h进行固相烧结获得密度低于2.5g/cm^3致密度达98%以上的Al—15%Mg合金。 相似文献
8.
CT5ATP在GTCP131-9BAPU管理中的作用 总被引:1,自引:0,他引:1
针对波音737NG机型GTCP131—9B辅助动力装置(APU)出现涡轮叶片移位的故障,分析了叶片移位对APU的影响,提出7CT5ATP方法.并结合南航的经验将其应用于GTCP131—9BAPU的管理中.确定了以CT5ATP作为启动值,结合修后使用时间(TSR)、孔探结论和后中心体盖裂纹检查作为完整性能监控的手段,为APU拆换提供了可信的实践依据,实现7APU单位维修成本的有效降低。 相似文献
9.
We review results of correlated IR, optical and X-ray observations of GX 339-4 made from March 1981 through May 1984. In the soft X-ray state, the object does not show outstanding optical and X-ray variability. Night-to-night smooth optical variations of 0.3 magnitudes were however present during one observing run. In contrast, the hard X-ray state is characterised by strong erratic optical and X-ray fluctuations on time scales from 20 milliseconds to seconds, as well as 7 to 20 second quasi-periodic oscillations. The optical counterpart appears much redder in the IR during the hard state. Particular attention is drawn to the hard to soft X-ray transition which occured in June 1981. The shape of the IR to X-ray energy distribution is discussed. The unusual features of this black hole candidate are examined in the framework of the current theories of accretion.Based partly on observations obtained at the European Southern Observatory, La Silla, Chile. 相似文献
10.
结合5架空客飞机退租的经验,对退租管理工作中的不足,围绕结构修理管理、工程管理和附件控制三方面进行了分析和探讨.并给出了有效的改进建议。 相似文献
11.
12.
13.
通过分析AS35083直升机装备的阿赫耶ARRIEL281发动机控制系统的原理,深入研究发动机控制系统引起的故障,从外场维护的角度提出快速确认故障部件的具体方案。 相似文献
14.
15.
通过对一定时期内6架某型老龄飞机的故障统计分析,根据飞机的技术状况以及故障的多发部位,从故障原因、故障预防和维护特点等方面提出了相应的维修预防措施。 相似文献
16.
《IEEE transactions on aerospace and electronic systems》1987,(2):215-224
The problem of parallel implementation of the square-root Kalman filters is addressed. At the system level, our approach is to apply systolic-type VLSI processor arrays as basic building blocks to accelerate the matrix operations required in each iteration. To maximize the parallelism, we also exploit an inter-array pipelining scheme through the overlapping of execution between successive processor arrays. We estimate that with (5n2 + r2 + 8nr + n + 3r)/2 processors, it would take max[(4n + 2r, 2n + 4r-2)] time units to complete one Kalman filter iteration, where n is the dimension of the underlying state space model and r is the dimension of the input vector. 相似文献
17.
18.
波音767飞机执行融合型翼尖小翼改装后可获得一系列飞行性能的提升,显著降低燃油成本,可为航空公司创造巨大的经济效益。本文介绍了实施改装中的关键技术以及一些技术问题的解决方案。 相似文献
19.
通过对老龄波音757飞机结构损伤特性的分析和隐蔽性等特点,建议实施有针对性、及时性、扩展性、构的安全。得出其具有集中性、蔓延性、严重性、重复性彻底性和双重性的维修,以确保老龄757飞机结 相似文献
20.
介绍了工业视频内窥镜测量技术的发展历程及民航孔探工作的常用测量方式,并从工作质量、工作效率以及安全角度考虑.推荐使用高精度、单视窗的三维测量技术。 相似文献