High and medium resolution spectroscopy of the X-ray transient 4U1543-47

Preliminary results of an EXOSAT observation of the transient X-ray source 4U1543-47 are presented. The source was observed in August 1983, during a high state, following a Tenma alert that the source was again active. Results from the GSPC and the LE 1000 l/mm grating are presented. The spectrum is complex, but in the 2–10 keV energy range can be well described by a Comptonised thermal distribution. Extrapolating the same model into the lower energy band of the grating requires an absorption column density equivalent to 2 × 10²¹ H cm². A marked under-abundance of Oxygen and overabundance of Nitrogen, along with a strong, unidentified line feature at 9.8 Å, are necessary to model the grating data.     

The use of gamma rays to trace the local interstellar hydrogen

COS-B data in the latitude range 11° <¦b¦ < 19° show the gamma-ray intensity to be closely correlated with the total line-of-sight absorption derived from galaxy counts. It is found that to a good approximation the gamma-ray intensity is proportional to the total gas column density, and on this basis a map of the angular distribution of local molecular hydrogen at intermediate latitudes is presented. Comparing this with a simular map produced from galaxy counts, several structures appear in both maps in regions related to Gould's Belt and elsewhere. Some regions in the Southern celestial hemisphere not accessible in galaxy counts show high molecular hydrogen column densities.Proceedings of the XVIII General Assembly of the IAU: Galactic Astrophysics and Gamma-Ray Astronomy, held at Patras, Greece, 19 August 1982.     

Sources of Solar Wind at Solar Minimum: Constraints from Composition Data

In this discussion of observational constraints on the source regions and acceleration processes of solar wind, we will focus on the ionic composition of the solar wind and the distribution of charge states of heavy elements such as oxygen and iron. We first focus on the now well-known bi-modal nature of solar wind, which dominates the heliosphere at solar minimum: Compositionally cool solar wind from polar coronal holes over-expands, filling a much larger solid angle than the coronal holes on the Sun. We use a series of remote and in-situ characteristics to derive a global geometric expansion factor of?～5. Slower, streamer-associated wind is located near the heliospheric current sheet with a width of 10–20°, but in a well-defined band with a geometrically small transition width. We then compute charge states under the assumption of thermal electron distributions and temperature, velocity, and density profiles predicted by a recent solar wind model, and conclude that the solar wind originates from a hot source at around 1 million?K, characteristic of the closed corona.     

Abell 1367 and 1060 observed with EXOSAT

Summary Two clusters of galaxies have been observed with EXOSAT to map the distribution of cool gas. For A1367 we have detected the two brightest sources found by EINSTEIN. We confirm the identification of a X-ray source with a blue object near NGC3842. By comparing the EXOSAT and the EINSTEIN count rates we can state, either that the source is variable, or that the HI column density is low and the spectrum is either a power-law with a spectral index > 1.5 or thermal with a temperature below 6×10⁶ K. For A1060 we confirm the classification from optical data of NGC3311 as the dominant galaxy but we find no evidence for a central source as inferred from the EINSTEIN data. We derive an accretion rate of 10M_o/yr.     

Elliptical vibration cutting of large-size thin-walled curved surface parts of pure iron by using diamond tool with active cutting edge shift

Large-size thin-walled curved surface parts of pure iron are crucial in aerospace, national defense, energy and precision physical experiments. However, the high machining accuracy and surface quality are difficult to achieve due to the serious tool wear and deformation when machining the parts with conventional cutting tools. In this paper, an elliptical vibration cutting (EVC) with active cutting edge shift (ACES) based on a long arbor vibration device is proposed for ultra-precision machining the pure iron parts by using diamond tool. Compared with cutting at a fixed cutting edge, the influence of ACES on the EVC was analyzed. Experiments in EVC of pure iron with ACES were conducted. The evolutions of the surface roughness, surface topography, and chip morphology with tool wear in EVC with ACES are revealed. The reasonable parameters of ultra-precision machining the pure iron parts by EVC with ACES were determined. It shows that the ACES has a slight influence on the machined surface roughness and surface topography. The diamond tool life can be significantly prolonged in EVC of pure iron with ACES than that with a fixed cutting edge, so that high profile accuracy and surface quality could be obtained even at higher nominal cutting speed. A typical thin-walled curved surface pure iron part with diameter ∅240 mm, height 122 mm, and wall thickness 2 mm was fabricated by the presented method, and its profile error and surface roughness achieved PV 2.2 μm and Ra less than 50 nm, respectively.     

机械蝴蝶模型悬停飞行的流动显示实验

为了探索蝴蝶独特的外形及运动模式下蕴含的流动机理，与以往只考虑翅膀气动影响的拍动翼实验不同，我们开发了一种同时考虑身体及翅膀的机械系统用以模拟蝴蝶的悬停飞行，并采用染色液流动显示的方法对升力的主要来源——前缘涡进行了细致的观测。结果显示，在蝴蝶飞行的上下拍动过程中均有前缘涡产生，且不是以往观测到的螺旋或锥状结构，而是近似等直径的柱状联通形式，其明显特征为：在拍动加速阶段存在明显的展向流动，而在减速阶段则会出现破裂；另外，蝴蝶看似杂乱无章的运动实际上是一种自适应控制的结果，有助于提高升力。     

翼型尾缘噪声源空间分布与辐射特性关系

详细研究了翼型湍流边界层尾缘宽频噪声源空间分布与辐射特性的关系.采用基于雷诺平均流场的翼型尾缘宽频预测方法研究了NACA0012翼型湍流边界层尾缘宽频噪声在4种不同工况下的噪声源空间分布与辐射特性.首先计算了NACA0012翼型湍流边界层尾缘噪声源在不同频率下的空间分布.计算结果发现:边界层中湍流是翼型湍流边界层尾缘噪声声源.随着频率的增加,噪声源强度和噪声源空间尺寸都是先增加后减小,噪声源位置不断靠近翼型尾缘.同时也计算了边界层内不同位置处的噪声源对远场噪声的辐射特性,结果表明:边界层内层区域,其噪声频谱能量集中在高频;边界层外部区域,其噪声能量集中在中低频;攻角增大或者来流速度减小,噪声能量向低频转移.      

EXOSAT observations of the BL Lac object Mkn 421

The BL Lac object Mkn 421 was observed by EXOSAT four times over a period of six days in February 1984. Significant X-ray variability was apparent on a timescale of less than a day, but with no accompanying spectral change. The source exhibited a very soft power law X-ray spectrum with an extremely low intrinsic column density (N_H10²⁰ cm^–2). There was no evidence for an additional hard component attributable to synchrotron self-Compton emission. The observations when combined with other published data imply that significant changes occur in the form of the broad-band UV/X-ray continuum of this source.     

基于彩色纹影的EdneyIV型激波相互作用研究

发展了一种高分辨率和灵敏度的彩色纹影技术,研究高超声速条件下EdneyIV型激波相互作用。解决了制作彩色滤光片的关键技术,采用特制的彩色滤光片代替了传统纹影系统中的刀口,高速彩色相机曝光时间60Vs,帧频6242fps。将光源限制在0．5mm×20mm的狭缝内以提高系统灵敏度。实验在马赫数为5的激波风洞内进行,EdneyIV型激波相互作用由15°斜劈和20mm直径钝头体产生,来流静压和静温分别为1800Pa和100K。数值模拟采用迎风格式求解三维RANS方程。实验得到了清晰的彩色纹影照片,细致地呈现了EdneyIV型激波相互作用的波系结构和马赫数为1．2的超声速射流。数值计算与实验结果很好地吻合,共同揭示了EdneyIV型激波相互作用机制和钝头体表面局部高压区域的形成原因。     

EXOSAT PSD and CMA observations of the SNR PKS 1209-52

EXOSAT PSD images and spectra are presented of the supernova remnant (SNR) PKS 1209-52 (G296.5+9.7. Milne 23). This source was observed for 8.5 hours in June, 1983. PSD images constructed in different energy intervals reveal that the spatial structure of the SNR is energy dependent. Comparison of the PSD and CMA images with the latest radio map of PKS 1209–52 shows some interesting correlations, especially between the X-ray and radio Hot Spots. The PSD spectrum of the SNR is fitted with a Raymond and Smith line-emission model: the best fit temperature is found to be 1.7×l0⁶ K and the absorbing column is less than 2×10²¹ cm^–2.A compact X-ray source lies within the radio shell of PKS 1209–52, near the centre of the remnant. The PSD spectrum of this object is somewhat harder than that of the SNR, but does not require a significantly different absorbing column density. The possible association of the SNR and the compact object is briefly discussed.     

示温漆图像等温线提取算法

分析示温漆（TIP）图像特征，根据等温线附近产生局部梯度极值的特点，实验对比了4种边缘提取算法效果。根据实验结果，选用Canny算子提取等温线。提出在边缘提取前进行K means聚类处理，并对K means聚类算法和Canny算子进行了改进。提出了两种K means初始聚类中心的选择方法，更适于示温漆图像的分割。改进了Canny算子的内核，提升了等温线的质量。结果表明:该算法能够快速提取清晰、连续的等温线，效果良好，满足工程应用要求，已用于示温漆自动判读软件开发。      

Large-scale structure of the Galaxy and high-energy gamma-ray observations

Detailed information on the high-energy gamma-ray emission from our Galaxy has become available through the two dedicated satellite missions SAS-2 and COS-B. The consistency of the two datasets is discussed; while a satisfying general agreement is observed, a few distinct discrepancies point to possible time variations within the compact source component of the total galactic emission. The bulk of emission appears very well correlated to the column density of the total interstellar gas, as traced by radio observations of Hi and CO. The gamma-ray observations exclude the possibility that H₂ dominates in the inner Galaxy, its mass should not exceed the mass existing in the form of Hi. Neither a significant galactocentric gradient of the (high-energy) cosmic-ray flux density is suggested inside the solar circle (outside a decrease is needed), nor a linear coupling between the cosmic rays and the gas is indicated by the gamma-ray data. The systematic variation with longitude of the spectrum of the gamma-ray emission points to an increased flux of cosmic-ray electrons in the 100 MeV to 1 GeV energy range in regions where dense clouds are concentrated. The variation could as well be due to the largely unresolved population of compact gamma-ray objects.     

TiA1双层辉光离子渗Cr的工艺研究

利用双层辉光离子渗金属技术（DGPSAT）对TiAl金属间化合物进行渗Cr处理。研究了主要工艺参数对渗层表面合金含量CA和渗层厚度δ这两个目标函数的影响。结果表明,表面合金含量CA和渗层厚度δ随源极电压Vs、有效功率密度比κ的增加而增加;随阴极电压Vc的增加而减少。气压存在一个峰值,太高或太低都不利。工艺参数的最佳值:源极电压Vs为1200V～1300V,阴极电压为200V～300V,有效功率密度比κ为4～5,气压为25Pa～30Pa。     

陀螺仪气室中碱金属原子数密度的检测

碱金属原子作为原子陀螺仪原子源的组成部分，其数密度是计算原子陀螺仪工作指标的重要参数。基于碱金属原子对不同激光失谐的吸收程度不同，提出了一种通过拟合碱金属原子吸收光谱得到碱金属原子数密度的测量方案。不同于以往的吸收测量法，该方案针对实际实验温度和气体压强等条件，对吸收谱拟合式进行了修正，从而提高了测量结果的准确度。测量结果与理论计算结果相吻合，两者偏差仅1.2倍左右，并可进一步应用于校准气室内碱金属蒸气的实际温度值。     

各向异性陶瓷基复合材料涡轮叶片概率性热分析方法

考虑陶瓷基复合材料等纤维增韧复合材料导热系数的各向异性及分散性，建立了基于概率统计的陶瓷基复合材料涡轮叶片热分析方法。研究中以Mark Ⅱ涡轮叶片冷却结构为例，综合利用有限元方法和蒙特卡洛方法，分析了应用陶瓷基复合材料后的温度场均值和波动特性。计算中将导热系数作为随机输入参数，分析了导热系数各向异性及其分散度对叶片前缘滞止点温度、尾缘温度以及高温区域（T>900K）面积的影响。计算中发现在本文的计算工况下,考虑导热系数存在正态波动情况时，叶片前缘滞止点、尾缘温度波动也满足正态分布。前缘滞止点温度在导热系数变异系数为01,导热系数比为2时其温度波动最大，相比12731K的均温，有16%的概率超温913K。尾缘温度在导热系数变异系数为01，导热系数比为10时波动最大，有16%的概率超过均值11529K达527K。计算结果表明:导热系数分散度所带来的波动，会导致叶片内部高温关注区域（T>900K）的面积增大，并且高温关注区域相对增加量ΔShot随导热系数变异系数α的增加而增加。计算结果表明，高温关注区域相对增加量最大发生在导热系数比为2，变异系数为0.1时，此时ΔShot=4.8%。      

The X-ray imaging telescopes on Exosat

The instrument configuration and performance characteristics of the X-ray imaging telescopes on EXOSAT are described. The instrument comprises two fully independent Wolter I imaging telescopes. Each telescope can be used in either of two principal modes: (i) an imaging mode with either a position sensitive proportional counter or a channel multiplier array plate in the focal plane, (ii) a spectrometer mode which features a 500 lines/mm and/or a 1000 lines/mm transmission grating as dispersive element.Preliminary results from the calibration of the fully integrated experiment indicate an ultimate angular resolution of 8.5 arc sec full width at half maximum or 17.5 arc sec half-power beam width. The ultimate wavelength resolution in the spectrometer mode ranges from 1Å for wavelengths below 50Å, to 5Å at wavelengths near 300Å.A method for estimating the telescope performance is given which reasonably accounts for the influence of the X-ray source spectrum and the degree of interstellar absorption on the counting statistics.A comparison between EXOSAT and the EINSTEIN telescope in terms of band width/resolution and minimum source detectability shows an enhanced potential for EXOSAT relative to EINSTEIN for sources with T 10⁷K and low column densities (< 4 × 10²⁰cm^–2) and a reduced potential for sources with hard, or heavily cut-off, spectra.     

航空煤油RP-3结焦产物的物性

在环境温度为800K和900K条件下,获取RP-3航空煤油结焦产物,通过试验获得表观形貌及物性,拟合了结焦产物的比热容和导热系数随温度变化的经验关系式。结果表明:航空煤油结焦产物的微观结构为球状颗粒堆积且表面存在可见孔隙,表观密度约为1 049kg/m~3,真密度约为1 498kg/m~3,孔隙率约为29.9%,环境温度为800K下生成的油焦真密度较900K下生成的小;通过闪光法测得油焦比热容约为1.1~2.2J/(g·K),导热系数约为0.19~0.28W/(m·K),比热容和导热系数均随着温度的升高而增加,环境温度为800K下生成的油焦比热容和导热系数较在900K条件下生成的略大。     

2A0526-328: The white dwarf rotation period revealed

We report results from EXOSAT observations of the intermediate polar system 2A0526-328 (TV Col). The hard X-ray emission (2–8 keV) is modulated with a period of 1943 s, interpreted as the white-dwarf rotation period. Soft and hard X-ray emission show intensity minima, in phase with the orbital period of 0.2286 days; analysis of the hard X-ray spectra shows that these minima are caused by an extra low-energy absorption corresponding to a H column density of 4 × 10²² cm^-2.     

典型前缘结构抗鸟撞性能改进研究

 针对某典型前缘结构,研究了使用纤维金属层板(Fibre Metal Laminates,FMLs)蒙皮进行抗鸟撞设计的可行性。以显式动态冲击分析程序PAM-CRASH为平台,结合由鸟撞平板试验结果验证的鸟体本构模型参数,建立了鸟撞前缘结构数值模型。通过计算研究了使用不同蒙皮(铝合金、FMLs)的前缘结构在鸟撞作用下的变形破坏模式及吸能效果。结果表明：采用适当铺层的FMLs蒙皮可以有效地提高前缘结构的抗鸟撞性能。研究结论对飞机结构的抗鸟撞研究具有一定的参考价值。     

无纺布织物涂层的吸波性能

以无纺布为基材,采用叠层式结构制备无纺布织物涂层吸波材料。用3 cm波导测量系统在9.35GHz研究复合吸波剂(羰基铁粉和乙炔炭黑)含量和叠层结构对材料吸波性能的影响。结果表明,这种以无纺布为基材的吸波材料,通过控制吸波涂层的组成和设计合理的结构,增加入射电磁波与吸波材料的作用几率,可以改进材料的吸波性能并降低材料面密度。