空间目标在天基光电望远镜中的光度特征研究

本文重点研究了天基光电望远镜对空间目标成像时空间目标、望远镜，太阳之间的相对位置关系。文章分析了天基光电望远镜对空间目标成像时三者的位置关系及其变化对目标光度特征的影响，以及望远镜系统参数对空间目标成像光度特征的影响；给出了太阳直射奈件下的空间目标成像条件。通过计算机仿真模拟了考虑目标在望远镜处的光度特征，以及在天基光电望远镜中的成像目标-星空图。研究结果表明，文中方法能有效地描述空间目标在天基光电望远镜中的光度特征。     

天文学自适应光学成像望远镜的模拟

为分析天文学自适应光学(AO)望远镜中AO系统的校正性能,利用Matlab仿真其成像过程。采用正交基为Zernike多项式的自相关法产生符合大气统计特性的大气相位屏,仿真平行光通过大气后的瞬时畸变波前相位;采用快速傅里叶变换仿真哈特曼-夏克波前传感器的成像光斑,根据实际成像与参考平面波成像的质心坐标之差,计算波前传感器子孔径内的平均波前斜率。模拟比较了1.2m望远镜两种AO系统布局的校正性能,结果表明,子孔径为正六边形AO系统的校正性能略优于子孔径为正方形AO系统的校正性能,两种AO系统的SR比(StrechlRatio)分别为0.872和0.859。     

星敏感器图像模拟及目标背景运动特性分析

考虑了星敏感器的方位和俯仰角度,给出了一种星空背景和目标的星敏感器序列图像模拟方法.利用TLE轨道根数与SGP4/SDP4模型计算出星敏感器和目标的精确位置和速度.考虑了传感器坐标系、星体坐标系、2000.0地心惯性坐标系三者的关系,对背景和目标分别计算其在CCD中的成像位置和灰度值并叠加生成序列图像.最后在图像仿真的基础上,分析了图像中背景与目标的运动性质.对背景和目标在图像中运动性质的分析结果对于弱小目标图像检测问题的解决也有帮助.     

带太阳能帆板的卫星光度特性分析

从辐射理论出发,对太阳可见光波段大气层外辐照度理论值进行了1/1.07倍的修正,推导出构成卫星的两种基本漫反射表面的地面照度计算公式,再由太阳、卫星和观测站在地心赤道坐标系中的位置矢量关系,算出它们的具体值。理论计算表明,虽然太阳能帆板的漫反射率要比卫星主体低30倍,但在卫星地面照度的计算和实际观测中仍不应忽略。     

RRR及RRC机械臂运动学建模与分析

运动学分析对于机械臂在实际工业应用中具有重要意义。本文针对平面RRR型机械臂、空间RRR、RRC机械臂这3种典型的工业机械臂进行了正运动学分析。首先建立坐标系,得到各坐标系之间的变换矩阵,即可得到机械臂末端位置与机械臂驱动关节之间的关系。机械臂末端执行器在末端坐标系中的坐标可根据得到的变换矩阵转换为在基坐标系下的坐标。最终通过机械臂的特殊位置,验证了正运动学建模分析的正确性。     

卫星490NG发动机复材支架测调方法改进

该文针对卫星490NG发动机复材支架测调工作存在经纬仪测调效率低、误差大、调整过程精度不易控等问题。提出了1种基于激光跟踪仪测调安装模板定位销孔位置度进而保证发动机复材支架精度方法,通过图纸解算出发动机模板三销孔在整星坐标系中的相对位置坐标,利用激光跟踪仪实时监测,将测调过程中的模板移动数值量化,操作人员能直观、准确地完成测调。通过试验,验证了该方法的有效性和实用性。     

机器人与激光跟踪仪的坐标系转换方法研究

激光跟踪仪对工业机器人的末端位姿进行绝对定位精度标定时,需要把测量坐标系和机器人坐标系下的坐标值转换到同一坐标系下,坐标值的比较才有意义。因为机器人运动学模型误差的存在,使得机器人坐标系下的点不能遵循着唯一确定的变换关系变换到测量坐标系,所以坐标系的变换精度不高。在建立齐次变换形式的变换模型之后,通过分析坐标系变换过程中的误差来源,提出结合最小二乘法的RANSAC快速转换算法。从测量样点中随机选择一定量的样点拟合变换模型,在获得多个变换模型之后,利用评判模型选择最优模型。结果表明:相比于常规的求解方法,机器人和激光跟踪仪的坐标转换精度提高3倍。RANSAC算法能有效地降低机器人模型误差对求解变换关系的影响,并且实验过程快速、操作简单。     

大模数分段齿单齿段的三坐标检测

本文基于三维数模的三坐标检测方法的基本原理,把零件的三维数模导入到三坐标测量机的检测软件中,并通过坐标系的对齐,使机器坐标系与工件坐标系保持一致,然后通过捕获零件的理论坐标与检测得到的工件的实际坐标点相比较。通过三维数模的导入、坐标系的对齐、三坐标测量机自动检测、测量结果评定及模拟装配等检测步骤完成整个检测过程。     

中国“哈勃”——空间太阳望远镜2005年后升空

中国“哈勃”———“空间太阳望远镜”将于2005年后发射升空,对太阳活动实行全波段和全连续观测。据国家天文台一位负责人介绍,有中国“哈勃”之称的空间太阳望远镜是我国第一个天文观测卫星,望远镜口径一米,卫星总重量达两吨,是目前世界上最大的热光学望远镜,上面配有多种望远镜。届时,中国“哈勃”将被安装在卫星上,由长征四号乙型火箭将其发射至太空,在距地709公里的太阳同步圆形极轨上以始终指向太阳的姿态运行。在3年寿命期内,实行24小时连续工作。据悉,中国“哈勃”由中国空间技术研究院和中国科学院国家天文台联合研制。国家天文台…     

月球车双目视觉避障像机标定

针对等距投影鱼眼成像模型,本文提出通过标定场方法对月球车避障像机进行自标定光束法平差,对月球车双目视觉避障像机的内参数、相对外参数进行标定。采用标定得到的参数,对摄影测量标志进行三维坐标恢复,得到标志在避障像机坐标系下的三维坐标。将该三维坐标与已知的三维坐标进行比较,利用比较的偏差结果评定避障像机的标定精度。实验结果表明,该方法完全满足避障像机标定精度要求。     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.     

Mechanism Study on the Wear of CrAlTiN Coated High-Speed Steel Twist Drills Under Dry Cutting Conditions

As demands about environment protection are growing up, dry cutting technology is getting more and more concerns from all over the world. Main works performed here are study on dry cutting performances and wear mechanisms of M2high-speed steel (HSS) twist drills with CrAlTiN multicomponent coatings, which was deposited using magnetron sputter ion plating system, in drilling 45 and 30CrMnSiA steel, and their comparisons to those in drilling the same steel but using monolayer CrN and commercial TiN coated drills. Drilling performances of drills are evaluated mainly through the measurements of width on outer corner flank land and the cutting forces. Results show that performances of CrAlTiN coated drills are better than those of monolayer CrN and TiN coated drills. In drilling 45 and 30CrMnSiA steel, the average tool life of the CrAlTiN coated drills are 17.2 and 11.8 times higher than those of the uncoated drills. Observing wear of the drill with scanning electronic microscope, results show that there is no crack or spallation of the CrAlTiN coatings in wear zones. Main mechanism of the wear here is adhesion.     

Study on Bond Ability of Arc-Spraying Coatings with Different Surface Pretreatment on Cast-Iron

Arc spraying coatings are widely used in various applications, but uncommon in cast iron substrate. Different surface pretreatment technology is tested on substrates of gray cast iron. Surface roughness and residual stress were measured by TR200 and X-ray diffraction analyzer. Influence of different surface pretreatment methods ( dry blasting and fusebond) on roughness and residual stress was analyzed. The arc-sprayed coatings of wire 3Cr13 (φ2mm) on gray cast iron substrate is studied. The microstructure and interface of bonding layer were observed by SEM. The bond strength was taken by tensile test. Results show that bond strength with grit blasting is higher than fuse-bond; it is feasible to make wire 3Cr13 coating with arc spraying on cast iron substrate roughened by grit blasting.     

Structural Characteristics of TiO2 Ceramic Coating by Micro-Plasma Oxidation

TiO2 ceramic coatings with thickness of 20 μm were formed on the surface of pure titanium by micro-plasma oxidation. Their micro-structures were investigated by by using X-ray diffraction and their surface images were detected by using scan electronic microscope. There were three kinds of TiO2 coatings, pure anatase type TiO2 phase, mixed phases consisted of rutile type TiO2 phase and anatase type TiO2 phase, pure rutile type TiO2 phase. The coating surface with the pure anatase type TiO2 phase is rough, while the coating surface with the pure rutile type TiO2phase is smooth. The upper coating surface with the mixed type TiO2 phases is anatase type TiO2 structure and the subsurface of the TiO2 coating is rutile type TiO2structure.     

Evaluation of fatigue life of steel using steel grain size

The insightful discussion of the relationship between the construction of metallographic and fatigue life and proposition of mathematical relationships describing this relationship was conducted in the paper. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the grain size and the participation of ferrite and pearlite phase.