Earthshine and Asteroseismology Telescope (East) Network

Several automated optical telescopes have been setup at appropriate longitudes around the globe to study earthshine variations and asteroseismology. The first telescope has been setup at Teide Observatory, Tenerife, Spain in October 2004. The intensity of earthshine relates to the average of Earth’s albedo, and in turn relates to the global temperature of the Earth. A global network is necessary because each site can measure the earthshine reflected from only a part of the Earth. The network will also be used for asteroseismology study. It can measure photometric variations of pulsating stars. The long-term and continuous measurements allow the accurate determination of mode frequencies of stellar pulsations, which provides information on the properties of stellar interior.     

The Far Ultra-Violet Imager on the Icon Mission

ICON Far UltraViolet (FUV) imager contributes to the ICON science objectives by providing remote sensing measurements of the daytime and nighttime atmosphere/ionosphere. During sunlit atmospheric conditions, ICON FUV images the limb altitude profile in the shortwave (SW) band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular to the satellite motion to retrieve the atmospheric O/N₂ ratio. In conditions of atmospheric darkness, ICON FUV measures the 135.6 nm recombination emission of \(\mathrm{O}^{+}\) ions used to compute the nighttime ionospheric altitude distribution. ICON Far UltraViolet (FUV) imager is a Czerny–Turner design Spectrographic Imager with two exit slits and corresponding back imager cameras that produce two independent images in separate wavelength bands on two detectors. All observations will be processed as limb altitude profiles. In addition, the ionospheric 135.6 nm data will be processed as longitude and latitude spatial maps to obtain images of ion distributions around regions of equatorial spread F. The ICON FUV optic axis is pointed 20 degrees below local horizontal and has a steering mirror that allows the field of view to be steered up to 30 degrees forward and aft, to keep the local magnetic meridian in the field of view. The detectors are micro channel plate (MCP) intensified FUV tubes with the phosphor fiber-optically coupled to Charge Coupled Devices (CCDs). The dual stack MCP-s amplify the photoelectron signals to overcome the CCD noise and the rapidly scanned frames are co-added to digitally create 12-second integrated images. Digital on-board signal processing is used to compensate for geometric distortion and satellite motion and to achieve data compression. The instrument was originally aligned in visible light by using a special grating and visible cameras. Final alignment, functional and environmental testing and calibration were performed in a large vacuum chamber with a UV source. The test and calibration program showed that ICON FUV meets its design requirements and is ready to be launched on the ICON spacecraft.     

纤维复合材料的形变功密度断裂准则

通过单边缺口、中心裂纹和中心圆孔碳/环氧和玻璃/环氧复合材料层合板试样的试验证实,在考虑了材料的各向异性后,把各向同性材料的J积分分析结果用于确定复合材料层合板的断裂过程区特征长度d₀是适宜的。 根据碳/环氧复合材料层合板的有限元分析结果和试验观察,提出了一个新的断裂准则 σ_y（d0,0）ε_y（d0,0）=ασ_Fε_F 称为形变功密度断裂准则。这个准则已得到试验验证。使用本文方法可以得出不随试样几何形状和应力分布而变化的特征长度。     

空间科学实验机器人辅助遥操作系统

建立了一个面向空间舱内晶体生长科学实验的地面模拟机器人遥操作系统。该系统通过基于虚拟现实的预测仿真来克服通讯时延的影响，并通过仿真图形和实际视频图像的叠加来对虚似仿真环境进行校准，以提高预测仿真的保真性。操作员利用空间鼠标等人机交互工具实时控制仿真机器人系统的运动，通过遥控与自主相结合的方式，并借助全局和局部视觉信息，完成了在空间晶体生长科学实验中更换晶体炉料棒的作业任务。     

Development and verification of an innovative photomultiplier calibration system with a 10-fold increase in photometer resolution

In this study, we construct a photomultiplier calibration system. This calibration system can help scientists measuring and establishing the characteristic curve of the photon count versus light intensity. The system uses an innovative 10-fold optical attenuator to enable an optical power meter to calibrate photomultiplier tubes which have the resolution being much greater than that of the optical power meter. A simulation is firstly conducted to validate the feasibility of the system, and then the system construction, including optical design, circuit design, and software algorithm, is realized. The simulation generally agrees with measurement data of the constructed system, which are further used to establish the characteristic curve of the photon count versus light intensity.     

快速计算虚拟物体之间精确接触位置的算法

在触觉、力觉交互的虚拟现实系统中,快速计算虚拟物体之间精确接触位置是触觉、力觉交互碰撞检测系统的前提.在这样的系统中虚拟物体大多是多面体模型且是三角形模型,采用层次包围盒法判断物体是否相交,如果相交,采用本文提出的二级检测算法快速计算出物体的接触位置.该算法首先判断那些相交三角形是异面还是同面,如果是异面,求出一个三角形T₂与另外一个三角形T₁所在平面的交线,然后再判断该交线与T₁之间的位置关系,进而求出有效的相交线段;如果是同面,需要判断两个三角形之间相互位置关系,然后有针对性地求出相关线段之间的交点,从而求出三角形的相交区域.最后用实例验证了该算法的有效性和鲁棒性.     

深空遥测系统中信道编码简述

由于深空信道的极低的信噪比,具有高增益的信道编码技术是深空遥测系统必不可少的环节。总结了深空通信领域中曾经使用的或可能使用的各种典型的信道编码包括卷积码、级联码、TURBO码和LDPC码方式,并对各种编译码方式的特点进行比较,给出其性能仿真。最后,对深空通信信道编码技术(包括TURBO接收机、LDPC码的应用以及编码调制技术)未来发展作展望。     

The Progress of the Taiwan Oscillation Network Project

We describe the present status of the project of the Taiwan Oscillation Network (TON) and discuss a scientific result using the TON data. The TON is a ground-based network to measure solar intensity oscillations for the study of the solar interior. Four telescopes have been installed in appropriate longitudes around the world. The TON telescopes take K-line full-disk solar images of diameter 1000 pixels at a rate of one image per minute. The data has been collected since October of 1993. The TON high-spatial-resolution data are specially suitable for the study of local properties of the Sun. In 1997 we developed a new method, acoustic imaging, to construct the acoustic signals inside the Sun with the acoustic signals measured at the solar surface. From the constructed signals, we can form intensity map and phase-shift map of an active region at various depths. The direct link between these maps and the subsurface wave-speed perturbation suffers from the poor vertical resolution of acoustic imaging. Recently an inversion method has been developed to invert the measured phase travel time perturbation to estimate the distribution of wave-speed perturbation based on the ray approximation. This technique of acoustic imaging has been used to image the far-side of the Sun that could provides information on space weather prediction. The TON Team includes: Antonio Jimenez (Instituto Astrofisica de Canarias, Spain); Guoxiang Ai and Honqi Zhang (Huairou Solar Observing Station, P.R.C.); Philip Goode and William Marquette (Big Bear Solar Observatory, U.S.A.); Shuhrat Ehgamberdiev and Oleg Ladenkov (Ulugh Beg Astronomical Institute, Uzbekistan) This revised version was published online in August 2006 with corrections to the Cover Date.     

基于手眼视觉的测量与定位方法的研究与实现

机器视觉对机器人克服工作环境中的不确定性具有重要意义。针对空间遥操作机器人面对的是危险不确定环境，文中提出一种基于手眼视觉的测量与定位方法，可为判断示知目标物体是否可抓持以及进行抓持规划提供有效依据。在重复定位的任务中，该方法可以利用目标物质的先验信息快速定位从而避免频繁移动手臂。文章首先给出了该方法的原理，然后通过实验实现了此方法，并对误差进行了分析，实验结果表明了该方法具有较高的精度。     

单框架控制力矩陀螺系统的运动奇异及回避

为满足航天器姿态三轴控制的要求,通常在姿态控制系统中采用3个或以上的单框架控制力矩陀螺(SGCMG).当多个SGCMG协调工作时,系统会出现奇异现象.在研究SGCMG系统的运动奇异机理及零运动的基础上,提出了一种判别奇异状态可回避性的新方法.该方法把对奇异状态可回避性的判别转化为对一组非线性常微分方程的定性研究.以某4-SGCMG系统为例,验证了上述方法的可行性.