光学观测中几种太阳夹角计算方法及精度分析

为从计算太阳夹角的所有简单算子中,找到最接近真实值的可靠算法组合,做此实验。完成对太阳赤纬、太阳时角的常见算法公式的演算,并介绍了天文观测中会涉及到的一些基础的天文概念,完成对太阳高度角和方位角的算法演算,同时考虑蒙气差等干扰因素,加入到计算当中,最后完成对在指定地理位置设备与太阳之间的夹角数值的计算。在本次计算中,采用精度较高的复杂算法SPA算法作为参考值,对上述算法的计算结果进行鉴定,以比较上述算法计算结果的精度误差,并进行统计分析。在实验中,使用C++工具代码实现算法的运算。通过对演算结果的定量比较分析,确定了VSOP87的时角算子与Wang赤纬角算子的组合,其计算结果最为真实可靠。通过实验分析,找到了既简单可行,又具备较高准确度的太阳夹角算法组合,为提高简单算法得到的太阳夹角值的准确性起到了积极作用。     

观测几何对目标探测性能影响的仿真分析

在光电武器作战探测目标性能问题的研究中,不同大气/气溶胶模式、不同观测几何条件下的光电武器作战效能差异显著.针对上述问题,通过分析大气传输和观测几何对视在对比度的影响,建立了视在对比度传递模型,结合TIP准则提出了观测几何对目标探测性能的影响模型.利用Modtran软件离线计算的基础数据,提出了探测性能模型快速仿真计算方法,实现了典型地区、全天时、不同观测几何和观测距离条件下的成像系统探测性能的快速仿真计算.采用快速仿真计算方法,选取典型参数,计算并分析了不同大气/气溶胶模式、观测几何等因素对视在对比度、探测概率和探测距离等指标的影响.结果表明:观测几何对目标探测性能影响显著,50％探测概率条件下,顺光探测距离是逆光探测距离的1.38 ～1.7倍;不同大气/气溶胶模式条件下,观测几何对探测距离影响差异明显,海洋性气溶胶模式下影响较大,乡村型气溶胶模式下影响较小.文中提出了观测几何对目标探测性能的影响模型和快速仿真计算方法,为光电武器系统任务规划和作战效能评估提供了理论和技术支持.     

针对GEO目标带的天基光学观测姿态规划研究

为了提高太阳同步轨道卫星对GEO轨道带目标的观测效率,在分析观测位置和传感器视轴指向与太阳同步轨道卫星对静止轨道带扫描速度基础上得到传感器视轴的最佳指向以及对应的GEO带上的最佳观测点,并提出了关于最佳观测点的姿态规划策略,并对在地影影响下有/无姿态机动时的观测效率进行了对比仿真分析.仿真结果表明:对于SBV传感器视场在1.5°×1.5 °时,最佳观测点的控制策略就能够完成对GEO轨道带的完全覆盖,相较于无姿态机动时,对静止轨道带的观测时间可提高一倍.     

植被结构及太阳／观测角度对NDVI的影响

在文献「１」中作者建立了计算多组分植被方向反射系数的综合解析模型。本文采用该模型研究植被空间结构对常用的归一化植被指数的影响。文中讨论了ＮＤＶＩ与叶角分布，植被组分的特征尺度和它们夺空间的散布方式，以及非叶器官面积在总面积中所占璋的依赖关系。同时给出 ＮＤＶＩ随太阳／观测角度的变化情况。     

用于超小型地球观测卫星的基本APS的微型太阳敏感器

本文介绍那不勒斯(Naples)大学对于用在微型与超小型卫星姿态确定系统中的一种基于APS的低成本微型太阳敏感器的研究工作与样机开发情况，阐述这种敏感器的总体结构以及样机和实验室测试设备的开发工作。开发该敏感器的数字仿真器也是本项目的重要内容。这种仿真器用来预测敏感器性能，并模拟样机的实验室测试。初步结果显示，敏感器最终精度优于1’。     

一种遥感图像太阳—观测几何归一化方法

宽空间覆盖、高观测频率传感器往往具有较大的观测视场,大观测视场带来的问题是不同位置和不同时间的太阳—观测几何不同。因此,在半经验的核驱动BRDF模型基础上,提出一种新的模型用于遥感数据太阳—观测几何归一化,利用植被指数组成的二次多项式作为基于核驱动的半经验BRDF模型中体散射部分和几何光学散射部分的核系数,并使用目标在不同时间的多角度观测数据反推用于太阳—观测几何转换的模型系数。分别利用红色和近红外波段的模拟数据和真实观测数据对模型进行验证,结果表明新提出模型的模拟值与真实观测值具有较好的一致性,能够应用于遥感图像的太阳—观测几何转换。     

太阳位置传感器设计

传感器是跟踪型太阳能装置中一种重要的电子元器件,它直接影响太阳能的利用效率。通过介绍太阳运行规律,结合目前常用的太阳跟踪方案,提出了一种跟踪方案,并由此设计了具有能主动搜索太阳位置的大范围、高精度的太阳位置光电传感器,完成了其机械结构、电路设计,详细阐述了传感器的工作原理及性能,最后通过仿真分析验证了传感器设计的正确性,为同类型设计提供借鉴。     

基于HPLC-UV与空间夹角判据的化妆品中对羟基苯甲酸酯分析

将HPLC-UV法与空间夹角判据结合,建立了化妆品中对羟基苯甲酸酯定量分析方法。通过高效液相色谱对待测样本进行分离,构建不含被测组分的本底数据库,基于空间夹角法步骤批量测定了化妆品样本中对羟基苯甲酸酯。结果表明:该方法计算结果和高效液相色谱分析结果接近,相对误差小于5.00%,回收率为97.95%~101.83%,RSD值为1.05%。方法快速、准确,降低了试剂消耗量,为降低化妆品的检测成本和现场分析提供了可行方案。     

基于夹角符号序列的凸多边形直径算法

对一个凸多边形直径算法———夹角序列法,进行了较为深入的分析和研究,并在此基础上提出了夹角符号序列算法。算法分别讨论了利用求夹角正切值符号序列和余弦值符号序列来求解凸多边形直径的两种途径,并给出了各自的算法实现,最后对算法进行了验证,实验结果证明夹角符号序列算法效率高、可靠性好。     

基于人脸角度估计的多观察视频合并

对特定人物进行观察记录时,由于被观察对象处于运动状态,需要通过布置多个观察源来充分采集其行为信息,这导致大量冗余信息的存储,同时不利于后续对视频的检索和对被测对象行为的分析.为此,提出了一种基于人脸角度估计的多观察视频合并方法,通过对多个观察视频的拆分、人脸检测、人脸角度估计和重组,获得单一的包含被观察对象正面行为的观察视频,然后进行存储.通过实验验证了算法的可行性,同时讨论了多观察源采集视频不同步带来的影响.     

基于PSD的高精度太阳敏感器电子学系统设计

针对目前国内太阳观测成像仪器稳像系统的需要,提出了一种基于位置敏感探测器(PSD)的高精度太阳敏感器电子学系统的设计,有针对性地提出了提高灵敏度的设计方案和降低系统噪声的具体措施.该系统噪声水平低于4 nA,在工作范围中心区域具备了0.3"的高分辨能力,可以配合偏摆镜结构组成稳像系统,服务于夸父和SPORT计划等具有高分辨率成像需求的太阳成像仪器.     

聚光系统中太阳位置的鱼眼图像识别

提出一种采用图像目标特征识别法跟踪太阳的方法,对图像进行仿人眼光学滤色镜效果的(H,S,I)变换域处理,凸现图像中高亮度区域;其次对高亮度区域进行鱼眼图像与平面图像的变换;然后根据各区域的轮廓、偏移量、面积等特征动态地识别出图像中的太阳斑区;最后通过鱼眼图像中太阳斑区中心点计算出太阳与视点之间的高度角与方位角.实验结果证明,该方法不仅能准确地实现太阳方位的跟踪,而且在物体遮挡、图像失真等情况下定位依然有效.     

Development of high-accuracy image centroiding algorithm for CMOS-based digital sun sensors

A digital sun sensor calculates the incident sunlight angle using the sunlight image registered on a Complimentary Metal Oxide Semiconductor (CMOS) image sensor. In order to accomplish this, an exact center of the sunlight image has to be determined. Therefore, an accurate estimate of the centroid is the most important factor in digital sun sensor development. The most general method for determining the centroid is the thresholding method, and this method is also the simplest and easy to implement. Another centering algorithm often used is the image filtering method that utilizes image processing. The sun sensor accuracy using these methods, however, is quite susceptible to noise in the detected sunlight intensity. This is especially true in the thresholding method where the accuracy changes according to the threshold level. In this paper, a template method that uses the sunlight image model to determine the centroid of the sunlight image is suggested, and the performance has been compared and analyzed. The template method suggested, unlike the thresholding and image filtering method, has comparatively higher accuracy. In addition, it has the advantage of having consistent level of accuracy regardless of the noise level, which results in a higher reliability.     

位置敏感探测器在转角测量中的应用

简要介绍了位置敏感检测器 (PSD)的基本原理和特点 ,以二维PSD为核心器件 ,设计制作了单镜二维激光扫描器转角测量系统。采用光学滤波和PSD后续信号处理电路相结合的方式 ,有效地消除了杂散光和暗电流的影响。对PSD作了位移标定 ,该系统可实现 30°二维转角测量 ,分辨力为 30″。     

Markerless visual servo control of a servosphere for behavior observation of a variety of wandering animals

ABSTRACT

Servospheres are robotized observation equipments that produce endless fields for behavior observation of wandering animals. This paper first proposes a markerless visual tracking technique for estimation of the position and the heading direction of wandering animals, since existing techniques for servospheres require special markers or do not estimate the heading direction. The proposed markerless visual tracking technique is then integrated with a visual servo controller for a servosphere. The integrated markerless visual servo controller is available for wandering animals whose shapes in the image plane are represented by long bodies and thinner parts than their bodies. This paper demonstrates that the proposed controller is available for ants, crickets, mantises and spiders, while the shapes of their bodies and legs are different from each other.     

天基光学观测低轨多目标跟踪的多模型CPHD滤波方法

低轨多目标跟踪是天基光学系统信息处理需要解决的重要问题之一。提出了一种基于多模型势概率假设密度(CPHD)滤波的跟踪方法,建立了描述低轨目标运动的常轴向力模型和二体力学模型,给出了天基测量模型,将低轨目标的运动模式和运动状态组合成扩展状态,利用CPHD滤波递推扩展状态的验后概率假设密度(PHD)和目标数量的验后概率密度,能够同时得到目标状态和目标数量的估计。仿真结果表明,多模型CPHD滤波对目标数量和目标状态的估计精度相对多模型PHD滤波和单模型CPHD滤波有显著提高。     

A novel technique for the accurate determination of average tilt angle in twisted nematic cells

Measurement of the spatial distribution of light transmitted through an arbitrary twisted nematic structure placed between crossed polarizers enables numerical evaluation of the average tilt angle in twisted nematic cells to be carried out without disturbance to the director configuration due to magnetic or electric fields. The measurement procedure is well suited for batch production testing as well as for research purposes, since no special measuring sample cells have to be prepared. Input data required for the numerical procedure are the twist angle and optical refractive indices of the liquid crystal material. Measurement accuracy of at least ±0.1° has been achieved for tilt bias angles less than 5°.     

Analysis and experimentation of key technologies in service-oriented optical internet

To satisfy diverse bandwidth-intensive applications envisioned in the internet of the future, research on a distributed optical internet, enabling efficient utilization of geographically distributed resources, has become attractive. The deployment of such a network, however, has its own technical challenges, including network architecture, resource management, and high-speed transmission. To address these issues, a service-oriented-architecture-based distributed optical internet architecture is pr...     

LORES: Low resolution shape program for the calculation of small angle scattering profiles for biological macromolecules in solution

A program for determining the low resolution shape of biological macromolecules, based on the optimization of a small angle neutron scattering profile to experimental data, is presented. This program, termed LORES, relies on a Monte Carlo optimization procedure and will allow for multiple scattering length densities of complex structures. It is therefore more versatile than utilizing a form factor approach to produce low resolution structural models. LORES is easy to compile and use, and allows for structural modeling of biological samples in real time. To illustrate the effectiveness and versatility of the program, we present four specific biological examples, Apoferritin (shell model), Ribonuclease S (ellipsoidal model), a 10-mer dsDNA (duplex helix) and a construct of a 10-mer DNA/PNA duplex helix (heterogeneous structure). These examples are taken from protein and nucleic acid SANS studies, of both large and small scale structures. We find, in general, that our program will accurately reproduce the geometric shape of a given macromolecule, when compared with the known crystallographic structures. We also present results to illustrate the lower limit of the experimental resolution which the LORES program is capable of modeling.

Program summary

Title of program:LORESCatalogue identifier: ADVCProgram summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVCProgram obtainable from: CPC Program Library, Queen's University of Belfast, N. IrelandComputer:SGI Origin200, SGI Octane, SGI Linux, Intel Pentium PCOperating systems:UNIX64 6.5 and LINUX 2.4.7Programming language used:CMemory required to execute with typical data:8 MBNo. of lines in distributed program, including test data, etc.:2270No. of bytes in distributed program, including test data, etc.:13 302Distribution format:tar.gzExternal subprograms used:The entire code must be linked with the MATH library