系统差及南纬站对GEO多站测距定轨精度的影响分析

在基于多站测距的GEO卫星定轨中,为了提高卫星的定轨精度,通过仿真分析了测距系统差对定轨精度的影响。阐述了GEO卫星多站测距定轨的原理,分析了系统差的误差源及其修正精度,分析表明系统差综合修正误差在2 m左右;定轨仿真分析了系统差及南纬站对GEO卫星定轨精度的影响。实验结果表明,系统差主要影响GEO卫星切向和外法向定轨精度,南纬站的加入对改善外法向定轨精度作用显著。     

利用激光测距卫星实现对测控设备的精度鉴定

测控设备的精度具有重要意义，利用激光测距卫星进行测控设备精度鉴定具有可行性和很大的优越性。首先选择待鉴定的目标，并进行标校；然后选定合适的精确定轨卫星；在轨道预报的基础上，使光学、遥测、雷达等测控设备同时跟踪指定卫星，获得测量数据；通过对卫星精确定轨的模型的应用，获取精确数据；两者对比就可以对测控设备的精度进行准确地鉴定。该方法操作简便，精度高，有着广泛的推广应用前景。     

卫星扩频测控体制研究

介绍了USB微波统一测控系统、连续波测量系统、GPS原理。对中低轨卫星扩频测控采用的测控体制作了相应的论述与设计。提出中低轨卫星测控采用星地上下行信号相干(包括载波相干、伪码相干)方式,使星上应答机发射的下行频率与地面站发射的上行频率同步,消除星地钟差,完成卫星的测速、测距以及遥测遥控任务,并阐述了星地扩频测控设备的组成和工作原理。     

基于多星联合的雷达精度鉴定方法研究

针对雷达数据汇集处理中心评估不同型号雷达测轨数据精度的迫切需求,研究了利用多颗低轨卫星开源精密星历开展精度鉴定的方法。通过分析标校卫星过境规律,探讨了多星联合观测标校方法在雷达精度鉴定中的可行性。系统讨论了标校星位置计算方法,解决了精密星历与测量数据在时间系统、坐标系统、数据率等方面存在的不一致问题,分析了雷达测量数据误差修正方法,有效消除了外界因素对测量误差的影响。在残差统计方面,通过统计雷达单圈次测量误差及多圈次总误差,综合反映雷达测轨精度水平。利用该方法对某型雷达测轨数据进行了误差分析,验证了该雷达测距优于10 m,测角优于360″。结合实际案例,探讨了该方法在雷达精度鉴定、雷达状态常态化监测中的应用价值。     

基于自发自收模式的卫星转发器测轨技术浅析

介绍了基于自发自收模式的卫星转发器测轨技术,在理论上分析了该技术的基本原理,并在此基础上讨论了卫星测轨地面站系统的组成,最后给出了卫星轨道数据精度的评估方法。     

一种同波束多目标测轨的角度修正方法

为解决船载测控设备对同波束内的非主跟踪扩频目标测轨时测角数据偏差大的问题,剖析了现有设备同波束多目标测轨方法的缺陷,提出了一种基于多目标角误差电压的角度修正方法,根据此方法分析了测控过程中获取的外测数据,对实测角度数据进行了修正和定轨反演验证,通过多目标测角信息传输方式的改进实现测角数据的实时修正,有效提高了同波束多目标飞行轨迹测量精度。     

空间碎片精密测角和测距仿真数据定轨性能分析

目前空间碎片精密跟踪数据可以通过光学测角和激光测距两种手段获取。文中旨在通过大量的仿真实验来分析上述两种手段获取的数据对碎片定轨及预报性能的影响,以期根据各自的特点更好地利用稀缺的数据资源。首先利用了2015年1月Starlette和Larets卫星CPF精密预报轨道作为参考轨道,仿真生成基于国内区域内4个观测站精度1的测角数据和精度1 m的测距数据,然后,利用仿真数据生成单站和双站算例并进行定轨,得到完整弧段及部分弧段的测角、测距数据定轨预报结果。结果表明:在上述观测数据精度基础上,测角数据较测距数据在定轨中的表现更加稳定,将完整通过弧段缩短至90 s时,约75%的角度定轨算例的短期(1~2天)预报轨道仍能够满足20精度要求。实验结果同时表明:单站、双站定轨预报误差分布相似。     

GEO卫星测距系统设计

随着卫星测定轨精度的提高,现有测距系统难以满足要求.文中着重介绍了GEO卫星采用三点测距为实现高测距精度的方案,给出了三点测距系统的结构和功能,并分析测距系统模型,以及提高测定轨精度的因素,最后对测距性能进行了分析.     

经纬仪测星法在测量船上的工程化应用研究

移动站缺少稳定的静基座,因此测控精度受到其不同设备间坐标转换的影响。通过分析经纬仪测星法理论和测量船设备组成、信息传输模式,提出将经纬仪测星法工程化应用于测量船上。经过深入的误差分析,其测量误差满足工程应用的需求,可以有效解决海上动态条件下航天测量船执行航天测控任务时因惯导台体不水平度导致的姿态误差以及因无线电设备大盘不水平度导致的测量误差,进一步提高测量船单位定轨能力,有效提升航天器测控精度。     

一种基于先验信息的中高轨卫星遥测任务资源调度方法

中高轨卫星测控需求的特性导致遥测数据接收任务占用了绝大部分设备跟踪时长,但遥测任务的资源调度问题的相比遥控和测轨复杂性更高,使得其资源调度算法的自动化水平一直不高。根据中高轨卫星遥测数据接收任务需求和我国测控站布站情况,设计了一种基于先验信息的中高轨卫星遥测任务资源调度算法。该算法以中高轨卫星遥测任务需求整体满足率最大和算法复杂度最低为设计目标,以人工安排中高轨遥测任务测控工作计划积累的有益经验作为先验信息,赋予中高轨卫星遥测任务可行解优先级使用值。通过实际数据仿真分析,该算法极大缩小了中高轨卫星遥测任务可行解空间规模,有效提高了资源调度效率,资源满足率达到99.7%以上,遥测单收设备使用率超过97.7%,为卫星资源调度算法设计提供了参考。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.