对流层散射双向时间比对中对流层斜延迟实时估计

对流层斜延迟是对流层散射双向时间比对中一个重要误差源,该文提出一种对流层散射双向时间比对中对流层斜延迟实时估计方法。通过GPT2w模型计算测站气象数据,克服对流层斜延迟估计中对实时气象数据的依赖。针对Hopfield模型中固定的对流层散射顶层高,利用几何方法计算动态对流层散射顶层高,以解决对流层散射双向比对的实际应用问题。选取日本地区3个测站,两两进行比对,在验证Hopfield模型精度后,计算3组比对站在不同入射角和不同时间的对流层斜延迟。计算结果表明,对流层散射双向时间比对中对流层斜延迟呈现出随比对距离增大而增大,随入射角增大而减小的特性,并且四季变化特性也比较明显。3个比对站的对流层散射斜延迟10~35 m之间,经比对抵消90%后的时间延迟为3.5~11.8 ns。     

基于对流层散射信道的时间同步技术研究

针对对流层散射时间同步系统高损耗、信道延迟估计难度大以及多径效应明显等问题,在介绍分布式系统时间同步方案的基础上,结合对流层散射通信传输距离远、抗干扰能力强以及越障能力强的优点,对基于对流层散射通信的分布式时间同步系统进行了简要介绍,分析了主要误差来源,给出了分集接收结合双向时间比对的时间同步解决方案;对接收电平、相干带宽等信道参数的变化进行了仿真分析,结果表明,该解决方案可有效提高基于对流层散射通信的分布式时间同步系统的时间同步精度,具有可行性。     

基于卫星双向法的时间比对系统构建与分析

为了实现高精度时间同步,采用了卫星双向法,对时间比对系统进行了构建,并对影响比对系统不确定度的因素进行了分析。卫星双向法即两个台站同步发送和接收时间信号,可消除传递路径引起的误差,如：卫星位置引起的误差、电离层和对流层修正误差、卫星转发器误差。分析表明：在所有不确定度影响因素中,发射与接收设备时延的不稳定性是最大影响分量,系统对时精度可控制在4ns以内。系统的构建为高精度时间同步提供了可操作的方法。     

基于状态协方差阵加权的GPS PPP应用研究

精密钟差以及天顶对流层时延是GPS PPP解算的重要参数.本文通过在PPP数据处理过程中加入基于更新迭代的状态协方差阵作为取权因子，分别在高精度时间比对和天顶对流层时延方面利用单向滤波以及双向加权滤波对PPP解算的钟差及对流层时延进行估计与分析.结果表明，在零基线比对方面，经加权估计的钟差标准偏差优于单向结果，提高在30%以上；在时间比对方面，利用加权估计的钟差与国际权度局发布的钟差在频率稳定度上水平相当；最后，在天顶对流层时延估计方面，两种方法相对于IGS分析中心公布的天顶对流层时延的残差均方根误差中，加权估计的天顶对流层时延也略有提高.     

低仰角对流层散射斜延迟实时估计方法

针对缺乏气象数据情况下低仰角对流层散射斜延迟的实时估计问题,该文提出一种基于射线描迹的对流层斜延迟估计方法。该算法利用UNB3m模型获取大气气象参数,建立了对流层大气折射率剖面模型,克服了气象数据对射线描迹法中折射率计算的限制。选取亚洲地区8个国际GNSS服务(International GNSS Service, IGS)测站2012年的实测气象数据,计算对流层大气折射率剖面,验证了对流层延迟模型的精度小于25 mm;选取基线距离适宜的3个测站分成3组散射通信比对站,利用射线描迹法计算了其在0--5 入射角下全年的斜延迟,计算结果表明：3组比对站最大单向传输斜延迟为22.38-- 48.37 m;在进行双向时间比对相互抵消95%的情况下,时间延迟为3.73 --8.07 ns。     

低仰角下对流层散射斜延迟估计方法

对流层斜延迟是对流层散射双向时间比对系统的主要误差来源,目前尚未有对系统中对流层斜延迟进行精确估计的模型。为精确估计斜延迟,引入电磁波射线描迹法,并利用Hopfield天顶延迟模型中折射率计算方案改进描迹法,以克服该方法对探空数据的依赖。首先,根据北纬35 ~37范围内的3个测站2010~2012年的实测气象数据和天顶延迟数据,验证 模型精度范围小于35 mm;然后,将3个测站按相互基线距离的不同分为3组比对站,利用改进后的模型结合2012年的气象数据,计算了在0~5入射角下,一年的斜延迟,并得出最大斜延迟对应的年积日和入射角。计算结果表明,3组比对站的最大单向斜延迟为24.94~45.37 m。在双向比对抵消90%的情况下,时间延迟为3.1~5.7 ns;相互抵消95%时,时间延迟为1.5~2.9 ns。     

岸船卫星双向时间比对及其误差分析

详细介绍了岸船卫星双向时间比对原理,从原理得出,影响卫星双向时间比对精度的因素主要有2项:TA和TB的测量精度和双向比对链当中的不一致性。分析各误差源对岸船时间比对精度的影响,表明主要误差源为两站设备时延,它是由岸船通信系统时钟和时统时钟不同源引起的采样误差,误差最大达到0.104 ms;而测量误差和由于卫星和地面站运动引起的误差较小,一般不超过ns级。     

车载卫星双向时间同步系统研究

卫星双向时间频率传递技术是高精度时间频率远程比对的基本手段。对设备时延进行校准是获得高精度时间比对的关键。设计了车载卫星双向时间同步系统,描述了系统设备组成、工作原理及各设备的功能特点,并对关键技术的实现进行了分析。设计并完成了同源零基线验证实验。实验结果表明,车载卫星双向时间同步系统时延不确定度在0.4 ns之内,可以完成对卫星双向时间比对链路设备时延高精度的校准。     

基于伪码测距的光纤双向时间比对技术

针对分布式雷达组网等对高精度时间同步的需求,在基于伪码测距的卫星双向时间比对系统基础上,利用光纤双向传输链路替代无线射频传输链路,开展基于伪码测距的光纤双向时间比对技术验证试验,采用单纤双向双波长的光信号传输体制实现了高精度光纤双向时间比对.试验结果表明,在105 km光纤链路上,光纤链路受环境变化引起的时延波动几乎被...     

远距离高精度光纤双向时间比对方法研究

针对光纤传输链路因受光信号衰减、温度变化和振动等因素引起的光学相位起伏,影响时间比对精度的问题,研究了基于双向伪码测距原理的光纤双向时间比对方法,并搭建模型系统进行了实验验证。结果表明,通过单光纤双向双波长的传输方案,在65 km光纤链路上,抵消了往返链路传输时延的不对称性,使时间比对精度可达108 ps。温度变化引起光纤折射率变化是导致时延波动的主要因素,对温度变化与光纤时延的关系进行了分析和仿真,通过温度试验验证了光纤时延随温度变化的温度漂移系数与理论值相符。     

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.     

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.     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

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.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks