基于TOA和DOA联合估计的UWB定位方法

对于UWB定位系统而言,利用时间参数估计信号源的位置需要多个参考节点,这样增加了系统的开销。如果参考节点既能估计目标源的时间参数又能估计角度参数,理论上一个参考节点就可以确定目标源的位置。该文提出一种UWB系统TOA(到达时间)和DOA(到达角度)参数联合估计的定位方法,该方法使用矩阵束算法估计出时间参数和角度参数,进而得到目标的相对坐标。该方法通过单个接收机就可以确定目标的位置,减少了定位系统负担。仿真实验证实了该方法估计时延和角度精度较高,而且定位精度能够达到厘米级,是一种简单可行的UWB系统定位方法。     

基于Stackelberg博弈的无线定位网络功率分配方案

针对采用超宽带(UWB)信号进行测距定位的无线协同定位网络,建立目标节点信号发射功率与网络均方位置误差下限的函数关系模型。在目标节点发射总功率受限的情况下,基于Stackelberg模型,结合粒子群算法,对目标节点的发射功率进行优化分配。仿真表明,提出的功率优化分配方案相比功率平均分配方案,使网络均方位置误差下限降低了3%,实现网络定位精确度的提高。     

基于捷联惯导系统补偿的UWB的室内定位方法研究

根据超宽带定位系统在室内定位应用,分析UWB信号丢失或被遮挡时类型,将基于捷联惯导系统的惯性器件IMU的加速度计在三个方向的增量信息作为UWB丢失信号的补偿,从而改善UWB在室内定位中的精度。通过仿真实验测得在UWB信号丢失10s时间,该设计可以将原来的位置误差缩小到2m以内。针对设计的定位模型,利用实验室设备搭建该原理样机,通过半物理仿真试验,证明基于捷联惯导系统的UWB室内定位系统在水平面X轴与Y轴误差基本保持在0.5m范围内。     

基于超宽带信号和地面数字电视信号的无线联合定位系统

针对基于地面数字电视信号定位系统定位范围广而室内定位精度不高的问题,将具有高抗多径效应和高定位精度的UWB技术应用到数字电视接收机中,提出基于超宽带信号和地面数字电视信号的联合定位系统方案,在利用地面数字电视信号进行户外定位的同时,通过数字电视接收机的中转作用,在室内实现用超宽带信号进行定位,使户外室内高精度的定位成为了可能。     

基于超宽带信号和地面数字电视信号的无线联合定位系统

针对基于地面数字电视信号定位系统定位范围广而室内定位精度不高的问题,将具有高抗多径效应和高定位精度的UWB技术应用到数字电视接收机中,提出基于超宽带信号和地面数字电视信号的联合定位系统方案,在利用地面数字电视信号进行户外定位的同时,通过数字电视接收机的中转作用,在室内实现用超宽带信号进行定位,使户外室内高精度的定位成为了可能.     

基于自适应UKF的UWB/PDR行人定位系统

UWB(Ultra-Wide Band)无线通讯技术在室内导航定位领域获得了广泛的应用，然而基于UWB的行人定位系统在复杂室内环境下的稳定性不佳，导致定位误差增大。为了解决这一问题，文中提出了一种基于自适应无迹卡尔曼滤波(Unscented Kalman Filter, UKF)的UWB/PDR(Pedestrian Dead Reckoning)行人定位系统。该系统利用无迹卡尔曼滤波算法将PDR模型与UWB的定位信息进行融合，以得到最优位置估计，随后利用UWB定位与PDR系统所获得的步长差概率密度函数来计算定位点的非视距评估概率，并将评估结果作用于系统的自适应噪声调整，以此提高系统对环境的适应性。实验验证结果表明，该系统可有效降低复杂环境下定位误差，提高行人定位结果的精度和稳定性，平均定位精度达到10 cm以内。     

多照明区域协作的室内可见光定位

考虑室内存在障碍物遮挡及背景光和反射光干扰 较强的实际定位场景,提出了一种基于多照明区域 协作的LED可见光室内定位方法。本文方法引入多照明区域联合定位思想,利用分布于室内 不同区域的LED 发出的参考信号估计定位节点到各LED的信号传输时间差,构造协作定位距离估计目标函数 ,并通过非线 性最小二乘(NLLS)算法获得定位目标的位置估计。将提出的定位算法在10m×3m的空间区域中进行定位仿 真,在5W LED照明、双区域协作条件下,获得了平均定位误差7.41 cm的定位精度。结果表明:提出的协 作算法不仅提高了室内定位精度和系统应用的普适性及鲁棒性,而且有效地解决了室内可见 光定位存在的遮挡效应;此外,对动态定位追踪也有一定的效果。     

单基站UWB定位距离的获得及处理方法

相比于其他定位系统通常至少需要3个参考基站的开销来说,UWB单基站定位只需要一个基站,系统配置简单,可以很快的被应用和发展。为了提高UWB单基站定位系统中对于距离的测定精度,提出了一种应用于该系统的通信定位协议。该定位通信协议用于更加精确地进行基站与标签之间的时钟同步。同时将最大概率数据处理方法应用于距离数据处理。通过对UWB单基站定位系统的整体仿真得到的距离测量误差小于5 cm。该仿真结果说明了此种定位协议和最大概率数据处理方法可以应用于室内高精度无线定位。     

基于信号分布混合假设检验的Wi-Fi室内定位方法

Wi-Fi室内定位技术是目前移动计算领域的研究热点之一,而传统位置指纹定位方法没有考虑复杂室内环境下Wi-Fi信号分布的多样性问题,从而导致Wi-Fi室内定位系统的鲁棒性较差。为了解决这一问题,该文提出一种基于信号分布混合假设检验的Wi-Fi室内定位方法。首先根据Jarque-Bera(JB)检验结果对各个参考点处的Wi-Fi信号分布进行正态性评价;然后针对不同Wi-Fi信号分布特性,利用混合Mann-Whitney U检验/T检验方法构造匹配参考点集合,以实现对目标的区域定位;最后通过计算定位区域中匹配参考点的K近邻(K-Nearest Neighbor, KNN),完成对目标的位置坐标估计。实验结果表明,所提方法相比于传统Wi-Fi室内定位方法具有更高的定位精度和更强的系统鲁棒性。     

全自动驾驶车辆基地库内精确定位技术研究

针对全自动驾驶车辆基地库内工作人员的高精度定位需求，设计了基于RFID和超宽带(UWB)技术的适用于室内的高精度定位系统。RFID记录定位开始和结束时间，获取目标相关信息；UWB对目标位置进行实时准确地监控。两种技术相结合实现对检修人员位置的实时跟踪，获取作业时间数据以及作业人员的其他相关信息。当UWB定位出现误差，通过对RFID标签进行读取，实现人员位置重置。测试结果表明，该系统在全自动驾驶车辆基地停车列检库内具有精确的定位性能，既可以对库内目标进行追踪定位，又能为目标提供定位数据校正。     

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.     

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.     

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.