基于MIMU的自适应步态检测算法

行人步态检测精度对个人导航系统至关重要。针对当前行人自主导航系统中常规步态检测算法不能适用于多种运动状态下的步态检测问题,提出了一种基于微惯性测量单元（MIMU）的自适应步态检测算法。该算法首先利用加速度计三轴模值方差、单轴方差差别和波形相位识别4种不同的行走状态,包括前进、快跑、后退和横向行走,然后针对不同的行走状态设置自适应阈值,实现各类运动状态下的自适应步态检测。利用实验室自主研发的MIMU固定在腰部脊椎位置进行实验验证,数据显示,前进行走和快跑步态检测精度可达99%,后退和横向行走步态检测精度可达93%。实验证明,自适应步态检测算法适用于个人导航系统。     

基于可穿戴式MIMU的波峰-双阈值步数检测算法

惯性导航系统中,行人航迹推算(PDR)算法在位置解算中至关重要,其中步数统计准确程度直接影响行人的定位精度。针对传统波峰-阈值检测法存在伪波峰的影响,提出了一种基于可穿戴式微型惯性测量单元(MIMU)的波峰-双阈值步数检测算法,在行走过程中,对窗函数滤波后的合加速度进行波峰检测,并对波峰进行双阈值限定。检测到波峰满足高阈值时计为有效波峰,且相连波峰间出现低阈值时则计步成功,从而降低伪波峰对计步的影响,实现步数的精确检测。实验结果表明,当MIMU分别佩戴在多种位置时,行人多运动模式下计步精度为98%以上。     

一种改进的步态识别方法

行走方向问题已经成为当今步态识别领域极富挑战性的课题.针对该问题,提出考虑到行走方向的步态识别算法,运用了全新的思路计算行走角度(DOW算法),并根据人体运动学模型和行走方向信息提取关键特征,引入了同时考虑到多类支持向量机算法和线性规划方法的lp-mc-sv算法识别,并对实验结果进行了分析.将本文算法应用于实际人体行走图像序列,获得了较为理想的识别率(80%).     

基于惯性传感器的动态步长算法研究

行人步态参数的精确估计是行人自主导航系统和行人健康监测的关键技术之一。针对当前行人自主导航系统中步长估算算法精度低和弱适应性的问题,提出了一种计算行人动态步长算法。首先对行人的步态特征进行分解,利用改进的零速检测确定行人运动状态,采用卡尔曼滤波技术降低惯性传感器中累积误差的影响,再对进行滤波和坐标转换后的加速度进行双重积分,最终得到行人脚尖的运动轨迹。通过采用MTI-700惯性模块设计实验并进行实验验证。结果表明,该文提出的步长算法计算的步长与行人实际步长的误差低于3.0%。与现有的行人动态步长算法相比,该算法首次计算出行人脚尖的运动轨迹,精度较高且适应强,在行人自主导航及行人健康监测领域具有较大的应用价值。     

自适应计步检测算法研究

通过检测人体行走步数,结合步距和行走方位,可推算出具体行走位置,从而在无GPS情况下,达到提高个人惯导位置精度的目的。为提高计步精度,利用加速度信号,首先采用5点平滑滤波,其次搜索自适应时间窗内的极值来求取自适应双阈值,最后检测信号向上穿越中阈值和向下穿越低阈值时刻。并结合动态精度判段停止或行走,从而缩短算法检测时间。实验结果表明,基于自适应时间窗、自适应双阈值和动态精度的步数检测算法能有效提高检测精度。     

低频压电马达的工作机理与动力学研究

通过检测人体行走步数,结合步距和行走方位,可推算出具体行走位置,从而在无GPS情况下,达到提高个人惯导位置精度的目的。为提高计步精度,利用加速度信号,首先采用5点平滑滤波,其次搜索自适应时间窗内的极值来求取自适应双阈值,最后检测信号向上穿越中阈值和向下穿越低阈值时刻。并结合动态精度判段停止或行走,从而缩短算法检测时间。实验结果表明,基于自适应时间窗、自适应双阈值和动态精度的步数检测算法能有效提高检测精度。     

基于加速度信号的走路模式多级分类算法

 研究了一种基于多级分类模型的非特定人走路模式识别算法,实现了对水平行走和上、下楼梯三种运动状态的识别.将装有微型加速度传感器的无线数据采集装置固定于人体后腰部,获取运动时的三维步态加速度信号.采用离散小波变换提取与运动相关频带的时频特征,并结合步频以及垂直方向和前进方向加速度信号之间的互相关性,经过特征融合设计了多级分类识别算法.通过对10个人共360组数据的测试结果表明:在步频范围扩大到1~3Hz时,识别率达到了96.1%,且对测试对象的依赖性小.     

基于步态的身份识别

步态就是个体的行走方式，它作为一种适用于非接触式远距离身份识别的生物特征近来倍受关注。文章提出了一种简单有效的利用行人的步态特征识别身份的算法。对于每个序列而言，行人的重心偏移量首先被用来去除序列中的冗余图像帧；然后，从图像中提取二值化人体轮廓的宽度信息，通过对其进行特征空间变换和规范空间变换来获得可分类的低维步态特征；标准的模式分类技术用于最终的识别。     

基于MEMS传感器的运动轨迹的追踪系统

设计一种基于MEMS惯性传感器的行人运动轨迹的追踪系统。测量方式采用计步器的原理,直接利用加速度传感器来检测记录行人步伐的加速度的变化波形,采用三轴磁力计检测行人的运动方向,同时采用加速度值对方向进行倾角补偿。采用平滑滤波的方法对测量结果滤波,通过微处理器处理原始数据,得到比较准确的行人步数和运动方向。最后通过实验验证系统的有效性和可行性。     

时空结合相机关联自适应特征增强的视频行人再识别算法研究

针对行人姿势、外部遮挡、光照强度和摄像设备等内外部条件变化导致的行人再识别率较低的问题,提出时空特征结合相机关联自适应特征增强-MFA的视频行人再识别算法。本文首先基于视频提取时空梯度方向直方图(HOG3D)特征,基于图像提取表观特征,然后将两者结合作为视频行人目标的特征描述子,从而提高特征描述有效性;距离度量时将特征进行自适应特征增强后再作边际费希尔分析(Marginal Fisher Analysis, MFA),增强共性特征之间的联系,进一步提高距离度量阶段对特征的判别性。基于iLIDS-VID 和PRID 2011两大视频行人数据集讨论加入时空梯度方向直方图特征和相机关联自适应特征增强的算法性能提升,多组实验结果表明,该算法能够充分利用视频中包含的运动信息,得到鲁棒的视频行人再识别匹配模型,提高行人再识别的匹配精度。      

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.     

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.