Modeling of prosthetic limb rotation control by sensing rotation of residual arm bone

We proposed a new approach to improve the control of prosthetic arm rotation in amputees. Arm rotation is sensed by implanting a small permanent magnet into the distal end of the residual bone, which produces a magnetic field. The position of the bone rotation can be derived from magnetic field distribution detected with magnetic sensors on the arm surface, and then conveyed to the prosthesis controller to manipulate the rotation of the prosthesis. Proprioception remains intact for residual limb skeletal structures; thus, this control system should be natural and easy-to-use. In this study, simulations have been conducted in an upper arm model to assess the feasibility and performance of sensing the voluntary rotation of residual humerus with an implanted magnet. A sensitivity analysis of the magnet size and arm size was presented. The influence of relative position of the magnet to the magnetic sensors, orientation of the magnet relative to the limb axis, and displacement of the magnetic sensors on the magnetic field was evaluated. The performance of shielding external magnetostatic interference was also investigated. The simulation results suggest that the direction and angle of rotation of residual humerus could be obtained by decoding the magnetic field signals with magnetic sensors built into a prosthetic socket. This pilot study provides important guidelines for developing a practical interface between the residual bone rotation and the prosthesis for control of prosthetic rotation.      

Alternative interpretation of rotation rate sensing by ring laser

This paper deals with the laser rotation rate sensor, sometimes also referred to as laser gyroscope, which was most extensively investigated by Macek and co-workers at Sperry Gyroscope. The function of rotation sensing is first discussed for a ring resonator of circular shape. It is seen that in that case the standing wave electromagnetic energy distribution remains stationary while the cavity structure with an attached detector is rotated so that the detector samples standing waves. Thus, rotation sensing is linked with the fact that Maxwell's equations are valid for inertial reference frames or equivalently, with the inertial nature of electromagnetic radiation. The concept of inertia is then used to derive the ring laser equation for arbitrary ring shape. It is hoped that these viewpoints offer a more elementary understanding of rotation sensing through ring lasers than other available derivations.     

基于多点耦合内切的光纤谐振环慢光系统转动传感理论

为满足惯性制导对高精度、高稳定度陀螺仪的需求,进行了对基于高色散谐振环结构的光纤陀螺原理研究.在一些高色散耦合谐振环结构中,其色散性质使其系统传递函数对相位微扰十分敏感,可以对萨格纳克相移起到放大作用,从而大大提高传感灵敏度.理论与仿真研究结果表明:多点耦合内切谐振环慢光结构系统能够同时满足实现高灵敏度转动传感所要求的“方向性条件”和“高群折射率(慢光)”两个基本条件,且具有进一步使群折射率比传统结构高出几个数量级的潜力.同时,由于该结构系统可使用定向耦合器来方便搭建,具有用来制作低成本、高灵敏度的光纤陀螺的潜力.     

Optical remote sensing of the earth

Optical remote sensing of the earth from aircraft and from orbit has made unique contributions to understanding the dynamics of the atmosphere, oceans, and the vegetation cover of the land, as well as provided new perspectives in the study of the solid earth. This paper encompasses optical remote sensing of the earth's surface in the region of 0.4 to 15 µm and is divided into four areas: principles, applications to science disciplines, recent sensor history, and new technology developments. The latter developments promise to revolutionize the methods used and the types of problems addressed with remote sensing techniques.     

Optical remote sensing of aircraft emissions with the K300

The K300 double pendulum interferometer, a compact high-resolution Fourier transform spectrometer designed for outdoor optical remote sensing in the infrared spectral region, is described. The remote diagnostic of hot aircraft engine emissions is a very interesting application of the infrared spectroscopy. First results of such measurements performed with the Kayser-Threde double pendulum interferometer K300 at the DLR airport, Oberpfaffenhofen, on 15 January 1992, are discussed     

光纤激光器加速光纤传感应用

光纤传感取代电传感已呈大势所趋。目前市场上的光纤传感绝大部分都是基于光波分复用(OWDM)的准分布式传感原理以及尚处于科研阶段的时域分布式(OTDR)光纤传感技术；两者均受制于各自的缺陷，离大规模市场应用尚待时日，尤其是在更高要求的传感领域更是无法实现。本文所介绍的光纤传感技术起源于激光雷达的调频连续波(FMCW)原理，采用相干探测进行检测，利用光纤本身进行直接传感，完全可以构建低成本的分布式传感网络，完成超远距离、超高精度和超低噪声的实时监控，可广泛用于国防、石油勘探和安保等各个传感领域。     

基于城市GCP模板的遥感图像几何校正研究

提出了一种自动寻找地面控制点进行遥感图像几何校正和配准定位的方法。分析遥感图像产生几何畸变的原因,介绍几何校正的原理和方法。由于中国地区大城市分布具有确定的几何关系,故可以将城市分布图作为模板自动地在待校正图像上匹配上相应的城市地面控制点。进而利用已匹配的GCP对遥感图像进行校正和定位。仿真结果表明,该算法不需要人为寻找GCP,运行速度快,结果令人满意。     

基于城市GCP模板的遥感图像几何校正研究

提出了一种自动寻找地面控制点进行遥感图像几何校正和配准定位的方法。分析遥感图像产生几何畸变的原因,介绍几何校正的原理和方法。由于中国地区大城市分布具有确定的几何关系,故可以将城市分布图作为模板自动地在待校正图像上匹配上相应的城市地面控制点。进而利用已匹配的GCP对遥感图像进行校正和定位。仿真结果表明,该算法不需要人为寻找GCP,运行速度快,结果令人满意。     

A graphical method for determining the in-plane rotation angle in geometric calibration of circular cone-beam CT systems

It is well known that seven parameters completely describe a circular cone-beam geometry in either flat-panel X-ray computed tomography (CT) or single pinhole SPECT imaging. This paper considers the problem of determining one of the seven parameters only, the detector in-plane rotation or twist angle η. We describe a graphical procedure that can determine η independently of all other six parameters from a geometric calibration scan of point objects. Our method is exact in the ideal noise-free case and is general in that the other two out-of-plane detector rotation angles θ and φ can be nonzero. The calibration scan typically needs at least two point objects and an even number of projection views over a full 360° data acquisition. Under certain conditions, projection data truncation or a short scan acquisition of 180° + fan angle can be accommodated without affecting the accuracy of the calibration result. The graphical method is equally applicable to rotational multipinhole SPECT geometry. In this case, the final result is averaged from the individual estimates considering each pinhole separately. We use computer simulations and a multipinhole SPECT experiment to demonstrate the accuracy and precision of the proposed method.     

Theory of magnetostatic waves in moving ferrite films andapplications to rotation rate sensing

A first-order field theory for electromagnetic waves in moving ferrites and ferrite thin films is presented. The dominant effect of the motion is found to be the Doppler-shifted frequency observed in the moving frame. This gives rise to an anomalously large shift in wavenumber, due to the dispersive nature of the ferrite medium. Because of the large effect, it is suggested that a moving-medium experiment using magnetostatic waves could be used to distinguish between various competing forms for the dispersion term in the Fresnel-Fizeau coefficient. The results of the field theory are discussed with relation to relative and absolute rotation rate sensing. The author describes how magnetostatic waves could be used to measure relative rotation rates if confined to propagate around the perimeter of a rotating disk. Since the phase shift would be established in the time required to propagate around the disk, the response time could be significantly shorter than conventional tachometers. An experiment with counterpropagating magnetostatic waves is suggested to clarify the effect of a magnetic medium on the magnitude of the Sagnac effect     

Determination of the minimum sampling frequency in bandpass sampling by geometric approach and geometric programming

This paper presents a simple and fast approach to find a minimum sampling frequency for multi-band signals. Instead of neighbor and boundary conditions, constraints on the sampling frequency were derived by using the geometric approach to the bandpass sampling theorem. Reformulation of the constraints on the minimum sampling frequency enabled to represent the problem as an optimization problem which was structured by the geometric programming and mixed-integer nonlinear programming methods. The convex optimization problem was then solved by the proposed algorithm applying interior point approach in the line search framework. It was demonstrated that this unified structure directly linked the geometric approach of the bandpass sampling theorem to the optimization problem. The proposed method was verified through numerical simulations in terms of the minimum sampling frequency and the computational efficiency. Results illustrated the feasibility of the geometric approach and the proposed algorithm in the determination of the minimum sampling frequency by providing the savings in the number of iterations and the decrease in the valid minimum sampling frequency.     

光纤中5阶非线性效应对光脉冲传输的影响

为了研究5阶非线性效应对光脉冲在光纤中传输的影响,采用分步傅里叶算法数值求解了含5阶非线性项的扩展非线性薛定谔方程,并进行了理论分析和数值模拟。计算结果显示,负的5阶非线性效应使光脉冲峰值减小,脉冲展宽,正的5阶非线性效应使峰值增大,脉冲被压缩。较小的5阶非线性效应产生较小的调制不稳定性,因而光脉冲能保持基本的形状,忽略光纤的损耗时,光脉冲保持绝热传输。对正的5阶非线性效应,适当小的损耗可以减缓调制是不稳定性。结果表明,在5阶非线性系数固定的情况下,初始入射脉冲的峰值会显著地增加5阶非线性项的贡献。     

下视景象几何畸变的余辉仿真

基于分析因俯仰角、滚转角、偏航角等无人机姿态角变化对下视景象余辉处理图产生的影响．在构建下视景象成像几何畸变数学模型的基础上,本文阐述了一种下视景像姿态畸变的余辉处理的模拟仿真方法,以获得规律性变化的余辉线段。通过对随机亮点图进行不同姿态角的余辉仿真,得到余辉仿真图。仿真实验结果验证了该方法的正确性,不同无人机姿态的余辉仿真得到特征各异的余辉图。     

Optical,electrical and sensing properties of In2O3 nanoparticles

In this work, various techniques such as differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible-near infrared (UV-vis-NIR), photoluminescence (PL), >as well as electrical and sensor techniques have been used for the characterization of indium oxide (In₂O₃₎ nanoparticles. Here, we also provide insight regarding the optical and electrical characteristics of In₂O₃ nanostructures. The impact of highly sensitive and fast responding gas sensors using In₂O₃ nanostructures is also discussed. It is found that the as-prepared In₂O₃ powder is a pure single phase and is stable up to 800 °C. The size of the particles is in the range of 12 nm as determined by transmission electron microscopy (TEM). The band gap was found to vary linearly with the annealing temperature. A good sensitivity up to 400 ppm was obtained for ethanol and a mechanism is proposed.     

Remote sensing of the earth by microwaves

Extant techniques for remotely sensing the earth with instruments operating at microwave frequencies are surveyed. Microwave sensors can provide day-night operation and almost an all-weather capability due to higher transmission through clouds at microwave than at visible or infrared wavelengths. Passive (radiometers), active (radars, altimeters, and scatterometers), and composite (passive-active) microwave sensors are in use or planned for such diverse applications as measuring ocean surface dynamics, Ocean salinity, soft moisture content, atmospheric temperature and atmospheric constituents; detecting sea ice, oil slicks, and storm cells; and identifying agricultural crops. These measurements have been taken with sensors located in towers, aircraft, and most recently satellites.     

The effect of electron beam geometric deformation errors on the small-signal characteristic of ECRM

In this paper is studied the effect of electron beam geometric deformation errors on the small — signal characteristics of the TE _mn ^o mode Electron Cyclotron Resonance Maser (ECRM), based on the elliptically cross—sectional e—beam deformation model. As an example, the effect of small geometric deformation errors on the TE ₀₁ ^o mode fundamental ECRM coupling coefficient is quantitatively shown.     

Optical Kerr effect studies of the dynamics of confined water

Time resolved optical Kerr effect measurements have been used to determine the orientational dynamics of water in the pores of ZrO₂ nanostructured films. We demonstrate that local heating effects can safely be ignored and present our results which are manifestly incompatible with the existence of a bulk-like population of water molecules in the core of the pores.     

聚类与几何特征相结合的遥感图像多类人造目标检测算法

针对高分辨率光学遥感图像中人造目标的检测问 题,对传统的相位编组直线段提取算法和k-means 聚类算法了改进,提出了一种k-means聚类和几何特征 相结合的检测方法。根据自然物体和 人造目标在几何外形上表现出的不同特性,首先运用改进的相位编组算法对图像进行快速的 直线段提取; 然后以获取的直线段中心点为处理对象,运用k-means聚类算法 对提取的直线段进行密度聚类;最后,根 据每个类中的直线段数目和构成的几何基元情况,进行人造目标的判定。实验结果表明,本 文算法对遥感 图像中的房屋、汽车、船舰和飞机跑道等多类人造目标可达到90%以 上的检测精度,并具有较高的检测速度,对于一幅512pixel ×512pixel的图像,整个检测过程在100ms 以内。     

纤端光场分布的计算机处理

本文引用文献［７］提出的多参数纤端光场场强分布表达式作为目标函数，结合实验中得到的实测数据，利用数据处理方法中的最小二乘拟合法的原理，采用三维极值的单形调优方法，给出调合参数的数值解，得到能准确反映实测数据的纤端光场场强分布表达式。并比较实验数据与拟会结果，最后给出纤端光场场强分布的三维图形。