无源测距快速定位技术

在分析现有单站无源定位方法优缺点的基础上,针对运动平台对固定目标无源定位技术的特点,提出了一种基于无源测距的快速定位方法。通过对其定位原理的深入分析和定位精度的仿真,验证了该方法是一种高精度、快速定位方法,并且具有较强的通用性。这种定位方法为单站无源快速定位技术的工程应用提供了一种新的思路,奠定了很好的理论基础。     

Wirelessly Synchronized One‐Way Ranging Algorithm with Active Mobile Nodes

In this letter, we propose a one‐way ranging algorithm that is based on wireless synchronization with measured timestamps and clock frequency offsets. In our proposed algorithm, an active mobile node initiates a ranging procedure by transmitting a ranging frame, and the anchor nodes report their timestamps for the received ranging frame to a reference anchor node. The synchronization of a pair of nodes is provided with instantaneous time information, and the corresponding difference of distances can be calculated.     

一种快速传输的太赫兹无线个域网MAC协议

针对现有太赫兹无线个域网MAC协议存在信道利用率低的问题,提出一种快速传输的太赫兹无线个域网MAC(Fast Transmission MAC Protocol for THz Wireless Personal Area Network,FTP-MAC)协议,FTP-MAC协议采用多对节点并行传输机制,在信道互不干扰的情况下实现了多对节点在同一时刻内同时传输的功能,通过OPNET仿真工具进行仿真验证。相较于LODMAC协议和TAB-MAC协议,FTP-MAC协议在吞吐量、信道利用率和网络整体的数据传输效率等性能方面都有所提高。     

Multi-digital Still Cameras with CCD

Digital still camera is a completely typical tool for capturing the digital images. With the development of IC technology and optimization-algorithm, the performance of digital still cameras（DSCs） will be more and more powerful in the world. But can we obtain the more and better info using the combined information from the multi-digital still camera？ The answer is yes by some experiments. By using multi-DSC at different angles, the various 3-D informations of the object are obtained.     

一种低仰角雷达射线的准确快速描迹方法

探讨了对流层中雷达射线的准确快速描迹技术。和国内一直沿用积分方程进行对流层射线描迹不同，该文基于射线微分方程进行射线描迹，使用了高阶Runge-Kutta数值微分解法，它可避免积分算法计算效率低、零度仰角附近难以计算等方面的局限。模拟结果和已有研究结果的比较表明，该方法可以获得较为理想的准确结果和计算速度。     

RDX Detection with THz Spectroscopy

Spectroscopic analysis in the Terahertz frequency range, providing characteristic “signatures” for explosive and non-explosive materials, is proposed as an efficient and powerful tool for explosive identification. It is demonstrated that spectral responses of materials can be used as fingerprints that distinguish cyclotrimethylenetrinitramine (RDX) from other materials even with simple detectors and a limited number of available frequencies. Detection is performed using a modified least squares approach and multilayer perceptrons that operate on smoothed reflectance spectra. The performance of the detectors is evaluated through application to spectra of RDX and several common materials. A Receiver Operating Characteristic curve analysis demonstrates that our detectors exhibit the desirable properties of high probability of detection and low probability of false alarm.     

阵列通道不一致性误差快速有源校正算法

针对阵列通道不一致性引起的幅相误差校正问题,基于多级维纳滤波器(MSWF),该文提出幅相误差快速校正的简化的多级维纳滤波器(SMSWF)算法。SMSWF算法利用校正源的方位和波形信息对阵列幅相参数进行估计,无需估计协方差矩阵和进行特征值分解,大大地减小了计算量,且具有与特征分解方法相同的幅相参数估计性能。研究发现,单个信源入射到阵列且信源波形已知时,SMSWF算法获得的信号子空间等价于特征分解法得到的信号子空间,这表明SMSWF算法能够替代特征分解法,从而极大减小基于特征分解法的信号处理方法的计算量。大量计算机仿真和消声水池试验验证了SMSWF算法的优越性能。     

Fast Reversible Phase Change Silicon for Visible Active Photonics

Both amorphous and crystalline silicon are ubiquitous materials for electronics, photonics, and microelectromechanical systems. On‐demand control of Si crystallinity is crucial for device manufacturing and to overcome the limitations of current phase‐change materials (PCM) in active photonics. Fast reversible phase transformation in silicon, however, has never been accomplished due to the notorious challenge of amorphization. It is demonstrated that nanostructured Si can function as a PCM, since it can be reversibly crystallized and amorphized under nanosecond laser irradiation with different pulse energies. Reflection probing on a single nanodisk's phase transformations confirms the distinct mechanisms for crystallization and amorphization. The experimental results show that the relaxation time of undercooled silicon at 950 K is 10 ns. The phase change provides a 20% nonvolatile reflectivity modulation within 100 ns and can be repeated over 400 times. It is shown that such transformations are free of deformation upon solidification. Based on the switchable photonic properties in the visible spectrum, proof‐of‐concept experiments of dielectric color displays and dynamic wavefront control are shown. Therefore, nanostructured silicon is proposed as a chemically stable, deformation free, and complementary metal–oxide‐semiconductor compatible (CMOS) PCM for active photonics at visible wavelengths.     

基于协议的信标快速提取有源实现

针对在强背景或假目标持续干扰的情况下,常规图像处理算法较难实现对信标进行准确快速提取的问题,提出了一种基于握手协议的APT信标快速识别系统,给出了系统的设计原理.提出一种基于图像边缘闭曲线拟合的虚警判据,能对潜在假目标进行准确的识剐判断.实验数据表明:在复杂背景和人工虚警干预情况下,系统能对信标光进行准确定位,具有一定的稳健性.     

IEEE802.11切换中一种快速主动扫频算法

提出了一种IEEE802.11切换过程中的快速主动扫频算法。首先STA从扩展了位置信息的邻居AP图中选择被扫频的AP,然后采用单播方式完成扫频。改进算法减轻了由多余信道扫频、等待时延和信道冲突所产生的时延。仿真分析表明,改进算法确保切换完成,并明显地减小了扫频时延。     

微型实时多目立体视觉机设计与实现

本文给出一种实时计算场景稠密深度图的多目立体视觉机设计与实现方法.立体视觉机使用多个微型摄像机同步获取场景图像,采用图像修正、LoG滤波、多立体图像对匹配和稠密深度图等并行算法,利用FPGA的大规模并行处理能力和各算法间的多级流水线关系,在一片FPGA芯片上实现了立体视觉信息的实时处理.设计的立体视觉机体积小,运行速度快.当图像分辨率为320×240像素,深度搜索范围为64级,深度图精度为8位,时钟频率为60MHz时,恢复稠密深度图的速度大于30帧/秒.     

L型波纹太赫兹喇叭天线

本文提出了一款高增益、低旁瓣的L型波纹太赫兹喇叭天线.该天线工作于太赫兹第一个大气窗口,由波导段、模式变换段和辐射段三部分组成,在模式变换段和辐射段内壁引入波纹结构,利用控制变量法分析L型波纹喇叭天线模式变换段的波纹数目和辐射段每个波长内的周期数目对天线辐射特性的影响.分析结果表明:该波纹喇叭天线在工作频率为320~380 GHz范围内增益均大于21.7 dB,其3 dB主瓣宽度都小于15.2°.该天线满足高增益、低旁瓣的要求,适用于太赫兹通信系统.     

基于频率选择平面的太赫兹波调制模拟

太赫兹波调制器是太赫兹通信的一个重要器件。利用介质折射率影响频率选择平面的透射峰,可以实现对太赫兹波强度透过率的调制。利用有限元法对该结构的调制性能进行模拟分析,在3.12 THz附近50 V电压下,实现了50%的强度调制。并进一步分析了该调制结构的调制机理。     

基于改进自抗扰的快速反射镜控制研究

快速反射镜(Fast Steering Mirror,FSM)是光电跟踪系统中精跟踪的重要组成部件,FSM系统需要满足响应时间快,高精度以及抗干扰等性能要求.提高跟踪精度以及减小响应时间是快反镜系统需要解决的关键问题.本文提出了一种改进非线性状态误差反馈控制律的自抗扰控制器,在传统自抗扰优良控制效果的基础上,进一步改善了系统的动态性能和稳态性能.经过大量仿真研究,与传统自抗扰控制相比,该方法使系统的动态性能提升80％左右,跟踪精度增加了46％左右.     

基于EMD的快速活动轮廓图像分割算法

C-V模型等传统基于区域的几何活动轮廓模型仅将灰度同质作为区域相似性的测度,致使其在分割噪声分布大、灰度复杂的自然及遥感图像时难有较好的分割结果。为此,该文提出基于Earth Movers Distance (EMD)的快速活动轮廓图像分割算法。首先,给出了基于EMD的区域相似性测度,并引入到模型的定义;接着,提出了基于过分割的规则化和快速曲线演化方法,很好地克服了传统模型的冗余轮廓、计算复杂等问题。对合成图像和遥感图像的实验结果证明了算法的有效性。     

一种应用于多通道自适应有源控制的快速算法

主要讨论了应用于多通道有源噪声控制系统的自适应组合逆算法及其性能分析。通过对该算法的理论推导,阐明其整体思路及物理意义,同时通过在同参数条件下与FxLMS算法的计算机仿真比较,得出结论:在多通道有源控制中,组合逆算法有效地降低了算法运算量,适合应用于多通道系统。     

3.3 THz Quantum Cascade Laser Based on a Three GaAs/AlGaAs Quantum-Well Active Module with an Operating Temperature above 120 K

Semiconductors - The design of a terahertz (THz) quantum cascade laser (QCL) with an active module based on three GaAs/Al0.18Ga0.82As quantum wells for high-temperature generation at a frequency of...     

PSO Assisted DD-ESB Beamforming with Robust Capabilities

This paper deals with adaptive array beamforming based on the decision-directed eigenspace-based (DD-ESB) technique with robust capabilities. It has been shown that DD-ESB adaptive beamformer demonstrates the advantages of better output signal-to-interference plus noise ratio performance and less sensitivity to pointing error over conventional ESB beamformers without any specific training bits. In conjugation with particle swam optimization assisted scheme to obtain more correct desired user’s transmitted bits from the output of the ESB, the more correct steering vector of the desired user can be reconstructed for DD-ESB adaptive beamforming in the presence of larger pointing error and relatively low interference-to-noise ratio. Computer simulations are provided to illustrate the effectiveness of the proposed approach.