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.     

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.     

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.     

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。     

Electroporation-Induced Cell Modifications Detected with THz Time-Domain Spectroscopy

Electroporation (electropermeabilization) increases the electrical conductivity of biological cell membranes and lowers transport barriers for normally impermeant materials. Molecular simulations suggest that electroporation begins with the reorganization of water and lipid head group dipoles in the phospholipid bilayer interface, driven by an externally applied electric field, and the evolution of the resulting defects into water-filled, lipid pores. The interior of the electroporated membrane thus contains water, which should provide a signature for detection of the electropermeabilized state. In this feasibility study, we use THz time-domain spectroscopy, a powerful tool for investigating biomolecular systems and their interactions with water, to detect electroporation in human cells subjected to permeabilizing pulsed electric fields (PEFs). The time-domain response of electroporated human monocytes was acquired with a commercial THz, time-domain spectrometer. For each sample, frequency spectra were calculated, and the absorption coefficient and refractive index were extracted in the frequency range between 0.2 and 1.5 THz. This analysis reveals a higher absorption of THz radiation by PEF-exposed cells, with respect to sham-exposed ones, consistent with the intrusion of water into the cell through the permeabilized membrane that is presumed to be associated with electroporation.     

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...     

THz interconnect with low-loss and low-group velocity dispersion

We report the demonstration of a physically flexible, practicable THz interconnect with minimal pulse distortion and loss. The interconnect is a parallel-plate waveguide, with the TEM mode excited, constructed of two thin copper strips. The incoming 0.22 ps THz pulse broadens to 0.39 ps after propagating 250 mm in the waveguide and is also attenuated by a factor of ten. We show that this attenuation is mainly due to the finite conductivity of copper with some additional loss caused by the beam spread in the unguided dimension. The pulse broadening is due to the frequency-dependent loss since the group velocity dispersion is negligible     

一种可用于T-DMB的快速调谐RC有源低通滤波器

设计了一种可用于T-DMB射频接收机的快速调谐RC有源低通滤波器,采用级联方法实现,并使用数字逻辑控制的电容阵列补偿了因工艺及工作条件变化而变化的元器件参数.基于SMIC 0.18μm、1.8V CMOS混合信号工艺,实现了七阶切比雪夫RC有源低通滤波器的设计,且其在RC时间常数±30%的变化情况下获得极小的截止频率(800 kHz)误差,并获得较快的调谐时间和高线性.调谐时间取决于数字逻辑控制的位数和比对时钟周期.     

结合温度补偿的超声波测距系统设计

本设计实现了一种以AT89C2051单片机为核心的超声波测距系统,它具有低成本,高精度,微型化数字显示的特点.为提高测量精度,在测量时使用了DS18B20温度传感器对系统进行有效的温度补偿.经实验证明,本系统电路设计合理、工作稳定、检测速度快、测量简单、易于做到实时控制.     

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.     

Asymmetric Y-branch tunable semiconductor laser with 1.0 THz tuningrange

The tuning range of the traditional tunable lasers using distributed Bragg reflection is limited by the small refractive index change that can be induced in semiconductors. The authors report the design, fabrication, and characteristics of a novel asymmetric Y-branch (AYB) tunable laser. By geometrically leveraging the index change in these laser structures, they demonstrate, using a single current control, a discrete tuning range as large as 1.0 THz, access to 24 frequency channels, and tuning rates in excess of 100 GHz/mA. AYB lasers appear promising for applications requiring wide tuning range, fast electronic frequency access, and simple low current control     

Investigation of aqueous acetone solution with THz pulse spectroscopy

The absorption spectra from 0.2 to 1.7 THz of five water-acetone mixtures,whose concentrations are 0％,25％,50％,75％,and 100％,has been investigated by THz time-domain spectroscopy (THz-TDS).The result ind...     

Low threshold THz QC lasers with thin core regions

It is demonstrated that the active region thickness of THz quantum cascade lasers can be reduced by a factor of 2 without effects on the threshold current density and maximum operating temperature of the laser. Pulsed and continuous-wave operation, with a low threshold J_th= 71 A/cm², are obtained for a 5.86 mum-thick THz QC laser. The emission is peaked at lambdasime115 mum and the waveguide resonator is based on a metal-metal geometry     

Epipolar Geometry of Line Cameras Moving with Constant Velocity and Attitude

Image resampling according to epipolar geometry is an important prerequisite for a variety of photogrammetric tasks. Established procedures for resampling frame images according to epipolar geometry are not suitable for scenes captured by line cameras. In this paper, the mathematical model describing epipolar lines in scenes captured by line cameras moving with constant velocity and attitude is established and analyzed. The choice of this trajectory is motivated by the fact that many line cameras can be assumed to follow such a flight path during the short duration of a scene capture (especially when considering space‐borne imaging platforms). Experimental results from synthetic along‐track and across‐track stereo‐scenes are presented. For these scenes, the deviations of the resulting epipolar lines from straightness, as the camera's angular field of view decreases, are quantified and presented.