用于光纤围栏入侵告警的频谱分析快速模式识别

相位敏感光时域反射计(Ф-OTDR)在光纤围栏等动态传感领域具有重要的应用,快速、有效地对入侵信号分类识别有着十分重要的意义。基于频谱分析提出了一种称为频谱欧氏距离法(EDFS)的快速模式识别方法。该方法通过短时平移差分和短时能量法对Ф-OTDR的解调信号进行提取,确定待分析数据段;对数据段进行归一化和快速傅里叶变换,获得信号的频谱特征;计算信号频谱与预先生成的模板之间的欧氏距离对入侵信号进行分类、识别。采用三种入侵信号对该方法的有效性和实时性进行了实验验证。结果表明,该模式识别方法可以有效识别扰动信号,识别时间小于传统的动态时域规划模式识别方法耗时的1/10。同时,该方法所需训练样本较少,对环境噪声有一定程度的抑制作用。     

运载火箭一级发动机自动归零技术研究

基于现役某型号运载火箭一级伺服回路的控制方案和原理,提出一种在发射场一级发动机挂齿后进行自动归零的方法.经发射场试验实际验证:一级发动机喷管在实施自动归零措施后可快速回零且不发生偏离,自动归零方案可行有效.     

基于Winsock的IP地址诊断技术

用户对象是PowerBuilder实现Sockets网络通信的关键,基于Winsock的IP地址诊断程序通过定义实例变量和用户对象函数将Winsock封装起来。IP地址诊断通过用户对象使用Winsock函数来实现。即先建立应用程序,将Winsock.pbl加到其中,再建立主窗口w_main,通过listen按钮获得主机名、UL地址及IP地址。     

AlGaAs/GaAs tunnel junctions in a 4-J tandem solar cell

TheⅢ-Ⅴcompound tandem solar cell is a third-generation new style solar cell with ultra-high efficiency. The energy band gaps of the sub-cells in a GaInP/GaAs/InGaAs/Ge 4-J tandem solar cell are 1.8,1.4,1.0 and 0.7 eV,respectively.In order to match the currents between sub-cells,tunnel junctions are used to connect the sub-cells.The characteristics of the tunnel junction,the material used in the tunnel junction,the compensation of the tunnel junction to the overall cell’s characteristics,the tunnel junction’s influence on the current density of sub-cells and the efficiency increase are discussed in the paper.An AlGaAs/GaAs tunnel junction is selected to simulate the cell’s overall characteristics by PC1D,current densities of 16.02,17.12,17.75 and 17.45 mA/cm² are observed,with a V_oc of 3.246 V,the energy conversion efficiency under AM0 is 33.9%.     

Throughput Maximization in Cognitive Radio System with Transmission Probability Scheduling and Traffic Pattern Prediction

In this paper, we propose a novel transmission probability scheduling (TPS) scheme for the opportunistic spectrum access based cognitive radio system (OSA-based CRS), in which the secondary user (SU) optimally schedules its transmission probabilities in the idle period of the primary user (PU), to maximize the throughput of the SU over a single channel when the collision probability perceived by the PU is constrained under a required threshold. Particularly, we first study the maximum achievable throughput of the SU when the proposed TPS scheme is employed under the assumption that the distribution of the PU idle period is known and the spectrum sensing is perfect. When the spectrum sensing at the SU is imperfect, we thoroughly quantify the impact of sensing errors on the SU performance with the proposed TPS scheme. Furthermore, in the situation that the traffic pattern of the PU and its parameters are unknown and the spectrum sensing is imperfect, we propose a predictor based on hidden Markov model (HMM) for the proposed TPS scheme to predict the future PU state. Extensive simulations are conducted and show that the proposed TPS scheme with the HMM-based predictor can achieve a reasonably high SU throughput under the PU collision probability constraint even when the sensing errors are severe.     

投影光刻系统中的掩模硅片相关识别对准技术

分析图像相关识别中的纯相位匹配滤波器的模式识别方法,利用该滤波器的相关识别位图计算算法,及其所具有的相干峰尖锐特性与高度旋转敏感特性,分别求取得光刻套刻过程中,掩模板和硅片基板对准标记的相对平移坐标与旋转坐标的精密量化驱动值。将此算法的实施单元建立在一套成型的大面积投影光刻系统中,使得该系统的对位精度与对位效率显著地提高。     

Charge Transportation and Chirality in Liquid Crystalline Helical Network Phases of Achiral BTBT-Derived Polycatenar Molecules

First examples of multichain (polycatenar) compounds, based on the π-conjugated [1]benzothieno[3,2-b]benzothiophene unit are designed, synthesized, and their soft self-assembly and charge carrier mobility are investigated. These compounds, terminated by the new fan-shaped 2-brominated 3,4,5-trialkoxybenzoate moiety, form bicontinuous cubic liquid crystalline (LC) phases with helical network structure over extremely wide temperature ranges (>200 K), including ambient temperature. Compounds with short chains show an achiral cubic phase with the double network, which upon increasing the chain length, is at first replaced by a tetragonal 3D phase and then by a mirror symmetry is broken triple network cubic phase. In the networks, the capability of bypassing defects provides enhanced charge carrier mobility compared to imperfectly aligned columnar phases, and the charge transportation is non-dispersive, as only rarely observed for LC materials. At the transition to a semicrystalline helical network phase, the conductivity is further enhanced by almost one order of magnitude. In addition, a mirror symmetry broken isotropic liquid phase is formed beside the 3D phases, which upon chain elongation is removed and replaced by a hexagonal columnar LC phase.     

An Optically Pumped Far-Infrared Folded Mirror-Less Cavity

A compact and efficient mirror-less cavity is presented for an optically pumped 192-μm far-infrared laser. With a gold-coated mirror and 30°-inclined anti-reflection coated Ge plate serving as highly reflective mirrors, a folded mirror-less CH₃F cavity is achieved. Maximum energy of 0.72 mJ is obtained with the pump energy of 600 mJ, which gives an energy increment of 75% in comparison with the previous 1.85-m mirror-less system. The beam divergence angle of the FIR radiation from this folded mirror-less cavity is measured to be 14.2 mrad.     

Electrospinning Multilayered Scaffolds Loaded with Melatonin and Fe3O4 Magnetic Nanoparticles for Peripheral Nerve Regeneration

Peripheral nerve injury is a common clinical problem bringing heavy burden to patients, due to its high incidence and unsatisfactory treatment. Nerve guidance conduit (NGC) is a promising scaffold for peripheral nerve repair, and bioactive agents are applied for great functional recovery. Melatonin (MLT) and Fe₃O₄ magnetic nanoparticles (Fe₃O₄‐MNPs) are proven to inhibit oxidative stress, inflammation, and induce nerve regeneration. Herein, a multilayered composite NGC loaded with MLT and Fe₃O₄‐MNPs is designed for sequential and sustainable drug release, creating an appropriate microenvironment for nerve regeneration. The composite scaffold shows sufficient mechanical strength and biocompatibility in vitro, and evidently promotes morphological, functional, and electrophysiological recovery of regenerated sciatic nerves in vivo. This work proves that the multilayered conduits show great prospect in the long‐term nerve defects treatment due to easy manufacture and desired efficacy.     

Improving local minima of columnar competitive model for TSPs

The columnar competitive model (CCM) has been recently proposed to solve the traveling salesman problem. This method performs much better than the original Hopfield network in terms of both the number and the quality of valid solutions. However, the local minima is still an open unsolved issue. This paper studies the performance of the CCM and aims to improve its local minima problem. The contributions of this paper are: 1) it proves by mathematics that the CCM is hardly to escape from local minimum states in general; 2) an alternate CCM is presented based on a modified energy function so as to enhance the capability of the original CCM; 3) a new algorithm is proposed by combining the alternative CCM with the original one, which enables the network to have lower energy level when trapped in local minima, this makes the network to reach the optimal or near-optimal state quickly; 4) Simulations are carried out to illustrate the performance of the proposed method.