远程火箭末敏弹弹道特性仿真

为研究远程火箭末敏弹弹道特性,应用弹道理论和控制理论,建立了远程火箭末敏弹母弹弹道方程;引入多体系统动力学理论,分析了末敏弹系统伞、伞盘、弹等刚体间的力学关系,考虑了系统的连接方式和约束,分析了伞绳弹性,建立了末敏弹在减速运动和稳态扫描段的完整运动模型.编制了远程火箭末敏弹弹道仿真软件,进行了末敏弹全弹道数字仿真,并得到了部分试验验证,分析了末敏弹弹道特性.为远程火箭末敏弹射击精度仿真和减少精度试验用弹量奠定了基础.     

钝黑-5炸药中硬脂酸质量分数对燃烧转爆轰的影响

为研究炸药中硬脂酸质量分数对燃烧转爆轰的影响,设计了一种传爆装置,在不同温度下对含有不同质量分数硬脂酸的钝黑-5炸药进行传爆试验,收集试验数据并进行分析。试验结果表明:随着温度的降低,低温下钝黑-5炸药燃烧转爆轰后传爆可靠性变差。当钝黑-5炸药中硬脂酸质量分数在1.0%～1.2%时,传爆装置能够可靠传爆; 当硬脂酸质量分数大于1.2%时,其燃烧转爆轰后的输出威力随着硬脂酸质量分数的增加而降低,不能进行有效传爆。     

A 2.4GHz Low Power ASK Transmitter for Wireless Capsule Endoscope Applications

提出了一种应用于无线内窥镜系统的2.4GHz低功耗ASK发射机.为了获得高的数据传输速率,采用了基于混频器的直接上变换发射机结构.为了节省功耗,提出了一种基于电流复用技术的伪差分堆栈结构的A类功放.低功耗发射机由两部分组成:基于恒幅度锁相环(PLL)的20MHz的ASK基带调制器和直接上变换的射频电路.该设计已经采用TSMC 0.25μm CMOS工艺实现并进行了验证.测试结果表明,发射数据速率为1Mbps时,发射机的输出功率为-23.217dBm.采用单2.5V的电源供电下,低功耗发射机消耗的电流约为3.17mA.     

基于MATLAB及FPGA的高速FIR滤波器的设计

FIR滤波器是一种被广泛应用的基本的数字信号处理部件。现提出采用MATLAB的窗函数方法设计并在附上实现高速FIR滤波器的一种新的方案。这种结构采用流水线技术，通过对高速乘法器的合理分割并组合Wallace加法树阵列构成，可以方便地调整滤波器的阶数和系数，适合不同场合的应用。通过编程调试结果表明，该设计是可靠的，可作为高速数字滤波器设计的较好方案。     

Analyzing Semicircular Groove Guide with the Conformal Mapping Technique

Semicircular groove guide is a kind of waveguide for millimeter waves. In this paper, a conformal mapping technique is used to analyze it. Several semicircular groove guides are calculated with the method. It is shown that their cutoff wavelength calculated by the method are very close to those calculated by the transverse resonance method.     

An optical IM/FSK coding technique for the implementation of a label-controlled arrayed waveguide packet router

In this paper, we present a new concept of optical packet/burst switching suitable for generalized multiprotocol label switched (GMPLS)-based optical networks. In such networks, optical labeled switched paths are being established in a similar way as label-switched paths in MPLS. We use a wavelength label as well as an orthogonally modulated label, with respect to the payload modulation format, and which is encoded using either frequency-shift keying (FSK) or differential phase-shift keying (DPSK). Wavelength is used for switching in the node, whereas the orthogonal label defines the label-switched path. We present both simulation and experimental results to assess transmission performance of the proposed combined modulation scheme. In addition, we propose a suitable optical node architecture that can take advantage of this stacked label concept. Toward this, we use widely tunable wavelength converters to efficiently route IM/FSK (or IM/DPSK) optically labeled packets in an arrayed-waveguide grating (AWG)-based node structure. We present performance simulation results in terms of packet loss ratio and internal block probability. Internal blocking is an inherent problem of AWG optical routers, and a specific wavelength assignment algorithm has been developed to minimize it. Finally, the feasibility of IM/FSK transmission is experimentally demonstrated over an 88-km single-mode fiber span, and novel aspects of FSK generation and detection techniques are presented.     

Gaussian Mixture Model-Based Bayesian Analysis for Underdetermined Blind Source Separation

This paper proposes a Gaussian mixture model-based Bayesian analysis for blind source separation of an underdetermined model that has more sources than sensors. The proposed algorithm follows a hierarchical learning procedure and alternative estimations for sources and the mixing matrix. The independent sources are estimated from their posterior means, and the mixing matrix is estimated by the maximum likelihood method. Because each source is conditionally correlated with others in its Markov blanket, the correlations between them are approximated by using linear response theory; this is based on the factorized approximation to the sources' true posteriors. In this framework, each source is modeled as a mixture of Gaussians to fit its actual distribution. Given enough Gaussians, the mixture model can learn any distribution. The algorithm provides a good identification of the mixing system, and its flexibility speeds up the convergence. The iterative learning for Gaussians leads to a parametric density estimation for all hidden sources as well as their recovery in the end. The major advantages of this algorithm are its flexibility and its fast convergence. Simulations using synthetic data validate the effectiveness of the algorithm.     

Study of Load Modeling Technology on Hardware-in-the-Loop Simulator of Gun Servo System

A hardware-in-the-loop (HWIL) simulator for gun servo system is described in this paper, and its load modeling technologies,such as road spectrum model,sea wave model are studied. The simulation results show that the models can be used in HWIL and satisfy the requirements of hardware-in-the-loop simulator of gun servo system.     

Room-Temperature Metal-Catalyzed Ultrafast Gasification of Ultrathin Boron Flakes

The trivalent outer shell of boron renders this element electron-poor but chemically rich, exhibiting more than one dozen allotropes. Its 2D polymorph has been recently synthesized on metal substrates under ultrahigh vacuum and has attracted intense interest. However, probing its properties ex situ has been challenging due to the quality degradation—surface oxidation—that occurs upon exposure to ambient environments. Herein, this surface chemistry is investigated in regard to the air stability of ultrathin boron flakes on metals prepared by atmospheric-pressure chemical vapor deposition. The characteristic Volmer–Weber growth is recognized by the stacking of polygon-shaped, thin flakes as isolated islands. Significantly, the metal-catalyzed, ultrafast gasification of boron flakes at room temperature, exemplified by the complete, spontaneous vanishment of 200 nm-thick boron islands in 3 h is observed. A two-step mechanism, first oxygen-involved surface oxidation and then subsequent reactions with water forming a highly volatile boric acid layer, is unambiguously revealed by combined surface characterizations. The catalysis by metal substrates, corroborated by theoretical calculations, is attributed as the crucial cause of the unprecedented gasification. The concept of oxygen-free growth is thereby proposed for air-sensitive material growth by introducing in situ oxygen scavengers. These findings significantly expand the fundamental understanding of the surface chemistry of boron and pave the way for the chemical vapor deposition growth of hydrophobic materials.