适合IPv6/IPv4灵活转换的GT64的实现

文章描述了一个基于点击软件的IPv6/IPv4通用转换器(GT64)的设计和应用。GT64有3个主要部件:1个地址端口转换器———APT和2个协议转换器———PT64和PT46,能够在大多数的网络应用中完成地址、端口和协议在IPv4和IPv6两个协议领域之间相互转换。     

Analysis of an Improved Split-Step Algorithm for Simulating Optical Transmission Systems

The standard Split-Step algorithm for calculating the signal transmission through optical fibres is significantly accelerated without relevant loss of accuracy by applying IIR filters as well as Fourier transformations for the linear operator. Depending on the system topology, high speed-up factors can be achieved by switching back and forth between time and frequency domain algorithms for the linear operator. Two different IIR filters are applied for calculating linear and parabolic dispersion. The efficiency of this algorithm in combination with an innovative step-size allocation method is evaluated.     

高阻硅基铝硅合金弹性膜MEMS相移器

级联式MEMS相移器可通过悬浮于共平面波导之上的微机械可调电容的变化,来改变传输线的特性阻抗和相速,达到相移的目的.文中讨论了MEMS相移器特性对微机械电容和下拉电压的要求,并通过轻质量的铝硅合金弹性膜,获得了较低的下拉电压.测试结果表明,相移器的下拉电压不大于40V,且当控制电压大于10V时,即有明显的相移.该MEMS相移器制备于电阻率大于4000Ω*cm的高阻硅衬底上,获得了较好的传输特性,在整个测试频段1～40GHz,S21均小于3dB,并在25V时获得了大于25°的相移量.     

A 1.2-V 19.2-mW 10-bit 30-MS/s pipelined ADC in 0.13-μm CMOS

A 10-bit 30-MS/s pipelined analog-to-digital converter(ADC) is presented.For the sake of lower power and area,the pipelined stages are scaled in current and area,and op amps are shared between the successive stages. The ADC is realized in the 0.13-μm 1-poly 8-copper mixed signal CMOS process operating at 1.2-V supply voltage. Design approaches are discussed to overcome the challenges associated with this choice of process and supply voltage, such as limited dynamic range,poor analog characteristic device...     

某火炮高平机手轮力6σ稳健优化设计

火炮高平机工作环境的温度存在一个波动范围,无法人为控制,影响到其平衡性能和高平机手轮力。传统的优化设计较少考虑温度等不确定性因素对手轮力的影响。为了提高高平机的稳健性和可靠性,降低高平机手轮力对温度变化的敏感度,基于6σ稳健优化方法,将工作温度作为影响手轮力的不确定因素,对高平机进行稳健优化设计。优化结果表明,在温度变化相同幅度时,手轮力变化值减小,优化结果降低了高平机手轮力对温度变化的敏感度,提高了高平机的稳健性。     

一种加速的PCA-L1 增量子空间学习跟踪方法

为解决PCA-L1增量子空间学习跟踪方法运算量大、实时性不强的不足,分析了PCA-L1的目标跟踪算法的运算瓶颈,应用、改进了边界误差重采样(bounded particle resampling,BPR)算法,引进了加速近似梯度法(accelerated proximal gradient,APG),并测试、比较了该方法与其他经典方法的跟踪效果及运算速度.实验结果表明:该方法加速效果明显,能提高跟踪的实时性,有较强的工程应用价值.     

基于灰度共生矩阵和神经网络的Si3N4陶瓷推挤加工表面纹理分析

基于边缘破碎效应驱动裂纹软推挤加工是一项新颖的加工技术。通过采集Si₃N₄陶瓷的软推挤加工表面形貌,运用灰度共生矩阵(GLCM)分析了对比度、熵、相关性3个特征参数与加工表面纹理分布的内在关系。通过径向基网络和竞争层网络两类神经网络的分工协作,对不同加工参数下已加工表面的纹理特征进行预测和分类,其预测结果的相对误差能控制在5%之内。随着对比度和熵越大,相关性越小;分类等级越大,表面平整程度越差。通过系统实验探讨了各加工参数对纹理特征的影响,可靠地评估了加工质量的优劣。随着车刀进给速度或槽深的增大,加工表面质量变差;随着凸缘厚度的增大,加工表面质量先逐渐变差,但经过凸缘厚度2.5 mm分界点后却又有所改善。     

Si/SiC-based DD hetero-structure IMPATTs as MM-wave power-source: a generalized large-signal analysis

A full-scale, self-consistent, non-linear, large-signal model of double-drift hetero-structure IMPATT diode with general doping profile is derived. This newly developed model, for the first time, has been used to analyze the large-signal characteristics of hexagonal SiC-based double-drift IMPATT diode. Considering the fabrication feasibility, the authors have studied the large-signal characteristics of Si/SiC-based hetero-structure devices. Under small-voltage modulation (～ 2%, i.e. small-signal conditions) results are in good agreement with calculations done using a linearised small-signal model. The large-signal values of the diode's negative conductance (5 × 10⁶S/m²), susceptance (10.4 × 10⁷ S/m^2}), average breakdown voltage (207.6 V), and power generating efficiency (15%, RF power: 25.0 W at 94 GHz) are obtained as a function of oscillation amplitude (50% of DC breakdown voltage) for a fixed average current density. The large-signal calculations exhibit power and efficiency saturation for large-signal (> 50%) voltage modulation and thereafter decrease gradually with further increasing voltage-modulation. This generalized large-signal formulation is applicable for all types of IMPATT structures with distributed and narrow avalanche zones. The simulator is made more realistic by incorporating the space-charge effects, realistic field and temperature dependent material parameters in Si and SiC. The electric field snap-shots and the large-signal impedance and admittance of the diode with current excitation are expressed in closed loop form. This study will act as a guide for researchers to fabricate a high-power Si/SiC-based IMPATT for possible application in high-power MM-wave communication systems.     

移动IPv6的嵌入式系统实现

分析了移动TPv6原理,在基于PXA270处理器的嵌入式系统平台上移植了对IPv6有良好支持的 Linux操作系统及图形系统,随后在WLAN环境下采用MIPL实现移动IPv6协议,搭建了移动IPv6试验床,测试了开发的嵌入式移动IPv6系统的性能.     

UHV/CVD法生长硅基低位错密度厚锗外延层

采用超高真空化学气相淀积系统,以高纯Si2 H6和GeH4作为生长气源,用低温缓冲层技术在Si(001)衬底上成功生长出厚的纯Ge外延层.对Si衬底上外延的纯Ge层用反射式高能电子衍射仪、原子力显微镜、X射线双晶衍射曲线和Ra-man谱进行了表征.结果表明在Si基上生长的约550nm厚的Ge外延层,表面粗糙度小于1nm,XRD双晶衍射曲线和Ra-man谱Ge-Ge模半高宽分别为530'和5.5cm-1,具有良好的结晶质量.位错腐蚀结果显示线位错密度小于5×105cm-2可用于制备Si基长波长集成光电探测器和Si基高速电子器件.