短突发传输系统的联合导频和迭代译码载波同步简

Considering the low estimation accuracy and small synchronization range of carrier synchronization algorithms in low signal to noise ratio (SNR) for short burst communication systems, a joint pilot and iterative decoding soft-output carrier synchronization algorithm is proposed. Firstly, the received pilot sequence is extracted and modulation is removed, with the modulation-removed signals made cross-correlated. Then the summation of all the correlation values is used to perform initial carrier parameters estimation. Secondly, the pilot sequence is reused with the soft-output information based on the extended Turbo decoder to obtain fine frequency and phase estimation values. Theoretical analysis and simulation results show that the coarse estimation algorithm can satisfy the requirements of the frequency estimation range and estimation accuracy, and preamble-middle pilot placement is optimal for a certain length of the data frame; The turbo decoder can obtain more reliable soft-output information with small residual frequency offset after initial coarse synchronization when the normalized frequency offset is less than 1.5×10^-3, with the joint pilot and soft-output of the decoder used to estimate fine carrier parameters, which can make the turbo code achieve optimal BER performance.     

超高频RFID标签命令头解析模块设计

该文针对超高频RFIDISO 18000-6C标准,分析了移位寄存器解析方案的冗余状态,提出了采用有限状态机优化超高频RFID标签命令头解析面积的方法。采用Verilog HDL,通过设置6组命令,进行了常用方案和新提出方案逻辑门数量的对比,从而反应出标签芯片电路面积的变化。实验结果表明,当指令数量在12 32条之间时,用有限状态机解析命令头的电路面积比用移位寄存器解析的面积小15%33%。     

机器视觉技术实现缺损QR条形码识别

针对二维条形码在印刷、运输等过程中不可避免的会发生缺失、破损等问题,设计一种基于计算机视觉技术的QR条形码商品信息识别系统,通过图像处理算法实现对条形码图像的去噪、定位及解码等处理.最后对不同尺寸、不同纠错级别、不同缺损程度下的二维条形码进行了识别.实验结果表明:当二维条形码中的校正图形存在缺损时,二维条码图像仍能被正确识读;当寻像图形存在缺损时,则无法对条码图像进行正确识读.另外,图像尺寸对破损二维条码的识别也有重要影响,图像尺寸越大,能识别的缺损程度越大.     

基于可信计算的恶意代码防御机制研究*

根据TCG规范中可信传递的思想,提出一种恶意代码防御机制,对被执行的客体实施完整性度量以防止恶意代码的传播;对客体的执行权限严格进行控制,防止恶意代码的执行,降低恶意代码的传播速度并限制其破坏范围,确保系统的完整性不被破坏。利用可信计算技术设计并实现恶意代码防御机制。     

对有关抗冻设计规范问题的探讨

对《水工建筑物抗冰冻设计规范》和《渠系工程抗冻胀设计规范》不同特点做了对比分析,指出按各自的标准进行计算会给工程设计带来不同安全度,建议宜协调一致,以利工程设计遵循.     

轴类零件NC自动编程及加工仿真系统

数控自动编程是当前数控加工中编程方法的主流，它具有编程速度快、周期短、质量高、使用方便等一系列优点。文章主要研究轴类零件计算机辅助编程及仿真系统，它集成了数控加工仿真模块，可以检测输出代码的正确性，从而提高编程质量，减少出错率，加快编程速度。     

电火花线切割机3B指令可视化软件的开发

开发了一种基于VBA平台、AutoCAD驱动的3B指令可视化软件，介绍了该软件的功能与开发工具的选择，阐述了软件的设计过程。实践证明该软件有助于提高3B指令编程的正确性与效率。     

Real-time nonlinear MPC and MHE for a large-scale mechatronic application

Progress in optimization algorithms and in computational hardware made deployment of Nonlinear Model Predictive Control (NMPC) and Moving Horizon Estimation (MHE) possible to mechatronic applications. This paper aims to assess the computational performance of NMPC and MHE for rotational start-up of Airborne Wind Energy systems. The capabilities offered by an automatic code generation tool are experimentally verified on a real physical system, using a model comprising 27 states and 4 inputs at a sampling frequency of 25 Hz. The results show the feedback times less than 5 ms for the NMPC with more than 1500 variables.     

基于空间填充曲线的动态负载均衡算法

针对Web集群系统中服务器的数量不断增加、负载指标动态变化的特点,为实现均衡的分配请求,提出一种使用空间填充曲线来实现动态负载均衡的算法。利用空间填充曲线可高效得将高维数据映射到一维索引的特点,使均衡器根据实时收集的各项负载指标快速定位到最优编码的服务器。实验结果表明,该算法能有效地缩短请求响应时间,提升了集群系统的整体性能,在大规模集群系统中均衡效果更好。