STK空中下载技术中的同步计数器机制研究

该文在介绍STK空中下载技术的基础上,对同步计数器机制及GSM03.48定义的同步机制进行了深入的分析和讨论,并提出了一种适用于空中下载技术的同步计数器机制,此机制能够防止重传攻击,为用户和系统提供完善的安全保证。     

施加反拉力的超声振动拉丝过程仿真

基于库伦摩擦模型和非局部摩擦模型对超声振动拉拔钛合金丝材的全过程进行有限元分析,分析结果表明：当反拉力小于临界反拉力时,拉拔应力基本保持不变,当反拉力超过临界反拉力时,拉拔应力迅速增加。在拉丝过程中施加临界反拉力可以在保持拉拔应力基本不变的情况下,减径区接触压应力和摩擦应力均有一定程度减小,且在非局部摩擦模型下所得结果比常规摩擦模型下所得结果误差要小。     

Electrodeposited Pt for cost-efficient and flexible dye-sensitized solar cells

Pt electrodes were prepared by direct and pulse current electrodeposition for use as counter electrodes in dye-sensitized solar cells. Scanning electron microscope and transmission electron microscope images confirmed the formation of uniform Pt nanoclusters of ∼40 nm composed of 3 nm nanoparticles, when the pulse current electrodeposition method was used, as opposed to the dendritic growth of Pt by the results from direct current electrodeposition. By applying pulse electrodeposited Pt which has a 1.86 times higher surface area compared to direct current electrodeposited Pt, short-circuit current and conversion efficiency were increased from 10.34 to 14.11 mA/cm² and from 3.68 to 5.03%, respectively. In addition, a flexible solar cell with a pulse current electrodeposited Pt counter electrode with a conversion efficiency of 0.86% was demonstrated.     

Boron removal by ion exchange membranes

Boron removal from aqueous solution was studied through Neosepta-AHA membrane by Donnan dialysis (DD) method as a function of concentration, pH, conduct time, membrane structure and effect of accompanying ions. The feasibility of the system was examined and the highest boron removal was obtained when the pH of the feed phase was 9.5. On the other hand, it was determined that reverse flow transition was accelerated by counter ions and HCO₃⁻ ion was found to be more effective than Cl⁻ and SO₄⁻² ions. It was determined that obtained results of AHA membrane was compared with Neosepta AFN and AMH membranes and the flow rate of boron through Neosepta AHA, AFN and AMH anion exchange membranes were found to be between 3.10⁻⁸−3232.10⁻⁸ mmol cm⁻² s⁻¹ depending on concentration of feed and receiver phases, pH as well as counter ion properties. The order for recovery of boron for membranes was found to be as AFN>AMH>AHA. It could be concluded that the DD method is an appropriate method for boron removal from aqueous solution when an appropriate counter anion was chosen at suitable pH value.     

基于FPGA的频率计电路设计

本文介绍了数字频率计设计的基本原理,对频率计所采用各种硬件除法进行了比较,提出了倍频计数法测量数字高频的实现方案,并给出了频率计设计的硬件电路原理和软件实现,结果表明这种方法实现了频率计的高速和高精度。     

适用于CCSDS的“一帧一密”加/解密方案的FPGA实现

加密是卫星数据传输系统特别是卫星星地数据传输系统的重要组成部分。设计了一种针对CCSDS标准的加/解密方案,该系统以Xilinx Spartan 6开发板为开发平台,以AES为核心加密算法,CTR模式为工作模式,能实现对少于块大小的数据的加密而不产生冗余数据,克服了分组加密算法只能对固定块大小的数据进行加密的局限性。提出“一帧一密”的加密方案,能有效提高算法的安全性。算法中采用的流水线结构和逻辑复用方法,能有效提高速度与节省芯片资源。在33 MHz时钟下测试,系统加密速度和解密速度都能达到264 Mb/s。     

利用计数器进行定位控制一例

本文介绍了一个使用计数器进行定位控制改造的例子和实现方法。为在一定场合利用计数器取代伺服控制或PLC特殊单元实现定位控制提供了参考实例。     

One-step synthesis of methylmethacrylate from methacrolein over Keggin-type heteropoly compounds

One-step synthesis of methylmethacrylate (MMA) using heteropoly compounds (HPCs) as catalysts was demonstrated by feeding a mixture of methacrolein (MAL), air, water, nitrogen and MeOH (methanol). The HPCs with different counter-ions, such as H_1.7Cs_1.5Cu_0.25As_0.1PMo₁₁VO₄₀ (CsPMo₁₁VO₄₀), H_1.7La_0.7Cu_0.25As_0.1PMo₁₁VO₄₀ (LaPMo₁₁VO₄₀) and H_1.7K_1.5Cu_0.25As_0.1PMo₁₁VO₄₀ (KPMo₁₁VO₄₀), were studied in oxidation of MAL, esterification of methacrylic acid (MAA) and one-step synthesis of MMA from MAL, respectively. The selectivity of MAA was up to 45.7% and MMA was 44.6% with 93.3% MAL conversion over CsPMo₁₁VO₄₀.     

宝钢三热轧跟踪系统运行分析

在热轧工艺的生产过程中，跟踪系统的正常工作至关重要。本文能过对热跟踪系统的分组方式，以及各类功能的描述，阐述了三热轧跟踪系统的工作原理。并且简单分析了在今后的调试和维护阶段，跟踪系统所以要关注的内容。     

双散射角光学粒子计数器的研制

为了实现同时测量气溶胶粒子的谱分布和折射率,研制了一种新的双角度光学粒子计数器(D-OPC),该计数器采用60°和110°双散射角系统对气溶胶谱分布进行测量.利用Mie散射理论定义敏感函数,选取两个最佳的散射角,使其既对折射率敏感又不线性相关.然后,利用气溶胶折射率对两个散射角系统敏感性的差异来反演气溶胶折射率.最后,利用该仪器对大气气溶胶谱分布以及折射率进行实际测量.与TSI公司黑炭仪和浊度计测量的吸收系数和散射系数对比表明,双散射角光学粒子计数器测量气溶胶折射率和谱分布结果合理,测量误差<20%,可以满足同时测量气溶胶粒子谱分布和折射率的需要.