基于FPGA的扩频信号的相位解旋

GPS与GLONASS二合一卫星导航接收机中相位解旋(载波剥离)方案的选取和实现对基带信号处理的实现和定位解算的稳定度和精度有很大的影响,一般的相位解旋方案不能满足二合一接收机的实际情况.根据相位解旋的原理,针对二合一接收机的实际问题,选取复数对相位解旋方案,并在具体实现中对其结构进行改进.利用FPGA实现相位解旋的逻...     

基于CORDIC算法的快速NCO设计

NCO在软件无线电、数字信号处理等方面有着广泛的应用。函数发生器是NCO中的关键部分,通过FPGA流水线实现了CORDIC算法,可替代传统ROM查找表法。通过对Altera和Xilinx公司的FPGA进行仿真及综合,验证了该设计的正确性及可行性。     

8GS/s-14bit RF-DAC中数字上变频器的ASIC实现

本文提出了一种内嵌于8GS/s-14bit RF-DAC中数字上变频器(DUC)的设计方案,该方案采用ASIC实现,能够得到采样频率达8 GHz的输出信号,并提供插值因子分别为2、4、8、16的上变频功能.基于CORDIC算法,提出16路时域交织的数控振荡器(NCO)结构,同时采用全半带滤波器(HB-FIR)折叠结构级联实现内插滤波器组.基于40 nm CMOS工艺,完成RTL级设计和GDSII版图设计,并将其内嵌于8 GS/s-14bit RF-DAC中完成混合SOC的电路设计与验证.测试结果显示,该设计可以在500 MHz的工作时钟频率下达到设计目标,数字部分的版图面积为2551*2580μm^2,仿真功耗约为1365.4 mW.在40 nm CMOS工艺下流片,流片测试结果显示该芯片设计能够完成预设目标,且在插值为16的模式下,测得芯片数字部分功耗为为1250 mW,符合设计预期.     

Effects of NCO/OH Ratio and Reactive Diluent Type on the Adhesion Strength of Polyurethane Methacrylates for Cord/Rubber Composites

A series of dual curable polyurethane methacrylate-based oligomers were synthesized by changing the NCO:OH ratio and then were included in adhesive formulations using trimethylolpropane trimethacrylate and tricyclodecane dimethanol diacrylate (TCDDA) as reactive diluents. The effects of NCO:OH ratio and reactive diluent type on the structural properties of UV-cured free films and adhesion properties between polyester cord/rubber surfaces were studied. The highest adhesion strength of the 103?N?cm^?1 was obtained when the NCO:OH ratio was set as 4 and the TCDDA was used as a reactive diluent.     

深化计算机基础课程教学改革提高士官高职学员信息技术应用能力

学校教学转型后,针对士官高职学员的教学实际,提出了在计算机基础课程教学中实现教学内容项目化、课堂教学一体化、学员信息技术应用能力评价标准化和教员队伍双师化,深化计算机基础课程的教学改革,提高士官高职学员的信息技术应用能力。     

The effects of NCO/OH ratio on propylene oxide‐modified oil palm empty fruit bunch‐based polyurethane composites

In this study, the effects of NCO/OH ratio on polyurethane composites prepared from propylene oxide‐modified oil palm empty fruit bunch (EFB‐PO) properties were studied. From the results obtained, the diffusion of solvents in the composites produced was classified as Fickian type. The molecular weight between crosslink points and degree of crosslinking were affected as the NCO/OH was increased. This phenomenon was attributed to the interaction between excess NCO and accessible OH groups from EFB‐PO to form a three‐dimensional network. From the mechanical testing results, it was found that the NCO/OH ratio had a significant effect on tensile and flexural test. However, no significant influence was observed on impact strength of the composites produced. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

基于并行NCO的宽带数字下变频器

为了解决当前数字下变频器对硬件处理速度要求过高的问题,设计了一种基于并行NCO的宽带数字下变频器,将并行处理与多相滤波相结合,可以大大降低对处理速度的要求,有效解决数字信号处理的瓶颈问题。仿真结果表明,该宽带数字下变频器成功实现了对数字中频信号的下变频、滤波抽取等功能,输出结果正确,可实现宽带接收处理。     

阳离子聚氨酯的合成研究

以二异氰酸酯、聚酯多元醇、氮-甲基二乙醇胺为主要原料制备聚氨酯乳液，研究了nNCO／nOH量比值、时间对反应的影响．最终确定适宜的工艺：预聚nNCO／nOH量比值为1．6～1.9，预聚反应120min，55℃；扩链反应60min，65℃；封端反应120min，60℃．     

Reduction of lean NOx by ethanol over Ag/Al2O3 catalysts in the presence of H2O and SO2

The reduction of lean NOx using ethanol in simulated diesel engine exhaust was carried out over Ag/Al₂O₃ catalysts in the presence of H₂O and SO₂. The Ag/Al₂O₃ catalysts are highly active for the reduction of lean NOx by ethanol but the reaction is accompanied by side reactions to form CH₃CHO, CO along with small amounts of hydrocarbons (C₃H₆, C₂H₄, C₂H₂ and CH₄) and nitrogen compounds such as NH₃ and N₂O. The presence of H₂O enhances the NOx reduction while SO₂ suppresses the reduction. The presence of SO₂ along with H₂O suppresses the formation of acetaldehyde and NH₃. By infrared spectroscopy, it was revealed that the reactivity of NCO species formed in the course of the reaction was greatly enhanced in the presence of H₂O. The NCO species readily reacts with NO in the presence of O₂ and H₂O at room temperature, being converted to N₂ and CO₂ (CO). Addition of SO₂ suppresses the formation of NCO species and lowers the reactivity of the NCO species. However, the reduction of NOx is still kept at high conversion levels in the presence of H₂O and SO₂ over the present catalysts. About 80% of NOx in the simulated diesel engine exhaust was removed at 743 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

数据传输系统的FPGA一体化设计与实现

当前的差分相移键控（DPSK）数据传输系统大多是采用独立的数据调制解调终端设备和收发信设备组成的,集成度低、可靠性较差,存在内部信号量化噪声。通过应用现场可编程门阵列（FPGA）加高速数字信号处理设计技术,将数据传输系统中的信号进行DPSK调制,基带到射频信号的数字上变频,以及信号的解调与射频到基带信号数字下变频进行一体化设计,解决了DPSK调制解调终端设备与射频信道设备相互独立所带来的集成度低、可靠性差,以及设备间信号变换引起信号受损等问题。