有限自动机积的初(末)态试验序列、UIO序列和同步序列

主要对积运算后有限自动机的初(末)态试验序列、U IO序列和同步序列进行了讨论,给出了积运算后的有限自动机与积运算前有限自动机的初(末)态试验序列、U IO序列和同步序列的联系,并给出了极小有限自动机的初态试验序列与U IO序列间的联系。     

2(5H)-呋喃酮的水相Diels-Alder反应

研究了2(5H)-呋喃酮、5-羟基-2(5H)-呋喃酮与环戊二烯发生Diels-Alder反应,产物用FT-IR、1HNMR、MS进行了表征。该反应在水相中进行时,反应时间为0.5 h,比在有机相反应的时间大大缩短。     

正交有理函数与有理Radau求积公式

在具有固定极点的有理函数空间上构造了一类新的正交有理函数,并讨论了基于这类正交有理函数的有理Gauss-Radau求积公式.     

低灵敏度FIR滤波器优化结构

针对有限冲激响应(FIR)滤波器实现时因有限精度限制导致滤波器性能下降问题,基于连续时间传递函数,利用增量差分离散方法提出一种低灵敏度FIR滤波器优化结构.首先,根据传统z算子与增量差分Delta算子的关系,利用双线性变换求得模拟域离散后的状态空间实现,并将系数矩阵进行稀疏化分解得到优化结构状态空间实现;然后,采用状态...     

苦丁茶主物质提取及其HPLC指纹图谱分析

通过对苦丁茶成分的提取方式和条件初步优化,选取最优的色谱分离条件,运用高效液相色谱技术(HPLC),针对4个不同产地的10个批次苦丁茶建立指纹图谱.从图谱中所含主成分的种类和化学成分的提取率选择超声提取的方式,确定75％的乙醇为提取溶剂和30 min的超声时间.在对HPLC条件的优化过程中,根据最终实验结果的优越性选择...     

基于FPGA的基-16FFT模块的实现

阐述了采用Alter公司的StratixⅡ系列FPGA设计高速FFT处理器的实现方法及技巧;充分利用其芯片的硬件资源,减少复杂逻辑,采用流水方式对复数数据实现了FFT运算;整个设计采用流水与并行方式尽量避免“瓶颈”的出现,提高系统时钟频率,达到高速处理;实验表明,此处理器既有专用ASIC电路的快速性,又有DSP器件灵活性的特点,适合用于高速数字信号处理。     

SAR image de-noising via grouping-based PCA and guided filter

A novel synthetic aperture radar(SAR)image de-noising method based on the local pixel grouping(LPG)principal component analysis(PCA)and guided filter is proposed.This method contains two steps.In the first step,we process the noisy image by coarse filters,which can suppress the speckle effectively.The original SAR image is transformed into the additive noise model by logarithmic transform with deviation correction.Then,we use the pixel and its nearest neighbors as a vector to select training samples from the local window by LPG based on the block similar matching.The LPG method ensures that only the similar sample patches are used in the local statistical calculation of PCA transform estimation,so that the local features of the image can be well preserved after coefficients shrinkage in the PCA domain.In the second step,we do the guided filtering which can effectively eliminate small artifacts left over from the coarse filtering.Experimental results of simulated and real SAR images show that the proposed method outstrips the state-of-the-art image de-noising methods in the peak signalto-noise ratio(PSNR),the structural similarity(SSIM)index and the equivalent number of looks(ENLs),and is of perceived image quality.     

基于分子动力学的P(VDF50-TrFE50)高电场极化仿真

P(VDF-TrFE)类共聚物具有优异的铁电性能,可用于制作柔性压电传感器。在试验研究中,通常采用高电场极化来增强其压电效应。为了研究该共聚物的传感特性,本文利用分子动力学模拟软件Materials Studio(MS)建立P(VDF₅₀-TrFE₅₀)的三维晶胞模型,模拟高电场极化过程,分析各项极化条件对其剩余极化的影响。结果显示：在高电场强度下,晶胞内的大部分铁电畴在极短时间内完成翻转;P(VDF₅₀-TrFE₅₀)的极化强度与外加电场强度正相关,但当电场强度高于5 V/nm后,极化强度增长减缓;晶胞在低温时保持铁电相而在高温时转变为顺电相;被充分极化的P(VDF₅₀-TrFE₅₀)晶胞的最高剩余极化强度为59.94 mC/m²。该研究表明MS软件具有模拟P(VDF-TrFE)聚合物材料压电特性的能力,可为后续试验研究及传感器制作提供仿真依据。     

基于正交设计和灰色关联理论的混杂纤维ECC优化设计

目的 对混杂纤维工程用水泥基复合材料进行配合比优化设计,得到综合性能优越的混杂纤维ECC材料(HFRECC).方法 采用正交试验研究水胶比、PVA纤维、碳酸钙晶须(CW)以及改性PP纤维(MPP)体积分数等因素对流动度、立方抗压强度、抗折强度以及劈裂抗拉强度的影响,利用组合加权灰色关联理论确定各性能的权重,实现HFRE...     

Short-range clutter suppression method combining oblique projection and interpolation in airborne CFA radar

The airborne conformal array(CFA)radar's clutter ridges are range-modulated,which result in a bias in the estimation of the clutter covariance matrix(CCM)of the cell under test(CUT),further,reducing the clutter suppression performance of the airborne CFA radar.The clutter ridges can be effectively compensated by the space-time separation interpolation(STSINT)method,which costs less computation than the space-time interpolation(STINT)method,but the performance of interpolation algorithms is seriously affected by the short-range clutter,especially near the platform height.Location distributions of CFA are free,which yields serious impact that range spaces of steering vector matrices are non-orthogonal complement and even no longer disjoint.Further,a new method is proposed that the shortrange clutter is pre-processed by oblique projection with the intersected range spaces(OPIRS),and then clutter data after being pre-processed are compensated to the desired range bin through the STSINT method.The OPIRS also has good compatibility and can be used in combination with many existing methods.At the same time,oblique projectors of OPIRS can be obtained in advance,so the proposed method has almost the same computational load as the traditional compensation method.In addition,the proposed method can perform well when the channel error exists.Computer simulation results verify the effectiveness of the proposed method.