Optimized staggered-grid finite-difference operators using window functions

蹒跚格子有限差别(SGFD ) 方法广泛地在地震前面的建模被使用了。向前当模特儿的结果的精确直接影响随后的地震倒置和迁居的结果。数字分散是在这个方法的问题之一。由用窗口操作符代替有限差别的操作符的窗口函数方法罐头还原剂分散，由截断 pseudospectral 方法的空间卷绕旋转系列获得了。尽管窗户操作员在 low-wavenumber 领域有高精确，他们的精确在 high-wavenumber 领域很快减少。我们开发一个最少的广场优化方法提高窗口函数方法获得的操作符的精确。我们把 SGFD 问题转变成一个最少的广场问题并且反复地发现最好的答案。当起始的值和优化的域被错误阀值放，窗口操作符被选择。conjugate 坡度方法也被采用增加答案的稳定性。近似错误分析和数字模拟结果建议建议方法增加窗户功能操作员和减少的精确数字分散。

Design of NPR-Type Cosine Modulated Filterbank Using Combinational Window Functions

This paper presents the design of near perfect reconstruction (NPR) cosine modulated filterbank (CMFB). The prototype filter is designed by the combinational window functions. These window functions provide high side-lobe-fall-off-rate (SLFOR) with better far-end attenuation which suppresses the undesired inter-ferences occur in the filterbank. A linear optimization is used to minimize the error parameters. Design ex-amples have been included to illustrate the effectiveness of the proposed technique over the earlier reported work.

Analysis of PC6 window function using fractional Fourier transform

Fractional Fourier transform(FRFT)is a linear transform generalizing Fourier transform(FT)that plays an important role in the field of signal processing and analysis.FRFT contains an adjustable parameterα,which it rotates the signal in the time frequency plane and represents the signal in an intermediate domain between time and frequency.FRFT provides a measure about the angular distribution of signal’s energy in time frequency plane.FT is a special case of FRFT when angleαis equal toπ/2.This paper presents mathematical model for obtaining FRFT of PC6 window function.The different parameters of this window function are also obtained with the help of simulation results.A comparison of window function parameters is presented using FT and FRFT.Also comparison of this window function with Hanning window function is presented in terms of Side Lobe Fall off Rate(SLFOR).For different values of FRFT order,PC6 window function shows variation in different parameters.Thus by changing the FRFT order,the minimum stop band attenuation of the resulting window function can be controlled.

Wavelet Variance Analysis of EEG Based on Window Function

A new wavelet variance analysis method based on window function is proposed to investigate the dynamical features of electroencephalogram(EEG).The exprienmental results show that the wavelet energy of epileptic EEGs are more discrete than normal EEGs, and the variation of wavelet variance is different between epileptic and normal EEGs with the increase of time-window width. Furthermore, it is found that the wavelet subband entropy (WSE) of the epileptic EEGs are lower than the normal EEGs.

Strong Consistency for the Kernal Estimates of the Random Window Width of the Density Function and its Derivatives Under Φ-Mixing Samples

In the paper,we study the strong uniform consistency for the kernal estimates of random window width of density function and its derivatives under the condition that the sequence｛Xa｝of the sample are the identically Φ-mixing random variables.

Effect of the Energy Window Width on the Estimation of Renal Function from Dynamic Renal Scintigraphy with ^99mTc-MAG3

Objective: The width of the photopeak energy window influences the image quality and quantitative accuracy of gamma camera imaging. We compared 20% and 15% energy windows in renal scintigraphy with 99mTc-mercaptoacetyltriglycine (MAG3), especially in terms of camera-based quantitative estimation of renal function. Materials and Methods: Forty patients who underwent dynamic renal scintigraphy with 99mTc-MAG3 were enrolled in this study. Images were acquired simultaneously using two energy windows centered at 140 keV and with widths of 20% and 15%. Fractional renal uptake was calculated as the ratio of initial renal uptake estimated by patient imaging to injected dose estimated by syringe imaging, and was converted to MAG3 clearance using an empirical equation determined previously from data obtained with a 20% energy window. Relative function of the right kidney was also assessed. Visual evaluation was performed to compare image quality between the 20% and 15% energy windows. Results: Both total kidney MAG3 clearance and relative function of the right kidney were identical between the 20% and 15% energy windows. Image quality was also similar irrespective of the energy window width. Conclusions: The camera-based method established using a 20% energy window is applicable for the estimation of renal function using a 15% energy window, and data obtained using 20% and 15% windows are interchangeable.

基于高倍过采样与加窗插值FFT的电力谐波分析

为提高谐波分析精度,分析了信号加窗引起的信噪比损失以及AD转换产生的量化误差,阐述了过采样技术提高信噪比的原理。在此基础上,提出了基于高倍过采样和加窗插值快速傅里叶变换(fast Fourier transform, FFT)的谐波分析方法。该方法充分利用AD转换器的潜力,以尽量高的采样速率进行AD采样,同时通过均值滤波避免高倍过采样引起的采样数据量激增问题。详细研究了所提谐波分析方法对信号中谐波分量幅值和相位的影响,并给出了简洁实用的谐波幅值和相位校正方法。仿真表明,所提方法可在不增加系统成本的前提下改善加窗插值FFT的抗噪声能力,提高谐波分析精度。

哈密瓜物流堆码运输包装件共振传递特性研究

为优化设计缓冲包装件,以及减缓运输过程中由共振引起的哈密瓜贮藏品质下降,采用哈密瓜及其包装瓦楞纸箱作为研究对象,设置5层堆码高度,进行模拟运输变频振动试验,结合频谱分析加汉宁窗函数测定各堆码包装件的固有频率,随后进行模拟运输定频振动试验。结果表明,加汉宁窗函数有效提高了频谱分析精度,获得5层包装件的固有频率分别为9.88,54.75,10.06,10.31,10.42 Hz;10 Hz定频振动下,5层包装件的峰值加速度分别为5.99,3.18,6.37,6.56,6.81 g,振动传递率分别为53.61%,28.52%,57.07%,58.76%,61.02%;54.75 Hz定频振动下,5层包装件的峰值加速度分别为1.29,6.34,0.99,0.87,0.23 g,振动传递率分别为8.38%,45.04%,6.47%,6.04%,0.75%。研究为其他包装件寻求更精确的共振频率,从而为运输过程中有效避开共振频率,达到内装果品减损目的提供参考。

基于自适应组合窗函数的SPWVD算法及应用研究

针对平滑伪Wigller-Ville分布(Smoothing Pseudo-Winger-Ville distribution,SPWVD)在处理不同信号时,需要采用对应的平滑窗参数才能达到最优时频分布的问题,提出了一种基于自适应组合窗函数的SPWVD算法。该算法将Rényi熵作为时频评价指标,以组合窗函数的窗长和系数作为参数库,提出将随机梯度下降和扰动随机梯度下降分别用于窗长和系数的选取,提升计算速度分别为遍历法的20倍和9倍,最终得到信号的最优时频图。将上述的改进方法应用于碳纤维复合材料的缺陷检测中,结果表明,自适应组合窗函数的SPWVD可以有效地对不同信号选取最优的窗函数参数,对比固定窗函数的SPWVD,自适应组合窗函数的SPWVD具有更好的时频聚集效果,更加完备地对信号进行了表征,并对缺陷进行了定量分析,具备缺陷检测的良好应用前景。

Windows9X下PC机与变频器的串行通信

介绍了在 Ｗｉｎｄｏｗｓ ９ｘ环境下，利用动态链接库技术，将Ｗｉｎｄｏｗｓ ＡＰＩ通信函数封装于动态链接库中，以适应ＰＣ机与变频器之间的串行通信。

重叠加窗下卫星直序扩频通信干扰非线性抑制方法

由于离散傅里叶变换是通过对整个窗口内的信号进行频域变换,如果信号在窗口的两端产生不连续性,会导致频谱泄漏。而重叠加窗技术能够通过窗口的重叠部分来平滑信号,在不同时间窗口之间实现平滑过渡,减小频率泄漏和旁瓣效应的影响。因此,为提高通信性能,文中研究重叠加窗下卫星直序扩频通信干扰非线性抑制方法。将卫星直序扩频通信信号分成两路,通过改进升余弦窗函数,分别进行1/2重叠加窗处理;利用调制离散傅里叶变换算法变换加窗后的两路扩频通信时域信号,得到频域信号;采用自适应门限干扰检测算法非线性干扰抑制两路频域信号;由改进自适应幅度恢复非对称算法还原抑制后的频域信号,并对其进行逆变换处理,得到时域信号;按照1/2重叠加窗思想,融合两路时域信号,完成通信干扰非线性抑制。实验结果证明:该方法可有效重叠加窗处理卫星直序扩频通信时域信号,避免了旁瓣效应的影响,准确地抑制了卫星直序扩频通信干扰。

Windows CE.NET环境下的流接口驱动程序开发

针对在WindowsCE.NET环境下进行驱动程序设计的难点及其设计时的具体特点和要求,主要介绍了基于WindowsCE的两种驱动模型,即本机驱动程序和流接口驱动程序,并重点对流接口驱动程序开发方法的4个方面进行了较为详细的探讨和描述。进而,以串行接口为例,给出了具体的开发过程和部分源代码,以便于在此基础上举一反三、有效地进行其他多种类型接口程序的开发及更为深入的研究。

Windows环境下的逻辑调色板及其应用

全面剖析了Windows操作系统处理色彩的关键”部件”－逻辑调色板的结构，简要说明了Windows操作系统提供的逻辑调包权操纵函数，详细论述了Windows应用程序创建和使用逻辑调色板，进而处理高质量图形图象的操作过程。

Performance analysis of fast GPS signal acquisition based on PMF and Window FFT

Combining the advantages of partial matched filter（PMF） and fast Fourier transform（FFT）,an improved fast acquisition method for GPS C/A code is proposed.According to PMF-FFT acquisition architecture,the greater the number of PMF will bring out the more slowly amplitude decreasing of the amplitude-frequency response,the smaller scale of the corresponding PMF,and the larger computation of the FFT.In order to compensate the frequency spectrum attenuation caused by spectrum leakage and fence effect,adding window function to PMF-FFT is presented.Through comparing the influences to the acquisition performance based on rectangular,Hamming,Blackman and Rife-Vincent（Ⅲ） window functions,an improved Rife-Vincent Ⅲ windowing algorithm is recommended for the fast acquisition based on PMF-FFT.

Windowing Techniques, the Welch Method for Improvement of Power Spectrum Estimation

This paper revisits the characteristics of windowing techniques with various window functions involved,and successively investigates spectral leakage mitigation utilizing the Welch method.The discrete Fourier transform(DFT)is ubiquitous in digital signal processing(DSP)for the spectrum analysis and can be efciently realized by the fast Fourier transform(FFT).The sampling signal will result in distortion and thus may cause unpredictable spectral leakage in discrete spectrum when the DFT is employed.Windowing is implemented by multiplying the input signal with a window function and windowing amplitude modulates the input signal so that the spectral leakage is evened out.Therefore,windowing processing reduces the amplitude of the samples at the beginning and end of the window.In addition to selecting appropriate window functions,a pretreatment method,such as the Welch method,is effective to mitigate the spectral leakage.Due to the noise caused by imperfect,nite data,the noise reduction from Welch’s method is a desired treatment.The nonparametric Welch method is an improvement on the periodogram spectrum estimation method where the signal-to-noise ratio(SNR)is high and mitigates noise in the estimated power spectra in exchange for frequency resolution reduction.The periodogram technique based on Welch method is capable of providing good resolution if data length samples are appropriately selected.The design of nite impulse response(FIR)digital lter using the window technique is rstly addressed.The inuence of various window functions on the Fourier transform spectrum of the signals is discussed.Comparison on spectral resolution based on the traditional power spectrum estimation and various window-function-based Welch power spectrum estimations is presented.

VB5.0中应用Windows API函数实施编程的策略

本文介绍了在ＶＢ５．０中，通过调用 Ｗｉｎｄｏｗｓ ＡＰＩ函数来实现对多媒体、图形设备的访问等，并详述了 ＡＰＩ函数的涵义及其使用方法，注意事项以及如何运用ＡＰＩ函数编写程序、优化程序，提高编程效率的典型实例．

Windows环境下动态链接库(DLL)程序设计

介绍了在 Windows平台下动态链接库的工作机制 ,详细讨论了使用动态链接库的编程方法 ,并给出了一个DL L 主函数的例子。

MS Windows兼容的系统芯片硬件核心的分析与实践

研究了开发MS Windows兼容的系统芯片硬件核心的方法。该方法在确保MS Windows兼容的前提下,通过多次模拟运行、逐步抽取的方式获得硬件核心基本系统功能规范。实验表明,相对于完整系统,该硬件核心的复杂度大幅度降低,同时表明不同MS Windows版本所需硬件核心有明显差别。此外,还在FPGA原型上验证了支持MSWindows 98的系统芯片硬件核心。

Authorware中Windows标准菜单的实现

介绍了在Authorware环境下,利用WindowsAPI函数实现Windows标准菜单的方法。所设计的标准菜单具有灵活性和使用方便等特色。

改进蚁群算法的送餐机器人路径规划

蚁群算法拥有良好的全局性、自组织性、鲁棒性,但传统蚁群算法存在许多不足之处。为此,针对算法在路径规划问题中的缺陷,在传统蚁群算法的状态转移公式中,引入目标点距离因素和引导素,加快算法收敛性和改善局部最优缺陷。在带时间窗的车辆路径问题(vehicle routing problem with time windows,VRPTW)上,融合蚁群算法和遗传算法,并将顾客时间窗宽度以及机器人等待时间加入蚁群算法状态转移公式中,以及将蚁群算法的解作为遗传算法的初始种群,提高遗传算法的初始解质量,然后进行编码,设置违反时间窗约束和载重量的惩罚函数和适应度函数,在传统遗传算法的交叉、变异操作后加入了破坏-修复基因的操作来优化每一代新解的质量,在Solomon Benchmark算例上进行仿真,对比算法改进前后的最优解,验证算法可行性。最后在餐厅送餐问题中把带有障碍物的仿真环境路径规划问题和VRPTW问题结合,使用改进后的算法解决餐厅环境下送餐机器人对顾客服务配送问题。