共查询到20条相似文献,搜索用时 15 毫秒
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Carbone P. Narduzzi C. Petri D. 《IEEE transactions on instrumentation and measurement》1996,45(2):435-439
Dithered quantizers are often employed in numerical instrumentation to improve the resolution and accuracy of the analog-to-digital converters used. To this aim, linear post-processing is usually performed on the quantized samples. In the paper, a different processing scheme is described that exhibits a nonlinear behavior. The characteristics of both linear and nonlinear topologies are analyzed, and expressions are given for the quantization error average and variance that make possible the comparison of the two algorithms. It is shown that the nonlinear one provides better performance, so that it can be employed to further improve the estimation capability of a dithered quantizing system. The reported results have been validated by means of meaningful simulations 相似文献
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主要研究了大角速度信号输入对栅结构振动式微陀螺及其检测电路分辨率的影响。在0.01-200°/s的动态范围内,按照设计值,陀螺器件与检测电路组成的系统能够分辨0.01°/s的输入角速度变化。考虑到驱动电压和积分电容与敏感电容的特性差异的影响后,当输入角速度大于10°/s时,整个系统即无法分辨0.01°/s的输入角速度变化。针对这种情况,提出了在传感器件上集成关键元件的方法来解决大角速度信号输入下整个系统分辨率降低的问题。 相似文献
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In this paper, the authors discuss the use of deterministic and stochastic dither sequences in analog-to-digital conversion including data postprocessing. Properties of both types of dither signals are highlighted, and a performance comparison is carried out by considering residual bias and mean square error. It is concluded that superior performance can be attained by deterministic dither in terms of system resolution and accuracy, at the expense of worse spectral characteristics. Experimental results are provided to support simulations and theoretical analysis 相似文献
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To increase the signal-to-noise ratio and to remove the spatially slow varying signals, a lock-in amplifier is often used in scanning probe microscopy. The signal reconstructed from the lock-in data contains the contributions of the evanescent and homogeneous waves that are mixed in the near-field zone (i.e., at a very short distance). The resolution is determined and a method is given to suppress the useless background information. Experimental images of nanoparticles are processed. 相似文献
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The collimated optical beam in a grating spectrometer may be circular or elliptical in cross section, so that different parts of the beam illuminate different numbers of grooves on the grating. Here we estimate the consequent loss in spectral resolution relative to that obtained with a beam that illuminates a fixed number of grooves. The effect reduces the intrinsic resolving power of the spectrometer by ~15%, exclusive of other contributions such as finite entrance-slit width. 相似文献
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环境噪声和工频噪声的干扰对脑电信号(EEG)的进一步处理和分析带来极为不利的影响。针对传统小波系数软阈值消噪方法去噪后产生的波形失真和硬阈值消噪方法去噪后产生的振荡现象,提出了一种新的小波系数非线性连续函数衰减处理算法。通过小波系数的非线性衰减处理,使低值端小波系数连续函数的变化介于硬软阈值函数之间,有效避免了处理后的波形失真和振荡。通过实验数据比较,证明处理后的脑电信号信噪比和均方误差均优于传统的小波去噪处理方法。 相似文献
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Alam SK Ophir J 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2000,47(1):297-303
We have reported several artifacts in elastography (1991). These include mechanical artifacts, such as stress concentration, and signal processing artifacts, such as zebras, which are caused by bias errors incurred during the estimation of the peak of correlation functions using a curve-fitting method. We investigate the bias errors and show that bias errors in curve-fitting methods are substantially increased because of nonlinear operations on the echo signals that reduce other errors. We also show that, for typical sampling rates, the bias errors can be ignored in the absence of these nonlinear operations. 相似文献
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高速数字电路中信号反射的分析及解决方案 总被引:5,自引:1,他引:5
随着微电子技术的不断发展,在数字系统设计中系统工作频率不断增加,高速器件的使用越来越广泛。对信号进行完整性分析已经成为高速数字电路设计中的一个必要环节。针对高速数字电路设计存在的信号完整性反射噪声问题,首先从理论上分析了信号反射产生的原因及解决方法。然后以高速数字测试模块为例,利用Mentor GraPhics公司的Hypcdy似软件进行仿真验证,以达到在设计阶段消除反射噪声的目的。 相似文献
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通过对信号处理领域抖动调制原理的分析,并结合人类视觉系统的掩蔽效应,提出了一个DCT 域盲水印模型。在MATLAB 仿真环境中,针对二值图像水印,实现了水印的预处理、嵌入、提取以及F 范数下水印检测。在水印嵌入过程中,通过自动调节量化步长改善了水印的透明性,水印检测时无需原始宿主图像,实现了盲检测,而且省略了反余弦变换过程,降低了算法复杂度。仿真实验表明,水印算法在JPEG 高强度压缩、剪切、各种噪声叠加以及多重水印等攻击下具有高鲁棒性。算法思想可应用于数字版权保护以及隐秘通讯等领域。 相似文献
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Mitigating the effects of system resolution on computer simulation of Portland cement hydration 总被引:2,自引:1,他引:1
CEMHYD3D is an advanced, three-dimensional computer model for simulating the hydration processes of cement, in which the microstructure of the hydrating cement paste is represented by digitized particles in a cubic domain. However, the system resolution (which is determined by the voxel size) has a prominent influence on the simulation results and, thus, is difficult to choose a priori. In this paper, it is shown that the effects of system resolution on the simulation results are mainly due to the lack of considerations of the diffusion-controlled reactions in the model. A new concept “hydration layer” is proposed for mitigating the effects of system resolution on the model predictions. By performing simulations with different system resolutions, the robustness of the improved model is demonstrated. Comparisons of model predictions with experimental measurements further demonstrate that the use of hydration layer can successfully mitigate the bias brought by the system resolution. 相似文献
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B. N. Morozov 《Measurement Techniques》1997,40(5):413-421
Analysis and derived formulas were employed to examine the salient features of the process when the current and voltage due
to optical rectification in crystals were used to measure the electric parameters of continuous, pulsed, and pulsed-periodic
lasers, with allowance for spatial dispersion. The errors of measurement were evaluated. Meters based on optical rectification
show promise for use in laser fusion facilities and for measuring the efficiency of harmonic generation.
Translated from Izmeritel'naya Tekhnika, No. 5, pp. 8–14, May, 1997. 相似文献
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The surface and nonlocal effects on the nonlinear flexural free vibrations of elastically supported non-uniform cross section nanobeams are studied simultaneously. The formulations are derived based on both Euler–Bernoulli beam theory (EBT) and Timoshenko beam theory (TBT) independently using Hamilton’s principle in conjunction with Eringen’s nonlocal elasticity theory. Green’s strain tensor together with von Kármán assumptions are employed to model the geometrical nonlinearity. The differential quadrature method (DQM) as an efficient and accurate numerical tool in conjunction with a direct iterative method is adopted to obtain the nonlinear vibration frequencies of nanobeams subjected to different boundary conditions. After demonstrating the fast rate of convergence of the method, it is shown that the results are in excellent agreement with the previous studies in the limit cases. The influences of surface free energy, nonlocal parameter, length of non-uniform nanobeams, variation of nanobeam width and elastic medium parameters on the nonlinear free vibrations are investigated. 相似文献
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Rs. I. Nigmatulin V. V. Politov K. A. Keivsar 《Journal of Engineering Physics and Thermophysics》2012,85(1):216-220
The results of investigations into the use of effects produced with hydrodynamic oscillators for solution of certain engineering problems have been presented. 相似文献