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1.
Traditional noise-filtering techniques are known to significantly alter features of chaotic data. In this paper, we present a noncausal topology-based filtering method for continuous-time dynamical systems that is effective in removing additive, uncorrelated noise from time-series data. Signal-to-noise ratios and Lyapunov exponent estimates are dramatically improved following the removal of the identified noisy points. 相似文献
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We report on a manifold advanced dual-wavelength digital holographic microscopy (DHM) configuration with a real-time measurement capability. The proposed configuration based on a polarizing separation scheme can be used for microscopic imaging polarimetry as well as dual wavelength digital holographic microscopy. In this paper, we show the feasibility of the proposed scheme by conducting the dual wavelength DHM experiments on a sample with a step height of 1.34 μm nominally. An averaging technique is treated and three-dimensional (3D) topographic measurements are presented. The results obtained by the proposed polarization separation based single shot DHM approach shows it can provide a real time solution for measuring 3D profile information of small objects with excellent accuracy. 相似文献
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Yamazaki Kazuyoshi Hosaka Makoto Yamada Kenichiro Ogata Takeshi Shimada Kenichi 《Optical Review》2016,23(5):848-858
Optical Review - A precise and fast method for controlling the reference-beam angle of an angular-multiplexed holographic data storage system (HDSS)—to achieve larger capacity and faster... 相似文献
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混沌信号与确定性小信号叠加生成的混合信号是一更高维的混沌信号,因而不能用一般的混沌信号噪声抑制的方法进行分离.提出了一种这类信号盲分离的方法.在重构未知的混沌信号的动力方程时,充分利用混沌吸引子的几何特性,并且限定动力映射为原混沌吸引子所在流形的内部映射,从而保证了重构的动力系统方程对应于原混沌信号,而不是同样具有混沌特性的混合信号.然后利用重构的动力方程,借用混沌信号中的噪声抑制思想,估计出原混沌信号对应的轨道,实现信号分离.通过对Lorenz系统中谐波信号、Henon映象中自回归过程,以及脑电信号中谐波信号进行提取的数值实验,验证了信号盲分离方法的有效性和可行性.
关键词:
混沌
非线性
信号处理
盲分离 相似文献
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In the process of the reconstruction of digital holography, the traditional methods of diffraction and filtration are commonly adopted to recover the original complex-wave signal. Influenced by twin-image and zero-order terms, the above-mentioned methods, however, either limit the field of vision or result in the loss of the amplitude and phase. A new method for complex-wave retrieval is presented, which is based on blind signal separation. Three frames of holograms are captured by a charge coupled device (CCD) camera to form an observation signal. The term containing only amplitude and phase of complex-wave is separated, by means of independent component analysis, from the observation signal, which effectively eliminates the zero-order term. Finally, the complex-wave retrieval of pure phase wavefront is achieved. Experimental results show that this method can better recover the amplitude and phase of the original complex-wave even when there is a frequency spectrum mixture in the hologram. 相似文献
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就一种基于非线性累加和的信号盲分离方法作了探讨。首先,文中针对方法中非线性函数特性对信号分离的影响从理论上作了分析,给出了加快迭代收敛的约束条件。接着,将该方法从无卷积混合信号分离的情况推广到混合卷积情形。最后通过数值模拟,给出了信号分离结果。 相似文献
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In the process of the reconstruction of digital holography, the traditional methods of diffraction and filtration are commonly adopted to recover the original complex-wave signal. Influenced by twin-image and zero-order terms, the above-mentioned methods, however, either limit the field of vision or result in the loss of the amplitude and phase. A new method for complex-wave retrieval is presented, which is based on blind signal separation. Three frames of holograms are captured by a charge coupled device (CCD)camera to form an observation signal. The term containing only amplitude and phase of complex-wave is separated, by means of independent component analysis, from the observation signal, which effectively eliminates the zero-order term. Finally, the complex-wave retrieval of pure phase wavefront is achieved.Experimental results show that this method can better recover the amplitude and phase of the original complex-wave even when there is a frequency spectrum mixture in the hologram. 相似文献
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为了提高数字全息图的重建速度和精度,本文提出了一种基于同态信号处理的数字全息广义线性重建算法. 首先利用预放大数字全息显微系统并结合同态信号处理原理进行了理论分析,得到了广义线性重建算法的实现条件及重建步骤,并对该算法的优点进行了分析;然后利用计算机模拟和实验相结合的方法对理论分析进行了验证. 结果表明:数字全息广义线性重建算法不仅可以有效的消除全息图频谱中零级项的干扰,实现高精度再现,而且由于采用一个完整象限的固定区域滤波,避免了常规线性算法的手动滤波操作,极大地提高了重建速度,同时最大限度地保留了原始像中的高频成分,实现全息图的高分辨重建.
关键词:
数字全息显微术
同态信号处理
傅里叶变换
分辨率 相似文献
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双全息面分离声场技术及其在声全息中的应用 总被引:5,自引:1,他引:5
提出双全息面分离声场技术,克服以往近场声全息(NAH)和基于声强测量的宽带声全息(BAHIM)的应用局限。以往方法的局限在于:全息面一侧的声场必须是自由声场,即要求所有的声源仅能位于全息面的另一侧;而在实际测量的情况下,这个要求是很难达到的。本文提出的声场分离技术利用波场的外推理论,建立起在波数域声场分离的公式,然后通过二维Fourier逆变换,便得到了全息面一侧声源产生的声压,从而达到声场分离的目的。原理的推导理论上论证该技术正确性,数值仿真显示了方法的可行性和有效性。 相似文献
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T E Hanna 《The Journal of the Acoustical Society of America》1986,80(2):473-478
The detectability of a sinusoid masked by two sinusoids was studied as a function of signal phase and the frequency separation between the two maskers. The signal frequency fs was equal to the arithmetic mean of the two masker frequencies, fl and fh, where fl less than fh. Signal frequencies of 1 and 4 kHz, eight signal phases, and 12 values of r = (fh-fl)/fs from 0.01-1.0 were used. The data could be divided into three regions. For large masker separations, r greater than 0.4, no consistent effects of signal phase were observed. For r less than 0.4, an effect of signal phase was evident at both signal frequencies. However, the effect of signal phase was different for the two regions 0.03 less than r less than 0.4 and r less than 0.03. For moderate masker separations, 0.03 less than r less than 0.4, masked thresholds were lowest at phases of 0 degrees and 180 degrees and highest at phases of 90 degrees and 270 degrees. For small masker separations, r less than 0.03, masked threshold was highest at 0 degree and the effect of signal phase depended on signal frequency. The different form of the phase effect for these three regions is discussed in terms of the use of different cues, arising from temporal resolution, spectral filtering, combination tones, and envelope spectra. 相似文献
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We address the problem of locating a transient source, such as an acoustic emission source, in a plate. We apply time-frequency analysis to the signals detected at a receiver. These highly dispersive and complex waveforms are measured for source-receiver separations ranging from 40 to 180 plate thicknesses and at frequencies such that 10 to 20 Rayleigh-Lamb branches are included. Reassigned, smoothed, pseudo-Wigner-Ville distributions are generated that exhibit the expected sharp ridges in the time-frequency plane, lying along the predicted frequency-time-of-arrival relations. The source-receiver separation can be determined from such plots. 相似文献
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Rahul Bhatt Lata Mainali Gyanendra Bhatnagar Asha Sharma Arun K. Gupta 《Optics and Lasers in Engineering》2008,46(3):217-221
Conventional methods of measuring the various parameters of holographic optical elements are tedious for mass production. A novel approach is described for the holographic elements used in the holographic sight, in which the parameters are defined and measured as per their intended final application. Since the holographic sight is used for accurate target acquisition along with the other features, parallax in the sight becomes a critical parameter. Besides, the maximum brightness of the reticle is another parameter of the device, which is important for the use of sight in the strong sunlight in summers. There are two holographic elements, namely holographic reticle and holographic lens in the sight. Both can be tested in a simple set-up in terms of the parallax of the sight and the brightness of the reticle. The masters for both elements are required to be benchmarked once and rest of the elements in a mass production can be tested with the reference of masters. 相似文献
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Allowing for the effect of a synthetic aperture of the transmitter, we obtain an expression for the generalized autocorrelation
function of a useful spatio-temporal signal of the measuring radar system whose ground-based receiver is equipped with a coherent
two-site antenna system, while the transmitter is located on a satellite. It is shown that the natural coordinates for measurement
by such a system are (i) the range to the object, measured from the delay time of the received signal, (ii) the projection
of the radius vector of the object onto the direction of the satellite ground track, measured from the Doppler shift of the
received-signal frequency, and (iii) the projection of the radius vector of the object onto the direction perpendicular to
the satellite ground track, measured from the arrival direction of the received electromagnetic wave by the two-site receiving
system.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 12, pp. 1033–1040, December 2005. 相似文献
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《Journal of Russian Laser Research》1988,9(5):695-766
Chapter 7 Electronic systems for Doppler signal separation and processing 相似文献
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In the manganites L1?xMxMnO3 (L = La, Nd, Pr, …; M = Sr, Ba, Ca, …), the doping concentration introduces a mixed valence (Mn3+, Mn4+) which governs the magnetic and electric properties of the compound. Mn3+ (S = 2) is scarcely observed in electron spin resonance (ESR). In contrast, Mn4+ (S = 3/2), is a good ESR probe. However, X-band measurements show an enhanced Mn4+ susceptibility, which is the signature of some kind of coupling of the Mn4+ ions with the Mn3+ ions, but its exact nature is still controversial. We present multifrequency ESR experiments (9–385 GHz) obtained on different systems (La1?δMnO3, La1?xMnO3, La1?xCaxMnO3, and Nd1?xCaxMnO3) in the low-concentration range (0 <x< 0.33). In the paramagnetic regime, the Mn3+ spectrum cannot be observed because of fast relaxation. The signal arises from polarons, whose size, temperature and magnetic field dependences vary with M andx. The single line observed in the metallic compound evolves towards a double-peak structure visible at high frequency in La0.97MnO3. Its evolution with temperature below the magnetic transition reveals the presence of manganese ions in a different magnetic environment, i.e., phase separation. The magnetic order of the separated phase is not ferromagnetic. It is a more complex order, which depends substantially on the nature of the cation M. 相似文献