Mixed noise removal for color images using quaternion representation

In order to effectively restore color noisy images with the mixture of Gaussian noise and impulse noise,a new algorithm is proposed using the quaternion-based holistic processing idea for color images.First,a color image is represented by a pure quaternion matrix.Secondly,according to the different characteristics of the Gaussian noise and the impulse noise,an algorithm based on quaternion directional vector order statistics is used to detect the impulse noise. Finally,the quaternion optimal weights non-local means filter （QOWNLMF）for Gaussian noise removal is improved for the mixed noise removal.The detected impulse noise pixels are not considered in the calculation of weights.Experimental results on five standard images demonstrate that the proposed algorithm performs better than the commonly used robust outlyingness ratio-nonlocal means （ROR-NLM）algorithm and the optimal weights mixed filter （OWMF）.

Effect of the mixing of s-wave and chiral p-wave pairings on electrical shot noise properties of normal metal/superconductor tunnel junctions

We study theoretically the electrical shot noise properties of tunnel junctions between a normal metal and a superconductor with the mixture of singlet s-wave and chiral triplet p-wave pairing due to broken inversion symmetry. We investigate how the shot noise properties vary as the relative amplitude between the two parity components in the pairing potential is changed. It is demonstrated that some characteristics of the electrical shot noise properties of such tunnel junctions may depend sensitively on the relative amplitude between the two parity components in the pairing potential, and some significant changes may occur in the electrical shot noise properties when the relative amplitude between the two parity components is varied from the singlet s-wave pairing dominated regime to the chiral triplet p-wave pairing dominated regime. In the chiral triplet p-wave pairing dominated regime, the ratio of noise power to electric current is close to 2e both in the in-gap and in the out-gap region. In the singlet s-wave pairing dominated regime, the value of this ratio is close to 4e in the inner gap region but may reduce to about 2e in the outer gap region as the relative amplitude of the chiral triplet pairing component is increased. The variations of the differential shot noise with the bias voltage also exhibit some significantly different features in different regimes. Such different features can serve as useful diagnostic tools for the determination of the relative magnitude of the two parity components in the pairing potential.

Mixed Noise Removal by Residual Learning of Deep CNN

Due to the huge difference of noise distribution,the result of a mixture of multiple noises becomes very complicated.Under normal circumstances,the most common type of mixed noise is to add impulse noise(IN)and then white Gaussian noise(AWGN).From the reduction of cascaded IN and AWGN to the latest sparse representation,a great deal of methods has been proposed to reduce this form of mixed noise.However,when the mixed noise is very strong,most methods often produce a lot of artifacts.In order to solve the above problems,we propose a method based on residual learning for the removal of AWGN-IN noise in this paper.By training,our model can obtain stable nonlinear mapping from the images with mixed noise to the clean images.After a series of experiments under different noise settings,the results show that our method is obviously better than the traditional sparse representation and patch based method.Meanwhile,the time of model training and image denoising is greatly reduced.

Distillability of Sudden Death in Qutrit-Qutrit Systems under Global Mixed Noise

Considering the influences of collective dephasing, multilocal qutrit-flip, local qutrit-flip, and the combination of global mixed noise, we study the dynamics of entanglement and the phenomenon of distillability of sudden death (DSD) in a qutrit-qutrit system under various decoherent noises. It is shown that the system always undergoes DSD when it interacts with multilocal and local qutrit-flip noise, and the time-determined bound entangled state is more dependent on different noises. Comparing with the cases of global mixed and collective dephasing noise,we conclude that the qutrit-flip noise is responsible for the DSD.

Mode decomposition of a noise suppressed mixing layer

Noise is generated in a two-dimensional mixing layer due to the growing of instability waves and vortex pairings. The adjoint-based control methodology has shown to be a robust tool to suppress noise radiation. The mode decomposition algorithms such as the compressible version of proper orthogonal decomposition （POD） and dynamic mode decomposition （DMD） are employed to analyze the spatial/spatial-temporal coherent structures for a consecutive data sets of the controlled mixing layer and its uncontrolled counterpart. The analyses of POD indicate that the y-direction body force control mainly modify the most energetic spatial structures, and increase the uniformity of the flow. The analyses of DMD show us prevalent frequencies and corresponding mode structures, and the stability characteristics of each mode can be obtained from DMD-spectrum. The spectral signatures illustrate that a lot of neutral/slightly damping modes emerging in uncontrolled flow within the frequency range （w 〈 0.4） are suppressed due to control, relevant spatial-temporal structures are also varied, which is coincident with the change of far-field noise spectra. From the view of mode decomposition, the action of control redistribute the energy for frequency components of ~ 〈 0.4 by weakening nonlinearities and regularizing corresponding dynamic structures in streamwise direction, and thus suppress the noise radiation. Moreover, the POD- and DMD-analysis in this study demon- strate that DMD can serve as an important supplement for POD in analyzing a time-resolved physical process.

Jet Noise Reduction of Double-Mixing Exhaust System

A jet noise reduction technique by using the external chevron nozzle with lobed mixer in the double-mixing exhaust system is investigated under cold conditions.The computations of jet field and the experiments of noise field are conducted with scaled model of high-bypass-ratio turbofan engine mixing exhaust system composed of external chevron nozzle with lobed mixer.The computational results indicate that comparing with the baseline nozzle with lobed mixer,the external chevron nozzle with lobed mixer increases mixing of jet and ambient air near the nozzle exit.The experimental results show that the external chevron nozzle with lobed mixer has better jet noise reduction at low frequencies,and this reduction rises with the increase of chevron bend angle.The experimental results also show that the external chevron nozzle with lobed mixer has sound pressure level(SPL)increase which is not obvious at high frequencies.With chevron bend angle increasing,SPL has relatively marked increase at 60°(directivity angle measured from upstream jet axis)and little fluctuations at 90°and 150°.The external chevron nozzle with lobed mixer has overall sound pressure level(OASPL)reduction in varying degrees at 60°and 150°,but it has little OASPL increase at 90°.

Numerical simulation of four-wave mixing efficiency and its induced relative intensity noise

Four-wave mixing, as well as its induced intensity noise, is harmful to wavelength division multiplexing systems. The efficiency and the relative intensity noise of four-wave mixing are numerically simulated for the two-wave and the three-wave fiber transmissions. It is found that the efficiency decreases with the increase of both the frequency spacing and the fiber length, which can be explained using the quasi-phase-matching condition. Furthermore, the relative intensity noise decreases with the increase of frequency spacing, while it increases with the increase of fiber length, which is due to the considerable power loss of the pump light. This investigation presents a good reference for the practical application of wavelength division multiplexing systems.

The effects of initial perturbation to mixing-layer noise

The far-field noise radiated from mixing layers is determined by the near-field flow dynamics which is sensitive to the initial perturbation of instability introduced physically or numerically.This study focuses on the effects of the phase delay in two initial perturbations,one at the fundamental wave number and the other at its subharmonic both calculated from linear instability analysis,on the sound generation in mixing layers.When different phase delaysφ_1 changing from zero to 2πis applied on the fundamental mode,we observe different vortex merging processes（e.g.vortex pairing or tearing）.The strong nonlinear interaction in the merging process generates most of the noise from mixing layers.There shows a pattern in a period of 2πfor the response of far-field sound to the change ofφ_1.Similar effects on the dynamics and acoustics can be achieved by adding different phase delaysφ_2 to the subharmonic mode instead,however,the response repeats in a period of onlyπforφ_2.The effects of the combination of different phase delays to other parameters,including the amplitude and wave number for each perturbations,are also investigated.All the results indicate a critical role of nonlinearity in the sound generation mechanism of mixing layers.

ADAPTIVE PINNING SYNCHRONIZATION OF COUPLED NEURAL NETWORKS WITH MIXED DELAYS AND VECTOR-FORM STOCHASTIC PERTURBATIONS

In this article, we consider the global chaotic synchronization of general cou- pled neural networks, in which subsystems have both discrete and distributed delays. Stochastic perturbations between subsystems are also considered. On the basis of two sim- ple adaptive pinning feedback control schemes, Lyapunov functional method, and stochas- tic analysis approach, several sufficient conditions are developed to guarantee global syn- chronization of the coupled neural networks with two kinds of delay couplings, even if only partial states of the nodes are coupled. The outer-coupling matrices may be symmetric or asymmetric. Unlike existing results that an isolate node is introduced as the pinning target, we pin to help the network realizing synchronization without introducing any iso- late node when the network is not synchronized. As a by product, sufficient conditions under which the network realizes synchronization without control are derived. Numerical simulations confirm the effectiveness of the obtained results.

Stochastic resonance in a time-delayed asymmetric bistable system with mixed periodic signal

This paper studies the phenomenon of stochastic resonance in an asymmetric bistable system with time-delayed feedback and mixed periodic signal by using the theory of signal-to-noise ratio in the adiabatic limit. A general approximate Fokker-Planck equation and the expression of the signal-to-noise ratio are derived through the small time delay approximation at both fundamental harmonics and mixed harmonics. The effects of the additive noise intensity Q, multiplicative noise intensity D, static asymmetry r and delay time T on the signal-to-noise ratio are discussed. It is found that the higher mixed harmonics and the static asymmetry r can restrain stochastic resonance, and the delay time τ can enhance stochastic resonance. Moreover, the longer the delay time τ is, the larger the additive noise intensity Q and the multiplicative noise intensity D are, when the stochastic resonance appears.

Impact of Channel Dynamics, Combined Nonlinearities and ASE Noise on Transmission Performance of all Optical Star WDM Networks

For all optical Wavelength Division Multiplexing (WDM) network based on G.653 fibers, we investigate the quality factor deterioration due to combined nonlinear effects and Amplified spontaneous emission (ASE) noise for system parameters based on ITU-T Recommendation G.692. The investigation: (a) emphasizes on stimulated Raman scattering (SRS) and four wave mixing (FWM) effects which are the dominant nonlinearities known to limit WDM system performance and (b) accounts for beating between nonlinearities and beating between ASE noise and nonlinearities. Using the proposed model, performance of the worst affected channels due to SRS and FWM is compared and the results indicate that the worst affected channel due to SRS performs better and hence must be preferred for reliable and efficient transmission over the worst affected channel due to FWM. Further, the results suggest that to achieve a desired error rate (quality factor);there exists an optimal value of channel spacing for a given number of channels. The proposed theoretical model is also validated through extensive simulations over Rsoft OptSimTM simulator and the two sets of results are found to match, indicating that the proposed model accurately calculates the quality factor of the all optical WDM network.

Mixed-Mode Device Modeling of DGMOS RF Oscillators

A Colpitts oscillator, working around a 3 GHz frequency, contains a double gate Metal Oxide Semiconductor transistor (DGMOS). A mixed-mode analysis is involved, applying a quantum model to the device, whereas the rest of the considered circuit is governed by Kirchhoff’s laws. The Linear Time Variant (LTV) model of phase noise is based on the Impulse Sensitivity Function of the Colpitts Oscillator which describes carefully the sensitivity of an oscillator to any impulse current injection in any node of the circuit. Finally, we improve the phase noise modeling, confronting some analytical developments to mixed-mode simulations.

An adaptive image sparse reconstruction method combined with nonlocal similarity and cosparsity for mixed Gaussian-Poisson noise removal

Compressed sensing(CS) has achieved great success in single noise removal. However, it cannot restore the images contaminated with mixed noise efficiently. This paper introduces nonlocal similarity and cosparsity inspired by compressed sensing to overcome the difficulties in mixed noise removal, in which nonlocal similarity explores the signal sparsity from similar patches, and cosparsity assumes that the signal is sparse after a possibly redundant transform. Meanwhile, an adaptive scheme is designed to keep the balance between mixed noise removal and detail preservation based on local variance. Finally, IRLSM and RACoSaMP are adopted to solve the objective function. Experimental results demonstrate that the proposed method is superior to conventional CS methods, like K-SVD and state-of-art method nonlocally centralized sparse representation(NCSR), in terms of both visual results and quantitative measures.

A new process monitoring method based on noisy time structure independent component analysis

Conventional process monitoring method based on fast independent component analysis(Fast ICA) cannot take the ubiquitous measurement noises into account and may exhibit degraded monitoring performance under the adverse effects of the measurement noises. In this paper, a new process monitoring approach based on noisy time structure ICA(Noisy TSICA) is proposed to solve such problem. A Noisy TSICA algorithm which can consider the measurement noises explicitly is firstly developed to estimate the mixing matrix and extract the independent components(ICs). Subsequently, a monitoring statistic is built to detect process faults on the basis of the recursive kurtosis estimations of the dominant ICs. Lastly, a contribution plot for the monitoring statistic is constructed to identify the fault variables based on the sensitivity analysis. Simulation studies on the continuous stirred tank reactor system demonstrate that the proposed Noisy TSICA-based monitoring method outperforms the conventional Fast ICA-based monitoring method.

Mixed Fault Diagnosing of Rolling Bearing Under Noise

In field of rolling bearing fault diagnosis, the sampled bearing vibration signals will be generally disturbed with noise. In noisy environment, the conventional blind source separation method is not good for diagnosing bearing faults. In this paper, wavelet de-noising method and blind source separation technology have been combined. In order to achieve fault diagnosis of rolling bearing, firstly wavelet soft threshold de-noising method has been applied on sampled signals. Then the better robust JADE algorithm has been applied in signals blind source separation. At last, vibration signals bearing inner and outer faults of have been analyzed in this paper, and the corresponding bearing faults have been diagnosed successfully. The proposed research methods provide a new way for diagnosing rolling bearing＇s mixed faults under noise

共模抑制的渐变结构高速差分电路设计

本文构建了一种拐角分段阻抗控制的渐变结构高速电路差分线,采用了HFSS三维电磁仿真软件对差分信号进行了建模分析。对混模S参数的仿真分析结果表明:对比平行结构的差分信号设计方式,所提出的添加GND孔渐变结构差分信号在10 GHz范围内差模转差模增大了58.7%,差模转共模减小了38.3%。通过对实物测试显示:添加GND孔渐变结构差分线的S_(d2d1)参数和S_(c2d1)仿真结果和实测结果具有很好的一致性,差分电路差模转共模得到了有效地抑制,对应的差分信号传输效率得到了提升。电场分布表明:渐变结构设计方法极大改善了差分电路转角位置电场分布,避免了差分电路传输线间电场聚集,使差分信号共模噪声和反射损耗减小,实现了高速差分信号传输的连续性。

基于非凸低秩张量分解和群稀疏总变分的高光谱混合噪声图像恢复

高光谱图像(Hyperspectral Image,HSI)在采集的过程中会被大量混合噪声污染,会影响遥感图像后续应用的性能,因此从混合噪声中恢复干净的HSI成为了重要的预处理过程。在本文中,提出了一种基于非凸低秩张量分解和群稀疏总变分正则化的高光谱混合噪声图像恢复模型;一方面,采用对数张量核范数来逼近HSI的低秩特性,可以利用高光谱数据固有的张量结构,同时减少对较大奇异值的收缩以保留图像更多细节特征;另一方面,采用群稀疏总变分正则化来增强HSI的空间稀疏性和相邻光谱间的相关性。并采用ADMM(Alternating Direction Multiplier Method)算法求解,实验证明该算法易于收敛。在模拟和真实的高光谱图像实验中,与其他方法相比,该方法在去除HSI混合噪声方面具有更好的性能。

面向电力设备红外图像的混合噪声去除方法研究

电力设备的红外图像在采集传输过程中,易受高斯噪声与脉冲噪声的影响从而破坏图像的真实信息,为满足图像处理过程对图像质量的要求,文中提出了一种针对红外图像混合噪声的滤除方法。首先利用三方加权稀疏编码(TWSC)模型有效滤除红外图像中的高斯噪声,然后利用图像结构纹理分解结合中值滤波算法实现剩余脉冲噪声的分离与去除,实现在滤除红外图像混合噪声的同时较好地保持图像的边缘结构信息,结合实例分析表明文中方法能够有效滤除噪声并获得较高的峰值信噪比(PSNR)与结构相似度(SSIM)。

基于全变分加权差正则的高光谱图像去噪算法

针对现有全变分模型在高光谱图像中出现的伪影、边缘结构消失等问题,文章提出一种增强型三维全变分加权差正则模型。首先,该模型并非直接将稀疏性强加于梯度映射本身,而是对梯度映射的基矩阵添加稀疏性约束。此外,与一般稀疏约束方法不同的是,为避免由l_(1)范数自身局限性带来的去噪不良影响,利用l_(1)范数与l_(2)范数的全变分加权差(简记为l_(1-2))分别对高光谱图像的空间域与光谱域施加稀疏约束。实验结果表明,该文提出的算法有效避免了伪影的产生以及图像细节丢失的问题,具有更优的去噪效果。

牵引异步电机气动和电磁混合噪声预测研究

高速列车牵引异步电机在高转速下的噪声主要由气动噪声和电磁噪声组成,且前者为主导成分。该研究为准确地预测该类型电机高转速下的气动和电磁混合噪声特性,首先建立了电机气动声源的仿真计算模型,包括基于计算流体动力学的流场计算和Lighthill声类比的声场计算;其次建立了电磁振动的计算模型,其中包含了Maxwell电磁场计算和基于模态叠加法的谐响应分析;最后通过有限元法和边界元法建立电机气动和电磁混合噪声的计算模型,最终得到电机混合噪声在各测点的总声压级和电机的声功率级,并与试验结果进行对比。结果表明,在4000 r/min和5600 r/min两个转速下的仿真计算的声功率级与试验值差距不超过0.6 dB(A),各测点总声压级与试验值接近,证明混合噪声的计算模型能够准确有效地预测牵引异步电机气动和电磁混合噪声。