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Near-Field Source Localization Using Spherical Microphone Arrays

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Chinese Journal of Electronics 2016年第1期25卷 159-166页

作者： HUANG Qinghua ZHANG Guangfei LIU Kai key laboratory of specialty Fiber optics and optical access networks Shanghai University

A new method is proposed for joint range and bearing(azimuth and elevation) estimation of multiple near-field acoustic sources using observations collected by a spherical microphone array. First, Spherical Fourier transform(SFT) is used to construct the array signal model in the spherical harmonics domain to decouple range and bearing information. Then the relation among the spherical harmonics of three adjacent degrees is exploited to build the recursive relationship of the signal subspace. Using Eigenvalue decomposition(EVD), bearings are estimated based on the eigenvalues and simultaneously the steering matrix can be represented by the signal ***, range is estimated using the energy ratios of the elements of the steering matrix in the spherical harmonics domain. The algorithm can avoid parameter pairing and multi-dimensional searching. It has lower computational complexity than that of the Multiple signal classification(MUSIC) method. The performance is evaluated by Monte-Carlo simulations and the estimation root meansquare errors are compared to the corresponding CramerRao bounds(CRBs) and those of MUSIC range estimates,which demonstrate the validity of the proposed algorithm.

关键词： Spherical microphone array Source localization Near-field Spherical Fourier transform(SFT) Spherical harmonics

DOA Estimation Using Block Variational Sparse Bayesian Learning

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Chinese Journal of Electronics 2017年第4期26卷 768-772页

作者： HUANG Qinghua ZHANG Guangfei FANG Yong key laboratory of specialty Fiber optics and optical access networks Shanghai University

In Direction-of-arrival(DOA) estimation,the real-valued sparse Bayesian algorithm degrades the estimation performance by decomposing the complex value into real and imaginary components and combining them independently. We directly use complex probability density functions to model the noise and complex-valued sparse direction weights. Based on the Multiple measurement vectors(MMV), block sparse structure for the direction weights is integrated into the variational Bayesian learning to provide accurate source direction estimates. The proposed algorithm can be used for arbitrary array geometries and does not need the prior information of the incident signal number. Simulation results demonstrate the better performance of the proposed method compared with the real-valued sparse Bayesian algorithm, the Orthogonal matching pursuit(OMP) and l1 norm based complexvalued methods.

关键词： Direction-of-arrival estimation Varia tional Bayesian learning Sparse recovery Multiple mea surement vectors Block sparse structure

Scattering of Circularly Polarized Terahertz Waves on a Graphene Nanoantenna

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Chinese Physics Letters 2016年第2期33卷 129-132页

作者：刘志坤谢亚楠耿莉潘登科宋盼 key laboratory of specialty Fiber optics and optical access networks Shanghai University

We present a surface current method to model the graphene rectangular nanoantenna scattering in the terahertz band with Comsol. Compared with the equivalent thin slab method, the results obtained by the surface current method are more accurate and efficient. Then the electromagnetic scattering of circularly polarized terahertz waves on graphene nanoantennas is numerically analyzed by utilizing the surface current method. The depen- dences of the antenna resonant frequency with the circularly polarized wave on width and length are consistent with those for the linear polarized waves. These results are proved to be useful to design et^cient nanoantennas in terahertz wireless communications.

关键词： of in Scattering of Circularly Polarized Terahertz Waves on a Graphene Nanoantenna is SCM THz on for

Distributed differential space-time coding for asynchronous two-way relaying networks with Nakagami-m fading

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The Journal of China Universities of Posts and Telecommunications 2014年第6期21卷 17-23,36页

作者： QIAN Min-jie JIN Yan-liang WU Zhuo key laboratory of specialty Fiber optics and optical access networks Shanghai University

A signal detection scheme was proposed for two-way relaying networks（TWRNs） using distributed differential space-time coding（DDSTC） under imperfect synchronization. Unlike most existing work perfect with synchronization assumed, a relative delay between the signals transmitted from both sources to the relay was considered. Since perfect channel state information（CSI） is difficult to be acquired in fast fading, the scenarios and computation complexity will be increased especially when there appear multiple relays, CSI is assumed unavailable at all nodes. Therefore, the article proposes a differential signal detection scheme based on estimating and cancelling the imperfect synchronization component in the received signal at the two source nodes, followed by a least square（LS） decoder. Simulations, using the Nakagami-m fading channel due to its versatile statistical distribution property, show that the proposed scheme for both source nodes are effective in suppressing the inter-symbol interference（ISI） caused by imperfect synchronization while neither the source nodes nor the relay nodes have any knowledge of CSI.

关键词： TWRNs DDSTC Nakagami-m fading imperfect synchronization

Piezoelectric transducer parameter selection for exciting a single mode from multiple modes of Lamb waves

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Chinese Physics B 2011年第9期20卷 262-270页

作者：张海燕于建波 School of Communication and Information Engineering Key Laboratory of Specialty Fiber Optics and Optical Access NetworksShanghai University

Excitation and propagation of Lamb waves by using rectangular and circular piezoelectric transducers surface- bonded to an isotropic plate are investigated in this work. Analytical stain wave solutions are derived for the two transducer shapes, giving the responses of these transducers in Lamb wave fields. The analytical study is supported by a numericM simulation using the finite element method. Symmetric and antisymmetric components in the wave propagation responses are inspected in detail with respect to test parameters such as the transducer geometry, the length and the excitation frequency. By placing only one piezoelectric transducer on the top or the bottom surface of the plate and weakening the strength of one mode while enhancing the strength of the other modes to find the centre frequency, with which the peak wave amplitude ratio between the SO and A0 modes is maximum, a single mode excitation from the multiple modes of the Lamb waves can be achieved approximately. Experimental data are presented to show the validity of the analyses. The results are used to optimize the Lamb wave detection system.

关键词： Lamb waves parameter selection analytical stain wave solutions single mode

A time reversal damage imaging method for structure health monitoring using Lamb waves

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Chinese Physics B 2010年第11期19卷 448-455页

作者：张海燕曹亚萍孙修立陈先华于建波 School of Communication and Information Engineering Key Laboratory of Specialty Fiber Optics and Optical Access NetworksShanghai University

This paper investigates the Lamb wave imaging method combining time reversal for health monitoring of a metallic plate structure. The temporal focusing effect of the time reversal Lamb waves is investigated theoretically. It demonstrates that the focusing effect is related to the frequency dependency of the time reversal operation. Numerical simulations are conducted to study the time reversal behaviour of Lamb wave modes under broadband and narrowband excitations. The results show that the reconstructed time reversed wave exhibits close similarity to the reversed narrowband tone burst signal validating the theoretical model. To enhance the similarity, the cycle number of the excited signal should be increased. Experiments combining finite element model are then conducted to study the imaging method in the presence of damage like hole in the plate structure. In this work, the time reversal technique is used for the recompression of Lamb wave signals. Damage imaging results with time reversal using broadband and narrowband excitations are compared to those without time reversal. It suggests that the narrowband excitation combined time reversal can locate and determine the size of structural damage more precisely, but the cycle number of the excited signal should be chosen reasonably.

关键词： Lamb wave time reversal damage imaging structure health monitoring

Novel scheme enabling broadcast signal transmission in WDM passive optical network

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Chinese optics Letters 2011年第4期9卷 14-17页

作者：马雪娇甘朝钦 key laboratory of specialty Fiber optics and optical access Shanghai University

We present a novel method for providing broadcast signal transmission in a wavelength division multiplexing passive optical network （WDM-PON）. An unmodulated optical carrier for downstream transmission and a pair of unmodulated single-side band subcarriers are utilized for broadcast delivery and upstream transmission, respectively. System performance at 2.5-Gb/s down/upstream and 2.5-Gb/s broadcast transmission is also investigated.

关键词： Carrier communication Fiber optic networks Light transmission Multiplexing equipment optical communication Wavelength division multiplexing

Fabrication of optical fiber sensor based on double-layer SU-8 diaphragm and the partial discharge detection

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Optoelectronics Letters 2015年第1期11卷 61-64页

作者：商娅娜倪晴燕丁丁陈娜王廷云 key laboratory of specialty Fiber optics and optical access networks Shanghai University

In this paper, a partial discharge detection system is proposed using an optical fiber Fabry-Perot(FP) interferometric sensor, which is fabricated by photolithography. SU-8 photoresist is employed due to its low Young's modulus and potentially high sensitivity for ultrasound detection. The FP cavity is formed by coating the fiber end face with two layers of SU-8 so that the cavity can be controlled by the thickness of the middle layer of SU-8. Static pressure measurement experiments are done to estimate the sensing performance. The results show that the SU-8 based sensor has a sensitivity of 154.8 nm/kP a, which is much higher than that of silica based sensor under the same condition. Moreover, the sensor is demonstrated successfully to detect ultrasound from electrode discharge.

关键词： envelope chromatic modulator wideband photonic receiver filtering impulse optics narrow

One-dimensional film-micro-cavity structure design for an asymmetrical interleaver filter

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Optoelectronics Letters 2010年第2期6卷 85-88页

作者：于帅张娟 key laboratory of specialty Fiber optics and optical access networks Shanghai University

Based on the theory of one-dimensional photonic crystal,an asymmetrical interleaver filter composed of thin-film glass cavities is *** thin-film glass cavities are cascaded in the *** cavity is formed by evaporating several layers of reflecting films on two surfaces of the glass *** with other proposed structures,this interleaver filter is very simple and easy to realize,and it has flat passband and stopband.A design example of a 50 GHz interleaver filter with the duty cycle of 1:5 is *** influence of the structural parameters of each reflecting film(including the glass cavity) on the spectral performance is *** the design results with duty cycles of 1:3 and 1:4 are also shown and analyzed.

关键词：一维光子晶体结构设计交织器非对称微腔电影薄膜玻璃理论设计