Shanghai Radio Equipment Institute

Shanghai, China

Shanghai Radio Equipment Institute

Shanghai, China
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Yuan J.,Shanghai Radio Equipment Institute | Wang Y.,Xi'an Jiaotong University | Peng Y.,Xi'an Jiaotong University | Wei C.,Shanghai Radio Equipment Institute
Mechanical Systems and Signal Processing | Year: 2017

Due to the nonobvious symptoms contaminated by a large amount of background noise, it is challenging to beforehand detect and predictively monitor the weak faults for machinery security assurance. Multiwavelets can act as adaptive non-stationary signal processing tools, potentially viable for weak fault diagnosis. However, the signal-based multiwavelets suffer from such problems as the imperfect properties missing the crucial orthogonality, the decomposition distortion impossibly reflecting the relationships between the faults and signatures, the single objective optimization and independence for fault prognostic. Thus, customized standard multiwavelets are proposed for weak fault detection and health degradation monitoring, especially the weak fault signature quantitative identification. First, the flexible standard multiwavelets are designed using the construction method derived from scalar wavelets, seizing the desired properties for accurate detection of weak faults and avoiding the distortion issue for feature quantitative identification. Second, the multi-objective optimization combined three dimensionless indicators of the normalized energy entropy, normalized singular entropy and kurtosis index is introduced to the evaluation criterions, and benefits for selecting the potential best basis functions for weak faults without the influence of the variable working condition. Third, an ensemble health indicator fused by the kurtosis index, impulse index and clearance index of the original signal along with the normalized energy entropy and normalized singular entropy by the customized standard multiwavelets is achieved using Mahalanobis distance to continuously monitor the health condition and track the performance degradation. Finally, three experimental case studies are implemented to demonstrate the feasibility and effectiveness of the proposed method. The results show that the proposed method can quantitatively identify the fault signature of a slight rub on the inner race of a locomotive bearing, effectively detect and locate the potential failure from a complicated epicyclic gear train and successfully reveal the fault development and performance degradation of a test bearing in the lifetime. © 2017 Elsevier Ltd

Chen P.,National Key Laboratory of Science and Technology on Reactor System Design Technology | Chen P.,CAS Institute of Electronics | Chen P.,University of Chinese Academy of Sciences | Liu L.,China Academy of Space Technology | And 6 more authors.
Remote Sensing | Year: 2017

Modulation model of radar backscatters is an important topic in the remote sensing of oceanic internal wave by synthetic aperture radar (SAR). Previous studies related with the modulation models were analyzed mainly based on the hypothesis that ocean surface waves are Gaussian distributed. However, this is not always true for the complicated ocean environment. Research has showed that the measurements are usually larger than the values predicted by modulation models for the high frequency radars (X-band and above). In this paper, a new modulation model was proposed which takes the third-order statistics of the ocean surface into account. It takes the situation into consideration that the surface waves are Non-Gaussian distributed under some conditions. The model can explain the discrepancy between the measurements and the values calculated by the traditional models in theory. Furthermore, it can accurately predict the modulation for the higher frequency band. The model was verified by the experimental measurements recorded in a wind wave tank. Further discussion was made about applicability of this model that it performs better in the prediction of radar backscatter modulation compared with the traditional modulation model for the high frequency band radar or under lager wind speeds. © 2017 by the authors.

Zhang L.,Shanghai JiaoTong University | Wang H.,Shanghai JiaoTong University | Qi J.,CAS Shanghai Advanced Research Institute | Wu Y.,Shanghai JiaoTong University | Peng S.,Shanghai Radio Equipment Institute
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | Year: 2015

Colloidal carbon microspheres were prepared from aqueous glucose solutions by hydrothermal synthesis procedure, and then submicron core/shell structured precursors of carbon spheres/ ZrW2O8 were prepared by sol-gel method with colloidal carbon microspheres as templates to provide reactive surfaces for facilitating the deposition of nano-sized ZrW2O8 particles. Finally, hollow spheres of ZrW2O8 can be produced by calcinating the precursors at 610℃ for 10 h to remove the colloidal carbon sphere templates. The final spheres ZrW2O8 with an average size about 3 μm were proved to be composed of single phase nano-sized ZrW2O8 particles. Their density was measured to be 2.8 g/cm3, ca 45% lower than that of ZrW2O8. Along with the density, FTIR and TG-DTA results also indicate the existence of hollow structure of the spheres ZrW2O8, of which the thermal expansion coefficient was -11.4×10-6 K-1 in the temperature range from room temperature to 200℃, a little higher than the theoretical value. © All right reserved.

Huang Q.,Shanghai University of Electric Power | Wu B.H.,Shanghai Maritime University | Gao L.,Shanghai Radio Equipment Institute | Guo D.M.,Shanghai Radio Equipment Institute | Tong M.L.,Shanghai University of Electric Power
Advanced Materials Research | Year: 2014

Phased array radar (PAR) used for space exploration is a potential technique in many fields such as space target detection, tracking and orbit determination. Nevertheless, it may take a long time for PAR to detect fast-moving targets due to the large searching scope. This paper introduces the compressive sensing (CS) theory used in phased array tracking radar. A fast target searching method and angle-range imaging algorithm based on CS theory are presented, which can reduce the scanning time, sampling and processing data storage. The results of numerical simulation indicate that the proposed method using fewer scanning times can retain almost equal imaging and resolution quality compared to conventional method, which can also ensure the signal-to-noise ratio (SNR) of target detection. © (2014) Trans Tech Publications, Switzerland.

Yuan J.,Xi'an Jiaotong University | Yuan J.,Shanghai Radio Equipment Institute | He Z.,Xi'an Jiaotong University | Zi Y.,Xi'an Jiaotong University | Wei Y.,Shanghai Radio Equipment Institute
Mechanical Systems and Signal Processing | Year: 2013

The essence of wavelet transforms is a similar measurement between the signal and the wavelet basis functions. Thus, the construction and selection of the proper wavelet basis functions similar to the fault feature and possessing good properties such as vanishing moments have vital importance to the effective fault diagnosis. In this paper, the construction of lifting-based adaptive multiwavelets with various vanishing moments and the selection rules for different mechanical fault detection are proposed. On the basis of the fixed cubic Hermite multiwavelets, lifting schemes are adopted to construct new changeable multiwavelets with diverse vanishing moments. Then, the defined local spectral entropy minimization rules are proposed to determine the optimum multiwavelets providing the proper vanishing moments, classified into the typical shaft faults, gear faults and rolling bearing faults. The proposed method is applied to incipient fault diagnosis of rolling bearing and gearbox fault diagnosis of rolling mill to verify its effectiveness and feasibility in comparison with different wavelet transforms and spectral kurtosis. The results show that the proposed method can act as a promising tool for mechanical fault detection. © 2013 Elsevier Ltd.

Cao Y.,Tongji University | Wei Z.,Tongji University | Wu C.,Tongji University | Li H.,Tongji University | And 2 more authors.
Optics Express | Year: 2012

In this paper the transmission properties of a metal plate perforated with a triangular array of air holes is investigated. We find that the normalized transmittivity exceeds unity within a certain frequency range under normal incidence of a Gaussian beam. Calculations and experiments indicate that the phenomenon results from the collimation effect which only occurs inside the complete bandgap of surface resonance states on the perforated metal plate. The findings present a simple approach for beam collimation. © 2012 Optical Society of America.

Li L.,Shanghai Radio Equipment Institute | Liang Z.,Shanghai Radio Equipment Institute | Liang Z.,Science and Technology on Electromagnetic Scattering Laboratory | Gao W.,Shanghai Radio Equipment Institute | And 2 more authors.
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) | Year: 2015

A novel method of simulating the sea surface was proposed in this paper, which employing the Bragg structures to control the mono-static reflectivity coefficient at certain angles, namely, the grazing angles is typically from 50° to 30°. The compared results between the simulated and measured data showed that the mean square error (MSE) is less than 3dB, which meant that the new method was very useful. © 2015 IEEE.

Lu M.,Shanghai Radio Equipment Institute | Tan Z.,Shanghai Radio Equipment Institute | Song K.,Shanghai Radio Equipment Institute
Proceedings of 3rd Asia-Pacific Conference on Antennas and Propagation, APCAP 2014 | Year: 2014

Long-time coherent integration method can improve the detection performance of weak targets, what just increase the residence time rather than increasing the power-aperture product. According to the radial velocity of the moving object, the coupling relationship between the walking range and Doppler frequency, an improved Radon-Fourier transform is proposed to achieve a two-dimensional space-time echo projected to low-dimensional parameter space, establishing a parameter space that covered the possible of radial velocity and range. Then the echo pulses are projected into this space, forming a "focus" of the peak, the coherent integration time to achieve the target of the "focus" process. Simulation results show the effectiveness of this method. © 2014 IEEE.

Cao Y.,Shanghai Radio Equipment Institute | Cao Y.,Shanghai Key Laboratory of Electromagnetic Environmental Effects for Aerospace Vehicle | Wang X.,Shanghai Radio Equipment Institute | Wang X.,Shanghai Key Laboratory of Electromagnetic Environmental Effects for Aerospace Vehicle
Progress in Electromagnetics Research Symposium | Year: 2014

Metamaterials (MMs) refer to a class of artificially engineered structures comprised of electric/magnetic resonant building blocks much smaller than the operating wavelength. The extraordinary electromagnetic responses of MMs, not available for naturally occurring materials, have attracted intensive investigations on the underlying physics as well as related applications. In recent years, MMs-based antennas are widely studied and proved to have great potential in improving the radiation performance. In this paper, a MMs-based Febry-Perot cavity antenna with wide viewing angle is proposed about 14 GHz. The antenna consists of a high-impedance surface which works as an artificial magnetic conductor (AMC) at resonance frequency and a partially reflective surface (PRS). The AMC loading contributes to the low-profile and high-gain property of the antenna, as the AMC ground plane gives a near-zero phase shift in contrast to conventional metal sheet ground plane. The lateral size of the antenna is only about 3λ × 0:6λ; and the thickness is about λ/5. Metal walls surrounding the limited aperture are introduced to prevent the leakage of cavity mode and improve the radiation pattern, which also protects the antenna from external electromagnetic environment. The MMs-based high-gain antenna has a broad beam width in H-plane, which may be applied in ETC and RFID system.

Lu M.,Shanghai Radio Equipment Institute | Tan Z.,Shanghai Radio Equipment Institute | Zhu J.,Shanghai Radio Equipment Institute
WIT Transactions on Information and Communication Technologies | Year: 2014

Radio Frequency Fingerprinting (RFF) can be used to uniquely identify a transceiver. The features of RFF can be extracted either from transient signals or stationary signals. Transient signals contain more nonlinear characteristics that can distinguish between individual differences. In this paper, a novel method is proposed to extract the features from transient signals for RFF recognition. The instantaneous phase variance is used to detect transient signal. The integral envelop method is presented to enhance the signals difference between individual. Validation using interphone signals has resulted in a success rate above 94.2%. The novel method supports various device authentication schemes in the wireless domain. © 2014 WIT Press.

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