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Xu, Pengcheng,Li, Xinxin,Yu, Haitao,Liu, Min,Li, Jungang IOP 2010 JOURNAL OF MICROMECHANICS AND MICROENGINEERING - Vol.20 No.11
<P>This paper reports MWCNT (multi-wall carbon nano-tube)-modified resonant micro-cantilever chemical sensors for detection of trinitrotoluene (TNT) vapor. The MWCNTs are pre-modified and then area-selectively self-assembled at the free-end gold pad of a micro-cantilever, in which a resonance-exciting heater and a signal-readout piezoresistive Wheatstone bridge are integrated. Featuring a high specific surface area, the MWCNTs are further functionalized with TNT-sensitive groups by grafting onto the sidewalls of the MWCNTs. To lower the non-specific absorption of water and other small organic molecules, the SiO<SUB>2</SUB> surface of the micro-cantilever was also pre-treated for hydrophobicity and oleophobicity by self-assembling a monolayer of heptadecafluorodecyltrimethoxysilane. The results of our sensing experiments have shown a capability to rapidly detect ppb-level TNT vapor, and a high specificity of the functionalized groups to TNT molecules. The experiment has also confirmed a good long-term stability in detecting sensitivity.</P>
A New Ambiguity Elimination Method for BSS Block Signals in Time Domain
Wei Zhao,Fengshan Wang,Yuehong Shen,Yuanyuan Wu,Zhigang Yuan,Pengcheng Xu,Pengcheng Xu,Yimin Wei,Wei Jian 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.11
This paper deals with the ambiguity problem of blind source separation (BSS) in the case where continuously received mixture signals are split in time and processed block by block. Due to the inherent permutation and scaling ambiguities of BSS, tying the separated components at each adjacent time blocks doesn’t recover the original source signals correctly in general. Inspired by the Permutation Method of reconstructing source signal blocks in time domain, a new ambiguity elimination approach is proposed in this paper. This method aims to concatenate the separated components in adjacent blocks by artificially setting contrast blocks for each adjacent time blocks. The core idea of this method is to utilize the associativity between components recovered from contrast blocks and corresponding adjacent blocks. Compared with Permutation Method, the main advantage of this new method consists in the fact that it is much more efficient in terms of separation quality and computational speed. Besides, a tradeoff can be adjusted between separation quality and computational speed by choosing different length of contrast blocks. Real-life experiments are performed to validate the performance of this method on the wireless communication system with two transmitting and receiving antennas.
Effect of curing conditions on mode-II debonding between FRP and concrete: A prediction model
Pengcheng Jiao,Sepehr Soleimani,Quan Xu,Lulu Cai,Yuanhong Wang 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.6
The rehabilitation and strengthening of concrete structures using Fiber-Reinforced Polymer (FRP) materials have been widely investigated. As a priority issue, however, the effect of curing conditions on the bonding behavior between FRP and concrete structures is still elusive. This study aims at developing a prediction model to accurately capture the mode-II interfacial debonding between FRP strips and concrete under different curing conditions. Single shear debonding experiments were conducted on FRP-concrete samples with respect to different curing time t and temperatures T. The J-integral formulation and constrained least square minimization are carried out to calibrate the parameters, i.e., the maximum slip s ̅ and stretch factor n. The prediction model is developed based on the cohesive model and Arrhenius relationship. The experimental data are then analyzed using the proposed model to predict the debonding between FRP and concrete, i.e., the interfacial shear stress-slip relationship. A Finite Element (FE) model is developed to validate the theoretical predictions. Satisfactory agreements are obtained. The prediction model can be used to accurately capture the bonding performance of FRP-concrete structures.
Shared Spatio-temporal Attention Convolution Optimization Network for Traffic Prediction
Pengcheng Li,Changjiu Ke,Hongyu Tu,Houbing Zhang,Xu Zhang 한국정보처리학회 2023 Journal of information processing systems Vol.19 No.1
The traffic flow in an urban area is affected by the date, weather, and regional traffic flow. The existing methodsare weak to model the dynamic road network features, which results in inadequate long-term prediction performance. To solve the problems regarding insufficient capacity for dynamic modeling of road network structuresand insufficient mining of dynamic spatio-temporal features. In this study, we propose a novel traffic flowprediction framework called shared spatio-temporal attention convolution optimization network (SSTACON). The shared spatio-temporal attention convolution layer shares a spatio-temporal attention structure, that isdesigned to extract dynamic spatio-temporal features from historical traffic conditions. Subsequently, the graphoptimization module is used to model the dynamic road network structure. The experimental evaluationconducted on two datasets shows that the proposed method outperforms state-of-the-art methods at all timeintervals.
Sequence Pulse Modulation for Voltage Balance in a Cascaded H-Bridge Rectifier
Xu Peng,Xiaoqiong He,Pengcheng Han,Xiaolan Lin,Zeliang Shu,Shibin Gao 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3
With the development of multilevel converters, cascaded single-phase H-bridge rectifiers (CHBRs) has become widely adopted in high-voltage high-power applications. In this study, sequence pulse modulation (SPM) is proposed for CHBRs. SPM is designed to balance the dc-link voltage and maintain the smooth changes of switch states. In contrast to phase disposition modulation, SPM balances the dc-link voltage even after removing the load of one submodule. The operation principle of SPM is deduced, and the unbalance degree of SPM is analyzed. All the proposed approaches are experimentally verified through a prototype of a four-module (nine-level) CHBR. Conclusions are drawn in accordance with the results of SPM and its imbalance degree analysis.
Pengcheng Han,Xiaoqiong He,Zhiqin Zhao,Haolun Yu,Yi Wang,Xu Peng,Zeliang Shu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1
This study proposes a new modulation strategy to deal with unbalanced output voltage that is based on three-levelneutral-point-clamped cascaded rectifiers. The fundament idea is to reallocate the value of the voltage levels generated by each ofthe modules on the basis of space vector pulse width modulation. This proposed modulation strategy can reduce the switchingfrequency while maintaining the mutual-module voltage balance. First, an analysis of unbalanced output voltage is reflected. Then a new modulation strategy is introduced in detail. Internal module capacitor voltages are balanced by the selection ofredundant vectors. Moreover, the voltage balance ability is calculated. Finally, the feasibility of this modulation strategy isverified through experimental results.
Han, Pengcheng,He, Xiaoqiong,Zhao, Zhiqin,Yu, Haolun,Wang, Yi,Peng, Xu,Shu, Zeliang The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1
This study proposes a new modulation strategy to deal with unbalanced output voltage that is based on three-level neutral-point-clamped cascaded rectifiers. The fundament idea is to reallocate the value of the voltage levels generated by each of the modules on the basis of space vector pulse width modulation. This proposed modulation strategy can reduce the switching frequency while maintaining the mutual-module voltage balance. First, an analysis of unbalanced output voltage is reflected. Then a new modulation strategy is introduced in detail. Internal module capacitor voltages are balanced by the selection of redundant vectors. Moreover, the voltage balance ability is calculated. Finally, the feasibility of this modulation strategy is verified through experimental results.
Nan Xu,Pengcheng Kan,Xiuhua Yao,Ping Yang,Jiwei Wang,Lei Xiang,Yu Zhu 한국미생물학회 2018 The journal of microbiology Vol.56 No.11
Acute ischaemic stroke (AIS) seriously affects patient quality of life. We explored the role of the intestinal microbiota on oxidative stress and autophagy in stroke, and Astragaloside IV (AS-IV) reversed the changes induced by intestinal microbiota. We determined the characteristics of the intestinal microbiota of AIS and transient ischaemic attack (TIA) patients by 16S sequencing and found that the structure and diversity of the intestinal microbiota in patients with AIS and TIA were significantly different from those in healthy subjects. Specifically, the abundance of genus Bifidobacterium, Megamonas, Blautia, Holdemanella, and Clostridium, content of homocysteine and triglyceride was increased significantly, thus it may be as a potential mechanism of AIS and TIA. Furthermore, germ-free mice were infused intracolonically with fecal supernatants of TIA and AIS with/without feed AS-IV for 12 weeks, and we found that the feces of AIS up-regulated the autophagy markers Beclin-1, light chain 3 (LC3)-II and autophagy-related gene (Atg)12, and the expression of reactive oxygen species (ROS) and NADPH oxidase 2/4 (NOX2/4), malondialdehyde (MDA), however, the expression of total antioxidant capacity (T-AOC) and activity of superoxide dismutase (SOD) and glutathione (GSH) was down-regulated in brain tissue, the content of homocysteine and free fatty acids (FFA) in serum of the mice. Meanwhile, AS-IV could reverse the above phenomenon, however, it does not affect the motor function of mice. AS-IV reversed these changes and it may be a potential drug for AIS therapeutics.
Sequence Pulse Modulation for Voltage Balance in a Cascaded H-Bridge Rectifier
Peng, Xu,He, Xiaoqiong,Han, Pengcheng,Lin, Xiaolan,Shu, Zeliang,Gao, Shibin The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3
With the development of multilevel converters, cascaded single-phase H-bridge rectifiers (CHBRs) has become widely adopted in high-voltage high-power applications. In this study, sequence pulse modulation (SPM) is proposed for CHBRs. SPM is designed to balance the dc-link voltage and maintain the smooth changes of switch states. In contrast to phase disposition modulation, SPM balances the dc-link voltage even after removing the load of one submodule. The operation principle of SPM is deduced, and the unbalance degree of SPM is analyzed. All the proposed approaches are experimentally verified through a prototype of a four-module (nine-level) CHBR. Conclusions are drawn in accordance with the results of SPM and its imbalance degree analysis.
Wu Peng,Xu Hongling,Xie Pengcheng 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.5
Aiming at the problem of ground penetrating radar image denoising, a new adaptive image denoising algorithm based on nonsubsampled Contourlet transform is proposed. The algorithm firstly performs nonsubsampled Contourlet transform to the noise image, to obtain the coefficients of each directional sub band and each scale, then, according to the energy of the coefficient, the denoising threshold value is adjusted adaptively. Simulation results show that, compared with the wavelet threshold denoising algorithm, the proposed algorithm can effectively remove the Gauss white noise in the image, improve the peak signal to noise ratio (PNSR), while preserving the edge details of the image, it can improve the PSNR value and reduce the Gibbs phenomenon.