ANALYSIS AND OPTIMIZATION OF AN EXPANDING ENERGY ABSORBER WITH VARIABLE THICKNESS DISTRIBUTION TUBE UNDER AXIAL DYNAMIC LOADING

Yanqing Wang,Shiming Wang,Lin Hou,Yong Peng 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.6

An expanding energy absorber with variable thickness distribution tube is proposed and studied in this work. At first, a uniform thickness tube structure finite element (FE) model was developed and then verified by the results of an impact test. The parametric study found that outer obliquity angle β and inner obliquity angle γ have positive influence on initial peak force (Fp). While as axial distribution ratio l less than 0.1, the l has significant positive effect on Fp. The non-monotonicity of specific energy absorption (SEA) with design parameters of β and γ was found. Increasing the parameter l could obviously improve the SEA. To obtain the optimal design, an integrated optimization methodology was applied. The Pareto fronts show that there is a lot of room for improvement of original design. The optimal compromising solution increased the SEA by 12.60 % with Fp decreased by 14.24 kN comparing with that of original design. At last, the optimization result were verified. The study stated that the proposed variable thickness distribution tube of expanding energy absorber is conducive to improving the crashworthiness of rail vehicles.

A Novel Approach of Feature Extraction for Analog Circuit Fault Diagnosis Based on WPD-LLE-CSA

Wang, Yuehai,Ma, Yuying,Cui, Shiming,Yan, Yongzheng The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

The rapid development of large-scale integrated circuits has brought great challenges to the circuit testing and diagnosis, and due to the lack of exact fault models, inaccurate analog components tolerance, and some nonlinear factors, the analog circuit fault diagnosis is still regarded as an extremely difficult problem. To cope with the problem that it's difficult to extract fault features effectively from masses of original data of the nonlinear continuous analog circuit output signal, a novel approach of feature extraction and dimension reduction for analog circuit fault diagnosis based on wavelet packet decomposition, local linear embedding algorithm, and clone selection algorithm (WPD-LLE-CSA) is proposed. The proposed method can identify faulty components in complicated analog circuits with a high accuracy above 99%. Compared with the existing feature extraction methods, the proposed method can significantly reduce the quantity of features with less time spent under the premise of maintaining a high level of diagnosing rate, and also the ratio of dimensionality reduction was discussed. Several groups of experiments are conducted to demonstrate the efficiency of the proposed method.

Cyano-Substituted Head-to-Head Polythiophenes: Enabling High-Performance n-Type Organic Thin-Film Transistors

Wang, Hang,Huang, Jun,Uddin, Mohammad Afsar,Liu, Bin,Chen, Peng,Shi, Shengbin,Tang, Yumin,Xing, Guichuan,Zhang, Shiming,Woo, Han Young,Guo, Han,Guo, Xugang American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.10

<P>Polythiophenes, built on the electron-rich thiophene unit, typically possess high-lying energy levels of the lowest unoccupied molecular orbitals (LUMOs) and show hole-transporting properties. In this study, we develop a series of n-type polythiophenes, <B>P1</B>-<B>P3</B>, based on head-to-head-linked 3,3′-dialkoxy-4,4′-dicyano-2,2′-bithiophene (BTCNOR) with distinct side chains. The BTCNOR unit shows not only highly planar backbone conformation enabled by the intramolecular noncovalent sulfur-oxygen interaction but also significantly suppressed LUMO level attributed to the cyano-substitution. Hence, all BTCNOR-based polymer semiconductors exhibit low-lying LUMO levels, which are ∼1.0 eV lower than that of regioregular poly(3-hexylthiophene) (rr-P3HT), a benchmark p-type polymer semiconductor. Consequently, all of the three polymers can enable unipolar n-type transport characteristics in organic thin-film transistors (OTFTs) with low off-currents (<I>I</I><SUB>off</SUB>s) of 10<SUP>-10</SUP>-10<SUP>-11</SUP> A and large current on/off ratios (<I>I</I><SUB>on</SUB>/<I>I</I><SUB>off</SUB>s) at the level of 10<SUP>6</SUP>. Among them, polymer <B>P2</B> with a 2-ethylhexyl side chain offers the highest film ordering, leading to the best device performance with an excellent electron mobility (μ<SUB>e</SUB>) of 0.31 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> in off-center spin-cast OTFTs. To the best of our knowledge, this is the first report of n-type polythiophenes with electron mobility comparable to the hole mobility of the benchmark p-type rr-P3HT and approaching the electron mobility of the most-studied n-type polymer, poly(naphthalene diimide-<I>alt</I>-bithiophene) (i.e., N2200). The change of charge carrier polarity from p-type (rr-P3HT) to n-type (<B>P2</B>) with comparable mobility demonstrates the obvious effectiveness of our structural modification. Adoption of <I>n</I>-hexadecyl (<B>P1</B>) and 2-butyloctyl (<B>P3</B>) side chains leads to reduced film ordering and results in 1-2 orders of magnitude lower μ<SUB>e</SUB>s, showing the critical role of side chains in optimizing device performance. This study demonstrates the unique structural features of head-to-head linkage containing BTCNOR for constructing high-performance n-type polymers, i.e., the alkoxy chain for backbone conformation locking and providing polymer solubility as well as the strong electron-withdrawing cyano group for lowering LUMO levels and enabling n-type performance. The design strategy of BTCNOR-based polymers provides useful guidelines for developing n-type polythiophenes.</P> [FIG OMISSION]</BR>

Experimental study of moment redistribution and load carrying capacity of externally prestressed continuous composite beams

Shiming Chen,Yuanlin Jia,Xindi Wang 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.5

A comparative experimental study of prestressed continuous steel-concrete composite beams was carried out. Two continuous composite beams were tested, one of which was plain continuous steelconcrete composite beam, while the other was a composite beam prestressed with external tendons. Cracking behavior and the load carrying capacity of the beams were investigated experimentally. Full plasticity was developed in the mid-span section each beam, the maximum moments attained at the internal support sections however were governed by local buckling which was related to the slenderness of composite section. It was found that in hogging moment regions, the ultimate resistance of an externally prestressed composite beam would be governed by either distortional lateral buckling or local buckling, or interactive mode of these two buckling patterns. The results show that exerting prestressing on a continuous composite beam with external tendons will increase the extent of internal force and moment redistribution in the beam. The influences of local and distortional buckling on the behaviors of the composite continuous beams are discussed. The Moment redistribution and the load carrying capacity of the prestressed continuous composite beams are evaluated, and it is found that at the ultimate state, the moment redistribution in the prestrssed continuous composite beams is greater than that in non-prestressed composite beams.

Lightweight Single Image Super-Resolution Convolution Neural Network in Portable Device

( Jin Wang ),( Yiming Wu ),( Shiming He ),( Pradip Kumar Sharma ),( Xiaofeng Yu ),( Osama Alfarraj ),( Amr Tolba ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.11

Super-resolution can improve the clarity of low-resolution (LR) images, which can increase the accuracy of high-level compute vision tasks. Portable devices have low computing power and storage performance. Large-scale neural network super-resolution methods are not suitable for portable devices. In order to save the computational cost and the number of parameters, Lightweight image processing method can improve the processing speed of portable devices. Therefore, we propose the Enhanced Information Multiple Distillation Network (EIMDN) to adapt lower delay and cost. The EIMDN takes feedback mechanism as the framework and obtains low level features through high level features. Further, we replace the feature extraction convolution operation in Information Multiple Distillation Block (IMDB), with Ghost module, and propose the Enhanced Information Multiple Distillation Block (EIMDB) to reduce the amount of calculation and the number of parameters. Finally, coordinate attention (CA) is used at the end of IMDB and EIMDB to enhance the important information extraction from Spaces and channels. Experimental results show that our proposed can achieve convergence faster with fewer parameters and computation, compared with other lightweight super-resolution methods. Under the condition of higher peak signal-to-noise ratio (PSNR) and higher structural similarity (SSIM), the performance of network reconstruction image texture and target contour is significantly improved.

Experimental study of moment redistribution and load carrying capacity of externally prestressed continuous composite beams

Chen, Shiming,Jia, Yuanlin,Wang, Xindi Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.5

A comparative experimental study of prestressed continuous steel-concrete composite beams was carried out. Two continuous composite beams were tested, one of which was plain continuous steel-concrete composite beam, while the other was a composite beam prestressed with external tendons. Cracking behavior and the load carrying capacity of the beams were investigated experimentally. Full plasticity was developed in the mid-span section each beam, the maximum moments attained at the internal support sections however were governed by local buckling which was related to the slenderness of composite section. It was found that in hogging moment regions, the ultimate resistance of an externally prestressed composite beam would be governed by either distortional lateral buckling or local buckling, or interactive mode of these two buckling patterns. The results show that exerting prestressing on a continuous composite beam with external tendons will increase the extent of internal force and moment redistribution in the beam. The influences of local and distortional buckling on the behaviors of the composite continuous beams are discussed. The Moment redistribution and the load carrying capacity of the prestressed continuous composite beams are evaluated, and it is found that at the ultimate state, the moment redistribution in the prestrssed continuous composite beams is greater than that in non-prestressed composite beams.

The Assessment of Arsenic Availability in Soils Using the In-Situ Diffusion Gradients in Thin Films Technique (dgt) - A Comparison Study of Dgt and the Typical Extraction Methods

Jinjin Wang,Lingyu Bai,Xibai Zeng,Shiming Su,Ran Duan,Yuanyuan Sun 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

A Novel Approach of Feature Extraction for Analog Circuit Fault Diagnosis Based on WPD-LLE-CSA

Yuehai Wang,Yuying Ma,Shiming Cui,Yongzheng Yan 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

The rapid development of large-scale integrated circuits has brought great challenges to the circuit testing and diagnosis, and due to the lack of exact fault models, inaccurate analog components tolerance, and some nonlinear factors, the analog circuit fault diagnosis is still regarded as an extremely difficult problem. To cope with the problem that it’s difficult to extract fault features effectively from masses of original data of the nonlinear continuous analog circuit output signal, a novel approach of feature extraction and dimension reduction for analog circuit fault diagnosis based on wavelet packet decomposition, local linear embedding algorithm, and clone selection algorithm (WPD-LLE-CSA) is proposed. The proposed method can identify faulty components in complicated analog circuits with a high accuracy above 99%. Compared with the existing feature extraction methods, the proposed method can significantly reduce the quantity of features with less time spent under the premise of maintaining a high level of diagnosing rate, and also the ratio of dimensionality reduction was discussed. Several groups of experiments are conducted to demonstrate the efficiency of the proposed method.

Block Sparse Low-rank Matrix Decomposition based Visual Defect Inspection of Rail Track Surfaces

( Linna Zhang ),( Shiming Chen ),( Yigang Cen ),( Yi Cen ),( Hengyou Wang ),( Ming Zeng ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.12

Low-rank matrix decomposition has shown its capability in many applications such as image in-painting, de-noising, background reconstruction and defect detection etc. In this paper, we consider the texture background of rail track images and the sparse foreground of the defects to construct a low-rank matrix decomposition model with block sparsity for defect inspection of rail tracks, which jointly minimizes the nuclear norm and the 2-1 norm. Similar to ADM, an alternative method is proposed in this study to solve the optimization problem. After image decomposition, the defect areas in the resulting low-rank image will form dark stripes that horizontally cross the entire image, indicating the preciselocations of the defects. Finally, a two-stage defect extraction method is proposed to locate the defect areas. The experimental results of the two datasets show that our algorithm achieved better performance compared with other methods.

Cyano-substituted benzochalcogenadiazole-based polymer semiconductors for balanced ambipolar organic thin-film transistors

Shi, Shengbin,Wang, Hang,Chen, Peng,Uddin, Mohammad Afsar,Wang, Yuxi,Tang, Yumin,Guo, Han,Cheng, Xing,Zhang, Shiming,Woo, Han Young,Guo, Xugang The Royal Society of Chemistry 2018 Polymer chemistry Vol.9 No.28

<P>Due to their high-lying lowest unoccupied molecular orbitals (LUMOs), π-conjugated polymers based on benzothiadiazole and its derivatives typically are p-type. We report here the successful development of two narrow bandgap, ambipolar donor-acceptor copolymers, PDCNBT2T and PDCNBSe2T, which are based on new cyano-substituted strong electron acceptors, 4,7-dibromo-5,6-dicyano-2,1,3-benzothiadiazole (DCNBT) and 4,7-dibromo-5,6-dicyano-2,1,3-benzoselenadiazole (DCNBSe), respectively. Compared to their polymer analogues with fluorine substituents, the LUMO was lowered by a big margin of <I>ca.</I> 0.6 eV and the bandgap was reduced by 0.2-0.3 eV for the cyano-substituted polymers. Therefore, the cyano-substituted benzothiadiazole polymers showed very low-lying LUMO levels of <I>ca.</I> 4.3 eV. Benefiting from their narrow bandgaps of 1.1-1.2 eV and appropriately positioned LUMO levels, both polymers exhibit well balanced ambipolar transport characteristics in organic thin-film transistors, which differ from the p-type dominating transport properties of their fluorinated polymer analogues. A balanced hole/electron mobility of 0.59/0.47 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> was achieved for polymer PDCNBT2T, and a reduced hole/electron mobility of 0.018/0.014 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> was observed for the benzoselenadiazole-based PDCNBSe2T due to its lower crystallinity. These results show that the electron mobility can be enhanced by approximately two orders <I>versus</I> the electron mobility of the previously reported 4,7-di(thiophen-2-yl)-5,6-dicyano-2,1,3-benzothiadiazole-based polymer. This improvement was achieved by using the new acceptor units without additional electron-rich thiophene flanks, which allow a higher degree of freedom in selecting the donor co-unit and more effective tuning of energy levels of frontier molecular orbitals.</P>