2012
2012
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Record 241 of
Title:Synthesis of two benzo[1,2-b:3,4-b′]dithiophene-based conjugated polymers with different side chains and their applications in photovoltaic devices
Author(s):Qu, Bo(1); Yang, Hongsheng(1); Tian, Di(2); Liu, Hongli(2); Cong, Zhiyuan(2); Gao, Chao(2,3); Chen, Zhijian(1); Xiao, Lixin(1); Gao, Zhi(1); Wei, Wei(3,4); Gong, Qihuang(1)Source: Synthetic Metals Volume: 162 Issue: 23 DOI: 10.1016/j.synthmet.2012.09.009 Published: December 2012Abstract:Two D-A conjugated polymers (named PBDTC6DBT and PBDTC 10DBT) with benzo[1,2-b:3,4-b′]dithiophene (BDT) as donor and 4,7-dithiophen-2,1,3-benzothiadiazole (DBT) as acceptor, were designed and synthesized. PBDTC6DBT and PBDTC10DBT have hexyl and decyl as side chains in the DBT units, respectively. The polymers were characterized by spectroscopic (NMR and UV-vis) methods, GPC, DSC and cyclic voltammetry. In order to study the photovoltaic properties of the two conjugated polymers, photovoltaic devices with the configuration of ITO/poly(3,4- ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/polymer:[6,6]-phenyl C61-butyric acid methyl ester (PC61BM)/LiF/Al, were fabricated, in which PBDTC6DBT or PBDTC10DBT acted as electron donor in active layers. According to the experimental data, when the blend ratio of PBDTC6DBT and PC61BM reached 1:2, the best photovoltaic properties among the PBDTC6DBT-based devices were obtained, and the open-circuit voltage, the short-circuit current density and the power conversion efficiency were measured to be 0.63 V, 6.18 mA/cm 2 and 1.86%, respectively. As to PBDTC10DBT-based devices, the maximum of power conversion efficiency reached 0.99% with the blend ratio of PBDTC10DBT and PC61BM being 1:2. PBDTC10DBT and PBDTC6DBT were both promising donor candidates in the application of polymer solar cells. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20124915754648 -
Record 242 of
Title:A copolymer based on benzo[1,2-b:4,5-b′]dithiophene and quinoxaline derivative for photovoltaic application
Author(s):Wu, Haimei(1,2); Qu, Bo(3); Cong, Zhiyuan(2); Liu, Hongli(2); Tian, Di(2); Gao, Bowen(4); An, Zhongwei(2); Gao, Chao(2,4); Xiao, Lixin(3); Chen, Zhijian(3); Liu, Huanhuan(4); Gong, Qihuang(3); Wei, Wei(1)Source: Reactive and Functional Polymers Volume: 72 Issue: 11 DOI: 10.1016/j.reactfunctpolym.2012.07.006 Published: November 2012Abstract:A D-A-D copolymer (PBDTQx) with a bandgap of 1.78 eV, containing alkoxy-substituted benzo[1,2-b:4,5-b′]dithiophene (BDT) as donor and quinoxaline derivative (Qx) as acceptor, was synthesized by Stille coupling reaction. In order to study the photovoltaic property of PBDTQx, polymer solar cells (PSCs) were fabricated with PBDTQx as the electron donor blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as the electron acceptor. The power conversion efficiency (PCE) of PSC was 1.01% for an optimized PBDTQx: PC61BM ratio of 1:5, under the illumination of AM 1.5, 100 mW/cm2. The results indicated that PBDTQx was a promising donor candidate in the application of polymer solar cells. ? 2012 Elsevier Ltd. All rights reserved.Accession Number: 20123915463584 -
Record 243 of
Title:High power laser diode drive power supply
Author(s):Lu, Kai(1,3); Liu, Baiyu(2); Bai, Yonglin(2); Gou, Yongsheng(2); Wang, Bo(2); Zhu, Bingli(1,3); Ouyang, Xian(2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 41 Issue: 10 DOI: Published: October 2012Abstract:High energy laser system typically requires multi-output mode laser diode drive power supply, and existing power supply has the problem of single output mode. In this paper, a laser diode drive power supply with multi-output mode characteristic was designed using power compression and current series negative feedback techniques. The principle of the negative feedback network was analyzed, which was a high input impendent different operation circuit with special design. Precise relationship between reference voltage and output current was deduced. After being applied in the first 400W industrial fiber laser system of China, the drive power supply realized continuous wave and quasi-continuous wave current output with the value adjusting continuous from 0 A to 26 A and the output current stability was better than 0.15‰. Test results demonstrate the feasibility of the design idea to achieve a multi-output mode and high current stability characteristics of the laser diode driver.Accession Number: 20125015795969 -
Record 244 of
Title:Three-dimensional reconstruction of laser-imploded targets from simulated pinhole images
Author(s):Xu, Peng(1,2,3); Bai, Yonglin(2); Bai, Xiaohong(1); Liu, Baiyu(2); Ouyang, Xian(2); Wang, Bo(2,3); Yang, Wenzheng(2); Gou, Yongsheng(2,3); Zhu, Bingli(2); Qin, Junjun(1)Source: Applied Optics Volume: 51 Issue: 32 DOI: 10.1364/AO.51.007820 Published: November 10, 2012Abstract:This paper proposes an integral method to achieve a more accurate weighting matrix that makes very positive contributions to the image reconstruction in inertial confinement fusion research. Standard algebraic reconstruction techniques with a positivity constraint included are utilized. The final normalized mean-square error between the simulated and reconstructed projection images is 0.000365%, which is a nearly perfect result, indicating that the weighting matrix is very important. Compared with the error between the simulated and reconstructed phantoms, which is 2.35%, it seems that the improvement of the accuracy of the projection image does not mean the improvement of the phantom. The proposed method can reconstruct a simulated laser-imploded target consisting of 100 × 100 × 100 voxels. ? 2012 Optical Society of America.Accession Number: 20124815715028 -
Record 245 of
Title:Research on the method of transient spectrum detection based on array CCD
Author(s):Zhu, Bing-Li(1,3); Bai, Yong-Lin(2); Wang, Bo(2); Liu, Bai-Yu(2); Ouyang, Xian(2); Yang, Wen-Zheng(2); Bai, Xiao-Hong(2); Qin, Jun-Jun(2); Zhao, Jun-Ping(2); Gou, Yong-Sheng(2); Lu, Kai(1,3)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 32 Issue: 4 DOI: 10.3964/j.issn.1000-0593(2012)04-1028-04 Published: April 2012Abstract:Based on the characteristic of high speed line scanning for CCD in transient spectrum detection, a method of transient spectrum detection with array CCD is presented. The high speed line scanning with array CCD was realized by changing the mode of charge transfer. In order to explore the feasibility of this method, a fast detection system of single point based on linear CCD was designed and fabricated. Seven different LED pulses were measured when the system worked at fast detection mode of single point and normal mode respectively. The results demonstrate that the method of fast detection of single point based on linear CCD is feasible, and the rate of single point detection reaches up to 20 MHz. Thus, in theory, it was proved that transient spectrum detection with array CCD by changing the mode of charge transfer is also feasible.Accession Number: 20121514940817 -
Record 246 of
Title:Robust CoHOG feature extraction in human-centered image/video management system
Author(s):Pang, Yanwei(1); Yan, He(1); Yuan, Yuan(2); Wang, Kongqiao(3)Source: IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics Volume: 42 Issue: 2 DOI: 10.1109/TSMCB.2011.2167750 Published: April 2012Abstract:Many human-centered image and video management systems depend on robust human detection. To extract robust features for human detection, this paper investigates the following shortcomings of co-occurrence histograms of oriented gradients (CoHOGs) which significantly limit its advantages: 1) The magnitudes of the gradients are discarded, and only the orientations are used; 2) the gradients are not smoothed, and thus, aliasing effect exists; and 3) the dimensionality of the CoHOG feature vector is very large (e.g., 200000). To deal with these problems, in this paper, we propose a framework that performs the following: 1) utilizes a novel gradient decomposition and combination strategy to make full use of the information of gradients; (2) adopts a two-stage gradient smoothing scheme to perform efficient gradient interpolation; and (3) employs incremental principal component analysis to reduce the large dimensionality of the CoHOG features. Experimental results on the two different human databases demonstrate the effectiveness of the proposed method. ? 2006 IEEE.Accession Number: 20121314907743 -
Record 247 of
Title:Vehicle detection and tracking in airborne videos by multi-motion layer analysis
Author(s):Cao, Xianbin(1,2); Lan, Jinhe(1); Yan, Pingkun(3); Li, Xuelong(3)Source: Machine Vision and Applications Volume: 23 Issue: 5 DOI: 10.1007/s00138-011-0336-x Published: September 2012Abstract:Airborne vehicle detection and tracking systems equipped on unmanned aerial vehicles (UAVs) are receiving more and more attention due to their advantages of high mobility, fast deployment and large surveillance scope. However, such systems are difficult to develop because of factors like UAV motion, scene complexity, and especially the partial occlusion of targets. To address these problems, a new framework of multi-motion layer analysis is proposed to detect and track moving vehicles in airborne platform. After motion layers are constructed, they are maintained over time for tracking vehicles. Most importantly, since the vehicle motion layers can be maintained even when the vehicles are only partially observed, the proposed method is robust to partial occlusion. Our experimental results showed that (1) compared with other previous algorithms, our method can achieve better performance in terms of higher detection rate and lower false positive rate; (2) it is more efficient and more robust to partial occlusion; (3) it is able to meet the demand of real time application due to its computational simplicity. ? 2011 Springer-Verlag.Accession Number: 20123515380095 -
Record 248 of
Title:Robust reversible watermarking via clustering and enhanced pixel-wise masking
Author(s):An, Lingling(1); Gao, Xinbo(1); Li, Xuelong(1); Tao, Dacheng(1); Deng, Cheng(2); Li, Jie(3)Source: IEEE Transactions on Image Processing Volume: 21 Issue: 8 DOI: 10.1109/TIP.2012.2191564 Published: 2012Abstract:Robust reversible watermarking (RRW) methods are popular in multimedia for protecting copyright, while preserving intactness of host images and providing robustness against unintentional attacks. However, conventional RRW methods are not readily applicable in practice. That is mainly because: 1) they fail to offer satisfactory reversibility on large-scale image datasets; 2) they have limited robustness in extracting watermarks from the watermarked images destroyed by different unintentional attacks; and 3) some of them suffer from extremely poor invisibility for watermarked images. Therefore, it is necessary to have a framework to address these three problems, and further improve its performance. This paper presents a novel pragmatic framework, wavelet-domain statistical quantity histogram shifting and clustering (WSQH-SC). Compared with conventional methods, WSQH-SC ingeniously constructs new watermark embedding and extraction procedures by histogram shifting and clustering, which are important for improving robustness and reducing run-time complexity. Additionally, WSQH-SC includes the property-inspired pixel adjustment to effectively handle overflow and underflow of pixels. This results in satisfactory reversibility and invisibility. Furthermore, to increase its practical applicability, WSQH-SC designs an enhanced pixel-wise masking to balance robustness and invisibility. We perform extensive experiments over natural, medical, and synthetic aperture radar images to show the effectiveness of WSQH-SC by comparing with the histogram rotation-based and histogram distribution constrained methods. ? 1992-2012 IEEE.Accession Number: 20123015284613 -
Record 249 of
Title:Efficient image matching using weighted voting
Author(s):Yuan, Yuan(1); Pang, Yanwei(2); Wang, Kongqiao(3); Shang, Mianyou(2)Source: Pattern Recognition Letters Volume: 33 Issue: 4 DOI: 10.1016/j.patrec.2011.02.008 Published: March 2012Abstract:Spectral decomposition subject to pairwise geometric constraints is one of the most successful image matching (correspondence establishment) methods which is widely used in image retrieval, recognition, registration, and stitching. When the number of candidate correspondences is large, the eigen-decomposition of the affinity matrix is time consuming and therefore is not suitable for real-time computer vision. To overcome the drawback, in this letter we propose to treat each candidate correspondence not only as a candidate but also as a voter. As a voter, it gives voting scores to other candidate correspondences. Based on the voting scores, the optimal correspondences are computed by simple addition and ranking operations. Experimental results on real-data demonstrate that the proposed method is more than one hundred times faster than the classical spectral method while does not decrease the matching accuracy. ? 2011 Published by Elsevier B.V. All rights reserved.Accession Number: 20120314685151 -
Record 250 of
Title:Experimental study on the imaging of the squeezed-state light with a virtual object
Author(s):Lu, Baozhu(1); Bi, Siwen(1); Feng, Fei(1); Kang, Menghua(1); Qin, Fei(2)Source: Optical Engineering Volume: 51 Issue: 11 DOI: 10.1117/1.OE.51.11.119001 Published: November 2012Abstract:A stable amplitude squeezed-state light was generated by utilizing the nondegenerate optical parametric amplifier based on periodically poled KTiOPO4 crystal at 1064 nm. We observed -4.93 dB of squeezing with a local oscillator phase locked in homodyne measurement. The imaging experiments of the resolution target have shown that the imaging resolution, which was based on squeezed-state light, is 1.41 times as much as the resolution that was acquired using coherent light as light source. In addition, the squeezed-state light was applied for imaging of the virtual object. It was found that the characters on the board were much more easily discerned with squeezed light as a light source than with coherent light. This result paves the way for further improvements of imaging resolution by use of the squeezed-state light. ? 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20135217143050 -
Record 251 of
Title:Experimental study on the imaging of the squeezed state light with-4. 93dB quantum-noise reduction at 1064 nm
Author(s):Lu, Baozhu(1); Bi, Siwen(1); Feng, Fei(1); Kang, Menghua(1); Qin, Fei(2)Source: Advanced Materials Research Volume: 571 Issue: DOI: 10.4028/www.scientific.net/AMR.571.439 Published: 2012Abstract:A stable amplitude squeezed state light was generated by utilizing the optical parametric down-conversion (OPDC) technique based on periodically poled KTiOPO4(PPKTP) in an optical parametric oscillator (OPO) resonator. We observed a-4. 93dB of squeezing in homodyne measurement. The imaging experiments of resolution target were conducted. It shown that the imaging resolution with squeezed state light as light source was 1. 26 times that of the resolution with coherent light as light source. The squeezed state light was applied for imaging of real objects and we found that the imaging with squeezed light as light source is more distinct and has less distortion. ? (2012) Trans Tech Publications, Switzerland.Accession Number: 20124815717076 -
Record 252 of
Title:Enhanced open-circuit voltage of two side chain conjugated polythiophene derivatives blended with indene-C60 bisadduct
Author(s):Gao, Chao(1,2); Qu, Bo(3); Chen, Dong(1); Cong, Zhiyuan(1); Liu, Jianqun(1); Chen, Jian(1); An, Zhongwei(1); Chen, Zhijian(3); Xiao, Lixin(3); Wei, Wei(2,4); Gong, Qihuang(3)Source: Reactive and Functional Polymers Volume: 72 Issue: 2 DOI: 10.1016/j.reactfunctpolym.2011.11.004 Published: February 2012Abstract:Two side chain conjugated polythiophene copolymer: poly[3-(5′- octylthienylenevinyl) thiophene]-thiophene (P1) and poly{3-[4-(2-ethyl-hexyloxy) -phenylvinyl]-thiophene}-thiophene (P2) were synthesized. Polymer photovoltaic solar cells using P1 and P2 as donor and a high LUMO energy level fullerene derivative indene-C60 bisadduct (IC60BA) as acceptor were demonstrated. The polymer solar cells (PSCs) based P1/IC60BA and P2/IC60BA showed enhanced open circuit voltage (Voc) of 0.89 and 0.88 V respectively, in comparison with that of P1/PC61BM and P2/PC61BM as 0.58 and 0.56 V, respectively. The improved V oc of IC60BA as acceptor in PSCs is benefited from the higher LUMO energy levels of the C60 derivatives. The power conversion efficiency of the PSCs based on P1/IC60BA and P2/IC 60BA were 0.32% and 0.35%, respectively. ? 2011 Elsevier Ltd. All rights reserved.Accession Number: 20120314702529