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Growth of N-polar GaN on vicinal sapphire substrate by metal organic chemical vapor deposition

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Rare Metals 2014年第6期33卷 709-713页

作者： Can-tao zhong Guo-Yi Zhang State Key Laboratory of Artificial Microstructure and Mesoscopic Physics School of Physics Peking University

The growth and properties of N-polar Ga N layers by metal organic chemical vapor deposition（MOCVD） were reported. It is found that N-polar Ga N grown on normal sapphire substrate shows hexagonal hillock surface morphology. With the misorientation angles increasing from 0.5° to 2.0° toward the a-plane of the sapphire substrate, the number of the hillock becomes less and less and finally the surface becomes flat one on the sapphire substrate with the misorientation angle of 2°. It is also found that the crystalline quality and the strain in the Ga N are greatly influenced by the misorientation angle.

关键词： GaN N-polarity Metal organic chemical vapor deposition

Finding a Way to Determine the Pion Distribution Amplitude from the Experimental Data

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Chinese Physics Letters 2013年第4期30卷 48-50页

作者： HUANG tao WU Xing-Gang zhong tao Institute of High Energy Physics and Theoretical Physics Center for Science Facilities Chinese Academy of SciencesBeijing 100049 Department of Physics Chongqing UniversityChongqing 401331

t is believed that one can extract more accurate information of the pion distribution amplitude from the pion-photon transition form factor(TFF)due to the single pion in this ***,the BABAR and Belle data of the pion-photon TFF have a big difference for Q^(2)∈[15,40]GeV^(2),and at present,the pion DA can not be definitely determined from the pion-photon *** is crucial to find the right pion DA behavior and to determine which data is more *** perform a combined analysis of the most existing data of the processes involving pion by using a general model for the pion wavefunction/*** a DA model can mimic all the existed pion DA behaviors,whose parameters can be fixed by the constraints from the processesπ^(0)→γγ,π→μν,and B→πlν,***,we examine the B→πtransition form factors that provides another constraint to the parameter B in our DA model,which results in B∈[0.00,0.29].This inversely shows that the predicted curve for the pion-photon TFF is between the BABAR and Belle data in the region Q^(2)∈[15,40]GeV^(2).It will be tested by coming more accurate data in large Q^(2)region,and the definite behavior of pion DA can be concluded finally.

关键词： process. finally transition

A residual denoising and multiscale attention-based weighted domain adaptation network for tunnel boring machine main bearing fault diagnosis

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Science China(Technological Sciences) 2024年第8期67卷 2594-2618页

作者： zhong tao QIN ChengJin SHI Gang ZHANG ZhiNan tao JianFeng LIU ChengLiang State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

As a critical component of a tunnel boring machine(TBM),the precise condition monitoring and fault analysis of the main bearing is essential to guarantee the safety and efficiency of the TBM cutter ***,under conditions of strong noise and complex working environments,traditional signal decomposition and machine learning methods struggle to extract weak fault features and achieve high fault classification *** address these issues,we propose a novel residual denoising and multiscale attention-based weighted domain adaptation network(RDMA-WDAN)for TBM main bearing fault *** approach skillfully designs a deep feature extractor incorporating residual denoising and multiscale attention modules,achieving better domain adaptation despite significant domain *** residual denoising component utilizes a convolutional block to extract noise features,removing them via residual ***,the multiscale attention module uses a 4-branch convolution and 3 pooling strategy-based channel–spatial attention mechanism to extract multiscale features,concentrating on deep fault *** training,a weighting mechanism is introduced to prioritize domain samples with clear fault *** optimizes the deep feature extractor to obtain common features,enhancing domain adaptation.A low-speed and heavy-loaded bearing testbed was built,and fault data sets were established to validate the proposed *** experiments show that in noise domain adaptation tasks,proposed the RDMA–WDAN significantly improves target domain classification accuracy by 42.544%,23.088%,43.133%,16.344%,5.022%,and 9.233%over dense connection network(DenseNet),squeeze–excitation residual network(SE-ResNet),antinoise multiscale convolutional neural network(ANMSCNN),multiscale attention module-based convolutional neural network(MSAMCNN),domain adaptation network,and hybrid weighted domain adaptation(HWDA).In combined noise and working condition domain a

关键词： tunnel boring machine(TBM) main bearing fault diagnosis domain adaptation antinoise cross working RDMA-WDAN

MULTIPARAMETER MEASUREMENT FOR RACEWAY GROOVE OF BEARING BASED ON 3D RECONSTRUCTION WITH DIGITAL STRUCTURED LIGHT

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Chinese Journal of Mechanical Engineering 2005年第3期18卷 470-472页

作者： He tao zhong Ming LiWei zhong Yuning Shi Tielin School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

A fast 3D reconstruction method based on structured light to measure various parameters of the raceway groove is presented. Digital parallel grating stripes distributed with sine density are projected onto the raceway groove by a DLP projector, and distorting of stripes is happened on the raceway. Simultaneously, aided by three-step phase-shifting approach, three images covered by different stripes are obtained by a high-resolution CCD camera at the same location, thus a more accuracy local topography can be obtained. And then the bearing is rotated on a high precision computer controlled rotational stage. Three images are also obtained as the former step at next planned location triggered by the motor. After one cycle, all images information is combined through the mosaics. As a result, the 3D information of raceway groove can be gained. Not only geometric properties but also surface flaws can be extracted by software. A preliminary hardware system has been built, with which some geometric parameters have been extracted from reconstructed local topography.

关键词： Structured light Fringe projection Phase-shifting Multiparameter measurement 3D reconstruction

Short Form of Weinstein Noise Sensitivity Scale(NSS-SF): Reliability, Validity and Gender Invariance among Chinese Individuals

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Biomedical and Environmental Sciences 2018年第2期31卷 97-105页

作者： zhong tao CHUNG Pak-kwong LIU Jing Dong Faculty of Social Science Hong Kong Baptist University

Objective Independent from noise exposure, noise sensitivity plays a pivotal role in people＇s noise annoyance perception and concomitant health deteriorations. The present study empirically investigated the psychometric properties of the Chinese version of the Weinstein Noise Sensitivity Scale-Short Form （CNSS-SF）, the widely used inventory measuring individual differences in noise *** In total, 373 Chinese participants （age = 21.41 ± 3.36） completed the online, anonymous questionnaire package. Examination of the CNSS-SF＇s reliability （internal consistency）, factorial validity through validation and cross-validation, nomological validity and measurement invariance across gender groups were *** The Cronbach alpha coefficients and composite reliabilities indicated sufficient reliability of the CNSS-SF. Two confirmatory factor analyses （CFA）, in two randomly partitioned groups of participants, substantiated the factorial validity of the scale. The nomological validity of the scale was also corroborated by the significant positive association of its score with the trait anxiety score. Measurement invariance of the CNSS-SF was also found across genders via multi-group *** Though not without limitations, findings from the present research provide promising evidence for the utility of the scale in measuring noise sensitivity among the Chinese population. The availability of the CNSS-SF can promote research related to environmental noise and health in China, as well as facilitate cross-cultural comparisons.

关键词： Environmental noise Individual differences Cross-cultural validation Measurement Publichealth

Route strategy of satellite network in GNSS based on topology evolution law

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Journal of Systems Engineering and Electronics 2014年第4期25卷 596-608页

作者： Xianqing Yi Zhenwei Hou tao zhong Yaohong Zhang Zhili Sun Science and Technology on Information Systems Engineering Laboratory National University of Defense Technology Centre for Communication Systems Research University of Surrey

As each type of satellite network has different link features, its data transmission must be designed based on its link features to improve the efficiency of data transferring. The transmission of navigation integrated services information （NISI） in a global navigation satellite system （GNSS） with inter-satellite links （ISLs） is studied by taking the real situation of inter-satellite communication links into account. An on-demand computing and buffering centralized route strategy is proposed based on dynamic grouping and the topology evolution law of the GNSS network within which the satellite nodes are operated in the manner of dynamic grouping. Dynamic grouping is based on satellites spatial relationships and the group role of the satellite node changes by turns due to its spatial relationships. The route strategy provides significant advantages of high efficiency, low complexity, and flexi- ble configuration, by which the established GNSS can possess the features and capabilities of feasible deployment, efficient transmission, convenient management, structural invulnerability and flexible expansion.

关键词： satellite navigation evolution law route strategy.

Numerical simulation of coupling heat transfer and thermal stress for spent fuel dry storage cask with different power distribution and tilt angles

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Nuclear Science and Techniques 2023年第2期34卷 109-127页

作者： Wei‑Hao Ji Jian‑Jie Cheng Han‑zhong tao Wei Li College of Urban Construction Nanjing Tech UniversityNanjing 211800China School of Energy Science and Engineering Nanjing Tech UniversityNanjing 211800China

Dry storage containers must be secured and reliable during long-term storage,and the effect of decay heat released from the internal spent fuel on the cask has become an important research *** this paper,a 3D computational fluid dynamics model is presented,and the accuracy of the calculation is verified,with computational errors of less than 6.2%.The thermal stress of the dry storage cask was estimated by coupling it with a transient temperature *** total power remained constant and adjusting the power ratio of the inner and outer zones had a small effect on the stress results,with a maximum equivalent stress of approximately 5.2 kPa,which occurred at the lower edge of the *** the case of tilt,the temperature gradient varied in a wavy distribution,and the wave crest moved from right to *** the tilt angle affects the air distribution in the annular gap,leading to the shell temperature being transformed,with a maximum equivalent stress of 202 MPa at the bottom of the ***,the equivalent stress in both cases was less than the yield stress(205 MPa).

关键词： Thermal stress CFD simulation Spent nuclear fuel Dry storage cask

A Simple and Efficient Algorithm to Identify the Chirality of Polymer Knots Based on the Alexander Polynomial

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Chinese Journal of Polymer Science 2024年第12期42卷 2030-2037,I0012页

作者： Qi-Yuan Qiu Yong-Jian Zhu zhong-tao Wu Liang Dai Department of Physics City University of Hong KongHong Kong999077China Shenzhen Research Institute City University of Hong KongShenzhen518057China Department of Mathematics The Chinese University of Hong KongHong Kong999077China

Recent experimental observations of knotting in DNA and proteins have stimulated the simulation studies of polymer *** studies usually identify knots in polymer conformations through the calculation of the Alexander ***,the Alexander polynomial cannot directly discriminate knot chirality,while knot chirality plays important roles in many physical,chemical,and biological *** this work,we discover a new relationship for knot chirality and accordingly,develop a new algorithm to extend the applicability of the Alexander polynomial to the identification of knot *** algorithm adds an extra step in the ordinary calculation of the Alexander *** extra step only slightly increases the computational *** correctness of our algorithm has been proved mathematically by *** implication of this algorithm in physical research has been demonstrated by our studies of the tube model for polymer *** this algorithm,we would be unable to obtain the tubes for polymer knots.

关键词： Polymerentanglement Polymer knot Polymerconformation Tubemodel Monte Carlo simulation

Synergistic Effect and Fluorination Effect in Ethylene Polymerization by Nickel Phenoxyiminato Catalysts

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Chinese Journal of Polymer Science 2018年第2期36卷 244-251页

作者： Di Xu Xiang-Xiang Zhao zhong-tao Chen Yu-Guo Ma Beijing National Laboratory for Molecular Sciences (BNLMS) Center for Soft Matter Science and Engineering Key Lab of Polymer Chemistry & Physics of Ministry of Education College of Chemistry Peking University

A series of binuclear nickel phenoxyiminato catalysts with different linkers and fluorine substituents were efficiently synthesized. Binuclear nickel catalysts with rigid linkers showed higher catalytic activity and thermal stability in ethylene polymerization and produced polymers with higher molecular weight possibly due to the larger steric hindrance and metal-metal synergistic effect. The introduction of fluorine atoms on the N-terphenyl moity also enhanced polymerization activity and molecular weight of polymer due to the electronic effect of fluorine atoms.

关键词： Nickel phenoxyiminato catalysts Fluorination effect Synergistic effect Bimetallic catalysts