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Combination of terrestrial reference frames based on space geodetic techniques in SHAO:methodology and main issues

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Research in Astronomy and Astrophysics 2017年第9期17卷 1-14页

作者： Bing He xiao-Ya wang xiao-Gong Hu qun-He Zhao Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Aerospace Dynamics Xi'an 710043China

Based on years of input from the four geodetic techniques （SLR, GPS, VLBI and DORIS）, the strategies of the combination were studied in SHAO to generate a new global terrestrial reference frame as the material realization of the ITRS defined in IERS Conventions. The main input includes the time series of weekly solutions （or fortnightly for SLR 1983-1993） of observational data for satellite techniques and session-wise normal equations for VLBI. The set of estimated unknowns includes 3- dimensional Cartesian coordinates at the reference epoch 2005.0 of the stations distributed globally and their rates as well as the time series of consistent Earth Orientation Parameters （EOPs） at the same epochs as the input. Besides the final solution, namely SOL-2, generated by using all the inputs before 2015.0 obtained from short-term observation processing, another reference solution, namely SOL- 1, was also computed by using the input before 2009.0 based on the same combination of procedures for the purpose of comparison with ITRF2008 and DTRF2008 and for evaluating the effect of the latest six more years of data on the combined results. The estimated accuracy of the x-component and y-component of the SOL- 1 TRF-origin was better than 0.1 mm at epoch 2005.0 and better than 0.3 mm yr- 1 in time evolution, either compared with ITRF2008 or DTRF2008. However, the z-component of the translation parameters from SOL-1 to ITRF2008 and DTRF2008 were 3.4 mm and -1.0 ram, respectively. It seems that the z-component of the SOL-1 TRF-origin was much closer to the one in DTRF2008 than the one in ITRF2008. The translation parameters from SOL-2 to ITRF2014 were 2.2, -1.8 and 0.9 mm in the x-, y- and z-components respectively with rates smaller than 0.4 mmyr-1. Similarly, the scale factor transformed from SOL-1 to DTRF2008 was much smaller than that to ITRF2008. The scale parameter from SOL-2 to ITRF2014 was -0.31 ppb with a rate lower than 0.01 ppb yr-1. The external precision （WRMS） compared

关键词： astrometry w reference systems -- techniques: interferometers -- methods: data analysis

Synthesis of glycerin triacetate over molding zirconia-loaded sulfuric acid catalyst

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Journal of Natural Gas Chemistry 2012年第1期21卷 25-28页

作者： Lian wang qun Liu Minghao Zhou Guomin xiao School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189JiangsuChina

Zirconia-loaded sulfuric acid （SO2-/ZrO2） catalysts were prepared by impregnation method, molded by punch tablet machine and characterized by X-ray diffraction. SO4^2-/ZrO2 catalyst was used to obtain glycerol triacetate （GTA） directly from glycerin. The effect of some factors, such as different temperatures of calcination and catalysts molded or not, on the reusable times of catalysts and the yield of GTA were investigated. The optimum reaction conditions were shown as follows： the reaction temperature was 403 K; the reaction time continued for 8 h; the amount of molded catalysts was 5 wt% of glycerin and the molar ratio of glycerin to acetic acid was 1 ： 8. The yield of GTA was 97.93% under the optimum condition.

关键词： glycerol triacetate zirconia-loaded sulfuric acid catalyst esterification

Intelligent Fault Diagnosis of Rotary Machinery Based on Unsupervised Multiscale Representation Learning

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Chinese Journal of Mechanical Engineering 2017年第6期30卷 1314-1324页

作者： Guo-Qian Jiang Ping Xie xiao wang Meng Chen qun He School of Electrical Engineering Yanshan University The Six Branch of Qinhuangdao Port Co Ltd

The performance of traditional vibration based fault diagnosis methods greatly depends on those hand- crafted features extracted using signal processing algo- rithms, which require significant amounts of domain knowledge and human labor, and do not generalize well to new diagnosis domains. Recently, unsupervised represen- tation learning provides an alternative promising solution to feature extraction in traditional fault diagnosis due to its superior learning ability from unlabeled data. Given that vibration signals usually contain multiple temporal struc- tures, this paper proposes a multiscale representation learning （MSRL） framework to learn useful features directly from raw vibration signals, with the aim to capture rich and complementary fault pattern information at dif- ferent scales. In our proposed approach, a coarse-grained procedure is first employed to obtain multiple scale signals from an original vibration signal. Then, sparse filtering, a newly developed unsupervised learning algorithm, is applied to automatically learn useful features from each scale signal, respectively, and then the learned features at each scale to be concatenated one by one to obtain multi- scale representations. Finally, the multiscale representa- tions are fed into a supervised classifier to achieve diagnosis results. Our proposed approach is evaluated using two different case studies： motor bearing and wind turbine gearbox fault diagnosis. Experimental results show that the proposed MSRL approach can take full advantages of the availability of unlabeled data to learn discriminative features and achieved better performance with higher accuracy and stability compared to the traditional approaches.

关键词： Intelligent fault diagnosis Vibration signals Unsupervised feature learning Sparse filtering Multiscalefeature extraction

Composite Quantile Regression Estimation for Left Censored Response Longitudinal Data

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Acta Mathematicae Applicatae Sinica 2018年第4期34卷 730-741页

作者： Li-qun xiao Zhan-feng wang Yao-hua WU School of Economics and Statistics Guangzhou University Guangzhou 510006 China Department of Statistics and Finance The School of Management University of Science and Technology of China Hefei 230026 China

For left censored response longitudinal data, we propose a composite quantile regression estimator（CQR） of regression parameter. Statistical properties such as consistency and asymptotic normality of CQR are studied under relaxable assumptions of correlation structure of error terms. The performance of CQR is investigated via simulation studies and a real dataset analysis.

关键词： longitudinal data left censored quantile regression randomly weighting

Credibility protection for resource sharing and collaborating in non-center network computing environments

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The Journal of China Universities of Posts and Telecommunications 2014年第3期21卷 46-55页

作者： XU xiao-long TU qun wang Xin-heng wang Ru-chuan College of Computer Nanjing University of Posts and Telecommunications State Key Laboratory for Novel Software Technology Nanjing University School of Computing University of the West of Scotland Paisley PA1 2BE United Kingdom

Non-center network computing environments have some unique characteristics, such as instability, heterogeneity, autonomy, distribution and openness, which bring serious issues of security and reliability. This article proposes a brand-new credibility protection mechanism for resource sharing and collaboration in non-center network computing environments. First, the three-dimensional hierarchical classified topology （3DHCT） is proposed, which provides a basic framework for realizations of the identity credibility, the behavior credibility and the capability credibility. Next, the agent technology is utilized to construct the credibility protection model. This article also proposes a new comprehensive credibility evaluation algorithm with simple, efficient, quantitative and able to meet the requirements of evaluating behavior credibility and the capability credibility evaluation as well. The Dempster-Shafer theory of evidence and the combination rule are used to achieve the evaluation of the capability credibility. The behavior credibility is evaluated with the current and historical performance of nodes for providers and consumers to realize more accurate prediction. Based on the non-center network computing simulation test platform, simulation is been conducted to test the performance and validity of the proposed algorithms. Experiment and analysis show that the proposed algorithms are suitable for large-scale, dynamic network computing environments, and able to maintain the credibility for networks without relying on central node, make a non-center network gradually evolve into an orderly, stable and reliable computing environment efficiently.

关键词： non-center network computing agent credibility evidence

First-principles Study of Electron Transport Through Oligoacenes

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Chinese Journal of Chemical Physics 2009年第1期22卷 7-12页

作者： Zhen Pan qun-xiang Li Qin-wei Shi xiao-ping wang Hefei National Laboratory for Physical Sciences at Microscale University of Science and Technology of China Hefei 230026 China

The electronic transport properties of oligoacenes sandwiched between two Au（111） surfaces with serial and parrallel configurations were investigeted by using a fully self-consistent nonequilibrium Green＇s function method combined with density functional calculations. This theoretical results show that the conductivity of oligoacenes with both sandwiched configurations at low bias voltage is mainly determined by the tail of the transmission peak from the perturbed highest occupied molecular orbital. When the molecular length increases, the zero-bias voltage conductance G（0） of oligoacenes with serial configuration neither follows Magoga＇s exponential law nor displays the even-odd oscillation effect, while the G（O） of the oligoacenes sandwiched with parallel configuration monotonically increases. The reduction of energy gaps, the alignment of the Fermi level, and the spatial distribution of the perturbed molecular orbitals are used to self-consistently explore the transport mechanism through oligoacenes.

关键词： Transport property Oligoacene Zero-bias voltage conductance First-principles calculation

Ensuring consistency of Web services transaction

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The Journal of China Universities of Posts and Telecommunications 2009年第4期16卷 59-66页

作者： wang xiao-jun LI Yang-qun WU xiao-mei MIN Li-juan Institute of Information and Network Technology Nanjing University of Posts and Telecommunications Nanjing 210003 China Foreign Languages Office Nanjing Institute of Politics Nanjing 210003 China

Composite Web services provide promising prospects for conducting cross-organizational Web service transactions. Such transactions generally require longer processing time and manipulate financially critical data. To efficiently manage these Web services transactions, isolation is commonly relaxed, but inconsistency will be caused by concurrently executing isolation-relaxing transactions. This article proposes an extension to the WS-Business Activity Protocol, which ensures the consistent executions of isolation-relaxing Web service transactions, and which is based on transaction dependency graphs distributed over multiple nodes. Furthermore, this article presents several algorithms implementing the protocol, and introduces the implement of a prototype system.

关键词： Web services transaction model transaction management protocol consistency

Influence of grain refinement on the corrosion behavior of metallic materials:A review

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International Journal of Minerals,Metallurgy and Materials 2021年第7期28卷 1112-1126页

作者： Pan-jun wang Ling-wei Ma Xue-qun Cheng xiao-gang Li Institute of Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China National Materials Corrosion and Protection Scientific Data Center University of Science and Technology BeijingBeijing 100083China

Grain refinement can strengthen the mechanical properties of materials according to the classical Hall-Petch relationship but does not always result in better corrosion *** the past few decades,various techniques have been dedicated to refining grain,along with relevant studies on corrosion behavior,including general corrosion,pitting corrosion,and stress corrosion ***,the funda-mental consensus on how grain size influences corrosion behavior has not been *** paper reviews existing literature on the beneficial and detrimental effects of grain refinement on corrosion ***,the effects of microstructural changes(i.e.,grain boundary,dislo-cation,texture,residual stress,impurities,and second phase)resulting from grain refinement on corrosion behavior are *** grain re-finement not only has an impact on the corrosion performance,but also results in microstructural changes that have a non-negligible effect on corrosion behavior or even outweigh that of grain *** size is not the only factor affecting the corrosion behavior of metallic ma-terials;thus,the overall influence of microstructures on corrosion behavior should be understood.

关键词： corrosion behavior grain refinement microstructure high-temperature oxidation

Novel gripper module and method for automated assembly of miniature parts

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Advances in Manufacturing 2023年第2期11卷 295-310页

作者： Zhi-Yong Zhang xiao-Dong wang Tong-qun Ren Tian-Lun Jin Key Laboratory for Micro/Nano Technology and System of Liaoning Province Dalian University of TechnologyDalian116024LiaoningPeople's Republic of China Key Laboratory for Precision and Non-traditional Machining of Ministry of Education Dalian University of TechnologyDalian116024LiaoningPeople's Republic of China

During assembly process,the miniature part needs to be fixed in its assembly *** some occasions where adhesive is used,the joining force is not established due to the adhesive curing process,in that case the locking of parts is *** locking is difficult to meet the increasing demand for mass *** solve this problem and realize fully automatic assembly,a novel gripper module was designed and corresponding locking method was *** to the functional integration,the gripper module is capable of manipulating and locking the *** module is integrated into the assembly system and plays a crucial role in automatic *** locking method for automatic assembly is based on the integration of the part picking up and the locking unit *** being placed accurately at its desired position,the miniature part can be automatically locked by releasing the locking *** innovative structure and mechanism of the gripper module convert the spring force into the locking force of the miniature part,ensuring non-rigid locking and suitable small locking *** principle,flexibility and limitations of the proposed method were clarified in ***,an effective compensation strategy was used to achieve accurate and stable pickup of the part,which increased the reliability of the assembly *** automatic locking,the disturbances to the part due to the eccentric load were *** effectiveness of the gripper module and proposed method was verified by *** results indicated that the modular system integrated with the gripper module could meet the requirements of fully automatic *** locking is replaced by automatic locking,and workers are liberated from tedious manual *** improvement of automation level enables assembly equipment to be applied to mass production scenarios.

关键词： Fully automatic assembly Miniature parts Automatic locking Gripper module