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On-line diagnosis method of crack behavior abnormality in concrete dams based on fluctuation of sequential parameter estimates

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Science China(Technological Sciences) 2015年第3期58卷 415-424页

作者： LI ZhanChao GU ChongShi WANG ZhengZhong wu ZhongRu College of Water Resources and Architectural Engineering Northwest A&F University State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University College of Water Conservancy and Hydropower Engineering Hohai University

Research on on-line diagnosis method of crack behavior abnormality in concrete dams can provide support for timely grasping abnormality state of the crack itself and achieving real-time monitoring of the dam *** that samples of crack effects in concrete dams increase actually over monitoring time,a superiority criterion for the on-line diagnosis is determined so as to detect the abnormality moments timely and *** integrating the safety monitoring statistical model of crack effect variable with change point theory,a fluctuation method of regression coefficients is established for the on-line *** addition,each abnormality moment is detected by the cumulative sum of regression model *** indicate that abnormality of crack behavior in concrete dams can be characterized by structural instability of crack monitoring *** causes of crack behavior abnormality can be analyzed by the established method,which will play an important role in dam safety ***,taking the crack in a concrete gravity-arch dam as an example,the scientific rationality and validity of the established on-line diagnosis method are confirmed.

关键词： concrete dams crack behavior abnormality on-line diagnosis fluctuation of regression coefficients

A framework for the fusion of visual and tactile modalities for improving robot perception

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Science China(Information Sciences) 2017年第1期60卷 145-156页

作者： Wenchang ZHANG Fuchun SUN Hang wu Haolin YANG The State Key Laboratory of Intelligent Technology and Systems Tsinghua University

Robots should ideally perceive objects using human-like multi-modal sensing such as vision, tactile feedback, smell, and hearing. However, the features presentations are different for each modal sensor. Moreover,the extracted feature methods for each modal are not the same. Some modal features such as vision, which presents a spatial property, are static while features such as tactile feedback, which presents temporal pattern,are dynamic. It is difficult to fuse these data at the feature level for robot perception. In this study, we propose a framework for the fusion of visual and tactile modal features, which includes the extraction of features, feature vector normalization and generation based on bag-of-system(BoS), and coding by robust multi-modal joint sparse representation(RM-JSR) and classification, thereby enabling robot perception to solve the problem of diverse modal data fusion at the feature level. Finally, comparative experiments are carried out to demonstrate the performance of this framework.

关键词： multi-modal fusion robot perception vision tactile classification

Flow structure and unsteady fluctuation with separation over a two-dimensional backward-facing step

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Journal of Hydrodynamics 2019年第6期31卷 1204-1217页

作者： Fang-fang Wang Shi-qiang wu Biao Huang State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research InstituteNanjing 210029China Smart Cities Institute Zhengzhou UniversityZhengzhou 450001China

The flow over a backward-facing step(BFS)is a typical separation and reattachment *** flow structures and unsteady mechanisms are still not well *** this paper,the global velocity fields of a BFS are obtained by a synchronous particle image velocimetry(PIV)system with Reh=5345(Reynolds number)and Er=2(expansion ratio).Flow structures are distinguished and defined by the fraction of the negative velocity(upn).The reattachment zone(Lr)is quantitatively defined as(u0.9,u/0.1)on the bottom *** distribution of the large-scale vortices couples well with the divided flow structures and their temporal evolution presenting four stages(forming,developing,shedding and redeveloping)when travel *** unsteady motions with various low frequencies are well explained by the coherent vortices and flow *** the unsteady low frequency motions,the Kelvin Helmholtz(KH)vortices and the oscillation of Xr(OX)come likely from the free shear *** KH vortices contribute to the unsteadiness of the temporal flow,and the OX is the primary response to the vortical fluctuations.

关键词： Backward-facing step flow structure large-scale vortices unsteady motion free shear layer

Effect of TiO_2 calcination temperature on the photocatalytic oxidation of gaseous NH_3

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Journal of Environmental Sciences 2014年第3期26卷 673-682页

作者： Hongmin wu Jinzhu Ma Changbin Zhang Hong He Research Center for Eco-Environmental Sciences Chinese Academy of Sciences

Carbon-modified titanium dioxide （TiO2） was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation （PCO） of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400℃ had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range （〈 300℃）. However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400℃ contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.

关键词： photocatalysis NH3 TiO2 calcination temperature indoor air quality

Repeated sending file delivery protocol in satellite networking communication

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Journal of Systems Engineering and Electronics 2012年第6期23卷 815-823页

作者： Yongqing Wang Jun Li Guang Chen Siliang wu School of Information and Electronics Beijing Institute of Technology Beijing 100081 E R. China Beijing Institute of Remote Sensing Devices Beijing 100854 P. R. China

Satellite networking communications in navigation satellite system and spacebased deep space exploration have the features of a long delay and high bit error rate （BER）. Through analyzing the advantages and disadvantages of the Consulta tive Committee for the Space Data System （CCSDS） file delivery protocol （CFDP）, a new improved repeated sending file delivery protocol （RSFDP） based on the adaptive repeated sending is put forward to build an efficient and reliable file transmission. According to the estimation of the BER of the transmission link, RSFDP repeatedly sends the lost protocol data units （PDUs） at the stage of the retransmission to improve the success rate and reduce time of the retransmission. Theoretical analyses and results of the Opnet simulation indicate that the performance of RSFDP has significant improvement gains over CFDP in the link with a long delay and high BER. The realizing results based on the space borne filed programmable gate array （FPGA） platform show the applicability of the proposed algorithm.

关键词： satellite networking high bit error rate (BER) Con-sultative Committee for Space Data System (CCSDS) file deliveryprotocol (CFDP).

LDPC Decoder for CCSDS Code by Flipping Bits and Fetching Words

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wuhan University Journal of Natural Sciences 2021年第2期26卷 174-182页

作者： wu Tao LIU Hailiang Shenzhen Research Institute of Sun Yat-sen University Shenzhen 518057GuangdongChina Guangzhou Institute of Artificial Intelligence and Advanced Computing Institute of Automation of Chinese Academy of SciencesGuangzhou 510530GuangdongChina

The well-known CCSDS(consultative committee for space data systems) LDPC(low density parity check) code for near-earth applications is discussed and used for a case study of Mc Eliece system. First, a data error is picked out with the CCSDS LDPC code. The problem with its generator matrix is illustrated and overcome by a shortened code with some middle code bits deleted. In correspondence, its parity check matrix is also revised with the new quasi-cyclic(QC)-LDPC code. Second, a fast decoding scheme for general QC-LDPC codes is proposed based on flipping bits and fetching words. Besides, a lightweight CCSDS LDPC code based Mc Eliece system can be set up with such codes. The repaired CCSDS LDPC code is supposed to be still useful for communications and storages, and the normalized decoding algorithm is also efficient for general QC-LDPC codes.

关键词： LDPC(low density parity check)code CCSDS(consultative committee for space data systems) bit-flipping Mc Eliece system

Asymptotic efficiency of randomly weighted bootstrap for linear models

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Chinese Science Bulletin 1998年第9期43卷 711-712页

作者： Yaohua wu Lincheng Zhao Univ Sci & Technol China Dept Stat & Finance Hefei 230026 Peoples R China

This note discusses the method of randomly weighted bootstrap to derive the approximation of M-estimates in linear models, and shows that the approximation is asymptotically valid under some mild conditions.

关键词： M-estimates randomly weighted bootstrap linear models.

Origin of high mechanical quality factor in CuO-doped （K, Na）NbO3-based ceramics

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Frontiers of Materials Science 2014年第2期8卷 165-175页

作者： Wen-Feng LIANG Ding-Quan XIAO Jia-Gang wu Wen-Juan wu Jian-Guo ZHU Department of Materials Science Sichuan University Chengdu 610064 China CAEP Key Laboratory of Neutron Physics Mianyang 621900 China Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang 621900 China

The origin of a high mechanical quality in CuO-doped （K, Na）NbO3-based ceramics is addressed by considering the correlations between the lattice positions of Cu ions and the hardening effect in K0.48Na0.52＋xNbO3-0.01CuO ceramics. The Cu ions simultaneously occupy K/Na and Nb sites of these ceramics with x = 0 and 0.02, only occupy the K/Na site of the ceramics with x= -0.02, and mostly form a secondary phase of the ceramics with x = -0.05. The Cu ions lead to the hardening of ceramics with an increase of Ec and Qm by only occupying the K/Na site, together with the formation of double hysteresis loops in un-poled compositions. A defect model is proposed to illuminate the origin of a high Qm value, that is, the domain stabilization is dominated by the content of relatively mobile O2- ions in the ceramics, which has a weak bonding with CUK/Na defects.

关键词： lead-free piezoelectric ceramic (K, Na)NbO3 (KNN) mechanism of hard-ening effect mechanical quality factor Qm domain stabilization

Intracellular recording and morphology of tectal neurons activated by contralateral nucleus isthmi in toads

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Chinese Science Bulletin 1997年第19期42卷 1647-1651页

作者： Wang, SR wu, GY Laboratory for Visual Information Processing Institute of Biophysics Chinese Academy of Sciences Beijing China

THE nucleus isthmi (NI) in lower vertebrates and its mammalian analogue, the nucleus para-bigeminalis, are all visual centres. They receive their tectal input ipsilaterally and project backipsilaterally in teleosts and birds, or bilaterally in amphibians and reptiles, as well as in mam-mals. It is well known that NI receives its visual excitation through the ipsilateral optic tec-tum (OT). NI mainly exerts inhibition on the ipsilateral OT in frogs.A recent study

关键词： nucleus isthmi tectum intracellular recording morphology toad