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Distribution function estimates by Wasserstein metric and Bernstein approximation for C^(-1) functions

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Applied Mathematics(A Journal of Chinese Universities) 2015年第2期30卷 141-150页

作者： WU zong-min tian Zheng Shanghai Key Laboratory for Contemporary Applied Mathematics School of Mathematical SciencesFudan University

The aim of the paper is to estimate the density functions or distribution functions measured by Wasserstein metric, a typical kind of statistical distances, which is usually required in the statistical learning. Based on the classical Bernstein approximation, a scheme is presented. To get the error estimates of the scheme, the problem turns to estimating the L1 norm of the Bernstein approximation for monotone C-1 functions, which was rarely discussed in the classical approximation theory. Finally, we get a probability estimate by the statistical distance.

关键词： Wasserstein metric Bernstein approximation L1 norm approximation confidence interval

Recent progress of sugar amino acids: Synthetic strategies and applications as glycomimetics and peptidomimetics

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Chinese Chemical Letters 2015年第8期26卷 922-930页

作者： guang-zong tian Xiao-Li Wang Jing Hu Xue-Bin Wang Xiao-Qiang Guo Jian Yin Key Laboratory of Carbohydrate Chemistry and Biotechnology Ministry of Education School of Biotechnology Jiangnan University Synergetic Innovation Center of Food Safety and Nutrition Jiangnan University Wuxi Medical School Jiangnan University

In order to meet the increasing demands for the development of large varieties of new molecules for discovering new drugs and materials, organic chemists are developing many novel multifunctional building blocks, which are assembled rationally to create ‘nature-like＇ and yet unnatural organic molecules with well-defined structures and useful properties. Sugar amino acids（SAAs）, the carbohydrate derivatives bearing both amino and carboxylic acid functional groups, are important ones of these multifunctional building blocks, which can be used to create novel materials with potential applications as glycomimetics and peptidomimetics. This review will focus on recent synthetic strategies of SAAs and their applications in creating large number of structurally diverse glycomimetics and peptidomimetics.

关键词： structurally carboxylic oligomer blocks assembled Fmoc amide carbohydrate diverse protected

Statistical analysis of one Chinese sun-synchronous satellite anomalies

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Science China(Technological Sciences) 2016年第4期59卷 540-546页

作者： tian tian zong QiuGang CHANG Zheng WANG YongFu YANG XiaoHua Institute of Space Physics and Applied Technology Peking UniversityBeijing 100871China Mailbox 5111 Beijing 100094China Center for Space Science and Applied Research Chinese Academy of SciencesBeijing 100190China

Based on the data from the Medium-Energy Proton and Electron Detector （MEPED） onboard NOAA-17, 141 anomalies of a Chinese Sun-Synchronous satellite （SSO-X） that occurred between 02/01/2010 and 09/31/2012 were studied statistically. About 26 out of the 52 anomalies that occurred outside the South Atlantic Anomaly （SAA） were accompanied by energetic electron storms. Superposed Epoch Analysis （SEA） was used to analyze the properties of the anomalies and the dynamics of the space environments during these 26 events. Then, a Monte Carlo method was utilized to simulate the electron deposition and the interactions of the injected electrons with an aluminum shield and polyethylene dielectric. The average, median, and 75tb percentile values of the maximum electric field strength inside the dielectric were calculated. The results showed the tbl- lowing. （1） SSO-X anomalies are more likely to occur within the SAA, as 89 out of 141 anomalies （63%） occurred there. （2） Twenty-six of the anomalies that occurred outside the SAA during energetic electron storms were located near the outer boundaries of the outer radiation belts, and these were more frequent in the Southern Hemisphere than in the Northern Hemi- sphere. （3） Electron flux enhancements occurred around the failure time at all energy levels but were more profound in the lower energy channels. The maximum fluxes of electrons 〉30 keV, 〉100 keV, and 〉300 keV were 106, 3.5x10s, and 1.2×10^6 cm 2 s^-1 · sr ^-1, respectively. （4） The average, median, and 75th percentile values of the maximum electric field strengths inside the dielectric for the aforementioned 26 events remained in the range from 106 to 107 V/m for long time periods, which sug- gests that the ＇potential hazards＇ of internal discharges cause SSO-X anomalies. The above results can provide useful infor- mation for the design and protection of sun-synchronous spacecraft.

关键词： SSO-X failure superposed epoch analysis Monte Carlo method internal charging maximum electric field strength radiation belts

Novel Hydroperoxides of 1-Imino-3,3-Disubstituted-1,3-Dihydro Isobenzofuran

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Chinese Chemical Letters 2000年第3期11卷 203-206页

作者： Wen Ge YAN Bai Ling XU zong Ru GUO Xiao tian LIANG guang Zhong YANG Institute of Materia Medica Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050

Some 1-imino-3,3-disubstituted-1,3-dihydro isobenzofuran and 2-(1,1-disubstituted hydroxymethyl) benzamide derivatives have been obtained by the aminolysis of phthalide in the presence of triethylamine/aluminum chloride. 1-Benzylimino-3,3-disubstituted-1,3-dihydro isobenzofuran can be peroxidized to the corresponding hydroperoxides on exposure to the air for a long period. The structure was characterized by single crystal X-ray diffraction and the possible mechanism was suggested.

关键词： phthalide hydroperoxide aminolysis

Observer-based multi-objective parametric design for spacecraft with super flexible netted antennas

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Science China(Information Sciences) 2020年第7期63卷 161-181页

作者： guang-Ren DUAN tian-Yi ZHAO Center for Control Theory and Guidance Technology Harbin Institute of Technology

A multi-objective parametric design method that based on the robust observer is proposed for the attitude control of satellites with super flexible netted antennas. First, a parametric observer-based controller is obtained based on the eigen-structure assignment theory. The closed-loop poles are assigned to desired positions or regions, and full degrees of freedom of the design, which are characterized by a set of parameters, are preserved under the proposed control law. Second, the obtained parameters are comprehensively optimized to make the closed-loop system have lower eigenvalue sensitivity, a smaller control gain, and stronger tolerance to high-order unmodeled dynamics and external disturbances. Finally, comparative simulations are carried out based on practical engineering parameters of a satellite in order to verify the effect of the proposed method, and also to show their superiority over the traditional proportional-integral-derivative(PID) controller with filters and the traditional dynamic compensators.

关键词： parametric design of control systems multi-objective designs robust observers super flexible spacecraft parameter perturbations high-order flexible modes

A Novel Self-Supervised Learning Network for Binocular Disparity Estimation

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 209-229页

作者： Jiawei tian Yu Zhou Xiaobing Chen Salman A.AlQahtani Hongrong Chen Bo Yang Siyu Lu Wenfeng Zheng Department of Computer Science and Engineering Major in Bio Artificial IntelligenceHanyang UniversityAnsan-si15577Republic of Korea School of Electrical and Computer Engineering Louisiana State UniversityBaton RougeLA 70803USA Department of Computer Engineering College of Computer and Information SciencesKing Saud UniversityRiyadh11574Saudi Arabia School of Automation University of Electronic Science and Technology of ChinaChengdu610054China

Two-dimensional endoscopic images are susceptible to interferences such as specular reflections and monotonous texture illumination,hindering accurate three-dimensional lesion reconstruction by surgical *** study proposes a novel end-to-end disparity estimation model to address these *** approach combines a Pseudo-Siamese neural network architecture with pyramid dilated convolutions,integrating multi-scale image information to enhance robustness against lighting *** study introduces a Pseudo-Siamese structure-based disparity regression model that simplifies left-right image comparison,improving accuracy and *** model was evaluated using a dataset of stereo endoscopic videos captured by the Da Vinci surgical robot,comprising simulated silicone heart sequences and real heart video *** results demonstrate significant improvement in the network’s resistance to lighting interference without substantially increasing ***,the model exhibited faster convergence during training,contributing to overall performance *** study advances endoscopic image processing accuracy and has potential implications for surgical robot applications in complex environments.

关键词： Parallax estimation parallax regression model self-supervised learning Pseudo-Siamese neural network pyramid dilated convolution binocular disparity estimation

Statistical study of the properties of the magnetic field and plasma in the earth's magnetotail near lunar orbit

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Science China(Technological Sciences) 2012年第9期55卷 2570-2577页

作者： tian tian zong QiuGang WANG YongFu FEI ZengPing Mailbox 5111 Beijing 100094China Science and Technology on Aerospace Flight Dynamics Laboratory Beijing 100094China Institute of Space Physics and Applied Technology Peking UniversityBeijing 100871China

Based on the magnetic field and plasma data obtained by GEOTAIL in 1992-1995 and WIND in1994-2009, the magnetic field and plasma properties in the magnetotail near lunar orbit were studied statistically using the superposed epoch analysis. The results showed that near the 0° sector the plasma density was negatively correlated with Dst index while the temperature was positively correlated with Dst index. The plasma velocity and magnetic field strength had little correlation with Dst index. Around the current sheet near the lunar orbit, the Bx varied between -15-15 nT, the plasma density was less than 0.4 cm^-3, the median of plasma density for all events was less than 0.1 cm^-3, the temperature varied from 0.016 to 8.98 keV, the median of the plasma temperature for all the events was -3 keV, the median of speed was about 200 km/s and the maximum speed was up to 1500 km/s. The tailward and earthward flows could be observed accompanied with the current sheet. For the current sheet cases with tailward flow, the Bx varied from -15 to 15 nT, the upper quartile of plasma velocity was more than 400 krn/s, the maximum speed was up to 1500 km/s. For the current sheet cases with tailward flow, the Bx varied from -10 to 10 nT, the upper quartile of plasma velocity was less than 400 km/s, the maximum speed was up to 1200 km/s. The median of plasma density, temperature and velocity were similar for the two categories. This paper discussed the relationship between above results and magnetic reconnection at magnetic tail, compared the above results with the observation in the far magnetotail. We fitted the statistical results according to the Harris current sheet model, and the observation was consistent with Harris current sheet model. The above results can provide useful information for the design and protection of lunar-orbiting spacecraft and can be used as the background magnetic field and plasma parameters in the numerical simulation of mid-magnetotail reconnection.

关键词： lunar space weather plasma current sheet storm superposed epoch analysis

Super twisting sliding mode control for a flexible air-breathing hypersonic vehicle based on disturbance observer

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Science China(Information Sciences) 2015年第7期58卷 84-98页

作者： zong Qun DONG Qi WANG Fang tian BaiLing College of Electric Engineering and Automation Tianjin University School of Science Yanshan University

A robust finite time sliding mode control strategy is proposed in this paper for a flexible air-breathing hypersonic vehicle(FAHV) model with aerodynamic parameter uncertainty. The strong coupling among the aerodynamics, the propulsion system and the flexibility effects makes the problem more challenging. Firstly, to reduce the complexity of the controller design, the FAHV model is transformed into three subsystems(velocity subsystem, altitude and flight path angle subsystem, attack of angle and pitch rate subsystem). Secondly, based on super-twisting algorithm, a novel finite time disturbance observer and an improved sliding mode controller are designed to ensure the finite time stability of each subsystem. The proposed disturbance observer can estimate the uncertainty and the derivative of virtual control in finite time. Finally, simulation results are presented to show the precision and rapidness in tracking the reference trajectory and validate the effectiveness of the designed controller.

关键词： flexible air-breathing hypersonic vehicle(FAHV) disturbance observer sliding mode control super-twisting algorithm finite time s

Cloud detection from visual band of satellite image based on variance of fractal dimension

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Journal of Systems Engineering and Electronics 2019年第3期30卷 485-491页

作者： tian Pingfang guang Qiang LIU Xing School of Computer Science and Technology Wuhan University of Science and Technology Wuhan 430065 China Key Laboratory of Intelligent Information Processing and Real-Time Industrial System in Hubei Province Wuhan 430065 China Institute of Big Data Science and Engineering Wuhan University of Science and Technology Wuhan 430065 China Key Laboratory of Rich-Media Knowledge Organization and Service of Digital Publishing Content National Press and Publication Administration Beijing 100038 China

Cover ratio of cloud is a very important factor which affects the quality of a satellite image, therefore cloud detection from satellite images is a necessary step in assessing the image quality. The study on cloud detection from the visual band of a satellite image is developed. Firstly, we consider the differences between the cloud and ground including high grey level, good continuity of grey level, area of cloud region, and the variance of local fractal dimension (VLFD) of the cloud region. A single cloud region detection method is proposed. Secondly, by introducing a reference satellite image and by comparing the variance in the dimensions corresponding to the reference and the tested images, a method that detects multiple cloud regions and determines whether or not the cloud exists in an image is described. By using several Ikonos images, the performance of the proposed method is demonstrated.

关键词： cloud detection visual image satellite image variance of local fractal dimension (VLFD)