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Deep learning-based multi-source precipitation merging for the Tibetan Plateau

Science China Earth Sciences 2023年第4期66卷 852-870页

作者： Tianyi nan Jie CHEN Zhiwei ding Wei LI Hua CHEN State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Hubei Provincial Key Lab of Water System Science for Sponge City Construction Wuhan UniversityWuhan 430072China

Due to its complex and diverse terrain, precipitation gauges in the Tibetan Plateau(TP) are sparse, making it difficult to obtain reliable precipitation data for environmental studies. Data merging is a method that can integrate precipitation data from multiple sources to generate high-precision precipitation data. However, the more commonly used methods, such as regression and machine learning, do not usually consider the local correlation of precipitation, so that the spatial pattern of precipitation cannot be reproduced, while deep learning methods do incorporate spatial correlation. To explore the ability of using deep learning methods in merging precipitation data for the TP, this study compared three methods: a deep learning method—a convolutional neural network(CNN) algorithm, a machine learning method—an artificial neural network(ANN) algorithm, and a statistical method based on Extended Triple Collocation(ETC) in merging precipitation from multiple sources(gauged, grid,satellite and dynamic downscaling) over the TP, as well as their performance for hydrological simulations. Dynamic downscaling data driven by global reanalysis data centered on the TP were introduced in the merging process to better reflect the spatial variability of precipitation. The results show that:(1) in terms of the meteorological metrics, the merged data perform better than the gauge interpolation data. By using data merging, the error between the raw multi-source and gauged precipitation can be reduced, and the precipitation detection capability can be greatly improved;(2) The merged precipitation data also perform well in the hydrological evaluation. The Xin’anjiang(XAJ) model parameter calibration experiments at the source of the Yangtze River(SYR) and the source of the Yellow River(SHR) were repeated 300 times to remove uncertainty in the model parameter results. The median Kling-Gupta Efficiency Coefficients(KGE) of simulated runoff from the merged data of the ANN, CNN and ETC me

关键词： Tibetan Plateau Precipitation data merging Deep learning Dynamic downscaling

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Characteristics of Fluid Flow and Temperature Field of Twin-roll Steel Strip Casting with a Novel-type Delivery System

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Journal of Iron and Steel Research International 2015年第10期22卷 885-891页

作者： jian-hong DONG Min CHEN nan WANG School of Materials and Metallurgy Northeastern University

A novel-type delivery system consisting of a special feeding device and delivery device was developed and applied to a φ600 mm× 1 000 mm twin-roll casting system for producing the steel strip of 2 mm in thickness, and the characteristics of fluid flow and temperature field in the casting pool were investigated by mathematical simulation. The results showed that the melt from the novel-type delivery system was distributed to the casting pool along the width direction smoothly and uniformly. At the casting speed of 80 m/min, the difference of minimum residence time （groin） and actual average residence time （tave） among different ports of the delivery device was less than 0.18 s and 0.26 s respectively, and the average amplitude of level fluctuation was 0.3 mm to 0.6 mm on the free surface of casting pool. In addition, the difference of temperature on the free surface of the pool was below 20 K and the difference across the width direction of roll in different pool depths was less than 13 K, which indicates that the uniformity of temperature distribution was obtained in the casting pool to maintain the casting process and the defect-free steel strip can also be obtained.

关键词： twin-roll strip casting novel-type delivery system fluid flow temperature field mathematical simulation

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A new green system of HPW@MOFs catalyzed desulfurization using O_2 as oxidant

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Chinese Chemical Letters 2016年第5期27卷 655-658页

作者： jian-Wei ding Rui Wang School of Environmental Science & Engineering Shandong University Department of Environmental Science and Engineering Shandong University

A series of crystalline compounds were obtained from simple one-step hydrothermal reaction of copper nitrate, benzentricaboxylate and different Keggin polyoxometalates. Phosphotungstic acid immobilized in host matrix was selected for the first time as a recyclable and efficient catalyst in oxidative desulfurization process, under eco-sustainable conditions supported by the green oxidant O2 and the green extracting agent distilled water. The efficiency of desulfurization with air was studied and it is possible to use air as green oxidant in desulfurization. Moreover, the catalyst is effective for the desulfurization of real diesel.

关键词： Oxidative desulfurization Metal organic frameworks OxygenReal dieselRecyclability

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Confidentiality-aware message scheduling for security-critical wireless networks

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Journal of Systems Engineering and Electronics 2010年第1期21卷 154-160页

作者： Wei jiang Guangze Xiong Xuyang ding Zhengwei Chang nan Sang College of Computer Science and Engineering University of Electronic Science and Technology of China Chengdu 610054 E R. China

Without considering security, existing message scheduling mechanisms may expose critical messages to malicious threats like confidentiality attacks. Incorporating confidentiality improvement into message scheduling, this paper investigates the problem of scheduling aperiodc messages with time-critical and security-critical requirements. A risk-based security profit model is built to quantify the security quality of messages; and a dynamic programming based approximation algorithm is proposed to schedule aperiodic messages with guaranteed security performance. Experimental results illustrate the efficiency and effectiveness of the proposed algorithm.

关键词： security-critical wireless networks confidentialityaware real-time message scheduling.

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Fluid Mud Measurement and Siltation Analysis in A Trial Excavated Channel in the Approach Channel of the Xiangshan Port

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China Ocean Engineering 2020年第3期34卷 421-431页

作者： ding jian HU Guo-dong WANG Zhen-xiang SHI jian WU De-an Key Laboratory of Coastal Disasters and Defence Ministry of EducationHohai UniversityNanjing 210098China Yangtze River Estuary Investigation Bureau of Hydrology and Water Resource Shanghai 200136China

In order to clarify the distribution and variation of silt and fluid mud in the Waiganmen shallow section of the 50000-ton intake channel of the Xiangshan Port,and to understand the influence of the channel excavation on the surrounding flow conditions and the strength of the backsilting,especially the impact of typhoon on the sudden silting of the channel,so as to demonstrate the feasibility and stability of the channel *** fluid mud,hydraulic,sediment and topographic measurements were carried out in the study area,and the thickness of the fluid mud layers,tidal current,sediment and topographic data were ***-frequency sounder,gamma-ray densitometer and SILAS navigational fluid mud measurement system were used to monitor the fluid mud,and the results were compared and *** adaptability and accuracy of the three methods were *** SILAS navigational continuous density measurement system and gamma-ray fixed-point fluid mud measurement are used to detect the density,thickness and variation of the fluid mud *** on the hydrological observation data,the process of erosion and deposition in excavation channel and its influence mechanism are analyzed,and the distribution characteristics and evolution law of siltation in engineering area are given in the form of empirical *** research shows that the super typhoon can produce large siltation,which results in sudden siltation of the *** tidal current is the main dynamic factor of the change of erosion and siltation of the excavation *** the influence of reciprocating tidal current and excavation topography,the trial excavation trench is silted on the *** is fluid mud in the monitoring area of the trench,and the distribution of fluid mud is different in *** thickness of the fluid mud at the bottom of the trench is generally larger than that outside the trench and the slope of the trench,and the siltation of the trench tends to be *** re

关键词： excavation trench fluid mud backsilting measurement tidal current dynamic mechanism

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The Local and Global Existence of Solutions for a Generalized Camassa-Holm Equation

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Acta Mathematica Sinica,English Series 2013年第4期29卷 757-776页

作者： Shao Yong LAI nan LI jian ZHANG Department of Mathematics Southwestern University of Finance and Economics Department of Mathematics Sichuan Normal University

A fully nonlinear generalization of the Camassa-Holm equation is investigated. Using the 3 pseudoparabolic regularization technique, its local well-posedness in Sobolev space Hs（R） with s 〉 is established via a limiting procedure. Provided that the initial momentum （1 - 02）u0 satisfies the sign condition,the existence and uniqueness of global solutionsfor the equation are shown to be true in the space C.

关键词： Existence of global solutions Camassa-Holm type equation Pseudoparabolic regulariza-tion method

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Deformation Mechanism and Hot Workability of Extruded Magnesium Alloy AZ31

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Acta Metallurgica Sinica(English Letters) 2018年第1期31卷 71-81页

作者： Zhao-Yang Jin nan-nan Li Kai Yan jian Wang Jing Bai Hongbiao Dong School of Mechanical Engineering Yangzhou University School of Physics and Optoelectronic Engineering Nanjing University of Information Science and Technology School of Materials Science and Engineering Southeast University Department of Engineering University of Leicester

Using the flow stress curves obtained by Gleeble thermo-mechanical testing, the processing map of extruded magnesium alloy AZ31 was established to analyze the hot workability. Stress exponent and activation energy were calculated to characterize the deformation mechanism. Then, the effects of hot deformation parameters on deformation mechanism, microstructure evolution and hot workability of AZ31 alloy were discussed. With increasing deformation temperature, the operation of non-basal slip systems and full development of dynamic recrystallization （DRX） contribute to effective improvement in hot workability of AZ31 alloy. The influences of strain rate and strain are complex. When temperature exceeds 350 ℃, the deformation mechanism is slightly dependent of the strain rate or strain. The dominant mechanism is dislocation cross-slip, which favors DRX nucleation and grain growth and thus leads to good plasticity. At low temperature （below 350 ℃）, the deformation mechanism is sensitive to strain and strain rate. Both the dominant deformation mechanism and inadequate development of DRX deteriorate the ductility of AZ31 alloy. The flow instability mainly occurs in the vicinity of 250 ℃ and 1 s^-1.

关键词： Hot workability. Deformation mechanism Dynamic recrystallization Activation energy Magnesium alloy

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Computing Degree of Maps Between Manifolds

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Acta Mathematica Sinica,English Series 2005年第6期21卷 1277-1284页

作者： Yan Hong ding jian Zhong PAN Department of Mathematics Hebeg Normal University Shijiazhuang 050016 P. R. China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 P. R. China

We determine the degrees of maps between two given closed （n-1）-connected 2n-mamifolds when n ≡ 1 （mod 8）.

关键词： 2n-manifolds degree

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A new dataset of dog breed images and a benchmark for fine-grained classification

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Computational Visual Media 2020年第4期6卷 477-487页

作者： ding-nan Zou Song-Hai Zhang Tai-jiang Mu Min Zhang Department of Computer Science and Technology BNRistTsinghua UniversityBeijing 100084China NaJiu Company Hunan 410022China Harvard Medical School Brigham and Women’s HospitalBostonMA 02115USA

In this paper, we introduce an image dataset for fine-grained classification of dog breeds: the Tsinghua Dogs Dataset. It is currently the largest dataset for fine-grained classification of dogs, including 130 dog breeds and 70,428 real-world images. It has only one dog in each image and provides annotated bounding boxes for the whole body and head. In comparison to previous similar datasets, it contains more breeds and more carefully chosen images for each breed. The diversity within each breed is greater,with between 200 and 7000+ images for each *** of the whole body and head makes the dataset not only suitable for the improvement of finegrained image classification models based on overall features, but also for those locating local informative parts. We show that dataset provides a tough challenge by benchmarking several state-of-the-art deep neural models. The dataset is available for academic purposes at https://***/ThuDogs/.

关键词： fine-grained classification dog dataset benchmark

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Isometric Extension Problem Between Strictly Convex Two-dimensional Normed Spaces

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Acta Mathematica Sinica,English Series 2019年第4期35卷 513-518页

作者： Guang Gui ding jian Ze LI School of Mathematical Sciences and LPMC Nankai University Electrical and Computer Engineering Ryerson University

In this paper, based on the smooth point of the unit ball and its support linear functional,we show two equivalent formulations of the isometric extension problem between the unit spheres of strictly convex two-dimens... 详细信息

关键词： Isometric extension strictly convex unit sphere smooth point additive map

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