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Fast parallel Grad–Shafranov solver for real-time equilibrium reconstruction in EAST tokamak using graphic processing unit

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Chinese Physics B 2017年第8期26卷 276-283页

作者：黄耀肖炳甲罗正平 Institute of Plasma Physics Chinese Academy of Sciences school of Nuclear science & Technology University of Science & Technology of China

To achieve real-time control of tokamak plasmas, the equilibrium reconstruction has to be completed sufficiently quickly. For the case of an EAST tokamak experiment, real-time equilibrium reconstruction is generally required to provide results within 1ms. A graphic processing unit（GPU） parallel Grad–Shafranov（G-S） solver is developed in P-EFIT code,which is built with the CUDA？ architecture to take advantage of massively parallel GPU cores and significantly accelerate the computation. Optimization and implementation of numerical algorithms for a block tri-diagonal linear system are presented. The solver can complete a calculation within 16 μs with 65×65 grid size and 27 μs with 129×129 grid size, and this solver supports that P-EFIT can fulfill the time feasibility for real-time plasma control with both grid sizes.

关键词： tokamak Grad-Shafranov equation equilibrium reconstruction GPU parallel computation

Gradient Elastic–Plastic Properties of Expanded Austenite Layer in 316L Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2018年第8期31卷 831-841页

作者： Yong Jiang Yang Li Yun-Fei Jia Xian-Cheng Zhang Jian-Ming Gong school of Mechanical and Power Engineering Nanjing University of TechnologyNanjing 211816China Key Laboratory of Design and Manufacture of Extreme Pressure Equipment Nanjing 211816Jiangsu ProvinceChina Key Laboratory of Pressure system and Safety MOESchool of Mechanical and Power EngineeringEast China Universityof Science and TechnologyShanghai 200237China

The gradient mechanical properties, variation of stress with strain and surface cracking behavior of expanded austenite developed on 316L austenitic stainless steel were investigated by nanoindentation tests, X-ray residual stress analysis and scanning electron microscope observation in four-point bending tests. The results show that the plastic properties of the carburizing layer including true initial yield strengths and strain hardening exponents increase significantly from substrate to surface, while the true elastic modulus just improves slightly. Due to the onset of plastic flow, the residual stresses are almost equivalent to the true initial yield strengths from surface to the depth of ～10 lm. The results of four-point bending tests show that surface stress increases linearly with the increase in strain until the strain reaches～1.0%, after that the plastic yield happens. The expanded austenite surface layer is brittle, and the cracks will be created at the strain of ～1.4%.The cracking stress is about～2.4 GPa.

关键词： Low-temperature gaseous carburization Expanded austenite Nanoindentation Gradient elastic-plastic properties Four-point bending

Design and analysis of a novel hinged boom based on cable drive

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Chinese Journal of Aeronautics 2022年第3期35卷 592-606页

作者： Kaijie DONG Duanling LI Qiuhong LIN Hui QIU Qiang CONG Xiao LI school of Automation Beijing University of Posts and TelecommunicationsBeijing 100876China College of Mechanical and Electrical Engineering Shaanxi University of Science and TechnologyXi’an 712000China Beijing Institute of Spacecraft system Engineering China Academy of Space TechnologyBeijing 100094China

Hinged booms are widely used in astrophysics missions;however,the trajectory and deployment velocity are difficult to control because they are usually driven by springs,which limits their application in narrow ***,a novel hinged boom is highly required to achieve motion *** an equivalent substitution between the cable drive loop and the binary link in topology,a type synthesis method for the cable-driven single-degree-of-freedom chain is proposed based on the single-open-chain(SOC)adding *** to the configuration design,a novel cable-driven hinged boom is proposed,aiming to achieve boom ***,to preload easily,a method that preload is applied and measured at the cable ends is adopted and the relationship between the initial preload and the target preload is *** analyzing the distribution of cable tension,a new stiffness model is proposed thus a stiffness equation is ***,the dynamic simulation analysis and zero-gravity deployment experiment of the hinged boom is carried out to verify its *** research provides a new way for the type synthesis of cable-driven single-degree-of-freedom chain and a new model for analyzing cable-driven ***,the novel cable-driven hinged boom obtained in this study can be well-applied in the field of aerospace.

关键词： Cable drive Deployable structure Dynamic simulation Hinged boom Stiffness Type synthesis

On Observability and Detectability of Continuous-Time Stochastic Markov Jump systems

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Journal of systems science & Complexity 2015年第4期28卷 830-847页

作者： TAN Cheng ZHANG Weihai school of Control science and Engineering Shandong University College of Electrical Engineering and Automation Shandong University of Science and Technology

This paper mainly studies observability and detectability for continuous-time stochastic Markov jump *** concepts called W-observability and W-detectability for such systems are introduced,which are shown to coincide with various notions of observability and detectability reported recently in literature,such as exact observability,exact detectability and ***,by introducing an accumulated energy function,some efficient criteria and interesting properties for both W-observability and W-detectability are obtained.

关键词： Continuous-time stochastic system detectability Markov jump observability.

PGG:An Online Pattern Based Approach for Stream Variation Management

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Journal of Computer science & Technology 2008年第4期23卷 497-515页

作者：唐绿岸崔斌李红燕苗高杉杨冬青周新彪 Department of Computer science University of Illinois at Urbana-Champaign school of Electronics Engineering and Computer science Peking University

Many database applications require efficient processing of data streams with value variations and fluctuant sampling frequency. The variations typically imply fundamental features of the stream and important domain knowledge of underlying objects. In some data streams, successive events seem to recur in a certain time interval, but the data indeed evolves with tiny differences as time elapses. This feature, so called pseudo periodicity, poses a new challenge to stream variation management. This study focuses on the online management for variations over such streams. The idea can be applied to many scenarios such as patient vital signal monitoring in medical applications. This paper proposes a new method named Pattern Growth Graph （PGG） to detect and manage variations over evolving streams with following features： 1） adopts the wave-pattern to capture the major information of data evolution and represent them compactly; 2） detects the variations in a single pass over the stream with the help of wave-pattern matching algorithm; 3） only stores different segments of the pattern for incoming stream, and hence substantially compresses the data without losing important information; 4） distinguishes meaningful data changes from noise and reconstructs the stream with acceptable accuracy. Extensive experiments on real datasets containing millions of data items, as well as a prototype system, are carried out to demonstrate the feasibility and effectiveness of the proposed scheme.

关键词： data stream noise reorganization pattern representation variation management

Hollow vortex Gaussian beams

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science China(Physics,Mechanics & Astronomy) 2013年第5期56卷 896-903页

作者： ZHOU GuoQuan CAI YangJian DAI ChaoQing school of sciences Zhejiang A & F University school of Physical science and Technology Soochow University

A kind of hollow vortex Gaussian beam is introduced. Based on the Collins integral, an analytical propagation formula of a hollow vortex Gaussian beam through a paraxial ABCD optical system is derived. Due to the special distribution of the optical field, which is caused by the initial vortex phase, the dark region of a hollow vortex Gaussian beam will not disappear upon propagation. The analytical expressions for the beam propagation factor, the kurtosis parameter, and the orbital angular mo- mentum density of a hollow vortex Gaussian beam passing through a paraxial ABCD optical system are also derived, respec- tively. The beam propagation factor is determined by the beam order and the topological charge. The kurtosis parameter and the orbital angular momentum density depend on beam order n, topological charge m, parameter y, and transfer matrix ele- ments A and D. As a numerical example, the propagation properties of a hollow vortex Gaussian beam in free space are demonstrated. The hollow vortex Gaussian beam has eminent propagation stability and has crucial application prospects in op- tical micromanipulation.

关键词： hollow vortex Gaussian beam beam propagation factor kurtosis parameter orbital angular momentum density

The Irregular Linear Quadratic Control Problem for Deterministic Case with Time Delay

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Journal of systems science & Complexity 2021年第2期34卷 642-656页

作者： LI Tongxing LI Lin LEI Jing JIN Nana JU Peijun school of math.matics and Statistics Taishan UniversityTaian 271000China school of Information science and Engineering Shandong Agricultural UniversityTaian 271000China school of Control science and Engineering Shandong UniversityJinan 250061China

This study deals with the irregular linear quadratic control problem governed by continuous time system with time *** quadratic(LQ)control for irregular Riccati equation with time delay remains challenging since the controller could not be solved from the equilibrium condition *** merit of this paper is that based on a new approach of‘two-layer optimization’,the controller entries of irregular case with time delay are deduced from two equilibrium conditions in two different layers,which is fundamentally different from the classical regular LQ *** authors prove that the irregular LQ with time delay is essentially different from the regular ***,the predictive controller bases on the feedback gain matrix and the state is given in the last *** presented conclusions are completely new to our best *** is presented to show the effectiveness of the proposed approach.

关键词： Forward and backward differential equations(FBDEs) irregular Riccati equation time delay system

New perspectives in free nitrous acid (FNA) uses for sustainable wastewater management

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Frontiers of Environmental science & Engineering 2024年第2期18卷 161-168页

作者： Zhiqiang Zuo Min Zheng Tao Liu Yongzhen Peng Zhiguo Yuan National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology Engineering Research Center of BeijingBeijing University of TechnologyBeijing 100124China Australian Centre for Water and Environmental Biotechnology The University of QueenslandSt.LuciaQLD 4072Australia Water Research Centre School of Civil and Environmental EngineeringUniversity of New South WalesSydneyNew South Wales 2052Australia Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHung HomKowloonHong Kong 999077China school of Energy and Environment City University of Hong KongHong Kong 999077China

The biocidal effects of free nitrous acid (FNA) have found applications in multiple units in an urban wastewater system, including sewer networks, wastewater treatment processes, and sludge treatment processes. However, these applications are associated with chemical costs as both nitrite and acid are needed to produce FNA at the required levels. The recent discovery of novel acid-tolerant ammonia oxidizers offers the possibility to produce FNA from domestic wastewater, enabling the development of next-generation FNA-based technologies capable of achieving self-sustaining FNA production. In this study, we focus on the concept of in situ FNA generation facilitated by acid-tolerant ammonia oxidizers and highlight the multiple benefits it creates, after a brief review of the historical development of FNA-based technologies. We will discuss how wastewater systems can be made more energy-efficient and sustainable by leveraging the potential of acid-tolerant ammonia oxidizers.

关键词： Free nitrous acid Acid-toler antammonia oxidizer In situ generationl Wastewater management

Debris flow susceptibility mapping in mountainous area based on multi-source data fusion and CNN model-taking Nujiang Prefecture,China as an example

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International Journal of Digital Earth 2022年第1期15卷 1966-1988页

作者： Fanshu Xu Baoyun Wang school of Information science and Technology Yunnan Normal UniversityKunmingPeople’s Republic of China school of math.matic Yunnan Normal UniversityKunmingPeople’s Republic of China Key Laboratory of Complex system Modelling and Application Yunnan Normal UniversityKunmingPeople’s Republic of China

Efforts to evaluate the susceptibility of debris flows in large areas,especially in mountainous regions,are often hampered by the alpine and canyon *** paper proposes a convolution neural network(CNN)model named dense residual shuffle net(DRSNet).It is successfully applied to Nujiang Prefecture in Yunnan Province of China,a typical alpine area with frequent debris *** uses digital elevation model,remote sensing,lithology,soil type and precipitation data as ***,dense connection and residual structure were used to extract the shallow features of various ***,channel shuffle,fuse block and fully connection were applied to strengthen the correlation between different shallow features and give inner danger ***,precipitation as the activation factor was introduced giving the valleys *** verify the feasibility of DRSNet,comparative tests were conducted on 7 CNN models and 3 other machine learning(ML)*** results show that DRSNet can achieve 78.6%accuracy in debris flow valley classification,which is at least 7.4%higher than common CNN models and 15.2%higher than other ML *** article provides new ideas for debris flow susceptibility evaluation.

关键词： Debris flow disaster prediction convolutional neural networks mountainous valleys