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A reusable planar triggered spark-gap switch batched-fabricated with PCB technology for medium- and low-voltage pulse power systems

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Defence Technology（防务技术） 2021年第4期17卷 1572-1578页

作者： Zhi Yang Ke Wang Peng Zhu Peng Liu Qiu Zhang cong xu Hao-tian jian Rui-qi Shen School of Chemical Engineering Nanjing University of Science and TechnologyNanjing210094China Key Laboratory of Special Energy Materials Ministry of EducationNanjing210094China Micro-Nano Energetic Devices Key Laboratory Ministry of Industry and Information TechnologyNanjing210094China

Triggered spark-gap switch is a popular discharge switch for pulse power *** studies have focused on planarizing this switch using thin film techniques in order to meet the requirements of compact size in the *** switches are one-shot due to electrodes being too thin to sufficiently resist ***,these switches did not employ any structures in securing internal gas composition,resulting in inconsistent performance under harsh *** this work,a novel planar triggered spark-gap switch(PTS)with a hermetically sealed cavity was batched-prepared with printed circuit board(PCB)technology,to achieve reusability with low *** proposed PTS was inspected by micro-computed tomography to ensure PCB techniques meet the requirements of machining *** results from electrical experiments demonstrated that PCB PTS were consistent and reusable with lifespan over 20 *** calculated switch voltage and circuit current were consistent with those derived from real-world ***,PCB PTS was used to introduce hexanitrostilbene(HNS)pellets in a pulse power system to verify its performance.

关键词： Pulse power systems Printed circuit board technology Triggered spark-gap switch Planar discharge switch Electrical performance

Detection of gross errors using mixed integer optimization approach in process industry

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第6期8卷 904-909页

作者： MEI cong-li SU Hong-ye CHU jian National Laboratory of Industrial Control Technology Institute of Advanced Process Control Zhejiang University Hangzhou 310027 China

A novel mixed integer linear programming (NMILP) model for detection of gross errors is presented in this paper. Yamamura et al.(1988) designed a model for detection of gross errors and data reconciliation based on Akaike information cri- terion (AIC). But much computational cost is needed due to its combinational nature. A mixed integer linear programming (MILP) approach was performed to reduce the computational cost and enhance the robustness. But it loses the super performance of maximum likelihood estimation. To reduce the computational cost and have the merit of maximum likelihood estimation, the simultaneous data reconciliation method in an MILP framework is decomposed and replaced by an NMILP subproblem and a quadratic programming (QP) or a least squares estimation (LSE) subproblem. Simulation result of an industrial case shows the high efficiency of the method.

关键词： Data reconciliation Detection of gross errors Mixed integer linear programming (MILP) Novel MILP (NMILP) Quadratic programming (QP)

Oxidation and Induration Characteristics of Pellets Made from Western Australian Ultrafine Magnetite Concentrates and Its Utilization Strategy

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Journal of Iron and Steel Research International 2016年第9期23卷 924-932页

作者： cong-cong YANG De-qing ZHU jian PAN Bin-zhi ZHOU Hu xuN Department of Ferrous Metallurgy Central South University

Western Australian magnetite concentrates normally have ultrafine granularity and much higher specific surface areas than Chinese magnetite concentrates owing to the significant pre-grinding and beneficiation for saleable iron grade. Such characteristics will inevitably affect the subsequent pelletization process. However, very few investi- gations have been done before. Thus, the oxidation and induration characteristics of pellet made from a Western Aus- tralian ultrafine magnetite concentrate were revealed by conducting routine preheating-roasting tests in an electric tube furnace and investigating the microstructure of fired pellets under an optical microscope in comparison with that of pellets made from typical Chinese magnetite concentrate. The liquidus regions of CaO-SiO2-Fe2O3 and CaO-SiO2- Al2O3 ternary systems in air at various temperatures were calculated by FactSage software to explain the importance of liquid phase in the consolidation of fired pellets. The results show that pellet made from ultrafine magnetite con- centrate possesses better oxidability and preheating performance than that made from Chinese magnetite concentrate. However, it has inferior roasting performance, usually requiring conditions of roasting at 1280℃ for at least 30 rain to acquire sufficiently high compressive strength, which are attributed to higher temperature sensitivity caused by its smaller particle size and less formation of liquid phase because of low impurities like CaO and Al2O3 in raw materials. Correspondingly, its roasting performanee can be significantly improved by blending with Chinese magnetite concen- trates or increasing the pellet basicity （WCaO/WSiO2）. By comprehensive evaluation, blending with Chinese iron ore concentrates is an appropriate way to utilize Western Australia ultrafine magnetite concentrates.

关键词： oxidation induration characteristic ultrafine magnetite concentrate iron ore pellet metallurgical performance

Pressure observer based adaptive robust trajectory tracking control of a parallel manipulator driven by pneumatic muscles

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第12期8卷 1928-1937页

作者： ZHU Xiao-cong TAO Guo-liang CAO jian The State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

This paper presents a pressure observer based adaptive robust controller (POARC) for posture trajectory tracking of a parallel manipulator driven by three pneumatic muscles without pressure sensors. Due to model errors of the static forces and friction forces of pneumatic muscles, simplified average flow rate characteristics of valves, unknown disturbances of entire system, and unmeasured pressures, there exist rather severe parametric uncertainties, nonlinear uncertainties and dynamic uncertainties in modeling of the parallel manipulator. A nonlinear pressure observer is constructed to estimate unknown pressures on the basis of a single-input-single-output (SISO) decoupling model that is simplified from the actual multiple-input-multiple-output (MIMO) coupling model of the parallel manipulator. Then, an adaptive robust controller integrated with the pressure observer is developed to accomplish high precision posture trajectory tracking of the parallel manipulator. The experimental results indicate that the system with the proposed POARC not only achieves good control accuracy and smooth movement but also maintains robustness to disturbances.

关键词： Pneumatic muscle Parallel manipulator Pressure observer Adaptive robust control Trajectory tracking

An analytical method for studying double Hopf bifurcations induced by two delays in nonlinear differential systems

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Science China(Technological Sciences) 2020年第4期63卷 597-602页

作者： GE JuHong xu jian Department of Mathematics and Information Science Henan University of Economics and LawZhengzhou 450046China Shanghai Institute of Intelligent Science and Technology Tongji UniversityShanghai 200092China

An analytical method is introduced to investigate double Hopf bifurcations induced by two delays qualitatively and *** an illustrative example,the clear procedure is demonstrated to study delay-induced weak resonant double Hopf bifurcation in a nonlinear system with multiple *** two delays are close to double Hopf bifurcation point,all solutions derived from the bifurcation are classified qualitatively and expressed *** simulations are a good agreement with our theoretical analysis,and also already work in *** results show that our work in this paper proposes a simple and valid method for investigating delay-induced double Hopf *** important feature of our work is that the explicit expression of periodic solutions is easy to be obtained by solving algebraic equations.

关键词： analytical methods multiple delays double Hopf bifurcation the coexistence of periodic motion

Heat transfer and flow structure in centrally-confined 2-D Rayleigh-Bénard convection

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Journal of Hydrodynamics 2024年第4期36卷 772-780页

作者： cong Sun jian-zhao Wu Xiao-hui Meng Cai-xi Liu Wei xu Yu-hong Dong Quan Zhou Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China China Electrical Equipment Group Research Institute of Science and Technology Co.Ltd. Shanghai200072China

Through direct numerical simulations,we investigated the flow structure and heat transfer of the centrally confined 2-D Rayleigh-Bénard(RB)convection over the Rayleigh number range 9×10^(5)≤Ra≤10^(9) at a fixed Prandtl number Pr=*** is found that with increasing Ra,the number of convection rolls in the central vertical channel increases from zero to *** there is no rolls in the vertical channel,the convective flow in central region is significantly influenced by the boundary layer,whereas when the convection rolls is generated in the vertical channel,the convective flows in central regions is free from the boundary layer limitation,and by defining the characteristic length,one obtains the heat transfer scaling law relation in vertical channel,i.e.,Nu_(vc)∼Ra_(vc)^(0.476±0.005),which could be the evidence of“ultimate regime”.

关键词： Rayleigh-Benard(RB)turbulence heat transport vertical channel ultimate regime

Development characteristics and controlling factors of fractures in lacustrine shale and their geological significance for evaluating shale oil sweet spots in the third member of the Shahejie Formation in the Qikou Sag, Bohai Bay Basin

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Petroleum Science 2024年第2期21卷 791-805页

作者： xu Zeng Tao Yang jian-Wei Feng cong-Sheng Bian Ming Guan Wei Liu Bing-Cheng Guo Jin Dong Research Institute of Petroleum Exploration and Development China National Petroleum CorporationBeijing100083China College of Geosciences China University of Petroleum(Beijing)Beijing102249China Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China School of Earth Sciences China University of PetroleumQingdao266400ShandongChina

Natural fractures are critical for shale oil and gas enrichment and development. Due to the extremely high heterogeneity of shale, the factors controlling the formation of internal fractures, especially horizontal fractures, remain controversial. In this study, we integrate thin section analysis and microcomputed tomography(CT) data from several lacustrine shale samples from the third member(Es3) of the Shahejie Formation, Qikou Sag, Bohai Bay Basin, to assess the fractures in detail. The goal is to reveal the development characteristics, controlling factors, and geological significance for evaluating sweet spots in a shale oil play. The fractures in the Es3contain high-angle structural and horizontal bed-parallel fractures that are mostly shear and extensional. Various factors influence fracture development,including lithofacies, mineral composition, organic matter content, and the number of laminae. Structural fractures occur predominantly in siltstone, whereas bed-parallel fractures are abundant in laminated shale and layered mudstone. A higher quartz content results in higher shale brittleness, causing fractures, whereas the transformation between clay minerals contributes to the development of bedparallel fractures. Excess pore pressure due to hydrocarbon generation and expulsion during thermal advance can cause the formation of bed-parallel fractures. The density of the bed-parallel and structural fractures increases with the lamina density, and the bed-parallel fractures are more sensitive to the number of laminae. The fractures are critical storage spaces and flow conduits and are indicative of sweet spots. The laminated shale in the Es3with a high organic matter content contains natural fractures and is an organic-rich, liquid-rich, self-sourced shale play. Conversely, the siltstone, massive mudstone, and argillaceous carbonate lithofacies contain lower amounts of organic matter and do not have bed-parallel fractures. However, good reservoirs can form in th

关键词： Fractures Development characteristics Controlling factors Shale oil Sweet spot

Reductivity and bundle shifts

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Applied Mathematics(A Journal of Chinese Universities) 2019年第1期34卷 27-32页

作者： xu An-jian College of Science Chongqing University of Technology

For the Hardy space H_E^2(R) over a ?at unitary vector bundle E on a ?nitely connected domain R, let TE be the bundle shift as [3]. If B is a reductive algebra containing every operator ψ(TE) for any rational functi... 详细信息

关键词： reductivity bundle shift multiply-connected domain

Probing microstructural evolution in weld metals subjected to varied CaF_(2)-TiO_(2) flux cored wires under high heat input electro-gas welding

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Journal of Iron and Steel Research International 2023年第1期30卷 150-157页

作者： xu Xie Ming Zhong Tan Zhao cong Wang Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200444China State Key Laboratory of Metal Material for Marine Equipment and Application Ansteel Co.Ltd.Anshan 114021LiaoningChina

Fused CaF_(2)-TiO_(2) fluxes have been designed,prepared,and applied in the flux cored wires to join EH36 shipbuilding steels under high heat input electro-gas *** microstructural evolution in the weld metals subjected to varied CaF_(2)-TiO_(2) flux cored wires has been fully *** has been demonstrated that as the content of TiO2 in the fused fluxes increases,columnar grain size increases,and major constituents in the weld metal change from lath bainite,to granular bainite,and then to acicular *** phenomena are elucidated via salient chemical reactions involving oxygen pickup and concurrent titanium transfer.

关键词： Microstructural evolution Elemental variation Electro-gas welding High heat input Shipbuilding steel