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Equation governing the probability density evolution of multi-dimensional linear fractional differential systems subject to Gaussian white noise

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Theoretical & Applied Mechanics Letters 2023年第3期13卷 199-208页

作者： Yi Luo meng-ze lyu Jian-Bing Chen Pol D.Spanos George R.Brown School of Engineering Rice UniversityHouston 77005TXUSA Institute for Risk&Reliability Leibniz University HannoverHannover 30167Germany College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

Stochastic fractional differential systems are important and useful in the mathematics,physics,and engineering ***,the determination of their probabilistic responses is difficult due to their non-Markovian *** recently developed globally-evolving-based generalized density evolution equation(GE-GDEE),which is a unified partial differential equation(PDE)governing the transient probability density function(PDF)of a generic path-continuous process,including non-Markovian ones,provides a feasible tool to solve this *** the paper,the GE-GDEE for multi-dimensional linear fractional differential systems subject to Gaussian white noise is *** particular,it is proved that in the GE-GDEE corresponding to the state-quantities of interest,the intrinsic drift coefficient is a time-varying linear function,and can be analytically *** this sense,an alternative low-dimensional equivalent linear integer-order differential system with exact closed-form coefficients for the original highdimensional linear fractional differential system can be constructed such that their transient PDFs are ***,for a multi-dimensional linear fractional differential system,if only one or two quantities are of interest,GE-GDEE is only in one or two dimensions,and the surrogate system would be a one-or two-dimensional linear integer-order *** examples are studied to assess the merit of the proposed *** presently the closed-form intrinsic drift coefficient is only available for linear stochastic fractional differential systems,the findings in the present paper provide a remarkable demonstration on the existence and eligibility of GE-GDEE for the case that the original high-dimensional system itself is non-Markovian,and provide insights for the physical-mechanism-informed determination of intrinsic drift and diffusion coefficients of GE-GDEE of more generic complex nonlinear systems.

关键词： Globally-evolving-based generalized density evolution equation(GE-GDEE) Linear fractional differential system Non-Markovian system Analytical intrinsic drift coefficient Dimension reduction

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Degree sum conditions for hamiltonian index

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Applied Mathematics(A Journal of Chinese Universities) 2021年第3期36卷 403-411页

作者： LIU ze-meng XIONG Li-ming School of Mathematics and Statistics Beijing Institute of TechnologyBeijing 100081China School of Mathematics and Statistics Beijing Key Laboratory on MCAACIBeijing Institute of TechnologyBeijing 100081China

In this note,we show a sharp lower bound of min{Σ_(i=1)^(k)dG(u_(i)):u1u2...uk is a path of(2-)connected G}on its order such that(k-1)-iterated line graphs L^(k-1)(G)are hamiltonian.

关键词： iterated line graph hamiltonian index degree sum condition

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Phylogeny and biogeography of Maianthemum(Asparagaceae:Nolinoideae)revisited with emphasis on its divergence pattern in SW China

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Plant Diversity 2021年第2期43卷 93-101页

作者： Ran meng Ying meng Yong-Ping Yang ze-Long Nie Key Laboratory of Plant Resources Conservation and Utilization College of Biological Resources and Environmental SciencesJishou UniversityJishou 416000HunanChina Xishuangbanna Tropical Botanical Garden Chinese Academy of SciencesMengla 666303YunnanChina Kunming Institute of Botany Chinese Academy of SciencesKunming 650201YunnanChina

Maianthemum is a genus with more than 35 species from the tribe Polygonateae(Asparagaceae),widely distributed between North to Central Americas and eastern Asia with high diversity in the easternHimalayas to the Hengduan Mountains of SW *** most species from SW China form a well-supported clade,phylogenetic relationships within this clade remain *** a broad level of taxon sampling and an extensive character sampling fromeight DNA regions,this study intends to revisit the phylogeny and biogeography of the genus to better understand the divergence patterns of species from SW *** results suggested the monophyly of Maianthemum with recognition of nine strongly supported clades,but backbone relationships among these clades remained largely *** the SWChina clade,individuals from the same species are grouped into different *** results revealed that the fast radiation of the SWChina cladewas occurred in the eastern Himalayas,followed by subsequent radiation in the Hengduan Mountains in the *** disjunctions of Maianthemum in the Northern Hemisphere appear to have occurred multiple times during the late Miocene to the Pliocene,likely resulted by a combination of both vicariance and long-distance dispersal events.

关键词： Biogeography Eastern Asia Hengduan mountains Intercontinental disjunction Maianthemum North America

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Numerical Simulations of Liquid-Solid Flows in A Vertical Pipe by MPS-DEM Coupling Method

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China Ocean Engineering 2022年第4期36卷 542-552页

作者： XIE Feng-ze meng Qing-jie WAN De-cheng Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Wuhan Second Ship Design and Research Institute Wuhan 430205China

In the process of deep-sea mining,the liquid-solid flows in the vertical transportation pipeline are very *** the present work,an in-house solver MPSDEM-SJTU based on the improved MPS and DEM is developed for the simulation of hydraulic ***,three examples including the multilayer cylinder collapse,the Poiseuille flow and two-phase dam-break are used to validate the precision of the DEM model,the pipe flow model and MPS-DEM coupling model,***,the hydraulic conveying with coarse particles in a vertical pipe is *** solid particle distribution is presented and investigated in ***,the coupling method is successfully applied for the simulation of the liquid-solid flows in a vertical pipe with rotating blades,which shows the stability of the solver under rotating boundary *** fully Lagrangian model is expected to be a new approach for analyzing hydraulic conveying.

关键词： liquid-solid flows MPS DEM vertical pipe rotating boundary conditions

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An in situ Digital Background Calibration Algorithm for Multi-Channel R-βR Ladder DACs

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Journal of Electronic Science and Technology 2022年第1期20卷 43-54页

作者： Liang-Jian lyu Qing-Zhen Wang ze-Peng Huang Xing Wu the in situ Devices Center School of Communication and Electronic EngineeringEast China Normal UniversityShanghai 200241

The R-2R resistor ladder is one of the best topologies for implementing compact-sized digital-to-analog converter(DAC)arrays in implantable ***,it has a limited resolution and considerable inter-channel variation due to component *** avoid losing analog information,we present sub-radix-2 DAC implemented by the R-βR resistor ladder in this *** digital successive approximation register(DSAR)algorithm corrects the transfer function of DACs based on their actual bit ***,a low-cost in situ adaptive bit-weight calibration(ABC)algorithm drives the analog output error between two DACs to zero by adjusting their bit weights *** simulation results show that the proposed algorithm can calibrate the non-linear transfer function of each DAC and the gain error among multiple channels in the background.

关键词： Digital calibration digital-to-analog converter gain error in situ mismatch non-linearity resistor ladder

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Simulation of the effects of different substrates, temperature,and substrate roughness on the mechanical properties of Al_2O_3 coating as tritium penetration barrier

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Nuclear Science and Techniques 2019年第4期30卷 80-90页

作者： ze Liu Fei meng Liang-Bi Yi Key Laboratory for Radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and Technology Sichuan University Chengdu Youfang Technology Co. Ltd Southwestern Institute of Physics

Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substrate, but also changes the properties of the material. In this study,finite element analysis was used to investigate the relationship between the residual thermal stress and the mechanical properties of Al_2O_3 tritium penetration barrier systems. Moreover, the residual thermal stress influenced by factors such as different substrates, temperature, and substrate roughness was also analyzed. The calculation showed that the hardness and elastic modulus increased with increasing compressive stress. However, the hardness and elastic modulus decreased with increasing tensile stress. The systems composed of Al_2O_3 coatings and different substrates exhibited different trends in mechanical properties. As the temperature increased, the hardness and the elastic modulus increased in an Al_2O_3/316 L stainless steel system; the trend was opposite in an Al_2O_3/Si *** from this, the roughness of the substrate surface in the system could magnify the change in hardness and elastic modulus of the coating. Results showed that all these factors led to variation in the mechanical properties of Al_2O_3 tritium permeation barrier systems. Thus, thedetailed reasons for the changes in mechanical properties of these materials need to be analyzed.

关键词： Finite element analysis Thermal stress Mechanical properties Al2O3 tritium penetration barrier systems Nanoindentation

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Two-stage robust optimization of power cost minimization problem in gunbarrel natural gas networks by approximate dynamic programming

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Petroleum Science 2022年第5期19卷 2497-2517页

作者： Yi-ze meng Ruo-Ran Chen Tian-Hu Deng Department of Industrial Engineering Tsinghua UniversityBeijing100084China

In short-term operation of natural gas network,the impact of demand uncertainty is not *** address this issue we propose a two-stage robust model for power cost minimization problem in gunbarrel natural gas *** demands between pipelines and compressor stations are uncertain with a budget parameter,since it is unlikely that all the uncertain demands reach the maximal deviation *** solving the two-stage robust model we encounter a bilevel problem which is challenging to *** formulate it as a multi-dimensional dynamic programming problem and propose approximate dynamic programming methods to accelerate the *** results based on real network in China show that we obtain a speed gain of 7 times faster in average without compromising optimality compared with original dynamic programming *** results also verify the advantage of robust model compared with deterministic model when facing *** findings offer short-term operation methods for gunbarrel natural gas network management to handle with uncertainties.

关键词： Natural gas Gunbarrel gas pipeline networks Robust optimization Approximate dynamic programming

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CO_(2)geological sequestration potential of the low-rank coals in the southern margin of the Junggar Basin

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Frontiers of Earth Science 2023年第3期17卷 727-738页

作者： Qun ZHAO ze DENG meng ZHAO Dexun LIU Research Institute of Petroleum Exploration&Development PetroChinaBeijing 100083China PetroChina Southwest Oil&Gasfield Company Chengdu 610051China

Carbon capture,utilization,and storage(CCUS)is considered one of the most effective measures to achieve net-zero carbon emissions by 2050,and low-rank coal reservoirs are commonly recognized as potential CO_(2)storage sites for carbon *** evaluate the geological CO_(2)sequestration potential of the low-rank coal reservoirs in the southern margin of the Junggar Basin,multiple experiments were performed on coal samples from that area,including high-pressure mercury porosimetry,low-temperature N2 adsorption,overburden porosity and permeability measurements,and high-pressure CH4 and CO_(2)isothermal adsorption *** with the geological properties of the potential reservoir,including coal seam development and hydrodynamic characteristics,the areas between Santun River and Sigong River in the Junggar Basin were found to be suitable for CO_(2)***,the coal-bearing strata from Santun River to Sigong River can be defined as“potentially favorable areas for CO_(2)eequetfraiion”To better guide the future field test of CO_(2)storage in these areas,three CO_(2)sequestration modes were defined:1)the broad syncline and faulted anticline mode;2)the monoclinic mode;3)the syncline and strike-slip fault mode.

关键词： CO_(2)geological sequestration coalbed methane low-rank coal coal reservoir Junggar Basin

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Large-scale model test study on the water pressure resistance of construction joints of karst tunnel linings

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Frontiers of Structural and Civil Engineering 2023年第8期17卷 1249-1263页

作者： meng HUANG Mingli HUANG ze YANG Yuan SONG Zhien ZHANG School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China Enterprise Key Laboratory Tianjin Municipal Engineering Design and Research InstituteTianjin 300392China School of Civil Engineering and Architecture Anhui University of Science and TechnologyHuainan 232001China

Model tests and numerical calculations were adopted based on the New Yuanliangshan tunnel project to investigate the water pressure resistance of lining construction joints in high-pressure and water-rich karst tunnels.A large-scale model test was designed and conducted,innovatively transforming the external water pressure of the lining construction joint into internal water *** effects of the embedded position and waterstop type on the water pressure resistance of the construction joint were analyzed,and the reliability of the model test was verified via numerical *** results show that using waterstops can significantly improve the water pressure resistance of lining construction *** water pressure resistance of the lining construction joint is positively correlated with the lining thickness and embedded depth of the *** addition,the type of waterstop significantly influences the water pressure resistance of lining construction *** test results show that the water pressure resistance of the embedded transverse reinforced waterstop is similar to that of the steel plate waterstop,and both have more advantages than the rubber *** water pressure resistance of the construction joint determined via numerical calculations is similar to the model test results,indicating that the model test results have high accuracy and *** study provides a reference for similar projects and has wide applications.

关键词： karst tunnel lining construction joint water pressure resistance large-scale model test numerical calculations

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Tool-path generation for industrial robotic surface-based application

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Advances in Manufacturing 2019年第1期7卷 64-72页

作者： He lyu Yue Liu Jiao-Yang Guo He-Ming Zhang ze-Xiang Li Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Hong Kong People's Republic of China Hong Kong University of Science and Technology Shenzhen Research Institute Shenzhen 518057 Guangdong People's Republic of China

Industrial robots are widely used in various applications such as machining, painting, and welding. There is a pressing need for a fast and straightforward robot programming method, especially for surface-based tasks. At present, these tasks are time-consuming and expensive, and it requires an experienced and skilled operator to program the robot for a specific task. Hence, it is essential to automate the tool-path generation in order to eliminate the manual planning. This challenging research has attracted great attention from both industry and academia. In this paper, a tool-path generation method based on a mesh model is introduced. The bounding box tree and kdtree are adopted in the algorithm to derive the tool path. In addition, the algorithm is integrated into an offline robot programming system offering a comprehensive solution for robot modeling, simulation, as well as tool-path generation. Finally, a milling experiment is performed by creating tool paths on the surface thereby demonstrating the effectiveness of the system.

关键词： Industrial robot Tool path generation Simulation Intelligent manufacturing

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