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Compressibility dependence on grain size distribution and relative density in sands

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Science China(Technological Sciences) 2015年第3期58卷 443-448页

作者： sun YiFei xiao Yang HANIF Khairul Fikry Faculty of Engineering and Information Sciences University of Wollongong College of Civil Engineering Chongqing University Faculty of Engineering Computing and Mathematics University of Western Australia

A framework of continuum breakage mechanics was used to investigate the dependence of compressibility on grain size distribution(GSD)as well as relative density of *** dependence on GSD was considered by employing a GSD index and relative density dependence was reflected by varying the plastic-breakage coupling *** of the experimental results including isotropic compression and one-dimensional compression of sands with different relative densities and GSDs revealed that sand compressibility increased with the increasing GSD index and plastic-breakage coupling *** coupling angle decreased with increasing relative density,indicating that grains would break more in sand with comparatively high relative density.

关键词： grain size distribution density compression grain breakage thermo-mechanics

A particle-breakage critical state model for rockfill material

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Science China(Technological Sciences) 2015年第7期58卷 1125-1136页

作者： xiao Yang sun YiFei HANIF Khairul Fikry Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing University College of Civil Engineering Chongqing University Faculty of Engineering and Information Sciences University of Wollongong Faculty of Engineering Computing and Mathematics University of Western Australia

Particle breakage has a significant influence on the stress-strain and strength behavior of rockfill material.A breakage critical state theory(BCST)was proposed to describe the evolution of particle *** breakage critical state line in the breakage critical state theory was correlated with the breakage factor,which was fundamentally different from that of the original critical state theory.A simple elastoplastic constitutive model was developed for rockfill in the frame of *** associated flow rule was adopted in this ***,contractive and distortional hardening rules were suggested in view of the particle *** was observed that the proposed model could well represent the complex deformation behaviors of rockfill material,such as the strain hardening,post-peak strain softening,volumetric contraction,volumetric expansion,and particle breakage under different initial confining pressures.

关键词： rockfill material particle breakage critical state theory hardening rule constitutive model

Molecular simulations of methane, ethane and propane adsorption on TON

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第11期10卷 1636-1641页

作者： Cheng PENG Zhi LI xiao-min sun Department of Chemistry Tongji University Shanghai 200092 China College of Water Conservancy Changsha Science and Technology University Changsha 410114 China The Environment Research Institute of Shandong University Jinan 250100 China

The aim of this study was to understand and characterize the adsorption of small alkanes, namely methane, ethane and propane, in zeolite TON through detailed Monte Carlo simulations. The isotherms of pure components were calculated and showed good agreement with experimental data. The adsorption positions, adsorption energy of pure components and isotherms of mixtures were also simulated and the results are discussed.

关键词： Monte Carlo simulations Zeolite Adsorption

Measurement and characterization of bulk nanobubbles by nanoparticle tracking analysis method

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Journal of Hydrodynamics 2022年第6期34卷 1121-1133页

作者： xiao-tong Ma Ming-bo Li Chao sun Center for Combustion Energy Key Laboratory for Thermal Science and Power Engineering of Ministry of EducationDepartment of Energy and Power EngineeringTsinghua UniversityBeijing100084China

The size of the bulk nanobubbles(typically 100 nm-200 nm in diameter)is below the optical resolution of the typical microscopes,which makes it difficult to make a direct observation of them and differentiate between the nanoparticles and the *** this work,a nanoparticle tracking analysis(NTA)system is developed for tracking and sizing the bulk nanobubbles,and more broadly,the Brownian diffusing *** demonstrate the capabilities of the NTA in characterizing the nanoparticles through systematic validation of accuracy and *** particularly exhibit its unique advantages in detecting the polydisperse nanoparticle *** the nucleation and the thermodynamic stability of the bulk nanobubbles are systematically studied by the NTA *** bulk nanobubbles smaller than 600 nm in size are generated via the ultrasonication *** is shown that both the ultrasonic cavitation treatment time and amplitude,essentially,the energy input,favor the nucleation of the bulk nanobubbles with a more concentrated size distribution,a higher concentration,and a smaller hydrodynamic *** temperature dependence of the bulk nanobubbles over a wide range from 25°C to 70°C is *** is found that the nanobubble first shrinks in size significantly and then the size keeps approximately constant with the increasing temperature,showing a narrow size *** transition temperature is around 45°***,as an open system,the NTA is a potential tool in the study of the dynamic behavior of the bulk nanobubbles in situ,such as the coalescence and the collapse.

关键词： Nanoparticle tracking analysis bulk nanobubble light scattering hydrodynamic size number concentration

Cross-seam Hybrid MTDC System for Integration and Delivery of Large-scale Renewable Energy

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Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1352-1362页

作者： Kaiqi sun Huangqing xiao Jiuping Pan Yilu Liu University of Tennessee the Oak Ridge National Laboratory School of Electric Power Engineering South China University of Technology Hitachi ABB Power Grids Research

To better utilize the diversity of renewable energies in the U. S., this paper proposes a cross-seam hybrid multi-terminal high-voltage direct current(MTDC) system for the integration of different types of renewable energies in the U. *** on a developed station-hybrid converter design, the proposed hybrid MTDC system further investigates the connection methods of renewable energies and develops novel flexible power flow control strategies for realizing uninterrupted integration of renewable energies. In addition, the frequency response control of the hybrid MTDC system is proposed by utilizing the coordination between the converters in the hybrid MTDC *** feasibility of the hybrid MTDC system and the performance of its corresponding control strategies are conducted in the PSCAD/EMTDC simulation. The simulation results indicate that the proposed hybrid MTDC system could realize the uninterrupted integration of renewable energies and flexible power transmission to both coasts of U.S.

关键词： Multi-terminal high-voltage direct current(MTDC)system cross-seam interconnection integration of large-scale renewable energies flexible power flow control frequency response control

Algorithms in a Robust Hybrid CFD-DEM Solver for Particle-Laden Flows

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Communications in Computational Physics 2011年第2期9卷 297-323页

作者： Heng xiao Jin sun Institute of Fluid Dynamics ETH Zürich8092 ZürichSwitzerland Institute for Infrastructure and Environment The University of EdinburghEdinburgh EH93JLUnited Kingdom

A robust and efficient solver coupling computational fluid dynamics(CFD)with discrete element method(DEM)is developed to simulate particle-laden flows in various physical *** interpolation algorithm suitable for unstructured meshes is proposed to translate between mesh-based Eulerian fields and particle-based Lagrangian *** interpolation scheme reduces the mesh-dependence of the averaging and interpolation *** addition,the fluid-particle interaction terms are treated semi-implicitly in this algorithm to improve stability and to maintain ***,it is demonstrated that sub-stepping is desirable for fluid-particle systems with small Stokes numbers.A momentum-conserving sub-stepping technique is introduced into the fluid-particle coupling procedure,so that problems with a wide range of time scales can be solved without resorting to excessively small time steps in the CFD *** numerical examples are presented to demonstrate the capabilities of the solver and the merits of the algorithm.

关键词： Fluid-particle interaction particle-laden flow discrete element method computational fluid dynamics hybrid model

Multi-timescale optimization scheduling of interconnected data centers based on model predictive control

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Frontiers in Energy 2024年第1期18卷 28-41页

作者： xiao GUO Yanbo CHE Zhihao ZHENG Jiulong sun Energy Power Electrical Automation and Information EngineeringTianjin UniversityTianjin 300072China

With the promotion of“dual carbon”strategy,data center(DC)access to high-penetration renewable energy sources(RESs)has become a trend in the ***,the uncertainty of RES poses challenges to the safe and stable operation of DCs and power *** this paper,a multi-timescale optimal scheduling model is established for interconnected data centers(IDCs)based on model predictive control(MPC),including day-ahead optimization,intraday rolling optimization,and intraday real-time *** day-ahead optimization stage aims at the lowest operating cost,the rolling optimization stage aims at the lowest intraday economic cost,and the real-time correction aims at the lowest power fluctuation,eliminating the impact of prediction errors through coordinated multi-timescale *** simulation results show that the economic loss is reduced by 19.6%,and the power fluctuation is decreased by 15.23%.

关键词： model predictive control interconnected data center multi-timescale optimized scheduling distributed power supply/landscape uncertainty

Machine learning-based fast frequency response control for a VSC-HVDC system

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 688-697页

作者： Kaiqi sun Huangqing xiao Shengyuan Liu Yilu Liu University of Tennessee KnoxvilleTN 37996USA University of Tennessee KnoxvilleTN 37996USA and also with the Oak Ridge National LaboratoryOak RidgeTN 37831USA

HVDC system can realize a very fast frequency response to the disturbed system under a contingency because its active power control is decoupled from the frequency ***,most of existing HVDC frequency control strategies are coupled with system primary frequency control and secondary frequency *** the traditional system frequency control is dominated by the thermal generators,the advantage of the fast response of the HVDC system is not made fully *** development of a frequency response estimation based on a machine learning algorithm provides another approach to improve the frequency response capability of the HVDC *** from other frequency deviation tracking strategies,a machine learning based HVDC frequency response control can directly increase the power flow of a HVDC system by estimation of the system generator or load *** this paper,a fast frequency response control using a HVDC system for a large power system disturbance based on the multivariate random forest regression(MRFR)algorithm is *** simulation is carried out with an integrated power system model based on the North American *** simulation results indicate that the proposed MRFR based frequency response control can significantly improve the frequency low point during an event,while stabilizing the frequency in advance.

关键词： Frequency response control multivariate random forest regression VSC-HVDC system

Optimization of Dead Load State in Earth-Anchored Cable-Stayed Bridges

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Journal of Harbin Institute of Technology(New Series) 2015年第3期22卷 87-94页

作者： Bin sun Rucheng xiao Department of Bridge Engineering Tongji University

In order to determine the reasonable completed dead load state in earth-anchored cable-stayed bridges,a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasible zone method,emphasizing on the mutual effect between the self-anchored structural parts and the earth-anchored ones. Three cable-stayed bridge models are designed with the main spans of 1 400 m,including a partially earth-anchored cable-stayed bridge,a cable-stayed-suspension bridge and a fully selfanchored cable-stayed bridge,in which the C50 concrete and Q345 steel are adopted. The partially earthanchored cable-stayed bridge and the cable-stayed-suspension bridge secure lower compressive force in the girder than the fully self-anchored cable-stayed bridge by 25 percent at least. The same is for the material consumption of the whole bridge. Furthermore,the anchor volume is more than 20% lower in the partially earthanchored cable-stayed bridge than that in the cable-stayed-suspension bridge. Consequently,the practical span of cable-stayed bridges can be accordingly extended.

关键词： cable-stayed bridge partially earth-anchored cable-stayed bridge cable-stayed-suspension bridge reasonable completed dead load state