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Nuclear magnetic resonance(NMR) microscopic simulation based on random-walk: Theory and parameters analysis

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Journal of Central South University 2014年第3期21卷 1091-1097页

作者：谭茂金徐晶晶邹友龙徐赤诚 Key Laboratory of Geo-detection of Ministry of Education (China University of Geosciences) School of Geophysics and Information Technology China University of Geosciences Department of Petroleum & Geosystems Engineering The University of Texas at Austin

The microscopic response characteristics of nuclear magnetic resonance(NMR) are widely used for characterizing complex pore structures of rocks. Due to the prohibitive NMR experiment cost, numerical simulation was employed as an alternative approach to verify some theoretical aspects of NMR responses. Firstly, the basic principles of pore-scale NMR simulation based on random-walk method(RWM) were introduced. The RWM-simulated results were benchmarked with the analytical results for an ideal spherical pore model. Then, the effects of two numerical parameters, namely diffusion radius and walk numbers, were studied on the simulation accuracy. The simulation method is then applied to various pore models with different pore sizes and pore shapes filled with different fluids to study the microscopic NMR response characteristics. The numerical experiments are useful for understanding and interpreting NMR measurements and the simulation code provides a numerical tool to perform pixel-based digital rock analysis.

关键词： microscopic nuclear magnetic resonance random-walk method pore structure parameters analysis

A statistical damage-based constitutive model for shearing of rock joints in brittle drop mode

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International Journal of Mining Science and Technology 2024年第8期34卷 1041-1058页

作者： Xinrong Liu Peiyao Li Xueyan Guo Xinyang Luo Xiaohan Zhou Luli Miao Fuchuan Zhou Hao Wang School of Civil Engineering Chongqing UniversityChongqing 400045China National Joint Engineering Research Center of Geohazards Prevention in The Reservoir Areas(Chongqing) Chongqing 400045China Key Laboratory of New Technology for Construction of Cities in Mountain Area(Chongqing University) Ministry of EducationChongqing 400045China Chongqing Vocational Institute of Engineering Chongqing 402260China

Some rock joints exhibit significant brittleness,characterized by a sharp decrease in shear stress upon reaching the peak ***,existing models often fail to accurately represent this behavior and are encumbered by numerous parameters lacking clear mechanical *** study presents a new statistical damage constitutive model rooted in both damage mechanics and statistics,containing only three model *** proposed model encompasses all stages of joint shearing,including the compaction stage,linear stage,plastic yielding stage,drop stage,strain softening stage,and residual strength *** derive the analytical expression of the constitutive model,three boundary conditions are *** data from both natural and artificial rock joints is utilized to validate the model,resulting in average absolute relative errors ranging from 3%to 8%.Moreover,a comparative analysis with established models illustrates that the proposed model captures stress drop and post-peak strain softening more effectively,with model parameters possessing clearer mechanical ***,parameter analysis is conducted to investigate the impacts of model parameters on the curves and unveil the relationship between these parameters and the mechanical properties of rock ***,the proposed model is straightforward in form,and all model parameters can be obtained from direct shear tests,thus facilitating the utilization in numerical simulations.

关键词： Rock joints Brittle rock Direct shear test Damage-based constitutive model parameters analysis

The impact of key parameters on the cycle efficiency of multi-stage RCAES system

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Journal of Modern Power Systems and Clean Energy 2014年第4期2卷 422-430页

作者： Bin LIU Laijun CHEN Shengwei MEI Feng LIU Junjie WANG Sixian WANG State Key Lab of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China

Due to the uncertainty and anti-peaking nature,large scale integration of renewable energy imposes great challenges to the operation and dispatch of power *** air energy storage(CAES)system provides new ideas to solve this problem as its characteristics of fast regulating,flexible location and long-service ***,regenerative compressed air energy storage(RCAES)system is widely concerned as its capability of heat recovery in the compression *** cycle efficiency is a key indicator of RCAES system which can be significantly impacted by the key parameters of the systems including compression ratio,exhaust air pressure of throttle(EAPT)and the maximum working pressure(MWP)of compressed air storage vessel(CASV).However,current research mostly focuses on the thermodynamic process and few studies have focused on the impact of key parameters on RCAES *** on the efficiency evaluation method which was formulated through the electricalmechanical-thermal dynamic process and measurable parameters,the impact of key parameters on the cycle efficiency of RCAES system is analyzed in this paper and a practical RCAES design scheme is adopted for case study.

关键词： RCAES Efficiency evaluation parameters analysis Energy conversion Energy storage

Torsional Vibration analysis of an FR Driveline System

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Journal of Donghua University(English Edition) 2004年第2期21卷 141-144页

作者：任少云朱正礼张建武 School of Mechanical Engineering Shanghai Jiaotong University shanghai 200030Dr School of Mechanical Engineering Shanghai Jiaotong University shanghai 200030

Towing tractor drivelines are lightly damped non-linear systems. Interactions between components can cause dynamic behavors such as gear gap impact in gear transmissions, shuffle and clonk phenomena in driveline. The torsional vibration of driveline has an important effect on grand engineering vehicle vibration and noise. Through analyzing torsional vibration equations of driveline, torsional vibration model of driveline is developed by using Matlab/Simulink software, Shuffle and clonk phenomena are observed in torsional vibration. The modeling method of analysizing driveline torsional vibration can be used to research and improve similar engineering vehicle driveline behavors.

关键词： towing tractor driveline torsional vibration modelling and simulation parameters analysis

analysis model for deformation mechanism of strip foundation of building:Considering shear effect of down-crossing tunnel under excavation

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Journal of Central South University 2021年第8期28卷 2556-2573页

作者： WU Ting-yao JIANG Nan ZHOU Chuan-bo XIA Yu-qing ZHANG Yu-qi ZHU Bin Faculty of Engineering China University of GeosciencesWuhan 430074China

When the tunnel underpasses through the building,it will cause deformation and even damage to the buildings above,and the deformation of building foundation is the key to building *** on the engineering case,the theoretical analysis was employed to evaluate the influence of shield tunnel underpass construction on the stability of the building,and the optimal tunneling parameters in the field construction have been obtained through the verified theoretical model and parameter ***,the strip foundation of the building was simplified to the Timoshenko beam,which was taken into account the shear effect,and then the deformation displacement of the soil at the same place of strip foundation was applied to the simplified Timoshenko ***,the numerical solution of the displacement of the strip foundation was obtained by using the finite element method and verified its reliability using Euler-Bernoulli beam theoretical model,field monitoring data,and numerical *** analysis for the deformation and internal force of strip foundation under different types of shield machine tunneling parameters showed that the influence of the pressure of shield excavation chamber,thrust of shield,and driving speed played an important role in the deformation of the building’s strip foundation and internal force.

关键词： down-crossing tunnel Timoshenko beam strip foundation finite element method parameters analysis