期刊文献+
共找到3,872篇文章
< 1 2 194 >
每页显示 20 50 100
ElasticDAG:弹性图式区块链
1
作者 岳镜涛 肖江 +3 位作者 张世桀 程凤 陈汉华 金海 《软件学报》 EI CSCD 北大核心 2024年第11期5279-5305,共27页
图式区块链采用有向无环图(directed acyclic graph,DAG)的并行拓扑结构,相较于基于串行拓扑结构的传统链式区块链,能够显著提升系统性能,已受到业界广泛关注.然而,现有图式区块链的共识协议与存储模型高度耦合,缺乏灵活性,难以适应多... 图式区块链采用有向无环图(directed acyclic graph,DAG)的并行拓扑结构,相较于基于串行拓扑结构的传统链式区块链,能够显著提升系统性能,已受到业界广泛关注.然而,现有图式区块链的共识协议与存储模型高度耦合,缺乏灵活性,难以适应多元化应用需求.同时,大部分图式区块链在共识协议层面上缺乏灵活性,局限于概率性共识协议,难以兼顾确认延迟和安全性,尤其对于延迟敏感型应用很不友好.为此,提出弹性图式区块链系统ElasticDAG,其核心思想是将存储模型和共识协议进行解耦,让两者并行、独立地运行,从而灵活适配多元化应用.针对提升系统吞吐量和活性的需求,为存储模型设计自适应区块确认策略和基于划分的确认区块排序算法;针对降低交易确认延迟的需求,设计低延迟DAG区块链混合共识协议.实验结果表明,ElasticDAG原型系统在广域网下的吞吐量高达11 Mb/s,并具有10秒级确认性能.与OHIE相比,Elastic DAG在实现同等吞吐量的情况下,可将确认延迟降低17倍;与Haootia相比,Elastic DAG在实现同等共识延迟的情况下,可将安全性从91.04%提升到99.999914%. 展开更多
关键词 图式区块链 混合共识协议 BFT协议 存储模型 弹性区块链系统
下载PDF
Effects of Initial Defects on Effective Elastic Modulus of Concrete with Mesostructure
2
作者 LI Xinxin DU Cheng +2 位作者 LI Chengyu XU Yi GONG Wenping 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第6期1484-1495,共12页
An exquisite mesostructure model was presented to predict the effective elastic modulus of concrete,in which concrete is realized as a four-phase composite material consisting of coarse aggregates,mortar matrix,interf... An exquisite mesostructure model was presented to predict the effective elastic modulus of concrete,in which concrete is realized as a four-phase composite material consisting of coarse aggregates,mortar matrix,interfacial transition zone(ITZ),and initial defects.With the three-dimensional(3D)finite element(FE)simulation,the highly heterogeneous composite elastic behavior of concrete was modeled,and the predicted results were compared with theoretical estimations for validation.Monte Carlo(MC)simulations were performed with the proposed mesostructure model to investigate the various factors of initial defects influencing the elastic modulus of concrete,such as the shape and concentration(pore volume fraction or crack density)of microspores and microcracks.It is found that the effective elastic modulus of concrete decreases with the increase of initial defects concentration,while the distribution and shape characteristics also exert certain influences due to the stress concentration caused by irregular inclusion shape. 展开更多
关键词 CONCRETE initial defects effective elastic modulus mesostructure model FEM
下载PDF
Trajectory compensation for multi-robot coordinated lifting system considering elastic catenary of the rope
3
作者 ZHAO Xiangtang ZHAO Zhigang +2 位作者 SU Cheng MENG Jiadong WANG Baoxi 《High Technology Letters》 EI CAS 2024年第3期252-262,共11页
The multi-robot coordinated lifting system is an unconstrained system with a rigid and flexible coupling.The deformation of the flexible rope causes errors in the movement trajectory of the lifting system.Based on the... The multi-robot coordinated lifting system is an unconstrained system with a rigid and flexible coupling.The deformation of the flexible rope causes errors in the movement trajectory of the lifting system.Based on the kinematic and dynamic analysis of the lifting system,the elastic catenary mod-el considering the elasticity and mass of the flexible rope is established,and the effect of the deform-ation of the flexible rope on the position and posture of the suspended object is analyzed.According to the deformation of flexible rope,a real-time trajectory compensation method is proposed based on the compensation principle of position and posture.Under the lifting task of the low-speed move-ment,this is compared with that of the system which neglects the deformation of the flexible rope.The trajectoy of the lifting system considering the deformation of flexible rope.The results show that the mass and elasticity of the flexible rope can not be neglected.Meanwhile,the proposed trajectory compensation method can improve the movement accuracy of the lifting system,which verifies the ef-fectiveness of this compensation method.The research results provide the basis for trajectory plan-ning and coordinated control of the lifting system。 展开更多
关键词 multi-robot lifting system deformation of flexible rope elastic catenary model compensation principle of position and posture trajectory compensation
下载PDF
基于RF的Elastic Net-Logistic个人信用违约风险评估 被引量:4
4
作者 陈倩 贺兴时 杨新社 《西安工程大学学报》 CAS 2021年第3期116-122,共7页
以南德信贷数据为基础,针对信贷数据中解释变量维数高、类型丰富、好坏客户数量不均衡等特点,通过分析影响个人信用违约风险的因素,构建了一种基于随机森林(random forest,RF)的Elastic Net-Logistic个人信用违约风险评估模型。并与传统... 以南德信贷数据为基础,针对信贷数据中解释变量维数高、类型丰富、好坏客户数量不均衡等特点,通过分析影响个人信用违约风险的因素,构建了一种基于随机森林(random forest,RF)的Elastic Net-Logistic个人信用违约风险评估模型。并与传统Elastic Net-Logistic模型、基于RF的Lasso-Logistic模型进行比较,证明所提出的模型表现更优。为更进一步验证模型有效性,采用澳大利亚信贷数据进行实例分析。结果表明,该模型的违约召回率与分类精度比Elastic Net-Logistic模型和基于RF的Lasso-Logistic模型分别提高了0.88%、8.78%和0.79%、6.06%。验证了基于RF的Elastic Net-Logistic模型对信贷数据有更好的分类效果。 展开更多
关键词 个人信用风险 随机森林 elastic net-logistic模型 Lasso-Logistic模型
下载PDF
Gas sand distribution prediction by prestack elastic inversion based on rock physics modeling and analysis 被引量:5
5
作者 贺芙邦 游俊 陈开远 《Applied Geophysics》 SCIE CSCD 2011年第3期197-205,240,共10页
Seismic inversion is one of the most widely used technologies for reservoir prediction. Many good results have been obtained but sometimes it fails to differentiate the lithologies and identify the fluids. However, se... Seismic inversion is one of the most widely used technologies for reservoir prediction. Many good results have been obtained but sometimes it fails to differentiate the lithologies and identify the fluids. However, seismic prestack elastic inversion based on rock physics modeling and analysis introduced in this paper is a significant method that can help seismic inversion and interpretation reach a new quantitative (or semi-quantitative) level from traditional qualitative interpretation. By doing rock physics modeling and forward perturbation analysis, we can quantitatively analyze the essential relationships between rock properties and seismic responses and try to find the sensitive elastic properties to the lithology, porosity, fluid type, and reservoir saturation. Finally, standard rock physics templates (RPT) can be built for specific reservoirs to guide seismic inversion interpretation results for reservoir characterization and fluids identification purpose. The gas sand distribution results of the case study in this paper proves that this method has unparalleled advantages over traditional post-stack methods, by which we can perform reservoir characterization and seismic data interpretation more quantitatively and efficiently. 展开更多
关键词 Rock physics seismic response elastic parameters elastic inversion reservoir characterization modelING
下载PDF
Perfectly matched layer-absorbing boundary condition for finite-element time-domain modeling of elastic wave equations 被引量:3
6
作者 赵建国 史瑞其 《Applied Geophysics》 SCIE CSCD 2013年第3期323-336,359,共15页
The perfectly matched layer (PML) is a highly efficient absorbing boundary condition used for the numerical modeling of seismic wave equation. The article focuses on the application of this technique to finite-eleme... The perfectly matched layer (PML) is a highly efficient absorbing boundary condition used for the numerical modeling of seismic wave equation. The article focuses on the application of this technique to finite-element time-domain numerical modeling of elastic wave equation. However, the finite-element time-domain scheme is based on the second- order wave equation in displacement formulation. Thus, the first-order PML in velocity-stress formulation cannot be directly applied to this scheme. In this article, we derive the finite- element matrix equations of second-order PML in displacement formulation, and accomplish the implementation of PML in finite-element time-domain modeling of elastic wave equation. The PML has an approximate zero reflection coefficients for bulk and surface waves in the finite-element modeling of P-SV and SH wave propagation in the 2D homogeneous elastic media. The numerical experiments using a two-layer model with irregular topography validate the efficiency of PML in the modeling of seismic wave propagation in geological models with complex structures and heterogeneous media. 展开更多
关键词 Absorbing boundary condition elastic wave equation perfectly matched layer finite-element modeling
下载PDF
Nonlinear elastic deformation of magnesium and cobalt by Preisach-Mayergoyz model
7
作者 李良 王红英 周爱国 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第9期2220-2225,共6页
A classic hysteretic model, Preisach-Mayergoyz model (P-M model), was used to calculate the nonlinear elastic deformation of magnesium (Mg) and cobalt (Co). Mg and Co samples in cylinder shape were compressively... A classic hysteretic model, Preisach-Mayergoyz model (P-M model), was used to calculate the nonlinear elastic deformation of magnesium (Mg) and cobalt (Co). Mg and Co samples in cylinder shape were compressively tested by uniaxial test machine to obtain their stress—strain curves with hysteretic loops. The hysteretic loops do have two properties of P-M hysteretic systems: wiping out and congruency. It is proved that P-M model is applicable for the analysis of these two metals’ hysteresis. This model was applied on Mg at room temperature and Co at 300 ℃. By the P-M model, Co and Mg nonlinear elastic deformation can be calculated based on the stress history. The simulated stress—strain curves agree well with the experimental results. Therefore, the mechanical hysteresis of these two metals can be easily predicted by the classic P-M hysteretic model. 展开更多
关键词 MAGNESIUM COBALT nonlinear elastic deformation Preisach-Mayergoyz model
下载PDF
Sensitivity analysis for stochastic user equilibrium with elastic demand assignment model
8
作者 王建 吴鼎新 邓卫 《Journal of Southeast University(English Edition)》 EI CAS 2014年第3期363-367,共5页
This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand (SUEED) model. First, proof is given for the existence of derivatives of output variables... This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand (SUEED) model. First, proof is given for the existence of derivatives of output variables with respect to the perturbation parameters for the SUEED model. Then by taking advantage of the gradient-based method for sensitivity analysis of a general nonlinear program, detailed formulae are developed for calculating the derivatives of designed variables with respect to perturbation parameters at the equilibrium state of the SUEED model. This method is not only applicable for a sensitivity analysis of the logit-type SUEED problem, but also for the probit-type SUEED problem. The application of the proposed method in a numerical example shows that the proposed method can be used to approximate the equilibrium link flow solutions for both logit-type SUEED and probit-type SUEED problems when small perturbations are introduced in the input parameters. 展开更多
关键词 network modeling stochastic user equilibrium elastic demand sensitivity analysis first-order approximation
下载PDF
Evaluation of soil fabric using elastic waves during load-unload 被引量:1
9
作者 Yang Li Masahide Otsubo Reiko Kuwano 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2023年第10期2687-2700,共14页
It is essential to assess the evolution of soil fabric as it has an important role in the mechanical responses of soils during complex loading conditions.This contribution carries out the physical experiments using th... It is essential to assess the evolution of soil fabric as it has an important role in the mechanical responses of soils during complex loading conditions.This contribution carries out the physical experiments using three granular materials in the laboratory.The variations of compression and shear wave velocities(Vp and Vs)are investigated during load-unload cycles under dry and drained conditions.Supplementary discrete element method(DEM)simulations are performed to understand the evolution of soil fabric during the equivalent load-unload cycles using spherical particles.Vp and Vs are not always reversible even though the stress state regains its isotropic condition after unload,indicating that Vp and Vs are governed by not only the stress state but also the fabric change.The variations of Vp/Vs are density-and stress-dependent;a higher level of stress ratio(s01/s03)threshold is observed for denser packings to trigger a significant change in wave velocity ratio(Vp/Vs)for experimental results using spherical glass beads and simulation data using spherical particles.Considering the particle shape,a higher s01/s03 threshold is found for more angular particles than rounded particles.The DEM result reveals that Vp/Vs of spherical particles can be correlated linearly with the evolution of fabric ratio(Fver/Fhor)during loadunload in a pre-peak range under dry and drained conditions. 展开更多
关键词 Soil fabric ANISOTROPY elastic waves Discrete element modelling Laboratory tests
下载PDF
On dynamics of elastic rod based on exact Cosserat model 被引量:11
10
作者 刘延柱 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第1期1-8,共8页
The analysis of kinematics and dynamics of an elastic rod with circular cross section is studied on the basis of exact Cosserat model under consideration of the tension and shear deformation of the rod. The dynamical ... The analysis of kinematics and dynamics of an elastic rod with circular cross section is studied on the basis of exact Cosserat model under consideration of the tension and shear deformation of the rod. The dynamical equations of a rod with arbitrary initial shape are established in general form. The dynamics of a straight rod under axial tension and torsion is discussed as an example. In discussion of static stability in the space domain the Greenhill criteria of stability and the Euler load are corrected by the influence of tension and shear strain. In analysis of dynamical stability in the time domain it is shown that the Lyapunov and Euler stability conditions of the rod in space domain are the necessary conditions of Lyapunov's stability in the time domain. The longitudinal, torsional and lateral vibrations of a straight rod based on exact model are discussed, and an exact formula of free frequency of lateral vibration is obtained. The free frequency formulas of various simplified models, such as the Rayleigh beam, the Kirchhoff rod, and the Timoshenko beam, can be seen as special cases of the exact formula under different conditions of simplification. 展开更多
关键词 dynamics of elastic rod exact Cosserat model lateral vibration of rod
下载PDF
Driving Force Model for Non-pneumatic Elastic Wheel 被引量:3
11
作者 Li Bo Zhao Youqun +3 位作者 Zang Liguo Bei Shaoyi Fu Hongxun Zhang Lanchun 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2016年第2期231-236,共6页
In order to obtain good driving performance,a driving force model is presented for non-pneumatic elastic wheel.Brush model of pneumatic tyres is introduced and the deformations of elastic supports and tread are also t... In order to obtain good driving performance,a driving force model is presented for non-pneumatic elastic wheel.Brush model of pneumatic tyres is introduced and the deformations of elastic supports and tread are also taken into account.The longitudinal slip rate is redefined.The grounding pressure distribution of elastic wheels is analyzed and corrected according to speed,temperature and stiffness.Then rolling resistance equation is developed.Finally,simulation is conducted by software CarSim,and the results show that the estimated values are consistent with simulation values,especially at low longitudinal slip rate.The research can help to optimize design of non-pneumatic elastic wheel. 展开更多
关键词 driving force non-pneumatic elastic WHEEL BRUSH model rolling resistance
下载PDF
The Numerical Modeling of 3-D Elastic Wave Equation Using a High-Order,Staggered-Grid, Finite Difference Scheme 被引量:8
12
作者 XiaFan DongLiangguo MaZaitian 《Applied Geophysics》 SCIE CSCD 2004年第1期38-41,共4页
This article provides the application of the high-order, staggered-grid, finite-difference scheme to model elastic wave propagation in 3-D isotropic media. Here, we use second-order, tempo- ral- and high-order spatial... This article provides the application of the high-order, staggered-grid, finite-difference scheme to model elastic wave propagation in 3-D isotropic media. Here, we use second-order, tempo- ral- and high-order spatial finite-difference formulations with a staggered grid for discretization of the 3-D elastic wave equations of motion. The set of absorbing boundary conditions based on paraxial approximations of 3-D elastic wave equations are applied to the numerical boundaries. The trial re- sults for the salt model show that the numerical dispersion is decreased to a minimum extent, the accuracy high and diffracted waves abundant. It also shows that this method can be used for modeling wave propagation in complex media with the lateral variation of velocity. 展开更多
关键词 numerical modeling staggered-grid and elastic wave
下载PDF
Dynamics Modeling and Numerical Analysis of Rotor with Elastic Support/Dry Friction Dampers 被引量:3
13
作者 Liao Mingfu Li Yan +1 位作者 Song Mingbo Wang Siji 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2018年第1期69-83,共15页
The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/p... The elastic support/dry friction damper is a type of damper which is used for active vibration control in a rotor system.To establish the analytical model of this type of damper,a two-dimensional friction model-ball/plate model was proposed.By using this ball/plate model,a dynamics model of rotor with elastic support/dry friction dampers was established and experimentally verified.Moreover,the damping performance of the elastic support/dry friction damper was studied numerically with respect to some variable parameters.The numerical study shows that the damping performance of the elastic support/dry friction damper is closely related to the stiffness distribution of the rotor-support system,the damper location,the pressing force between the moving and stationary disk,the friction coefficient,the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk.In general,the damper should be located on an elastic support which has a large vibration amplitude in order to achieve a better damping performance,and the more vibration energy in this elastic support concentrates,the better performance of the damper will be.The larger the tangential contact stiffness of the contact interface,and the stiffness of the stationary disk are,the better performance of the damper will be.There will be an optimal value of the friction force at which the damper performs best. 展开更多
关键词 ROTOR system elastic support/dry FRICTION DAMPER FRICTION model rotor′s mode UNBALANCE response
下载PDF
Mathematical modeling of elastic inverted pendulum control system 被引量:3
14
作者 ChaoXU XinYU 《控制理论与应用(英文版)》 EI 2004年第3期281-282,共2页
Inverted pendulums are important objects of theoretical investigation and experiment in the area of control theory and engineering. The researches concentrate on the rigid finite dimensional models which are described... Inverted pendulums are important objects of theoretical investigation and experiment in the area of control theory and engineering. The researches concentrate on the rigid finite dimensional models which are described by ordinary differential equations (ODEs) .Complete rigidity is the approximation of practical models ; Elasticity should be introduced into mathematical models in the analysis of system dynamics and integration of highly precise controller. A new kind of inverted pendulum, elastic inverted pendulum was proposed, and elasticity was considered. Mathematical model was derived from Hamiltonian principle and variational methods, which were formulated by the coupling of partial differential equations (PDE) and ODE. Because of infinite dimensional, system analysis and control of elastic inverted pendulum is more sophisticated than the rigid one. 展开更多
关键词 elastic inverted pendulum Hamiltonian principle Variational methods Mathematical model Coupling equation array
下载PDF
A method to Estimate Dynamic Responses of VLFS Based on Multi-Floating-Module Model Connected by Elastic Hinges 被引量:5
15
作者 HUANG Heng CHEN Xu-jun +2 位作者 LIU Jun-yi MIAO Yu-ji JI Song 《China Ocean Engineering》 SCIE EI CSCD 2021年第5期687-699,共13页
Based on the elastic foundation beam theory and the multi-floating-module hydrodynamic theory,a novel method is proposed to estimate the dynamic responses of VLFS(Very Large Floating Structure).In still water,a VLFS c... Based on the elastic foundation beam theory and the multi-floating-module hydrodynamic theory,a novel method is proposed to estimate the dynamic responses of VLFS(Very Large Floating Structure).In still water,a VLFS can be simplified as an elastic foundation beam model or a multi-floating-module model connected by elastic hinges.According to equivalent displacement of the two models in static analysis,the problem of rotation stiffness of elastic hinges can be solved.Then,based on the potential flow theory,the dynamic responding analysis of multi-floatingmodule model under wave loads can be computed in ANSYS-AQWA software.By assembling the time domain analysis results of each module,the dynamic responses of the VLFS can be obtained.Validation of the method is conducted through a series of comparison calculations,which mainly includes a continuous structure and a three-part structure connected by hinges in regular waves.The results of this paper method show a satisfactory agreement with the experiment and calculation data given in relative references. 展开更多
关键词 Very Large Floating Structure(VLFS) dynamic responses elastic foundation beam multi-floatingmodule model elastic hinge
下载PDF
On the Elastic Vibration Model for High Length-Diameter Ratio Rocket with Attitude Control System 被引量:3
16
作者 朱伯立 杨树兴 《Journal of Beijing Institute of Technology》 EI CAS 2003年第3期269-272,共4页
An elastic vibration model for high length diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dy... An elastic vibration model for high length diameter ratio spinning rocket with attitude control system which can be used for trajectory simulation is established. The basic theory of elastic dynamics and vibration dynamics were both used to set up the elastic vibration model of rocket body. In order to study the problem more conveniently, the rocket's body was simplified to be an even beam with two free ends. The model was validated by simulation results and the test data. 展开更多
关键词 elastic vibration model high length diameter ratio rocket simulation
下载PDF
The Analysis of Wall Shear Stress Modulated by Acute Exercise in the Human Common Carotid Artery with an Elastic Tube Model 被引量:2
17
作者 Yanxia Wang Yu Wang +3 位作者 Siqi Li Aziz ur Rehman Aziz Shutian Liu Kairong Qin 《Computer Modeling in Engineering & Sciences》 SCIE EI 2018年第8期127-147,共21页
Assessment of the magnitude and pattern of wall shear stress(WSS)in vivo is the prerequisite for studying the quantitative relationship between exercise-induced WSS and arterial endothelial function.In the previous st... Assessment of the magnitude and pattern of wall shear stress(WSS)in vivo is the prerequisite for studying the quantitative relationship between exercise-induced WSS and arterial endothelial function.In the previous studies,the calculation of the WSS modulated by exercise training was primarily based upon the rigid tube model,which did not take non-linear effects of vessel elastic deformation into consideration.In this study,with an elastic tube model,we estimated the effect of a bout of 30-minute acute cycling exercise on the WSS and the flow rate in the common carotid artery according to the measured inner diameter,center-line blood flow velocity,heart rates and the brachial blood pressures before and after exercise training.Furthermore,the roles of exerciseinduced arterial diameter and blood flow rate in the change of WSS were also determined.The numerical results demonstrate that acute exercise significantly increases the magnitudes of blood flow rate and WSS.Moreover,the vessel elastic deformation is a non-negligible factor in the calculation of the WSS induced by exercise,which generates greater effects on the minimum WSS than the maximum WSS.Additionally,the contributions of exercise-induced variations in blood flow rate and diameter are almost identical in the change of the mean WSS. 展开更多
关键词 Acute CYCLING exercise blood flow wall shear stress common CAROTID ARTERY elastic TUBE model rigid TUBE model
下载PDF
Hybrid absorbing boundary condition for threedimensional elastic wave modeling 被引量:3
18
作者 Liu Xin Liu Yang +4 位作者 Ren Zhi-Ming Cai Xiao-Hui Li Bei Xu Shi-Gang Zhou Le-Kai 《Applied Geophysics》 SCIE CSCD 2017年第2期270-278,323,324,共11页
Edge reflections are inevitable in numerical modeling of seismic wavefields, and they are usually attenuated by absorbing boundary conditions. However, the commonly used perfectly matched layer (PML) boundary condit... Edge reflections are inevitable in numerical modeling of seismic wavefields, and they are usually attenuated by absorbing boundary conditions. However, the commonly used perfectly matched layer (PML) boundary condition requires special treatment for the absorbing zone, and in three-dimensional (3D) modeling, it has to split each variable into three corresponding variables, which increases the computing time and memory storage. In contrast, the hybrid absorbing boundary condition (HABC) has the advantages such as ease of implementation, less computation time, and near-perfect absorption; it is thus able to enhance the computational efficiency of 3D elastic wave modeling. In this study, a HABC is developed from two-dimensional (2D) modeling into 3D modeling based on the I st Higdon one way wave equations, and a HABC is proposed that is suitable for a 3D elastic wave numerical simulation. Numerical simulation results for a homogenous model and a complex model indicate that the proposed HABC method is more effective and has better absorption than the traditional PML method. 展开更多
关键词 3D elastic wave equation hybrid absorbing boundary condition forward modeling
下载PDF
Analytical Model of Elastic Modulus and Coefficient of Thermal Expansion for 2.5D C/SiC Composite 被引量:1
19
作者 孔春元 孙志刚 +1 位作者 NIU Xuming SONG Yingdong 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第3期494-499,共6页
To make better use of 2.5D C/SiC composites in industry, it is necessary to understand the mechanical properties. A finite element model'of 2.5D composites is established, by considering the fiber undulation and the ... To make better use of 2.5D C/SiC composites in industry, it is necessary to understand the mechanical properties. A finite element model'of 2.5D composites is established, by considering the fiber undulation and the porosity in 2.5D C/SiC composites. The fiber direction of warp is defined by cosine function to simulate the undulation of warp, and based on uniform strain assumption, analytical model of the elastic modulus and coefficient of thermal expansion (CTE) for 2.5D C/SiC composites were established by using dual- scale model. The result is found to correlate reasonably well with the predicted results and experimental results. The parametric study also demonstrates the effects of the fiber volume fraction, distance of warp yarn, and porosity in micro-scale on the mechanical properties and the coefficients of thermal expansion. 展开更多
关键词 2.5D C/SiC composites finite element model analytical model elastic modulus coefficient of thermal expansion
下载PDF
Naturally fractured hydrocarbon reservoir simulation by elastic fracture modeling 被引量:1
20
作者 Mehrdad Soleimani 《Petroleum Science》 SCIE CAS CSCD 2017年第2期286-301,共16页
Accurate fluid flow simulation in geologically complex reservoirs is of particular importance in construction of reservoir simulators.General approaches in naturally fractured reservoir simulation involve use of unstr... Accurate fluid flow simulation in geologically complex reservoirs is of particular importance in construction of reservoir simulators.General approaches in naturally fractured reservoir simulation involve use of unstructured grids or a structured grid coupled with locally unstructured grids and discrete fracture models.These methods suffer from drawbacks such as lack of flexibility and of ease of updating.In this study,I combined fracture modeling by elastic gridding which improves flexibility,especially in complex reservoirs.The proposed model revises conventional modeling fractures by hard rigid planes that do not change through production.This is a dubious assumption,especially in reservoirs with a high production rate in the beginning.The proposed elastic fracture modeling considers changes in fracture properties,shape and aperture through the simulation.This strategy is only reliable for naturally fractured reservoirs with high fracture permeability and less permeable matrix and parallel fractures with less cross-connections.Comparison of elastic fracture modeling results with conventional modeling showed that these assumptions will cause production pressure to enlarge fracture apertures and change fracture shapes,which consequently results in lower production compared with what was previously assumed.It is concluded that an elastic gridded model could better simulate reservoir performance. 展开更多
关键词 Reservoir performance Discrete fracture model Naturally fractured reservoir History matching elastic gridding
下载PDF
上一页 1 2 194 下一页 到第
使用帮助 返回顶部