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Fully implicit improved discrete velocity method for diatomic gas in all flow regimes 认领 引用 被引量：2
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作者 Linchang Han Liming Yang +3 位作者 Zhihui Li Yanan Ma Ruoyu Li Hao Dong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2026年第2期45-63,共19页
The improved discrete velocity method(IDVM),a multiscale kinetic approach,solves both the Boltzmann model equation and the macroscopic governing equations.It maintains the simplicity of the conventional discrete veloc... The improved discrete velocity method(IDVM),a multiscale kinetic approach,solves both the Boltzmann model equation and the macroscopic governing equations.It maintains the simplicity of the conventional discrete velocity method while significantly enhancing accuracy and efficiency in the continuum flow regime.However,previous implementations of IDVM were limited to monatomic gases,rendering it inapplicable under real atmospheric conditions dominated by diatomic gases.In this paper,the fully implicit IDVM is extended to the Boltzmann-Rykov model equation to simulate multiscale gas flows involving the rotational non-equilibrium effects of diatomic molecules.This approach incorporates macroscopic governing equations to predict the equilibrium distribution function,enabling the fully implicit discretization of the BoltzmannRykov model equation and ensuring rapid convergence.Numerical simulations are performed for several cases,including the one-dimensional nitrogen shock tube,two-dimensional flows around a flat plate and a blunt circular cylinder,and threedimensional supersonic flow over a sphere.The results of the present algorithm show remarkable alignment with those from similar kinetic algorithms and experimental data,demonstrating its ability to simulate non-equilibrium diatomic gas flows.Relative to the conventional semi-implicit discrete velocity method and implicit kinetic methods with a macroscopic forecasting technique,the proposed approach attains varying degrees of acceleration. 展开更多
关键词 Rotational non-equilibrium effect Improved discrete velocity method Rykov model Fully implicit scheme
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Improved methods,properties,applications and prospects of microbial induced carbonate precipitation(MICP)treated soil:A review 认领 引用 被引量：11
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作者 Xuanshuo Zhang Hongyu Wang +3 位作者 Ya Wang Jinghui Wang Jing Cao Gang Zhang 《Biogeotechnics》 2025年第1期34-54,共21页
Soil improvement is one of the most important issues in geotechnical engineering practice.The wide application of traditional improvement techniques(cement/chemical materials)are limited due to damage ecological en-vi... Soil improvement is one of the most important issues in geotechnical engineering practice.The wide application of traditional improvement techniques(cement/chemical materials)are limited due to damage ecological en-vironment and intensify carbon emissions.However,the use of microbially induced calcium carbonate pre-cipitation(MICP)to obtain bio-cement is a novel technique with the potential to induce soil stability,providing a low-carbon,environment-friendly,and sustainable integrated solution for some geotechnical engineering pro-blems in the environment.This paper presents a comprehensive review of the latest progress in soil improvement based on the MICP strategy.It systematically summarizes and overviews the mineralization mechanism,influ-encing factors,improved methods,engineering characteristics,and current field application status of the MICP.Additionally,it also explores the limitations and correspondingly proposes prospective applications via the MICP approach for soil improvement.This review indicates that the utilization of different environmental calcium-based wastes in MICP and combination of materials and MICP are conducive to meeting engineering and market demand.Furthermore,we recommend and encourage global collaborative study and practice with a view to commercializing MICP technique in the future.The current review purports to provide insights for engineers and interdisciplinary researchers,and guidance for future engineering applications. 展开更多
关键词 Soil improvement Bio-cement MICP Improved methods Field application cases
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Thermal fatigue of hot work tool steels:a review on damage mechanisms,performance improvement,and evaluation methods 认领 引用
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作者 Peng-Peng Zuo Hai-Lan Zhao +3 位作者 Xin-Yu Chen Hong-Qing Wu Shao-Hong Li Jun-Wan Li 《Journal of Iron and Steel Research International》 SCIE EI CSCD 2026年第7期276-294,共19页
Thermal fatigue failure is one of the main factors affecting the service life of hot-working dies.Thermal fatigue resistance also plays a fundamental role in work safety and cost saving in the rapidly developing autom... Thermal fatigue failure is one of the main factors affecting the service life of hot-working dies.Thermal fatigue resistance also plays a fundamental role in work safety and cost saving in the rapidly developing automotive industry.The recent studies on the thermal fatigue phenomenon of hot work tool steels are reviewed.Those researches primarily focus on damage mechanism,performance improvement,and evaluation methods,encompassing both testing methods and life prediction.Compared to previous researches,notable progress has been made in the following areas:damage mechanisms have been extensively studied from macroscale to microscale.Furthermore,damage mechanisms in different fatigue regimes have also been investigated.In terms of improving the thermal fatigue resistance of hot work tool steels,additive manufacturing is increasingly being adopted as a novel forming method,particularly for designing conformal cooling channel systems in dies.Regarding the evaluation methods for thermal fatigue behavior,iterated numerical analysis and elaborated finite-element models are playing an essential role in predicting thermal fatigue life.This field is currently undergoing tremendous evolution.Finally,current challenges and future research directions are presented for incoming investigators.It is acknowledged that significant scope remains for advancing these areas to more effectively guide the practical manufacture and application of hot-working dies. 展开更多
关键词 Hot work tool steel Thermal fatigue Damage mechanism Performance improvement Evaluation method Life prediction
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Advances in the Improved Element-Free Galerkin Methods:A Comprehensive Review 认领 引用 被引量：1
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作者 Heng Cheng YichenYang Yumin Cheng 《Computer Modeling in Engineering & Sciences》 SCIE EI 2025年第12期2853-2894,共42页
The element-free Galerkin(EFG)method,which constructs shape functions via moving least squares(MLS)approximation,represents a fundamental and widely studied meshless method in numerical computation.Although it achieve... The element-free Galerkin(EFG)method,which constructs shape functions via moving least squares(MLS)approximation,represents a fundamental and widely studied meshless method in numerical computation.Although it achieves high computational accuracy,the shape functions are more complex than those in the conventional finite element method(FEM),resulting in great computational requirements.Therefore,improving the computational efficiency of the EFG method represents an important research direction.This paper systematically reviews significant contributions fromdomestic and international scholars in advancing the EFGmethod.Including the improved element-free Galerkin(IEFG)method,various interpolating EFG methods,four distinct complex variable EFG methods,and a series of dimension splitting meshless methods.In the numerical examples,the effectiveness and efficiency of the three methods are validated by analyzing the solutions of the IEFG method for 3D steadystate anisotropic heat conduction,3D elastoplasticity,and large deformation problems,as well as the performance of two-dimensional splitting meshless methods in solving the 3D Helmholtz equation. 展开更多
关键词 Meshless method improved element-free Galerkin method singular weight function nonsingular weight function interpolating element-free Galerkin method complex variable element-free Galerkin method dimension splitting method dimension splitting meshless method
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New injection method using composite gel system and gel breaker to improve sweep efficiency and mitigate formation damage 认领 引用
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作者 Jiong Zhang Hong-Gen Tan +4 位作者 Tao Zhang Ying-Qi Gao Hong-Bin Cheng Hong-Yu Li Dao-Yi Zhu 《Petroleum Science》 SCIE EI CAS CSCD 2026年第1期383-392,共10页
Polymer gels can cause damage to lowly to moderately permeable formations during both oilfield applications and laboratory evaluations of conformance treatment.To enhance reservoir sweep efficiency and oil recovery wh... Polymer gels can cause damage to lowly to moderately permeable formations during both oilfield applications and laboratory evaluations of conformance treatment.To enhance reservoir sweep efficiency and oil recovery while using conventional bullhead injection,this study proposed a new injection method whe re a small amount of branched preformed particle gel(BPPG) was injected as a preflush slug before the injection of in situ cross-linked polymer gel(ISCPG).After that,a gel breaker was pumped to degrade particle gel.The breaking behavior of ISCPG and particle gels in gel breaker was first evaluated using static gel-breaking tests.Core plugging experiments combined with nuclear magnetic resonance(NMR) measurements were then employed to assess the sweep efficiency improvement and oil displacement effects of the ISCPG-BPPG composite gel system.Results showed that injecting the ISCPGBPPG composite gel system into core samples,followed by a gel breaker,could effectively remove damage at the end faces of lowly to moderately permeable formations.Thus,it expanded the subsequent waterflood sweep volume and thus increased oil recovery by 28.43% original oil in place(OOIP).The gel breaker contained a 2:8 ratio of depolymerizing agent to ammonium persulfate at 2 wt% concentration.Moreover,BPPG in the composite gel system could act as a preflush slug to block subsequent ISCPG invasion into lowly to moderately permeable formations,reducing damage to oil-bearing formations.Compared to the single-gel injection method,the ISCPG-BPPG composite gel system demonstrated superior conformance improvement capability and oil recovery after gel-breaking treatment.The NMR technology was employed to analyze the novel conformance improvement method based on composite gel and gel-breaking mechanisms at the microscopic scale. 展开更多
关键词 Polymer gel Particle gel Nuclear magnetic resonance technology Damage protection method Conformance improvement
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Topology Optimization of Orthotropic Materials Using the Improved Element-Free Galerkin (IEFG) Method 认领 引用
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作者 Wenna He Yichen Yang +1 位作者 Dongqiong Liang Heng Cheng 《Computers, Materials & Continua》 SCIE EI 2025年第4期1415-1437,共23页
In this paper,we develop an advanced computational framework for the topology optimization of orthotropic materials using meshless methods.The approximation function is established based on the improved moving least s... In this paper,we develop an advanced computational framework for the topology optimization of orthotropic materials using meshless methods.The approximation function is established based on the improved moving least squares(IMLS)method,which enhances the efficiency and stability of the numerical solution.The numerical solution formulas are derived using the improved element-free Galerkin(IEFG)method.We introduce the solid isotropic microstructures with penalization(SIMP)model to formulate a mathematical model for topology opti-mization,which effectively penalizes intermediate densities.The optimization problem is defined with the numerical solution formula and volume fraction as constraints.The objective function,which is the minimum value of flexibility,is optimized iteratively using the optimization criterion method to update the design variables efficiently and converge to an optimal solution.Sensitivity analysis is performed using the adjoint method,which provides accurate and efficient gradient information for the optimization algorithm.We validate the proposed framework through a series of numerical examples,including clamped beam,cantilever beam,and simply supported beam made of orthotropic materials.The convergence of the objective function is demonstrated by increasing the number of iterations.Additionally,the stability of the iterative process is analyzed by examining the fluctuation law of the volume fraction.By adjusting the parameters to an appropriate range,we achieve the final optimization results of the IEFG method without the checkerboard phenomenon.Comparative studies between the Element-Free Galerkin(EFG)and IEFG methods reveal that both methods yield consistent optimization results under identical parameter settings.However,the IEFG method significantly reduces computational time,highlighting its efficiency and suitability for orthotropic materials. 展开更多
关键词 Solid isotropic microstructures with penalization method variable density method sensitivity analysis improved element-free Galerkin method meshless method
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Numerical Exploration on Load Transfer Characteristics and Optimization of Multi-Layer Composite Pavement Structures Based on Improved Transfer Matrix Method 认领 引用
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作者 Guo-Zhi Li Hua-Ping Wang +2 位作者 Si-Kai Wang Jing-Cheng Zhou Ping Xiang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2025年第12期3165-3195,共31页
Transportation structures such as composite pavements and railway foundations typically consist of multi-layered media designed to withstand high bearing capacity.A theoretical understanding of load transfer mechanism... Transportation structures such as composite pavements and railway foundations typically consist of multi-layered media designed to withstand high bearing capacity.A theoretical understanding of load transfer mechanisms in these multi-layer composites is essential,as it offers intuitive insights into parametric influences and facilitates enhanced structural performance.This paper employs an improved transfer matrix method to address the limitations of existing theoretical approaches for analyzing multi-layer composite structures.By establishing a twodimensional composite pavement model,it investigates load transfer characteristics and validates the accuracy through finite element simulation.The proposed method offers a straightforward analytical approach for examining internal interactions between structural layers.Case studies indicate that the concrete surface layer is the main load-bearing layer for most vertical normal and shear stresses.The soil base layer reduces the overall mechanical response of the substructure,while horizontal actions increase the risk of interfacial slip and cracking.Structural optimization analysis demonstrates that increasing the thickness of the concrete surface layer,enhancing the thickness and stiffness of the soil base layer,or incorporating gradient layers can significantly mitigate these risks of interfacial slip and cracking.The findings of this study can guide the optimization design,parameter analysis,and damage prevention of multi-layer composite structures. 展开更多
关键词 Multi-layer composite pavement improved theoretical analysis transfer matrix method structural optimization damage prevention
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Improved Guide-Weight method for multi-material topology optimization under inertial loads based on the alternating active-phase algorithm 认领 引用
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作者 Zihao Meng Yiru Ren 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2025年第8期138-148,共11页
The application of multi-material topology optimization affords greater design flexibility compared to traditional single-material methods.However,density-based topology optimization methods encounter three unique cha... The application of multi-material topology optimization affords greater design flexibility compared to traditional single-material methods.However,density-based topology optimization methods encounter three unique challenges when inertial loads become dominant:non-monotonous behavior of the objective function,possible unconstrained characterization of the optimal solution,and parasitic effects.Herein,an improved Guide-Weight approach is introduced,which effectively addresses the structural topology optimization problem when subjected to inertial loads.Smooth and fast convergence of the compliance is achieved by the approach,while also maintaining the effectiveness of the volume constraints.The rational approximation of material properties model and smooth design are utilized to guarantee clear boundaries of the final structure,facilitating its seamless integration into manufacturing processes.The framework provided by the alternating active-phase algorithm is employed to decompose the multi-material topological problem under inertial loading into a set of sub-problems.The optimization of multi-material under inertial loads is accomplished through the effective resolution of these sub-problems using the improved Guide-Weight method.The effectiveness of the proposed approach is demonstrated through numerical examples involving two-phase and multi-phase materials. 展开更多
关键词 Topology optimization Improved Guide-Weight method Alternating active-phase algorithm Inertial loads Multi-material
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Stability evaluation of the tunnel portal slope based on improved unascertained measure method 认领 引用
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作者 ZHANG Cengceng HUANG Shibing +1 位作者 ZHENG Luobin LI Wen 《Journal of Mountain Science》 SCIE CSCD 2025年第6期2261-2275,共15页
The stability of the tunnel portal slope is crucial for ensuring safe tunnel construction.Thus,a sound stability evaluation is of significance.Given the unique geological characteristics of tunnel portal slopes,it is ... The stability of the tunnel portal slope is crucial for ensuring safe tunnel construction.Thus,a sound stability evaluation is of significance.Given the unique geological characteristics of tunnel portal slopes,it is necessary to establish a specific evaluation indicator system that differs from those used for ordinary slopes.Based on the unascertained measure method,uncertainties in the indicator are addressed by introducing the left and right half cloud asymmetric cloud model to optimize the linear membership function.The subjectivity of confidence criterion level identification is also improved by using the Euclidean distance method.Thus,a stability evaluation model for the tunnel portal slope is established based on the improved unascertained measure method.Finally,using the collected tunnel portal slope data,the results of four evaluation methods are compared with the safety factor levels.The evaluation methods include the traditional unascertained measure method,the method improved by using the left and right half cloud asymmetric cloud model,the method improved by using the Euclidean distance method,and the method improved by using both the left and right half cloud asymmetric cloud model and the Euclidean distance method.The results show that the accuracy rates of these four methods are 50%,55%,85%,and 90%,respectively.Among them,the joint improvement method has the slightest deviation,with only one level,while the other three methods had deviations of two levels.This result verifies the stability and effectiveness of the joint improvement method,providing a reference for tunnel portal slope stability evaluation. 展开更多
关键词 Tunnel portal slope Stability evaluation Improved unascertained measure method Left and right half cloud asymmetric cloud model Euclidean distance method
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Performance evaluation of sponge city PPP projects using improved matter-element extension method 认领 引用
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作者 CHEN Zhi-ding HU Min-qian 《Ecological Economy》 2025年第2期151-168,共18页
Sponge city(SPC)is proposed to solve the issues such as the degradation of urban water ecosystem environment,imbalanced water resource allocation,urban water logging,and water contamination.The PPP(Public Private Part... Sponge city(SPC)is proposed to solve the issues such as the degradation of urban water ecosystem environment,imbalanced water resource allocation,urban water logging,and water contamination.The PPP(Public Private Partnership)model is combined to release the government pressure of SPC project construction.The development of the SPC-PPP model makes significant contributions to the sustainable development and the enhancement of urban resilience against water-related disasters.However,there is no scientific performance evaluation system on its operation period has been conducted.Therefore,the SPC-PPP Evaluation model aims to objectively and reasonably assess project effectiveness,promote its development and refine the evaluation framework.This paper has set up the MEE model for performance evaluation,with improved Matter-Element Extension method to assign values to the evaluation indices.The research results show that:(1)The MEE model is more accurate in the performance evaluation and its effectiveness is reflected in its ability to capture the correlation among different indices in the same membership,rather than merely focusing on individual indices.(2)The proposed approach provided a new aspect for performance evaluation,improving the accuracy of evaluation and promoting the development of SPC-PPP project. 展开更多
关键词 public private partnership sponge city performance evaluation improved matter-element extension method
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Improved normalization method for ductile fracture toughness determination based on dimensionless load separation principle 认领 引用 被引量：12
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作者 Chen Bao Lixun Cai +2 位作者 Kaikai Shi Chen Dan Yao Yao 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2015年第2期168-181,共14页
This study successfully deals with the inhomogeneous dimension problem of load separation assumption, which is the theoretical basis of the normalization method. According to the dimensionless load separation principl... This study successfully deals with the inhomogeneous dimension problem of load separation assumption, which is the theoretical basis of the normalization method. According to the dimensionless load separation principle, the normalization method has been improved by intro- ducing a forcible blunting correction. With the improved normalization method, the J-resistance curves of five different metallic materials of CT and SEB specimens are estimated. The forcible blunting correction of initial crack size plays an important role in the J-resistance curve estima- tion, which is closely related to the strain hardening level of material. The higher level of strain hardening leads to a greater difference in JQ determined by different slopes of the blunting line. If the blunting line coefficient recommended by ASTM E1820-11 is used in the improved nor- realization method, it will lead to greater fracture resistance than that processed by the blunting line coefficient recommended by ISO 12135-2002. Therefore, the influence of the blunting line on the determination of JQ must be taken into full account in the fracture toughness assessment of metallic materials. 展开更多
关键词 dimensionless load separation improved normalization method dimension inho-mogeneous J-resistance curve forcible blunting correction
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An improved interpolating element-free Galerkin method with a nonsingular weight function for two-dimensional potential problems 认领 引用 被引量：18
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作者 王聚丰 孙凤欣 程玉民 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第9期53-59,共7页
In this paper, an improved interpolating moving least-square （IIMLS） method is presented. The shape function of the IIMLS method satisfies the property of the Kronecker 5 function. The weight function used in the II... In this paper, an improved interpolating moving least-square （IIMLS） method is presented. The shape function of the IIMLS method satisfies the property of the Kronecker 5 function. The weight function used in the IIMLS method is nonsingular. Then the IIMLS method can overcome the difficulties caused by the singularity of the weight function in the IMLS method. The number of unknown coefficients in the trial function of the IIMLS method is less than that of the moving least-square （MLS） approximation. Then by combining the IIMLS method with the Galerkin weak form of the potential problem, the improved interpolating element-free Galerkin （IIEFG） method for two-dimensional potential problems is presented. Compared with the conventional element-free Galerkin （EFG） method, the IIEFG method can directly use the essential boundary conditions. Then the IIEFG method has higher accuracy. For demonstration, three numerical examples are solved using the IIEFG method. 展开更多
关键词 meshless method improved interpolating moving least-square method improved inter-polating element-free Galerkin method potential problem
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Water quality evaluation based on improved fuzzy matter-element method 认领 引用 被引量：25
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作者 Dongjun Liu Zhihong Zou 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2012年第7期1210-1216,共7页
For natural water, method of water quality evaluation based on improved fuzzy matter-element evaluation method is presented. Two important parts are improved, the weights determining and fuzzy membership functions. Th... For natural water, method of water quality evaluation based on improved fuzzy matter-element evaluation method is presented. Two important parts are improved, the weights determining and fuzzy membership functions. The coefficient of variation of each indicator is used to determine the weight instead of traditional calculating superscales method. On the other hand, fuzzy matter-elements are constructed, and normal membership degrees are used instead of traditional trapezoidal ones. The composite fuzzy matter-elements with associated coefficient are constructed through associated transformation. The levels of natural water quality are determined according to the principle of maximum correlation. The improved fuzzy matter-element evaluation method is applied to evaluate water quality of the Luokou mainstream estuary at the first ten weeks in 2011 with the coefficient of variatiola method determining the weights. Water quality of Luokou mainstream estuary is dropping from level I to level II. The results of the improved evaluation method are basically the same as the official water quality. The variation coefficient method can reduce the workload, and overcome the adverse effects from abnormal values, compared with the traditional calculating superscales method. The results of improved fuzzy matter- element evaluation method are more credible than the ones of the traditional evaluation method. The improved evaluation method can use information of monitoring data more scientifically and comprehensively, and broaden a new evaluation method for water quality assessment. 展开更多
关键词 water quality improved fuzzy matter-element evaluation method synthetic evaluation variation coefficient method normal membership Key words： water quality improved fuzzy matter-element evaluation method synthetic evaluation variation coefficient method normal membership
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An improved boundary element-free method (IBEFM) for two-dimensional potential problems 认领 引用 被引量：30
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作者 任红萍 程玉民 张武 《Chinese Physics B》 SCIE EI CAS 2009年第10期4065-4073,共9页
The interpolating moving least-squares （IMLS） method is discussed first in this paper. And the formulae of the IMLS method obtained by Lancaster are revised. Then on the basis of the boundary element-free method （B... The interpolating moving least-squares （IMLS） method is discussed first in this paper. And the formulae of the IMLS method obtained by Lancaster are revised. Then on the basis of the boundary element-free method （BEFM）, combining the boundary integral equation （BIE） method with the IMLS method, the improved boundary element-free method （IBEFM） for two-dimensional potential problems is presented, and the corresponding formulae of the IBEFM are obtained. In the BEFM, boundary conditions are applied directly, but the shape function in the MLS does not satisfy the property of the Kronecker ~ function. This is a problem of the BEFM, and must be solved theoretically. In the IMLS method, when the shape function satisfies the property of the Kronecker 5 function, then the boundary conditions, in the meshless method based on the IMLS method, can be applied directly. Then the IBEFM, based on the IMLS method, is a direct meshless boundary integral equation method in which the basic unknown quantity is the real solution of the nodal variables, and the boundary conditions can be applied directly and easily, thus it gives a greater computational precision. Some numerical examples are presented to demonstrate the method. 展开更多
关键词 moving least-squares approximation interpolating moving least-squares method mesh- less method improved boundary element-free method potential problem
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A method for predicting the water-flowing fractured zone height based on an improved key stratum theory 认领 引用 被引量：15
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作者 Jianghui He Wenping Li +3 位作者 Kaifang Fan Wei Qiao Qiqing Wang Liangning Li 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第1期61-71,共11页
In the process of using the original key stratum theory to predict the height of a water-flowing fractured zone(WFZ),the influence of rock strata outside the calculation range on the rock strata within the calculation... In the process of using the original key stratum theory to predict the height of a water-flowing fractured zone(WFZ),the influence of rock strata outside the calculation range on the rock strata within the calculation range as well as the fact that the shape of the overburden deformation area will change with the excavation length are ignored.In this paper,an improved key stratum theory(IKS theory)was proposed by fixing these two shortcomings.Then,a WFZ height prediction method based on IKS theory was established and applied.First,the range of overburden involved in the analysis was determined according to the tensile stress distribution range above the goaf.Second,the key stratum in the overburden involved in the analysis was identified through IKS theory.Finally,the tendency of the WFZ to develop upward was determined by judging whether or not the identified key stratum will break.The proposed method was applied and verified in a mining case study,and the reasons for the differences in the development patterns between the WFZs in coalfields in Northwest and East China were also fully explained by this method. 展开更多
关键词 Coal mining Water-flowing fractured zone height Prediction method Improved key stratum theory
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An improved complex variable element-free Galerkin method for two-dimensional elasticity problems 认领 引用 被引量：4
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作者 Bai Fu-Nong Li Dong-Ming +1 位作者 Wang Jian-Fei Cheng Yu-Min 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第2期56-65,共10页
In this paper, the improved complex variable moving least-squares （ICVMLS） approximation is presented. The ICVMLS approximation has an explicit physics meaning. Compared with the complex variable moving least-squar... In this paper, the improved complex variable moving least-squares （ICVMLS） approximation is presented. The ICVMLS approximation has an explicit physics meaning. Compared with the complex variable moving least-squares （CVMLS） approximations presented by Cheng and Ren, the ICVMLS approximation has a great computational precision and efficiency. Based on the element-free Galerkin （EFG） method and the ICVMLS approximation, the improved complex variable element-free Galerkin （ICVEFG） method is presented for two-dimensional elasticity problems, and the corresponding formulae are obtained. Compared with the conventional EFC method, the ICVEFG method has a great computational accuracy and efficiency. For the purpose of demonstration, three selected numerical examples are solved using the ICVEFG method. 展开更多
关键词 meshless method improved complex variable moving least-squares approximation improved complex variable element-free Galerkin method elasticity
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The improved element-free Galerkin method forthree-dimensional wave equation 认领 引用 被引量：17
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作者 Zan Zhang Dong-Ming Li +1 位作者 Yu-Min Cheng Kim Moew Liew 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第3期808-818,共11页
The paper presents the improved element-free Galerkin （IEFG） method for three-dimensional wave propa- gation. The improved moving least-squares （IMLS） approx- imation is employed to construct the shape function, w... The paper presents the improved element-free Galerkin （IEFG） method for three-dimensional wave propa- gation. The improved moving least-squares （IMLS） approx- imation is employed to construct the shape function, which uses an orthogonal function system with a weight function as the basis function. Compared with the conventional moving least-squares （MLS） approximation, the algebraic equation system in the IMLS approximation is not ill-conditioned, and can be solved directly without deriving the inverse matrix. Because there are fewer coefficients in the IMLS than in the MLS approximation, fewer nodes are selected in the IEFG method than in the element-free Galerkin method. Thus, the IEFG method has a higher computing speed. In the IEFG method, the Galerkin weak form is employed to obtain a dis- cretized system equation, and the penalty method is applied to impose the essential boundary condition. The traditional difference method for two-point boundary value problems is selected for the time discretization. As the wave equations and the boundary-initial conditions depend on time, the scal- ing parameter, number of nodes and the time step length are considered for the convergence study. 展开更多
关键词 Weighted orthogonal function Improved mov-ing least squares （IMLS） approximation. Improved element-free Galerkin （IEFG） method Penalty method Temporaldiscretization Wave equation
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Analysis of elastoplasticity problems using an improved complex variable element-free Galerkin method 认领 引用 被引量：6
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作者 程玉民 刘超 +1 位作者 白福浓 彭妙娟 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第10期16-25,共10页
In this paper, based on the conjugate of the complex basis function, a new complex variable moving least-squares approximation is discussed. Then using the new approximation to obtain the shape function, an improved c... In this paper, based on the conjugate of the complex basis function, a new complex variable moving least-squares approximation is discussed. Then using the new approximation to obtain the shape function, an improved complex variable element-free Galerkin（ICVEFG） method is presented for two-dimensional（2D） elastoplasticity problems. Compared with the previous complex variable moving least-squares approximation, the new approximation has greater computational precision and efficiency. Using the penalty method to apply the essential boundary conditions, and using the constrained Galerkin weak form of 2D elastoplasticity to obtain the system equations, we obtain the corresponding formulae of the ICVEFG method for 2D elastoplasticity. Three selected numerical examples are presented using the ICVEFG method to show that the ICVEFG method has the advantages such as greater precision and computational efficiency over the conventional meshless methods. 展开更多
关键词 meshless method complex variable moving least-squares approximation improved complex vari- able element-free Galerkin method elastoplasticity
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A measurement method for distinguishing the real contact area of rough surfaces of transparent solids using improved Otsu technique 认领 引用 被引量：4
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作者 宋保江 阎绍泽 向吴维凯 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第1期354-360,共7页
An experimental method of measuring the real contact area of transparent blocks based on the principle of total internal reflection is presented, intending to support the investigation of friction characteristics, hea... An experimental method of measuring the real contact area of transparent blocks based on the principle of total internal reflection is presented, intending to support the investigation of friction characteristics, heat conduction, and energy dissipation at the contact interface. A laser sheet illuminates the contact interface, and the transmitted laser sheet is projected onto a screen. Then the contact information is acquired from the screen by a camera. An improved Otsu method is proposed to process the data of experimental images. It can compute the threshold of the overall image and filter out all the pixels one by one. Through analyzing the experimental results, we describe the relationship between the real contact area and the positive pressure during a continuous loading process, at different loading rates, with the polymethyl methacrylate（PMMA）material. A hysteresis phenomenon in the relationship between the real contact area and the positive pressure is found and explained. 展开更多
关键词 real contact area total internal reflection improved Otsu method hysteresis phenomenon
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Correction of cosine oscillation to the improved correlation method of estimating the amplitude of gravitational background signal 认领 引用 被引量：2
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作者 巫伟皇 田苑 +2 位作者 薛超 罗杰 邵成刚 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第4期122-131,共10页
In the measurement of G with the angular acceleration method,the improved correlation method developed by Wu et al.（Wu W H,Tian Y,Luo J,Shao C G,Xu J H and Wang DH 2016 Rev.Sci.Instrum.87 094501） is used to accurate... In the measurement of G with the angular acceleration method,the improved correlation method developed by Wu et al.（Wu W H,Tian Y,Luo J,Shao C G,Xu J H and Wang DH 2016 Rev.Sci.Instrum.87 094501） is used to accurately estimate the amplitudes of the prominent harmonic components of the gravitational background signal with time-varying frequency.Except the quadratic slow drift,the angular frequency of the gravitational background signal also includes a cosine oscillation coming from the useful angular acceleration signal,which leads to a deviation from the estimated amplitude.We calculate the correction of the cosine oscillation to the amplitude estimation.The result shows that the corrections of the cosine oscillation to the amplitudes of the fundamental frequency and second harmonic components obtained by the improved correlation method are within respective errors. 展开更多
关键词 gravitational background signal improved correlation method correction cosine oscillation
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