<em>A method of scenario computing is developed for modeling systems with deep uncertainty</em>. The method consists three complementary parts: hybrid modelling, diverse computing, and interactive validation. Hybrid modelling is to dynamically develop models with merging historical knowledges and observed information. Diversity computation is to simulate multiple plausible scenarios about system future. Interactive validation helps scenario computing process being on the right way instead of deviating. Two cases are provided in this paper applying scenario computing, one is earthquake and the other is driving and transportation. The results show good performance of scenario computing method in modeling uncertainty systems.

A method of scenario computing is developed for modeling systems with deep uncertainty. The method consists three complementary parts: hybrid modelling, diverse computing, and interactive validation. Hybrid modelling is to dynamically develop models with merging historical knowledges and observed information. Diversity computation is to simulate multiple plausible scenarios about system future. Interactive validation helps scenario computing process being on the right way instead of deviating. Two cases are provided in this paper applying scenario computing, one is earthquake and the other is driving and transportation. The results show good performance of scenario computing method in modeling uncertainty systems. © 2018, The Editorial Board of Journal of System Simulation. All right reserved.

社区是公共安全治理的基本单元,社区安全研究意义重大.该文面向社区风险防范的重大需求,首先,从人、物及管理3个角度厘清社区风险的来源,剖析社区风险的特性及原因;然后,阐述社区风险防范的内涵,提出监测监控,预测预警和智能防范是社区风险防范的关键技术,在综合分析当前风险防范研究现状及发展趋势的基础上,指出大数据平台是社区风险防范的基础支撑;最后,分别从功能、结构及构建流程3个层面展开面向社区风险防范大数据平台的理论架构设计.为社区风险防范及大数据平台的基础理论研究大数据平台搭建及风险防范提供理论和技术支撑.

This paper proposes a new constitutive model for geotechnical materials that consists two basic constitutive functions, the free energy function and the dissipation rate function, within the framework of hyperplastic theory. This free energy function is capable of describing the pressure-dependent elastic behavior of soils. The new constructed dissipation rate function accounts for the frictional mechanism of energy dissipation. Based on this dissipation rate function, the non-associated flow rule can be obtained. Furthermore, the convexity of the yield surface that is derived from the dissipation rate function is proved. Predictions of the behavior of a soil sample using this new constitutive model agree well with triaxial test data under drained and undrained conditions.

社区是公共安全治理的基本单元,社区安全研究意义重大.该文面向社区风险防范的重大需求,首先,从人、物及管理3个角度厘清社区风险的来源,剖析社区风险的特性及原因;然后,阐述社区风险防范的内涵,提出监测监控,预测预警和智能防范是社区风险防范的关键技术,在综合分析当前风险防范研究现状及发展趋势的基础上,指出大数据平台是社区风险防范的基础支撑;最后,分别从功能、结构及构建流程3个层面展开面向社区风险防范大数据平台的理论架构设计.为社区风险防范及大数据平台的基础理论研究大数据平台搭建及风险防范提供理论和技术支撑.

提出了一种面向深度不确定系统的情景计算方法,该方法由三部分组成:混合建模、多样性计算、交互验证。混合建模是基于已有模型和相关数据,实现快速高效的动态建模;多样性计算指通过大规模计算实现对系统多样化演化的分析和预测;交互验证是基于人工计算系统与真实客观系统之间的交互验证保障情景计算结果的有效和可靠。给出了地震波经过建筑物后的传播与叠加效应计算和交通与驾驶行为计算两个算例,分析了情景计算方法对不确定系统仿真计算的有效性与应用前景。

In order to apply classical micromechanics in predicting the effective prop-erties of nanocomposites incorporating interface energy, a concept of equivalent inclusion (EI) is usually adopted. The properties of EI are obtained by embedding a single inclusion with the interface into an infinite matrix. However, whether such an EI is universal for different micromechanics-based methods is rarely discussed in the literature. In this pa-per, the interface energy theory is used to study the applicability of the above mentioned EI. It is found that some elastic properties of the EI are related only to the properties of the inclusion and the interface, whereas others are also related to the properties of the matrix. The former properties of the EI can be applied to both the classical Mori-Tanaka method (MTM) and the generalized self-consistent method (GSCM). However, the latter can be applied only to the MTM. Two kinds of new EIs are proposed for the GSCM and used to estimate the effective mechanical properties of nanocomposites.

In order to apply classical micromechanics in predicting the effective prop-erties of nanocomposites incorporating interface energy, a concept of equivalent inclusion (EI) is usually adopted. The properties of EI are obtained by embedding a single inclusion with the interface into an infinite matrix. However, whether such an EI is universal for different micromechanics-based methods is rarely discussed in the literature. In this pa-per, the interface energy theory is used to study the applicability of the above mentioned EI. It is found that some elastic properties of the EI are related only to the properties of the inclusion and the interface, whereas others are also related to the properties of the matrix. The former properties of the EI can be applied to both the classical Mori-Tanaka method (MTM) and the generalized self-consistent method (GSCM). However, the latter can be applied only to the MTM. Two kinds of new EIs are proposed for the GSCM and used to estimate the effective mechanical properties of nanocomposites.

Surface/interface effect plays a significant role in the study of the mechanical properties of nano composites. Most previous papers in the literature only considered the surface/interface elasticity, whereas some papers only considered the residual surface/interface stress (surface/interface tension). In this paper, an energy-based surface/interface theory is applied to systematically study the effective thermo-elastic properties of unidirectional fiber-reinforced nanocomposites, in which both the surface/interface elasticity and the residual surface/interface stress are included. The emphasis is particularly placed on the influence of the residual interface stress on the effective thermo-elastic properties of such nanocomposites, since this influence was ignored by many previous authors. Analytical expressions of five effective transversely isotropic elastic constants are derived, in which a modified generalized self consistent method is suggested to obtain an explicit expression of the size-dependent effective transverse shear modulus. Furthermore, with an introduced concept of 'equivalent fiber' (i.e., a fiber together with its interface), the effective thermal expansion coefficients and the effective specific heat at constant strain of the fiber-reinforced nanocomposite are obtained. Finally, numerical examples are illustrated, and the effect of residual interface stress on the effective thermo-elastic properties of the fibrous nanocomposite is discussed. It is shown that the residual interface stress has a significant effect on the overall thermo-elastic properties of the nanocomposites. (C) 2016 Elsevier Ltd. All rights reserved.

A new micromechanics method is proposed to investigate the effective properties of saturated porous media with connected pores. This topic is seldom discussed in the literature because it is difficult to describe the connected pores and skeleton using conventional micromechanics methods. A new micromechanics model (i.e., Model I) is suggested to characterize such saturated porous media in which the pores saturated by fluid are taken as the matrix, and the interconnected randomly oriented long fiber (ROLF)-like solid skeleton is taken as the inclusions. The proposed model is verified by numerical simulations; the simulation results indicate that the difference of the elastic constants calculated for media with interconnected pores and for those with dispersed ROLF solid inclusions is small. Thus, the elastic moduli of Model I can be treated as approximate values for porous media with connected pores. Further, a modified Eshelby tensor for spherical inclusions is derived based on the equivalency of the elastic moduli of Model I and a conventional micromechanics model in which spherical fluid inclusions are distributed randomly in a solid matrix. By means of the modified Eshelby tenor, conventional micromechanics methods can be utilized directly to calculate the effective mechanical and thermal properties of saturated porous media with interconnected pores. Some examples are presented to show that the macroscopic elastic moduli predicted by the proposed method are in good agreement with test data found in the literature.

Surface/interface effect plays a significant role in the study of the mechanical properties of nano composites. Most previous papers in the literature only considered the surface/interface elasticity, whereas some papers only considered the residual surface/interface stress (surface/interface tension). In this paper, an energy-based surface/interface theory is applied to systematically study the effective thermo-elastic properties of unidirectional fiber-reinforced nanocomposites, in which both the surface/interface elasticity and the residual surface/interface stress are included. The emphasis is particularly placed on the influence of the residual interface stress on the effective thermo-elastic properties of such nanocomposites, since this influence was ignored by many previous authors. Analytical expressions of five effective transversely isotropic elastic constants are derived, in which a modified generalized self consistent method is suggested to obtain an explicit expression of the size-dependent effective transverse shear modulus. Furthermore, with an introduced concept of 'equivalent fiber' (i.e., a fiber together with its interface), the effective thermal expansion coefficients and the effective specific heat at constant strain of the fiber-reinforced nanocomposite are obtained. Finally, numerical examples are illustrated, and the effect of residual interface stress on the effective thermo-elastic properties of the fibrous nanocomposite is discussed. It is shown that the residual interface stress has a significant effect on the overall thermo-elastic properties of the nanocomposites. (C) 2016 Elsevier Ltd. All rights reserved.

A new micromechanics method is proposed to investigate the effective properties of saturated porous media with connected pores. This topic is seldom discussed in the literature because it is difficult to describe the connected pores and skeleton using conventional micromechanics methods. A new micromechanics model (i.e., Model I) is suggested to characterize such saturated porous media in which the pores saturated by fluid are taken as the matrix, and the interconnected randomly oriented long fiber (ROLF)-like solid skeleton is taken as the inclusions. The proposed model is verified by numerical simulations; the simulation results indicate that the difference of the elastic constants calculated for media with interconnected pores and for those with dispersed ROLF solid inclusions is small. Thus, the elastic moduli of Model I can be treated as approximate values for porous media with connected pores. Further, a modified Eshelby tensor for spherical inclusions is derived based on the equivalency of the elastic moduli of Model I and a conventional micromechanics model in which spherical fluid inclusions are distributed randomly in a solid matrix. By means of the modified Eshelby tenor, conventional micromechanics methods can be utilized directly to calculate the effective mechanical and thermal properties of saturated porous media with interconnected pores. Some examples are presented to show that the macroscopic elastic moduli predicted by the proposed method are in good agreement with test data found in the literature.

In multiphase particulate composites, the deviation and mismatch of the elastic moduli of different particles may significantly affect the overall mechanical performance of the composites. This study investigates the effects of such deviations on the macroscopic properties of multiphase composites via an iterative micromechanics-based method. The elastic properties of the particles are assumed to obey certain statistical distributions. In the proposed iterative method, the composites are divided into multiple two-phase composites and their strain concentration tensors are derived by means of the inclusion matrix-reference medium model, which is a modification of the generalized self-consistent method. Iterative solutions are established that take into account the effects of the variation in the elastic properties of the particles in terms of the effective shear and bulk moduli. The findings show that the proposed iterative method converges quickly and that the results agree well with the experimental data for three-phase composites. In addition, the model indicates that the variation in the elastic properties of the particles does have a significant effect on the effective moduli of the composites. (C) 2015 American Society of Civil Engineers.

In multiphase particulate composites, the deviation and mismatch of the elastic moduli of different particles may significantly affect the overall mechanical performance of the composites. This study investigates the effects of such deviations on the macroscopic properties of multiphase composites via an iterative micromechanics-based method. The elastic properties of the particles are assumed to obey certain statistical distributions. In the proposed iterative method, the composites are divided into multiple two-phase composites and their strain concentration tensors are derived by means of the inclusion matrix-reference medium model, which is a modification of the generalized self-consistent method. Iterative solutions are established that take into account the effects of the variation in the elastic properties of the particles in terms of the effective shear and bulk moduli. The findings show that the proposed iterative method converges quickly and that the results agree well with the experimental data for three-phase composites. In addition, the model indicates that the variation in the elastic properties of the particles does have a significant effect on the effective moduli of the composites. (C) 2015 American Society of Civil Engineers.

The interface energy theory developed by Huang et al. is further extended to incorporate the effect of the residual interface stresses on the effective specific heats of multiphase thermoelastic nanocomposites. First, a micromechanics-based method is employed to derive the expressions of the effective specific heats at constant-strain and constant-stress of the composites. Second, in order to take into account the influence of the interface stresses on the overall properties of the nanocomposites, a thermoelastic interface constitutive relation expressed in terms of the first Piola-Kirchhoff interface stresses and the Lagrangian description of the generalized Young-Laplace equations are presented. Finally, by means of the Helmholtz free energy of the "equivalent inclusion" (the inclusion together with its interface), analytical expressions of the size-dependent effective specific heats of the nanocomposites are obtained. The model is illustrated by an example of a "three-phase thermoelastic composite" showing that the overall properties of the nanocomposites are influenced by the "residual interface stresses," which was sometimes ignored in the literature.

The interface energy theory developed by Huang et al. is further extended to incorporate the effect of the residual interface stresses on the effective specific heats of multiphase thermoelastic nanocomposites. First, a micromechanics-based method is employed to derive the expressions of the effective specific heats at constant-strain and constant-stress of the composites. Second, in order to take into account the influence of the interface stresses on the overall properties of the nanocomposites, a thermoelastic interface constitutive relation expressed in terms of the first Piola-Kirchhoff interface stresses and the Lagrangian description of the generalized Young-Laplace equations are presented. Finally, by means of the Helmholtz free energy of the "equivalent inclusion" (the inclusion together with its interface), analytical expressions of the size-dependent effective specific heats of the nanocomposites are obtained. The model is illustrated by an example of a "three-phase thermoelastic composite" showing that the overall properties of the nanocomposites are influenced by the "residual interface stresses," which was sometimes ignored in the literature.

A micromechanics-based elastoplastic constitutive model for porous materials is proposed. With an assumption of modified three-dimensional Ramberg-Osgood equation for the compressible matrix material, the variational principle based on a linear comparison composite is applied to study the effective mechanical properties of the porous materials. Analytical expressions of elastoplastic constitutive relations are derived by means of micromechanics principles and homogenization procedures. It is demonstrated that the derived expressions do not involve any additional material constants to be fitted with experimental data. The model can be useful in the prediction of mechanical properties of elastoplastic porous solids.

In this paper, a new method of topological cleanup for quadrilateral mesh is presented. The method first selects a patch of mesh around an irregular node. It then seeks the best connection of the selected patch according to its irregular valence using a new topological operation: small polygon reconnection (SPR). By replacing the original patch with an optimal one that has less irregular valence, mesh quality can be improved. Three applications based on the proposed approach are enumerated: (1) improving the quality of a quadrilateral mesh, (2) converting a triangular mesh to a quadrilateral one, and (3) adapting a triangle generator to a quadrilateral one. The presented method is highly effective in all three applications.