“多方建模”化解物理知识难点初探

物理模型是物理学中常用的科学方法,能使复杂事物简单化、纯粹化,有利于真理的探索与发现。在实际教学中,提高物理模型的显性化水平,组织训练物理模型法,可促进自主构建物理模型去解释事物、理解知识、解决问题。对于某些难点知识,还可以循序渐进地层层构建模型,即"多方建模",使难点知识得到突破。本文以闭合电路教学为例,初步探讨了多方建模化解知识难点的方法。

“多方建模”突破物理模型思维障碍——以理想气体压强微观表达式的探究教学为例

培养物理模型思维是落实学科核心素养的重要体现, 在实际教学中开展物理模型教学却存在种种思维障碍.通过科学探究活动、 提高建模教学显性化水平、 在问题解决中训练建模方法等教学策略有利于消除建模思维障碍.其中, “多方建模” 是落实前述教学策略的具体方法, 十分有利于突破物理模型思维障碍.

浅谈多方多阶段BIM模型的重要性

各地新发布的建筑领域信息模型(BIM)政策,均强调“一模到底”“一模多用”,但是当前的现状是利益主体不一致,建设阶段不一致,技术要求也不一样,应鼓励和提倡多方建模、多阶段建模。作者从建筑工程设计、施工、运维三个阶段,对各个阶段的BIM模型的必要性、特点进行描述,并且创造性的提出以出图为目的的BIM模型称为设计数字模型,以算量为目的的BIM模型称为算量数字模型,以运维为目的的BIM模型为运维数字模型,厘清了设计数字模型、算量数字模型和运维数字模型的概念和内涵,提出了检验数字模型质量的标准和要求,期望摆脱BIM政策中的误区,获得更好的发展。

面向CIMS的集成多方位建模与仿真框架

首先分析了几种常用建模方法，包括ＩＤＥＦ０、ＩＤＥＦ１、动态建模方法及ＯＭＴ方法。然后提出了一个集成多方位建模与仿真框架（ＩＭＭＳ），它将功能、信息、动态视图及仿真核心集成在一起，实现了仿真模型的自动生成，它使得在系统功能设计早期就能预见、评价未来系统的有关动态品质。

ulti-azimuth three-component surface seismic modeling for viscoelastic cracked monoclinic media

In this article, a method of high order, staggered grid, finite difference was used to model snapshots of seismic wave propagation and multi-azimuth surface seismic records in viscoelastic cracked monoclinic media. The modeling results clearly show the anisotropy caused by the crack fill material and the viscoelastic wave field through the monoclinic media. Summarizing the regularity of seismic records for different azimuths, this study is a significant attempt to understand the wave fields propagated in real media and to propose a more rational theoretical model for the future.

A New Rational-based Optimal Design Strategy of Ship Structure Based on Multi-level Analysis and Super-element Modeling Method

A new multi-level analysis method of introducing the super-element modeling method, derived from the multi-level analysis method first proposed by O. F. Hughes, has been proposed in this paper to solve the problem of high time cost in adopting a rational-based optimal design method for ship structural design. Furthermore,the method was verified by its effective application in optimization of the mid-ship section of a container ship. A full 3-D FEM model of a ship,suffering static and quasi-static loads, was used as the analyzing object for evaluating the structural performance of the mid-ship module, including static strength and buckling performance. Research results reveal that this new method could substantially reduce the computational cost of the rational-based optimization problem without decreasing its accuracy, which increases the feasibility and economic efficiency of using a rational-based optimal design method in ship structural design.

Modeling and monitoring of nonlinear multi-mode processes based on similarity measure-KPCA

A new modeling and monitoring approach for multi-mode processes is proposed.The method of similarity measure(SM) and kernel principal component analysis(KPCA) are integrated to construct SM-KPCA monitoring scheme,where SM method serves as the separation of common subspace and specific subspace.Compared with the traditional methods,the main contributions of this work are:1) SM consisted of two measures of distance and angle to accommodate process characters.The different monitoring effect involves putting on the different weight,which would simplify the monitoring model structure and enhance its reliability and robustness.2) The proposed method can be used to find faults by the common space and judge which mode the fault belongs to by the specific subspace.Results of algorithm analysis and fault detection experiments indicate the validity and practicability of the presented method.

Modeling, identification and compensation for geometric errors of laser annealing table

In order to improve the process precision of an XY laser annealing table, a geometric error modeling, and an identification and compensation method were proposed. Based on multi-body system theory, a geometric error model for the laser annealing table was established. It supports the identification of 7 geometric errors affecting the annealing accuracy. An original identification method was presented to recognize these geometric errors. Positioning errors of 5 lines in the workspace were measured by a laser interferometer, and the 7 geometric errors were identified by the proposed algorithm. Finally, a software-based error compensation method was adopted, and a compensation mechanism was developed in a postprocessor based on LabVIEW. The identified geometric errors can be compensated by converting ideal NC codes to actual NC codes. A validation experiment has been conducted on the laser annealing table, and the results indicate that positioning errors of two validation lines decreased from ±37 μm and ±33 μm to ±5 μm and ±4.5 μm, respectively. The geometric error modeling, identification and compensation method presented in this work can be straightforwardly extended to any configurations of 2-dimensional worktable.

A modeling method for virtual scene based on multi-view image sequence

Through the analysis and comparison of shortcomings and advantages of existing technologies on object modeling in 3D applications,we propose a new modeling method for virtual scene based on multi-view image sequence to model irregular objects efficiently in 3D application.In 3D scene,this method can get better visual effect by tracking the viewer's real-time perspective position and projecting the photos from different perspectives dynamically.The philosophy of design,the steps of development and some other relevant topics are discussed in details,and the validity of the algorithm is analyzed.The results demonstrate that this method represents more superiority on simulating irregular objects by applying it to the modeling of virtual museum.

Combined back-analysis method of ground stress based on refined geological modeling

A new back-analysis method of ground stress is proposed with comprehensive consideration of influence of topography, geology and nonlinear physical mechanical properties of rock on ground stress. This method based on non-uniform rational B-spline (NURBS) technology provides the means to build a refined three-dimensional finite element model with more accurate meshing under complex terrain and geological conditions. Meanwhile, this method is a back-analysis of ground stress with combination of multivariable linear regression model and neural network (ANN) model. Firstly, the regression model is used to fit approximately boundary loads. Regarding the regressed loads as mean value, some sets of boundary loads with the same interval are constructed according to the principle of orthogonal design, to calculate the corresponding ground stress at the observation positions using finite element method. The results (boundary loads and the corresponding ground stress) are added to the samples for ANN training. And on this basis, an ANN model is established to implement higher precise back-analysis of initial ground stress. A practical application case shows that the relative error between the inversed ground stress and observed value is mostly less than 10 %, which can meet the need of engineering design and construction requirements.

A multiscale modeling approach to adhesive contact

In order to model the adhesive contact across different length scales, a multiscale approach is developed and used to study the adhesive contact behaviors between a rigid cylinder and an elastic face-centered cubic (FCC) substrate. The approach combines an atomistic treatment of the interfacial region with an elastic mechanics method description of the continuum region. The two regions are connected by a coupling region where nodes of the continuum region are refined to atoms of the atomistic region. Moreover, the elastic constants of FCC crystals are obtained directly from the Lennard-Jones potential to describe the elastic response characteristics of the continuum region, which ensures the consistency of material proprieties between atomistic and con- tinuum regions. The multiscale approach is examined by comparing it with the pure MD simulation, and the results indicate that the multiscale modeling approach agrees well with the MD method in studying the adhesive contact behaviors.