构模法解初中数学中的难题

初中数学难题，也是教学中的难点。实践证明，构模法是解决初中数学难题的最好办法。构模法就是根据题里的一个概念、一个名词、一条线、一个图形、一个问题等马上联想到学过的概念、定理、公式、例题、习题、涉及知识、条件、联的线、用什么方法解的，从而确定这道难题解题的方向、思路、辅助线的联法，进一步找到解难题的方法。通过构模法训练学生联想能力，培养学生的直觉思维，使学生能迅速找到解难题思路，从而具有解难题的分析综合能力。

构模法解初中数学中的难题

随着新课程改革进程的加快,新的人才观给学校教育提出了更高的要求,初中数学教学面临着一些新的挑战.在初中数学教学中,构模法是重要的解题方法之一,是构建初中数学体系的重要组成部分,是解答数学难题的基础和必备条件.笔者结合多年的教学经验,构模法在解答初中数学难题中的应用进行了研究,剖析其设计思路及其在教学活动中的应用,供广大教育工作者参考.

矿体表面模型在计算机境界圈定方法中的应用

在以往的计算机方法境界圈定中都需建立矿块模型,逐个块段扫描导致运算速度慢,不能满足大数据量计算,该文针对以上问题在建模方面采用了矿体表面模型,该模型采用一种再现传统手绘的建模方法,通过一系列平面图或剖面图的矿体边界多边形进行线框建模技术来描述矿体空间分布即线框构模法。在读取平面图或剖面图中矿体边界多边形的工作中需要运用图形学、分形学等理论,实现了对矢量图形图元素的提取。完成矿岩多边形提取后便可以利用线框构模法进行矿体线框模型的建立,最后利用Open GL技术对线框模型进行填充,生成矿体表面模型。

Novel damage constitutive models and new quantitative identification method for stress thresholds of rocks under uniaxial compression

Four key stress thresholds exist in the compression process of rocks,i.e.,crack closure stress(σ_(cc)),crack initiation stress(σ_(ci)),crack damage stress(σ_(cd))and compressive strength(σ_(c)).The quantitative identifications of the first three stress thresholds are of great significance for characterizing the microcrack growth and damage evolution of rocks under compression.In this paper,a new method based on damage constitutive model is proposed to quantitatively measure the stress thresholds of rocks.Firstly,two different damage constitutive models were constructed based on acoustic emission(AE)counts and Weibull distribution function considering the compaction stages of the rock and the bearing capacity of the damage element.Then,the accumulative AE counts method(ACLM),AE count rate method(CRM)and constitutive model method(CMM)were introduced to determine the stress thresholds of rocks.Finally,the stress thresholds of 9 different rocks were identified by ACLM,CRM,and CMM.The results show that the theoretical stress−strain curves obtained from the two damage constitutive models are in good agreement with that of the experimental data,and the differences between the two damage constitutive models mainly come from the evolutionary differences of the damage variables.The results of the stress thresholds identified by the CMM are in good agreement with those identified by the AE methods,i.e.,ACLM and CRM.Therefore,the proposed CMM can be used to determine the stress thresholds of rocks.

地矿3维GIS模型的构建及可视化

本文在总结已有的构模方法的基础上 ,针对矿体的不规则性 ,提出采用线框构模法来构造三维 (3D)形体。文中利用OpenGL图形库实现地矿 3D模型的可视化技术 ,从而方便地生成高真实感的三维图形。

自然植被对气候变化响应的研究:建模

预测性植被制图（ＰＶＭ）是自然植被对气候变化响应建模的重要思想和方法，已为国外的许多生态学家、地理学家在开展全球变化的影响研究中所采用。本文在简述了ＰＶＭ发展过程的基础上，对其方法进行了归纳，并探讨了ＰＶＭ对气候－植被响应模型研究的作用。在文中作者特别强调地理信息系统（ＧＩＳ）在自然植被对气候变化响应建模中的重要性，并对ＧＩＳ支持下的构模方法和步骤进行了总结。

基于Minex的露天矿三维地质模型的建立及可视化研究

利用Minex.6.0软件以新疆后峡煤田黑山露天煤矿为例,构建了地质数据库,将钻孔数据和煤层信息数据成功地导入Minex数据库中,实现了钻孔数据的三维可视化。研究探讨了Minex.6.0软件的构模方法和理论,采用界面构模法,建立了地表模型和矿体三维模型统一形成了新疆后峡煤田黑山矿区矿床的空间三维模型系统并实现了可视化。

Modeling constitutive relationship of 6013 aluminum alloy during hot plane strain compression based on Kriging method

Hot plane strain compression tests of 6013 aluminum alloy were conducted within the temperature range of 613?773 K and the strain rate range of 0.001?10 s?1. Based on the corrected experimental data with temperature compensation, Kriging method is selected to model the constitutive relationship among flow stress, temperature, strain rate and strain. The predictability and reliability of the constructed Kriging model are evaluated by statistical measures, comparative analysis and leave-one-out cross-validation (LOO-CV). The accuracy of Kriging model is validated by the R-value of 0.999 and the AARE of 0.478%. Meanwhile, its superiority has been demonstrated while comparing with the improved Arrhenius-type model. Furthermore, the generalization capability of Kriging model is identified by LOO-CV with 25 times of testing. It is indicated that Kriging method is competent to develop accurate model for describing the hot deformation behavior and predicting the flow stress even beyond the experimental conditions in hot compression tests.

Research on Rice Panicle L-system Model Based on Substructure Algorithm

In order to decrease model complexity of rice panicle for its complicated morphological structure,an interactive L-system based on substructure algorithm was proposed to model rice panicle in this study.Through the analysis of panicle morphology,the geometrical structure models of panicle spikelet,axis and branch were constructed firstly.Based on that,an interactive panicle L-system model was developed by using substructure algorithm to optimize panicle geometrical models with the similar structure.Simulation results showed that the interactive L-system panicle model based on substructure algorithm could fast construct panicle morphological structure in reality.In addition,this method had the well reference value for other plants model research.

国防军费的评估问题

国防军费的评估问题张最良（军科院运筹所）０引言国防军费评估是国防、经济、外交乃至最高决策部门都十分重视的一项战略研究课题．但各个部门重视的角度或者说需要的目的不同，因而评估的要求也不同．一般说来，可能有以下几种不同的角度：１、对外政策研究目的对比各国...

Identification of constitutive model parameters for nickel aluminum bronze in machining

The material of nickel aluminum bronze (NAB) presents superior properties such as high strength, excellent wear resistance and stress corrosion resistance and is extensively used for marine propellers. In order to establish the constitutive relation of NAB under high strain rate condition, a new methodology was proposed to accurately identify the constitutive parameters of Johnson?Cook model in machining, combining SHPB tests, predictive cutting force model and orthogonal cutting experiment. Firstly, SHPB tests were carried out to obtain the true stress?strain curves at various temperatures and strain rates. Then, an objective function of the predictive and experimental flow stresses was set up, which put the identified parameters of SHPB tests as the initial value, and utilized the PSO algorithm to identify the constitutive parameters of NAB in machining. Finally, the identified parameters were verified to be sufficiently accurate by comparing the values of cutting forces calculated from the predictive model and FEM simulation.

Effect of cetyltrimethylammonium bromide on morphology and porous structure of mesoporous hydroxyapatite

The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.

AN UPDATING METHOD FOR LOCAL MODEL ERRORS

The location of model errors in a stiffness matrix by using test data has been investigated by the others.The present paper deals with the problem of updating stiffness elements in the erroneous areas. Firstly,a model that bears relation to erroneous elements only is derived.This model is termed local errors model,which reduces orders and computational loads compared with global stiffness matrix. Secondly,an inverse eigenvalue method is used to update model errors. The results of a numerical experiment demonstrate that the method is quite effective.

Simulation of texture evolution during plastic deformation of FCC,BCC and HCP structured crystals with crystal plasticity based finite element method

Two alternative formulations of single crystal plasticity model were introduced respectively and two schemes were implemented in the explicit FE code with software ABAQUS/Explicit by writing the user subroutine VUMAT.Meshes containing material data were created with solid elements.Each element represented an individual grain,and the grain orientations were explicitly stored and updated at each increment.Tangential modulus method was employed to calculate the plastic shear strain increment of deformation systems in combination with a hardening law to describe the hardening responses.Both two developed subroutines were applied to simulate the texture evolution during the uniaxial tension of copper（FCC）,cold rolling of IF steel（BCC） and uniaxial compression of AZ31 magnesium alloy（HCP）.The predicted texture distributions are in qualitative agreement with the experimental results.

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.

Maneuvering target tracking algorithm based on cubature Kalman filter with observation iterated update

Reasonable selection and optimization of a filter used in model estimation for a multiple model structure is the key to improve tracking accuracy of maneuvering target.Combining with the cubature Kalman filter with iterated observation update and the interacting multiple model method,a novel interacting multiple model algorithm based on the cubature Kalman filter with observation iterated update is proposed.Firstly,aiming to the structural features of cubature Kalman filter,the cubature Kalman filter with observation iterated update is constructed by the mechanism of iterated observation update.Secondly,the improved cubature Kalman filter is used as the model filter of interacting multiple model,and the stability and reliability of model identification and state estimation are effectively promoted by the optimization of model filtering step.In the simulations,compared with classic improved interacting multiple model algorithms,the theoretical analysis and experimental results show the feasibility and validity of the proposed algorithm.

Use of a submodel method to check the bolt strength of marine equipment

A submodel method was proposed that works from computational models of marine gear cases to verify that the proposed bolts will give it sufficient structural integrity. Calculations for marine equipment using this system accorded well with conventional results. As an example, an anti-shock computation was processed for a gear case, and the submodel was then employed to check the strength of individual components. The results showed that the gear case connecting structure can satisfy relative anti-shock requirements, and the dynamic response characteristics seen in the bolt structures had a close relationship with the method used for attaching the bolt. This provides a new means for checking the strength of connecting structures on large-scale equipment and thus has significant reference value.

Simulation and analysis of resin flow in injection machine screw

A method with simulation and analysis of the resin flow in a screw is presented to ease the control of some problems that may affect the efficiency and the quality of the product among existing screws in an injection machine. The physical model of a screw is established to represent the stress, the strain, the relationship between velocity and stress, and the temperature of the cells. In this paper, a working case is considered where the velocity and the temperature distributions at any section of the flow are obtained. The analysis of the computational results shows an ability to master various parameters depending on the specifications.