虚拟环境中多细节层次模型自动生成算法

虚拟环境是限时计算和限时图形绘制技术的典型应用．本文对用于限时图形绘制的多细节层次模型表示进行研究，提出了基于三角形网格简化的多细节层次模型自动生成算法．该算法多次遍历现有三角形网格模型的每一个顶点，使用局部几何和拓扑特征移去满足简化标准的顶点，对移去顶点后产生的多边形区域进行局部三角化．多次执行上述过程，结果形成不同细节层次的三角形网格模型．文中给出的实例说明了该算法的有效性．     

基于顶点在的多面体模型简化方法

本文介绍一种基于顶点聚类的多面体模型简化方法，该方法主要由三部分组成：（１）把多面体模型划分若干个小单元；（２）落在同一单元中的一组网格顶点用一个代表顶点表示；（３）由代表顶点进消运操作得到简化的三角形网格模型，该方法实现简单、速度快，并且具有通用性。     

Windows NT词汇选登(续)

DefaultNetworkandDesired默认的网络及目的区域Zonedefaultprofile默认配置文件DeferredProcedureCall（DPC）延时过程调用（DPC）Deinstall卸下DelayBetweenLines:行间延迟：Delaybetweenwarningmessages：警告消息间隔时间：delayspeed速度延迟delayedbinding延迟绑定delayedrendering延迟响应DeleteCllnetAce。。。l。Ic，n。，。删除客户访问授权DeleteJobsAfterPrln；lug打印之后删除作业DeleteMapping删除映象Delete（）wuer删除所有者DeletePo，t删除端口DeleteRemotehatWork。ta；l。us删除远程启动的工作站Deleting…     

VB编程技巧三则

一、从List Box中移去Items 时易犯的错误 VB的List Box控件允许你在程序运行时增加或移去Items。当你给List Box控件List1增加一新的item时,使用additem方法,如下: List1.Addltem“Item 1”这个新的item被加在List1的最后一项,ListCount属性值被自动加1,这是由AddItem方法引发的。当你从List1中删除一项时,使用RemoveItem方法。下面的语句将从List1中删除掉“Item 1”:     

NDSAIL系统的归纳结构正确性准则及其自动确认方法

归纳结论正确性的自动确认是归纳学习用于软件自动化必须解决的首要问题。本文针对自学习软件自动化系统ＮＤＳＡＩＬ的需要，提出了保证归纳结论正确性的一致性准则和可满足性准则以及用多层次的演绎推理加以自动确认的方法。其主要特点是：（１）面向应用的归纳结论正确性准则；（２）验证功能与修正功能相结合的确认方法；（３）基于自动演绎机制的自动实现。     

采用删除低密度校验码的比特交织编码调制技术研究

本文从系统的角度提出了采用删除低密度校验码（LDPC）作为成员码的比特交织编码调制（BICM）系统方案，其中删除模式分别采用通过优化算法确定LDPC码的优化删除分布和随机删除两种方案。仿真结采表明，该系统方案的性能与系统BICM容量之间的距离小于1dB，从而清楚地说明了该系统能够很好地适应信道的变化，在不同的信遁裘件下均保持了良好的性能。     

基于重新划分的三角形网格简化的一种改进算法

基于重新划分的三角形网格简化方法能自动生成多细节层次模型，它的基本思想是:根据三角形网格的局部几何和拓扑特征将一定数量的点分布到原网格上,生成一个中间网格,移去中间网格中的老顶点,并对产生的多边形区域进行局部三角化,最后形成以新点为顶点的三角形网格.本文在已有算法的基础上,提出了一种分布新点的算法,从而克服了原有方法的局限性.它利用三角形顶点的曲率和三角形的面积两个因素来反映网格在每个三角形处的特征.文中给出的一组实例说明了算法的有效性.     

基于主应力删除准则的ESO法及其应用

为促进渐进结构优化（Evolutionary Structure Optimization,ESO）法在桥梁找型方面的应用,阐述基于主应力删除准则ESO法的基本原理,研究不同M值对优化结果的影响,并建议在应用该法进行拓扑优化时取M≥10.应用基于拉应力占优删除准则的ESO法分析高跨比对缆索支承桥形式的影响,结果表明：当高跨比大于等于1/7时缆索支承桥的最优形式为斜拉桥;当高跨比低于1/7时最优形式为悬索桥.     

如何在WIN95的开始菜单上删除或增加应用程序图标?

笔者在使用WIN95的过程中，安装了一些程序，后来由于硬盘空间紧张，需要删除它。但许多程序的SETUP程序没有卸载这一功能，以致删除该程序后，其图标依然在开始（Start）的菜单上残留，无法删除。后来通过较长时间的实践摸索，最终找到了在Start（开始）菜单上删除应用程序图标的方法。那么，如何才能删除开始菜单上的该程序图标呢？步骤如下：用左键点击Start（开始）菜单，将鼠标箭头移到Settings（设置）上，再向右平移到分菜单上，其中有ChntrolPanelPrinterSTaskbar三个子项，用左键点击Taskbar任务条），立即就弹出“Taskbar…     

三角形交通标志的智能检测方法

基于交通标志都具有一定的颜色和形状，以红色倒三角形交通标志为例，介绍一种新的智能检测方法。该方法主要由以下4个环节构成。首先是颜色提取，将图像转换到HSI颜色模型的色调子空间，提取特定颜色——红色；其次是边缘检测，使用标准LOG模板在提取出来的红色区域上进行；这样，计算量将大为减少；然后是顶点判别，对边缘上的这些点，采用神经网络分类器进行分类，并分别对三角形的3种不同顶点作标记；最后是三角形的定位，通过一定的匹配准则提取出三角形。对不同场景下的20幅图像进行测试，检测正确率达到了100％。实验结果表明，该方法具有鲁棒性好、速度快、检测准确率高等特点。     

Triangle Influence Supersets for Fast Distance Computation

We present an acceleration structure to efficiently query the Signed Distance Field (SDF) of volumes represented by triangle meshes. The method is based on a discretization of space. In each node, we store the triangles defining the SDF behaviour in that region. Consequently, we reduce the cost of the nearest triangle search, prioritizing query performance, while avoiding approximations of the field. We propose a method to conservatively compute the set of triangles influencing each node. Given a node, each triangle defines a region of space such that all points inside it are closer to a point in the node than the triangle is. This property is used to build the SDF acceleration structure. We do not need to explicitly compute these regions, which is crucial to the performance of our approach. We prove the correctness of the proposed method and compare it to similar approaches, confirming that our method produces faster query times than other exact methods.     

Spectral methods on triangles and other domains

This article shows how to obtain multidimensional spectral methods as a warped product of one-dimensional spectral methods, thus generalizing direct (tensor) products. This generalization includes the fast Fourier transform. Applications are given for spectral approximation on a disk and on a triangle. The use of the disk spectral method for simulating the Navier-Stokes equations in a periodic pipe is detailed. The use of the triangle method in a spectral element scheme is discussed. The degree of approximation of the triangle method is computed in a new way, which favorably compares with the classical approximation estimates.     

The pseudo-linear semantics of interval-valued fuzzy logics

Triangle algebras are equationally defined structures that are equivalent with certain residuated lattices on a set of intervals, which are called interval-valued residuated lattices (IVRLs). Triangle algebras have been used to construct triangle logic (TL), a formal fuzzy logic that is sound and complete w.r.t. the class of IVRLs.In this paper, we prove that the so-called pseudo-prelinear triangle algebras are subdirect products of pseudo-linear triangle algebras. This can be compared with MTL-algebras (prelinear residuated lattices) being subdirect products of linear residuated lattices.As a consequence, we are able to prove the pseudo-chain completeness of pseudo-linear triangle logic (PTL), an axiomatic extension of TL introduced in this paper. This kind of completeness is the analogue of the chain completeness of monoidal T-norm based logic (MTL).This result also provides a better insight in the structure of triangle algebras; it enables us, amongst others, to prove properties of pseudo-prelinear triangle algebras more easily. It is known that there is a one-to-one correspondence between triangle algebras and couples (L,α), in which L is a residuated lattice and α an element in that residuated lattice. We give a schematic overview of some properties of pseudo-prelinear triangle algebras (and a number of others that can be imposed on a triangle algebra), and the according necessary and sufficient conditions on L and α.     

An application of the Ts-VI triangle method with enhanced edges determination for evapotranspiration estimation from MODIS data in arid and semi-arid regions: Implementation and validation

The commonly applied surface temperature-vegetation index (T_s-VI) triangle method is used to estimate regional evapotranspiration (ET) in arid and semi-arid regions. A practical algorithm based on the T_s-VI triangle method is developed to determine quantitatively the dry and wet edges of this triangle space. First, the T_s-VI triangle method is reviewed. Assumptions involved in this method are highlighted, and advantages, disadvantages and applicability are discussed. Then, an experimental use of the T_s-VI triangle method is developed and applied to several MODIS/TERRA datasets acquired during the Heihe Field Experiment from May 20th to August 21st, 2008. The sensible heat fluxes retrieved using MODIS data from a grassland located in the middle reach of Heihe river basin, Northwest China, are in good agreement with those measured from a Large Aperture Scintillometer (LAS). The Root Mean Square Error of this comparison is 25.07 W/m². It is shown that determination of dry and wet edges using the proposed algorithm is accurate enough at least in most cases of our study for the estimates of regional surface ET.     

一种新的基于二次误差的三角形网格简化方法

介绍一种新的基于二次误差的三角形网格简化方法,该方法由三部分组成：（1）特征边判定;（2）根据特征边进行顶点分类;（3）根据顶点类型及二次误差度量进行半边收缩,得到简化网格。该方法实现简单、速度快,文中给出了一些实例说明了本方法的有效性。     

一种基于不平滑度的网格简化算法

在三维建模中,一个物体的网格模型常常包含数以百万计的三角形面片,给模型的存储、绘制、渲染、传输及交互处理带来诸多不便。提出一种三角形折叠法,计算各个顶点的不平滑度,基于顶点不平滑度确定各三角形的权值,并对符合折叠要求的三角形求解折叠后新顶点的位置及累积不平滑度,通过实例验证证明该算法在简化网格时能较好地保持模型整体特征。     

Robust multi‐level partition of unity implicits from triangular meshes

This paper presents a new robust multi‐level partition of unity (MPU) method, which constructs an implicit surface from a triangular mesh via the new error metric between the mesh and the implicit surface. The new error metric employs a weighted function of inner points and vertices of a triangle to fit an implicit surface, which can control the approximation error between the surface and vertices of the triangle. Furthermore, it is applied to the MPU method by utilizing the dual graph of a triangular mesh, and the general quadric implicit surface is used for surface representation. Compared with the MPU method, the new method generates fewer subdivision cells with the same approximation error and performs more steadily especially when given triangular mesh with fewer vertices. Copyright © 2013 John Wiley & Sons, Ltd.     

On the evaluation of the eigenvalues of the finite differences laplacian over a hexagon

Fast numerical methods for the evaluation of the eigenvalues of the finite-differences laplacian over a regular hexagon are devised. At first we show how this eigenvalue problem can be splitted into 3 eigenvalue problems, of lower dimension (reduced by a factor of 1/6), for the discrete laplacian over a regular triangle with suitable boundary conditions. Then, expressing explicitely the eigenvalues and the eigenvectors of the discrete laplacian over a triangle in terms of the coefficients of the discrete Fourier transform, we show how to deal efficiently with each subproblem. In particular we show that each step of the shifted inverse power method, for the approximation of the eigenvalues, costs O(n²log n) arithmetic operations in a sequential model of computation, and O(log n) steps with n² processors in a parallel model of computation, where n is the number of the nodes on the edge of the hexagon. Similar estimates hold for the orthogonal iterations (subspaces iterations) method and for Lanczos method. This approach includes the deflation of the eigenvalues of the triangle from those of the hexagon. These results improve the methods given by Bauer and Reiss [1] allowing a higher precision in the approximation of the eigenvalues of the laplacian and reducing the computational cost, either in a sequential or in a parallel model of computation.