景物空间的镜面反射(折射)现象绘制方法

为了提高视点相关的镜面反射(折射)现象的绘制速度和绘制质量,提出了计算任意曲面反射(折射)光学映射虚物体的方法。该方法根据实际物体在反射/折射体中所成的像创建虚物体,利用图形加速硬件像处理实际三维物体一样绘制这些虚物体,将得到的关于虚物体的图像与实际反射/折射体的图像相混合,就可以得到有反射/折射效果的最终图像。实验结果表明:该方法可以克服光线跟踪方法当空间点采样不足时所带来的走样问题。该方法利用图形硬件加速,提高了绘制的速度。     

基于光线跟踪的一般辐射度方法研究

通过对目前主要采用的两种真实感图形绘制技术—光线跟踪技术和辐射度方法的研究；在将光线跟踪技术和辐射度方法相结合，更有效地模拟光能在物体表面间的镜面反射、透射和漫反射光照效应方面，本文做了较深入的讨论；对非理想漫射的一般环境，给出了基于光线跟踪的一般辐射度方法及其逐步求精选代的算法。     

基于图形硬件加速的并行绘制

并行方法是绘制大规模复杂场景的真实感图形的有效手段之一。特别是随着图形加速硬件的普及和性能提高,基于图形硬件加速的并行绘制成为当前的研究热点之一。本文介绍了目前主要的基于图形硬件的并行绘制技术,并对这些方法的特性分别进行了论述。最后,指出了这类方法的优点以及存在的问题和解决方案。     

现实反馈的仿真算法研究

指出虚拟现实和仿真的方法已在多个工业领域中得到应用,但目前仿真应用都有一个特点:缺少现实反馈信息指导仿真场景的绘制,控制信息只能单向传输.而在很多领域的应用中,仿真场景需要"忠于"现实场景,从而需要一个信息从现实反馈的方法.现实反馈的关键问题就是如何使仿真场景中物体始终与现实中的对应物体一致,包括形状一致和位置一致.针对此问题,提出一种方法,即通过精确建模保证形状一致,通过合适的模型变换保证位置一致.模型变换矩阵的计算方法是:定义和测量物体上的3个控制点,根据三点的模型坐标和世界坐标计算.利用这种算法构建实时仿真场景的数据要求是:预先建造好的零部件模型;每个刚性部件需测量反馈3个控制点的坐标.这种算法可作为仿真监控系统的数学基础.     

图形硬件加速的实时阴影生成方法

针对虚拟环境中阴影计算时间耗费较大的问题,提出了利用图形硬件特性加速阴影绘制的方法.算法基于图像空间,采用三遍绘制方法.第3遍绘制用于计算物体的真实感光照,并对阴影边界的走样现象进行了处理.利用硬件的图形处理单元GPU的处理能力和OpenGL特性扩展,在GPU编程和通用OpenGL实现两个层次上进行了实验,实验结果表明,三遍绘制方法产生的光照和阴影效果更真实,得到的阴影边界更平滑.     

基于IFS分形树的模拟

分形理论是利用分数维数的数学方法来描述和研究客观事物。利用分形可以模拟出逼真的自然景物,解决了计算机对复杂自然景物建模困难的问题。IFS迭代函数系统模型是产生分形图形的重要方法之一。根据IFS模型构建分形图形的方法和原理,通过观察树木等自然景物的特征,抽象出一种自然界树木的形状,利用拼贴的方法计算出该树木的IFS码,并用VC++作为工具实现对树木的绘制。通过树木绘制实例详细介绍了绘制的过程、颜色问题的改善和迭代次数及伴随概率对图形的显示效果的影响。由于迭代函数系统模型是通过绘制迭代点来生成图形的,对于点的颜色设置要么单一要么比较杂乱,因此对绘制过程中如何设置迭代点的颜色提出了改善办法。根据程序最终的显示效果,生成图形符合预期的形状,经过颜色改善后的图形效果更加逼真。     

基于非真实感绘制技术的实时阴影渲染

在基于非真实感绘制的实时场景渲染过程中,为了达到更逼真的效果,三维物体在光照作用下产生的阴影需要被实时绘制并能够体现设计者的风格。本文利用现代可编程图形显示硬件技术,提出了一种基于阴影线算法的阴影绘制方法,与采用传统的阴影图方法绘制阴影的效果相比较,该方法具有更好的艺术效果。     

基于混合式绘制技术的分布式虚拟环境系统

给出了一个基于分布式计算技术的虚拟环境原型系统.系统根据当前摄像机的运动趋势,首先利用预测技术实时地确定下帧图象摄像机的方位,然后分布式地采用基于几何的快速绘制算法来生成预测图象,最后采用图象warping算法来实时生成前后预测图象间的画面过渡.由于引入了几何信息,因而本系统允许用户对虚拟景物进行直接交互操作,从而克服了传统基于图象的图形绘制技术只能处理静态场景的缺陷.实验结果表明,本系统对场景复杂性的依赖程度低,能在中等计算能力的工作站上实现复杂场景的实时交互.     

基于GPU粒子系统的烟花实时仿真

烟花的仿真对于烟花燃放编排、动画游戏、影视特效等有着非常重要的应用.基于粒子系统可以进行烟花的模拟,但粒子数较多时常常绘制速度较慢.引进最新发展的图形硬件加速绘制技术,提出了一种基于GPU(GraphicProcess Unit)粒子系统的烟花绘制技术,并构架实现了一个实时的烟花仿真系统,实现了不同烟花燃放场景的真实感仿真.     

点绘制技术在图形绘制中的应用

在基于点的图形绘制技术中，作为绘制基本元素的是点．点绘制是传统的基于三角网格绘制的重要补充．文章介绍了基于点绘制技术的原理和比较有代表性的点绘制方法，探讨了外形非常复杂的不规则几何体在计算机图形绘制中生成的物体表面空洞的处理方法．     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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