基于CATIA V5的虚拟投影体系的研究

介绍了在CATIA V5中创建物体三视图的虚拟投影体系模型图的方法.首先建立物体的实体模型,捕捉必要的视图图像,然后在实时渲染模块中利用盒形场景编辑器模拟投影体系,再将捕捉的视图图像作为背景贴图映射到虚拟投影面上,虚拟物体的正投影,实现了在CATIA数字环境下虚拟物体三面正投影视图的生成过程.该模型可以直观地展示获得物体多面正投影的过程,是利用CATIA V5模拟物体投影的有益尝试.     

基于CATIA V5的虚拟投影体系的研究

介绍了在CATIA V5中创建物体三视图的虚拟投影体系模型图的方法.首先建立物体的实体模型,捕捉必要的视图图像,然后在实时渲染模块中利用盒形场景编辑器模拟投影体系,再将捕捉的视图图像作为背景贴图映射到虚拟投影面上,虚拟物体的正投影,实现了在CATIA数字环境下虚拟物体三面正投影视图的生成过程.该模型可以直观地展示获得物体多面正投影的过程,是利用CATIA V5模拟物体投影的有益尝试.     

投影与视图

投影与视图是形成机器制造图样的核心问题。本文对投影与视图的地位,相互关系以及异同点,从多方面进行了分析对比,为正确认识、深入理解和恰当运用投影与视图这两个重要的术语及其概念提出了一系列具体的区分内容。     

视图特征的曲面重建方法研究

提出了一种基于视图特征的三维形体重建方法,根据分离视图的投影特征定义曲面特征,通过匹配二维视图特征识别曲面类型及参数,从而构造曲面线框图生成B-rep结构形体模型.利用曲面求交法求解三维二次曲面交线及高次曲线,解决了五点法及共轭直径法在求解二次曲线时采样复杂且耗时的问题以及无法通过视图投影获取高次曲线的问题.实验结果和算法分析表明,通过特征获得曲面类型再求交获得高次曲线的这一过程,是恢复二次或高次曲线的行之有效的方法,而且计算效率也有较大提高.     

高校工科学生机械制图教学中的一些变革

讨论了传统机械制图教育的缺陷,只注重画法的技巧和节省时间和空间,已经不适应现在的计算机绘图的发展要求。计算机绘图是基于三维模型的建立,可以方便地形成各种投影视图和剖视图,因此对制图的要求提出相应的变化,可以多生成完整视图,多生成剖视图,可以生成轴测图。传统的教学方法应该加以修改,对机械制图的国家标准也做相应修改,把轴测图的要求写如国家标准中。     

利用视觉事件求解多面体线框模型主视图方向

文中提出了正投影下多面体产生的4种简单视觉事件的定义,并分析了各视觉事件的计算复杂程度,为空间任意位置的多面体线框模型找到了一种求解最佳主视图投影方向的方法。该方法利用视觉事件求解投影方向,向各投影方向投影生成视图,再利用点点型和线线型视觉事件的权重值选出最佳的主视图投影方向。通过在matlab中编程运行表明,该方法计算简单,准确率高,易于实现,选出的主视图投影方向符合人们的制图习惯。     

水平体视图图幅分析及计算作图法

通过分析体视视野在水平画面上的视野椭圆半轴a、b与视距Sz及主视线偏角θ之间的关系，研究水平体视图最大图幅。同时，依据体视投影原理，推导出水平体视图图形位似系数Kγ及右体视投影坐标(xal，yal)与左体视投影坐标(xar，yar)，并编写出水平体视图计算作图法框图，为计算机绘制水平体视图提供了计算方法。     

制作三面投影形体体视图的一种新方法

本文提出一种利用三面投影的体视图确定形体体视图的方法。方法的要点是先在画面上作出水平投影,然后作出另外二个投影的体视图。由于方法中规定使 X 轴与水平方向成30°,使 Y 轴与水平方向成60°,在确定点的空间位置时,采用视线双投射法直接按比例求解,所以可大大加快作图速度。整个作图过程,真实地再现了能用三面投影确定空间形体形状的原理。文章最后提出了如何确定各体视图间互不遮挡的极限位置及三种检查图形错误的方法。     

带三面投影的形体体视图的画法

讨论了带三面投影的形体体视图的画法、体视图间互不遮挡的位置及图形的着色和观看方法。     

工程图投影域逻辑关联关系模型研究

以投影视图模型理论为基础,通过对矢量工程图图元信息的智能化处理,依据各投影视图蕴涵的内在关联机理及工程图表达产品设计信息的规律,提出了投影域的概念并对其进行技术获取。根据工程图的投影规律和表达规则,研究了投影域间的逻辑关联关系。以投影域之间的逻辑关联关系为基础,给出了逻辑关系的判别算子,并研究了投影域逻辑关系获取算法。通过对投影域关联关系的获取,以投影域逻辑关联关系模型为基础,达到对工程图的检索评价。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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