多维空间形体的计算机图示

本文在研究多维空间结构的基础上,用矩阵方法表达多维画法几何中正投影及其投影变换过程,将多维几何理论与计算机绘图结合起来,从而使计算机绘制多维空间形体的多面正投影图、轴测投影图和透视投影图成为可能。     

轴测图扁圆画法的研究及对剖视方法的意见

一、前言轴测投影图因富有立体感,明显易懂,故在工程制图中应用极广,例如机器装配说明,仪器构造图,教科书用插图等等,都广泛地采用轴测图。结合我们教学来说,根据高教部“机械制图统一教学大纲”的规定;要完成相当数量的轴测投影图、轴测草图及完成轴测部件图,并指出轴测投影图的练习须在全部课程中进行。可见轴测投影图在机械制图中占有极大的位置。     

基于透视投影的垂直视角投影算法研究

在计算机视觉领域,透视投影变换是图像变换中最复杂的变换之一.在透视投影中的垂直投影是在实际工程应用中使用最广泛的变换方法.研究了透视变换中斜投影与正投影之间的变换关系,分析了不同角度的斜投影图像到正投影图像之间变换对参数的影响,得出了变化参数与斜投影的倾角关系.实验表明,按照所得到的参数与倾角关系矩阵,可以准确地计算出斜投影图像对应的正投影图像.     

正三测轴测投影图尺设计的探讨

轴测投影图具有较好的直观性和度量性。本文以轴测投影理论为依据,提出正三测轴测图尺的设计方案,使手工难以绘制的正三测图变得简便又准确了,并由此引出用一种正三测轴测图尺就能绘制出24种不同表达方法的正三测轴测图。     

三维图形变换的统一矩阵

对轴测投影和透视投影变换矩阵进行了研究,推出了三维图形变换的统一矩阵。     

基于工程三视图的正等轴测图生成技术

详细论述了由工程三视图生成正等轴测图的关键技术,得出了有关的矩阵变换公式,并利用ＡｕｔｏＣＡＤ的内嵌ＶＢＡ语言编制了相应的应用程序,算法简单可靠。     

透视投影变换总矩阵的研究

通过建立透视变换总矩阵，代入各类透视投影及正轴测投影的几何条件，推导出这些三维图形的变换矩阵。在讨论透视图与轴测图之间联系的同时，提出了中心投影与平行投影的变换矩阵能够统一的观点。     

电子计算机绘制轴测图和透视图

本文着重介绍如何运用矩阵变换的数学方法将图形转化为数字信息,使电子计算机能操纵绘图机进行工作,画出不同视向的各轴测图或透视图,在设计中供审视和修改用。文中附有绘制绕竖轴旋转的物体轴测图和房屋透视图的程序设计实例和图象等。     

由三维实体模型生成二维投影图的方法

文中介绍使用AutoCAD的提取三视图功能可以直接由实体模型生成二维投影图和轴测图的方法,利用这种方法可以方便地将三维图形转变为平面图形,符合产品的设计思路,且大大提高产品设计的效率。     

辅助球面法在画法几何学中的应用

本文探讨了用球面作为辅助面，解决回转体的正投影图及轴测投影图的作图问题。     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

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