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1.
基于特征的产品建模研究   总被引:8,自引:0,他引:8  
提出了面向对象的特征及其关系的表达方法,建立特征类库;提出基于特征的产品定义模型,并开发出基于特征的CAD原型系统,初步实现了某厂回转类零件CAD/CAM集成。  相似文献   

2.
基于特征约束的CAD技术研究   总被引:1,自引:0,他引:1  
特征设计是当前解决CAD/CAM集成的重要方法之一。但目前特征的描述及特征建模的方法还不能解决CAD/CAM集成过程中提出的问题,这些问题包括特征库中特征类的简化、特征灵活性与变化性,设计特征映射成加工特征的困难等等。现提出一种特殊约束建模的方法,能较好地解决上述问题,并给出基于这种建模的CAD系统的结构。  相似文献   

3.
CAD与CAIP信息集成的研究   总被引:1,自引:0,他引:1  
首先介绍了基于特征技术的设计质量数据模型,然后建立了基于特征测面的零件检测数据模型,同时通过ODBC实现了基于特征技术的CAD与CAIP的信息集成。  相似文献   

4.
有关特征建模技术的研究   总被引:4,自引:0,他引:4  
开发基于特征建模的CAD系统是实现CAD/CAM一体化的根本方法,讨论了特征及其分类、特征空间及特征关系等关键技术,提出了基于特征的产品模型,并对其实现做了研究,最后建立了完整的特征模型。  相似文献   

5.
基于特征的回转体零件建模系统的研制   总被引:1,自引:0,他引:1  
本文在分析了基于几何的CAD系统的不足的基础上,提出了利用特征建模技术来建造计算机模型,并以所开发的FBRPMS系统为例,说明特征建模的原理和方法。该系统模块化设计,功能性强,易扩展,已成功地应用于CAD/CAPP/CAM集成领域  相似文献   

6.
面向并行工程的 CAD 系统   总被引:5,自引:0,他引:5  
针对并行工程的需求,提出了广义特征概念。基于Pro/EngineerCAD系统,借助于Pro/Develop开发工具二次开发了面向并行工程的CAD系统。特征造型后,该系统可对形状特征增加设计的后续过程所需的信息,便于实现CAD与后续过程的并行。基于广义特征和STEP标准,建立了集成产品信息模型。经特征识别和提取特征信息后,基于集成产品信息模型,可自动生成STEP中性文件,为实现了CAD与CAPP和DFM等后续过程的并行提供了丰富的信息。实际应用表明:该系统操作简单方便、设计效率高,为实现CAD与后续过程的并行打下了良好的基础。  相似文献   

7.
特征设计是当前解决CAD/CAM集成的重要方法之一.但目前特征的描述及特征建模的方法还不能解决CAD/CAM集成过程中提出的问题.这些问题包括特征库中特征类的简化、特征灵活性与变化性,设计特征映射成加工特征的困难等等.现提出一种特征约束建模的方法,能较好地解决上述问题,并给出基于这种建模的CAD系统的结构.  相似文献   

8.
着重讨论了集成与 并行环境下的 C A D/ C A P P/ C A M 模式构建问题。提出了特征刀具的概念。并就基于特征刀具的建模方法进行了充分的阐述  相似文献   

9.
机械零件的特征造型是实现零件的CAD/CAM一体化集成的基础。回转体类机械零件特征造型系统-HZTCAD,就是通过对回转体类零件进行特征分类,特征体素定义,特征体素的设计和特征体素的操作生成零件的几何模型和特征模型。提出一个基于特征表达的回转体类机械零件几何模型及数据结构,对回转体类零件的特征信息表达及表达的数据结构进行了尝试。  相似文献   

10.
本文介绍的机床主轴单元CAD系统是基于特征造型兼有静、动态分析的实用CAD系统,系统特征信息多,用户操作使用方便.  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
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.  相似文献   

14.
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.  相似文献   

15.
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。  相似文献   

16.
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.  相似文献   

17.
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-  相似文献   

18.
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-  相似文献   

19.
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  相似文献   

20.
<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  相似文献   

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