挤了模流道的优化设计

结合塑料熔体流变理论和实践经验，提出了塑料异型材挤出模流道优化设计的思想和方法，通过计算机对流道系统进行设计，使流体在流道中流动分布均匀，流道设计合理，缩短设计时间。     

挤出模流道的优化设计

结合塑料熔体流变理论和实践经验，提出了塑料异型材挤出模流道优化设计的思想和方法．通过计算机对流道系统进行优化设计，使流体在流道中流动分布均匀．流道设计合理，缩短设计时间．     

硬质聚氯乙烯异型材挤出模具的设计

主要介绍硬质聚氯乙烯塑料中空异型材挤出模具的设计,通过一典型实例,讨论了异型材挤出模具的设计理论、计算方法、设计程序与设计要点。     

异型材挤出模头压力降的数值计算

介绍了一种基于横截面法的异型材挤出成型中熔体在模头内流动压力降的数值计算方法，可用于预测截面复杂的异型材挤出模头压力降，通过一个例子说明了数值计算结果的可靠性和用途。     

CAD技术在塑料型材挤出模的成功应用

1 研制背景 塑料型材挤出模的设计,由于模塑料流动的非牛顿特性和异型材截面的复杂性,综合考虑的因素多,计算繁杂,设计周期长,易出差错;而过多依靠经验数据,已无法适应多变的市场需求和不断提高的技术要求(如模塑料配方的改进,牵引速率的提高,异型材功能和精度要求的增加     

塑料异型材挤出成型模具CAD系统

塑料挤出成型是一种非常重要的塑料成型工艺。在各种塑料成型工艺中,塑料挤出成型制品的产量最多,约占世界塑料制品总产量的40%。在我国,塑料挤出成型却是塑料加工工业中较薄弱的一个门类。然而,自80年代起,为加速发展我国的塑料门窗工业,我国先后进口了200多条先进的高效双螺杆塑料异型材挤出成型机组,使我国塑料挤出机的水平上了一个新台阶。但是,与这些机组相适应的塑料异型材挤出成型模具在国际市场上价格昂贵(3～4万美元/套),且国内一时尚不能配套,这便限制了塑料异型材挤出成型机组的应用。     

一种橡胶异型材机头的设计

橡胶异型材机头的设计等技术问题，是橡胶挤出中难以解决的问题，主要是挤出平衡问题，文中通过对一种橡胶异型材机头的设计及试验，对异型材机头的设计提出一些看法。     

异型材模头中内流道成型区长度设计

异型材模头中内流道成型区长度设计一直是以经验设计为主,或通过简易公式的计算来确定内流道成型区的长度,这在一定程度上影响异型材模具的性能.文章依据聚合物流变学理论导出塑料异型材模头中内流道成型区长度公式,并结合简易公式分析了各类参数对内流道成型区长度的影响程度,指出了简易公式的适用范围.     

塑料动态挤出填充过程的数值模拟研究

利用ANSYS软件对受入口处周期性振动压力驱动的塑料熔体在"L"形异型材挤出口模内的填充过程进行了三维等温数值模拟。研究了流场压力和速度随入口压力振动的变化规律,分析了压力振动对塑料熔体流动稳定性的影响。结果表明:流场压力和速度都随入口压力的振动而振动,但振动强度随流程增加而减弱,只要选择适当的振动参数和口模长度,就可以使出口流场稳定,以保证塑料制件的质量。     

塑料异型材真空定型模冷却水道优化设计

热的塑料异型材通过定型模来冷却定型,因此定型模内冷却水道的设计是保证型材成型质量的重要基础.通过分析型材冷却过程中的热传递方式,对传热模型、初始条件和边界条件进行了深入的分析和计算,完成了塑料异型材在定型模内冷却过程的数值模拟.在此基础之上,以定型模出口处型材截面上各点冷却均匀性和效率为优化目标,基于有限元分析结果和水道参数化模型建立目标函数的数学模型,对水道的位置参数进行优化设计.通过生产型材SF66的定型模的优化设计和实验,验证了该方法的正确性和有效性.     

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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