变截面型线涡旋压缩机的CFD流场分析

建立了变截面三段基圆渐开线和变截面高次曲线涡旋压缩机压缩腔二维物理模型,借助计算流体动力学(CFD)方法对压缩机工作过程进行瞬态数值模拟,得到压缩腔在曲轴转角为30°~150°时的速度场、压力场分布图.研究了两种变截面型线压缩腔流场分布特点及型线曲率对流场的影响,并与传统等截面型线进行了对比分析.结果表明:涡旋压缩腔流场分布受型线曲率的影响比较大,在同一主轴转角变化范围内变截面压缩腔速度变化趋于平缓,这也为涡旋压缩机的动平衡研究提供了依据.     

天气图上的涡旋动力学

天气图上有许多种涡旋型式。本文说明了天气图上的流场可以分解为旋转场和变形场：地转无摩擦的气旋、反气旋的涡旋型式是围绕中心点的闭合环流;考虑摩擦的气旋、反气旋的流型是围绕焦点的螺旋型式;鞍型场有4个涡旋中心点（2个气旋和2个反气旋）与1个鞍点;阻塞高压和切断低压由1个涡旋中心点与1个鞍点组成。从以上结果可以清楚地了解实际大气涡旋形态的动力和形成机制。     

天气图上的涡旋动力学

天气图上有许多种涡旋型式。本文说明了天气图上的流场可以分解为旋转场和变形场:地转无摩擦的气旋、反气旋的涡旋型式是围绕中心点的闭合环流流;考虑摩擦的气旋、反气旋的流型是围绕焦点的螺旋型式;鞍型场有4个涡旋中心点(2个气旋和2个反气旋)与1个鞍点;阻塞高压和切断低压由1个涡旋中心点与1个鞍点组成。从以上结果可以清楚地了解实际大气涡旋形态的动力和形成机制。     

基于Frenet标架的变截面涡旋型线构建与性能研究

在涡旋压缩机的型线设计中,针对传统等截面涡旋型线压缩比低、动静涡旋面积利用率不够充分等问题,提出一种新型的变截面涡旋型线.运用Frenet标架分段构建了由圆渐开线和三次曲线组合而成的涡旋型线并建立了该型线的基本几何理论.引入行程容积、压缩比、面积利用系数、轴向气体力以及切向气体力对涡旋型线的性能进行评价.结果表明,与传统的由单一圆渐开线构成的等截面涡旋型线相比,新构建的变截面涡旋型线的几何性能显著提高,而动力性能的变化幅度较小;行程容积、压缩比和面积利用系数分别提高了8.80%、10.57%和8.84%.     

坡莫合金纳米盘中交换偏置的涡旋动力学行为

提出铁磁反铁磁界面交换作用模型,并采用数值计算方法对在交换偏置场作用下坡莫合金纳米盘中涡旋的动力学行为进行研究.计算表明,在这种涡旋形钉扎场的作用下,涡旋核的螺旋运动频率会增大,而且随着铁磁/反铁磁之间界面交换作用的增加而线性增加;同时涡旋核向平衡位置的弛豫时间缩短,交换偏置作用起到了阻尼的效果.当有外磁场作用时,交换偏置使得铁磁层涡旋核运动轨迹不再是简单的螺旋曲线,核到盘中心的距离振荡增加直到达到一个稳定值.     

基于多种群遗传算法的涡旋型线误差评定

为了提高涡旋型线的评定精度和效率,基于展成法开发了涡旋型线误差快速测量系统,分别对固定涡旋体和转动涡旋体进行测量.建立了以涡旋中心偏差和转角偏差为参数的涡旋型线径向误差数学模型.分别采用不同的优化算法对涡旋型线误差进行了评定,评定结果表明:多种群实数编码遗传算法(RMGA)对固定涡旋体和转动涡旋体涡旋型线误差评定结果分别为13.01和11.48μm.RMGA能满足涡旋型线误差的评定精度和效率.     

变壁厚涡旋膨胀机型线参数的优化分析

为深入研究变壁厚涡旋膨胀机的型线参数,文章以高次曲线组合型线和圆弧组合型线为例,建立了一种新的优化模型-涡旋型线占积比;讨论分析了型线参数对型线面积和占积比的影响;运用单目标遗传算法对占积比取得极值时的2种组合型线参数取值进行了优化,并运用多目标遗传算法讨论了型线面积和占积比同时优化时的非劣解集及对应参数的选取.该文的...     

型线参数对变截面涡旋压缩机齿厚的影响

为定量研究变截面涡旋压缩机的齿厚变化规律,提出一种由圆渐开线、高次曲线和圆弧组合而成的变截面型线,根据几何模型得到了一种计算变截面涡旋齿齿厚的数学模型,通过对此数学模型的求解,详细分析了影响齿厚的因素,精确建立了齿厚与型线参数（基圆半径、回转半径、齿厚控制系数、最大展弦和连接点）之间的关系.研究表明:所建立的数学模型能够准确描述变截面涡旋齿的齿厚变化规律,并且可以根据设计需求对齿厚的大小以及变齿厚的起始位置进行定量设计,为涡旋齿的柔性化设计提供了思路,该数学模型同样适用于其他类型组合型线的涡旋齿齿厚计算.      

基于多学科设计优化的通用涡旋型线形状优化

针对传统单一涡旋型线难以达到最优压缩特性的缺陷,提出了多学科设计优化方法,利用该方法进行了涡旋型线结构参数的设计优化,建立了基于泛函的通用涡旋型线多学科设计优化数学模型,对基于泛函的通用涡旋型线进行了形状优化,最后给出了涡旋型线形状多学科设计优化方法实例分析.得出了一组能满足多性能较优要求、形状性态良好的涡旋型线,与传统的基圆单一涡旋型线相比,其压缩性能均有显著提高,体积利用系数和压缩比分别提高了15.73 %和22.79 %.     

一种检测涡旋压缩机涡旋盘的新方法

基于涡旋型线的精密加工 ,设计了一套涡旋盘的检测系统 .利用该系统可以检测得到涡旋体的线轮廓度误差 .该系统不存在二次装夹误差 ,检测结果直接反映加工误差 ,可直接用于生产现场中涡旋型线的检测 ,有效地防止了废品的产生 .     

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.     

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