压电支承减摩机理研究

本文在研制要求高分辨力和动态性能的小过载加速度计时,在传统的液浮摆式基础上采用了压电支承。并用润滑和摩擦理论对在轴向正弦激励下支承转动方向的减摩机理进行分析,表明在支承的球枢轴和圆柱宝石眼之间存在着以流体动力油膜润滑为主的多种润滑状态。用雷诺方程和润滑理论的分析方法计算了间隙油膜厚度和承载能力,并用所设计的实验装置验证了润滑状态和测定了静、动摩擦力矩,从而确定了支承的工艺要求和最优参数,使所研制成的加速度计性能较传统的提高1～2个数量级。     

动静压支承滑动轴承性能分析

对用于承载部件的动静压支承滑动轴承进行了弹性流体润滑分析.采用有限元方法产生柔度矩阵计算动静压支承滑动轴承的弹性变形,并在考虑滑动轴承弹性变形下,得出其动压效应随轴承转速的变化、承载能力随偏心率的变化以及静刚度随偏心率的变化情况.结果表明,在弹性流体润滑分析中,用柔度矩阵法可以准确计算动静压支承滑动轴承的弹性变形以及承载性能.     

多支承回转窑支承系统模糊优化配置研究

回转窑支承系统的配置决定着回转窑载荷的分配情况,从而决定着回转窑的整体运行性能.在建立求解回转窑支承载荷力学模型的基础上,以均衡分配回转窑载荷为优化目标,考虑支承系统优化配置中的模糊因素,建立了回转窑支承系统模糊优化配置模型,并用最大最小法对该优化模型进行了求解,结果表明回转窑支承系统模糊优化配置能尽可能地均衡分配回转窑载荷,提高支承系统的性能和回转窑的运转率.     

转子临界转速无极调节支承的设计与分析

转子系统支承刚度对转子系统的临界转速有很大影响,由此推出一种转子整体刚度可调节的新型转子支承系统.本系统设计了四轴联动机构、对称式弹性机构以及变刚度机构,可以对转子系统进行精确定位,增加转子系统的稳定性,延长转子系统的寿命,并且该支承可对转子支承的整体刚度进行调节,从而对转子系统的临界转速进行控制.在这种新型的支承方式下,运用传递矩阵法对支承机构转子系统的临界转速可调节性作了理论分析,并运用有限元法以及试验方法对其分析结果作了相应验证.结果证明该新型转子支承系统可有效地调节转子系统的临界转速.     

高空作业车支承反力测试系统中无线方式的研究

由于高空作业车支承反力测试系统不便于使用线缆作为测量设备的数据通讯和电源供给,采用无线通讯,存在无线通讯频率被干扰或占用的情况以及测量设备的电源供给问题,本文中给出了一种避免无线通讯频率被占用的方法.采用锂离子电池作为供给电源,解决了测量设备的供电问题.真正实现了测量设备与外界的无线.     

高速气流纺杯芯轴振型与轴承受力的计算

本文在高速气流纺杯轴承系统临界速度计算的基础上,通过在刚性支承与弹性支承状态下,芯轴振型与轴承受力的计算、分析、对比,从理论上对弹性支承减震器的作用实质作进一步的探讨。计算结果显示减震器改变了芯轴振型,改善了其疲劳磨损,大大降低了轴承受力的动态峰值,因而对改善轴承的润滑条件、减小摩擦磨损、降低功率消耗、提高轴承使用寿命有重要意义。     

弹性支承下的齿轮传动动力学仿真分析

为了准确得到齿轮传动系统动态特性,对传动轴进行离散处理.数值模拟齿轮啮合内部动态激励,采用改进的齿轮副动力学模型进行计算;同时,模拟各滚动轴承在润滑接触下的动态特性,考虑齿轮啮合时变特性、传动轴的弯扭耦合和支承弹性建立单级齿轮传动样机模型.仿真结果表明,支承条件不同会导致仿真结果差异较大,弹性支承更符合实际.     

60万千瓦汽轮发电机模拟机组弹性阻尼支承理论分析及计算

对60万千瓦汽轮发电机模拟组弹性阻尼支承进行了研究,开发研制了计算机程序,计算分析表明,该程序可应用于多质量多支承变截面的大挠性转子系统的计算.     

基于有限元法的气浮支承系统的数值模拟与实验研究

气浮支承系统以气体作为工作介质,根据气体润滑理论对气膜中气体的流动作了理论分析,采用有限元法对气膜流场进行了数值模拟,计算出了一定载荷下的速度分布、压力分布和耗气量、承载能力,通过与实验测试结果的对比,说明该方法是可行的.     

基于有限元法的气浮支承系统的数值模拟与实验研究

气浮支承系统以气体作为工作介质,根据气体润滑理论对气膜中气体的流动作了理论分析,采用有限元法对气膜流场进行了数值模拟,计算出了一定载荷下的速度分布、压力分布和耗气量、承载能力,通过与实验测试结果的对比,说明该方法是可行的.     

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