改善电刷的滑动接触和电刷选择

本文介绍了氧化膜的形成和作用以及对换向的影响。同时论述了电刷选择的方法。     

发电机集电环及电刷故障探析

在集电环上运行时,在其接触面上形成一层均匀、适度、稳定的氧化膜,这是电机运行良好的主要标志之一。因为这层氧化膜的存在,改变了电刷与集电环的接触特性、减少了摩擦、降低磨损、延长使用寿命。本文着重探讨了电刷及集电环常见故障的原因及解决办法,分析了几起集电环、电刷故障的原因并提出相关建议。     

碳纤维－石墨－银基复合材料电刷的应用研究

文章研究了碳纤维－石墨－银基复合材料的制造并应用于雷达电刷传输电讯号。结果表明，应用镀银碳纤维部分代替原银－石黑系电刷中的石墨，能有效提高电刷使用寿命。降低电刷与汇流环之间的动态接触电阻。经过对５８９ＧＡ雷达实机进行实验，各项性能均优于原银－石墨系电刷。     

电机的电接触及表面膜研究

文章综述了电机上电刷的电接触种类、机理及影响因素,讨论了在滑动接触表面上形成的表面膜对电刷的导电性、耐磨性的影响,指出均匀、适度、稳定的表面膜是保证电机正常运行的条件之一.研究了碳纤维-铜-石墨复合材料电刷在电磨损过程中接触电压降的变化情况,证明了碳纤维-铜-石墨复合材料电刷在满足接触电阻为非线性要求上的优越性,观察了复合材料电刷的磨面形貌.     

EM生物接触氧化反应器启动过程试验研究

以啤酒废水为例,讨论了不同填料、不同接种污泥对有效微生物群(EM)生物接触氧化反应器挂膜和启动过程的影响．结果表明：生物接触氧化工艺中使用EM能够缩短反应器的启动时间,提高启动阶段的处理效果;陶粒填料和EM原液接种方式的采用有助于生物接触氧化反应器中EM菌群多种微生物的生长和繁殖,能促进EM接触氧化工艺挂膜和启动的成功．     

不同温度下铁基粉末冶金材料的冲击磨损规律

在不同温度下，对3种Fe基粉末冶金材料的冲击接触磨损速率进行了试验研究，结果表明，试验温度升高使试样表面氧化，导致磨损速率先降低后升高，并在350－400℃时达到最低值，CrNiVCu与CrMoWVCu两种材料的磨损速率与温度关系曲线出现的交点，是由于原材料与高温表面氧化膜硬度变化造成的，而Cu的加入有利于冲击磨损速率的降低。     

铝锂合金硬质阳极化工艺研究

研究了各种工艺参数对铝锂合金阳极化氧化膜生长和硬度的影响。试验表明，氧化膜厚度与电流密度和氧化时间乘积呈线性关系。降低硫酸浓度和温度有利于氧化膜生长和硬度的提高。弯曲试验和ＳＥＭ观察发现，氧化膜与合金基体结合牢固，无剥落现象。初步分析了锂对氧化膜性能的影响。     

铝合金表面装饰性阳极瓷质氧化的研究

铝合金在草酸钛钾的酸性溶液中进行阳极氧化可得到具有装饰效果和防护作用的瓷质氧化膜。研究了铝合金直流电解的电压、电解时间、阳极氧化液温度，以及草酸钛钾和草酸含量对瓷质氧化膜的影响。通过正交实验得到了瓷质氧化的最佳工艺条件，并对氧化膜的防护性能、氧化液主要成分的消耗速度进行了测定。结果表明，最佳工艺条件下得到的瓷质氧化膜耐腐蚀性高，具有独特的装饰效果。     

实用型固定膜催化氧化装置去除水中苯酚研究

实用型固定膜催化氧化装置去除水中苯酚研究李田，严煦世通过实用型固定膜光催化氧化反应器，进行了水中苯酚的光催化氧化研究．试验表明，与光分解相比，光催化氧化具有氧化程度高，可实现完全矿化的优点．相近条件下固定膜与悬浮型光催化氧化装置的运行结果表明，在本项...     

实用型固定膜光催化氧化装置去除水中苯酚

通过实用型固定膜光催化氧化反应器，进行了水中苯酚的光催化氧化研究，试验表明，与光分解相比，光催化氧化具有氧化程度高，可实现完全矿化的优点，相近条件下固定膜与悬浮型光催化氧化装置的运行结果表明，在本项目研制的实用型固定膜装置中，苯酚的光催化氧化效率高于其在ＴｉＯ２水浊液中的氧化效率。     

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