高速数控车削中心主轴单元的可靠性研究

分析讨论了超高速数控车中心主轴单元性能的可靠性要求，对高速数控车削中心的主轴单元典型结构－电主轴的设计进行了详细记述，为车削中心提供了必要的依据和设计方法。     

精密电主轴结构设计及测控技术发展现状

由于经济和环境因素,现阶段对高速、高精度、高效机床的需求越来越迫切,电主轴作为数控机床的关键功能部件,国内外学者在电主轴结构设计及测控技术方面做了大量的研究,取得了较好的研究成果。主要从国内外电主轴的结构创新、优化设计提高电主轴综合性能及电主轴的测量技术进行介绍,从中了解电主轴的研究现状,为我国电主轴设计人员及学者提供参考。     

高速电主轴热态特性研究综述

电主轴技术是随着高速数控机床的发展和需求而发展起来的.高速电主轴的工作性能直接影响机床加工系统的精度、稳定性和应用范围,其热态特性对高速加工起着关键作用.本文对高速电主轴内部的发热进行了深层次的综述,同时结合电主轴稳态热分析,提出了改善电主轴的热态特性的措施.     

高速电主轴机电耦合实验教学方法研究

提出了高速电主轴机电耦合实验教学方法,建立了高速电主轴机电耦合实验环境和实验方案,研究了高速电主轴机电耦合实验方法(主要是加载实验方法),并分析了实验结果.通过实验研究突出科研成果在教学中的应用,启迪学生的科学思维和创新意识.     

磨削加工电主轴热态分析与温升测试

通过分析电主轴的发热源,找出影响其温升特性的相关因素。采用ANSYS有限元分析软件对电主轴温度场进行分析,并对温升时产生的热变形进行仿真模拟,为进一步制定热误差补偿方案提供依据。针对电主轴内部温度难以检测的问题,建立温度预测模型,在红外测温法的基础上进行实验研究。结果表明,该方法能有效建立预警机制,可实现电主轴内部温度的预测和提前报警。     

从电主轴装备看高速数控机床发展趋势

本文通过介绍电主轴与直线电机结构和性能的优势，展示了在电主轴及直线电机装备下，当今国内外高速数控机床的新面貌，进而指出了我国高精、高速加工与国际间的差距，对我国高速数控机床产业提出几点建议，仅供同仁参考。     

从电主轴装备看高速数控机床发展趋势

本文通过介绍电主轴与直线电机结构和性能的优势,展示了在电主轴及直线电机装备下,当今国内外高速数控机床的新面貌,进而指出了我国高精、高速加工与国际间的差距,对我国高速数控机床产业提出几点建议,仅供同仁参考。     

基于自适应粒子群优化BP神经网络的高速电主轴温度预测模型（英文）

为精确地预测电主轴高速运转时内部温升的变化情况,提出了一种基于自适应粒子群优化BP神经网络的电主轴温度预测模型(APSO-BPNN).该模型在PSO-BPNN算法的基础上,引入自适应惯性权重,使权重跟随粒子适应度的变化而变化;采用自适应学习因子,在算法的初期和后期获得不同的搜索能力;融入变异算子,增加种群的多样性,避免算法的早熟收敛等缺点.然后,分别采用BPNN、PSO-BPNN和APSO-BPNN预测模型对电主轴不同测温点的温度进行预测.实验结果表明,与传统的BP神经网络和PSO-BPNN预测方法相比,所提APSO-BPNN模型预测精度最高,鲁棒性最强,可为电主轴及机床温升的智能控制和早期预警系统开发提供理论依据.     

交流磁轴承支承电主轴转子系统建模

为克服现有混合磁轴承具有的缺陷,提出一种结构新颖的交流混合磁轴承作为高速电主轴的支承部件,永磁体产生偏磁磁通,电磁铁线圈产生控制磁通;介绍了该磁轴承的结构和工作原理,并基于Matlab/Simulink建立了考虑陀螺耦合的电主轴刚性转子和柔性转子四自由度的模型。     

主轴轴承预紧力预紧装置的研究

主轴轴承预紧力是高性能电主轴的核心技术,对主轴轴承预紧力的研究可知电主轴在其中发挥的最大能力,本论文主要描述的是主轴轴承预紧力发展及研究,通过研究认识到主轴轴承预紧力的发展现状和未来前景。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!