励磁装置在无刷同步电动机的应用

本文详细介绍了励磁装置的原理、结构技术性能和励磁保护,穿插介绍了国内最新颖的全数字式微机励磁装置实际的先进的工作原理和应用情况,分析说明目前我厂同步电动机所使用励磁装置的应用状况。     

同步电动机频繁损坏的解决措施

同步电动机因为具有温度低、运行稳定、输出功率大,特别是支持电网电压,提高功率因数等一系列优点,所以在化工行业得到广泛应用.但是,长期以来发生同步电动机及其励磁装置损坏事故屡见不鲜.本文阐述同步电动机频繁损坏的根本原因不在电动机本身,而在励磁装置技术性能太差.针对励磁装置技术性能的缺陷,进行技术改造.     

天生桥电站励磁装置的改造

本文总结通过对天生桥电站2#机原有励磁装置的改造经验，自投入运行以来（2004年3月-2007年1月），新励磁装置操作简便，工作性能指标优良，可靠性高，运行维护简单，同比原来的直流励磁机励磁方式有许多不可比拟的优越性．在小型农村水电站励磁装置改造中值得推荐。     

大型同步电动机励磁装置的改造

制氧车间使用的3号氧压机、2号氮压机励磁装置,为前苏联产品,投入运行了近十五年,设备故障不断发生。动力厂采用中国核工业部电机运行技术开发公司生产的BKL-501H型励磁装置,取代原前苏联励磁系统,取得了较好效果。     

同步电动机可控硅励磁装置的安装与调试

通过KGLF-10和BKL-I系列可控硅励磁装置的安装调试,介绍了可控硅励磁装置在安装和调试过程中所解决和注意的问题。     

浅谈200MW发电机组励磁系统与PSS装置

同步电机励磁系统是＂提供电机磁场电流的装置,包括所有调节与控制元件,还有磁场放电或灭磁装置以及保护装置＂。励磁控制系统是包括控制对象的反馈控制系统。励磁控制系统对电力系统的安全、稳定、经济运行都有重要的影响。     

移动电源用同步发电机的磁性半导体自励磁装置

清华大学与天津发电设备厂合作研究试制成功了新型的磁性半导体自励磁装置。这种装置与柴油发电机组共装在卡车的拖车上,从而可以到山区、林区、边远地区以及其它许多缺电的地方发出电力,在国民经济发展中是很有意义的。 原有的国产电源车采用直流机励磁,并应用TD—1型炭阻式自动电压调节器进行励磁调节。这种励磁系统的主要缺点是运行可靠性较差、电压精度较低、启动异步机的能力较弱、直流机和炭阻调节器的制造也较费事。 新型的励磁装置克服了上述缺点,采用以硅整流器和相位复励变压器组成的磁性半导体励磁系统代替电机励磁,励破所需功…     

关于励磁装置故障分析与探讨

介绍了励磁装置在主扇风机正常运转中的作用,结合工作中的实际情况,对励磁装置经常出现的故障进行了技术分析。     

EX2100励磁系统保护逻辑分析

励磁系统的控制是由SCR（半导体可控整流桥）整流桥回路的相位控制得到的。SCR的触发信号是由控制器中的数字调节器产生的。励磁装置是一个灵活的模块系统,它可以组合起来,以提供一定范围的输出电流和几级系统冗余。EX2100励磁控制（EX2100或励磁装置）输出励磁电流,以控制发电机交流端电压,和/或无功功率。它是为新建的和改造的汽轮机、燃气轮机和水轮机设计的全静态励磁系统。     

西门子1FC5和1FC6发电机励磁装置的替换

目前国内油田配备了大量国产西门子1FC5、1FC6系列无刷三相同步发电机,在实际使用中发现,该系列机的励磁装置故障率很高,由于励磁装置用器件比较多,调整比较烦琐,所以在现场修复比较困难,严重影响钻井生产。本文在简要回顾了西门子励磁装置原理,分析了引起故障的原因,提出用通用发电机自动电压调节器代替相复励磁装置,并在现场进行应用并取得了良好效果,证明方案是可行的。     

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.     

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.     

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.     

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.