500kA电解槽焙烧启动技术

该文从焙烧启动的流程、所用物料、工器具、电解槽检查、铺焦挂极、装炉、通电焙烧、启动、启动后期管理及数据测量等方面论述了酒钢集团甘肃东兴铝业有限公司500k A电解槽焙烧启动技术。     

单斗轮取料机斗轮电机启动方式的改造

单斗轮取料机的斗轮电机原有的启动方式启动电流大，电机的启动性能差，容易造成斗轮的联轴器、高速轴、减速机等部位的损坏。启动方式改为软起动器起动后，启动性能得到优化，电机及机械的寿命延长2倍，年减少非正常停车120小时。     

铝电解槽干法无效应启动生产实践

对铝电解槽干法启动和湿法启动的利弊进行分析,并提出了干法无效应启动的改进方案。该方案克服了干法无效应启动存在的弊端,并使其应用于生产实践,相比于湿法启动更加节能、更有利于延长槽寿命。     

质子交换膜燃料电池启动策略

为了缩短质子交换膜燃料电池启动过程中氢气/空气界面存在的时间并限制电堆启动电压,通过实验研究直接启动、启动前氢气吹扫时间以及启动辅助负载对质子交换膜燃料电池性能影响的差异性,在此基础上提出一种电堆启动时氢气吹扫阳极和启动辅助负载相结合的燃料系统启动控制策略.实验验证了该启动控制策略不仅能限制燃料电池启动时的高电压以及缩短燃料电池启动过程中电堆阳极侧氢气/空气界面的存在时间,还有利于提高单电池的电压均衡性,是一种有效的质子交换膜燃料电池启动控制策略.      

降低240kA铝电解槽焙烧启动成本的途径探讨

从240 kA铝电解槽焦粒焙烧启动过程中物料与能源消耗入手,结合生产实际对焙烧启动过程中装炉用料配比的优化、最佳焙烧时间的确认、湿法无效应启动以及降低启动电压等方面进行了研究,探讨了降低240 kA铝电解槽焙烧启动成本的途径,并对产生的经济效益与社会效益进行了阐述。     

600kA铝电解槽焙烧启动实践

针对600 kA铝电解槽焙烧启动时存在角部阳极导电偏低、电流分流量低、冲击电压高、启动温度高、灌铝量低等问题,某公司从装炉作业、分流设计、焙烧升温制度、启动温度控制、灌铝前后电压控制等方面优化电解槽焙烧启动工艺,取得了良好的焙烧启动效果。     

1420冷连轧机穿带启动轧制工艺及过程仿真

通过消化剖析某1420冷连轧机组原有的穿带启动轧制过程的数学模型和控制系统,并建立针对此机组的穿带启动轧制过程的仿真平台,分别从工艺和控制角度深入研究了此机组启动轧制过程中存在的问题——张力不稳、启动困难,指出了问题产生的主要原因,提出通过优化启动工艺和控制策略及数学模型解决此机组启动轧制过程中存在问题的技术措施。     

轧机软启动控制优化

本文主要分析1550轧机软启动的过程控制并分析造成轧机启动跑偏的原因,根据现场生产数据分析机架的倾斜、机架间张力以及启动前带钢位置对启动跑偏的影响。同时对日立轧机软启动过程进行研究,提出轧机启动过程中对机架倾斜、张力差进行监控,并根据来料带钢的规格动态设定最小轧制力等控制优化方案,有效避免轧机启动跑偏。     

石墨化阴极365 kA预焙阳极铝电解槽启动后期管理

通过对石墨化阴极大型预焙槽启动后期管理工艺的分析研究,总结提出适合350 kA以上大型预焙阳极电解槽的启动后期管理工艺思路.对某铝厂365 kA型石墨化阴极预焙铝电解槽进了启动后期管理的工业试验,考察启动后期电解槽槽况的变化、炉膛建立、生产指标完成情况等,对管理方案进行实验验证.指出启动后期管理中应避免的一些问题和方法.     

石墨化阴极365kA预焙阳极铝电解槽启动后期管理

通过对石墨化阴极大型预焙槽启动后期管理工艺的分析研究,总结提出适合350 kA以上大型预焙阳极电解槽的启动后期管理工艺思路.对某铝厂365 kA型石墨化阴极预焙铝电解槽进了启动后期管理的工业试验,考察启动后期电解槽槽况的变化、炉膛建立、生产指标完成情况等,对管理方案进行实验验证.指出启动后期管理中应避免的一些问题和方法.     

Translation of the flagellar gene fliO of Salmonella typhimurium from putative tandem starts

The flagellar gene fliO of Salmonella typhimurium can be translated from an AUG codon that overlaps the termination codon of fliN (K. Ohnishi et al., J. Bacteriol. 179:6092-6099, 1997). However, it had been concluded on the basis of complementation analysis that in Escherichia coli a second start codon 60 bp downstream was the authentic one (J. Malakooti et al., J. Bacteriol. 176:189-197, 1994). This raised the possibility of tandem translational starts, such as occur for the chemotaxis gene cheA; this possibility was increased by the existence of a stem-loop sequence covering the second start, a feature also found with cheA. Protein translated from the first start codon was detected regardless of whether the second start codon was present; it was also detected when the stem-loop structure was disrupted or deleted. Translation from the second start codon, either as the natural one (GUG) or as AUG, was not detected when the first start and intervening sequence were intact. Nor was it detected when the first codon was attenuated (by conversion of AUGAUG to AUAAUA; in S. typhimurium there is a second, adjacent, AUG) or eliminated (by conversion to CGCCGC); disruption of the stem-loop structure still did not yield detectable translation from the second start. When the entire sequence up to the second start was deleted, translation from the second start was detected provided the natural codon GUG had been converted to AUG. A fliO null mutant could be fully complemented in swarm assays whenever the first start and intervening sequence were present, regardless of the state of the second start. Reasonably good complementation occurred when the first start and intervening sequence were absent provided the second start was intact, either as AUG or as GUG; thus translation from the GUG codon must have been occurring even though protein levels were too low to be detected. The translated intervening sequence is rather divergent between S. typhimurium and E. coli and corresponds to a substantial cytoplasmic domain prior to the sole transmembrane segment, which is highly conserved; the sequence following the second start begins immediately prior to that transmembrane segment. The significance of the data for FliO is discussed and compared to the equivalent data for CheA. Attention is also drawn to the fact that given an optimal ribosome binding site, AUA can serve as a fairly efficient start codon even though it seldom if ever appears to be used in nature.     

从操作过电压谈高压电机软起动装置的选择

从操作过电压产生机理出发，阐述操作过电压对高压电动机的危害，通过对高压电机在各种情况下操作过电压的探讨分析，指出高压电动机采用传统起动方式存在的问题，分析了高压电动机采用软起动的必要性，通过对当前各种软起动装置的比较，提出了选择依据。     

On negative selection against ATG triplets near start codons in eukaryotic and prokaryotic genomes

The frequencies of ATG triplets in the genomes of various species were systematically analyzed, and the frequency of ATG triplets was significantly low around start codons in both prokaryotic and eukaryotic genomes. In eukaryotes, however, the frequency decrease before the start codon is much more evident than that after the start codon. In prokaryotes, on the other hand, the ATG frequency pattern around the start codon is less evident, and-more importantly-symmetric. We also computed average distances between a start codon and its nearest upstream-located ATG triplet and found a general tendency for the average distances to be longer in higher organisms.     

软启动装置在风机中的应用

随着工业化规模的不断扩大,大容量电机的应用急剧增加。而大容量电机启动时产生的大电流冲击严重影响着工业设备的正常运行和使用寿命。本文主要分析了当今工业中为解决电机启动过程中的大电流冲击问题而产生的软启动装置。简要的介绍了电动机软启动的启动方式,软启动装置的种类和组成以及特点。并结合酒钢烧结厂抽风机简要的介绍了液阻式软启动装置的原理,特点。最后分析了未来软启动的发展方向。     

梅钢4号烧结机主抽风机变频软启动系统

介绍一个采用一台西门子GL150型LC I变频器依次启动两台6 900 kW同步电动机拖动的主抽风机的变频软启动系统。变频器的控制方式为转矩控制,启动方式为分段加速,变频软启动系统通过降压变压器-GL150变频器-升压变压器启动10 kV同步电动机。GL150型变频器采用大功率晶闸管元件,变频软启动系统在启动中通过直接检测定子电压、电流来计算转子位置,不需要外置的测速编码器。采用变频软启动方式启动大型高压电动机,避免了传统的不变频异步启动方式必然带来的电动机电枢发热严重的现象。采用GL150型变频器的变频软启动系统,在整个启动-并网过程中对电动机完全可控,对风机无冲击。     

交流电动机的软起动技术

交流电动机的软起动是一种综合技术，它克服了发鼠笼异步机传统降压起动方式的许多缺点，通过采用软起动器可以实现交流电动机的软起动。本文介绍了交流电动机主要的几种软起动方式以及交流电动机软起动的特点，并指出了软起动器的其他一些应用。     

液态变阻软起动器在高压鼠笼型电动机上的应用

通过对几种起动方式的计算、分析,介绍了GZYQ认态变阻软起动器的实际使用情况,为改善大型高压鼠笼电动机在过程大中电流对电网和设备的冲击,提供了一个切实可行的起动装置。     

Where am I? Distal cues use requires sensitivity to start location change in the rat.

Place learning is impaired when a single plus maze is moved between adjacent locations 33-120 cm apart. This maze translation creates distinct start locations but maintains a single goal location with respect to distal cues. Hippocampal cell recording data suggest the majority of place fields are tied to apparatus boundaries, not to distal cues, when an apparatus is moved these distances to the left or right. Thus, rats may fail to appreciate the existence of multiple start locations with respect to distal cues when the maze is moved in this way and their start location on the surface is constant. Performance on the single plus maze problem was improved when texture cues were correlated with different start locations. Place learning was supported when multiple start locations were provided on a single large surface (double plus maze), even though rats did not explore the entire surface. Place learning was also supported when random extensions were added to a double plus maze such that start locations, relative to surface boundaries, were not informative as to goal location. This outcome suggests sensitivity to multiple start locations is required for distal cue use in translational place problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

IF钢开浇阶段铸坯洁净度分析

由于IF钢生产过程中对开浇阶段铸坯质量判定不明确,因此在利用时容易导致产品质量问题而增加生产成本。通过对头坯不同位置进行取样,研究IF钢开浇阶段铸坯沿拉坯方向的洁净度变化。实验结果表明,IF钢开浇阶段铸坯中大型夹杂物主要来源于结晶器卷渣和中间包中来不及上浮的脱氧或二次氧化产物;从距离头坯头部2.5m位置开始,由结晶器卷渣所引入的大型夹杂物含量接近正常坯水平;距离头坯头部7.5m位置处开始N含量与正常坯含量基本持平,簇状Al_2O_3夹杂物数量及尺寸接近正常坯水平;距离头坯头部8.5m位置处开始全氧质量分数保持在20×10~(-6)左右。     

高碳帘线钢72A连续冷却转变(CCT)的特性

采用热膨胀法,通过THERMECMASTOR-Z热模拟实验机测试了高碳帘线钢72A(%:0.72C、0.53Mn、0.22Si)的连续冷却转变(CCT)曲线,并分析了开始冷却温度(840～930℃)和冷却速度(0.8～22℃/s)对钢组织的影响。结果表明,相同开始冷却温度条件下,冷却速度越快,相变时间越短;相同冷速条件下,随着开始冷却温度的升高,到达相变开始转变温度的时间和到达转变终了温度的时间会延后;提高开始冷却温度,珠光体的百分含量增加,珠光体片层间距减少,有利于提高线材力学性能。