脱水风机的振动测试分析

1.设备情况 某厂从日本引进的玻璃棉生产线,投产后运行状态良好。为了提高设备的管理水平,对其进行振动状态监测,这条生产线只有一台脱水风机是国产设备,且振动一直很大。通过对其进行周期性监测,并进一步做了对中处理和现场动平衡,运行情况达到了良好。     

交通振动对邻近古建筑的动力影响测试分析

对北京地铁2号线和在建直径线邻近古建筑(明城墙遗址和京奉铁路正阳门老车站旧址)现场测试,评估其在既有地铁交通和路面交通作用下的振动响应,并研究古建筑结构振动响应的传播规律.测试结果表明:1)时域内,古建筑结构在地铁运营下的振动响应是路面交通的10倍左右;交通振动引起古建筑结构的动力响应随水平距离和竖直距离呈规律改变,且古建筑结构以水平方向动力响应为主;2)频域内,地铁交通引起古建筑响应的主要频段是40～90 Hz,路面交通引起古建筑响应的主要频段是10～20 Hz,且路面交通引起的古建筑振动速度在一定范围内出现放大现象.     

机床振动测试分析系统开发

根据市场需要,重庆迪佳科技有限公司与重庆大学合作开发了机床振动分析测试系统.介绍该系统的测试内容、测试仪器布置及测试方法,以及系统的结构、硬件及客户端软件.该系统通过了各种现场实验测试,并已投产使用,应用效果良好.     

三点弯曲法测试硬质合金弹性模量

通过确定荷载范围和修正仪器变形引起的系统误差,用三点弯曲法在电子万能试验机上测定了硬质合金的弹性模量。结果表明:硬质合金弹性模量(y)与Co含量(x)存在稳定的线性关系,其关系式为y=0.13x2-14.24x+708.41,即弹性模量随着Co含量的增加而减小。三点弯曲法测试的硬质合金弹性模量结果稳定、精确,与振动法测试的结果相吻合。这种测试方法简单易行,适合于硬质合金的力学性能表征。     

济钢球团厂1#球磨机电机振动测试与分析

通过点检发现济钢球团厂1#球磨机电机故障后,应用故障诊断和分析技术,对设备进行振动测试与分析,查找设备故障原因,从而避免了设备突发性事故的发生.     

煤气加压机组振动噪声测试及分析

煤气加压机组运行过程中,产生剧烈的振动,不仅影响机组的安全运行,也降低设备和厂房的疲劳寿命,由振动而产生的噪声传递到控制室,严重影响工作人员的工作效率和身心健康。运用基于数字信号处理技术的测试系统,对机组的振动与噪声进行了现场测试,识别出了主要振动、噪声源,提出了初步的减振降噪方案,为后续的改造和治理提供了理论依据。     

议论文中对比分析论证法详解与运用

中学阶段的议论文训练，学生的整体写作能力容易得到提高，但很多高中学生在议论文写作重要的环节素材引用和分析时，难免叙多议少，素材叙述不够简洁，分析和解说不够明白、充分、透彻，这也是高中学生议论文写作的关键环节和薄弱环节，本文就针对此种情况介绍论证方法中一种对比分析法，旨在让学生掌握和学会运用此种方法，帮助学生提高把道理想清楚、说清楚、说透彻的能力，提高其思维水平与理论水平，给学生以论证方法上的指导，有效提高考场作文成绩。     

银山矿业露天采场生产爆破振动测试分析

为研究露天开采过程中生产爆破振动波的衰减规律及其对临近边坡稳定性的影响,以银山露天矿爆破开采工程为背景,对露天采区进行爆破振动效应测试试验。试验结果表明:(1)根据测点与爆源距离、单段最大爆破炸药量、实际测得的振速,采用数理统计原理的最小二乘法进行线性回归分析,得到爆破地震波衰减参数K、α,其爆破振动质点振动速度衰减规律公式为:■;(2)采区临近边坡爆破时,宜采用预裂爆破等控制爆破技术,减少单段最大爆破药量及爆破规模,以此降低爆破振动对边坡稳定性的影响。     

DH45—8型离心式空压机振动的测试与消除

首钢冷轧用的两台DH45-8型透平空压机是引进日本专利国内生产的产品,离心式四级两轴。各级间有中间冷却器,整台空压机安在顺向横卧的三台冷却器上,和1~#、3~＃冷却器焊为一体,冷却器底座一端固定,一端可滑动,结构紧凑,占地少,外有隔音罩,用2240KW四级同步电机驱动,采用带定位齿的齿轮联轴器。在高、低速轴轴承处各装有两套测轴振探头(共8套),和操纵室显示仪表相连(美国     

轧机动系统在急剧振动时扭矩值的测量和分析

对不同类型同传动系统的扭振进行了在外测量,并对测量数据采用快速富氏分析法进行频谱分析。介绍了扭矩珠先进方法及其原理;列出了几套轧机的扭振特性;分析了引起扭振的因素及防止方法,这对认识轧制过程的扭振现象,正确操作和避免事故,具有指导意义。     

减振复合板阻尼测试样品模态分析及尺寸确定

针对减振复合板样品在阻尼测试中样品尺寸标准不一,样品尺寸在确定时缺乏理论依据,无法确定测试样品尺寸的问题,利用有限元方法对减振复合板进行模态分析,用悬臂梁法进行阻尼实测。有限元模拟结果表明,在一定的宽度和厚度下,随着试样长度的增加,其1阶到6阶共振频率均出现降低的规律;在一定的长度和厚度下,随着样品宽度的增加,前4阶共振频率有略微增加的趋势;在一定的长度和宽度下,随着样品厚度的增加,1阶到3阶的共振频率基本保持稳定。实测结果表明,选取自由端长度为216 mm、宽度为12.7 mm的样品,利用2阶和3阶共振频率下的损耗因子进行阻尼表征较为合理。     

基于耐震时程法的连续刚构桥地震损伤分析

探讨了在真实成桥内力状态下,耐震时程法(Endurance time method,ETM)评估连续刚构桥地震反应与损伤的准确性和有效性. 以一座典型非规则连续刚构桥为背景,采用MIDAS/Civil模拟实际施工过程,经施工阶段分析得到10 a收缩徐变下的成桥内力状态,再借助等效荷载法建立考虑成桥内力状态的OpenSees动力分析模型;通过与天然地震动下的增量动力分析(Incremental dynamic analysis,IDA)结果相对比,验证了采用ETM可快速准确地得到地震反应的适用性;通过该方法分析了墩顶位移、梁端位移及碰撞力等地震反应,并采用位移延性系数和Park?Ang损伤指数对桥墩损伤进行了量化分析与评估. 结果表明:ETM可以有效地预测真实成桥内力状态下连续刚构桥达到某一损伤程度的时间;耐震时间较短时主桥桥墩较引桥桥墩的损伤要小,耐震时间较长时则反之.      

Using just noticeable differences to interpret test scores.

This study explored the value of obtaining a just noticeable difference (JND) for a test—the difference in scores needed before observers detect a difference in examinees' behavior—as a means of interpreting the practical meaning of scores. Classical psychophysical methods were adapted and applied to the scores of foreign teaching assistants (TAs) on an achievement test, the Test of Spoken English (TSE), and the ratings for English proficiency that the TAs received from their students. The JND for the TSE scores was substantial, as large as the standard deviation of the scores and much larger than the standard error of measurement and guidelines for the d index of effect size for mean differences, suggesting that both sets of standards may highlight score differences that are not practically significant. This study demonstrates the applicability of JNDs for evaluating scores on educational and psychologists' tests. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Using three-color chromosome painting to test chromosome aberration models

Ionizing radiation induces DNA double-strand breaks (DSB), which interact pairwise to produce chromosome aberrations. There have long been two main competing theories of such pairwise DSB-DSB interactions. The "classical" theory asserts that an unrepaired DSB makes two ends that separate within the cell nucleus, with each end subsequently able to join any similar (nontelomeric) end. The "exchange" theory asserts that at a DSB the chromatin does not separate completely; rather the DSB ends remain associated until repair, or an illegitimate recombination involving another DSB, occurs. The DSB-DSB interaction mechanism was tested by using three-color fluorescence in situ hybridization to paint chromosomes and observe "three-color triplets": three broken and misrejoined chromosomes having cyclically permuted colors. We observed 18 "three-color triplets" in 2000 cells after 2.25 Gy of gamma-irradiation. On the exchange model in its standard form such three-color triplets cannot occur, so this model is inconsistent with the observations. On the classical model, formalized as a discrete time Markov chain embedded at the transitions of a continuous time Markov chain, the frequency of occurrence of three-color triplets can be computed by Monte Carlo simulations. The number of three-color triplets predicted mathematically by the classical model was found to be slightly larger than the observed number. Thus our data, together with our computer simulations, exclude the standard form of the exchange model but are compatible with the classical model. The results are also compatible with other, more complicated models.     

Effect of frequency and amplitude of vibration on void formation in dies poured from polyvinyl siloxane impressions

To determine the susceptibility of Escherichia coli O157:H7 to freezing and thawing in apple cider, methods that recover injured cells are needed for accurate enumeration. This study compared the ISO-GRID hydrophobic grid membrane filter (HGMF) SD-39 agar method to two other methods: a reference most probable number (MPN) method, and plating on sorbitol MacConkey agar (SMA). To determine numbers of injured cells, SMA spread plating was also compared to Trypticase soy agar (TSA) spread plating. Two strains of E. coli O157:H7 QA 326 and ATCC 43895, were inoculated into presterilized apple cider (10 ml) which was then frozen (-20 degrees C for 24 h). Samples were thawed at 4 degrees C for 4 h, or at 23 degrees C for 1.5 h, or in a microwave oven (700 W for 10 s). Substantial cell death (0.69- to 6.33 log10 CFU/ml decreases) and injury (0.70- to 2.38-log10 CFU/ml decreases) occurred during freezing and thawing. The extent of death and injury varied with strain and thawing method. The TSA spread plating method recovered the most cells while the HGMF method always recovered more viable cells than the reference MPN method and also either recovered significantly more (P < 0.05) cells or a not significantly different number of cells than SMA spread plating. Some injured cells of both strains were not counted by the HGMF method. Significant numbers of cells injured by freezing and thawing at 4 degrees C in apple cider were enumerated in the cider was diluted 1:2 Trypticase soy broth immediately before plating. Two epifluorescent microscopic methods showed that injury was not associated with loss of cell membrane integrity.