U形管式换热器管板的优化设计

简要介绍了U形管式换热器管板设计规范;并通过MATLAB编程计算和绘图,实现了对U形管式换热器管板的优化设计。该研究对于U形管式换热器的工程设计具有一定的参考价值。     

直立倒装U型管式换热器管束快捷检修方法

更换直立倒装在钢架平台上的U型管式换热器固定管板与壳体法兰间的垫片及检查U型管泄漏位置并堵管是一项难度较大的检修工作,现介绍一种现场快捷检修U型管式换热器的方法。     

浅析一种U型管冷弯快速成型法

介绍了一种利用焊接变位器快速煨管成形的方法,解决U型管换热器制作中最为耗工耗时的问题,提高了U型管换热器制作的工作效率。     

管壳式换热器在工艺螺杆压缩机中的应用

换热器作为一种基本的换热设备,在化工、动力、冶金、食品、能源、航天等工程领域中有着广泛的应用.阐述了U型管壳式换热器在工艺螺杆压缩机中的应用及利用经验算式和htri软件方法对换热器进行设计,为石化压缩机系统中换热器的选型提供合理的依据.     

压缩机辅机换热器制造难题排解

针对往复压缩机辅机中大型U型管式换热器遇到的制造难点,笔者将列举U型管用压制方法解决大型U型管在生产加工中的难题。     

地能换热器的分析与研究

阐述了地能换热器作为地源热泵系统的主要组成部分，对其进行了分析研究。指出了套管式换热器优于U型管式换热器、影响套管式换热器的具体关联因子和今后地能换热器的研究方向。     

管壳式换热器试压工装

阐述了钩圈浮头式换热器、浮头管板廉作法兰浮头式换热器、浮头式换热器管束和管板非兼作法兰U形管式换热器管束的试压工装设计思路，并提出了详细的试压方案。     

氮肥工程上“O”形膨胀节的应用

在合成氨生产过程中,其工艺流程一般都是在中温、中压或高压下进行的。为了合理的充分利用能源,回收热量,势必在工艺过程中不可缺少的大量使用换热器。在以往的设计中,因壳程和管理压力较高、温差较大,使用“U”形膨胀节亦不能满足设计要求。所以不得不把结构简单的固定管板式换热器改设为结构复杂的浮头式换热器或U形管式换热器。这样一来使得设备结构复杂,也增加造价,有时也很难达到理想的工艺要求。在70年代初我国引进30万吨大化肥,在尿     

翅片式换热器短U管自动装配方法与装置研究

换热器是空调系统中四大核心部件之一,在翅片式换热器生产制造过程中短U管装配工序凭借个人记忆确定系统管路回路,进行人工装配,极易产生装配错误,导致质量问题。现介绍一种更为先进的翅片式换热器中短U管自动装配方法及装置,其特性在于使用信息系统及PLC系统传输产品参数,利用机器人系统及视觉系统分析来料工件的管口偏差及位置偏差并补偿给机器人,完成短U管准确安装,实现全系统的自动化安装,避免人工装配作业错误。     

换热器U型管束组装制造工艺

针对换热器U型管束制造组装要求,制定工艺规程。方案从U型管结构特点开始分析了工艺难点所在,在依据组装精度要求上,制定了组装制造工艺方案。进而依据方案制定工装等。对于焊接特殊行业的换热器的制造工艺提供了可行的参考。     

Immunohistochemical distribution of enkephalin, substance P, and somatostatin in the brainstem of the leopard frog, Rana pipiens

The brainstems of frogs contain many of the neurochemicals that are found in mammals. However, the clustering of nuclei near the ventricles makes it difficult to distinguish individual cell groups. We addressed this problem by combining immunohistochemistry with tract tracing and an analysis of cell morphology to localize neuropeptides within the brainstem of Rana pipiens. We injected a retrograde tracer, Fluoro-Gold, into the spinal cord, and, in the same frog, processed adjacent sections for immunohistochemical location of antibodies to the neuropeptides enkephalin (ENK), substance P (SP), and somatostatin (SOM). SOM+ cells were more widespread than cells containing immunoreactivity (ir) to the other substances. Most reticular nuclei in frog brainstem contained ir to at least one of these chemicals. Cells with SOM ir were found in nucleus (n.) reticularis pontis oralis, n. reticularis magnocellularis, n. reticularis paragigantocellularis, n. reticularis dorsalis, the optic tectum, n. interpeduncularis, and n. solitarius. ENK-containing cell bodies were found in n. reticularis pontis oralis, n. reticularis dorsalis, the nucleus of the solitary tract, and the tectum. The midbrain contained most of the SP+ cells. Six nonreticular nuclei (griseum centrale rhombencephali, n. isthmi, n. profundus mesencephali, n. interpeduncularis, torus semicircularis laminaris, and the tectum) contained ir to one or more of the substances but did not project to the spinal cord. The descending tract of V, and the rubrospinal, reticulospinal, and solitary tracts contained all three peptides as did the n. profundus mesencephali, n. isthmi, and specific tectal layers. Because the distribution of neurochemicals within the frog brainstem is similar to that of amniotes, our results emphasize the large amount of conservation of structure, biochemistry, and possibly function that has occurred in the brainstem, and especially in the phylogenetically old reticular formation.     

汽车B柱Rollforming成型的有限元仿真

在汽车车体构件制造中的辊弯成型工艺应用项目研究中,利用大型非线性有限元分析软件MSC.Marc研究了汽车B柱变截面辊弯成型仿真的有限元建模方法,主要包括板料模型和成型辊模型的建立、单元选择、边界条件、各种参数的设置及成型辊的速度加载等内容,然后采用刚性轧辊沿板料长度方向平动的方式对板料成型过程进行仿真模拟,分析了板料在...     

APPLICATION OF WAVELET TRANSFORM ON DIAGNOSIS AND PREDICTION OF MILLING CHATTER

In order to avoid the accuracy deterioration or tool damage caused by milling chatter, it is necessary to have an efficient and reliable diagnosis system that can on-line predict/detect the occur-rence of chatter. The diagnosis/predicting system proposed is to on-line process and analysis the vi-bration signals of the milling machine measured by accelerometers. According to the analysis results, the system will be able to detect/predict the occurrence of the chatter. The diagnosis algorithm is, first, collecting both the normal signals and chatter signals from milling processes, and then, converting the signals through wavelet transform and fast Fourier transform (FFT). Since the converted chatter sig-nals exhibit different characteristics from the normal signals, through defining the characteristic val-ues, such as root-mean-square value, max value, and ratio of peak value to root-mean-square value, etc, a diagnosis reference library that contains the distribution of these characteristic values is built for diagnosis. When a diagnosis is executing, the characteristic value of the measured signals is con-trasted with the diagnosis reference. The approach index which shows the possibility of occurrence of milling chatter will, then, be calculated through the diagnosis system. Cutting experiments are con-ducted to verify the proposed diagnosis system. The results show the success of early chatter detecting for the system.     

简易多功能计数器的设计

设计了一个简易多功能计数器,由89C52单片机控制。配合相应的测量电路以及相应的软件,实现对频率、周期和时间间隔,被测信号峰值、温度等的测量,可记录10个历史数据,且具有掉电保持功能。其主要电路包括电平电路、时基电路、测频电路、测周电路、测温电路,键盘输入电路,显示电路等,信号输入后先自动判断频率的范围,然后选择需要的测量电路.通过单片机对数据进行处理,在误差允许的范围内显示各个测量值。     

“老板文化”对“企业文化”的作用——也谈“企业文化”建设的认知

优秀企业的成长、发展、壮大,与其优秀的＂企业文化＂建设不无关系。任何企业都是有文化的,不存在没有文化的组织,只有不同文化的组织。衡量企业文化的标准,只有显著程度、优劣和现实性,而不是有或无。只要有人群存在,他们的行为就构成一定的文化。企业老板,是企业文化的倡导者和缔造者。老板对企业文化建设的影响很大。＂老板文化＂是＂企业文化＂的奠基石。因此,企业要创建优秀的企业文化,企业领导层首先要有优秀的＂老板文化＂。而随着企业的发展,企业所有员工共同参与讨论并提炼企业文化,逐步走向民主与开放。这时的企业文化更多的融入了集体的智慧,老板文化的作用会逐渐减小,所以企业文化又不单是老板文化。     

浅谈汽油机尾气排放的控制

汽油发动机尾气排放控制主要分为机体内的控制和机体外的控制;关于机体外的控制,笔者从废弃再循环装置、二次空气供给系统、曲轴箱通风、燃油蒸发控制、三元转化催化装置等五个方面进行了阐述,并得出的结论是汽油发动机的尾气控制是综合控制,与多方因素有关.     

A system for wear prediction in lubricated sliding contacts

A system of analysis is developed to predict the rate of wear in sliding contacts. The essence of the approach is the proposal that the rate of wear can be predicted only in probabilistic terms. Therefore, the estimation of the probability of wear, which can be regarded as synonymous with the probability of surface asperity contacts, precedes the calculation of the wear rate. Further, recognising the fact that wear takes place within the actual area of contact, it is argued that this area consists of plastic and elastic contacts between asperities which, in turn, have different shear strengths and contribute differently to the wear process. In the case of lubricated contact, a frictional film defect represents the influence of a lubricant on the wear process. Moreover, as in this type of contact the load is supported by both lubricating film and contacting asperities, a special procedure is provided to estimate the load supported by the asperities, because it is only that part of the load which contributes to the wear. The catastrophic form of wear in lubricated contacts, that is termed ‘scuffing’, is also considered, and the probability of scuffing, under a given set of operating conditions, is estimated. The predictive system has been tested and its predictions are compared with available experimental results.     

Sperm ultrastructure and spermatogenesis in the lizard, <i>Tropidurus itambere</i>

Spermatogenesis, with emphasis on spermiogenesis, is described for the lizard, Tropidurus itambere, using light microscopy, phase contrast and epifluorescence, as well as scanning and transmission electron microscopy. Cellular differentiation involves events of chromatin condensation, nuclear elongation and the formation of structural complexes, such as the acrosomal and axonemal ones. Other new characteristics, exclusive for this species, include various aspects of the subacrosomal granule, the insertion of the proacrosomal vesicle and the development of these structures to participate in the acrosomal complex. Radial projections occur just above the nuclear shoulders, which have been recognized already from the beginning of cellular elongation. The development of the midpiece, the dense bodies, formation of the flagellum and elimination of residual cytoplasm result in the final characterization of the mature spermatozoon. Comparisons between Tropiduridae and other lizard families are made.     

引信MEMS后坐机构的设计与实验

通过受力分析并根据动能定理建立了影响后坐机构加速度as的关系式和动力学方程,得到弹性系数K、两侧齿之间竖直方向的间隙d、齿的斜边长a、齿底长c和齿数n的大小决定着as大小的结论。通过ADAMS软件仿真分析,得到运动方程和设计的合理性,并得到K、d、a、c、n与as的关系。仿真结果表明,在同等条件下,严格控制齿底长c的加工误差、减小错位间隙d、增大线宽b均能提高as。同时考虑增大齿数n来提高as。对采用LIGA工艺加工出的后坐机构进行模拟实验,验证了仿真分析的合理性和加工误差的影响,同时验证了设计和运动方程的合理性。     

谐波齿轮传动误差的补偿控制

由于谐波系统中存在传动误差,结果会使机构无法准确执行预定的传动。为了对谐波齿轮系统的传动误差进行补偿,本文首先对谐波齿轮传动系统进行分析,综合考虑谐波齿轮啮合摩擦、扭转刚度、侧隙、传动误差等多种非线性因素,根据谐波齿轮传动系统的力学模型,建立系统非线性动力学微分方程。采用PID控制器对系统进行控制,为补偿误差根据传递函数建立了控制系统方框图。最后通过比较PID控制前后的仿真误差,证明了PID控制对误差补偿的有效性。