编码器自动监测与故障诊断系统的研究与实现

文中介绍了某大型机电设备编码器的实时监测与故障诊断系统的设计工作.系统采用在线和离线两种工作方式,实现了接触式编码器的监测和诊断.系统硬件主要电路板基于PC104总线结构,18路I/O通道(9路输入,9路输出)完成9位编码器的检测和诊断.系统软件界面友好,巧妙地实现了格雷码与角度值的转换.本系统对其他编码器自动监测和故障诊断系统具有重要的借鉴意义.     

形势要求机床工具工业必须加快增长方式的转型(一)

1999年以来，我国国民生产总值持续快速稳定增长。表1是这期间国民生产总值增长情况。     

成都市彭青公路后张法预应力混凝土空心梁板施工技术研究

成都市彭青公路长25．83km,采用后张法预应力混凝土空心梁板施工,在施工中通过关注混凝土浇筑和钢绞线张拉两大关键技术。提出了自己的见解。     

都汶高速公路庙子坪岷江特大桥震后5号主墩加固技术

都汶高速公路是成都通往汶川的重要的交通枢纽,为国道213和317合线。都汶高速公路庙子坪岷江特大桥(又名紫坪铺大桥)直接跨越紫坪铺水库和岷江,都江堰端接著名的董家山高瓦斯隧道,汶川端接龙洞子隧道。5.12汶川大地震对庙子坪岷江特大桥产生了不少震害,地震后大桥的加固时间紧、工作量大、技术复杂,这在中国乃至世界桥梁史上前所未有;特别是5号主墩加固异常复杂和艰难,从桥面防撞护栏顶面到5号主墩地面承台顶面之间总体落差114.488 m,5号主墩地面承台顶面到水面水深达65 m。通过对5号主墩承台顶面以上14 m加固区间(全部位于深水区域)的潜水堵孔和钢沉箱工艺进行深入细致的研究,制定了系列相应措施。     

化地不化人的城市化符合中国国情吗?——人口密集型的“老浦西”和土地资本密集型的“新浦东”的历史比较

基于对城市化真谛的理解,在论证城市化的二重性和城市集聚效应的内生性的基础上,针对中国城市化过程中存在的化地不化人的弊病,在对比"老浦西"和"新浦东"城市化机制及其绩效后发现,"新浦东"受制于现行户籍和土地制度,对人口、土地和资本等要素的配置以行政导向为主,以土地密集和资本密集为主要特征,对中国真实城市化率的提高贡献甚微,陷入城市自我现代化的困境,也违反国情和环保的要求,难以持续。对众多农村人口亟待城市化的中国而言,"新浦东"模式不具备普遍意义。市场导向的人口密集型的"老浦西"模式,更符合内生增长的要求,更能发挥城市吸收农村人口的集聚效应,也更符合可持续增长和环保原则,值得今日中国借鉴。     

基于自相关降噪的混叠转子振动信号分离

航空发动机在运行过程中,传感器测得的振动信号是各振源的混叠信号,且含有很强的噪声。常规的信号处理方法难以分离混叠信号,对机器的健康监测和故障诊断造成了很大的困难。介绍了盲源分离基本原理和方法,指出盲源分离算法在强噪声环境下失效。针对强噪声环境下的混叠振动信号,提出首先通过时延自相关降噪方法对振动信号进行降噪,然后通过盲源分离算法对降噪后的信号分离。仿真结果验证了提出方法的有效性。最后,利用该方法对实测混叠转子振动信号成功实现了降噪和盲分离,为噪声环境下的混叠信号分离提供了一种新的方法。     

The effect of nonsteroidal antiinflammatory drugs on electrolyte homeostasis and blood pressure in young and elderly persons with and without renal insufficiency

More than 35% of atria in Hong Kong can be classified as linear with large transverse dimensions. The smoke filling process due to fires in these atria was studied. Both the zone model and the computational fluid dynamics (CFD) field model were used. A linear atrium of volume 7,500 m3 was taken as an example. The multicell concept was used while simulating the smoke filling process with the zone model. Results were also justified by studying the smoke filling patterns in a scale model. The effects of the space volume on the smoke filling process was studied in three larger atria with volumes of 15,000, 22,500, and 30,000 m3. Finally, natural smoke-control systems, using horizontal ceiling vents in the first atrium, were studied.     

Cytoprotective effects of adrenomedullin in glomerular cell injury: central role of cAMP signaling pathway

Activation of cAMP signaling pathway was shown to inhibit some pathobiologic processes in mesangial cells (MC). We investigated whether adrenomedullin (ADM), a potent agonist of adenylate cyclase, is synthesized in MC and whether it can, via cAMP, suppress the generation of reactive oxygen metabolites (ROM) and proliferation of cells in glomeruli. With the use of an immunohistologic technique ADM was detected in mesangial and microvascular areas of rat glomeruli. MC grown in primary culture synthesized ADM, and the synthesis was stimulated by TNF alpha and IL-1 beta but not by PDGF and EGF. ADM inhibited ROM generation in MC dose-dependently and caused in situ activation of protein kinase A (PKA). In macrophages (cell line J774) ROM generation was about four times higher than in MC and was inhibited by ADM in a similar way as in MC. The rate of MC proliferation, measured by [3H]-incorporation, and the activity of mitogen-activated protein kinase (MAPK) stimulated by PDGF and EGF were dose-dependently inhibited by ADM; the maximum inhibition (at 10 nM ADM) was about -80%. Mitogenesis of MC and MAPK activity when stimulated to a similar extent by endothelin (ET-1) was inhibited by ADM to a significantly (P < 0.01) lesser degree (-30%). Further, ADM inhibited PDF-stimulated mitogenesis and activation of MAPK in cultured vascular smooth muscle cells (VSMC). The inhibition of PDGF-activated MAPK by ADM in VSMC was reversed by the protein kinase A (PKA) inhibitor, H89. Taken together, results indicate the adrenomedullin (ADM) generated in mesangial cells (MC) can suppress, via activation of the cAMP-protein kinase A (PKA) signaling pathway, reactive oxygen metabolites (ROM) generation in MC and infiltrating macrophages as well as mitogen-activated protein kinase (MAPK)-mediated mitogenesis in MC and vascular smooth muscle cells (VSMC). We suggest that introglomerular ADM may serve as a cytoprotective autoacoid that suppresses pathobiologic processes evoked by immuno-inflammatory injury of glomeruli.     

Vaccine evaluation studies of replication-defective SIVsmB7

Non-infectious virus-like particles of SIVsmB7 that expresses env and gag gene products but are defective in pol and vpx/vpr were assessed for their ability to induce protective immunity against infection with pathogenic SIVsmE660 in rhesus macaques. Animals were immunized in three groups: group A was primed with cell-associated SIVsmB7 and boosted with cell-free SIVsmB7; group B was primed with cell-free SIVsmB7 and boosted with cell-free SIVsmB7 conjugated to iron oxide microbeads; group C was primed with cell-free SIVsmB7 mixed with Titer Max adjuvant and boosted with cell-free SIVsmB7 mixed with SAF-M adjuvant followed by secondary boosting with cell-free SIVsmB7 conjugated to microbeads. Animals were challenged intravenously with 20 animal infectious doses of SIVsmE660 grown in rhesus peripheral blood mononuclear cells 3 weeks after final boosting. All animals became infected as evidenced by quantitative virus cultivation. Sera from immunized animals contained low-titer antibodies by ELISA and low or undetectable neutralizing antibodies on the day of challenge but strong anamnestic antibody responses were observed following challenge. Interestingly, 2 of 3 animals in group A showed evidence of transient viremia and more stable CD4 counts following challenge as compared to the other immunized animals and to non-immunized controls. Thus, immunization with cell-associated SIVsmB7 did not provide sterilizing immunity against challenge with a highly pathogenic SIV strain but might have caused virus clearance later in infection.