网络系统可靠性研究现状与展望

探讨了网络系统可靠性的发展历程、概念与特点,从多方面介绍了网络系统可靠性的研究现状,最后对网络系统可靠性研究未来的发展进行了展望.     

冗余设计在冶金锅炉检测系统中的应用

针对冶金企业生产发展现状及对锅炉检测系统可靠性要求更高问题,在分析冗余设计技术可靠性的基础上,运用系统可靠性优化原理,结合石钢锅炉水位检测系统的实例,提出了在现有技术条件下,提高锅炉水位检测信息可靠性的多传感器融合技术.通过对系统可靠性分析和数值计算对比,证明该方法是可行的、有效的.     

基于熵值法—突变理论的地下矿山紧急避险系统可靠性研究

为了确保紧急避险系统在地下矿山应急避险中的有效作用,有必要对其可靠性进行研究。结合熵值法及突变理论,基于环境、人、物料、设施设置和管理5个方面,对影响紧急避险系统可靠性的因素进行了3层分解,建立了包含19项指标的评价指标体系,运用熵值法对指标的重要性进行了排序,结合突变理论评估工具,构建了紧急避险系统可靠性评价模型。将该模型应用于山东某地下矿山的紧急避险系统可靠性评价分析,提出了提高其可靠性的对策。研究表明,该评价模型较好地细化及深入剖析了影响紧急避险系统可靠性的因素,客观确定了各层指标的相对重要性,得出了与矿山实际情况一致的评价结果,为地下矿山紧急避险系统可靠性评价提供了一种新方法。     

基于神经网络的矿井通风可靠性预计研究

矿井通风系统是煤矿生产中的重要组成部分,通风系统的稳定、可靠运行关系着煤矿安全生产和井下人员的生命安全。在对矿井通风系统可靠性影响因素分析的基础上,分析了通风网络单元模型,并确定了基于神经网络算法的通风系统可靠性预计方案;根据通风系统可靠性预计因素确定了可靠性预计神经网络的算法构型及各层神经元参数,通过对神经网络预计模型的仿真,得到该预计模型仿真结果与实际结果的对比情况,并确定该预计模型的可行性。     

炼铁变电站供配电可靠性分析

电力可靠性指标是衡量电力系统可靠性大小的重要参数。通过最小割集法对炼铁变电站供配电系统进行可靠性分析,发现钳制炼铁系统可靠性的薄弱环节,从而为系统规划运行提供重要的指导意见。     

地下采矿工艺系统可靠性研究

地下金属矿床回采工作过程为一多生产环节串联可修系统。本文应用马尔柯夫随机过程理论，建立地下采矿工艺系统可靠性数学模型，获得系统可靠性指标，对系统进行可靠性分析和评估．     

仪表自动化可靠性问题探讨

本文介绍仪表自动化设计中有关可靠性的问题,其中包括设备选型、方案设计等,并具体阐述可靠性的经济效果和系统可靠性的分析计算方法。     

电柜的热设计

主要阐述了电拒热设计的目的、方法和步骤.结合现代设计制冷技术,提出从电拒设计的初端热设计就必须与机械设计、电气设计同时进行,相互兼顾,制定出合理可行有效的热设计方案,保证整个电器设备系统可靠性.     

露天矿半连续运输系统可靠性研究

在以往的露天矿半连续运输系统可靠性分析中 ,实质上一般进行的只是其中的一部分环节即连续部分的可靠性分析。运用排队理论 ,加上相应的假设 ,提出了对半连续运输系统中连续环节前间断部分可靠性分析的处理办法 ,另外提出在进行半连续系统可靠性分析时还应在间断和连续环节间加上储矿仓环节 ,这样才能真正体现整个半连续运输系统的可靠性分析。     

紫金山金铜矿单斗-卡车开采工艺系统可靠性研究

为提高露天开采工艺的可靠性和适应性,在确保生产能力完成的同时,降低生产成本,对单斗-卡车开采工艺系统可靠性进行分析,建立了单斗-卡车开采工艺系统可靠性模型。以紫金山金铜矿为例,对工艺系统设备故障率和维修率进行统计分析,最终确定开采工艺系统可靠度为0.973,研究成果为紫金山金铜矿工程公司考核管理、设备选型、开采工艺系统布置及生产运行保障提供了重要依据。     

Three-dimensional model of the fibrin(ogen) molecule and fibrin fibril

The paper deals with the three-dimensional model of fibrin(ogen) molecule and fibrin fibril, based on the electron microscopy data on fibrin(ogen) molecule and on fibrin fibril structure, data on symmetry of fibrinogen primary structure, on domain structure of molecule, on location of sites of polymerization and on the data on polymerization mechanism of fibrin.     

Expression of HLA-ABC and -DR locus antigens on human kidney, endothelial, tubular and glomerular cells

The distribution of the major histocompatibility complex antigens on the various cellular structures of the human kidney was analysed by using a modified Staphylococcus aureus Cowan 1 method. Conventional alloantisera and heterologous antisera raised against isolated molecules were used for the HLA-ABC antigens, whereas the HLA-DR (Ia) antigens were detected with heterologous antisera only. The HLA-ABC antigens were expressed on all types of kidney passenger leucocytes, on vascular endothelial cells, and on kidney tubular cells, but not substantially on the glomerular podocytes. The DR antigens were strongly expressed on (a fraction of) the passenger lymphocytes and on the kidney vascular endothelial cells, weakly on the passenger monocytes, but not measurably on the urine-producing apparatus of the kidney--that is, on the glomerular and tubular cells.     

炼钢厂生产管理信息系统的设计与实现

炼钢厂生产管理信息系统包括制造命令管理子系统、生产辅助管理子系统和工艺质量管理子系统.本文从软件工程理论出发,围绕数据库应用系统的开发,结合制造命令管理子系统的具体实现,主要介绍了生产管理系统在Oracle Developer中的设计思想及开发方法.     

电磁场对钢材组织性能的影响

介绍了国内外磁场热处理对钢材组织影响的最新研究结果,并进行了电磁场对相变形核及晶料长大影响的动力学分析。利用自行设计的电磁场装置,在GLEEBL－1500热力模拟实验机上进行了电磁场对形变及随后相变过程影响的实验研究,得到了较为明显的晶粒细化效果。     

Oxidative stress is found in amyloid deposits in systemic amyloidosis

PURPOSE: To investigate a method of diagnosing angiomyolipoma that contains minimal fat. MATERIALS AND METHODS: In six cases of angiomyolipoma with minimal fat, the attenuation on contrast material-enhanced and unenhanced computed tomographic (CT) images, the echogenicity on sonograms, the signal intensity on T2-weighted magnetic resonance (MR) images, and the gross configuration of the lesion were retrospectively analyzed. In 100 cases of renal cell carcinoma, the same parameters were analyzed, and results were compared with those of angiomyolipoma. RESULTS: When compared with the surrounding renal parenchyma, all six angiomyolipomas showed homogeneously high attenuation on unenhanced CT images, homogeneous enhancement on contrast-enhanced CT images, and homogeneous isoechogenicity on sonograms. Of the five angiomyolipomas examined with MR imaging, four were hypointense and one was isointense on T2-weighted images. All six angiomyolipomas protruded from the renal margin. None of the 100 renal cell carcinomas showed homogeneously high attenuation on unenhanced CT images, homogeneous enhancement on contrast-enhanced CT images, or homogeneous isoechogenicity on sonograms. CONCLUSION: In the kidney, homogeneously high attenuation on unenhanced CT images, homogeneous enhancement on contrast-enhanced CT images, and homogeneous isoechogenicity on sonograms are suggestive of angiomyolipoma that contains abundant muscle and minimal fat.     

320MPa级高强度船板表面微裂纹形成原因的分析

采用金相、扫描电镜对320 MPa级高强度船板表面微裂纹的形成原因进行了研究,发现铸坯表面微裂纹是造成板材表面微裂纹的主要原因,并进一步分析了铸坯表面微裂纹的成因。通过铸坯冷、热装对比试验,指出采取堆垛缓冷的措施可以有效降低板材表面微裂纹的产生。     

铸轧带坯晶粒粗大的原因分析及对策

金属结晶时晶粒的大小取决于体积形核率和晶体表面长大线速度的相对大小,形核率与长大线速度的大小主要取决于液相的过冷度。根据影响晶粒度大小的因素分析铸轧带坯产生粗大晶粒的主要原因,提出了控制和细化铸轧带坯晶粒度的对策。     

汽车覆盖件拉延筋的单元模拟试验研究

通过拉延筋基本单元模拟试验，对板料在筋内变形机理、压边力和筋的几何参数对拉延筋束力的影响规律、拉延筋约束力随模具包角变化的规律及板料拉过筋时的变形情况进行了研究，建立了柱延筋约束力计算模型。     

Proliferation and differentiation of human trabecular osteoblastic cells on hydroxyapatite

In order to evaluate whether human osteoblastic cells differentiate normally on hydroxyapatite, we have compared the adhesion, proliferation, and differentiation of human trabecular (HT) osteoblastic cells on synthetic-dense hydroxyapatite and on standard plastic culture. We show here that initial HT cell attachment was 4-fold lower on hydroxyapatite than on plastic after 4 h of culture, and that normal cell attachment on hydroxyapatite was restored after 18 h of culture. HT cell proliferation was similar on the two substrates at 2-8 days of culture, but was lower on hydroxyapatite compared to plastic after 15 and 28 days of culture, as evaluated by DNA synthesis or cell number. HT cells cultured on both substrates produced an abundant extracellular matrix which immunostained for Type I collagen. The levels of carboxyterminal propeptide of Type I procollagen (P1CP) in the medium were lower in HT cell cultures on hydroxyapatite than on plastic. In addition, (3H)-proline incorporation into matrix proteins and the mean thickness of matrix layers were 52% and 26% lower, respectively, on hydroxyapatite compared to plastic after 4 weeks of culture, indicating that the total collagenous matrix synthesized by HT cells was lower on hydroxyapatite. However, (3H)-proline and calcium uptake expressed per cell was higher on hydroxyapatite than on plastic. The results show that human osteoblastic cells attach, proliferate, and differentiate on dense hydroxyapatite with a sequence similar to that of plastic. However, the growth of human osteoblastic cells is lower on hydroxyapatite in long-term culture, which results in a reduced amount of extracellular matrix, although matrix production per cell may be increased.     

Effects of ionizing radiation on cartilage: emphasis on effects on the extracellular matrix

In this report, we review data dealing with radiation effects on cartilage. More specifically, we emphasize on alterations caused in the extra-cellular cartilage matrix. Although radiation studies predominantly describe the effect on the structure of DNA and on the mitotic activity of cells, alterations caused by the effect on the non-mitotic activity can also be important. Cartilage, having an extracellular matrix composed of 2 major components, aggrecan and collagen, provides a good model to study this kind of radiation effects. The following topics concerning literature data are summarized: effects on the amount of matrix synthesized, effects on the activity of certain enzymes and effects on the structure and morphology of the matrix. Some new findings concerning the radiation effect on the size distribution of aggrecan-aggregate populations, de novo synthesized by chondrocyte cultures, either derived from calcifying or from non-calcifying cartilage, are given.