一种云计算环境下的安全模型

本文针对当前流行的云计算技术,分析了其所面临的安全问题。以中国墙模型(简称BN模型)为基础提出了保护云端服务器私有云中敏感数据完整性和保密性的CCBN(cloud computing BN)模型,并给出了该模型的基本原理和在云环境中应用该模型的配置方案。     

REINORCING THEORY AND TECHNIQUE OF SLOPE EXCAVATION

Ａｆｔｅｒａｓｅｒｉｅｓｏｆｌａｒｇｅｓｃａｌｅｍｏｄｅｌｌｉｎｇｔｅｓｔ，ｔｈｅｏｒｅｔｉｃａｌａｎａｌｙｓｅｓａｎｄｄｉｇｉｔａｌｍｏｄｅｌｌｉｎｇａｎａｌｙｓｅｓｏｆｓｌｏｐｅｅｘｃａｖａ－ｔｉｏｎｉｎｃｏｍｐｏｓｉｔｅｓｏｉｌｂｅｉｎｇｒｅｉｎｆｏｒｃｅｄｗｉｔｈｓｔｅｅｌｂａｒｓ，ｔｈｅｐｒｏｐｅｒｔｙａｎｄｂｅａｒｉｎｇｃａｐａｃｉｔｙｏｆｃｏｍｐｏｓｉｔｅｓｏｉｌｓｌｏｐｅｗｅｒｅａｎａｌｙｚｅｄｓｙｓｔｅｍａｔｉｃａｌｌｙ．Ｔｈｅｒｅｉｎｆｏｒｃｉｎｇｔｈｅｏｒｙｆｏｒｓｌｏｐｅｅｘｃａｖａｔｉｏｎｗａｓｓｏｐｕｔｆｏｒｗａｒｄ．ｔｈａｔｉｓ，ａｃｔｉｖｅｒｅｔａｉｎｉｎｇｓｔａ－ｂｉｌｉｔｙｍｅｃｈａｎｉｓｍ，ａｎｄｒｅｉｎｆｏｒｃｉｎｇｔｅｃｈｎｉｑｕｅｆｏｒｅｘｃａｖａｔｉｏｎｓｌｏｐｅｗｉｔｈｓｔｅｅｌｂａｒｓ．     

冻结管断裂处理及冻结测温研究

介绍了绑双楼西风井冻结管断裂原因和处理方法，分析了套管处理后冻结壁温度场发展规律，实践证明，以此推断得新开挖条件和时间是可行的。     

塔里木盆地富满油田二叠系玄武岩井壁稳定技术研究及应用

塔里木盆地富满油田二叠系普遍发育有玄武岩,玄武岩段钻进易发生井壁失稳,引起卡钻等井下故障复杂,影响了在该区块钻井时效和经济效益。通过对二叠系玄武岩进一步结构特征研究、易垮井地震相态特征及实钻特征研究、理化特性、地应力、坍塌压力研究,确定引起井壁失稳的原因。根据该区块现场实钻资料及井壁失稳处理经验,从强化钻井液封堵性、控制滤失量、提高钻井液抑制性、携岩能力、密度优选、控制工程参数等几个方面给出避免二叠系玄武岩井壁失稳的处理建议。研究成果在AM3井应用成功,效果显著,对指导富满油田二叠系玄武岩钻进具有一定的指导意义。     

沉箱式护岸的新型结构

本文通过已运用几年的工程实例,介绍沉箱式预制构件护岸的设计和施工方法。这种结构的优越性是;结构轻巧,造型美观,占地较少,简免施工围堰和基坑排水,从而能缩短工期,降低工程造价。这一经验,可因地制宜地在江、河、湖、海滨的护岸工程中推广应用。     

锯槽成墙法在蛤蟆通水库防渗中的应用

锯槽成墙法是一种建造地下截水墙的新技术，本文主要介绍应用锯槽成墙法在蛤蟆通水库建造地下水防渗墙的施工工艺，实践证明，采用该技术建造的地下防渗墙具有墙体连续，厚度均匀，适应变形能力强，施工效率高及成本低等优点。     

基于材料损伤的水电站厂房上部结构地震易损性分析

水电站厂房上部钢筋混凝土框架-剪力墙结构在地震中易遭受破坏,基于材料损伤提出了上部结构抗震性能的评估方法,并采用有限元方法和增量动力分析法对厂房上部结构的地震易损性进行了分析.结果表明:水电站厂房上部结构主要的震损为墙柱的开裂以及混凝土保护层的剥落,核心区混凝土的压损伤较小,厂房上部结构具有较高的抗震安全储备,发生严重...     

Dynamic Collapse Mechanisms in Metal Foam Expansion

The study provides insight into decomposition of titanium hydride as foaming agent for powder metallurgically produced aluminum foams. Decomposition is characterized using thermal and kinetic analysis, allowing prediction of decomposition reactions. Such predictions are made for various time–temperature cycles, which are experimentally evaluated in parallel foaming experiments. A new explanation of foam collapse is derived from the results, which interprets hints at a maximum gas release rate, limiting maximum expansion, in terms of the existence of a maximum cell wall stretching rate and expanding foam can sustain. Thus a dynamic collapse criterion is added to existing static ones.     

Computational fluid dynamic simulations of image-based stented coronary bifurcation models

One of the relevant phenomenon associated with in-stent restenosis in coronary arteries is an altered haemodynamics in the stented region. Computational fluid dynamics (CFD) offers the possibility to investigate the haemodynamics at a level of detail not always accessible within experimental techniques. CFD can quantify and correlate the local haemodynamics structures which might lead to in-stent restenosis. The aim of this work is to study the fluid dynamics of realistic stented coronary artery models which replicate the complete clinical procedure of stent implantation. Two cases of pathologic left anterior descending coronary arteries with their bifurcations are reconstructed from computed tomography angiography and conventional coronary angiography images. Results of wall shear stress and relative residence time show that the wall regions more prone to the risk of restenosis are located next to stent struts, to the bifurcations and to the stent overlapping zone for both investigated cases. Considering a bulk flow analysis, helical flow structures are generated by the curvature of the zone upstream from the stent and by the bifurcation regions. Helical recirculating microstructures are also visible downstream from the stent struts. This study demonstrates the feasibility to virtually investigate the haemodynamics of patient-specific coronary bifurcation geometries.