膨胀波纹管通过焊接连接在一起,焊缝的膨胀性能直接决定膨胀波纹管整体的膨胀性能。为了解焊缝的膨胀性能,在介绍手工焊和自动焊2类膨胀波纹管焊接工艺的基础上,利用弹塑性力学及有限元法模拟了?149.2 mm 8字形膨胀波纹管焊缝的膨胀过...膨胀波纹管通过焊接连接在一起,焊缝的膨胀性能直接决定膨胀波纹管整体的膨胀性能。为了解焊缝的膨胀性能,在介绍手工焊和自动焊2类膨胀波纹管焊接工艺的基础上,利用弹塑性力学及有限元法模拟了?149.2 mm 8字形膨胀波纹管焊缝的膨胀过程、分析了焊缝的膨胀性能,并通过膨胀波纹管的试验井试验和现场试验进行了验证。由模拟分析及试验可知:膨胀波纹管膨胀过程中焊缝应力和应变最大点在波谷处的管壁外侧;焊缝和膨胀波纹管本体的应力和应变随内压变化的规律相同,焊缝的应力和应变始终大于膨胀波纹管本体,加压至30 MPa时?149.2 mm 8字形膨胀波纹管及焊缝依然在安全范围内;?149.2 mm 8字形膨胀波纹管采用液压膨胀方式加压至18 MPa即满足机械膨胀要求。研究结果表明,采用现有焊接工艺获得的焊缝满足现场膨胀需求,通过模拟获得的膨胀过程中膨胀波纹管焊缝应力和应变的变化规律与试验结果基本吻合,这对现场应用膨胀波纹管具有一定的指导作用。展开更多
Any computer system with known vulnerabilities can be presented using attack graphs. An attacker generally has a mission to reach a goal state that he expects to achieve. Expected Path Length (EPL) [1] in the context ...Any computer system with known vulnerabilities can be presented using attack graphs. An attacker generally has a mission to reach a goal state that he expects to achieve. Expected Path Length (EPL) [1] in the context of an attack graph describes the length or number of steps that the attacker has to take in achieving the goal state. However, EPL varies and it is based on the “state of vulnerabilities” [2] [3] in a given computer system. Any vulnerability throughout its life cycle passes through several stages that we identify as “states of the vulnerability life cycle” [2] [3]. In our previous studies we have developed mathematical models using Markovian theory to estimate the probability of a given vulnerability being in a particular state of its life cycle. There, we have considered a typical model of a computer network system with two computers subject to three vulnerabilities, and developed a method driven by an algorithm to estimate the EPL of this network system as a function of time. This approach is important because it allows us to monitor a computer system during the process of being exploited. Proposed non-homogeneous model in this study estimates the behavior of the EPL as a function of time and therefore act as an index of the risk associated with the network system getting exploited.展开更多
文摘膨胀波纹管通过焊接连接在一起,焊缝的膨胀性能直接决定膨胀波纹管整体的膨胀性能。为了解焊缝的膨胀性能,在介绍手工焊和自动焊2类膨胀波纹管焊接工艺的基础上,利用弹塑性力学及有限元法模拟了?149.2 mm 8字形膨胀波纹管焊缝的膨胀过程、分析了焊缝的膨胀性能,并通过膨胀波纹管的试验井试验和现场试验进行了验证。由模拟分析及试验可知:膨胀波纹管膨胀过程中焊缝应力和应变最大点在波谷处的管壁外侧;焊缝和膨胀波纹管本体的应力和应变随内压变化的规律相同,焊缝的应力和应变始终大于膨胀波纹管本体,加压至30 MPa时?149.2 mm 8字形膨胀波纹管及焊缝依然在安全范围内;?149.2 mm 8字形膨胀波纹管采用液压膨胀方式加压至18 MPa即满足机械膨胀要求。研究结果表明,采用现有焊接工艺获得的焊缝满足现场膨胀需求,通过模拟获得的膨胀过程中膨胀波纹管焊缝应力和应变的变化规律与试验结果基本吻合,这对现场应用膨胀波纹管具有一定的指导作用。
文摘Any computer system with known vulnerabilities can be presented using attack graphs. An attacker generally has a mission to reach a goal state that he expects to achieve. Expected Path Length (EPL) [1] in the context of an attack graph describes the length or number of steps that the attacker has to take in achieving the goal state. However, EPL varies and it is based on the “state of vulnerabilities” [2] [3] in a given computer system. Any vulnerability throughout its life cycle passes through several stages that we identify as “states of the vulnerability life cycle” [2] [3]. In our previous studies we have developed mathematical models using Markovian theory to estimate the probability of a given vulnerability being in a particular state of its life cycle. There, we have considered a typical model of a computer network system with two computers subject to three vulnerabilities, and developed a method driven by an algorithm to estimate the EPL of this network system as a function of time. This approach is important because it allows us to monitor a computer system during the process of being exploited. Proposed non-homogeneous model in this study estimates the behavior of the EPL as a function of time and therefore act as an index of the risk associated with the network system getting exploited.
