基于简单再生码的带宽感知的分布式存储节点修复优化

分布式存储系统为保证可靠性会采用一定存储冗余策略如多副本策略、纠删码策略.纠删码相对于副本具有存储开销小的优点,但节点修复网络开销大.针对修复网络开销优化,业界提出再生码与以简单再生码为代表的局部可修复码,显著降低了修复网络开销.然而,现有基于编码的分布式容错存储方案大都假设节点处于星型逻辑网络结构中,忽略了实际的物理网络拓扑结构和带宽信息.为实现拓扑感知的容错存储优化,相关研究在纠删码和再生码修复过程结合网络链路带宽能力,建立树型修复路径,进一步提高了修复效率.但由于编码和修复过程的差异性,上述工作并不适合于简单再生码修复.针对该问题,本文结合实际物理网络拓扑结构,将链路带宽能力引入到简单再生码的修复过程中,对带宽感知的简单再生码修复优化技术开展研究.论文建立了带宽感知节点修复时延模型,提出了基于最优瓶颈路径和最优修复树的并行修复树构建算法.并通过实验对所提算法性能进行了评估.实验结果表明,与星型修复方式相比,论文所提算法有效地降低了节点修复时延,提高了修复效率.     

碳纤维片材在桥梁粘接加固工程中的应用

简要地介绍了碳纤维片材及其配套胶粘剂的基本性能入特点，通过介绍碳纤维片材在桥梁工程中的应用，验证了碳纤维片材及其配套胶粘剂的加固效果，在此基础上总结了应用碳纤维片材时的注意事项。     

基于 CATIA的自由曲面重构以及应用

利用CATIA强大的自由曲面设计的功能特点，结合颅骨修复实例探讨了CATIA在曲面重构方面的新应用。     

Study on the heating behavior of Ni-embedded thermoplastic polyurethane adhesive film via induction heating

The heating behavior of nanoscopic and microscopic Nickel particle-embedded thermoplastic polyurethane (TPU) adhesive under induction heating is studied. Different particle sizes and content of Nickel were applied to TPU with varying film thicknesses and output power of the induction heater. From the results, heat generation of the TPU films increased with increases in Nickel content, TPU film thickness, and output power. The heat generation of the Nickel particle-embedded TPU films was in the order of 70 nm > 1 µm > 70 µm > 20 µm in terms of particle size, and this result can be explained by increases in the ratio of eddy current heating to hysteresis heating with increases in particle size.     

Repair of damaged aluminum truss joints of highway overhead sign structures using FRP

An innovative repair technique is introduced for aluminum truss-type highway overhead sign structures, using fibre-reinforced polymer (FRP) sheets. The welded k-joints are typically subjected to excessive fatigue-induced cracking under the effects of wind and moving traffic. The repair technique proposed in this paper utilizes longitudinal FRP layers bonded to the diagonals and wrapped around the main chord to form alternating v-patterns, followed by additional circumferential layers for anchorage. Eight tests were conducted on four full-scale specimens. Weld lines at the junction between diagonals and main chord were ground to simulate a 90% loss of joint strength. After repair, diagonals were loaded to failure in tension. The study showed that full strength of the welded joints was restored using carbon-FRP sheets. Only 70% of joint strength was restored when using glass-FRP. The strengthening technique is particularly sensitive to quality control during installation. A field application using the proposed technique was successfully completed by the New York State Department of Transportation for a cracked aluminum truss over Route 88 in NY State.     

KJC－2型矿山机械工程检修车

ＫＪＣ－２型矿山机械工程检修车是集机械设备状态监测与故障诊断研究实验室和修理车间两大功能于一体的大型自行式设备．本文介绍其基本结构与装备、性能参数、适用范围和使用条件．     

高温高压设备现场修复

介绍了高温高压临氢设备腐蚀表面的现场修复方法。解决了无法移动设备现场预热、热处理及施焊操作等关键工艺,提出了施焊操作中的保护措施。     

尿素合成塔衬里的腐蚀及修复

阐述了尿素合成塔材里腐蚀机理及对腐蚀衬里进行局部更换过程,提出了塔衬防腐措施。     

Opportunity-based age replacement policy with minimal repair

This paper proposes an opportunity-based age replacement policy with minimal repair. The system has two types of failures. Type I failures (minor failures) are removed by minimal repairs, whereas type II failures are removed by replacements. Type I and type II failures are age-dependent. A system is replaced at type II failure (catastrophic failure) or at the opportunity after age T, whichever occurs first. The cost of the minimal repair of the system at age z depends on the random part C(z) and the deterministic part c(z). The opportunity arises according to a Poisson process, independent of failures of the component. The expected cost rate is obtained. The optimal T^* which would minimize the cost rate is discussed. Various special cases are considered. Finally, a numerical example is given.     

Influences of the Welding Heat Input and the Repeated Repair Welding on Ti–3Al–2.5V Titanium Alloy

The primary purpose of this study was to determine the effects of gas tungsten arc welding heat input on the high-temperature tensile properties, toughness, and microstructural features of titanium alloy Ti–3Al–2.5V. The secondary objective was to examine the effect of the repeated repair welding on the properties of the alloy. It was also found that the mechanical properties progressively decreased with increasing the repair welding cycles, especially in the case of the weldment after the first welding repair. It was observed that the sizes of the acicular α' and prior β grain boundaries as well as the volume fraction of the acicular α' phases increased with increasing the welding heat input. In addition, the amount and size of the acicular α' phases were found to increase with increasing the repair welding cycles.