Modeling and simulation of a counter-rotating turbine system for underwater vehicles

The structure of a counter-rotating turbine of an underwater vehicle is designed by adding the counter-rotating second-stage turbine disk after the conventional single-stage turbine. The available kinetic energy and the absorption power of the auxiliary system are calculated at different working conditions, and the results show that the power of the main engine and auxiliary system at the counter-rotating turbine system matches well with each other. The experimental simulation of the lubricating oil loop, fuel loop, and seawater loop are completed right before the technology scheme of the counter-rotating turbine system is proposed. The simulation results indicate that the hydraulic transmission system can satisfy the requirements for an underwater vehicle running at a steady sailing or variable working conditions.     

Real-Time Fault Diagnosis for Gas Turbine Blade Based on Output-Hidden Feedback Elman Neural Network

In order to remotely monitor and maintain large-scale complex equipment in real time, China Telecom plans to create a total solution that integrates remote data collection, transmission, storage, analysis and prediction. This solution can provide manufacturers with proactive, systematic, integrated operation and maintenance service, and the data analysis and health forecasting are the most important part. This paper conducts health management for the turbine blades. Elman neural network, and improved Elman neural network, i.e., outputhidden feedback (OHF) Elman neural network are studied as the main research methods. The results verify the applicability of OHF Elman neural network.     

上软下硬地层盾构隧道围岩应力释放率研究

为解决盾构隧道在上软下硬地层中掘进时开挖面应力释放率难以确定的问题，基于一种既有的体积损失率迭代求解应力释放率的方法，依托广州地铁21号线盾构穿越上软下硬地层实际工程，通过数值模拟研究掌子面不同软硬岩比例、不同埋深条件下的应力释放率变化趋势，并结合现场实测资料进行对比分析。研究结果表明： 1）在盾构隧道掘进穿越上软下硬地层分界面的过程中，围岩的初次应力释放率范围基本保持在24%~36%，且随掌子面硬岩比例的增加呈线性增加趋势； 2）相对于围岩条件而言，埋深对应力释放率的影响更小。此外，在盾构隧道穿越上软下硬地层的全过程模拟中，根据围岩变化情况随不同开挖步动态调整应力释放率这一做法较全程取一固定应力释放率值更为合理。     

"以公共交通为导向的开发"理念引导下的成都轨道交通站点综合开发体系框架

在成都市实施轨道交通引领城市发展的战略下,轨道交通站点综合开发是保障轨道交通可持续发展的现实需要及推动城市组织重构、动力升级的有效途径.通过文献研究,借鉴国内外先进城市TOD(公共交通导向开发)经验,总结站点综合开发的理念及先进做法.结合成都实际情况,提出成都轨道交通站点综合开发体系框架.     

酚醛树脂复合材料在轨道交通车辆上的应用

介绍了酚醛树脂复合材料试制的主要原材料、主要设备及仪器、试制流程及测试标准。详细阐述了酚醛树脂复合材料的氧指数、燃烧性能、机械性能、低密度等性能。分析了热压时间、热压温度及生产工艺对酚醛树脂复合材料性能的影响。试验证明,酚醛树脂产品的性能较为优良:热压时间控制在1.1~1.4 h时,复合材料的表面性能良好;热压温度为80~100℃时,可以得到表面质量细腻均匀的复合材料;适当调整生产工艺,可以提高酚醛树脂的产品质量、降低生产成本。     

单片机在无线通讯中的应用

采用可工作于433 MHz频段的无线射频收发模块n RF9E5,通过内嵌8051单片机C语言编程,实现多通道、短距离的数据传输。并在近距离范围内验证了所设计的无线通讯模式的可靠性和准确性。     

Dynamic Behavior of Two Part Towing Cable System During Turning

An improved numerical method is used to simulate the dynamic behavior of a two part towing cable systems during turnings. In U turns and full turns, periodical heave motions are found both for the towed vehicle and for the depressor. Periodic motions of the subsea units and of the cable surface tension are closely related to the turning parameters, such as turning velocity and turning radius. System parameters, such as length of the second cable and the vehicle hydrodynamics, also damp turning instability.     

Vortex-induced vibration of a tension leg platform tendon: Multi-mode limit cycle oscillations

This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, analyzed using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation (lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.     

Some insights in novel risk modeling of liquefied natural gas carrier maintenance operations

This study discusses the analysis of various modeling approaches and maintenance techniques applicable to the Liquefied Natural Gas (LNG) carrier operations in the maritime environment. Various novel modeling techniques are discussed; including genetic algorithms, fuzzy logic and evidential reasoning. We also identify the usefulness of these algorithms in the LNG carrier industry in the areas of risk assessment and maintenance modeling.