Pipeline leakage detection and isolation: An integrated approach of statistical and wavelet feature extraction with multi-layer perceptron neural network (MLPNN)

Leakage diagnosis of hydrocarbon pipelines can prevent environmental and financial losses. This work proposes a novel method that not only detects the occurrence of a leakage fault, but also suggests its location and severity. The OLGA software is employed to provide the pipeline inlet pressure and outlet flow rates as the training data for the Fault Detection and Isolation (FDI) system. The FDI system is comprised of a Multi-Layer Perceptron Neural Network (MLPNN) classifier with various feature extraction methods including the statistical techniques, wavelet transform, and a fusion of both methods. Once different leakage scenarios are considered and the preprocessing methods are done, the proposed FDI system is applied to a 20-km pipeline in southern Iran (Goldkari-Binak pipeline) and a promising severity and location detectability (a correct classification rate of 92%) and a low False Alarm Rate (FAR) were achieved.     

爆炸波在饱和土介质中传播时压力变化规律的试验研究

介绍了在Φ900平面波加载器中进行的饱和土爆炸波传播试验,通过试验比较系统地研究了爆炸波在饱和土自由场中的传播规律及其在刚性边界上的反射问题。试验表明饱和土中的气体含量是控制波传播规律的主要因素,在深度方向上自由场应力峰值可能随深度增加,而在刚性边界上荷载反射系数可能>2。对饱和土与非饱和土中波传播规律的区别,在确定饱和土中结构的设计荷载时必须给予极大的关注。     

海原大地震极震区内烈度衰减异常探讨

宁夏海原大地震极震区所存在的南北两侧地震烈度衰减异常及伴随的震害程度差异现象,严格受极震区内黄土微地形地貌、土层厚度、显微结构、工程地质特性和发震构造断裂的控制。上述诸因素与地震波耦合后,达到进一步激化和放大地震能量的效应,导致研究区内黄土强度瞬间丧失,并因之具更高的地震易损性而加重震害。     

Coupling effects of foam ceramics on the flame and shock wave of gas explosion

The coupling of gas explosion flame and shock wave is analyzed. In the gas explosion process, shock wave is affected by the flame directly, and shock wave also induces the flame. Inhibiting explosion can be achieved by the interference between the flame and shock wave propagation. If the coupling effects can be damaged, the adverse effects caused by the explosion should be mitigated and controlled. According to the structure characteristics of foam ceramics, the coupling effects mechanism of ceramic foam on gas explosion flame and shock wave is researched. When the explosion goes through the structure of foam ceramics, the flame can be quenched and the shock wave be attenuated. After the flame is quenched, the supply of precursor shock wave energy is cut off. Due to lack of energy supply, the destructive effects of blast wave will be reduced effectively. Coupling effects of the flame and shock wave can be damaged by the special structure of foam ceramics. Studies suggest that a certain function to represent the structure characteristics of foam ceramics must exist. For a certain material of foam ceramics, the sure porosity δ and the pore diameter d also can be get, which is the key to research and develop foam ceramic suppression technology of gas explosion.     

煤与瓦斯突出冲击波及瓦斯气流所致伤害研究

为揭示煤与瓦斯突出过程中冲击波及瓦斯气流传播特性,针对这种突出做功随瓦斯压力、煤的普氏系数和煤的放散初速度变化的特征,运用气体动力学理论,建立冲击波超压、冲击瓦斯流速度与传播距离以及煤层瓦斯压力等参数的关系,计算不同超压下瓦斯气流传播伤害的范围。理论计算与现场测试结果表明,突出冲击波属惰性弱冲击波;波阵面上的超压传播伤害距离与突出时瓦斯膨胀的强度、巷道断面及巷道壁面的摩擦力和局部阻力等因素有关;冲击产生的高压瓦斯气流是造成巷道内大量人员窒息伤亡的主要诱因;突出能量瞬间释放没有补给,冲击波及瓦斯气流会在巷道阻力等因素作用下迅速衰减。     

表面裂纹对Rayleigh波的滤波特性分析

摘要表面裂纹是危害很大且普遍存在的一种缺陷,严重影响到特种设备的安全运行。对表面裂纹尺寸的测量一直未得到很好的解决,由于Rayleigh波能量主要集中在深度一个波长的范围内,当传播过程中和裂纹相互作用时,其频谱会发生变化,一部分高频波将会被吸收,吸收频率的大小与裂纹的深度密切相关。此时裂纹起了一个类似低通滤波器的作用,这点对于裂纹深度检测具有指导意义。     

开敞空间可燃气云爆炸冲击波超压及灾害动力响应研究评述

为了进一步梳理和分析开敞空间可燃云爆炸冲击波超压传播规律及灾害动力响应方面的各项研究成果,推进可燃气体爆炸安全防控,减少人员伤亡和经济损失。在分析现有研究的基础上,总结开敞空间可燃气云爆炸冲击波超压传播规律及灾害动力响应研究等方面存在的不足,提出开敞空间多元混合气体爆炸冲击波超压传播规律研究、多影响参数下可燃气云爆炸冲击波超压传播规律定量分析、基于可燃气云爆炸冲击波超压作用下的承载体动力响应等未来研究的关键技术问题。     

地面运动转动分量的合成方法

假设近场地面运动由体波产生（忽略面波的影响）,根据弹性半空间的平面谐波理论,提出了利用平动分量加速度记录合成地面转动加速时程的方法。该方法考虑了由于实际介质的不均匀性而产生的地震波频散现象。     

WIND GENERATED WAVES IN LAKE OKEECHOBEE1

ABSTRACT: The study of wind generated waves is important because waves affect sediment resuspension in lakes. Measurements of wind velocity and wave elevation were made at three different stations in Lake Okeechobee. Significant wave heights were computed using a direct count from the recorded data, and verified by the root-mean-square value approach. The correlation between wind stress and significant wave height also was analyzed. The data revealed a strong correlation. In addition to field measurements, a Boussinesq-type wind-wave model was developed to simulate wind-generated, long-propagating waves. This model included the effects of wind stress and bottom viscous dissipation. Wave elevation and velocity field were evaluated numerically. A six-day simulation using 1996 wind data was conducted. Simulated significant wave heights were found to agree reasonably well with measured values. A predictive wind-wave model provides information about wind generated waves, which is used to compute bottom shear stresses required for sediment resuspension studies.     

超声波降解水溶液中叔丁醇的研究

研究了超声场降解水溶液中叔丁醇的行为，并探讨了反应动力学模式。实验表明．在本实验条件下超声波降解叔丁醇能够达到较好的降解效果。叔丁醇的去除率随着超声辐射时间的延长而提高，在频率为20kHz、功率为1500W的超声场下，作用80min能够达到90％左右的去除率。反映体系的降解速率随着反应温度的提高而升高，随着初始浓度的增大而降低：反应体系的pH值对叔丁醇的降解率影响不大：溶液中溶解气体的种类对降解效果有一定影响。反应速率常数按照由快到慢的顺序为ko2〉k未作处理〉kN2。在一定的初始浓度条件下，超声波降解叔丁醇的反应符合假一级反应动力学模式。