天然气输气管道泄漏因素分析

"十五"期间是我国经济建设持续发展的重要阶段。天然气作为清洁的新兴能源,在我国将得到快速发展,只有避免天然气管道泄漏,加强管理,保障管网的安全和稳定供气,才能对我国天然气产业链的供应安全建设提供强有力的支持。     

事故树分析法在油气输送管道泄漏事故中的应用

泄漏是油气管道输送过程中常见的典型事故,更是引起其他重大后果的主要原因。运用事故树分析法对油气输送管道的泄漏问题进行了侧重性分析,重点探讨了其发生影响模式,得出材料的耐腐蚀性为主要因素,并由此提出了针对性的对策措施,为更好地实施油气输送管道的安全运行提供了更加全面的理论和数据支持。     

Structural,chemical, and electrical properties of Y2O3 thin films grown by atomic layer deposition with an (iPrCp)2Y(iPr-amd) precursor

Y₂O₃ thin films were grown by atomic layer deposition (ALD) through a heteroleptic liquid (iPrCp)₂Y(iPr-amd) precursor at 350 °C. The structural and chemical properties of both as-deposited and annealed Y₂O₃ films at 500 °C and 700 °C are analyzed by atomic force microscopy for variation in surface roughness, X-ray diffraction for crystalline structure, and X-ray photoelectron spectroscopy for chemical states. The as-deposited Y₂O₃ film shows the same crystalline orientation along the plane (222), a stoichiometric state, and minimal hydroxylate formation up to 700 °C. Being the dielectric layer in the metal-oxide-semiconductor capacitor, the as-deposited ALD-Y₂O₃ films with liquid (iPrCp)₂Y(iPr-amd) precursor without any post-deposition annealing show the much lower leakage density than ALD-Y₂O₃ with solid Y(MeCp)₃.     

Passivity analysis of neural networks with two different Markovian jumping parameters and mixed time delays

This paper studies the problem of passivity analysis for neural networks with two different Markovian jumping parameters and mixed time delays utilizing some integral inequalities. The integral inequalities produce sharper bounds than what the Jensen's inequality produces, consequently, better results are obtained. The Markovian jumping parameters in connection weight matrices and discrete delay are assumed to be different in the system model. By constructing a new appropriate Lyapunov-Krasovskii functional (LKF), some sufficient conditions are established which guarantee the passivity of the proposed model. Numerical examples are given to show the less conservatism and effectiveness of the proposed method.     

Performance of Al2O3 particle reinforced glass-based seals in planar solid oxide fuel cells

Glass-based materials are usually considered as excellent seals for jointing adjacent components in planar solid oxide fuel cells, but the uncontrollable crystallization in the glass may cause delamination and micro-cracks in such seals. To solve this problem, Al2O3 ceramic particles were added to a BaO–CaO–Al2O3–B2O3–SiO2 glass system to reduce negative effects caused by crystalline phase on the gas tightness and the joint strength in the seals. At an operating temperature of 750 °C, the glass-based seals with 20 wt% Al2O3 addition (GA80) exhibited extremely low leakage rates (~0.002 sccm/cm under an input gas pressure of 13.6 kPa) and higher shear strength (3.31 MPa). The Al2O3 ceramic addition and the crystalline phase BaAl2Si2O8 reinforced the glass matrix. Further thermal cycle analyses indicated that leakage rates for the GA80 seals remained at around 0.0025 sccm/cm after 10 thermal cycles, which was consistent with minor microstructural change and good interface bonding. Single cell testing with of GA80 seals was performed and the results demonstrated stable electrochemical performance through 6 thermal cycles at an open circuit voltage of 1.16–1.18 V, as well as a power density above 546 mW/cm2 at a current density of 925 mA/cm2. These results showed the high thermal cycle stability of the glass/Al2O3 composite seals in intermediate temperature planar solid oxide fuel cells.     

Stochastic evaluation of leakages through holes in wrinkle networks of composite liners

This paper presents a study on stochastic evaluation of leakages through holes in wrinkle networks of composite liners. The statistical parameters of wrinkles are used as indexes to describe the spatial distributions of wrinkles in a wrinkle network and the wrinkle density is modeled as a random field in the proposed approach, which allows the construction of a database about how wrinkles may be distributed in different conditions and provides input parameters for leakage evaluation at the design stage when the site has not been constructed yet and the aerial image of the wrinkle network (AWN) is unavailable. Statistical analyses were performed on wrinkle geometric parameters and wrinkle density of wrinkles from three sites reported in the literature. The procedures of generating random wrinkle networks (RWNs) based on the statistical parameters of wrinkles are introduced. The proposed approach was applied to typical examples and showed sufficient accuracy when compared to the evaluated leakages based on the corresponding AWNs. Wrinkle density is recommended to be modeled as random field.     

Evaluating leakages through GMB/GCL composite liners considering random hole distributions in wrinkle networks

This paper presents a study on the development of a hydraulic connectivity analysis-based approach for evaluating leakage rates through geomembrane (GMB)-geosynthetic clay liner (GCL) composite liners considering random hole distributions in a GMB wrinkle network. An algorithm for hydraulic connectivity analysis was developed to find the hydraulically connected wrinkles from a wrinkle network, and an explicitly expressed criterion is proposed to define the hydraulic connection between wrinkles under the assumption that only one of the two adjacent wrinkles is possible to be damaged. A Monte Carlo simulation was used to evaluate the probability weighted average of the total leakage through multiple randomly distributed holes considering numerous possible combinations of locations of holes. The proposed approach was applied to typical examples reported in the literature and shows that it can objectively quantify the effect of the hydraulic properties of the liner and overburden pressure on the hydraulic connectivity between wrinkles in a wrinkle network. The proposed approach also allowed assessing the effect of different probabilities of various hole distributions on the calculated leakage, which was demonstrated to be non-negligible, especially when the hole frequency is small.     

Structural and electrical properties of ultra-thin high-k ZrO2 film on nitride passivated Ge(100) prepared by PEALD

The study of ultrathin ZrO₂ films grown on surface passivated germanium substrates by plasma enhanced Atomic Layer Deposition (PEALD) has been carried out. Nitride passivation has been used to form an interfacial layer between ZrO₂/Ge. The ultra-thin ZrO₂ film deposited with thickness of ~5.75 nm and refractive index of ~2.05 as observed through ellipsometry. The Ge3d, Zr3d, N1s and O1s are XPS core level spectra's confirm the formation of GeON and ZrO₂ ultra-thin films. The AFM results show the roughness of deposited films as low as 0.3 nm. The effect of post metallization annealing (PMA) on electrical properties of Au/Cr/ZrO₂/GeON/Ge capacitors has been investigated. The improvement in k value (~38) and an EOT value (~0.5 nm) after PMA on Ge/GeON/ZrO₂ stack has been observed. The flat band voltage and hysteresis of post metallization annealed devices has been reduced as compared to that of without PMA GeON/ZrO₂ stack.     

Experimental investigation of an oscillating circular piston positive displacement flowmeter: II – Leakage flows and wear tests

Experimental data from an oscillating circular piston positive displacement flowmeter are described which focused on leakage flows and wear. This is the second part of a two part paper on the experimental tests, the first part concerned piston movement and pressure loss. In this paper the leakage across the meter is reported for key parameters including: flow rate, liquid density and viscosity, mass of circular piston, surface coating and length of connection pipes. In addition to the average leakage over a period of time, the leakage past a stationary circular piston was measured during a simulated oscillation. Wear tests were run for both stainless steel and carbon pistons to identify the affected areas of piston and chamber.     

改性环氧树脂浆材(SK-E系列)在挡水坝段渗漏处理中的应用

近年来,随着社会的不断进步以及经济的迅猛发展,水利行业获得深化进步,改性环氧树脂浆材由于具有良好的综合性能,在水利工程建设中有着较为广泛的有效应用,其重要性不容忽视。在此,将针对改性环氧树脂浆材(SK-E系列)在挡水坝段渗漏处理中的实践进行简要探讨。