基于STA/LTA的输油管道泄漏检测方法

研究了将微震检测中的STA/LTA方法与负压波检测法相结合,并应用于输油管道泄漏检测的技术方法.根据管道泄漏时产生的负压波波形与微震信号初至的相似性,可利用STA/LTA方法对该特征波形进行准确的提取和捕捉,并通过对比管道首末站检测到该特征波形的时间差,对泄漏点位置进行定位.研究表明该方法可有效识别突变的负压波信号,并减少传统泄漏检测方法中小波变换等信号处理方法带来的计算复杂性.室内实验结果表明,将STA/LTA应用于输油管道泄漏检测具备可行性且能够有效识别负压波信号.      

热阻和热漏对耦合制冷循环性能的影响

建立多级不可逆耦合制冷系统的一般循环模型,探讨热阻和热漏等不可逆因素对其循环性能的影响．以制冷系数为目标函数,对制冷循环系统的性能进行优化分析．导出制冷系数与比制冷率间的基本优化关系,确定最大制冷系数及其对应的比制冷率,并对其它优化性能作了分析讨论．所得结果具有普遍意义,可揭示制冷循环系统的一般性能特性     

信息缺失条件下管道泄漏信号识别研究

在管道泄漏诊断过程中,负压波信息缺失会导致误判或漏判,采用改进奇异值降噪技术对负压波信号进行预处理,以提高定性评判泄漏的准确性。介绍了奇异值降噪技术的基本原理及其改进方法,并利用信号互相关技术对泄漏点位置进行了定量计算,实现了对液体输送管线的泄漏故障诊断。对室内液体管道在泄漏诊断过程中负压波特征明显和模糊情况下的奇异值降噪结果进行了对比。结果表明,相关分析方法对信息缺失条件下负压波信号拐点识别的准确率较高。该方法能突出强噪声背景下的负压波信号,并且使泄漏点的定位精度提高到1.52%。该研究结果也可用于液体管线小泄漏的诊断分析。     

广义相关时延估计方法在漏水检测定位中的应用

广义相关时间延迟估计是解决时间延迟估计的重要方法.文章分析了应用广义相关时延估计方法处理管道泄漏噪声信号时间延迟估计问题.研究了广义相关时延估计方法在管道泄漏信号时延估计应用中的关键技术.计算机仿真结果表明广义相关时延估计方法可以有效的应用于管道漏检测定位中.     

Electrolyte membranes for intermediate temperature proton exchange membrane fuel cell

An overview of intermediate temperature (100–300 °C) proton conducting membrane electrolyte materials for fuel cells is presented in this review. The fuel cells operated in intermediate temperature range could enhance the electrochemical kinetics, simplify water management, and improve impurities resistance. Polyfluorosulfonic acid polymer membrane represented by Nafion, and non-fluorinated arylene polymer membranes represented by polybenzimidazole are the two most widely polymer electrolyte membranes for intermediate temperature membrane. The structure regulation and fillers addition are two effective ways to maintain the conductivity and mechanical properties of membranes at intermediate temperature. Moreover, heteropolyacids, metal pyrophosphates and inorganic membranes also have attracted widespread attention when they operate at intermediate temperature.     

Towards mass applications: A review on the challenges and developments in metallic bipolar plates for PEMFC

The industrial applications of proton exchange membrane fuel cell (PEMFC) technology have attracted tremendous capitals and research attention in the last ten years. However, there are still many bottlenecking problems before the progress triumphs. Among them, a core challenge is the improvement of bipolar plates (BPs). As a key component of PEMFC, the BPs undertake the crucial functions of distributing reactant gases and cooling medium, collecting the electricity generated, exporting waste products, etc. Due to the unique advantages of ultra-thin, high strength, easy-to-mass-produce, etc., metallic BPs have been considered as the promising solution for the automotive and aerospace application scenarios with a strong requirement of power density. However, many challenges remain to be conquered in metallic BPs to fully meet all the requirements in those industrial applications such as corrosion, toxic ion emission and fabrication. The aim of this work is to provide an overview of the important researches in recent years dealing with the most critical problems of metallic BPs before industrial applications. The future studying directions in material and processing methods development are also given towards the wide application of metallic BP PEMFCs.     

热漏对卡诺制冷机性能的影响

在内可逆卡诺制冷循环的基础上，进一步研究热漏对卡诺制冷机性能的影响，结果表明，考虑热漏的影响，可使制冷机的最佳制冷系数与制冷率间的关系与实际制冷机的观测性能相符。     

地面工程中常见的缺陷分析及防治

介绍了地面工程中五种常见的工程缺陷：水泥地面裂缝，水泥楼面裂缝和脱壳，地面起砂，水磨石地面缺陷以及厕浴间渗漏水等，分析了产生的原因，并分别提出了防治措施。     

Understanding of free radical scavengers used in highly durable proton exchange membranes

Lifetime is always one of the core concerns of proton exchange membrane fuel cell, especially in commercial utilization. Membrane failure caused by chemical degradation can lead to crash of the whole fuel cell system. Proton exchange membranes with enhanced chemical durability can be fabricated via the addition of free radical scavengers. Free radical scavengers are a series of compounds that can react with harmful radicals preferentially than ionomers, with the membranes protected. This review presents the free radical scavengers that had been applied to proton exchange membranes. The mechanisms of the additives in scavenging radicals are discussed in detail. Meanwhile, the challenges and drawbacks of free radical scavengers need to be addressed are also highlight.     

基于DSP的供水管道泄漏检测系统的设计

针对目前传统供水管道检测系统的方案系统复杂,软件运行效率不高,造价昂贵等缺点,设计一种新型供水管道泄露检测系统,以DSP TMS320LF2407A为图像处理核心,通过超声波传感器采集管道的背景噪声,转化成电信号后传送给DSP系统进行分析,充分利用DSP丰富的外部接口,用串行或以太网方式送到PC,以达到实时显示显示及报警的作用。设计采用C语言与汇编语言的混合程序完成电路板的程序设计,并通过对蝶形FFT算法的改良,使得运算速度更快,实时性更强。MATLAB的验证结果表明该系统精确度高,稳定性强,适用于城市供水管道的检测和诊断,具有较好的应用前景。