基于改进Mallat算法及包络线的气阀故障诊断

气阀故障微弱信号特征不明显,常规方法难以通过计算结果来判断气阀状态,且传统Mallat算法存在频率混叠及边界震荡现象,难以提取出气阀故障特征。为此,提出一种结合改进Mallat分解算法及包络线的故障特征提取方法。改进传统的边界处理方式,对信号右边界进行数据延拓,用二阶Volterra模型对延拓信号进行预测,用递推最小二乘法求取预测系数,用非抽样算法对信号进行小波包分解。对分解得到的各频带信号进行奇异值降噪处理,通过奇异熵增量曲线选择降噪阶次,画出信号的上、下包络线,用于提取气阀故障特征。对仿真信号及工程信号的处理表明,用改进的Mallat算法对信号进行分解,消除了边界震荡及频率混叠现象,成功提取了阀片破损的微弱故障特征,取得了良好的效果。     

Relationship between Formation Water Rate, Equivalent Penetration Rate and Volume Flow Rate of Air in Air Drilling

Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper,the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.     

无畸变针孔广角物镜的研究

随着ＣＣＤ探测器的出现，针孔广角物镜得到广泛地应用，由于入瞳在针孔广角物镜的外面，畸变难以矫正，它的应用受到限制。在本文中，详细地研究了利用非球面如何短矫正光学系统中的畸变，并给出光学系统设计的结果和各种像差曲线。     

淮南粉煤灰现状及利用分析

在分析淮南电厂粉煤灰的理化性质以及特点的基础上,研究了粉煤灰带来的环境问题,重点探讨了其在农业领域、材料科学领域和工程领域的利用问题,并对今后应加强的重点研究作了展望.     

结构参数对压裂双弯头冲蚀及流致变形的影响*

双弯头管汇是水力压裂地面高压管汇系统中的关键部件,由于高压大排量携砂压裂液在其中多次强制转向,双弯头管汇长期遭受着严重的冲蚀磨损和流致变形。为改善管件冲蚀磨损状态,从管汇结构参数的角度研究其对冲蚀率的影响。采用计算流体力学(CFD)数值模拟,结合离散相模型(DPM)和流固耦合(FSI)方法,对双弯头结构管汇在工况条件下的流致冲蚀和变形情况进行综合分析,研究双弯头结构参数,如连接直管长度、管道内径及弯头间连接角度对冲蚀和变形的影响。结果表明:随着连接直管长度增加,冲蚀率先减小后变化不大,而结构变形程度逐渐增大,综合考虑冲蚀磨损和结构变形,双弯头之间的连接直管长度宜设计为管道外径的4倍;大口径管道的冲蚀磨损程度更低,但会带来更大的变形,因此双弯头管汇的管内径不宜过大或过小;当2个弯头间的连接角度为0°时,冲蚀和变形程度达到最小。     

基于Modbus/TCP的管道泄漏远程检测系统研究

基于目前迅猛发展的、开放的Modbus/TCP协议技术,设计了管道泄漏远程检测系统总体结构。通过Modbus和Modbus/TCP协议实现了远程监控中心与现场设备之间的数据交换,用C++builder编制了实时多任务的管道泄漏检测软件系统,可对管网进行在线诊断。现场测试结果和实际工业应用证明,基于Modbus/TCP协议实时多任务的管道泄漏远程检测系统误判率为零,并且几乎无漏判;其相对定位误差仅为0.58%。系统运行可靠,移植性好,是一种值得推广的管网泄漏诊断方法。     

柴油机燃烧状况的不解体诊断方法

不解体诊断技术是实现机械设备预测维修的重要手段。对于在油田上广泛使用的动力设备柴油机而言，机械振动法是一种对其燃烧状况进行评估的常用不解体诊断方法。通过对柴油机缸体表面振动信号的分析，根据时域指标的均方值大小及频域指标的频谱分布，可对柴油机气缸的熄火、爆燃等故障进行诊断，从而达到对缸内燃烧状况进行评判的目的。通过实验，对柴油机的爆燃进行了识别，验证了以机械振动法作为不解体诊断法的有效性。     

变载荷齿轮箱状态监测技术研究

目前关于齿轮箱故障诊断的研究成果大都集中在固定载荷工况的齿轮箱故障诊断,与实际生产中的齿轮使用情况大相径庭。为此,借鉴齿轮变工况研究思路,针对齿轮箱在变工况下的信号特征,提出变载荷工况下的齿轮箱断齿故障诊断和状态监测技术思路。利用奇异值分解降噪对齿轮箱振动信号进行预处理,选择啮合齿轮的倍频及其边频为特定频段,以无量纲的脉冲指标和裕度指标作为评价指标,得到齿轮健康状态参数,实现了对齿轮箱的状态监测。最后利用模拟齿轮故障试验台取得了2种转速变负载条件下的故障和正常的振动信号,对齿轮故障诊断和状态监测方法进行了验证。     

输气管道泄漏音波传声特性及泄漏识别

介绍了音波泄漏检测与定位的基本原理,研究了管道泄漏音波的传声特性,利用输气管道泄漏检测平台进行了不同输气压力下不同泄漏孔径的泄漏检测试验,分析了不同条件下的声谱特征。根据管道泄漏音波不同信号特征量建立不同条件下的隐马尔可夫模型,对管道泄漏进行了分类识别。试验分析结果表明,该方法有较好的识别率,隐马尔可夫模型应用于输气管道泄漏识别是可行的,且比支持向量机具有更高的识别准确率。该方法为天然气管道泄漏的进一步研究提供了理论基础。     

Safety prognostic technology in complex petroleum engineering systems: progress, challenges and emerging trends

Oil and gas facilities used in the petroleum industry can be considered as complex dynamic systems in that they require different types of equipment with various causal relationships among components and process variables under monitoring.As the systems grow increasingly large,high speed,automated and intelligent,the nonlinear relations among these process variables and their effects on accidents are to be fully understood for both system reliability and safety assurance.Failures that occur during the process can both cause tremendous loss to the petroleum industry and compromise product quality and affect the environment.Therefore,failures should be detected as soon as possible,and the root causes need to be identified so that corrections can be made in time to avoid further loss,which relate to the safety prognostic technology.By investigation of the relationship of accident causing factors in complex systems,new progress into diagnosis and prognostic technology from international research institutions is reviewed,and research highlights from China University of Petroleum（Beijing） in this area are also presented.By analyzing the present domestic and overseas research situations,the current problems and future directions in the fundamental research and engineering applications are proposed.