基于光纤分布式测温的热力管道泄漏定位系统

针对传统热力管道泄漏巡检方式存在的准确度不高、抗干扰能力差等不足，采用光纤分布式测温的方法测量热力管道沿线温度场，当发生泄漏时，管道中的热水或蒸汽会流出并改变泄漏点周围的温度场，系统可以快速捕捉温度变化并实时定位泄漏点。实验检测系统性能指标为温度精度(温度测量值与真实值间的误差)±1℃,空间分辨率≤2 m,目前已成功应用于济宁运河电厂热力管道的检测中，精确地测量了热力管道沿线15 km的温度变化，并成功对一处泄漏行为进行了报警，表明分布式光纤测温系统在热力管道泄漏监测领域具有广阔的应用前景。     

基于改进的经验模态分解方法的热网管道泄漏检测方法

管道泄漏检测技术是保障管道安全生产的重要手段。为了延长管道使用寿命、及时发现和处理管道泄漏事故,通常采用基于声波检测的管道泄漏检测方法。对基于声波检测的热网管道泄漏检测方法进行了研究。对经验模态分解方法进行了分析,针对其存在的端点效应问题提出了一种改进的方法,经过仿真实验和性能对比,验证了方法的有效性和优越性。将这种改进的EMD算法应用在热网管道泄漏检测中,取得了较好的管道信息处理效果。     

基于改进的EMD方法的热网管道泄漏检测方法

管道泄漏检测技术是保障管道安全生产的重要手段.为了延长管道使用寿命、及时发现和处理管道泄漏事故,通常采用基于声波检测的管道泄漏检测方法.对基于声波检测的热网管道泄漏检测方法进行了研究.对经验模态分解方法进行了分析,针对其存在的端点效应问题提出了一种改进的方法,经过仿真实验和性能对比,验证了方法的有效性和优越性.将这种改进的EMD算法应用在热网管道泄漏检测中,取得了较好的管道信息处理效果.     

一种基于气压感知的地下输油管道泄漏监测系统

为了减少石油运输过程中管道泄漏带来的危害，提出一种基于气压感知的地下输油管道泄漏监测方法，基于该方法设计了地下输油管道泄漏监测系统.在输油管道外部包裹双层密闭的塑料外壳，通过测量外壳内部的气压来监测管道是否发生泄漏，利用RS485和NB-IoT网络将报警信息上传至云平台，在PC端和移动端导入地图，实时动态地显示管道发生泄漏的位置.经测试，该系统报警时延小，定位精度高，稳定可靠.     

基于结构化压缩感知方法的管道检测应用研究

根据压缩感知(CS)理论及管道泄漏信号特征,提出管道泄漏信号结构化测量矩阵部分重构(SRMPR)的压缩采样和检测定位方法。该方法以远低于Nyquist采样率对管道泄漏信号同步实现压缩采样,并在部分重构过程中实现泄漏检测定位。与传统相关定位法的仿真实验比较的结果表明,当信号长度为4096时,SRMPR方法比传统相关定位方法精确度提高0.34%;当压缩采样比为5%时,重构信噪比达到30.44dB。本文所提方法能够重构管道泄漏信号重要特征,具有可行性和有效性,可以满足管道泄漏信号实时检测定位的需求。     

基于TDLAS的城市天然气管道泄漏检测系统

将TDLAS(tunable diode laser absorption spectroscopy)技术应用于城市天然气管道泄漏检测及定位.阐述了天然气管道泄漏检测系统的设计原理,介绍了所选用的二极管激光器和多次反射吸收池的特性.实验测量给出了二极管激光器最优的参数设置,得到了系统的最低检测限(2 7×10-6)、线性响应度和系统换气速率(9 3~11 3 次/min),运用数值模拟方法得到了天然气管道泄漏后气体浓度沿管道的分布情况,提出了对天然气管道泄漏定位的方法.     

面向近海管道泄漏检测探究传感器布局的线性动力学计算(英文)

由于缺少管道沿途测量数据,近海管道运输中的泄漏检测问题比陆地流体管道泄漏检测系统更具有挑战性.我们用传输线模型来考虑其线性动力学部分,然后通过有限差分法和偏微分方程拉普拉斯变换来比较传递函数的频域响应.仿真结果表明,有限维模型在低频下可以有效地逼近原始线性模型.由于近海管道监控与数据采集系统缺少传感器,进一步提出了一种新型集成漂流传感器的方法来解决此类型的检测问题并对数据同化框架进行了简要地介绍.     

基于压电传感器的管道泄漏监测仪的研制

提出了通过提高输油管道泄漏信号的信噪比进而提高泄漏检测的可靠性和灵敏度的方法；在定量分析、比较压阻式压力传感器和压电式动态压力传感器各自信号的特征和信噪比的基础上，提出了基于压电传感器的管道泄漏监测方法。阐述了基于压电传感器的管道泄漏监测、定位原理以及基于MSP430F149单片机的管道泄漏监测仪软、硬件设计方法及实现。现场泄漏检测试验结果表明，基于压电传感器的管道泄漏监测仪可以较好地提高泄漏检测的可靠性和灵敏度。     

基于泄漏瞬变模型的管道泄漏检测与定位方法

目前基于模型的管道泄漏检测与定位方法在泄漏瞬态过程中难以稳定定位,造成定位时间过长,无法及时排除泄漏故障.基于特征线法,对管道泄漏瞬变信号的产生和传播进行研究,提出基于泄漏瞬变模型的管道泄漏检测与定位方法.该方法能够在泄漏瞬态过程中进行定位,缩短了模型法的定位时间.通过仿真研究和实际管道的实验验证对该方法的定位时间、定位持续时间、定位精度和噪声的影响等进行分析和讨论.实验结果表明该方法具有快速定位能力,可适用于突发泄漏和缓泄的检测和定位.但该方法的定位持续时间有限,测量信号中的噪声会影响该方法的定位精度、定位稳定性和定位响应速度.     

声发射检测技术在管道泄漏信号识别中的应用

对基于声发射技术的管道泄漏检测这一新方法进行了实验研究。从声发射技术的基本理论入手,分析了声发射技术的特点及检测原理,掌握了声发射信号的分析处理方法及源定位技术,然后进一步将声发射检测技术应用于输油管道的泄漏检测,建立了管道泄漏声发射检测模型,并建立了两种泄漏定位模型。对整个检测系统进行了设计,并进行了管道泄漏声发射实验,对管道泄漏声发射信号的特征进行了分析和提取,为进一步的实验研究及现场应用打下基础。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

正~~