弯管流量计的研究与开发

弯管流量计是根据流体流经弯管时具有离心力的原理进行和开发的一种新型流量计。用它进行流量测量时，测量管道内无可动部件，无附加的压损，并可测脏污介质的流量。由它组成的含砂含水原油弯管流量计量装置，解决了油田含砂油水两相流的测量难题。本文讨论了弯管流量传感器的基本公式和流量系数，取压位置及取压孔直径的确定方法以及现场使用的管道条件，介绍了测水介质时的准确度和量程比，并对测油水两相流时与腰轮流量计的现场…     

应用弯管流量计测量不同介质流量的方法及其管路布置原则

对应用弯管流量计如何正确测量管道中不同介质的流量，不同管路状况下提高差压测量精度的问题进行了探讨，旨在推动弯管流量计在工业流量测量领域的应用．     

90°弯管流量计的特性

弯管流量计以其无附加压损、可测脏污介质、结构简单、成本低廉等特点逐渐引起人们的重视。本文介绍了弯管流量计的工作原理。研究结果表明，弯管流量计的精度可达到１．０级，流量系数与弯管的几何尺寸和取压位置有关。每个弯管流量计的流量系数须经过实际标定。测双向流时，正、反向流量系数要分别标定。     

90°弯管流量计的特性

弯管流量计以其无附加压损、可测脏污介质、结构简单、成本低廉等特点逐渐引起人们的重视.本文介绍了弯管流量计的工作原理.研究结果表明,弯管流量计的精度可达到1.0级,流量系数与弯管的几何尺寸和取压位置有关.每个弯管流量计的流量系数须经过实际标定.测双向流时,正、反向流量系数要分别标定.     

差压流量计量程修改方法探讨

工程设计时的流量计量程和实际运行时的流量常有偏差,为减少计量设备更换带来的诸多问题。通过计算差压流量计的流量系数变化值,来判断其流量计量程调整后的偏差,若偏差不影响正常计量,则分别调整差压和量程,改善差压流量计的计量的可靠性。     

弯管流量计流量系数的试验研究

提出了弯管流量计的理论公式及其流量系数的理论，在大量试验的基础上对影响弯管流量计流量系数的诸因素如：雷诺数、弯管的几何形状、上下游直管段长度、取压孔方向、弯管的管壁粗糙度以及二次流等进行了分析，从而丰富了弯管流量计的理论和设计。     

浅析弯管流量计的特点

浅析弯管流量计的特点王玉东（机械系）１弯管流量计的工作原理弯管流量计也是一种差压式流量计，但其差压的产生与传统流量计（如孔板、喷嘴、文丘里管等）有根本的区别。传统流量计是缩流型差压流量计，而弯管流量计不是。简单地说，当流体流过弯管时，由于弯管的约束作...     

基于科氏流量计和PSO-SVM的气液两相流测量研究

科氏质量流量计测量单相流具有很高的精度,但在气液两相流工况下,科氏流量计测量性能下降,质量流量测量误差急剧增加．为减小测量误差和量化气体体积分数,本文对液相质量流量测量量程0～1 000 kg/h的科氏流量计,结合差压变送器,进行了含气率0～30%的气液两相流实验,并设计了基于粒子群优化算法-支持向量机(PSO-SVM)数据驱动的质量流量修正和含气率预测模型．PSO算法提高了模型构建的速度与预测精度．其中,差压可提供流动形态、相含率等信息,是模型的重要输入变量,包含该变量构建的模型对质量流量修正的相对误差为±1.5%,预测含气率的绝对误差为±3%．由于差压变量需外接差压变送器获取,存在安装不便、空间受限的问题．为实现一体化测量,利用科氏流量计自身动态信号来替代差压变量,并保证模型精度在可接受范围内．结合实验数据分析,设计了另外一种去除差压变量、输入变量完全基于科氏流量计自身信号的两相流测量模型．采用质量流量测量值方差替代差压,修正质量流量,对含气率预测设计了两级SVM模型,将质量流量修正的绝对偏差作为含气率预测模型的输入,以替代差压．结果显示,该模型对质量流量修正后的相对误差为±2%,...     

弯管流量计标准化

依据弯管流量计的工作原理，提出弯管流量计的标准化工作重点是流量计硬件结构尺寸的标准化问题。并介绍了在严格保证弯管流量计的特征结构尺寸弯径比(R／D)一致的前提条件下，通过实验确定相同管径的多个流量计的流量系数α值，其性能具有很好的一致性；再通过对不同管径流量计的实验比对，发现了流量系数随管径减小而相应增大的对应关系。从而证实了硬件结构尺寸的确定可作为这种流量计标准化工作的首要问题。     

V锥流量计超量程使用的处理方法

V锥流量计是2000年左右才在国内出现的流量计,V锥流量计是一种通过节流取差压以反映流量大小的节流装置.中冶京诚(营口)中试基地90%的煤气流量测量使用V锥流量计计量.通过对制气区域消耗煤气总管V锥流量计FE-2732超量程使用的实际情况进行理论分析与计算,提出一套解决流量计超量程问题的具体方案:即在保证测量精度的前提下,不更换V锥流量计,使其继续可以对流量进行准确测量.此方案实际应用于制气区域生产现场已有一年之久,用户反映良好,使用情况令人满意.并已经推广到其他存在类似问题的V锥流量计上.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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