弯曲管道内流量压差关系的研究

本文从分析弯曲管道内水流的运动规律出发，对压差的形成及计算、流量与压差的关系进行了理论研究。通过对试验实测资料的统计分析，研究了利用弯曲管道水流压差测量流量的实用方法，得出了规律性的有价值的结果。     

二冲程汽油机扫气过程多维数值模拟

为揭示二冲程汽油机扫气过程的特点,对倒拖工况下二冲程汽油机的气缸,扫气道和排气道内的流场进行了多维数值模拟,计算结果与实验结果表明,曲轴箱与排气道之间的压差对扫气道的流速有决定性的影响。计算发现,在扫气过程中出现双环涡和滚涡,且滚涡一直持续到上止点附近。     

柴油机螺旋进气道的三维造型设计

螺旋进气道的设计是个难点，使用传统的方法很难对其进行准确的描述，也难以对气道流动特性进行精确研究．通过确定螺旋进气道的主要设计参数，进行螺旋进气道的计算机三维造型设计，可以实现螺旋气道的精确造型、以气缸直径102mm的直喷式柴油机的螺旋进气道为例，使用Pro／E对其进行了三维造型设计，并将三维模型载入Fluent中进行仿真计算，得到的计算值与试验值基本一致．结果表明：计算机构造的三维模型能很好地模拟螺旋气道，这为研究螺旋气道提供了新的方法．     

间喷式柴油机缸内压力精确测量及放热率计算

提出了一种间喷式柴油机缸内压力精确测量的新方法,即直接测量主副室的压差．对压力测量结果和放热率计算结果作了分析和对比,结果表明,用此方法测得的压力及压差具有更高的精度,对提高放热率计算精度有明显好处．     

缸内三维流场的测量及旋流形成

1.前言缸内空间三维流场实测是解决旋流预测的关键,是目前内燃机界的重要研究课题之一。气道稳流吹风试验是这项研究中的主要手段,其主要目的在于:a.判断不同气道结构的缸内流动形态及湍流特性;b.提供预测模型的边界条件;c.提高稳流试验结果,预测旋流的精度。在稳流吹风试验台上,将热线探针置于透明气缸内测量瞬态变化的湍流三维流场。从频响、干扰流场及信号处理等要求来看均是适合的。其困难在于不能判断方向,必须附加适当的探明方向的可视化方法。作者应用热线风速仪单线探针及自制的丝线网格示踪装置,实现缸内三维流速测量。并根据动量守恒定律阐明旋流形成原理,分析计算了平均速度的分布特性及进气过程的旋流强度。2.缸内旋流的生成     

柴油机旋流气道的稳流试验

本文对在稳流试验台上评定气道产生涡流能力的两种方法,即风速仪法和测矩仪法,进行了广泛的对此试验,并用五孔探针测出了气缸内的空间流场,证实了测矩仪法的正确性,以及分析了风速仪法产生误差的原因.此外,还对气道性能的评定指标作了新的约定.     

水平管内水-胶凝原油两相管流微压差测量方法探讨

准确测量压差是模拟试验研究高含水低温条件下水-胶凝原油在水平管路中的流动特性的关键,但有关温度低于原油凝固点时胶凝原油水力悬浮输送微压差测量方面还没有见到相关报道。分析了水-胶凝原油微压差测量存在的几个问题。在对比分析各种压差变送器测试原理的基础上,针对水-胶凝原油两相流压差信号波动频率低、波动幅值小等特点,选用电容式压差变送器进行水平管内水-胶凝原油两相流微压差测量;并根据模拟试验中被测压差要求的量程、精度和压差信号频率确定了设备的具体型号。对于影响测量准确度的取压口位置、导压管安装方式和仪表防堵防腐等问题,提出具体的解决方案。     

基于LuGre摩擦模型的气缸摩擦力特性实验

为准确测量气缸的实际摩擦力,建立基于伺服电机速度控制的气缸摩擦力测试台,以一无杆气缸为例对其在不同气压、速度下的摩擦力进行测试分析,提出基于LuGre摩擦模型的各个动态和静态参数辨识和建模方法,并进一步研究供气压力和两腔压差对各个参数的影响.研究结果表明,被测气缸的库仑摩擦力、黏性摩擦系数和最大静摩擦力随着供气压力、两腔差压增大而变大;动态参数则与气压关系不大.     

基于SVM和相干平均去噪的大坝位移检测方法

在测量大坝、桥梁等建筑物的形变过程中，常需要采用微小位移测试技术．传统的测试方法难以实现在成本和维护费用较低、定标过程较为简单的前提下保证较高的测量精度．针对此问题，提出了一种新的基于支持向量机和相干平均去噪的大坝微小位移检测方法．首先通过自行研制的图像采集卡获取测量所需图像，然后用相干平均对图像进行预处理，最后用支持向量机进行进一步去噪，试验结果证明了该方法可以在低成本、低维护费用、定标过程较为简单的情况下使测量精度满足实际要求．     

变离心力场中等截面冷却通道的流量计算和实验研究

本文用数值计算得到的数据集，回归出在变离心力场下，等截面管流由于热阻力引起的变密度流流量减少公式，并用热平衡法在旋转试验台上测量了加热条件下通道内的加热量和平均流速．由实验数据集回归出的流量减少公式与数值计算结果相符．     

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

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