稳态流体管网的灵敏度

引入微分灵敏度和大变化灵敏度的数学原理,导出了它们在稳态流体网络中的计算公式和求解方法,从而在流体网络中当某些分支参数产生微小变化或任意变化时,能分别利用微分灵敏度和大变化灵敏度来反映这些参数变化对网络响应的影响．通过对加热管网算例的比较分析,证明了流体网络中某些参数任意改变后,采用大变化灵敏度分析方法,可以获得网络响应的准确解,网络中m个分支参数的较大变化会引起n个分支流量的变化,将它们对整个网络的影响分开考虑,易于区分开网络系统的故障区域和流量的正常波动区域,有利于评估流体管网的实际特性,实现在线模拟和故障诊断等。     

体循环系统建模与仿真

根据流体网络与电气网络的等效关系,用电流表示血液的流动,用电阻表示血液流动的黏滞阻力,用电容表示血管的顺应性,用电感表示血流的惯性.采用1个时变电容和1个心肌电阻模拟左心室,建立了改进型五阶集总参数体循环系统电路模型.根据人体实际生理状况和临床数据制定模型参数,仿真健康心脏、不同部位病变导致的衰竭心脏的血流动力学特性,探讨了衰竭心脏的仿生控制机理,验证了所建模型的可行性.根据基础电路法列写状态方程,应用MATLAB软件进行仿真.结果表明:改进的左心室模型能全面地反映心脏的工作机理和功能,可以模拟健康状态血液动力学特性,通过改变参数又可以模拟因左心室弹性变化、外周阻力变化、心肌阻抗特性变化分别导致心衰的血流动力学特性.     

人体循环系统的物理分析

心脏是一个血泵,血液是一种流体.心脏收缩所产生的压强驱使血液在血管中流动,实现血液循环的生理功能.对血液循环中血流动力学的真正理解,必须立足于控制流体在静止和运动时行为的物理学基本定律和知识.本文应用一些基本的物理学定律、模型和公式说明物理学在循环系统中的应用.     

基于SIR模型的蠕虫传播流量模型

为了更好地研究在蠕虫传播过程中的流量特征，通过对传统SIR蠕虫模型的不足之处进行分析，提出一个改进的蠕虫传播流量模型，用分层次划分网络拓扑和增加一个“临界”状态模拟网络延迟造成的影响，并在NS2环境中进行了模拟．模拟结果显示，改进的模型能较好地符合实际网络中的蠕虫传播趋势和流量特征．     

赣江尾闾多级分汊河道分流影响因素及联动响应分析

基于赣江尾闾综合整治模型,分析不同试验条件和工程措施下多级分汊河道分流特点,探讨多级分汊河道联动响应规律。试验结果表明:上游来流量、分汊口地形、洲头位置、支流进水口门地形及各支流水面比降对分汊口分流特性将产生不同程度的影响;改变影响某一分汊口分流特性的影响因素,除对该分汊口分流比有影响之外,相邻分汊口将会产生联动响应,使得相邻分汊口的分流特点发生改变。     

人体脑血流问题的并行数值模拟

设计了一套高性能血流动力学数值模拟系统,包括几何模型构建、计算网格生成、流体方程离散和求解以及计算结果可视化和分析等模块.重点介绍流体方程的求解模块,并通过对北京天坛医院提供的1个真实脑中风病例(包括术前和术后)的血流动力学瞬态模拟案例来验证系统的可靠性和效率.模拟结果显示:计算获得的各项参数(包括压力、速度、剪切力等)的分布与临床观察结果基本一致.该系统的并行性能测试结果显示:当模型的网格单元数量为2.12×10~6,CPU核数扩展至128时,系统仍可达到72.43%的并行效率.     

积液型两相流分配器的性能与优化

摘要： 试验研究了带有复杂入口管的积液型两相流分液器在不同干度和质量流量条件下的分液均匀性.结果表明：当干度增大时,分液器的分液均匀性下降;当质量流量增大时,分液器的分液均匀性得到改善;各工况下分液器分液的流体质量流量标准偏差（STD）的平均值为2.80%.同时,对复杂入口管进行了计算流体动力学模拟,提出了一种能够有效降低入口管形式影响的新型双筒体型分液器,并通过试验加以验证.验证试验结果表明,在各工况下,双筒体型分液器分液的STD的平均值为2.36%,比积液型分液器的分液均匀性提高了15.7%.     

心血管流场高质量模拟显示实验

动态流体双折射分析用于显示、测量模拟血液流场切应力精细结构，对３种心血管模型实现了心血管流场的高质量模拟和多种血流信息的同步采集处理，为全面综合研究涉及血流动力学因素的心血管疾病及评估人工心瓣的动态性能提供了新的方法。     

水平井油水分层流速度场数值模拟

依据N-S方程和相应的界面耦合条件,构建了牛顿流体牛顿流体两相流的2层和3层分离模型;用有限差分法和松弛迭代法离散和求解各种模型的方程,并模拟了水平井油水分层流流速场.模拟结果表明:水平井中由于压差作用,黏度相对较小的流体流速比较快,不同分界面高度流量和各相持率差别比较大;3层与2层分离模型模拟结果,除了分界面局部特征有些差异外,整个速度场绝对数值也有较大的不同.     

人体上肢血管系统建模及仿真

为了探讨人体动脉脉搏波中所蕴涵的血流动力学信息,从而预测人体生理病理状态。根据Windkessel模型理论,将血管等效为许多小的串联的弹性管道的模型,建立了一个上肢血管系统的电网络模型。采用Matlab中的Simulink/Simpowersystem模块构建该上肢电网络模型进行仿真试验,对动脉脉搏波进行动态模拟。鉴于高血压和动脉硬化等疾病主要体现在心血管动力学参数的变化上,分析研究了血流动力学参数中外周阻力和血管顺应性对脉搏波的影响。仿真结果与生理实际系统相符,表明该模型具有一定的实用性和有效性。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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