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基于对流效应的寒区路堤块石层临界高度研究 被引量:13
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作者 孙斌祥 徐学祖 +2 位作者 赖远明 汪双杰 章金钊 《中国公路学报》 EI CAS CSCD 北大核心 2005年第4期1-6,共6页
为了研究块石路堤降温效应与块石层高度之间的关系,基于多孔介质自然对流理论和热传导理论引入了表征寒区块石路堤自然对流降温效应的自然对流指数,利用热传导温度分布函数获得了路堤自然对流指数随块石层高度变化的近似公式。分析表明... 为了研究块石路堤降温效应与块石层高度之间的关系,基于多孔介质自然对流理论和热传导理论引入了表征寒区块石路堤自然对流降温效应的自然对流指数,利用热传导温度分布函数获得了路堤自然对流指数随块石层高度变化的近似公式。分析表明:自然对流指数最小值对应于路堤块石层的最小高度,而其最大值对应于路堤块石层的最大高度。另外介绍了一种利用自然对流指数近似公式估算路堤块石层临界高度的方法,并具体给出了算例,最后进行了数值验算。结果表明:通过自然对流指数确定的临界高度可为寒区工程的路堤设计提供参考。 展开更多
关键词 道路工程 寒区块石路堤 自然对流理论 临界高度 热传导理论 数值验算
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土壤溶质迁移理论研究进展 被引量:16
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作者 王全九 《灌溉排水学报》 CSCD 北大核心 2005年第3期77-80,共4页
随着农业发展和环境保护工作的加强,土壤溶质迁移研究成为一个热点问题。国内外学者从不同角度研究了土壤溶质迁移机制,并建立了相关的数学模型。通过综合国内外研究文献的基础上,分析了几何模型、对流弥散方程和传递函数模型方面的研... 随着农业发展和环境保护工作的加强,土壤溶质迁移研究成为一个热点问题。国内外学者从不同角度研究了土壤溶质迁移机制,并建立了相关的数学模型。通过综合国内外研究文献的基础上,分析了几何模型、对流弥散方程和传递函数模型方面的研究进展及存在问题,并探讨了在相关理论方面间内在关系,指出以后研究的重点问题。 展开更多
关键词 土壤溶质 几何模型 对流弥散理论 传递函数
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大气对流边界层中的涡漩结构 被引量:8
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作者 桑建国 《气象学报》 CSCD 北大核心 1997年第3期285-296,共12页
大气边界层中存在尺度从几百米到几十公里的大涡漩运动。它们在边界层中动量、热量、水汽等垂直输送中起重要作用。作者从边界层中对流和上部稳定层中波动相互作用的观点,发展得出大涡结构的对流波动理论。根据此理论,大涡的波谱构成... 大气边界层中存在尺度从几百米到几十公里的大涡漩运动。它们在边界层中动量、热量、水汽等垂直输送中起重要作用。作者从边界层中对流和上部稳定层中波动相互作用的观点,发展得出大涡结构的对流波动理论。根据此理论,大涡的波谱构成主要由上、下层大气中风向、风速、层结以及两层之间的温度跃变等因素决定。本文根据卫星云图和天气资料分析了一次冷空气爆发流经暖洋面上形成云街、对流单体以及它们之间的相互演化的过程,并用对流波动理论,依据各阶段的大气条件计算出它们的波数构成,并得出了垂直速度、辐合带、界面扰动的分布,解释了云街、对流单体的形成。 展开更多
关键词 大气 对流边界层 涡漩结构 对流波动理论
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星载SAR遥感图像反演海洋大气边界层高度 被引量:5
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作者 范开国 黄韦艮 +2 位作者 贺明霞 傅斌 施英妮 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2012年第4期1137-1143,共7页
本研究将边界层相似理论与对流理论应用到具有海洋大气边界层(Marine Atmospheric Boundary Layer,MABL)对流特征的星载合成孔径雷达(Synthetic Aperture Radar,SAR)遥感图像,探讨了星载SAR遥感图像描述海气应力作用下水平扰动尺度变化... 本研究将边界层相似理论与对流理论应用到具有海洋大气边界层(Marine Atmospheric Boundary Layer,MABL)对流特征的星载合成孔径雷达(Synthetic Aperture Radar,SAR)遥感图像,探讨了星载SAR遥感图像描述海气应力作用下水平扰动尺度变化的潜在可能性.针对具有三维对流涡旋Cell和二维水平滚轴涡旋Roll特征的星载SAR遥感图像,反演了中国海海域MABL高度,并与同步实验获取的MABL高度结果进行对比.结果表明,利用具有对流特征的星载SAR遥感图像反演MABL高度是可行的,展示了以高分辨率、大面积观测为特点的星载SAR遥感图像探测MABL的广阔前景. 展开更多
关键词 SAR 海洋大气边界层 相似理论 对流理论
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90年代太阳模型和太阳震荡研究进展(I):太阳模型研究进展(英) 被引量:1
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作者 龚志刚 袁永泉 +2 位作者 W.D ppen 李焱 彭美仙 《天文学进展》 CSCD 北大核心 1998年第4期287-304,共18页
太阳模型的研究是了解太阳整体结构和性质的极为重要的手段。90年代以来太阳模型研究取得了进展。随着MHD及OPAL物态方程的引入,理论上的太阳振荡频率与观测值的差别已大为减小,而考虑湍流频谱分布的局域对流理论和三维流体动力学模... 太阳模型的研究是了解太阳整体结构和性质的极为重要的手段。90年代以来太阳模型研究取得了进展。随着MHD及OPAL物态方程的引入,理论上的太阳振荡频率与观测值的差别已大为减小,而考虑湍流频谱分布的局域对流理论和三维流体动力学模拟结果可对太阳内部对流能量传输过程有更深刻的理解.以前所发现的理论模型与反演结果得到的初始氦丰度的差别已能由扩散过程加以解释,而太阳表面锂丰度亏损问题也可以由扩散过程或早期演化星风来加以解决,太阳中微子问题则似应由粒子物理而不是天体物理来解决。 展开更多
关键词 太阳 太阳模型 太阳震荡 对流理论
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管道煤气热式质量流量计研制及标定技术研究 被引量:4
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作者 李成伟 李朝辉 +1 位作者 戴景民 陈守仁 《哈尔滨工业大学学报》 EI CAS CSCD 北大核心 2002年第3期333-336,共4页
为解决目前燃气计量中仪表下限以下测量精度差或无法计量而造成漏计等问题 ,基于强制对流换热理论和热线风速计原理 ,研制成功了新型气体质量流量计 .仪表中敏感元件和测速加热元件采用了微丝结构 ,测量线路中应用了副电桥技术 ,较大地... 为解决目前燃气计量中仪表下限以下测量精度差或无法计量而造成漏计等问题 ,基于强制对流换热理论和热线风速计原理 ,研制成功了新型气体质量流量计 .仪表中敏感元件和测速加热元件采用了微丝结构 ,测量线路中应用了副电桥技术 ,较大地提高了仪表的灵敏度 ,降低了仪表的死区 .由于煤气介质较特殊 ,影响因素多 ,采用了实流标定 .通过大量实流标定实验 ,分析了煤气导热系数对标定结果的影响 ,并提出了一种新的补偿方法 .经实验测试 ,仪表可做到几乎零下限 。 展开更多
关键词 管道 对流换热理论 热式质量流量计 实验标定 导热系数补偿 煤气计量
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基于相对流面理论的液体火箭发动机泵内部流动计算 被引量:2
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作者 马冬英 雷宗琪 梁国柱 《航空动力学报》 EI CAS CSCD 北大核心 2013年第3期583-590,共8页
应用相对流面理论对某液体火箭发动机离心泵内叶轮机械部件的内部流动进行计算和分析.流面的求解采用流线曲率法.根据不同部件内的流动数值模拟编制了模块化计算程序,使各部件的计算相对独立.不同部件之间采用混合平面法进行处理,将非... 应用相对流面理论对某液体火箭发动机离心泵内叶轮机械部件的内部流动进行计算和分析.流面的求解采用流线曲率法.根据不同部件内的流动数值模拟编制了模块化计算程序,使各部件的计算相对独立.不同部件之间采用混合平面法进行处理,将非定常问题转化为定常问题,简化计算.黏性的影响通过几种损失系数进行修正.数值计算的结果显示诱导轮和离心叶轮增加了液体的压强,而导流通道主要改变了液体的流动方向。 展开更多
关键词 液体火箭发动机 离心泵 对流理论 流线曲率法 混合平面法
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Introduction to the Turbulent Flows Theory--An Axially-Symmetric Non-peaceful Flows
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作者 Tomasz M. Jankowski 《Journal of Mechanics Engineering and Automation》 2014年第4期327-357,共31页
In fluid mechanics, there is lack of turbulent flows theory. The theory of laminar flows is also not completed. Therefore, the aim of this paper is to fill in the gaps in the theory of laminar flow. First time in the ... In fluid mechanics, there is lack of turbulent flows theory. The theory of laminar flows is also not completed. Therefore, the aim of this paper is to fill in the gaps in the theory of laminar flow. First time in the history of fluid mechanics, it shows that the value of the boundary Reynolds number, dividing the flows of Newtonian fluids into laminar and turbulent, can be calculated theoretically. The very existence of this boundary has been known to researchers over a century ago, but all knowledge in this area so far comes only from experimental physics. This paper marks a turning point, as it not only explains the theory of the said phenomenon, but also presents the methodology of its analytical description. It should be noted that the said description refers to the type of flow which is best understood by scientists, i.e., steady axially-symmetric laminar flow through a straight-axis duct of a circular cross-section of the radius R under the action of constant natural gravitational forces. This paper comes second in a series of papers aimed at eliminating chaos from fluid mechanics and replacing it with harmony and mathematical order. 展开更多
关键词 Dualism theory primary motion secondary motion.
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Influence of A Hyperons ^1S0 Superfluidity on the Direct Urca Processes with Hyperons 被引量:1
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作者 许妍 刘广洲 +2 位作者 吴姚睿 王红岩 张峰 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第9期521-524,共4页
In the framework of the relativistic mean field theory (RMFT), the relativistic energy losses of the direct Urea processes with hyperons (Y-DURCA ) for reactions A → p + e + υe and ≡^-→ A+e+υe are studied... In the framework of the relativistic mean field theory (RMFT), the relativistic energy losses of the direct Urea processes with hyperons (Y-DURCA ) for reactions A → p + e + υe and ≡^-→ A+e+υe are studied in neutron stars. We calculate the energy gap of A hyperons and investigate the effects of the ^1S0 superfluidity (SF) of A hyperons on the Y-DURCA processes. The calculated results are in line with the recent experimental data △ BAA ~ 1.01 ±0.20-0.11^+0.18 MeV. The results indicate that the ^1S0 SF of A hyperons exists in most density ranges of happening the two reactions. The theoretical cooling curves are in agreement with observation data. 展开更多
关键词 hyperons superfluidity direct Urca processes with hyperons neutron star
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1996年边界层试验(BLX96)
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作者 Stull,R 戴秋丹 《大气情报》 1997年第4期16-25,共10页
关键词 边界层 积云 对流输送理论 试验
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Two-Quark Condensate Changes with Quark Current Mass
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作者 LU Chang-Fang LU Xiao-Fu +1 位作者 WU Xiao-Hua ZHAN Yong-Xin 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第9期483-486,共4页
Using the Schwinger Dyson equation and perturbation theory,we calculate the two-quark condensates forthe light quarks u,d,strange quark s and a heavy quark c with their current masses respectively.The results show tha... Using the Schwinger Dyson equation and perturbation theory,we calculate the two-quark condensates forthe light quarks u,d,strange quark s and a heavy quark c with their current masses respectively.The results show thatthe two-quark condensate will decrease when the quark mass increases,which hints the chiral symmetry may be restoredfor the heavy quarks. 展开更多
关键词 quark current mass quark condensates QCD sum rule Schwinger-Dyson equation perturbation theory
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Introduction to the Turbulent Flows Theory An Axially-Symmetric Peaceful Flows 被引量:1
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作者 Tomasz M. Jankowski 《Journal of Mechanics Engineering and Automation》 2013年第1期35-52,共18页
This paper introduces to fluid state physics (fluid mechanics) a new interpretation of physical phenomena taking place in a fluid in motion. It introduces the base of a new theory claiming that every flow has its ow... This paper introduces to fluid state physics (fluid mechanics) a new interpretation of physical phenomena taking place in a fluid in motion. It introduces the base of a new theory claiming that every flow has its own internal structure of motion, which is definite organization of motion, rather than a "molecular chaos", known from the fluid statics. The paper introduces the new notion of structures vector fields of power and momentum and shows every Newtonian fluid flows are dual in character. It shows that the flow of Newtonian fluid has a dual character. It demonstrates on models and further in mathematical interpretation of physical phenomena. It introduces, on the one hand, the cycloidal motion model into the fluid mechanics, ad on the other hand an addition to the known, the classical model of Poiseuille laminar motion. The theory of dualism (double nature of physical phenomena) allows the description of selected characteristics of the flow, either by using the theory ofcycloidal motion (semicycloidal), or by using the supplemented theory of laminar motion. The dualism theory is useful to describe each type of flows both, laminar and turbulent. This paper is only an introduction to the theory. It has been assigned number 1. It has been granted a high priority, since it contains basic concepts that will be used in others, following papers of long cycle. 展开更多
关键词 CYCLOID peaceful flow threshold Reynolds number.
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PARAMETER-UNIFORM FINITE DIFFERENCE SCHEME FOR A SYSTEM OF COUPLED SINGULARLY PERTURBED CONVECTION-DIFFUSION EQUATIONS 被引量:5
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作者 CEN Zhongdi 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2005年第4期498-510,共13页
A coupled system of singularly perturbed convection-diffusion equations is considered. The leading term of each equation is multiplied by a small positive parameter, but these parameters may have different magnitudes.... A coupled system of singularly perturbed convection-diffusion equations is considered. The leading term of each equation is multiplied by a small positive parameter, but these parameters may have different magnitudes. The solutions to the system have boundary layers that overlap and interact. The structure of these layers is analyzed, and this leads to the construction of a piecewise-uniform mesh that is a variant of the usual Shishkin mesh. On this mesh an upwind difference scheme is proved to be almost first- order accurate, uniformly in both small parameters. We present the results of numerical experiments to confirm our theoretical results. 展开更多
关键词 CONVECTION-DIFFUSION singular perturbation solution decomposition Shishkinmesh upwind finite difference scheme.
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Pattern Formations in Heat Convection Problems
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作者 Takaaki NISHIDA Yoshiaki TERAMOTO 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2009年第6期769-784,共16页
After Bénard's experiment in 1900, Rayleigh formulated heat convection problems by the Oberbeck-Boussinesq approximation in the horizontal strip domain in 1916. The pattern formations have been investigated by t... After Bénard's experiment in 1900, Rayleigh formulated heat convection problems by the Oberbeck-Boussinesq approximation in the horizontal strip domain in 1916. The pattern formations have been investigated by the bifurcation theory, weakly nonlinear theories and computational approaches. The boundary conditions for the velocity on the upper and lower boundaries are usually assumed as stress-free or no-slip. In the first part of this paper, some bifurcation pictures for the case of the stress-free on the upper boundary and the no-slip on the lower boundary are obtained. In the second part of this paper, the bifurcation pictures for the case of the stress-free on both boundaries by a computer assisted proof are verified. At last., Bénard-Marangoni heat convections for the ease of the free surface of the upper boundary are considered. 展开更多
关键词 Oberbeck-Boussinesq equation Heat convection Pattern formation Computer assisted proof
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Effect of Nonlinear Convection on Stratified Flow of Third Grade Fluid with Revised Fourier-Fick Relations 被引量:1
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作者 M.Waqas M.Ijaz Khan +1 位作者 T.Hayat A.Alsaedi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2018年第7期25-30,共6页
Here thermal dependence conductivity and nonlinear convection features in third-grade liquid flow bounded by moving surface having varying thickness are formulated. Stagnation point flow is considered. Revised Fourier... Here thermal dependence conductivity and nonlinear convection features in third-grade liquid flow bounded by moving surface having varying thickness are formulated. Stagnation point flow is considered. Revised FourierFick relations and double stratification phenomena are utilized for modeling energy and concentration expressions.Mathematical model of considered physical problem is achieved by implementing the idea of boundary layer theory. The acquired partial differential system is transformed into ordinary ones by employing relevant variables. The homotopic scheme yield convergent solutions of governing nonlinear expressions. Graphs are constructed for distinct values of physical constraints to elaborate the heat/mass transportation mechanisms. 展开更多
关键词 nonlinear convection double stratification revised Fourier-Fick relations third grade liquid ther-mal dependence conductivity
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