具有正弦波纹的平行板微通道中Jeffrey流体周期电渗流动

研究了具有正弦波纹的平行板微通道中Jeffrey流体周期电渗流动(AC EOF).通过摄动展开法,求解了动量方程,得到了平行板微管道中Jeffrey流体AC EOF速度的近似解析解及其体积流率.在此基础上,研究了相关无量纲参数,如振荡Reynolds数Re_(Ω)、压力梯度G、Deborah数De、滞后时间λ2ω、电动宽度K、正弦波纹的小振幅δ、相位差θ及其波数λ对平均速度u_(m)(t)与平均速度的振幅|U_(m)|的影响.结果表明:Newton、Maxwell和Jeffrey流体之间的速度振幅差异是明显的;Jeffrey流体速度分布受壁面波纹的影响显著,并呈现出明显的波动现象,同时,速度分布还受上下板波纹相位差θ的影响;随着Re_(Ω)的增大,AC EOF速度和u_(m)(t)呈现出快速振荡且振幅逐渐减小的趋势;De数类似于Re_(Ω),使得在外加电场作用下,AC EOF速度更容易产生振荡;同时,AC EOF速度和|Um|随着λ2ω的增大而减小;对于给定的Re_(Ω),相位滞后χ(代表电场和平均速度之间的相位差)随着θ的变化呈明显增大或减小趋势;而χ随着G,λ2ω和θ的增大而减小,但是在较大的λ下(如λ>3.4),χ几乎没有显著变化.

基于Jeffreys先验的参数相关退化可靠性评估

通过Jeffreys无信息先验分布描述了Gamma退化过程中参数的相关性,由贝叶斯模型得到各参数满条件分布,使用马尔科夫链蒙特卡洛(Markov Chain Monte Carlo,MCMC)方法得到参数后验期望估计,最后给出可靠度评价模型。工程实例表明,所得可靠性评估较独立情形更为保守,能够更早地给出产品修理建议。同时,仿真表明,可靠度要求越高,相关与独立情形寿命估计结果偏差越大,0.9999可靠度下偏差率最大可达9.26%。

应用Jeffreys方法计算可靠性参数和始发事件频率的无信息先验

在核电厂概率安全评价(PSA)分析中,有些始发事件频率或设备失效记录在工业界几乎无历史数据。为了计算这些无信息先验的可靠性参数和始发事件频率,可采用Bayesian统计学中的Jeffreys方法。本文阐述了Jeffreys先验和简化的受限无信息先验分布(SCNID)的数学原理,分别导出了Gamma-Poisson模型和Beta-Binomial模型的Jeffreys无信息先验公式和不确定性区间。结合反应堆冷却剂小破口失水事故(SLOCA)实例介绍了如何应用Jeffreys先验计算始发事件频率。结果表明,Jeffreys方法是一种计算无信息先验的有效方法。

极大值与极小值I型分布的Jeffreys无信息先验分布

先验分布的选取一直以来是贝叶斯学派研究的重点,尤其是在无先验信息的情况下如何确定先验分布是贝叶斯学派关心的焦点。文章根据Jeffrey提出的利用Fisher信息矩阵确定无信息先验分布的方法,给出了极大值I型分布与极小值I型分布在不同情况下的无信息先验,为实际模型中的计算提供了便利。

美国作曲家Jeffrey Stolet的互动音乐创作访谈——新媒体时代音乐语言探索(二)

杰弗里·斯托莱特(Jeffrey Stolet),美国著名作曲家、新媒体音乐家和表演艺术家,其作品和创作理念对中国新媒体音乐研究创作产生了极其重要的影响。笔者根据与斯托莱特的特约访谈,以其具体作品和研究成果为基础,探讨了作曲家在现代媒体技术发展中互动音乐的创作方法与新理念。

基于Radon变换和Jeffrey散度的SAR图像变化检测方法

针对多时相合成孔径雷达(Synthetic Aperture Radar,SAR)图像的变化检测,该文采用Radon变换将局部图像投射成投影,用Edgeworth展开来逼近投影的统计分布,比较投影之间的概率分布变化,并引入Jeffrey散度作为两种分布差异的衡量因子,从而计算两个时相SAR图像之间的变化差异图像。投影片断保留了一定量的图像结构信息,弥补了局部概率密度不变时的检测漏洞,而Jeffrey散度具有较好的数值稳定性和对噪声的鲁棒性。最后通过实际的星载SAR图像实验,验证了该文算法的有效性。

Simulation of Variable Viscosity and Jeffrey Fluid Model for Blood Flow Through a Tapered Artery with a Stenosis

Non-Newtonian fluid model for blood flow through a tapered artery with a stenosis and variable viscosity by modeling blood as Jeffrey fluid has been studied in this paper. The Jeffrey fluid has two parameters, the relaxation time A1 and retardation time A2. The governing equations are simplified using the case of mild stenosis. Perturbation method is used to solve the resulting equations. The effects of non-Newtonian nature of blood on velocity profile, temperature profile, wall shear stress, shearing stress at the stenotsis throat and impedance of the artery are discussed. The results for Newtonian fluid are obtained as special case from this model.

Heat transfer analysis in peristaltic flow of MHD Jeffrey fluid with variable thermal conductivity

The effect of an inclined magnetic field in the peristaltic flow of a Jeffrey fluid with variable thermal conductivity is discussed. The temperature dependent thermal conductivity of fluid in an asymmetric channel is taken into account. A dimensionless nonlinear system subject to a long wavelength and a low Reynolds number is solved. The explicit expressions of the stream function, the axial velocity, the pressure gradient, and the temperature are obtained. The effects of all physical parameters on peristaltic transport and heat transfer characteristics are observed from graphical illustrations. The behaviors of θ∈ [0, π/2] and θ∈ [π/2, π] on fluid flow and heat transfer are found to be opposite. Further, the size of trapped bolus is greater for the case of the inclined magnetic field （θ≠ π/2） than that for the case of the transverse magnetic field （θ = π/2）. The heat transfer coefficient decreases when the constant thermal conductivity （Newtonian） fluid is changed to the variable thermal conductivity （Jeffrey） fluid.

平行板微管道内的Jeffrey流体的电磁流动

研究了平行板微管道内线性黏弹性流体的电磁流动,其中线性黏弹性流体的本构关系是由Jeffrey流体模型来描述的。利用分离变量法,在无滑移条件和滑移条件下,求解了线性化的非定常柯西动量方程和Jeffrey流体本构方程,给出了黏弹性Jeffrey流体速度的解析表达式。通过数值计算,分析了无量纲雷诺数Re、哈特曼数Ha、弛豫时间λ1ω和滞后时间λ2ω对速度剖面的影响。结果表明,无量纲滑移长度α增大了流体的速度振幅,滑移条件下流体的速度大于无滑移条件下流体的速度。此外,随着哈特曼数Ha的增加,速度先增加后减少;随着弛豫时间λ1ω的增加,速度也变得越来越大;随着雷诺数Re和滞后时间λ2ω的增加,速度变得越来越小。

Three-dimensional stretched flow of Jeffrey fluid with variable thermal conductivity and thermal radiation

This article addresses the three-dimensional stretched flow of the Jeffrey fluid with thermal radiation. The thermal conductivity of the fluid varies linearly with respect to temperature. Computations are performed for the velocity and temperature fields. Graphs for the velocity and temperature are plotted to examine the behaviors with different parameters. Numerical values of the local Nusselt number are presented and discussed. The present results are compared with the existing limiting solutions, showing good agreement with each other.

MHD three-dimensional flow of Jeffrey fluid with Newtonian heating

The magnetohydrodynamic(MHD) three-dimensional flow of Jeffrey fluid in the presence of Newtonian heating is investigated. Flow is caused by a bidirectional stretching surface. Series solutions are constructed for the velocity and temperature fields. Convergence of series solutions is ensured graphically and numerically. The variations of key parameters on the physical quantities are shown and discussed in detail. Constructed series solutions are compared with the existing solutions in the limiting case and an excellent agreement is noticed. Nusselt numbers are computed with and without magnetic fields. It is observed that the Nusselt number decreases in the presence of magnetic field.

Convective heat and mass transfer in MHD mixed convection flow of Jeffrey nanofluid over a radially stretching surface with thermal radiation

Mixed convection flow of magnetohydrodynamic(MHD) Jeffrey nanofluid over a radially stretching surface with radiative surface is studied. Radial sheet is considered to be convectively heated. Convective boundary conditions through heat and mass are employed. The governing boundary layer equations are transformed into ordinary differential equations. Convergent series solutions of the resulting problems are derived. Emphasis has been focused on studying the effects of mixed convection, thermal radiation, magnetic field and nanoparticles on the velocity, temperature and concentration fields. Numerical values of the physical parameters involved in the problem are computed for the local Nusselt and Sherwood numbers are computed.

Quadratic convective flow of radiated nano-Jeffrey liquid subject to multiple convective conditions and Cattaneo-Christov double diffusion

A nonlinear flow of Jeffrey liquid with Cattaneo-Christov heat flux is investigated in the presence of nanoparticles. The features of thermophoretic and Brownian movement are retained. The effects of nonlinear radiation, magnetohydrodynamic(MHD), and convective conditions are accounted. The conversion of governing equations into ordinary differential equations is prepared via stretching transformations. The consequent equations are solved using the Runge-Kutta-Fehlberg(RKF) method. Impacts of physical constraints on the liquid velocity, the temperature, and the nanoparticle volume fraction are analyzed through graphical illustrations. It is established that the velocity of the liquid and its associated boundary layer width increase with the mixed convection parameter and the Deborah number.

Peristaltic flow of MHD Jeffrey fluid through finite length cylindrical tube

The present investigation studies the peristaltic flow of the Jeffrey fluid through a tube of finite length. The fluid is electrically conducting in the presence of an applied magnetic field. Analysis is carried out under the assumption of long wavelength and low Reynolds number approximations. Expressions of the pressure gradient, volume flow rate, average volume flow rate, and local wall shear stress are obtained. The effects of relaxation time, retardation time, Hartman number on pressure, local wall shear stress, and mechanical efficiency of peristaltic pump are studied. The reflux phenomenon is also investigated. The case of propagation of a non-integral number of waves along the tube walls, which are inherent characteristics of finite length vessels, is also examined.

Darcy-Forchheimer flow of variable conductivity Jeffrey liquid with Cattaneo-Christov heat flux theory

The role of the Cattaneo-Christov heat flux theory in the two-dimensional laminar flow of the Jeffrey liquid is discussed with a vertical sheet. The salient feature in the energy equation is accounted due to the implementation of the Cattaneo-Christov heat flux. A liquid with variable thermal conductivity is considered in the Darcy-Forchheimer porous space. The mathematical expressions of momentum and energy are coupled due to the presence of mixed convection. A highly nonlinear coupled system of equations is tackled with the homotopic algorithm. The convergence of the homotopy expressions is calculated graphically and numerically. The solutions of the velocity and temperature are expressed for various values of the Deborah number, the ratio of the relaxation time to the retardation time, the porosity parameter, the mixed convective parameter, the Darcy-Forchheimer parameter, and the conductivity parameter. The results show that the velocity and temperature are higher in Fourier＇s law of heat conduction cases in comparison with the Cattaneo-Christov heat flux model.

Jeffreys无信息先验分布下参数的Bayes估计

随着Bayes统计学的快速发展,分布族参数的Bayes估计问题越来越多,本文通过两个分布族,得出在Jeffreys无信息先验分布情况下参数的Bayes估计的精确形式,并证明出其结果的可效性.

汉英人称与物称主语使用差异对比——以《边城》及Jeffrey C.Kinkley的英译本为例

受地理环境、思维方式、历史文化、主体客体意识上对立等影响,英语多用物称作主语,汉语多用人称做主语。物称作主语使得整个句子更加客观、委婉、间接,人称做主语使句子更加主观辩证、自然流畅、通俗易懂。《边城》是沈从文的中短篇小说,自问世以来就引起了国内外学者的广泛研究。在英语翻译方面,目前有四种英译本,其中,Jeffrey C.Kinkley的译本最新且最具有研究价值。因此,本文以沈从文的《边城》以及Jeffrey C.Kinkley的英译本为例,提出在翻译时应当根据译入语国家的行文习惯进行主客体的转换,以期译出更加流畅优美地道的译文。

Physical aspects of magnetized Jeffrey nanomaterial flow with irreversibility analysis

This research presents the applications of entropy generation phenomenon in incompressible flow of Jeffrey nanofluid in the presence of distinct thermal features. The novel aspects of various features, such as Joule heating, porous medium,dissipation features, and radiative mechanism are addressed. In order to improve thermal transportation systems based on nanomaterials, convective boundary conditions are introduced. The thermal viscoelastic nanofluid model is expressed in terms of differential equations. The problem is presented via nonlinear differential equations for which analytical expressions are obtained by using the homotopy analysis method(HAM). The accuracy of solution is ensured. The effective outcomes of all physical parameters associated with the flow model are carefully examined and underlined through various curves. The observations summarized from current analysis reveal that the presence of a permeability parameter offers resistance to the flow. A monotonic decrement in local Nusselt number is noted with Hartmann number and Prandtl number.Moreover, entropy generation and Bejan number increases with radiation parameter and fluid parameter.

Peristaltic flow of a heated Jeffrey fluid inside an elliptic duct:streamline analysis

The peristaltic flow of a heated Jeffrey fluid inside a duct with an elliptic cross-section is studied.A thorough heat transfer mechanism is interpreted by analyzing the viscous effects in the energy equation.The governing mathematical equations give dimensionless partial differential equations after simplification.The final simplified form of the mathematical equations is evaluated with respect to the relevant boundary conditions,and the exact solution is attained.The results are further illustrated by graphs,and the distinct aspects of peristaltic flow phenomena are discussed.

Convective flow of Jeffrey nanofluid along an upright microchannel with Hall current and Buongiorno model:an irreversibility analysis

The thermal properties and irreversibility of the Jeffrey nanofluid through an upright permeable microchannel are analyzed by means of the Buongiorno model.The effects of the Hall current,exponential space coefficient,nonlinear radiation,and convective and slip boundary conditions on the Jeffrey fluid flow are explored by deliberating the buoyant force and viscous dissipation.The non-dimensionalized equations are obtained by employing a non-dimensional system,and are further resolved by utilizing the shooting approach and the 4th-and 5th-order Runge-Kutta-Fehlberg approaches.The obtained upshots conclude that the amplified Hall parameter will enhance the secondary flow profile.The improvement in the temperature parameter directly affects the thermal profile,and hence the thermal field declines.A comparative analysis of the Newtonian fluid and non-Newtonian fluid(Jeffrey fluid)is carried out with the flow across a porous channel.In the Bejan number,thermal field,and entropy generation,the Jeffrey nanofluid is more highly supported than the Newtonian fluid.