多孔介质中热层滞流中辐射效应和均相–非均相反应的熔化传热（英文）

本文研究了不同厚度多孔介质中的饱和热层滞点流的熔化传热。进一步研究了均相–非均相反应和辐射效应对传热性能的影响。熔融传热和均相反应现象在金属纯化、焊接工艺、电渣熔炼、生化系统、催化和工业中得到了广泛应用。利用同伦过程给出了问题的收敛解。讨论了几个相关参数,速度、热场和浓度分布。本文还描述了摩擦系数和Nusselt数的图解。反应物的浓度由于非均相和均相反应参数强度的变化而降低。由于熔融现象的存在,在较高的辐射参数下,流体温度下降。

MHD stagnation point flow by a permeable stretching cylinder with Soret-Dufour effects

Combined effects of Soret(thermal-diffusion) and Dufour(diffusion-thermo) in MHD stagnation point flow by a permeable stretching cylinder were studied. Analysis was examined in the presence of heat generation/absorption and chemical reaction. The laws of conservation of mass, momentum, energy and concentration are found to lead to the mathematical development of the problem. Suitable transformations were used to convert the nonlinear partial differential equations into the ordinary differential equations. The series solutions of boundary layer equations through momentum, energy and concentration equations were obtained.Convergence of the developed series solutions was discussed via plots and numerical values. The behaviors of different physical parameters on the velocity components, temperature and concentration were obtained. Numerical values of Nusselt number, skin friction and Sherwood number with different parameters were computed and analyzed. It is found that Dufour and Soret numbers result in the enhancement of temperature and concentration distributions, respectively.

具有二元化学反应和活化能的压缩流体的磁流体动力学（英文）

研究了在外加磁场作用下,黏性流体在压缩通道中的运动规律。热量和质量传输过程涉及温度依赖的二元化学反应和修正的Arrhenius活化能函数理论,但是该理论尚未揭示挤压流动机理。在无滑移壁边界条件下,流场、热场和质量场通过无量纲、高度非线性的常微分方程来控制。采用一种收敛性稳定的解析方法求解边值问题。对各种新出现参数的流速场、温度场和流体浓度分布的图进行了详细的研究,获得了表面摩擦、Nusselt和Sherwood数并以图表形式表现。结果表明,流体温度随着占主导地位的无量纲反应速率σ和活化能E的增加而升高。然而,σ和E的增加随着流体浓度的增加而下降。当前研究应用于许多工程和工业过程包括聚合物工业、压缩和注塑成型、润滑系统、纸张的生产、塑料薄膜的成型。在化学工程和地热领域,可以利用磁场来控制核冷却反应、核或化学系统、双分子反应、生化过程和导电聚合物流动。在这些应用的推动下,此研究已得到发展。

Note on characteristics of homogeneous-heterogeneous reaction in flow of Jeffrey fluid

This letter describes the characteristics of homogeneous-heterogeneous re- action in the boundary layer flow of a Jeffrey fluid due to an impermeable horizontal stretching sheet. An analysis is carried out through the similar values of reactant and auto catalyst diffusion coefficients. Heat released by the reaction is not accounted. The exact solution for the flow of the Jeffrey fluid is constructed. The series solution for the concentration equation is derived. The velocity and concentration fields reflecting the impact of interesting parameters are plotted and examined.

Mixed Convective Viscoelastic Nanofluid Flow Past a Porous Media with Soret–Dufour Effects

The present study is carried out to see the thermal-diffusion(Dufour) and diffusion-thermo(Soret) effects on the mixed convection boundary layer flow of viscoelastic nanofluid flow over a vertical stretching surface in a porous medium. Optimal homotopy analysis method(OHAM) is best candidate to handle highly nonlinear system of differential equations obtained from boundary layer partial differential equations via appropriate transformations. Graphical illustrations depicting different physical arising parameters against velocity, temperature and concentration distributions with required discussion have also been added. Numerically calculated values of skin friction coefficient, local Nusselt and Sherwood numbers are given in the form of table and well argued. It is found that nanofluid velocity increases with increase in mixed convective and viscoelastic parameters but it decreases with the increasing values of porosity parameter. Also, it is observed that Dufour number has opposite behavior on temperature and concentration profiles.

Investigations of Viscous Dissipation in Stagnation Point Flow Past a Stretchable Riga Wall: Modern Analysis of Heat Transport

This article scrutinizes the features of viscous dissipation in the stagnation point ?ow past through a linearly stretched Riga wall by implementing Cattaneo-Christov heat ?ux model. Viscous dissipation is carried out in Cattaneo-Christov diffusion analysis for the ?rst time in this letter. As a result of Cattaneo-Christov model, some extra terms of viscous dissipation are appeared in the energy equation. These extra terms of viscous dissipation are missing in the literature. On the utilization of suitable transformations, the equations governing the problem are reduced under the boundary layer approximation into the non-linear and dimensionless ordinary differential equations. Convergent approach is utilized to solve the dimensionless governing equations. The solution thus acquired is used to highlight the effects of emerging parameters on velocity distribution and ?uid's temperature through the graphs. Features of the drag force(or skin friction co-e?cient) are graphically interpreted. It is noticed that the presence of modi?ed Hartman number helps to reduce the ?uid's temperature but enhances the velocity pro?le. Further an enlargement in the value of thermal time relaxation parameter helps to decrease the temperature distribution.

Ag/PEPC/NiPc/ZnO/Ag thin film capacitive and resistive humidity sensors

A thin film of blended poly-N-epoxypropylcarbazole（PEPC）（25 wt.%）,nickel phthalocyanine（NiPc）（50 wt.%） and ZnO nano-powder（25 wt.%） in benzene（5 wt.%） was spin-coated on a glass substrate with silver electrodes to produce a surface-type Ag/PEPC/NiPc/ZnO/Ag capacitive and resistive sensor.Sensors with two different PEPC/NiPc/ZnO film thicknesses（330 and 400 nm） were fabricated and compared.The effects of humidity on capacitance and resistance of the Ag/PEPC/NiPc/ZnO/Ag sensors were investigated at two frequencies of the applied voltage：120 Hz and 1 kHz.It was observed that at 120 Hz under humidity of up to 95%RH the capacitance of the sensors increased by 540 times and resistance decreased by 450 times with respect to humidity conditions of 50%RH. It was found that the sensor with a thinner semiconducting film（330 nm） was more sensitive than the sensor with a thicker film（400 nm）.The sensitivity was improved when the sensor was used at a lower frequency as compared with a high frequency.It is assumed that the humidity response of the sensors is associated with absorption of water vapors and doping of water molecules in the semiconductor blend layer.This had been proven by simulation of the capacitance-humidity relationship.

Surface-type humidity sensor based on cellulose-PEPC for telemetry systems

Au/cellulose-PEPC/Au surface-type humidity sensors were fabricated by drop-casting cellulose and poly-N-epoxypropylcarbazole （PEPC） blend thin films. A blend of 2wt% of each cellulose and PEPC in benzol was used for the deposition of humidity sensing films. Blend films were deposited on glass substrates with preliminary deposited surface-type gold electrodes. Films of different thicknesses of cellulose and PEPC composite were deposited by drop-casting technique. A change in electrical resistance and capacitance of the fabricated devices was observed by increasing the relative humidity in the range of 0-95% RH. It was observed that the capacitances of the sensors increase, while their resistances decrease with increasing the relative humidity. The sensors were connected to op-amp square wave oscillators. It was observed that with increasing the relative humidity, the oscillator＇s frequencies were also increased in the range of 4.2-12.0 kHz for 65μm thick film sample, 4.1-9.0 kHz for 88μm thick film sample, and 4.2-9.0 kHz for 210μm sample. Effects of film thickness on the oscillator＇s frequency with respect to humidity were also investigated. This polymer humidity sensor controlled oscillator can be used for short-range and long-range remote systems at environmental monitoring and assessment of the humidity level.