Modulated gravity effects on nonlinear convection in viscoelastic ferromagnetic fluids between two horizontal parallel plates

In this study, the analysis of nonlinear stability with viscoelastic ferromagnetic fluids as working media is performed by finite-amplitude perturbations. The solution of the resulting nonautonomous system of the Lorenz model (generalized Khayat–Lorenz model of four modes) is obtained numerically to measure the amount of heat transport. The effects of elastic parameters, Prandtl number, modulation parameters, buoyancy magnetic parameter, and nonbuoyancy magnetic parameter on heat transport are studied. Heat transport is quantified through the average Nusselt number, which is determined by solving the scaled Lorenz model. As limiting cases of the study, the results of Newtonian, Maxwell, Rivlin–Ericksen fluids are determined. The results obtained have been presented graphically.     

Heat and mass transfer in a MHD non‐Darcian micropolar fluid over an unsteady stretching sheet with non‐uniform heat source/sink and thermophoresis

The effect of heat and mass transfer in a MHD non‐Darcian flow of a micropolar fluid over an unsteady stretching sheet with thermophoresis and non‐uniform heat source/sink is discussed. The fluid is electrically conducting in the presence of a uniform applied magnetic field. The arising nonlinear problem is solved by the Keller box method. The effects of various physical parameters on skin friction, local Nusselt number, and Sherwood number are presented graphically and in tabular form. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21018     

如何认识制动液/水溶液的液态不溶物

一般认为制动液/水溶液中的液态不溶物是矿油。红外光谱发现,其液态不溶物除了矿油外还有其它的化学物质。矿油和这些化学物质是被原料或在生产和使用中带入制动液中的。     

Antisolvent micronization of BSA using supercritical mixtures carbon dioxide + organic solvent

In this work, expanded liquid antisolvent (ELAS) process has been used to micronize bovine serum albumin (BSA) solubilized in water. Carbon dioxide mixtures with ethanol, acetone or isopropyl alcohol, at expanded liquid conditions, have been used as the antisolvent. The effect of process parameters, such as the kind of co-antisolvent and the organic co-antisolvent/water/carbon dioxide mole fraction on the morphology and dimensions of the precipitates, was studied. Changing co-antisolvent and operating conditions, we obtained nanoparticles (with a mean diameter of about 60 nm ± 10 nm), sub-microparticles (with a mean diameter of 470 nm ± 130 nm), microparticles (with a mean diameter of 0.93 μm ± 0.37 μm) and expanded microparticles with an empty core (with a mean diameter of about 9 μm ± 5 μm). Fourier transform infrared analysis on BSA powders revealed that, using acetone as co-antisolvent, no modifications of the protein secondary structure were induced by ELAS processing.     

An inductance-based technique for the measurement of magnetic moment of the magnetorheological fluids

We presented a detailed study of the inductance properties of a MRF-based system with different MRF volume fractions under a magnetic field. The inductance of the system raised firstly and then decreased while the magnetic field kept increasing. We theoretically analyzed the mechanism of the field-induced variation of the inductance and deduced that the magnetic field dependence of the inductance could be represented by the derivative of the magnetic moment of MRF, thus the M–H curves of the MRF could be derived from the inductance measurement proceeded in our work. This method for the magnetization calibration was very convenient and economic for manipulation compared with the traditional magnetization meter techniques and has been proved to be feasible according to the experimental results which showed a satisfactory measurement precision.     

Numerical simulation of viscous fingering of shear‐thinning fluids

The viscous fingering instability of miscible shear‐thinning fluids has been examined using a pseudo‐spectral numerical technique based on the Hartley transform. The instability was studied for a flow in a rectilinear Hele‐Shaw cell, and the shear‐thinning character of the fluids has been modelied using the Carreau equation. New mechanisms of viscous fingering not previously observed in the case of similar Newtonian flow displacements have been identified. These mechanisms, which are reminiscent of the fractal patterns observed in experimental studies, were interpreted in terms of the velocity‐dependent mobility of the flow.     

Electrochemical behaviour of Ti–25Nb–3Mo–3Zr–2Sn biomedical alloy in different simulated physiological environments

The electrochemical corrosion behaviour of biomedical Ti–25Nb–3Mo–3Zr-2Sn (TLM) alloy was investigated in various simulated body fluids at 37±0·5°C utilising potentiodynamic polarisation and current–time curves. The Ti–6Al–4V (TC4) alloy was also investigated to make a comparison. The different simulated body fluids comprised of 0·9%NaCl saline, Hank’s and Ringer’s solution were employed. The effect of heat treatment on the electrochemical behaviour of the TLM alloy was also considered. It was discovered that all the test specimens were passivated once immersed into the simulated body fluids. It was also found that the TLM alloy has poorer corrosion resistance in Hank’s solution, due to the chemical composition of the Hank’s. After different heat treated, the TLM alloy had different phases and microstructure, and the corrosion behaviour of the TLM alloy was different. In this study, after the heat treatment of 760°C/1 h/AC+550°C/6 h/AC, the TLM alloy had better corrosion resistance. Owing to the corrosion resistance of the TLM alloy was influenced by numerous factors, such as microstructure and the chemical composition of electrolyte, the corrosion behaviour of the TLM alloy is complex. By comparing with the corrosion behaviour of the TC4 alloy, the TLM alloy has poorer corrosion resistant than the TC4 alloy under the same conditions. But the current–time curves of the TLM alloy were more stable than these of the TC4 alloy with further experiments, because of the more passivation film on the surface of the TLM alloy.     

努森压缩制冷系统的设计及性能分析

分别以氨、水、R290和R600a为工质设计了努森压缩制冷系统。系统结构尺寸受工质的分子直径和宏观物性影响,其中依靠微尺度热流逸效应工作的努森压缩机设计成由两个功能组组成并采用多级串联形式。根据努森压缩制冷系统的微观与宏观工作机制和系统构建方式建立了性能分析模型。努森压缩制冷系统的运行特性类似于压缩机转速可调的常规蒸气压缩制冷系统,其COP随室内温度升高(或环境温度降低)而增大、制冷量随室内温度升高(或环境温度降低)而减小。综合考虑系统结构、性能、成本等因素,水为工质的努森压缩制冷系统明显优于其它3种工质系统。若按一次能源效率计算,努森压缩制冷的COP与常规蒸气压缩制冷的相差不大,加之其具有可直接利用太阳能和余(废)热资源、且没有运动部件等优点,努森压缩制冷是一种具有发展前景和竞争力的新型制冷方式。     

Characterization of extensional rheological filament stretching with a dual‐mode Giesekus model

A new, simple, formulation that describes capillary thinning as predicted by a two‐mode Giesekus model is derived, and its application in analyzing data from extensional rheometry (capillary thinning) experiments is discussed. An algorithm is presented that can be used to fit the expressions obtained from the Giesekus model to extensional rheometry data. Examples of data fitting are given for an idealized data set, for measurements obtained for aqueous solutions of 6 wt % 900,000 molecular weight polyethylene oxide, and for biological fluids obtained from pitchers of Nepenthes Rafflesiana. Good fits to the data were obtained, with coefficients of determination in excess of 0.98. For each data set, it was possible to calculate values of extensional viscosity and relaxation time for each of the two modes, allowing quantitative comparison of different fluids or of the same fluid as it ages. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2188–2199, 2016