Acoustics of Nanodispersed Magnetic Fluids presents key information on the acoustic properties of magnetic fluids. The book is based on research carried out by the author as well as on many ...publications in both the Russian and foreign scientific literature from 1969 onwards.It describes a wide variety of topics, which together lay the foundation of
In the article, magnetization, viscosity and its increment (“magnetoviscous” effect) in a thin near-wall layer of the column of magnetic fluid that oscillates in the tube when applying a strong ...transverse magnetic field are assessed. Calculations were performed using formulae obtained on the basis of two different theoretical approaches. The described technique is of interest for studying magnetophoresis and the processes of aggregation of magnetic nanoparticles.
The findings of the experimental research of a phased air cavity capture in a flat channel with a magnetic fluid located along the axis of the annular magnet influenced by the changing in sign ...magnetic field are discussed. The research was carried out with four magnetic fluids with the magnetic phase concentrations of 1.93%; 2.70%; 4.34%; 9.08%. The analysis of the obtained results is presented within the framework of the electrodynamic model of “low magnetic bodies” based on the development of the system of isolines of the module of the magnetic field intensity. The provided data, first, clarify the conclusions of the previous interpretation of the air cavity capture with an opaque magnetic fluid column, and second, can be useful to solve practical issues of microhydraulics.
Elastic-and magnetic properties of magnetic fluid confined by ponderomotive force in a tube fixed in horizontal position are considered. The system is placed in a strong magnetic field under the ...influence of external static and dynamic perturbations. An experimental setup has been developed. A theoretical basis of the processes of magnetic colloid elastic deformation has been proposed. The values of the static ponderomotive elasticity coefficient and the elasticity coefficient under dynamic action are experimentally determined. The calculations of the saturation magnetization for two magnetic fluid samples, carried out according to the equation containing the dynamic elasticity coefficient, are in good agreement with the experimental magnetization curve. The described method is of interest when studying magnetophoresis and aggregation of nanoparticles in magnetic colloids.
Abstract
When analyzing a 1D time series, it is traditional to represent it as the sum of the trend, cyclical components and noise. The trend is seen as an external influence. However, the impact can ...be not only additive, but also multiplicative. In this case, not only the level changes, but also the amplitude of the cyclic components. In the PCA-Seq method, a generalization of SSA, it is possible to pre-standardize fragments of a time series to solve this problem. The algorithm is applied to the Anderson series – a sign alternating version of the well-known Wolf series, reflecting the 22-year Hale cycle. The existence of this cycle is not disputed at high solar activity, but there are doubts about the constancy of its period at this time, as well as its existence during the epoch of low solar activity. The processing of the series by the PCA-Seq method revealed clear oscillations fluctuations of almost constant amplitude with an average period of 21.9 years, and it was found that the correlation of these oscillations with the time axis for 300 years does not differ significantly from zero. This confirms the hypothesis of the existence of 22-year oscillations in solar activity even at its minima, like the Maunder minimum.
One of the areas for improvement in ITS-90 is studied: the search for a fixed temperature point as an alternative to the triple point of mercury, e.g., the triple point of carbon dioxide. The need ...for this area of improvement arises from the signing in 2013 of the Minamata Convention on Mercury under the auspices of the UN and the avoidance of new measurement instrumentation based on mercury (liquid mercury thermometers, etc.). A cell for implementation of the triple point of carbon dioxide is designed. Methods for producing the triple point of carbon dioxide are introduced and the results of studies of its reproducibility are presented. These studies demonstrate that the use of the triple point of carbon dioxide offers promise as the fixed point for ITS-90 in place of the triple point of mercury, as well as the possibility of using it for calibration of both capsule and long-stem standard platinum resistance thermometers.
In time series analysis using the SSA method, a univariate series is converted into the multivariate one by shifts. The resulting trajectory matrix is subjected to principal component analysis (PCA). ...However, the principal components can also be computed using the PCA-Seq method if segments of the original series are selected as objects. The matrix of Euclidean distances between the objects can be obtained using any method, which offers additional opportunities for time series analysis compared to the conventional SSA. In this study, the PCA-Seq method was used to analyze the dynamics of COVID-19 epidemic indicators.
Gas permeation properties of three highly permeable perfluorinated polymers (polyhexafluoropropylene (PHFP), amorphous Teflon AF2400, and polyperfluoro(2-methyl-2-ethyl-dioxole-1,3) (PPFMED)), which ...are promising materials for the dense thin layer of hollow fiber membranes for extracorporeal membrane oxygenation have been studied using nitrogen, oxygen, and carbon dioxide. Hemocompatibility of the polymeric films has also been investigated on whole blood from healthy donors. Gas permeation of the polymers increases in the order PHFP < PPFMEDD < AF2400, with PHFP alone having the permeability coefficients of the gases do not below those of polydimethylsiloxane applied as the selective layer of blood oxygenation membranes. Hemocompatibility of the polymers declines in the order PHFP > PPFMED > AF2400, with the most permeable polymer AF2400 exhibiting the worst hemocompatibility among the other polymers studied. Polyperfluoro(2-methyl-2-ethyl-dioxole-1,3) is shown to be the most appropriate polymer to fabricate hollow fiber membranes for blood oxygenation.
Abstract
The dynamics of some magnetic fluid (MF) samples of various concentrations filling the tube horizontally and held by a field of a magnetic axial system made based on unipolar permanent ...rare-earth ring magnets were studied. The magnetic field of an “axial” magnetic system of MSO was studied, as well as the dependence of the system oscillation frequency on the length of the MF cylinder. An original method for determining MF magnetization is proposed and applied to the obtained data. Magnetization was determined for three magnetic fluid samples. The results obtained by the developed method are comparable to the magnetization values obtained by the ballistic method. The developed and presented technique of a dynamic experiment with measuring oscillations frequency of the “MF column suspended in a strong and inhomogeneous magnetic field” system involves the creation of a new absolute method for determining saturation magnetization and can be useful for studying magnetophoresis and aggregation processes of magnetic nanoparticles. This technique is used to study the degree of elastomagnetic consistency parameters over time.
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