Rheological behavior of oils in a magnetic field

The influence of magnetic treatment parameters on the rheological properties of oils has been investigated. It has been noted that the strongest effect on these properties is produced by the regime of magnetic treatment — steady-state or flowing, the volume rate of oil flow, and the induction value of the magnetoactivator magnetic field. The optimal regimes of magnetic treatment have been determined. It has been shown that treatment of oil with a magnetic field promotes a decrease in the solidification temperature and the amount of asphalt-resin deposits. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 102–109, January–February, 2006.     

Functional approach to the Rayleigh-Bénard problem for a nematic liquid crystal

The derivation of a functional analog of the free energy—the generalized thermodynamic potential— for an open system such as a nematic liquid crystal in a temperature gradient field is proposed. Near the threshold of thermal convection all the hydrodynamic variables can be described by a single complex amplitude w, the order parameter of the system, which enables one to determine the spatial position and the intensity of rotation of the convection rolls that arise. The orthogonality condition for the solutions is shown to yield an Euler equation from which one can recover the generalized thermodynamic potential, the extrema of which correspond to the most probable realizations of the dissipative structures. Pis’ma Zh. Tekh. Fiz. 24, 6–12 (June 26, 1998)     

Variational approach to free convection boundary-layer flow with suction and injection

The Gyarmati variational principle — a significant development in the field of the thermodynamics of irreversible processes — is employed to study suction and injection effects in flow and heat transfer in a free convection boundary layer over a cone. The velocity and temperature distributions inside respective boundary layers are considered as simple polynomial functions, and with the use of the perturbation procedure the variational principle is formulated. The Euler-Lagrange equations are reduced to coupled polynomial equations in terms of boundary-layer thicknesses. The skin-friction (shear-stress) and heat-transfer (Nusselt number) values with constant wall temperature are computed for various values of the suction and injection parameters and the cone-angle parameter. The comparison of the present solution with an available numerical solution shows good agreement. Published in Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 6, pp. 109–115, November–December, 2007.     

Influence of Optical and Thermophysical Characteristics of Biological Tissue on Its Thermal Conditions Under Laser Irradiation

On the basis of the developed analytical method of solving the heat conduction equation in a multicomponent biological tissue, its thermal conditions under laser irradiation have been investigated. Quantitative data on the temperature fields under a wide variation of the optical and thermophysical parameters in the tissue in the 400– 700-nm range of wavelengths are given. The steady-state regime of the field in the tissue at various depths has been investigated. Estimates of the possible use of the time dependence of temperature under tissue cooling to solve the inverse problem — determine the heat-conductivity coefficient, the parameter of heat exchange with the medium, and the depth attenuation coefficient of light — are given. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 3, pp. 15–21, May–June, 2005.     

Non-unique solution for combined-convection assisting flow over vertical flat plate

Non-unique solutions of flow and temperature field are reported here for the first time for non-similar flows given by the laminar boundary layer equations for combined-convection flow past a vertical flat plate. The solution of the boundary layer equation for natural convection constitutes the self-similar solution whose perturbation with respect to the small parameter (ε), which is inversely proportional to the square root of the Richardson number (G _x ), provides the non-similar solution. Solutions obtained by the shooting method indicate two sets for the self-similar solution (ε = 0) — one of them showing positive velocity everywhere inside the shear layer (well-known oft-reported physical result). The other self-similar solution shows that recirculation in the outer part of the shear layer may not be physical — as it has not been experimentally demonstrated so far. In contrast, the perturbative part of the non-similar solution (ε ⊋ 0) is seen to be either convergent or divergent depending upon the choice of integration domain of the shear layer equations — bringing forth the question of the validity of such perturbation procedures and possible stability of the basic solution itself.     

Temperature field of an ice shelf in the vicinity of a hot water-drilled well

The temperature of an ice shelf following open thermic drilling is investigated. The time dependence of the ice temperature and the profile of its lower surface are analyzed. The time of relaxation of the system ocean—ice shelf—atmosphere to the equilibrium state is estimated. The results are used to substantiate the use of data on the dynamics of the lower surface of an ice shelf in monitoring of global temperature of the ocean. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 1, pp. 155–160, January–February, 1998.     

Anticipating technological breakthroughs: Using bibliographic coupling to explore the nanotubes paradigm

There is general consensus that the field of nanotechnology will be very important in the future. An open question is, however, which technological approaches or paradigms will be important in the field. The paper assumes that the carbon nanotube will be a key element of an emerging technological paradigm in nanotechnology. This study employs a bibliometric method — bibliographic coupling — to identify important nanotubes-related ‘leitbilder’ — a concept meaning ‘guiding images’ that provide a basis for different professions and disciplines to work in the same direction. Until recently, bibliographic coupling has been applied rarely for purposes of research evaluation, not to mention technology foresight. Our case study seems to suggest that bibliographic coupling is particularly suitable for anticipating technological breakthroughs. Bibliographic coupling analysis of recent nanotube-related patents focused our attention to recent patents owned by Nantero Inc. Nantero’s main focus is the development of NRAM — a high-density nonvolatile random access memory. The NRAM leitbild seems to be an important emerging leitbild. It connects technical opportunities and promising applications relating to the memories in devices such as cell phones, MP3 players, digital cameras, as well as applications in networking arena.     

Physical Properties of π-d Interaction-Based Molecular Conducting Magnet (EDO-TTFBr2)2FeCl4 Under Pressure

SdH — measurements were performed on the organic metal (TMTSF)₂ReO₄ under a pressure of 8.5 kbar. Fast oscillations (FO) with a frequency of 330T could be reproduced already above 4.5T for temperatures below 4.5K. It could be shown, that these oscillations are not influenced by field induced spin-density-waves (FISDW’s) with a frequency of 28T. The effective carrier mass could be calculated to be m_FO=1.4 m_e. The observation of the FISDW’s is strongly temperature dependent. The temperature and magnetic field dependent phase diagram for the FISDW’s is discussed.     

Analysis of the process of mixing of a passive impurity in a jet mixer

The experimental results for two regimes of mixing of a passive impurity in an axisymmetric jet mixer — the mixing of a turbulent jet and a cocurrent flow to form a recirculation zone behind the nozzle and an analogous mixing without the formation of a recirculation zone (Re_d = 10,000) — have been presented. The velocity field has been measured in the mixer cross sections at different distances from the nozzle (0.1 < x/D < 9.1) with a one-component Doppler laser anemometer, whereas the scalar field (concentration of the passive impurity) has been diagnosed by the laser-induced fluorescence method. Based on the scalar distributions obtained, the autocorrelation function and the integral scale have been computed, the form of the probability density function has been restored, and the distributions of the asymmetry and excess coefficients have been constructed. Visualization of flow in the mixer has been carried out. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 46–59, March–April, 2007.     

Construction and Start-up of a Large-Volume Thermostat for Dielectric-Constant Gas Thermometry

A liquid-bath thermostat with a volume of about 800  L was designed to provide a suitable thermal environment for a dielectric-constant gas thermometer (DCGT) in the range from the triple point of mercury to the melting point of gallium. In the article, results obtained with the unique, huge thermostat without the DCGT measuring chamber are reported to demonstrate the capability of controlling the temperature of very large systems at a metrological level. First tests showed that the bath together with its temperature controller provide a temperature variation of less than ±0.5mK peak-to-peak. This temperature instability could be maintained over a period of several days. In the central working volume (diameter—500mm, height—650mm), in which the vacuum chamber containing the measuring system of the DCGT will be placed later, the temperature inhomogeneity has been demonstrated to be also well below 1mK.     

Faceting–roughening of twin grain boundaries

The coincidence site lattice (CSL) plays a similar role for grain boundaries (GB) as the crystal lattice plays for free surfaces. The most densely packed CSL is the twin-related CSL, characterized by an inverse density of coincidence sites Σ = 3. Phase diagrams in coordinates “relative temperature T/T _m—misorientation angle θ—inclination angle φ” were constructed for the twin GBs in Cu, Al, and Mo having different stacking fault energy γ. At low γ the twin GB remains faceted at all φ values and the number of crystallographically different facets increases with decreasing temperature. With increasing γ asymmetric twin GBs become more and more rough, and fewer facets appear with decreasing temperature. Also, with increasing γ the facets start to degenerate of into the first order rough-to-rough ridges. The behavior of twin GBs in Cu, Al, and Mo is compared with that of twin GBs in Zn.     

Dynamics of laser bullet propagation in carbon nanotube array with metal inhomogeneities

The problem of the propagation of a solitary wave—a two-dimensional analog of the so-called laser (light) bullet—in an array of carbon nanotubes with metal inhomogeneities (defects) has been considered. An effective equation for the vector potential of this wave is obtained and numerically studied. It is established that the scattering of a laser bullet on a pair of metal inhomogeneities is accompanied by characteristic “beats” of the electromagnetic field.     

Theoretical substantiation of the possibility of inducing a ponderomotive thermodynamic force in a solid and a gas

Based on the principle of least action extended by the author to heat conduction in a solid, owing to the formal analogy between time and absolute temperature stated in the 1980s by means of the formalism of the Hamilton—Jacobi equation an expression is obtained for the ponderomotive thermodynamic force in a solid and a gas. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 5, pp. 917–926, September–October, 1998.     

Effects of crosslinking ratio,model drugs,and electric field strength on electrically controlled release for alginate-based hydrogel

The drug release characteristics of calcium alginate hydrogels, (Ca-Alg), under an electric field assisted transdermal drug delivery system were systematically investigated. The Ca-Alg hydrogels were prepared by the solution-casting using CaCl₂ as a crosslinking agent. The diffusion coefficients and the release mechanism of the anionic model drugs, benzoic acid and tannic acid, and a cationic model drug, folic acid on the Ca-Alg hydrogels were determined and investigated using a modified Franz-Diffusion cell in an MES buffer solution of pH 5.5, at a temperature of 37°C, for 48 h. The influences of the crosslinking ratio, —the mole of the crosslinking agent to the mole of the alginate monomer—mesh size, model drug size, drug charge, electric field strength, and electrode polarity were systematically studied. The drug diffusion coefficient decreased with an increasing crosslinking ratio and drug size for all of the model drugs. The drug diffusion coefficient is precisely controlled by an applied electric field and the electrode polarity depending on the drug charge, suitable for a tailor-made transdermal drug delivery system.     

Influence of the concentration of a dispersed phase and of the magnetic field on the attenuation of ultrasonic waves in magnetic fluids

The regularities of the propagation of elastic waves of ultrasonic range in magnetic fluids have been experimentally established. The influence of relaxation processes — nonlocal heat exchange and viscous dissipation — on the coefficient of attenuation of sound has been revealed and a comparison to the existing theoretical data has been made. The dependences (anisotropic in form) of the attenuation of the wave’s amplitude on the value and direction of the magnetic field have been determined and an interpretation of the results obtained has been proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 5, pp. 133–140, September–October, 2007.     

A basis for the évolution of strategy for a futuristic development of building materials

Conclusions A basis for evolving strategy for development of building materials maintaining the mass—energy— environment balance is outlined. The technical, ecological and economic dictates of the future compell us to develop building materials aligning with nature — using natural resources and converting society’s wastes into wealth. Energy requirements in the manufacture and use of materials will be a prime consideration. Greater thrusts to the engineering and industrial aspects of manufacture and utilization of building materials is futuristically important.     

Allowance for the index of refraction in air during transmission of the unit of length—the meter—in the long wave region

We show that for transmission of the unit of length—the meter—we must allow for the index of refraction of air. We present a mechanical solution for determination of the integral index of refraction by using the Faraday effect in the Earth's magnetic field. Translated from Izmeritel'naya Tekhnika, No. 7, pp. 6–7, July, 1997.     

Unsteady Heat Transfer in HeII in Cylindrical and Spherical Geometries

The problem of evolution of strong heat pulses in superfluid helium interacting with quantum vortices induced by these pulses is investigated numerically on the basis of equations of hydrodynamics of superfluid turbulence. The “discontinuity decay” method (Godunov method) is used for the calculations. In order to study nonlinear effects, the initial equations are expanded to the second order in the amplitudes of pulses. The influence of the main flow parameters—heat flux and rest time—on temperature evolution is reported. The numerical investigations are carried out at the bath temperature of 1.4 K. The obtained results are compared with experimental data.      

Preparation of PLGA/β-TCP composite scaffolds with supercritical CO 2 foaming technique

A high porosity scaffold with suitable compressive strength prepared by a gentle method has become a pressing need. To meet this demand, poly(DL-lactide-co-glycolide) (PLGA) and β-tricalcium phosphate (β-TCP) were designed to prepare composite scaffolds by the supercritical technique. The preparation process consisted of three units: the mixing of PLGA and β-TCP, compression molding of the mixture, and the foaming process. Six influencing factors — temperature, pressure of the scCO₂ system, maintaining time of scCO₂, the ratio of β-TCP to PLGA, the rate of depressurization, and the molecular weight — were investigated. The results collectively indicated that the optimized conditions for the foaming process were that CO₂ pressure and temperature be 8MPa and 39°C, respectively, which should be kept for 8h; the content of β-TCP in the mixture should be 25% and the depressurizing rate be 0.1 MPa/s, using PLGA of an 80kDa molecular weight. Scaffolds with a porosity of 65.47% and a compressive strength of 4.76 MPa could be obtained. The pore size ranged around 100 µm. The material’s use as tissue engineering scaffolding is expected.     

Simulation of the turbulent mixing of a passive impurity in a jet mixer

Results of numerical simulation of the mixing of a turbulent jet with a cocurrent incompressible-fluid flow (Schmidt number Sc ≈ 1000) in a cylindrical channel of circular cross section (axisymmetric mixer) with the use of the standard k-ε turbulence model and different models for the averaged value of the mixture fraction and its variance have been given. For the problem of mixing of an inert passive impurity, two regimes of flow — the regime with the formation of a recirculation zone and that without its formation — have been considered. The formulated statistical model has been verified with the use of experimental data and results of calculation by large-eddy simulation. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 4, pp. 666–681, July–August, 2008.