Concentration dependence of the anomalous thermoelectric power of dilute magnetic alloys

It has been pointed out recently by one of us (M.S.R.C.) that the variation of the Kondo slopesd (of the /c vs. lnT curves) of dilute magnetic alloys containing a finite solute concentrationc bears a close resemblance to the variation of the functionf (=cos⁶ cos2) with the phase shift for ordinary spin-independent scattering. Sinced is itself primarily determined byf the inference is that is a function ofc when the criterion of infinite dilution is violated. For infinite dilutions theory expects the anomalous thermoelectric power in such alloys to be independent ofc as well as ofT. Taking the experimentally observed extremum in the TEP (S _m) as an approximation to such a TEP, we report, for finite solute concentrations, the variation ofS _m withc, to correspond with the variation off(=cos ⁶ sin2) with . This substantiates the above inference. In fact, one can predict the sign and the variation (withc) ofd, knowing that ofS _m, and vice versa, for a given dilute magnetic alloy system.     

Evolution of transient thermal processes in layer counterflow apparatuses and heat exchangers

Results are given of an analytic investigation of transient processes inside counterflow apparatuses and heat exchangers with temperature disturbance in one of the heat carriers at the entry to the apparatus.Notation =(t–t₀)/(T₀–t₀),=(T–t₀)/(T₀ s-t₀) relative temperatures - t, T temperatures of material and gas respectively - t₀, T₀ same for the initial state - Z=[ _Vm₁/c(1–w/w_g)] [–(y₀–y)/w_g] dimensionless time - m₁=1/(1+Bi/) solidity coefficient - B₁=( _FR/) Biot number - _{F V} heat-exchange coefficients referred to 1 m² surface and 1 m³ layer - R depth of heat penetration in a portion - portion heat conductivity coefficient - shape coefficient (=0 for a plate,=1 for a cylinder,=2 for a sphere) - c, C_g heat capacities of material and gas respectively - , _g volumetric masses - w, W_g flow velocities of material and gas - y distance from the point of entry to the heating heat carrier - y₀ heat-exchanger length - Y= _Vm₁y/W_gC_{g g} dimensionless coordinate - m=cw/C_g– _gW_g water equivalent ratio Deceased.Translated from Inzhenerno-Fizicheskii Zhurnal, vol. 20, No. 5, pp. 832–840, May, 1971.     

Influence of Saffman's lift force on the motion of a particle in a Couette layer

The article is concerned with the study of the effect of E. S. Asmolov's corrections to Saffman's lift force for the wall vicinity and a nonzero ratio of Reynolds numbers. It is shown in what way these corrections change the particle paths in a Couette layer and the conditions of deposition.Notation x=X/D, y=Y/D dimensionless longitudinal and transverse coordinates - u=U _p /U , =V _p /U dimensionless projections of particle velocity on the longitudinal and transverse axes - =tU /D dimensionless time - U ²/(18D) Stokes number - = _g / _p , coefficient of the gas kinematic viscosity - particle diameter - /D - _g , _p densities of the gas and particle material - du/d - dv/d - P _s Saffman's force - C coefficient in the formula for Saffman's force - yRe _d ^1/2 - A v _r Re _d ^1/2 - 3.08 - Re V _r / - Re _k ²/)U _g /Y - A Re/Re _k ^1/2 - Re _d U D/ - V _r ((U _g –U _p )²+V _p ² )^1/2 Indices g refers to gas parameters - p refers to the parameters of particles - 0 at the time momentt=0 - S Saffman's force - k Reynolds number based on the velocity gradient - based on velocity - r relative velocity - x projection on thex axis     

Critical dynamics of a sheared micellar solution

We have investigated the dynamic behavior of a nonionic micellar solution of tetra-ethylene glycoln-decylether (C₁₀ E₄) in water near its critical point in the presence of shear. The non-Newtonian behavior of the viscosity can be represented by * = [ 1 +a(S₄)=]², where* is the viscosity in the absence of shear,S is the shear rate. ₄ is the lifetime of the critical Iluctuations,a is a system-dependent constant, and = 0.02 In addition, we have found that, before attaining a steady state, the sheared mixture undergoing phase separation shows significant shear-dependent rheological effects due to the presence of concentration domains.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24. 1994, Boulder, Colorado, U.S.A.     

New manifestations of the Josephson effect in helium

Using a method due to Bloch, it is shown that in thermodynamic equilibrium an annular container of mean radiusR, massM, containingN atoms of helium II of massm each will, when subjected to a torque , evince oscillations in its angular acceleration about the classical value. The frequency, , of these oscillations is given by /m=/(M+Nm). The difficulty of achieving equilibrium is pointed out.Supported in part by US Air Force Office of Scientific Research through Grant No. AFOSR 565-66.     

The effect of temperature on the transition from crazing to shear deformation in crosslinked polystyrene

Thin films (0.7m thick) of polystyrene (PS) are bonded to copper grids and crosslinked by exposure to electron irradiation. By controlling the exposure time it is possible to produce samples of PS having a range of network strand densities (entangled and crosslinked). After physical ageing at 75° C for 10 to 12 h the PS films are then strained in tension at various temperatures. Transmission electron microscopy is used to characterize the ensuing deformation as well as measure the local extension ratio in either a craze or a deformation zone. A transition from crazing to shear deformation is observed to occur with increasing values of . At a slow strain rate of 4.1×10^–6 sec^–1 and a temperature of 23° C this transition in the aged PS occurs at (10 to 14)×10²⁵ strands m^–3, whereas at the same strain rate and 90° C the transition occurs at (5.8 to 8)×10²⁵ strands m^–3. The transition from crazing to shear deformation with increasing v may be rationalized by considering the extra energy required to break more main-chain polymer bonds to form the craze fibril surfaces in the high- networks. As the temperature is increased the yield stress _y (which is assumed to be independent of ) decreases almost linearly to zero as T _g is approached. On the other hand the crazing stress may be approximated by S _c [ _y(T) ^1/2]^1/2. Thus at higher temperatures the transition from crazing to shear deformation is expected to occur at lower values of as observed.     

Heat transfer in vapor condensation on laminar and turbulent liquid jets,taking account of the inlet section and variability of the flow rate over the jet cross section

The results of numerical modeling of heat transfer in phase transition at jets are outlined.Notation x, y orthogonal coordinate system related to jet symmetry axis - u, v components of the velocity vector along the coordinates x and y - T temperature - kinematic viscosity - a thermal diffusivity - density - thermal conductivity - c_p specific heat at constant pressure - h_fg latent heat of vaporization - Re=u₀R₀/ Reynolds number - Pr=/a Prandtl number - Fr=u₀ ²/(gR₀) Froude number - We=u₀ ²R₀/ Weber number Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 5, pp. 732–735, May, 1988.     

Intensity of critical opalescence of helium-4

We present measurements of the critical opalescence of helium-4. The results are analyzed by the Einstein and Ornstein-Zernike theory and the power laws. We obtain ==1.17±0.02, ==0.62±0.1,/=4.5±0.3,P _c =1706.008 mm Hg, andT _c =5,189.863 mK (T ₅₈ ). The critical behavior of helium-4 is almost the same as that of classical fluids and the influence of the quantum nature of helium-4 is not as evident as has been claimed.     

A boundary integral equation method for a Neumann boundary problem for force-free fields

Summary A Neumann boundary value problem for the equation rot –=0 is considered in 29-1 and 29-2. The approach is by transforming the boundary value problem into an equivalent boundary integral equation deduced from a representation formula for solutions of rot –=0 based on the fundamental solution of the Helmholtz equation. In particular, for the two-dimensional case a detailed discussion of the integral equation is carried out including the approximate solution by numerical integration.     

Influence of pressure and crystallization rate on the surface microhardness of high-density polyethylene

The indentation microhardnessMH of high-density polyethylene crystallized at different pressuresp and crystallization rates _c has been investigated. The results confirm thatMH is an increasing function of lamellar thickness and therefore of density. The rate of increase depends on the crystallization conditionsp and _c. Crystallization at high pressure leads toMH values considerably higher than those of samples prepared under atmospheric pressure. The results are discussed in terms of compressed amorphous regions contributing to an elastic release after removal of the indenter. For samples crystallized under different pressures the hardness value turns out to be nearly independent of the elastic modulusE. For samples crystallized at different rates _c there is a steady decrease of microhardness with increasing _c (decrease of lamellar thickness) but no simple relationship withE. With higher rates _c the appearance of strained tie molecules provokes a rapid increase ofE whileMH decreases further because the crystals become smaller.     

Natural convection in a rectangular enclosure in the presence of a magnetic field with uniform heat flux from the side walls

Summary A numerical study is presented for magnetohydrodynamic free convection of an electrically conducting fluid in a two-dimensional rectangular enclosure in which two side walls are maintained at uniform heat flux condition. The horizontal top and bottom walls are thermally insulated. A finite difference scheme comprising of modified ADI (Alternating Direction Implicit) method and SOR (Successive-Over-Relaxation) method is used to solve the governing equations. Computations are carried out over a wide range of Grashof number, Gr and Hartmann number, Ha for an enclosure of aspect ratio 1 and 2. The influences of these parameters on the flow pattern and the associated heat transfer characteristics are discussed. Numerical results show that with the application of an external magnetic field, the temperature and velocity fields are significantly modified. When the Grashof number is low and Hartmann number is high, the central streamlines are elongated and the isotherms are almost parallel representing a conduction state. For sufficiently large magnetic field strength the convection is suppressed for all values of Gr. The average Nusselt number decreases with an increase of Hartmann number and hence a magnetic field can be used as an effective mechanism to control the convection in an enclosure.List of symbols Ar aspect ratio,H/L - B ₀ induction magnetic field - H ₀ magnetic field,H ₀=B ₀/ _m - g gravitational acceleration - Gr Grashof number,gq(L/k)L ³/v ² - H height of the enclosure - Ha Hartmann number, - k thermal conductivity - Nu local Nusselt number - average Nusselt number - p pressure - Pr Prandtl number, / - q heat flux - t time - T dimensionless temperature, (–₀)/q(L/k) - u vertical velocity - U dimensionless vertical velocity,uL/ - v horizontal velocity - V dimensionless horizontal velocity,vL/ - x vertical coordinate - X dimensionless vertical coordinate,x/L - y horizontal coordinate - Y dimensionless horizontal coordinate,y/L - thermal diffusivity - thermal expansion coefficient - temperature - ₀ reference temperature - density - kinematic viscosity - viscosity - _m magnetic permeability - electrical conductivity - stream function - dimensionless stream function, / - dimensionless time,t/L ² - vorticity - dimensionless vorticity, L ²/ - X grid spacing inX-direction - Y grid spacing inY-direction - time increment - ² Laplacian operator     

Thermophysical properties data on molten semiconductors

Thermophysical properties of molten semiconductors are reviewed. Published data for viscosity, thermal conductivity, surface tension, and other properties are presented. Several measurement methods often used for molten semiconductors are described. Recommended values of thermophysical properties are tabulated for Si, Ge, GaAs, InP, InSb, GaSb, and other compounds. This review shows that further measurements of thermophysical properties of GaAs and InP in the molten state are required. It is also indicated that a very limited amount of data on emissivity is available. Space experiments relating to thermophysical property measurements are described briefly.Nomenclature Density - C _p Specific heat - Kinematic viscosity - Dynamic viscosity= - Thermal diffusivity - Thermal conductivity=C_p - Volumetric thermal expansion coefficient - Surface tension - d/dT Temperature coefficient of surface tension - g Gravitational acceleration - T Temperature - T Temperature difference - L Characteristic dimension     

Environmental shear deformation zones and crazes in crosslinked polystyrene and poly(para-methylstyrene)

Thin films ( 1m) of polystyrene and poly (para-methylstyrene) were bonded to annealed copper grids and crosslinked using electron radiation to increase, the network strand density. At each separate films were strained in air and in Freon 113 until the critical strain, _c, for plastic deformation was reached. Transmission electron microscopy observations reveal that both sets of films undergo a transition from crazing to localized shear deformation zones (DZs) as is increased. The critical strains for both crazing and DZ formation are markedly decreased in Freon 113. The DZs formed in Freon 113 show abrupt changes in extension ratio,, at their interfaces while those formed in air show more diffuse changes in. A mechanism for environmental DZ formation is proposed in which the diffusion rate of Freon 113 into the DZ is strongly enhanced by the ongoing plastic deformation. This mechanism is suggested by Rutherford backscattering measurements of Freon 113 diffusion into PS which show that such diffusion in the absence of plastic deformation is much too slow to allow the observed rate of growth of the environmental DZs.     

Study on attribution of laser Raman spectroscopy for hopeite crystal films

Laser Raman spectroscopy was applied to clarify the chemical structure of hopeite crystal films. Orthophosphate [PO ₄ ^3– ], which is a regular tetrahedron, has four basic vibration modes, + ₁, ₂, ₃ + of which ₁, and ₃ are observed at 800 to 1300 cm^–1. Here, the main peak corresponds to ₁ and the other peaks correspond to ₃ untied and split. A reference sample of 85% H₃PO₄ showed two peaks in the same region, the main peak corresponding to ₁ and the sub-peak corresponding to ₃ degenerated. It was found that a basic vibration mode of ₃ appears at 1150 cm^–1. Raman spectra were observed for hopeite dissolved in HCL solution. Three peaks were found in the region, but the spectral pattern was quite different from that of crystalline hopeite, and was similar to that of H₃PO₄ aqueous solution. The peak intensity ratio of I ₁₀₇₅/I ₆₉₀ differed between liquid-state hopeite and H₃PO₄ aqueous solution, but the band frequencies of the three peaks were consistent with each other. It was confirmed that the three peaks correspond to the P(OH)₃ and PO stretching vibrations of [H₃PO₄] and the PO₂ stretching vibration of [H₂PO ₄ ^– ] formed by the dissociation of H₃PO₄. The PO₂ stretching vibration observed at 1075 cm^–1 depends on the dissociation state of H₃PO₄.     

Influence of metal components in Hopeite films on IR and laser Raman spectra

Hopeite films on galvannealed steel were formed in various zinc phosphate solutions. The metal component composition of various Hopeite films was determined by atomic absorption. By measuring the infrared (IR) spectra and the laser Raman spectra for these films, the influence of metal component composition on these spectra could be investigated. In IR spectra, peaks corresponding to ₃ and ₄, the basic vibration mode of PO ₄ ^3– , were seen, but the peak patterns of ₄ were different for Hopeite containing manganese and that not containing it. In the Raman spectra, four clear peaks for various films were found in the region 1300 to 800 cm^–1 . Although these spectra are due to PO ₄ ^3– , ₁ and ₃ are found in this region. Essentially, ₃ degenerates triply, but in the crystalline state of Hopeite films, the symmetry of the regular PO ₄ ^3– tetrahedron will be distorted by the interaction. At that moment, the degenerations of ₃ are untied and split into three peaks. Thus it was thought that spectra with four peaks of ₁ were generated. However, the main peak corresponds to ₁ and other three peaks correspond to ₃. The values of the Raman band for various Hopeite films were compared. The band shifted to the lower wavenumber region according to the increase of manganese or nickel in these films. The structure of Hopeite films modified by the action of manganese or nickel has been analysed to be Zn_3–x Me _x (PO₄)₂ · 4H₂O (Me = Mn or Ni), but this structure is different from that of normal Hopeite films (Zn₃(PO₄)₂ · 4H₂O).     

A boundary layer theory for the end problem of a circular cylinder

Summary This paper discusses the nature of an approximate solution for the hollow circular cylinder whose fixed ends are given a uniform relative axial displacement and whose cylindrical surfaces are free from traction. We shall take the solution of this problem to be given by a super-position of the following two problems: problem I considers a finite length cylinder whose ends are given a relative axial displacement, but are no longer fixed; problem II removes the radial displacement at the end of the cylinder obtained in problem I.Nomenclature a mid-surface radius of cylinder - c half-height of cylinder - E, in-plane elastic moduli - E_t, _t, G_t transverse elastic moduli - _z, , _r axial, circumferential, and normal strain - _rz transverse shear strain - h cylinder thickness - _z, , _r axial, circumferential, and normal stress - _rz transverse shear stress - z, r axial and radial coordinates - u_z, u_r axial and normal displacements     

hp-version finite elements for the space-time domain

A bilinear formulation of elasto-dynamics is offered which includes, as a special case, Hamilton's law of varying action. However, the more general bilinear formulation has several advantages over Hamilton's law. First, it admits a larger class of initial-value and boundary-value problems. Second, in its variational form, it offers physical insight into the so-called trailing terms of Hamilton's law. Third, numerical applications (i.e., finite elements in time) can be proven to be convergent under correct application of the bilinear formulation, whereas they can be demonstrated to diverge for specific problems under Hamilton's law. Fourth, the bilinear formulation offers automatic convergence of the natural velocity end conditions; while these must be constrained in present applications of Hamilton's law. Fifth, the bilinear formulation can be implemented in terms of a Larange multiplier that gives an order of magnitude improvement in the convergence of velocity. This implies that, in this form, the method is a hybrid finite-element approach.List of symbols b arbitrary constant - A _i, A _i vector of integrals, i = 0, j - A() linear operator on - () Hamilton's form of A - B (u, ) bilinear operator u, - B (u, ) Hamilton's form of B - B _i,j , B _ij , B _ij matrix of integrals - C constant, N/m - c number of floating-point operations per coef. evaluation - f, f(x) force per unit length, N/m - F, F ₀, F _L forces, N - J number of functions in series for û - k spring rate per unit length, N/m² - K spring rate, N/m - K _max maximum value of K - L _a Lagrangian, non-dimensional - L length of beam, m - m mass per unit length, kg/m - M mass, kg - M _max maximum value of M - n number of functions in series for - N number of elements in domain - p momentum density, kg/sec - P, P ₀, P _T momentum, kg-m/sec - q _i generalized coordinates - r _j coefficients of _j - t time, sec - t ₀, t ₁ limits of action integral, Hamilton's law - T end of time period, sec - u solution for displacement, m - û approximation to u, m - u ₀ initial value for u, m - test function, m - limited class of , m - x spatial coordinate, m - flapping angle, rad - Lock number - time increment, sec - Lagrange multiplier - longitudinal stiffness EA, N (Eqs. 1–18) - advance ratio of rotor (Eqs. 33–34 and figures) - _i , _r polynomial functions - non-dimensional time, azimuth angle - () variation of ( ) - W virtual work - ( ) d ( )/dx - ( .) d ( )/dt - (*) d/d - [ ] matrix - { } column vector - row vector     

Numerical simulation of hydrodynamics of a weakly compressible gas-liquid medium

A method for numerical simulation of the hydrodynamic parameters of a gas-liquid medium with allowance for its weak compressibility is proposed. Application of the method is illustrated by the example of the calculation of the hydrodynamics of a melt in a ladle during its filling and the blow.Notation V, V velocity of the medium and its value - W diffusion velocity of the gas phase - g free fall acceleration - , ₀, ₁ densities of the medium, the liquid, and the gas phases - p pressure - ; ₀, , , , coefficients of the gas content in the flow, gas content in the medium, dynamic and kinematic viscosity, surface tension - _ef effective dynamic viscosity coefficient - Re _d ,b its parameters: the grid Reynolds number and the ratio of the mixing length to the grid subinterval - polytrope exponent - R, H radius and height of the tank - R _fl radius of the flow - time step - d grid subinterval Institute of Technical Thermophysics of the Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 5, September–October, 1995, pp. 774–780.     

Evaporation of liquids from cylindrical vessels under conditions of free concentrational convection in a gas phase

An analytical solution is obtained for the axisymmetric problem of free concentrational convection in a vapor-gas mixture with isothermal evaporation of liquids from open cylindrical vessels. Formulas are derived to calculate concentration fields, local and integral mass fluxes of vapor. A comparative analysis of the results of analytical and numerical simulation is carried out for the processes of the evaporation of liquids under the conditions of convective mass transfer.Notation p pressure, Pa - density, kg/m³ - v velocity, m/sec - , dynamic and kinematic viscosity, Pa·sec, m²/sec - D diffusion coefficient, m²/sec - ₁, ₂ mass fractions of vapor and gas in a mixture - g free fall acceleration, m/sec² - M ₁,M ₂ molar masses of vapor and gas, kg/kmole - _r , _z radial and axial components of the velocity of a gas-vapor mixture, m/sec - r, z cylindrical coordinates, m - R, H radius and height of vessel, m - j local mass flux of vapor, kg/(m²·sec) - j vessel cross-sectional area-averaged mass flux of vapor, kg/(m²·sec) - j vessel cross-sectional area-averaged mass flux Chelyabinsk State Technical University, Russia. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 3, pp. 403–407, May–June, 1995.     

Structure of flows in vortices

The structure of a gradient vortical flow was studied experimentally.Notation v_x, v_y, v_z flow velocity components in a rectangular coordinate system - v, v_r, v_z flow velocity components in a cylindrical coordinate system - v₁ tangential velocity at the boundary of solid revolution at r = r₁ - l length of the vortex - kinematic viscosity - R radius of the forming cylinder - circulation in the region of potential flow - second air flow rate through the eddy of ascending flows - Re=v₁r₁/ tangential Reynolds number - N=Q/r_o radial Reynolds number - a=l/r₀ configuration ratio for the vortex model - s=r_o/2Q effective exchange coefficient - a ^*=l/r configuration ratio for the vortex generator - s^*=R/Q constructive exchange coefficient - p=p–p pressure drop in the vortex relative to atmospheric pressure p - r^*= r/r₁ dimensionless radius of the vortex - v^*=v/v₁ dimensionless tangential velocity - a ^*/a gradient ratio Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 4, pp. 611–618, October, 1980.