Retardation of electromagnetic waves by helices of large diameters

This paper is devoted to the study of the wave retardation by helices of large diameters, when the lengthL of one turn of the helix is larger than the vacuum wavelength, i.e.L/>1. The dispersion equation of the tape helix wound up on a dielectric cylinder was derived and the dependence of the phase velocity of slowed-down waves on the diameter of helix was calculated. The theory was verified experimentally at a frequencyf=2·385 GHz. Helices were wound up on polyfoam (=1·04) and plexiglass (=2·55) cylinders of various diameters. For the helix wound up on plexiglass cylinders it was found that the wave retardation depends on the form of conductor from which the helix is made. The retardation of waves is determined by an effective dielectric constant _ef which is equal either ( _i + _e)/2 for the tape helix or ( _{i e}) for the helix made from a wire of the circular cross-section; here _i is the dielectric constant of inner dielectric rod and _e is that of outer space.     

An upgraded analysis of ɛ′/ɛ at the next-to-leading order

An upgraded analysis of ,x _d and /, using the latest determinations of the relevant experimental and theoretical parameters, is presented. Using the recent determination of the top quark mass,m _t =(174±17) GeV, our best estimate is /=(3.1±2.5)×10^–, which lies in the range given by E731. We describe our detemination of / and make a comparison with other similar studies. A detailed discussion of the matching of the full theory to the effective Hamiltonian, written in terms of lattice operators, is also given.     

Investigation of ionic thermocurrents in SrCl2-K crystals

Ionic thermocurrents in SrCl₂-K crystals have been investigated for the first time. Two maxima of thermally stimulated depolarization currents have been detected at T=112°K and T=210–240°K. The low-temperature maximum with a reorientation energy =0.25 eV and a frequency factor _o=7.1·10⁹ Hz is due to relaxation of impurity-vacancy dipoles. Its intensity grows linearly with the concentration of the dopand. The high-temperature maximum is due to the space charge. Its activation energy =0.46 eV coincides with the migration energy of anion vacancies associated with the potassium ions.Translated from Izvestiya Vysshikh Zavedenii, Fizika, No. 9, pp. 80–83, September, 1982.     

Effect of ultrasonic vibrations on the parameters of the hardening curve for copper single crystals

The variations induced in the parameters of the hardening curve for copper single crystals by ultrasonic vibrations at a frequency of 20 kHz are investigated. It is shown that the application of ultrasound to the samples under tension significantly lowers the critical yield stress (₀) and increases the duration of the first hardening stage (₂). Preliminary ultrasonic irradiation is accompanied by an increase in ₀ and an appreciable increase in ₂. The magnitude of the variations oft ₀ and ₂ depends on the ultrasonic intensity. Experimental results are given for the time dependence of the recovery of the yield point for the irradiated copper samples at 20 and –50 °C.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 51–56, February, 1972.     

Improved slow-positron yield using a single crystal tungsten moderator

A well-annealed W(110) single crystal was used as a fast-to-slow positron moderator. The measured moderator efficiency at room temperature using a⁵⁸Co positron source in the backscattering geometry is =(3.2±0.4)×10^–3, roughly a factor of three better than for the best previously reported Cu(111)+S moderator. We find a stable positron moderation efficiency over a period of several weeks when maintained at pressures around 10^–9 Torr and an energy spreadE = 0.7 eV of the emitted slow positrons. An initial attempt was made to fabricate a hybrid Cu on W(110) moderator, which yielded of about 1.2×10^–3 after annealing.     

The ɛ-expansion for the Hierarchical Model

In this paper, the Hierarchical Model is studied near a non-trivial fixed point of its renormalization group. Our analysis is an extension of work of Bleher and Sinai. We prove the validity of the -expansion for . We then show that the renormalization transformations around have an unstable manifold which is completely characterized by the tangent map and can be brought to normal form. We then establish relations between this result and the critical behaviour of the model in the thermodynamic limit.     

Dielectric properties of titanium and gadolinium doped MgO single crystals

The dielectric properties of titanium doped magnesium oxide (Ti/MgO) and gadolinium doped magnesium oxide (Gd/MgO) single crystals have been measured at room temperature over the frequency range 500 Hz to 50 kHz. For both the crystals, the dielectric constant is found to be independent of frequency and the ac conductivity Re{_ae} agrees well with the relation Re{_ae} ⁿ , being the angular frequency with n=0.84±0.05 for Ti/MgO andn=0.81±0.03 for Gd/MgO. The data fits well with the relation ^n–1(n<1), being the dielectric loss factor. An explanation may be found on the basis of the hopping phenomenon.     

Critical (Φ4)3,ε

The Euclidean (⁴)_3, model in R³ corresponds to a perturbation by a ⁴ interaction of a Gaussian measure on scalar fields with a covariance depending on a real parameter in the range 01. For =1 one recovers the covariance of a massless scalar field in R³. For =0, ⁴ is a marginal interaction. For 0<1 the covariance continues to be Osterwalder-Schrader and pointwise positive. We consider the infinite volume critical theory with a fixed ultraviolet cutoff at the unit length scale and we prove that for >0, sufficiently small, there exists a non-gaussian fixed point (with one unstable direction) of the Renormalization Group iterations. We construct the stable critical manifold near this fixed point and prove that under Renormalization Group iterations the critical theories converge to the fixed point. Partially supported by NSERC of CanadaLaboratoire Associé au CNRS. UMR 5825Partially supported by CNR, G.N.F.M. and MURST     

Effect of quenching temperature on the components of the permeability tensor and the complex dielectric constant of microwave magnesium ferrites

We report an investigation of the effect of the quenching temperature (from 900 °C, 700 °C, and for self-cooling) on the components of the permeability tensor and on the complex dielectric constant * of magnesium-aluminum, magnesium-chromium and magnesium-manganese, ferrites of fixed composition. The measuring apparatus and measurement procedure are described and an estimate of the errors is given. It is shown that due to quenching the gyrotropic properties of the ferrites are increased ( falls and _a increases), while the dielectric constant is unchanged. Quenching leads to an increase in the magnetic and dielectric losses.Translated from Izvestiya VUZ. Fizika, Vol. 11, No. 11, pp. 41–47, November, 1968.     

P-polarized nonlinear surface polaritons near the surface of a saturable self-defocusing medium: Threshold case

We have obtained the solution of the stationary problem for P-polarized nonlinear surface polaritons (NLSP) near the interface of two media, one of which is optically linear and the other having an optical nonlinearity with saturation and a dielectric function of the form: =_xx=_zz=₀+a|E|²/(1+b|E|²), where E is the amplitude of the electric field. On this basis the NLSP energy and propagation properties, the polarization structure and the localization depth of the NLSP field as well as the physically allowed region in the parameter space have been investigated for the case in which the parameter ₀ is positive, b is non-negative, and a and ₁ are negative (₁ is the dielectric function of the linear medium); ₀>|₁|.     

A new solution of Schmutzer's projective relativistic cosmology

Schmutzer's cosmological model on the basis of his projective unified field theory leads to a system of differential equations equivalent to a set of highly complicated Abel differential equations [1, 2]. This paper is concerned with the properties of this coupled system of differential equations. The main results of this paper are as follows, (i) We have found the explicit general solution of the cosmological equations for the case=±5/2,= ±1. (ii) The procedure of solving the general case arbitrary=0 is easily within this formalism, (iii) After having found the solution with arbitrary,=±1, one gets the corresponding solution= -, =±1. (iv) In general the coupled system of differential equations describing Schmutzer's cosmological model is equivalent to a single generalized Emden differential equation and it is identical to Emden's differential equation for special values of the parameter.     

One-dimensional harmonic lattice caricature of hydrodynamics

We derive the hydrodynamic (Euler) approximation for the harmonic time evolution of infinite classical oscillator system on one-dimensional lattice ¹ It is known that equilibrium (i.e., time-invariant attractive) states for this model are translationally invariant Gaussian ones, with the mean 0, which satisfy some linear relations involving the interaction quadratic form. The natural parameter characterizing equilibrium states is the spectral density matrix function (SDMF)F(), [– , ). Time evolution of a space profile of local equilibrium parameters is described by a space-time SDMFF(t;x, ) t, xR ¹. The hydrodynamic equation forF(t; x, ) which we derive in this paper means that the normal mode profiles indexed by are moving according to linear laws and are mutually independent. The procedure of deriving the hydrodynamic equation is the following: We fix an initial SDMF profileF(x, ) and a familyP ,>0 of mean 0 states which satisfy the two conditions imposed on the covariance of spins at various lattice points: (a) the covariance at points close to the value ^–1 x in the stateP is approximately described by the SDMFF(x, ); (b) The covariance (on large distances) decreases with distance quickly enough and uniformly in. Given nonzerotR ¹, we consider the states P _–1 ,>0, describing the system at the time moments ^–1 t during its harmonic time evolution. We check that the covariance at lattice points close to ^–1 x in the state P _–1 is approximately described by a SDMFF(t;x, ) and establish the connection betweenF(t; x, ) andF(x,).     

On the mechanism of the induced anisotropy of magnesium ferrites in the range of higher temperatures

A simple mechanism explaining not only the magnitude but also the type of induced anisotropy on the magnesium ferrite Mg_0·78 Fe_2·22 O_4·026 in the temperature range from 400 to 500°K has been designed. The experimentally estimated values of the microscopic bond energyl _p 7×10^–16 erg of the configuration contributing to theF-type anisotropy and the activation energy _exp = 1·1 eV are in good correspondence with the valuesl _d1·6×10^–16erg and _cal = 1·1₅ eV which have been calculated theoretically.Dedicated to Professor Dr. Jaromír Bro on his sixtieth birthday.The author would like to express his thanks to Dr. S. Krupika for valuable discussions and his interest in this paper.     

Static and dynamic properties of XY systems with extended defects in cubic anisotropic crystallines

Static and dynamic critical behavior ofXY systems in cubic anisotropic crystallines, with extended defects (or quenched nonmagnetic impurities) strongly correlated along _d -dimensional space and randomly distributed ind – _d dimensions, were studied. These extended defects make the systems coordinate anisotropic, resulting in unique critical behavior due to competition between the cubic anisotropy and the coordinate anisotropy. The systems were analyzed by an ^1/2 (4 – d) type of expansion with double expansion parameters based on a renormalization-group (RG) approach. Critical exponents were calculated near the second-order phase transition point and the behavior of the first-order transition was evaluated near the tricritical point.     

Exact solution of a three-component system on the honeycomb lattice

A model three-component system is considered in which the bonds of a honeycomb lattice are covered by rodlike molecules of typesAA, BB, andAB. The ends of molecules near a common lattice site interact with energies _AA, _BB, and _AB. The model is equivalent to an Ising model on the 3–12 lattice. Exact results are obtained for the two-phase coexistence curves in the isothermal composition plane.     

Accurate calculation of functional determinants

A dependence of the functional determinant of the operator from the family D() satisfying the condition D()=fD()+D()f on the parameter m² of infrared regularization is found in the regularization method using a generalized function.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 27–32, June, 1988.     

Sensitivity of approximate formulas for determining optical constants of thin films

The sensitivity of approximate formulas for determining the optical constants of thin films using measurement of reflectancesR and transmittancesT at normal incidence have been investigated theoretically. The ranges of refractive indexn, absorption indexk,2nk (=₂) andn ²–k ²(=₁) within relative errors of 5%, 10%, and 20% may be obtained. Selected signs of (₁)⁺ or (₁)^– have been determined. Validity of the condition n₀ A=n _s A has been also evaluated (A=1–R –T andA=1–R–T).     

Resonant shielding of an inhomogeneous gyrotropic plasma slab

Conclusions The problem of the incidence of a plane TM electromagnetic wave on an isotropic, symmetric, resonance plasma slab (n=2, 4, 6, ...), discussed in [1], was solved by an iteration method in a recent paper [6]. The physical results found there are the same as those of [1]. Zhivulin and Makarov [6] then applied the iteration method to the analogous problem of a gyrotropic resonance plasma slab [7]. The analysis in these papers furnishes a clearer mathematical justification of the results of [1] and the present paper and thus of the method used there. The present method, which satisfies only a physical condition of rigor, is preferable to the mathematically more rigorous methods (in particular, the iteration method) because of its simplicity, its graphic nature, and its clear physical meaning. It also answers many questions which cannot be answered in the more rigorous approach because of the serious difficulties which arise (and which have not yet been overcome).N. G. Denisov has called our attention to the fact that complete shielding was actually found previously by Rytov and Yudkevich [8], who treated the problem of the incidence of a plane TE electromagnetic wave on a slab with a dielectric constant (x)=₁ – A₁/(a – x)² for x<0. (x)=₂ – A₂/(b + x)² for x>0, and ₁ – A₁/(a² = ₂ – A₂/b² in the plane x=0. In the limita0, b0, they found results corresponding to a slab with a dielectric constant having a first-order pole; it is in this case that complete shielding is achieved. This method for obtaining the corresponding results is analogous to the method used in [1] and the present paper. We also note that the distribution of the effective dielectric constant (6) in the immediate vicinity of the pole—where the contribution of the last term. (1–u)x², can be neglected—is the same as the distribution adopted in [8] if we seta-b-0, ₁ = ₂, A₁=A₂=u.Scientific-Research Institute of Radiophysics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 19, No. 8, pp. 1130–1141, August, 1976.     

Precipitation hardening of alloys with structure modulated within the region of micro- and macroflow. I

The effect of precipitation of phase Co₃Ti on the change in mechanical properties, measured within the range of micro ( - 10^§-1), and macroflow ( = 10^–3) was studied at various stages of decomposition of the Co-Ni-Ti and Co-Ni- Ti-Al alloys. It was shown that in the region of microdeformation, a parabolic dependence () is observed, and the dependence of resistance to deformation on the grain size is expressed by Petch equation. It was shown that theoretical estimations with the use of Gerold -Haberkorn and Gleiter-Hornbogen theories are in agreement with the experimentally observed changes in macroscopic yield stress during the process of precipitation of Co₃Ti phase in the studied alloys.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 46–52, September, 1972.     

Kinetic theory of adsorption and desorption

In this paper we use stochastic methods to discuss adsorption and desorption. The paper derives generalized coefficients of sticking and accomodation depending on surface temperatureT _s and gas temperatureT _g and shows, that for additive Markov processes, these kinetic coefficients are identical. Furthermore, exact solutions of the kinetic equations for certain simple transition probabilitiesP(, ) are found and an approximation method for more complicatedP(, ) is given. The comparison of the theory with experimental results for noble gas-metal systems indicate a quadratic relationship between the first moment of the transition probabilityP(, ) and the well depth of the physisorption system.