Short range order in (Ni65Fe35)77B23 metallic glass by neutron diffraction

The S(Q) structure factor of (Ni₆₅Fe₃₅)₇₇B₂₃ metallic glass was measured by time-of-flight neutron diffraction up to 24 Å^?1 momentum transfer. The distribution of transition metal-boron and transition metal-transition metal first neighbour atom pairs is resolved in the distribution function obtained from S(Q) by Fourier transformation. The distances of these first neighbours pairs, the width of their distribution, the partial coordination numbers and the short range order parameter are given. The results on (Ni₆₅Fe₃₅)₇₇B₂₃ and on the previously studies Fe₈₁B₁₉ amorphous alloys are compared.     

111In(111Cd) quadrupole interaction in the chalcogenide spinel CdCr2Se4

The¹¹¹Cd quadrupole coupling in the spinel CdCr₂Se₄ is investigated by TDPAC after different sample treatments. The experiments are consistent with Se vacancies causing the non-cubic probe environments and with the assumption that the majority of the¹¹¹In atoms are positioned at A-sites.     

Measurement of the electron distribution function in flowing afterglow plasma by means of Langmuir probe

Conclusion In the present report an attempt has been made to use the second derivative method for measurements of the electron distribution function in flowing afterglow plasma. It has been shown that using the cross-correlation technique, this method seems to be a useful tool for flowing afterglow plasma investigation.     

Thermionic energy converter in magnetic field

The paper deals with the influence of a magnetic field on the function of a thermionic energy converter. It derives a relation for the effect of the magnetic field on the converter current in a diffusion regime and gives measurements for a quasi-vacuum and diffusion regime of the converter.     

пРИМЕНЕНИЕ МЕтОДА ОтНОшЕНИь к ОпРЕДЕДЕНИУ сОстАВльУЩЕИ σx НАпРьжЕНИь

In this paper the possibility is analyzed of using the ratio method to determine the biaxial stress component _x in an arbitrary direction from two photographs, one taken with the primary beam incident perpendicularly and rotating film holder and the second photograph with the primary beam incident obliquely and film holder stacionary or oscillating in a small angular range. A relation is derived for the value of _x based on measurements of the diameters of the diffraction circles in the corresponding azimut, and a relation for estimating the magnitude of the percentual error of the value of _x thus determined as compared with the real value of _x .It is shown in the case of aluminium in three typical stress states (circularly symmetrical stress distribution, unaxial state, torsional stress) that the error in determining _x , caused by using the ratio method, is quite unimportant for application in technical practice and is much smaller than when applying the ratio methods to the determination of the sum of the two principal stresses from one photograph taken with the primary beam incident perpendicularly. The application of the ratio method for determining _x gives simultaneously the possibility of using this method for solving the general problem, i.e. of determining the two principal stresses as to their magnitude and direction.     

Parametrized convolutionless Generalized-Master-Equation approach to the exciton and electron propagation in the Agranovich and Galanin model

Expressing the influence of reservoirs (lattice modes, solvent etc.) on the exciton or electron propagation in homogeneous systems via two relaxation times in the Agranovich and Galanin model, the convolutionless Generalized Master Equations for the site occupation probabilities are derived. Two different projection operator techniques are used. Identity of the two approaches is verified for a dimer and physical contents of the result are discussed.     

On the hardening in modulated structure

Hardening in modulated structure is evaluated using the periodic approximation. The critical shear stress increment due to the periodic structure is calculated in the constant line energy approximation. The results are applicable to any periodic structure (concentration waves must be neither homophase nor symmetric) exerting on the dislocation local glide forces with an amplitude smaller than ( denotes the line energy of corresponding straight dislocation directed along the concentration variations with the wave vector). In the zero approximation, the critical forceb is then simply the glide force on the straight dislocation averaged along its length in its most hardened position.     

Bull-free Berge graphs are perfect

Abull is the (self-complementary) graph with verticesa, b, c, d, e and edgesab, ac, bc, bd, ce; a graphG is calledBerge if neitherG not its complement contains a chordless cycle whose length is odd and at least five. We prove that bull-free Berge graphs are perfect; a part of our argument relies on a new property of minimal imperfect graphs.This work was done while both authors were at the School of Computer Science, McGill University; support by NSERC is gratefully acknowledged.     

Estimation of density functions by order statistics

The properties of the empirical density function,f _n(x) = k/n( _j ⁺ – _j-1 ⁺ ) if _j-1 ⁺ < x ⁺ where _j-1 ⁺ and _j ⁺ are sample elements and there are exactlyk – 1 sample elements between them, are studied in that practical point of view how to choose a suitablek for a good estimation. A bound is given for the expected value of the absolute value of difference between the empirical and theoretical density functions.     

Extensions of Szegö's theory of orthogonal polynomials,III

Let {ø _n (dμ)} be a system of orthonormal polynomials on the unit circle with respect to a measuredμ. Szegö's theory is concerned with the asymptotic behavior ofø _n (dμ) when logμ′∈L ¹. In what follows we will discuss the asymptotic behavior of the ratioø _n (dμ ₂)/ø _n (dμ ₁) on the unit circle whendμ ₁ anddμ ₂ are close in a sense (e.g.,dμ ₂=gdμ ₁, where g≥0 is such thatQ(e ^it )g(t) andQ(e ^it )/g(t) are bounded for a suitable polynomialQ) and μ ₁ ^′ >0 almost everywhere or (a somewhat weaker requirement) lim _n→∞Φ _n (dμ ₁,0)=0 for the monic polynomial Φ _n . The asymptotic behavior of the same fraction outside the unit circle was discussed in an earlier paper.