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991.
Intermetallic compounds capable of absorbing large amounts of hydrogen attract attention due to their applied significance in the production of chemical power sources. A variety of such compounds have been studied. The present paper gives some examples of hydrogen-absorbing intermetallides and describes their preparation, as well as touches upon some problems of hydride-forming alloys. The survey covers results obtained over the past decade. 相似文献
992.
Consider a problem of minimizing a separable, strictly convex, monotone and differentiable function on a convex polyhedron generated by a system of m linear inequalities. The problem has a series–parallel structure, with the variables divided serially into n disjoint subsets, whose elements are considered in parallel. This special structure is exploited in two algorithms proposed here for the approximate solution of the problem. The first algorithm solves at most min{m, ν − n + 1} subproblems; each subproblem has exactly one equality constraint and at most n variables. The second algorithm solves a dynamically generated sequence of subproblems; each subproblem has at most ν − n + 1 equality constraints, where ν is the total number of variables. To solve these subproblems both algorithms use the authors’ Projected Newton Bracketing method for linearly constrained convex minimization, in conjunction with the steepest descent method. We report the results of numerical experiments for both algorithms. 相似文献
993.
S. I. Nefedkin M. A. Klimova E. A. Kolomeitseva M. K. Klochnev E. E. Levin O. A. Petrii 《Russian Journal of Electrochemistry》2017,53(3):284-291
Disperse catalytic compositions for water electrolysis in electrolyzers with a solid polymer electrolyte were obtained by magnetron sputtering of C–Pt and Mo–Ir sectional targets. The catalysts were studied by X-ray diffraction analysis, electron microscopy, and voltammetry. The synthesized Pt–С and Ir–Mo catalysts with lowered contents of the precious component were subjected to prolonged trials in an electrolysis cell with a solid polymer electrolyte and showed high activity and stability. 相似文献
994.
995.
This paper presents a new method for the analysis of convergence and smoothness of univariate nonuniform subdivision schemes. The analysis involves ideas from the theory of asymptotically equivalent subdivision schemes and nonuniform Laurent polynomial representation together with a new perturbation result. Application of the new method is presented for the analysis of interpolatory subdivision schemes based upon extended Chebyshev systems and for a class of smoothly varying schemes. 相似文献
996.
A decelerated flow in a supersonic boundary layer containing a heat source modeling an electric discharge is studied numerically.
Calculations are performed for a wide range of the source power. The possibility of controlling the boundary layer separation
is demonstrated. The boundary layer separation on cooled walls is found to occur substantially later than on thermally insulated
walls. 相似文献
997.
Nanosecond laser flash photolysis technique is used to study the formation and decay kinetics of covalently linked triplet radical pairs (RP) formed after photoinduced electron transfer in the series of 21 zinc porphyrin—chain—viologen (Pph—Spn—Vi2+) dyads, where the number of atoms (n) in the chain increases from 2 to 138. In poorly viscous polar solvents (acetone, CHCl3—CH3OH (1 : 1) mixture), the dependence of the rate constant of RP formation on n can be described by the equation k
e = k
e
0
n
–a at k
e
0 = 2.95·108 s–1 anda = 0.8. In the zero magnetic field, the RP recombination rate constant (k
r(B = 0)) is significantly lower than k
e and ranges from 0.7·106 to 8·106 s–1. The dependence of k
r(B = 0) on n is extreme. The dependence k
r(B = 0) reaches a maximum at n = 20. In the strong magnetic field (B = 0.21 T), the significant retardation of triplet RP recombination is observed. The chain length has an insignificant effect on k
r(B = 0.21 T), which ranges from 0.3·106 to 0.9·106 s–1. The regularities found are discussed in terms of the interplay of molecular and spin dynamics. 相似文献
998.
999.
Daniel Levin 《Archiv der Mathematik》2002,79(6):515-519
We consider two quadratic forms on a class of manifolds conformally equivalent to the euclidean space. We give necessary and
sufficient conditions for the equivalence of these quadratic forms in terms of a weighted Hardy inequality.
The research was supported by the Chateaubriand Scholarship 2000–2001. 相似文献
1000.
E. E. Vdovin Yu. N. Khanin A. V. Veretennikov A. Levin A. Patane Yu. V. Dubrovskii L. Eaves P. C. Main M. Henini G. Hill 《JETP Letters》2001,74(1):41-45
We present an experimental study of electron wave functions in InAs/GaAs self-assembled quantum dots by magnetotunneling spectroscopy. The electronic wave functions have a biaxial symmetry in the growth plane, with axes corresponding to the main crystallographic directions in the growth plane. Moreover, we observed the in-plane anisotropy of the subbands of the quantum well. 相似文献