A manifestation of magnetism of bismuth in iron garnet films

Bismuth iron garnet films prepared through electron-beam and laser-induced evaporation on (001)-oriented substrates of scandium gallium gadolinium garnet are investigated using ferromagnetic resonance. It is assumed that the additional minima observed in the angular dependence of the resonance field can be associated with the magnetic moment of bismuth ions.     

Organylthiochloroacetylenes: IX. Reactions with geminal and vicinal dithiols

Alkylthiochloroacetylenes react with geminal (in ether) and vicinal (in THF) dithiols to form, respectively, functional 1,3-dithiolenes (yield 43%) or 1,3-dithiolanes (yield 34%).     

Measurement of the $b\overline{b}$ production cross section in 920 GeV fixed-target proton-nucleus collisions

Using the HERA - B detector, the production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The production was tagged via inclusive bottom quark decays into by exploiting the longitudinal separation of decay vertices from the primary proton-nucleus interaction. Both e ⁺ e ^- and channels have been reconstructed and the combined analysis yields the cross section . Received: 6 June 2002 / Revised version: 2 September 2002 / Published online: 8 November 2002     

Duality theorems for convex problems with time delay

In this paper, we examine a class of convex problems of Bolza type, involving a time delay in the state. It encompasses a variety of time-delay problems arising in the calculus of variations and optimal control. A duality analysis is carried out which, among other things, leads to a characterization of minimizers in terms of the Euler-Lagrange inclusion. The results obtained improve in significant respects on what is achievable by techniques previously employed, based on elimination of the time delay by introduction of an infinite-dimensional state space or on the method of steps.     

Coherentization of the energy of heat fluctuations by a two-channel bilinear control system

We propose and investigate a mathematical model of an open bilinear control system for the conversion of heat energy in a coherent form. We show that the use of a combinational parametric resonance formed by the control system in a one-temperature ensemble of weakly dissipative elastic-gyroscopic subsystems enables one to obtain a positive energy output without using any cooling device apart from the control system. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 11, pp. 1557–1573, November, 2007.     

Automorphisms of the semigroup of invertible matrices with nonnegative elements

In this paper, we prove that every automorphism of the semigroup of invertible matrices with nonnegative elements over a linearly ordered associative ring on some specially defined subgroup coincides with the composition of an inner automorphism of the semigroup, an order-preserving automorphism of the ring, and a central homothety. __________ Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 2, pp. 3–23, 2005.     

Necessary first-order conditions for optimal crossing of a given region

We consider a nonlinear optimal control problem with an integral functional in which the integrand is the characteristic function of a closed set in the phase space. An approximation method is applied to prove the necessary conditions of optimality in the form of a Pontryagin maximum principle without any prior assumptions on the behavior of the optimal trajectory. Similarly to phase-constrained problems, we derive conditions of nondegeneracy and pointwise nontriviality of the maximum principle. __________ Translated from Nelineinaya Dinamika i Upravlenie, No. 4, pp. 179–204, 2004.