Optimal Resource Consumption Control with Interval Restrictions

Some method is developed for calculating the optimal resource consumption control with interval restrictions on the components of the control vector. The approach is based on the sequential adjustment of the values of a quasioptimal control actions up to their limit values. The connection is found between the deviations of the initial conditions of the adjoint system and the deviations of the values of the quasioptimal control from the limit values. The rule for specifying the initial approximation is given, and the specific features of the rule are noted. An iterative algorithm is developed, and an example is given.     

Preservation of stability under discretization of systems of ordinary differential equations

We study the stability preservation problem while passing from ordinary differential to difference equations. Using the method of Lyapunov functions, we determine the conditions under which the asymptotic stability of the zero solutions to systems of differential equations implies that the zero solutions to the corresponding difference systems are asymptotically stable as well. We prove a theorem on the stability of perturbed systems, estimate the duration of transition processes for some class of systems of nonlinear difference equations, and study the conditions of the stability of complex systems in nonlinear approximation.     

Bulk model of rapid thermal oxidation of silicon

A model of rapid thermal oxidation of silicon in dry oxygen based on the reaction of volume oxidation is constructed. It is assumed that the coefficient of oxygen diffusion for silicon dioxide decreases because of internal compressive stress, which is at a maximum near the SiO₂-Si interface; as the distance from the interface increases, this stress decreases according to the time-dependent exponential law because of viscoelastic relaxation from the value of the diffusion coefficient for strained oxide to that for fused quartz. The characteristic relaxation time of the coefficient of oxygen diffusion in silicon dioxide correlates with the relaxation time of internal stress in silicon dioxide films on silicon and with the relaxation time of the refraction index. Because the refraction index is related to the density of silicon dioxide, we arrive at the conclusion that the relaxation of the diffusion coefficient is related not only to the relaxation of internal mechanical stress, but also to the relaxation of the density of silicon dioxide.     

Frequency-domain criteria for the global stability of phase synchronization systems

New criteria for the global stability of phase synchronization systems are formulated and proved. The efficiency of the criteria for phase-locked loops is demonstrated.     

Influence of the nature of organic ligands on the character of thermal decomposition products of CoII and NiII pivalate complexes with amino derivatives of pyridine

The thermal stability and the solid-state thermal decomposition of the known mononuclear cobalt(II) and nickel(II) complexes [H₂N(C₅H₃N)N(H)C(Me)=NH]M(OOCBu^t)₂, [(NH₂)₂C₆H₂Me₂]₃M(OOCBu^t)₂ and the new compounds L₂M(OOCBu^t)₂ (L = = (2-NH₂)C₅H₃N, (2-NH₂)(6-Me)C₅H₃N), and [(2,6-NH₂)₂C₅H₃N]₂Ni(OOCBu^t)₂ were studied by differential scanning calorimetry and thermogravimetric analysis. Efficient methods were developed for the synthesis of these complexes. The mononuclear complexes are thermally quite stable. The thermal stability of the complexes depends on the nature of the ligand and decreases in the series (2,6-NH₂)₂C₅H₃N > H₂N(C₅H₃N)NHC(Me)=NH > (NH₂)₂C₆H₂Me₂ > (2-NH₂)C₅H₃N > (2-NH₂)(6-Me)C₅H₃N. The nickel(II) complexes are thermally more stable than the related cobalt(II) complexes. The thermolysis (<500 °C) of Co and Ni pivalates is a destructive process. The phase composition of the decomposition products is determined by the nature of metal and coordinated ligands.     

The structure and adsorption properties of amorphous linear-chain carbon

A highly effective adsorbent based on linear-chain carbon is studied by infrared spectroscopy, Raman spectroscopy, X-ray microanalysis, and X-ray diffraction analysis. The structure and the properties of amorphous linear-chain carbon are investigated.     

Application of ion implantation for the modification of silicon-on-sapphire epitaxial systems,their structure,and properties

Articles devoted to methods for improving the structural quality of epitaxial films, which utilize the high-temperature interaction between hydrogen and silicon as well as solid-phase recrystallization process, are reviewed. A correlation between the quality of the epitaxial layer and the radiation resistance of the microcircuits obtained thereon is also considered. A method for creating capture/recombination centers in sapphire during the implantation of helium ions is proposed, yielding high-quality radiation-resistant silicon-on-sapphire films.     

New fluorescent 2-(5-acetoacetyl-2-furyl)-benzazoles with prochiral methylene group protons

New fluorescent benzazoles containing prochiral protons in the methylene group have been synthesized. Their spectral-absorption and fluorescent properties have been investigated. Quantum yields of fluorescence were 0.39–0.55. The long-wave absorption band and the emission band in the spectra of the obtained acetoacetyl furylbenzazole derivatives are caused by electronic transition with charge transfer between the benzazole and acetoacetylfuryl fragments.