Simulating the Kinematic Dynamo Forced by Heteroclinic Convective Velocity Fields

We report on the integration of the kinematic dynamo problem in a spherical domain forced by velocity fields that are convective fluid flows resulting from a bifurcation analysis of the spherical Bénard problem. We derive a code based on generalized spherical harmonics that ensures a divergence-free magnetic field. We determine the growth or decay of a magnetic field in the kinematic dynamo equation for various physically relevant velocity fields which are stationary as well as time-periodic and chaotic. Velocity signals that are produced by heteroclinic cycles are used as an input to an energy-saturated kinematic dynamo equation that limits the growth of the linearly unstable modes. Preliminary calculations indicate the possibility of reversals of the magnetic field for this case of forcing. Received 8 October 1996 and accepted 28 April 1997     

A generalised model and calculation of the hyperfine interaction constant for anomalous muonium in the crystalline lattice of silicon

A new microscopic model of anomalous muonium for the elemental semiconductors is proposed. The relevant configuration consisting of both a diamagrentic molecule Si−Mu and an unpaired orbital e⁻ is contained into a semivacancy of the real lattice. By using the unrestricted Hartree-Fock computational method the principal properties of the system are established. A dynamical version of the model together with a question on the formation of such system are discussed.     

The exactly resolved nonlattice model of random media based on Markov walks with a stable law for jumps

A random-medium model which is a correlated distribution of points (particles) randomly positioned in the 3-dimensional space is considered. The construction of the medium starts from a noncorrelated (Poisson) distribution of parent particles, each of them initiates a finite Markov chain of its descendants. The complete collection of correlation functions of all orders within the scope of the model have been obtained. The use of the 3-dimensional stable law (Lévy law) as a transition probability allows us to present the correlation function in an explicit form. Proceedings of the XVII Seminar on Stability Problems for Stochastic Models, Kazan, Russian, 1995, Part II.     

Linear systems of arbitrary genus

Kalman's theory is extended to a complete, smooth, and irreducible algebraic curve of arbitrary genus.     

Resistance of composite flywheel rim to radial tensile stresses from centrifugal forces based on results of pure bending of a rim segment

A method is proposed for evaluating the resistance of a flywheel rim to radial stresses in free rotation. The method is based on loading a rim segment in pure bending and calculating the limiting moment and the corresponding limiting angular velocity. Applicability of the method is substantiated theoretically by investigating the similarity of the radial stress diagrams in rotation and pure bending. The method is verified experimentally for the strained state of a rim segment in pure bending.Translated from Mekhanika Kompozitnykh Materialov, Vol. 29, No. 4, pp. 521–526, July–August, 1993.     

Hamiltonian and recursion operators for two-dimensional scalar fields

The equation for the Noether operator is obtained. It gives the necessary conditions for complete integrability of the field equations. For several double-component models the Hamiltonian pairs and the recursion operators are presented.     

Gelation of poly(n-butylisocyanate) in benzene

Poly (n-butylisocyanate)-benzene solutions prepared by solubilization at 45°C, followed by aging at room temperature were found to be metastable for months, although, eventually, they separated into a birefringent polymer-rich phase and an isotropic solution. These metastable solutions, as well as isothermally phase-separated biphasic samples, flowed and exhibited dynamic moduli indicative of low polymer connectivity. By contrast samples prepared by a freeze-thaw cycle were uniformly and highly birefringent and showed network (gel) behavior at room temperature. The mechanism of gel formation is most likely the exclusion of the polymer from the benzene crystal during crystallization, forcing the polymer to align and exist at grain boundaries. Films formed from solutions have different moduli than those formed from gels, and are consistent with the proposed mechanism.     

Penetration of a rigid cone into a plastic orthotropic half space

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 159–163, September–October, 1991.     

High performance liquid chromatography as a tool in the definition of abnormalities in monoamine and tryptophan metabolites in cerebrospinal fluid from patients with neurological disorders

In this study we report the levels of 3-methoxy-4-hydroxyphenylglycol, 3,4-dihydroxyphenylacetic acid, homovallinic acid, tryptophan, 5-hydroxyindole-3-acetic acid and serotonin in lumbar cerebrospinal fluid (CSF) from patients with multiple sclerosis, cerebrovascular disease and muscular tension headache the later, as healthy controls. The separation of these substances was performed on a reversed phase column by ion pair high performance liquid chromatography and detection was made by a glassy carbon electrode set at +900 mV vs Ag+/AgCl. The whole separation was achieved within 25 min. Concentrations of all substances (10-1000 pmole/L) were linearly proportional to areas obtained. The system is sensitive, stable and reproducible. The significance of CSF levels of these metabolites from patients groups compared with healthy controls are discussed.