Methods and software for cosmic ray scintillation studies

The principal instrument used in cosmic ray scintillation studies is the spectra constructed from intensive observation. This method has its drawbacks in that the statistical characteristics of the process undergo essential reconstruction, i.e., the process becomes nonstationary from the viewpoint of such phenomena as Forbush decrease and during solar flares. The software used to process the above includes the direct Fourier transform and its modifications, autoregressive processes, and instantaneous spectrum methods. Used in various combinations, they prove helpful in handling the time series

Study of cosmic ray scintillations from 5-minute data of the scintillations telescope Izmran and world-wide network stations

During cosmic ray propagation in interplanetary space there appear characteristic cosmic-ray intensity scintillations which are due to charged particle scattering on random inhomogeneities of the interplanetary magnetic field. The power spectra of cosmic ray scintillations on the Earth during some intervals from 1977 to 1982 (for quiet periods, for solar flares and Forbush decreases due to power shock waves) have been calculated from five-minute, one and two-hour values of the cosmic-ray intensity measured by the scintillator supertelescope IZMIRAN. The spectra were estimated by the methods of spectral analysis and by autoregressive methods which mutually control each other and make it possible not only to analyze scintillation powers at distinguished frequencies, but also to determine the behavior of spectrum slopes in some frequency ranges

On Robustness of Discrete Time Optimal Filters

A new result on stability of an optimal nonlinear filter for a Markov chain with respect to small perturbations on every step is established. An exponential recurrence of the signal is assumed

Large Deviations Analysis for Distributed Algorithms in an Ergodic Markovian Environment

We provide a large deviations analysis of deadlock phenomena occurring in distributed systems sharing common resources. In our model transition probabilities of resource allocation and deallocation are time and space dependent. The process is driven by an ergodic Markov chain and is reflected on the boundary of the d-dimensional cube. In the large resource limit, we prove Freidlin-Wentzell estimates, we study the asymptotic of the deadlock time and we show that the quasi-potential is a viscosity solution of a Hamilton-Jacobi equation with a Neumann boundary condition. We give a complete analysis of the colliding 2-stacks problem and show an example where the system has a stable attractor which is a limit cycle

Prediction of interplanetary shock waves using cosmic ray fluctuations

En el trabajo se propone usar métodos espectrales y autorregresivos para mejorar los procesos de detección de variaciones en la composición espectral de la intensidad de rayos cósmicos y de la componente Bz del campo magnético interplanetario. Usando esta metodología, se determinaron algunas regularidades en la variación del espectro de potencias de la intensidad de los rayos cósmicos antes del arribo de una onda de choque a la Tierra. Así, el arribo de la onda de choque es precedido por la aparición de una onda con período de 4 a 8 horas en el espectro de potencias de la componente Bz del campo magnético. Los resultados confirman la posibilidad de usar los rayos cósmicos y la actividad geomagnética para el diagnóstico del medio interplanetario y la predicción del arribo de ondas de choque a la Tierra, con una anticipación de 1 a 2 días. doi: https://doi.org/10.22201/igeof.00167169p.1998.37.2.39