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  • Determination of critical stresses in shells of high flexibility

    The article is considered the wall stability of a steel cylindrical pre-stressed granary, compressed by the friction forces of grain and shell, taking into consideration the influence of the grain internal pressure, its elastic resistance from the inside and the elastic resistance of the pre-stressed shell outside. In this case, the initial and subcritical deflection of the shell is assumed to be axisymmetric, and the loss of the shell stability occurs with the formation of asymmetric deflection. The given solution of the problem allows to determine the magnitude of the critical efforts taking into consideration the influence of the grain internal pressure, its elastic repulsion, the magnitude of the initial deflections and the ratio of shell dimensions.

    Keywords: stability calculation, wall stability, prestressing, internal lateral pressure, elastic rebound

  • Methodology for the deployment of dual-use military infrastructure facilities and a model for optimizing the deployment of a service network

    The article discusses the methodology for deploying dual-purpose military infrastructure facilities, including a model for optimizing the placement of the service network in garrisons, where it has already developed, and the question is its reconstruction and expansion. The calculations are made on the example of service in military camps. To optimize the placement of the service network, a criterion is adopted to minimize the service time.

    Keywords: garrison service, service network, service center, hierarchy, gravity model of gravity, the theory of central places, commodity circulation, a military town

  • Calibtating tempered stable Levy models to data of cryptocurrencies Bitcoin and Ethereum

    In the paper, we consider the problem of modeling the dynamics of leading cryptocurrencies such as Bitcoin (BTC) and Etherium (ETH). We calculate the log-returns based on the time series of cryptocurrency rates and analyze the realized power variation to estimate the corresponding generalized Blumenthal-Getoor index. The analysis shows that tempered stable Levy processes without a diffusion component are suitable for modeling the cryptocurrency rates considered. To obtain a more accurate estimate of the parameter that describes the activity of jumps in the log-returns, we exclude the influence of drift by considering auxilary series of increments of the initial log-returns.

    Keywords: mathematical modeling, cryptocurrencies, Levy models, Tempered Stable Levy models, CGMY modes, Blumenthal-Getoor index, realized power variation