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The existence and identification of chaos regarding in-plane pitch motions of tethered satellite systems are scientific problems of concern, and are directly related to normal system operations in the station-keeping phase. This paper studies the effect of microamplitude longitudinal oscillation on the occurrence of chaos in a tethered system subjected to atmospheric perturbations. Based on a simplified rod model that considers tether elasticity and satellite masses, the Melnikov method is used to identify a criterion that can predict chaos, and a chaotic zone is further proposed to recognize the relationship between the chaos and system parameters. Then the cell mapping method is used to describe the system's global dynamic behaviors, including chaos. A discrete model of the flexible system that consists of particles connected by massless springs and satellite rigid bodies is structured so that more accurate dynamic simulations can be used to verify the theoretical analysis. Finally, numerical examples demonstrate that the chaotic zone and criterion expression are useful tools for revealing chaos. The relationship between the dynamics and system parameters is also assessed. The results of the simplified model agree with those of the sophisticated model. • A chaotic criterion and a chaotic zone on a tethered satellite system are proposed. • The relationship between the dynamics and system parameters is estimated. • The global dynamic characteristics of the system are revealed via cell mapping. [ABSTRACT FROM AUTHOR]

Gas escape features are a common presence on any young sedimentary basins where large amounts of organic-rich sediments are deposited within a short time. The fast burial process conducts to maturation and carbonization of the sedimentary organic matter by bacterial and, later, by temperature transformations. The Black Sea is one such basin, where numerous shallow gas accumulation and gas escape features were observed and analyzed, ranging from gas hydrates, gas chimneys, flares, and mud volcanos. The study of such geological phenomena is important for identifying present seabed geohazards, and nonetheless for hydrocarbon exploration. Our study integrates newly acquired 2D high-resolution seismic lines, further used to correlate the gas escape features and their relationship with deep-seated faults, such as Peceneaga-Camena, and petroleum system of the Romanian Black Sea Shelf area. Our results show that in the studied area the gas escape features are confined into the Pliocene-Quaternary sequence, hence not related to Peceneaga-Camena Fault or to a deeper thermogenic petroleum system, and most probably, the gas is sourced from the shallower biogenic system. [ABSTRACT FROM AUTHOR]