MIREA - Russian Technological University

New model of the waveguide structure based on the graded-index photonic crystal structure with attenuating refractive index with a distance and nonlinear crystal with the Kerr-type nonlinear response disappearing with an increase in the light intensity is proposed. Both cases of the sign of the Kerr nonlinearity coefficient corresponding to the disappearance of self-focusing and defocusing nonlinearity are considered. New exact solutions to the nonlinear contact boundary problem in explicit form are found. The light intensity distribution using obtained exact analytical solutions are described and analyzed with variation of the optic structure parameters. Two types of the transverse distribution of the light intensity corresponding to the surface wave characterized by one maximum, and monotonic attenuation in field with a distance from the interface and the waveguide modes characterized by several intensity peaks formed in graded-index photonic crystal structure are described by obtained exact solutions. It is shown that formation of the waveguide modes occurs with an increase in the interface dielectric constant.

Scene graph generation provides a compact structured representation for visual perception, but accurate and fast graph prediction from images and videos remains challenging. Recent VLM-based methods can generate scene graphs end-to-end as structured text, yet often produce long outputs with irrelevant objects and relations. We present SceneGraphVLM, a compact method for image and video scene graph generation with small visual language models. SceneGraphVLM serializes graphs in a token-efficient TOON format and trains the model in two stages: supervised fine-tuning followed by reinforcement learning with hallucination-aware rewards that balance relation coverage and precision while penalizing unsupported objects and relations. For videos, the model can optionally condition each frame on the previously generated graph, providing lightweight short-term context without tracking or post-processing. We evaluate SceneGraphVLM on PSG, PVSG, and Action Genome. With compact VLMs and vLLM-accelerated decoding, SceneGraphVLM achieves a strong quality-speed trade-off, improves precision-oriented SGG metrics while preserving reasonable recall, and generates complete scene graphs with approximately one-second latency. Code and implementation details are available at: https://github.com/markus0440/SceneGraphVLM.git.

The newly formulated non-Newtonian rivulet flows streaming down an inclined planar surface, with additional periodic perturbations arising from the application of the 2nd Stokes problem to the investigation of rivulet dynamics, are demonstrated in the current research. Hereby, the 2nd Stokes problem assumes that the surface, with a thin shared layer of the fluid on it, oscillates in a harmonic manner along the x-axis of the rivulet flow, which coincides with the main flow direction streaming down the underlying surface. We obtain the exact extension of the rivulet flow family, clarifying the structure of the pressure field, which fully absorbs the arising perturbation. The profile of the velocity field is assumed to be Gaussian-type with a non-zero level of plasticity. Hence, the absolutely non-Newtonian case of the viscoplastic flow solution, which satisfies the motion and continuity equations, is considered (with particular cases of exact solutions for pressure). The perturbed governing equations of motion for rivulet flows then result in the Riccati-type ordinary differential equation (ODE), describing the dynamics of the coordinate x(t). The approximated schematic dynamics are presented in graphical plots.

This study investigated two groups of surgical suture materials—nonabsorbable (polyethylene terephthalate, polyamide, and silk) and absorbable (glycolic/lactic acid copolymer)—before and after accelerated aging. The analysis employed tensile strength testing, Fourier-transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). Following domestic and international standards for polymer aging, the samples were subjected to the following initial accelerated aging conditions: 168 days at 50°C, 84 days at 60°C, and 42 days at 70°C. The results demonstrate that accelerated aging does not alter the chemical or phase structure of the nonabsorbable sutures. Their strength properties complied with the relevant standard requirements, which supports the suitability of these test conditions for such materials. However, not all initial test conditions suit absorbable sutures because these fibers lose a significant portion of their strength because of pronounced chemical and physical changes. FTIR and DSC data support the use of more moderate accelerated-aging conditions for absorbable sutures.

This paper uses methods of systems analysis, modeling, and fuzzy logic to address the problem of assessing cyber risks at oil and gas enterprises. Fuzzy cognitive maps are used to formalize the cause-and-effect relationships between vulnerabilities, attack vectors, protective measures, and possible consequences. The application of fuzzy logic is also justified by the uncertainty inherent in technological processes in the context of cyber threats. This article proposes a fuzzy cognitive model in which the weight coefficients of the relationships are specified by experts based on a linguistic scale. The model's dynamics are described by a recurrent equation with a hyperbolic cosine as the activity function, ensuring smooth dynamics and normalization of values. Simulation results show that the fuzzy cognitive model allows comparison of scenarios of various cyber attacks, identification of connections that amplify the propagation of failures across infrastructure levels of an oil and gas enterprise, and evaluation of the effectiveness of protective measures. A generalized scheme for constructing a fuzzy cognitive map based on expert assessments is presented. The proposed model can be applied during the planning stage of countermeasures against cyber attacks at enterprises in the oil and gas industry.