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Control of chaotic oscillations of a satellite

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Applied Mathematics and Mechanics(English Edition) 2007年第7期28卷 893-900页

作者： alexey Bobtsov Nikolay Nikolaev Olga Slita Department of Control Systems and Informatics Saint-Petersburg State University of Information Technologies Mechanics and OpticsKronverksky Ave.49Saint-Petersburg197101Russia

Analytical conditions and practical methods of their realization are proposed to solve a problem of a command signal tracking for a nonlinear disturbed system. Nonlinear disturbed plants consisting of linear dynamic block and nonlinear block in feedback are considered. Nonlinear part of the plant and disturbance are unknown and bounded. The paper illustrates a possibility of applications of proposed algorithms to control libration angle of satellite.

关键词： adaptive control chaotic behaviour satellite control nonlinear stabilization nonlinear control output control

Assessment of the Design Displacement Values at Seismic Fault Crossings and of Their Excess Probability

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Journal of Mountain Science 2011年第2期8卷 228-233页

作者： STROM Alexander IVASCHENkO alexey kOZHURIN Andrey Institute of Geospheres Dynamics of Russian Academy of Sciences Institute of Oceanology of Russian Academy of Sciences Geological Institute of Russian Academy of Sciences

Line structures such as pipelines that cross active faults should be designed to retain leak-tightness if the design displacement (Ddesign) occurs. Principal approaches to the Ddesign and rupture kinematics assessment are described. They are based on relationships between earthquake magnitude, rupture length and displacement, and on the detailed field data on a specific fault that crosses the pipeline route. Since the future offset at the crossing may exceed the design value, the probability of a displacement occurrence where the safety of the structure can not be ensured should be estimated. Assessment method on such event probability is described and exemplified through active fault studies carried out at several pipeline projects in Russia.

关键词： Active Fault Surface Rupture Design Displacement Pipeline Sakhalin Island

Stress dependence of elastic wave dispersion and attenuation in fluid-saturated porous layered media

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Science China Earth Sciences 2023年第11期66卷 2622-2634页

作者： Fubin CHEN Zhaoyun ZONG Xingyao YIN alexey STOVAS National key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580China Laoshan Laboratory Qingdao 266580China Centre for Exploration Geophysics Curtin UniversityGPO Box U1987PerthWA 6845Australia Department of Geoscience and Petroleum Norwegian University of Science and Technology(NTNU)Trondheim 7031Norway

The fluid-saturated porous layered(FSPL)media widely exist in the Earth's subsurface and their overall mechanical properties,microscopic pore structure and wave propagation characteristics are highly relevant to the in-situ ***,the effect of in-situ stress on wave propagation in FSPL media cannot be well explained with the existing *** fill this gap,we propose the dynamic equations for FSPL media under the effect of in-situ stress based on the theories of poroacoustoelasticity and anisotropic *** loss mechanism is considered to account for the stress-dependent wave dispersion and attenuation induced by global wave-induced fluid ***'s elastic anisotropy parameters are used to represent the anisotropy of the skeleton.A plane-wave analysis is implemented on dynamic equations yields the analytic solutions for fast and slow P waves and two S *** results show that the elastic anisotropy parameters significantly determine the stress dependence of wave *** tortuosity and permeability have remarkable effects on fast and slow P-wave velocity curves and the corresponding attenuation peaks but have little effect on S-wave *** difference in velocities of two S waves occurs when the FSPL medium is subjected to horizontal uniaxial stress,and the S wave along the stress direction has a larger velocity,which implies that the additional anisotropy other than that induced by the beddings appears due to horizontal ***,the predicted velocity results have the reasonable agreement with laboratory *** equations and results are relevant to a better understanding of wave propagation in deep strata,which provide some new theoretical insights in the rock physics,hydrocarbon exploration and stress detection in deep-strata shale reservoirs.

关键词： Fluid-saturated porous layered(FSPL)media In-situ stress Theory of poroacoustoelasticity Wave equation Wave dispersion and attenuation

Advances in laser-plasma interactions using intense vortex laser beams

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Science China(Physics,Mechanics & Astronomy) 2024年第9期67卷 14-42页

作者： Yin Shi Xiaomei Zhang alexey Arefiev Baifei Shen Department of Plasma Physics and Fusion Engineering University of Science and Technology of ChinaHefei 230026China Department of Physics Shanghai Normal UniversityShanghai 200234China Department of Mechanical and Aerospace Engineering University of California at San DiegoLa JollaCA 92093USA

Low-intensity light beams carrying orbital angular momentum(OAM),commonly known as vortex beams,have garnered significant attention due to promising applications in areas ranging from optical trapping to *** recent years,there has been a surge in global research exploring the potential of high-intensity vortex laser beams and specifically their interactions with *** paper provides a comprehensive review of recent advances in this *** with conventional laser beams,intense vortex beams exhibit unique properties such as twisted phase fronts,OAM delivery,hollow intensity distribution,and spatially isolated longitudinal *** distinct characteristics give rise to a multitude of rich phenomena,profoundly influencing laser-plasma interactions and offering diverse *** paper also discusses future prospects and identifies promising general research areas involving vortex *** areas include low-divergence particle acceleration,instability suppression,high-energy photon delivery with OAM,and the generation of strong magnetic *** growing scientific interest and application potential,the study of intense vortex lasers is poised for rapid development in the coming years.

关键词： intense vortex laser orbital angular momentum laser plasma interactions high power laser high energy density science

Instance Segmentation of Characters Recognized in Palmyrene Aramaic Inscriptions

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2869-2889页

作者： Adéla Hamplová alexey Lyavdansky TomášNovák Ondrej Svojše David Franc Arnošt Veselý Czech University of Life Sciences in Prague(CULS) Faculty of Economics and ManagementDepartment of Information EngineeringPrague16500Czech Republic National Research University Higher School of Economics(HSE) Faculty of HumanitiesInstitute for Oriental and Classical StudiesMoscow101000The Russian Federation

This study presents a single-class and multi-class instance segmentation approach applied to ancient Palmyrene inscriptions,employing two state-of-the-art deep learning algorithms,namely YOLOv8 and Roboflow *** goal is to contribute to the preservation and understanding of historical texts,showcasing the potential of modern deep learning methods in archaeological *** research culminates in several key findings and scientific *** comprehensively compare the performance of YOLOv8 and Roboflow 3.0 in the context of Palmyrene character segmentation—this comparative analysis mainly focuses on the strengths and weaknesses of each algorithm in this *** also created and annotated an extensive dataset of Palmyrene inscriptions,a crucial resource for further research in the *** dataset serves for training and evaluating the segmentation *** employ comparative evaluation metrics to quantitatively assess the segmentation results,ensuring the reliability and reproducibility of our findings and we present custom visualization tools for predicted segmentation *** study advances the state of the art in semi-automatic reading of Palmyrene inscriptions and establishes a benchmark for future *** availability of the Palmyrene dataset and the insights into algorithm performance contribute to the broader understanding of historical text analysis.

关键词： Optical character recognition instance segmentation Palmyrene ancient languages computer vision

A simple semiempirical model for the static polarizability of electronically excited atoms and molecules

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Chinese Physics B 2023年第4期32卷 290-301页

作者： Alexander S Sharipov alexey V Pelevkin Boris I Loukhovitski Central Institute of Aviation Motors Aviamotornaya 2Moscow 111116Russia

We present a semiempirical analytical model for the static polarizability of electronically excited atoms and molecules,which requires very few readily accessible input data,including the ground-state polarizability,elemental composition,ionization potential,and spin multiplicities of excited and ground *** very simple model formulated in a semiclassical framework is based on a number of observed trends in polarizability of electronically excited *** adjust the model,both accurate theoretical predictions and reliable measurements previously reported elsewhere for a broad range of multielectron species in the gas phase are *** some representative compounds of general concern that have not yet attracted sufficient research interest,the results of our multireference second-order perturbation theory calculations are additionally *** show that the model we developed has reasonable(given the considerable uncertainties in the reference data)accuracy in predicting the static polarizability of electronically excited species of arbitrary size and excitation *** findings can be useful for many applications,where there is a need for inexpensive and quick assessments of the static gas-phase polarizability of excited electronic states,in particular,when building the complex nonequilibrium kinetic models to describe the observed optical refractivity(dielectric permittivity)of nonthermal reacting gas flows.

关键词： polarizability electronic excitation semiempirical model quantum chemistry

Nanoscopic imaging of oxidized graphene monolayer using tip-enhanced Raman scattering.

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Nano Research 2018年第12期11卷 6346-6359页

作者： Joseph M.Smolsky alexey V.krasnoslobodtsev Department of Physics University of Nebraska at Omaha6001Dodge StreetOmaha NE 68182USA

Tip-enhanced Raman scattering (TERS) can be used for the structural and chemical characterization of materials with a nanoscale resolution, and offers numerous advantages compared to other forms of imaging. We use TERS to track the local structural features of a CVD-grown graphene monolayer. Ag nanoparticles were added to AFM probes using ion-beam sputtering in order to make them TERS-active. Such modification provides probes with large factors of enhancement and good reproducibility. TERS measurements on graphene show an emergence of a defect-induced D-Raman band and a strain-induced shoulder of the graphene’s G-band. Comparison of TERS results with micro-Raman for oxidized graphene suggests that local oxidation occurs with the introduction of sp3 defects, under TERS conditions.

关键词： graphene Raman spectroscopy tip-enhanced Raman scattering graphene oxidation

Glial decline and loss of homeostatic support rather than inflammation defines cognitive aging

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Neural Regeneration Research 2022年第3期17卷 565-566页

作者： Alexei Verkhratsky Natalia Lazareva alexey Semyanov Faculty of Biology Medicine and HealthThe University of ManchesterManchesterUK Achucarro Center for Neuroscience IKERBASQUEBasque Foundation for ScienceBilbaoDepartment of NeurosciencesUniversity of the Basque Country UPV/EHU and CIBERNEDLeioaSpain Sechenov First Moscow State Medical University MoscowRussia Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of SciencesFaculty of BiologyMoscow State UniversityMoscowRussia

The preservation of cognitive longevity and arresting the pandemic of senile dementia engulfing the modern world is arguably the major challenge faced by biomedical research in the 21st *** is the leading risk factor for neurodegenerative diseases and vascular dementia,and yet there is a clear distinction between physiological and pathological brain aging.

关键词： inflammation senile aging

Insights into the hydrogen evolution reaction in vanadium redox flow batteries:A synchrotron radiation based X-ray imaging study

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Journal of Energy Chemistry 2024年第4期91卷 132-144页

作者： kerstin köble alexey Ershov kangjun Duan Monja Schilling Alexander Rampf Angelica Cecilia TomášFaragó Marcus Zuber Tilo Baumbach Roswitha Zeis Helmholtz Institute Ulm Karlsruhe Institute of Technology89081 UlmGermany Laboratory for Applications of Synchrotron Radiation Karlsruhe Institute of Technology76131 KarlsruheGermany Institute for Photon Science and Synchrotron Radiation Karlsruhe Institute of Technology76344 Eggenstein-LeopoldshafenGermany Department of Electrical Electronicsand Communication EngineeringFaculty of EngineeringFriedrich-Alexander-Universität Erlangen-Nürnberg(FAU)91058 ErlangenGermany Department of Mechanical and Industrial Engineering University of TorontoToronto M5S 3G8OntarioCanada

The parasitic hydrogen evolution reaction(HER)in the negative half-cell of vanadium redox flow batteries(VRFBs)causes severe efficiency ***,a deeper understanding of this process and the accompanying bubble formation is *** benchmarking study locally analyzes the bubble distribution in thick,porous electrodes for the first time using deep learning-based image segmentation of synchrotron X-ray *** large three-dimensional data set was processed precisely in less than one minute while minimizing human errors and pointing out areas of increased HER activity in *** study systematically varies the electrode potential and material,concluding that more negative electrode potentials of-200 m V *** hydrogen electrode(RHE)and lower cause more substantial bubble formation,resulting in bubble fractions of around 15%–20%in carbon felt ***,the bubble fractions stay only around 2%in an electrode combining carbon felt and carbon *** detected areas with high HER activity,such as the border subregion with more than 30%bubble fraction in carbon felt electrodes,the cutting edges,and preferential spots in the electrode bulk,are potential-independent and suggest that larger electrodes with a higher bulk-to-border ratio might reduce HER-related performance *** described combination of electrochemical measurements,local X-ray microtomography,AI-based segmentation,and 3D morphometric analysis is a powerful and novel approach for local bubble analysis in three-dimensional porous electrodes,providing an essential toolkit for a broad community working on bubble-generating electrochemical systems.

关键词： Vanadium redox flow battery Synchrotron X-ray imaging Tomography Hydrogen evolution reaction Gas bubbles Deep learning