arXiv subjects

Alexey Popov

Publications and source records attributed to Alexey Popov.

9 recordsLinked to original sources

arXiv2026

Mobile Traffic Camera Calibration from Road Geometry for UAV-Based Traffic Surveillance

Unmanned aerial vehicles (UAVs) can provide flexible traffic surveillance where fixed roadside cameras are unavailable, costly, or impractical. However, raw UAV video is difficult to use for traffic analytics because vehicle motion is observed in perspective image coordinates rather than in a stable metric road coordinate system. This paper presents a lightweight pipeline for converting monocular oblique UAV traffic video into a local metric bird's-eye-view (BEV) representation. Visible road geometry, including lane markings, road borders, and crosswalks, is used to estimate a road-plane homography from image coordinates to metric ground-plane coordinates. Vehicle observations from dataset annotations or detectors are then projected to BEV using estimated ground contact points. The resulting trajectories support estimation of vehicle direction, speed, heading, and dynamic 3D cuboids on the road plane. We evaluate the pipeline on UAVDT using ground-truth annotations to isolate calibration and geometric reconstruction from detector and tracker errors. For sequence M1401, 40 sampled frames from img000001-img000196 produce 632 metric cuboid instances across 23 tracks. Results show that road-geometry calibration can transform monocular UAV footage into interpretable traffic-camera-style analytics, including BEV tracks and synchronized 3D cuboid visualizations. They also reveal key limitations: far-field vehicles are sensitive to homography errors, manual validation is currently more reliable than fully automatic calibration, and the single-plane assumption limits performance in non-planar or ambiguous road regions. The proposed pipeline provides a practical foundation for deployable UAV traffic cameras and future real-time traffic digital-twin systems.

cs.CV↗

arXiv2026

RISC-V Functional Safety for Autonomous Automotive Systems: An Analytical Framework and Research Roadmap for ML-Assisted Certification

RISC-V is emerging as a viable platform for automotive-grade embedded computing, with recent ISO 26262 ASIL-D certifications demonstrating readiness for safety-critical deployment in autonomous driving systems. However, functional safety in automotive systems is fundamentally a certification problem rather than a processor problem. The dominant costs arise from diagnostic coverage analysis, toolchain qualification, fault injection campaigns, safety-case generation, and compliance with ISO 26262, ISO 21448 (SOTIF), and ISO/SAE 21434. This paper analyzes the role of RISC-V in automotive functional safety, focusing on ISA openness, formal verifiability, custom extension control, debug transparency, and vendor-independent qualification. We examine autonomous driving safety requirements and map them to RISC-V architectural challenges such as lockstep execution, safety islands, mixed-criticality isolation, and secure debug. Rather than proposing a single algorithmic breakthrough, we present an analytical framework and research roadmap centered on certification economics as the primary optimization objective. We also discuss how selected ML methods, including LLM-assisted FMEDA generation, knowledge-graph-based safety case automation, reinforcement learning for fault injection, and graph neural networks for diagnostic coverage, can support certification workflows. We argue that the strongest outcome is not a faster core, but an ASIL-D-ready certifiable RISC-V platform.

cs.SE↗

arXiv2024

SnS2 thin film with in-situ and controllable Sb doping via atomic layer deposition for optoelectronic applications

SnS2 stands out as a highly promising two-dimensional material with significant potential for applications in the field of electronics. Numerous attempts have been undertaken to modulate the physical properties of SnS2 by doping with various metal ions. Here, we deposited a series of Sb-doped SnS2 via atomic layer deposition (ALD) super-cycle process and compared its crystallinity, composition, and optical properties to those of pristine SnS2. We found that the increase in the concentration of Sb is accompanied by a gradual reduction in the Sn and S binding energies. The work function is increased upon Sb doping from 4.32 eV (SnS2) to 4.75 eV (Sb-doped SnS2 with 9:1 ratio). When integrated into photodetectors, the Sb-doped SnS2 showed improved performances, demonstrating increased peak photoresponsivity values from 19.5 A/W to 27.8 A/W at 405 nm, accompanied by an improvement in response speed. These results offer valuable insights into next-generation optoelectronic applications based on SnS2.

cond-mat.mtrl-sci↗

arXiv2017

Cross-Bridge Induced Adhesion of Red Blood Cells Assessed by Optical Tweezers

The reversible aggregation of red blood cells (RBCs) is a process of erythrocytes clumping that strongly influences the rheological properties of blood. The adhesion of RBCs has been studied extensively in the frame of cell-to-cell interaction induced by dextran macromolecules, whereas the data is lacking for native plasma solution. We apply optical tweezers to investigate the induced adhesion of RBCs in plasma and in dextran solution. Two hypotheses 'cross-bridges' and 'depletion layer' are being utilized to describe the mechanism of cells interaction, while both need to be confirmed experimentally. The results show that in dextran solution the interaction of adhering RBCs agrees well with the quantitative predictions obtained on the basis of a depletion-induced cells adhesion model, whereas a migrating 'cross-bridge' model is more appropriate for plasma. Furthermore, the 'cross-bridge' mechanism is confirmed by direct visualization of red blood cells adhesion utilizing scanning electron microscopy (SEM).

physics.bio-ph↗

arXiv2015

An operational definition of the 100 second blocking temperature T$_{\mathrm{B}100}$ for single molecule magnets

An important figure of merit for the performance of single-molecule magnets (SMMs) is the 100 s blocking temperature T$_{\mathrm{B}100}$. It is the temperature at which the remanence or zero field relaxation time is 100 seconds. If there is more than one relaxation process of the magnetisation, the determination of the relaxation times may, however, become ambiguous. Here we propose an operational definition for the zero-field magnetic relaxation times from which T$_{\mathrm{B}100}$ may be determined. This definition allows for a direct comparison of the performance of different samples independent of the details of the relaxation processes involved in the demagnetization.

cond-mat.mtrl-sci↗

arXiv2015

Surface aligned magnetic moments and hysteresis of an endohedral single-molecule magnet on a metal

The interaction between the endohedral unit in the single-molecule magnet Dy$_2$ScN@C$_{80}$ and a rhodium (111) substrate leads to alignment of the Dy 4$f$ orbitals. The resulting orientation of the Dy$_2$ScN plane parallel to the surface is inferred from comparison of the angular anisotropy of x-ray absorption spectra and multiplet calculations in the corresponding ligand field. The x-ray magnetic circular dichroism (XMCD) is also angle dependent and signals strong magnetocrystalline anisotropy. This directly relates geometric and magnetic structure. Element specific magnetization curves from different coverages exhibit hysteresis at a sample temperature of $\sim4$ K. From the measured hysteresis curves we estimate the zero field remanence life-time during x-ray exposure of a sub-monolayer to be about 30 seconds.

cond-mat.mtrl-sci↗

arXiv2013

Tunneling, Remanence, and Frustration in Dysprosium based Endohedral Single Molecule Magnets

A single molecule magnet (SMM) can maintain its magnetization direction over a long period of time [1,2]. It consists in a low number of atoms that facilitates the understanding and control of the ground state, which is essential in future applications such as high-density information storage or quantum computers [3,4]. Endohedral fullerenes realize robust, nanometer sized, and chemically protected magnetic clusters that are not found as free species in nature. Here we demonstrate how adding one, two, or three dysprosium atoms to the carbon cage results in three distinct magnetic ground states. The significantly different hysteresis curves demonstrate the decisive influence of the number of magnetic moments and their interactions. At zero field the comparison relates tunneling of the magnetization, with remanence, and frustration. The ground state of the tridysprosium species turns out to be one of the simplest realizations of a frustrated, ferromagnetically coupled magnetic system.

cond-mat.mtrl-sci↗

arXiv2013

Topological Signatures in the Electronic Structure of Graphene Spirals

Topology is familiar mostly from mathematics, but also natural sciences have found its concepts useful. Those concepts have been used to explain several natural phenomena in biology and physics, and they are particularly relevant for the electronic structure description of topological insulators and graphene systems. Here, we introduce topologically distinct graphene forms - graphene spirals - and employ density-functional theory to investigate their geometric and electronic properties. We found that the spiral topology gives rise to an intrinsic Rashba spin-orbit splitting. Through a Hamiltonian constrained by space curvature, graphene spirals have topologically protected states due to time-reversal symmetry. In addition, we argue that the synthesis of such graphene spirals is feasible and can be achieved through advanced bottom-up experimental routes that we indicate in this work.

cond-mat.mes-hall↗

arXiv2007

W and Z Boson Production at sqrt(S)=1.96TeV with the D0 Detector

Preliminary measurements of the cross-section for the processes ppbar --> W --> mu nu, e nu; ppbar --> Z --> mu mu, e e, tau tau from the D0 detector are presented. Integrated luminosities for these data samples are 96 pb-1 for W --> mu nu, 177.3 pb-1 for W --> e nu and Z --> e e, 148pb-1 for Z --> mu mu and 207 pb-1 for Z --> tau tau. A measurement of the muon charge asymmetry from W boson decays (integrated luminosity 230 pb-1) and Z/gamma* --> e e inclusive differential cross section as a function of boson rapidity (integrated luminosity 337 pb-1) are presented as well. The results are in generally good agreement with SM predictions.

hep-ex↗