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Dynamic Neural Potential Field: Online Trajectory Optimization in Presence of Moving Obstacles

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arXiv 2024年

作者： Staroverov, Aleksey Alhaddad, Muhammad Narendra, Aditya Mironov, Konstantin Panov, Aleksandr The Artificial Intelligence Research Institute Moscow105064 Russia Federal Research Center "Computer Science and Control Moscow117312 Russia Center of Cognitive Modeling Moscow Institute of Physics and Technology Dolgoprudny141701 Russia Faculty of Electrical and Electronic Engineering University of Aleppo Syria Ufa University of Science and Technology Ufa450000 Russia

We address a task of local trajectory planning for the mobile robot in the presence of static and dynamic obstacles. Local trajectory is obtained as a numerical solution of the Model Predictive Control (MPC) problem. Collision avoidance may be provided by adding repulsive potential of the obstacles to the cost function of MPC. We develop an approach, where repulsive potential is estimated by the neural model. We propose and explore three possible strategies of handling dynamic obstacles. First, environment with dynamic obstacles is considered as a sequence of static environments. Second, the neural model predict a sequence of repulsive potential at once. Third, the neural model predict future repulsive potential step by step in autoregressive mode. We implement these strategies and compare it with CIAO* and MPPI using BenchMR framework. First two strategies showed higher performance than CIAO* and MPPI while preserving safety constraints. The third strategy was a bit slower, however it still satisfy time limits. We deploy our approach on Husky UGV mobile platform, which move through the office corridors under proposed MPC local trajectory planner. The code and trained models are available at https://***/CognitiveAISystems/ Dynamic-Neural-Potential-Field. © 2024, CC BY.

关键词： Cost functions

Persistent currents in topological and trivial confinement in silicene

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Physical Review B 2020年第7期101卷 075408-075408页

作者： Piotr Jurkowski Bartłomiej Szafran AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 30-059 Kraków Poland

We consider states bound at the flip of the electric field in buckled silicene. Along the electric flip lines a topological confinement is formed with the orientation of the charge current and the resulting magnetic dipole moment determined by the valley index. We compare the topological confinement to the trivial one that is due to a local reduction of the vertical electric field but without energy gap inversion. For the latter the valley does not protect the orientation of the magnetic dipole moment from inversion by external magnetic field. We demonstrate that the topologically confined states can couple and form extended bonding or antibonding orbitals with the energy splitting influenced by the geometry and the external magnetic field.

关键词： Topological insulators 2-dimensional systems Quantum rings Silicene Topological materials Tight-binding model

List covering of regular multigraphs with semi-edges

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arXiv 2022年

作者： Bok, Jan Fiala, Jiří Jedličková, Nikola Kratochvíl, Jan Rzążewski, Pawel Computer Science Institute Faculty of Mathematics and Physics Charles University Prague Czech Republic Department of Applied Mathematics Faculty of Mathematics and Physics Charles University Prague Czech Republic Warsaw University of Technology Warsaw Poland University of Warsaw Warsaw Poland

In line with the recent development in topological graph theory, we are considering undirected graphs that are allowed to contain multiple edges, loops, and semi-edges. A graph is called simple if it contains no semi-edges, no loops, and no multiple edges. A graph covering projection, also known as a locally bijective homomorphism, is a mapping between vertices and edges of two graphs which preserves incidences and which is a local bijection on the edge-neighborhood of every vertex. This notion stems from topological graph theory, but has also found applications in combinatorics and theoretical computer science. It has been known that for every fixed simple regular graph H of valency greater than 2, deciding if an input graph covers H is NP-complete. Graphs with semi-edges have been considered in this context only recently and only partial results on the complexity of covering such graphs are known so far. In this paper we consider the list version of the problem, called List-H-Cover, where the vertices and edges of the input graph come with lists of admissible targets. Our main result reads that the List-H-Cover problem is NP-complete for every regular graph H of valency greater than 2 which contains at least one semi-simple vertex (i.e., a vertex which is incident with no loops, with no multiple edges and with at most one semi-edge). Using this result we show the NP-co/polytime dichotomy for the computational complexity of List-HCover for cubic graphs. Copyright © 2022, The Authors. All rights reserved.

关键词： Undirected graphs

Electrostatic quantum dot confinement in phosphorene

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Physical Review B 2020年第23期101卷 235313-235313页

作者： Bartłomiej Szafran Faculty of Physics and Applied Computer Science AGH University of Science and Technology al. Mickiewicza 30 30-059 Kraków Poland

We consider states localized by electrostatic potentials in phosphorene using an atomistic tight-binding approach. From the tight-binding spectra of states confined in a parabolic potential we extract effective masses for conduction band electrons moving along the armchair and zigzag crystal directions by a fit to the harmonic oscillator spectrum. The masses derived in this way are used for a simple single-band effective-mass model which, as we find, reproduces very well the tight-binding energy spectra in an external magnetic field, the confined probability densities, and the interaction effects. We study the confined states in the conduction band and find that both methods produce Wigner crystallization with separated single-electron islands already for small quantum dots. The effective-mass model works with slightly worse precision for confined states of the valence band. The continuum approach deviates considerably from the tight-binding model only in the limit of extremely strong lateral confinement.

关键词： Few-body systems Phosphorene Quantum dots Wigner crystal

Transmon probe for quantum characteristics of magnons in antiferromagnets

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arXiv 2023年

作者： Azimi-Mousolou, Vahid Bergman, Anders Delin, Anna Eriksson, Olle Pereiro, Manuel Thonig, Danny Sjöqvist, Erik Department of Applied Mathematics and Computer Science Faculty of Mathematics and Statistics University of Isfahan Isfahan81746-73441 Iran Department of Physics and Astronomy Uppsala University Box 516 UppsalaSE-751 20 Sweden Department of Applied Physics School of Engineering Sciences KTH Royal Institute of Technology AlbaNova University Center StockholmSE-10691 Sweden KTH Royal Institute of Technology StockholmSE-10044 Sweden School of Science and Technology Örebro University ÖrebroSE-701 82 Sweden

The detection of magnons and their quantum properties, especially in antiferromagnetic (AFM) materials, is a substantial step to realize many ambitious advances in the study of nanomagnetism and the development of energy efficient quantum technologies. The recent development of hybrid systems based on superconducting circuits provides the possibility of engineering quantum sensors that exploit different degrees of freedom. Here, we examine the magnon-photon-transmon hybridisation based on bipartite AFM materials, which gives rise to an effective coupling between a transmon qubit and magnons in a bipartite AFM. We demonstrate how magnetically invisible magnon modes, their chiralities and quantum properties such as nonlocality and two-mode magnon entanglement in bipartite AFMs can be characterized through the Rabi frequency of the superconducting transmon qubit. © 2023, CC BY.

关键词： Hybrid systems

STAR-RIS-NOMA Assisted Power Constrained Covert Communication Systems

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IEEE Transactions on Vehicular technology 2025年

作者： Lei, Yuxin Huang, Gaojian Li, Xingwang Tian, Zhifa Mumtaz, Shahid Asif, Muhammad Henan Polytechnic University School of Physics and Electronic Information Engineering Jiaozuo454003 China City University of Macau Faculty of Data Science 999078 China Henan Polytechnic University School of Surveying and Land Information Engineering Jiaozuo454003 China Henan Polytechnic University School of Physics and Electronic Information Engineering Jiaozuo454099 China Southeast University National Mobile Communications Research Laboratory Nanjing210096 China Silesian University of Technology Department of Applied Informatics Gliwice Poland Department of Engineering Nottingham Trent University United Kingdom Jiangsu University School of Computer Science and Communication Engineering Zhenjiang China

In this paper, a covert communication system assisted by a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) in non-orthogonal multiple access (NOMA) networks is proposed. When the maximum channel power gain from the transmitter in the main network to the users in adjacent networks is smaller than the threshold, the transmitter sends the NOMA signals to the users with the assistance of STAR-RIS. Moreover, channel estimation errors and imperfect successive interference cancellation (SIC) are considered in the system analysis. To characterize the covert performance, the detection error probability (DEP) and the average minimum detection error probability (AMDEP) are first derived. Then, the closed-form solutions of the outage probability (OP) for the users are obtained. Finally, the maximum effective covert rate (ECR) subject to the covertness constraint and non-interruption constraint is studied. The numerical simulation results show that: 1) the detection performance of Willie (warden) deteriorates as the channel estimation errors increase;2) when the transmitter power exceeds the threshold, communication in the main network is interrupted;3) under a certain transmit power, the maximum ECR increases with the increasing of the number of STAR-RIS reflection elements. © 2025 IEEE.

关键词： Channel estimation

Grain Stresses and Critical Resolved Shear Stresses in Duplex Steel Studied Using Neutron Diffraction and Crystallite Group Method

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SSRN

SSRN 2024年

作者： Baczmański, Andrzej Wroński, Sebastian François, Manuel Le Joncour, Léa Panicaud, Benoit Braham, Chedly Ludwik, Aleksandra Wierzbanowski, Krzysztof Klosek, Vincent AGH University of Kraków Faculty of Physics and Applied Computer Science al. Mickiewicza 30 Kraków30-059 Poland 12 rue Marie Curie Troyes10010 France PIMM 151 Bd de l’Hôpital 75013 Paris France CEA Laboratoire Léon Brillouin Gif-sur-Yvette91191 Cedex France

In this work, a new method for determining the critical resolved shear stress (CRSS) and stress concentration in polycrystalline grains was tested and applied to study the elastic-plastic properties of textured duplex steel. The methodology is based on in situ neutron diffraction measurements of lattice strains during tensile loading. The lattice deformations are measured for several hkl reflections and for different sample orientations with respect to the scattering vector. As a result, the full stress tensor for preferred texture orientations in function of applied stress has been determined using the crystallite group method (CGM). Knowing the experimental values of stresses, the stress concentration tensor is determined. The experimental data are then compared with self-consistent model calculations performed for groups of grains corresponding to the measured hkl reflections. The important advance of the proposed methodology consists in the possibility of estimating the CRSSs directly from measurements, without the use of any elastic-plastic *** the research carried out, on the basis of diffraction measurements, the evolution of grain stresses in preferred orientations in the ferritic and austenitic phases of the tested duplex steel was determined. Using these data, the evolution of the resolved shear stress (RSS) was analysed and, for the first time, CRSS values in both duplex phases were obtained directly from the experimental data. The final results also took into account the influence of initial stresses in the obtained material on the determined CRSSs. © 2024, The Authors. All rights reserved.

关键词： Neutron diffraction

Video Scene Location Recognition with Neural Networks

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arXiv 2023年

作者： Korel, Lukáš Pulc, Petr Tumpach, Jiří Holeňa, Martin Faculty of Information Technology Czech Technical University Prague Czech Republic Faculty of Mathematics and Physics Charles University Prague Czech Republic Institute of Computer Science Academy of Sciences of the Czech Republic Prague Czech Republic

This paper provides an insight into the possibility of scene recognition from a video sequence with a small set of repeated shooting locations (such as in television series) using artificial neural networks. The basic idea of the presented approach is to select a set of frames from each scene, transform them by a pre-trained single-image pre-processing convolutional network, and classify the scene location with subsequent layers of the neural network. The considered networks have been tested and compared on a dataset obtained from The Big Bang Theory television series. We have investigated different neural network layers to combine individual frames, particularly AveragePooling, MaxPooling, Product, Flatten, LSTM, and Bidirectional LSTM layers. We have observed that only some of the approaches are suitable for the task at hand. © 2023, CC0.

关键词： Location

List locally surjective homomorphisms in hereditary graph classes

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arXiv 2022年

作者： Dvorák, Pavel Krawczyk, Monika Masarík, Tomáš Novotná, Jana Rzazewski, Pawel Zuk, Aneta Department Of Computer Science University Of Bristol United Kingdom Faculty Of Mathematics And Information Science Warsaw University Of Technology Warsaw Poland Institute Of Informatics Faculty Of Mathematics Informatics And Mechanics University Of Warsaw Poland Department Of Applied Mathematics Faculty Of Mathematics And Physics Charles University Prague Czech Republic

A locally surjective homomorphism from a graph G to a graph H is an edge-preserving mapping from V (G) to V (H) that is surjective in the neighborhood of each vertex in G. In the list locally surjective homomorphism problem, denoted by LLSHom(H), the graph H is fixed and the instance consists of a graph G whose every vertex is equipped with a subset of V (H), called list. We ask for the existence of a locally surjective homomorphism from G to H, where every vertex of G is mapped to a vertex from its list. In this paper, we study the complexity of the LLSHom(H) problem in F-free graphs, i.e., graphs that exclude a fixed graph F as an induced subgraph. We aim to understand for which pairs (H, F) the problem can be solved in subexponential time. We show that for all graphs H, for which the problem is NP-hard in general graphs, it cannot be solved in subexponential time in F-free graphs for F being a bounded-degree forest, unless the ETH fails. The initial study reveals that a natural subfamily of boundeddegree forests F, that might lead to some tractability results, is the family S consisting of forests whose every component has at most three leaves. In this case, we exhibit the following dichotomy theorem: besides the cases that are polynomial-time solvable in general graphs, the graphs H ∈ {P3, C4} are the only connected ones that allow for a subexponential-time algorithm in F-free graphs for every F ∈ S (unless the ETH fails). © 2022, CC BY.

关键词： Graphic methods