检索结果-内蒙古大学图书馆

Non-Gaussian transverse momentum fluctuations from impact parameter fluctuations

学校读者我要写书评

暂无评论

Physical Review C 2023年第2期108卷 024908-024908页

作者： Rupam Samanta João Paulo Picchetti Matthew Luzum Jean-Yves Ollitrault AGH University of Science and Technology Faculty of Physics and Applied Computer Science aleja Mickiewicza 30 30-059 Cracow Poland Université Paris Saclay CNRS CEA Institut de Physique Théorique 91191 Gif-sur-Yvette France Instituto de Física Universidade de São Paulo Rua do Matão 1371 Butantã 05508-090 São Paulo Brazil

The transverse momentum per particle, [pt], fluctuates event by event in ultrarelativistic nucleus-nucleus collisions, for a given multiplicity. These fluctuations are small and approximately Gaussian, but a nonzero skewness has been predicted on the basis of hydrodynamic calculations, and seen experimentally. We argue that the mechanism driving the skewness is that, if the system thermalizes, the mean transverse momentum increases with impact parameter for a fixed collision multiplicity. We postulate that fluctuations are Gaussian at fixed impact parameter, and that non-Gaussianities solely result from impact parameter fluctuations. Using recent data on the variance of [pt] fluctuations, we make quantitative predictions for their skewness and kurtosis as a function of the collision multiplicity. We predict, in particular, a spectacular increase of the skewness below the knee of the multiplicity distribution, followed by a fast decrease.

关键词： Particle correlations & fluctuations Relativistic heavy-ion collisions

Pressure induced transition from chiral charge order to time-reversal symmetry-breaking superconducting state in Nb-doped CsV3Sb5

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Graham, J.N. Islam, S.S. Sazgari, V. Li, Y. Deng, H. Janka, G. Zhong, Y. Gerguri, O. Král, P. Doll, A. Bialo, I. Chang, J. Salman, Z. Suter, A. Prokscha, T. Yao, Y. Okazaki, K. Luetkens, H. Khasanov, R. Wang, Z. Yin, J.-X. Guguchia, Z. PSI Center for Neutron and Muon Sciences CNM Villigen5232 Switzerland Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement Ministry of Education School of Physics Beijing Institute of Technology Beijing100081 China Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems Beijing Institute of Technology Beijing100081 China Department of Physics Southern University of Science and Technology Guangdong Shenzhen518055 China Institute for Solid States Physics The University of Tokyo Kashiwa Japan Physik-Institut Universität Zürich Winterthurerstrasse 190 ZürichCH-8057 Switzerland AGH University of Science and Technology Faculty of Physics and Applied Computer Science Kraków30-059 Poland International Center for Quantum Materials Beijing Institute of Technology Zhuhai319000 China Trans-scale Quantum Science Institute The University of Tokyo Tokyo Japan Material Innovation Research Center The University of Tokyo Kashiwa Japan

The experimental realisation of unconventional superconductivity and charge order in kagome systems AV3Sb5 is of critical importance. We conducted a highly systematic study of Cs(V1−xNbx)3Sb5 with x=0.07 (Nb0.07-CVS) by employing a unique combination of tuning parameters such as doping, hydrostatic pressure, magnetic fields, and depth, using muon spin rotation, AC susceptibility, and STM. We uncovered tunable magnetism in the normal state of Nb0.07-CVS, which transitions to a time-reversal symmetry (TRS) breaking superconducting state under pressure. Specifically, our findings reveal that the bulk of Nb0.07-CVS (at depths >20 nm from the surface) experiences TRS breaking below T∗ = 40 K, lower than the charge order onset temperature, TCO = 58 K. However, near the surface ( © 2024, CC BY.

关键词： Magnetic susceptibility

Influence of In-induced resonant level on the normal-state and superconducting properties of Sn1.03Te

学校读者我要写书评

暂无评论

Physical Review B 2022年第7期106卷 075205-075205页

作者： Shantanu Misra Bartlomiej Wiendlocha Janusz Tobola Petr Levinský Jiří Hejtmánek Sylvie Migot Jaafar Ghanbaja Anne Dauscher Bertrand Lenoir Christophe Candolfi Institut Jean Lamour UMR 7198 CNRS – Université de Lorraine 2 allée André Guinier-Campus ARTEM BP 50840 54011 Nancy Cedex France Faculty of Physics and Applied Computer Science AGH University of Science and Technology Aleja Mickiewicza 30 30-059 Krakow Poland Institute of Physics Czech Academy of Sciences Cukrovarnická 10 162 00 Praha 6 Czech Republic

Normal-state transport properties (2–300 K) of the polycrystalline series Sn1.03−δ−xInxTe (0≤x≤0.07; δ≤0.0025) were investigated by means of electrical resistivity, thermopower, Hall effect, and thermal conductivity measurements. The distortion of the valence-band structure by the In-induced resonant level (RL) has a profound influence on the evolution of the normal-state properties with x and on the emergence of superconductivity evidenced by specific-heat measurements down to 0.35 K. In addition to a nearly 40-fold increase in the residual electrical resistivity ρ0 on going from x=0.0 to 0.05, the thermopower α shows a nonlinear, complex behavior as a function of both temperature and x. While Hall measurements indicate a dominant holelike response across the entire composition and temperature ranges, α changes sign below about 100 K and remains negative down to 5 K for 0.0015≤x≤0.0045. Additional measurements under magnetic fields μ0H of up to 14 T further shows that α(μ0H) gradually shifts towards positive values, suggestive of a dominant holelike contribution to α. Superconductivity emerges for x=0.02 at a critical temperature Tc=0.67 K, with Tc increasing with x to reach 1.73 K for x=0.07. The variations in the superconducting parameters with x, notably the specific-heat jump at Tc, confirm the results reported in prior studies and suggests a nontrivial role of the RL on the electron-phonon coupling strength. The striking similarities between this series and the canonical resonant system Pb1−xTlxTe provide an excellent experimental opportunity to gain a deeper understanding of the close interplay between resonant level, anomalous transport properties, and superconductivity.

关键词： Electronic structure Thermoelectric effects Energy materials Narrow band gap systems Polycrystalline materials Korringa-Kohn-Rostoker method Methods in transport Transport techniques

Insights into dendritic growth mechanisms in batteries: A combined machine learning and computational study

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Zhao, Zirui Xia, Junchao Wu, Si Wang, Xiaoke Xu, Guanping Zhu, Yinghao Sun, Jing Li, Hai-Feng Institute of Applied Physics and Materials Engineering University of Macau Avenida da Universidade Taipa999078 China School of Materials Science and Engineering Chang’an University Xi’an710061 China School of Physical Science and Technology Ningbo University Ningbo315211 China Faculty of Data Science City University of Macau Avenida Padre Tomas Pereira Taipa999078 China

In recent years, researchers have increasingly sought batteries as an efficient and cost-effective solution for energy storage and supply, owing to their high energy density, low cost, and environmental resilience. However, the issue of dendrite growth has emerged as a significant obstacle in battery development. Excessive dendrite growth during charging and discharging processes can lead to battery short-circuiting, degradation of electrochemical performance, reduced cycle life, and abnormal exothermic events. Consequently, understanding the dendrite growth process has become a key challenge for researchers. In this study, we investigated dendrite growth mechanisms in batteries using a combined machine learning approach, specifically a two-dimensional artificial convolutional neural network (CNN) model, along with computational methods. We developed two distinct computer models to predict dendrite growth in batteries. The CNN-1 model employs standard convolutional neural network techniques for dendritic growth prediction, while CNN-2 integrates additional physical parameters to enhance model robustness. Our results demonstrate that CNN-2 significantly enhances prediction accuracy, offering deeper insights into the impact of physical factors on dendritic growth. This improved model effectively captures the dynamic nature of dendrite formation, exhibiting high accuracy and sensitivity. These findings contribute to the advancement of safer and more reliable energy storage systems. Copyright © 2025, The Authors. All rights reserved.

关键词： Convolutional neural networks

Contention Window Optimization in IEEE 802.11ax Networks with Deep Reinforcement Learning

学校读者我要写书评

暂无评论

Contention Window Optimization in IEEE 802.11ax Networks wit...

IEEE Conference on Wireless Communications and Networking

作者： Witold Wydmański Szymon Szott Faculty of Computer Science Electronics and Telecommunications AGH University of Science and Technology Krakow Poland

The proper setting of contention window (CW) values has a significant impact on the efficiency of Wi-Fi networks. Unfortunately, the standard method used by 802.11 networks is not scalable enough to maintain stable throughput for an increasing number of stations, yet it remains the default method of channel access for 802.11ax single-user transmissions. Therefore, we propose a new method of CW control, which leverages deep reinforcement learning (DRL) principles to learn the correct settings under different network conditions. Our method, called centralized contention window optimization with DRL (CCOD), supports two trainable control algorithms: deep Q-network (DQN) and deep deterministic policy gradient (DDPG). We demonstrate through simulations that it offers efficiency close to optimal (even in dynamic topologies) while keeping computational cost low.

关键词： Training Network topology Heuristic algorithms IEEE 802.11ax Standard Reinforcement learning Throughput Topology

Tailoring population transfer between two hyperfine ground states of Rb87

学校读者我要写书评

暂无评论

Physical Review A 2023年第5期107卷 052810-052810页

作者： Aleksandra Sierant Marek Kopciuch Szymon Pustelny Institute of Physics Jagiellonian University in Kraków Łojasiewicza 11 30-348 Kraków Poland Institut de Ciencies Fotoniques The Barcelona Institute of Science and Technology Castelldefels (Barcelona) 08860 Spain Jagiellonian University Doctoral School of Exact and Natural Sciences Faculty of Physics Astronomy and Applied Computer Sciences Łojasiewicza 11 30-348 Kraków Poland

In this paper, we investigate the coherent control over a complex multilevel atomic system using the stimulated Raman adiabatic passage. Based on the example of Rb87 atoms, excited with circularly polarized light at the D1 line, we demonstrate the ability to decompose the system into three- and four-level subsystems independently interacting with light beams. Focusing on the four-level system, we demonstrate that the presence of an additional excited state significantly affects the dynamics of the system evolution. Specifically, it is shown that, through the appropriate tuning of the light beams, some of the transfer channels can be blocked, which leads to better control over the system. We also demonstrate that this effect is most significant in media free from inhomogeneous broadening (e.g., Doppler effect) and deteriorates if such broadening is present. For instance, the motion of atoms affects both the efficiency and selectivity of the transfer.

关键词： Atom optics Atomic & molecular processes in external fields Coherent control Light-matter interaction Quantum optics

Magnon Shake-up: Entanglement Generation and Sensing

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Azimi-Mousolou, Vahid Sjöqvist, Erik Delin, Anna Eriksson, Olle 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 Swedish e-Science Research Center KTH Royal Institute of Technology StockholmSE-10044 Sweden KTH Royal Institute of Technology StockholmSE-10044 Sweden WISE-Wallenberg Inititative Materials Science Uppsala University Box 516 UppsalaSE-751 20 Sweden

Shake-up phenomena, rooted in the sudden approximation and many-body quantum dynamics, unveil critical characteristics of quantum systems, with wide-ranging applications in molecular spectroscopy and electronic structure studies. Here, this principle is extended to magnetic systems, and magnon shake-up structures and their relevance in generating and sensing magnon-magnon entanglement are demonstrated. This not only reveals new insights into shake-up phenomena and quantum magnetism but also paves the way for new opportunities in quantum technologies. © 2025, CC BY.

关键词： Quantum entanglement

Air Particulate Matters Auto-Rule-Based Labeling to Support Long-Distance Run Environment Data Classification

学校读者我要写书评

暂无评论

Air Particulate Matters Auto-Rule-Based Labeling to Support ...

International Conference on computer Applications and Industrial Electronics (ICCAIE)

作者： Wandy Wandy Kusworo Adi Media Anugerah Ayu Doctoral Program of Information Systems School of Postgraduate Studies Diponegoro University Semarang Indonesia Department of Physics Faculty of Science and Mathematics Diponegoro University Semarang Indonesia Department of Computer Science Faculty of Engineering and Technology Sampoerna University South Jakarta Indonesia

Sports science is an interdisciplinary and multidisciplinary science that strives to increase athletic performance and endurance. Sport science recognizes and prevents injuries. Sensors and statistics formalize Sports science. Runners need coaches and teams to support them before, during, and after the run race. Coaches generate running training plans to boost performance. Running race performances may be impacted by air pollution exposure while training, so coaches should consider limiting air pollution exposure when training. One of the external factors is Particulate Matter (PM 2.5 and PM 10 ). Sensors connecting to the Internet can record external factors and produce csv data. The foundation of supervised machine learning is the labeling process. Labeling a set of data is one of the laborious and time-consuming phases in every machine-learning application because it requires verifying the accuracy of the labels and making any necessary revisions. This research aimed to find a solution to automatically label numerous air particulate matter raw data using a rule based on parameters to reduce manual work, human errors and faster processes. This labeled data will later be used for supervised machine learning classification to support the coach in generating training programs for the runners in a Sports Information System. Based on Indonesia Air Quality index rule-based approach, labeled text data in csv has been generated and tested with PM 2.5 and PM 10 parameters in three scenarios with a 100% success rate. It was possible to automate the labeling process, and it explained how automation results in fast and accurate results.

关键词：

Yang-Lee zeros for real-space condensation

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Burda, Zdzislaw Johnston, Desmond A. Kieburg, Mario AGH University of Krakow Faculty of Physics and Applied Computer Science al. Mickiewicza 30 Kraków30-059 Poland School of Mathematical and Computer Sciences Heriot-Watt University Riccarton EdinburghEH14 4AS United Kingdom Maxwell Institute of Mathematical Sciences Edinburgh United Kingdom University of Melbourne School of Mathematics and Statistics ParkvilleVIC3010 Australia Faculty of Physics Bielefeld University PO-Box 100131 BielefeldD-33501 Germany

Using the electrostatic analogy, we derive an exact formula for the limiting Yang-Lee zero distribution in the random allocation model of general weights. This exhibits a real-space condensation phase transition, which is induced by a pressure change. The exact solution allows one to read off the scaling of the density of zeros at the critical point and the angle at which locus of zeros hits the critical point. Since the order of the phase transition and critical exponents can be tuned with a single parameter for several families of weights, the model provides a useful testing ground for verifying various relations between the distribution of zeros and the critical behavior, as well as for exploring the behavior of physical quantities in the mesoscopic regime, i.e., systems of large but finite size. The main result is that asymptotically the Yang-Lee zeros are images of a conformal mapping, given by the generating function for the weights, of uniformly distributed complex phases. © 2024, CC BY.

关键词： Condensation