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arXiv 2024年

作者： Qiu, Taotao Zhu, Mian School of Physics Huazhong University of Science and Technology Wuhan430074 China Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Krakow30-348 Poland

Recent pulsar timing array (PTA) experiments have reported strong evidence of the stochastic gravitational wave background (SGWB). If interpreted as primordial Gravitational Waves (pGWs), the signal favors a strongly blue-tilted spectrum. On the other hand, the Ekpyrosis-bouncing cosmology with a strongly blue-tilted GW spectrum, i.e., nT 2, offers a potential explanation for the observed SGWB signal. In this paper, we construct a concrete Ekpyrosis-bouncing model, and show its capacity to intepret the PTA result without pathologies. Both tensor and scalar perturbations are analysed with constraints from the current observations. © 2024, CC BY.

关键词： Cosmology

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Through-Wall Human Sensing Using mmWave FMCW Radar 4

Through-Wall Human Sensing Using mmWave FMCW Radar

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4th Research, Invention, and Innovation Congress: Innovative Electricals and Electronics, RI2C 2023

作者： Phaisiri, Kritthee Boonpoonja, Akkarat Kittiyanpunya, Chainarong Kaemarungsi, Kamol Chudpooti, Nonchanutt Department of Electrical and Computer Engineering Faculty of Engineering King Mongkut’s University of Technology North Bangkok Bangkok Thailand Department of Mechatronics Engineering Faculty of Engineering Rajamangala University of Technology Rattanakosin Nakhon Pathom Thailand National Electronics and Computer Technology Center National Science and Technology Development Agency Pathumthani Thailand Department of Industrail Physics and Medical Instrumentation Faculty of Applied Science King Mongkut’s University of Technology North Bangkok Bangkok Thailand

ISBN: (纸本)9798350330618

This paper experimentally demonstrates the through wall sensing to detect human movement using a mmwave FMCW radar operating in the 60 GHz to 64 GHz band. The mmWave radar data processing framework focuses on the generation of point cloud data. Each human movement is illustrated with point cloud data, whose represents the position and orientation of pose, usually in 3D-cartesian coordinate system. In experiments, point cloud data from sensing through two different walls were collected for three activities into a 3 m by 3 m room. The data was analyzed through a comparison between the position of point cloud data and the position of the actual posture movement. The results prove that a mmWave radar placed behind the wall of the room is suitable for human detection and tracking in indoor environments, in terms of consistency with the actual posture. . ©2023 IEEE.

关键词： Frequency modulation

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Strong-coupling superconductivity of the Heusler-type compound ScAu2Al: Ab-initio studies

arXiv

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arXiv 2023年

作者： Kuderowicz, Gabriel Wiendlocha, Bartlomiej AGH University of Krakow Faculty of Physics and Applied Computer Science Aleja Mickiewicza 30 Krakow30-059 Poland

The ScAu2Al superconducting Heusler-type compound was recently characterized to have the highest critical temperature of Tc = 5.12 K and the strongest electron-phonon coupling among the Heusler family. In this work, the electronic structure, phonons, electron-phonon coupling, and superconductivity of ScAu2Al are studied using ab initio calculations. The spin-orbit coupling significantly changes the electronic structure removing the van Hove singularity from the vicinity of the Fermi level. In the phonon spectrum, low frequency acoustic modes, additionally softened by the spin-orbit interaction, strongly couple with electrons, leading to the electron-phonon coupling constant λ = 1.25, a record high among Heuslers. The density functional theory for superconductors is then used to analyze superconducting state in this two-band superconductor. The effect of spin fluctuations (SF) on superconductivity is also analyzed. The calculated critical temperatures of Tc = 5.16 K (4.79 K with SF) agree very well with the experiment, confirming the electron-phonon mechanism of superconductivity and showing a weak spin-fluctuations effect. The superconducting gaps formed on two Fermi surface sheets exhibit moderate anisotropy. Their magnitudes confirm the strong coupling regime, as the reduced average values are 2∆b1/kBTc 4.1 and 2∆b2/kBTc 4.3. Anisotropy of the gaps and large spread in their values significantly affect the calculated quasiparticle density of states. Copyright © 2023, The Authors. All rights reserved.

关键词： Spin fluctuations

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Momentum dependent measures of correlations between mean transverse momentum and harmonic flow in heavy ion collisions

arXiv

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arXiv 2023年

作者： Samanta, Rupam Bozek, Piotr AGH University of Krakow Faculty of Physics and Applied Computer Science aleja Mickiewicza 30 Cracow30-059 Poland

The correlation between the mean transverse momentum and the harmonic flow coefficients is an observable which is of great interest;it is sensitive to shape fluctuations in the initial state of a relativistic nuclear collision. The measurement of that correlation coefficient in central collisions allows one to infer about the intrinsic deformation of the colliding nuclei. We propose to study the momentum dependent covariance and correlation coefficient between the mean transverse momentum and the harmonic flow in a given transverse momentum bin. Two possible constructions of such observables are provided and predictions are obtained from a viscous hydrodynamic model. We find that such momentum dependent correlation coefficients between the mean transverse momentum and the harmonic flow show a strong and nontrivial momentum dependence. We also explore the effects of granularity (nucleon width) in the initial state, the nuclear deformation, and the shear viscosity on this momentum dependent correlation coefficient. The shape of the momentum dependence of the correlation coefficient for the triangular flow is found to be sensitive to the size of small scale fluctuations in the initial state. On the other hand, the shape of the momentum dependence of the covariance between the mean transverse momentum and the harmonic flow coefficients is found to be sensitive to the value of the shear viscosity and to the granularity of the initial state. © 2023, CC BY.

关键词： Momentum

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Can we observe effects of early nonequilibrium dynamics using collective flow

arXiv

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arXiv 2023年

作者： Bozek, Piotr AGH University of Krakow Faculty of Physics and Applied Computer Science aleja Mickiewicza 30 Cracow30-059 Poland

The rapid expansion of the fireball created in a heavy-ion collision causes strong departures from local equilibrium. Such effects are especially important in the very early phase of the collision, bringing a substantial pressure asymmetry. We investigate effects of this early stage pressure asymmetry in a kinetic model without boost-invariance. In the kinetic evolution the pressure asymmetry results from the competition of the longitudinal expansion and the kinetic relaxation. Unlike the transverse flow, the directed flow is found to be very sensitive to the equilibration rate and the pressure anisotropy. © 2023, CC BY.

关键词： Heavy ions

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Reconstruction of Long-Lived Particles in LHCb CERN Project by Data Analysis and Computational Intelligence Methods 21st

Reconstruction of Long-Lived Particles in LHCb CERN Project ...

引用

21st International Conference on Computational science, ICCS 2021

作者： Golaszewski, Grzegorz Kulczycki, Piotr Szumlak, Tomasz Lukasik, Szymon Faculty of Physics and Applied Computer Science AGH University of Science and Technology Kraków Poland Systems Research Institute Polish Academy of Sciences Warsaw Poland

ISBN: (纸本)9783030779603

LHCb at CERN, Geneva is a world-leading high energy physics experiment dedicated to searching for New physics phenomena. The experiment is undergoing a major upgrade and will rely entirely on a flexible software trigger to process the data in real-time. In this paper a novel approach to reconstructing (detecting) long-lived particles using a new pattern matching procedure is presented. A large simulated data sample is applied to build an initial track pattern by an unsupervised approach. The pattern is then updated and verified by real collision data. As a performance index, the difference between density estimated by nonparametric methods using experimental streaming data and the one based on theoretical premises is used. Fuzzy clustering methods are applied for a pattern size reduction. A final decision is made in a real-time regime with rigorous time boundaries. © 2021, Springer Nature Switzerland AG.

关键词： Pattern matching

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Quantum catalysis in cavity quantum electrodynamics

引用

Physical Review Research 2024年第2期6卷 023127-023127页

作者： A. de Oliveira Junior Martí Perarnau-Llobet Nicolas Brunner Patryk Lipka-Bartosik Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University 30-348 Krakow Poland Department of Applied Physics University of Geneva 1211 Geneva Switzerland

Catalysis plays a key role in many scientific areas, most notably in chemistry and biology. Here we present a catalytic process in a paradigmatic quantum optics setup, namely the Jaynes-Cummings model, where an atom interacts with an optical cavity. The atom plays the role of the catalyst, and it allows for the deterministic generation of nonclassical light in the cavity. Considering a cavity prepared in a “classical” coherent state, and choosing appropriately the atomic state and the interaction time, we obtain an evolution with the following properties. First, the state of the cavity has been modified, and it now features nonclassicality, as witnessed by sub-Poissonian statistics or Wigner negativity. Second, the process is catalytic in the sense that the atom is deterministically returned to its initial state exactly, and it can be reused multiple times. What is more, we also show that our findings are robust under dissipation and can be applied to scenarios featuring cavity loss and atomic decay. Finally, we investigate the mechanism of this catalytic process, in particular highlighting the key role of correlations and quantum coherence.

关键词： Atom optics Cavity quantum electrodynamics Light-matter interaction Non-gaussian quantum states Optical coherence Photon statistics Quantum information theory Quantum state engineering Quantum states of light Resource theories

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Single-shot single-beam coherent Raman scattering thermometry based on optically induced air lasing

引用

Light(science & Applications) 2024年第12期13卷 3253-3260页

作者： Xu Lu Yewei Chen Francesco Mazza Siyi He Zihan Li Shunlin Huang Quanjun Wang Ning Zhang Bo Shen Yuzhu Wu Jinping Yao Ya Cheng State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai 200093China Faculty of Aerospace Engineering Delft University of TechnologyKluyverweg 12629 HS DelftThe Netherlands Institute of Modern Optics Nankai UniversityTianjin 300350China School of Microelectronics Shanghai UniversityShanghai 200444China

Thermometric techniques with high accuracy,fast response and ease of implementation are desirable for the study of dynamic combustion environments,transient reacting flows,and non-equilibrium ***,single-shot singlebeam coherent Raman scattering(SS-CRS)thermometry is developed,for the first time to our knowledge,by using air lasing as a *** show that the air-lasing-assisted CRS signal has a high signal-to-noise ratio enabling single-shot measurements at a 1 kHz repetition *** SS-CRS thermometry consistently exhibits precision of<2.3%at different temperatures,but the inaccuracy grows with the increase in *** high measurement repeatability,1 kHz acquisition rate and easy-to-implement single-beam scheme are achieved thanks to the unique temporal,spectral and spatial characteristics of air *** work opens a novel avenue for high-speed CRS thermometry,holding tremendous potential for fast diagnostics of transient reacting flows and plasmas.

关键词： scattering lasing beam

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Predicted Distribution Density Estimation for Streaming Data 1

引用

21st International Conference on Computational science, ICCS 2021

作者： Kulczycki, Piotr Rybotycki, Tomasz Faculty of Physics and Applied Computer Science AGH University of Science and Technology Kraków Poland Systems Research Institute Polish Academy of Sciences Warsaw Poland

ISBN: (数字)9783030779801

ISBN: (纸本)9783030779795

Recent growth in interest concerning streaming data has been forced by the expansion of systems successively providing current measurements and information, which enables their ongoing, consecutive analysis. The subject of this research is the determination of a density function characterizing potentially changeable distribution of streaming data. Stationary and nonstationary conditions, as well as both appearing alternately, are allowed. Within the distribution-free procedure investigated here, when the data stream becomes nonstationary, the procedure begins to be supported by a forecasting apparatus. Atypical elements are also detected, after which the meaning of those connected with new tendencies strengthens, while diminishing elements weaken. The final result is an effective procedure, ready for use without studies and laborious research. © 2021, Springer Nature Switzerland AG.

关键词： Atypical element (outlier) Distribution density Distribution-free procedure Nonparametric estimation Prediction Streaming data

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Flexible Consensus Mechanism for Current Allocation in DC Microgrid

Flexible Consensus Mechanism for Current Allocation in DC Mi...

引用

2023 International Symposium on Electrical and Electronics Engineering, ISEE 2023

作者： Tran, Khoa Dang Nguyen Ly, Trinh Thi Hoang, Khoa Truong Phuoc, Hoa Truong Le, Nhuan An Nguyen, Hung Duc Ho Chi Minh City University of Technology VNU-HCM Faculty of Electrical and Electronics Engineering Ho Chi Minh City Viet Nam University of Science Vietnam National University Faculty of Physics and Engineering Physics Department of Physics and Computer Science Ho Chi Minh City Viet Nam

ISBN: (纸本)9798350315486

Renewable energy sources (RESs) have become the predominant trend in the development of energy systems in many countries. To coordinate RESs, microgrids have emerged as an efficient and optimal solution. However, the microgrid is facing the problem of inaccurate power sharing between the generators. To address the issue, this paper proposes a control technique that combines a dynamic consensus with droop control algorithms. The proposed method calculates current sharing error by utilizing current values and consensus algorithm. Then, an external current-sharing controller is adopted to regulate the droop parameter in an inner controller for improving the current sharing among RESs. By applying the proposed control method, the current sharing accuracy is achieved in the microgrid system under different load conditions. The proposed technique is analyzed and evaluated with the scale-down microgrid consisting of three distributed generators. The simulation results of the scale-down microgrid are obtained from the PLECS simulation platform. © 2023 IEEE.

关键词： Controllers

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