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Heat capacity and quantum compressibility of dynamical spacetimes with thermal particle creation

Physical Review D 2024年第6期110卷 063504页

作者： Jen-Tsung Hsiang Yu-Cun Xie Bei-Lok Hu College of Electrical Engineering and Computer Science Department of Physics

This work continues the investigation in two recent papers on the quantum thermodynamics of spacetimes, (1) placing what was studied in [Universe 8, 291 (2022)] for thermal quantum fields in the context of early universe cosmology, and (2) extending the considerations of vacuum compressibility of dynamical spaces treated in [Phys. Rev. D 109, 065027 (2024)] to dynamical spacetimes with thermal quantum fields. We begin with a warning that thermal equilibrium condition is not guaranteed to exist or maintained in a dynamical setting and thus finite temperature quantum field theory in cosmological spacetimes needs more careful considerations than what is often described in textbooks. A full description requires nonequilibrium quantum field theory in dynamical spacetimes using “in-in” techniques. A more manageable subclass of dynamics is where thermal equilibrium conditions are established at both the beginning and the end of evolution, where the in-thermal state and the out-thermal state are both well defined. Particle creation in the full history can then be calculated in this in-out asymptotically-stationary setup via the S-matrix transition amplitudes. Here we shall assume an in-vacuum state. It has been shown that if the intervening dynamics has an initial period of exponential expansion, such as in inflationary cosmology, particles created from the parametric amplification of the vacuum fluctuations in the initial vacuum will have a thermal spectrum measured at the out-state. Under these conditions finite temperature field theory can be applied to calculate the quantum thermodynamic quantities. Here we consider a massive conformal scalar field in a closed four-dimensional Friedmann-Lemaître-Robertson-Walker universe based on the simple analytically solvable Bernard-Duncan model. We calculate the energy density of particles created from an in-vacuum and derive the partition function. From the free energy we then derive the heat capacity and the quantum compressibili

关键词： Casimir effect Finite temperature field theory Fluctuations & noise Inflation Nonequilibrium statistical mechanics Particle production Quantum fields in curved spacetime Quantum thermodynamics Vacuum stability

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Reduced order model for a streamer discharge in air 37

Reduced order model for a streamer discharge in air

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37th International Conference on Lightning Protection, ICLP 2024

作者： Jayasinghe, Hasupama Arevalo, Liliana Morrow, Richard Cooray, Vernon Department of Electrical Engineering Uppsala University Uppsala Sweden Hitachi Energy - HVDC R&D Department Sweden Department of Applied Physics Sydney University Australia

ISBN: (纸本)9783800764174

Lightning involves complex physical processes in atmospheric discharges, beginning with the development of streamer discharges. Therefore, to understand the mechanism of streamer discharges, it is important to develop a computationally efficient and an accurate numerical model. In this paper, we present the results of a 1.5-dimensional (1.5D) streamer discharge simulation using the well-established explicit finite difference method (FD) with flux-corrected transport (FCT) method. The method was applied to a streamer propagating in a 1.25cm plane-plane air gap in standard atmospheric pressure and temperature. We compared our results to those from a previously published two-dimensional (2D) axisymmetric streamer paper which is focused on the same air gap but using different numerical approaches. One can observe that the electric field is obtained with good accuracy in this 1.5D numerical simulation. The streamer position and the streamer bridging time agree with 2D results. This model has the potential to deal with moving non-uniform meshes. © 2024 IEEE, © VDE VERLAG GMBH ∙ Berlin ∙ Offenbach.

关键词： Electric discharges

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Ge_(0.92)Sn_(0.08)/Ge multi-quantum-well LEDs operated at 2-μm-wavelength on a 12-inch Si substrate

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Photonics Research 2023年第10期11卷 1606-1612页

作者： SHAOTENG WU LIN ZHANG RONGQIAO WAN HAO ZHOU KWANG HONG LEE QIMIAO CHEN YI-CHIAU HUANG XIAO GONG CHUAN SENG TAN School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Applied Materials Inc.SunnyvaleCalifornia 95054USA Department of Electrical and Computer Engineering National University of SingaporeSingapore 117576Singapore

The development of an efficient group-IV light source that is compatible with the CMOS process remains a significant goal in Si-based ***,the Ge Sn alloy has been identified as a promising candidate for realizing Si-based light ***,previous research suffered from a small wafer size,limiting the throughput and *** overcome this challenge,we report the successful growth of Ge Sn/Ge multiple-quantum-well(MQW)p-i-n LEDs on a 12-inch(300-mm)Si *** the best of our knowledge,this represents the first report of semiconductor LEDs grown on such a large *** MQW LED epitaxial layer is deposited on a 12-inch(300-mm)(001)-oriented intrinsic Si substrate using commercial reduced pressure chemical vapor *** mitigate the detrimental effects of threading dislocation densities on luminescence,the Ge Sn/Ge is grown *** to the high crystal quality and more directness in the bandgap,enhanced electroluminescence(EL)integrated intensity of 27.58 times is demonstrated compared to the Ge *** MQW LEDs exhibit EL emission near 2μm over a wide operating temperature range of 300 to 450 K,indicating hightemperature *** work shows that Ge Sn/Ge MQW emitters are potential group-IV light sources for large-scale manufacturing.

关键词： quantum emitter overcome

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Experimental Validation of Online Learning in Deep Photonic Neural Networks

Experimental Validation of Online Learning in Deep Photonic ...

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2024 Conference on Lasers and Electro-Optics, CLEO 2024

作者： Li, Xi Biswas, Disha Zhou, Peng Brigner, Wesley H. Friedman, Joseph S. Gu, Qing Department of Electrical and Computer Engineering North Carolina State University Raleigh27606 United States Department of Electrical and Computer Engineering The University of Texas at Dallas Richardson75080 United States Department of Physics North Carolina State University Raleigh27606 United States

We experimentally demonstrated supervised and unsupervised online learning for the "NCSUTD" letter recognition task in a deep photonic neural network using fiber optics and proposed a chip-scale crossbar mul... 详细信息

ISBN: (纸本)9781957171395

关键词： Unsupervised learning

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Static Eccentricity Fault Analysis in Three-Phase Induction Motors Using Current Signal 2

Static Eccentricity Fault Analysis in Three-Phase Induction ...

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2nd Edition IEEE International Conference on Metrology for eXtended Reality, Artificial Intelligence and Neural engineering, MetroXRAINE 2023

作者： Refaat, Shady S. Al-Shemmery, Ahmed Abdulmawjood, Kais Kameli, Sayed Mohammad Abuelrub, Abdelaziz Texas A&m University at Qatar Electrical and Computer Engineering Department Doha Qatar School of Physics Engineering and Computer Science University of Hertfordshire Hatfield United Kingdom Ontario Tech University Department of Electrical Computer and Software Engineering Canada

ISBN: (纸本)9798350300802

Preventing mechanical faults in motors is often impossible, early detection of air gap eccentricity faults in induction motors is critical in preventing damage to the machine. Therefore, designing a reliable, effective fault detection system can help to improve its operation. This paper presents an analysis of static eccentricity fault for induction motors. This paper proposes the use of the empirical mode decomposition (EMD) followed by the implementation of wavelet packet decomposition (WPD) on current signals to extract and identify static eccentricity fault frequency signatures. The accuracy in fault detection and diagnosis of the effects of static airgap eccentricity using stator current based monitoring with WPD based on EMD is experimentally verified. © 2023 IEEE.

关键词： Airgap eccentricity fault empirical mode decomposition induction machine wavelet packet decomposition

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Differential coding scheme based FSO channel for optical coherent DP-16 QAM transceiver systems

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Journal of Optical Communications 2024年第2期45卷 331-345页

作者： Urooj, Shabana Alwadai, Norah Muhammad Sorathiya, Vishal Lavadiya, Sunil Parmar, Juveriya Patel, Shobhit K. Abd El-Aziz, Ismail A. Rashed, Ahmed Nabih Zaki Electronics and Electrical Communications Engineering Department Faculty of Electronic Engineering Menoufia University Menouf 32951 Egypt Department of Electrical Engineering College of Engineering Princess Nourah bint Abdulrahman University Riyadh84428 Saudi Arabia Department of Physics College of Sciences Princess Nourah bint Abdulrahman University Riyadh84428 Saudi Arabia Department of Information and Communication Technology Marwadi University Rajkot India Department of Physics Marwadi University Rajkot360003 India Department of Electronics and Communication Engineering Marwadi University Rajkot360003 India Department of Computer Engineering Marwadi University Rajkot360003 India Benha Faculty of Engineering Benha University Benha Egypt

This article has indicated optical coherent differential polarization (DP) 16 quadrature amplitude modulation (QAM) transceiver systems with free-space optical (FSO) channel in the presence of differential coding scheme. The optical coherent DP 16-QAM receiver executes the reverse process conversion of the optical signal into an electrical one that is detected to the users. The proposed optical coherent DP-16 QAM transceiver systems based FSO channel model with differential coding has been presented and compared with the previous model. However, the simulation results have confidence realization about the superiority of the proposed simulation model. Hence the proposed optical coherent DP-16 QAM transceiver systems simulation model with differential coding is verified and validated the enhancement performance based on simulation performance parameters. © 2024 Walter de Gruyter GmbH. All rights reserved.

关键词： Quadrature amplitude modulation

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Efficient storage of multidimensional telecom photons in a solid-state quantum memory

Optica Quantum

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Optica Quantum 2025年第3期3卷 295-302页

作者： Zongfeng Li Yisheng Lei Trevor Kling Mahdi Hosseini Department of Electrical and Computer Engineering and Applied Physics Program Northwestern University Evanston Illinois 60208 USA Elmore Family School of Electrical and Computer Engineering Purdue University West Lafayette Indiana 47907 USA

Efficient storage of telecom-band quantum optical information represents a crucial milestone for establishing distributed quantum optical networks. Erbium ions in crystalline hosts provide a promising platform for telecom quantum memories; however, their practical applications have been hindered by demanding operational conditions, such as ultra-high magnetic fields and ultra-low temperatures. In this work, we demonstrate the storage of telecom photonic qubits encoded in polarization, frequency, and time-bin bases. Using the atomic frequency comb protocol in an Er 3+ -doped crystal, we developed a memory initialization scheme that improves storage efficiency by over an order of magnitude. The observed results were made possible by the deliberate selection of the pumping sequence and the minimization of lattice interactions, to the extent possible without the use of dilution refrigerators or superconducting magnets.

关键词： Frequency combs Optical networks Photon polarization Quantum computation Quantum information Quantum memories

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PLC and Human Machine Interface based PV Condition Monitoring Structure Comprising an Innovative Fault Detection Scheme 3

PLC and Human Machine Interface based PV Condition Monitorin...

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3rd International Conference on Energy Transition in the Mediterranean Area, SyNERGY MED 2024

作者： Nedaei, Amir Eskandari, Aref Pourshahbaz, Nima Salehpour, Sherko Parvin, Parviz Livera, Andreas Makrides, George Aghaei, Mohammadreza Department of Electrical Engineering Tehran Iran Department of Electrical Engineering Tehran Iran Department of Physics and Energy Engineering Tehran Iran PHAENTON Centre of Excellence for Intelligent Efficient and Sustainable Energy Solutions PV Technology Laboratory Department of Electrical and Computer Engineering Nicosia Cyprus PHAETHON Centre of Excellence for Intelligent Efficient and Sustainable Energy Solutions PV Technology Laboratory Department of Electrical and Computer Engineering Nicosia Cyprus Department of Ocean Operations and Civil Engineering Ålesund Norway Freiburg Germany

ISBN: (纸本)9798350375923

Photovoltaic (PV) systems operate outdoors and are inevitably exposed to various environmental stresses. These stresses may result in several faults and failures which can affect the PV proper performance in terms of reducing the output power and even in some catastrophic cases may end in fire hazards. Therefore, PV systems need to be constantly and carefully monitored to maintain their appropriate performance. In this paper, a condition monitoring (CM) scheme is proposed based on the Programmable Logic Controller (PLC). The scheme is capable to detect line-to-line (LL) and line-to-ground (LG) faults on the DC-side of the PV array and also enables the system to track the maximum power point (MPP) and provides the operator with the real-time PV information via Human-Machine Interface (HMI). © 2024 IEEE.

关键词： Fire hazards

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A Voting based Assimilation Method for the Winning Neurons in Multi-Level SOM to Cluster the Convoluted Biomarkers of a Time Varying 'Omic Data 15

A Voting based Assimilation Method for the Winning Neurons i...

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15th International Conference on Computing Communication and Networking Technologies, ICCCNT 2024

作者： Dey, Anirban Sharma, Kaushik Das Bhattacharjee, Pritha Chatterjee, Amitava University of Calcutta Department of Applied Physics Kolkata India University of Calcutta Department of Environmental Science Kolkata India Jadavpur University Department of Electrical Engineering Kolkata India

ISBN: (纸本)9798350370249

Early detection and modelling of disease development are crucial for effective healthcare. Diseases develop over time, with changes in 'omic expressions, leading to genotypic or phenotypic changes in the sample. These changes are unique to disease samples and can develop in various parts of the body and continue to grow, if not addressed in a timely fashion. However, due to the availability of a small population of very high dimensional 'omic samples, this presents a significant challenge. Thus, dimensionality reduction techniques are essential to simplify the data while preserving its core structure. This work focuses on the technique of Non-Negative Matrix Factorization (NMF), where the decomposed basis and coefficient matrices are component-wise non-negative. NMF has recently gained prominence for analyzing time-varying 'omic data and the present work uses a contemporary variant of NMF, called flexible NMF (FNMF). In a bid to effective extract differentially expressed biomarkers using NMF, this work proposes a voting based assimilation method for factorized convoluted biomarkers obtained from FNMF using a hybrid MLSOM (Hy-MLSOM) architecture. This results in an enhanced representation of the 'omic data, thereby facilitating more effective and precise disease detection. © 2024 IEEE.

关键词： Biomarker Identification Feature Representational Learning Microarray Data Analysis Non Negative Matrix Factorization Self-Organizing Maps

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Temporal Shaping of Light at the Nanoscale with Photonic Funnels

Temporal Shaping of Light at the Nanoscale with Photonic Fun...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： LaMountain, J. Raju, A. Briggs, A. Wasserman, D. Podolskiy, V.A. Department of Physics and Applied Physics University of Massachusetts Lowell One University Avenue LowellMA01854 United States Department of Electrical and Computer Engineering University of Texas Austin AustinTX78758 United States

Photonic funnels have been demonstrated as a flexible platform to confine light to deep subwavelength spatial areas. Here we consider the utility of this platform to provide temporal, as well as spatial, light shaping...

ISBN: (纸本)9781957171258

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