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A METAL PLATE FRESNEL LENS FOR 4 GHZ SATELLITE TV RECEPTION

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 1984年第3期32卷 306-307页

作者： SHUTER, WLH CHAN, CP LI, EWP YEUNG, AKC Engineering Physics Program. Department of Physics University of British Columbia Vancouver BC Canada

A metal plate Fresnel lens antenna with aperture dimensions 12 ft \times 12 ft , and fed by a pyramidal horn has been built for satellite TV reception at 4 GHz. When used with a commercial receiver equipped with a 120K LNA it produced good video pictures from the geostationary satellite Satcom F3. We believe this to be the first application of a Fresnel lens antenna for ground-based satellite TV reception.

关键词： Lenses Satellite broadcasting TV Satellite antennas Testing Aperture antennas Optical design Feeds Antennas and propagation Horn antennas

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Impact of Quantum Well Thickness on Efficiency Loss in InGaN/GaN LEDs: Challenges for Thin-Well Designs

arXiv

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arXiv 2025年

作者： Li, Xuefeng Pant, Nick Rahman, Sheikh Ifatur Armitage, Rob Rajan, Siddharth Kioupakis, Emmanouil Feezell, Daniel University of New Mexico AlbuquerqueNM87106 United States Department of Materials Science & Engineering University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States Lumileds LLC San JoseCA95131 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States

We investigate the impact of quantum well (QW) thickness on efficiency loss in c-plane InGaN/GaN LEDs using a small-signal electroluminescence (SSEL) technique. Multiple mechanisms related to efficiency loss are independently examined, including injection efficiency, carrier density vs. current density relationship, phase space filling (PSF), quantum confined stark effect (QCSE), and Coulomb enhancement. An optimal QW thickness of around 2.7 nm in these InGaN/GaN LEDs was determined for quantum wells having constant In composition. Despite better control of deep-level defects and lower carrier density at a given current density, LEDs with thin QWs still suffer from an imbalance of enhancement effects on the radiative and intrinsic Auger-Meitner recombination coefficients. The imbalance of enhancement effects results in a decline in internal quantum efficiency (IQE) and radiative efficiency with decreasing QW thickness at low current density in LEDs with QW thicknesses below 2.7 nm. We also investigate how LED modulation bandwidth varies with quantum well thickness, identifying the key trends and their implications for device performance. Copyright © 2025, The Authors. All rights reserved.

关键词： Semiconductor quantum wells

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BPS2025 - Transport of chemical signals within cell filopodia

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Biophysical Journal 2025年第3期124卷 143a-143a页

作者： Mohamed O. Mahmoud Khattab C. Nadir Kaplan Engineering Mechanics Program Virginia Tech Blacksburg VA USA Department of Physics Virginia Tech Blacksburg VA USA

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Investigating the effects of QCD matter’s electrical conductivity on charge dependent directed flow

arXiv

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arXiv 2025年

作者： Benoit, Nicholas J. Miyoshi, Takahiro Nonaka, Chiho Takahashi, Hiroyuki R. Physics Program Graduate School of Advanced Science and Engineering Hiroshima University Higashi-Hiroshima739-8511 Japan Department of Physics Nagoya University Nagoya464-8602 Japan Kobayashi Maskawa Institute Nagoya University Nagoya464-8602 Japan International Institute for Sustainability with Knotted Chiral Meta Matter Hiroshima University Higashi-Hiroshima739-8511 Japan Department of Natural Sciences Faculty of Arts and Sciences Komazawa University Tokyo154-8525 Japan

Charge dependent directed flow is an important observable of electromagnetic fields in relativistic heavy-ion collisions. We demonstrate how the difference in charge dependent directed flows between protons and antiprotons is sensitive to the resistivity, inverse of quark-gluon plasma’s electric conductivity, over different collision centralities. Our model numerically solves the 3+1D relativistic resistive magneto-hydrodynamic (RRMHD) equations, assuming the electric conductivity to be a scalar. For this work, we focus on symmetric Au + Au collisions at the top RHIC energy of √s = 200 GeV. We illustrate the time evolution of the electromagnetic fields in our model and connect that to the charge dependent directed flow results. Our results highlight the importance of modeling quark-gluon plasma’s electric conductivity for charge dependent observables in relativistic heavy-ion collisions. Copyright © 2025, The Authors. All rights reserved.

关键词： Heavy ions

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Early and advanced crystallization stages in lithia-alumina-silica glasses nucleated by ZrO2

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Ceramics International 2025年

作者： Revelo, Raúl Julián Souza, Mauricio Lima Pena, Rafaella Bartz Yoshida, Satoshi Zanotto, Edgar Dutra Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil São Carlos Institute of Physics University of São Paulo SP São Carlos13566-590 Brazil Materials Integration Laboratories AGC Inc 1-1 Suehiro-Cho Tsurumi-Ku Kanagawa Yokohama230-0045 Japan

ZrO2 is one of the most effective and widely used nucleating agents in various families of glass-ceramics;however, its detailed mechanism remains a subject of debate. Understanding its nucleation mechanism requires a thorough analysis of microstructural evolution and the identification of factors influencing this process. This study investigates the effects of ZrO2 incorporation on the internal nucleation and microstructural evolution in stoichiometric LAS (Li2O·Al2O3·nSiO2) glass-ceramics of varying composition. Glasses with different SiO2 molar ratios (n = 2, 4, 5, and 6) were prepared with ZrO2 additions of 3.0 and 3.5 mol%. Several thermal treatments were employed, followed by characterization using XRD, SEM, STEM, and Raman spectroscopy. The results indicate that a minimum of 3.5 mol% ZrO2 is required to induce internal nucleation in LAS glasses with n = 4, 5, and 6. In these compositions, Zr-enriched regions formed through liquid-liquid phase separation serve as preferential sites for ZrO2 crystal precipitation, which subsequently induces the nucleation of β-quartz solid solution. Upon further treatment at higher temperatures, this metastable phase transforms into β-spodumene or its solid solution. As expected, increasing SiO2 content enhances glass network polymerization, as evidenced by the increased presence of Q3 species in Raman spectroscopy, leading to higher characteristic temperatures of glass transition and peak crystallization in DSC analyses. A higher SiO2 content results in fewer but larger crystals, whereas a lower SiO2 content promotes a higher number density of crystals within the glass matrix. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Glass ceramics

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Non-Empirical Models for Assessing the Thermal Properties of Nonlinear Polyatomic Molecules

SSRN

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SSRN 2025年

作者： Eyube, Edwin Samson Yabwa, D. Onate, C.A. Makama, E.K. Tahir, A.M. Omugbe, E. Makasson, C.R. Umar, U. Department of Physics Faculty of Physical Sciences Modibbo Adama University P.M.B. 2076 Adamawa State Yola Nigeria Department of Physics Faculty of Science Taraba State University P.M.B. 1176 Taraba State Jalingo Nigeria Physics Program College of Agriculture Engineering and Science Bowen University Iwo Osun State Nigeria Department of Physics Faculty of Natural Sciences University of Jos P.M.B. 2084 Plateau State Jos Nigeria Department of Science Laboratory Technology School of Science and Technology Adamawa State Polytechnic P.M.B. 2146 Adamawa State Yola Nigeria Department of Physics University of Agriculture and Environmental Sciences P.M.B. 1038 Imo State Umuagwo Nigeria Department of Physics Modibbo Adama University Secondary School P.M.B. 2076 Adamawa State Yola Nigeria

The current study explores computational models developed using the improved Scarf potential and harmonic oscillator to simulate vibrational modes in nonlinear polyatomic systems. These models are derived from the partition functions of the system and are designed to predict molar Gibbs free energy, entropy, enthalpy, and heat capacity. The models are applied to nonlinear polyatomic molecules, including aluminum chloride (AlCl2), boron difluoride (BF2), and sulfur dioxide (SO2). For Gibbs free energy and entropy, the equations yield a mean percentage relative error (MPRE) of no more than 0.09% compared to NIST data. Furthermore, using the heat capacity expression, MPRE values of 0.968%, 1.035%, and 2.764% are obtained for AlCl2, BF2, and SO2, respectively. These findings are in good agreement with results from existing literature on nonlinear molecules © 2025, The Authors. All rights reserved.

关键词： Free energy

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Non-Empirical Models for Assessing the Thermal Properties of Nonlinear Polyatomic Molecules

SSRN

引用

SSRN 2025年

作者： Eyube, Edwin Samson Yabwa, D. Onate, C.A. Makama, E.K. Tahir, A.M. Omugbe, E. Makasson, C.R. Umar, U. Department of Physics Faculty of Physical Sciences Modibbo Adama University P.M.B. 2076 Adamawa State Yola Nigeria Department of Physics Faculty of Science Taraba State University P.M.B. 1176 Taraba State Jalingo Nigeria Physics Program College of Agriculture Engineering and Science Bowen University Osun State Iwo Nigeria Department of Physics Faculty of Natural Sciences University of Jos P.M.B. 2084 Plateau State Jos Nigeria Department of Science Laboratory Technology School of Science and Technology Adamawa State Polytechnic P.M.B. 2146 Adamawa State Yola Nigeria Department of Physics University of Agriculture and Environmental Sciences Umuagwo P.M.B. 1038 Imo State Nigeria Department of Physics Modibbo Adama University Secondary School P.M.B. 2076 Adamawa State Yola Nigeria

关键词： Free energy

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Quantum oscillation studies of the nodal line semimetal Ni3In2S2-xSex

arXiv

引用

arXiv 2025年

作者： Sharma, M.M. Chhetri, Santosh Karki Acharya, Gokul Graf, David Upreti, Dinesh Dahal, Sagar Un Nabi, Md Rafique Rahman, Sumaya Sakon, Josh Churchill, Hugh O.H. Hu, Jin Department of Physics University of Arkansas FayettevilleAR72701 United States National High Magnetic Field Lab TallahasseeFL32310 United States MonArk NSF Quantum Foundry University of Arkansas FayettevilleAR72701 United States Material Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States Department of Chemistry & Biochemistry University of Arkansas FayettevilleAR72701 United States

Ternary shandite compounds with the general formula T3M2X2 (T = Ni, Co, Rh or Pd;M = Sn, In, or Pb;and X = S or Se) have emerged as a large pool of topological semimetals. This family of compounds hosts different topological phases for various combinations of T, M and X. This paper reports the observation of quantum oscillations under the high magnetic fields in Ni3In2S2-xSex single crystals. Angular dependence of oscillation frequency suggests an evolution of the Fermi surface from three-dimensional to two-dimensional on Se substitution for S in Ni3In2S2. The effective mass obtained for each composition by fitting the oscillation amplitude with the Lifshitz-Kosevich formula, shows no significant change, suggesting that the topological phase might be relatively robust against enhanced SOC upon Se doping in Ni3In2S2 Copyright © 2025, The Authors. All rights reserved.

关键词： Single crystals

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B(s)→D(s)(*)M decays in the presence of final-state interactions

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Physical Review D 2025年第9期111卷 095020-095020页

作者： Albertus Hariwangsa Panuluh Satoshi Tanaka Hiroyuki Umeeda Department of Physics Education Faculty of Teacher Training and Education Sanata Dharma University Paingan Maguwohardjo Sleman Yogyakarta 55282 Indonesia Physics Program Graduate School of Advanced Science and Engineering Hiroshima University 1-3-1 Kagamiyama Higashi-Hiroshima 739-8526 Japan Scientific Computational Division Nippon Advanced Information Service (NAIS Co. Inc.) 416 Muramatsu Tokaimura Naka-gun Ibaraki 319-1112 Japan Center for Theoretical Physics and College of Physics Jilin University Changchun 130012 China China Center of Advanced Science and Technology Beijing 100190 China Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China

In light of the recent data for B¯(s)→D(s)(*)P and B¯(s)→D(s)V decays, we perform a model-independent phenomenological analysis in the presence of quasielastic rescattering. With the Wilson coefficients including contributions beyond the standard model, the lifetimes of the B meson and Bd0−B¯d0 mixing are investigated to clarify correlations among the observables. We show that parameter regions for quasielastic rescattering, the size of color-suppressed tree amplitudes, and new physics are constrained due to the lifetime data. As a consequence, it is revealed that this scenario can be tested by the future LHCb measurement of the width difference in Bd0−B¯d0 mixing and semileptonic CP asymmetry.

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Analysis of the operation of thin nanowire photoelectrodes for solar energy conversion (vol 5, pg 5203, 2012)

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ENERGY & ENVIRONMENTAL SCIENCE 2012年第12期5卷 9946-9946页

作者： Foley, Justin M. Price, Michelle J. Feldblyum, Jeremy I. Maldonado, Stephen Program in Applied Physics Macromolecular Engineering Department of Chemistry 930 N University Ann Arbor Michigan

The solar energy conversion properties of thin Si and GaP nanowire photoelectrodes in photoelectrochemical cells have been examined through sets of finite-element simulations. A discussion describing the motivation behind nanostructured, high aspect ratio semiconductor photoelectrode designs and a brief survey of current experimental results reported for nanostructured semiconductor photoelectrodes in photoelectrochemical cells are presented first. An analysis is then shown that outlines the primary recombination pathways governing the steady-state current-potential behaviors of thin, cylindrical nanowire photoelectrodes, with explicit expressions detailing the differences between planar and cylindrical photoelectrodes arising from the solution of carrier fluxes in planar and cylindrical geometries. Results from finite-element simulations used to model the key features of thin nanowire photoelectrodes under low-level injection conditions are shown that illustrate which recombination pathway(s) is operative under various experimental conditions. Specifically, the respective effects of non-uniform doping, tapering along the length, variation in charge carrier mobilities and lifetimes, changes in nanowire radius, and changes in the density of surface defects on the observable photocurrent-potential responses are reported. These cumulative results serve as guides for future experimental work aimed at improving the attainable solar energy conversion efficiencies of doped semiconductor nanowire photoelectrodes. Lastly, separate simulations that model lightly doped nanowire photoelectrodes under high-level injection conditions are discussed. These results suggest discrete, ohmic-selective contacts may afford a way to circumvent the stringent doping requirements discussed herein for thin nanowire photoelectrodes.

关键词： Nanowires

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