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7th International Conference on Engineering Geophysics, ICEG 2023

作者： Safa, Khadija Elsamani, Mahmoud A. Khaldi, Hunaida Abdel-Fattah, Mohammed Hamdan, Hamdan University of Sharjah Petroleum Geosciences and Remote Sensing Program Department of Applied Physics and Astronomy United Arab Emirates Sharjah Heritage Institute United Arab Emirates

The Sharjah Institute of Heritage collaborated with the University of Sharjah's Petroleum Geoscience and Remote Sensing program to locate a buried well at a historic heritage site in Liluiyyah, Khorfakkan, United Arab Emirates. The well was an important source of water for the community, and its location was unknown as it had become buried beneath layers of sand and debris. The GPR survey was conducted over almost 600 m2 and more than 375 GPR profiles were obtained. The processed data produced multiple anomalies that were marked and recorded in a Geographic Information System (GIS) database. A group of GPR anomalies was identified in the northern section of the plot, indicating the presence of stones comprising the well mouth. However, after conducting an excavation at the proposed site, the water well was not found. The research team re-evaluated the GPR sections and slices, concentrating on anomalies deeper than 1 m depth and identified a circular shape anomaly at a depth of 15 ns and deeper in the northwestern part of Grid A. A trial pit was executed at the proposed location, revealing the anticipated water well at a depth of 1.2m from the existing ground level. © 2024 7th International Conference on Engineering Geophysics, ICEG 2023. All rights reserved.

关键词： Geophysics

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Multifunctional resonant wavefront-shaping meta-optics based on multilayer and multi-perturbation nonlocal metasurfaces

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Light(Science & Applications) 2022年第9期11卷 2194-2206页

作者： STEPHANIE CMALEK ADAM COVERVIG ANDREA ALÙ NANFANG YU Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY 10027USA Photonics Initiative Advanced Science Research CenterCity University of New YorkNew YorkNY 10031USA Physics Program Graduate CenterCity University of New YorkNew YorkNY 10016USA

Photonic devices rarely provide both elaborate spatial control and sharp spectral control over an incoming *** optical metasurfaces,for example,the localized modes of individual meta-units govern the wavefront shape over a broad bandwidth,while nonlocal lattice modes extended over many unit cells support high quality-factor ***,we experimentally demonstrate nonlocal dielectric metasurfaces in the near-infrared that offer both spatial and spectral control of light,realizing metalenses focusing light exclusively over a narrowband resonance while leaving off-resonant frequencies *** devices attain this functionality by supporting a quasi-bound state in the continuum encoded with a spatially varying geometric *** leverage this capability to experimentally realize a versatile platform for multispectral wavefront shaping where a stack of metasurfaces,each supporting multiple independently controlled quasi-bound states in the continuum,molds the optical wavefront distinctively at multiple wavelengths and yet stay transparent over the rest of the *** a platform is scalable to the visible for applications in augmented reality and transparent displays.

关键词： spectrum resonant supporting

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A New Pulse Skipping Control for Series Resonant Converter 3

A New Pulse Skipping Control for Series Resonant Converter

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3rd IEEE Industrial Electronics Society Annual On-Line Conference, ONCON 2024

作者： Bhowmick, Supratik Chakraborty, Soham Maiti, Suman Indian Institute of Technology Kharagpur Department of Electrical Engineering Kharagpur721302 India Calcutta University UG Program of Electrical Engineering Department of Applied Physics Kolkata700009 India

ISBN: (纸本)9798331540319

This paper proposes a pulse skipping based combined frequency and duty ratio control for a series resonant converter which is targeted for voltage regulator applications. The proposed pulse skipping control combines duty ratio based phase shifted control for maintaining output voltage at its reference value, along with frequency based control which assists in development of the pulse skipping algorithm. This algorithm is structured so that pulses are skipped in generated gate pulses for upper switching devices present in the converter whenever the output voltage tries to be higher than its specified maximum value or be lower than its specified minimum value. These maximum and minimum voltages are determined based on its reference voltage and allowable voltage ripple within which the oscillations in output voltage are desired to be in. The converter system with the proposed control method is simulated in MATLAB/Simulink environment to validate its performance under transient conditions e.g., variation in load resistance and output voltage reference. The system performance with proposed method is also compared with conventional method where the proposed control demonstrates its superiority by significantly minimizing the output voltage ripple. © 2024 IEEE.

关键词： Resonant converters

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Performance Optimization of Series Resonant Converter by Combined Frequency and Duty Ratio Control 3

Performance Optimization of Series Resonant Converter by Com...

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3rd IEEE Industrial Electronics Society Annual On-Line Conference, ONCON 2024

作者： Chakraborty, Soham Bhowmick, Supratik Maiti, Suman Calcutta University UG Program of Electrical Engineering Department of Applied Physics Kolkata700009 India Indian Institute of Technology Kharagpur Department of Electrical Engineering Kharagpur721302 India

ISBN: (纸本)9798331540319

Resonant converters are widely used for voltage regulator applications. The basic converters i.e., Series resonant Converter (SRC) and Parallel Resonant Converter (PRC) are having some merits and limitations. These are addressed in multi element topologies at the cost of adding extra elements. This work takes up the SRC and reports a combined frequency and duty ratio control for performance optimization of the SRC. The key issue of SRC is that the voltage cannot be controlled at a low Q (i.e. Quality factor) operation. For example, at no load Q becomes zero making the converter inert to frequency variation. This however can be eliminated by pulse width modulation technique. Duty ratio can be properly controlled to achieve the output voltage at an extended load range. The work further takes up challenge to make efficiency optimized. For this a combined control of duty ratio and frequency are proposed. Efficiency Optimization Control (EOC) requires two voltage sensors (one at the input side and another at the output) and a current sensor. Following this, a new minimum rms current algorithm is developed that only requires a current and a voltage sensor. All the proposed techniques are simulated and verified using MATLAB/Simulink. © 2024 IEEE.

关键词： Resonant converters

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Conversion of twisted light to twisted excitons using carbon nanotubes

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npj Computational Materials 2022年第1期8卷 392-402页

作者： Xiaoning Zang Nirpendra Singh Mark T.Lusk Udo Schwingenschlögl Applied Physics Program Physical Sciences and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal23955-6900Saudi Arabia Department of Physics Khalifa University of Science and TechnologyAbu Dhabi127788United Arab Emirates Department of Physics Colorado School of MinesGoldenCO80401USA

Carbon nanotubes are explored as a means of coherently converting the orbital angular momentum of light to an excitonic form that is more amenable to quantum information *** analytical analysis,based on dynamical conductivity,is used to show that orbital angular momentum is conserved,modulo N,for a carbon nanotube illuminated by radially polarized,twisted *** result is numerically demonstrated using real-time time-dependent density functional theory which captures the absorption of twisted light and the subsequent transfer of twisted *** results suggest that carbon nanotubes are promising candidates for constructing optoelectronic circuits in which quantum information is more readily processed while manifested in excitonic form.

关键词： twisted carbon light

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Real-space screening of quantum spin-Hall insulators

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Physical Review Materials 2024年第12期8卷 124203-124203页

作者： Alexander C. Tyner Pallab Goswami Graduate Program in Applied Physics Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA

It was shown by Prodan in 2009 that both magnetic and nonmagnetic two-dimensional insulators can support quantized spin-Chern number in the absence of spin-rotation symmetry as a bulk topological invariant, which is robust against impurity effects. Recent studies on higher-order and fragile topological insulators further demonstrate that the spin-Chern number can exist without gapless edge states. Therefore, the presence of generalized quantum spin-Hall states in real materials can be difficult to identify using only symmetry-based indicators and Wannier obstruction. Such phases require more sophisticated probes of bulk topology. Magnetic flux tube has emerged as one such singular real-space probe that leads to spin-charge separation and allows for a precise diagnosis of the spin-Chern number. In this paper, we develop an automated workflow to scan the database of experimentally relevant, large band-gap, two-dimensional insulators using magnetic flux tubes. The results reveal many material candidates of higher-order topological insulators possessing double spin-Chern number, including the 1H-MX2 family of transition metal dichalcogenides. Our paper has broad implications for current efforts to employ these materials for new platforms of moiré systems.

关键词： Magnetic flux

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Terahertz phonon polariton concentrator based on perovskite oxides

Terahertz phonon polariton concentrator based on perovskite ...

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2023 Conference on Lasers and Electro-Optics, CLEO 2023

作者： Xu, Rui Lin, Tong Luo, Jiaming Chen, Xiaotong Blackert, Elizabeth R. Moon, Alyssa R. JeBailey, Khalil M. Zhu, Hanyu Department of Materials Science and Nano Engineering Rice University Houston United States Applied Physics Graduate Program Rice University Houston United States Program Rice University Houston United States

ISBN: (纸本)9781957171258

We report the experimental demonstration of surface phonon-polaritonic devices in a broad spectral range of 7-13 THz based on SrTiO3. We designed planar ultrafast concentrators that amplifies transient electric field by 6 times and measured an average field of 0.5 GV/m in an optically resolvable area in the far field. © 2023 The Author(s)

关键词： Perovskite

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Correlations in interacting electron liquids: Many-body statistics and hyperuniformity

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Physical Review B 2024年第10期110卷 104201页

作者： Haina Wang Rhine Samajdar Salvatore Torquato Department of Chemistry Department of Physics Princeton Center for Theoretical Science Princeton Materials Institute Program in Applied and Computational Mathematics

Disordered hyperuniform many-body systems are exotic states of matter with novel optical, transport, and mechanical properties. These systems are characterized by an anomalous suppression of large-scale density fluctuations compared to ordinary liquids. The structure factor of disordered hyperuniform systems often obeys the scaling relation S(k)∼Bkα with B,α>0 in the limit k→0. Ground states of d-dimensional free fermionic gases, which are fundamental models for many metals and semiconductors, are key examples of quantum disordered hyperuniform states with important connections to random matrix theory. However, the effects of electron-electron interactions as well as the polarization of the electron liquid on hyperuniformity have not been explored thus far. In this paper, we systematically address these questions by deriving the analytical small-k behaviors (and, associated, α and B) of the total and spin-resolved structure factors of quasi-one-dimensional, two-dimensional, and three-dimensional electron liquids for varying polarizations and interaction parameters. We validate that these equilibrium disordered ground states are hyperuniform, as dictated by the fluctuation-compressibility relation. Interestingly, free fermions, partially polarized interacting fermions, and fully polarized interacting fermions are characterized by different values of the small-k scaling exponent α and coefficient B. In particular, partially polarized fermionic liquids exhibit a unique form of multihyperuniformity, in which the net configuration exhibits a stronger form of hyperuniformity (i.e., larger α) than each individual spin component. The detailed theoretical analysis of such small-k behaviors enables the construction of corresponding equilibrium classical systems under effective one- and two-body interactions that mimic the pair statistics of quantum electron liquids. Our paper thus reveals that highly unusual hyperuniform and multihyperuniform states can be achieved in simple

关键词： Electronic structure Quantum many-body systems Two-dimensional electron gas

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Direct current generation by dielectric loss in ferroelectrics

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Physical Review B 2024年第4期110卷 045129-045129页

作者： Takahiro Morimoto Naoto Nagaosa Department of Applied Physics (CEMS) Wako Saitama 351-0198 Japan Fundamental Quantum Science Program TRIP Headquarters

We study direct current (DC) generation induced by microwave irradiation to ferroelectric materials. The DC generation originates from microwave absorption called dielectric loss due to the delay of a dielectric response. Such current generation can be formulated as the low-frequency limit of the phonon shift current which arises from an increase of electric polarization accompanying photoexcitation of phonons due to the electron-phonon coupling. To study the DC generation by the dielectric loss, we apply the diagrammatic treatment of nonlinear optical responses to photoexcitations of phonons and derive the general formula for phonon shift current. We then study the DC generation in the low-frequency region and find that the current scales as ∝ω2 for the linearly polarized light and time-reversal symmetric systems. We estimate the order of magnitude of the DC generation by dielectric loss, indicating its feasibility for experimental detection in the GHz region.

关键词： Phonons Photovoltaic effect Ferroelectrics Diagrammatic methods

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AI-enabled Lorentz microscopy for quantitative imaging of nanoscale magnetic spin textures

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npj Computational Materials 2024年第1期10卷 2102-2111页

作者： Arthur.R.C.McCray Tao Zhou Saugat Kandel Amanda Petford-Long Mathew J.Cherukara Charudatta Phatak Materials Science Division Argonne National LaboratoryLemontILUSA Applied Physics Program Northwestern UniversityEvanstonILUSA Center for Nanoscale Materials Argonne National LaboratoryLemontILUSA Advanced Photon Source Argonne National LaboratoryLemontILUSA Department of Materials Science and Engineering Northwestern UniversityEvanstonILUSA

The manipulation and control of nanoscale magnetic spin textures are of rising interest as they are potential foundational units in next-generation computing *** this requires a quantitative understanding of the spin texture behavior under external stimuli using in situ *** transmission electron microscopy(LTEM)enables real-space imaging of spin textures at the nanoscale,but quantitative characterization of in situ data is extremely ***,we present an AI-enabled phase-retrieval method based on integrating a generative deep image prior with an image formation forwardmodel for *** approach uses a single out-of-focus image for phase retrieval and achieves significantly higher accuracy and robustness to noise compared to existing ***,our method is capable of isolating sample heterogeneities from magnetic contrast,as shown by application to simulated and experimental *** approach allows quantitative phase reconstruction of in situ data and can also enable near real-time quantitative magnetic imaging.

关键词： textures magnetic Lorentz

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