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arXiv 2023年

作者： Karmakar, Annesha Kumar, G. Anil Bhavika Anand, V. Pal, Anikesh Nuclear Engineering and Technology Program Department of Mechanical Engineering Indian Institute of Technology-Kanpur India Radiation Detectors and Spectroscopy Laboratory Department of Physics Indian Institute of Technology Roorkee India Department of Mechanical Engineering Indian Institute of Technology-Kanpur India

The use of programmable hardware devices is imperative for digital based pulse shape discrimination (PSD) to differentiate between various types of radiation. This work reports the development of a PSD algorithm based on tail area and total area, eliminating the need for programmable hardware. The pulses were collected using BC501 detector and Pu-Be source from a digitizer in the oscilloscope mode. The algorithm performs crucial functions such as pulse normalization, shaping, identification and removal of multiple peaks and threshold determination. The algorithm provides neutron and γ-ray counts, scatter plot, and FoM. In order to test the efficacy of our proposed algorithm, pulses were collected from a different source-detector setup comprising BC501A detector and an Am-Be source from a digitizer in the oscilloscope mode and Charge Integration (CI) mode. The results obtained from our proposed algorithm and CI method clearly indicates a good agreement in terms of number of neutrons and γ-rays and Figure-of-Merit (FoM), thus providing cost-effective alternative method for neutron and γ-ray discrimination, offering flexibility and accuracy without specialized hardware. © 2023, CC BY.

关键词： Gamma rays

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CVIT: CONTINUOUS VISION TRANSFORMER FOR OPERATOR LEARNING

arXiv

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arXiv 2024年

作者： Wang, Sifan Seidman, Jacob H. Sankaran, Shyam Wang, Hanwen Pappas, George J. Perdikaris, Paris Institution for Foundation of Data Science Yale University United States Graduate Program in Applied Mathematics and Computational Science University of Pennsylvania United States Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania United States Department of Electrical and Systems Engineering University of Pennsylvania United States

Operator learning, which aims to approximate maps between infinite-dimensional function spaces, is an important area in scientific machine learning with applications across various physical domains. Here we introduce the Continuous Vision Transformer (CViT), a novel neural operator architecture that leverages advances in computer vision to address challenges in learning complex physical systems. CViT combines a vision transformer encoder, a novel grid-based coordinate embedding, and a query-wise cross-attention mechanism to effectively capture multi-scale dependencies. This design allows for flexible output representations and consistent evaluation at arbitrary resolutions. We demonstrate CViT’s effectiveness across a diverse range of partial differential equation (PDE) systems, including fluid dynamics, climate modeling, and reaction-diffusion processes. Our comprehensive experiments show that CViT achieves state-of-the-art performance on multiple benchmarks, often surpassing larger foundation models, even without extensive pretraining and roll-out fine-tuning. Taken together, CViT exhibits robust handling of discontinuous solutions, multi-scale features, and intricate spatio-temporal dynamics. Our contributions can be viewed as a significant step towards adapting advanced computer vision architectures for building more flexible and accurate machine learning models in the physical sciences. All data and code are publicly available at https://***/PredictiveIntelligenceLab/cvit. © 2024, CC BY-NC-SA.

关键词： Computer vision

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Melting/solidification of phase change material in a multi-tube heat exchanger in the presence of metal foam:effect of the geometrical configuration of tubes

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Energy Storage and Saving 2022年第4期1卷 241-258页

作者： Atef Chibani Aissa Dehane Slimane Merouani Cherif Bougriou Djemaa Guerraiche Laboratory of Environmental Process Engineering Department of Chemical EngineeringFaculty of Process EngineeringUniversity Salah Boubnider Constantine 3Constantine25000Algeria Department of Mechanical Engineering Faculty of TechnologyUniversity of Mostefa Ben BoulaidBatna 2Batna05000Algeria Faculty of Sciences and Applied Sciences Department of Process EngineeringLarbi Ben M’hidi UniversityOum El Bouaghi04000Algeria Applied Energy Physics Laboratory(LPEA) Physical DepartmentFaculty of Matter SciencesUniversity of Batna 1Batna05000Algeria

One of the likely methods for enhancing heat transfer in a latent thermal energy storage system is the conception of a thermal *** this study,the orientation of oval tubes(horizontal,vertical,and oblique)in phase change material(PCM,C_(19)-C_(20))-based shell-tube heat exchanger was analyzed with respect to the metal foam(MF)type(graphite,copper,and nickel)in comparison to the case of pure *** this purpose,a two-dimensional mathematical model was developed to investigate the thermal efficiency of the PCM-metal foam based composite energy storage *** was concluded that the orientation of the oval tubes(oblique,horizontal,and vertical)has a negligible impact on the performance of the thermal unit during the melting/solidification *** on the liquid/solid fraction,total enthalpy and the average temperature in the annular space,the performance of a heat exchanger during fusion/solidification periods is in the order:copper-MF>graphite-MF>nickel-MF>pure *** the adopted MF or the geometry of tubes,the melting process is expedited compared to the solidification mechanism.

关键词： Phase change material(PCM) Solidification process Melting process PCM-metal foam Heat exchanger

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Direct numerical simulations of turbulent jets: vortex-interface-surfactant interactions

Direct numerical simulations of turbulent jets: vortex-inter...

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2023 AIChE Annual Meeting

作者： Constante-Amores, R. Abadie, T. Kahouadji, L. Shin, S. Chergui, J. Juric, D. Castrejon-Pita, A.A. Matar, O.K. Department of Chemical Engineering Imperial College London LondonSW7 2AZ United Kingdom Department of Engineering Science University of Oxford OxfordOX1 3PJ United Kingdom Department of Mechanical and System Design Engineering Hongik University Korea Republic of Orsay91400 France Department of Applied Mathematics and Theoretical Physics University of Cambridge CambridgeCB3 0WA United Kingdom

We study the effect of insoluble surfactants on the spatio-temporal evolution of turbulent jets. We use three-dimensional numerical simulations and employ an interface-tracking/level-set method that accounts for surfactant-induced Marangoni stresses. The present study builds on our previous work (Constante-Amores et al., 2021, J. Fluid Mech., 922, A6) in which we examined in detail the vortex-surface interaction in the absence of surfactants. Numerical solutions are obtained for a wide range of Weber and elasticity numbers in which vorticity production is generated by surface deformation and surfactant-induced Marangoni stresses. The present work demonstrates, for the first time, the crucial role of Marangoni stresses, brought about by surfactant concentration gradients, in the formation of coherent, hairpin-like vortex structures. These structures have a profound influence on the development of the three-dimensional interfacial dynamics. We also present theoretical expressions for the mechanisms that influence the rate of production of circulation in the presence of surfactants for a general, three-dimensional, two-phase flow and highlight the dominant contribution surfactant-induced Marangoni stresses. © 2023 American Institute of Chemical Engineers. All rights reserved.

关键词： Surface active agents

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Viscoelastic fluid flow in a slowly varying planar contraction: the role of finite extensibility on the pressure drop

arXiv

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arXiv 2024年

作者： Mahapatra, Bimalendu Ruangkriengsin, Tachin Stone, Howard A. Boyko, Evgeniy Faculty of Mechanical Engineering Technion – Israel Institute of Technology Haifa3200003 Israel Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Department of Mechanical and Aerospace Engineering Princeton University PrincetonNJ08544 United States

We analyze the steady viscoelastic fluid flow in slowly varying contracting channels of arbitrary shape and present a theory based on the lubrication approximation for calculating the flow rate–pressure drop relation at low and high Deborah (De) numbers. Unlike most prior theoretical studies leveraging the Oldroyd-B model, we describe the fluid viscoelasticity using a FENE-CR model and examine how the polymer chains’ finite extensibility impacts the pressure drop. We employ the low-Deborah-number lubrication analysis to provide analytical expressions for the pressure drop up to O(De4). We further consider the ultra-dilute limit and exploit a one-way coupling between the parabolic velocity and elastic stresses to calculate the pressure drop of the FENE-CR fluid for arbitrary values of the Deborah number. Such an approach allows us to elucidate elastic stress contributions governing the pressure drop variations and the effect of finite extensibility for all De. We validate our theoretical predictions with two-dimensional numerical simulations and find excellent agreement. We show that, at low Deborah numbers, the pressure drop of the FENE-CR fluid monotonically decreases with De, similar to the previous results for the Oldroyd-B and FENE-P fluids. However, at high Deborah numbers, in contrast to a linear decrease for the Oldroyd-B fluid, the pressure drop of the FENE-CR fluid exhibits a non-monotonic variation due to finite extensibility, first decreasing and then increasing with de. Nevertheless, even at sufficiently high Deborah numbers, the pressure drop of the FENE-CR fluid in the ultra-dilute and lubrication limits is lower than the corresponding Newtonian pressure drop. © 2024, CC BY.

关键词： Non Newtonian flow

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Maximizing the Thermal Performance of Microheaters for Non-Volatile Phase Change Photonics: A Comparative Study of Pulse Width Parameter Effects 23

Maximizing the Thermal Performance of Microheaters for Non-V...

引用

23rd IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2024

作者： F., Vasquez-Aza H., Sun C., Lian Y.-S., Huang S.A., Vitale I., Takeuchi J., Hu N., Youngblood C.A.R., Ocampo G., Pavlidis University of Connecticut School of Mechanical Aerospace and Manufacturing Engineering StorrsCT06269 United States University of Maryland Department of Materials Science and Engineering College ParkMD20742 United States University of Maryland Institute for Research in Electronics and Applied Physics College ParkMD20742 United States Mit Lincoln Laboratory Advanced Materials and Microsystems Group LexingtonMA02139 United States University of Maryland Quantum Materials Center Department of Physics College ParkMD20742 United States Massachusetts Institute of Technology Department of Materials & Science Engineering CambridgeMA02139 United States The University of Pittsburgh Electrical & Computer Engineering Department PittsburghPA15213 United States

ISBN: (数字)9798350364330

ISBN: (纸本)9798350364330

Guiding, manipulating, and detecting light is integral to modern photonic systems that can be designed for displays, memory, data transfer, and sensors. The prospect of realizing programmable yet zero-static power photonics has recently gained attention thanks to the rise of optical phase change materials (PCMs). PCMs have a unique set of properties that make them desirable for this task: nonvolatile retention and reversible switching between their amorphous and crystalline states, which, in addition, display distinct optical and electronic properties. Nonvolatile photonic devices have primarily relied on either electrical or optical switching of PCMs. Electrical switching offers effortless CMOS integration;however, it is predominantly limited to binary output. In contrast, optical switching enables accurate multilevel control but is limited in scalability. This paper studies an alternative electro-thermal approach to nonvolatile photonics by controlling the PCM phase via doped silicon microheaters. The results highlight the significance of precise spatial and temporal temperature control to ensure optimal modulation of the PCM. Specifically, this paper investigates the impact of the electric pulse width (0.2 μs to 10 μs) on the maximum temperature for two different microheater designs. High resolution (≈410 nm) transient thermoreflectance imaging (TTI) is used to measure and analyze the surface temperature distribution across each microheater under pulsed biasing. To assess the impact of varying pulse widths, this study systematically examines their effects on maximum temperature, response time, and maximum power. Shorter pulse widths ( 1 μs) provide greater thermal stability but exhibit reduced maximum temperatures due to limited current levels. The experimental results demonstrate a nonlinear relationship between the peak temperature and the power supplied at sub-steady state thermalization time scales. For the specific microheater geometry, the optimal pulse wid

关键词： Photonic integration technology

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Advances in powder nano-photocatalysts as pollutant removal and as emerging contaminants in water:Analysis of pros and cons on health and environment

Advanced Powder Materials

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Advanced Powder Materials 2024年第6期3卷 33-69页

作者： Sahil Thakur Abhijeet Ojha Sushil Kumar Kansal Navneet Kumar Gupta Hendrik C.Swart Junghyun Cho Andrej Kuznetsov Shuhui Sun Jai Prakash Department of Chemistry National Institute of Technology HamirpurHamirpur(H.P.)177005India Department of Materials Science and Engineering National Institute of Technology HamirpurHamirpur(H.P.)177005India Dr.S.S.Bhatnagar University Institute of Chemical Engineering and Technology Panjab UniversityChandigarh 160014India Center for Sustainable Technologies Indian Institute of Science(IISc)Gulmohar MargMathikereBengaluru 560012India Department of Physics University of the Free State(UFS)BloemfonteinZA 9300South Africa Department of Mechanical Engineering&Materials Science and Engineering Program State University of New York(SUNY)BinghamtonNY 13902-6000USA University of Oslo Department of Physics and Centre for Materials Science and NanotechnologyPO Box 1048 BlindernN-0316OsloNorway Institut National de la Recherche Scientifique(INRS)-CentreEnergie Materiaux et Telecommunications VarennesQuebec J3X 1P7Canada

Photocatalysis is an advanced oxidation process where light exposure triggers a semiconducting nanomaterial(nano-photocatalyst)to generate electron-hole(e^(-)/h^(+))pairs and free *** phenomenon is widely used for the photocatalysis-assisted removal of organic and other contaminants using wide range of nanophotocatalysts,offering an efficient approach to environmental ***,the introduction of powdered nano-photocatalysts into water systems often leads to unintended secondary pollution in the form of residual nano-photocatalysts,ion leaching,free radicals,toxic by-products *** practices potentially introduce emerging secondary contaminants into aquatic environments,posing risks to both aquatic life and human *** resulting chemical by-products and intermediates can effectively induce chronic toxicity,neurological and developmental disorders,cardiovascular defects,and intestinal ailments in humans and aquatic *** having a range of health and environmental consequences,this dark side of nano-photocatalysts has been comparatively less explored and discussed in the *** this review,the pros and cons of powder nanophotocatalysts are discussed in view of their advantages as well as disadvantages in wastewater *** discussion encompasses their classification based on composition,dimensions,structure,and activity,as well as recent advancements in improving their photocatalytic *** article also explores the recent advances on their applications in photocatalytic removal of various water pollutants/contaminants of emerging concern(i.e.,organic pollutants,micro/nano plastics,heavy ions,disinfections,etc.)Furthermore,an emphasis on the role of such nano-photocatalysts as emerging(secondary)contaminants in water system,along with a thorough discussion of latest studies related to the health and environmental issues,has been ***,it addresses critical issues in applying powder nano-photo

关键词： Powder nano-photocatalysts Advanced oxidation processes Wastewater treatment Pros and cons Emerging contaminants Health and environment issues

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Light-driven single-cell rotational adhesion frequency assay

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eLight 2022年第1期2卷 154-164页

作者： Yaoran Liu Hongru Ding Jingang Li Xin Lou Mingcheng Yang Yuebing Zheng Department of Electrical and Computer Engineering The University of Texas at AustinAustinTX 78712USA Walker Department of Mechanical Engineering The University of Texas at AustinAustinTX 78712USA Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX 78712USA School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory Dongguan 523808GuangdongChina Department of Biomedical Engineering The University of Texas at AustinAustinTX 78712USA

The interaction between cell surface receptors and extracellular ligands is highly related to many physiological processes in living *** techniques have been developed to measure the ligand-receptor binding kinetics at the single-cell ***,few techniques can measure the physiologically relevant shear binding affinity over a single cell in the clinical ***,we develop a new optical technique,termed single-cell rotational adhesion frequency assay(scRAFA),that mimics in vivo cell adhesion to achieve label-free determination of both homogeneous and heterogeneous binding kinetics of targeted cells at the subcellular ***,the scRAFA is also applicable to analyze the binding affinities on a single cell in native human *** its superior performance and general applicability,scRAFA is expected to find applications in study of the spatial organization of cell surface receptors and diagnosis of infectious diseases.

关键词： diagnosis kinetics rotational

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The effect of deposition rate and temperature on the structure and ferroelectric properties of pulsed laser deposited Bi0.95Dy0.05FeO3 thin films

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Surface and Coatings Technology 2024年 479卷

作者： Lin, Ting-Kai Wu, Cheng-En Chang, Huang-Wei Wang, Chang-Ren Wei, Da-Hua Tu, Chi-Shun Chen, P.Y. Institute of Manufacturing Technology and Department of Mechanical Engineering National Taipei University of Technology Taipei10608 Taiwan Department of Applied Physics Tunghai University Taichung407 Taiwan Department of Physics National Chung Cheng University Chia-Yi621 Taiwan Department of Physics Fu Jen Catholic University Taipei24205 Taiwan Department of Mechanical Engineering Ming Chi University of Technology New Taipei City24301 Taiwan

In this study, the structural and ferroelectric properties of Bi0.95Dy0.05FeO3 (BDFO) thin films prepared using pulsed laser deposition (PLD) under various deposition rates (Dr) and substrate temperatures (Ts) are investigated. Regardless of Dr in the range of 1.0–3.0 Å/s, a predominant crystallographic orientation, BDFO(001), and similar microstructure are consistently identified for BDFO films at Ts = 500 °C. Stress analysis revealed the distinct stress states with Dr. Ferroelectric properties might depend on stress in this case. The compressive stress found for the film at Dr = 3.0 Å/s results in enhanced polarization, with a 2Pr of 180 μC/cm2. In contrast, tensile stress for the film at Dr = 1.0 Å/s exhibits a lower 2Pr = 106 μC/cm2. Besides, XRD results for the films at different Ts demonstrated that the optimal temperature for BDFO growth is Ts = 500 °C, which exhibits the lowest leakage current density due to the suppressed vacancies and improved crystallinity. These findings provide comprehensive insights into the structural and ferroelectric properties of BDFO films, elucidating the impact of deposition rate on their characteristics, and significantly improving ferroelectric properties of BDFO films for the applications. © 2024 Elsevier B.V.

关键词： Deposition rates

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Sensing Beyond the Exceptional Point for High Detectivity

Sensing Beyond the Exceptional Point for High Detectivity

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Conference on Lasers and Electro-Optics (CLEO)

作者： Zhichao Li Ciril S. Prasad Xielin Wang Ding Zhang Gururaj V. Naik Applied Physics Graduate Program Smalley-Curl Institute Rice University Houston TX USA Department of Electrical and Computer Engineering Rice University Houston TX USA Department of Physics and Astronomy Rice University Houston TX USA

Exceptional point (EP)-based optical sensors exhibit exceptional sensitivity but poor detectivity. Slightly off EP operation boosts detectivity without much loss in sensitivity. We experimentally demonstrate a high-de... 详细信息

ISBN: (纸本)9798350369311

关键词： Proteins Optical losses Sensitivity Optical device fabrication Measurement by laser beam Lasers and electrooptics Optical sensors Laser applications Electro-optical waveguides

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