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arXiv 2022年

作者： Sánchez, Hugo A. Castillo Jovanović, Mihailo R. Kumar, Satish Morozov, Alexander Shankar, V. Subramanian, Ganesh Wilson, Helen J. Department Of Applied Mathematics And Statistics Institute Of Mathematics And Computational Sciences University Of Sao Paulo Brazil Ming Hsieh Department Of Electrical And Computer Engineering University Of Southern California Los AngelesCA90089 United States Department Of Chemical Engineering And Materials Science University Of Minnesota MinneapolisMN55455 United States SUPA School Of Physics And Astronomy The University Of Edinburgh EdinburghEH9 3FD United Kingdom Department Of Chemical Engineering Indian Institute Of Technology Kanpur208016 India Engineering Mechanics Unit Jawaharlal Nehru Center For Advanced Scientific Research Bangalore560064 India Mathematics Department University College London Gower Street LondonWC1E 6BT United Kingdom

The Oldroyd-B model has been used extensively to predict a host of instabilities in shearing flows of viscoelastic fluids, often realized experimentally using polymer solutions. The present review, written on the occasion of the birth centenary of James Oldroyd, provides an overview of instabilities found across major classes of shearing flows. These comprise (i) the canonical rectilinear shearing flows including plane Couette, plane and pipe Poiseuille flows;(ii) viscometric shearing flows with curved streamlines such as those in the TaylorCouette, cone-and-plate and parallel-plate geometries;(iii) non-viscometric shearing flows with an underlying extensional flow topology such as the flow in a cross-slot device;and (iv) multilayer shearing flows. While the underlying focus in all these cases is on results obtained using the Oldroyd-B model, we also discuss their relation to the actual instability, and as to how the shortcomings of the Oldroyd-B model may be overcome by the use of more realistic constitutive models. All the three commonly used tools of stability analysis, viz., modal linear stability, nonmodal stability, and weakly nonlinear stability analyses are discussed, with supporting evidence from experiments and numerical simulations as appropriate. Despite only accounting for a shear-rate-independent viscosity and first normal stress coefficient, the Oldroyd-B model is able to qualitatively predict the majority of instabilities in the aforementioned shearing flows. The review also highlights, where appropriate, open questions in the area of viscoelastic stability. © 2022, CC BY.

关键词： Stability

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Adaptively detect and accurately resolve macro-scale shocks in an efficient Equation-Free multiscale simulation

arXiv

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arXiv 2021年

作者： Maclean, John Bunder, J.E. Kevrekidis, I.G. Roberts, A.J. School of Mathematical Sciences University of Adelaide SA Australia Department of Chemical and Biomolecular Engineering and Applied Mathematics and Statistics Johns Hopkins University BaltimoreMD United States

The Equation-Free approach to efficient multiscale numerical computation marries trusted micro-scale simulations to a framework for numerical macro-scale reduction-the patch dynamics scheme. A recent novel patch scheme empowered the Equation-Free approach to simulate systems containing shocks on the macro-scale. However, the scheme did not predict the formation of shocks accurately, and it could not simulate moving shocks. This article resolves both issues, as a first step in one spatial dimension, by embedding the Equation-Free, shock-resolving patch scheme within a classic framework for adaptive moving meshes. Our canonical micro-scale problems exhibit heterogeneous nonlinear advection and heterogeneous diffusion. We demonstrate many remarkable benefits from the moving patch scheme, including efficient and accurate macro-scale prediction despite the unknown macro-scale closure. Equation-free methods are here extended to simulate moving, forming and merging shocks without a priori knowledge of the existence or closure of the shocks. Whereas adaptive moving mesh equations are typically stiff, typically requiring small time-steps on the macro-scale, the moving macro-scale mesh of patches is typically not stiff given the context of the micro-scale time-steps required for the sub-patch dynamics. Copyright © 2021, The Authors. All rights reserved.

关键词： Mesh generation

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RANDONET: SHALLOW-NETWORKS WITH RANDOM PROJECTIONS FOR LEARNING LINEAR AND NONLINEAR OPERATORS

arXiv

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arXiv 2024年

作者： Fabiani, Gianluca Kevrekidis, Ioannis G. Siettos, Constantinos Yannacopoulos, Athanasios N. Scuola Superiore Meridionale Naples80138 Italy Department of Chemical and Biomolecular Engineering Johns Hopkins University BaltimoreMD21210 United States Dipartimento di Matematica e Applicazioni "Renato Caccioppoli" Università degli Studi di Napoli Federico II Naples80126 Italy Department of Statistics Athens University of Economics and Business Athens Greece Department of Applied Mathematics and Statistics Johns Hopkins University BaltimoreMD21210 United States Medical School Department of Urology Johns Hopkins University BaltimoreMD21210 United States

Deep Operator Networks (DeepOnets) have revolutionized the domain of scientific machine learning for the solution of the inverse problem for dynamical systems. However, their implementation necessitates optimizing a high-dimensional space of parameters and hyperparameters. This fact, along with the requirement of substantial computational resources, poses a barrier to achieving high numerical accuracy. Here, inpsired by DeepONets and to address the above challenges, we present Random Projection-based Operator Networks (RandONets): shallow networks with random projections that learn linear and nonlinear operators. The implementation of RandONets involves: (a) incorporating random bases, thus enabling the use of shallow neural networks with a single hidden layer, where the only unknowns are the output weights of the network’s weighted inner product;this reduces dramatically the dimensionality of the parameter space;and, based on this, (b) using established least-squares solvers (e.g., Tikhonov regularization and preconditioned QR decomposition) that offer superior numerical approximation properties compared to other optimization techniques used in deep-learning. In this work, we prove the universal approximation accuracy of RandONets for approximating nonlinear operators and demonstrate their efficiency in approximating linear nonlinear evolution operators (right-hand-sides (RHS)) with a focus on PDEs. We show, that for this particular task, RandONets outperform, both in terms of numerical approximation accuracy and computational cost, the "vanilla" *** Codes 65M32, 65D12, 65J22, 41A35, 68T20, 65D15, 68T07, 68W20, 41A35 Copyright © 2024, The Authors. All rights reserved.

关键词： Differential equations

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Metal ratio and bimetal nanoarchitectonics of ammonia-based fluoride complex induced nickel hydroxide and manganese oxide composites as active materials of an energy storage device

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Journal of Energy Storage 2024年 80卷

作者： Hsu, Chuan-Chih Yu, You Zher Wu, Chung-Hsien Lee, Pin-Yan Chen, Hung-Ming Husain, Sadang Kongvarhodom, Chutima Hsiao, Yu-Cheng Lin, Lu-Yin Division of Cardiovascular Surgery Department of Surgery School of Medicine College of Medicine Taipei Medical University Taiwan Division of Cardiovascular Surgery Department of Surgery Taipei Medical University Hospital Taiwan Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei Taiwan Gingen Technology Co. LTD. Rm. 7 10F. No.189 Sec. 2 Keelung Rd. Xinyi Dist. Taipei11054 Taiwan Department of Physics Faculty of Mathematics and Natural Science Lambung Mangkurat University Banjarmasin70124 Indonesia Department of Chemical Engineering King Mongkut's University of Technology Thonburi 126 Pracha-u-thit Toong-kru Bangkok10140 Thailand Department of Chemical Engineering Ming Chi University of Technology New Taipei City24301 Taiwan Cell Physiology and Molecular Image Research Center Wan Fang Hospital Taipei Medical University Taipei11696 Taiwan International PhD Program in Biomedical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Stanford Byers Center for Biodesign Stanford University CA94305-5428 United States Graduate Institute of Biomedical Optomechatronics College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan

Nickel and manganese compounds are widely applied as efficient battery-type active materials for energy storage devices, due to high theoretical capacities and abundant redox states for generating redox reactions to store charges. Morphology plays significant roles on energy storage ability. Structure directing agent (SDA) is widely reported to have ability for modulating configurations of active materials and to achieve excellent surface properties. In this work, it is the first time to use NH4BF4 and NH4HF2 as structure directing agents for synthesizing nickel manganese compounds derived from ZIF67 as active materials of energy storage devices. Bimetallic compounds are composed of nickel hydroxide and manganese oxide, which presents the favorable two-dimensional flower-like structure with high surface area and abundant redox states. The largest specific capacitance (CF) of 1358.2 F/g corresponding to the capacity of 226.4 mAh/g are achieved for the bimetallic compound synthesized using the Ni to Mn precursor ratio of 1 to 1 (NiMn11). The energy storage device assembled using NiMn11 and reduced graphene oxide on Ni foams presents a maximum energy density of 11.45 Wh/kg at the power density of 0.35 kW/kg, and excellent long-term stability with the CF retention of 85.6% and Coulombic efficiency of 87.5% after 10,000 cycles. © 2023

关键词： Fluorine compounds

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Investigation of different membrane porosities on the permeate flux of direct contact membrane distillation 6th

Investigation of different membrane porosities on the permea...

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6th International Conference on Composite Materials and Material engineering, ICCMME 2021

作者： Elrasheedy, Asmaa Rabie, Mohammed Elshazly, Ahmed Bassyouni, Mohamed El-Moneim, Ahmed Abd Kady, Marwa El Alexandria21934 Egypt Department of Chemical Engineering Faculty of Engineering Port Said University Port Said42526 Egypt Mechanical Power Engineering Department Mansoura University El-Mansoura35516 Egypt Chemical Engineering Department Faculty of Engineering Alexandria University Alexandria21544 Egypt Materials Science Program Zewail University of Science and Technology City of Science and Technology October Gardens 6th of October Giza12578 Egypt Materials Science and Engineering Department Egypt-Japan University of Science and Technology NewBorg El-Arab Alexandria21934 Egypt Institute of Basic and Applied Sciences Egypt-Japan University of Science and Technology New Borg El-Arab Alexandria21934 Egypt Borg El-Arab City Alexandria21934 Egypt

ISBN: (纸本)9783035718195

In the present study the surface morphology of electrospun fibers at different polystyrene (PS) solution concentration was studied by SEM imaging to determine the best PS solution concentration yielding continuous uniform beadles fibers. Contact angle measurements of the optimum fabricated PS-18 membrane confirmed the super hydrophobic property of the membrane that exhibited a static water contact angle of 145o . Numerical investigation of the performance of PS-18 membrane at different membrane thicknesses and porosities on direct contact membrane distillation showed that increasing the membrane porosity increases the permeate flux considerably. © 2021 Trans Tech Publications Ltd, Switzerland.

关键词： Polystyrenes

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Quantum Logic Enhanced Sensing in Solid-State Spin Ensembles

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Physical Review Letters 2023年第10期131卷 100801-100801页

作者： Nithya Arunkumar Kevin S. Olsson Jner Tzern Oon Connor A. Hart Dominik B. Bucher David R. Glenn Mikhail D. Lukin Hongkun Park Donhee Ham Ronald L. Walsworth Department of Physics Harvard University Cambridge Massachusetts 02138 USA John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA Quantum Technology Center University of Maryland College Park Maryland 20742 USA Department of Electrical and Computer Engineering University of Maryland College Park Maryland 20742 USA Intelligence Community Postdoctoral Research Fellowship Program University of Maryland College Park Maryland 20742 USA Department of Physics University of Maryland College Park Maryland 20742 USA Department of Chemistry Technical University of Munich Lichtenbergstraße 4 85748 Garching Germany Department of Chemistry and Chemical Biology Harvard University Cambridge Massachusetts 02138 USA

We demonstrate quantum logic enhanced sensitivity for a macroscopic ensemble of solid-state, hybrid two-qubit sensors. We achieve over a factor of 30 improvement in the single-shot signal-to-noise ratio, translating to an ac magnetic field sensitivity enhancement exceeding an order of magnitude for time-averaged measurements. Using the electronic spins of nitrogen vacancy (NV) centers in diamond as sensors, we leverage the on-site nitrogen nuclear spins of the NV centers as memory qubits, in combination with homogeneous and stable bias and control fields, ensuring that all of the ∼109 two-qubit sensors are sufficiently identical to permit global control of the NV ensemble spin states. We find quantum logic sensitivity enhancement for multiple measurement protocols with varying optimal sensing intervals, including XY8 and DROID-60 dynamical decoupling, as well as correlation spectroscopy, using an applied ac magnetic field signal. The results are independent of the nature of the target signal and broadly applicable to measurements using NV centers and other solid-state spin ensembles. This work provides a benchmark for macroscopic ensembles of quantum sensors that employ quantum logic or quantum error correction algorithms for enhanced sensitivity.

关键词： NV centers Nuclear & electron resonance Quantum memories Quantum metrology Quantum sensing

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Study of Duck Feather Modification using NaOH to Removal Iron in Acid Mine Drainage (AMD 5

Study of Duck Feather Modification using NaOH to Removal Iro...

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5th International Conference on Energy, Environmental and Information System, ICENIS 2020

作者： Baroroh Lili Utami, Umi Heru, Susanto Cahyono, Bambang Doctor of Scientific Environmental Science Program Diponegoro University Semarang Indonesia Department of Chemical Faculty of Engineering Diponegoro University Semarang Indonesia Department of Chemistry Faculty of Science and Mathematics Diponegoro University Semarang Indonesia

Study of duck feather modification using NaOH to removal iron in acid mine drainage (AMD) has been done. The objective of this study was to determine adsorption capacity. Modification duck feather that 2 g of duck powder was dissolved in 25 mL NaOH with a concentration of 1.00;1.25;1.50;1.75;2.00;and 2.25 % (v/v), then placed on hotplate stirrer at 50°C and stirred for 24 hours. The results showed that adsorption capacity of Fe by adsorbent of duck feather modification using NaOH optimum at concentration 1.50% and adsorption capacity before and after activation were 36.231 mg/g and 68.493 mg/g and potential to be used as an adsorbent to removal of Fe in acid mine drainage at coal mining. © The Authors, published by EDP Sciences, 2020.

关键词： Sodium hydroxide

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Investigating the Biomechanics of Red Blood Cells Through Deformable Interendothelial Slits Model in the Spleen

SSRN

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SSRN 2024年

作者： Li, Guansheng Li, He Ndou, Papa Alioune Franco, Mélanie Li, Xuejin MacDonald, Ian Dao, Ming Buffet, Pierre A. Karniadakis, George Em Division of Applied Mathematics Brown University ProvidenceRI02906 United States School of Chemical Materials and Biomedical Engineering University of Georgia AthensGA30602 United States Université Paris Cité Université des Antilles Inserm Paris75015 France Laboratoire d′Excellence du Globule Rouge Paris75015 France Department of Engineering Mechanics Center for X-Mechanics Zhejiang University Zhejiang Hangzhou310027 China Department of Medical Biophysics Schulich School of Medicine and Dentistry Western University LondonON Canada Department of Materials Science and Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

The spleen constantly clears altered red blood cells (RBCs) from the circulation, tuning the balance between RBC formation (erythropoiesis) and removal. The retention and elimination of RBCs occur predominantly in the open circulation of the spleen, where RBCs must cross submicron-wide inter-endothelial slits (IES). Several experimental and computational studies have illustrated the role of IES in filtrating the biomechanically and morphologically altered RBCs based on a rigid wall assumption. However, these studies also reported that when the size of IES is close to the lower end of clinically observed sizes (less than 0.5 µm), an unphysiologically large pressure difference across the IES is required to drive the passage of normal RBCs, sparking debates on the feasibility of the rigid wall assumption. In this work, We propose two deformable IES models, namely the passive model and the active model, aiming to explore the impact of the deformability of IES on the filtration function of the spleen. In the passive model, we implement the worm-like string model to depict the IES’s deformation as it interacts with blood plasma and allows RBC to traverse. In contrast, the active model involved regulating the IES deformation based on the local pressure surrounding the slit. To demonstrate the validity of the deformable model, we simulate the filtration of RBCs with varied size and stiffness by IES under three scenarios: 1) a single RBC traversing a single slit;2) a suspension of RBCs traversing an array of slits, mimicking in vitro spleen-on-a-chip experiments;3) RBC suspension passing through the 3D spleen filtration unit known as ’the splenon’. Our simulation results of RBC passing through a single slit show that the deformable IES model offers more accurate predictions of the critical cell surface area to volume ratio that dictate the removal of aged RBCs from circulation compared to prior rigid-wall models. Our biophysical models of the spleen-on-a-chip indicate a hier

关键词： Blood

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Grapenet_Lv1 for the Prediction of Optimum Hand-Picking Time of Nagano Purple Grapes

SSRN

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SSRN 2025年

作者： Islam, Md. Parvez Shinagawa, K. Hatou, K. Abdurrakhman, Arief Dian, K. Department of Biomechanical Systems Faculty of Agriculture Ehime University 3-5-7 Tarumi Matsuyama790-8566 Japan United Graduate School of Agriculture Ehime University 3-5-7 Tarumi Matsuyama790-8566 Japan Department of Instrumentation Engineering Institut Teknologi Sepuluh Nopember Surabaya60111 Indonesia Business Mathematics Program Study School of Applied STEM Universitas Prasetiya Mulya BSD Campus BSD City Kav. Edutown I.1 Tangerang15339 Indonesia Indonesia

We investigated the optimum hand-picking time of Nagano Purple, a rare Japanese table grape variety. The color sensitivity between pure red–purple–black and pure purple–black makes it difficult for farmers to harvest these fruits at the right time while maintaining high sweetness level. We manually extracted 13 color parameters, namely, X, Y, Z, x, y, L*, a*, b*, L, a, b, C*, and h, from 355 grape skin samples using a colorimeter, which is a time-consuming and expensive process. In addition, we developed a 15-layer shallow long short-term memory (LSTM) and bidirectional long short-term memory (BLSTM) neural network, namely, GrapeNet_Lv1, with a learnable parameter of 1.39E+06. This network is compact and requires low computational cost for training. Furthermore, it has the ability to prevent the problems of vanishing gradient and overfitting. The combination of all the 13 aforementioned parameters yielded promising results in predicting color and sweetness levels, with test accuracies of 0.83 and 0.76, respectively. In the prediction of color level, our proposed network GrapeNet_Lv1 achieves a high validation accuracy of 0.92, F1 score of 0.88, recall of 0.87, low validation loss of 0.39, and RMSE of 0.31. However, in the prediction of sweetness level, GrapeNet_Lv1 achieves a relatively low validation accuracy of 0.79, F1 score of 0.70, recall of 0.69, high validation loss of 0.72, and RMSE of 0.33. Further research can help improve the accuracy. GrapeNet_Lv1 can be applied to other crops, where, predicting the whose optimal hand-picking time is difficult to predict based on color recognition. Keywords: Neural network;LSTM-BLSTM;Nagano Purple, color, sweetness © 2025, The Authors. All rights reserved.

关键词： Long short-term memory

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Computational design of anisotropic stealthy hyperuniform composites with engineered directional scattering properties

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Physical Review E 2023年第4期108卷 045306-045306页

作者： Wenlong Shi David Keeney Duyu Chen Yang Jiao Salvatore Torquato Materials Science and Engineering Arizona State University Tempe Arizona 85287 USA Materials Research Laboratory University of California Santa Barbara California 93106 USA Department of Physics Arizona State University Tempe Arizona 85287 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Department of Physics Princeton University Princeton New Jersey 08544 USA Princeton Institute of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

Disordered hyperuniform materials are an emerging class of exotic amorphous states of matter that endow them with singular physical properties, including large isotropic photonic band gaps, superior resistance to fracture, and nearly optimal electrical and thermal transport properties, to name but a few. Here we generalize the Fourier-space-based numerical construction procedure for designing and generating digital realizations of isotropic disordered hyperuniform two-phase heterogeneous materials (i.e., composites) developed by Chen and Torquato [Acta Mater. 142, 152 (2018)] to anisotropic microstructures with targeted spectral densities. Our generalized construction procedure explicitly incorporates the vector-dependent spectral density function χ̃V(k) of arbitrary form that is realizable. We demonstrate the utility of the procedure by generating a wide spectrum of anisotropic stealthy hyperuniform microstructures with χ̃V(k)=0 for k∈Ω, i.e., complete suppression of scattering in an “exclusion” region Ω around the origin in Fourier space. We show how different exclusion-region shapes with various discrete symmetries, including circular-disk, elliptical-disk, square, rectangular, butterfly-shaped, and lemniscate-shaped regions of varying size, affect the resulting statistically anisotropic microstructures as a function of the phase volume fraction. The latter two cases of Ω lead to directionally hyperuniform composites, which are stealthy hyperuniform only along certain directions and are nonhyperuniform along others. We find that while the circular-disk exclusion regions give rise to isotropic hyperuniform composite microstructures, the directional hyperuniform behaviors imposed by the shape asymmetry (or anisotropy) of certain exclusion regions give rise to distinct anisotropic structures and degree of uniformity in the distribution of the phases on intermediate and large length scales along different directions. Moreover, while the anisotropic exclusion regions

关键词： Amorphous materials Complex materials Simulated annealing

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