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Rigidity percolation in disordered 3D rod systems

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arXiv 2021年

作者： Heroy, Samuel Taylor, Dane Shi, Feng Forest, M. Gregory Mucha, Peter J. The Bartlett Centre for Advanced Spatial Analysis University College London LondonW1 4TJ United Kingdom Mathematical Institute University of Oxford OxfordOX2 6GG United Kingdom Department of Mathematics University at Buffalo State University of New York BuffaloNY14260 United States The Odum Institute for Research in Social Science University of North Carolina Chapel HillNC27599 United States Carolina Center for Interdisciplinary Applied Mathematics Department of Mathematics University of North Carolina Chapel HillNC27599 United States

In composite materials composed of soft polymer matrix and stiff, high-aspect-ratio particles, the composite undergoes a transition in mechanical strength when the inclusion phase surpasses a critical density. This phenomenon (rheological or mechanical percolation) is well-known to occur in many composites at a critical density that exceeds the conductivity percolation threshold. Conductivity percolation occurs as a consequence of contact percolation, which refers to the conducting particles’ formation of a connected component that spans the composite. Rheological percolation, however, has evaded a complete theoretical explanation and predictive description. A natural hypothesis is that rheological percolation arises due to rigidity percolation, whereby a rigid component of inclusions spans the composite. We model composites as random isotropic dispersions of soft-core rods, and study rigidity percolation in such systems. Building on previous results for two-dimensional systems, we develop an approximate algorithm that identifies spanning rigid components through iteratively identifying and compressing provably rigid motifs—equivalently, decomposing giant rigid components into rigid assemblies of successively smaller rigid components. We apply this algorithm to random rod systems to estimate a rigidity percolation threshold and explore its dependence on rod aspect ratio (α). We show that this transition point, like the contact percolation transition point, scales inversely with the average (α-dependent) rod excluded volume. However, the scaling of the rigidity percolation threshold, unlike the contact percolation scaling, is valid for relatively low α. Moreover, the critical rod contact number is constant for α above some relatively low value;and lies below the prediction from Maxwell’s isostatic condition. © 2021, CC BY.

关键词： Solvents

Inferring solar differential rotation through normal-mode coupling using bayesian statistics

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arXiv 2021年

作者： Kashyap, Samarth Ganesh Bharati Das, Srijan Hanasoge, Shravan M. Woodard, Martin F. Tromp, Jeroen Department of Astronomy and Astrophysics Tata Institute of Fundamental Research Mumbai India Department of Geosciences Princeton University PrincetonNJ United States NorthWest Research Associates Boulder Office 3380 Mitchell Lane BoulderCO United States Department of Geosciences and Program in Applied & Computational Mathematics Princeton University PrincetonNJ United States

Normal-mode helioseismic data analysis uses observed solar oscillation spectra to infer perturbations in the solar interior due to global and local-scale flows and structural asphericity. Differential rotation, the dominant global-scale axisymmetric perturbation, has been tightly constrained primarily using measurements of frequency splittings via "a-coefficients". However, the frequency-splitting formalism invokes the approximation that multiplets are isolated. This assumption is inaccurate for modes at high angular degrees. Analysing eigenfunction corrections, which respect cross coupling of modes across multiplets, is a more accurate approach. However, applying standard inversion techniques using these cross-spectral measurements yields a-coefficients with a significantly wider spread than the well-constrained results from frequency splittings. In this study, we apply Bayesian statistics to infer a-coefficients due to differential rotation from cross spectra for both f-modes and p-modes. We demonstrate that this technique works reasonably well for modes with angular degrees ` = 50 − 291. The inferred a3−coefficients are found to be within 1 nHz of the frequency splitting values for ` > 200. We also show that the technique fails at ` © 2021, CC BY.

关键词： Eigenvalues and eigenfunctions

Flow characteristics and noise diagnosis of hydrogen charging solenoid valve in hydrogen- fueled automobile 33

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Flow characteristics and noise diagnosis of hydrogen chargin...

33rd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2020

作者： Ariyadi, Hifni M. Giannetti, Niccolò Jeong, Jongsoo Yamaguchi, Seiichi Saito, Kiyoshi Lee, Changhoon Kim, Jungtae Lee, Seungbeom Lee, Jiyong Jeong, Kwangyeol Department of Applied Mechanics and Aerospace Engineering Waseda University Tokyo Japan Waseda Institute for Advanced Study Waseda University Tokyo Japan Waseda Research Institute for Science and Engineering Waseda University Tokyo Japan Interdisciplinary Institute for Thermal Energy Conversion Engineering and Mathematics Waseda University Tokyo Japan UNICK Corporation Gyeongsangnam Korea Republic of

There is a growing interest in green vehicles, such as hydrogen powered fuel cell cars, along with the increase in public awareness towards the environmental issues. However, with compressed systems applied for fuel storage purpose, refueling of hydrogen causes an issue, during which high-pressure hydrogen from the station storage tank passes through filling components before entering the empty tank in the vehicle. In this state, as the pressure difference between the station tank and the vehicle tank can be very high, the complexity of solenoid valve geometry creates complex flow characteristics (turbulence and interaction of gas and wall) that could generate intense pressure fluctuation and excessive noise. This paper presents the results of a three-dimensional simulation for characterizing the complex flow inside the solenoid valve and for diagnosing flow-induced noise generated during the charging process at different valve openings and pressures. Simulation is carried out using computational fluid dynamics (CFD) by implementing appropriate turbulence and viscous models. Firstly, the simulation is conducted in a steady state condition to investigate the acoustic power and to localize the regions that are most likely to be affected. In addition, transient simulations are performed to obtain the frequency of the pressure fluctuation inside the solenoid valve. The results provide accurate and useful data about flow pattern inside the solenoid valve and additionally, furnish information to determine the sources, locations, and characteristics of flow-induced noise generated within the solenoid valve. This investigation can be applied to reduce the undesirable noise and to analyze the possibility of system failure due to flow-induced vibrations. © ECOS *** right reserved.

关键词： Turbulence

Quality of internal representation shapes learning performance in feedback neural networks

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Physical Review Research 2021年第1期3卷 013176-013176页

作者： Lee Susman Francesca Mastrogiuseppe Naama Brenner Omri Barak Interdisciplinary Program in Applied Mathematics Technion Israel Institute of Technology Haifa 32000 Israel Network Biology Research Laboratories Technion Israel Institute of Technology Haifa 32000 Israel Gatsby Computational Neuroscience Unit University College London London W1T 4JG United Kingdom Department of Chemical Engineering Technion Israel Institute of Technology Haifa 32000 Israel Rappaport Faculty of Medicine Technion Israel Institute of Technology Haifa 32000 Israel

A fundamental feature of complex biological systems is the ability to form feedback interactions with their environment. A prominent model for studying such interactions is reservoir computing, where learning acts on low-dimensional bottlenecks. Despite the simplicity of this learning scheme, the factors contributing to or hindering the success of training in reservoir networks are in general not well understood. In this work, we study nonlinear feedback networks trained to generate a sinusoidal signal, and analyze how learning performance is shaped by the interplay between internal network dynamics and target properties. By performing exact mathematical analysis of linearized networks, we predict that learning performance is maximized when the target is characterized by an optimal, intermediate frequency which monotonically decreases with the strength of the internal reservoir connectivity. At the optimal frequency, the reservoir representation of the target signal is high-dimensional, desynchronized, and thus maximally robust to noise. We show that our predictions successfully capture the qualitative behavior of performance in nonlinear networks. Moreover, we find that the relationship between internal representations and performance can be further exploited in trained nonlinear networks to explain behaviors which do not have a linear counterpart. Our results indicate that a major determinant of learning success is the quality of the internal representation of the target, which in turn is shaped by an interplay between parameters controlling the internal network and those defining the task.

关键词： Learning theory Artificial neural networks Dynamical systems Neuronal network models

Correction to: A dual layer security scheme for medical images using Hessenberg and singular value decompositions

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Multimedia Tools and Applications 2022年第10期81卷 14023-14023页

作者： Elmoasry, Ahmed Khan, Lal Said Khan, Majid Hussain, Iqtadar Department of Mathematics College of Science Al-Zulfi Majmaah University Al-Zulfi Saudi Arabia Department of Avionics Engineering Institute of Space Technology Islamabad Pakistan Department of Applied Mathematics and Statistics Institute of Space Technology Islamabad Pakistan Mathematics Program Department of Mathematics Statistics and Physics College of Arts and Sciences Qatar University Doha Qatar Statistical Consulting Unit College of Arts and Science Qatar University Doha Qatar

Incremental learning and state-space evolving fuzzy control of nonlinear time-varying systems with unknown model

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arXiv 2021年

作者： Leite, Daniel Coutinho, Pedro Bessa, Iury Camargos, Murilo Cordovil Junior, Luiz A.Q. Palhares, Reinaldo Department of Automatics Federal University of Lavras Brazil Graduate Program in Electrical Engineering Federal University of Minas Gerais Brazil Department of Electricity Federal University of Amazonas Brazil School of Applied Mathematics Fundação Getulio Vargas Rio de Janeiro Brazil Department of Electronics Engineering Federal University of Minas Gerais Brazil

We present a method for incremental modeling and time-varying control of unknown nonlinear systems. The method combines elements of evolving intelligence, granular machine learning, and multi-variable control. We propose a State-Space Fuzzy-set-Based evolving Modeling (SS-FBeM) approach. The resulting fuzzy model is structurally and parametrically developed from a data stream with focus on memory and data coverage. The fuzzy controller also evolves, based on the data instances and fuzzy model parameters. Its local gains are redesigned in real-time – whenever the corresponding local fuzzy models change – from the solution of a linear matrix inequality problem derived from a fuzzy Lyapunov function and bounded input conditions. We have shown one-step prediction and asymptotic stabilization of the Henon chaos. © 2021, CC BY-NC-SA.

关键词： Fuzzy control

Bayesian quantum phase estimation with fixed photon states

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arXiv 2023年

作者： Zhou, Boyu Guha, Saikat Gagatsos, Christos N. Department of Physics The University of Arizona 1118 E 4th St TucsonAZ85721 United States Department of Electrical and Computer Engineering University of Maryland 2410 A.V. Williams Building College ParkMD20742 United States Wyant College of Optical Sciences The University of Arizona 1630 E University Blvd TucsonAZ85721 United States Department of Electrical and Computer Engineering The University of Arizona 1230 E Speedway Blvd TucsonAZ85721 United States Program in Applied Mathematics The University of Arizona 617 N. Santa Rita TucsonAZ85721 United States

We consider a two-mode bosonic state with fixed photon number n ∈ N, whose upper and lower modes pick up a phase and − respectively. We compute the optimal Fock coefficients of the input state, such that the mean square error (MSE) for estimating is minimized while the minimum MSE is always attainable by a measurement. Our setting is Bayesian, i.e., we consider to be a random variable that follows a prior probability distribution function (PDF). Initially, we consider the flat prior PDF and we discuss the well-known fact that the MSE is not an informative tool for estimating a phase when the variance of the prior PDF is large. Therefore, we move on to study truncated versions of the flat prior in both single-shot and adaptive approaches. For our adaptive technique we consider n = 1 and truncated prior PDFs. Each subsequent step utilizes as prior PDF the posterior probability of the previous step and at the same time we update the optimal state and optimal measurement. Copyright © 2023, The Authors. All rights reserved.

关键词： Distribution functions

A review of coagulation explaining its definition, mechanism, coagulant types, and optimization models;RSM, and ANN

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Current Research in Green and Sustainable Chemistry 2023年 6卷

作者： El-taweel, Reem M. Mohamed, Nora Alrefaey, Khlood A. Husien, Sh Abdel-Aziz, A.B. Salim, Alyaa I. Mostafa, Nagwan G. Said, Lobna A. Fahim, Irene Samy Radwan, Ahmed G. School of Engineering and Applied Sciences Nile University Giza Egypt Industrial Engineering Program SESC Research Center Nile University Giza Egypt October High Institute for Engineering Technology Giza Egypt Environmental and Sanitary Engineering Division Public Works Department Faculty of Engineering Cairo University Giza Egypt Nanoelectronics Integrated Systems Center (NISC) Nile University Giza Egypt Engineering Mathematics and Physics Dept. Faculty of Engineering Cairo University Giza 12613 Egypt

The textile business is one of the most hazardous industries since it produces several chemicals, such as dyes, which are released into water streams with ef-fluents. For the survival of the planet's life and the advancement of humanity, water is a crucial resource. One of the anthropogenic activities that pollute and consume water is the textile industry. Thus, the purpose of the current effort is to Apply coagulation as a Physico-chemical and biological treatment strat-egy with different techniques and mechanisms to treat the effluent streams of textile industries. The discharge of these effluents has a negative impact on the environment, marine life, and human health. Therefore, the treatment of these effluents before discharging is an important matter to reduce their adverse ef-fect. Many physico-chemical and biological treatment strategies for contaminants removal from polluted wastewater have been proposed. Coagulation is thought to be one of the most promising physico-chemical strategies for removing con-taminants and colouring pollutants from contaminated water. Coagulation is accompanied by a floculation process to aid precipitation, as well as the collection of the created sludge following the treatment phase. Different commercial, and natural coagulants have been applied as a coagulants in the process of coagulation. Additionally, many factors such as;pH, coagulant dose, pollu-tants concentration are optimized to obtain high coagulants removal capacity. This review will discuss the coagulation process, coagulant types and aids in addition to the factors affecting the coagulation process. Additionally, a brief comparison between the coagulation process, and the other processes;princi-ple, advantages, disadvantages, and their efficiency were discussed throgh the review. Furthermore, it discusses the models and optimization techniques used for the coagulation process including response surface methodology (RSM), ar-tificial neural network (ANN), and several

关键词： Coagulants Coagulation Mathematical models optimization Textile Textile effluents

Using Smartphones to Study Vaccination Decisions in the Wild

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arXiv 2024年

作者： Girardini, Nicolò Alessandro Stopczynski, Arkadiusz Baranov, Olga Betsch, Cornelia Brockmann, Dirk Lehmann, Sune Böhm, Robert University of Trento Italy Trento Italy University of Copenhagen Denmark Department of Applied Mathematics and Computer Science Technical University of Denmark Lyngby Denmark Faculty of Psychology University of Vienna Austria Department of Psychology University of Copenhagen Denmark Health Communication Implementation Science Bernhard Nocht Institute for Tropical Medicine Germany Health Communication Institute for Planetary Health Behaviour University of Erfurt Germany Fraunhofer Institute for Translational Medicine and Pharmacology ITMP Immunology Infection and Pandemic Research Munich Germany Partner site Munich Germany Division of Infectious Diseases and Tropical Medicine LMU University Hospital LMU Munich Germany Center Synergy of Systems AND Center for Interdisciplinary Digital Sciences Faculty of Biology AND Faculty of Physics TUD Dresden University of Technology Dresden Germany Independent Researcher

One of the most important tools available to limit the spread and impact of infectious diseases is vaccination. It is therefore important to understand what factors determine people’s vaccination decisions. To this end, previous behavioural research made use of, (i) controlled but often abstract or hypothetical studies (e.g., vignettes) or, (ii) realistic but typically less flexible studies that make it difficult to understand individual decision processes (e.g., clinical trials). Combining the best of these approaches, we propose integrating real-world Bluetooth contacts via smartphones in several rounds of a game scenario, as a novel methodology to study vaccination decisions and disease spread. In our 12-week proof-of-concept study conducted with N = 494 students, we found that participants strongly responded to some of the information provided to them during or after each decision round, particularly those related to their individual health outcomes. In contrast, information related to others’ decisions and outcomes (e.g., the number of vaccinated or infected individuals) appeared to be less important. We discuss the potential of this novel method and point to fruitful areas for future research. Copyright © 2024, The Authors. All rights reserved.

关键词： Smartphones