Article
Physics, Multidisciplinary
Guo-Yang Li, Artur L. Gower, Michel Destrade, Seok-Hyun Yun
Summary: The authors propose an accurate measurement technique for in-plane stress in thin films based on the speed of elastic waves measured through optical coherence tomography. Experimental results demonstrate the high accuracy of this method, which could be useful in various applications such as soft matter devices, biomaterial engineering, and medical diagnosis.
COMMUNICATIONS PHYSICS
(2022)
Article
Mathematics, Interdisciplinary Applications
Salim Lahmiri, Stelios Bekiros
Summary: This study presents an improved CAD system for distinguishing between normal heart sound and murmur based on the nonlinear characteristics of high frequency oscillations. The system decomposes the original signal using DWT and analyzes it using complexity measures such as Hurst exponent, Lempel-Ziv information, and Shannon entropy. These measures are computed from the high frequency oscillations obtained by wavelet transform and employed to train a nonlinear SVM classifier. Tested on a large dataset, the proposed CAD system outperforms existing models and shows promise in clinical settings.
CHAOS SOLITONS & FRACTALS
(2022)
Article
Physics, Fluids & Plasmas
Ziyu Wang, Jung Hee Seo, Rajat Mittal
Summary: This study uses hemoacoustic simulations to characterize the features of murmurs in chronic mitral regurgitation (MR). The study finds that the intensity of the MR murmur is lower at the mitral point on the precordium, and the intensity and break frequency of the murmur are well correlated with the severity of MR.
Article
Mathematics
Hui Li
Summary: This paper studies the motion of a 1-D closed elastic string in a 2-D Stokes flow, introducing tangent angle and stretching functions to describe different deformations. By reformulating the problem into a parabolic system known as the contour dynamic system, the local well-posedness of the free boundary problem in Sobolev space is established under certain assumptions. It is proven that when initial configurations are sufficiently close to equilibrium, solutions can be extended globally and will converge exponentially to equilibrium state.
JOURNAL OF FUNCTIONAL ANALYSIS
(2021)
Article
Physics, Applied
Xuewei Liu, Mingyu Duan, Maolin Liu, Fengxian Xin, Chuanzeng Zhang
Summary: The study introduces an acoustic labyrinthine porous metamaterial designed for subwavelength sound absorption by combining the acoustic properties of porous material matrix and folded slit configuration. The experimental results demonstrate excellent subwavelength low-frequency sound absorption performance of the material at low frequencies.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Yihao Li, Yan Huang, Ni Zhao
Summary: Low-cost and wearable heart sound sensors can facilitate early detection and monitoring of cardiovascular and respiratory diseases. By using a hybrid near-field/far-field electrospinning approach, a new heart sound sensor with high sensitivity and low detection limit is demonstrated. The sensor can be integrated with apparel and capture high-quality heart sound signals to distinguish different cardiovascular diseases.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Georg Watzl, Christian Kerschbaummayr, Martin Schagerl, Thomas Mitter, Bernhard Sonderegger, Clemens Gruensteidl
Summary: In this study, we demonstrate the in situ measurement of zero-group-velocity Lamb waves and thickness-resonances in steel sheet samples using laser-based ultrasound. We show that the ratio of resonance frequencies can be used to determine the temperature dependent Poisson's ratio of the material. Additional resonances in the response spectrum can be used to cross-check the evaluation. By combining this method with additional knowledge on the thickness, longitudinal and transverse sound velocities can also be determined. The results show good qualitative agreement with reference data and the method provides a robust and contact-free determination of Poisson's ratio.
Article
Acoustics
Gen Li, Yan Chen, Weiting Chen, Jinming Liu, Huan He
Summary: This paper proposes a novel configuration called the local resonance Helmholtz (LRH) lattices, designed to suppress both solid-borne and air-borne sound waves simultaneously. Through numerical simulations and experimental verification, the results show the feasibility of the LRH lattices concept, opening up new possibilities for designing advanced materials with sound and vibration attenuation performances.
Article
Mechanics
Guilherme Jorge Vernizzi, Stefano Lenci, Guilherme Rosa Franzini
Summary: This paper investigates the advantages or issues of different reduced-order models (ROMs) for the analysis of elastic cables hanging between supports at different height. The choice of the function to interpolate the top motion effects is of top-most importance, and working with more complex functions instead of simple trigonometric functions leads to a significance enhancement of the computational performance of the simulations.
INTERNATIONAL JOURNAL OF NON-LINEAR MECHANICS
(2022)
Letter
Cardiac & Cardiovascular Systems
Timothy W. Churchill, Shawn X. Li, Lisa Curreri, Emily K. Zern, Emily S. Lau, Elizabeth E. Liu, Robyn Farrell, Mark W. Shoenike, John Sbarbaro, Rajeev Malhotra, Matthew Nayor, Carsten Tschoepe, Rudolf A. de Boer, Gregory D. Lewis, Jennifer E. Ho
Summary: The article includes additional digital content.
Article
Physics, Fluids & Plasmas
Robert Hunt, Ze Zhao, Eli Silver, Jinhui Yan, Yuri Bazilevs, Daniel M. Harris
Summary: We investigated the drag on a centimetric sphere in a uniform flow with a free surface at different submergence depths. Our experiments demonstrated that the drag in the partially immersed state can significantly exceed the drag in a single-phase flow and reaches a peak just before complete immersion. The additional drag in the partially immersed state can be attributed to hydrostatic effects caused by the asymmetric surface height profile induced by the obstacle.
PHYSICAL REVIEW FLUIDS
(2023)
Article
Engineering, Biomedical
Alexander D. Kaiser, Nicole K. Schiavone, Christopher J. Elkins, Doff B. McElhinney, John K. Eaton, Alison L. Marsden
Summary: The immersed boundary (IB) method is used in this study to simulate fluid-structure interaction (FSI) problems around heart valves. Physical experiments and numerical simulations were conducted, and the results showed excellent qualitative and quantitative agreement between the two, providing comparable experimental data for further validation studies of FSI simulations.
ANNALS OF BIOMEDICAL ENGINEERING
(2023)
Article
Physics, Multidisciplinary
Hongbo Liu, Guoliang Dai, Fengxi Zhou, Zhanlin Mu
Summary: This study investigated the reflection and refraction phenomenon of homogeneous plane-P-1-waves at the interface between thermoelastic solid and unsaturated porothermoelastic media. The theoretical expressions of amplitude reflectivity/refractivity and energy ratio for various reflected/refracted waves were derived, and numerical results were used to discuss the relationship with thermophysical parameters such as frequency, incident angle, thermal expansion coefficient, and medium temperature. Overall, the parameters were found to be significantly influenced by the incident angle, with different effects observed for the thermal expansion coefficients of the two mediums. Additionally, changes in frequency and medium temperature only affected certain types of waves.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Acoustics
L. M. B. C. Campos, I. d'Avila
Summary: Acoustic-entropy waves are linear compressive perturbations of a non-uniform flow, satisfying a modified convected wave equation with varying sound speed. Exact solutions for these waves can be obtained using Bessel functions of an exponential variable, with different characteristics observed in various flow scenarios.
JOURNAL OF SOUND AND VIBRATION
(2021)
Article
Mechanics
Zhi-Hua He, Yi-Ze Wang, Yue-Sheng Wang
Summary: In this study, a new type of elastic wave metamaterial consisting of vertical and lateral resonators, as well as orthogonal stiffeners, is proposed. An active feedback control system is applied to extend the tunable scope and change the characteristics of acoustic-structure coupling. The effective mass density under different feedback constants and the sound transmission loss (STL) of the elastic wave metamaterial immersed in different fluid media are discussed. This work offers a feasible method for creating mechanical/acoustic models with multi-functional potentials.
JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME
(2021)
Article
Engineering, Electrical & Electronic
P. Julian, A. G. Andreou, M. Villemur, N. Rodriguez
Summary: This paper proposes a method using the simplicial algorithm to compute digital vector-vector multiplication without multiplications, showing improved error propagation during parameter quantization and more efficient digital implementation in the case of large number of inputs. The method also has the capability to produce multivariable nonlinear processing.
INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Christos Sapsanis, Marios Sophocleous, Andreas G. Andreou, Julius Georgiou
Summary: This tutorial discusses trade-offs in sensor system design, addressing design considerations at different system levels and introducing fundamental concepts and practical considerations for sensor readout systems. The tutorial explores both fundamental trade-offs and practical/technological trade-offs, providing important insights towards the design of sensory systems operating within demanding constraints.
IEEE SENSORS JOURNAL
(2022)
Article
Mechanics
Jung-Hee Seo, Karthik Menon, Rajat Mittal
Summary: This study proposes a method to decompose the loading noise into components related to their generation mechanism and specific vortex structures. The method is applied to sound generation by a circular cylinder and loading noise generation by a pitching airfoil, showing its ability to identify dominant noise generation mechanisms and quantify the effect of vortex structures on noise generation.
Article
Mechanics
Tomas Solano, Chuanxin Ni, Rajat Mittal, Kourosh Shoele
Summary: The effectiveness of face masks depends on both the material and the fit on faces. A new model for masks is presented to study the leakage pattern on realistic faces. Higher porosity reduces leakage.
Article
Mechanics
J. H. Lee, S. Kuhar, J. -H. Seo, P. J. Pasricha, R. Mittal
Summary: This study explores the impact of body posture and stomach motility on drug bioavailability using a biomimetic in silico simulator. The simulations demonstrate that changes in posture significantly affect the emptying rate of the drug into the duodenum, while gastroparesis reduces the dissolution and emptying of the drug. Neuropathic gastroparesis has a greater impact on gastric emptying compared to myopathic gastroparesis.
Article
Physics, Fluids & Plasmas
Wen Wu, Charles Meneveau, Rajat Mittal, Alberto Padovan, Clarence W. Rowley, Louis Cattafesta
Summary: The response of a turbulent separation bubble to zero-net-mass-flux actuation is investigated via direct numerical simulations. The results demonstrate that the length of the separation bubble can be reduced by forming vortex pairs at the appropriate excitation frequencies. In addition, the time-averaged structures exhibit a high sensitivity to the actuation.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Physics, Fluids & Plasmas
Mostafa Aghaei-Jouybari, Jung -Hee Seo, Junlin Yuan, Rajat Mittal, Charles Meneveau
Summary: The force partitioning method is used to analyze the pressure-induced drag for turbulent flow over rough walls. The study quantifies the contributions of rotation-dominated vortical regions and strain-dominated regions to the pressure drag, and investigates the effects of surface geometry on drag. The results suggest that the phi field, which encodes surface geometry, can be used to parametrize the surface drag.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Engineering, Multidisciplinary
Jung-Hee Seo, Rajat Mittal
Summary: This study reveals the mechanism of how a trailing swimmer can improve its swimming performance by utilizing the wake-induced flow of the leading fish. The results show that this mechanism can significantly enhance the thrust and efficiency of the trailing fish. The findings not only contribute to the understanding of fish-fish hydrodynamic interactions but also have potential applications in designing bioinspired propulsion systems.
BIOINSPIRATION & BIOMIMETICS
(2022)
Article
Mechanics
Sharun Kuhar, Jae Ho Lee, Jung-Hee Seo, Pankaj J. Pasricha, Rajat Mittal
Summary: This study simulates the mixing, breakdown, and emptying process of a liquid meal containing protein in a model of a human stomach, and quantifies the effect of stomach motility on the rate of food breakdown.
Article
Physics, Fluids & Plasmas
Karthik Menon, Sushrut Kumar, Rajat Mittal
Summary: This study reports on the mechanisms of vortex-induced lift production in low Reynolds number flows over low aspect-ratio rectangular wings. By using a force-partitioning method, the pressure-induced aerodynamic loads due to distinct flow features or vortex structures around the wing can be estimated. The study shows that cross-span-oriented vortices contribute more to the total lift than spanwise-oriented vortices, and spanwise vortices in the near wake can produce net negative lift on the wing.
PHYSICAL REVIEW FLUIDS
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Jonah P. Sengupta, Martin Villemur, Philippe O. Pouliquen, Pedro Julian, Andreas G. Andreou
Summary: This paper presents a neuromorphic signal processing pipeline that reduces energy consumption, increases signal-to-noise ratio, and improves algorithm performance by sparsifying the event stream. The pipeline is integrated within a system-on-chip platform for prototyping different standards compliant hardware modules.
2022 IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS (ISCAS 22)
(2022)
Proceedings Paper
Automation & Control Systems
Martin Villemur, Jonah P. Sengupta, Pedro Julian, Andreas G. Andreou
Summary: This paper presents a high-speed object detection algorithm that uses data from an event-based camera and a spike-based, cellular neural network framework. The algorithm processes the asynchronous event data in parallel and produces object blobs, shape skeletons, and centroids for low-latency object detection.
2022 8TH INTERNATIONAL CONFERENCE ON EVENT-BASED CONTROL, COMMUNICATION AND SIGNAL PROCESSING (EBCCSP 2022)
(2022)
Proceedings Paper
Computer Science, Information Systems
Jonah P. Sengupta, Martin Villemur, Andreas G. Andreou
Summary: The paper introduces a foundation and architecture for a spike-based, neuromorphic cellular neural network, which processes spike information from a dynamic vision sensor asynchronously. Spatiotemporal filtering of spike data is achieved through mixed-signed, embedded morphological processing, and preliminary simulation and modeling indicate a clear pathway towards realizing the architecture in hardware.
2021 55TH ANNUAL CONFERENCE ON INFORMATION SCIENCES AND SYSTEMS (CISS)
(2021)
Proceedings Paper
Computer Science, Information Systems
Jonah P. Sengupta, Martin Villemur, Andreas G. Andreou
Summary: Neuromorphic vision sensors offer a low-power, bandwidth efficient method for extracting visual information, making them suitable for energy-efficient embedded systems. An algorithm for embedded, event-driven feature extraction and object tracking has been outlined, showing significant data reduction, improved throughput of feature extraction, and sustained event processing rate.
2021 55TH ANNUAL CONFERENCE ON INFORMATION SCIENCES AND SYSTEMS (CISS)
(2021)
Proceedings Paper
Computer Science, Information Systems
Daniel R. Mendat, Jonah P. Sengupta, Drake K. Foreman, Andreas G. Andreou
Summary: A graphical framework has been demonstrated to approximate visual features from spike-based sensor data, utilizing event-based camera input to compute optical flow, spatial gradient, and intensity in parallel for incremental optimization. An event-based algorithm was used to compute optical flow and aid network convergence. The full network has been deployed in Python and parallelized for potential specialized hardware deployment.
2021 55TH ANNUAL CONFERENCE ON INFORMATION SCIENCES AND SYSTEMS (CISS)
(2021)
Article
Computer Science, Interdisciplinary Applications
Tian Liang, Lin Fu
Summary: In this work, a new shock-capturing framework is proposed based on a new candidate stencil arrangement and the combination of infinitely differentiable non-polynomial RBF-based reconstruction in smooth regions with jump-like non-polynomial interpolation for genuine discontinuities. The resulting scheme achieves high order accuracy and resolves genuine discontinuities with sub-cell resolution.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Lukas Lundgren, Murtazo Nazarov
Summary: In this paper, a high-order accurate finite element method for incompressible variable density flow is introduced. The method addresses the issues of saddle point system and stability problem through Schur complement preconditioning and artificial compressibility approaches, and it is validated to have high-order accuracy for smooth problems and accurately resolve discontinuities.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Gabriele Ciaramella, Laurence Halpern, Luca Mechelli
Summary: This paper presents a novel convergence analysis of the optimized Schwarz waveform relaxation method for solving optimal control problems governed by periodic parabolic PDEs. The analysis is based on a Fourier-type technique applied to a semidiscrete-in-time form of the optimality condition, which enables a precise characterization of the convergence factor at the semidiscrete level. The behavior of the optimal transmission condition parameter is also analyzed in detail as the time discretization approaches zero.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jonas A. Actor, Xiaozhe Hu, Andy Huang, Scott A. Roberts, Nathaniel Trask
Summary: This article introduces a scientific machine learning framework that uses a partition of unity architecture to model physics through control volume analysis. The framework can extract reduced models from full field data while preserving the physics. It is applicable to manifolds in arbitrary dimension and has been demonstrated effective in specific problems.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Nozomi Magome, Naoki Morita, Shigeki Kaneko, Naoto Mitsume
Summary: This paper proposes a novel strategy called B-spline based SFEM to fundamentally solve the problems of the conventional SFEM. It uses different basis functions and cubic B-spline basis functions with C-2-continuity to improve the accuracy of numerical integration and avoid matrix singularity. Numerical results show that the proposed method is superior to conventional methods in terms of accuracy and convergence.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Timothy R. Law, Philip T. Barton
Summary: This paper presents a practical cell-centred volume-of-fluid method for simulating compressible solid-fluid problems within a pure Eulerian setting. The method incorporates a mixed-cell update to maintain sharp interfaces, and can be easily extended to include other coupled physics. Various challenging test problems are used to validate the method, and its robustness and application in a multi-physics context are demonstrated.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Xing Ji, Fengxiang Zhao, Wei Shyy, Kun Xu
Summary: This paper presents the development of a third-order compact gas-kinetic scheme for compressible Euler and Navier-Stokes solutions, constructed particularly for an unstructured tetrahedral mesh. The scheme demonstrates robustness in high-speed flow computation and exhibits excellent adaptability to meshes with complex geometrical configurations.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Alsadig Ali, Abdullah Al-Mamun, Felipe Pereira, Arunasalam Rahunanthan
Summary: This paper presents a novel Bayesian statistical framework for the characterization of natural subsurface formations, and introduces the concept of multiscale sampling to localize the search in the stochastic space. The results show that the proposed framework performs well in solving inverse problems related to porous media flows.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jacob Rains, Yi Wang, Alec House, Andrew L. Kaminsky, Nathan A. Tison, Vamshi M. Korivi
Summary: This paper presents a novel method called constrained optimized DMD with Control (cOptDMDc), which extends the optimized DMD method to systems with exogenous inputs and can enforce the stability of the resulting reduced order model (ROM). The proposed method optimally places eigenvalues within the stable region, thus mitigating spurious eigenvalue issues. Comparative studies show that cOptDMDc achieves high accuracy and robustness.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Andrea La Spina, Jacob Fish
Summary: This work introduces a hybridizable discontinuous Galerkin formulation for simulating ideal plasmas. The proposed method couples the fluid and electromagnetic subproblems monolithically based on source and employs a fully implicit time integration scheme. The approach also utilizes a projection-based divergence correction method to enforce the Gauss laws in challenging scenarios. Numerical examples demonstrate the high-order accuracy, efficiency, and robustness of the proposed formulation.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Junhong Yue, Peijun Li
Summary: This paper proposes two numerical methods (IP-FEM and BP-FEM) to study the flexural wave scattering problem of an arbitrary-shaped cavity on an infinite thin plate. These methods successfully decompose the fourth-order plate wave equation into the Helmholtz and modified Helmholtz equations with coupled conditions on the cavity boundary, providing an effective solution to this challenging problem.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
William Anderson, Mohammad Farazmand
Summary: We develop fast and scalable methods, called RONS, for computing reduced-order nonlinear solutions. These methods have been proven to be highly effective in tackling challenging problems, but become computationally prohibitive as the number of parameters grows. To address this issue, three separate methods are proposed and their efficacy is demonstrated through examples. The application of RONS to neural networks is also discussed.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Marco Caliari, Fabio Cassini
Summary: In this paper, a second order exponential scheme for stiff evolutionary advection-diffusion-reaction equations is proposed. The scheme is based on a directional splitting approach and uses computation of small sized exponential-like functions and tensor-matrix products for efficient implementation. Numerical examples demonstrate the advantage of the proposed approach over state-of-the-art techniques.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Sebastiano Boscarino, Seung Yeon Cho, Giovanni Russo
Summary: This work proposes a high order conservative semi-Lagrangian method for the inhomogeneous Boltzmann equation of rarefied gas dynamics. The method combines a semi-Lagrangian scheme for the convection term, a fast spectral method for computation of the collision operator, and a high order conservative reconstruction and a weighted optimization technique to preserve conservative quantities. Numerical tests demonstrate the accuracy and efficiency of the proposed method.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jialei Li, Xiaodong Liu, Qingxiang Shi
Summary: This study shows that the number, centers, scattering strengths, inner and outer diameters of spherical shell-structured sources can be uniquely determined from the far field patterns. A numerical scheme is proposed for reconstructing the spherical shell-structured sources, which includes a migration series method for locating the centers and an iterative method for computing the inner and outer diameters without computing derivatives.
JOURNAL OF COMPUTATIONAL PHYSICS
(2024)
