143 results match your criteria motion compressible

Highly Compressible and Sensitive Flexible Piezoresistive Pressure Sensor Based on MWCNTs/TiCT MXene @ Melamine Foam for Human Gesture Monitoring and Recognition.

Nanomaterials (Basel) 2022 Jun 29;12(13). Epub 2022 Jun 29.

Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100864, China.

Flexible sensing devices provide a convenient and effective solution for real-time human motion monitoring, but achieving efficient and low-cost assembly of pressure sensors with high performance remains a considerable challenge. Herein, a highly compressible and sensitive flexible foam-shaped piezoresistive pressure sensor was prepared by sequential fixing multiwalled carbon nanotubes and Ti3C2Tx MXene on the skeleton of melamine foam. Due to the porous skeleton of the melamine foam and the extraordinary electrical properties of the conductive fillers, the obtained MWCNTs/Ti3C2Tx MXene @ melamine foam device features high sensitivity of 0. Read More

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Technical note: Low-cost MR-compatible pneumatic respiratory organ motion simulator for the development of MR-guided thermal therapy.

Med Phys 2022 Jul 7;49(7):4365-4371. Epub 2022 Jun 7.

Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.

Background: In magnetic resonance (MR)-guided thermal therapy, respiratory motion can cause a significant temperature error in MR thermometry and reduce the efficiency of the treatment. A respiratory motion simulator is necessary for the development of new MR imaging (MRI) and motion compensation techniques.

Purpose: The purpose of this study is to develop a low-cost and simple MR-compatible respiratory motion simulator to support proof-of-concept studies of MR monitoring approaches with respiratory-induced abdominal organ motion. Read More

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Critical pressure in liquids due to dynamic choking.

Phys Rev E 2022 Apr;105(4-2):045107

Institute of Automotive Engineering, Faculty of Mechanical Engineering, Brno University of Technology, Technická 2896/2, 616 69 Brno, Czech Republic.

The existence of a critical pressure ratio due to gas-dynamic choking is well known for an ideal gas. It is reasonable to assume that liquids whose compressibility is defined by the bulk modulus also have a critical pressure ratio. The problem discussed here is a fundamental one because it deals with the basic principles of the compressible flow of liquids. Read More

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Quadrupolar active stress induces exotic patterns of defect motion in compressible active nematics.

Soft Matter 2022 Jun 1;18(21):4118-4126. Epub 2022 Jun 1.

The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.

A wide range of living and artificial active matter exists in close contact with substrates and under strong confinement, where in addition to dipolar active stresses, quadrupolar active stresses can become important. Here, we numerically investigate the impact of quadrupolar non-equilibrium stresses on the emergent patterns of self-organisation in non-momentum conserving active nematics. Our results reveal that beyond having stabilising effects, the quadrupolar active forces can induce various modes of topological defect motion in active nematics. Read More

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Combined Gluteal and Posterior Thigh Compartment Syndrome Without Associated Fracture: A Case Report.

J Clin Med Res 2022 Apr 30;14(4):170-173. Epub 2022 Apr 30.

Department of General Medicine, Saint Helena General Hospital, Jamestown, STHL 1ZZ Saint Helena, South Atlantic Ocean, UK.

Compartment syndrome usually occurs after trauma, fracture, or compression injuries. To the authors' best knowledge, this is the first reported case in the medical literature of a combined gluteal and posterior thigh compartment syndrome after an accidental fall without an associated fracture. A 65-year-old man attended the emergency department of the general hospital in a remote island complaining of a swollen painful thigh. Read More

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Equations of motion for weakly compressible point vortices.

Philos Trans A Math Phys Eng Sci 2022 Jun 9;380(2226):20210052. Epub 2022 May 9.

Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.

Equations of motion for compressible point vortices in the plane are obtained in the limit of small Mach number, , using a Rayleigh-Jansen expansion and the method of Matched Asymptotic Expansions. The solution in the region between vortices is matched to solutions around each vortex core. The motion of the vortices is modified over long time scales [Formula: see text] and [Formula: see text]. Read More

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Invariant Measures for the Stochastic One-Dimensional Compressible Navier-Stokes Equations.

Appl Math Optim 2021 16;83(3):1487-1522. Epub 2019 Jul 16.

Department of Mathematics, University of Maryland, College Park, MD 20742 USA.

We investigate the long-time behavior of solutions to a stochastically forced one-dimensional Navier-Stokes system, describing the motion of a compressible viscous fluid, in the case of linear pressure law. We prove existence of an invariant measure for the Markov process generated by strong solutions. We overcome the difficulties of working with non-Feller Markov semigroups on non-complete metric spaces by generalizing the classical Krylov-Bogoliubov method, and by providing suitable polynomial and exponential moment bounds on the solution, together with pathwise estimates. Read More

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Nonlinear dynamics of a solid particle in an acoustically excited viscoelastic fluid. II. Acoustic radiation force.

Phys Rev E 2021 Dec;104(6-2):065108

Department of Mechanical and Process Engineering, Institute for Mechanical Systems (IMES), Swiss Federal Institute of Technology (ETH Zurich), Tannenstrasse 3, 8092 Zurich, Switzerland.

An analytical formula is derived for acoustic radiation force exerted by an axisymmetric acoustic wave on an isotropic solid spherical particle in a compressible viscoelastic fluid. The particle is assumed to undergo pulsation, translation, and shape deformations of all orders. The fluid motion is described by the compressible Oldroyd-B model. Read More

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December 2021

Nonlinear dynamics of a solid particle in an acoustically excited viscoelastic fluid. I. Acoustic streaming.

Phys Rev E 2021 Dec;104(6-2):065107

Department of Mechanical and Process Engineering, Institute for Mechanical Systems (IMES), Swiss Federal Institute of Technology (ETH Zurich), Tannenstrasse 3, 8092 Zurich, Switzerland.

An analytical theory is developed for acoustic streaming induced by an axisymmetric acoustic wave field around an isotropic solid spherical particle in a compressible viscoelastic fluid. The particle is assumed to undergo pulsation, translation, and shape deformations of all orders. The fluid motion is described by the compressible Oldroyd-B model. Read More

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December 2021

The ultrafast snap of a finger is mediated by skin friction.

J R Soc Interface 2021 11 17;18(184):20210672. Epub 2021 Nov 17.

Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30311, USA.

The snap of a finger has been used as a form of communication and music for millennia across human cultures. However, a systematic analysis of the dynamics of this rapid motion has not yet been performed. Using high-speed imaging and force sensors, we analyse the dynamics of the finger snap. Read More

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November 2021

Computed Tomography Imaging in Simulated Ongoing Cardiopulmonary Resuscitation: No Need to Switch Off the Chest Compression Device during Image Acquisition.

Diagnostics (Basel) 2021 Jun 19;11(6). Epub 2021 Jun 19.

Department of Radiology, Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin, 12203 Berlin, Germany.

Computed tomography (CT) represents the current standard for imaging of patients with acute life-threatening diseases. As some patients present with circulatory arrest, they require cardiopulmonary resuscitation. Automated chest compression devices are used to continue resuscitation during CT examinations, but tend to cause motion artifacts degrading diagnostic evaluation of the chest. Read More

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Self-Restoring Capacitive Pressure Sensor Based on Three-Dimensional Porous Structure and Shape Memory Polymer.

Polymers (Basel) 2021 Mar 8;13(5). Epub 2021 Mar 8.

Precision Mechanical Process and Control R&D Group, Korea Institute of Industrial Technology, 42-7, Baegyang-daero 804beon-gil, Sasang-gu, Busan 46938, Korea.

Highly flexible and compressible porous polyurethane (PU) structures have effectively been applied in capacitive pressure sensors because of the good elastic properties of the PU structures. However, PU porous structure-based pressure sensors have been limited in practical applications owing to their low durability during pressure cycling. Herein, we report a flexible pressure sensor based on a three-dimensional porous structure with notable durability at a compressive pressure of 500 kPa facilitated by the use of a shape memory polymer (SMP). Read More

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Regimes of Soft Lubrication.

J Fluid Mech 2021 May 15;915. Epub 2021 Mar 15.

Physics of Fluids Group, Faculty of Science and Technology, Mesa+ Institute, University of Twente, 7500 AE Enschede, The Netherlands.

Elastohydrodynamic lubrication, or simply soft lubrication, refers to the motion of deformable objects near a boundary lubricated by a fluid, and is one of the key physical mechanisms to minimise friction and wear in natural and engineered systems. Hence it is of particular interest to relate the thickness of the lubricant layer to the entrainment (sliding/rolling) velocity, the mechanical loading exerted onto the contacting elements, and properties of the elastic boundary. In this work we provide an overview of the various regimes of soft lubrication for two-dimensional cylinders in lubricated contact with compliant walls. Read More

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Faraday-Wave Contact-Line Shear Gradient Induces Streaming and Tracer Self-Organization: From Vortical to Hedgehoglike Patterns.

Phys Rev Lett 2020 Dec;125(25):254505

Departamento de Física, Universidad de Santiago de Chile, Avenida Ecuador 3493, Estación Central, Santiago, Chile.

In this Letter, we experimentally demonstrate self-organization of small tracers under the action of longitudinal Faraday waves in a narrow container. We observe a steady current formation dividing the interface in small cells given by Faraday-wave symmetries. These streaming currents rotate in each cell, and their circulation increases with wave amplitude. Read More

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December 2020

Numerical Study of Nanoparticle Deposition in a Gaseous Microchannel under the Influence of Various Forces.

Micromachines (Basel) 2021 Jan 1;12(1). Epub 2021 Jan 1.

Institute of Fluid Measurement and Simulation, China Jiliang University, Hangzhou 310018, China.

Nanoparticle deposition in microchannel devices inducing contaminant clogging is a serious barrier to the application of micro-electro-mechanical systems (MEMS). For micro-scale gas flow fields with a high Knudsen number () in the microchannel, gas rarefaction and velocity slip cannot be ignored. Furthermore, the mechanism of nanoparticle transport and deposition in the microchannel is extremely complex. Read More

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January 2021

Effect of Supraglottal Acoustics on Fluid-Structure Interaction During Human Voice Production.

J Biomech Eng 2021 04;143(4)

Department of Mechanical Engineering, University of Maine, Room 213 A, Boardman Hall, Orono, ME 04473.

A hydrodynamic/acoustic splitting method was used to examine the effect of supraglottal acoustics on fluid-structure interactions during human voice production in a two-dimensional computational model. The accuracy of the method in simulating compressible flows in typical human airway conditions was verified by comparing it to full compressible flow simulations. The method was coupled with a three-mass model of vocal fold lateral motion to simulate fluid-structure interactions during human voice production. Read More

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Prospective, multicenter clinical trial comparing M6-C compressible six degrees of freedom cervical disc with anterior cervical discectomy and fusion for the treatment of single-level degenerative cervical radiculopathy: 2-year results of an FDA investigational device exemption study.

Spine J 2021 02 21;21(2):239-252. Epub 2020 Oct 21.

OrthoCarolina, 2001 Randolph Rd, Charlotte, NC 28207, USA.

Background Context: Various designs of total disc replacement (TDR) devices have been compared to anterior cervical discectomy and fusion (ACDF) with favorable outcomes in FDA-approved investigational device exemption trials. The design of M6-C with a compressible viscoelastic nuclear core and an annular structure is substantially different than prior designs and has previously demonstrated favorable kinematics and clinical outcomes in small case series.

Purpose: To evaluate the safety and effectiveness of the novel M6-C compressible artificial cervical disc compared with ACDF for subjects with single-level degenerative cervical radiculopathy. Read More

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February 2021

Actomyosin Contraction Induces In-Bulk Motility of Cells and Droplets.

Biophys J 2020 09 6;119(5):1025-1032. Epub 2020 Jul 6.

SUPA, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom. Electronic address:

Cell crawling on two-dimensional surfaces is a relatively well-understood phenomenon that is based on actin polymerization at a cell's front edge and anchoring on a substrate, allowing the cell to pull itself forward. However, some cells, such as cancer cells invading a three-dimensional matrigel, can also swim in the bulk, where surface adhesion is impossible. Although there is strong evidence that the self-organized engine that drives cells forward in the bulk involves myosin, the specific propulsion mechanism remains largely unclear. Read More

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September 2020

An improved abdominal phantom for intrafraction image guidance validation.

Phys Med Biol 2020 07 3;65(13):13NT02. Epub 2020 Jul 3.

School of Medicine and Public Health Department of Medical Physics, University of Wisconsin, Madison, WI, United States of America. Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, United States of America.

A dynamically compressible phantom of the human abdomen that simulates organ motion with breathing is being developed for possible testing of image-gated beam delivery in radiotherapy. The polyvinyl chloride plastisol (PVCP) phantom features a cavity that can contain a deformable normoxic polyacrylamide gel (nPAG) dosimeter that is intended for use with MRI to provide dosimetric data. The phantom has been improved by the inclusion of new components that are more realistic anatomically and exhibit CT values similar to those of the tissues they mimic. Read More

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Arbitrary Lagrangian-Eulerian unstructured finite-volume lattice-Boltzmann method for computing two-dimensional compressible inviscid flows over moving bodies.

Phys Rev E 2020 Feb;101(2-1):023308

Aerospace Engineering Department, Sharif University of Technology, Tehran 11365-11155, Iran.

The objective of this study is to develop and apply an arbitrary Lagrangian-Eulerian unstructured finite-volume lattice-Boltzmann method (ALE-FVLBM) for solving two-dimensional compressible inviscid flows around moving bodies. The two-dimensional compressible form of the LB equation is considered and the resulting LB equation is formulated in the ALE framework on an unstructured body-fitted mesh to correctly model the body shape and properly incorporate the mesh movement due to the body motion. The spatial discretization of the resulting system of equations is performed by a second-order cell-centered finite-volume method on arbitrary quadrilateral meshes and an implicit dual-time stepping method is utilized for the time integration. Read More

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February 2020

Analysis of the aerodynamic sound of speech through static vocal tract models of various glottal shapes.

J Biomech 2020 01 5;99:109484. Epub 2019 Nov 5.

Department of Mechanics, Linné FLOW Centre, KTH Royal Institute of Technology, Stockholm SE-10044, Sweden. Electronic address:

The acoustic spectrum of our voice can be divided into harmonic and inharmonic sound components. While the harmonic components, generated by the oscillatory motion of the vocal folds, are well described by reduced-order speech models, the accurate computation of the inharmonic components requires high-order flow simulations, which predict the vortex shedding and turbulent structures present in the shear layers of the glottal jet. This study characterizes the dominant frequencies in the unsteady flow of the intra- and supraglottal region. Read More

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January 2020

Highly Compressible and Robust Polyimide/Carbon Nanotube Composite Aerogel for High-Performance Wearable Pressure Sensor.

ACS Appl Mater Interfaces 2019 Nov 29;11(45):42594-42606. Epub 2019 Oct 29.

Key Laboratory of Materials Processing and Mold (Zhengzhou University), Ministry of Education; National Engineering Research Center for Advanced Polymer Processing Technology , Zhengzhou University , Zhengzhou , Henan 450002 , China.

Wearable pressure sensors are in great demand with the rapid development of intelligent electronic devices. However, it is still a huge challenge to obtain high-performance pressure sensors with high sensitivity, wide response range, and low detection limit simultaneously. Here, a polyimide (PI)/carbon nanotube (CNT) composite aerogel with the merits of superelastic, high porosity, robust, and high-temperature resistance was successfully prepared through the freeze drying plus thermal imidization process. Read More

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November 2019

Exact formula for the horizontal-to-vertical displacement ratio of Rayleigh waves in layered orthotropic half-spaces.

J Acoust Soc Am 2019 Aug;146(2):1279

Institute for Geosciences, Friedrich-Schiller University Jena, Burgweg 11, 07749 Jena, Germany.

This paper is concerned with the propagation of Rayleigh waves in a compressible orthotropic half-space coated by a compressible orthotropic layer. The main purpose of the paper is to establish an explicit exact formula for the H/V ratio (the horizontal-to-vertical displacement ratio) of the Rayleigh wave. This formula is derived by using the transfer matrix for an orthotropic elastic layer and by the effective boundary condition technique. Read More

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Highly Compressible and Sensitive Pressure Sensor under Large Strain Based on 3D Porous Reduced Graphene Oxide Fiber Fabrics in Wide Compression Strains.

ACS Appl Mater Interfaces 2019 Oct 10;11(40):37051-37059. Epub 2019 Sep 10.

Department of Machine Intelligence and Systems Engineering, Faculty of Systems Science and Technology , Akita Prefectural University , Yurihonjo 015-0055 , Japan.

The development of highly sensitive wearable and foldable pressure sensors is one of the central topics in artificial intelligence, human motion monitoring, and health care monitors. However, current pressure sensors with high sensitivity and good durability in low, medium, and high applied strains are rather limited. Herein, a flexible pressure sensor based on hierarchical three-dimensional and porous reduced graphene oxide (rGO) fiber fabrics as the key sensing element is presented. Read More

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October 2019

Generalization of the Zabolotskaya equation to all incompressible isotropic elastic solids.

Proc Math Phys Eng Sci 2019 Jul 3;475(2227):20190061. Epub 2019 Jul 3.

School of Mathematics, Statistics and Applied Mathematics, NUI Galway, University Road Galway, Republic of Ireland.

We study elastic shear waves of small but finite amplitude, composed of an anti-plane shear motion and a general in-plane motion. We use a multiple scales expansion to derive an asymptotic system of coupled nonlinear equations describing their propagation in all isotropic incompressible nonlinear elastic solids, generalizing the scalar Zabolotskaya equation of compressible nonlinear elasticity. We show that for a general isotropic incompressible solid, the coupling between anti-plane and in-plane motions cannot be undone and thus conclude that linear polarization is impossible for general nonlinear two-dimensional shear waves. Read More

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Bridging the gap between molecular dynamics and hydrodynamics in nanoscale Brownian motions.

Soft Matter 2019 May;15(21):4380-4390

Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.

Through molecular dynamics simulations, we examined the hydrodynamic behavior of the Brownian motion of fullerene particles based on molecular interactions. The solvation free energy and velocity autocorrelation function (VACF) were calculated by using the Lennard-Jones (LJ) and Weeks-Chandler-Andersen (WCA) potentials for the solute-solvent and solvent-solvent interactions and by changing the size of the fullerene particles. We also measured the diffusion constant of the fullerene particles and the shear viscosity of the host fluid, and then the hydrodynamic radius aHD was quantified from the Stokes-Einstein relation. Read More

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Plantar Acceleration Time: A Novel Technique to Evaluate Arterial Flow to the Foot.

Ann Vasc Surg 2019 Oct 8;60:308-314. Epub 2019 May 8.

PeaceHealth Thoracic and Vascular Surgery, Vancouver, WA. Electronic address:

Background: Arterial duplex ultrasound (DUS) and ankle-brachial indices (ABIs) are accepted methods for assessing lower limb arterial perfusion. However, in a significant number of diabetic patients, medial wall calcification often precludes an ABI measurement. Direct, noninvasive duplex imaging of the pedal arch in the setting of peripheral arterial disease (PAD) has not been well evaluated. Read More

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October 2019

Modeling of Microbubble-Enhanced High-Intensity Focused Ultrasound.

Ultrasound Med Biol 2019 07 12;45(7):1743-1761. Epub 2019 Apr 12.

Dynaflow, Inc., Jessup, Maryland, USA.

Heat enhancement at the target in a high intensity focused ultrasound (HIFU) field is investigated by considering the effects of the injection of microbubbles in the vicinity of the tumor to be ablated. The interaction between the bubble cloud and the HIFU field is investigated using a 3-D numerical model. The propagation of non-linear ultrasonic waves in the tissue or in a phantom medium is modeled using the compressible Navier-Stokes equations on a fixed Eulerian grid, while the microbubbles dynamics and motion are modeled as discrete singularities, which are tracked in a Lagrangian framework. Read More

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Eulerian-Lagrangian method for simulation of cloud cavitation.

J Comput Phys 2018 Oct 18;371:994-1017. Epub 2018 May 18.

Division of Engineering and Applied Science, California Institute of Technology 1200 East California Boulevard, Pasadena, CA 91125, USA.

We present a coupled Eulerian-Lagrangian method to simulate cloud cavitation in a compressible liquid. The method is designed to capture the strong, volumetric oscillations of each bubble and the bubble-scattered acoustics. The dynamics of the bubbly mixture is formulated using volume-averaged equations of motion. Read More

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October 2018

Fixation probabilities in weakly compressible fluid flows.

Proc Natl Acad Sci U S A 2019 01 26;116(2):373-378. Epub 2018 Dec 26.

Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.

Competition between biological species in marine environments is affected by the motion of the surrounding fluid. An effective 2D compressibility can arise, for example, from the convergence and divergence of water masses at the depth at which passively traveling photosynthetic organisms are restricted to live. In this report, we seek to quantitatively study genetics under flow. Read More

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January 2019