3,258 results match your criteria velocity distributions


Structure and dynamics of small-scale turbulence in vaporizing two-phase flows.

Sci Rep 2021 Jul 27;11(1):15242. Epub 2021 Jul 27.

School of Engineering, Newcastle University, Claremont Road, Newcastle-Upon-Tyne, NE1 7RU, UK.

Improving our fundamental understanding of multiphase turbulent flows will be beneficial for analyses of a wide range of industrial and geophysical processes. Herein, we investigate the topology of the local flow in vaporizing forced homogeneous isotropic turbulent two-phase flows. The invariants of the velocity-gradient, rate-of-strain, rate-of-rotation tensors, and scalar gradient were computed and conditioned for different distances from the liquid-gas surface. Read More

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Photodissociation Dynamics of CHOO on Multiple Potential Energy Surfaces: Experiment and Theory.

J Phys Chem A 2021 Jul 27. Epub 2021 Jul 27.

Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States.

UV excitation of the CHOO Criegee intermediate across most of the broad span of the (B A')-(X A') spectrum results in prompt dissociation to two energetically accessible asymptotes: O (D) + HCO (X A) and O (P) + HCO (a A''). Dissociation proceeds on multiple singlet potential energy surfaces that are coupled by two regions of conical intersection (CoIn). Velocity map imaging (VMI) studies reveal a bimodal total kinetic energy release (TKER) distribution for the O (D) + HCO (X A) products with the major and minor components accounting for ca. Read More

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Influence of road salt thawing peaks on the inflow composition and activated sludge properties in municipal wastewater treatment.

Water Sci Technol 2021 Jul;84(2):314-322

Institute for Water Quality and Resource Management, TU Wien, Karlsplatz 13/226, 1040 Vienna, Austria.

Operational data over 2 years from three large Austrian wastewater treatment plants (WWTPs) with design capacities of 4 million, 950,000 and 110,000 population equivalent (PE) were examined. Salt peaks, due to thawing road salt were detected and quantified by electrical conductivity, temperature and chloride measurement in the inflow of the WWTPs. Daily NaCl inflow loads up to 1,147 t/d and PE-specific loads of 0. Read More

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Forecasting of the composite dose for organs at risk and solid targets with random movements during different image-guided scenarios of the photon radiation therapy. Solution for the Varian therapeutic line.

Rep Pract Oncol Radiother 2021 9;26(3):489-494. Epub 2021 Jun 9.

Department of Medical Physics, Greater Poland Cancer Centre, Poznań, Poland.

Background: This study aims to develop a useful tool for robust plan analysis which includes the effects of soft tissue deformations on simulated dose distributions. The solution was benchmarked in the light of the commercial method implemented in Eclipse treatment planning system (TPS).

Materials And Methods: Study was carried out on data of one patient with prostate-restricted cancer. Read More

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Liquid-microjet photoelectron imaging spectrometry for liquid aqueous solutions.

Rev Sci Instrum 2021 Jun;92(6):065108

State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China.

A new liquid-microjet photoelectron imaging (PEI) spectrometer has been constructed that combines the liquid-microjet technique with velocity-map imaging. This novel method enables us to simultaneously measure the energy and angular distributions of the photoelectrons produced from highly volatile liquid solutions. The capability of the spectrometer has been demonstrated by recording the photoelectron image of the aqueous 2-furfural. Read More

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Measurements of impurity ion temperature and velocity distributions via active charge-exchange recombination spectroscopy in C-2W.

Rev Sci Instrum 2021 May;92(5):053512

TAE Technologies, Rancho Santa Margarita, California 92688, USA.

In TAE Technologies' C-2W experiment, electrode biasing is utilized for boundary control of a field-reversed configuration (FRC) plasma embedded in a magnetic mirror. Understanding the underlying physics associated with FRC rotation, stabilization, and heating is crucial for improving machine performance. Impurity ion rotation and temperature are sensitive to biasing effects, and measurements of these quantities can provide insight into important plasma dynamics and overall effectiveness of the biasing system. Read More

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A Comparison of Six Transport Models of the MADE-1 Experiment Implemented With Different Types of Hydraulic Data.

Water Resour Res 2021 May 26;57(5):e2020WR028672. Epub 2021 May 26.

Helmholtz Centre for Environmental Research - UFZ Leipzig Germany.

Six conceptually different transport models were applied to the macrodispersion experiment (MADE)-1 field tracer experiment as a first major attempt for model comparison. The objective was to show that complex mass distributions in heterogeneous aquifers can be predicted without calibration of transport parameters, solely making use of structural and flow data. The models differ in their conceptualization of the heterogeneous aquifer structure, computational complexity, and use of conductivity data obtained from various observation methods (direct push injection logging, DPIL, grain size analysis, pumping tests and flowmeter). Read More

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Strain Rate Distribution in Layered Myocardium Measured Using Local Velocity Estimator with Multifrequency Phase Differences.

Ultrasound Med Biol 2021 Jun 30. Epub 2021 Jun 30.

Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan; Graduate School of Engineering, Tohoku University, Sendai, Japan.

Measurement of the myocardial strain rate (SR), with high spatial resolution, is useful in evaluation of the transmurality of myocardial infarction. As the SR distribution is calculated using velocities observed at multiple positions in the heart wall, it is necessary to estimate the local velocity to measure SR distribution. In the present study, our previously proposed local velocity estimator, with multifrequency phase differences, was used to measure SR distribution in the heart wall. Read More

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[Single-molecule electrophoresis: renewed understanding of nanopore electrochemistry].

Se Pu 2020 Sep;38(9):993-998

School of Chemistry and Molecule Engineering, East China University of Science and Technology, Shanghai 200237, China.

This study aims to understand nanopore technology from the standpoint of capillary electrophoresis separation. The nanopore electrochemical measurements could be regarded as "single molecule electrophoresis". Similar to the case of capillary electrophoresis, the single target molecules migrate inside a nanopore under an external electric field. Read More

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September 2020

Profiles of and variations in aluminum species in PAC-MC used for the removal of blooming microalgae.

J Environ Sci (China) 2021 Aug 27;106:76-82. Epub 2021 Jan 27.

College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.

Polyaluminum chloride modified clay (PAC-MC) is a safe and efficient red tide control agent that has been studied and applied worldwide. Although it is well known that the distribution of hydrolytic aluminum species in PAC affects its flocculation, little is known about the influence of particulars aluminum species on the microalgae removal efficiency of PAC-MC; this lack of knowledge creates a bottleneck in the development of more efficient MCs based on aluminum salts. The ferron method was used in this study to quantitatively analyze the distributions of and variations in different hydrolytic aluminum species during the process of microalgae removal by PAC-MC. Read More

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Space Electroosmotic Thrusters in Ion Partitioning Soft Nanochannels.

Micromachines (Basel) 2021 Jun 30;12(7). Epub 2021 Jun 30.

School of Mathematical Science, Inner Mongolia University, Hohhot 010021, China.

Space electroosmotic thrusters (EOTs) are theoretically investigated in a soft charged nanochannel with a dense polyelectrolyte layer (PEL), which is considered to be more realistic than a low-density PEL. When the PEL is dense, its permittivity is smaller than the one of the electrolyte solution layer, leading to rearrangement of ions in the channel, which is denoted as the ion partitioning effect. It is noted that fluid viscosity becomes high within the PEL owing to the hydration effect. Read More

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Plasma Modeling and Prebiotic Chemistry: A Review of the State-of-the-Art and Perspectives.

Molecules 2021 Jun 16;26(12). Epub 2021 Jun 16.

Istituto per la Scienza e Tecnologia dei Plasmi, CNR, Via Amendola, 122/D, 70126 Bari, Italy.

We review the recent progress in the modeling of plasmas or ionized gases, with compositions compatible with that of primordial atmospheres. The plasma kinetics involves elementary processes by which free electrons ultimately activate weakly reactive molecules, such as carbon dioxide or methane, thereby potentially starting prebiotic reaction chains. These processes include electron-molecule reactions and energy exchanges between molecules. Read More

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Effect of Ergodic and Non-Ergodic Fluctuations on a Charge Diffusing in a Stochastic Magnetic Field.

Entropy (Basel) 2021 Jun 19;23(6). Epub 2021 Jun 19.

Departamento de Ingeniería Eléctrica-Electrónica, Universidad de Tarapacá, Arica 1000000, Chile.

In this paper, we study the basic problem of a charged particle in a stochastic magnetic field. We consider dichotomous fluctuations of the magnetic field where the sojourn time in one of the two states are distributed according to a given waiting-time distribution either with Poisson or non-Poisson statistics, including as well the case of distributions with diverging mean time between changes of the field, corresponding to an ergodicity breaking condition. We provide analytical and numerical results for all cases evaluating the average and the second moment of the position and velocity of the particle. Read More

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A Multi-Rheology Design Method of Sheeting Polymer Extrusion Dies Based on Flow Network and the Winter-Fritz Design Equation.

Polymers (Basel) 2021 Jun 10;13(12). Epub 2021 Jun 10.

Department of Civil & Environmental Engineering, School of Engineering & Digital Sciences, Nazarbayev University, Kabanbay Batyr 53, Nur-Sultan 0100000, Kazakhstan.

In the polymer sheet processing industry, the primary objective when designing a coat-hanger die is to achieve a uniform velocity distribution at the exit of the extrusion die outlet. This velocity distribution depends on the internal flow channels of the die, rheological parameters and extrusion process conditions. As a result, coat-hanger dies are often designed for each polymer based on its individual rheological data and other conditions. Read More

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Cross talk between endothelial and red blood cell glycocalyces via near-field flow.

Biophys J 2021 Jun 29. Epub 2021 Jun 29.

Department of Mechanical Engineering, University College London, London, United Kingdom. Electronic address:

Vascular endothelial cells and circulating red blood cell (RBC) surfaces are both covered by a layer of bushy glycocalyx. The interplay between these glycocalyx layers is hardly measurable and insufficiently understood. This study aims to investigate and qualify the possible interactions between the glycocalyces of RBCs and endothelial cells using mathematical modeling and numerical simulation. Read More

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The characteristics and in-sewer transport potential of solids derived from domestic food waste disposers.

Water Sci Technol 2021 Jun;83(12):2963-2979

Department of Civil & Structural Engineering, University of Sheffield, Mappin Street, Sheffield, UK E-mail:

This study aims to assess the transportability of food waste disposer particles within a sewer system. A series of laboratory studies has examined the physical characteristics of solid particles derived from domestic food waste disposers. Particle size distributions and maximum settling velocity characteristics were measured for 18 common food types, and stored in a publicly accessible database. Read More

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Patient-specific fluid-structure interaction model of bile flow: comparison between 1-way and 2-way algorithms.

Comput Methods Biomech Biomed Engin 2021 Jun 26:1-25. Epub 2021 Jun 26.

Institute of Mechanics of Moscow State University, Moscow, Russian Federation.

Gallbladder disease is one of the most spread pathologies in the world. Despite the number of operations dealing with biliary surgery increases, the number of postoperative complications is also high. The aim of this study is to show the influence of the biliary system pathology on bile flow character and to numerically assess the effect of surgical operation (cholecystectomy) on the fluid dynamics in the extrahepatic biliary tree, and also to reveal the difference between 1-way and 2-way FSI algorithms on the results. Read More

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Energy partitioning and spin-orbit effects in the photodissociation of higher chloroalkanes.

Phys Chem Chem Phys 2021 Jul;23(26):14340-14351

J. Heyrovský Institute of Physical Chemistry, v.v.i., The Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.

We investigate the photodissociation dynamics of the C-Cl bond in chloroalkanes CH3Cl, n-C3H7Cl, i-C3H7Cl, n-C5H11Cl, combining velocity map imaging (VMI) experiment and direct ab initio dynamical simulations. The Cl fragment kinetic energy distributions (KEDs) from the VMI experiment exhibit a single peak with maximum close to 0.8 eV, irrespective of the alkyl chain length and C-Cl bond position. Read More

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On the Sensitivity Analysis of Porous Finite Element Models for Cerebral Perfusion Estimation.

Ann Biomed Eng 2021 Jun 21. Epub 2021 Jun 21.

Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK.

Computational physiological models are promising tools to enhance the design of clinical trials and to assist in decision making. Organ-scale haemodynamic models are gaining popularity to evaluate perfusion in a virtual environment both in healthy and diseased patients. Recently, the principles of verification, validation, and uncertainty quantification of such physiological models have been laid down to ensure safe applications of engineering software in the medical device industry. Read More

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Mean-field theories for depinning and their experimental signatures.

Phys Rev E 2021 May;103(5-1):052114

Laboratoire de Physique de l'Ećole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, 24 rue Lhomond, 75005 Paris, France.

Mean-field theory is an approximation replacing an extended system by a few variables. For depinning of elastic manifolds, these are the position u of its center of mass and the statistics of the forces F(u). There are two proposals how to model the latter: as a random walk (ABBM model), or as uncorrelated forces at integer u (discretized particle model, DPM). Read More

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High accuracy capillary network representation in digital rock reveals permeability scaling functions.

Sci Rep 2021 Jun 15;11(1):11370. Epub 2021 Jun 15.

IBM Research, Rio de Janeiro, RJ, 22290-240, Brazil.

Permeability is the key parameter for quantifying fluid flow in porous rocks. Knowledge of the spatial distribution of the connected pore space allows, in principle, to predict the permeability of a rock sample. However, limitations in feature resolution and approximations at microscopic scales have so far precluded systematic upscaling of permeability predictions. Read More

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Measurements of exhaled airflow velocity through human coughs using particle image velocimetry.

Build Environ 2021 Sep 9;202:108020. Epub 2021 Jun 9.

School of Engineering, The University of Tokyo, Tokyo, Japan.

The sudden outbreak of coronavirus (COVID-19) has infected over 100 million people and led to over two million deaths (data in January 2021), posing a significant threat to global human health. As a potential carrier of the novel coronavirus, the exhaled airflow of infected individuals through coughs is significant in virus transmission. The research of detailed airflow characteristics and velocity distributions is insufficient because most previous studies utilize particle image velocimetry (PIV) with low frequency. Read More

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September 2021

Importance of convective boundary layer flows with inhomogeneous material properties under linear and quadratic Boussinesq approximations around a horizontal cylinder.

Heliyon 2021 May 25;7(5):e07074. Epub 2021 May 25.

Department of Mathematics, Obafemi Awolowo University, Ile-Ife, 220005, Nigeria.

This study investigates boundary layer flows with inhomogeneous material properties driven by natural convection using linear and quadratic Boussinesq approximations around a horizontal cylinder. The cylinder's surface was kept at a uniform temperature. The governing equations for the setup were formulated from the principles of mass continuity, momentum and energy under realistic assumptions. Read More

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Quantifying groundwater flow variability in a poorly cemented fractured sandstone aquifer to inform in situ remediation.

J Contam Hydrol 2021 May 27;241:103838. Epub 2021 May 27.

G360 Institute for Groundwater Research, University of Guelph, Canada.

This study applies innovative methods to characterize and quantify the magnitude of groundwater flow in a fractured and variably cemented sandstone aquifer to inform an in-situ remediation strategy for trichloroethene (TCE) contamination. A modified active-distributed temperature sensing (A-DTS) approach in which fiber optic cables were permanently grouted in the borehole was used to quantify groundwater flow rates. Two additional tracer tests were conducted: 1) fluorescein tracer injection followed by rock coring and sampling for visual mapping and porewater analysis, and 2) deployment of passive flux meters in conventional monitoring wells to evaluate groundwater velocity and mass flux distributions. Read More

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Multiphysics Modeling and Simulation of Subcutaneous Injection and Absorption of Biotherapeutics: Sensitivity Analysis.

Pharm Res 2021 Jun 2;38(6):1011-1030. Epub 2021 Jun 2.

Department of Industrial and Physical Pharmacy, Purdue University, 525 Stadium Mall Dr. RHPH Building, Indiana, 47907, West Lafayette, USA.

Purpose: A multiphysics simulation model was recently developed to capture major physical and mechanical processes of local drug transport and absorption kinetics of subcutaneously injected monoclonal antibody (mAb) solutions. To further explore the impact of individual drug attributes and tissue characteristics on the tissue biomechanical response and drug mass transport upon injection, sensitivity analysis was conducted and reported.

Method: Various configurations of injection conditions, drug-associated attributes, and tissue properties were simulated with the developed multiphysics model. Read More

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Methodology for comprehensive cell-level analysis of wound healing experiments using deep learning in MATLAB.

BMC Mol Cell Biol 2021 Jun 2;22(1):32. Epub 2021 Jun 2.

Institute for ImplantTechnology and Biomaterials e.V, Rostock, Germany.

Background: Endothelial healing after deployment of cardiovascular devices is particularly important in the context of clinical outcome. It is therefore of great interest to develop tools for a precise prediction of endothelial growth after injury in the process of implant deployment. For experimental investigation of re-endothelialization in vitro cell migration assays are routinely used. Read More

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A FEM-Based 2D Model for Simulation and Qualitative Assessment of Shot-Peening Processes.

Materials (Basel) 2021 May 24;14(11). Epub 2021 May 24.

Laboratory of Machine Elements & Machine Design, School of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.

Shot peening is one of the most favored surface treatment processes mostly applied on large-scale engineering components to enhance their fatigue performance. Due to the stochastic nature and the mutual interactions of process parameters and the partially contradictory effects caused on the component's surface (increase in residual stress, work-hardening, and increase in roughness), there is demand for capable and user-friendly simulation models to support the responsible engineers in developing optimal shot-peening processes. The present paper contains a user-friendly Finite Element Method-based 2D model covering all major process parameters. Read More

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Modeling of Heat Stress in Sows Part 2: Comparison of Various Thermal Comfort Indices.

Animals (Basel) 2021 May 21;11(6). Epub 2021 May 21.

College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China.

Heat stress has an adverse effect on the production performance of sows, and causes a large economic loss every year. The thermal environment index is an important indicator for evaluating the level of heat stress in animals. Many thermal indices have been used to analyze the environment of the pig house, including temperature and humidity index (THI), effective temperature (ET), equivalent temperature index of sows (ETIS), and enthalpy (H), among others. Read More

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Pursuit and evasion strategies in the predator-prey interactions of fishes.

Integr Comp Biol 2021 Jun 1. Epub 2021 Jun 1.

Department of Ecology and Evolutionary Biology, University of California, Irvine, 321 Steinhaus Hall, Irvine, 92697, CA, U.S.A.

Predator-prey interactions are critical to the biology of a diversity of animals. Although prey capture is determined by the direction, velocity, and timing of motion by both animals, it is generally unclear what strategies are employed by predators and prey to guide locomotion. Here we review our research on fishes that tests the pursuit strategy of predators and the evasion strategy of prey through kinematic measurements and agent-based models. Read More

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