How Compliance of Surfaces Affects Ankle Moment and Stiffness Regulation During Walking

Humans can regulate ankle moment and stiffness to cope with various surfaces during walking, while the effect of surfaces compliance on ankle moment and stiffness regulations remains unclear. In order to find the underlying mechanism, ten healthy subjects were recruited to walk across surfaces with different levels of compliance. Electromyography (EMG), ground reaction forces (GRFs), and three-dimensional reflective marker trajectories were recorded synchronously. Ankle moment and stiffness were estimated using an EMG-driven musculoskeletal model. Our results showed that the compliance of surfaces can affect both ankle moment and stiffness regulations during walking. When the compliance of surfaces increased, the ankle moment increased to prevent lower limb collapse and the ankle stiffness increased to maintain stability during the mid-stance phase of gait. Our work improved the understanding of gait biomechanics and might be instructive to sports surface design and passive multibody model development.

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Modeling and Simulation of Paraplegic Ambulation in a Reciprocating Gait Orthosis

Journal of Biomechanical Engineering ◽

10.1115/1.2794185 ◽

1995 ◽

Vol 117 (3) ◽

pp. 300-308 ◽

Cited By ~ 35

Author(s):

S. Tashman ◽

F. E. Zajac ◽

I. Perkash

Keyword(s):

Initial Conditions ◽

Model Development ◽

Three Dimensional ◽

The Body ◽

Upper Body ◽

Double Support ◽

Body Forces ◽

Reaction Forces ◽

Spinal Cord Injured ◽

Stimulation Of

We developed a three dimensional, four segment, eight-degree-of-freedom model for the analysis of paraplegic ambulation in a reciprocating gait orthosis (RGO). Model development was guided by experimental analysis of a spinal cord injured individual walking in an RGO with the additional assistance of arm crutches. Body forces and torques required to produce a dynamic simulation of the RGO gait swing phase were found by solving an optimal control problem to track the recorded kinematics and ground reaction forces. We found that high upper body forces are required, not only during swing but probably also during double support to compensate for the deceleration of the body during swing, which is due to the pelvic thrust necessary to swing the leg forward. Other simulations showed that upper body forces and body deceleration during swing can be reduced substantially by producing a ballistic swing. Functional neuromuscular stimulation of the hip musculature during double support would then be required, however, to establish the initial conditions needed in a ballistic swing.

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Unsteady Three-Dimensional Numerical Model Development for the Investigation of the Gas Jet Wiping Process on Flow Behaviors Near the Galvanizing Bath Surface

AISTech2019 Proceedings of the Iron and Steel Technology Conference ◽

10.33313/377/182 ◽

2019 ◽

Author(s):

F. Goodwin ◽

F. Ilinca ◽

K. Yu

Keyword(s):

Numerical Model ◽

Model Development ◽

Three Dimensional ◽

Gas Jet ◽

Bath Surface

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Deterministic Modeling of Water Entry and Drop of An Arbitrary Three-Dimensional Body - A Building Block for Stochastic Model Development

10.21236/ada626995 ◽

2001 ◽

Author(s):

Dick K. Yue ◽

Yuming Liu

Keyword(s):

Stochastic Model ◽

Building Block ◽

Model Development ◽

Three Dimensional ◽

Water Entry ◽

Deterministic Modeling

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Modeling and Assessment of the Produced Water Discharges from Offshore Petroleum Platforms

Water Quality Research Journal ◽

10.2166/wqrj.2007.032 ◽

2007 ◽

Vol 42 (4) ◽

pp. 303-310 ◽

Cited By ~ 7

Author(s):

Zhi Chen ◽

Lin Zhao ◽

Kenneth Lee ◽

Charles Hannath

Keyword(s):

Random Walk ◽

Produced Water ◽

Model Development ◽

Three Dimensional ◽

Monitoring Program ◽

Ecological Monitoring ◽

Numerical Approach ◽

Ocean Model ◽

Scale Model ◽

Water Stream

Abstract There has been a growing interest in assessing the risks to the marine environment from produced water discharges. This study describes the development of a numerical approach, POM-RW, based on an integration of the Princeton Ocean Model (POM) and a Random Walk (RW) simulation of pollutant transport. Specifically, the POM is employed to simulate local ocean currents. It provides three-dimensional hydrodynamic input to a Random Walk model focused on the dispersion of toxic components within the produced water stream on a regional spatial scale. Model development and field validation of the predicted current field and pollutant concentrations were conducted in conjunction with a water quality and ecological monitoring program for an offshore facility located on the Grand Banks of Canada. Results indicate that the POM-RW approach is useful to address environmental risks associated with the produced water discharges.

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Energies and Electric Dipole Moments of the Bound Vibrational States of HN2+ and DN2+

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20080873 ◽

2008 ◽

Vol 73 (6-7) ◽

pp. 873-897 ◽

Cited By ~ 8

Author(s):

Vladimír Špirko ◽

Ota Bludský ◽

Wolfgang P. Kraemer

Keyword(s):

Dipole Moment ◽

Nearest Neighbor ◽

Energy Surface ◽

Dipole Moments ◽

Three Dimensional ◽

Vibrational States ◽

Spacing Distribution ◽

Triatomic Molecules ◽

Vibrational Levels ◽

Different Levels

The adiabatic three-dimensional potential energy surface and the corresponding dipole moment surface describing the ground electronic state of HN2+ (Χ1Σ+) are calculated at different levels of ab initio theory. The calculations cover the entire bound part of the potential up to its lowest dissociation channel including the isomerization barrier. Energies of all bound vibrational and low-lying ro-vibrational levels are determined in a fully variational procedure using the Suttcliffe-Tennyson Hamiltonian for triatomic molecules. They are in close agreement with the available experimental numbers. From the dipole moment function effective dipoles and transition moments are obtained for all the calculated vibrational and ro-vibrational states. Statistical tools such as the density of states or the nearest-neighbor level spacing distribution (NNSD) are applied to describe and analyse general patterns and characteristics of the energy and dipole results calculated for the massively large number of states of the strongly bound HN2+ ion and its deuterated isotopomer.

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The ICON Single-Column Mode

Atmosphere ◽

10.3390/atmos12070906 ◽

2021 ◽

Vol 12 (7) ◽

pp. 906

Author(s):

Ivan Bašták Ďurán ◽

Martin Köhler ◽

Astrid Eichhorn-Müller ◽

Vera Maurer ◽

Juerg Schmidli ◽

...

Keyword(s):

Data Storage ◽

Model Development ◽

Computational Cost ◽

Three Dimensional ◽

Shallow Convection ◽

Modeling Framework ◽

Additional Tool ◽

Eddy Simulation ◽

Single Column ◽

Stratocumulus Clouds

The single-column mode (SCM) of the ICON (ICOsahedral Nonhydrostatic) modeling framework is presented. The primary purpose of the ICON SCM is to use it as a tool for research, model evaluation and development. Thanks to the simplified geometry of the ICON SCM, various aspects of the ICON model, in particular the model physics, can be studied in a well-controlled environment. Additionally, the ICON SCM has a reduced computational cost and a low data storage demand. The ICON SCM can be utilized for idealized cases—several well-established cases are already included—or for semi-realistic cases based on analyses or model forecasts. As the case setup is defined by a single NetCDF file, new cases can be prepared easily by the modification of this file. We demonstrate the usage of the ICON SCM for different idealized cases such as shallow convection, stratocumulus clouds, and radiative transfer. Additionally, the ICON SCM is tested for a semi-realistic case together with an equivalent three-dimensional setup and the large eddy simulation mode of ICON. Such consistent comparisons across the hierarchy of ICON configurations are very helpful for model development. The ICON SCM will be implemented into the operational ICON model and will serve as an additional tool for advancing the development of the ICON model.

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Ground Reaction Forces of Dressage Horses Performing the Piaffe

Animals ◽

10.3390/ani11020436 ◽

2021 ◽

Vol 11 (2) ◽

pp. 436 ◽

Cited By ~ 1

Author(s):

Hilary Mary Clayton ◽

Sarah Jane Hobbs

Keyword(s):

Coefficient Of Variation ◽

Three Dimensional ◽

Individual Variability ◽

The Other ◽

Ground Reaction Forces ◽

High Coefficient ◽

Reaction Forces

The piaffe is an artificial, diagonally coordinated movement performed in the highest levels of dressage competition. The ground reaction forces (GRFs) of horses performing the piaffe do not appear to have been reported. Therefore, the objective of this study was to describe three-dimensional GRFs in ridden dressage horses performing the piaffe. In-ground force plates were used to capture fore and hindlimb GRF data from seven well-trained dressage horses. Peak vertical GRF was significantly higher in forelimbs than in the hindlimbs (7.39 ± 0.99 N/kg vs. 6.41 ± 0.64 N/kg; p < 0.001) with vertical impulse showing a trend toward higher forelimb values. Peak longitudinal forces were small with no difference in the magnitude of braking or propulsive forces between fore and hindlimbs. Peak transverse forces were similar in magnitude to longitudinal forces and were mostly directed medially in the hindlimbs. Both the intra- and inter-individual variability of longitudinal and transverse GRFs were high (coefficient of variation 25–68%). Compared with the other diagonal gaits of dressage horses, the vertical GRF somewhat shifted toward the hindlimbs. The high step-to-step variability of the horizontal GRF components is thought to reflect the challenge of balancing on one diagonal pair of limbs with no forward momentum.

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Hereditary Optic Neuropathies: Induced Pluripotent Stem Cell-Based 2D/3D Approaches

Genes ◽

10.3390/genes12010112 ◽

2021 ◽

Vol 12 (1) ◽

pp. 112

Author(s):

Marta García-López ◽

Joaquín Arenas ◽

M. Esther Gallardo

Keyword(s):

Stem Cell ◽

Retinal Ganglion Cells ◽

Pluripotent Stem Cell ◽

Ganglion Cells ◽

Genetic Disorders ◽

Three Dimensional ◽

Induced Pluripotent Stem Cell ◽

Underlying Mechanism ◽

Retinal Ganglion ◽

Induced Pluripotent

Inherited optic neuropathies share visual impairment due to the degeneration of retinal ganglion cells (RGCs) as the hallmark of the disease. This group of genetic disorders are caused by mutations in nuclear genes or in the mitochondrial DNA (mtDNA). An impaired mitochondrial function is the underlying mechanism of these diseases. Currently, optic neuropathies lack an effective treatment, and the implementation of induced pluripotent stem cell (iPSC) technology would entail a huge step forward. The generation of iPSC-derived RGCs would allow faithfully modeling these disorders, and these RGCs would represent an appealing platform for drug screening as well, paving the way for a proper therapy. Here, we review the ongoing two-dimensional (2D) and three-dimensional (3D) approaches based on iPSCs and their applications, taking into account the more innovative technologies, which include tissue engineering or microfluidics.

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