Comparison of mechanical work done during walking by different calculation methods

2021 ◽  
Vol 90 ◽  
pp. 246-247
Author(s):  
K. Shimoda ◽  
H. Okada
Keyword(s):  
Mechanical Work ◽  
Calculation Methods ◽  
Work Done

scholarly journals Crystallization of Polymers under the Influence of an External Force Field

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2078
Author(s):  
Rajdeep Singh Payal ◽  
Jens-Uwe Sommer
Keyword(s):  
External Force ◽  
Melting Behavior ◽  
Mechanical Work ◽  
Stem Length ◽  
Heat Of Fusion ◽  
Strong Increase ◽  
Lamellar Thickness ◽  
Equilibrium System ◽  
External Force Field ◽  
Work Done

We simulated the crystallization and melting behavior of entangled polymer melts using molecular dynamics where each chain is subject to a force dipole acting on its ends. This mimics the deformation of chains in a flow field but represents a well-defined equilibrium system in the melt state. Under weak extension within the linear response of the chains, the mechanical work done on the system is about two orders of magnitude smaller as compared with the heat of fusion. As a consequence, thermodynamic and simple arguments following the secondary nucleation model predict only small changes of the crystalline phase. By contrast, an increase of the stem length up to a factor of two is observed in our simulations. On the other hand, the lamellar thickening induced by the external force is proportional to the increase of the entanglement length in the melt prior to crystallization as measured by the primitive path method. While the mechanical work done on the system is only a small perturbation for thermodynamics of polymer crystallization, the change of the primitive path is large. This suggests that a strong increase in the lamellar thickness induced, by external deformation, a topological rather than a thermodynamic origin.

scholarly journals The theory of the chain fountain revisited

2021 ◽  
Vol 2090 (1) ◽  
pp. 012166
Author(s):  
Dragos-Victor Anghel
Keyword(s):  
Energy Transfer ◽  
Kinetic Energy ◽  
Significant Role ◽  
Mechanical Work ◽  
Scientific Consensus ◽  
Energy And Momentum ◽  
Work Done

Abstract We analyze the chain fountain effect-the chain siphoning when falling from a container onto the floor. We argue that the main reason for this effect is the inertia of the chain, whereas the momentum received by the beads of the chain from the bottom of the container (typically called “kicks”) plays no significant role. The inertia of the chain leads to an effect similar to pulling the chain over a pulley placed up in the air, above the container. In another model (the so called “scientific consensus”), it was assumed that up to half of the mechanical work done by the tension in the chain may be wasted when transformed into kinetic energy during the pickup process. This prevented the chain to rise unless the energy transfer in the pickup process is improved by the “kicks” from the bottom of the container. Here we show that the “kicks” are unnecessary and both, energy and momentum are conserved-as they should be, in the absence of dissipation-if one properly considers the tension and the movement of the chain. By doing so, we conclude that the velocity acquired by the chain is high enough to produce the fountain effect. Simple experiments validate our model and certain configurations produce the highest chain fountain, although “kicks” are impossible.

scholarly journals External mechanical work done during the acceleration stage of maximal sprint running and its association with running performance

2019 ◽  
Vol 222 (5) ◽  
pp. jeb189258 ◽  
Author(s):  
Akifumi Matsuo ◽  
Mirai Mizutani ◽  
Ryu Nagahara ◽  
Testuo Fukunaga ◽  
Hiroaki Kanehisa
Keyword(s):  
Mechanical Work ◽  
Running Performance ◽  
Sprint Running ◽  
Work Done

External mechanical work done by each leg during walking in stroke patients

2006 ◽  
Vol 39 ◽  
pp. S171-S172
Author(s):  
G.G. Stoquart ◽  
C. Detrembleur ◽  
T.M. Lejeune
Keyword(s):  
Mechanical Work ◽  
Stroke Patients ◽  
Work Done

The absorption of work by a muscle stretched during a single twitch or a short tetanus

1951 ◽  
Vol 139 (894) ◽  
pp. 86-104 ◽  
Keyword(s):  
Chemical Synthesis ◽  
Elastic Energy ◽  
Physical System ◽  
Active Phase ◽  
Mechanical Work ◽  
Significant Part ◽  
Chemical System ◽  
Relaxation Phase ◽  
Single Twitch ◽  
Work Done

When a stimulated muscle is stretched fairly quickly during the active phase of contraction, it resists strongly and mechanical work must be done in stretching it. What happens to this work? If the length to which the muscle is stretched is not too great no significant part of the work remains as mechanical (elastic) energy after the muscle has relaxed. The total heat produced up to the end of relaxation is greater than it would have been had no work been performed on the muscle, but the excess is too small to account for all the work done. It is concluded that the missing work, about half of the whole, is absorbed, presumably as chemical energy. If a stretch is applied entirely during the relaxation phase, when activity is over but tension is still present, the whole of the work performed reappears as heat. If the view is accepted that the missing work is absorbed in chemical synthesis, it appears that the physical system responsible for mechanical work is reversibly coupled, during the active state, with a chemical system providing the necessary energy; and that this coupling is broken when activity passes off. Other possible hypotheses, however, are discussed. The application to ordinary muscular movement is referred to.

scholarly journals Assessment of esophageal body peristaltic work using functional lumen imaging probe panometry

2020 ◽  
Author(s):  
Shashank Acharya ◽  
Sourav Halder ◽  
Dustin A Carlson ◽  
Wenjun Kou ◽  
Peter J. Kahrilas ◽  
...  
Keyword(s):  
Physiological State ◽  
Distal Segment ◽  
Work Capacity ◽  
Mechanical Work ◽  
Lumen Area ◽  
Imaging Probe ◽  
Functional Lumen Imaging Probe ◽  
Using Data ◽  
Secondary Peristalsis ◽  
Work Done

Background: The goal of this study was to conceptualize and compute measures of "mechanical work" done by the esophagus using data generated during functional lumen imaging probe (FLIP) panometry and compare work done during secondary peristalsis among patients and controls. Methods: 85 individuals were evaluated with a 16 cm FLIP during sedated endoscopy, including controls (n=14), achalasia subtypes I, II and III (n=15, each), GERD (n=13), EoE (n=9) and SSc (n=5). The FLIP catheter was positioned to have its distal segment straddling the EGJ during stepwise distension. Two metrics of work were assessed: "active work" (bag volumes ≤ 40 mL where contractility generates changes in lumen area) and "work capacity" (bag volumes ≥ 60 mL when contractility cannot alter the lumen area). Results: Controls showed median (IQR) of 7.3 (3.6-9.2) mJ of active work and 268.6 (225.2-332.3) mJ of work capacity. All achalasia subtypes, GERD, and SSc showed lower active work done than controls (p≤0.003). Achalasia subtypes I, II, GERD, and SSc had lower work capacity compared to controls (p<0.001, 0.004, 0.04, and 0.001 respectively). Work capacity was similar between controls, achalasia type III and EoE. Conclusions Mechanical work of the esophagus differs between healthy controls and patient groups with achalasia, EoE, SSc and GERD. Further studies are needed to fully explore the utility of this approach, but these work metrics would be valuable for device design (artificial esophagus), to measure the efficacy of peristalsis, to gauge the physiological state of the esophagus, and comment on its pumping effectiveness.

Mechanical work of breathing derived from rib cage and abdominal V-P partitioning

1976 ◽  
Vol 41 (5) ◽  
pp. 752-763 ◽  
Author(s):  
M. D. Goldman ◽  
G. Grimby ◽  
J. Mead
Keyword(s):  
Chest Wall ◽  
Work Of Breathing ◽  
Mechanical Work ◽  
Quiet Breathing ◽  
Campbell Diagram ◽  
Rib Cage ◽  
Abdominal Musculature ◽  
Work Done ◽  
Inspiratory Work

Estimates of the mechanical work of breathing derived from measurements of separate rib cage and abdominal volume displacements, each plotted against transthoracic pressure, include the elastic cost of chest wall distortion which may occur during breathing. Inspiratory work is partitioned between the diaphragm and the rib cage musculature by adding measurements of transabdominal pressure. The mechanical work of breathing derived from separate rib cage and abdominal volume-pressure (V-P) tracings (the sum of work done by the diaphragm, rib cage, and abdominal musculature) is compared with ventilatory work estimated from the Campbell diagram (which does not include any distortional work). During resting breathing the two estimates are closely comparable, consistent with little or no distortion of the chest wall during quiet breathing. As ventilation increases, the estimate developed from rib cage and abdominal tracings reveals systematically greater mechanical work than is estimated from the Campbell diagram, consistent with distortion of the chest wall from the relaxed thoracoabdominal configuration at higher levels of ventilation. At ventilations achieved during exercise, the Campbell diagram may underestimate the work of breathing by up to 25%.

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