Mechanical power input from buoyancy and wind to the circulation in an ocean model

2012 ◽  
Vol 39 (13) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. A. Saenz ◽  
A. M. Hogg ◽  
G. O. Hughes ◽  
R. W. Griffiths
Keyword(s):  
Power Input ◽  
Ocean Model ◽  
Mechanical Power

scholarly journals Flagellar energetics from high-resolution imaging of beating patterns in tethered mouse sperm

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ashwin Nandagiri ◽  
Avinash Satish Gaikwad ◽  
David L Potter ◽  
Reza Nosrati ◽  
Julio Soria ◽  
...  
Keyword(s):  
High Resolution ◽  
Power Input ◽  
Mechanical Power ◽  
Secretory Proteins ◽  
Ion Channel Regulation ◽  
Mouse Sperm ◽  
Energy Flows ◽  
Internal Dissipation ◽  
Resolution Imaging ◽  
Proper Orthogonal

We demonstrate a technique for investigating the energetics of flagella or cilia. We record the planar beating of tethered mouse sperm at high-resolution. Beating waveforms are reconstructed using Proper Orthogonal Decomposition of the centerline tangent-angle profiles. Energy conservation is employed to obtain the mechanical power exerted by the dynein motors from the observed kinematics. A large proportion of the mechanical power exerted by the dynein motors is dissipated internally by the motors themselves. There could also be significant dissipation within the passive structures of the flagellum. The total internal dissipation is considerably greater than the hydrodynamic dissipation in the aqueous medium outside. The net power input from the dynein motors in sperm from Crisp2-knockout mice is significantly smaller than in wildtype samples, indicating that ion-channel regulation by cysteine-rich secretory proteins (CRISPs) controls energy flows powering the axoneme.

scholarly journals Consequences of load carrying by birds during short flights are found to be behavioral and not energetic

2002 ◽  
Vol 283 (1) ◽  
pp. R249-R256 ◽  
Author(s):  
Robert L. Nudds ◽  
David M. Bryant
Keyword(s):  
Body Mass ◽  
Power Input ◽  
Mechanical Power ◽  
Zebra Finches ◽  
Mass Loading ◽  
Metabolic Power ◽  
Additional Mass ◽  
Reduced Body ◽  
Mechanical Power Output ◽  
Load Carrying

The doubly-labeled water technique and video were used to measure the effect of mass loading on energy expenditure and takeoff performance in zebra finches, Taeniopygia guttata, that were making routine (nonalarm) short flights. Finches that carried 27% additional mass did not expend more energy during flight than unloaded controls. Carrying additional mass, however, led to a reduced body mass and a decreased velocity during takeoffs (by 12%). Calculations of instantaneous mechanical power indicated that energy expended by unloaded and loaded finches at takeoff was similar, due to the observed decrease in velocity by mass-loaded finches and a lowering of their body mass. During routine short flights, zebra finches appear to maintain their metabolic power input and mechanical power output regardless of mass loading. Here, the costs of carrying additional mass during routine short flights were revealed to be behavioral and not energetic.

Mechanical and propelling efficiency in swimming derived from exercise using a laboratory-based whole-body swimming ergometer

2012 ◽  
Vol 113 (4) ◽  
pp. 584-594 ◽  
Author(s):  
Paola Zamparo ◽  
Ian L. Swaine
Keyword(s):  
Power Output ◽  
Power Input ◽  
Mechanical Power ◽  
Whole Body ◽  
Metabolic Power ◽  
Exact Simulation ◽  
Mechanical Power Output ◽  
Propelling Efficiency ◽  
Overall Efficiency ◽  
Active Drag

Determining the efficiency of a swimming stroke is difficult because different “efficiencies” can be computed based on the partitioning of mechanical power output (Ẇ) into its useful and nonuseful components, as well as because of the difficulties in measuring the forces that a swimmer can exert in water. In this paper, overall efficiency (ηO = ẆTOT/Ė, where ẆTOT is total mechanical power output, and Ė is overall metabolic power input) was calculated in 10 swimmers by means of a laboratory-based whole-body swimming ergometer, whereas propelling efficiency (ηP = ẆD/ẆTOT, where ẆD is the power to overcome drag) was estimated based on these values and on values of drag efficiency (ηD = ẆD/Ė): ηP = ηD/ηO. The values of ηD reported in the literature range from 0.03 to 0.09 (based on data for passive and active drag, respectively). ηO was 0.28 ± 0.01, and ηP was estimated to range from ∼0.10 (ηD = 0.03) to 0.35 (ηD = 0.09). Even if there are obvious limitations to exact simulation of the whole swimming stroke within the laboratory, these calculations suggest that the data reported in the literature for ηO are probably underestimated, because not all components of ẆTOT can be measured accurately in this environment. Similarly, our estimations of ηP suggest that the data reported in the literature are probably overestimated.

scholarly journals Empirical evidence of a fluctuation theorem for the wind mechanical power input into the ocean

2021 ◽  
Vol 28 (3) ◽  
pp. 371-378
Author(s):  
Achim Wirth ◽  
Bertrand Chapron
Keyword(s):  
Temporal Distribution ◽  
Power Input ◽  
Fluctuation Theorem ◽  
Ocean Currents ◽  
Ocean Dynamics ◽  
Mechanical Power ◽  
Western Boundary ◽  
Strong Constraint ◽  
Temporal Averaging ◽  
Recirculation Area

Abstract. Ocean dynamics is predominantly driven by the shear stress between the atmospheric winds and ocean currents. The mechanical power input to the ocean is fluctuating in space and time and the atmospheric wind sometimes decelerates the ocean currents. Building on 24 years of global satellite observations, the input of mechanical power to the ocean is analysed. A fluctuation theorem (FT) holds when the logarithm of the ratio between the occurrence of positive and negative events, of a certain magnitude of the power input, is a linear function of this magnitude and the averaging period. The flux of mechanical power to the ocean shows evidence of a FT for regions within the recirculation area of the subtropical gyre but not over extensions of western boundary currents. A FT puts a strong constraint on the temporal distribution of fluctuations of power input, connects variables obtained with different lengths of temporal averaging, guides the temporal down- and up-scaling and constrains the episodes of improbable events.

Aeration of liquids in a vessel equipped with multistage impellers

1985 ◽  
Vol 50 (12) ◽  
pp. 2863-2872 ◽  
Author(s):  
Václav Machoň ◽  
Jiří Vlček
Keyword(s):  
Input Data ◽  
Power Input ◽  
Experimental Results ◽  
Simple Equation ◽  
Mechanical Power ◽  
System A ◽  
Liquid Dispersion ◽  
Liquid Depth ◽  
Turbine Impeller ◽  
Tank Diameter

The paper deals with the influence of the number of impellers and the mode of aeration on the mechanical power input in a stirred gas-liquid dispersion using two impellers on the same shaft. Gas has been supplied either under the lower impeller or under both impellers. The power input was measured in the water-air system. A six-blade turbine impeller of the Rushton type and/or impellers with six inclined blades (with downward or upward pumping effect) were used. Experimental results have been obtained for a single impeller in a tank where the depth of liquid was equal to the tank diameter, and for different combinations of two impellers located on a single shaft where the distance between the impellers was equal to the tank diameter and the liquid depth was twice this diameter. It has been found that the power input data for the two-impeller system of two turbines can be correlated adequately by a simple equation. An estimate was made of the amount of gas supplied below the lower impeller which was transported into the region of the upper impeller.

scholarly journals Dynamical Potential Energy: A New Approach to Ocean Energetics

2013 ◽  
Vol 43 (2) ◽  
pp. 457-476 ◽  
Author(s):  
Fabien Roquet
Keyword(s):  
Potential Energy ◽  
General Circulation ◽  
Circulation Model ◽  
Power Input ◽  
Ocean Model ◽  
Conservation Of Energy ◽  
Available Potential Energy ◽  
Power Inputs ◽  
Ocean Energetics ◽  
Dynamical Potential

Abstract The concept of available potential energy is supposed to indicate which part of the potential energy is available to transform into kinetic energy. Yet it is impossible to obtain a unique definition of available potential energy for the real ocean because of nonlinearities of the equation of state, rendering its usefulness largely hypothetical. In this paper, the conservation of energy is first reformulated in terms of horizontal anomalies of density and pressure for a simplified ocean model using the Boussinesq and hydrostatic approximations. This framework introduces the concept of “dynamical potential energy,” defined as the horizontal anomaly of potential energy, to replace available potential energy. Modified conservation equations are derived that make it much simpler to identify oceanic power input by buoyancy and mechanical forces. Closed budgets of energy are presented for idealized circulations obtained with a general circulation model, comparing spatial patterns of power inputs generated by wind and thermal forcings. Finally, a generalization of the framework to compressible fluids is presented, opening the way to applications in atmosphere energetics.

scholarly journals The changes in power requirements and muscle efficiency during elevated force production in the fruit fly Drosophila melanogaster.

1997 ◽  
Vol 200 (7) ◽  
pp. 1133-1143 ◽  
Author(s):  
F O Lehmann ◽  
M H Dickinson
Keyword(s):  
Drosophila Melanogaster ◽  
Power Output ◽  
Force Production ◽  
Fruit Fly ◽  
Reynolds Numbers ◽  
Power Input ◽  
Mechanical Power ◽  
Total Power ◽  
Mechanical Power Output ◽  
The Cost

The limits of flight performance have been estimated in tethered Drosophila melanogaster by modulating power requirements in a 'virtual reality' flight arena. At peak capacity, the flight muscles can sustain a mechanical power output of nearly 80 W kg-1 muscle mass at 24 degrees C, which is sufficient to generate forces of approximately 150% of the animal's weight. The increase in flight force above that required to support body weight is accompanied by a rise in wing velocity, brought about by an increase in stroke amplitude and a decrease in stroke frequency. Inertial costs, although greater than either profile or induced power, would be minimal with even modest amounts of elastic storage, and total mechanical power energy should be equivalent to aerodynamic power alone. Because of the large profile drag expected at low Reynolds numbers, the profile power was approximately twice the induced power at all levels of force generation. Thus, it is the cost of overcoming drag, and not the production of lift, that is the primary requirement for flight in Drosophila melanogaster. By comparing the estimated mechanical power output with respirometrically measured total power input, we determined that muscle efficiency rises with increasing force production to a maximum of 10%. This change in efficiency may reflect either increased crossbridge activation or a favorable strain regime during the production of peak forces.

scholarly journals Agricultural Mechanization Status for Some Crops in Irrigated Sector in River Nile State, Sudan

2019 ◽  
Vol 11 (13) ◽  
pp. 127
Author(s):  
Alaeldin M. E. Awadalla ◽  
Kang Sukwon ◽  
Kwon Taek-Ryoun ◽  
S. A. Haider
Keyword(s):  
Power Input ◽  
Fertilizer Application ◽  
Mechanical Power ◽  
Total Power ◽  
Irrigated Agriculture ◽  
Baseline Survey ◽  
River Nile ◽  
Land Preparation ◽  
Agricultural Mechanization ◽  
Tillage Operation

Agricultural mechanization and it is impact on agricultural productivity was studied by many authors in different areas in the world. Irrigated agriculture in the Sudan, have played a significant role in expanding agricultural mechanization, and the major mechanized operation is the land preparation, operations such as planting, spraying, fertilizer application, mechanical weeding and harvesting are still largely carried out manually. A baseline survey on mechanization status was implemented in River Nile State, focuses on mechanization status for production of wheat as strategic crop, legumes as food crops, onion and alfalfa as cash crops in smallholder farms. The analysis of respondents answers show that tillage operation has the high percent (90.5-93.3%) of mechanical power among other operations for production of the selected crops, where wheat has considerable percent of using mechanical power in sowing and harvesting operations compare to the three rest crops. For legumes and alfalfa broadcasting of seeds for sowing and cutting and binding at harvest operations, still manual activity prevailing, where for onion transplanting are 100% carried out manually.The mechanization level range between 0.2-0.58, which reflect the less number of tractors to the cultivated areas in the state. Concerning the mechanization index as the ratio of mechanical power to the total power input in term of MJ/ha for each crop range from 0.03- 0.07, shows that manual and animal power still exerted to produce such crops.

scholarly journals Flagellar energetics from high-resolution imaging of beating patterns in tethered mouse sperm

2020 ◽  
Author(s):  
Ashwin Nandagiri ◽  
Avinash S. Gaikwad ◽  
David L. Potter ◽  
Reza Nosrati ◽  
Julio Soria ◽  
...  
Keyword(s):  
High Resolution ◽  
High Speed ◽  
Power Input ◽  
Internal Resistance ◽  
Mechanical Power ◽  
Secretory Proteins ◽  
Mouse Sperm ◽  
Kirchhoff Rod ◽  
Internal Dissipation ◽  
Processing Techniques

AbstractWhile much is known about the microstructure of sperm flagella, the mechanisms behind the generation of flagellar beating patterns by the axoneme are still not fully understood. We demonstrate a technique for investigating the energetics of flagella or cilia. We record the planar beating of tethered wildtype and Crisp2-knockout mouse sperm at high-speed and high-resolution and extract centerlines using digital image processing techniques. We accurately reconstruct beating waveforms using a Chebyshev-polynomial based Proper Orthogonal Decomposition of the centerline tangent-angle profiles. External hydrodynamic forces and the internal resistance from the passive flagellar material are calculated from the observed kinematics of the beating patterns using a Soft, Internally-Driven Kirchhoff-Rod (SIDKR) model. Energy conservation is employed to further compute the flagellar energetics. We thus obtain the distribution of mechanical power exerted by the dynein motors without any further assumptions about mechanisms regulating axonemal function. We find that, in both the mouse genotypes studied, a large proportion of the mechanical power exerted by the dynein motors is dissipated internally, within the passive structures of the flagellum and by the motors themselves. This internal dissipation is considerably greater than the hydrodynamic dissipation in the aqueous medium outside. The net power input from the dynein motors in sperm from Crisp2-knockout mice is significantly smaller than in corresponding wildtype samples. The reduced power is correlated with slower beating and smaller amplitudes. These measurements of flagellar energetics indicate that the ion-channel regulating cysteine-rich secretory proteins (CRISPs) may also be involved in regulating mammalian sperm motility.

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