scholarly journals Strain Evolution and Instability of an Anticyclonic Eddy From a Laboratory Experiment

2021 ◽  
Vol 8 ◽  
Author(s):  
Guoqing Han ◽  
Changming Dong ◽  
Jingsong Yang ◽  
Joel Sommeria ◽  
Alexandre Stegner ◽  
...  
Keyword(s):  
Laboratory Experiment ◽  
Rotation Speed ◽  
Anticyclonic Eddy ◽  
Experimental Results ◽  
Rotating Platform ◽  
Decay Period ◽  
Strain Evolution ◽  
Mature Phase ◽  
Inertial Instability ◽  
Underlying Mechanisms

Using the 13 m diameter LEGI-Coriolis rotating platform, the evolution processes of a generated anticyclonic eddy throughout its lifecycle are analyzed. Experimental results have shown that the eddy lasted for approximately 3T0, where T0 is the rotating period of 90 s. After T = 0.3T0, the eddy enters its mature phase, whereby following this event, eddy intensity slowly decreases from its maximum rotation speed. By T = 2.6T0, the eddy enters a stage of rapid weakening. In its decay period, two underlying mechanisms for this decay have been identified as inertial instability and eddy–eddy interactions.

scholarly journals Self-Governance in Generalized Exchange. A Laboratory Experiment on the Structural Embeddedness of Peer Punishment

Games ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 50
Author(s):  
Georg Kanitsar
Keyword(s):  
Laboratory Experiment ◽  
Public Good ◽  
Experimental Evidence ◽  
Experimental Results ◽  
Social Cooperation ◽  
The Public ◽  
Norm Enforcement ◽  
Structural Setting ◽  
Structural Embeddedness ◽  
Generalized Exchange

Peer punishment is widely lauded as a decentralized solution to the problem of social cooperation. However, experimental evidence of its effectiveness primarily stems from public good structures. This paper explores peer punishment in another structural setting: a system of generalized exchange. In a laboratory experiment, a repeated four-player prisoner’s dilemma is arranged either in a public good structure or in a circular network of generalized exchange. The experimental results demonstrate that the merits of peer punishment do not extend to generalized exchange. In the public good, peer punishment was primarily altruistic, was sensitive to costs, and promoted cooperation. In generalized exchange, peer punishment was also altruistic and relatively frequent, but did not increase cooperation. While the dense punishment network underlying the public good facilitates norm enforcement, generalized exchange decreases control over norm violators and reduces the capacity of peer punishment. I conclude that generalized exchange systems require stronger forms of punishment to sustain social cooperation.

scholarly journals Perception of Vestibular Sensation During Turning Operation of Construction Machine

2021 ◽  
Vol 33 (3) ◽  
pp. 599-603
Author(s):  
Koji Okuda ◽  
◽  
Youjirou Ohbatake ◽  
Daisuke Kondo
Keyword(s):  
Remote Control ◽  
Laboratory Experiment ◽  
Visual Information ◽  
Experimental Results ◽  
Work Efficiency ◽  
Turning Operation ◽  
Lack Of Information ◽  
Somatosensory Information ◽  
Construction Machine

A major challenge in remote control is the reduction in work efficiency compared with on-board operation. The factors of reduction in work efficiency include a lack of information (information such as perspective, realistic sensation, vibration, and sound) compared to on-board operations. One of the factors is the lack of vestibular/somatosensory information regarding rotation. To clarify the effect of the presence of input of vestibular/somatosensory information regarding rotation on the worker’s operation, we conducted a basic laboratory experiment of a horizontal turning operation. The experimental results indicate that a response appropriate for the input of information regarding rotation can be made only with visual information; however, the reaction is delayed in the case without the input of information regarding rotation in comparison with a case with the input of information regarding rotation.

Experimental Research on Rotating Skimmer

2003 ◽  
Author(s):  
Minoru Chino ◽  
Kenji Takizawa ◽  
Takashi Yabe
Keyword(s):  
Experimental Research ◽  
Rotational Speed ◽  
Rotation Speed ◽  
Experimental Results ◽  
Injection System ◽  
Benchmark Test ◽  
Injection Speed ◽  
Structure Interaction ◽  
Wide Range ◽  
Computer Codes

This paper provides the experimental results on skimmer and gives some detailed information useful for benchmark test of computer codes that are now able to simulate the fluid-structure interaction. For this purpose, we specially designed the injection system that imposes reproducible rotational speed and injection speed on the skipper. The effect of rotation is discussed by changing rotation speed in a wide range.

Lubricated Friction of Rubber. III. Components of Friction in Mating Surfaces

1968 ◽  
Vol 41 (4) ◽  
pp. 854-861 ◽  
Author(s):  
E. P. Percarpio ◽  
E. M. Bevilacqua
Keyword(s):  
Laboratory Experiment ◽  
Frictional Resistance ◽  
Experimental Results ◽  
Radius Of Curvature ◽  
Critical Limit ◽  
Friction Coefficients ◽  
Resistance To Sliding ◽  
Wet Friction ◽  
Abrasive Friction ◽  
Local Pressures

Abstract Friction is usually discussed in terms of contributions from two processes: deformation and adhesion. This terminology has been retained in discussions of lubricated friction of rubber although there is not apparent any clear mechanism by which adhesion might occur. Our study of wet friction leads us to suggest that the components making up frictional resistance to sliding might more appropriately be referred to as deformation and abrasive components. On this basis, there is an obvious mechanism for both processes, and some of the disagreements about interpretation of certain experimental results may be resolved. The basis for our interpretation is implicit in the literature but was originally expressed somewhat tentatively and has not been restated in recent discussions. Greenwood and Tabor pointed out that hysteretic losses make an important contribution to friction of rubber sliding on a lubricated surface and that this contribution is independent of asperity size or distribution so long as only the asperities support the load and the radius of curvature at the asperity tip is above a critical limit which is remarkably low. Further, the experiments of Sabey showed that it was difficult to obtain coefficients higher than 0.4 with spherical sliders. Mean average local pressures high enough to give high friction coefficients could be obtained only with sharp asperities. In the laboratory experiment these were cones. Greenwood and Tabor found that with these damage to the rubber becomes visible at just the semiangle at which the coefficient began to rise abruptly (Figure 1). It is entirely reasonable to call the process causing this damage abrasive friction.

scholarly journals Design and Experiment of the Buckwheat Hill-Drop Planter Hole Forming Device

Agriculture ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1085
Author(s):  
Yu Chen ◽  
Yuming Cheng ◽  
Jun Chen ◽  
Zhiqi Zheng ◽  
Chenwei Hu ◽  
...  
Keyword(s):  
Rotation Speed ◽  
Simulation Analysis ◽  
Rotation Axis ◽  
Wire Diameter ◽  
Experimental Results ◽  
Pressure Plate ◽  
Original Length ◽  
Calculation Results ◽  
Multi Body ◽  
The Hill

The hole forming device is an important element of the buckwheat hill-drop planter, and its design level directly affects the seeding quality of the hill-drop planter. A hole forming device with a duckbill structure is widely used in hill-drop planters for wheat, cotton, peanuts, etc. According to the requirements of buckwheat seeding operations, this study designs the components of the duckbill hole forming device. It is determined that the duckbill upper jaw length is 65 mm, the duckbills number is 10, the pressure plate on the spring side length is 90 mm, the duckbill opening size is 8.79 mm, and the duckbill effective opening time is 0.1 s. Through co-simulation analysis of discrete element software EDEM (DEM-Solutions, Edinburgh, United Kingdom) and multi-body dynamics software RecurDyn (FunctionBay, Inc., Seongnam-si, South Korea), it is measured that when the pressure plate on the spring side is directly below the rotation axis of the dibber wheel, the spring compression is 33.3 mm, the pressure on the pressure plate is 95–102.6 N, and the contact time of a single duckbill with the soil is 0.2 s at a speed of 40 r/min. Based on the results of the design and simulation analysis, the large end diameter, small end diameter, original length and wire diameter of the duckbill spring are 36 mm, 26 mm, 60 mm, and 1.8 mm, respectively. An experimental bench for the seeding wheel of a buckwheat hill-drop planter was built, and three wire diameter duckbill springs of 1.6 mm, 1.8 mm and 2.0 mm were tested to verify the simulation and calculation results. The experimental results show that the optimal wire diameter of the duckbill spring is 1.8 mm. Finally, a single factor experiment of the dibber wheel rotation speed was carried out. The experimental results show that when the rotation speed of the dibber wheel is 40–65 r/min, the seeding qualification rate, seeding void hole rate and seeding damage rate of the buckwheat hill-drop planter are ≥85.3%, 0, and <0.3%, respectively. This study provides a basis and reference for the hole forming device design of a buckwheat hill-drop planter.

Mixing in a Rotating Micro-Channel

2010 ◽  
Author(s):  
Wallace Woon-Fong Leung ◽  
Yong Ren
Keyword(s):  
Rotation Speed ◽  
Rectangular Cross Section ◽  
Cross Flow ◽  
Maximum Effect ◽  
Large Radius ◽  
Micro Channel ◽  
Common Channel ◽  
Rotating Platform ◽  
Channel Lengths ◽  
Rotating Channel

Mixing of liquids in rotating micro-channel is studied as it has important applications in portable diagnostic devices in rotating lab-on-a-chip. The latter utilizes rotation to pump liquid samples and reagents, and to actuate mixing between different liquids during transport in the channel using secondary flow generated from rotation. Experiments have been carried out on a rotating platform wherein two liquids are directed from their respective reservoirs through small capillaries into a common channel when the centrifugal force generated from rotation exceeds the capillary force which initially traps the liquid in their respective reservoirs. As two liquids are combined to flow through a common channel directed radially outward, Coriolis acceleration which is proportional to the rotation speed and relative radial velocity of the fluids, induces a tangential acceleration and thus velocity component that directs opposite to the direction of rotation. As this cross-flow, predominantly with maximum effect at the center of the channel, intercepts the far wall (i.e. pressure face) it splits up into two streams returning the flow back to the leading (in direction of rotation) face of the channel. This produces two main vortices/circulations for the channel and smaller vortices at the four corners for a channel with a rectangular cross-section. These vortices specifically the two main vortices are responsible for mixing of momentum, mass and energy in the cross-flow direction as the throughflow moves radially outward along the channel from small to a large radius. In the reference frame of the rotating channel, the combination of throughflow and crossflow results in two cork screw-shaped helical flow pattern streaming down the rotating channel. Connected with a microscope to view in details of the mixing in a small area, a rotating camera, mounted to the rotating platform, is used to take video of the mixing at various locations along a radial channel 30-mm in length and 1 mm width. This test is repeated for other observation locations along the channel. All the tests under identical rotation speed are grouped together to provide a full record of the mixing in the entire channel. These results can also be examined as mixing under same rotation speed but different channel lengths. Obviously, increasing length enhances mixing especially at small channel lengths under 5–10 mm. However, between 10–30 mm downstream mixing is diminished. It was also found that higher rotation speed can indeed produces better mixing with a modest increase.

scholarly journals Research Concerning the Correlations Between Some Experimental Results in the Case of a Sucker Rod Pumping Installation

2018 ◽  
Vol 69 (11) ◽  
pp. 3060-3063
Author(s):  
Dorin Badoiu ◽  
Georgeta Toma
Keyword(s):  
Computer Program ◽  
Rotation Speed ◽  
Experimental Results ◽  
Programming Environment ◽  
Sucker Rod ◽  
Pumping Unit ◽  
Polished Rod

In the paper are analyzed the correlations between the experimental results obtained for the instantaneous rotation speed of the cranks shaft of a conventional sucker rod pumping installation and the speed and the acceleration at the end of the polished rod. The correlations have been established by analyzing the kinematics of the mechanism of the sucker rod pumping unit. The experimental records have been processed with the program Total Well Management. A computer program for performing the simulations has been developed by the authors using Maple programming environment.

Numerical Simulation and Experimental Study on Internal Flow Characteristic in the Dynamic Fluidic Sprinkler

2020 ◽  
Vol 36 (1) ◽  
pp. 61-70
Author(s):  
Alexander Fordjour ◽  
Xingye Zhu ◽  
Shouqi Yuan ◽  
Frank Agyen Dwomoh ◽  
Zakaria Issaka
Keyword(s):  
Numerical Simulation ◽  
Velocity Distribution ◽  
Relative Error ◽  
Crop Production ◽  
Rotation Speed ◽  
Experimental Results ◽  
List Type ◽  
Operating Pressure ◽  
Perfect Correlation ◽  
The Relationship

HighlightsA detailed study of the relationship between the velocity distribution, length of tube and nozzle sizes. Rotation speed decreased approximately linearly as the length of the tube increased.Relative error was less than 4% for validated results indicating a perfect correlation between the values of numerical simulation, calculated, and experiment results. Abstract.A detailed study of the relationship between velocity distribution, length of tube and nozzle sizes was conducted using a dynamic fluidic sprinkler. Therefore, the objectives of this article were: (1) to study inner flow characteristics of dynamic fluidic sprinkler, (2) to compare numerical simulation and experimental results (3) to introduce an empirical equation of the variation trend of rotation speed for the newly designed sprinkler. A mathematical model for simulation of the inner flow distribution of the sprinkler was obtained by using computational fluid dynamics. The results were validated by numerical simulation and compared to the experimental results. The minimum average deviation between the calculated, simulation and experiment was 0.25%, whiles the maximum was 0.90%. It was found that the relative error was less than 4% results indicating a perfect correlation between the values of numerical simulation, calculated and experiment results. It was established that the rotation speed decreases approximately linearly as the length of the tube increases. The results revealed that the nozzle diameter, length of the tube, and the operating pressure had a significant influence on the rotation speed of the sprinkler. This study provides baseline information to improve water application efficiency for crop production in sprinkler irrigated fields. Keywords: Dynamic fluidic sprinkler, Inner flow, Nozzle, Numerical simulation, Water saving.

scholarly journals Indulgent Foods Can Paradoxically Promote Disciplined Dietary Choices

2019 ◽  
Vol 30 (2) ◽  
pp. 273-287 ◽  
Author(s):  
Nicolette J. Sullivan ◽  
Gavan J. Fitzsimons ◽  
Michael L. Platt ◽  
Scott A. Huettel
Keyword(s):  
Individual Differences ◽  
Eye Gaze ◽  
Experimental Results ◽  
Behavioral Bias ◽  
A Value ◽  
Dietary Choices ◽  
Binary Choices ◽  
The Common ◽  
Underlying Mechanisms

As obesity rates continue to rise, interventions promoting healthful choices will become increasingly important. Here, participants ( N = 79) made binary choices between familiar foods; some trials contained a common consequence that had a constant probability of receipt regardless of the participant’s choice. We theorized—on the basis of simulations using a value-normalization model—that indulgent common consequences potentiated disciplined choices by shaping other options’ perceived healthfulness and tastiness. Our experimental results confirmed these predictions: An indulgent common consequence more than doubled the rate of disciplined choices. We used eye-gaze data to provide insights into the underlying mechanisms, finding that an indulgent common consequence biased eye gaze toward healthful foods. Furthermore, attention toward the common consequence predicted individual differences in behavioral bias. Results were replicated across two independent samples receiving distinct goal primes. These results demonstrate that introducing an irrelevant indulgent food can alter processing of healthier items—and thus promote disciplined choices.

scholarly journals Molecular Dynamics Simulation of the Superspreading of Surfactant-Laden Droplets. A Review

Fluids ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 176 ◽  
Author(s):  
Panagiotis E. Theodorakis ◽  
Edward R. Smith ◽  
Richard V. Craster ◽  
Erich A. Müller ◽  
Omar K. Matar
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Molecular Level ◽  
Force Fields ◽  
Experimental Results ◽  
Dynamics Simulation ◽  
Coarse Grained ◽  
Coating Technology ◽  
Underlying Mechanisms

Superspreading is the rapid and complete spreading of surfactant-laden droplets on hydrophobic substrates. This phenomenon has been studied for many decades by experiment, theory, and simulation, but it has been only recently that molecular-level simulation has provided significant insights into the underlying mechanisms of superspreading thanks to the development of accurate force-fields and the increase of computational capabilities. Here, we review the main advances in this area that have surfaced from Molecular Dynamics simulation of all-atom and coarse-grained models highlighting and contrasting the main results and discussing various elements of the proposed mechanisms for superspreading. We anticipate that this review will stimulate further research on the interpretation of experimental results and the design of surfactants for applications requiring efficient spreading, such as coating technology.

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