scholarly journals Rotational Maneuvers of Copepod Nauplii at Low Reynolds Number

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 78
Author(s):  
Kacie T. M. Niimoto ◽  
Kyleigh J. Kuball ◽  
Lauren N. Block ◽  
Petra H. Lenz ◽  
Daisuke Takagi
Keyword(s):  
Reynolds Number ◽  
Rotational Motion ◽  
High Speed ◽  
The Body ◽  
Three Dimensions ◽  
Linear Path ◽  
Physical Mechanisms ◽  
High Speed Video ◽  
Video Observations ◽  
Principal Axes

Copepods are agile microcrustaceans that are capable of maneuvering freely in water. However, the physical mechanisms driving their rotational motion are not entirely clear in small larvae (nauplii). Here we report high-speed video observations of copepod nauplii performing acrobatic feats with three pairs of appendages. Our results show rotations about three principal axes of the body: yaw, roll, and pitch. The yaw rotation turns the body to one side and results in a circular swimming path. The roll rotation consists of the body spiraling around a nearly linear path, similar to an aileron roll of an airplane. We interpret the yaw and roll rotations to be facilitated by appendage pronation or supination. The pitch rotation consists of flipping on the spot in a maneuver that resembles a backflip somersault. The pitch rotation involved tail bending and was not observed in the earliest stages of nauplii. The maneuvering strategies adopted by plankton may inspire the design of microscopic robots, equipped with suitable controls for reorienting autonomously in three dimensions.

High Speed Video Observations of Vocal Fold Kinematics While Playing a Clarinet

2021 ◽  
Author(s):  
Andrew L. DiMatteo ◽  
Juergen Neubauer ◽  
David G. Lott ◽  
Stephanie Zacharias ◽  
Thomas Murry ◽  
...  
Keyword(s):  
Vocal Fold ◽  
High Speed ◽  
High Speed Video ◽  
Video Observations

Comparison of acceleration, expansion, and brightness of sprite streamers obtained from modeling and high-speed video observations

2009 ◽  
Vol 114 (A3) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. Y. Liu ◽  
V. P. Pasko ◽  
K. Adams ◽  
H. C. Stenbaek-Nielsen ◽  
M. G. McHarg
Keyword(s):  
High Speed ◽  
High Speed Video ◽  
Video Observations

Observation and Scaling of Tip Vortex Cavitation on Elliptical Hydrofoils

2011 ◽  
Author(s):  
Shigeki Nagaya ◽  
Risa Kimoto ◽  
Kenji Naganuma ◽  
Takayuki Mori
Keyword(s):  
Water Quality ◽  
Reynolds Number ◽  
High Speed ◽  
Tip Vortex ◽  
Video Observation ◽  
Tip Vortex Cavitation ◽  
Air Content ◽  
Sheet Cavitation ◽  
High Speed Video ◽  
Systems Research

Experimental study on tip vortex cavitation (TVC) was carried out for elliptical hydrofoils with various chord lengths. The purpose of the experiment was to clarify the influences of Reynolds number and water quality on tip vortex cavitation. Experiments were made in a large cavitation tunnel of the Naval Systems Research Center, TRDI/Ministry of Defense Japan. The elliptical hydrofoils tested were NACA 0012 cross section with chord lengths of 500mm, 250mm and 50mm. Reynolds number based on hydrofoil chord length was 2×105 < ReC < 7.4×106. Water quality of the tunnel was characterized by air content and nuclei distribution. Air content of the tunnel was varied between 30% and 80%. Nuclei distribution was measured by a cavitation susceptibility meter (CSM) with center-body venturi. Cavitation inception was determined from high speed video observation. A standard formula, (σL/σS) = (ReL/ReS)n, was applied for the scaling. In the present study, exponent of the scaling law n was found to be 0.2 < n < 0.4. High speed video observation showed that the process of the TVC inception strongly depends on water quality. In the experiments, unsteady behaviors of TVC were also investigated. Strong interactions between sheet cavitation and TVC were observed.

High-speed Video Observations of Unusual Dart Leaders in Two Natural Lightning Flashes Striking on Canton Tower

2021 ◽  
Author(s):  
Hansheng Cai ◽  
Xiaolei Wang ◽  
Gang Liu ◽  
Minchuan Liao ◽  
Shangmao Hu ◽  
...  
Keyword(s):  
High Speed ◽  
High Speed Video ◽  
Video Observations

Water skating in the larvae of dixella aestivalis (Diptera) and hydrobius fuscipes (Coleoptera)

1999 ◽  
Vol 202 (7) ◽  
pp. 845-853
Author(s):  
J. Brackenbury
Keyword(s):  
High Speed ◽  
The Body ◽  
Water Interface ◽  
Body Movements ◽  
Chironomid Larvae ◽  
High Speed Video ◽  
Adhesive Organ ◽  
Video Recordings ◽  
Air Water Interface

The kinematics of locomotion was investigated in the aquatic larvae of Dixella aestivalis and Hydrobius fuscipes with the aid of high-speed video recordings. Both insects are able to skate on the surface of the water using the dorso-apical tracheal gill as an adhesive organ or ‘foot’. Progress relies on the variable adhesion of the foot between ‘slide’ and ‘hold’ periods of the locomotory cycle. The flexural body movements underlying skating in D. aestivalis can be derived directly from the figure-of-eight swimming mechanism used in underwater swimming. The latter is shown to be similar to figure-of-eight swimming in chironomid larvae. This study shows how the deployment of a ‘foot’ enables simple side-to-side flexural movements of the body to be converted into effective locomotion at the air-water interface.

scholarly journals Angular velocity of rotation of extended bodies in general relativity

1996 ◽  
Vol 172 ◽  
pp. 309-320
Author(s):  
S.A. Klioner
Keyword(s):  
General Relativity ◽  
Angular Velocity ◽  
Rigid Body ◽  
Rotational Motion ◽  
The Body ◽  
Astronomical Observations ◽  
Newtonian Approximation ◽  
Accurate Definition ◽  
Principal Axes ◽  
Definition Of

We consider rotational motion of an arbitrarily composed and shaped, deformable weakly self-gravitating body being a member of a system of N arbitrarily composed and shaped, deformable weakly self-gravitating bodies in the post-Newtonian approximation of general relativity. Considering importance of the notion of angular velocity of the body (Earth, pulsar) for adequate modelling of modern astronomical observations, we are aimed at introducing a post-Newtonian-accurate definition of angular velocity. Not attempting to introduce a relativistic notion of rigid body (which is well known to be ill-defined even at the first post-Newtonian approximation) we consider bodies to be deformable and introduce the post-Newtonian generalizations of the Tisserand axes and the principal axes of inertia.

scholarly journals Stable hovering of a jellyfish-like flying machine

2014 ◽  
Vol 11 (92) ◽  
pp. 20130992 ◽  
Author(s):  
Leif Ristroph ◽  
Stephen Childress
Keyword(s):  
High Speed ◽  
Motion Tracking ◽  
The Body ◽  
Flapping Wings ◽  
Wing Size ◽  
Centre Of Mass ◽  
Hovering Flight ◽  
High Speed Video ◽  
Aerodynamic Model ◽  
Aerodynamic Surfaces

Ornithopters, or flapping-wing aircraft, offer an alternative to helicopters in achieving manoeuvrability at small scales, although stabilizing such aerial vehicles remains a key challenge. Here, we present a hovering machine that achieves self-righting flight using flapping wings alone, without relying on additional aerodynamic surfaces and without feedback control. We design, construct and test-fly a prototype that opens and closes four wings, resembling the motions of swimming jellyfish more so than any insect or bird. Measurements of lift show the benefits of wing flexing and the importance of selecting a wing size appropriate to the motor. Furthermore, we use high-speed video and motion tracking to show that the body orientation is stable during ascending, forward and hovering flight modes. Our experimental measurements are used to inform an aerodynamic model of stability that reveals the importance of centre-of-mass location and the coupling of body translation and rotation. These results show the promise of flapping-flight strategies beyond those that directly mimic the wing motions of flying animals.

scholarly journals High-speed video observations on fork lightning events in Malaysia

2020 ◽  
Vol 19 (3) ◽  
pp. 1620
Author(s):  
Nor Asrina Binti Ramlee ◽  
N. A. Ahmad ◽  
Z. A. Baharudin ◽  
A. R. Mohamed
Keyword(s):  
High Speed ◽  
Temporal Analysis ◽  
Lightning Protection ◽  
Stroke Event ◽  
Time Duration ◽  
Return Stroke ◽  
Lightning Strikes ◽  
High Speed Video ◽  
Three Samples ◽  
Video Observations

Malaysia is one of the countries with the highest lightning strikes incidence in the world. Yet, Malaysians are still taking a proper lightning protection indifferent manner. This might be due to lack of knowledge on lightning characteristics in Malaysia. Therefore, this study presents an unusual lightning phenomenon with multiple grounding points that might cause a disastrous event, called fork lightning. Between November and December 2018, there were three different patterns of fork lightning mechanism successfully recorded by using high speed camera with 2800 frame per second. Temporal analysis of the lightning progress had been done on the samples based only on the camera records which then played back by using Wondershare Filmora video editor. These three samples of fork lightning images were acquired among 37 lightning events recorded in this study. The first sample of fork lightning fully established the forked branch 0.35 ms before the return stroke occurred. On the contrary, second fork lightning established its forked branch 0.35 ms after the return stroke. Both forked branches for third sample simultaneously fully established with the return stroke event. Obviously, these events had striking the ground in up to ten milliseconds of time duration. Thus, there is always a possibility that they might cause serious damage and should not be neglected in designing a lightning protection system.

scholarly journals High‐Speed Video Observations of Natural Lightning Attachment Process With Framing Rates up to Half a Million Frames per Second

2019 ◽  
Vol 46 (21) ◽  
pp. 12580-12587 ◽  
Author(s):  
Qi Qi ◽  
Weitao Lyu ◽  
Ying Ma ◽  
Bin Wu ◽  
Lyuwen Chen ◽  
...  
Keyword(s):  
High Speed ◽  
High Speed Video ◽  
Video Observations ◽  
Attachment Process
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