Small-slope simulation of acoustic backscatter from a physical model of an elastic ocean bottom

2007 ◽  
Vol 122 (5) ◽  
pp. 2551 ◽  
Author(s):  
Raymond J. Soukup ◽  
Gaetano Canepa ◽  
Harry J. Simpson ◽  
Jason E. Summers ◽  
Robert F. Gragg
Keyword(s):  
Physical Model ◽  
Acoustic Backscatter ◽  
Ocean Bottom

Opercular jetting during fast-starts by flatfishes

1997 ◽  
Vol 200 (8) ◽  
pp. 1179-1188
Author(s):  
E Brainerd ◽  
B Page ◽  
F Fish
Keyword(s):  
Physical Model ◽  
High Speed ◽  
Adhesion Force ◽  
The Body ◽  
Total Force ◽  
Ocean Bottom ◽  
Blind Side ◽  
Pseudopleuronectes Americanus ◽  
Fast Start ◽  
Coherent Jet

When attacked by predators, flatfishes perform fast-starts that result in a rapid take-off from the ocean bottom on which they lie. High-speed video recordings of the blind side of flatfishes indicate that they expel a coherent jet of water from the blind-side opercular valve during take-off. Buccal pressure recordings in winter flounder (Pseudopleuronectes americanus) show that a buccal pressure pulse begins 0­20 ms before the beginning of the fast-start and has a range of mean magnitudes for three individuals of 1.6­10.7 kPa. We hypothesize that one function of the opercular jet in flatfishes may be to reduce the effects of Stefan adhesion. Stefan adhesion occurs as the fish lifts its head up rapidly from the ocean bottom, when water must flow into the space forming beneath the fish. Water viscosity opposes this rapid shear, and a suction pressure develops under the fish, making it more difficult for the fish to escape from the bottom. To estimate the magnitude of Stefan adhesion, we simulated fast-starts using a physical model in which a dead flounder was pulled upwards with an acceleration of 95 m s-2. Results from the physical model indicate that up to 35 % of the total force required to lift the head at 20 ms into the start can be attributed to Stefan adhesion. Despite this large adhesion force, previous work has shown that live flatfish do not show improved fast-start performance when Stefan adhesion has been eliminated by starting the fish from an open wire grid. Thus, live fishes are likely to be using behavioral mechanisms to reduce the adhesion force. Both the timing and location along the body of the opercular jet indicate that it is ideally suited to attenuate the effects of Stefan adhesion. Propping the body up on the median fins may also reduce adhesion by increasing the initial distance between the fish and the ocean floor.

scholarly journals Acoustic backscatter from the ocean bottom

1982 ◽  
Vol 72 (S1) ◽  
pp. S74-S74
Author(s):  
T. G. Goldsberry ◽  
S. P. Pitt ◽  
R. A. Lamb
Keyword(s):  
Acoustic Backscatter ◽  
Ocean Bottom

EXPERIMENTAL STUDIES OF CAR PROPERTIES ON A PHYSICAL MODEL

2019 ◽  
pp. 10-16
Author(s):  
Oleksii Timkov ◽  
Dmytro Yashchenko ◽  
Volodymyr Bosenko
Keyword(s):  
Mathematical Model ◽  
Remote Control ◽  
Physical Model ◽  
Model Experiment ◽  
Experimental Studies ◽  
Electrical Energy ◽  
Short Term ◽  
Motor Current ◽  
Memory Card ◽  
The Mathematical Model

The article deals with the development of a physical model of a car equipped with measuring, recording and remote control equipment for experimental study of car properties. A detailed description of the design of the physical model and of the electronic modules used is given, links to application libraries and the code of the first part of the program for remote control of the model are given. Atmega microcontroller on the Arduino Uno platform was used to manage the model and register the parameters. When moving the car on the memory card saved such parameters as speed, voltage on the motor, current on the motor, the angle of the steered wheel, acceleration along three coordinate axes are recorded. Use of more powerful microcontrollers will allow to expand the list of the registered parameters of movement of the car. It is possible to measure the forces acting on the elements of the car and other parameters. In the future, it is planned to develop a mathematical model of motion of the car and check its adequacy in conducting experimental studies on maneuverability on the physical model. In addition, it is possible to conduct studies of stability and consumption of electrical energy. The physical model allows to quickly change geometric dimensions and mass parameters. In the study of highway trains, this approach will allow to investigate the various layout schemes of highway trains in the short term. It is possible to make two-axle road trains and saddle towed trains, three-way hitched trains of different layout. The results obtained will allow us to improve not only the mathematical model, but also the experimental physical model, and move on to further study the properties of hybrid road trains with an active trailer link. This approach allows to reduce material and time costs when researching the properties of cars and road trains. Keywords: car, physical model, experiment, road trains, sensor, remote control, maneuverability, stability.

TO PHYSICAL MODEL OF THE VACANCY CLUSTER TUBES FORMATION AND METAL PROPERTIES CHANGES AFTER DYNAMIC CENTRIFUGAL CASTING

2016 ◽  
pp. 96-103
Author(s):  
E. M. Solovyov ◽  
V. I. Novikov ◽  
B. V. Spitsyn ◽  
M. R. Kiselev ◽  
V. A. Sorokin ◽  
...  
Keyword(s):  
Physical Model ◽  
Centrifugal Casting ◽  
Vacancy Cluster ◽  
Metal Properties
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