Numerical Exploration on Pitching Motion of Robotic Dolphin Realized by Pectoral Fin

Author(s):  
Jiabo Cao ◽  
Zhihan Li ◽  
Xufeng Zhou ◽  
Dan Xia
Author(s):  
Manoj Prabakar Sargunaraj ◽  
Dibya Raj R. Adhikari ◽  
Carlos E. Soto ◽  
Samik Bhattacharya

ROBOT ◽  
2013 ◽  
Vol 35 (4) ◽  
pp. 484
Author(s):  
Qiang LIU ◽  
Chenglong GONG ◽  
Zhicheng JI

2014 ◽  
Vol 12 (4) ◽  
pp. 747-753 ◽  
Author(s):  
Daniel Pires Coutinho ◽  
Wolmar Benjamin Wosiacki

A new species of Polycentrusis described from the rio Negro, in Brazil. It is distinguished from P. schomburgkii by the presence of two dark postocular and one subocular band, all smaller than orbital diameter, blunt snout, isognathous mouth, reduction of the serrations on the lower edge of the lacrimal-spines ranging from zero to two tiny spines at the posterior end, intensely serrated edge of the interopercle, fully serrated posterior edge of the vertical arm of the preopercle, presence of five pungent opercular spines, subopercle broadly serrated along most of its posterior ventral edge, presence of serrations dorsally on the posterior margin of the cleithrum, fourth ray of pectoral fin reaching the vertical through the anal-fin origin, 19-21 predorsal scales, 19-20 scales on dorsal-fin base, 12-14 scales on anal-fin base, and absence of a median opercular blotch.


Zootaxa ◽  
2012 ◽  
Vol 3586 (1) ◽  
pp. 329 ◽  
Author(s):  
ZACHARY S. RANDALL ◽  
LAWRENCE M. PAGE

The genus Homalopteroides Fowler 1905 is resurrected and distinguished from the genus Homaloptera van Hasselt 1823based on a combination of characters including a unique mouth morphology, dorsal-fin origin over pelvic fin,≤60 lateral-line scales, and≤30 predorsal scales. Species included in Homalopteroides are H. wassinkii (Bleeker 1853), H. modestus(Vinciguerra 1890), H. rupicola (Prashad & Mukerji 1929), H. smithi (Hora 1932), H. stephensoni (Hora 1932), H. weberi(Hora 1932), H. tweediei (Herre 1940), H. indochinensis (Silas 1953), H. nebulosus (Alfred 1969), H. yuwonoi (Kottelat1998), and possibly H. manipurensis (Arunkumar 1999). Homalopteroides modestus (Vinciguerra 1890) is a poorlyknown species that was originally described from the Meekalan and Meetan rivers of southern Myanmar. It occurs in theSalween, Mae Khlong, and Tenasserim basins, and can be distinguished from all other species of Homalopteroides by thecombination of caudal-fin pattern (black proximal and distal bars, median blotch), 15 pectoral-fin rays, pectoral-fin lengthgreater than head length, 5½–6½ scales above and 5–6 scales below the lateral line (to the pelvic fin), 39–44 total lateral-line pores, no axillary pelvic-fin lobe, pelvic fin not reaching anus, orbital length less than interorbital width in adult, and maxillary barbel reaching to or slightly past the anterior orbital rim.


Author(s):  
Sanaz Bazaz Behbahani ◽  
Xiaobo Tan

In this paper, we propose a novel design for a pectoral fin joint of a robotic fish. This joint uses a flexible part to enable the rowing pectoral fin to feather passively and thus reduce the hydrodynamic drag in the recovery stroke. On the other hand, a mechanical stopper allows the fin to maintain its motion prescribed by the servomotor in the power stroke. The design results in net thrust even when the fin is actuated symmetrically for the power and recovery strokes. A dynamic model for this joint and for a pectoral fin-actuated robotic fish involving such joints is presented. The pectoral fin is modeled as a rigid plate connected to the servo arm through a pair of torsional spring and damper that describes the flexible joint. The hydrodynamic force on the fin is evaluated with blade element theory, where all three components of the force are considered due to the feathering degree of freedom of the fin. Experimental results on robotic fish prototype are provided to support the effectiveness of the design and the presented dynamic model. We utilize three different joints (with different sizes and different flexible materials), produced with a multi-material 3D printer, and measure the feathering angles of the joints and the forward swimming velocities of the robotic fish. Good match between the model predictions and experimental data is achieved, and the advantage of the proposed flexible joint over a rigid joint, where the power and recovery strokes have to be actuated at different speeds to produce thrust, is demonstrated.


1918 ◽  
Vol 2 (12) ◽  
pp. 471-476 ◽  
Author(s):  
Branislav Petronievics
Keyword(s):  

1996 ◽  
Vol 06 (09) ◽  
pp. 1665-1671 ◽  
Author(s):  
J. BRAGARD ◽  
J. PONTES ◽  
M.G. VELARDE

We consider a thin fluid layer of infinite horizontal extent, confined below by a rigid plane and open above to the ambient air, with surface tension linearly depending on the temperature. The fluid is heated from below. First we obtain the weakly nonlinear amplitude equations in specific spatial directions. The procedure yields a set of generalized Ginzburg–Landau equations. Then we proceed to the numerical exploration of the solutions of these equations in finite geometry, hence to the selection of cells as a result of competition between the possible different modes of convection.


2011 ◽  
Vol 83 ◽  
pp. 280-284
Author(s):  
Ming Jiang ◽  
Shu Zhang ◽  
Xiao Yuan He

Fast-starts are brief, sudden accelerations used by fish during predator-prey encounters. In this paper, a three-dimensional (3D) test and analysis method is critical to understand the function of the pectoral fin during maneuvers. An experiment method based on Fourier Transform Profilometry for 3D pectoral fin profile variety during fish maneuvers is proposed. This method was used in a carp fast-start during prey. Projecting the moiré fringes onto a carp pectoral fin it will produce the deformed fringe patterns contain 3D information. A high speed camera captures these time-sequence images. By Fourier transform, filter, inverse Fourier transform and unwrap these phase maps in 3D phase space, the complex pectoral fin profile variety were really reconstructed. The present study provides a new method to quantify the analysis of kinetic characteristic of the pectoral fin during maneuvers.


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