Bio-Inspired Robotic Undulatory Stingray

2016 ◽  
Author(s):  
Emily Studebaker ◽  
William Ermlick ◽  
Rickey Warner ◽  
Brandon Hart ◽  
Aanand Pandey ◽  
...  
Keyword(s):  
Qualitative Agreement ◽  
Wave Speed ◽  
Wave Amplitude ◽  
Wave Number ◽  
Computational Results ◽  
Cfd Simulations ◽  
Amplitude Wave ◽  
And Control ◽  
Undulating Fin

The purpose of this study was to investigate fin undulation as a form of locomotion. The analysis generated CFD simulations and models that identify characteristics that are known to indicate propulsive forces. A mechanical undulating fin was designed and built to experimentally validate these computational results. Comparing thrust data from the mechanical fin with the CFD results yielded qualitative agreement with various parameters including wave amplitude, wave speed, and wave number. Quantifying these characteristics are necessary towards understanding the mechanics of undulation and will aid in the design and control of underwater undulating robotics.

Modeling of Coupled Bending and Torsion in Elastic Structures

1993 ◽  
Author(s):  
H. T. Banks ◽  
C. A. Smith
Keyword(s):  
Experimental Data ◽  
Numerical Results ◽  
Computational Results ◽  
Elastic Structures ◽  
Approximation Techniques ◽  
Flexural Vibrations ◽  
And Control

Abstract In this presentation we will report on joint efforts with D.J. Inman and his colleagues at MSL, SUNY at Buffalo, to develop viable models for the analysis and control of elastic structures exhibiting coupled torsional and flexural vibrations. A model for coupled torsion and bending is developed which incorporates Kelvin Voigt damping and warping. Approximation techniques are introduced and preliminary numerical results are discussed. Experimental data is presented and used to test our computational results.

Abstract 2769: Bradycardia-Dependent Augmentation of J-wave Elevation in Patients with Idiopathic Ventricular Fibrillation

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Koichi Mizumaki ◽  
Akira Fujiki ◽  
Masao Sakabe ◽  
Tamotsu Sakamoto ◽  
Yosuke Nakatani ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Linear Regression ◽  
Wave Amplitude ◽  
Idiopathic Ventricular Fibrillation ◽  
Cardioverter Defibrillator ◽  
Rate Dependent ◽  
Wave Elevation ◽  
Male Patients ◽  
And Control ◽  
J Wave

Although J-wave elevation (JWE) in the inferior or lateral leads is characteristic of subtype of idiopathic ventricular fibrillation (IVF), difference between malignant and benign JWE remains to be elucidated. So, we assessed the hypothesis that the rate dependent changes in JWE could be different between patients with IVF and control subjects. Six male patients with IVF and 18 age matched male controls with JWE (>2 mm) in the lateral leads were studied. CM-5 lead digital Holter ECG was recorded and J wave amplitude was automatically measured. J/RR relationships were evaluated by means of J/RR linear regression lines for 24 hours, and according to four 6-hour periods. From J-RR linear regression lines, J-RR slope (mm/sec), J wave amplitude (mm) at RR intervals of both 0.6 sec and 1.2 sec (J (0.6) and J (1.2) ) were determined. In all 6 patients with IVF, the time of spontaneous episodes of VF were investigated from the implantable cardioverter defibrillator (ICD) stored data. For 24 hours, J-RR slope was greater in IVF patients than in controls (3.5±0.7 vs 2.4±0.8, p<0.01). (J (0.6) ) wasn’t different between 2 groups; however, J (1.2) was greater in IVF patients than in controls (2.8±0.9 vs 2.0±0.6, p<0.05). In IVF patients, ST/RR slope was highest during 18:00–24:00; however, these circadian changes were blunted in controls. J(1.2) was greater during 18:00 – 6:00 in IVF patients than in controls. Seven (59%) of total 9 episodes of spontaneous VF of IVF patients occurred during 18:00 – 6:00. In patients with subtype of IVF, JWE augmented during bradycardia especially at night. This could relate to nighttime occurrence of IVF.

scholarly journals Development and Motion Testing of a Robotic Ray

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Jianhui He ◽  
Yonghua Zhang
Keyword(s):  
Aspect Ratio ◽  
Morphological Parameters ◽  
Kinematic Parameters ◽  
Motion Patterns ◽  
Pectoral Fins ◽  
Fin Ray ◽  
The Stability ◽  
And Control ◽  
Undulating Fin ◽  
Fin Shape

Biomimetics takes nature as a model for inspiration to immensely help abstract new principles and ideas to develop various devices for real applications. In order to improve the stability and maneuvering of biomimetic fish like underwater propulsors, we selected bluespotted ray that propel themselves by taking advantage of their pectoral fins as target. First, a biomimetic robotic undulating fin driven propulsor was built based on the simplified pectoral structure of living bluespotted ray. The mechanical structure and control circuit were then presented. The fin undulating motion patterns, fin ray angle, and fin shape to be investigated are briefly introduced. Later, the kinematic analysis of fin ray and the whole fin is discussed. The influence of various kinematic parameters and morphological parameters on the average propulsion velocity of the propulsor was analyzed. Finally, we conclude that the average propulsion velocity generally increases with the increase of kinematic parameters such as frequency, amplitude, and wavelength, respectively. Moreover, it also has a certain relationship with fin undulating motion patterns, fin ray angle, fin shape, and fin aspect ratio.

Research on the Noise Reduction and Efficiency Increase for Axial Fan with Wave Leading Edge Blades

2020 ◽  
Author(s):  
Bo Li ◽  
Yujing Wu ◽  
Dange Guo ◽  
Dan Luo ◽  
Diangui HUANG
Keyword(s):  
Noise Reduction ◽  
Sound Pressure Level ◽  
Wave Amplitude ◽  
Sound Pressure ◽  
Noise Analysis ◽  
Leading Edge ◽  
Pressure Level ◽  
Wave Number ◽  
Monitoring Point ◽  
Reduction Effect

Abstract This paper imitates the raised structure of the leading edge of the humpback whale fin limbs, designed six bionic blades. The aerodynamic analysis show that: the wave leading edge blade can improve the total pressure efficiency of the axial flow fan, and under off-design conditions, the aerodynamic performance of bionic fan is better than that of prototype fan. The noise analysis shows that: under the condition of constant wave number, increasing wave amplitude can reduce the overall sound pressure level at the monitoring point, in the middle and high frequency range, the sound pressure level of the bionic fan at the monitoring point is significantly lower than that of the prototype fan, and the noise reduction effect increases with the increase of wave amplitude; under the condition of constant wave amplitude, increasing the wave number can reduce the fan noise. At a certain wave number and amplitude, the overall sound pressure level of the bionic fan at the monitoring point is at most 2.91 dB lower than that of the prototype fan. In this paper, the noise reduction effect of increasing wave number is more obvious than that of increasing wave amplitude.

scholarly journals Boussinesq Model and CFD Simulations of Non-Linear Wave Diffraction by a Floating Vertical Cylinder

2020 ◽  
Vol 8 (8) ◽  
pp. 575
Author(s):  
Sarat Chandra Mohapatra ◽  
Hafizul Islam ◽  
C. Guedes Soares
Keyword(s):  
Wave Diffraction ◽  
Perturbation Technique ◽  
Harmonic Wave ◽  
Vertical Cylinder ◽  
Numerical Data ◽  
Second Order ◽  
Wave Number ◽  
Linear Wave ◽  
Cfd Simulations ◽  
Boussinesq Model

A mathematical model for the problem of wave diffraction by a floating fixed truncated vertical cylinder is formulated based on Boussinesq equations (BEs). Using Bessel functions in the velocity potentials, the mathematical problem is solved for second-order wave amplitudes by applying a perturbation technique and matching conditions. On the other hand, computational fluid dynamics (CFD) simulation results of normalized free surface elevations and wave heights are compared against experimental fluid data (EFD) and numerical data available in the literature. In order to check the fidelity and accuracy of the Boussinesq model (BM), the results of the second-order super-harmonic wave amplitude around the vertical cylinder are compared with CFD results. The comparison shows a good level of agreement between Boussinesq, CFD, EFD, and numerical data. In addition, wave forces and moments acting on the cylinder and the pressure distribution around the vertical cylinder are analyzed from CFD simulations. Based on analytical solutions, the effects of radius, wave number, water depth, and depth parameters at specific elevations on the second-order sub-harmonic wave amplitudes are analyzed.

The Detection and Analysis of Reservoir Dam Crack Depth and Grouting Quality Analysis

2012 ◽  
Vol 204-208 ◽  
pp. 3329-3332 ◽  
Author(s):  
Jin Yang Zhang ◽  
Xiu Gao
Keyword(s):  
Wave Speed ◽  
Wave Amplitude ◽  
Ultrasonic Method ◽  
Crack Depth ◽  
Quality Analysis ◽  
Test Surface ◽  
Clean Water ◽  
Wave Shape ◽  
Sonic Logging ◽  
Deep Crack

Ultrasonic method is a considerably mature method to test the defects of concrete. As for a certain dam deep crack with merely one test surface, the operations can be done such as drilling holes on both crack sides, filling clean water as coupling agent and finally the crack depth is tested with cross-hole sonic logging, subsequently, the data processing and depth judgment with the test principle of the said method. The result manifests that before grouting treatment, the measured dam crack depth is 1.2~9.0m, and the tested point wave shape has not been obviously abnormal and the criterions of wave amplitude and wave speed against the intact local concrete remain no greater differences and the cracks grout in the tested zone are generally solid after the grouting.

scholarly journals Internal Waves at an Interface between Two Layers of Differing Stability

2009 ◽  
Vol 66 (6) ◽  
pp. 1845-1855 ◽  
Author(s):  
John McHugh
Keyword(s):  
Free Surface ◽  
Internal Waves ◽  
Density Profile ◽  
Wave Speed ◽  
Wave Amplitude ◽  
Buoyancy Frequency ◽  
Higher Harmonics ◽  
Free Surface Waves ◽  
Interfacial Boundary ◽  
Upper Boundary

Abstract Internal waves in a two-layer fluid are considered. The layers have different values of the buoyancy frequency, assumed to be constant in each layer. The density profile is chosen to be continuous across the interface and the flow is Boussinesq. The solution is an expansion in the wave amplitude, similar to a Stokes expansion for free surface waves. The results show that the nonlinear terms in the interfacial boundary conditions require higher harmonics and result in nonlinear wave steepening at the interface. The first few harmonics are scattered by the interface, whereas the higher harmonics are evanescent in the vertical. The second-order correction to the wave speed is negative, similar to previous results with a rigid upper boundary.

scholarly journals Design, Implementation and Control of a Fish Robot with Undulating Fins

10.5772/50898 ◽  
2011 ◽  
Vol 8 (5) ◽  
pp. 60 ◽  
Author(s):  
Mohsen Siahmansouri ◽  
Ahmad Ghanbari ◽  
Mir Masoud Seyyed Fakhrabadi
Keyword(s):  
Field Trials ◽  
Robotic Fish ◽  
Propulsive Force ◽  
Fish Robot ◽  
Revolution Speed ◽  
The Individual ◽  
And Control ◽  
Phase Angles ◽  
The Relationship ◽  
Undulating Fin

Biomimetic robots can potentially perform better than conventional robots in underwater vehicle designing. This paper describes the design of the propulsion system and depth control of a robotic fish. In this study, inspired by knife fish, we have designed and implemented an undulating fin to produce propulsive force. This undulating fin is a segmental anal fin that produces sinusoidal wave to propel the robot. The relationship between the individual fin segment and phase angles with the overall fin trajectory has also been discussed. This propulsive force can be adjusted and directed for fish robot manoeuvre by a mechanical system with two servomotors. These servomotors regulate the direction and depth of swimming. A wireless remote control system is designed to adjust the servomotors which enables us to control revolution, speed and phase differences of neighbor servomotors of fins. Finally, Field trials are conducted in an outdoor pool to demonstrate the relationship between robotic fish speed and fin parameters like phase difference, the number of phase and undulatory amplitude.

Spatial stability of the non-parallel Bickley jet

1981 ◽  
Vol 102 ◽  
pp. 127-140 ◽  
Author(s):  
Vijay K. Garg
Keyword(s):  
Growth Rate ◽  
Energy Density ◽  
Critical Reynolds Number ◽  
Transverse Velocity ◽  
Parallel Flow ◽  
Wave Number ◽  
Amplitude Wave ◽  
Spatial Stability ◽  
Rate Dependent ◽  
Neutral Curves

The spatial stability of the plane, two-dimensional jet flow to infinitesimal disturbances is investigated by taking into account the effects of transverse velocity component and the streamwise variations of the basic flow and of the disturbance amplitude, wave-number and spatial growth rate. This renders the growth rate dependent on the flow variable as well as on the transverse and streamwise co-ordinates. Growth rates for the energy density of the disturbance and the associated neutral curves are provided as a function of the streamwise co-ordinate. Variation of growth rate of the disturbance stream function and streamwise component of velocity with the transverse co-ordinate is also given for different disturbance frequencies and streamwise locations. Results are compared with those for the parallel-flow stability analysis, and also with those for an analysis that accounts for only some of the non-parallel effects. It is found that the critical Reynolds number based on the growth of energy density of the disturbance depends on the streamwise co-ordinate and lies within the range (around 20) found experimentally, while the parallel-flow theory yields a rather low value of 4·0.

scholarly journals The Exciting Forces on Fixed Bodies in Waves

1962 ◽  
Vol 6 (04) ◽  
pp. 10-17 ◽  
Author(s):  
J. N. Newman
Keyword(s):  
Wave Amplitude ◽  
Amplitude Ratio ◽  
Exciting Force ◽  
The Body ◽  
Forced Oscillations ◽  
Wave Number ◽  
Far Field ◽  
Two Dimensional ◽  
Calm Water ◽  
Exciting Forces

General expressions, originally given by Haskind, are derived for the exciting forces on an arbitrary fixed body in waves. These give the exciting forces and moments in terms of the far-field velocity potentials for forced oscillations in calm water and do not depend on the diffraction potential, or the disturbance of the incident wave by the body. These expressions are then used to compute the exciting forces on a submerged ellipsoid, and on floating two-dimensional ellipses. For the ellipsoid, the problem is solved using the far-field potentials, and detailed results and calculations are given for the roll moment. The other forces agree, for the special case of a spheroid, with earlier results obtained by Havelock. In the case of two-dimensional motion the exciting forces are related to the wave amplitude ratio A for forced oscillations in calm water, and this relation is used to compute the heave exciting force for several elliptic cylinders. Expressions are also given relating the damping coefficients and the exciting forces. A = wave amplitude A = wave-height ratio for forced oscillations(a1 a2 a3) = semi-axis of ellipsoidBij = damping coefficientsC4 = nondimensional roll exciting-force coefficientDj = virtual-mass coefficients, defined by equations (18) and (19)g = gravitational accelerationh = depth of submergencei = √ — 1j = index referring to direction of force or motionn(z) = spherical Bessel function, K = wave number, K = ω2/gPj = functions defined following equation (17)R = polar coordinateV, = velocity components (x, y, z) = Cartesian coordinatesαi = Green's integrals, defined by equation (20)β = angle of incidence of wave systemθ = polar coordinateρ= fluid densityφj = velocity potentialsω = circular frequency of encounter

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