Complex Modal Analysis of the Swimming Motion of a Whiting

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
B. F. Feeny ◽  
A. K. Feeny
Keyword(s):  
Wave Speed ◽  
Transverse Motion ◽  
Complex Mode ◽  
Swimming Motion ◽  
Before And After ◽  
Single Complex ◽  
Anterior Body ◽  
Complex Modal Analysis ◽  
Propulsive Mechanism ◽  
Complex Modal

The kinematics of the transverse motion of a swimming fish are analyzed using a complex modal decomposition. Cinematographic images of a swimming whiting (Gadus merlangus) were obtained from the work of Sir James Gray (1933, “Studies in Animal Locomotion III. The Propulsive Mechanism of the Whiting (Gadus merlangus),” J. Exp. Biol., 10, pp. 391–402). The position of the midline for each image was determined and used to produce planar positions of virtual markers distributed along the midline of the fish. Transverse deflections of each virtual marker were then used for the complex orthogonal decomposition of modes. This method was applied to images of a whiting before and after amputation in a Newtonian frame of reference and an “anterior-body-fixed” frame as well. The fish motions were well represented by a single complex mode, which was then used as a modal filter. The extracted mode and modal coordinate were used to estimate the frequency, wavelength, and wave speed. The amputated fish was compared to the nonamputated fish, and the amount of traveling in the respective waveforms was quantified. The dominant complex mode shape and the estimated modal frequency were employed to reanimate the fish motion.

Complex Modal Analysis of the Swimming Motion of a Whiting

2011 ◽  
Author(s):  
B. F. Feeny ◽  
A. K. Feeny
Keyword(s):  
Modal Analysis ◽  
Wave Speed ◽  
Experimental Biology ◽  
Orthogonal Decomposition ◽  
Transverse Motion ◽  
Complex Mode ◽  
Swimming Motion ◽  
Single Complex ◽  
Complex Modal Analysis ◽  
Complex Modal

The kinematics of the transverse motion of a swimming fish are analyzed using a complex modal decomposition. Cinematographic images of a swimming whiting (Gadus merlangus) were obtained from the work of Sir James Gray (Journal of Experimental Biology, 1933). The position of the midline for each image was determined, and used to produce planar positions of virtual markers distributed along the midline of the fish. Transverse deflections of each virtual marker were used for the complex orthogonal decomposition of modes. This method was applied to a normal whiting and an amputated whiting, both of Gray’s paper. The fish motions were well represented by a single complex mode, which was used as a modal filter. The modal coordinate was also extracted. The mode and modal coordinate were used to estimate the frequency, wavelength, and wave speed. The amputated fish was compared to the non-amputated fish, and the different amount of traveling in the respective waveforms was quantified.

Experimental Complex Modal Analysis of Machine Tool Structures

1989 ◽  
Vol 111 (2) ◽  
pp. 116-124 ◽  
Author(s):  
Y. C. Shin ◽  
K. F. Eman ◽  
S. M. Wu
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Mode Analysis ◽  
Mode Shapes ◽  
Coupled Modes ◽  
Complex Mode ◽  
Machine Tool Structure ◽  
Experimental Complex ◽  
Complex Modal Analysis ◽  
Complex Modal

Despite the well-established theories and considerable experimental research, the identification of the complex mode shapes of a real machine tool structure with general damping still remains a formidable task. Moreover, the existence of closely coupled modes with heavy damping introduces additional difficulties. This paper presents a detailed procedure for experimental complex modal analysis of a machine tool structure by the Dynamic Data System method. The accuracy and efficiency are first illustrated by numerical examples through simulation studies. It has been shown that closely coupled modes and modes with heavy damping can be successfully identified from both simulated and actual experimental data from a machine tool. Complex mode shapes were also obtained without adding any complexity or losing accuracy as compared to normal mode analysis. The experimental results obtained by the proposed method were compared with those based on the FFT algorithm.

Complex Modal Analysis of Non-Self-Adjoint Hybrid Serpentine Belt Drive Systems

2000 ◽  
Vol 123 (2) ◽  
pp. 150-156 ◽  
Author(s):  
Lixin Zhang ◽  
Jean W. Zu ◽  
Zhichao Hou
Keyword(s):  
Modal Analysis ◽  
Closed Form ◽  
Closed Form Solution ◽  
Form Solution ◽  
Mode Shapes ◽  
Belt Drive ◽  
Serpentine Belt ◽  
Complex Modal Analysis ◽  
Drive Systems ◽  
Complex Modal

A linear damped hybrid (continuous/discrete components) model is developed in this paper to characterize the dynamic behavior of serpentine belt drive systems. Both internal material damping and external tensioner arm damping are considered. The complex modal analysis method is developed to perform dynamic analysis of linear non-self-adjoint hybrid serpentine belt-drive systems. The adjoint eigenfunctions are acquired in terms of the mode shapes of an auxiliary hybrid system. The closed-form characteristic equation of eigenvalues and the exact closed-form solution for dynamic response of the non-self-adjoint hybrid model are obtained. Numerical simulations are performed to demonstrate the method of analysis. It is shown that there exists an optimum damping value for each vibration mode at which vibration decays the fastest.

Windkesselness of coronary arteries hampers assessment of human coronary wave speed by single-point technique

2008 ◽  
Vol 295 (2) ◽  
pp. H482-H490 ◽  
Author(s):  
Christina Kolyva ◽  
Jos A. E. Spaan ◽  
Jan J. Piek ◽  
Maria Siebes
Keyword(s):  
Coronary Arteries ◽  
Wave Speed ◽  
Single Point ◽  
Coronary Vessels ◽  
Distal Segment ◽  
Doppler Velocity ◽  
Healthy Human ◽  
Catheterization Laboratory ◽  
Before And After ◽  
Local Wave

A novel single-point technique to calculate local arterial wave speed ( SPc) has recently been presented and applied in healthy human coronary arteries at baseline flow. We investigated its applicability for conditions commonly encountered in the catheterization laboratory. Intracoronary pressure (Pd) and Doppler velocity ( U) were recorded in 29 patients at rest and during adenosine-induced hyperemia in a distal segment of a normal reference vessel and downstream of a single stenosis before and after revascularization. Conduit vessel tone was minimized with nitroglycerin. Microvascular resistance (MR) and SPc were calculated from Pd and U. In the reference vessel, SPc decreased from 21.5 m/s (SD 8.0) to 10.5 m/s (SD 4.1) after microvascular dilation ( P < 0.0001). SPc was substantially higher in the presence of a proximal stenosis and decreased from 34.4 m/s (SD 18.2) at rest to 27.5 m/s (SD 13.4) during hyperemia ( P < 0.0001), with a concomitant reduction in Pd by 20 mmHg and MR by 55.4%. The stent placement further reduced hyperemic MR by 26% and increased Pd by 26 mmHg but paradoxically decreased SPc to 13.1 m/s (SD 7.7) ( P < 0.0001). Changes in SPc correlated strongly with changes in MR ( P < 0.001) but were inversely related to changes in Pd ( P < 0.01). In conclusion, the single-point method yielded erroneous predictions of changes in coronary wave speed induced by a proximal stenosis and distal vasodilation and is therefore not appropriate for estimating local wave speed in coronary vessels. Our findings are well described by a lumped reservoir model reflecting the “windkesselness” of the coronary arteries.

Complex modal analysis and coupled electromechanical simulation of energy harvesting piezoelectric laminated beams

2018 ◽  
Vol 233 (7) ◽  
pp. 2526-2537 ◽  
Author(s):  
Abdolreza Pasharavesh ◽  
MT Ahmadian ◽  
H Zohoor
Keyword(s):  
Energy Harvesting ◽  
Modal Analysis ◽  
Output Voltage ◽  
Exact Analytical Solution ◽  
Lateral Displacement ◽  
Coupled Analysis ◽  
System Response ◽  
Complex Modal Analysis ◽  
Tip Mass ◽  
Complex Modal

In this paper, coupled electromechanical behavior of a vibrational energy harvesting system composed of a unimorph piezoelectric laminated beam with a large attached tip mass is investigated. To achieve this goal, first the electromechanically coupled partial differential equations governing the lateral displacement and output voltage of the harvester are extracted through exploiting the Hamilton’s principle. Considering vibration damping due to mechanical to electrical energy conversion, a complex modal analysis is performed to extract the complex eigenfrequencies and eigenfunctions of the system. Furthermore, an exact analytical solution is presented for the system response to the harmonic base excitations, including output voltage and harvested power. To validate the analytical results, at the next step a finite element simulation is conducted through ABAQUS software. To perform a fully-coupled analysis which brings into account the effect of harvesting circuit, user subroutine User-defined Amplitude (UAMP) is utilized to calculate the voltage–current relation and impose the correct electrical charge on the electrodes in each step by monitoring the output voltage of the system at previous time increments. Results of both analytical and numerical simulations are compared for a Micro-Electro-Mechanical Systems (MEMS) harvester as a case study, where a very good agreement is observed between them.

Complex modal analysis of serpentine belt drives based on beam coupling model

2017 ◽  
Vol 116 ◽  
pp. 162-177 ◽  
Author(s):  
Yue Pan ◽  
Xiandong Liu ◽  
Yingchun Shan ◽  
Gang(Sheng) Chen
Keyword(s):  
Modal Analysis ◽  
Coupling Model ◽  
Belt Drives ◽  
Beam Coupling ◽  
Serpentine Belt ◽  
Complex Modal Analysis ◽  
Complex Modal

Complex modal analysis of rods with viscous damping devices

2014 ◽  
Vol 333 (7) ◽  
pp. 2130-2163 ◽  
Author(s):  
Natale Alati ◽  
Giuseppe Failla ◽  
Adolfo Santini
Keyword(s):  
Modal Analysis ◽  
Viscous Damping ◽  
Complex Modal Analysis ◽  
Complex Modal

Complex Modal Analysis of a Flat Belt Pulley System With Belt Damping and Coulomb-Damped Tensioner

1996 ◽  
Vol 118 (2) ◽  
pp. 306-311 ◽  
Author(s):  
T. C. Kraver ◽  
G. W. Fan ◽  
J. J. Shah
Keyword(s):  
Complex Model ◽  
Pulley System ◽  
Coulomb Damping ◽  
Future Extension ◽  
Analytical Development ◽  
Complex Modal Analysis ◽  
Vibration Coupling ◽  
Modal Solution ◽  
Belt System ◽  
Complex Modal

The effects of damping on rotational vibratory solutions of a multiple pulley—flat viscoelastomeric belt system with rotary arm tensioner is developed. A complex model procedure is developed to solve both underdamped and overdamped cases. This complex modal procedure allows for future extension to include nonsymmetric rotational models, such as transverse belt vibration coupling. The modal solution enables rapid analysis over a spectrum of frequencies. Seven pulley system experimental results reported in the literature support the analytical development. Belt damping has significant vibration and belt tension amplitude effects. Tensioner spring rate and coulomb damping has minor effects.

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