scholarly journals Breathers in Hamiltonian PT -Symmetric Chains of Coupled Pendula under a Resonant Periodic Force

Symmetry ◽  
2016 ◽  
Vol 8 (7) ◽  
pp. 59 ◽  
Author(s):  
Alexander Chernyavsky ◽  
Dmitry Pelinovsky
Keyword(s):  
Periodic Force ◽  
Symmetric Chains

Influence of Axial Excitations and of Boundary Conditions on the Parametric Instability of a Beam

1995 ◽  
Author(s):  
Régis Dufour ◽  
Alain Berlioz ◽  
Thomas Streule
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Ritz Method ◽  
Parametric Instability ◽  
Experimental Tests ◽  
Time Varying ◽  
Periodic Force ◽  
Modal Reduction ◽  
Time Varying Parameter ◽  
The Stability

Abstract In this paper the stability of the lateral dynamic behavior of a pinned-pinned, clamped-pinned and clamped-clamped beam under axial periodic force or torque is studied. The time-varying parameter equations are derived using the Rayleigh-Ritz method. The stability analysis of the solution is based on Floquet’s theory and investigated in detail. The Rayleigh-Ritz results are compared to those of a finite element modal reduction. It shows that the lateral instabilities of the beam depend on the forcing frequency, the type of excitation and the boundary conditions. Several experimental tests enable the validation of the numerical results.

Design of an Electro-Mechanical Device for Knee Loading Applications

2015 ◽  
Author(s):  
Sai Krishna Prabhala ◽  
Sohel Anwar ◽  
Hiroki Yokota ◽  
Stanley Chien
Keyword(s):  
Clinical Trials ◽  
Knee Joint ◽  
Mechanical Loading ◽  
Software Package ◽  
Bone Fractures ◽  
Dynamic Loads ◽  
Linear Motion ◽  
Mechanical Device ◽  
Periodic Force ◽  
Knee Loading

Mechanical loading of the knee is an innovative modality developed for rehabilitation of the knee joint as well as the femur and tibia that are subjected to bone fractures, osteoarthritis and osteoporosis. Loading essentially applies a lateral and periodic force to the knee joint [1]. In this paper, we propose the design of an electro-mechanical device that is capable of applying such dynamic loads. The key variable attributes of this device are the magnitude of the loading force, together with displacement and frequency. A DC motor with a controller actuates the device to produce the necessary force. The loading force is applied to the knee by a set of pads in a restricted linear motion. The operation of the device is approximated using the software package, SimMechanics of MATLAB. The simulations show that the device is capable of producing a suitable loading force with desired frequency. This simulation helps in constructing the device and performing experiments with appropriate frequencies. The device is expected to stimulate the fluids in porous skeletal matrix, resulting in strengthening the knee and bones. It can be employed for clinical trials for necessary evaluations and improvements.

scholarly journals Talin Folding as the Tuning Fork of Cellular Mechanotransduction

2020 ◽  
Author(s):  
Rafael Tapia-Rojo ◽  
Alvaro Alonso-Caballero ◽  
Julio M. Fernandez
Keyword(s):  
Bandpass Filter ◽  
Tuning Fork ◽  
Frequency Range ◽  
Periodic Force ◽  
Binding Partners ◽  
Mechanical Noise ◽  
Cellular Mechanotransduction ◽  
Folding Dynamics ◽  
Mechanical Information ◽  
Biological Environment

Cells continually sample their mechanical environment using exquisite force sensors such as talin, whose folding status triggers mechanotransduction pathways by recruiting binding partners. Mechanical signals in biology change quickly over time and are often embedded in noise; however, the mechanics of force-sensing proteins have only been tested using simple force protocols, such as constant or ramped forces. Here, using our magnetic tape head tweezers design, we measure the folding dynamics of single talin proteins in response to external mechanical noise and cyclic force perturbations. Our experiments demonstrate that talin filters out external mechanical noise but detects periodic force signals over a finely-tuned frequency range. Hence, talin operates as a mechanical bandpass filter, able to read and interpret frequency-dependent mechanical information through its folding dynamics. We describe our observations in the context of stochastic resonance, which we propose as a mechanism by which mechanosensing proteins could respond accurately to force signals in the naturally noisy biological environment.

scholarly journals DYNAMICS OF PULSED FLOW IN AN ELASTIC TUBE

2003 ◽  
Vol 17 (26) ◽  
pp. 4619-4629
Author(s):  
AMIT K. CHATTOPADHYAY ◽  
SHREEKANTHA SIL
Keyword(s):  
Fluid Flow ◽  
Viscous Fluid ◽  
Elastic Tube ◽  
Periodic Force ◽  
Pulsed Flow ◽  
Cardio Vascular ◽  
Simplistic Model

Internal haemorrhage, often leading to cardio-vascular arrest happens to be one of the prime sources of high fatality rates in mammals. We propose a simplistic model of fluid flow in our attempt to specify the location of the haemorrhagic spot, which, if located accurately, could possibly be operated leading to an instant cure. The model we employ for the purpose is basically fluid mechanical in origin and consists of a viscous fluid, pumped by a periodic force and flowing through an elastic tube. The analogy is with that of blood, pumped from the heart and flowing through an artery or vein. Our results, aided by graphical illustrations, match reasonably well with experimental observations.

THE OSCILLATION–ROTATION ATTRACTORS IN THE FORCED PENDULUM AND THEIR PECULIAR PROPERTIES

2002 ◽  
Vol 12 (01) ◽  
pp. 159-168 ◽  
Author(s):  
WANDA SZEMPLIŃSKA-STUPNICKA ◽  
ELŻBIETA TYRKIEL
Keyword(s):  
Control Parameter ◽  
Fractal Structure ◽  
Basins Of Attraction ◽  
Parameter Plane ◽  
System Control ◽  
Periodic Force ◽  
Forced Pendulum ◽  
Insight Into

The paper is aimed at exploration of the properties of the oscillation–rotation attractors in the dissipative pendulum driven by external periodic force. The study of regions of existence of the orbits in the system control parameter plane, coexistence with other attractors, fractal structure of their basins of attraction, and the role they play in the onset of the tumbling chaos, give an insight into some peculiar features of the oscillation–rotation attractors and their bifurcational structures.

Effect of externally applied periodic force on ion acoustic waves in superthermal plasmas

2018 ◽  
Vol 25 (4) ◽  
pp. 042112 ◽  
Author(s):  
Snigdha Chowdhury ◽  
Laxmikanta Mandi ◽  
Prasanta Chatterjee
Keyword(s):  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Periodic Force ◽  
Ion Acoustic
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