Search results for "Damping constant"
showing 4 items of 4 documents
Highly Reduced Saturation Magnetization in Epitaxially Grown Ferrimagnetic Heusler Thin Films
2019
The key of spintronic devices using the spin-transfer torque phenomenon is the effective reduction of switching current density by lowering the damping constant and the saturation magnetization while retaining strong perpendicular magnetic anisotropy. To reduce the saturation magnetization, particular conditions such as specific substitutions or buffer layers are required. Herein, we demonstrate highly reduced saturation magnetization in tetragonal D022 Mn3–xGa thin films prepared by rf magnetron sputtering, where the epitaxial growth is examined on various substrates without any buffer layer. As the lattice mismatch between the sample and the substrate decreases from LaAlO3 and (LaAlO3)0.3…
Nonadiabatic Transitions for a Decaying Two-Level-System: Geometrical and Dynamical Contributions
2006
We study the Landau-Zener Problem for a decaying two-level-system described by a non-hermitean Hamiltonian, depending analytically on time. Use of a super-adiabatic basis allows to calculate the non-adiabatic transition probability P in the slow-sweep limit, without specifying the Hamiltonian explicitly. It is found that P consists of a ``dynamical'' and a ``geometrical'' factors. The former is determined by the complex adiabatic eigenvalues E_(t), only, whereas the latter solely requires the knowledge of \alpha_(+-)(t), the ratio of the components of each of the adiabatic eigenstates. Both factors can be split into a universal one, depending only on the complex level crossing points, and a…
OPTIMAL DAMPING CONSTANT OF THE QUARTER CAR SHOCK ABSORBER
2013
The paper aim is the investigation of optimal damping constant of a quarter car shock absorber that is performed in the frequency domain. The optimal damping constant refers to the value that minimizes the acceleration of all connected bodies characterizing a two degree of freedom system sketching a quarter car. The connected bodies are sprung and unsprung mass respectively for quarter of chassis and tire, the last one maintain the contact with the ground and it is connected with the sprung mass through a shock absorber characterized by spring and fluid damper. Optimal damping constant was determined by imposing analytical conditions on the expression of acceleration of two masses. Afterwar…
The Recovery of the Optimal Damping Constant by the MRF Damper
2009
In this paper was studied a method to analyze the recovering of optimal damping constant because of temperature increasing in a shock absorber. The increasing on temperature leads to decreasing that constant by mean dynamic viscosity such to modify the dynamic behavior of a 2DOF system built-up by sprung and unsprung mass. A MagnetoRheological damper was designed according with the desired optimal damping constant once fixed temperature design. It was seen that the increasing of temperature this constant is lost. As MagnetoRheological-Fluids allows us to increase the viscosity, we use a control signal by a state feedback of reduced order to create a such magnetic induction field to recover …