Measured damping coefficients of six different perforated micromechanical test structures are compared with damping coefficients given by published compact models. The motion of the perforated plates is almost translational, the surface shape is rectangular, and the perforation is uniform validating the assumptions made for compact models. In the structures, the perforation ratio varies from 24...

The paper is a continuation of the works "Modelling of viscous damping of perforated planar micromechanical structures. Applications in acoustics" [Homentcovschi and Miles, J. Acoust. Soc. Am. 116, 2939-2947 (2004)] and "Viscous Damping of Perforated Planar Micromechanical Structures" [Homentcovschi and Miles, Sensors Actuators, A119, 544-552 (2005)] where design formulas for the case of an off...

The article presents an axi-symmetrical model for determining the total damping coefficient of a periodic perforated microelectromechanical systems (MEMS) microstructure for cases where the lubrication approximation yielding the Reynolds’ equation is no longer appropriate. Damping is modeled by solving for the viscous flow in an approximation of the periodic cell geometry using an equivalent ax...

The low frequency response and damping behavior of four quantum well (4QW) gradedindex separate confinement heterostructure (GRINSCH) and SCH strained-layer lasers are compared. The SCH laser is shown to be better in both respects due to a shorter carrier capture time into the quantum wells. A record 3-dB bandwidth of 28 GHz is reported for a 150 pm cavity length 4QW strained-layer SCH laser. T...

The dimensionality of turbulence in fluid layers determines their properties. We study electromagnetically driven flows in finite-depth fluid layers and show that eddy viscosity, which appears as a result of three-dimensional motions, leads to increased bottom damping. The anomaly coefficient, which characterizes the deviation of damping from the one derived using a quasi-two-dimensional model,...

OBJECTIVE To develop a modification of the pendulum test to allow evaluation of elbow spasticity. DESIGN The main difficulties of directly applying the conventional pendulum test to the elbow were the small inertia of the forearm and the uncomfortable posture. We designed an experimental apparatus similar to a clock pendulum and developed an elbow biomechanic model to measure objectively spas...

The paper gives an analytical approximation to the viscous damping coefficient due to the motion of a gas between a pair of closely spaced fluctuating plates in which one of the plates contains a regular system of circular holes. These types of structures are important parts of many microelectromechanical devices realized in MEMS technology as microphones, microaccelerometers, resonators, etc.T...