We have measured the twist viscoelastic coefficient of a lyotropic nematic liquid crystal composed of
disc-like micelles of cesium perfluoro-octanoate (CSPFO) in water employing dynamic
light scattering. We find that the twist viscoelastic coefficient increases with increase
in temperature in the nematic phase. We have studied the viscoelastic response of
the medium with the concentration of CSPFO in water. Twist viscoelastic coefficient
rapidly increases with the concentration of CSPFO in water at a given reduced temperature.
We have estimated the activation energy associated with the twist dynamics. We find that the
activation energy is nearly independent of the concentration of CSPFO in water. We have
also studied the effects of doping polyethylene glycol polymer on the viscoelasticity of
CSPFO-water system.
KEYWORDS: Video, Video compression, Video coding, Image segmentation, Computer programming, Cameras, Optical tracking, Image processing algorithms and systems, Detection and tracking algorithms, Computing systems
This paper introduces a multi-differential video coding algorithm for the efficient transmission of video conference streams. Because the camera is typically stationary during a video conference, we can take advantage of this information to aid in the robust transmission of the video. Specifically, we describe two simple techniques that can be used to segment the video in to background and foreground information. Using this information, we can then efficiently transmit the video stream while reducing the burstiness seen at the network layer. This technique does not require any changes to the video compression standard (typically H.261 or H.263 for video conferencing) but can reduce the bandwidth required for transmission by 20%. Experimental results are shown with actual video stream traces.
Active control systems that rely on piezoelectric materials are effective in controlling vibrations of structural components. In the present work, a finite element model is developed to study the dynamic behavior of laminated composite plates with integrated sensors and actuators. The model is valid for both continuous and segmented piezoelectric elements that can be either surface banded or embedded in the laminated plate. The formulation is based on the shear deformation plate theory and is applicable for both thin and moderately thick plates. The charge generated by the sensor and the response of the plate to an actuator voltage can be computed independently. These features are then coupled with a constant-gain control algorithm to actively control the transient response of the plate in a closed loop. Finite element solutions are presented to demonstrate the influence of sensor location, actuator location, stacking sequence and boundary conditions on the dynamic behavior of laminated plates.
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