A new predictive search area approach for fast block motion estimation

According to the observation on the distribution of motion differentials among the motion vector of any block and those of its four neighboring blocks from six real video sequences, this paper presents a new predictive search area approach for fast block motion estimation. Employing our proposed simple predictive search area approach into the full search (FS) algorithm, our improved FS algorithm leads to 93.83% average execution-time improvement ratio, but only has a small estimation accuracy degradation. We also investigate the advantages of computation and estimation accuracy of our improved FS algorithm when compared to the edge-based search algorithm of Chan and Siu (see IEEE Trans. Image Processing, vol.10, p.1223-1238, Aug. 2001); experimental results reveal that our improved FS algorithm has 74.33% average execution-time improvement ratio and has a higher estimation accuracy. Finally, we further compare the performance among our improved FS algorithm, the three-step search algorithm, and the block-based gradient descent search algorithm.     

A new MMIC broadside coupler using an array of air-bridges for directivity enhancement

A new quadrature broadside coupler is proposed, which employs an array of air-bridges to enhance directivity via its phase-equalization effect on the c-mode and /spl pi/-modes. The realization of air-bridges follows a standard MMIC fabrication process. An experimental chip fabricated on the 75-/spl mu/m GaAs substrate verifies the air-bridge effect and shows wideband characteristics of the coupling of 3.2/spl plusmn/0.4 dB, the insertion loss of 3.9/spl plusmn/0.4 dB, the output phase deviation from quadrature less than 6/spl deg/, and the isolation greater than 18 dB from 20 to 40 GHz.     

Modeling Temperature in Coupled Electrical and Thermal Simulations of the Electroconsolidation® Process

Electroconsolidation® is a process for densifying complex-shaped parts by using electrically conductive particulate solids as a pressure-transmitting medium. The part is immersed in a bed of the particulate medium contained in a die chamber. Sintering temperature is achieved by resistive heating of the medium while applying compaction pressure. The process is capable of ultrahigh temperatures and short cycle times and offers the potential for low processing costs.

Control of the process and selection of process conditions require knowledge of the temperatures within the die. Temperature gradients exist because of the high heating rate and because of variations of density and electrical resistivity of the medium due to the presence of the part. Direct measurement of temperature with thermocouples or other conventional means is impractical because of the high temperatures, high currents, and high pressures that are involved. Therefore, a computer model was developed to predict temperature as a function of time and applied voltage for any location in the die. The computer model is composed of three parts: a geometrical model to approximate the density and resistivity variations in the medium, a finite-element model to calculate the rate of resistive heating within each element, and a finite-difference model to calculate the temperature distribution based on solution of the heat-transfer equations. Predicted temperatures have been shown to be in excellent agreement with measurements, and numerical simulation provided encouraging consistency and reasonably accurate predictions of temperature profiles within the die. The model demonstrated the feasibility of a new process to achieve simultaneous application of pressure and heat to powder densification in Electroconsolidation.     

Fabrication and characteristics of high-speed implant-confined index-guided lateral-current 850-nm vertical cavity surface-emitting lasers

Process technology of high-speed implant-apertured index-guide lateral-current-injection top dielectric-mirror quantum-well 850-nm vertical cavity surface-emitting lasers (VCSELs) has been developed. Oxygen and helium implantation for aperture definition and extrinsic capacitance reduction, dielectric mirror formation, p- and n-ohmic contact formation, VCSEL resistance, and thermal analysis were investigated. Employing this technology, GaAs/AlGaAs-based 850-nm VCSELs with small signal modulation bandwidths up to 11.5 Gb/s and an eye diagram generated at 12 Gb/s by a pseudorandom bit sequence of 2/sup 31/-1 were achieved. The bit-error rates were below 10/sup -13/. The threshold current is as low as 0.8 mA for 7-/spl mu/m-diameter current apertures and typical slope efficiencies of 0.45-0.5 mA/mW were obtained.     

Querying distributed multimedia databases and data sources for sensor data fusion

Sensor data fusion imposes a number of novel requirements on query languages and query processing techniques. A spatial/temporal query language called /spl Sigma/QL has been proposed to support the retrieval and fusion of multimedia information from multiple sources and databases. In this paper we investigate fusion techniques, multimedia data transformations and /spl Sigma/QL query processing techniques for sensor data fusion. Fusion techniques including fusion by the merge operation, the detection of moving objects, and the incorporation of belief values, have been developed. An experimental prototype has been implemented and tested to demonstrate the feasibility of these techniques.     

Electroplating of Ni-Cr on steel with pulse plating

It has been difficult to electrolytically obtain crack- free chromium plating because of the high stresses caused by several factors. Accordingly, electroplating of nickel- chromium also encounters a similar problem. Cracks in chromium- containing plating was ascribed, in a certain sense, to the formation of a hydride formed through hydrogen adsorption from the electrolyte. A periodical pulse reverse plating current would enhance the release of hydrogen and hence the elimination of cracking. The present work describes a successful process for obtaining crack- free nickel- chromium plating and the effects of experimental variables on plating compositions.     

The Effect of Run Time on the Inter-Unit Uniformity of Aqueous Film Coating Applied to Glass Beads in a Hi-Coater

Coating experiments were conducted to assess the inter-unit uniformity using individual weight gains of glass beads. Applying more aqueous film coating and prolonging the film-coating process by diluting the coating suspension did improve the coating variability among glass beads. It appears that run time is an important underlying factor which affecting the inter-unit coating uniformity.