The effect of carrier-induced change on the optical properties of AlGaAs-GaAs intermixed quantum wells

The carrier-induced effects in the change of absorption and refractive index on the AlGaAs-GaAs intermixing modified quantum wells (QW's) have been investigated theoretically. Band-filling, bandgap shrinkage, and free-carrier absorption have been included for various carrier concentrations. The Schrodinger and the Poisson equations have been considered self-consistently. The polarized absorption coefficients are calculated using the Kane k·p method for a four band model and followed by the Kramers-Kranig transformation to obtain the refractive index change. The results obtained show a more enhanced bandgap renormalization and change of absorption, but a reduced change in refractive index for the larger intermixing extents. It is important to know the carrier-induced optical parameter changes the intermixed QW's because of their recent interests in photonics.published_or_final_versio

Analysis of the resonance modes of PZT/epoxy 1-3 composite rings

Author name used is this publication: C. P. ChongRefereed conference paper2001-2002 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Optimization of Textured-surface Light Emitting Diode

We present an analysis of the efficiency and radiation pattern of the textured-surface LED by tracing the light rays that emits from the active layer. Through simulation, we discover that the efficiency depends on the thickness of the textured layer and its separation distance from the active layer. By carefully choosing these two parameters, maximum efficiency an be achieved. The radiation pattern of a texture-surface LED is found to be different from the flat-surfaced LED in that the textured surface has a wider angular spread.published_or_final_versio

Designing an external efficieny of over 30% for light emittingdiode

In designing high intensity LED's, substantial increase in efficiency can be achieved with the use of a textured surface, which is characterized by its external quantum efficiency and radiation pattern. We have found that the randomness of the inclined facade surfaces contributes substantially to the enhanced efficiency substantially. Such efficiency is strongly dependent upon the textured surface layer's thickness and its distance to the active layer of the diode. To attain the maximum efficiency, an optimal range for these parameters is required.published_or_final_versio

Heap graph based software theft detection

published_or_final_versio

Brain tumor boundary detection in MR image with generalized fuzzy operator

Boundary detection in MR image with brain tumor is an important image processing technique applied in radiology for 3D reconstruction. The nonhomogeneities density tissue of the brain with tumor can result in achieving the inaccurate location in any boundary detection algorithms. Recently, some studies using the contour deformable model with regional base technique, the performance is insufficient to obtain the fine edge in the tumor, and the considerable error in accuracy is existed. Moreover, even in some of the normal tissue region, edge created by this method has also been encompassed. In this paper, we propose a new approach to detect the boundary of brain tumor based on the generalized fuzzy operator (GFO). One typical example is used for evaluating this method with the contour deformable model.published_or_final_versio

Estimation of the gray level variations in soft and hard peri-implant tissue from X-ray images

In the treatment and assessment of periodontal disease periapical films are taken at regular intervals. The films are compared around the region of the implant to monitor the changes that have taken place. A computer-assisted method to automate this process is presented here. To compare two images, a pair of X-ray images are superimposed on top of each other. The images are normalized and transformed to obtain the best fit. These images are subtracted and the difference in pixel values are used as a basis for analysis. A method for improving the alignment accuracy and contrast compensation is highlighted.published_or_final_versio

Water-induced degradation in lead zirconate titanate piezoelectric ceramics

2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Thyroid cancer cells boundary location by a fuzzy edge detection method

Morphometric assessment of tumor cells is important in the prediction of biological behavior of thyroid cancer. In order to automate the process, the computer-based system has to recognize the boundary of the cells. Many methods for the boundary detection have appeared in the literature and some of them applied to microscopic slice analysis. However, there is no reliable method since the gray-levels in the nuclei are uneven and are similar to the background. In the paper, a fuzzy edge detection method is used and is based on an improved generalized fuzzy operator. The method enhances the nuclei and effectively separates the cells from the background.published_or_final_versio

Testing object-oriented industrial software without precise oracles or results

Software testing such as object-oriented software Testing At the Class and Cluster LEvels, or TACCLE, can be achieved by defining the test objectives, selecting and executing test cases, and checking results. The software specifications are extracted from technical drawings of mechanical and electronic hardware designed by process engineers using an in-house technique. TACCLE enables software engineers to test each individual class independently, then test the interaction among classes. The TACCLE methodology is described in three sections that include class-level testing, cluster-level testing, and test case generation and test script translation. The notion of testing observational equivalence and bypassing the need for oracles is important in test automation for industrial projects where it is impractical to define a precise relationship between specification and the software under test.postprin