Texture segmentation using Voronoi polygons

Textures are defined in terms of primitives called tokens. A texture segmentation algorithm based on the Voronoi tessellation is discussed. The algorithm first builds the Voronoi tessellation of the tokens that make up the textured image. It then computes a feature vector for each Voronoi polygon. These feature vectors are used in a probabilistic relaxation labeling on the tokens, to identify the interior and the border regions of the textures. Some experimental results are shown     

Internal optical loss measurements in InGaAs-InAlGaAs quantum-well lasers operating around 1550 nm

A multisection device technique is employed to carry out internal optical loss measurements in two types of InGaAs-InAlGaAs quantum-well structures. One structure consists of conventional identical-width quantum wells and the other, a broader spectral-width material, consists of multiple-width quantum wells in the active region. The temperature dependence of the internal optical losses is also investigated for both structures.     

Experimental validation of mechanical stress models by micro-Raman spectroscopy

It is shown that micro-Raman spectroscopy offers a unique tool for the validation of stress models for microelectronics devices. Starting from an analytical or numerical model that describes the variation of local stress in a device, the corresponding Raman shift is calculated and compared with the data. In this way feed-back is given to the model. This technique is demonstrated for stripes (Si₃N₄, COSi₂, W) on a Si substrate, but can be applied to any device where Raman data can be obtained.     

Effectiveness of visual interactive modeling in the context of multiple-criteria Group decisions

Significant research about the impact of information presentation on decision processes, group-decision support systems, and multicriteria decision making has occurred over the past 10 to 15 years. Advances in hardware and software technologies have significantly reduced costs and enhanced information presentation capability, specifically in the areas of virtual reality and visual interactive modeling (VIM). These visualization technologies can aid in the assimilation of complex qualitative and quantitative information by the decision maker and allow the abstraction of vast information space. Thus, in group-decision situations, visualization has the potential to enhance the decision makers' ability to make appropriate tradeoffs and improve communication between group members resulting in quicker and better consensus decisions. This paper focuses on the study of the effectiveness of advanced information-presentation technologies, such as VIM in complex decision situations involving multiple criteria and groups of decision makers. The effectiveness of VIM is evaluated through a controlled experimental study. The study finds that VIM leads to greater efficiency in decision making and improved group-member attitude and satisfaction with the decision-making process and group-decision solution. However, somewhat contrary to our a priori expectations, the quality of the decision that is made by the groups using visual-interaction modeling is not better than those without this support.     

Development of a novel mounting method for the fabrication of Pb-salt laser grown on [110] oriented BaF/sub 2/ substrate

The development of a novel mounting method for the fabrication of a cleaved cavity Pb-salt laser grown on [110] BaF/sub 2/ substrate is reported. The method involves bonding of the [110] oriented Pb-salt epitaxial layer on [100]-oriented GaAs wafers and removal of the BaF/sub 2/ substrate. After epitaxial layers were grown by molecular beam epitaxy on the BaF/sub 2/ substrate, the sample was bonded with the epilayer side down on GaAs wafers followed by an alignment process. The substrate was then completely etched away. The alignment and bonding technique allows the cleaving of Pb-salt layers in the natural cleavage plane {100}, leading to the formation of a cleaved cavity for the fabrication of a Fabry-Pe/spl acute/rot Pb-salt diode laser.     

Evaluation of solar fraction (Fn) for the north wall of a controlled environment greenhouse: an experimental validation

In this communication, an attempt has been made to define and evaluate the solar fraction (F_n) for a north wall on the basis of annual experimental studies. An even‐span greenhouse has been considered for experimental studies for the climatic conditions of Delhi. Experiments were conducted from September 1999 to August 2000. A model based on Auto‐CAD 2000 has also been developed for validation. It has been observed that the solar fraction mainly depends on angle of incidence, solar altitude angle and shape and size of the greenhouse. It is inferred that solar fraction (F_n) plays a significant role in thermal modelling of an even‐span type greenhouse. Further, it was noted that there is a fair agreement between experimental and theoretical results. Copyright © 2002 John Wiley & Sons, Ltd.     

Semiconductor optical amplifiers in WDM tree-net

In this paper, effectiveness of semiconductor optical amplifiers (SOAs) in tree-net in terms of increase in the number of users has been investigated. In the analysis, SOAs with (i) unsaturated gain, (ii) average gain saturation, and (iii) average gain saturation with gain fluctuations have been considered. Further, the results for the tree-net are compared with those for the star network. It is observed that tree-net supports more number of users than star for a given number of SOAs     

Sintering of a Ceramic at Very Low Temperatures

Surface area, linear shrinkage, and compressive strength measurements show that, with the help of neutron irradiation, sintering of high-purity alumina can be initiated at temperatures lower than 150°C; such radiation sintering might be beneficial to many other ceramics.     

Design of digital FIR notch filters

A new procedure for designing digital FIR notch filters for a specified notch frequency ω_d and 3-dB rejection bandwidth Δω has been proposed. Design formulae for computing the required weights and the length N for the filter have been derived. Illustrative examples confirming the new approach are also given     

Imaging findings in patients with-right lower quadrant pain: alternative diagnoses to appendicitis

Patients with right lower quadrant (RLQ) pain referred for imaging studies with a clinical diagnosis of appendicitis may have other pathologic conditions mimicking appendicitis. Appropriate diagnostic imaging may establish other specific diagnoses and thereby play a significant role in determining proper medical or surgical treatment. In this pictorial essay, we present a spectrum of imaging findings in patients whose clinical features were suggestive of appendicitis, but the diagnoses of a broad spectrum of other diseases were established with the imaging studies. The differential diagnoses of diseases mimicking appendicitis are reviewed.