A design methodology for fractal layout organization

Venkatadri el a.(HE Transactions, 29, 911-924, 1997) have proposed a new methodology for shop floor layout that involves the use of fractal cells and have compared the performance of their new layout with those obtained using the function, group and holographic layouts. A few inconsistencies are present in their results, expressed as flow scores. This note points out these inconsistencies through the use of appropriate examples.     

Situated Software: Concepts, Motivation, Technology, and the Future

Situated software, a type of opportunistic software, is created by a small subset of users to fulfill a specific purpose. For example, business users have been creating situated software through mashups, which combine data from multiple sources on internal systems or the Internet. Situated software can change the way users access, perceive, and consume information, and can allow users to finally focus on what to do with information, rather than where to find it or how to get to it. However, situated software also has limitations. This article identifies situated software's role, provides examples of its use, traces the Internet's role in its rapid evolution, outlines areas where it is appropriate, describes its limitations, and presents enablers for adopting situated software in an enterprise.     

An energy-based three-dimensional segmentation approach for the quantitative interpretation of electron tomograms.

Electron tomography allows for the determination of the three-dimensional structures of cells and tissues at resolutions significantly higher than that which is possible with optical microscopy. Electron tomograms contain, in principle, vast amounts of information on the locations and architectures of large numbers of subcellular assemblies and organelles. The development of reliable quantitative approaches for the analysis of features in tomograms is an important problem, and a challenging prospect due to the low signal-to-noise ratios that are inherent to biological electron microscopic images. This is, in part, a consequence of the tremendous complexity of biological specimens. We report on a new method for the automated segmentation of HIV particles and selected cellular compartments in electron tomograms recorded from fixed, plastic-embedded sections derived from HIV-infected human macrophages. Individual features in the tomogram are segmented using a novel robust algorithm that finds their boundaries as global minimal surfaces in a metric space defined by image features. The optimization is carried out in a transformed spherical domain with the center an interior point of the particle of interest, providing a proper setting for the fast and accurate minimization of the segmentation energy. This method provides tools for the semi-automated detection and statistical evaluation of HIV particles at different stages of assembly in the cells and presents opportunities for correlation with biochemical markers of HIV infection. The segmentation algorithm developed here forms the basis of the automated analysis of electron tomograms and will be especially useful given the rapid increases in the rate of data acquisition. It could also enable studies of much larger data sets, such as those which might be obtained from the tomographic analysis of HIV-infected cells from studies of large populations.     

Warm isostatic pressing (WIP''ing) of GS44 Si3N4 FDC parts for defect removal

Fused deposition of ceramics (FDC) is one of the developing solid freeform fabrication (SFF) techniques. The successful production of high performance ceramics by the FDC process requires that no defects exist in the green parts. However, build defects, such as missing roads, poorly bonded layers or sub-perimeter voids can be encountered in improperly built FDC parts. In this study, a method known as WIP'ing (warm isostatic pressing) was evaluated for its ability to eliminate existing defects in GS44 Si₃N₄ green FDC parts. Analogous to CIP'ing (cold isostatic pressing), the green FDC parts were rubber bagged and loaded into a pressure chamber filled with water soluble oil at different temperatures, ranging from 30 to 90°C, at pressures of up to 35 MPa. X-Ray radiography results indicated that at temperatures above 70°C, WIP'ing was effective in closing the gaps of the intentionally placed void defects in FDC parts. However, WIP'ing above 70°C was not effective in healing the defects completely. The fracture strengths of FDC parts with intentional added defects, WIP'ed above 70°C were substantially lower than control samples.     

Chemical synthesis of the high-pressure cubic-spinel phase of ZnIn2S4

Chemical reactions conducted in solution are known to generate solid precursors containing molecular units that help in the formation of high-temperature phases. The structural units are created by controlling the molecular environments in solution, and as a result, phases that normally form and are stable at high temperatures can be synthesized at low or moderately elevated temperatures. However, the application of chemical approaches for synthesizing phases that normally form at high pressure are relatively unknown. In this work, a simple room-temperature aqueous chemical precipitation route has been used to synthesize the high-pressure cubic spinel modification of ZnIn2S4. A solution coordination model (SCM) has been proposed to explain the formation of the high-pressure phase. The crystallinity, phase purity and phase transformation characteristics of the cubic phase have been studied using X-ray diffraction (XRD) including Rietveld refinement, transmission electron microscopy (TEM), and Auger electron microscopy (AEM). Results of these studies are discussed in the light of a proposed solution coordination model (SCM). © 1998 Kluwer Academic Publishers     

A TCP offload accelerator for 10 Gb/s Ethernet in 90-nm CMOS

This programmable engine is designed to offload TCP inbound processing at wire speed for 10-Gb/s Ethernet, supporting 64-byte minimum packet size. This prototype chip employs a high-speed core and a specialized instruction set. It includes hardware support for dynamically reordering out-of-order packets. In a 90-nm CMOS process, the 8-mm/sup 2/ experimental chip has 460 K transistors. First silicon has been validated to be fully functional and achieves 9.64-Gb/s packet processing performance at 1.72 V and consumes 6.39 W.     

Analyzing transformation-based simulation metamodels

To analyze a simulation (response surface) metamodel that involves a variance-stabilizing transformation of the original simulation-generated response, we present two techniques. In the first technique we compute an approximate percentile-type confidence interval for the mean of the original response at a selected factor-level combination (design point) as follows: we compute the usual confidence interval for the mean of the transformed response at that design point; and then we untransform the corresponding endpoints to obtain the desired confidence interval for the untransformed metamodel. In the second technique we compute the Maximum Likelihood Estimator (MLE) for the mean of the untransformed response based on standard distributional properties of the transformed metamodel; then using the delta method to approximate the MLE's variance, we construct for the untransformed metamodel an asymptotically exact confidence interval centered on the MLE. We illustrate these techniques in a case study on manufacturing cell design, comparing them with a more conventional approach for analyzing transformed-based simulation metamodels. A Monte Carlo performance evaluation shows that significantly better confidence-interval coverage is maintained with the second proposed technique (called the "MLE-delta method") over a wide range of values for the residual variance of the transformed metamodel.     

Automated heart abnormality detection using sparse linear classifiers.

In this article, the task of building a computer-aided diagnosis system that can automatically detect wall-motion abnormalities from echocardiograms was addressed. Some medical background on cardiac ultrasound and the standard methodology used by cardiologists to score wall-motion abnormalities were provided. Real-life dataset, which consists of echocardiograms used by cardiologists at St. Francis Heart Hospital to diagnose wall-motion abnormalities were also described. The paper provides an overview of the proposed system, which was built on top of an algorithm that detects and tracks the inner and outer walls of the heart. It consists of a classifier that classifies the local region of the heart wall (and the entire heart) as normal or abnormal based on the wall motion. A methodology for feature selection and classification, followed by our experimental results was also described. The novel feature selection technique results in a robust hyperplane-based classifier that achieves the best performance in terms of AUC (area under the curve) and number of features selected when compared to three other well-known classification algorithms     

V-bending studies on sintered copper powder metallurgical preform sheets

Sintered sheet specimens of copper of varying mean preform densities were free-bent with four V-bending punch radii and dies to obtain free bending force and the springback, for comparison with their wrought equivalents. The objective of the above testing was to highlight the influence of porosity in accommodating the springback. Following the free bending, die bending was performed to arrive at the optimal die force to ensure minimal springback.     

Mechanical property measurements of nanoscale structures using an atomic force microscope

This paper describes nanometer-scale bending tests of fixed single-crystal silicon (Si) and silicon dioxide (SiO2) nanobeams using an atomic force microscope (AFM). The technique is used to evaluate elastic modulus of the beam materials and bending strength of the beams. Nanometer-scale Si beams with widths ranging from 200 to 800 nm were fabricated on a Si diaphragm using field-enhanced anodization using an AFM followed by anisotropic wet etching. Subsequent thermal oxidation of Si beams was carried out to create SiO2 beams. Results from the bending tests indicate that elastic modulus values are comparable to bulk values. However, the bending strength appears to be higher for these nanoscale structures than for large-scale specimens. Observations of the fracture surface and calculations of the crack length from Griffith's theory appear to indicate that the maximum peak-to-valley distance on the beam top surfaces influence the values of the observed bending strengths.