Dependence of dc and ac conduction on the pre-sintering temperature in sol–gel derived Ba0.5Sr0.5TiO3 thin films

The effect of pre-sintering temperature on the activation energies of dc and ac conduction in sol–gel spin-coated Ba_0.5Sr_0.5TiO₃ (BST) thin films is reported in this paper. Layer by layer coating of BST sol on Pt/TiN/SiO₂/Si substrates was done with varying pre-sintering temperatures (drying temperature for individual layers). Dominant mechanism of dc conduction was identified as Schottky process whereas ac conduction was governed by trap controlled hopping process. The activation energy for dc conduction decreased from 0.45 to 0.38 eV with increase in the pre-sintering temperature from 400 to 600 °C; whereas, that for ac conduction increased from 0.17 to 0.21 eV. The results have been correlated with grain growth phenomena and reduction of oxygen vacancies in the films with increase in the pre-sintering temperature.     

Room-temperature optically-pumped GaSb quantum well based VCSEL monolithically grown on Si (100) substrate

Monolithic vertical cavity surface emitting lasers (VCSELs) on Si are demonstrated. The GaSb multi-quantum well active region embedded in an Al(Ga)Sb half-wave cavity spacer layer enables lasing under room-temperature optically-pumped conditions. The 13% lattice mismatch is accommodated by a spontaneously formed 2-D array of 90/spl deg/ misfit dislocations at the AlSb/Si interface. This growth mode produces very low defect density (/spl sim/8/spl times/10/sup 5//cm/sup 2/) and relaxed materials growth (98%) without the use of a buffer layer. Presented are VCSEL lasing spectra, light-in against light-out curves along with defect density measurements performed by microscopy and etch-pit density. A threshold excitation density of I/sub th/=0.1 mJ/cm/sup 2/ and a multimode lasing spectrum peaked at 1.62 /spl mu/m, results from a 3 mm pump-spot size.     

View and space management on large displays

This article describes the canvas portal framework that facilitates the development of alternative view-based space-management techniques on large displays. Implementations of the framework provide layout management, context switching, and space creation. The canvas portals are alternative views of display canvas areas where interacting with the portal's interior is equivalent to interacting with the depicted display area. To illustrate the generality of the canvas portals concept, we've instantiated a representative sample of existing large-display interaction techniques within the canvas portal design space, and developed several interaction techniques that address some of the challenges in new ways.     

Effects of Layer Thickness and Density on Settlement and Lateral Spreading

This paper presents the results of six large-scale centrifuge model tests that were performed to study the effect of relative density and thickness of sand layers on the amount of settlement and lateral spreading. The models included a “river” channel with clay flood banks underlain by layers of loose and dense sand of variable thickness, and a bridge abutment surcharge on one of the banks. The model container was tilted to provide an overall slope to the model. Each model was subjected to three or four significant ground motion events, which were obtained by scaling the amplitude of recordings of the Kobe (1995) and Loma Prieta (1989) earthquakes. Several measurements of acceleration, pore water pressure, settlement, and lateral movement are presented. The liquefaction potential index and a deformation index, which combine the influences of depth, density, and layer thickness, were found to correlate reasonably well with liquefaction induced settlements and lateral deformations for the range of models tested and indicate that centrifuge results are consistent with field observations.     

Development of hybrid genetic algorithms for product line designs.

In this paper, we investigate the efficacy of artificial intelligence (AI) based meta-heuristic techniques namely genetic algorithms (GAs), for the product line design problem. This work extends previously developed methods for the single product design problem. We conduct a large scale simulation study to determine the effectiveness of such an AI based technique for providing good solutions and bench mark the performance of this against the current dominant approach of beam search (BS). We investigate the potential advantages of pursuing the avenue of developing hybrid models and then implement and study such hybrid models using two very distinct approaches: namely, seeding the initial GA population with the BS solution, and employing the BS solution as part of the GA operator's process. We go on to examine the impact of two alternate string representation formats on the quality of the solutions obtained by the above proposed techniques. We also explicitly investigate a critical managerial factor of attribute importance in terms of its impact on the solutions obtained by the alternate modeling procedures. The alternate techniques are then evaluated, using statistical analysis of variance, on a fairy large number of data sets, as to the quality of the solutions obtained with respect to the state-of-the-art benchmark and in terms of their ability to provide multiple, unique product line options.     

Evaluation of anti‐bacterial activity of silver nanoparticles synthesised by coprophilous fungus PM0651419

The study explored biological synthesis of metallic silver nanoparticles (AgNPs) from the less explored non‐pathogenic coprophilous fungus, sterile mycelium, PM0651419 and evaluates the antimicrobial efficacy of biosynthesised AgNPs when impregnated in wound fabrics and in combination with six antimicrobial agents. AgNPs alone proved to be potent antibacterial agents and in combination they enhanced the antibacterial activity and spectrum of antibacterials used in the study against a microbiologically diverse battery of Gram positive, Gram negative and multidrug‐resistant bacteria. AgNPs impregnated on the wound dressings established their antibacterial activity by significantly reducing the bacterial load of pathogenic bacteria like Staphylococcus aureus and Bacillus subtilis e stablishing potential as effective antimicrobial wound dressings for treatment of polymicrobial wound infections. This study presents the first report on the potential of biosynthesis of AgNPs from the under explored class of coprophilous fungi. Their promise to be used in wound dressings and as potent antibacterials alone and in combination is evaluatedInspec keywords: silver, nanoparticles, nanofabrication, nanomedicine, biomedical materials, microorganisms, antibacterial activity, wounds, fabricsOther keywords: antibacterial activity, coprophilous fungus PM0651419, biological synthesis, metallic silver nanoparticles, nonpathogenic coprophilous fungus, sterile mycelium, antimicrobial efficacy, biosynthesised AgNPs, wound fabrics, microbiologically diverse battery, Gram positive bacteria, Gram negative bacteria, multidrug‐resistant bacteria, wound dressings, bacterial load, pathogenic bacteria, Staphylococcus aureus, Bacillus subtilis, polymicrobial wound infections, Ag     

Implementation of an inquisitive chatbot for database supported knowledge bases

Chatbot is a piece of software that responds to natural language input and attempts to hold a conversation in a way that imitates a real person. Some chatbots are used for entertainment purposes, while others for business and commercial purposes. Chatbots are getting a lot of attention from business community right now as they can save costs in customer service centers and can handle multiple clients at a time. Successful implementation of a chatbot calls for correct analysis of user’s query by the bot and the formation of the correct response that should be given to the user. In many scenarios the information available from the user’s query is inadequate to provide the answer. In such contexts, the chatbot needs to be inquisitive so that it will be more interactive and can mimic a more natural human interaction. This paper reports the implementation of an inquisitive chatbot, which finds the missing data in query and probes the questions to users to collect data that are required to answer the query. Through this implementation, the level of interactivity between the user and the chatbot is improved.     

Recurrence relations for bivariate and extended skew- distributions and an application to order statistics from bivariate

In this paper, we derive recurrence relations for cumulative distribution functions (cdf’s) of bivariate t and extended skew-t distributions. These recurrence relations are over ν (the degrees of freedom), and starting from the known results for ν=1 and ν=2, they will allow for the recursive evaluation of the distribution function for any other positive integral value of ν. Then, we consider a linear combination of order statistics from a bivariate t distribution with an arbitrary mean vector and show that its cdf is a mixture of cdf’s of the extended skew-t distributions. This mixture form, along with the explicit expressions of the cdf’s of the extended skew-t distributions, enables us to derive explicit expressions for the cdf of the linear combination for any positive integral value of ν.     

Where Am I? How Can I Get There? Impact of Navigability and Narrative Transportation on Spatial Presence

From video games to virtual worlds on the World Wide Web, modern media are becoming increasingly spatial, with users traversing artificial spaces and experiencing a kind of immersion known as “spatial presence.” But how do these media induce spatial presence? Are the affordances for movement provided by these technologies responsible for this illusion? Or do narratives that accompany them persuade us to suspend disbelief and transport ourselves into a virtual space? We explore these theoretical questions by pitting the navigability affordances of a video game against narrative transportation and examining their relative contributions to the formation of spatial presence in a virtual reality context. Results from a large experiment (N = 240) reveal that the narrative actually detracts from spatial presence while traversibility (in the form of greater degrees of steering motion) enhances it even without invoking a mental model of the portrayed environment. Theoretical and practical implications are discussed.     

Effect of high thermal expansion glass infiltration on mechanical properties of alumina-zirconia composite

This work studies the effect on the mechanical properties of alumina-10 wt% zirconia (3 mol% yttria stabilized) composite by infiltrating glass of a higher thermal expansion (soda lime glass) on the surface at high temperature. The glass improved the strength of composite at room temperature as well as at high temperature. This could be attributed to the drastic drop in the coefficient of thermal expansion due to the compositional change in the soda lime glass during infiltration. There was a significant improvement in the Weibull modulus after glass infiltration. Glass infiltrated samples showed better thermal shock resistance. The magnitude of strength increment was found to be in the order of the surface residual stress generated by thermo-elastic properties mismatch between the composite and the penetrated glass.