Informal and formal requirements specification languages: bridgingthe gap

The differences between informal and formal requirements specification languages are noted, and the issue of bridging the gap between them is discussed. Using structured analysis (SA) and the Vienna development method (VDM) as surrogates for informal and formal languages, respectively, two approaches are presented for integrating the two. The first approach uses the SA model of a system to guide the analyst's understanding of the system and the development of the VDM specifications. The second approach proposes a rule-based method for generating VDM specifications from a set of corresponding SA specifications. The two approaches are illustrated through a simplified payroll system case. The issues that emerge from the use of the two approaches are reported     

Metal distribution in alumina/aluminium composites synthesized by directed metal oxidation

The directed oxidation of molten aluminium alloys by vapour phase oxidants can be used to produce Al₂O₃/Al ceramic matrix composites. The toughness of these composites is determined by the amount and the nature of metal distribution in the composite. This paper addresses the problem of understanding the metal distribution in Al₂O₃/Al composites and its dependence on growth temperature. Electrical conductivities and microstructures of Al₂O₃/Al composites synthesized by directed oxidation of Al-5056 alloy are investigated. The high conductivity of the Al₂O₃/Al composite compared to sintered Al₂O₃-4 wt% MgO is shown as a proof of the presence of some continuous metal channels in the composite. The activation energy forthe diffusion of the dominant charge carrier in the oxide matrix is found to be 1.36 eV from the analysis of the conductivity data. Both the amount of metal in the composite and the extent of interconnection of the metal channels decrease with increasing growth temperature. The observed changes in microstructure with temperature can be explained by considering temperature variations of grain boundary energies in alumina and the alumina/aluminium interfacial energy. The metal content of the Al₂O₃/Al composites, prepared by directed oxidation of Al-5056 alloys, can be tailored by the choice of the growth temperature.     

Computer aided decision support system for mitral valve diagnosis and classification using depthwise separable convolution neural network

Multimedia Tools and Applications - The significance of mitral valve (MV) treatment is increasing recently because of an aging population. The computer vision-based acquisition and quantification...     

Long Duration Persistent Photocurrent in 3 nm Thin Doped Indium Oxide for Integrated Light Sensing and In-Sensor Neuromorphic Computation

Miniaturization and energy consumption by computational systems remain major challenges to address. Optoelectronics based synaptic and light sensing provide an exciting platform for neuromorphic processing and vision applications offering several advantages. It is highly desirable to achieve single-element image sensors that allow reception of information and execution of in-memory computing processes while maintaining memory for much longer durations without the need for frequent electrical or optical rehearsals. In this work, ultra-thin (<3 nm) doped indium oxide (In₂O₃) layers are engineered to demonstrate a monolithic two-terminal ultraviolet (UV) sensing and processing system with long optical state retention operating at 50 mV. This endows features of several conductance states within the persistent photocurrent window that are harnessed to show learning capabilities and significantly reduce the number of rehearsals. The atomically thin sheets are implemented as a focal plane array (FPA) for UV spectrum based proof-of-concept vision system capable of pattern recognition and memorization required for imaging and detection applications. This integrated light sensing and memory system is deployed to illustrate capabilities for real-time, in-sensor memorization, and recognition tasks. This study provides an important template to engineer miniaturized and low operating voltage neuromorphic platforms across the light spectrum based on application demand.     

An Efficient Security Framework for Trusted and Secure Routing in MANET: A Comprehensive Solution

Wireless Personal Communications - Secure routing of data in MANET (Mobile Ad-hoc Network) is an important concern to save the network from various attacks such as blackhole attack, wormhole...     

Mill scale as a potential additive to improve the quality of hematite ore pellet

Hematite pellet is required to be indurated at very high temperature to achieve its good strength as there is no exothermic heat of oxidation unlike magnetite. As mill scale contains mainly FeO and Fe₃O₄, any minor amount of its addition in pellet can provide in situ heat and enhance diffusion bonding and sintering. In this study, the mill scale generated in steel plant is added as magnetite input in hematite pellet both in acidic and in basic condition. It has been found that in fluxed pellet, mill scale can improve the properties of pellet. In acidic pellet, the induration temperature has been reduced to a great extent (1250–1275°C) and all properties have been found to be improved due to the addition of 15% mill scale. Mill scale shows enough potential to eliminate the flux addition in producing blast furnace quality pellet from hematite ore. Thus, the flux free acidic pellet has been developed even at very low temperature (1275°C) of induration.     

Characterization and properties of metallic iron nanoparticles: spectroscopy, electrochemistry, and kinetics

There are reports that nano-sized zero-valent iron (Fe0) exhibits greater reactivity than micro-sized particles of Fe0, and it has been suggested that the higher reactivity of nano-Fe0 may impart advantages for groundwater remediation or other environmental applications. However, most of these reports are preliminary in that they leave a hostof potentiallysignificant(and often challenging) material or process variables either uncontrolled or unresolved. In an effort to better understand the reactivity of nano-Fe0, we have used a variety of complementary techniques to characterize two widely studied nano-Fe0 preparations: one synthesized by reduction of goethite with heat and H2 (Fe(H2)) and the other by reductive precipitation with borohydride (Fe(BH)). Fe(H2) is a two-phase material consisting of 40 nm alpha-Fe0 (made up of crystals approximately the size of the particles) and Fe3O4 particles of similar size or larger containing reduced sulfur; whereas Fe(BH) is mostly 20-80 nm metallic Fe particles (aggregates of <1.5 nm grains) with an oxide shell/coating that is high in oxidized boron. The FeBH particles further aggregate into chains. Both materials exhibit corrosion potentials that are more negative than nano-sized Fe2O3, Fe3O4, micro-sized Fe0, or a solid Fe0 disk, which is consistent with their rapid reduction of oxygen, benzoquinone, and carbon tetrachloride. Benzoquinone-which presumably probes inner-sphere surface reactions-reacts more rapidly with FeBH than Fe(H2), whereas carbon tetrachloride reacts at similar rates with FeBH and Fe(H2), presumably by outer-sphere electron transfer. Both types of nano-Fe0 react more rapidlythan micro-sized Fe0 based on mass-normalized rate constants, but surface area-normalized rate constants do not show a significant nano-size effect. The distribution of products from reduction of carbon tetrachloride is more favorable with Fe(H2), which produces less chloroform than reaction with Fe(BH).     

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping

Separation of nickel from copper in ammoniacal/ammonium carbonate solution using ACORGA M5640 by selective stripping was carried out. The influence of equilibration time, equilibrium pH and extractant concentration on the extraction of both the metals was studied. It was found that the copper extraction equilibrium was reached in a shorter time than the nickel extraction equilibrium. Nickel extraction decreases above an equilibrium pH of 9.0, while the extraction of copper remains unaffected by the changes in the equilibrium pH range of 7–10. Co-extraction, ammonia scrubbing and the selective stripping of copper and nickel were performed for a solution containing 3 g/l each of copper and nickel and 60 g/l ammonium carbonate. The extraction and the percentage stripping of copper and nickel were almost quantitative.     

Nanostructured ceramics for biomedical implants

Recent progress in the synthesis, characterization, and biological compatibility of nanostructured ceramics for biomedical implants is reviewed. A major goal is to develop ceramic coating technology that can reduce the friction and wear in mating total joint replacement components, thus contributing to their significantly improved function and longer life span. Particular attention is focused on the enhancement of mechanical properties such as hardness, toughness, and friction coefficient and on the bioactivity as they pertain to the nanostructure of the material. The development of three nanostructured implant coatings is discussed: diamond, hydroxyapatite, and functionally graded metalloceramics based on the Cr-Ti-N ternary system. Nanostructured diamond produced by chemical vapor deposition (CVD) techniques and composed of nano-size diamond grains have particular promise because of the combination of ultrahigh hardness, improved toughness over conventional microcrystalline diamond, low friction, and good adhesion to titanium alloys. Nanostructured processing applied to hydroxyapatite coatings is used to achieve the desired mechanical characteristics and enhanced surface reactivity and has been found to increase osteoblast adhesion, proliferation, and mineralization. Finally, nanostructured metalloceramic coatings provide continuous variation from a nanocrystalline metallic bond at the interface to the hard ceramic bond on the surface and have the ability to overcome adhesion problems associated with ceramic hard coatings on metallic substrates.