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101.
The issues involved in building dynamic, hard real-time systems, in which resource availability and requirements are not fixed, are discussed. It is shown that the problem of ensuring timing correctness in dynamic real-time systems has three aspects: resource requirements, resource availability, and guarantees. These issues overlap, and a single mechanism or technique may address several issues. The R-Shell, an object-oriented framework that structures resources in a class hierarchy so that they can be selected or substituted dynamically is described 相似文献
102.
A bioprocessing approach for the extraction of base, nuclear and precious metals from refractory and lean grade ores has been
reviewed in this paper. Characteristic morphological features ofThiobacillus ferrooxidans, the organism which has been extensively used for biooxidation of sulphide ores have been discussed. Mechanisms of chemoautotrophy
and mineral oxidation have been illustrated. The current engineering applications of this microorganism have also been brought
out. Various methods for accelerating the growth ofThiobacillus ferrooxidans for faster biooxidation and genetic manipulation for development of desired strains have been outlined. 相似文献
103.
R Solberg M Sandberg V Natarajan PA Torjesen V Hansson T Jahnsen K Taskén 《Canadian Metallurgical Quarterly》1997,138(1):169-181
104.
105.
Omar Hatamleh Joacim Beek Royce Forman Venkataraman Shivakumar Jed Lyons 《International Journal of Fracture》2005,134(3-4):251-265
A new numerical method based on the strip yield analysis approach was developed for calculating the Crack Tip Opening Displacement
(CTOD). This approach can be applied to any crack geometry, of either infinite or finite extent, with arbitrary applied loading
conditions. The technique is an adaptation of the dislocation-density based boundary element method to obtain crack-face opening
displacements at any point on a crack, and succeeds in obtaining the requisite values as a series of definite integrals, the
functional parts of each of which are evaluated exactly in closed form. The power of the technique is demonstrated by obtaining
solutions to several crack configurations of practical interest. 相似文献
106.
This article discusses immunization, development, vision, blood pressure, dentition, behavioral, and environmental screening for preschool children. The authors then discuss screening for children in the early school years. Injury and violence prevention and topics of sexuality for the preadolescent are also presented. 相似文献
107.
V. Natarajan M. Arivanandhan P. Anandan K. Sankaranarayanan G. Ravi Y. Inatomi Y. Hayakawa 《Materials Chemistry and Physics》2014
Melt growth of benzophenone was in-situ observed under various cooling rate and temperature gradient. The melt growth experiments were performed for various cooling rate of melt and various temperature gradients. The movement of growth interface with time was measured for various growth faces such as (001), (101) and (011) and the growth rates of the respective faces were calculated. It was found that the growth rate of all the faces increased with cooling rate of the melt. Steady state growth was observed in the experiments with low temperature gradient while, the steep gradient leads to unstable growth of crystal. The observed growth rate variation was explained using the attachment energy model. 相似文献
108.
The reaction of O(3P) with H2 has been studied behind reflected shock waves in the temperature range of 1713–3532K at total pressures of about 1.4–2.0 bar by Atomic Resonance Absorption Spectroscopy using mixtures of N2O and H2 highly diluted in Ar. The O atoms were generated by the fast thermal decomposition of N2O and the reaction with H2 was followed by monitoring the time dependent O and H atom concentrations in the postshock reaction zone. For the experimental conditions chosen, the measured O and H atom concentrations were primarily sensitive to the well-known N2O dissociation and to the studied reaction and hence its rate coefficient could be deduced. The measured rate coefficient data are fitted by the least-squares method to obtain the following three parameter expression: K4=3.72×106(T/K)2.17exp(−4080K/T)cm3 mol−18−, which is in excellent agreement with the recent ab initio calculations for the rate coefficient of this reaction in the overlapping temperature range. The present result is also compared to the experimental results reported by earlier investigators. 相似文献
109.
One dimensional nanofibers of organic and inorganic materials have been used in filters, optoelectronic devices, sensors etc. It is difficult to obtain ultra fine fibers of inorganic materials having lengths in the order of millimeter as they tend to break during formation due to thermal and other mechanical stresses. In this study, we have investigated the mechanism to prevent the defect formation and the breaking ZnO nanofibers by using optimized heat flow rates. ZnO nanofibers were obtained by heat treating the PVA composites fibers formed by electrospinning. The morphology and structural characteristic of prepared samples were investigated by Scanning electron microscopy and X-ray diffraction. It was found that the morphology of the composite and annealed nanofibers could be influenced by the concentration of the polymer content and heat flow rate during thermal treatment respectively. A lower concentration favors the formation of defects along the fiber and the number of defects reduces when the concentration is increased. The reasons for the formation of defects and their reduction, and the observed structural changes of ZnO nanofibers during heat treatment are also discussed. 相似文献
110.
Here we report an approach to fabricate flexible polymer self standing films embedded with continuous aligned microtubes/microchannels via electrospinning. The scheme is to wash the electrospun fibers selectively to form either microtubes/microchannels. Optical microscope (OM) and Scanning electron microscope images are evident for the well aligned microtubes and microchannels respectively with a diameter of ~ 8 μm and a length of ~ 4 cm. Meniscus of tetrahydrofuran in the microtubes can be observed explicitly in the OM images. Mutually perpendicular microtubes are also fabricated on a polymer film. Angular distribution of aligned microstructures indicates the standard deviation is not more than 1°. These tubes/channels can be potential for tissue engineering as they could provide a directional template for the growth when a biodegradable polymer such as Poly(vinylalcohol) is used. 相似文献