963 research outputs found
Applying quantitative semantics to higher-order quantum computing
Finding a denotational semantics for higher order quantum computation is a
long-standing problem in the semantics of quantum programming languages. Most
past approaches to this problem fell short in one way or another, either
limiting the language to an unusably small finitary fragment, or giving up
important features of quantum physics such as entanglement. In this paper, we
propose a denotational semantics for a quantum lambda calculus with recursion
and an infinite data type, using constructions from quantitative semantics of
linear logic
Constraints on filament models deduced from dynamical analysis
The conclusions deduced from simultaneous observations with the Ultra-Violet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission satellite, and the Multichannel Subtractive Double Pass (MSPD) spectrographs at Meudon and Pic du Midi observatories are presented. The observations were obtained in 1980 and 1984. All instruments have almost the same field of view and provide intensity and velocity maps at two temperatures. The resolution is approx. 0.5 to 1.5" for H alpha line and 3" for C IV. The high resolution and simultaneity of the two types of observations allows a more accurate description of the flows in prominences as functions of temperature and position. The results put some contraints on the models and show that dynamical aspects must be taken into account
Diffusion of fission products and radiation damage in SiC
A major problem with most of the present nuclear reactors is their safety in terms of
the release of radioactivity into the environment during accidents. In some of the
future nuclear reactor designs, i.e. Generation IV reactors, the fuel is in the form of
coated spherical particles, i.e. TRISO (acronym for Triple Coated Isotropic) particles.
The main function of these coating layers is to act as diffusion barriers for radioactive
fission products, thereby keeping these fission products within the fuel particles, even
under accident conditions. The most important coating layer is composed of
polycrystalline 3C-SiC. This paper reviews the diffusion of the important fission
products (silver, caesium, iodine and strontium) in SiC. Because radiation damage
can induce and enhance diffusion, the paper also briefly reviews damage created by
energetic neutrons and ions at elevated temperatures, i.e. the temperatures at which
the modern reactors will operate, and the annealing of the damage. The interaction
between SiC and some fission products (such as Pd and I) is also briefly discussed.
As shown, one of the key advantages of SiC is its radiation hardness at elevated
temperatures, i.e. SiC is not amorphized by neutron or bombardment at substrate
temperatures above 350°C. Based on the diffusion coefficients of the fission products
considered, the review shows that at the normal operating temperatures of these new
reactors (i.e. less than 950°C) the SiC coating layer is a good diffusion barrier for
these fission products. However, at higher temperatures the design of the coated
particles needs to be adapted, possibly by adding a thin layer of ZrC.http://iopscience.iop.org/hb201
A weakly-intrusive multi-scale substitution method in explicit dynamics
For virtual testing of composite structures, the use of fine modeling seems preferable to simulate complex mechanisms
like delamination. However, the associated computational costs are prohibitively high for large structures.
Multi-scale coupling techniques aim at reducing such computational costs, limiting the fine model only where necessary.
The dynamic adaptivity of the models represents a crucial feature to follow evolutive phenomena. Domain
decomposition methods would have to be combined with re-meshing strategies, that are considered intrusive implementations
within commercial software. Global-local approaches are considered less intrusive, because they allow
one to use a global coarse model on the overall structure and a fine local patch eventually adapted to cover the
interest zone. In our work, we developed a global-local coupling method for explicit dynamics, presented in [1] and
[2] and implemented in Abaqus/Explicit via the co-simulation technique for the simulation of delamination under
high velocity impact
A fast weakly intrusive multiscale method in explicit dynamics
This paper presents new developments on a weakly intrusive approach for the simplified implementation of space and time multiscale methods within an explicit dynamics software. The 'substitution' method proposed in previous works allows to take advantage of a global coarse model, typically used in an industrial context, running separate, refined in space and in time, local analyses only where needed. The proposed technique is iterative, but the explicit character of the method allows to perform the global computation only once per global time step, while a repeated solution is required for the small local problems only. Nevertheless, a desirable goal is to reach convergence with a reduced number of iterations. To this purpose, we propose here a new iterative algorithm based on an improved interface inertia operator. The new operator exploits a combined property of velocity Hermite time interpolation on the interface and of the central difference integration scheme, allowing the consistent upscaling of interface inertia contributions from the lower scale. This property is exploited to construct an improved mass matrix operator for the interface coupling, allowing to significantly enhance the convergence rate. The efficiency and robustness of the procedure are demonstrated through several examples of growing complexity. Copyright {\copyright} 2014 John Wiley \& Sons, Ltd
The production of reduced-alcohol wines using Gluzyme Mono® 10.000 BG-treated grape juice
High alcohol wines have become a major challenge in the international wine trade. Several physical processes areused to produce wines with reduced-alcohol content, all of which involve the selective extraction of ethanol basedon volatility or diffusion. In this study, the possibility of Gluzyme Mono® 10.000 BG (Gluzyme) (Novozymes, SouthAfrica) to reduce the glucose content of synthetic grape juice before fermentation was investigated in order to producewine with reduced-alcohol content. Gluzyme is a glucose oxidase preparation from Aspergillus oryzae, currently usedin the baking industry. Glucose oxidase catalyses the oxidation of glucose to gluconic acid and hydrogen peroxide(H2O2) in the presence of molecular oxygen. Gluzyme was initially used in synthetic grape juice, where differentenzyme concentrations and factors influencing its efficiency were investigated under winemaking conditions. Theresults showed up to 0.5% v/v less alcohol at an enzyme concentration of 20 kU compared to the control samples.This reduction in alcohol was increased to 1 and 1.3% v/v alcohol at pH 3.5 and pH 5.5 respectively in aerated (8mg/L O2) synthetic grape juice using 30 kU enzyme. Secondly, Gluzyme was used to treat Pinotage grape mustbefore fermentation. Gluzyme-treated wines at 30 kU enzyme concentration after fermentation contained 0.68%v/v less alcohol than the control wines. A decrease in acetic acid concentration of the treated compared to controlwines was also observed
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