Search results for "heterogeneous"
showing 10 items of 460 documents
Surface phase transitions at O and CO catalytic reaction on Pd(111)
2006
Abstract The model has been proposed to simulate numerically the reaction O + CO → CO2 and occurring phase transitions on Pd(1 1 1) surface. We calculate the phase diagram for this system by kinetic Monte Carlo method. It shows the phase transitions p ( 2 × 2 ) O → 3 × 3 R 30 O ° and p ( 2 × 2 ) O → 3 × 3 R 30 O ° → p ( 2 × 1 ) O with increase of CO coverage for room and intermediate temperatures, respectively, while in the low temperature limit the direct p(2 × 2)O → p(2 × 1)O phase transition is observed. We demonstrate that the reaction rate is the crucial factor determining the occurrence of the p(2 × 1)O phase and vanishing of the 3 × 3 R 30 O ° with decrease of temperature. The result…
How much space for communication is there for a low achieving student in a heterogeneous group ?
2015
International audience; This paper reports on a case study aiming to deepen our understanding of low achieving students' learning of algebra, in particular when they work with pattern problems. We observed one low achieving student, May, who participated and worked in three different heterogeneous settings. Data were analysed from a multimod-al perspective on key and regulating activities in the groups. The analysis revealed that May's contribution varied, depending on the composition of the groups, and that her contributions were influenced by regulating activities by peers and access to physical artefacts. The findings show that a low achieving student is able to generalise beyond her ari…
Achieving Ultra Reliable Communication in 5G Networks: A Dependability Perspective Availability Analysis in the Space Domain
2017
As part of the 5G communication paradigm, ultra reliable communication (URC) is envisaged as an important technology pillar for providing anywhere and anytime services to end users. While most existing studies on reliable communication do not investigate this problem from a dependability theory perspective, those dependability-based studies tend to define reliability merely in the time domain. In this letter, we advocate extending the concept of URC from the dependability perspective also in the space domain . We initiate definitions on cell availability and system availability. The availability and the probability of providing a guaranteed level of availability in a network are analyzed bo…
Exploring the catalytic performance of a series of bimetallic MIL-100(Fe, Ni) MOFs
2019
[EN] A series of mixed-metal Fe-III/Ni-II metal-organic frameworks (MOFs) of the MIL-100 type containing different metal ratios have been synthesized de novo, following an approach that requires tuning of the Fe-III/Ni-II reactivity. The resulting heterometallic MIL-100(Fe, Ni) materials maintain thermal, chemical and structural stability with respect to the parent MIL-100(Fe) MOF as can be deduced from various techniques. The nature and the oxidation state of the accessible metal cations have been evaluated by in situ infrared spectroscopy and extended X-ray absorption fine structure measurements. The obtained mixed-metal MOFs and the parent material have been evaluated as heterogeneous ca…
Estimating radiant fields in flat heterogeneous photoreactors by the six-flux model
2006
Heterogeneous photoreactor modeling is a task complicated by the integro-differential nature of the Radiation Transfer Equation (RTE) when scattering phenomena are important. In the present work, a novel “Six Flux Model” (SFM) is proposed, which may be regarded as a step forward with respect to the previously proposed “Two Flux Model” (TFM). In order to validate the newly proposed model, Monte Carlo simulations of an indefinite plane-slab photoreactor have been performed. As no simplifying assumptions are involved in this case, the information obtained may be regarded as “pseudo-experimental,” and therefore compared with the predictions of both TFM and SFM models. Results show that the nove…
Preface
2009
This Special Issue of Catalysis Today includes selected papers presented at the 5th European Conference on Solar Chemistry & Photocatalysis: Environmental Applications (SPEA 5). The conference, held from 4th to 8th October 2008, was organized by Leonardo Palmisano and Vincenzo Augugliaro in Palermo (Italy). The 252 delegates (representing 757 authors) who came from many different European and non-European countries delivered four plenary lectures and 49 oral presentations. To emphasise the poster presentation, the 184 posters were briefly introduced by the appropriate Session Chairman before each oral sessions began. Both oral and poster presentations were divided into the following five to…
Evaluating Bluetooth Performance as the Support for Context-Aware Applications
2005
We present an experiment relative to the use of the Bluetooth wireless technology to provide network support for context-aware applications. We describe an approach to provide network interconnection using a combination of wireless and wired network technologies. We also describe the steps taken to create a Bluetooth based context-aware application. We, finally, evaluate, using a small test-bed and simulation the overall performance of this technology when adopted in the area of context-aware and ubiquitous computing.