Phenomenological investigation of sodium boiling in a SFR core during a postulated ULOF transient with CATHARE 2 system code: a stabilized boiling case

In the framework of the research and development on GEN IV sodium fast reactors (SFRs), the phenomenology of sodium boiling during a postulated unprotected loss of flow (ULOF) transient has been investigated with the CATHARE 2 system code. This study focuses on a stabilized boiling case: in such a regime, no flow redistribution occurs from the subassemblies which have reached the saturation temperature to those that are still single-phase. In this paper, for a subassembly design featuring no restrictive structures above the fuel bundle, a quasi-static approach is first developed to get an upper bound of the reactor core power at boiling onset that would be compatible with the well-known Ledinegg criteria for diphasic flow static equilibrium. Then, dynamics results achieved through simulation with the CATHARE 2 code for a postulated ULOF are presented: boiling is shown to remain stable during the transient for such a core power at boiling onset. Another important outcome of the simulation is the calculation of a dynamic instability, in the form of a two-phase hydrodynamic chugging phenomenon. The predicted phenomenology of this stabilized boiling case should be studied further in order to consider its dependency on the underlying closure laws and to eliminate the possibility of a numerical instability.     

Characterization and Mechanical Properties of Calcium Silicate/Citric Acid–Based Polymer Composite Materials

Optimal implants for bone tissue engineering require sufficient mechanical strength as well as apt bioactivity and biodegradability. Calcium silicate (CaSiO₃ ‐ CS) ceramics have been studied for tissue engineering and implantation for their good bioactivity properties. Elastomer poly (1.8‐octanediol citrate) (POC), one of the most biocompatible polymer, is used for biomedical application. The objective of this study is to fabricate a novel composite of calcium silicate with different ratios of POC to enhance the mechanical properties. The results showed that the compressive and the bending strengths of calcium silicate/POC biocomposite were improved remarkably at 40 wt% POC.     

Accuracy Testing of a Vehicle Proximity Warning System based on GPS and Wireless Networks

A vehicle proximity warning system is being developed using GPS and wireless local area networks to improve safety of off-highway trucks in open pit mines. After two years of research, software development, and laboratory testing, field-tests were performed at the Colorado School of Mines and in two open-pit operations to evaluate GPS accuracy and overall system effectiveness under rugged operating conditions. This paper discusses the methodology used for testing and presents a summary of results.     

Influence de l'oxygene et des ions chlorure sur le comportement electrochimique d'un alliage Fe---Ni (36 % Ni) en milieu acide et neutre

An investigation of the behaviour of a Fe---Ni alloy (64-36) was undertaken in sulfate solutions of pH from 1.7 to 9, and the effects of Cl⁻ ions and dissolved oxygen were examined. In the absence of these two species, the alloy is in the active state in the whole pH range and only becomes passive in neutral solutions at high concentrations of oxygen. Pitting was found to occur only in acidic solutions in the presence of Cl⁻ ions.     

Support Vector Learning for Semantic Argument Classification

The natural language processing community has recently experienced a growth of interest in domain independent shallow semantic parsing—the process of assigning a Who did What to Whom, When, Where, Why, How etc. structure to plain text. This process entails identifying groups of words in a sentence that represent these semantic arguments and assigning specific labels to them. It could play a key role in NLP tasks like Information Extraction, Question Answering and Summarization. We propose a machine learning algorithm for semantic role parsing, extending the work of Gildea and Jurafsky (2002), Surdeanu et al. (2003) and others. Our algorithm is based on Support Vector Machines which we show give large improvement in performance over earlier classifiers. We show performance improvements through a number of new features designed to improve generalization to unseen data, such as automatic clustering of verbs. We also report on various analytic studies examining which features are most important, comparing our classifier to other machine learning algorithms in the literature, and testing its generalization to new test set from different genre. On the task of assigning semantic labels to the PropBank (Kingsbury, Palmer, & Marcus, 2002) corpus, our final system has a precision of 84% and a recall of 75%, which are the best results currently reported for this task. Finally, we explore a completely different architecture which does not requires a deep syntactic parse. We reformulate the task as a combined chunking and classification problem, thus allowing our algorithm to be applied to new languages or genres of text for which statistical syntactic parsers may not be available.Editors: Dan Roth and Pascale FungThis research was partially supported by the ARDA AQUAINT program via contract OCG4423B and by the NSF via grant IIS-9978025.     

Residential decision-making and satisfaction among new suburbanites in the Tallinn urban region, Estonia

The prevailing research into suburbanisation in former centrally planned countries explains suburban change by referring to macro-level factors that are evident in the transition from a centrally planned to a market economy. Findings show that in a neo-liberal environment, the public sector plays only a modest role in residential planning; the key players are developers and banks. This study takes a different approach by focusing on the micro-level factors that lead households to move from the city to new, post-Soviet suburban settlements, specifically in the Tallinn urban region of Estonia. A sample of data from the University of Tartu’s 2006 New Residential Areas Survey is herein analysed in order to ascertain the reasons for moving, the criteria used in the selection of a particular suburban settlement, and the subsequent levels of residential satisfaction. The results show that, for the period in question, housing adjustment moves were more prevalent than induced moves triggered by life-course changes. In addition, it was found that, generally, new suburbanites were satisfied with their housing and neighbourhoods. However, they were less satisfied with the provision of local services, especially when their new settlements lay at a distance from pre-transition settlements.     

Accurate and efficient numerical method for the analysis ofmultimode waveguide discontinuities

This paper presents an original approach to analyze multimode waveguide discontinuities. The generalized scattering parameters are determined by a matrix pencil moment method associated with efficient numerically multimode matched loads placed at each physical port of the discontinuities. The analysis of both microstrip-coupled lines and coplanar lines asymmetric discontinuities is presented and successfully compared to experiments and available published results     

Interaction between C3A,silica fume and naphthalene sulphonate superplasticiser in high performance concrete

In high performance concrete, fillers and superplasticisers are typically added to the binder system. It is clear that cement, filler and admixture interact, and influence concrete properties. By means of an experimental programme on concrete with different types of Portland cement, with and without partial cement replacement by silica fume, and considering a naphthalene sulphonate superplasticiser, the interaction between C₃A, silica fume and naphthalene sulphonate superplasticiser has been investigated.A higher C₃A content of the Portland cement leads to a higher required dosage of superplasticiser. Partial cement replacement by silica fume leads to an acceleration of the second hydration peak (hydration of C₃S). Early age strength development of the concrete is higher in case of a higher C₃A content.