Extracting Multilingual Lexicons from Parallel Corpora

The paper describes our recent developments in automatic extraction of translation equivalents from parallel corpora. We describe three increasingly complex algorithms: a simple baseline iterative method, and two non-iterative more elaborated versions. While the baseline algorithm is mainly described for illustrative purposes, the non-iterative algorithms outline the use of different working hypotheses which may be motivated by different kinds of applications and to some extent by the languages concerned. The first two algorithms rely on cross-lingual POS preservation, while with the third one POS invariance is not an extraction condition. The evaluation of the algorithms was conducted on three different corpora and several pairs of languages.     

An Efficient Stochastic Clustering Auction for Heterogeneous Robotic Collaborative Teams

Stochastic Clustering Auctions (SCAs) constitute a class of cooperative auction methods that enable improvement of the global cost of the task allocations obtained with fast greedy algorithms. Prior research had developed Contracts Sequencing Algorithms (CSAs) that are deterministic and enable transfers, swaps, and other types of contracts between team members. In contrast to CSAs, SCAs use stochastic transfers or swaps between the task clusters assigned to each team member and have algorithm parameters that can enable tradeoffs between optimality and computational and communication requirements. The first SCA was based on a “Gibbs Sampler” and constrained the stochastic cluster reallocations to simple single transfers or swaps; it is applicable to heterogeneous teams. Subsequently, a more efficient SCA was developed, based on the generalized Swendsen-Wang method; it achieves the increased efficiency by connecting tasks that appear to be synergistic and then stochastically reassigning these connected tasks, hence enabling more complex and efficient movements between clusters than the first SCA. However, its application was limited to homogeneous teams. The contribution of this work is to present an efficient SCA for heterogeneous teams; it is based on a modified Swendsen-Wang method. For centralized auctioning and homogeneous teams, extensive numerical experiments were used to provide a comparison in terms of costs and computational and communication requirements of the three SCAs and a baseline CSA. It was seen that the new SCA maintains the efficiency of the second SCA and can yield similar performance to the baseline CSA in far fewer iterations. The same metrics were used to evaluate the performance of the new SCA for heterogeneous teams. A distributed version of the new SCA was also evaluated in numerical experiments. The results show that, as expected, the distributed SCA continually improves the global performance with each iteration, but converges to a higher cost solution than the centralized SCA. The final discussion outlines a systematic procedure to use SCA in various aspects of the application of multi-robot cooperative systems.     

Basic properties mapping of anodic oxides in the hafnium–niobium–tantalum ternary system

A thin film combinatorial library deposited by co-sputtering of Hf, Nb and Ta was employed to characterise fundamental properties of the Hf-Nb-Ta system. Compositional mappings of microstructure and crystallography revealed similarities in alloy evolution. Distinct lattice distortion was observed upon addition of hexagonal Hf, leading to amorphisation of alloys containing more than 32 at.% Hf and less than 27 and 41 at.% Nb and Ta, respectively. Volta potential and open circuit potential mappings indicated minimal values for the highest Hf concentration. Localised anodisation of the library by scanning droplet cell microscopy revealed valve metal behaviour. Oxide formation factors above 2 nm V^?1 were identified in compositional zones with high amounts of Nb and Ta. Fitting of electrochemical impedance spectroscopy data allowed electrical permittivity and resistivity of mixed oxides to be mapped. Their compositional behaviours were attributed to characteristics of the parent metal alloys and particularities of the pure oxides. Mott–Schottky analysis suggested n-type semiconductor properties for all Hf–Nb–Ta oxides studied. Donor density and flat-band potential were mapped compositionally, and their variations were found to be related mainly to the Nb amount. Synergetic effects were identified in mappings of Hf-Nb-Ta parent metals and their anodic oxides.     

Possible mercury speciation in urine samples using potentiometric methods

The strong dependence of heavy metal toxicity on metal physical–chemical structure has directed the interest in the qualitative and quantitative measurement of metal species in different environments. Mercury is ubiquitous in the environment, and occurs in three oxidation states in several physical and chemical forms. Among these, Hg(II) can severely damage the kidneys and the gastrointestinal tract, and is generally a serious hazard to human health. Potentiometric sensors based on ion-selective electrodes provide a simple, highly selective, precise, and economical method for online Hg(II) concentration monitoring in a variety of environments. Due to their selectivity, neutral carrier-based potentiometric sensors are routinely used for measuring ions directly in complex biological and environmental samples, and therein, several Hg(II)-selective electrodes have been studied in literature. This work presents a Hg(II) ion-selective electrode that uses a 1,4,8,11-tetrathiacyclotetradecane derivative entrapped inside a membrane for the measurement of Hg(II) in urine samples. Alumina modified dimethyl sulfoxide (AMDMSO) was used to separate Hg(II) from matrices, a mechanism already suggested in literature explaining the unique uptake of Hg(II) ions by binding as neutral at pH values < 3.     

Micellization of pH‐sensitive poly(butadiene)‐block‐poly(2 vinylpyridine)‐block‐poly(ethylene oxide) triblock copolymers: Complex formation with anionic surfactants

The micellization of three tailor‐made triblock copolymers, such as PB₁₀₀–P2VP₁₀₀–PEO₁₀₄, PB₁₈₅–P2VP₁₀₈–PEO₁₅₄, and PB₃₇–P2VP₁₁₅–PEO₂₄₁, having similar total molecular weights and constant poly(2‐vinylpyridine) (P2VP) sequence lengths, was investigated as a function of pH and sodium dodecyl sulfate (SDS) concentration. At pH 7 the formation of intermicellar aggregates was observed, especially for copolymers of low poly(ethylene oxide) (PEO) content. A pH decrease from 7 to 3 leads to a particle size increase due to the electrostatic repulsion of the protonated P2VP chains. The influence of the PEO sequence length was also observed for zeta potential values. At pH 3, in the absence of SDS, core–shell–corona micelles are formed whereas in the presence of small amount of SDS (degree of neutralization DN = 0%–50%), a complex is formed between SDS and the protonated P2VP which leads to the shrinkage of the shell and thus to a decrease of the micellar sizes. For higher DN values, the micellar sizes increase due to the formation of large agglomerates and a transition occurs from a monomodal to a bimodal size distribution. Furthermore, it turned out that secondary aggregation, such as intermicellar aggregation, can completely be avoided if the degree of polymerization (DPn) of the water‐soluble block is significantly higher than the DPn of the water‐insoluble sequence. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45313.     

Irradiation damage in 304 and 316 stainless steels: experimental investigation and modeling. Part I: Evolution of the microstructure

Irradiation damage in three austenitic stainless steels, SA 304L, CW 316 and CW Ti-modified 316, is investigated both experimentally and theoretically. The density and size of Frank loops after irradiation at 320 and 375 °C in experimental EBR II, BOR-60 and OSIRIS reactors for doses up to 40 dpa are characterized by TEM. The evolution of the initial dislocation network under irradiation is evaluated. A cluster dynamics model is proposed to account quantitatively for the experimental findings.     

Multiscale modelling of defect kinetics in irradiated iron.

Changes in microstructure and mechanical properties of nuclear materials are governed by the kinetics of defects produced by irradiation. The population of vacancies, interstitials and their clusters can however be followed only indirectly, for example by macroscopic resistivity measurements. The information on the mobility, recombination, clustering or dissociation of defects provided by such experiments is both extremely rich and difficult to interpret. By combining ab initio and kinetic Monte Carlo methods, we successfully reproduce the abrupt resistivity changes-so-called recovery stages-observed upon annealing at increasing temperatures after electron irradiation in alpha-iron. New features in the mechanisms responsible for these stages are revealed. We show that di-vacancies and tri-interstitials contribute to the stages attributed to mono-vacancy and di-interstitial migration respectively. We also predict the effect of the unexpected low migration barriers found for tri- and quadri-vacancies, and discuss the challenging questions raised by the mobility of larger defect clusters.