3D structure of oil droplets in hardened geopolymer emulsions

Geopolymer (GP) cements have the ability to integrate huge amounts of organic oils by direct emulsion in the fresh paste. Moreover, the oil emulsion remains stable during GP hardening. This allows to design tailored GP/oil (GEOIL) composites for an array of industrial applications. Using 3D X-ray micro-Computed Tomography (micro-CT), this research determines the spatial distribution of an industrial oil emulsion inside a GP cement (emulsification in the fresh state, imaging in the hardened state), depending on the oil volume fraction (from 5% to 60% total volume). The oil droplet size distribution, mean distance between droplets, and connectivity of the oil system are determined quantitatively.     

Diffusion barrier properties of TaNx films prepared by plasma enhanced atomic layer deposition from PDMAT with N2 or NH3 plasma

Carbon free TaN_x films were deposited by plasma enhanced atomic layer deposition (PEALD) using a combination of pentakis(dimethylamino)Ta (PDMAT) and either N₂ or NH₃ plasma. Good linearity and saturation behavior were observed for the TaN_x films grown with NH₃ plasma while non-ideal saturation features were observed for the films grown with N₂ plasma. The thermal stability of the TaN_x films could be improved by reducing the pressure of the reactants and by increasing the plasma exposure time. The TaN_x films deposited using N₂ plasma exhibit better diffusion barrier properties than the films deposited using NH₃ plasma.     

Comparative study of three methods for the simulation of two-dimensional photonic crystals

Three methods for the efficient simulation of two-dimensional photonic crystal structures are compared, namely, a semianalytical multiple-scattering technique; a vectorial eigenmode expansion technique; and a FDTD-ROM technique. The basic principles of each method are presented. For the semianalytical technique and for the vectorial eigenmode expansion technique, we show how reflections coming from abruptly terminated waveguides can be avoided. The main advantages and disadvantages of each method are discussed. Results from use of the three methods are compared for several photonic crystal structures.     

From measured physical parameters to the haptic feeling of fabric

Abstract real-time cloth simulation involves the solution of many computational challenges, particularly in the context of haptic applications, where high frame rates are necessary for obtaining a satisfactory tactile experience. In this paper, we present a real-time cloth simulation system that offers a compromise between a realistic physically-based simulation of fabrics and a haptic application with high requirements in terms of computation speed. We place emphasis on architecture and algorithmic choices for obtaining the best compromise in the context of haptic applications. A first implementation using a haptic device demonstrates the features of the proposed system and leads to the development of new approaches for haptic rendering using the proposed approach.     

Aspect-oriented Programming for Dynamic Web Service Selection,Integration and Management

In service-oriented computing, applications are often created by integrating third-party Web Services. Current integration approaches, however, require client applications to hardcode references to specific Web Services, thereby affecting adaptability and robustness. Moreover, support for client-side management is rarely provided. To enable the development of more flexible and robust applications, we propose to insert a new layer between the client applications and the Web Services: the Web Services Management Layer (WSML). This layer decouples Web Services from client applications and enables hot-swapping between semantically equivalent Web Services based on availability. This mechanism allows for dynamic switching between Web Services based on selection policies that encapsulate changing business requirements. In addition, with WSML, client-side management concerns (e.g., caching, billing and logging) can be decoupled from the applications. In this paper, we identify a list of requirements for WSML to realize dynamic integration and client-side service management, and provide support for service criteria to govern the selection, integration and composition of Web Services. We also show that dynamic Aspect-Oriented Programming (AOP) is well suited to implement the core functionality of WSML.     

An introduction to fuzzy answer set programming

In this paper we show how the concepts of answer set programming and fuzzy logic can be successfully combined into the single framework of fuzzy answer set programming (FASP). The framework offers the best of both worlds: from the answer set semantics, it inherits the truly declarative non-monotonic reasoning capabilities while, on the other hand, the notions from fuzzy logic in the framework allow it to step away from the sharp principles used in classical logic, e.g., that something is either completely true or completely false. As fuzzy logic gives the user great flexibility regarding the choice for the interpretation of the notions of negation, conjunction, disjunction and implication, the FASP framework is highly configurable and can, e.g., be tailored to any specific area of application. Finally, the presented framework turns out to be a proper extension of classical answer set programming, as we show, in contrast to other proposals in the literature, that there are only minor restrictions one has to demand on the fuzzy operations used, in order to be able to retrieve the classical semantics using FASP.     

Influence of environmental conditions on carbonaceous particle concentrations within New Zealand

Variables that influence ambient concentrations of air particulate matter due to motor vehicle emissions and biomass burning for home heating were investigated for 10 urban environments in New Zealand. It was found that contributions to ambient particulate matter concentrations from these two main anthropogenic carbonaceous sources were only sometimes correlated with the population and/or source activity within an airshed. The average particulate concentration attributed to motor vehicle emissions was found to correlate with the airshed population, whereas the home heating contribution was observed to be independent. It was found that particulate matter from biomass burning for home heating emissions often build up during cold calm nights under temperature inversion conditions, restricting vertical dispersion thus confining air particulate matter to a limited atmospheric volume. The average winter particulate concentrations due to home heating within the airsheds studied were attributed more to environmental confinement rather than source activity.     

Mean atomic number and backscattered electron coefficient calculations for some materials with low mean atomic number

In modelling electron backscattering from solids using Monte Carlo simulations, knowledge of mean atomic number, mean atomic weight, and density of the bulk material are required. We studied four different ways in common useforthe calculation of mean atomic number. An alternative and improved approach is to calculate the mean backscattered electron (BSE) coefficient, η , from a knowledge of the elemental composition and values of η for the elements. Again, we studied a number of formulae suggested for this averaging process. As it is not possible to measure η directly for a number of elements, the method used to interpolate between elements with known η was also examined. In addition, we obtained experimental backscattering relationships for topography-free samples of poly (methylmethacrylate) (PMMA), carbon, aluminium, and a series of novel halogenated resins, all solids with relatively low mean atomic numbers, and calcified tissues. None of the methods for determining mean atomic number placed the materials of interest in the correct sequence of their experimentally determined BSE peaks: the data differed widely between the individual methods. The averaged BSE coefficient calculated by the Castaing formula gave the best agreement with the experimentally derived data.     

CW laser-initiated formation of nano-Si crystals in glass-metal nanostructures

Local and controllable growth of nanocrystalline silicon (nano-Si) in a commercial borosilicate glass is demonstrated. The nano-Si was formed in the subsurface region of the glass via aluminothermic reaction in the course of the irradiation of a 2D array of aluminum nanodisks fabricated on the glass surface with CW low-power 633 and 532 nm lasers. The thermoplasmonic nature of the nanodisks heating is demonstrated: at low incident intensity, the phenomenon takes place only if the plasmon resonance of the array and the laser wavelength is close enough. However, when the laser beam intensity at the sample surface exceeds 8 MW/cm² mutual position of the plasmon resonance and the laser wavelength weakly influences the phenomenon. The nano-Si formation is studied with Raman scattering technique, and the average size of the silicon nanocrystals is evaluated.