A fuzzy noise reduction method for color images.

A new fuzzy filter is presented for the reduction of additive noise for digital color images. The filter consists of two subfilters. The first subfilter computes fuzzy distances between the color components of the central pixel and its neighborhood. These distances determine in what degree each component should be corrected. All performed corrections preserve the color component distances. The goal of the second subfilter is to correct the pixels where the color components differences are corrupted so much that they appear as outliers in comparison to their environment. Experimental results show the feasibility of the proposed approach. We compare with other noise reduction methods by numerical measures and visual observations. We also illustrate the performance of the proposed method as preprocessing step for edge detection.     

Visibility Sampling on GPU and Applications

In this paper, we show how recent GPUs can be used to very efficiently and conveniently sample the visibility between two surfaces, given a set of occluding triangles. We use bitwise arithmetics to evaluate, encode, and combine the samples blocked by each triangle. In particular, the number of operations is almost independent of the number of samples. Our method requires no CPU/GPU transfers, is fully implemented as geometric, vertex and fragment shaders, and thus does not impose to modify the way the geometry is sent to the graphics card. We finally present applications to soft shadows, and visibility analysis for level design.     

Inelastic scattering on spherical microparticles with inclusions

The subject of the paper is scattering at spherical microparticles with inclusions. The inclusions are represented as dipoles for both elastic and inelastic scattering. For elastic scattering the dipoles are computed iteratively, and sequence transformations are used to accelerate this iteration. Mie theory is used to calculate the cross sections for scattering on spherical microparticles with inclusions as well as on agglomerates.     

Imaging and elasticity measurements of the sarcolemma of fully differentiated skeletal muscle fibres

This study aimed to describe the three-dimensional structure and the elastic properties of the sarcolemma of adult, fully differentiated, skeletal muscle fibres combining Atomic Force Microscopy (AFM) and optical microscopy. Single fibres were enzymatically dissociated from Flexor Digitorum Brevis of adult mice and were maintained in culture up to 3 weeks. On the sixth day after dissociation, the upper surface of intact fibres, either alive in solution or fixed and kept in solution or fixed and exposed in air, was analysed with AFM. The most prominent features in AFM images were periodic transversal foldings with an interval that corresponded to the sarcomere length. More detailed analysis of the topography profile showed that the depth in the folding decreased with increasing sarcomere length and that the crests of the foldings corresponded to the Z-lines. Minor periodic structures could be detected in the valleys between the major foldings. AFM images also showed deep depressions on the sarcolemma likely corresponding to openings of T tubules and caveolae. Two-dimensional elasticity maps were obtained using AFM as an indenter and showed that the crests of the transversal foldings correspond to higher stiffness regions. This study provides the first complete three-dimensional topography and mechanical characterization of intact, living skeletal muscle fibres and might form the basis for further investigations aimed to compare healthy and dystrophic muscles.     

Characterization of wood-filled thermoplastic polyurethanes for the injection molding process

Fiber fillings of wood plastic composites (WPC) are almost exclusively limited to standard plastics such as polyethylene and polypropylene. At the Kunststofftechnik Paderborn of the University of Paderborn the wood fiber filling of engineering plastics is being promoted. WPC with different fiber types and fiber contents based on two thermoplastic polyurethanes (TPU) were compounded and subsequently characterized. We found that the physicochemical properties of the materials differ from standard plastic-based WPC. Wood filling with increasing fiber content did not immediately correlate with an increase in density. A decrease in density and swelling of the compound was detected with reaching a critical fiber content. Our compounds showed an increased water absorption at high-fiber contents over time, which can be described logarithmically. The observed viscosity curves obey the Ostwald and de Waele power law, but an increased viscosity at increased fiber content was not apparent for both TPU matrices.     

Toward efficient Cu(In,Ga)Se2 solar cells prepared by reactive magnetron co‐sputtering from metallic targets in an Ar:H2Se atmosphere

In this paper, we show that a reactive co‐sputtering process using metallic CuGa and In targets; an Ar:H₂Se atmosphere is well suited for the deposition of photoactive Cu(In,Ga)Se₂ (CIGSe) absorber layers for thin‐film solar cells in a single process step. The achievement of single‐phase and well‐crystallized layers is thereby no major problem if a sufficiently high H₂Se content and substrate temperatures in the range of 400–500 °C are used. However, in order to achieve the desired Cu‐poor film stoichiometry, which is crucial for the device performance, it has to be considered already that, at moderate substrate temperatures in the range of 400–500 °C, indium has a strong tendency to re‐evaporate from the film surface if the film composition is Cu‐poor. If excess indium is supplied, this effect can lead to a self‐adjustment of the film composition. This allows a very wide process window in a one‐stage process concerning the supply ratio from the two targets of [Cu]/([In] + [Ga])_supply ≈ 0.35–0.8. However, the maximum efficiencies achievable with such a process are limited to 11.7% because an adequate Cu‐poor composition can only be achieved with significant Cu‐poor conditions, which allow only a low material quality. By using an improved process with an intermediate Cu‐rich composition and a final Cu‐poor stage, the absorber quality could be significantly improved; efficiencies of up to 14.3% have been achieved with CIGSe films prepared on Na‐doped Mo back contacts. Copyright © 2015 John Wiley & Sons, Ltd.     

YAG(Ce) crystal characterization with proton beams

A YAG(Ce) crystal has been characterized with a proton beam up to 100 MeV. Tests were performed to investigate the possibility of using this detector as a proton calorimeter. A crystal size has been chosen that is able to stop up to 200 MeV. Energy resolution and light response have been measured at Laboratori Nazionali del Sud with a proton beam up to 60 MeV and a spatial homogeneity study of the crystal has been performed at Loma Linda University Medical Center with a 100 MeV proton beam. The YAG(Ce) crystal showed a good energy resolution equal to 3.7% at 60 MeV and measurements, performed in the 30-60 MeV proton energy range, were fitted by Birks' equation. Using a silicon tracker to determine the particle entry point in the crystal, a spatial homogeneity value of 1.7% in the light response has been measured.     

Novel ceramic–polymer composites synthesized by compaction of polymer-encapsulated TiO2-nanoparticles

A novel processing route for producing composites from ceramic particles and a thermoplastic polymer with high ceramic content was developed. Via a radical emulsion polymerization reaction in an aqueous suspension, titanium dioxide is encapsulated by a thin layer of poly(methyl methacrylate). Subsequently, the coated particles are compacted by applying high pressure (∼1 GPa) at a temperature above the glass transition temperature of the polymer (∼160 °C). This technique enables producing dense, hard and stiff composites at low processing temperatures. Microstructural investigations of composites by scanning electron microscopy confirm successful coating of titanium dioxide particles by polymer. Compositions were estimated from thermogravimetric measurements. A maximum TiO₂ volume content of almost 70% was achieved. For characterizing mechanical properties, Vickers microhardness as well as flexural strength and elastic modulus were determined. With respect to pure PMMA, composites exhibit a 10-fold increase in microhardness. Furthermore, a strong increase in elastic modulus with TiO₂ contents, up to 40 GPa at 66 vol.% TiO₂ was observed. These moduli are among the highest found in literature for ceramic polymer composites. However, bending strength of the material is still low.