Polymere Nanoverbundwerkstoffe: Chancen,Risiken und Potenzial zur Verbesserung der mechanischen und physikalischen Eigenschaften

Polymer Nanocomposites: chances, risks and potential to improve the mechanical and physical properties The development of nano‐particle reinforced polymer composites is presently seen as one of the most promising approaches of materials for future engineering applications. The unique properties of at least some types of the nano‐particles (e.g., Carbon Nanotubes or Carbon Black) and the possibility of combining them with conventional materials and reinforcements (e.g., carbon‐, glass‐ or aramid‐fibres), has led to an intense research in the field of nanocomposites. Especially Carbon Nanotubes have shown a high potential for an improvement of the properties of polymers. Besides an increase in the electrical conductivity even at an extremely low nanotube content the improvement of the mechanical properties is of special interest. The exceptionally high aspect ratio in combination with a low density and a high strength and stiffness make the carbon nanotubes a most interesting candidate for a reinforcement of polymeric materials. The electrical, mechanical and thermal properties of Carbon Nanotubes open up new perspectives also for their use as multifunctional materials, e.g. conductive polymers with improved mechanical performance. The problem, however, is to transfer the interesting potential regarding the mechanical, thermal and electrical properties to the polymer. Two main issues have to be addressed for a significant improvement of the properties of polymers by adding Carbon Nanotubes: the interfacial bonding and, especially also, a proper dispersion of the individual Carbon Nanotubes in the polymeric matrix.     

Fuzzy two-step filter for impulse noise reduction from color images.

A new framework for reducing impulse noise from digital color images is presented, in which a fuzzy detection phase is followed by an iterative fuzzy filtering technique. We call this filter the fuzzy two-step color filter. The fuzzy detection method is mainly based on the calculation of fuzzy gradient values and on fuzzy reasoning. This phase determines three separate membership functions that are passed to the filtering step. These membership functions will be used as a representation of the fuzzy set impulse noise (one function for each color component). Our proposed new fuzzy method is especially developed for reducing impulse noise from color images while preserving details and texture. Experiments show that the proposed filter can be used for efficient removal of impulse noise from color images without distorting the useful information in the image.     

Cylindrically etched carbon-fiber microelectrodes for low-noise amperometric recording of cellular secretion

The most important sources of noise with disk-shaped carbon-fiber microelectrodes (CFMEs) are the exposed cut disk face of the fiber itself and the seal region between the carbon fiber and the applied insulating layer. To reduce noise and to fabricate simple, reproducible low-noise CFMEs, we sealed commercially available carbon fibers in pulled glass pipets and then we performed cylindrical etching of the fiber extending beyond the glass sheath, followed by insulation with anodic electrophoretic deposition of paint. The resulting CFMEs had electroactive carbon disks with radii as small as ～0.5 μm. The noise of such electrodes was minimized by virtue of a design that ensures a good seal between the carbon fiber and its insulation and a reduced diameter of the exposed carbon. In contrast to CFMEs made of conically etched carbon fibers, cylindrically etched CFMEs offer the significant advantage that they can be easily reused: The cylindrically etched region extends over several hundreds of micrometers and, therefore, can be cut back repeatedly to expose a fresh carbon surface of uniform diameter. The low noise and small size of these electrodes make them ideal for the high-sensitivity measurements demanded in studies of single-vesicle transmitter release from secretory cells. Furthermore, the small cross-sectional diameter of the tips allows them to be used in restricted spaces, such as inside the tapering micrometer-diameter tips of melted and pulled glass microcapillaries (e.g., patch pipets).     

Design Rules for Laser‐Treated Icephobic Metallic Surfaces for Aeronautic Applications

Ice accretion on external aircraft surfaces due to the impact of supercooled water droplets can negatively affect the aerodynamic performance and reduce the operational capability and, therefore, must be prevented. Icephobic coatings capable of reducing the adhesion strength of ice to a surface represent a promising technology to support thermal or mechanical ice protection systems. Icephobicity is similar to hydrophobicity in several aspects and superhydrophobic surfaces embody a straightforward solution to the ice adhesion problem. Short/ultrashort pulsed laser surface treatments are proposed as a viable technology to generate superhydrophobic properties on metallic surfaces. However, it has not yet been verified whether such surfaces are generally icephobic under representative icing conditions. This study investigates the ice adhesion strength on Ti6Al4V, an alloy commonly used for aerospace components, textured by means of direct laser writing, direct laser interference patterning, and laser‐induced periodic surface structures laser sources with pulse durations ranging from nano‐ to femtosecond regimes. A clear relation between the spatial period, the surface microstructure depth, and the ice adhesion strength under different icing conditions is investigated. From these observations, a set of design rules can be defined for superhydrophobic surfaces that are icephobic, too.     

ShutterApp: Spatio‐temporal Exposure Control for Videos

A camera's shutter controls the incoming light that is reaching the camera sensor. Different shutters lead to wildly different results, and are often used as a tool in movies for artistic purpose, e.g., they can indirectly control the effect of motion blur. However, a physical camera is limited to a single shutter setting at any given moment. ShutterApp enables users to define spatio‐temporally‐varying virtual shutters that go beyond the options available in real‐world camera systems. A user provides a sparse set of annotations that define shutter functions at selected locations in key frames. From this input, our solution defines shutter functions for each pixel of the video sequence using a suitable interpolation technique, which are then employed to derive the output video. Our solution performs in real‐time on commodity hardware. Hereby, users can explore different options interactively, leading to a new level of expressiveness without having to rely on specialized hardware or laborious editing.     

H2O2 / O3, H2O2 / UV And H2O2 / Fe2+ Processes For The Oxidation Of Hazardous Wastes

Activated hydrogen peroxide produces very reactive OH-radicals which destroy hazardous contaminants in water. The principles and different methods of activation are described. Results from laboratory studies show the numerous applications of this new technology. A successful scaleup of laboratory tests to an industrial level is discussed. Finally, a cost estimate for treating different types of water with hydrogen peroxide is presented.     

An investigation of the diffraction of waves by complementary infinite double-sectors

Contents In this paper we treat the diffraction by infinite double-sectors. The scalar boundary value problem as well as the electromagnetic boundary value problem is solved using the problem adapted sphero-conal coordinate system. We determine appropriate eigenfunctions and we find a remarkable relation between the eigenvalues of complementary double-sectors due to Babinet's principle. Additionally we consider the diffraction of a plane wave normally incident upon the double-sector for the scalar and for the electromagnetic case.

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Eine Untersuchung der Beugung von Wellen an komplementären unendlich ausgedehnten Doppelsektoren

Übersicht In dieset Arbeit wird die Beugung an unendlich ausgedehnten Doppelsektoren untersucht. Sowohl das skalare wie auch das elektromagneticsche Randwert-problem werden in elliptischen Kegelkoordinaten als problemangepaßtem Koordinatensystem gelöst. Es werden geeignete Eigenfunktionen bestimmt, wobei sich für die Eigenwerte für zueinander komplementäre Doppelsektoren eine Symmetriebeziehung ergibt, welche dem Babinetschen Prinzip entspricht. Desweiteren wird die Beugung einer senkrecht einfallenden ebenen Welle am Doppelsektor für den skalaren wie auch für den elektromagnetischen Fall untersucht.