Technische Universität Darmstadt

About: Technische Universität Darmstadt is a education organization based out in Darmstadt, Germany. It is known for research contribution in the topics: Computer science & Context (language use). The organization has 17316 authors who have published 40619 publications receiving 937916 citations. The organization is also known as: Darmstadt University of Technology & University of Darmstadt.

Highly-Ordered Supportless Three-Dimensional Nanowire Networks with Tunable Complexity and Interwire Connectivity for Device Integration

Abstract: The fabrication of three-dimensional assemblies consisting of large quantities of nanowires is of great technological importance for various applications including (electro-)catalysis, sensitive sensing, and improvement of electronic devices. Because the spatial distribution of the nanostructured material can strongly influence the properties, architectural design is required in order to use assembled nanowires to their full potential. In addition, special effort has to be dedicated to the development of efficient methods that allow precise control over structural parameters of the nanoscale building blocks as a means of tuning their characteristics. This paper reports the direct synthesis of highly ordered large-area nanowire networks by a method based on hard templates using electrodeposition within nanochannels of ion track-etched polymer membranes. Control over the complexity of the networks and the dimensions of the integrated nanostructures are achieved by a modified template fabrication. The networks possess high surface area and excellent transport properties, turning them into a promising electrocatalyst material as demonstrated by cyclic voltammetry studies on platinum nanowire networks catalyzing methanol oxidation. Our method opens up a new general route for interconnecting nanowires to stable macroscopic network structures of very high integration level that allow easy handling of nanowires while maintaining their connectivity.

Expressive pointcuts for increased modularity

Abstract: In aspect-oriented programming, pointcuts are used to describe crosscutting structure. Pointcuts that abstract over irrelevant implementation details are clearly desired to better support maintainability and modular reasoning. We present an analysis which shows that current pointcut languages support localization of crosscutting concerns but are problematic with respect to information hiding. To cope with the problem, we present a pointcut language that exploits information from different models of program semantics, such as the execution trace, the syntax tree, the heap, static type system, etc., and supports ion mechanisms analogous to functional abstraction. We show how this raises the abstraction level and modularity of pointcuts and present first steps toward an efficient implementation by means of a static analysis technique.

A marching method for the triangulation of surfaces

Abstract: Surface triangulations are necessary in applying finite element methods for solving mechanical problems and for displaying surfaces by ray tracing or other hidden line algorithms. A parametric surface can be a triangulated by triangulating its (plane) area of definition. However, the images of these triangles in object space may vary unacceptably for the application. Thus we need suitable methods of triangulation even for parametric surfaces. Triangulation algorithms for implicit surfaces are available in the literature. [ALGN'91; BL'88; LO'87; SC'93; WY'86]. All these methods divide the space into suitable polyhedrons (cubes, tetrahedrons) and determine the section of the given implicit surface with the edges of these polyhedrons. The intention of this paper is to introduce a marching method to build a mesh of triangles successively by starting with a point or a prescribed polygon. The triangulation is terminated by several bounding polygons (on the given surface) or a global bounding box. (A similar idea is used in the recently published paper [BAXU'97] on algebraic surfaces.) The method will be established for implicit surfaces. With the idea of numerical implicitization introduced in [HA'97], the triangulation is applicable to any surface for which foot points (i.e., points of minimal distance to the surface) can be determined.The main advantages of the triangulation presented in this paper are: