Die Lösung des feldtheoretischen Viermedienproblems ebener Schichten

Übersicht In der Praxis tritt häufig der Fall eines in ebene Materieschichten geteilten Raumes auf. Die so entstehenden Feldprobleme werden für vier Schichten analytisch gelöst, womit sich der numerische Rechenaufwand stark verringern läßt. Der Lösungsgang mit der Spiegelungsmethode erfolgt systematisch konstruktiv vom Zweimedienproblem über das Dreimedienproblem. Die Lösung ist unabhängig von der Form der feldverursachenden Quellen. Dadurch sind die Felder aller Quellenanordnungen, die im unbegrenzten homogenen Raum angebbar sind, nunmehr auch im vierfach geschichteten Raum bekannt. Die Spiegelquellen können darüber hinaus zur Berechnung von Kräften dienen. Als Anwendungsbeispiel werden Kapazitätsbeläge gekoppelter Mikrostripleitungen berechnet.

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Solving fourmedia problems of plane layers in field theory

Contents Arrangements with plane layers of material are quite common. The analytical solution of the four layers problem greatly facilitates subsequent numerical calculations. The procedure is based on the fundamental twomedia and threemedia arrangements. No restrictions must be imposed on the shapes of the field's sources. Thus, for arbitrary distributions of sources the field can be given, if it is available in unbounded homogenious material. The image sources also can serve for the calculation of forces. As an example the mutual capacities of microstrip lines are calculated.

     

Finite difference time-domain analysis of planar microwave circuits

Contents The application of finite difference time domain analysis techniques to planar microwave integrated circuit design is discussed. It is shown that using this technique, three-dimensional discontinuity problems in planar microstrip and coplanar circuits can be analyzed in a full-wave approach.

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Finite-Differenzen-Analyse von planaren Mikrowellen-schaltungen im Zeitbereich

Übersicht Es wird die Anwendung der Finiten-Differenzen-Analyse elektromagnetischer Felder im Zeitbereich auf den Entwurf integrierter Mikrowellenschaltungen diskutiert. Es wird gezeigt, daß durch Anwendung dieser Technik eine Lösung der Beschreibungsprobleme für dreidimensionale Schaltkreis-Diskontinuitäten in planarer Mikrostreifenleitungstechnik und in koplanarer Leitungstechnik unter Berücksichtigung der vollen Welleneigenschaften gefunden werden kann. Verschiedene Beispiele von Analysen planarer Mikrowellenbauelemente werden diskutiert und die Ergebnisse mit Messungen verglichen.

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Dedicated to Prof. Dr.-Ing. Herbert Döring on the occasion of his 80th birthday     

Dual-Color InAs/GaSb Superlattice Focal-Plane Array Technology

Within a very few years, InAs/GaSb superlattice technology has proven its suitability for high-performance infrared imaging detector arrays. At the Fraunhofer Institute for Applied Solid State Physics (IAF) and AIM Infrarot-Module GmbH, efforts have been focused on developing mature fabrication technology for dual-color InAs/GaSb superlattice focal-plane arrays for simultaneous, colocated detection at 3 μm to 4 μm and 4 μm to 5 μm in the mid-wavelength infrared atmospheric transmission window. Integrated into a wide-field-of-view missile approach warning system for an airborne platform, a very low number of pixel outages and cluster defects is mandatory for bispectral detector arrays. Process refinements, intense root-cause analysis, and specific test methodologies employed at various stages during the process have proven to be the key for yield enhancements.     

Nanoimprint Lithography Facilitated Plasmonic-Photonic Coupling for Enhanced Photoconductivity and Photocatalysis

Imprint lithography has emerged as a reliable, reproducible, and rapid method for patterning colloidal nanostructures. As a promising alternative to top-down lithographic approaches, the fabrication of nanodevices has thus become effective and straightforward. In this study, a fusion of interference lithography (IL) and nanosphere imprint lithography on various target substrates ranging from carbon film on transmission electron microscope grid to inorganic and dopable polymer semiconductor is reported. 1D plasmonic photonic crystals are printed with 75% yield on the centimeter scale using colloidal ink and an IL-produced polydimethylsiloxane stamp. Atomically smooth facet, single-crystalline, and monodisperse colloidal building blocks of gold (Au) nanoparticles are used to print 1D plasmonic grating on top of a titanium dioxide (TiO₂) slab waveguide, producing waveguide-plasmon polariton modes with superior 10 nm spectral line-width. Plasmon-induced hot electrons are confirmed via two-terminal current measurements with increased photoresponsivity under guiding conditions. The fabricated hybrid structure with Au/TiO₂ heterojunction enhances photocatalytic processes like degradation of methyl orange (MO) dye molecules using the generated hot electrons. This simple colloidal printing technique demonstrated on silicon, glass, Au film, and naphthalenediimide polymer thus marks an important milestone for large-scale implementation in optoelectronic devices.     

SIVA: A System for Coverage-Directed State Space Search

We introduce SImulation Verification with Augmentation (SIVA), a tool for coverage-directed state space search on digital hardware designs. SIVA tightly integrates simulation with symbolic techniques for efficient state space search. Specifically, the core algorithm uses a combination of ATPG and BDDs to generate directed input vectors, i.e., inputs which cover behavior not excited by simulation. We also present approaches to automatically generate lighthouses that guide the search towards hard-to-reach coverage goals. Experiments demonstrate that our approach is capable of achieving significantly greater coverage than either simulation or symbolic techniques in isolation.     

Optical Interconnects on and in Printed Circuit Boards

Two types of short distance optical interconnects for on-board applications are presented: Small diameter plastic optical fibre (POF) links and multimode polymer waveguide layers integrated in multilayer printed circuit boards (PCB). POF links with fibre numbers up to 128 and link lengths up to 50 cm are realized with total transmission loss values below 2 dB at 660 nm. First tests of 10 cm long temperature stable multimode polymer waveguides laminated into standard multilayer PCBs demonstrate the capabilities of combined electrical-optical circuit boards.     

The Effects of Embedded Dipoles in Aromatic Self‐Assembled Monolayers

Using a representative model system, here electronic and structural properties of aromatic self‐assembled monolayers (SAMs) are described that contain an embedded, dipolar group. As polar unit, pyrimidine is used, with its orientation in the molecular backbone and, consequently, the direction of the embedded dipole moment being varied. The electronic and structural properties of these embedded‐dipole SAMs are thoroughly analyzed using a number of complementary characterization techniques combined with quantum‐mechanical modeling. It is shown that such mid‐chain‐substituted monolayers are highly interesting from both fundamental and application viewpoints, as the dipolar groups are found to induce a potential discontinuity inside the monolayer, electrostatically shifting the core‐level energies in the regions above and below the dipoles relative to one another. These SAMs also allow for tuning the substrate work function in a controlled manner independent of the docking chemistry and, most importantly, without modifying the SAM‐ambient interface.     

50 Jahre Kybernetik in Österreich

The term “cybernetics” is very old, but in the middle of the last century it gained new importance as steering brought new aspects to the area of information technology. This paper deals with the general history of cybernetics and then describes the beginning of this field at Vienna University of Technology. In this context it was an important step, when the book “Cybernetics” by Norbert Wiener first came to Vienna; thus the interest in cybernetic models evolved. Originating from the interest in cybernetic models, three models were recreated (and refined):

1. the model of the conditioned reflex (artificial tortoise),
2. the model of orientation in a maze (mouse), and
3. the model of homeostasis (homeostat).

The third and final part of this paper illustrates the gradual transition to artificial intelligence (AI). Hopes that were tied up with this term are discussed. Apart from that the question of how much has been left of cybernetics and artificial intelligence today is raised. The mouse in the maze is very closely connected to our Emeritus: He built the Viennese version of it as part of his diploma thesis.