Raman spectroscopy and field emission measurements on catalytically grown carbon nanotubes

We used microcontact printing to pattern a silicon surface with an iron-containing catalytic solution. Multi-wall carbon nanotubes were subsequently grown on the patterned areas by chemical vapor deposition at temperatures between 650 and 1000C. We demonstrate that the diameter of the catalytically grown multi-wall nanotubes increases with the deposition temperature. Raman spectroscopy has been used to investigate the crystalline character of the obtained structures and it is found that the fraction of the nano-crystalline shell increases with the temperatures. The measurement of the field emission properties shows a correlation between the tube diameter and the emission field values.Comment: 6 pages, 6 figures, 1 tabl

Intelligent assembly in flexible automation

This work investigates the automation of assembly cells and the need to incorporate sensor-guided decision techniques. The experience of industry in this area is examined by observing a real cell on the shop floor. From the collected data conclusions point to an alternative error interpretation which describes the successful completion rather than an enumeration of errors. A methodology for the description of the process in robotic assembly is developed. The constituent phases in handling components are identified as Feeding, Transport and Mating. Each phase has well defined characteristic properties which can be determined using appropriate sensing mechanisms. The mating phase is given special attention by proposing the method of information Spaces as a suitable frame work for sensor fusion and context directed interpretation. Thus the successful progress is described regarding any deviations as errors. They in turn can be interpreted in the context in which they were encountered and recovery is accomplished in the demonstration cell by operator taught routines. Where error repetition occurs, a simple look-up technique suffices to remove the need for another operator intervention. The required data structures and the implementation of the experimental cell are discussed. It is concluded from the results that the principle of knowledge-based assembly control exhibits an intelligent behaviour which contributes to an increase in the cell productivity. This method addresses only a part of the overall problem of assembly automation, but it has a central place in the system and could be extended to the complete system

Digraph based determination of Jordan block size structure of singular matrix pencils

AbstractThe generic Jordan block sizes corresponding to multiple characteristic roots at zero and at infinity of a singular matrix pencil will be determined graph-theoretically. An application of this technique to detect certain controllability properties of linear time-invariant differential algebraic equations is discussed

Self-Management – Potentiale, Probleme, Perspektiven

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Gordon Moores Gesetz vom exponentiellen Wachstum der Transistordichte pro Quadrat-Zoll hat seit 1965 die IT-Industrie geprägt. Mit der damit einhergehenden Explosion der Rechnerleistung wurde die Software immer leistungsfähiger, und man ist dazu übergegangen, Rechnersysteme zu vernetzen und Anwendungen zu verteilen. Eine Folge dieser Entwicklungen ist die rapide zunehmende Komplexität der modernen Informationstechnologie. 40 Jahre nach Moores Entdeckung droht eben diese Tatsache, dem bisherigen exponentiellen Wachstum natürliche Grenzen zu setzen. Moderne, vernetzte Rechnersysteme, wie sie in der Industrie weit verbreitet sind, sind schon heute zu komplex als dass sie auf manuellem Wege, d.h., durch menschliche Administratoren, in einem optimalen Betriebszustand gehalten werden können. Die Folgen sind eine unzureichende Ausnutzung vorhandener Ressourcen, wiederkehrende Fehlerzustände und Lücken in der Absicherung gegen mutwillige Angriffe auf die System-Integrität. Dies führt zu erheblichen finanziellen Mehraufwendungen bzw. Verlusten. Ein permanent überfordertes Administrationspersonal, trägt durch eigene Fehler ein Übriges bei.Schenkt man den jüngst aufkeimenden Initiativen von IT-Giganten wie IBM, Microsoft und Sun Glauben, so heißt die Lösung dieser Misere automatisiertes Management. Vernetzte Rechnersysteme sollen sich auf lange Sicht selbst verwalten. Man erhofft sich hiervon ein effektiveres Management und eine Freistellung von Personal, welches sich dann um wichtigere Aufgaben kümmern kann.In diesem Beitrag beleuchten wir den aktuellen Stand und die Perspektiven im Bereich des Self-Managements. Des Weiteren diskutieren wir offene Fragen, welche auf dem Weg zu selbstverwaltenden Systemen zu lösen sind

Using a dual plasma process to produce cobalt--polypyrrole catalysts for the oxygen reduction reaction in fuel cells -- part II: analysing the chemical structure of the films

The chemical structure of cobalt--polypyrrole -- produced by a dual plasma process -- is analysed by means of X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption spectroscopy (NEXAFS), X-ray diffraction (XRD), energy-dispersive X-Ray spectroscopy (EDX) and extended x-ray absorption spectroscopy (EXAFS).It is shown that only nanoparticles of a size of 3\,nm with the low temperature crystal structure of cobalt are present within the compound. Besides that, cobalt--nitrogen and carbon--oxygen structures are observed. Furthermore, more and more cobalt--nitrogen structures are produced when increasing the magnetron power. Linking the information on the chemical structure to the results about the catalytic activity of the films -- which are presented in part I of this contribution -- it is concluded that the cobalt--nitrogen structures are the probable catalytically active sites. The cobalt--nitrogen bond length is calculated as 2.09\,\AA\ and the carbon--nitrogen bond length as 1.38\,\AA

(η5-Cyclo­penta­dien­yl)(propionitrile-κN)bis­(triphenyl­phosphine-κP)ruthenium(II) trifluoro­methane­sulfonate

The title compound, [Ru(C5H5)(C3H5N)(C18H15P)2]CF3SO3, forms yellow crystals with a distinctly hemimorphic habit. It contains a half-sandwich complex of ruthenium with a three-legged piano-stool geometry, with Ru—P = 2.3585 (4) and 2.3312 (4) Å, and Ru—N = 2.0422 (15) Å as the legs. The CF3SO3 − anion is anchored in the crystal lattice by C—H⋯O and C—H⋯F hydrogen bonds, with C⋯F,O distances starting at 3.125 (2) Å

On the Structure of Spatial Branching Processes

The paper is a contribution to the theory of branching processes with discrete time and a general phase space in the sense of [2]. We characterize the class of regular, i.e. in a sense sufficiently random, branching processes (Φk) k∈Z by almost sure properties of their realizations without making any assumptions about stationarity or existence of moments. This enables us to classify the clans of (Φk) into the regular part and the completely non-regular part. It turns out that the completely non-regular branching processes are built up from single-line processes, whereas the regular ones are mixtures of left-tail trivial processes with a Poisson family structure

Identifying the Challenges in Reducing Latency in GSN using Predictors

Simulations based on real-time data continuously gathered from sensor networks all over the world have received growing attention due to the increasing availability of measured data. Furthermore, predictive techniques have been employed in the realm of such networks to reduce communication for energy-efficiency. However, research has focused on the high amounts of data transferred rather than latency requirements posed by the applications. We propose using predictors to supply data with low latency as required for accurate simulations. This paper investigates requirements for a successful combination of these concepts and discusses challenges that arise