Development of error-compensating UI for autonomous production cells

This contribution deals with the impact of human error on the overall system reliability in flexible manufacturing systems (FMS). Autonomous production cells are used to illustrate an error-compensating system design on the basis of Sheridan's (1997) paradigm of supervisory control. In order to specify human errors and their effects in terms of system disturbances, a taxonomy of system disturbances is recommended. This taxonomic approach was derived by a value benefit analysis and is based on HEDOMS (Human Error and Disturbance Occurrence in Manufacturing Systems) with slight modifications and Reason's GEMS (Generic Error Modelling System). The taxonomy is used for data acquisition. Next, a risk priority equivalent to FMEA (Failure Mode and Effect Analysis) is introduced to structure the data according to their relevance. Then, Vicente's and Rasmussen's guidelines (1987) for an ecological interface design are related to the paradigm of supervisory control. On the basis of these guidelines four case studies are presented to show their successful applicability for interface design in FMS.     

A Simple Method to Extract Essential Oils from Tissue Samples by Using Microwave Radiation

A microwave protocol to extract lipophilic substances from tissue was modified to extract essential oils (EOs) from plant tissue and insect feculae. The material, in a solvent transparent to microwave radiation, is exposed for a short time to steam in a microwave oven. EO extracts are analyzed directly by GC or GC-MS when plant material is fresh and terpenes contained in glandular structures on leaf surfaces are readily released into the solvent. For dried material or insect feculae, mechanical means are utilized first to break up tissue; however, the complete procedure is carried out inside the same vial to reduce losses. Statistical analysis shows that the reproducibility of the modified method is high. Several samples can be run within an hour with this method.     

Fabrication of diamond nanowires for quantum information processing applications

We present a design and a top-down fabrication method for realizing diamond nanowires in both bulk single crystal and polycrystalline diamond. Numerical modeling was used to study coupling between a Nitrogen Vacancy (NV) color center and optical modes of a nanowire, and to find an optimal range of nanowire diameters that allows for large collection efficiency of emitted photons. Inductively coupled plasma (ICP) reactive ion etching (RIE) with oxygen is used to fabricate the nanowires. Drop-casted nanoparticles (including Au, SiO₂ and Al₂O₃) as well as electron beam lithography defined spin-on glass and evaporated Au have been used as an etch mask. We found Al₂O₃ nanoparticles to be the most etch resistant. At the same time FOx e-beam resist (spin-on glass) proved to be a suitable etch mask for fabrication of ordered arrays of diamond nanowires. We were able to obtain nanowires with near-vertical sidewalls in both polycrystalline and single crystal diamond. The heights and diameters of the polycrystalline nanowires presented in this paper are ≈ 1 μm and 120–340 nm, respectively, having a 200 nm/min etch rate. In the case of single crystal diamond (types Ib and IIa) nanowires the height and diameter for different diamonds and masks shown in this paper were 1–2.4 μm and 120–490 nm with etch rates between 190 and 240 nm/min.     

Eine abgeschirmte Schleifdrahtbrücke zur Feinmessung von Verlustwinkeln an hochwertigen flüssigen Isolierstoffen

Zusammenfassung Die Verwendung von Schleifdrähten mit vollkommen gleicher Zeitkonstante als untere Brückenzweige ermöglichte es, eine Verlustwinkelmeßbrücke nach dem Schering-Prinzip zu entwickeln, bei der die Einwirkung der Zeitkonstantenänderung auf den Verlustwinkel, die infolge der Verstellung vonR ₃ auftritt, vermieden wird. Durch einen zweiten Abgriff anR ₃ wurde erreicht, daß der Widerstand, der sich sonst mit der Prüfkapazität in Reihe schalten und so einen größeren Verlustwinkel vortäuschen würde, kurzgeschlossen wird. Der Einfluß der Störkapazitäten, die sich parallel zu den unteren Brückenzweigen legen, wird durch Anwendung der doppelten Abschirmung und Kompensation der Störkapazität parallelR ₄ mittels astatischer Gegeninduktivität beseitigt. Hierdurch wird bewirkt, daß ein Hilfszweig nach K. W. Wagner nicht benötigt wird.Bei dem neuen Aufbau der Mauschen Brücke wurde in den Nullzweig ein Übertrager gelegt, um eine bessere Anpassung an den hohen Innenwiderstand der Brücke zu erreichen. Ein Meßbereichschalter in der Hilfsbrücke ermöglicht die Messung von Prüfkapazitäten vom 1/60 fachen bis zum6fachen Betrag des Vergleichskondensators. Im dritten Brückenzweig wurde der Widerstand, der zum Abgleich des tg dient, vor den verlustlosen Kondensator gelegt. Hierdurch wird der Einfluß der Verlustkapazität, die sich vom Verbindungspunkt Widerstand—Normalkapazität nach Erde hin legt, vernachlässigbar klein.Von der Fakultät für Maschinenwesen der T. H. Hannover genehmigte Dissertation.Diese Arbeit wurde im Elektro-Institut I der Technischen Hochschule Hannover ausgeführt. Für die stete Förderung der Arbeit und die wertvollen Anregungen bin ich Herrn Prof. Dr. Schering zu tiefem Dank verpflichtet.Den Firmen Hartmann & Braun und Siemens & Halske möchte ich an dieser Stelle ebenfalls meinen Dank dafür aussprechen, daß sie zum Aufbau der Brücke verwendetes Material kostenlos zur Verfügung stellten.     

Urban traffic modeling and pattern detection using online map vendors and self-organizing maps

Typical traffic modeling approaches, such as network-based methods and simulation models, have been shown inadequate for urban-scale studies due to the fidelity issue of models. As a go-around, data-driven models have received increasing attention recently. However, most data-driven methods have been restricted by their data source and cannot be scaled up to manage urban- and regional-scale studies. Regarding this issue, this research proposes a pipeline that collects traffic data from online map vendors to bypass data limitations for large-scale studies. The study consists of two experiments: 1) recognizing the dominant traffic patterns of cities and 2) site-specific predictions of typical traffic or the most probable locations of patterns of interests. The experiments were conducted on 32 Swiss cities using traffic data that were collected for a two-month period. The results show that dominant patterns can be extracted from the temporal traffic data, and similar patterns exist not only in various parts of a city but also in different cities. Moreover, the results reveal that a country-level lockdown decreased traffic congestions in regional highways but increased those connections near the city centers and the country borders.     

Synthesis,Chiral Separation,Absolute Configuration Assignment,and Biological Activity of Enantiomers of Retro‐1 as Potent Inhibitors of Shiga Toxin

The Shiga toxin (Stx) family is composed of related protein toxins produced by the bacteria Shigella dysenteriae and certain pathogenic strains of E. coli. No effective therapies for Stx intoxication have been developed yet. However, inhibitors that act on the intracellular trafficking of these toxins may provide new options for the development of therapeutic strategies. This study reports the synthesis, chromatographic separation, and pharmacological evaluation of the two enantiomers of Retro‐1, a compound active against Stx and other such protein toxins. Retro‐1 works by inhibiting retrograde transport of these toxins inside cells. In vitro experiments proved that the configuration of the stereocenter at position 5 is not crucial for the activity of this compound. X‐ray diffraction data revealed (S)‐Retro‐1 to be slightly more active than (R)‐Retro‐1.     

Dicing of hard and brittle materials with on-machine laser-dressed metal-bonded diamond blades

The ultra-precision dicing of hard and brittle materials causes high wear on the abrasive tool which results in the deterioration of blade cross section as well as the decrease of diamond grain exposure. Resin-bonded diamond blades are used due to their in-process self-sharpening capability. Nevertheless, the shape of the blade cross section generated by self-sharpening is random which leads to poor accuracy when precise grooves need to be produced. Metal-bonded diamond blades feature higher tool lifetime and shape accuracy compared to resin-bonded blades, but are not capable of performing self-sharpening. In this study, the laser dressing of metal-bonded diamond blades is investigated to enable their use in the ultra-precision dicing of hard and brittle materials by continuous laser dressing. We investigated laser dressing with and without the presence of cooling water. The sharpness (grain exposure) after dressing is measured by the cutting face surface roughness. The dicing performance is evaluated by observing the dicing results in terms of cutting depth consistency and by monitoring the spindle power during dicing. Dicing blades which have been laser dressed in an environment with coolant feature less grain exposure than dicing blades which have been laser dressed in dry condition. The dicing results show an improvement in the sharpness and durability of laser-dressed dicing blades in comparison with new or conventionally dressed blades. The ability to apply and perform laser dressing on a dicing machine in an environment with coolant shows the feasibility of laser technology for continuous dressing.     

Deposition of titanium on SiC fibres from chloride melts

The present study examined the feasibility of producing titanium matrix composites based on a molten salt fibre coating process. It is demonstrated that sufficiently thick and coherent titanium coatings can be deposited on SiC fibres in LiCl–KCl–TiCl₂ at 700 K. One important aspect of the study was the behaviour of the substrate during electrolysis. Therefore, additional features related to carbon-coated SiC fibres and carbonaceous substrates in general are outlined. The morphologies and microstructures of electrolytically coated SiC fibres were investigated by scanning electron microscopy and compared to fibres coated by a physical vapour deposition technique. The cause and relevance of the growth failures that were observed in this study are also discussed.     

Heterogeneous functionalizing of polysulfone membranes

In recent years efforts have been increased to work with more intelligent membranes which render more than normal filtration properties. Thus, membranes have been prepared using chemically modified polymers or have been furnished with additives in order to increase their selectivity and/or special sorbing capabilities. In this paper, methods are described how commercially available polysulfone membranes can be functionalized by chemical reactions without disintegrating their mechanical properties. For this purpose, Sulfonation, chloromethylation, aminomethylation, and lithiation reactions were applied. A broad spectrum for further conversions modified membranes is opened by these chemical reactions which allow an individual fitting of the membranes with special substitutes. The chemical reactions and the analytical procedures are also described.