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Pandaboard, TurtleBot, Kinect und Co. : Low-Cost Hardware im Lehreinsatz für die mobile Robotik.
(2012)
Mit freundlicher Genehmigung der Autoren und des Oldenbourg Industrieverlags https://www.oldenbourg-industrieverlag.de/de/9783835633223-33223 erschienen als Beitrag im Tagungsband zur AALE-Tagung 2012. 9. Fachkonferenz 4.-5. Mai 2012, Aachen, Fachhochschule. ISBN 9783835633223 S 8-1 S. 229-238 Original-Abstract des Autors: "Die mobile Robotik wird durch den Einsatz von Low-Cost Hardware einem breiten Publikum zugänglich. Bis vor kurzem basierte eine erschwingliche Hardware meist auf Mikrocontrollern mit den entsprechenden Leistungseinschränkungen z.B. im Bereich der Bildverarbeitung. Die Wahrnehmung einer 3D-Umgebung und somit die Möglichkeit zur autonomen Navigation wurde mit relativ kostenintensiver Hardware, z.B. Stereo-Vision-Systemen und Laserscannern gelöst. Die zur Auswertung der Sensorik notwendige Rechenleistung stand - entweder aufgrund des Stromverbrauchs oder der Performance meist für mobile Plattformen (lokal) - nicht zur Verfügung. Durch Einsatz von leistungsfähigen Prozessoren aus dem Bereich der Mobilgeräte (Smartphones, Tablets) und neuartigen Sensoren des Consumer-Bereichs, wie der Kinect, können mobile Roboter kostengünstig für den Einsatz in der Lehre aufgebaut werden.
Im Beitrag wird zunächst das Verfahren eines dynamischen elektro-geometrischen Modells vorgestellt. Dieses arbeitet im Gegensatz zum klassischen Blitzkugel-Verfahren nicht mit konstanten Radien; vielmehr wird der Radius der Blitzkugel variiert. Dabei werden ausschließlich vorhandene und in internationalen Normen anerkannte Ergebnisse, blitzphysikalische Grundlagen und Untersuchungen verwendet, und auf deren Grundlage ein numerisches Verfahren erarbeitet. Mit dem dynamischen elektro-geometrischen Modell werden dann einige Beispiele des Schutzes mit Fangstangen, die gemäß dem klassischen Blitzkugel-Verfahren nach DIN EN 62305-3 für die Schutzklassen I – II – III – IV geplant sind, untersucht. Es wird gezeigt, dass die Einfangwirksamkeiten wesentlich höher sind als in der Normenreihe DIN EN 62305 selbst angegeben. Grund dafür ist die Tatsache, dass das Blitzkugel-Verfahren sehr konservativ aufgebaut ist und dem Planer von Blitzschutzsystemen nur die möglichen Stellen für einen Einschlag aufzeigt, ohne eine Bewertung der Einschlagshäufigkeit zu liefern. Andererseits bedeutet dies jedoch, dass man mit dem klassischen Blitzkugel-Verfahren stets auf der „sicheren Seite“ liegt.
Agil ist im Trend und immer mehr Unternehmen, die ihre Projekte bisher nach klassischen Prinzipien durchführten, denken über den Einsatz agiler Methoden nach. Doch selbst wenn die Organisation bereits beide Philosophien unterstützt, gilt für ein Projekt meist die klare Vorgabe: agil oder klassisch. Es gibt aber noch einen anderen Ansatz, mit diesen "unterschiedlichen Welten" umzugehen: Und zwar die beiden Philosophien innerhalb eines Projekts zu kombinieren. Wie dies in der Praxis aussehen und gelingen kann, zeigen Dr. Michael Kirchhof und Prof. Dr. Bodo Kraft in diesem Beitrag.
Realisation of a calorimetric gas sensor on polyimide foil for applications in aseptic food industry
(2012)
A calorimetric gas sensor is presented for the monitoring of vapour-phase H2O2 at elevated temperature during sterilisation processes in aseptic food industry. The sensor was built up on a flexible polyimide foil (thickness: 25 μm) that has been chosen due to its thermal stability and low thermal conductivity. The sensor set-up consists of two temperature-sensitive platinum thin-film resistances passivated by a layer of SU-8 photo resist and catalytically activated by manganese(IV) oxide. Instead of an active heating structure, the calorimetric sensor utilises the elevated temperature of the evaporated H2O2 aerosol. In an experimental test rig, the sensor has shown a sensitivity of 4.78 °C/(%, v/v) in a H2O2 concentration range of 0%, v/v to 8%, v/v. Furthermore, the sensor possesses the same, unchanged sensor signal even at varied medium temperatures between 210 °C and 270 °C of the gas stream. At flow rates of the gas stream from 8 m3/h to 12 m3/h, the sensor has shown only a slightly reduced sensitivity at a low flow rate of 8 m3/h. The sensor characterisation demonstrates the suitability of the calorimetric gas sensor for monitoring the efficiency of industrial sterilisation processes.
Characterisation of polymeric materials as passivation layer for calorimetric H2O2 gas sensors
(2012)
Calorimetric gas sensors for monitoring the H₂O₂ concentration at elevated temperatures in industrial sterilisation processes have been presented in previous works. These sensors are built up in form of a differential set-up of a catalytically active and passive temperature-sensitive structure. Although, various types of catalytically active dispersions have been studied, the passivation layer has to be established and therefore, chemically as well as physically characterised. In the present work, fluorinated ethylene propylene (FEP), perfluoralkoxy (PFA) and epoxy-based SU-8 photoresist as temperature-stable polymeric materials have been investigated for sensor passivation in terms of their chemical inertness against H₂O₂, their hygroscopic properties as well as their morphology. The polymeric materials were deposited via spin-coating on the temperature-sensitive structure, wherein spin-coated FEP and PFA show slight agglomerates. However, they possess a low absorption of humidity due to their hydrophobic surface, whereas the SU-8 layer has a closed surface but shows a slightly higher absorption of water. All of them were inert against gaseous H₂O₂ during the characterisation in H₂O₂ atmosphere that demonstrates their suitability as passivation layer for calorimetric H₂O₂ gas sensors.
As part of a novel approach to automatic sewer inspection, this paper presents a robust algorithm for automatic flow line detection. A large image repository is obtained from about 50,000 m sewers to represent the high variability of real world sewer systems. Automatic image processing combines Canny edge detection, Hough transform for straight lines and cost minimization using Dijkstra's shortest path algorithm. Assuming that flow lines are mostly smoothly connected horizontal structures, piecewise flow line delineation is reduced to a process of selecting adjacent line candidates. Costs are derived from the gap between adjacent candidates and their reliability. A single parameter α enables simple control of the algorithm. The detected flow line may precisely follow the segmented edges (α = 0.0) or minimize gaps at joints (α = 1.0). Both, manual and ground truth-based analysis indicate that α = 0.8 is optimal and independent of the sewer's material. The algorithm forms an essential step to further automation of sewer inspection.
Auswahl der Herniennetze nach der “effektiven Porosität” - warum das Gewicht weniger wichtig ist
(2012)
Außerbilanzielle Korrekturen
(2012)
31P MR spectroscopic imaging of the human prostate provides information about phosphorylated metabolites that could be used for prostate cancer characterization. The sensitivity of a magnetic field strength of 7 T might enable 3D 31P MR spectroscopic imaging with relevant spatial resolution in a clinically acceptable measurement time. To this end, a 31P endorectal coil was developed and combined with an eight-channel 1H body-array coil to relate metabolic information to anatomical location. An extensive safety validation was performed to evaluate the specific absorption rate, the radiofrequency field distribution, and the temperature distribution of both coils. This validation consisted of detailed Finite Integration Technique simulations, confirmed by MR thermometry and Burn:x-wiley:07403194:media:MRM24175:tex2gif-stack-1 measurements in a phantom and in vivo temperature measurements. The safety studies demonstrated that the presence of the 31P endorectal coil had no influence on the specific absorption rate levels and temperature distribution of the external eight-channel 1H array coil. To stay within a 10 g averaged local specific absorption rate of 10 W/kg, a maximum time-averaged input power of 33 W for the 1H array coil was allowed. For transmitting with the 31P endorectal coil, our safety limit of less than 1°C temperature increase in vivo during a 15-min MR spectroscopic imaging experiment was reached at a time-averaged input power of 1.9 W. With this power setting, a second in vivo measurement was performed on a healthy volunteer. Using adiabatic excitation, 3D 31P MR spectroscopic imaging produced spectra from the entire prostate in 18 min with a spatial resolution of 4 cm3. The spectral resolution enabled the separate detection of phosphocholine, phosphoethanolamine, inorganic phosphate, and other metabolites that could play an important role in the characterization of prostate cancer.
Purpose: It was demonstrated previously that retinal pulse wave velocity (rPWV) as a measure of retinal arterial stiffness is increased in aged anamnestically healthy volunteers compared with young healthy subjects. Using novel methodology of rPWV assessment this finding was confirmed and investigated whether it might relate to the increased blood pressure usually accompanying the aging process, rather than to the aging itself.
Methods: A total of 12 young 25.5-year-old (24.0–28.8) [median(1st quartile–3rd quartile)] and 12 senior 68.5-year-old (63.8–71.8) anamnestically healthy volunteers; and 12 senior 63.0-year-old (60.8–65.0) validated healthy volunteers and 12 young 33.0-year-old (29.5–35.0) hypertensive patients were examined. Time-dependent alterations of vessel diameter were assessed by the Dynamic Vessel Analyzer in a retinal artery of each subject. The data were filtered and processed using mathematical signal analysis and rPWVs were calculated.
Results: rPWV amounted to 1200 (990-1470) RU (relative units)/s in the hypertensive group and to 1040 (700-2230) RU/s in anamnestically healthy seniors. These differed significantly from rPWVs in young healthy group (410 [280–500] RU/s) and in validated healthy seniors (400 [320–510] RU/s). rPWV associated with age and mean arterial pressure (MAP) in the pooled cohort excluded validated healthy seniors. In a regression model these associations remain when alternately adjusted for MAP and age. When including validated healthy seniors in the pooled cohort only association with MAP remains.
Conclusions: Both aging (with not excluded cardiovascular risk factors) and mild hypertension are associated with elevated rPWV. rPWV increases to a similar extent both in young mildly hypertensive subjects and in aged anamnestically healthy persons. Healthy aging is not associated with increased rPWV.