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A new and simple method for nanostructuring using conventional photolithography and layer expansion or pattern-size reduction technique is presented, which can further be applied for the fabrication of different nanostructures and nano-devices. The method is based on the conversion of a photolithographically patterned metal layer to a metal-oxide mask with improved pattern-size resolution using thermal oxidation. With this technique, the pattern size can be scaled down to several nanometer dimensions. The proposed method is experimentally demonstrated by preparing nanostructures with different configurations and layouts, like circles, rectangles, trapezoids, “fluidic-channel”-, “cantilever”- and meander-type structures.
Dipl.-Ing. Ralf Engels - DHI Wasser und Umwelt GmbH, Syke. 24 S. (S. 70-93) Beitrag zum 1. Aachener Softwaretag in der Wasserwirtschaft <1,2007, Aachen> Einleitung [des Autors] Die hydrodynamische Kanalnetzmodellierung ist ein Standardwerkzeug für die Bemessung von Kanalnetzen. Neben der Berechnung der hydrologischen und hydraulischen Gegebenheiten in einem städtischen Einzugsgebiet gehören auch weiterführende Technologien mittlerweile zum Standard. So können alle steuerbaren Elemente eines Kanalnetzes dynamisch so optimiert werden, dass die Leistungsfähigkeit des Kanalnetzes zusätzlich gesteigert werden kann. Automatische Werkzeuge zur dynamischen hydraulischen Schmutzfrachtberechnung ermöglichen die Erweiterung der Steuerung – insbesondere von Entlastungsanlagen – im Hinblick auf die entlasteten Schmutzfrachten und geben darüber hinaus detaillierte Informationen für den Betrieb der Kläranlage. Weiterführende biologische Prozessmodellierungen ergänzen dieses Themenfeld. GIS Werkzeuge können bei der räumlich differenzierten Modellierung von Kanalnetzen wertvolle Dienste leisten. Die detaillierte Betrachtung einzelner Haltungsflächen in ihrem räumlichen Zusammenhang ist damit ebenso möglich wie eine komplette Verwaltung aller für die Kanalnetzmodellierung notwendigen Daten in einem übersichtlichen grafischen Menü. Die Grenzen der Kanalnetzmodellierung lagen in früheren Zeiten an dessen Rand. Detaillierte Informationen über die Wege des Wassers auf der Geländeoberfläche, an der Schnittstelle zu Vorflutern und in der Interaktion mit Grundwasser waren bisher nicht modelltechnisch bewertbar. Eine dynamische Kopplung verschiedener Modelle zur Darstellung aller relevanten hydraulischen Prozesse ermöglicht eine integrative Betrachtung aller möglichen Wege, die das Wasser in der Stadt nehmen kann (Mark & Djordjevic, 2006). Dieser Beitrag präsentiert den Stand der Technik für die integrierte Modellierung städtischer Überschwemmungen mit Hilfe der Modellkopplung von Oberflächenmodellen und Kanalnetzmodellen.
Urban farming is an innovative and sustainable way of food production and is becoming more and more important in smart city and quarter concepts. It also enables the production of certain foods in places where they usually dare not produced, such as production of fish or shrimps in large cities far away from the coast. Unfortunately, it is not always possible to show students such concepts and systems in real life as part of courses: visits of such industry plants are sometimes not possible because of distance or are permitted by the operator for hygienic reasons. In order to give the students the opportunity of getting into contact with such an urban farming system and its complex operation, an industrial urban farming plant was set up on a significantly smaller scale. Therefore, all needed technical components like water aeriation, biological and mechanical filtration or water circulation have been replaced either by aquarium components or by self-designed parts also using a 3D-printer. Students from different courses like mechanical engineering, smart building engineering, biology, electrical engineering, automation technology and civil engineering were involved in this project. This “miniature industrial plant” was also able to start operation and has now been running for two years successfully. Due to Corona pandemic, home office and remote online lectures, the automation of this miniature plant should be brought to a higher level in future for providing a good control over the system and water quality remotely. The aim of giving the student a chance to get to know the operation of an urban farming plant was very well achieved and the students had lots of fun in “playing” and learning with it in a realistic way.
Various planar technologies are employed for developing solid-state sensors having low cost, small size and high reproducibility; thin- and thick-film technologies are most suitable for such productions. Screen-printing is especially suitable due to its simplicity, low-cost, high reproducibility and efficiency in large-scale production. This technology enables the deposition of a thick layer and allows precise pattern control. Moreover, this is a highly economic technology, saving large amounts of the used inks. In the course of repetitions of the film-deposition procedure there is no waste of material due to additivity of this thick-film technology. Finally, the thick films can be easily and quickly deposited on inexpensive substrates. In this contribution, thick-film ion-selective electrodes based on ionophores as well as crystalline ion-selective materials dedicated for potentiometric measurements are demonstrated. Analytical parameters of these sensors are comparable with those reported for conventional potentiometric electrodes. All mentioned thick-film strip electrodes have been totally fabricated in only one, fully automated thickfilm technology, without any additional manual, chemical or electrochemical steps. In all cases simple, inexpensive, commercially available materials, i.e. flexible, plastic substrates and easily cured polymer-based pastes were used.
Mischwassereinleitungen in Gewässer nach BWK Merkblatt M3 - Vorteile des detaillierten Nachweises
(2009)
Dipl.-Ing. Brigitte Huber und Dr.-Ing. Gerd Demny - Wasserverband Eifel Rur, Düren. 16 Seiten ( S. 59-74). Beitrag zum 2. Aachener Softwaretag in der Wasserwirtschaft <2, 2009, Aachen> Zusammenfassung [der Autoren] Für das städtisch geprägte Einzugsgebiet des Broicher Baches sind ein vereinfachter und ein detaillierter Nachweis nach BWK-M3 durchgeführt worden. Dabei zeigt sich, dass die Methodik des vereinfachten Nachweises nicht geeignet ist, um eine realitätsnahe Abbildung der einleitungsgeprägten Abflüsse des Gewässers zu erhalten. Dies ist insbesondere auf die Vernachlässigung von Wellentranslation und -retention im Gerinne zurückzuführen. Die dadurch entstehende Fehleinschätzung der Abflussverhältnisse versperrt den Blick auf eine situationsgerechte Maßnahmenplanung. Der mit Hilfe eines NA-Modells geführte detaillierte Nachweis ist zwar in der Erstellung aufwändiger, zeichnet aber ein reales Bild der Abflusserhöhung durch Einleitungen. Mit Hilfe des Modells können die wesentlichen Einflüsse schnell lokalisiert und zielführende Maßnahmenvarianten identifiziert werden. In dem hier vorgestellten Beispiel des Broicher Baches können die ursprünglich identifizierten acht Maßnahmen auf eine reduziert werden. Das Gesamtvolumen der erforderlichen Rückhaltungen wird um die Hälfte verringert. Der Vergleich beider Nachweismethoden legt nach Ansicht der Autoren nahe, den vereinfachten Nachweis höchstens für eine erste Einschätzung des Maßnahmenbedarfs anzuwenden. Die Maßnahmenidentifikation und -dimensionierung sollte grundsätzlich mit der detaillierten Nachweismethode durchgeführt werden, die auf einem entsprechenden NA-Modell basiert. Dies gilt insbesondere für Gewässerstrecken, deren Abfluss durch mehrere, hintereinander liegende Einleitungsstellen geprägt ist.
The so-called "compound solar sail", also known as "Solar Photon Thruster" (SPT), is a solar sail design concept, for which the two basic functions of the solar sail, namely light collection and thrust direction, are uncoupled. In this paper, we introduce a novel SPT concept, termed the Advanced Solar Photon Thruster (ASPT). This model does not suffer from the simplified assumptions that have been made for the analysis of compound solar sails in previous studies. We present the equations that describe the force, which acts on the ASPT. After a detailed design analysis, the performance of the ASPT with respect to the conventional flat solar sail (FSS) is investigated for three interplanetary mission scenarios: An Earth-Venus rendezvous, where the solar sail has to spiral towards the Sun, an Earth-Mars rendezvous, where the solar sail has to spiral away from the Sun, and an Earth-NEA rendezvous (to near-Earth asteroid 1996FG3), where a large orbital eccentricity change is required. The investigated solar sails have realistic near-term characteristic accelerations between 0.1 and 0.2mm/s2. Our results show that a SPT is not superior to the flat solar sail unless very idealistic assumptions are made.
Within ESA's Cosmic Vision 2015-2025 plan, a mission to explore the Saturnian System, with special emphasis on its two moons Titan and Enceladus, was selected for study, termed TANDEM (Titan and Enceladus Mission). In this paper, we describe an optimized mission design for a TANDEM-derived solar electric propulsion (SEP) mission. We have chosen the SEP mission scenario for the interplanetary transfer of the TANDEM spacecraft because all feasible gravity assist sequences for a chemical transfer between 2015 and 2025 result in long flight times of about nine years. Our SEP system is based on the German RIT ion engine. For our optimized mission design, we have extensively explored the SEP parameter space (specific impulse, thrust level, power level) and have calculated an optimal interplanetary trajectory for each setting. In contrast to the original TANDEM mission concept, which intends to use two launch vehicles and an all-chemical transfer, our SEP mission design requires only a single Ariane 5 ECA launch for the same payload mass. Without gravity assist, it yields a faster and more flexible transfer with a fight time of less than seven years, and an increased payload ratio. Our mission design proves thereby the capability of SEP even for missions into the outer solar system.
Solar sails provide ignificant advantages over other low-thrust propulsion systems because they produce thrust by the momentum exchange from solar radiation pressure (SRP) and thus do not consume any propellant.The force exerted on a very thin sail foil basically depends on the light incidence angle. Several analytical SRP force models that describe the SRP force acting on the sail have been established since the 1970s. All the widely used models use constant optical force coefficients of the reflecting sail material. In 2006,MENGALI et al. proposed a refined SRP force model that takes into account the dependancy of the force coefficients on the light incident angle,the sail’s distance from the sun (and thus the sail emperature) and the surface roughness of the sail material [1]. In this paper, the refined SRP force model is compared to the previous ones in order to identify the potential impact of the new model on the predicted capabilities of solar sails in performing low-cost interplanetary space missions. All force models have been implemented within InTrance, a global low-thrust trajectory optimization software utilizing evolutionary neurocontrol [2]. Two interplanetary rendezvous missions, to Mercury and the near-Earth asteroid 1996FG3, are investigated. Two solar sail performances in terms of characteristic acceleration are examined for both scenarios, 0.2 mm/s2 and 0.5 mm/s2, termed “low” and “medium” sail performance. In case of the refined SRP model, three different values of surface roughness are chosen, h = 0 nm, 10 nm and 25 nm. The results show that the refined SRP force model yields shorter transfer times than the standard model.
A laser-enhanced solar sail is a solar sail that is not solely propelled by solar radiation but additionally by a laser beam that illuminates the sail. This way, the propulsive acceleration of the sail results from the combined action of the solar and the laser radiation pressure onto the sail. The potential source of the laser beam is a laser satellite that coverts solar power (in the inner solar system) or nuclear power (in the outer solar system) into laser power. Such a laser satellite (or many of them) can orbit anywhere in the solar system and its optimal orbit (or their optimal orbits) for a given mission is a subject for future research. This contribution provides the model for an ideal laser-enhanced solar sail and investigates how a laser can enhance the thrusting capability of such a sail. The term ”ideal” means that the solar sail is assumed to be perfectly reflecting and that the laser beam is assumed to have a constant areal power density over the whole sail area. Since a laser beam has a limited divergence, it can provide radiation pressure at much larger solar distances and increase the radiation pressure force into the desired direction. Therefore, laser-enhanced solar sails may make missions feasible, that would otherwise have prohibitively long flight times, e.g. rendezvous missions in the outer solar system. This contribution will also analyze exemplary mission scenarios and present optimial trajectories without laying too much emphasis on the design and operations of the laser satellites. If the mission studies conclude that laser-enhanced solar sails would have advantages with respect to ”traditional” solar sails, a detailed study of the laser satellites and the whole system architecture would be the second next step