Refine
Year of publication
- 2015 (14) (remove)
Document Type
- Conference Proceeding (14) (remove)
Conference Type
- Konferenzartikel (11)
- Konferenz-Abstract (1)
- Konferenz-Poster (1)
- Sonstiges (1)
Has Fulltext
- no (14)
Is part of the Bibliography
- yes (14) (remove)
Keywords
- Alexander von Humboldt (2)
- Finite-Elemente-Methode (2)
- Abgas (1)
- Abtragung (1)
- Archives (1)
- Ausbildung (1)
- Biogas (1)
- CAE (1)
- Controlling (1)
- Dimension 2 (1)
Institute
- Fakultät Maschinenbau und Verfahrenstechnik (M+V) (14) (remove)
Open Access
- Open Access (9)
- Closed Access (5)
- Bronze (2)
- Diamond (1)
Combined heat and power production (CHP) based on solid oxide fuel cells (SOFC) is a very promising technology to achieve high electrical efficiency to cover power demand by decentralized production. This paper presents a dynamic quasi 2D model of an SOFC system which consists of stack and balance of plant and includes thermal coupling between the single components. The model is implemented in Modelica® and validated with experimental data for the stack UI-characteristic and the thermal behavior. The good agreement between experimental and simulation results demonstrates the validity of the model. Different operating conditions and system configurations are tested, increasing the net electrical efficiency to 57% by implementing an anode offgas recycle rate of 65%. A sensitivity analysis of characteristic values of the system like fuel utilization, oxygen-to-carbon ratio and electrical efficiency for different natural gas compositions is carried out. The result shows that a control strategy adapted to variable natural gas composition and its energy content should be developed in order to optimize the operation of the system.
Autonomous humanoid robots require light weight, high torque and high speed actuators to be able to walk and run. For conventional gears with a fixed gear ratio the product of torque and velocity is constant. On the other hand desired motions require maximum torque and speed. In this paper it is shown that with a variable gear ratio it is possible to vary the relation between torque and velocity. This is achieved by introducing systems of rods and levers to move the joints of our humanoid robot ”Sweaty II”. On the basis of a variable gear ratio low speed and high torque can be achieved for those joint angles, which require this motion mode, whereas high speed and low torque can be realized for those joint angles, where it is favorable for the desired motion.
This article sets the focus on methods of information technology in the Humboldt Portal, which represents an ongoing research project to develop a virtual research environment on the Internet for the legacy of Alexander von Humboldt. Based on the experiences of developing and providing the Humboldt Digital Library (www.avhumboldt.net) for more than a decade, we defined a working plan to create an Internet portal for comprehensive access to Humboldt’s writings, no matter if documents are provided as PDF files, scan images or XML-TEI documents on external archives (Google Books, Internet Archive, Deutsches Textarchiv, Bibliotheque National de France). Going far beyond services of a digital library we will provide an information network with multimedia assets, which are containing objects like terms, paragraphs, data tables, scan images, or illustrations, together with correlated properties like thematic linkage to other objects, relevant keywords with optional synonyms and dynamic hyperlinks to related translations in different languages. So the Humboldt Portal can contribute to the key question, how to present interconnected data in an appropriate form using information technologies on the Web.
Der hier vorliegende Beitrag beschreibt erste Untersuchungsergebnisse mit der Finite-Elemente-Methode (FEM) zur Entlastung der Kerbspannungen an Getriebewellen mit Durchdringungskerben. Es handelt sich bei den Kerben um eine Umlaufnut mit überlagerter Querbohrung und um einen Wellenabsatz mit überlagerter Querbohrung. Die neu entwickelte Entlastungskerbe erweitert die üblichen Möglichkeiten zur Entlastung von Durchdringungskerben und ermöglicht bedeutende Spannungsreduktionen bis etwa 48% bei Biegung oder Zug/Druck. Die Entlastung bei Torsionsbelastung beträgt maximal etwa 18%. Es wurden Spannungsdiagramme der variierten Entlastungsnutparameter erstellt und Formeln zur näherungsweisen Berechnung der zu erwartenden Spannungen in der Durchdringungskerbe und in der Entlastungsnut ermittelt, zudem werden Empfehlungen zur Gestaltung der Entlastungskerbe gegeben. Dieser Beitrag bietet eine Grundlage zur weiteren Untersuchung zum Thema „räumliche Durchdringungskerben“ und deren Entlastung.
Eye-Tracking-Analyse des Betrachtungsverhaltens bei Micro-Präsentationen in der CAE-Ausbildung
(2015)
Die Zielsetzung des vorliegenden Beitrags ergibt sich aus der persönlichen Motivation der Autoren, das visuelle Verhalten und das Handeln vom jungen Ingenieur beim Micro-Präsentieren technischer Inhalte und Lösungsergebnisse in bildlicher und begrifflicher Form besser zu verstehen und somit effizienter unterstützen zu können. Dabei wurden mehrere Einzelpersonen aus dem Studiengang des Maschinenbaus der Hochschule Offenburg mit Hilfe der Eye-Tracking-Technick beobachtet. Die Probanden befinden sich im 6. Semester, sind im Alter von 21 bis 24 Jahren und zeichnen sich durch einen einheitlichen Ausbildungsstand aus. Die Versuchszeit für die Präsentation der Aufgabe betrug 100 Sekunden. Die Analyse der gewonnenen Daten dieser empirischen Laboruntersuchung erlaubt erste Einblicke in die visuelle Wahrnehmung technischer Objekte beim Vortragen.
The transformation of the building energy sector to a highly efficient, clean, decentralised and intelligent system requires innovative technologies like microscale trigeneration and thermally activated building structures (TABS) to pave the way ahead. The combination of such technologies however presents a scientific and engineering challenge. Scientific challenge in terms of developing optimal thermo-electric load management strategies based on overall energy system analysis and an engineering challenge in terms of implementing these strategies through process planning and control. Initial literature research has pointed out the need for a multiperspective analysis in a real life laboratory environment. To this effect an investigation is proposed wherein an analytical model of a microscale trigeneration system integrated with TABS will be developed and compared with a real life test-rig corresponding to building management systems. Data from the experimental analysis will be used to develop control algorithms using model predictive control for achieving the thermal comfort of occupants in the most energy efficient and grid reactive manner. The scope of this work encompasses adsorption cooling based microscale trigeneration systems and their deployment in residential and light commercial buildings.