70 research outputs found
Eddy Current Analysis of Litz Wire Using Homogenization-Based FEM in Conjunction With Integral Equation
No full textA new method is introduced to evaluate the macroscopic permeability of a litz wire which is composed of stranded conductors. In this method, an integral equation is solved for the complex magnetization in the litz wire generated due to the proximity effect. The macroscopic permeability computed from the magnetization is used in the homogenization-based finite-element analysis of eddy currents in a litz-wire coil. It is shown that the wire twist has a little effect on the complex permeability
Integration Framework for Preliminary Design Toolchains
No full textThe goals defined by the ACARE Vision 2020 present a major challenge to aeronautic research. Besides developments in new aerodynamics and structures, advancements in aero engine research will account for a major part of the required reduction in fuel, emissions and noise. To enable a commercial launch of new aircraft and engine concepts, complex and often contradictory demands have to be fulfilled.
Strong dependencies between the individual technical disciplines exist so that the optimization in a single discipline may not lead inevitably to a global optimum. Therefore it is necessary to look at the overall system in order to evaluate the potential of new technologies realistically.
This article presents a typical design task in aeroengine predesign and a software solution which supports and enables multidisciplinary cooperation on the engineer side. A common data format based on XML, necessary for data exchange, as well as supporting programming libraries for the processing of this data format are introduced. Furthermore it is described, how a parametric representation can be realized for various geometries with the help of XML. A programming library with C and FORTRAN Interfaces supports geometrical computations for these representations. Finally it is demonstrated that the tools used by the different technical disciplines can be connected to a process chain within a framework
Fast 3-D Analysis of Eddy Current in Litz Wire Using Integral Equation
No full textEddy current loss in a litz wire which has 3-D structure is analyzed using the integral equation method considering the proximity effect. In the present method, each wire is modeled as a polygonal line. 1-D integral equation is solved for the dipole magnetization generated by the anti-parallel eddy currents in the wire. The discretized integral equation can effectively be solved using an iterative method solver to compute the eddy current distribution in the wire due to the proximity effect
Open Source Software Framework for Applications in Aeronautics and Space
No full textThe DLR developed the open source software framework
RCE to support the collaborative and distributed work in
the shipyard industry. From a technology side of view a software
from the shipbuilding field has many requirements in common
with aerospace software projects. Accordingly, RCE has become
the basis for further projects within the DLR. Over the last years
of usage a subset of frequently used software components could
be derived and are provided by the RCE framework. In particular,
the workflow engine, allowing the integration of different
domain-specific tools from local and remote locations into one
overall calculation has become important for various projects.
We present RCE and show how its software components are
reused in two aerospace applications
Analysis of Litz Wire Losses Using Homogenization-Based FEM
No full textThis article proposes a novel analysis method for the losses in a litz wire considering the circulating and eddy currents. In the proposed method, the macroscopic complex permeability is introduced to evaluate the eddy current loss owing to the proximity effect. Homogenization-based finite element analysis using the macroscopic complex permeability can effectively compute the proximity effect loss. The loss owing to the circulating currents is evaluated by solving the corresponding circuit equation. It is shown that the eddy current loss is dominant for the solenoidal and spiral coils without magnetic cores because of the uniform magnetic field distribution along the wire. Moreover, the magnetic reactors in which the circulating current loss cannot be ignored are analyzed using the proposed method. It is shown that the losses computed by the proposed method agree well with the measured results
El tiempo y su abismo. Reflexiones sobre la melancolía
No full textPartiendo de la figura de Hamlet como ejemplo para un carácter melancólico par excellence, el autor traza la historia de la melancolía, de su interpretación y manifestación en las diferentes etapas del cristianismo, en las distintas corrientes filosóficas, artísticas y culturales en Europa desde la antigüedad hasta hoy. La melancolía como estado del alma habitualmente peligroso y sospechoso para el dogmatismo religioso, los sistemas autoritarios y las promesas de felicidad y de progreso del capitalismo, es investigada no sólo respecto a la resignación, no-acción (Hamlet), odio hacia sí mismo (Kierkegaard) que ella provoca, sino también en su potencial creativo y constructivo. El autor identifica como elemento desencadenante de la melancolía en una persona o un grupo social (ilustrándolo paradigmáticamente con el fondo histórico de la Francia del siglo XVID) una pérdida existencial que culmina en el anhelo hacia el pasado y la percepción del presente como carga insoportable. Haciendo hincapié en esta distinta y particular percepción del tiempo del melancólico, que describe como un repetido volver al pasado para encontrar lo perdido, el autor define al arte melancólico (Proust, Kiefer) como medio de reencuentro productivo con el pasado y lugar de cuestionarniento de la felicidad como única solución para la vida. Con una crítica mirada sobre los movimientos de modernización de la segunda mitad del siglo XX, el autor rescata el valor reflexivo y reconstructivo de la melancolía frente a la superficialidad del progreso y la obligación a la felicidad de la modernización, valor que se manifiesta en los movimientos de los siglos XX y XXI de protección del medio ambiente y del patrimonio cultural.</p
Implementierung des Access Control Protocols in den Catacomb WebDAV Server
No full textIm Rahmen dieser Diplomarbeit wurde ein Konzept erstellt, um das im RFC 3744 beschriebene Access Control Protocol in den Catacomb WebDAV Server einzubinden.
Es wurde das WebDAV Protokoll vorgestellt und gezeigt wie der Catacomb Server funktioniert. Dann wurde das Access Control Protocol vorgestellt und ein passendes Datenbankmodell erstellt, das das bereit vorhandene erweitert. Auf Grundlage des Software-Designs wurde dann die ACP Erweiterung für Catacomb und die notwendigen Erweiterungen in dem Apache2 Modul mod_dav implementiert.
Außerdem wurde ein differenzierteres Speicherverhalten in Catacomb implementiert, sodass angegeben werden kann ab welcher Dateigröße Ressourcen im Dateisystem gespeichert werden sollen anstatt in der Datenbank. Als nächstes wurde das Softwareergebnis mit geeigneten Mitteln getestet. Es wurde neben Einzeltests auch automatisierte Programme wie die Litmus WebDAV Server Test Suit zum Testen der Kompatibilität eingesetzt. Dabei wurde ein Bug im WebDAVExplorer entdeckt und mit den Entwicklern besprochen.
Als letztes wurde die Performance des Systems mit einer Auswahl anderer WebDAV Server verglichen und anschließend fand ein ausführlicherer Vergleich der zwei verschiedenen Catacomb Server statt. Dazu wurde der Quellcode der Prestan Performance Test Suit um einige Tests erweitert, um den Anforderungen des DLR gerecht zu werden.
Anschließend wurde die Performance mehrerer WebDAV Server gemessen und gegenübergestellt, ebenso wie der Catacomb Server in einer Version mit und einer ohne Access Control Protocol verglichen wurden. Dabei wurde die Frage untersucht, ob und wie sehr die Implementierung des Access Control Protocols die Geschwindigkeit des Servers beeinflusst hat
The Catacomb WebDAV Server
No full textCatacomb is a WebDAV repository module for use with the Apache WebDAV module, mod_dav. Apache mod_dav parses WebDAV and DeltaV protocol requests into operations on a repository providing persistent storage of resources and their properties. The default repository for mod_dav is provided by a separate module, mod_dav_fs, which stores resource bodies as files in the filesystem, and stores properties in a (G)DBM database. Catacomb provides a replacement for mod_dav_fs called mod_dav_repos that stores resources and their properties in a relational database using mod_dbd from the apache project for database abstraction. The primary advantage of this approach is the searching capabilities of the database are used to implement the DASL protocol. Additionally, the database allows straightforward implementation of the versioning capabilities of the DeltaV protocol.
We will present the current state of development of the catacomb WebDAV server. We also explain the use of catacomb for storing scientific data in the german aerospace center. Finally there will be an outlook of future WebDAV protocol extensions in catacomb and how they will be realized
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