Electric Wheel-Hub-Drive for Aircraft Application

The German Centre for Aerospace, Institute of Vehicle Concepts, has designed and built a prototype of an electric nose wheel drive for its research aircraft Airbus A320. In this paper the requirements and interfaces, the design of the drive and the test results are described

Immobilienpreise: Ist die Entwicklung am deutschen Wohnungsmarkt noch fundamental gerechtfertigt?

Die Wohnimmobilienpreise in Deutschland sind in den vergangenen Jahren kräftig gestiegen, vor allem in den Metropolen München und Berlin. Diese Entwicklung weckt die Befürchtung, dass sich in Deutschland, ähnlich wie in Spanien oder dem Vereinigten Königreich, eine spekulative Immobilienpreisblase aufbaut. Mithilfe des Wohnnutzerkostenkonzepts lässt sich jedoch zeigen, dass die aktuelle Preisentwicklung in den meisten Kreisen nach wie vor fundamental gerechtfertigt ist. Die teilweise starken Preiserhöhungen sind Ausdruck von Nachholeffekten, bedingt durch größtenteils stagnierende oder sogar fallende Immobilienpreise bis zum Jahr 2008. Selbst eine plötzliche Umkehrung der Niedrigzinspolitik würde nur einen geringen Korrekturbedarf auslösen, der typisch für eine spekulative Blase wäre. Das Risiko einer spekulativen Blase ist damit gering, wenngleich eine dauerhafte Niedrigzinspolitik die Gefahr beinhaltet, dass sich die Verhaltensmuster künftig ändern könnten

The Design, Manufacture, and Testing of a Novel Adhesion System for a Climbing Vehicle

We present the design and fabrication of a prototype wall-climbing vehicle employing a unique combined locomotion and adhesion system in which the adhesive vacuum is transmitted through moving, perforated treads. Implementing the adhesion/drive system involved a broad range of design challenges, including: developing reliable sealing of sliding and static interfaces, understanding the frictional interactions between the drive treads and various vehicle components and surfaces on which they ride, as well as designing for lightness, manufacturability, and adjustability. The clean sheet design presented in this thesis was taken from concept to functioning prototype in less than 6 months, requiring a considered mix of off-the-shelf components, custom fabrication, and outsourced production. Proof of concept testing is reviewed, including static pressure and force results as well as dynamic vertical surface maneuverability trials

Using DCCP: Issues and improvements

is no longer too young to be usable: the first RFCs were published in 2006, and a stable and quite complete Linux implementation exists. DCCP over UDP has also recently been specified to address network traversal problems. But how good is the service provided to applications by this protocol? This paper identifies some deficiencies of the current implementation—the lack of transparency in the API with regard to packet loss, the coarse granularity of the lookup table used to calculate the TFRC equation, and the lack of history discounting in CCID-3—and demonstrates that they can significantly impair the performance of typical DCCP use cases such as live video streaming. Solutions are proposed to tackle all these problems, and it is shown that they considerably improve the performance and the flexibility of applications. I

Entwicklungsansatz für On Bord - Ladesysteme

Zur Erhöhung der Reichweite von konventionellen Elektrofahrzeugen bietet sich der Einsatz von Range-Extender-Modulen auf Basis von Brennstoffzellen an. Am Institut für Fahrzeugkonzepte des Deutschen Zentrums für Luft- und Raumfahrt wird die Eignung von Hochtemperatur-PEM–Brennstoffzellen erforscht. Diese Brennstoffzellen weisen neben elektrischen Wirkungsgraden von ~ 40 % auch hohe Abwärmetemperaturen auf einem Temperaturniveau von T ~170 °C auf. Zur Konzeptvalidierung wurde ein Brennstoffzellenprüfstand aufgebaut, um die Aufheizzeit und die dafür benötigte Energiemenge zu bestimmen. Durch ein neues Brennstoffzellenkühlsystem werden Einsparpotentiale beim stationären Erhaltungsheizen erwartet. Weiter wird durch das neue Kühlsystem eine Verbesserung der Wärmenutzung angestrebt. Außerdem wird der Klimatisierungsbedarf eines Demonstratorfahrzeugs anhand von verschiedenen klimatischen Bedingungen am Klimarollenprüfstand untersucht. Dadurch wird eine Dimensionierungs- und Validierungsgrundlage sowohl für die im Projekt erstellten Simulationsmodelle als auch für das Thermomanagementkonzept geschaffen. Die gewonnen Daten dienen nach der Integration des Brennstoffzellensystems ins Fahrzeug als Vergleichs-grundlage. Dieser Beitrag fasst die Ergebnisse zusammen

Optimizing excitation coil currents for advanced magnetorelaxometry imaging

Magnetorelaxometry imaging is a highly sensitive technique enabling noninvasive, quantitative detection of magnetic nanoparticles. Electromagnetic coils are sequentially energized, aligning the nanoparticles’ magnetic moments. Relaxation signals are recorded after turning off the coils. The forward model describing this measurement process is reformulated into a severely ill-posed inverse problem that is solved for estimating the particle distribution. Typically, many activation sequences employing different magnetic fields are required to obtain reasonable imaging quality. We seek to improve the imaging quality and accelerate the imaging process using fewer activation sequences by optimizing the applied magnetic fields. Minimizing the Frobenius condition number of the system matrix, we stabilize the inverse problem solution toward model uncertainties and measurement noise. Furthermore, our sensitivity-weighted reconstruction algorithms improve imaging quality in lowly sensitive areas. The optimization approach is employed to real measurement data and yields improved reconstructions with fewer activation sequences compared to non-optimized measurements

Stand-Alone Battery Thermal Management for Fast Charging of Electric Two Wheelers - Integrated Busbar Cooling

This paper presents a thermal interface for cylindrical cells using busbar-integrated cooling channels. This interface is available due to the use of a stand-alone refrigerant circuit for the thermal management of the battery. A stand-alone refrigerant circuit offers performance and efficiency increases compared to state-of-the-art battery thermal management systems. This can be achieved by increasing the evaporation temperature to the requirements of the Li-ion cells and the use of alternative refrigerants. The solution proposed in this paper is defined for electric two-wheelers, as the thermal management of these vehicles is currently insufficient for fast charging where high heat losses occur. Three channel patterns for the integrated busbar cooling were examined regarding their thermal performance to cool the li-ion cells of a 16p14s battery pack during fast charging. A method of coupling correlation-based heat transfer and pressure drop with thermal finite element method (FEM) simulations was developed. The symmetric channel pattern offers a good compromise between battery temperatures and homogeneity, as well as the best volumetric and gravimetric energy densities on system level. Average cell temperatures of 22 °C with a maximum temperature spread of 8 K were achieved

study protocol for a randomized-controlled trial

Background Functional abdominal pain (FAP) is not only a highly prevalent disease but also poses a considerable burden on children and their families. Untreated, FAP is highly persistent until adulthood, also leading to an increased risk of psychiatric disorders. Intervention studies underscore the efficacy of cognitive behavioral treatment approaches but are limited in terms of sample size, long-term follow-up data, controls and inclusion of psychosocial outcome data. Methods/Design In a multicenter randomized controlled trial, 112 children aged 7 to 12 years who fulfill the Rome III criteria for FAP will be allocated to an established cognitive behavioral training program for children with FAP (n = 56) or to an active control group (focusing on age-appropriate information delivery; n = 56). Randomization occurs centrally, blockwise and is stratified by center. This study is performed in five pediatric gastroenterology outpatient departments. Observer- blind assessments of outcome variables take place four times: pre-, post-, 3- and 12-months post-treatment. Primary outcome is the course of pain intensity and frequency. Secondary endpoints are health-related quality of life, pain- related coping and cognitions, as well as selfefficacy. Discussion This confirmatory randomized controlled clinical trial evaluates the efficacy of a cognitive behavioral intervention for children with FAP. By applying an active control group, time and attention processes can be controlled, and long-term follow-up data over the course of one year can be explored