Investigation of passive flow control techniques to enhance the stall characteristics of a microlight aircraft

This report investigates the enhancement of aerodynamic stall characteristics of a Skyranger microlight aircraft by the use of passive flow control techniques, namely vortex generators and turbulators. Each flow control device is designed and scaled to application conditions. Force balance measurements and surface oil flow visualisation are carried out on a half-model of the microlight to further investigate the nature of the flow on the aircraft with and without the flow control devices. The results indicate a clear advantage to the use of turbulators compared with vortex generators. Turbulators increased the maximum lift coefficient by 2.8%, delayed the onset of stall by increasing the critical angle by 17.6% and reduced the drag penalty at both lower (pre-stall) and higher angles of attack by 8% compared to vortex generators. With vortex generators applied, the results indicated a delayed stall with an increase in the critical angle by 2% and a reduced drag penalty at higher angles of attack

Static Testing of Propulsion Elements for Small Multirotor Unmanned Aerial Vehicles

The growing use of small multirotor aircraft has increased the interest in having better performance results especially with the propulsion system. The size of the propellers used on these aircraft operate at low Reynolds numbers that are typically less than 200,000. Static performance testing of ten propeller pairs (tractor and pusher) were completed and is the beginning of a systematic test of propellers used on multirotor systems. The propellers chosen for this initial set of tests were selected from four popular quadrotors. Besides testing the propellers provided with the aircraft, propellers that are sold as replacements from third-party companies were also tested. Both the 3D Robotics Solo and DJI Phantom 3 had multiple propellers tested and a method to compare the resulting endurance is discussed

Internal Transcribed Spacer 2 (nu ITS2 rRNA) Sequence-Structure Phylogenetics: Towards an Automated Reconstruction of the Green Algal Tree of Life

L). Some have advocated the use of the nuclear-encoded, internal transcribed spacer two (ITS2) as an alternative to the traditional chloroplast markers. However, the ITS2 is broadly perceived to be insufficiently conserved or to be confounded by introgression or biparental inheritance patterns, precluding its broad use in phylogenetic reconstruction or as a DNA barcode. A growing body of evidence has shown that simultaneous analysis of nucleotide data with secondary structure information can overcome at least some of the limitations of ITS2. The goal of this investigation was to assess the feasibility of an automated, sequence-structure approach for analysis of IT2 data from a large sampling of phylum Chlorophyta.Sequences and secondary structures from 591 chlorophycean, 741 trebouxiophycean and 938 ulvophycean algae, all obtained from the ITS2 Database, were aligned using a sequence structure-specific scoring matrix. Phylogenetic relationships were reconstructed by Profile Neighbor-Joining coupled with a sequence structure-specific, general time reversible substitution model. Results from analyses of the ITS2 data were robust at multiple nodes and showed considerable congruence with results from published phylogenetic analyses.Our observations on the power of automated, sequence-structure analyses of ITS2 to reconstruct phylum-level phylogenies of the green algae validate this approach to assessing diversity for large sets of chlorophytan taxa. Moreover, our results indicate that objections to the use of ITS2 for DNA barcoding should be weighed against the utility of an automated, data analysis approach with demonstrated power to reconstruct evolutionary patterns for highly divergent lineages

Governance im Politikfeld Wirtschaftspolitik

This paper gives an overview of the topic "economic governance". This term is used in economics and neighboring social sciences as a generic term under which usually all activities are subsumed that are conducted by economic policymakers to 'steer' or 'control' the economic system, individual markets therein or certain economic actors (e.g., businesses, consumers). In addition to a more detailed clarification of the concept of "economic governance" and the presentation of actors and instruments of economic governance, the paper discusses why and in what situations economic governance is necessary. The latter issue is the subject of a continuing debate in politics, the public and the social sciences

Entwicklung des parametrischen Netzgenerierungssystems MegaCads

Das Netzgenerierungssystem MegaCads (Multiblock-Elliptic- Grid-Generation-And CAD-System) ermoeglicht die interaktive Konstruktion von Blockgrenzen, die Verteilung von Punkten, die Generierung von Netzen auf Oberflaechen und von Volumennetzen. Die gesamte Konstruktion erfolgt parametrisch und jeder Schritt wird mit Hilfe einer Skriptsprache dokumentiert. Zusammen mit der integrierten "Restart-Faehigkeit" ist es moeglich Parametervariationen einfach durchzufuehren

The Parametric Grid Generation System MegaCads.

The progress of the development of the interactive and parametric grid generation system MegaCads is presented. MegaCads enables the user to define arbitrary grid topologies and to create surface and volume grids. The complete grid generation sequence is performed in a parametric way and stored in a script file. Together with interactive editing, the sequence can be reused for different geometries with a minimum of user interactions. The currently implemented CAD and grid generation techniques as well as grid examples are presented

Entwicklung des parametrischen Netzgenerierungssystems MegaCads, Statusbericht 1-96

Neben dem Entwicklungsstand des Netzgenerierungssystems MegaCads (1(96) wird das parametrische Konzept, die Skript- datei Technik sowie die Programmstruktur erlaeutert. Erste Anwendungsbeispiele im Zwei- und Dreidimensionalen zeigen die grundsaetzlichen Moeglichkeiten von MegaCads