No description available.

No description available.

No description available.

The forward and reverse flow characteristics have been measured for Zobel type vortex diode with 19 mm throat diameter using superheated stea with inlet pressures up to 12 bar absolute, and exhausting into a subatmospheric condenser to achieve inlet to outlet pressure ratios up to 30 A discharge factor, Cf, which relates the measured mass flow rate to the theoretical mass flow rate of a critical flow through a comparable isentropic nozzle, has been used to describe the resistance of the diode. In the choked region of the forward and reverse flow, Cf has a constant value of 0.95 and 0.38 respectively. The critical pressure ratios in the forward and reverse flow are approximately 2 and 4. Repeating the tests using wet steam with known dryness fractions, ha shown separately the effects of wetness on the diode performance. The forward flow discharge factor in the choked condition is seen to be independent of dryness fraction, and found to lie between 0.9 and 1.0, which is similar to that found with superheated steam. The reverse flow discharge factor in the choked condition varied from about 0.4 for a dryness fraction of, 0.98, to 0.48 for a dryness fraction of 0.92. Excessive steam wetness (quality less than 0.93) in the reverse flow direction led to a build-up of water and when this was eventually swept through to the diode, the resistance was seen to fall substantially as th strong internal vortex was destroyed. This problem can be overcome in practice, however, by installing a water separator before the diode. Reverse flow characteristics of four 10 mm throat diameter Zobel typ vortex diodes have been measured using air with inlet pressure up to 31 bar absolute, and exhausting into atmosphere. The characteristics are seen to be similar to those found with superheated steam, with a value of Cf of 0.38. The effect of installing the four diodes in series was investigated. It was shown that by sharing the pressure drop between the diodes and moving the operating point into the incompressible regime, som of the high resistance performance could be recovered. A detailed study of vortex flow was carried out using a large vortex throttle with superheated steam as the working fluid. The static pressur distribution has been determined experimentally both across the vortex an along the axis of the chamber exit duct. The chamber internal wall temperatures have been obtained using insulated, flush-mounted thermocouples. The measurements enabled the velocity field to be calculated. The bulk of the internal vortex was found to have an exponer. of 0.69. It was found that the vortex throttle choked at an upstream to downstream pressure ratio of about 6 with corresponding Cf value of 0.28. The resistance of vortex chambers is known to be strongly influenced by the presence of reversed flow in the exit, due to vortex breakdown. Schlieren photography of the swirling exhaust flow was used to show that whilst vortex breakdown does occur, it can only do so after the flow has become subsonic downstream of the exit and cannot therefore influence the vortex chamber resistance.

No description available.

No description available.

Approved for public release; distribution is unlimited / Antennas are designed for specific system requirements such as gain, radiation pattern, bandwidth and input impedance and patterns. During this design and testing process, one of the most important steps is the measurement of its radiation pattern to define these critical parameters. Anechoic chambers are used for indoor testing purposes. Ideally they are isolated from all kinds of electromagnetic noise and have absorber coated walls inside. They also are used for radar cross-section (RCS) measurements and electromagnetic interference tests. This thesis examines the performance of the current Naval Postgraduate School anechoic chamber. Different absorbers and antenna patterns are simulated using the Urbana Wireless Toolset. It also includes a noise evaluation of the anechoic chamber. The results of this thesis can be used to guide the users of the existing chamber configuration in setting up tests and assist in any future redesign. / Lieutenant Junior Grade, Turkish Navy

I följande uppsats har en nyfikenhet kring hur högläsning och boksamtal används i förskolor varit huvudområdet. Det har undersökts på tio utvalda förskolor och bland tio yrkesarbetande utvalda pedagoger. Genom observationer på två förskolor och en enkätundersökning bland tio yrkesarbetande pedagoger på tio utvalda förskolor har Marie-Anne Lyckman och Ann-Cathrin Jönsson kommit fram till ett resultat och en tolkning av det. Detta redovisas i två metoddelar för respektive förskola samt en metoddel för enkätfrågorna till de tio utvalda pedagogerna. Tillsammans med varje metoddel finns en resultatdel. Vad forskare och teoretiker beskriver i sin litteratur har tillsammans med metoder och resultat bildat en helhet där tolkningar och undersökningar blivit diskuterat.

Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Brophy, Christopher M. Second Reader: Hobson, Garth V. "December 2009." Description based on title screen as viewed on January 28, 2010. Author(s) subject terms: Pulse Detonation Combustors, PDC, Pulse Detonation Engines, PDE, PDE ignition, PDE initiation, low-loss obstacles, ramp, swept ramp, DDT, DDT initiation. Includes bibliographical references (p. 89-90). Also available in print.

Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Jose O. Sinibaldi, Garth V. Hobson. Includes bibliographical references (p. 69). Also available online.