Preliminary investigation of high power microwave plasmas for electrothermal thruster use

Results are reported from preliminary tests to evaluate the high power microwave electrothermal thruster (MET) concept, which employs a free-floating plasma discharge maintained by applied CW microwave power to heat a propellant gas flow. Stable plasmas have been created and maintained in helium (He), nitrogen (N2), and hydrogen (H2) as propellants in both the TM(sub 011) and TM(sub 012) modes at discharge pressures from 10 Pa to 69 kPa. Reproducible starting conditions of pressure and power have been documented for all the plasmas. Vortical inflow of the propellant gas was observed to cause the formation of on-axis 'spike' plasmas. The formation and unformation conditions of these plasmas were studied. Operation in the spike plasma condition enables maximum power absorption with minimum wall heating and offers maximum efficiency in heating the propellant gas. In the spike condition, plasmas of the three propellant gases were investigated in an open channel configuration to a maximum applied power level of 11.2 kW (in N2). Microwave power coupling efficiencies of over 90 percent were routinely obtained at absorbed power levels up to 2 kW. Magnetic nozzle effects were investigated with a superconducting solenoid Al magnet applying a high magnetic field to the plasmas in and exiting from the discharge tube

Overview of Translational Biomedical Research and the UMass Center for Clinical & Translational Science

This seminar provides an overview of the resources and infrastructure available to UMass researchers conducting clinical and translational research

Constructing the Cable Television Market in Latin America: A Structurational Approach to Organizational Knowledge in U.S. Cable Networks

Scholars with a keen interest in the globalization of media content have examined trends in international entertainment flows, focusing particular attention on the market structures and business realities which sustain information disparities between the United States and other nations around the globe. However, few scholars have connected the operation of international media markets with the methods by which individuals within transnational media companies obtain knowledge about a foreign market for use in decision-making about activities in that market. This study takes a new approach, utilizing structuration theory by conceptualizing cable networks as knowledgeable, reflexive agents that make decisions within existing market and institutional structures. Using data gathered from trade publications, internal company communications, and indepth interviews, this dissertation describes and analyzes how American cable networks gather information from a new market environment, how they process data into market knowledge, and how this information is ultimately utilized in making decisions about market activities. The data were gathered through qualitative, in-depth interviews with 33 individuals working for seven different U.S. cable networks that have introduced new services in countries throughout Latin America. The qualitative data were supplemented with market data published in trade publications and with information from several cable industry observers. Results suggest that the most important types of market information for U.S. cable executives were data from two quantitative, syndicated market research studies of audience/consumer behavior, which were particularly crucial for cementing financial relationships with advertisers and local cable operators. Executives attempted to compensate for information gaps by accepting these current gaps, by estimating certain numbers, and sometimes by investing in their own market research. Very little of the market information gathered was put to use for internal decision-making regarding programming choices. Instead, audience ratings data were used by executives to build their own market reputation and to differentiate their services from their competitors’. Analysis of market data suggests that cable networks owned by large U.S. media conglomerates have begun to far outpace their Latin American-owned competitors, partially by redefining the standards for market performance. The implications of these trends for structuration theory and media globalization are discussed

Graduate Recital:John L. Sullivan, Guitar

Kemp Recital Hall Monday Evening February 23, 2004 7:00p.m

The role of oxidation in the protection of sliding metal surfaces

This study is concerned with the mechanisms of growth and wear of protective oxide films formed under various tribological conditions. In the study three different tribological systems are examined in each of which oxidational wear is the dominant equilibrium mode. These are an unlubricated steel on steel system sliding at low and elevated temperatures, a boundary lubricated aluminium bronze on steel system and an unlubricated reciprocating sliding 9% Cr steel system operated at elevated temperature, in an atmosphere of carbon dioxide. The results of mechanical measurements of wear and friction are presented for a range of conditions of load, speed and temper.ature for the systems, together with the results of extensive examinations of the surfaces and sub­ surfaces by various physical methods of analysis. The major part of the thesis, however, is devoted to the development and application of surface models and theoretical quantative expressions in order to explain the observed oxidational wear phenomena. In this work, the mechanisms of formation of load bearing ox ide plateaux are described and are found to be dependent on system geometry and environment. The relative importance of ''in contact" and "out of contact" oxidation is identified together with growth rate constants appropriate to the two situations. Hypotheses are presented to explain the mechanisms of removal of plateaux to form wear debris. The latter hypotheses include the effects of cyclic stressing and dislocation accumulation, together with effects associated with the kinetics of growth and physical properties of the various oxides. The proposed surf ace mode1s have led to the develop­ ment of quantitative expressions for contact temperature, unlubricated wear rates, boundary lubricated wear rates and the wear of rna ter ial during the transition from severe to mild wear. In general theoretical predictions from these expressions are in very good agreement with experimental values

Simulation and Measurement of Windows with Low Emissivity Coatings Used in Conjunction with Teflon Inner Glazings

Theoretical work has illustrated that highly infrared, transparent plastic films are well suited for use as intermediate glazings when used in conjunction with a low emissivity coating. Prototype glazing systems that incorporate low emissivity coatings and Teflon films were constructed. The thermal resistance of each of these prototypes was measured using the University of Waterloo Natural Convection Apparatus. Simulation of the glazing systems was carried out using a two-band glazing system thermal analysis program called VISION. Comparison between measurement and simulation showed good agreement. It can be concluded that highly infrared transparent intermediate glazings can be useful when high thermal resistance is desired and that the VISION glazing system analysis program is useful not only for parametric and sensitivity investigations but can also be used with confidence to estimate U-values of specific glazing systems.Renewable Energy Branch of the Department of Energy, Mines and Resource

A two-dimensional numerical model for natural convection in a vertical, rectangular window cavity

© 1994 ASHRAE (www.ashrae.org). Published in ASHRAE Transactions 1994, Vol. 100, Part 2. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE`s prior written permissionIt is common for sealed glazing units to exhibit condensation problems when operated in cold climates. Condensation often forms along the perimeter of the exposed surface of the indoor glazing because of the thermal short circuit caused by the edge seal. Furthermore, condensation most readily forms along the bottom edge of the indoor glazing because of the combined effects of edge seal conduction and fill gas convection. A simple two-dimensional numerical control volume formulation is presented that can be used to model the natural convection of gas within a vertical, rectangular cavity. Details of a unique perturbation scheme used to generate secondary cells are also presented This model closely reproduces the average Nusselt number results of more complex numerical models. Average and local Nusselt numbers have also been compared with experimental results and close agreement has been demonstrated for conditions typical of window cavities.Energy efficiency technology division || CANMET || Department of Energy || Mines and Resources Canada || Natural Sciences and Engineering Research Council of Canad