Advanced Rankine and Brayton cycle power systems: Materials needs and opportunities

Conceptual advanced potassium Rankine and closed Brayton power conversion cycles offer the potential for improved efficiency over steam systems through higher operating temperatures. However, for utility service of at least 100,000 hours, materials technology advances will be needed for such high temperature systems. Improved alloys and surface protection must be developed and demonstrated to resist coal combustion gases as well as potassium corrosion or helium surface degradation at high temperatures. Extensions in fabrication technology are necessary to produce large components of high temperature alloys. Long time property data must be obtained under environments of interest to assure high component reliability

High temperature environmental effects on metals

The gas turbine engine was used as an example to predict high temperature environmental attack on metals. Environmental attack in a gas turbine engine derives from high temperature, combustion products of the air and fuel burned, and impurities. Of all the modes of attack associated with impurity effects, hot corrosion was the most complicated mechanistically. Solutions to the hot corrosion problem were sought semi-empirically in: (1) improved alloys or ceramics; (2) protective surface coating; (3) use of additives to the engine environment; and (4) air/fuel cleanup to eliminate harmful impurities

Toward more environmentally resistant gas turbines: Progress in NASA-Lewis programs

A wide range of programs are being conducted for improving the environmental resistance to oxidation and hot corrosion of gas turbine and power system materials. They range from fundamental efforts to delineate attack mechanisms, allow attack modeling and permit life prediction, to more applied efforts to develop potentially more resistant alloys and coatings. Oxidation life prediction efforts have resulted in a computer program which provides an initial method for predicting long time metal loss using short time oxidation data by means of a paralinear attack model. Efforts in alloy development have centered on oxide-dispersion strengthened alloys based on the Ni-Cr-Al system. Compositions have been identified which are compromises between oxidation and thermal fatigue resistance. Fundamental studies of hot corrosion mechanisms include thermodynamic studies of sodium sulfate formation during turbine combustion. Information concerning species formed during the vaporization of Na2SO4 has been developed using high temperature mass spectrometry

The Diary of an internship in municipal public administration as performed at the Planning Department, City Hall, Chicago, Illinois June 8, 1964 - August 21, 1964

Diary in lieu of thesis (M.P.A. - Public Administration) --University of Arizona

“Let’s Wait and See!” The Real Option to Switch as a Value Component of Customer Relationships

Contains fulltext : 112218.pdf (publisher's version ) (Open Access)We suggest that a customer’s option to switch suppliers, and to wait and see before switching, adds to customer value in uncertain markets, and affects the customer’s switching behavior. We use a real options model to examine the value of this option and conduct sensitivity analyses based on data collected from the German public health insurance market to support our argument. We elaborate on the customer value construct and show how it contributes to customers’ behavioral loyalty. We also provide guidelines for managers of in-suppliers and out-suppliers on how to use the value of customers’ option to switch, e.g., for pricing decisions and management of customer churn.25 p