Development and characterization of Powder Metallurgy (PM) 2XXX series Al alloy products and Metal Matrix Composite (MMC) 2XXX Al/SiC materials for high temperature aircraft structural applications

The results of a series of material studies performed by the Lockheed Aeronautical Systems Company over the time period from 1980 to 1991 are discussed. The technical objective of these evaluations was to develop and characterize advanced aluminum alloy materials with temperature capabilities extending to 350 F. An overview is given of the first five alloy development efforts under this contract. Prior work conducted during the first five modifications of the alloy development program are listed. Recent developments based on the addition of high Zr levels to an optimum Al-Cu-Mg alloy composition by powder metallurgy processing are discussed. Both reinforced and SiC or B4C ceramic reinforced alloys were explored to achieve specific target goals for high temperature aluminum alloy applications

Guiding e-learning: introducing online informal learning to a global voluntary organisation

The World Association of Girl Guides and Girl Scouts (WAGGGS) is the umbrella organisation for Member Organisations from 145 countries around the world, with a total membership of ten million. While Member Organisations offer training and development within their own countries, WAGGGS offers international opportunities. This project seeks to explore how technology can be used to offer similar opportunities to those provided by the face-to-face courses to a much wider audience, while retaining the community and interactive learning aspects of the existing programmes

Adult Education as Snake Oil under the Guise of Democracy

Based on initial content analysis research into the semiotics of advertising for online learning, this paper extends our understanding of the commodification of education via the web by carefully examining the implications of this marketing on the goals of democracy, the just distribution of education and knowledge as resources, and the consequent impact on social justice and equity

Dewey and Habermas: Re-reading Ethics for Adult Education

The relevance of Dewey and Habermas\u27s ethics for adult education is grounded in epistemology and learning, in particular delineating the centrality of ethics -- normative conceptions of right and wrong -- to how we come to know and understand the world, generate meaning, and hence, learn

A method for continuous239Pu determinations in Arctic and Antarctic ice cores

Atmospheric nuclear weapons testing (NWT) resulted in the injection of plutonium (Pu) into the atmosphere and subsequent global deposition. We present a new method for continuous semi-quantitative measurement of 239Pu in ice cores, which was used to develop annual records of fallout from NWT in ten ice cores from Greenland and Antarctica. The 239Pu was measured directly using an Inductively Coupled Plasma – Sector Field Mass Spectrometer, thereby reducing analysis time and increasing depth-resolution with respect to previous methods. To validate this method, we compared our one year averaged results to published 239Pu records and other records of NWT. The 239Pu profiles from four Arctic ice cores reflected global trends in NWT and were in agreement with discrete Pu profiles from lower latitude ice cores. The 239Pu measurements in the Antarctic ice cores tracked low latitude NWT, consistent with previously published discrete records from Antarctica. Advantages of the continuous 239Pu measurement method are (1) reduced sample preparation and analysis time; (2) no requirement for additional ice samples for NWT fallout determinations; (3) measurements are exactly co-registered with all other chemical, elemental, isotopic, and gas measurements from the continuous analytical system; and (4) the long half-life means the 239Pu record is stable through time

Pragmatism, Postmodernism, and Adult Education: Structure and Agency in the 21st Century

This paper develops a theory that interprets the philosophical schools of American Pragmatism and Continental Postmodernism as important, complementary resources for understanding the effects of structure and agency on the possibilities for learning and meaning-making. This type of theory building can provide for practitioners and scholars a useful framework for negotiating the limited battle between self-determination and structural determination

Stealing Our Smarts: Indigenous knowledge in On-Line Learning

Tell me what you know….Knowledge  and knowing can be a very tricky thing.  Reflect on what you are fairly certain that you know. Self-certainty in human knowledge is a function of metacognition primarily.  This paper addresses how we know what we know about the most primal and fundamental functions in our everyday lives, and equates the ways in which technology has invaded such spaces as romance to the ways in which technology has begun to infiltrate our own understandings of learning.  Through an examination of indigenous knowledge, also thought of as folk knowledge, but meaning that knowledge which is resident within the learner themselves, this paper asserts that we need to move to more of a user-design (Carr, 1997) approach to online learning design and development

Massive Open Online Courses and Educational Equality in China: A Qualitative Inquiry

Although Chinese governments are devoted to the improvement of education, considerable defects such as inequality in education and an increase in educational costs exist in the current education system of China. Massive Open Online Courses (MOOCs) assume the hope of resolving the educational inequality in China with the potential of empowering a diverse population with free, open access to prominent educational resources. This qualitative research project applies narrative inquiry to examine Chinese MOOCs learners’ perceptions of their lived experiences and how MOOCs attend to the problems in Chinese education. The inquiry includes triangulated data in the form of interviews, observations, and online posts. The research finds that MOOCs have limited influence on the issue of educational inequality in China. By identifying the perceptions that Chinese learners have towards MOOCs, this study provides significant implications for the adoption and diffusion of MOOCs in China

Boreal fire records in Northern Hemisphere ice cores: a review

Here, we review different attempts made since the early 1990s to reconstruct past forest fire activity using chemical signals recorded in ice cores extracted from the Greenland ice sheet and a few mid-northern latitude, high-elevation glaciers. We first examined the quality of various inorganic (ammonium, nitrate, potassium) and organic (black carbon, various organic carbon compounds including levoglucosan and numerous carboxylic acids) species proposed as fire proxies in ice, particularly in Greenland. We discuss limitations in their use during recent vs. pre-industrial times, atmospheric lifetimes, and the relative importance of other non-biomass-burning sources. Different high-resolution records from several Greenland drill sites and covering various timescales, including the last century and Holocene, are discussed. We explore the extent to which atmospheric transport can modulate the record of boreal fires from Canada as recorded in Greenland ice. Ammonium, organic fractions (black and organic carbon), and specific organic compounds such as formate and vanillic acid are found to be good proxies for tracing past boreal fires in Greenland ice. We show that use of other species – potassium, nitrate, and carboxylates (except formate) – is complicated by either post-depositional effects or existence of large non-biomass-burning sources. The quality of levoglucosan with respect to other proxies is not addressed here because of a lack of high-resolution profiles for this species, preventing a fair comparison. Several Greenland ice records of ammonium consistently indicate changing fire activity in Canada in response to past climatic conditions that occurred during the last millennium and since the last large climatic transition. Based on this review, we make recommendations for further study to increase reliability of the reconstructed history of forest fires occurring in a given region

Development of powder metallurgy 2XXX series Al alloy plate and sheet materials for high temperature aircraft structural applications, FY 1983/1984

The objective of this investigation is to fabricate and evaluate PM 2124 Al alloy plate and sheet materials according to NASA program goals for damage tolerance and fatigue resistance. Previous research has indicated the outstanding strength-toughness relationship available with PM 2124 Al-Zr modified alloy compositions in extruded product forms. The range of processing conditions was explored in the fabrication of plate and sheet gage materials, as well as the resultant mechanical and metallurgical properties. The PM composition based on Al-3.70 Cu-1.85 Mg-0.20 Mn with 0.60 wt. pct. Zr was selected. Flat rolled material consisting of 0.250 in. thick plate was fabricated using selected thermal mechanical treatments (TMT). The schedule of TMT operations was designed to yield the extreme conditions of grain structure normally encountered in the fabrication of flat rolled products, specifically recrystallized and unrecrystallized. The PM Al alloy plate and sheet materials exhibited improved strength properties at thin gages compared to IM Al alloys, as a consequence of their enhanced ability to inhibit recrystallization and grain growth. In addition, the PM 2124 Al alloys offer much better combinations of strength and toughnessover equivalent IM Al. The alloy microstructures were examined by optical metallographic texture techniques in order to establish the metallurgical basis for these significant property improvements