Thermal barrier coating on high temperature industrial gas turbine engines

The thermal barrier coating used was a yttria stabilized zirconia material with a NiCrAlY undercoat, and the base engine used to establish improvements was the P&WA FT50A-4 industrial gas turbine engine. The design benefits of thermal barrier coatings include simplified cooling schemes and the use of conventional alloys in the engine hot section. Cooling flow reductions and improved heating rates achieved with thermal barrier coating result in improved performance. Economic benefits include reduced power production costs and reduced fuel consumption. Over the 30,000 hour life of the thermal barrier coated parts, fuel savings equivalent to $5 million are projected and specific power (megawatts/mass of engine airflow) improvements on the order of 13% are estimated

Joining refractory/austenitic bimetal tubing Supplemental report

Joining bimetal tubing consisting of austenitic stainless steel with inner lining of niobium or tantalu

Plio-Pleistocene time-averaged field in southern Patagonia recorded in lava flows

Paleomagnetic directions were obtained from stepwise alternating-field or thermal demagnetization of 53 lava flows from southern Patagonia (latitudes 49.5°-52.1 °S) that include the Pali-Aike volcanic field and the Meseta Viscachas plateau lavas. In addition to previous Miocene-late Quaternary ages of these flows, 40Ar/39Ar dates spanning from 0.1 to 15.4 Ma were obtained for 17 of the sites. All except one of the magnetic polarities coincide with the expected polarities of the magnetic polarity timescale [Cande and Kent, 1995] for the obtained 40Ar/39Ar ages. The mean direction from 33 sites (eliminating sites <4 Ma) that pass a selection criteria of α95 ≤5° is Dec = 358.7°,Inc = - 68.2°, α95 = 3.5°, a value that coincides within the statistical uncertainty with the direction of the geocentric axial dipole for that area (Inc = - 68.1°). Likewise, the mean virtual geomagnetic pole (VGP) coincides within the statistical uncertainty with the geographic North Pole. The secular variation described by the VGP angular standard deviation for these sites is 17.1°, a value expected for that latitude according to Model G of paleosecular variation [McFadden et al., 1988]. The characteristics of the data presented are optimum for time-averaged field (TAF) studies because of the good age control and good quality of the paleomagnetic data: (1) primary components of magnetization were obtained using principal component analysis [Kirschvink, 1980] from at least five points and maximum angular deviation ≤5°, (2) site means were calculated with Fisher statistics using at least three samples, and (c) 38 of the 53 flows had α95 ≤ 5°. No results (five sites) or high α95 values (≤5°) were obtained primarily from sites affected by lightning.Fil: Mejia, V.. University of Florida; Estados UnidosFil: Opdyke, N. D.. University of Florida; Estados UnidosFil: Vilas, Juan Francisco A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Singer, B. S.. University of Wisconsin; Estados UnidosFil: Stoner, J. S.. State University of Colorado at Boulder; Estados Unido

Coupling between magnetic ordering and structural instabilities in perovskite biferroics: A first-principles study

We use first-principles density functional theory-based calculations to investigate structural instabilities in the high symmetry cubic perovskite structure of rare-earth (R $=$ La, Y, Lu) and Bi-based biferroic chromites, focusing on $\Gamma$ and $R$ point phonons of states with para-, ferro-, and antiferromagnetic ordering. We find that (a) the structure with G-type antiferromagnetic ordering is most stable, (b) the most dominant structural instabilities in these oxides are the ones associated with rotations of oxygen octahedra, and (c) structural instabilities involving changes in Cr-O-Cr bond angle depend sensitively on the changes in magnetic ordering. The dependence of structural instabilities on magnetic ordering can be understood in terms of how super-exchange interactions depend on the Cr-O-Cr bond angles and Cr-O bond lengths. We demonstrate how adequate buckling of Cr-O-Cr chains can favour ferromagnetism. Born effective charges (BEC) calculated using the Berry phase expression are found to be anomalously large for the A-cations, indicating their chemical relevance to ferroelectric distortions.Comment: 8 pages, 13 figure

Market for Luca Pacioli\u27s Summa Arithmetica

This paper looks at an aspect of Luca Pacioli and his Summa Arithmetica that has not previously been explored in detail the market for which he wrote the book. In order to do so, it follows a path identified by two clues in the bookkeeping treatise as to the nature of this market that modern eyes, unaware of how life was in late 15th century Italy, have missed. After discussing the curriculum taught in schools at that time, this paper considers a range of possible markets for which the book may have been written. The paper concludes that it was written primarily for, and sold mainly to, merchants who used the book as a reference text, as a source of pleasure from the mathematical puzzles it contained, and as an aid for the education of their sons

Accounting students' IT applicaton skills over a 10-year period

This paper reports on the changing nature of a range of information technology (IT) application skills that students declare on entering an accounting degree over the period from 1996 to 2006. Accounting educators need to be aware of the IT skills students bring with them to university because of the implications this has for learning and teaching within the discipline and the importance of both general and specific IT skills within the practice and craft of accounting. Additionally, IT skills constitute a significant element within the portfolio of employability skills that are increasingly demanded by employers and emphasized within the overall Higher Education (HE) agenda. The analysis of students' reported IT application skills on entry to university, across a range of the most relevant areas of IT use in accounting, suggest that their skills have continued to improve over time. However, there are significant differential patterns of change through the years and within cohorts. The paper addresses the generalizability of these findings and discusses the implications of these factors for accounting educators, including the importance of recognising the differences that are potentially masked by the general increase in skills; the need for further research into the changing nature, and implications, of the gender gap in entrants' IT application skills; and the low levels of entrants' spreadsheet and database skills that are a cause for concern

Collection of relevant results obtained with the Skylab images by the Institute for Space Research, INPE

There are no author-identified significant results in this report

Pacioli\u27s forgotten book: The Merchant\u27s Ricordanze

Double entry bookkeeping emerged by the end of the 13th century and was adopted by, for example, the Datini of Prato during the 1380s. In the transition from single to double entry evident in the Datini Archives, initially accounting records were kept in an account book called a Ricordanze. Record books of this name were typical of Tuscany and, when such books were first used in Tuscany, businessmen began to use them also as a form of personal diary and autobiographical record. Others not in business followed suit and maintained purely personal biographical diaries of the same name. For those in business, the Ricordanze thus developed into a hybrid: partly autobiography and personal and, partly, a place to record matters relating to his business, including details of transactions and of other matters he did not wish to forget, such as promises, obligations, and conditional agreements. As revealed in the Datini archives for the 14th and 15th centuries, use of a Ricordanze for this purpose was discontinued in the accounting system and the book was replaced with another called a Memoriale, which contained details of all business transactions. By the time Pacioli wrote the first published description of double entry bookkeeping, the Memoriale was identified as one of the three principal account books of that system. The others were the Giornale [journal] and the Quaderno [ledger]. However, largely unnoticed by accounting scholars, towards the end of his treatise, Pacioli also describes another book that merchants would be wise to keep\u27: a Ricordanze. Not a personal Ricordanze nor a hybrid personal plus business Ricordanze, nor a version of a Memoriale. Pacioli,s Ricordanze was intended to serve a very specific purpose: it was a book dedicated to maintaining a record of things that should not be forgotten. As such, it was intended to provide an extra layer of managerial control over the affairs of the merchant beyond that provided by the double entry system. This paper considers the role of Pacioli\u27s Ricordanze, of the records that may be maintained within it, discusses the merits of maintaining a record book of this type, and questions why such a clearly useful device does not appear to have been adopted even though it was described in the same treatise which led to the universal adoption of double entry bookkeeping

ADHD and Attention Problems in Children With and Without Spina Bifida

Objectives: To identify differences in the diagnosis and treatment of attention deficit/hyperactivity disorder (ADHD) between typically developing children and children with spina bifida. Method: Sixty-eight children with spina bifida and 68 demographically matched, typically developing children participated in a larger, longitudinal study. Rates of maternal, paternal, and teacher reports of attention problems, as well as rates of maternal reports of ADHD diagnosis, diagnosing provider, pharmaceutical treatment, mental health treatment, and academic accommodations were obtained at 5 time points over a period of 8 years and were compared across groups. Results: Children with spina bifida were more likely to have an ADHD diagnosis and attention problems. Attention problems and ADHD diagnoses were first reported at earlier time points for children with spina bifida than typically developing children. Among children with ADHD or attention problems, children with spina bifida were more likely to be treated with medication, but they were just as likely to use mental health services and receive resource services at school. Conclusions: Children with spina bifida were diagnosed with ADHD and identified as having attention problems more frequently and at an earlier age. This finding could be due to earlier symptom development, greater parental awareness, or more contact with providers. Among those with ADHD or attention problems, stimulant medication was more likely to be prescribed to children with spina bifida, despite research that suggests it may not be as beneficial for them. Further research on the effectiveness of ADHD pharmacological treatment for children with spina bifida is recommended