A finite element for thermal stress analysis of shells of revolution

A new finite element is described for performing detailed thermal stress analysis of thin orthotropic shells of revolution. The element provides for temperature loadings which may vary over the surface of the shell as well as through the thickness. In a number of sample calculations, results from the present method are compared with analytical solutions as well as with independent numerical analyses. Such calculations are carried out for two cylinders, a conical frustum, a truncated hemisphere, and an annular plate. Generally, the agreement between the present solution and the other solutions is excellent

Analysis of a turbine rotor containing a transverse crack at Oak Creek Unit 17

Transient increases in one, two and three per revolution vibration characteristics of a low pressure steam turbine were observed during steam temperature reduction operations. Vibration and fracture mechanics analyses suggested the presence of a transverse shaft crack which was eventually identified by ultrasonic inspection and confirmed by destructive sectioning. Signature analyses of vibration data recorded over a two-year period prior to crack identification are correlated with fatigue crack growth, which occurred intermittently during transient temperature decreases. The apparent increased response of the rotor to vibration is due to asymmetric stiffness changes introduced by the growing transverse crack. The vibration response is predicted to increase with increasing crack depths in excess of 10% of the shaft diameter. Fracture mechanics analyses predict that fatigue crack growth occurred during periods of steam temperature decrease, when high surface tensile stresses are present. These same transient thermal stresses are shown to have retarded and prevented subsequent fatigue crack growth during steady operation

Subscale, hydrogen-burning, airframe-integrated-scramjet: Experimental and theoretical evaluation of a water cooled strut airframe-integrated-scramjet: Experimental leading edge

A water-cooled leading-edge design for an engine/airframe integrated scramjet model strut leading edge was evaluated. The cooling design employs a copper cooling tube brazed just downstream of the leading edge of a wedge-shaped strut which is constructed of oxygen-free copper. The survival of the strut leading edge during a series of tests at stagnation point heating rates confirms the practicality of the cooling design. A finite difference thermal model of the strut was also proven valid by the reasonable agreement of calculated and measured values of surface temperature and cooling-water heat transfer

Mathematics

Contains reports on three research projects

Francis Johnson: Music Master of Early Philadelphia

Guthrie P. Ramsey, Jr., Associate Professor of Music, University of Pennsylvania, delivers a lecture on Francis Johnson (1792-1844), Philadelphia band leader and composer. Johnson holds a special place in the history of American music. Although a free African American, he lived in an age when racial segregation and prejudice were commonplace. Despite these obstacles, he was able to achieve extraordinary renown and respect among the elite of Philadelphia through performances of his band at balls, parades, and promenade concerts. Following a series of concert tours late in his life, Johnson\u27s fame eventually extended through the Midwest and across the Atlantic to London. His music survives today in piano arrangements published during his lifetime. The lecture marked the opening of an exhibition in the Otto E. Albrecht Music Library. The exhibition included a selection from the over forty pieces of Johnson sheet music in the collection of the late Kurt Stein. Also part of the exhibition were prints, period newspaper articles, and a Kent bugle like that favored by Johnson. To download a podcast of the lecture, select one of the additional files below. Welcome, H. Carton Rogers, 00-04:52 Introduction, Richard Griscom, 04:52-13:06 Lecture, Guthrie P. Ramsay, Jr., 13:15-37:27 The event announcement is also available for download, by selecting the download button, at upper right. The exhibition is available in an online version, at: https://web.archive.org/web/20160422121347/https://www.library.upenn.edu/exhibits/music/fjohnson

Spin-injection Hall effect in a planar photovoltaic cell

Successful incorporation of the spin degree of freedom in semiconductor technology requires the development of a new paradigm allowing for a scalable, non-destructive electrical detection of the spin-polarization of injected charge carriers as they propagate along the semiconducting channel. In this paper we report the observation of a spin-injection Hall effect (SIHE) which exploits the quantum-relativistic nature of spin-charge transport and which meets all these key requirements on the spin detection. The two-dimensional electron-hole gas photo-voltaic cell we designed to observe the SIHE allows us to develop a quantitative microscopic theory of the phenomenon and to demonstrate its direct application in optoelectronics. We report an experimental realization of a non-magnetic spin-photovoltaic effect via the SIHE, rendering our device an electrical polarimeter which directly converts the degree of circular polarization of light to a voltage signal.Comment: 14 pages, 4 figure

FEMA's Integration of Preparedness and Development of Robust Regional Offices

In October 2006, Congress enacted major legislation to reform the function and organization of the Federal Emergency Management Agency (FEMA) in response to the recognized failures in preparation for and response to Hurricane Katrina. The Post-Katrina Emergency Management Reform Act of 2006 (PKEMRA) focused national preparedness responsibilities within FEMA and directed additional resources and responsibilities to FEMA's ten regional offices. Directed by Congress, in October 2008 a National Academy Panel began an independent assessment of FEMA's integration of preparedness functions and progress in development of robust regional offices.Main FindingsOver the past three years, FEMA has taken significant steps in an effort to integrate preparedness and develop more robust regional offices. These efforts, undertaken by both the previous and current Administrations, are documented throughout this report and should be recognized and applauded. However, FEMA has yet to define specific goals and outcomes that would permit it, Congress or the public to determine when preparedness has been fully integrated into all aspects of FEMA's work and whether the development and ongoing operation of robust regional offices has been achieved. In the absence of well-defined, measurable outcome indicators, the National Academy Panel relied upon the assessments of FEMA leaders and staff, documentation provided by FEMA, and a review of secondary sources material to inform its findings and recommendations. Based upon this evidence, the Panel has concluded that, while progress has been made: (1) preparedness is not fully integrated across FEMA, (2) FEMA's regional offices do not yet have the capacity required to ensure the nation is fully prepared, (3) stakeholders are not yet full partners with FEMA in national preparedness, and (4) FEMA has ineffective internal business practices, particularly with regard to human resource management. The Panel made seven recommendations for FEMA:Establish a cross-organizational process, with participation from internal and external stakeholders, to develop a shared understanding of preparedness integrationEstablish a robust set of outcome metrics and standards for preparedness integration, as well as a system to monitor and evaluate progress on an ongoing basisWork to eliminate organizational barriers that are adversely impacting the full integration of preparedness across the agencyContinue to build regional office capacity and monitor implementation consistent with the Administrator's recent policy guidanceUndertake steps to improve the ongoing working relationship between headquarters and the regions in accord with Panel-identified principlesTake steps to improve stakeholder engagement and relationships at all levels in accord with Panel-identified principles; andStrengthen internal business practices, especially in the area of human capital planning

On the solution of trivalent decision problems by quantum state identification

The trivalent functions of a trit can be grouped into equipartitions of three elements. We discuss the separation of the corresponding functional classes by quantum state identifications

Effect of the Output of the System in Signal Detection

We analyze the consequences that the choice of the output of the system has in the efficiency of signal detection. It is shown that the signal and the signal-to-noise ratio (SNR), used to characterize the phenomenon of stochastic resonance, strongly depend on the form of the output. In particular, the SNR may be enhanced for an adequate output.Comment: 4 pages, RevTex, 6 PostScript figure

Classifying the Arithmetical Complexity of Teaching Models

This paper classifies the complexity of various teaching models by their position in the arithmetical hierarchy. In particular, we determine the arithmetical complexity of the index sets of the following classes: (1) the class of uniformly r.e. families with finite teaching dimension, and (2) the class of uniformly r.e. families with finite positive recursive teaching dimension witnessed by a uniformly r.e. teaching sequence. We also derive the arithmetical complexity of several other decision problems in teaching, such as the problem of deciding, given an effective coding $\{\mathcal L_0,\mathcal L_1,\mathcal L_2,\ldots\}$ of all uniformly r.e. families, any $e$ such that $\mathcal L_e = \{L^e_0,L^e_1,\ldots,\}$, any $i$ and $d$, whether or not the teaching dimension of $L^e_i$ with respect to $\mathcal L_e$ is upper bounded by $d$.Comment: 15 pages in International Conference on Algorithmic Learning Theory, 201