74,159 research outputs found
Adjoint Computation for Hypersurfaces Using Formal Desingularizations
We show how to use formal desingularizations (defined earlier by the first
author) in order to compute the global sections (also called adjoints) of
twisted pluricanonical sheaves. These sections define maps that play an
important role in the birational classification of schemes.Comment: 10 page
Cryogenic wind tunnel technology. A way to measurement at higher Reynolds numbers
The goals, design, problems, and value of cryogenic transonic wind tunnels being developed in Europe are discussed. The disadvantages inherent in low-Reynolds-number (Re) wind tunnel simulations of aircraft flight at high Re are reviewed, and the cryogenic tunnel is shown to be the most practical method to achieve high Re. The design proposed for the European Transonic Wind tunnel (ETW) is presented: parameters include cross section. DISPLAY 83A46484/2 = 4 sq m, operating pressure = 5 bar, temperature = 110-120 K, maximum Re = 40 x 10 to the 6th, liquid N2 consumption = 40,000 metric tons/year, and power = 39,5 MW. The smaller Cologne subsonic tunnel being adapted to cryogenic use for preliminary studies is described. Problems of configuration, materials, and liquid N2 evaporation and handling and the research underway to solve them are outlined. The benefits to be gained by the construction of these costly installations are seen more in applied aerodynamics than in basic research in fluid physics. The need for parallel development of both high Re tunnels and computers capable of performing high-Re numerical analysis is stressed
Red-giant stars in eccentric binaries
The unparalleled photometric data obtained by NASA’s Kepler Space Telescope has led to improved understanding of red-giant stars and binary stars. We discuss the characterization of known eccentric system, containing a solar-like oscillating red-giant primary component. We also report several new binary systems that are candidates for hosting an oscillating companion. A powerful approach to study binary stars is to combine asteroseimic techniques with light curve fitting. Seismology allows us to deduce the properties of red giants. In addition, by modeling the ellipsoidal modulations we can constrain the parameters of the binary system. An valuable independent source are ground-bases, high-resolution spectrographs
Experience, expertise and expert-performance research in public accounting
Bibliography: p. [22-25]
Speaking of Music and the Counterpoint of Copyright: Addressing Legal Concerns in Making Oral History Available to the Public
Oral history provides society with voices and memories of people and communities experiencing events of the past first-hand. Such history is created through interviews; an interview, however, like any other type of intellectual property—once in a fixed form—is subject to copyright law. In order to make oral history available to the public, it is critically important that individuals generating and acquiring oral history materials clearly understand relevant aspects of copyright law. The varied nature of how one may create, use, and acquire oral history materials can present new, surprising, and sometimes baffling legal scenarios that challenge the experience of even the most skilled curators.
This iBrief presents and discusses two real-world scenarios that raise various issues related to oral history and copyright law. These scenarios were encountered by curators at Yale University’s Oral History of American Music archive (OHAM), the preeminent organization dedicated to the collection and preservation of recorded memoirs of the creative musicians of our time. The legal concerns raised and discussed throughout this iBrief may be familiar to other stewards of oral history materials and will be worthwhile for all archivists and their counsel to consider when reviewing their practices and policies
Analytical reliability calculation of linear dynamical systems in higher dimensions
The recent application of reliability analysis to controller synthesis has created the need for a
computationally efficient method for the estimation of the first excursion probabilities for linear dynamical
systems in higher dimensions. Simulation methods cannot provide an adequate solution to this specific application,
which involves numerical optimization of the system reliability with respect to the controller parameters,
because the total computational time needed is still prohibitive. Instead, an analytical approach is presented
in this paper. The problem reduces to the calculation of the conditional upcrossing rate at each surface
of the failure boundary. The correlation between upcrossings of the failure surface for the different failure
events may be addressed by the introduction of a multi-dimensional integral. An efficient algorithm is
adopted for the numerical calculation of this integral. Also, the problem of approximation of the conditional
upcrossing rate is discussed. For the latter there is no known theoretical solution. Three of the semi-empirical
corrections that have been proposed previously for scalar processes are compared and it is shown that the correction
should be based on the bandwidth characteristics of the system. Finally, examples that verify the validity
of the analytical approximations for systems in higher dimensions are discussed
Common Bulkhead Joint Development and Evaluation Final Report
Optimized composite welded joint design for Saturn booster common bulkhea
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