1,715 research outputs found
Jet noise from instability mode interactions
No full textA nonlinear interaction model is used to study sources of sound in jets. The model uses quadratic interactions of instability modes, which are obtained by solving the linear parabolized stability equations. Source terms involving nonlinear interactions are evaluated and a linear wave equation is solved with direct injection of the source terms. Thus the complete method solves only linear partial differential equations, coupled by nonlinear source terms. It allows the contribution of each modal interaction to be studied separately, giving a breakdown of the radiation pattern of each interaction. The method is demonstrated using a fixed base flow matched to the experiment of Stromberg et al. (J. Fluid Mech. 72(2), 1980). The squared streamwise velocity quadrupole is the largest source term for axisymmetric mode interactions, while for helical-helical mode interactions both the squared radial and squared azimuthal velocities are the main contributing sources, despite a strong cancelation effect between them. Results are also presented for an alternative implementation, in which the base flow is allowed to vary according to the Reynolds stresses of the developing instability modes. This model demonstrates sound production during mode growth and subsequent saturation
Domain Names in Turkey
No full textTurkey faces both unique and common domain name regulatory issues. In this paper, the author focuses on the challenges ahead for Turkey, with especial focus on the regulation of IDNs
Plagiarism: concepts and contexts
No full textAfter outlining the key difficulties in modern literature on academic plaigarism, the author suggests that these may be resolved by a new model of plaigarism (whilst noting that this new model does raise additional uncertainties, e.g. as to the status of 'self plagiarism') that she has developed
Determinação de soluções corretivas na operação de sistemas eletricos atraves de tecnicas de projeção ortogonal
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina. Centro TecnologicoNa operação de um sistema de potência, podem ocorrer eventos que o conduzam a um estado onde existam violações nos limites de tensão das barras e/ou fluxos de potência nas linhas de transmissão. Nestas situações, o operador deve exercer ações de controle corretivo, as quais consistem em ajustes nas variáveis de controle adequadas para cada situação. Este trabalho apresenta um algoritmo baseado no método de projeção ortogonal, cujo objetivo é a eliminação das violações nas magnitudes de tensão das barras do sistema. Busca-se determinar a mínima variação em determinados controles do sistema de potência, tal que os limites naquelas variáveis sejam observados. O problema é formulado em termos da determinação da solução de uma seqüência de sistemas de equações lineares subdeterminadas ou, se para estes não existir solução viável, sobre determinado. Cada sub-problema desta seqüência é alternada com a solução das equações não lineares que apresentam a rede elétrica. São utilizadas matrizes de sensibilidade derivadas das equações linearizadas do fluxo de potência AC, e fatores de ponderação. Tais fatores são necessários para enfatizar ou inibir, quando necessário, a influência de certas variáveis de controle no processo de convergência. Resultados númericos são apresentados para avaliar o desempenho da técnica proposta em termos de precisão, rapidez e confiabilidade para aplicação em sistemas de potência
Dictionary of Acoustics
No full textThe science and technology of acoustics embraces an unusually wide range of disciplines, from aircraft noise reduction to ultrasonics in medicine, from psychoacoustics to signal processing. The student of acoustics has to become familiar with a corresponding range of specialist terms in order to communicate with others and to understand the literature. Here, in one informative dictionary, for the first time, are listed accurate and helpful definitions to provide the student - or the specialist from another discipline - with a point of entry into the world of acoustics. The dictionary's 2,800 entries cover most of the essential concepts and terminology that the practicing acoustician needs to understand, outside the subfields of music and speech communication. The author has drawn on experience gained during a long career spent mostly at Southampton University's multidisciplinary Institute of Sound and Vibration Research, supplemented by the expertise and perspective of a team of subject specialists
Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation
No full textThe desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters
Modelling of turbulent jets and wall layers: extensions of Lighthill's acoustic analogy with application to computational aeroacoustics
No full textTwo extensions to Lighthill’s aeroacoustic analogy are presented. First, equivalent sources due to initial conditions are derived that supplement those due to boundary conditions, as given by Ffowcs Williams & Hawkings. The resulting exact inhomogeneous wave equation is then reformulated with pressure rather than density as the wave variable, and the right-hand side is rearranged using the energy equation with no additional assumptions. Applications to computational aeroacoustics are discussed, and illustrated with examples based on 2D and 3D simulations
Coauthor prediction for junior researchers
No full textResearch collaboration can bring in different perspectives and generate more productive results. However, finding an appropriate collaborator can be difficult due to the lacking of sufficient information. Link prediction is a related technique for collaborator discovery; but its focus has been mostly on the core authors who have relatively more publications. We argue that junior researchers actually need more help in finding collaborators. Thus, in this paper, we focus on coauthor prediction for junior researchers. Most of the previous works on coauthor prediction considered global network feature and local network feature separately, or tried to combine local network feature and content feature. But we found a significant improvement by simply combing local network feature and global network feature. We further developed a regularization based approach to incorporate multiple features simultaneously. Experimental results demonstrated that this approach outperformed the simple linear combination of multiple features. We further showed that content features, which were proved to be useful in link prediction, can be easily integrated into our regularization approach. © 2013 Springer-Verlag
[] to C.L. Thomas, 26 January 1850
No full texthttps://egrove.olemiss.edu/aldrichcorr_b/1214/thumbnail.jp
On excursions of stochastic processes, cox-point processes, entrance behaviour and resolvents
No full textElectrical Engineering, Mathematics and Computer Scienc
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