Scattering of a fluid-structure coupled wave at a flanged junction between two flexible waveguides

Copyright 2013 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America. The following article appeared in the Journal of the Acoustical Society of America, 134(3), 1939 - 1949 and may be found at http://scitation.aip.org/content/asa/journal/jasa/134/3/10.1121/1.4817891.The scattering of a fluid-structure coupled wave at a flanged junction between two flexible waveguides is investigated. The flange is assumed to be rigid on one side and soft on the other; this enables a solution to be formulated using mode-matching. It is shown that both the choice of the edge conditions imposed on the plates at the junction and the choice of incident forcing significantly affect the transmission of energy along the duct. In particular, the edge conditions crucially affect the transmission of structure-borne vibration but have little effect on fluid-borne noise. Given the singular nature of the velocity field at the flange tip, particular attention is paid to the validity of the mode-matching method. It is demonstrated that the velocity field can be accurately reconstructed by incorporating the Lanczos filter into the truncated modal expansions. The mode-matching method is thus confirmed as an viable tool for this class of problem.The Higher Education Commission, Pakista

Comments on a class of orthogonality relations relevant to fluid-structure interaction

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Box Graphs and Singular Fibers

We determine the higher codimension fibers of elliptically fibered Calabi-Yau fourfolds with section by studying the three-dimensional N=2 supersymmetric gauge theory with matter which describes the low energy effective theory of M-theory compactified on the associated Weierstrass model, a singular model of the fourfold. Each phase of the Coulomb branch of this theory corresponds to a particular resolution of the Weierstrass model, and we show that these have a concise description in terms of decorated box graphs based on the representation graph of the matter multiplets, or alternatively by a class of convex paths on said graph. Transitions between phases have a simple interpretation as `flopping' of the path, and in the geometry correspond to actual flop transitions. This description of the phases enables us to enumerate and determine the entire network between them, with various matter representations for all reductive Lie groups. Furthermore, we observe that each network of phases carries the structure of a (quasi-)minuscule representation of a specific Lie algebra. Interpreted from a geometric point of view, this analysis determines the generators of the cone of effective curves as well as the network of flop transitions between crepant resolutions of singular elliptic Calabi-Yau fourfolds. From the box graphs we determine all fiber types in codimensions two and three, and we find new, non-Kodaira, fiber types for E_6, E_7 and E_8.Comment: 107 pages, 44 figures, v2: added case of E7 monodromy-reduced fiber

Using Machine Learning to Analyze Children’s Drawings as Indicators of Mental Well-Being

Human figure drawings are a well-studied diagnostic tool for emotional distress in children. Cleft lip/palate is one of the most common birth defects in the world, and has been shown to negatively impact emotional well-being in childhood which can have negative economic consequences in adulthood. Utilizing a dataset of human figure drawings from children in India and survey data on mental health, this paper will assess the impact of corrective surgery on mental health outcomes, as well as assess the validity of the drawing emotional indicators themselves. The results indicate that while the emotional indicators may not be valid in predicting emotional distress in this sample, there is a positive relationship between corrective surgery and mental health outcomes

Alpacas and Ecosystems Management

Alpacas are a species that present physiological, anatomical, morphological and behavioural distinctive characteristics compared to other species used in animal production. Empirical observation of a herd, grazing under time management controlled conditions, allowed to approximate some initial observations about the effect of alpacas in the management of ecosystems. Larger green matter availability in the paddocks grazed by alpacas, evident natural weed control, better plants distribution and increasing stocking capacity were the relevant observed issues. It is considered that the special behavioural characteristics of alpacas in terms of excretion habits, low hoof pressure, food conversion efficiency and grazing habits should be factors to be rigourously studied to explore the value of alpacas as an environmentally friendly species.Sustainable farm management, farming systems research, alpacas, Environmental Economics and Policy, Livestock Production/Industries,