Interaction of linear waves with an array of infinitely long horizontal circular cylinders in a two-layer fluid of infinite depth

The linear water wave scattering and radiation by an array of infinitely long horizontal circular cylinders in a two-layer fluid of infinite depth is investigated by use of the multipole expansion method. The diffracted and radiated potentials are expressed as a linear combination of infinite multipoles placed at the centre of each cylinder with unknown coefficients to be determined by the cylinder boundary conditions. Analytical expressions for wave forces, hydrodynamic coefficients, reflection and transmission coefficients and energies are derived. Comparisons are made between the present analytical results and those obtained by the boundary element method, and some examples are presented to illustrate the hydrodynamic behavior of multiple horizontal circular cylinders in a two-layer fluid. It is found that for two submerged circular cylinders the influence of the fluid density ratio on internal-mode wave forces is more appreciable than surface-mode wave forces, and the periodic oscillations of hydrodynamic results occur with the increase of the distance between two cylinders; for four submerged circular cylinders the influence of adding two cylinders on the wave forces of the former cylinders is small in low and high wave frequencies, but the influence is appreciable in intermediate wave frequencies.

Interaction of linear waves with infinitely long horizontal cylinders studied by boundary element method

The two-dimensional problems concerning the interaction of linear water waves with cylinders of arbitrary shape in two-layer deep water are investigated by use of the Boundary Integral Equation method (BIEM). Simpler new expressions for the Green functions are derived, and verified by comparison of results obtained by BIEM with these by an analytical method. Examined are the radiation and scattering of linear waves by two typical configurations of cylinders in two-layer deep water. Hydrodynamic behaviors including hydrodynamic coefficients, wave forces, reflection and transmission coefficients and energies are analyzed in detail, and some interesting physical phenomena are observed.

Universal Biot number determining stress duration and susceptibility of ceramic cylinders to quenching

A universal Biot number, which not only describes the susceptibility of ceramic cylinders to quenching but also determines the duration that ceramic cylinders are subjected to thermal stress during thermal shock, is theoretically obtained. The analysis proves that thermal shock failure of ceramic cylinders with a Biot number greater than the critical value is a rapid process, which only occurs in the initial heat conduction regime. The results provide a guide to the selection of ceramic materials for thermostructural engineering, with particular reference to thermal shock.

Self-assembly of crystalline-coil diblock copolymer in solvents with varying selectivity: From spinodal-like aggregates to spheres, cylinders, and lamellae

We have investigated systematically the morphology of thin films spin-coated from solutions of a semicrystalline diblock copolymer, poly(L-lactic acid)-block-polystyrene (PLLA-b-PS), in solvents with varying selectivity. In neutral solvents (chloroform and tetrahydrofuran (THF)), a spinodal-like pattern was obtained and the pattern boundary was sharpened by diluting the solution. Meanwhile, loose spherical associates, together with larger aggregates composed of these associates by unimer bridges, formed partly due to crystallization of the PLLA blocks in relatively concentrated solutions. In slightly PS-selective solvent (e.g., benzene), both loose and compact spherical micelles were obtained, depending on the polymer concentration, coexisting with unimers. When enhancing the selectivity with mixed solvents, for example, mixing the neutral solvent and the slightly selective solvent with a highly PS-selective solvent, CS2, loose assemblies (nanorods in CS2/THF mixtures and polydisperse aggregates in CS2/benzene mixtures) and well-developed lamellar micelles were obtained.

Preparation of Pb-Ca-Na master alloy using molten chloride salt electrolysis

An electrolysis technique for co-deposition of Ca2+ and Na+ at the liquid lead cathode was put forward. The experiment was carried out at an electrolysis temperature below 650 degrees C and had a current efficiency of 98%, which are respectively 100 similar to 300 degrees C lower and 15% similar to 30% higher than those reported both at home and abroad.

Effective elastic properties of piezoelectric composites with radially polarized cylinders

Effective elastic properties of piezoelectric composites containing an infinitely long, radially polarized cylinder embedded in an isotropic non-piezoelectric matrix are theoretically investigated under an external strain field. Analytical solutions of elastic displacement and electric potentials are exactly derived, and the effective elastic responses are formulated in the dilute limit. Meanwhile, a vanishing piezoelectric response mechanism is revealed in the piezoelectric composite containing radially polarized cylinders. Furthermore, it is shown that the effective elastic properties can be enhanced (or reduced) due to the increase of the piezoelectric (or dielectric) constants of the cylinders. (C) 2009 Elsevier B.V. All rights reserved.

Feedback Unbound: from master to usher.

A major theme of this book is that feedback should encourage dialogue; between students and lecturers, amongst peers and individually, as a form of self-critique and reflection. Here we endorse that theme but also propose an understanding of dialogue that goes beyond simple exchang or the presence of two or more voices. Inspired by Freire’s (1996) critical pedagogy we seek to make a link between the social nature of learning, the social nature of dialogue and the role of feedback as dialogue in a broader transformative learning process, and not merely as an adjunct to assessment.

Use of library and information science journals by Master?s students in their dissertations: experiences at the University of Wales Aberystwyth

Tedd, L.A. (2006).Use of library and information science journals by Master?s students in their dissertations: experiences at the University of Wales Aberystwyth. Aslib Proceedings: New Information Perspectives, 58(6), 570-581.

The Legacy of Oboist and Master Teacher, Robert Bloom

Robert Bloom (1908-1994) was legendary in the education and performance world. Often hailed as one of the last performers of the Golden Era of classical music and a favorite of conductors ranging from Stokowski to Stravinsky to Shaw, Bloom was an orchestral oboist and English hornist, oboe soloist, chamber musician, teacher (Eastman, Yale, Hartt, Manhattan School of Music, Juilliard and Philadelphia's University of the Arts), composer, conductor, editor of masterworks of the 18th century, and, as a founding member of the Bach Aria group, a seminal influence in the post-WWII revival of Baroque music in America. In The Robert Bloom Collection and the Art of Robert Bloom CD and video archives, we see what his musical ideals were in 1)18th-century performance practices, 2) writing new music for the instrument and commissioning new works, and 3) and transcribing music for the oboe and English horn. As an oboist, I believe it is important that Bloom's teachings, historical performance practices and ideas for expanding repertoire are propagated. Therefore, the works chosen for this dissertation illustrated this legacy. My recitals included 1) some of Bloom's published 18th-century baroque elaborations (his term for ornamentation), as well Baroque works which I have elaborated, 2) works written by him and by other oboists/composers (Labate, Roseman) as well as a flute/oboe duo that I commissioned by Dr. Marcus Maroney and 3) transcriptions by both Bloom and myself (Bach, Donizetti, Mendelssohn, Mozart, Handel, Schumann and Telemann). In these three dissertation recitals, I hope to have illustrated some of Robert Bloom's lasting contributions and impact on the oboe world, and to have demonstrated the potential for carrying forward this legacy by studying his teaching and emulating his example.

Consistent couplings between fields with a gauge freedom and deformations of the master equation

The antibracket in the antifield-BRST formalism is known to define a map Hp × Hq → Hp + q + 1 associating with two equivalence classes of BRST invariant observables of respective ghost number p and q an equivalence class of BRST invariant observables of ghost number p + q + 1. It is shown that this map is trivial in the space of all functionals, i.e. that its image contains only the zeroth class. However, it is generically non-trivial in the space of local functionals. Implications of this result for the problem of consistent interactions among fields with a gauge freedom are then drawn. It is shown that the obstructions to constructing non-trivial such interactions lie precisely in the image of the antibracket map and are accordingly non-existent if one does not insist on locality. However consistent local interactions are severely constrained. The example of the Chern-Simons theory is considered. It is proved that the only consistent, local, Lorentz covariant interactions for the abelian models are exhausted by the non-abelian Chern-Simons extensions. © 1993.

Experimental Investigation into the Free-Air Cooling of Air-Cooled Cylinders

This paper describes an experimental investigation into the surface heat transfer coefficient of finned metal cylinders in a free air stream. Eight cast aluminium alloy cylinders were tested with four different fin pitches and five different fin lengths. The cylinders and their fins were designed to be representative of those found on a motorcycle engine. Each electrically heated cylinder was mounted in a wind tunnel and subjected to a range of air speeds between 2 and 20 m/s. The surface heat transfer coefficient, h, was found primarily to be a function of the air speed and the fin separation, with fin length having a lesser effect. The coefficient increases with airspeed and as the fins are separated or shortened. It was also noted that a limiting value of coefficient exists, influenced only by airspeed. Above the limiting value the surface heat transfer could not be increased by further separation of the fins or reduction in their length.