Rough surface backscatter and statistics via extended parabolic integral equation

This paper extends the parabolic integral equation method, which is very effective for forward scattering from rough surfaces, to include backscatter. This is done by applying left-right splitting to a modified two-way governing integral operator, to express the solution as a series of Volterra operators; this series describes successively higher-order surface interactions between forward and backward going components, and allows highly efficient numerical evaluation. This and equivalent methods such as ordered multiple interactions have been developed for the full Helmholtz integral equations, but not previously applied to the parabolic Green's function. In addition, the form of this Green's function allows the mean field and autocorrelation to be found analytically to second order in surface height. These may be regarded as backscatter corrections to the standard parabolic integral equation method

Efficient boundary integral solution for acoustic wave scattering by irregular surfaces

The left-right operator splitting method is studied for the efficient calculation of acoustic fields scattered by arbitrary rough surfaces. Here the governing boundary integral is written as a sum of left- and right-going components, and the solution expressed as an iterative series, expanding about the predominant direction of propagation. Calculation of each term is computationally inexpensive both in time and memory, and the field is often accurately captured using one or two terms. The convergence and accuracy are examined by comparison with exact solution for smaller problems, and a series of much larger problems are tackled. The method is also immediately applicable to other scatterers such as waveguides, of which examples are given

Random scattering by rough surfaces with spatially varying impedance

A method is given for evaluating electromagnetic scattering by an irregular surface with spatially-varying impedance. This uses an operator expansion with respect to impedance variation and allows examination of its effects and the resulting modification of the field scattered by the rough surface. For a fixed rough surface and randomly varying impedance, expressions are derived for the scattered field itself, and for the coherent field with respect to impedance variation for both flat and rough surfaces in the form of effective impedance conditions

Visualisation and Grid applications of electromagnetic scattering from aircraft

Proceedings of the 2003 UK e-Science All Hands Meeting, 31st August - 3rd September, Nottingham UKElectromagnetic scattering behaviour plays a central role in the design of aircraft and other complex structures. This paper describes progress on visualisation tools in this area and on initial development of a web portal to enable scientists at remote locations to collaborate

Developing web services in a computational grid environment

Grid and Web services are both hot topics today. In this paper, we will present some ongoing work and planned future work at the Cambridge eScience Centre. After an introduction to these technologies in the context of Grid applications development, we describe two use-cases: a database of results in computational fluid dynamics (CFD) and a small computational Grid for aircraft engineering design. As Grid services are moving towards Web services, we continue to make use of the Globus Toolkit v2.4 (GT2.4), without adopting the Open Grid Services Architecture (OGSA) wholesale. In our scenario, GT2.4 integrates distributed computing resources including HPC and clusters while Web services wrap the scientific code as a service.Proceedings of the IEEE International Conference on Services Computing, Shanghai, September 200

Recovery of rough surface in ducting medium from grazing angle scattered wave

A method is developed for rough surface reconstruction using fields scattered at grazing angles in a medium with a linearly varying refractive index and Neumann boundary condition. This regime represents a ducting medium, bounded by a perfectly conducting surface with a TM incident field or an acoustically hard surface. This significantly extends the iterated marching method, based upon the parabolic integral equation for forward-scattered field components [Chen and Spivack, J. Opt. Soc. Am. A 35, 504–513 (2018)]. The approach, which uses a fixed frequency, is able to accurately recover multiscale surfaces and is found to be robust with respect to measurement noise and localized perturbations.</jats:p

From Hillary Clinton to Lady Macbeth: Or, Historicizing Gender, Law, and Power Through Shakespeare\u27s Scottish Play

Female rule was anomalous in the sixteenth century, therefore, Elizabeth I developed a complex set of symbols, rooted in claims traditionally made by male rulers, to legitimate her claim to rule. Nonetheless, her reign was anxiety-provoking, and this article argues that the years after her death saw a backlash against female power. Part of this backlash consisted of the reworking of the symbols Elizabeth had used. This article examines this process of revision in Shakespeare\u27s play Macbeth and, later, in the responses of King James I to claims of demonic possession. This article draws together three historical moments - Queen Elizabeth\u27s role in the trial of Mary, Queen of Scots; Shakespeare\u27s rewriting of the female ruler\u27s conscience in Lady Macbeth; and King James\u27s response to claims of demonic possession - to analyze a period when the female body was redefined in ways that continue to animate the law today. This connection to modern jurisprudence is especially prevalent in the areas of reproductive rights and fetal protection law. This article shows that the idea of the female body as merely biological and lacking in a subjectivity comparable to the male body originated in part in early seventeenth-century England

The Duchess\u27 Privy Chamber: Early Modern Marriage Law and the Eviction of Women from the Public Sphere in John Webster\u27s Duchess of Malfi

The Duchess’ Privy Chamber: Early Modern Marriage Law and the Eviction of Women from the Public Sphere in The Duchess of Malfi (argues that the symbolism in Webster’s Duchess of Malfi systemically undoes the iconography of Elizabethan power; that images taken from the legal descriptions of marriage work in the play to replace the image of woman as political ruler in the public sphere with woman as wife sequestered in the private sphere)