10 research outputs found

    Classification, identification, and modeling of unexploded ordnance in realistic environments

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 205-218).Recovery of buried unexploded ordnance (UXO) is very slow and expensive due to the high false alarm rate created by clutter. Electromagnetic induction (EMI) has been shown to be a promising technique for UXO detection and discrimination. This thesis uses the EMI response of buried targets to identify or classify them. To perform such discrimination, accurate forward models of buried UXO are needed. This thesis provides a survey of existing target models: the dipole model, the spheroid model, and the fundamental mode model. Then the implementation of a new model, the spheroidal mode model, is described and validated against measurements of a UXO. Furthermore, an in-depth study of the effects of permeable soil, modeled as a permeable half space, is presented. This study concludes that the discontinuity created by the air to permeable soil interface produces minimal effect in the response of a buried object. The change is limited to a magnitude shift of the real portion of the EMI response and can be reproduced by superposition of a permeable half space response on the response of the same object in frees pace. Accurate soil modeling also allows one to invert for soil permeability values from measured data if such data are in known units. However, the EMI sensor used in this study provides measurements in consistent but unknown units. Furthermore, the instrument is from a third party and is proprietary. Therefore, this thesis describes the development of a non-invasive method to model and calibrate non-adaptive instruments so that all measurements can be converted into units consistent with modeled data. This conversion factor is shown to be a constant value across various conditions, thus demonstrating its validity.(cont.) Given that now a more complete model of the measurable response of a buried UXO is implemented, this study proceeds to demonstrate that EMI responses from UXO and clutter objects can be used to identify the objects through the application of Differential Evolution (DE), a type of Genetic Algorithm. DE is used to optimize the parameters of the UXO fundamental mode model to produce a match between the modeled response and the measured response of an unknown object. When this optimization procedure is applied across a library of models for possible UXO, the correct identity of the unknown object can be ascertained because the corresponding library member will produce the closest match. Furthermore, responses from clutter objects are shown to produce very poor matches to library objects, thus providing a method to discriminate UXO from clutter. These optimization experiments are conducted on measurements of UXO in air, UXO in air but obscured by clutter fragments, buried UXO, and buried UXO obscured by clutter fragments. It is shown that the optimization procedure is successful for shallow buried objects obscured by light clutter contributing to roughly 20 dB SNR, but is limited in applicability towards very deeply buried UXO or those in dense clutter environments. The DE algorithm implemented in this study is parallelized and the optimization results are computed with a multi-processor supercomputer. Thus, the computational requirement of DE is a considerable drawback, and the method cannot be used for real time, on-site inversion of measured UXO data. To address this concern, a different approach to inversion is also implemented in this study. Rather than identifying particular UXO, one may do a discrimination between general UXO and general clutter items. Previous work has shown that the expansion coefficients of EMI responses in the spheroidal coordinate system can uniquely characterize the corresponding targets.(cont.) Therefore, these coefficients readily lend themselves for use as features by which objects can be classified as likely to be UXO or unlikely to be UXO. To do such classification, the relationship between these coefficients and the physical properties of UXO and clutter, such as differences in size or body-of-revolution properties or material heterogeneity properties, must be found. This thesis shows that such relationships are complex and require the use of the automated pattern recognition capability of machine learning. Two machine learning algorithms, Support Vector Machines and Neural Networks, are used to identify whether objects are likely to be UXO. Furthermore, the effects of small diffuse clutter fragments and uncertainty about the target position are investigated. This discrimination procedure is applied on both synthetic data from models and measurements of UXO and clutter. It is found that good discrimination is possible for up to 20 dB SNR. But the discrimination is sensitive to inaccurate estimations of a target's depth. It is found that the accuracy must be within a 10 cm deviation of an object's true depth. The general conclusion forwarded by this work is that while increasingly accurate discrimination capabilities can be produced through more detailed forward modeling and application of robust optimization and learning algorithms, the presence of noise and clutter is still of great concern. Minimization or filtering of such noise is necessary before field deployable discrimination techniques can be realized.by Beijia Zhang.Ph.D

    The art and architecture of mathematics education: a study in metaphors

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    This chapter presents the summary of a talk given at the Eighth European Summer University, held in Oslo in 2018. It attempts to show how art, literature, and history, can paint images of mathematics that are not only useful but relevant to learners as they can support their personal development as well as their appreciation of mathematics as a discipline. To achieve this goal, several metaphors about and of mathematics are explored

    Edmund Wilson\u27s America

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    When Edmund Wilson died in 1972 he was widely acclaimed as one of America\u27s great literary critics. But it was often forgotten by many of his admirers that he was also a brilliant and penetrating critic of American life. In a literary career spanning half a century, Wilson commented on nearly every aspect of the American experience, and he produced a body of work on the subject that rivals those of Tocqueville and Henry Adams. In this book, George H. Douglas has distilled the essence from Wilson\u27s many writings on America. An active reporter and journalist as much as a scholar, Wilson ranged from Harding to Nixon, from bathtub gin to marijuana. Douglas here surveys Wilson\u27s mordant observations on the roaring twenties, the Great Depression, income tax, suburbia, sex, populist politics, the Vietnam War, the Great Society, the failure of American scholarship, pollution of the landscape, and the breakdown of traditional American values. The Wilson who emerges from this survey is a historical writer with deep and unshakable roots in Jeffersonian democracy. Among his most far-seeing and poignant books are studies of the literature of the American Civil War and of the treatment of the American Indian. Pained by the crumbling moral order, Wilson was never completely at home in the twentieth century. In politics he was neither a liberal nor a conservative as those terms are understood today. He endured those ideologies and their adherents, but his genius was that he could bring them into hard focus from the perspective of the traditional American individualist who was too pained to accept the standardized commercial world that had grown up around him. Edmund Wilson\u27s America offers a distinctive overview of the nation\u27s life and culture as seen and judged by its leading man of letters. Professor of English at the University of Illinois, George H. Douglas has written on a variety of American authors and cultural matters, including a recent book on Chicago and the railroad.https://uknowledge.uky.edu/upk_english_language_and_literature_north_america/1052/thumbnail.jp

    Course Catalogue of the Massachusetts Institute of Technology 1953 - 1954

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    Massachusetts Institute of Technology Bulletin, Catalogue Issue 1953-1954. A Bulletin of general information about the Institute, Its government, staff, regulations, requirements for admission, facilities, and both undergraduate and graduate courses of instruction. Includes two appendices: student aid and prizes; student housing. Also includes several full page black and white photographs depicting various aspects of campus life, and campus map, Cambridge. Digitized from microfiche copies. Digital version may contain microfiche headers and targets

    Annual Review of Progress in Applied Computational Electromagnetics

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    Approved for public release; distribution is unlimited

    MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

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    Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described

    Generalized averaged Gaussian quadrature and applications

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    A simple numerical method for constructing the optimal generalized averaged Gaussian quadrature formulas will be presented. These formulas exist in many cases in which real positive GaussKronrod formulas do not exist, and can be used as an adequate alternative in order to estimate the error of a Gaussian rule. We also investigate the conditions under which the optimal averaged Gaussian quadrature formulas and their truncated variants are internal

    High Energy Physics

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