9,950 research outputs found

    Signal and Image Manipulation in Microanalysis

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    Scanning electron microscopes, and transmission instruments equipped for EELS, generate a host of signals and hence of images from each pixel of the specimen. Numerous ingenious ways of coping with this multiplicity of information, which may be very different in character, have been devised, but no detailed study has yet been made of the appropriate mathematical structure, with the aid of which all this information could be manipulated reasonably easily. One such structure falls within the subject that has come to be known as Image Algebra, the principal attraction of which is that we deal directly with entire images and not with individual pixels; the operations involved do of course ultimately take effect at pixel level. Despite its forbidding name, image algebra is intrinsically very simple and has the merit that the notion of image is very general. Images can in particular be multi-valued, that is, a set of values can be associated with every pixel. Indeed, a whole image is associated with each pixel, in the case of the very important class of images known as templates. Image algebra has proved to be an extremely fertile subject, generating many new ideas and especially, revealing several unsuspected relationships between different branches of image and signal processing. The value of this approach will be examined, after a very simple introduction to the basic ideas. The application to image-spectra will be considered as a tangible example. We conclude with some speculations concerning the future of this rich new way of picturing images

    Image Algebra and Restoration

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    The arrival of image algebras has made it possible to express a vast amount of the heterogeneous material in the image processing literature in a convenient and consistent manner. Furthermore, this type of formulation has proved very fertile and many new ideas have emerged. Image restoration has, however, been studied very much less than enhancement and analysis. We explain briefly the use of one such algebra in this field and show that such tasks as reconstruction from focal series and three-dimensional reconstruction can easily be incorporated

    Our Lady of Victories

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    This article describes the process and competition for the design of the Portland Soldiers and Sailors Monument

    Hydrogen and fuel cell technologies for heating: A review

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    The debate on low-carbon heat in Europe has become focused on a narrow range of technological options and has largely neglected hydrogen and fuel cell technologies, despite these receiving strong support towards commercialisation in Asia. This review examines the potential benefits of these technologies across different markets, particularly the current state of development and performance of fuel cell micro-CHP. Fuel cells offer some important benefits over other low-carbon heating technologies, and steady cost reductions through innovation are bringing fuel cells close to commercialisation in several countries. Moreover, fuel cells offer wider energy system benefits for high-latitude countries with peak electricity demands in winter. Hydrogen is a zero-carbon alternative to natural gas, which could be particularly valuable for those countries with extensive natural gas distribution networks, but many national energy system models examine neither hydrogen nor fuel cells for heating. There is a need to include hydrogen and fuel cell heating technologies in future scenario analyses, and for policymakers to take into account the full value of the potential contribution of hydrogen and fuel cells to low-carbon energy systems

    Communications platform payload definition study, executive summary

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    Large geostationary communications platforms have been investigated in a number of studies since 1974 as a possible means to more effectively utilize the geostationary orbital arc and electromagnetic spectrum and to reduce overall satellite communications system costs. This NASA Lewis sponsored study addresses the commercial feasibility of various communications platform payload concepts circa 1998. It defines promising payload concepts, estimates recurring costs and identifies critical technologies needed to permit eventual commercialization. Ten communications service aggregation scenarios describing potential groupings of services were developed for a range of conditions. Payload concepts were defined for four of these scenarios: (1) Land Mobile Satellite Service (LMSS), meet 100% of CONUS plus Canada demand with a single platform; (2) Fixed Satellite Service (FSS) (Trunking + Customer Premises Service (CPS), meet 20% of CONUS demands; (3) FSS (Trunking + video distribution), 10 to 13% of CONUS demand; and (4) FSS (20% of demand) + Inter Satellite Links (ISL) + TDRSS/TDAS Data Distribution

    Passively Adaptive Radiative Switch for Thermoregulation in Buildings

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    With the ever-growing need to reduce energy consumption, building materials that passively heat or cool are gaining importance. However, many buildings require both heating and cooling, even within the same day. To date, few technologies can automatically switch between passive heating and cooling, and those that can require a large temperature range to cycle states (>15o C), making them ineffective for daily switching. We present a passively adaptive radiative switch that leverages the expansion in phase-change energy storage materials to actuate the motion of louvers and can cycle states in less than 3o C. The black selective-absorber louvers induce high heat gain when closed, yet when open, expose a white, emissive surface for low heat gain. During an outdoor test in which temperature was held steady, our device reduced the energetic cost of cooling by 3.1x and heating by 2.6x compared to non-switching devices. Our concept opens the door for passively adaptive thermoregulating building materials.Comment: 32 pages with supplementary information include

    On nearness measures in fuzzy relational data models

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    AbstractIt has been widely recognized that the imprecision and incompleteness inherent in real-world data suggest a fuzzy extension for information management systems. Various attempts to enhance these systems by fuzzy extensions can be found in the literature. Varying approaches concerning the fuzzification of the concept of a relation are possible, two of which are referred to in this article as the generalized fuzzy approach and the fuzzy-set relation approach. In these enhanced models, items can no longer be retrieved by merely using equality-check operations between constants; instead, operations based on some kind of nearness measures have to be developed. In fact, these models require such a nearness measure to be established for each domain for the evaluation of queries made upon them. An investigation of proposed nearness measures, often fuzzy equivalences, is conducted. The unnaturalness and impracticality of these measures leads to the development of a new measure: the resemblance relation, which is defined to be a fuzzified version of a tolerance relation. Various aspects of this relation are analyzed and discussed. It is also shown how the resemblance relation can be used to reduce redundancy in fuzzy relational database systems
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