870 research outputs found

    Image retrieval based on swarm intelligence

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    To keep pace with the development of modern technology in this information technology era, and the immense image databases, whether personal or commercial, are increasing, is requiring the management of these databases to strong and accurate systems to retrieve images with high efficiency. Because of the swarm intelligence algorithms are great importance in solving difficult problems and obtaining the best solutions. Here in this research, a proposed system is designed to retrieve color images based on swarm intelligence algorithms. Where the algorithm of the ant colony optimization (ACOM) and the intelligent water drop (IWDM) was used to improve the system's work by conducting the clustering process in these two methods on the features extracted by annular color moment method (ACM) to obtain clustered data, the amount of similarity between them and the query image, is calculated to retrieve images from the database, efficiently and in a short time. In addition, improving the work of these two methods by hybridizing them with fuzzy method, fuzzy gath geva clustering algorithm (FGCA) and obtaining two new high efficiency hybrid algorithms fuzzy ant colony optimization method (FACOM) and fuzzy intelligent water drop method (FIWDM) by retrieving images whose performance values are calculated by calculating the values of precision, recall and the f-measure. It proved its efficiency by comparing it with fuzzy method, FGCA and by methods of swarm intelligence without hybridization, and its work was excellent

    Conceptual design for the Space Station Freedom fluid physics/dynamics facility

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    A study team at NASA's Lewis Research Center has been working on a definition study and conceptual design for a fluid physics and dynamics science facility that will be located in the Space Station Freedom's baseline U.S. Laboratory module. This modular, user-friendly facility, called the Fluid Physics/Dynamics Facility, will be available for use by industry, academic, and government research communities in the late 1990's. The Facility will support research experiments dealing with the study of fluid physics and dynamics phenomena. Because of the lack of gravity-induced convection, research into the mechanisms of fluids in the absence of gravity will help to provide a better understanding of the fundamentals of fluid processes. This document has been prepared as a final version of the handout for reviewers at the Fluid Physics/Dynamics Facility Assessment Workshop held at Lewis on January 24 and 25, 1990. It covers the background, current status, and future activities of the Lewis Project Study Team effort. It is a revised and updated version of a document entitled 'Status Report on the Conceptual Design for the Space Station Fluid Physics/Dynamics Facility', dated January 1990

    Look-a-like:a fast content-based image retrieval approach using a hierarchically nested dynamically evolving image clouds and recursive local data density

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    The need to find related images from big data streams is shared by many professionals, such as architects, engineers, designers, journalist, and ordinary people. Users need to quickly find the relevant images from data streams generated from a variety of domains. The challenges in image retrieval are widely recognised and the research aiming to address them led to the area of CBIR becoming a 'hot' area. In this paper, we propose a novel computationally efficient approach which provides a high visual quality result based on the use of local recursive density estimation (RDE) between a given query image of interest and data clouds/clusters which have hierarchical dynamically nested evolving structure. The proposed approach makes use of a combination of multiple features. The results on a data set of 65,000 images organised in two layers of an hierarchy demonstrate its computational efficiency. Moreover, the proposed Look-a-like approach is self-evolving and updating adding new images by crawling and from the queries made

    NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

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    Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977

    Generation and metrology of ultrashort pulses and their application in attosecond science

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    This thesis deals with the dynamical processes in atoms and small molecules initiated by the absorption of ultrashort, coherent light pulses. The studied phenomena takeplace on the femtosecond (1 fs = 10−15 s) and attosecond (1 as = 10−18 s) timescales and critically depend on the properties of the light fields that drive them. Wework with infrared (IR) femtosecond laser pulses, which we manipulate through nonlinear interactions with matter to either study these interactions themselves or applythem to investigate other light-induced processes.One part of this thesis focuses on the generation and characterisation of IR pulses spectrally broadened through the Kerr effect. We use a technique called dispersion scanto temporally compress and at the same time measure pulses broadened in gas-filled hollow-core fibres. We propose multiple improvements to this well-established characterisation technique. Further, we investigate femtosecond filamentation in gases, a process with highly complex dynamics involving several non-linear processes including the Kerr effect and ionisation. We develop a method that allows us to measure the electric field of a laser pulse undergoing filamentation in three dimensions, whilealso scanning along the filament length. Our technique provides access to pulses with desirable characteristics that may be generated at a point inside the filament, simultaneously enabling their measurement and extraction for applications. In addition, this technique opens up the possibility to explore intricate filament dynamics.In the other part of this work, we up-convert the IR laser pulses into trains of extreme ultraviolet (XUV) attosecond pulses through a non-linear process called high-orderharmonic generation. We combine the IR and XUV pulses to study the photoionisation dynamics in different species using a method known as RABBIT (Reconstructionof Attosecond Beating By Interference of Two-photon transitions). In this technique, a target gas is ionised by the XUV field, creating an electron wave-paket (EWP) in thecontinuum, while a weak IR pulse probes the system. The EWP scatters off the ionic potential, acquiring an additional phase as it propagates. Recording the photoelectronspectrum as a function of the IR-XUV time delay allows us to infer time-resolved information about the ionic potential. We apply this method to investigate the dynamicsof different ionisation processes in noble gases (He, Ar, and Xe) and the N2 molecule. The high spectral resolution of our electron spectrometer allows us to disentanglethe contributions from different ionisation channels. In addition, we perform angle-resolved measurements, investigating the coherent superposition of final stateswith different angular momenta

    Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4

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    Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

    NASA scientific and technical publications: A catalog of special publications, reference publications, conference publications, and technical papers, 1991-1992

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    This catalog lists 458 citations of all NASA Special Publications, NASA Reference Publications, NASA Conference Publications, and NASA Technical Papers that were entered into the NASA Scientific and Technical Information database during accession year 1991 through 1992. The entries are grouped by subject category. Indexes of subject terms, personal authors, and NASA report numbers are provided

    Programmable optics for ultrashort pulse management: devices and applications

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    The contribution of the present report to the field of ultrashort optics has several aspects: from the development of new optical devices for ultrashort pulse management, to the application of those devices for triggering laser-matter interaction processes. In this sense, the key point of this Thesis is the use of reconfigurable phase-only SLMs based on LCOS technology for spatial and temporal shaping of femtosecond pulses. The management of femtosecond pulses demands specific strategies to obtain the desired output response while preventing undesirable distortions. Our results show that programmable diffractive optics encoded in SLMs is a powerful tool for ultrashort (~30 fs) beam management. The reconfigurable nature of SLMs allows wavefront control of an input pulsed beam at a micro scale level. In this way, we have developed devices for transferring amplitude and/or phase maps onto the spatial and temporal profile of an ultrashort pulse. Moreover, our proposals result in very compact optical devices, allowing easy-to-align setups especially suitable for non-expert users. We believe that this fact may promote the use of ultrafast technology in many different scientific fields that demands user-friendly devices for ultrashort pulse control

    Aeronautical Engineering: A Continuing Bibliography with Indexes (supplement 194)

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    This bibliography lists 369 reports, articles and other documents introduced into the NASA scientific and technical information system in November 1985
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