1,460 research outputs found

    NASREN: Standard reference model for telerobot control

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    A hierarchical architecture is described which supports space station telerobots in a variety of modes. The system is divided into three hierarchies: task decomposition, world model, and sensory processing. Goals at each level of the task dedomposition heirarchy are divided both spatially and temporally into simpler commands for the next lower level. This decomposition is repreated until, at the lowest level, the drive signals to the robot actuators are generated. To accomplish its goals, task decomposition modules must often use information stored it the world model. The purpose of the sensory system is to update the world model as rapidly as possible to keep the model in registration with the physical world. The architecture of the entire control system hierarch is described and how it can be applied to space telerobot applications

    Hierarchical control of intelligent machines applied to space station telerobots

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    A hierarchical architecture is described which supports space station telerobots in a variety of modes. The system is divided into three hierarchies: task decomposition, world model, and sensory processing. Goals at each level of the task decomposition hierarchy are divided both spatially and temporally into simpler commands for the next lower level. This decomposition is repeated until, at the lowest level, the drive signals to the robot actuators are generated. To accomplish its goals, task decomposition modules must often use information stored in the world model. The purpose of the sensory system is to update the world model as rapidly as possible to keep the model in registration with the physical world. The architecture of the entire control system hierarchy and how it can be applied to space telerobot applications are discussed

    Power spectral measurements of clear-air turbulence to long wavelengths for altitudes up to 14,000 meters

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    Measurements of three components of clear air atmospheric turbulence were made with an airplane incorporating a special instrumentation system to provide accurate data resolution to wavelengths of approximately 12,500 m (40,000 ft). Flight samplings covered an altitude range from approximately 500 to 14,000 m (1500 to 46,000 ft) in various meteorological conditions. Individual autocorrelation functions and power spectra for the three turbulence components from 43 data runs taken primarily from mountain wave and jet stream encounters are presented. The flight location (Eastern or Western United States), date, time, run length, intensity level (standard deviation), and values of statistical degrees of freedom for each run are provided in tabular form. The data presented should provide adequate information for detailed meteorological correlations. Some time histories which contain predominant low frequency wave motion are also presented

    Structured Parallel Architecture for Displacement MIMO Kalman Equalizer in CDMA Systems

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    A reduced complexity MIMO Kalman equalizer architecture is proposed in this brief by jointly considering the displacement structure and the block-Toeplitz structure. Numerical matrix–matrix multiplications with O(F3) complexity are eliminated by simple data loading process, where is the spreading factor. Finally, an iterative Conjugate-Gradient based algorithm is proposed to avoid the inverse of the Hermitian symmetric innovation covariance matrix in Kalman gain processor. The proposed architecture not only reduces the numerical complexity from O(F2) to O(Flog2F) per chip, but also facilitates the parallel and pipelined VLSI implementation in real-time processing

    Rapid Industrial Prototyping and SoC Design of 3G/4G Wireless Systems Using an HLS Methodology

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    Many very-high-complexity signal processing algorithms are required in future wireless systems, giving tremendous challenges to real-time implementations. In this paper, we present our industrial rapid prototyping experiences on 3G/4G wireless systems using advanced signal processing algorithms in MIMO-CDMA and MIMO-OFDM systems. Core system design issues are studied and advanced receiver algorithms suitable for implementation are proposed for synchronization, MIMO equalization, and detection. We then present VLSI-oriented complexity reduction schemes and demonstrate how to interact these high-complexity algorithms with an HLS-based methodology for extensive design space exploration. This is achieved by abstracting the main effort from hardware iterations to the algorithmic C/C++ fixed-point design. We also analyze the advantages and limitations of the methodology. Our industrial design experience demonstrates that it is possible to enable an extensive architectural analysis in a short-time frame using HLS methodology, which significantly shortens the time to market for wireless systems.National Science Foundatio

    Nollywood and its Others: Questioning English Language Hegemony in Nollywood Studies

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    The current trend in Nollywood Studies is to focus on the way video films are being made and consumed around the world, a focus that parallels the name “Nollywood,” which, as Jonathan Haynes and Alessandro Jedlowski point out, references the film industries of Hollywood and Bollywood (Haynes, “Nollywood” 106; Jedlowski, “Videos” 11). While such studies are important in understanding the global impact of Nigeria’s film industry, a focus on migration, diaspora, and transnationalism of largely English-language films often overshadows those being made in Nigerian languages. Ironically, according to 2011 National Film and Video Censor’s Board statistics, Nigerian-language films are currently about 75% of the productions being made in Nigeria (Bala, “2011” 18). While research is being done on Nigerian-language films, the theorizing about Nollywood most found often at international conferences and in international publications is most often of English-language productions. This is problematic for several reasons: 1) It ignores the majority of the films being made and consumed in Nigeria, as well as the local discourses surrounding them; 2) It overlooks the full history of the video film in Nigeria, as well as nuances and variations in the style and culture of Nigerian-language film industries; 3) It risks missing the way that Nigerian-language films are also crossing borders and appealing to transnational audiences. Such oversight creates gaping holes in the research used to theorize the video phenomenon in Nigeria. The first part of my article examines English-language hegemony in representations of Nollywood, and the second part demonstrates why the study of Nigerian-language films is important in theorizing Nollywood. While I touch on multiple Nigerian-language industries, the bulk of my examples and analysis come from the Hausa language industry which I have been studying since 2005

    LOFT-1 Mission: New Concepts For Educational and Commercial Spaceflight

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    The Launch Operations Flight Test One (LOFT-1) was originally conceived by E\u27Prime Aerospace Corporation (EPAC) of Titusville, Florida, as strictly an administrative pathfinder toward satisfying all governmental requirements for conducting commercial spaceflight activities from the Cape Canaveral Air Force Station (CCAFS). As the program progressed from early June 1987 toward the original launch date set in the Fall, the complexion of the flight changed dramatically to one of a bonafide scientific mission. Four individual educational/commercial organizations agreed to provide experiments. As such, LOFT-1 would mark the first launch of a privately developed and funded suborbital vehicle carrying payloads from the CCAFS. The University of Alabama in Huntsville, by way of participants within the Industrial and Systems Engineering Department, volunteered to serve as a focal point for all LOFT-1 payload design and integration tasks. In addition, UAH went on to design and develop its own experiment. Given only a few short months between conception of the mission and the originally planned flight date of October 1^, 1987, it was necessary to define a close-knit team, literally from across the nation, to make the mission possible within the original time constraint

    Molecular and mass spectroscopic analysis of isotopically labeled organic residues

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    Experimental studies aimed at understanding the evolution of complex organic molecules on interstellar grains were performed. The photolysis of frozen gas mixtures of various compositions containing H2O, CO, NH3, and CH4 was studied. These species were chosen because of their astrophysical importance as deducted from observational as well as theoretical studies of ice mantles on interstellar grains. These ultraviolet photolyzed ices were warmed up in order to produce refractory organic molecules like the ones formed in molecular clouds when the icy mantles are being irradiated and warmed up either by a nearby stellar source or impulsive heating. The laboratory studies give estimates of the efficiency of production of such organic material under interstellar conditions. It is shown that the gradual carbonization of organic mantles in the diffuse cloud phase leads to higher and higher visual absorptivity - yellow residues become brown in the laboratory. The obtained results can be applied to explaining the organic components of comets and their relevance to the origin of life

    Editorial foreword: Angiogenesis: Cells, tissues and organs

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    On the occasion of his 90th birthday, this Special Issue is dedicated to Professor Robert Auerbach. Born 1929 in Berlin, Germany, he and his family escaped Nazi Germany in 1939 and emigrated to the United States, where he became a zoologist and ultimately Professor and Director of the Developmental Biology Training Program at the Department of Zoology, Madison, University of Wisconsin, USA. In Auerbach's laboratory, students and scientists of many different nations, including politically persecuted ones, harmoniously worked together on different aspects of angiogenesis. One of the hallmarks of Auerbach's career as a scientist was and is his generosity towards others, sharing his equipment and ideas freely, his integrity and his collegiality. His significant contributions to angiogenesis and tumour research include the finding that angiogenesis in tumours can occur even after their irradiation (Auerbach, Arensman, Kubai, & Folkman, 1975) and an explanation of organ selectivity in the spread of metastasizing cancer cells (Auerbach, 1988). Through his outstanding papers on in vitro methods in angiogenesis research, he also supported animal welfare (Alby & Auerbach, 1984; Auerbach, Lewis, Shinners, Kubai, & Akhtar, 2003; Gumkowski, Kaminska, Kaminski, Morrissey, & Auerbach, 1987; Obeso, Weber, & Auerbach, 1990)
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