7,668 research outputs found

    High speed lookup table approach to radiometric calibration of multispectral image data

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    A concept for performing radiometric correction of multispectral image data onboard a spacecraft at very high data rates is presented and demonstrated. This concept utilized a lookup table approach, implemented in hardware, to convert the raw sensor data into the desired corrected output data. The digital lookup table memory was interfaced to a microprocessor to allow the data correction function to be completely programmable. Sensor data was processed with this approach at rates equal to the access time of the lookup table memory. This concept offers flexible high speed data processing for a wide range of applications and will benefit from the continuing improvements in performance of digital memories

    Energy, Shading and Daylighting Analysis for the Austin Bergstrom International Airport Terminal

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    Our firm was under contract with the City of Austin, Texas to perform energy analysis and analysis of the daylighting potential within the New Austin Bergstrom International Airport Terminal. Design of the Passenger Terminal Facility for the New Austin Airport included large glass areas for viewing arriving and departing planes, the sky, and the surrounding terrain. The glass was envisioned to provide quality natural lighting for the terminal during daylight hours in order to improve the quality of the space and save energy throughout the usable life of the terminal. For the glass to achieve the design goals, adverse qualities were minimized and beneficial qualities must be enhanced. Using computer simulation, we studied the shading devices on the south clearstories to maximize the daylight and minimize problems of direct gain in a large commercial space. The study also included analysis of skylights above the baggage claim, indirect lighting of major spaces within the airport, and the controls of the artificial lights for integrating the efficient use of the available daylight. The energy, shading, and daylighting analysis includes analysis of a mix of low and high volume spaces. The daylight sources include glass walls, clearstories, and skylights

    A Combination Theorem for Metric Bundles

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    We define metric bundles/metric graph bundles which provide a purely topological/coarse-geometric generalization of the notion of trees of metric spaces a la Bestvina-Feighn in the special case that the inclusions of the edge spaces into the vertex spaces are uniform coarsely surjective quasi-isometries. We prove the existence of quasi-isometric sections in this generality. Then we prove a combination theorem for metric (graph) bundles (including exact sequences of groups) that establishes sufficient conditions, particularly flaring, under which the metric bundles are hyperbolic. We use this to give examples of surface bundles over hyperbolic disks, whose universal cover is Gromov-hyperbolic. We also show that in typical situations, flaring is also a necessary condition.Comment: v3: Major revision: 56 pages 5 figures. Many details added. Characterization of convex cocompact subgroups of mapping class groups of surfaces with punctures in terms of relative hyperbolicity given v4: Final version incorporating referee comments: 63 pages 5 figures. To appear in Geom. Funct. Ana

    Introduction of Mechatronics Specialization through Concentration Areas in the Mechanical and Electrical Engineering Technology Programs

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    The last few decades have experienced an explosion of technology, both in industry and in customer products. A large variety of embedded systems from various areas of applications, digital electronics, internet of things, automatically controlled products, and ultimately mechatronics systems are part of the everyday life. The changes in the industries, consumer markets and implicitly in the job markets, impose changes in the academic programs and curricula. Recently, mechatronics undergraduate programs started being developed in 2 or 4 years colleges across the nation, mainly driven by international companies operating in countries that already offer mechatronics degrees ranging from high school to doctoral programs. Most of the time there are independent mechatronics programs, mainly at the community college level, but mechatronics areas of specialization were also developed under either electrical or mechanical engineering programs, through senior elective courses. In the College of Engineering and Technology at Old Dominion University there are currently well established, accredited electrical and mechanical engineering technology programs, and steps are being taken to introduce the option for mechatronics specialization. A mechatronics concentration area was already introduced under the mechanical engineering technology (MET) program with new courses developed to provide skills in mechatronics, hydraulics, and simulation of mechatronics systems, complementing the existing courses focusing on automation, industrial robotics, computer integrated manufacturing, and computer numerical control. The electrical engineering technology (EET) program, with a current curriculum that includes a large number of courses to provide the foundation for mechatronics, is taking its turn in the development of a mechatronics concentration area. This paper discusses the introduction of mechatronics specialization through concertation areas in the mechanical and electrical engineering technology programs at Old Dominion University, with emphasis on the implementation challenges. This specialization model offers students the choice to incline the balance between the electrical and mechanical components of their mechatronics education through their major and minor selection, and in consonance with their individual strengths and preferences

    Adrenal myelolipoma: Operative indications and outcomes

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    Background: Adrenal myelolipoma (AM) is a benign lesion for which adrenalectomy is infrequently indicated. We investigated operative indications and outcomes for AM in a large single-institution series. Subjects and Methods: A retrospective cohort study of prospectively collected data was conducted. Patients (≥16 years of age) who underwent adrenalectomy in the Division of General Surgery at Barnes-Jewish Hospital (1993–2010) were grouped by operative indication (myelolipoma versus other pathology) and compared using nonparametric tests (α<0.05). Results: Sixteen patients (4.0%) had myelolipomas resected out of 402 patients who underwent adrenalectomy. Fourteen patients with suspected AM underwent adrenalectomy, 13 (93%) of whom had AM confirmed on pathology. Indications for adrenalectomy were abdominal or flank pain, large tumor size (>8 cm), atypical radiologic appearance, and/or inferior vena cava compression. Three patients with suspected other adrenal lesions had AM confirmed on final pathology. Operative approach was laparoscopic in 15 cases and open in 1 case of a 21-cm lesion. Patients who underwent laparoscopic adrenalectomy for AM (n=15) or other adrenal pathology (n=343) were similar with respect to age, gender, American Society of Anesthesiologists classification, prior abdominal operation, tumor side, operative time, conversion rate, estimated blood loss, intraoperative complications, hospital length of stay, and 30-day morbidity. However, patients with resected AM had a higher body mass index (36.5±8.1 kg/m(2) versus 30.1±7.5 kg/m(2); P<.01) and a larger preoperative tumor size (8.4±3.0 cm versus 3.1±1.7 cm; P<.01). Conclusions: Laparoscopic adrenalectomy may be appropriate for patients with a presumptive diagnosis of AM and abdominal or flank pain, large tumor size, and/or uncertain diagnosis after imaging. Outcomes and morbidity following LA for AM and other adrenal pathology appear comparable

    Energy, Shading and Daylighting Analysis for the Austin Bergstrom International Airport Terminal

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    Our firm was under contract with the City of Austin, Texas to perform energy analysis and analysis of the daylighting potential within the New Austin Bergstrom International Airport Terminal. Design of the Passenger Terminal Facility for the New Austin Airport included large glass areas for viewing arriving and departing planes, the sky, and the surrounding terrain. The glass was envisioned to provide quality natural lighting for the terminal during daylight hours in order to improve the quality of the space and save energy throughout the usable life of the terminal. For the glass to achieve the design goals, adverse qualities were minimized and beneficial qualities must be enhanced. Using computer simulation, we studied the shading devices on the south clearstories to maximize the daylight and minimize problems of direct gain in a large commercial space. The study also included analysis of skylights above the baggage claim, indirect lighting of major spaces within the airport, and the controls of the artificial lights for integrating the efficient use of the available daylight. The energy, shading, and daylighting analysis includes analysis of a mix of low and high volume spaces. The daylight sources include glass walls, clearstories, and skylights

    Divergent modulation of nociception by glutamatergic and GABAergic neuronal subpopulations in the periaqueductal gray

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    The ventrolateral periaqueductal gray (vlPAG) constitutes a major descending pain modulatory system and is a crucial site for opioid-induced analgesia. A number of previous studies have demonstrated that glutamate and GABA play critical opposing roles in nociceptive processing in the vlPAG. It has been suggested that glutamatergic neurotransmission exerts antinociceptive effects, whereas GABAergic neurotransmission exert pronociceptive effects on pain transmission, through descending pathways. The inability to exclusively manipulate subpopulations of neurons in the PAG has prevented direct testing of this hypothesis. Here, we demonstrate the different contributions of genetically defined glutamatergic and GABAergic vlPAG neurons in nociceptive processing by employing cell type-specific chemogenetic approaches in mice. Global chemogenetic manipulation of vlPAG neuronal activity suggests that vlPAG neural circuits exert tonic suppression of nociception, consistent with previous pharmacological and electrophysiological studies. However, selective modulation of GABAergic or glutamatergic neurons demonstrates an inverse regulation of nociceptive behaviors by these cell populations. Selective chemogenetic activation of glutamatergic neurons, or inhibition of GABAergic neurons, in vlPAG suppresses nociception. In contrast, inhibition of glutamatergic neurons, or activation of GABAergic neurons, in vlPAG facilitates nociception. Our findings provide direct experimental support for a model in which excitatory and inhibitory neurons in the PAG bidirectionally modulate nociception
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