7,668 research outputs found
High speed lookup table approach to radiometric calibration of multispectral image data
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
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
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
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
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
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
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
- …