3,224 research outputs found
Turnstile slot antenna
A turnstile slot antenna is disclosed, the antenna being for and integral with a spacecraft having a substantially cylindrical body portion. The antenna comprises a circumferential slot about the periphery of the spacecraft body portion with an annular wave guide cavity defining a radial transmission line disposed within the spacecraft body portion behind and in communication with the circumferential slot. Feed stubs and associated transmission apparatus are provided to excite the annular cavity in quadrature phase such that an omnidirectional, circularly polarized, rotating radiation pattern is generated. The antenna of the instant invention has utility both as a transmitting and receiving device, and ensures continuous telemetry and command coverage with the spacecraft
An atlas of 1975 GEOS-3 radar altimeter data for hurricane/tropical disturbance studies, volume 1
Geographic locations of 1975 hurricanes and other tropical disturbances were correlated with the closest approaching orbits of the GEOS-3 satellite and its radar altimeter. The disturbance locations and altimeter data were gathered for a seven-month period beginning with GEOS-3 launch in mid-April 1975. Areas of coverage were the Atlantic Ocean, the Carribean, the Gulf of Mexico, the west coast of the continental United States, and the central and western Pacific Ocean. Volume 1 contains disturbance coverage data for the Atlantic Ocean, Gulf of Mexico, and Eastern Pacific Ocean. Central and Western Pacific coverage is documented in Volume II
Investigation of Kevlar fabric based materials for use with inflatable structures
Design, manufacture and testing of laminated and coated composite materials incorporating a structural matrix of Kevlar are reported in detail. The practicality of using Kevlar in aerostat materials is demonstrated and data are provided on practical weaves, lamination and coating particulars, rigidity, strength, weight, elastic coefficients, abrasion resistance, crease effects, peel strength, blocking tendencies, helium permeability, and fabrication techniques. Properties of the Kevlar based materials are compared with conventional, Dacron reinforced counterparts. A comprehensive test and qualification program is discussed and quantitative biaxial tensile and shear test data are provided. The investigation shows that single ply laminates of Kevlar and plastic films offer significant strength to weight improvements, are less permeable than two ply coated materials, but have a lower flex life
Electronic to Vibrational Energy Transfer from Cl\u3csup\u3e*\u3c/sup\u3e (\u3csup\u3e2\u3c/sup\u3eP\u3csub\u3e1/2\u3c/sub\u3e) to CH\u3csub\u3e4\u3c/sub\u3e and CD\u3csub\u3e4\u3c/sub\u3e
Electronic-to-vibrational (E-V) energy transfer is a significant kinetic channel in the collisional quenching of spin-orbit excited chlorine atoms, Cl* (2P1/2, 882 cm-1), by molecular collision partners. In the present study Cl* atoms are prepared in the presence of CH4 or CD4, under pseudo first-order conditions, by photolysis of ICl at 532 nm with a pulsed Nd:YAG laser. Quenching of Cl* by CH4 or CD4 results in E-V excitation of the ν4 asymmetric bending mode as observed by infrared (IR) fluorescence from the vibrationally excited products. Time-resolved IR fluorescence observations of CH4(ν4) and CD4(ν4) are consistent with a simple kinetic scheme involving direct E-V excitation of CH4(ν4) or CD4(ν4) followed by a slower collisional relaxation. The total quenching rate of Cl* is reflected in the rise of the ν4 fluorescence signal. The Cl* total bimolecular quenching rate coefficients (± 2σ) obtained in this study at 298 ± 2 K are (1.9 ± 0.5) x 10-11 cm3 molecule-1 s-1 for quenching by CH4 and (1.4 ± 0.9) x 10-10 cm3 molecule-1 s-1 for CD4. Intensity measurements interpreted within this kinetic scheme indicate that the E-V channel for ν4 mode excitation accounts for ≈30% of the total quenching of Cl* by CH4 and CD4. It is remarkable that the E-V branching ratios are the same in both systems even though the ν4 -- -Cl* energy differences span a four-fold range from approximately ½kT (CD4) to 2kT (CH4)
Investigation of Kevlar fabric-based materials for use with inflatable structures
Design, manufacture and testing of laminated and coated composite materials incorporating a structural matrix of Kevlar are reported. The practicality of using Kevlar in aerostat materials is demonstrated, and data are provided on practical weaves, lamination and coating particulars, rigidity, strength, weight, elastic coefficients, abrasion resistance, crease effects, peel strength, blocking tendencies, helium permeability, and fabrication techniques. Properties of the Kevlar-based materials are compared with conventional Dacron-reinforced counterparts. A comprehensive test and qualification program is discussed, and considerable quantitative biaxial tensile and shear test data are provided
First Experiences Integrating PC Distributed I/O Into Argonne's ATLAS Control System
First Experiences Integrating PC Distributed I/O Into Argonne's ATLAS Control
System The roots of ATLAS (Argonne Tandem-Linac Accelerator System) date back
to the early 1960s. Located at the Argonne National Laboratory, the accelerator
has been designated a National User Facility, which focuses primarily on
heavy-ion nuclear physics. Like the accelerator it services, the control system
has been in a constant state of evolution. The present real-time portion of the
control system is based on the commercial product Vsystem [1]. While Vsystem
has always been capable of distributed I/O processing, the latest offering of
this product provides for the use of relatively inexpensive PC hardware and
software. This paper reviews the status of the ATLAS control system, and
describes first experiences with PC distributed I/O.Comment: ICALEPCS 2001 Conference, PSN WEAP027, 3 pages, 1 figur
COMET: A Recipe for Learning and Using Large Ensembles on Massive Data
COMET is a single-pass MapReduce algorithm for learning on large-scale data.
It builds multiple random forest ensembles on distributed blocks of data and
merges them into a mega-ensemble. This approach is appropriate when learning
from massive-scale data that is too large to fit on a single machine. To get
the best accuracy, IVoting should be used instead of bagging to generate the
training subset for each decision tree in the random forest. Experiments with
two large datasets (5GB and 50GB compressed) show that COMET compares favorably
(in both accuracy and training time) to learning on a subsample of data using a
serial algorithm. Finally, we propose a new Gaussian approach for lazy ensemble
evaluation which dynamically decides how many ensemble members to evaluate per
data point; this can reduce evaluation cost by 100X or more
Pancreatic Cancer Signature Center: Providing the Research Tools Necessary to Advance Pancreatic Cancer Patient Care
There were approximately 45,000 new cases of pancreatic ductal adenocarcinoma (PDAC) in the U.S. in 2013, and approximately 38,500 deaths. PDAC thus constitutes the fourth leading cause of cancer deaths in adults, and PDAC patients have a dismal 5-year survival rate of 6%. Moreover, approximately 75% of patients die within the first year after diagnosis. PDAC is notoriously resistant to chemotherapy and radiation and even with our best treatment options, a complete margin-negative surgical resection, few patients achieve long-term survival. Despite these statistics, surprisingly only a small number of NCI-designated cancer centers have a specialized pancreatic cancer program. The creation of the IUPUI Signature Center for Pancreatic Cancer Research has been the foundation for putting IUPUI, the IU School of Medicine, Purdue University and the IU Simon Cancer Center at the forefront of pancreatic cancer treatment and research across the nation. The Signature Center, comprised of basic, translational and clinical researchers, represents the continuum of the disease from biological / molecular investigation to clinical trials. Funding from the Signature Center Initiative is being utilized to develop genetically engineered mouse models, generate orthotopic pancreatic cancer mouse models, develop cancer associated fibroblast lines to be used as a shared resource as well as provide funding for peer reviewed pilot projects led by young investigators. Establishment and characterization of these cell lines and in vivo models provides the groundwork for these resources to be used by all members in their translational research projects. Support of pilot projects provides preliminary data and identification of projects to be ultimately used in a SPORE application. Additionally, work has begun on a web portal to promote and educate both patients and clinicians about the IUSCC Pancreas Cancer Clinic which became operational in 2010. Taken together, these activities provide the infrastructure to support pancreas cancer research at IU across the continuum of bench to bedside to practice. The availability of these resources to all members promotes inter-disciplinary collaborations aimed at increasing our understanding of pancreatic cancer so that advancements can be made in early diagnosis, prevention and multi-modality targeted treatment of this malignancy
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