265 research outputs found

    Collapse Resistance of Moment Resisting Frame and Shear Wall RC Structural Systems Exposed to Blast

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    Various characteristics of a structure influence its response when subjected to a blast load. This has important implications for survivability and resistance to progressive collapse. In this study, the effect of the type of lateral load resisting system on reinforced concrete building resistance to progressive collapse when exposed to blast load is examined. Fourteen different reinforced concrete structures were considered for analysis, with five structures designed as moment resisting frames and nine designed as shear walls systems. Buildings with 3, 6, and 10 stories with 3, 4, and 5-bay symmetric configurations were considered. The structures were exposed to external and internal charges, while the nonlinear, transient dynamic analysis of collapse behavior was investigated with a finite element based approach, the applied element method (AEM). The results show that the shear wall structures and structures larger in height and plan generally provide greatest resistance to blast damage and progressive collapse

    Booster Obsolescence and Life Extension (BOLE) for Space Launch System (SLS)

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    A human mission to the moon and Mars is the stated space exploration goal of the United States and the international community. To achieve these goals, NASA is developing the Space Launch System (SLS) and the Orion crew capsule as key elements in the architecture for missions to the moon and Mars. As part of the SLS Booster Obsolescence and Life Extension (BOLE) program, Northrop Grumman Space Systems is working to address booster obsolescence issues in design and manufacturing. The upgraded boosters will also provide increased performance that will benefit future lunar campaigns, science missions, and the eventual Mars campaign

    Elementary School Experience with Comprehension Testing May Influence Metacomprehension Accuracy Among Seventh and Eighth Graders

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    We explored whether exposure to different kinds of comprehension tests during elementary years influenced metacomprehension accuracy among 7th and 8th graders. This research was conducted in a kindergarten through eighth grade charter school with an expeditionary learning curriculum. In literacy instruction, teachers emphasize reading for meaning and inference building, and they regularly assess deep comprehension with summarization, discussion, dialogic reasoning and prediction activities throughout the elementary years. The school recently expanded, doubling enrollments in 7th and 8th grades. Thus, approximately half of the students had long-term exposure to the curriculum and the other half did not. In Study 1, metacomprehension accuracy using the standard relative accuracy paradigm was significantly better for long-time students than for newcomers. In Study 2, all students engaged in delayed-keyword generation before judging their comprehension of texts. Metacomprehension accuracy was again significantly better for long-time students than for newcomers. Further, the superior monitoring accuracy led to more effective regulation of study, as seen in better decisions about which texts to restudy, that led, in turn, better comprehension. The results suggest the importance of early exposure to comprehension tests for developing skills in comprehension monitoring and self-regulated learning

    Booster Obsolescence and Life Extension (BOLE) for Space Launch System (SLS)

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    A human mission to the moon and Mars is the stated space exploration goal of the United States and the international community. To achieve these goals, NASA is developing the Space Launch System (SLS) and the Orion crew capsule as key elements in the architecture for missions to the moon and Mars. As part of the SLS Booster Obsolescence and Life Extension (BOLE) program, Northrop Grumman Innovation Systems is working to address booster obsolescence issues in design and manufacturing. The upgraded boosters will also provide increased performance that will benefit future lunar campaigns, science missions, and the eventual Mars campaign

    Radio Frequency Tag Satellite: Backscatter Communication in Low Earth Orbit

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    Wireless sensor communication can evaluate the structural integrity of a system while reducing the danger and cost of installation and maintenance on satellites. This is needed at the International Space Station as well as other satellites. The objective of this mission is to perform a demonstration using backscatter Radio Frequency Identification (RFID) Tag technology as a method of wireless communication in extremely low earth orbit. While RFID tag communication has been used on earth for many practical applications the technology has yet to be tested in space. A 3U Cubesat was selected as the configuration to house the experiment. This project utilizes an electrical power system, an interface board custom built around a microcontroller, and two radio communication systems to run the RFID experiment to be designed by a Georgia Tech engineering team. The RFID tag will be mounted to a carbon fiber boom that can be extended out one meter to incrementally collect data. This satellite will need to be strong enough to pass a series of vibration and heat tests to be qualified for flight. It will be programmed to maintain its own power, take data, and communicate the data back to earth via the Globalstar Network

    Illustrating potential efficiency gains from using cost-effectiveness evidence to reallocate Medicare expenditures

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    This article is available open access through the publisher’s website at the linke below. Copyright @ 2013, International Society for Pharmacoeconomics and Outcomes Research (ISPOR).This article has been made available through the Brunel Open Access Publishing Fund.Objectives - The Centers for Medicare & Medicaid Services does not explicitly use cost-effectiveness information in national coverage determinations. The objective of this study was to illustrate potential efficiency gains from reallocating Medicare expenditures by using cost-effectiveness information, and the consequences for health gains among Medicare beneficiaries. Methods - We included national coverage determinations from 1999 through 2007. Estimates of cost-effectiveness were identified through a literature review. For coverage decisions with an associated cost-effectiveness estimate, we estimated utilization and size of the “unserved” eligible population by using a Medicare claims database (2007) and diagnostic and reimbursement codes. Technology costs originated from the cost-effectiveness literature or were estimated by using reimbursement codes. We illustrated potential aggregate health gains from increasing utilization of dominant interventions (i.e., cost saving and health increasing) and from reallocating expenditures by decreasing investment in cost-ineffective interventions and increasing investment in relatively cost-effective interventions. Results - Complete information was available for 36 interventions. Increasing investment in dominant interventions alone led to an increase of 270,000 quality-adjusted life-years (QALYs) and savings of $12.9 billion. Reallocation of a broader array of interventions yielded an additional 1.8 million QALYs, approximately 0.17 QALYs per affected Medicare beneficiary. Compared with the distribution of resources prior to reallocation, following reallocation a greater proportion was directed to oncology, diagnostic imaging/tests, and the most prevalent diseases. A smaller proportion of resources went to cardiology, treatments (including drugs, surgeries, and medical devices, as opposed to nontreatments such as preventive services), and the least prevalent diseases. Conclusions - Using cost-effectiveness information has the potential to increase the aggregate health of Medicare beneficiaries while maintaining existing spending levels.The Commonwealth Fun

    A Bright Submillimeter Source in the Bullet Cluster (1E0657--56) Field Detected with BLAST

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    We present the 250, 350, and 500 micron detection of bright submillimeter emission in the direction of the Bullet Cluster measured by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). The 500 micron centroid is coincident with an AzTEC 1.1 mm point-source detection at a position close to the peak lensing magnification produced by the cluster. However, the 250 micron and 350 micron centroids are elongated and shifted toward the south with a differential shift between bands that cannot be explained by pointing uncertainties. We therefore conclude that the BLAST detection is likely contaminated by emission from foreground galaxies associated with the Bullet Cluster. The submillimeter redshift estimate based on 250-1100 micron photometry at the position of the AzTEC source is z_phot = 2.9 (+0.6 -0.3), consistent with the infrared color redshift estimation of the most likely IRAC counterpart. These flux densities indicate an apparent far-infrared luminosity of L_FIR = 2E13 Lsun. When the amplification due to the gravitational lensing of the cluster is removed, the intrinsic far-infrared luminosity of the source is found to be L_FIR <= 10^12 Lsun, consistent with typical luminous infrared galaxies.Comment: Accepted for publication in the Astrophysical Journal. Maps are available at http://blastexperiment.info
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