5,341 research outputs found

    Debris control design achievements of the booster separation motors

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    The stringent debris control requirements imposed on the design of the Space Shuttle booster separation motor are described along with the verification program implemented to ensure compliance with debris control objectives. The principal areas emphasized in the design and development of the Booster Separation Motor (BSM) relative to debris control were the propellant formulation and nozzle closures which protect the motors from aerodynamic heating and moisture. A description of the motor design requirements, the propellant formulation and verification program, and the nozzle closures design and verification are presented

    Utilization of ERTS-1 data to monitor and classify eutrophication of inland lakes

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    A technique is being developed for use of ERTS in estimating and monitoring trophic levels of inland lakes. Preliminary findings are that Michigan lakes and ponds of one acre or more are resolvable in bands 5, 6 and 7 of NASA MSS imagery under fair conditions (haze and 70% cloud cover). In processed imagery (CCT) smaller features, including water color patterns, are evident within some lakes of 40 acres or more. Image distortion of lake size, shape, orientation, etc. is minimal; discrimination of lakes and ponds from various wetlands is good. Subsequent ERTS and aircraft imagery will be correlated with detailed ground truth of water color and quality in eutrophic test lakes

    5/14/1947 Letter from Margaret Chase Smith

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    Letter from Margaret Chase Smith, Maine Representative to the United States House of Representatives, to Louis-Philippe Gagné concerning H.R.2910. H.R. 2910 was introduced by Representative William Stratton (R-Illinois). This bill would have allowed a total of 400,000 persons displaced by WWII into the United States for resettlement over a four year period.https://digitalcommons.usm.maine.edu/fac-lpg-1947-04-06/1011/thumbnail.jp

    Japanese Octopus Traps & Broken Hearts: Takotsubo Cardiomyopathy

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    This academic poster provides a brief overview of Takotsubo Cardiomyopathy (TTC), it’s pathophysiology, and implications for nursing care. TTC is a non-ischemic cardiomyopathy that typically presents acutely in a very similar fashion to an acute myocardial infarction (Reeder & Prasad, 2015). Interestingly the disease primarily afflicts females (90% of cases) and is often triggered by an intense emotional or physical stressor (Minhas, Hughey & Kolas, 2014). Despite the acute onset and symptoms, the majority of cases are benign and resolve with conservative heart failure treatment (Scantlebury & Prasad, 2014) though a small percentage of cases can develop profound shock, resulting in significant mortality. An awareness and familiarity of the disease is certainly warranted for healthcare professionals as the disease has seen a three-fold increase in cases between 2007-2012 (Minhas, Hughey & Kolas, 2014)

    Examining Soil Based Construction Materials through X-Ray Computed Tomography

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    X-ray computed tomography (XRCT) enables the non-destructive analysis of samples internal structures down to a sub-micron resolution and has been used to examine the macrostructure of unstabilized soil based construction materials (SBCMs) alongside experiments on the materials unconfined compressive strength. SBCMs are manufactured mixtures of clay, sand and gravel which should be considered as highly unsaturated compacted soil where suction is the key source of strength. The use of XRCT in geotechnical literature is comprehensively reviewed before three laboratory investigations are described. Firstly crack propagation in SBCMs following unconfined compression is investigated and key lessons about XRCT scanning highlighted. Secondly the impact of altering sample size to match optimum XRCT scanning conditions is explored through experiments on void size distribution and unconfined compressive strength. Finally the effects of adding expansive clay to SBCM mixes on macrostructure are investigated and insights on how the unconfined compressive strength develops as SBCM dries are given. Conclusions from this thesis have applicability to both the SBCM industry, as the insights into the fundamental behaviour of SBCM can be used to inform building practice, and geotechnical researchers where the extensive use and development of XRCT can be applied to investigate the internal structure of a wide range of geotechnical materials

    Declaration of Conscience

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    Text of Senator Margaret Chase Smith\u27s address to U.S. Senate on June 1, 195

    Design and Analysis of High Frequency Power Converters for Envelope Tracking Applications

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    In the field of power electronics, designers are constantly researching new methods to improve efficiency while optimizing dynamic performance. As communication technologies progress we are more often dealing with systems of increasing speed and complexity. For instance, from 1991 to 2013 we have observed the mobile broadband communication sector evolve from ~230 Kbits/s (2G) speeds to ~100 Mbits/s (4G LTE), a 430% increase in communication speed. In contrast, we have not observed the same evolutionary development in industrial power converters. Most switch-mode power supplies are still manufactured for 100 KHz to 800 KHz operating frequencies. The main reason for this is that most electrical devices only require steady-state DC power, so high speed conversion performance is largely unnecessary. But as size expectations for portable electronic devices continue to decrease, the only way to meet future demand is to realize power electronics that operate at much higher switching frequencies. Furthermore there is increasing demand to improve the transient response requirements in processor-based systems and achieve practical envelope tracking in RF communication systems. The most straightforward method of increasing the dynamic response for these systems is to increase the switching frequency of the power electronics in a sustainable and coherent manner

    Modelling Social Structures and Hierarchies in Language Evolution

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    Language evolution might have preferred certain prior social configurations over others. Experiments conducted with models of different social structures (varying subgroup interactions and the role of a dominant interlocutor) suggest that having isolated agent groups rather than an interconnected agent is more advantageous for the emergence of a social communication system. Distinctive groups that are closely connected by communication yield systems less like natural language than fully isolated groups inhabiting the same world. Furthermore, the addition of a dominant male who is asymmetrically favoured as a hearer, and equally likely to be a speaker has no positive influence on the disjoint groups.Comment: 14 pages, 3 figures, 1 table. In proceedings of AI-2010, The Thirtieth SGAI International Conference on Innovative Techniques and Applications of Artificial Intelligence, Cambridge, England, UK, 14-16 December 201
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