118 research outputs found

    Flight Measurements of Flying Qualities of a P-47D-30 Airplane (AAF No. 43-3441) to Determine Longitudinal Stability and Control and Stalling Characteristics

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    Flight tests have been made to determine the longitudinal stability and control and stalling characteristics of the P-47.E-30 airplane. The teat results show the airplane to be unstable stick free in any power-on condition even at the most forward center-of-gravity position tested. At the rearward center-of-gravity position tested the airplane also had neutral to negative stick-fixed stability with power on. The characteristics in accelerated flight were acceptable at the forward center-of-gravity position at low and high altitudes except at high speed where the control-force variations with acceleration were high. At the rearward center-of-gravity position, elevator-force reversals were experienced in turns at low speeds, and the force per g was low at all the other speeds. Ample stall warning was afforded in all the conditions tested and the stalling characteristics were very satisfactory except in the approach and wave-off conditions

    Water solubility in aluminosilicate melts of haplogranite composition at 2 kbar

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    The compositional dependence of H2O solubility was investigated at 2 kbar and 800°C in haplogranite melts (system SiO2---1bNaAlSi3O8---1bKAlSi3O8 or Qz---1bAb---1bOr). The sixteen investigated compositions contained 25, 35 or 45 wt.% normative Qz and various Ab/(Ab+Or) ratios (0.15–0.92). Starting solid materials were anhydrous bubble-free glasses to which 10 wt.% H2O was added. The H2O contents of the isobarically quenched melts (glasses) were measured by Karl-Fischer titration. The results show that H2O solubility in aluminosilicate melts depends significantly upon anhydrous composition. The highest solubility values are obtained for the most Ab-rich melts. At a constant normative quartz content, the solubility of water decreases from 6.49 ± 0.20 wt.% H2O for a composition Qz35Ab60Or05 (normative composition expressed in wt.%) to 5.50 ± 0.15 wt.% H2O for a composition Qz35Ab10Or55. Along this join, the most significant changes are observed for Ab-rich melts whereas H2O solubility in Or-rich melts remains almost constant. The H2O solubility data imply that H2O is preferentially associated with the Ab component in aluminosilicate melts. Application of the results to natural granitic melts suggests that Na-rich, H2O-saturated melts may be significantly less viscous than H2O-saturated, K-rich melts. The temperature dependence of H2O solubility, investigated for composition Qz28Ab38Or34 at 2 kbar, is low. Increasing temperature from 750° to 1150°C only causes a decrease in H2O solubility from 6.00 to 5.41 wt.% H2O. These data are in agreement with previous data obtained for albite melts

    NCSX Vacuum Vessel Fabrication

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    The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in conjunction with the Oak Ridge National Laboratory (ORNL). The goal of this experiment is to develop a device which has the steady state properties of a traditional stellarator along with the high performance characteristics of a tokamak. A key element of this device is its highly shaped Inconel 625 vacuum vessel. This paper describes the manufacturing of the vessel. The vessel is being fabricated by Major Tool and Machine, Inc. (MTM) in three identical 120º vessel segments, corresponding to the three NCSX field periods, in order to accommodate assembly of the device. The port extensions are welded on, leak checked, cut off within 1" of the vessel surface at MTM and then reattached at PPPL, to accommodate assembly of the close-fitting modular coils that surround the vessel. The 120º vessel segments are formed by welding two 60º segments together. Each 60º segment is fabricated by welding ten press-formed panels together over a collapsible welding fixture which is needed to precisely position the panels. The vessel is joined at assembly by welding via custom machined 8" (20.3 cm) wide spacer "spool pieces." The vessel must have a total leak rate less than 5 X 10-6 t-l/s, magnetic permeability less than 1.02μ, and its contours must be within 0.188" (4.76 mm). It is scheduled for completion in January 2006

    NCSX Construction Progress and Research Plans

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    Stellarators use 3D plasma and magnetic field shaping to produce a steady-state disruption-free magnetic confinement configuration. Compact stellarators have additional attractive properties — quasi-symmetric magnetic fields and low aspect ratio. The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in partnership with the Oak Ridge National Laboratory (ORNL) to test the physics of a high-beta compact stellarator with a lowripple, tokamak-like magnetic configuration. The engineering challenges of NCSX stem from its complex geometry requirements. These issues are addressed in the construction project through manufacturing R&D and system engineering. As a result, the fabrication of the coil winding forms and vacuum vessel are proceeding in industry without significant technical issues, and preparations for winding the coils at PPPL are in place. Design integration, analysis, and dimensional control are functions provided by system engineering to ensure that the finished product will satisfy the physics requirements, especially accurate realization of the specified coil geometries. After completion of construction in 2009, a research program to test the expected physics benefits will start

    Role of Pleiotropy in the Evolution of a Cryptic Developmental Variation in Caenorhabditis elegans

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    Using vulval phenotypes in Caenorhabditis elegans, the authors show that cryptic genetic variation can evolve through selection for pleiotropic effects that alter fitness, and identify a cryptic variant that has conferred enhanced fitness on domesticated worms under laboratory conditions

    The severity of pandemic H1N1 influenza in the United States, from April to July 2009: A Bayesian analysis

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    Background: Accurate measures of the severity of pandemic (H1N1) 2009 influenza (pH1N1) are needed to assess the likely impact of an anticipated resurgence in the autumn in the Northern Hemisphere. Severity has been difficult to measure because jurisdictions with large numbers of deaths and other severe outcomes have had too many cases to assess the total number with confidence. Also, detection of severe cases may be more likely, resulting in overestimation of the severity of an average case. We sought to estimate the probabilities that symptomatic infection would lead to hospitalization, ICU admission, and death by combining data from multiple sources. Methods and Findings: We used complementary data from two US cities: Milwaukee attempted to identify cases of medically attended infection whether or not they required hospitalization, while New York City focused on the identification of hospitalizations, intensive care admission or mechanical ventilation (hereafter, ICU), and deaths. New York data were used to estimate numerators for ICU and death, and two sources of data - medically attended cases in Milwaukee or self-reported influenza-like illness (ILI) in New York - were used to estimate ratios of symptomatic cases to hospitalizations. Combining these data with estimates of the fraction detected for each level of severity, we estimated the proportion of symptomatic patients who died (symptomatic case-fatality ratio, sCFR), required ICU (sCIR), and required hospitalization (sCHR), overall and by age category. Evidence, prior information, and associated uncertainty were analyzed in a Bayesian evidence synthesis framework. Using medically attended cases and estimates of the proportion of symptomatic cases medically attended, we estimated an sCFR of 0.048% (95% credible interval [CI] 0.026%-0.096%), sCIR of 0.239% (0.134%-0.458%), and sCHR of 1.44% (0.83%-2.64%). Using self-reported ILI, we obtained estimates approximately 7-96lower. sCFR and sCIR appear to be highest in persons aged 18 y and older, and lowest in children aged 5-17 y. sCHR appears to be lowest in persons aged 5-17; our data were too sparse to allow us to determine the group in which it was the highest. Conclusions: These estimates suggest that an autumn-winter pandemic wave of pH1N1 with comparable severity per case could lead to a number of deaths in the range from considerably below that associated with seasonal influenza to slightly higher, but with the greatest impact in children aged 0-4 and adults 18-64. These estimates of impact depend on assumptions about total incidence of infection and would be larger if incidence of symptomatic infection were higher or shifted toward adults, if viral virulence increased, or if suboptimal treatment resulted from stress on the health care system; numbers would decrease if the total proportion of the population symptomatically infected were lower than assumed.published_or_final_versio
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