4,964 research outputs found

    Jamestown Board of Public Utilities and International Brotherhood of Electrical Workers Local 459

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    In the matter of the fact-finding between the Jamestown Board of Public Utilities, employer, and the International Brotherhood of Electrical Workers Local 459, union. PERB case no. M2009-336. Before: James R. McDonnell, Ph.D., fact finder

    Modeling and parameter uncertainties for aircraft flight control system design

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    Values of plant dynamic uncertainties for some recent aircraft design and development programs are given. Histories of pertinent aerodynamic, inertial, and structural parameter variations are given for a period of time from program initiation to aircraft certification. These data can be used as typical of future vehicles so that control system design concepts are evaluated with due consideration to their sensitivity to uncertainties in plant dynamics

    Extensional viscosity of copper nanowire suspensions in an aqueous polymer solution

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    Suspensions of copper nanowires are emerging as new electronic inks for next-generation flexible electronics. Using a novel surface acoustic wave driven extensional flow technique we are able to perform currently lacking analysis of these suspensions and their complex buffer. We observe extensional viscosities from 3 mPa⋅\cdots (1 mPa⋅\cdots shear viscosity) to 37.2 Pa⋅\cdots via changes in the suspension concentration, thus capturing low viscosities that have been historically very challenging to measure. These changes equate to an increase in the relative extensional viscosity of nearly 12,200 times at a volume fraction of just 0.027. We also find that interactions between the wires and the necessary polymer additive affect the rheology strongly. Polymer-induced elasticity shows a reduction as the buffer relaxation time falls from 819 to 59 μ\mus above a critical particle concentration. The results and technique presented here should aid in the future formulation of these promising nanowire suspensions and their efficient application as inks and coatings.Comment: 7 pages, 5 figures, under review for Soft Matter RS

    Searching for Hyperspectral Optical Proxies to Aid Chesapeake Bay Resource Managers in the Detection of Poor Water Quality

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    Shellfish aquaculture is a growing industry in the Chesapeake Bay. As population grows near the coast, extreme weather events cause a greater volume of pollutant runoff from impervious surfaces and agricultural lands. Resource managers who monitor shellfish beds need reliable information on a variety of water quality indicators at higher frequency than is possible through field monitoring programs and at a higher level of detail than current satellite products can provide. Although many factors causing degraded water quality that can impact human health are not currently discernable by traditional multispectral techniques, hyperspectral imagery offers a new opportunity to detect phytoplankton communities associated with harmful algal blooms and biotoxin production. Together with resource managers in their routine monitoring of sites around the bay from small boats, we have been exploring remotely sensed optical proxies for the detection of harmful algal blooms and sewage. Early warning by remote sensing could guide sampling and improve the efficiency of shellfish bed closures, ultimately improving health outcomes for humans and animals. An extensive network of routine sampling by Chesapeake Bay Program managers makes this is an ideal location to develop and test future satellite data products to support management decisions. Next generation hyperspectral measurements from the future Plankton Aerosol Cloud ocean Ecosystem (PACE) mission at nearly daily frequency, combined with the potential of higher spatial resolution from the Surface Biology and Geology (SBG) observing system recommended in the recent Decadal Survey, along with high frequency observations from the newly selected Geostationary Littoral Imaging and Monitoring Radiometer (GLIMR) Earth Venture Instrument make this a critical time for defining the needs of the aquaculture and resource management community to save lives, time, and money

    Trade-Offs Between Responsiveness and Naturalness for Player Characters

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    Real-time animation controllers are fundamental for animating characters in response to player input. However, the design of such controllers requires making trade-offs between the naturalness of the character’s motions and the promptness of the character’s response. In this paper, we investigate the effects of such tradeoffs on the players’ enjoyment, control, satisfaction, and opinion of the character in a simple platform game. In our first experiment, we compare three controllers having the same responsiveness, but varying levels of naturalness. In the second experiment, we compare three controllers having increasing realism but at the expense of decreased responsiveness. Not surprisingly, our least responsive controller negatively affects players’ performance and perceived ability to control the character. However, we also find that players are most satisfied with their own performance using our least natural controller, in which the character moves around the environment in a static pose; that differences in animation can significantly alter players’ enjoyment with responsiveness being equal; and that players do not report increased motion quality with our most natural controller, despite viewers outside of a game context rating the same controller as significantly more natural than our other conditions

    ELEVATED Α-FETOPROTEIN IN ASSOCIATION WITH LOSS OF SERUM HBeAg

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73663/1/j.1572-0241.1993.tb07621.x.pd

    Motility induced changes in viscosity of suspensions of swimming microbes in extensional flows

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    Suspensions of motile cells are model systems for understanding the unique mechanical properties of living materials which often consist of ensembles of self-propelled particles. We present here a quantitative comparison of theory against experiment for the rheology of such suspensions. The influence of motility on viscosities of cell suspensions is studied using a novel acoustically-driven microfluidic capillary-breakup extensional rheometer. Motility increases the extensional viscosity of suspensions of algal pullers, but decreases it in the case of bacterial or sperm pushers. A recent model [Saintillan, Phys. Rev. E, 2010, 81:56307] for dilute active suspensions is extended to obtain predictions for higher concentrations, after independently obtaining parameters such as swimming speeds and diffusivities. We show that details of body and flagellar shape can significantly determine macroscale rheological behaviour.Comment: 12 pages, 1 appendix, 7 figures, submitted to Soft Matter - under revie

    Young athletes under pressure?

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    Regular participation in exercise has long been known to result in cardiovascular adaptation. Historically, the ‘athlete’s heart’ hypothesis has encouraged a dichotomised view of the heart’s adaptation to sport, depending on whether the physical activity was either of isotonic activity (runners and swimmers) resulting in ‘cardiomegaly’ or of isometric effort (wrestlers and shot putters, ie, ‘strength’ athletes) with clear peripheral adaptations and an ‘obvious increase in cardiac size’. Today, the classification of sports according to their physiological demands acknowledges a greater diversity of exposure, depending on the physical activity, with an emphasis on a ‘graded transition’ between the main categories: dynamic, static and impact. Still, our understanding of the determinants of structural and functional cardiovascular adaptation to exercise are limited, and the consequences for health remain a matter of debate
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