12,379 research outputs found

    Organizing for Product Development

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    In this paper, we propose four parameters that determine appropriate organizational structure for a research, development or engineering organization. Examining the positions that an organization occupies on the four parameters will determine relative need for interaction with the market and with supporting technologies as well as the need for coordination among project team members. This, along with the time needed to bring the product to market, can then be translated into an organizational structure, giving proper emphases to each of the three needs

    Activated dynamics and effective temperature in a steady state sheared glass

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    We conduct nonequilibrium molecular dynamics simulations to measure the shear stress, the average inherent structure energy, and the effective temperature TeffT_{eff} of a sheared model glass as a function of bath temperature TT and shear strain rate. For TT above the glass transition temperature T0T_0, the rheology approaches a Newtonian limit and TeffT_{eff} approaches TT as the strain rate approaches zero, while for T<T0T<T_0, the shear stress approaches a yield stress and TeffT_{eff} approaches a limiting value near T0T_0. In the shear-dominated regime at high TT, high strain rate or at low TT, we find that the shear stress and the average inherent structure energy each collapse onto a single curve as a function of TeffT_{eff}. This indicates that TeffT_{eff} is controlling behavior in this regime.Comment: 4 pages, 2 figures. Revised to include additional data. Inherent structure energy results were included, and much of the shear transformation zone discussion was remove

    Precipitation Trends across the Commonwealth of Virginia (1947 – 2016)

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    Water is an important resource for the Commonwealth of Virginia. Too much water increases runoff, disrupt transportation networks, and contributes to school closures. Too little water may adversely impact agricultural operations. To improve climate-related information to Virginia citizens, this study assesses means and changes in precipitation across the Commonwealth of Virginia (1947 – 2016). Using daily station-level precipitation data from the Global Historical Climate Network (GHCN), descriptive statistics were calculated for 43 locations in terms of total precipitation (inches decade-1), precipitation days (x\u3e0”), and heavy precipitation days (x\u3e1.0”). On average, locations showed an overall increase in total precipitation across the time period. The frequency of heavy rainfall events has also increased across many of the analyzed locations. Precipitation has important ramifications for agriculture, storm water management, and hazard response, and improved coordination of atmospheric-related information may be beneficial to various stakeholders across the Commonwealth

    Computing the local pressure in molecular dynamics simulations

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    Computer simulations of inhomogeneous soft matter systems often require accurate methods for computing the local pressure. We present a simple derivation, based on the virial relation, of two equivalent expressions for the local (atomistic) pressure in a molecular dynamics simulation. One of these expressions, previously derived by other authors via a different route, involves summation over interactions between particles within the region of interest; the other involves summation over interactions across the boundary of the region of interest. We illustrate our derivation using simulations of a simple osmotic system; both expressions produce accurate results even when the region of interest over which the pressure is measured is very small.Comment: 11 pages, 4 figure

    Plasmas generated by ultra-violet light rather than electron impact

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    We analyze, in both plane and cylindrical geometries, a collisionless plasma consisting of an inner region where generation occurs by UV illumination, and an un-illuminated outer region with no generation. Ions generated in the inner region flow outwards through the outer region and into a wall. We solve for this system's steady state, first in the quasi-neutral regime (where the Debye length ÎťD{\lambda}_D vanishes and analytic solutions exist) and then in the general case, which we solve numerically. In the general case a double layer forms where the illuminated and un-illuminated regions meet, and an approximately quasi-neutral plasma connects the double layer to the wall sheath; in plane geometry the ions coast through the quasi-neutral section at slightly more than the Bohm speed csc_s. The system, although simple, therefore has two novel features: a double layer that does not require counter-streaming ions and electrons, and a quasi-neutral plasma where ions travel in straight lines with at least the Bohm speed. We close with a pr\'{e}cis of our asymptotic solutions of this system, and suggest how our theoretical conclusions might be extended and tested in the laboratory.Comment: 10 pages, 3 figures, accepted by Physics of Plasma

    An eighth-century inscribed cross-slab in Dull, Perthshire

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    The discovery of a cross-inscribed slab with an inscription is described. Because of its importance it was decided to invite specialist comment on this piece of sculpture and to publish it in advance of the full report on the excavations. The form of the monument, its inscription and archaeological context are considered. The text appears to consist of a Gaelic personal name. The script is a form of geometrical lettering which can be dated to the opening quarter of the eighth century. The form of the cross has Columban associations which sit well with place-name and other evidence which points to Dull having been a monastery founded from Iona by c. AD 700

    Durrington Walls to West Amesbury by way of Stonehenge: a major transformation of the Holocene landscape

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    A new sequence of Holocene landscape change has been discovered through an investigation of sediment sequences, palaeosols, pollen and molluscan data discovered during the Stonehenge Riverside Project. The early post-glacial vegetational succession in the Avon valley at Durrington Walls was apparently slow and partial, with intermittent woodland modification and the opening-up of this landscape in the later Mesolithic and earlier Neolithic, though a strong element of pine lingered into the third millennium BC. There appears to have been a major hiatus around 2900 cal BC, coincident with the beginnings of demonstrable human activities at Durrington Walls, but slightly after activity started at Stonehenge. This was reflected in episodic increases in channel sedimentation and tree and shrub clearance, leading to a more open downland, with greater indications of anthropogenic activity, and an increasingly wet floodplain with sedges and alder along the river’s edge. Nonetheless, a localized woodland cover remained in the vicinity of DurringtonWalls throughout the third and second millennia BC, perhaps on the higher parts of the downs, while stable grassland, with rendzina soils, predominated on the downland slopes, and alder–hazel carr woodland and sedges continued to fringe the wet floodplain. This evidence is strongly indicative of a stable and managed landscape in Neolithic and Bronze Age times. It is not until c 800–500 cal BC that this landscape was completely cleared, except for the marshy-sedge fringe of the floodplain, and that colluvial sedimentation began in earnest associated with increased arable agriculture, a situation that continued through Roman and historic times

    MR418: Farm Property Taxes in Maine

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    The purpose of this report is to look at the effect of property taxes on agriculture in Maine using existing data sources. We investigate four specific issues: (1) whether property taxes on agricultural lands in Maine differ from the property taxes on agricultural lands at a national level; (2) whether property taxes on agricultural lands in Maine differ from the property taxes on land in nonagricultural uses in Maine; (3) whether property taxes have increased as a percentage of production costs for Maine agriculture over the past fifty years; (4) whether property taxes on agricultural lands differ for farms located in different regions of the statehttps://digitalcommons.library.umaine.edu/aes_miscreports/1007/thumbnail.jp
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