14,563 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 λD{\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

    Sense of Place: American Regional Cultures

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    Despite the homogenization of American life, areas of strong regional consciousness still persist in the United States, and there is a growing interest in regionalism among the public and among academics. In response to that interest ten folklorists here describe and interpret a variety of American regional cultures in the twentieth century. Their book is the first to deal specifically with regional culture and the first to employ the perspective of folklore in the study of regional identity and consciousness. The authors range widely over the United States, from the Eastern Shore to the Pacific Northwest, from the Southern Mountains to the Great Plains. They look at a variety of cultural expressions and practices—legends, anecdotes, songs, foodways, architecture, and crafts. Tying their work together is a common consideration of how regional culture shapes and is shaped by the consciousness of living in a special place. In exploring this dimension of regional culture the authors consider the influence of natural environment and historical experience on the development of regional culture, the role of ethnicity in regional consciousness, the tensions between insiders and outsiders that stem from a sense of regional identity, and the changes in culture in response to social and economic change. With its focus on cultural manifestations and its folkloristic perspective this book provides a fresh and needed contribution to regional studies. Writ¬ten in a clear, readable style, it will appeal to general readers interested in American regions and their cultures. At the same time the research and analytical approach make it useful not only to folklorists but to cultural geographers, anthropologists, and other scholars of regional studies. Barbara Allen is chair of the Department of American Studies at the University of Notre Dame. Thomas J. Schlereth is professor of American studies at the University of Notre Dame. Presents valuable work on parts of the U.S. that are somewhat sparsely represented in folklore publications. —Choice Reinforces what we may have already expected—that the folk region lies in the mind and spirit as much as in physical boundaries. —South Bend Tribunehttps://uknowledge.uky.edu/upk_folklore/1008/thumbnail.jp

    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

    Web Applet For Predicting Structure And Thermodynamics Of Complex Fluids

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    Based on a recently introduced analytical strategy [Hollingshead et al., J. Chem. Phys. 139, 161102 (2013)], we present a web applet that can quickly and semi-quantitatively estimate the equilibrium radial distribution function and related thermodynamic properties of a fluid from knowledge of its pair interaction. We describe the applet's features and present two (of many possible) examples of how it can be used to illustrate concepts of interest for introductory statistical mechanics courses: the transition from ideal gas-like behavior to correlated-liquid behavior with increasing density, and the tradeoff between dominant length scales with changing temperature in a system with ramp-shaped repulsions. The latter type of interaction qualitatively captures distinctive thermodynamic properties of liquid water, because its energetic bias toward locally open structures mimics that of water's hydrogen-bond network. (C) 2015 American Association of Physics Teachers.Chemical Engineerin
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