3,973 research outputs found

    The effect of capital and labor on a manufacturing process: a production function approach

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    Modification of neoclassical production function models is proposed by this paper to adapt them for microeconomic or manufacturing shop environments. Production function terminology, the formulation of production function models for actual shops, and illustrations of possible utilization by management are presented

    An All Optical Fibre Quantum Controlled-NOT Gate

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    We report the first experimental demonstration of an optical controlled-NOT gate constructed entirely in fibre. We operate the gate using two heralded optical fibre single photon sources and find an average logical fidelity of 90% and an average process fidelity of 0.83<F<0.91. On the basis of a simple model we are able to conclude that imperfections are primarily due to the photon sources, meaning that the gate itself works with very high fidelity.Comment: 4 pages, 4 figures, comments welcom

    Prediction of Undsteady Flows in Turbomachinery Using the Linearized Euler Equations on Deforming Grids

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    A linearized Euler solver for calculating unsteady flows in turbomachinery blade rows due to both incident gusts and blade motion is presented. The model accounts for blade loading, blade geometry, shock motion, and wake motion. Assuming that the unsteadiness in the flow is small relative to the nonlinear mean solution, the unsteady Euler equations can be linearized about the mean flow. This yields a set of linear variable coefficient equations that describe the small amplitude harmonic motion of the fluid. These linear equations are then discretized on a computational grid and solved using standard numerical techniques. For transonic flows, however, one must use a linear discretization which is a conservative linearization of the non-linear discretized Euler equations to ensure that shock impulse loads are accurately captured. Other important features of this analysis include a continuously deforming grid which eliminates extrapolation errors and hence, increases accuracy, and a new numerically exact, nonreflecting far-field boundary condition treatment based on an eigenanalysis of the discretized equations. Computational results are presented which demonstrate the computational accuracy and efficiency of the method and demonstrate the effectiveness of the deforming grid, far-field nonreflecting boundary conditions, and shock capturing techniques. A comparison of the present unsteady flow predictions to other numerical, semi-analytical, and experimental methods shows excellent agreement. In addition, the linearized Euler method presented requires one or two orders-of-magnitude less computational time than traditional time marching techniques making the present method a viable design tool for aeroelastic analyses

    Pioneer Experience in Walla Walla

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    "Your father's name? Ransom Clark. When did he first see the Walla Walla Valley? He was one of four or five American citizens who came across the continent in 1843 with the exploration company of Lieutenant John C. Fremont.

    Long-term CO2 enrichment of a forest ecosystem : implications for forest regeneration and succession

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    Author Posting. © Ecological Society of America, 2007. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 17 (2007): 1198–1212, doi:10.1890/05-1690.The composition and successional status of a forest affect carbon storage and net ecosystem productivity, yet it remains unclear whether elevated atmospheric carbon dioxide (CO2) will impact rates and trajectories of forest succession. We examined how CO2 enrichment (+200 μL CO2/L air differential) affects forest succession through growth and survivorship of tree seedlings, as part of the Duke Forest free-air CO2 enrichment (FACE) experiment in North Carolina, USA. We planted 2352 seedlings of 14 species in the low light forest understory and determined effects of elevated CO2 on individual plant growth, survival, and total sample biomass accumulation, an integrator of plant growth and survivorship over time, for six years. We used a hierarchical Bayes framework to accommodate the uncertainty associated with the availability of light and the variability in growth among individual plants. We found that most species did not exhibit strong responses to CO2. Ulmus alata (+21%), Quercus alba (+9.5%), and nitrogen-fixing Robinia pseudoacacia (+230%) exhibited greater mean annual relative growth rates under elevated CO2 than under ambient conditions. The effects of CO2 were small relative to variability within populations; however, some species grew better under low light conditions when exposed to elevated CO2 than they did under ambient conditions. These species include shade-intolerant Liriodendron tulipifera and Liquidambar styraciflua, intermediate-tolerant Quercus velutina, and shade-tolerant Acer barbatum, A. rubrum, Prunus serotina,Ulmus alata, and Cercis canadensis. Contrary to our expectation, shade-intolerant trees did not survive better with CO2 enrichment, and population-scale responses to CO2 were influenced by survival probabilities in low light. CO2 enrichment did not increase rates of sample biomass accumulation for most species, but it did stimulate biomass growth of shade-tolerant taxa, particularly Acer barbatum and Ulmus alata. Our data suggest a small CO2 fertilization effect on tree productivity, and the possibility of reduced carbon accumulation rates relative to today's forests due to changes in species composition.This research was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-95ER62083, and by Terrestrial Ecosystems and Global Change (TECO) Grant No. DE-F602-97ER62463

    Record of an alleged Solitary Eagle in Oaxaca is a Great Black Hawk

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    In a recent article in this journal (García-Grajales et al., 2018), an adult Great Black Hawk (Buteogallus urubitinga) was mistakenly identified as an adult of the Solitary Eagle (Buteogallus solitarius). The Solitary Eagle differs from the Greater Black Eagle in having the longest and widest wings, and the shortest tail. These characteristics give it a more triangular shape in flight. These differences are easy to see in Figures 1–3. The same authors also cite a case of the nesting of the Solitary Eagle in Mexico (Smith, 1982). However, after reviewing photos of the young, we consider that this record is probably the Common Black Hawk (B. anthracinus). The illustrations of the Solitary Eagle in field guides of Mexico and Central America (Howell &amp; Webb, 1995; Van Perlo, 2006) demonstrate greater similarity with the Great Black Hawk, contributing to the frequent confusion of the two species if used without consulting the text. The new features published here and in Clark et al. (2006) and Clark and Schmitt (2017) should help with correct identification of Buteogallus species in the future.En un artículo reciente en esta revista (García-Grajales et al., 2018), un adulto del Aguililla Negra Mayor (Buteogallus urubitinga) fue identificado erróneamente como un adulto del Águila Solitaria (Buteogallus solitarius). El Águila Solitaria difiere del Aguililla Negra Mayor en tener las alas más largas y anchas, y la cola más corta. Estas características le confieren una forma más triangular en el vuelo. Estas diferencias son fáciles de apreciar en la Figuras 1–3. Los mismos autores también citan un caso del anidamiento del Águila Solitaria en México (Smith, 1982). Sin embargo, después de revisar fotos de las crías, consideramos que este registro probablemente se trata del Aguililla Negra Menor (B. anthracinus). Las ilustraciones del Águila Solitaria en guías de campo de México y Centroamérica (Howell &amp; Webb, 1995; Van Perlo, 2006) demuestran mayor similitud con el Aguililla Negra Mayor, contribuyendo a la confusión frecuente de las dos especies si se utilizan sin consultar el texto. Las nuevas características publicadas aquí y en Clark et al. (2006) y Clark y Schmitt (2017) deben ayudar a su correcta identificación en el futuro

    1864-09-12 Captain William S. Clark recommends promotion of Lieutenant Benjamin F. Rollins and Sergeant Frank A. Clark

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