2,179 research outputs found

    Improved diamond coring bits developed for dry and chip-flush drilling

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    Two rotary diamond bit designs, one operating with a chip-flushing fluid, the second including auger section to remove drilled chips, enhance usefulness of tool for exploratory and industrial core-drilling of hard, abrasive mineral deposits and structural masonry

    Since You Called Me Dearie

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    https://digitalcommons.library.umaine.edu/mmb-vp/6532/thumbnail.jp

    Microgravity vibration isolation: An optimal control law for the one-dimensional case

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    Certain experiments contemplated for space platforms must be isolated from the accelerations of the platforms. An optimal active control is developed for microgravity vibration isolation, using constant state feedback gains (identical to those obtained from the Linear Quadratic Regulator (LQR) approach) along with constant feedforward (preview) gains. The quadratic cost function for this control algorithm effectively weights external accelerations of the platform disturbances by a factor proportional to (1/omega)(exp 4). Low frequency accelerations (less than 50 Hz) are attenuated by greater than two orders of magnitude. The control relies on the absolute position and velocity feedback of the experiment and the absolute position and velocity feedforward of the platform, and generally derives the stability robustness characteristics guaranteed by the LQR approach to optimality. The method as derived is extendable to the case in which only the relative positions and velocities and the absolute accelerations of the experiment and space platform are available

    Feature integration in natural language concepts

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    Two experiments measured the joint influence of three key sets of semantic features on the frequency with which artifacts (Experiment 1) or plants and creatures (Experiment 2) were categorized in familiar categories. For artifacts, current function outweighed both originally intended function and current appearance. For biological kinds, appearance and behavior, an inner biological function, and appearance and behavior of offspring all had similarly strong effects on categorization. The data were analyzed to determine whether an independent cue model or an interactive model best accounted for how the effects of the three feature sets combined. Feature integration was found to be additive for artifacts but interactive for biological kinds. In keeping with this, membership in contrasting artifact categories tended to be superadditive, indicating overlapping categories, whereas for biological kinds, it was subadditive, indicating conceptual gaps between categories. It is argued that the results underline a key domain difference between artifact and biological concepts

    Chemical kinetic and photochemical data for use in stratospheric modelling

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    An evaluated set of rate constants and photochemical cross sections were compiled for use in modelling stratospheric processes. The data are primarily relevant to the ozone layer, and its possible perturbation by anthropogenic activities. The evaluation is current to, approximately, January, 1979

    Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas

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    Solutions of 1,3-diketones and 1,3-ketoester derivatives react with fluorine to give the corresponding 2,2-difluoro-1,3-dicarbonyl derivatives in the presence of quinuclidine. Quinuclidine reacts with fluorine in situ to generate a fluoride ion that facilitates limiting enolization processes, and an electrophilic N-F fluorinating agent that is reactive towards neutral enol species

    Disease Control and Plant Growth Promotion of \u3cem\u3e Miscanthus \u3c/em\u3e × \u3cem\u3e giganteus \u3c/em\u3e with \u3cem\u3e Trichoderma \u3c/em\u3e Bio-Inoculants

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    The second-generation bioenergy crop Miscanthus (Miscanthus × giganteus) is being assessed in New Zealand for its potential to provide shelter on irrigated dairy farms. Miscanthus is a perennial sterile hybrid vegetatively propagated rhizomatous C4 grass and the young rhizomes and roots are prone to infection by soil-borne fungal pathogens (Glynn et al., 2015) which can cause deleterious effects on plant establishment and growth. In Europe, several species of Fusarium such as F. avenaceum, F. culmorum, F. moniliforme and F. oxysporum have been implicated as causal agents of root and rhizome rot (Thinggaard, 1997; Covarelli et al., 2012) leading to poor field establishment of in-vitro propagated Miscanthus plants. When tested for their ability to cause disease of Miscanthus, Rhizoctonia solani (Kuhn) was reported as the most aggressive species among nineteen fungal pathogens of cereal crops (Glynn et al. 2015). In New Zealand, R. solani reduces seedling emergence and plant establishment of several herbage species and the problem may be alleviated through biocontrol using Trichoderma fungi (Kandula et al., 2015). In a glass-house study, the effect of four T. atroviride isolates on growth of tissue culture propagated Miscanthus plants in a soil naturally infested with R. solani was investigated

    Residual Strength Predictions with Crack Buckling

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    Fracture tests were conducted on middle crack tension, M(T), and compact tension, C(T), specimens of varying widths, constructed from 0.063 inch thick sheets of 2024-T3 aluminum alloy. Guide plates were used to restrict out-of-plane displacements in about half of the tests. Analyses using the three-dimensional, elastic-plastic finite element code WARP3D simulated the tests with and without guide plates using a critical CTOA fracture criterion. The experimental results indicate that crack buckling reduced the failure loads by up to 40%. Using a critical CTOA value of 5.5 deg., the WARP3D analyses predicted the failure loads for the tests with guide plates within +/- 10% of the experimentally measured values. For the M(T) tests without guide plates, the WARP3D analyses predicted the failure loads for the 12 and 24 inch tests within 10%, while over predicting the failure loads for the 40 inch wide tests by about 20%

    Farm-Tractor-Related Fatalities -- Kentucky, 1994

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    Fatalities associated with farm tractors are the most common cause of work-related death in the U.S. agricultural industry (1). To characterize farm-tractor-related fatalities in Kentucky, the Kentucky Fatality Assessment and Control Evaluation (KY FACE) Project studied all fatal farm injuries occurring among persons in that state during 1994, the initial year of operation for FACE in Kentucky. This report summarizes the results of that study
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