885 research outputs found

    Rasch model usage for testing results assessment

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    Automated system for the creation and replenishment of users' electronic lexicographical resources

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    This article proposes a solution to improve the efficiency of automated generation of electronic lexicographical resources based on strongly-structured electronic information arrays processing. The developed automated information system for lexicographical resources creation and replenishment have been described is this article. Several supporting subsystems of developed automated system have been characterized. The effectiveness of the information system has been evaluated

    Tungsten wire/FeCrAlY matrix turbine blade fabrication study

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    The objective was to establish a viable FRS monotape technology base to fabricate a complex, advanced turbine blade. All elements of monotape fabrication were addressed. A new process for incorporation of the matrix, including bi-alloy matrices, was developed. Bonding, cleaning, cutting, sizing, and forming parameters were established. These monotapes were then used to fabricate a 48 ply solid JT9D-7F 1st stage turbine blade. Core technology was then developed and first a 12 ply and then a 7 ply shell hollow airfoil was fabricated. As the fabrication technology advanced, additional airfoils incorporated further elements of sophistication, by introducing in sequence bonded root blocks, cross-plying, bi-metallic matrix, tip cap, trailing edge slots, and impingement inserts

    Two-step percolation in aggregating systems

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    The two-step percolation behavior in aggregating systems was studied both experimentally and by means of Monte Carlo (MC) simulations. In experimental studies, the electrical conductivity, σ\sigma, of colloidal suspension of multiwalled carbon nanotubes (CNTs) in decane was measured. The suspension was submitted to mechanical de-liquoring in a planar filtration-compression conductometric cell. During de-liquoring, the distance between the measuring electrodes continuously decreased and the CNT volume fraction φ\varphi continuously increased (from 10310^{-3} up to 0.3\approx 0.3% v/v). The two percolation thresholds at φ1103\varphi_{1}\lesssim 10^{-3} and φ2102\varphi_{2}\approx 10^{-2} can reflect the interpenetration of loose CNT aggregates and percolation across the compact conducting aggregates, respectively. The MC computational model accounted for the core-shell structure of conducting particles or their aggregates, the tendency of a particle for aggregation, the formation of solvation shells, and the elongated geometry of the conductometric cell. The MC studies revealed two smoothed percolation transitions in σ(φ)\sigma(\varphi) dependencies that correspond to the percolation through the shells and cores, respectively. The data demonstrated a noticeable impact of particle aggregation on anisotropy in electrical conductivity σ(φ)\sigma(\varphi) measured along different directions in the conductometric cell.Comment: 10 pages, 6 figure

    Agroecological substantiation of Medicago sativa cultivation technology

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    Medicago sativa is one of the most productive legumes, which provides high protein production. Application of the biostimulant and microfertilizers is quite relevant and effective. Theoretically substantiates and presents ways to solve the scientific problem of formation of Medicago sativa productivity and the impact on them of seed treatment and foliar nutrition, taking into account the conditions of the Forest-Steppe right bankof Ukraine. The research was conducted in the research field of Vinnytsia National Agrarian University in the village of Agronomichne, Vinnytsia district during 2016–2018. Sinyukha variety was sown (2010). There has been established that the use of pre-sowing treatment of seeds and crops of Medicago sativa with biostimulant and microfertilizer improves the conditions of growth and development of the crop and increases individual productivity. On the researches it is established that fodder productivity of Medicago sativa sowing is provided by application of biostimulators of growth and microfertilizers on crops, genetic potential the culture realized as much as possible on the 2nd year of cultivation. The effect of growth stimulants on Medicago sativa productivity was defined and the optimal combination of macro- and microelements in modern complex fertilizers was determined, which contributes to the maximum possible yield of Medicago sativa green mass. New technological regulations for the use of bioorganic preparations and components in the technological scheme of Medicago sativa cultivation have been developed. It was found that on average for three years of vegetation of Medicago sativa sown on gray forest soils in the Forest-Steppe Right Bank, the highest yield of seeds and green mass provides the option of treatment with biostimulator Saprogum® and microfertilizer Wuxal®. Creating optimal conditions for mineral nutrition for Medicago sativa plants through the use of bacterial fertilizers and foliar nutrition contributed not only to the formation of high grain yields, but also significantly improved biochemical parameters and, consequently, increased crude protein content in grain, which is important for solving the problem of vegetable protein and balancing the diets of farm animals. The research results are aimed at solving current problems of technological renewal and development of agro-industrial complex on the basis of development of bioorganic models of varietal technology of Medicago sativa cultivation with orientation at the level of adequate arable productivity and climate fertility
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