2,424 research outputs found
Nitretação por plasma de ferro puro enriquecido superficialmente com molibdênio
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência e Engenharia de Materiais.Neste trabalho, amostras de ferro puro, sinterizadas e enriquecidas superficialmente com molibdênio via plasma, foram submetidas ao tratamento termoquímico de nitretação por plasma, visando melhorar as propriedades mecânicas na região superficial das amostras. Foram realizados estudos em diferentes condições para tratamento superficial de nitretação por plasma variando-se a mistura gasosa N2-H2 e a temperatura de nitretação. Duas temperaturas de nitretação (450o C e 540o C) e duas concentrações de nitrogênio na mistura nitretante N2-H2 (baixa concentração 5% de N2 e alta concentração 75% de N2) foram empregadas para realização do trabalho. Com a escolha dessas variáveis no processo de nitretação foi possível definir a melhor condição de nitretação para endurecimento da camada enriquecida com Mo. A caracterização microestrutural das camadas enriquecidas e nitretadas foram realizadas por microscopia ótica (MO) e microscopia eletrônica de varredura (MEV) e as fases presentes por difração de raios X (DRX). Testes de microdureza avaliaram o endurecimento das camadas obtidas. Os resultados mostram que ocorre um aumento significativo na dureza da camada enriquecida com molibdênio e nitretada. A presença de Mo na região superficial da amostra leva a formação de microestruturas com diferentes morfologias dependentes da temperatura e do teor de nitrogênio no processo de nitretação. Não foi possível identificar fases relativas à formação de nitretos de molibdênio ou nitretos mistos de Fe-Mo-N nas análises de DRX para as amostras enriquecidas e nitretadas por plasma, mas acredita-se que eles estão presentes devido ao aumento no perfil de microdureza das amostras enriquecidas. Amostras de Mo puro também foram nitretadas nas mesmas condições com a finalidade de comparar as amostras, verificar a formação de MoN e avaliar o comportamento do perfil de microdureza. Este trabalho mostrou que a nitretação de compactados metálicos enriquecidos superficialmente com Mo, melhora a dureza da camada nitretada.In this work, aiming to improve the surface properties, unalloyed iron samples, sintered and enriched superficially with molybdenum by Plasma, were subjected to the thermochemical treatment of nitriding by Plasma. Studies of the nitriding treatments by plasma were carried out in different conditions: varying to gas mixture (H2-N2) and temperature of nitriding. Two different temperatures (450o C and 540o C) and two concentrations of nitrogen in the gas mixture N2-H2 (low concentration 5% of N2 and high concentration 75% N2) were investigated. With the choice of the variables to the realized nitriding process, it was possible to define the best condition of nitriding process to hardening of the molybdenum enriched layer. The surfaces of the samples were characterized by Electronic Scanning Microscopy (SEM). The microstructural characterizations of the enriched and nitrided layers were done by optical microscopy (OM) and SEM and the phases present by X-ray (XRD) diffraction. Tests of hardness were done to assess the properties of layers obtained. The results show that there is a significant increase in the hardness of the nitrided molybdenum enriched surface layer. The presence of Mo in the surface of the samples leads to the formation of microstructures with different morphologies dependents on temperature and nitrogen content used in the nitriding process. It was not possible to identify the formation of molybdenum nitrides phases (MoN) or mixed nitrides (Fe-Mo-N) in the analysis of XRD for the nitrided enriched samples by plasma. In spit of this, it is believed that they are present, due to the increase in the hardness nitrided enriched layer. Samples of unalloyed Mo were also nitrided under the same conditions in order to compare and to verify the formation of MoN and to evaluate the behavior of the microhardness profile. This study showed that nitriding of sintered metals and superficially molybdenum enriched, improves the hardness of the nitrided layer
Decay of /sup 99/Mo
No full textRelative intensities for K x-rays and gamma rays emanating from /sup 99/Mo in equilibrium with its /sup 99/Tc* daughter have been measured using several Ge photon detectors. Combining these intensities with an evaluated set of electron-conversion coefficients has provided a set of absolute intensities for the observed gamma rays. The absolute intensity for the dominant 140.5-keV gamma ray in /sup 99/Tc was determined to be 90.7 +- 0.6/100 /sup 99/Mo disintegrations for /sup 99/Mo decay in equilibrium with decay of the /sup 99/Tc* daughter
Спектроскопія плазми електродугового розряду з домішками W, Mo, Cr
No full textPlasma of electric arc discharges between composite Cu-W, Cu-Mo and Cu-Cr electrodes in argon flow and
their spectra were studied by optical emission spectroscopy. Since values of oscillator strengths for W I, Mo I and
Cr I presented in various databases are significantly different, selection of spectroscopic data for these elements
(particularly oscillator strength) was expected to be useful for plasma diagnostics. The Boltzmann plot method
was used as a tool for selection of appropriate spectral lines and their spectroscopic data. The main result of the
paper are lists of W I, Mo I and Cr I spectral lines and spectroscopic data, which can be recommended for
purposes of diagnostics of plasma with such metal impurities.Методами оптической эмиссионной спектроскопии исследована плазма электродугового разряда между
композитными Cu-W, Cu-Mo и Cu-Cr электродами. Поскольку значения сил осцилляторов для линий W I,
Mo I и Cr I, представленные в разных литературных источниках, существенно различаются, то считалось
целесообразным провести селекцию спектроскопических констант данных элементов, для чего
использовался метод диаграмм Больцмана. Основными результатами работы являются таблицы
спектральных линий W I, Mo I и Cr I, а также соответствующих спектроскопических данных,
рекомендованных для диагностики плазмы с примесями этих металлов.Методами оптичної емісійної спектроскопії досліджено плазму електродугового розряду між
композитними Cu-W, Cu-Mo та Cu-Cr електродами. Оскільки значення сил осциляторів для ліній W I, Mo I
та Cr I, які наведені у різних літературних джерелах, суттєво відрізняються, то вважалось за доцільне
провести селекцію спектроскопічних констант цих елементів, для чого використано метод діаграм
Больцмана. Основними результатами роботи є таблиці спектральних ліній W I, Mo I та Cr I, а також
відповідні спектроскопічні дані, які рекомендовані для діагностики плазми електродугового розряду з
домішками цих металів
Спектроскопія плазми електродугового розряду з домішками W, Mo, Cr
No full textPlasma of electric arc discharges between composite Cu-W, Cu-Mo and Cu-Cr electrodes in argon flow and
their spectra were studied by optical emission spectroscopy. Since values of oscillator strengths for W I, Mo I and
Cr I presented in various databases are significantly different, selection of spectroscopic data for these elements
(particularly oscillator strength) was expected to be useful for plasma diagnostics. The Boltzmann plot method
was used as a tool for selection of appropriate spectral lines and their spectroscopic data. The main result of the
paper are lists of W I, Mo I and Cr I spectral lines and spectroscopic data, which can be recommended for
purposes of diagnostics of plasma with such metal impurities.Методами оптической эмиссионной спектроскопии исследована плазма электродугового разряда между
композитными Cu-W, Cu-Mo и Cu-Cr электродами. Поскольку значения сил осцилляторов для линий W I,
Mo I и Cr I, представленные в разных литературных источниках, существенно различаются, то считалось
целесообразным провести селекцию спектроскопических констант данных элементов, для чего
использовался метод диаграмм Больцмана. Основными результатами работы являются таблицы
спектральных линий W I, Mo I и Cr I, а также соответствующих спектроскопических данных,
рекомендованных для диагностики плазмы с примесями этих металлов.Методами оптичної емісійної спектроскопії досліджено плазму електродугового розряду між
композитними Cu-W, Cu-Mo та Cu-Cr електродами. Оскільки значення сил осциляторів для ліній W I, Mo I
та Cr I, які наведені у різних літературних джерелах, суттєво відрізняються, то вважалось за доцільне
провести селекцію спектроскопічних констант цих елементів, для чого використано метод діаграм
Больцмана. Основними результатами роботи є таблиці спектральних ліній W I, Mo I та Cr I, а також
відповідні спектроскопічні дані, які рекомендовані для діагностики плазми електродугового розряду з
домішками цих металів
Water Level Monitoring in the Karnali River, Nepal: Evaluating Satellite SAR Altimetry Techniques through Field Observations
No full textRivers play a crucial role in shaping landscapes and supporting ecosystems. This is demonstrated by the tiger habitats in and around Bardia National Park in West-Nepal, which rely on the Karnali River. This study contributes to a larger effort aimed at sustainably managing these tiger habitats. Monitoring the rivers in this remote area is challenging, suggesting a role for remote sensing. An exploration is presented regarding the potential of satellite synthetic aperture radar altimetry (sat-SARA) for monitoring rivers situated in diverse topographic landscapes. Focusing on the Bheri, Karnali, and Geruwa Rivers, the applicability of sat-SARA techniques for water level monitoring, multiple channel identification, and channel activation detection was evaluated. For deriving water surface heights from sat-SARA data, an empirical Gaussian retracker was used. The findings are promising. While resulting water level variations align with field observations, complementary in-situ measurements are imperative for a comprehensive evaluation. Additionally, the study reveals the potential for identifying multiple channels from sat-SARA return signals, extending to channel classification and detecting channel activation. Leveraging the labour-intensive nature of sat-SARA data processing, the technique holds great promise for monitoring rivers in remote and difficult-to-access landscapes. Therewith, this study contributes to advancing the understanding of the hydrodynamics of the Lower Karnali River and opens doors for sat-SARA applications for river monitoring in challenging terrains.Save the Tigers, Save the Grasslands, Save the Water!Water Managemen
Caracterização estrutural e microestrutural de camadas obtidas em ferro puro sinterizado, enriquecido superficialmente e nitretado por plasma
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2013.Uma nova técnica para sinterizar materiais a partir do pó foi desenvolvida pelo LabMat-UFSC. Essa técnica baseia-se na tecnologia de plasma DC utilizando descarga luminescente anormal para a sinterização de compactados obtidos via MP (Metalurgia do Pó). Na sinterização a plasma, com o posicionamento das amostras no ânodo (configuração ânodo- cátodo confinado), é possível enriquecer a superfície das mesmas com elementos de liga metálicos, provenientes da composição do cátodo. Esta possibilidade de modificar as características superficiais dos componentes obtidos por MP é fundamental para várias aplicações e desempenho desses componentes. Por exemplo, aumentar a resistência ao desgaste. Neste trabalho, amostras de ferro puro, sinterizadas e enriquecidas superficialmente com molibdênio via plasma DC, foram submetidas ao tratamento termoquímico de nitretação por plasma, modificando as propriedades mecânicas na região superficial das amostras resultando em uma região superficial mais endurecida. A presença de Mo na superfície da amostra leva a formação de microestruturas com diferentes morfologias dependentes da temperatura e do teor de nitrogênio no processo de nitretação. A análise microestrutural detalhada das camadas formadas foi realizada através de MO (Microscopia Ótica), MEV (Microscopia Eletrônica de Varredura), DRX (Difratometria de Raios-X). As distintas características morfológicas e composição das camadas desenvolvidas nas amostras enriquecidas e nitretadas foi especialmente analisada e discutida com base em resultados obtidos via MET (Microscopia Eletrônica de Transmissão). A formação de nitretos mistos ??-(Fe,Mo)4N e e-(Fe,Mo)2-3N, na camada composta das amostras enriquecidas e nitretadas em alto potencial de nitrogênio foi discutido, levando a proposição de um modelo para seu desenvolvimento. Camadas superficiais obtidas após a nitretação sem precipitados visíveis por MO e MEV, mas com elevados valores de dureza, foram analisadas com base na teoria de nucleação e precipitação. Os perfis de microdureza obtidos confirmaram as alterações nas propriedades mecânicas. Este trabalho mostrou que a nitretação de compactados ferrosos enriquecidos superficialmente com Mo, melhora a dureza da camada nitretada, mesmo quando não ocorre a precipitação da camada composta. Valores de microdureza mais elevados foram obtidos nas amostras enriquecidas e nitretadas quando comparado as amostras de Fe puro nitretadas. <br
An integrated operational system to reduce O&M cost of offshore wind farms
No full textOffshore wind is a relatively new industry and it is generally more expensive to generate electricity than many alternative renewable sources. Operation & Maintenance (O&M) makes up a significant part of the overall cost of running Offshore Wind Turbines (OWT). Since the O&M associated responsibility is shared among turbine manufacturers, wind farm operators and the offshore transmission owners, this has inevitably led to lack of information, duplication of effort and less efficiency. Big data analytics is one great technique that will drive future growth. In this paper, an integrated operational system of offshore wind farm is proposed deploying big data analytics. Firstly, the current state of the O&M of offshore wind farm and the big data analytics are introduced. Afterwards, a predictive maintenance model and a maintenance implementation model are proposed, and an integrated operational system is developed incorporating those two models in order to optimize maintenance planning and implementation. Finally, the possible contribution of such a system to a more effective O&M of offshore wind farm is discussed.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
An introduction to management science: quantitative approaches to decision making
No full textRetaining the accessible application-driven approach for which An Introduction to Management Science is highly regarded, adapting author Mik Wisniewski has carefully reworked the existing US textbook to benefit students across the UK, Europe, Middle East and Africa. Packed with diverse realistic examples from Scotland to Saudi Arabia, the landmark text from the ASW team is now available in a truly internationalised version for students studying Management Science and Operations Research at postgraduate and undergraduate level
National ethnology: the contribution of professor Novogrodsky T.A. to the study of the food traditions of Belarusians
No full textThe article is devoted to the analysis of the contribution to the study of the eating traditions of the Belarusians by the ethnologist, professor Novogrodsky T.A. The author attempts to study and systematize scientist's works, describe used sources and scientific methods, determine the level of topic under consideration inquiry.У артыкуле аналізуецца ўклад айчыннага этнолага, прафесара Навагродскага Т.А. у вывучэнне традыцый харчавання беларусаў. Аўтарам разгледжаны і сістэматызаваны працы вучонага, ахарактарызавана база выкарыстаных ім крыніц і метадаў, вызначана ступень вывучанасці навукоўцам дадзенай часткі матэрыяльнай культуры беларусаў
PENGARUH KEMANDIRIAN BELAJAR SISWA DAN LINGKUNGAN SEKOLAH TERHADAP PRESTASI BELAJAR EKONOMI SISWA KELAS XI IS SMA NEGERI 1 BARUS TAHUN AJARAN 2019/2020
No full textMasalah dalam penelitian ini adalah kemandirian belajar siswa dan kondisi lingkungan sekolah siswa yang kurang mendukung prestasi belajar ekonomi siswa Kelas XI IIS SMA Negeri 1 Barus T.A.2019/2020. Tujuan dalam penelitian ini adalah untuk mengetahui pengaruh kemandirian belajar siswa dan kondisi lingkungan sekolah terhadap prestasi belajar ekonomi siswa Kelas XI IIS SMA Negeri 1 Barus T.A. 2019/2020.
Populasi dalam penelitian ini adalah siswa Kelas XI IIS SMA Negeri 1 barus T.A. 2019/2020 yang berjumlah 105 siswa kemudian diambil sampel dengan menggunakan teknik Random Sampling sebanyak 83 siswa. Metode pengumpulan data adalah observasi, wawancara, kuesioner dan dokumentasi. Teknik analisis data yang digunakan yaitu regresi linear berganda, koefisien determinasi (R2), uji “t” secara parsial dan uji “F” secara simultan.
Berdasarkan analisis data dengan menggunakan program SPSS versi 20 diperoleh persamaan regresi linier berganda Y= 19,809 + 0,516 X1 + 0,331 X2 Selanjutnya variabel motivasi belajar (X1) memiliki pengaruh yang positif dan signifikan secara parsial terhadap prestasi belajar siswa dengan nilai thitung>ttabel (780>1,998) dan nilai signifikansi (0,000ttabel (3,065>1,989 ) serta nilai Sig 0,000 lebih kecil dari nilai α (0,0003 < 0,05).
Dengan demikian dapat disimpulkan bahwa terdapat pengaruh positif dan signifikan kemandirian belajar dan Lingkungan sekolah siswa berpengaruh terhadap prestasi belajar ekonomi siswa Kelas XI IIS SMA Negeri 1 Barus T.A. 2019/2020
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