1,031 research outputs found

    Cast segment evaluation

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    Evaluation program to determine feasibility of fabricating segmented rocket engine thrust chambers using low cost, lightweight castings extends state of the art in areas of casting size and complexity, and in ability to provide thin sections and narrow, deep, cooling channels. Related developments are discussed

    A time-of-flight mass spectrometer suitable for ionospheric composition investigations

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    Time-of-flight spectrometer for examining ionospheric ion density in D and E region

    Orbit transfer vehicle advanced expander cycle engine point design study. Volume 2: Study results

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    The design characteristics of the baseline engine configuration of the advanced expander cycle engine are described. Several aspects of engine optimization are considered which directly impact the design of the baseline thrust chamber. Four major areas of the power cycle optimization are emphasized: main turbine arrangement; cycle engine source; high pressure pump design; and boost pump drive

    Linear aerospike engine study

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    Parametric data on split-combustor linear engine propulsion systems are presented for use in mixed-mode single-stage-to-orbit (SSTO) vehicle studies. Preliminary design data for two selected engine systems are included. The split combustor was investigated for mixed-mode operations with oxygen/hydrogen propellants used in the inner combustor in Mode 2, and in conjunction with either oxygen/RP-1, oxygen/RJ-5, O2/CH4, or O2/H2 propellants in the outer combustor for Mode 1. Both gas generator and staged combustion power cycles were analyzed for providing power to the turbopumps of the inner and outer combustors. Numerous cooling circuits and cooling fluids (propellants) were analyzed and hydrogen was selected as the preferred coolant for both combustors and the linear aerospike nozzle. The maximum operating chamber pressure was determined to be limited by the availability of hydrogen coolant pressure drop in the coolant circuit

    Tropical and subtropical actinorhizal plants

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    A maioria dos países tropicais enfrenta dois grandes problemas: o aumento constante da exploração das reservas florestais para extração de madeira ou lenha e a diminuição da fertilidade do solo para produção agrícola. O conceito geral é o de que plantas fixadoras de N2 podem evitar a propalada crise de madeira e alimentos. Juntas com um grande número de leguminosas fixadoras de N2, plantas actinorrízicas podem ter um papel importante na produção de madeira e recuperação de solos. As plantas actinorrízicas compreendem oito famílias de dicotiledôneas, todas elas representadas nos trópicos. Neste trabalho, as mais promissoras plantas actinorrízicas tropicais são brevemente apresentadas e a ênfase é dada principalmente à família Casuarinaceae. Esta família compreende quatro gêneros (Casuarina, Allocasuarina, Gymnostoma e gênero C), com 82 espécies, incluindo muitas árvores que podem produzir madeira de boa qualidade. As estirpes de Frankia que têm sido isoladas das Casuarinaceae crescem lentamente e são capazes de reduzir acetileno in vitro sob ar, o que indica uma capacidade de proteção contra o O2 muito mais eficiente do que no Rhizobium. Apenas as espécies do gênero Casuarina podem ser noduladas pela estirpe ORS 021001, isolada de Casuarina junghuhniana, o que sugere a existência de grupos de inoculação dentro da família Casuarinaceae. A fixação de N2 de Casuarina equisetifolia, crescida em microparcelas de 1 m2, na estação experimental de ORSTM, em Dakar, foi estimada através da comparação do N total em plantas não-inoculadas e plantas inoculadas com a estirpe ORS 021001. Extrapolando para um hectare, a fixação de N2 foi de 131 kg/N em um período de 6,5 meses. Usando o método de equivalência com adubo nitrogenado, a inoculação parece ser equivalente à aplicação de 288 kg de N/ha-1.Most tropical countries face two major problems: increasing overexploitation of wood reserves for timber or fuel wood and diminishing soil fertility for agricultural production. The present consensus is that N2 -fixing plants can help prevent the forthcoming wood and food crisis. Together with the vast group of N2 -fixing Leguminoseae, actinorhizal plants (AP) can play a major role in wood production and land regeneration. AP comprise eight families of dicotyledonous plants all of which are represented in the tropics. In this paper the most promising tropical AP are briefly presented and the emphasis is put mainly on Casuarinaceae. This family forms a group of four genera (Casuarina, Allocasuarina, Gymnostoma and genus C) with 82 species, including many trees that can yield wood of good quality. The Frankia strains that have been isolated from Casuarinaceae grow slowly and are able to reduce acetylene in vitro under air, which indicates that the protection against O2 is much more efficient in Frankia than in rhizobia. Only the species belonging to the Casuarina genus could be nodulated by strain ORS 021001, isolated from Casuarina junghuhniana, suggesting the existence of crossinoculation groups within the family Casuarinaceae. N2 fixation of Casuarina equisetifolia, grown in 1 m2 microplots at the ORSTOM experimental station of Dakar, was estimated by comparing total N in non-inoculated plants and plants inoculated with Frankia strain ORS 021001. Extrapolating to 1 hectare, N2 fixation was 131 kg for a 6.5-month period. Using the N fertilizer equivalence method, inoculation appeared to be equivalent to the application of 288 kg of N fertilizer per hectare

    Enhancing ECG Analysis of Implantable Cardiac Monitor Data: An Efficient Pipeline for Multi-Label Classification

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    Implantable Cardiac Monitor (ICM) devices are demonstrating as of today, the fastest-growing market for implantable cardiac devices. As such, they are becoming increasingly common in patients for measuring heart electrical activity. ICMs constantly monitor and record a patient's heart rhythm and when triggered - send it to a secure server where health care professionals (denote HCPs from here on) can review it. These devices employ a relatively simplistic rule-based algorithm (due to energy consumption constraints) to alert for abnormal heart rhythms. This algorithm is usually parameterized to an over-sensitive mode in order to not miss a case (resulting in relatively high false-positive rate) and this, combined with the device's nature of constantly monitoring the heart rhythm and its growing popularity, results in HCPs having to analyze and diagnose an increasingly growing amount of data. In order to reduce the load on the latter, automated methods for ECG analysis are nowadays becoming a great tool to assist HCPs in their analysis. While state-of-the-art algorithms are data-driven rather than rule-based, training data for ICMs often consist of specific characteristics which make its analysis unique and particularly challenging. This study presents the challenges and solutions in automatically analyzing ICM data and introduces a method for its classification that outperforms existing methods on such data. As such, it could be used in numerous ways such as aiding HCPs in the analysis of ECGs originating from ICMs by e.g. suggesting a rhythm type

    Геофизические исследования скважин для выявления коллекторов и определения их фильтрационно-емкостных свойств на Вынгаяхинском газо-нефтяном месторождении (Тюменская область)

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    Объектом исследования является месторождение Вынгаяхинское. Цель работы – проектирование комплекса геофизических методов исследования скважин с целью изучения пластов- коллекторов Вынгаяхинского месторождения (ЯНАО). В процессе исследования проводились сбор и анализ геофизических материалов для обоснования оптимального комплекса. В результате исследования предложен комплекс ГИС для выявления и исследования нефтенасыщенных коллекторов. Область применения: предназначаемый комплекс ГИС может применяться на любых месторождениях нефти с терригенно-поровым типом коллекторов. Экономическая значимость работы определяется необходимостью исследований для подсчетов запасов.The object of this study is to deposit Vyngayakhinskoye. The purpose of the work - design of geophysical methods for wells to examine plastov- collectors Vyngayakhinskoye deposit (Yamalo-Nenets District). The study carried out collection and analysis of geophysical data to support the optimum combination. The study proposed a set of GIS for the detection and investigation of oil-saturated reservoir. Scope: intended complex GIS can be used on any oil fields with terrigenous pore type reservoirs. The economic significance of the work is determined by the necessity of research for calculation of reserves

    An effective strain of Frankia from Casuarina.

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    . . An effective strain of Frankia from Casuarina sp. Can. J. Bot. 61: A strain of Frankia, designated Cjl-82, from root nodules of a hybrid of Casuarina junghuhniana and C . equisetifolia has been isolated in pure culture. When grown under standard culture conditions, Cj 1-82 exhibited the following characteristics: cushionlike colonies with short, wide hyphae and, in addition to typical sporangia, intercalary elongated sporangialike structures (SLS) which could be disrupted into sporelike units. No vesicles were found. When inoculated into the rhizosphere of C. equisetifolia, Cj 1-82 produced vesicles. Reinfection of seedlings of C. equisetifolia was achieved repeatedly with inocula prepared from a suspension of Cjl-82. Sequences of infection of root hairs were described, Fourteen days after inoculation, nodules were apparent on the roots. Nodules were shown to be effective in nitrogen fixation as assessed by the 2815-2821.
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