6 research outputs found

    Akusztikai célú anyagok dinamikai tulajdonságainak kutatása = Dynamic properties of materials for sound insulation in buildings

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    A téma középpontjában az akusztikai célú anyagok dinamikai tulajdonságának, illetve viselkedésének kutatása állt. A munkának alapvetően három célja volt. Az egyik cél az volt, hogy új ismereteket szerezzünk az akusztikai célú viszkoelasztikus anyagok dinamikai tulajdonságainak frekvenciafüggéséről, különös tekintettel a nagyfrekvenciás tartományra. Ennek eredményeként arra az új megállapításra jutottunk, hogy a viszkoelasztikus anyagok komplex rugalmassági modulusa nagyfrekvencián nem korlátos növekedést is mutathat. Igazoltuk, hogy ez a nagyfrekvenciás viselkedés összhangban van az általános érvényű Kramers-Krönig diszperziós összefüggésekkel. A kutatás másik céljának megfelelően kidolgoztunk egy új anyagmodellt, amely elsősorban a kis veszteségű anyagok esetében alkalmas a dinamikai tulajdonságok frekvenciafüggésének matematikai leírására. A kutatás harmadik célja a viszkoelasztikus anyagok komplex Poisson száma veszteségi része - az ú.n. Poisson veszteségi tényező értékének a meghatározása volt. Ennek során igazoltuk, hogy a Poisson veszteségi tényező az anyag energiaelnyelő képességén kívül a dinamikai Poisson számtól is függ. Új elméleti összefüggéseket dolgoztunk ki, amelyek lehetővé teszik a Poisson veszteségi tényező meghatározását a nyírási veszteségi tényező és a dinamikai Poisson szám ismeretében. Az összefüggések érvényességét kísérleti adatokkal is igazoltuk. Kutatási eredményeinket a szakma rangos, nemzetközi folyóirataiban, illetve fórumain közöltük. | The dynamic elastic and damping properties of solid materials used for sound and vibration control were in focus of this research work. The research project basically had three aims. The first aim was to investigate the frequency dependences of dynamic properties of viscoelastic materials with special respect to the high frequency range. As a result of investigations it has been found that the complex modulus of elasticity of viscoelastic materials may exhibit unbounded increase at high frequencies. It has been proved that the unbounded high frequency behaviour is in agreement with the Kramers-Kronig dispersion relations. The second aim of the project was to search for material models to describe mathematically the dynamic behaviour of materials used for acoustical purposes. A new model has been developed which is able to describe the dynamic behaviour of solid materials experienced over a certain frequency range. The third research aim was to determine the Poisson's loss factor of solid viscoelastic materials. It has been proved that the magnitude of the Poisson?s loss factor is proportional to the damping in viscoelastic material, moreover it is dependent on the dynamic Poisson?s ratio too. New theoretical relationships have been found which enable one to determine the Poisson?s loss factor from knowledge of the shear loss factor and the dynamic Poisson's ratio. The theoretical results have been verified with experimental data

    Improving Motor Current Control Using Decoupling Technique

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    Abstract-This paper reports advances in the design and development of decoupling method in motor control of electric power assisted steering (EPAS) systems. A motor model for permanent magnet synchronous machines (PMSM) is described. Implementation details, simulation and measurement results are also presented. Keywords-Decoupling, electric power assisted steering (EPAS) systems, field oriented control (FOC), motor control, permanent magnet synchronous machines (PMSM)

    Earth Observation and Geospatial Big Data Management and Engagement of Stakeholders in Hungary to Support the SDGs

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    To support the monitoring and reporting processes during implementation of the Sustainable Development Goals, well-developed, commonly recognized Earth observations and geospatial data, methods, innovations, committed professionals, and strong sustainability policies are necessary. This article informs the readers on the Earth observation and geoinformation developments and innovations, and on the engagement of profession, academy and governance to support implementation of the Sustainable Development Goals in Hungary. Description, analyses and critical assessments are given on the elements selected from Hungarian sustainable-oriented Earth observation and geospatial novelties: (a) Working Group for Sustainable Development mission and national sustainability-policy, (b) international partnerships, domestic activities and achievements, (c) status of the professional education, (d) spatial databases and services to support implementation of the sustainable development, (e) a case study on the internationally recognized soil geoinformation system, (f) national Earth Observation Information System and perspectives of its applications for monitoring the sustainability. The article conclusion strongly advises the Hungarian realization of (a) institutionalization of the Earth observation and geospatial tools and capacity for sustainable development, (b) their use in integration with statistical data, (c) establishment of national spatial information infrastructure and (d) development and spreading of the use of big data

    A Systematic Review of the Efficacy of Interventions to Control Aflatoxins in the Dairy Production Chain—Feed Production and Animal Feeding Interventions

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    The study presents a systematic review of published scientific articles investigating the effects of interventions aiming at aflatoxin reduction at the feed production and animal feeding phases of the milk value chain in order to identify the recent scientific trends and summarize the main findings available in the literature. The review strategy was designed based on the guidance of the systematic review and knowledge synthesis methodology that is applicable in the field of food safety. The Web of Science and EBSCOhost online databases were searched with predefined algorithms. After title and abstract relevance screening and relevance confirmation with full-text screening, 67 studies remained for data extraction, which were included in the review. The most important identified groups of interventions based on their mode of action and place in the technological process are as follows: low-moisture production using preservatives, acidity regulators, adsorbents and various microbiological additives. The results of the listed publications are summarized and compared for all the identified intervention groups. The paper aimed to help feed producers, farmers and relevant stakeholders to get an overview of the most suitable aflatoxin mitigation options, which is extremely important in the near future as climate change will likely be accompanied by elevated mycotoxin levels
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