30 resultados para Sage Eurowin
Resumo:
Kirjallisuusarvostelu
Resumo:
Kirjallisuusarvostelu
Resumo:
Kirjallisuusarvostelu
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Kirjallisuusarvostelu
Resumo:
Kirjallisuusarvostelu
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State-of-the-art predictions of atmospheric states rely on large-scale numerical models of chaotic systems. This dissertation studies numerical methods for state and parameter estimation in such systems. The motivation comes from weather and climate models and a methodological perspective is adopted. The dissertation comprises three sections: state estimation, parameter estimation and chemical data assimilation with real atmospheric satellite data. In the state estimation part of this dissertation, a new filtering technique based on a combination of ensemble and variational Kalman filtering approaches, is presented, experimented and discussed. This new filter is developed for large-scale Kalman filtering applications. In the parameter estimation part, three different techniques for parameter estimation in chaotic systems are considered. The methods are studied using the parameterized Lorenz 95 system, which is a benchmark model for data assimilation. In addition, a dilemma related to the uniqueness of weather and climate model closure parameters is discussed. In the data-oriented part of this dissertation, data from the Global Ozone Monitoring by Occultation of Stars (GOMOS) satellite instrument are considered and an alternative algorithm to retrieve atmospheric parameters from the measurements is presented. The validation study presents first global comparisons between two unique satellite-borne datasets of vertical profiles of nitrogen trioxide (NO3), retrieved using GOMOS and Stratospheric Aerosol and Gas Experiment III (SAGE III) satellite instruments. The GOMOS NO3 observations are also considered in a chemical state estimation study in order to retrieve stratospheric temperature profiles. The main result of this dissertation is the consideration of likelihood calculations via Kalman filtering outputs. The concept has previously been used together with stochastic differential equations and in time series analysis. In this work, the concept is applied to chaotic dynamical systems and used together with Markov chain Monte Carlo (MCMC) methods for statistical analysis. In particular, this methodology is advocated for use in numerical weather prediction (NWP) and climate model applications. In addition, the concept is shown to be useful in estimating the filter-specific parameters related, e.g., to model error covariance matrix parameters.
Resumo:
Kirjallisuusarvostelu
Resumo:
Kirjallisuusarvostelu
Resumo:
Kirjallisuusarvostelu
Resumo:
Kirjallisuusarvostelu
Resumo:
Tutkielman aiheena on differentiaaliyhtälöt. Tarkoituksena on, että tämä tutkielma toimisi oppikirjana lukion differentiaaliyhtälöiden kurssille. Aluksi kerrataan derivaatan ja integraalin määritelmät. Tämän jälkeen suoritetaan johdatus differentiaaliyhtälöihin. Pääasiasssa perehdytään ensimmäisen kertaluvun yhtälöihin, vaikka useamman kertaluvun yhtälöt mainitaankin teoksessa. Kun differentiaaliyhtälön käsite on määritelty tarkastellaan Sage-ohjelmistoa. Tarkoituksena on, että Sage olisi tukena yhtälöitä ratkaistaessa. Sagen avulla käydään läpi suuntakenttien ja kuvaajien piirtäminen sekä differentiaaliyhtälöiden ratkaiseminen. Differentiaaliyhtälöiden ratkaiseminen aloitetaan separoituvista yhtälöistä, jonka jälkeen siirrytään lineaariseen ja eksaktiin yhtälöön. Näillä metodeilla ratkeaa suuri osa ensimmäisen kertaluvun yhtälöistä. Tämän jälkeen esitellään sopivia muunnoksia, joilla tietyt yhtälötyypit muuttuvat helpommin ratkaistavaan muotoon. Tällaisia tapauksia ovat esimerkiksi Bernoullin ja Riccatin yhtälö. Viimeisessä kappaleessa perehdytään differentiaaliyhtälöiden sovelluksiin. Differentiaaliyhtälöihin päädytään muun muassa fysiikan maailmassa sekä populaatioita tarkkailtaessa.
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The purpose of this study is to improve the potential energy recovery to electric energy in an electrohydraulic forklift system. The initial achieved result for energy saving ratio after structural optimization is 40 %. Component optimization is applied to the tested drive which consists of a DTC controlled electric servo motor directly running a reversible hydraulic pump. According to the study the energy efficiency and the energy recovery from the electro-hydraulic forklift system can be increased by 11 % units. New ideas and directions of further research were obtained during the study.
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The interest towards wood-plastic composites (WPCs) is growing due to growing interest in materials with novel properties, which can replace more traditional materials, such as wood and plastic. The use of recycled materials in manufacture is also a bonus. However, the application ofWPCs has been limited because of their often poor mechanical and barrier properties, which can be improved by incorporation of the reinforcing fillers. Nanosized fillers, having a large surface area, can significantly increase interfacial interactions in the composite on molecular level, leading to materials with new properties. The review summarizes the development trends in the use on nanofillers for WPC design, which were reported in accessible literature during the last decade. The effect of the nanofillers on the mechanical properties, thermal stability, flammability and wettability ofWPC is discussed.
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Biodegradable waste quantities in Lithuania and their potential for the co-treatment in renewable energy and organic fertilizer production are investigated. Two scenarios are formulated to study the differences of the amounts of obtainable energy and fertilizers between different ways of utilization. In the first scenario, only digestion is used, and in the second scenario, other materials than straw are digested, and straw and the solid fraction of sewage sludge digestate are combusted. As a result, the amounts of heat and electricity, as well as the fertilizer amounts in the counties are obtained for both scenarios. Based on this study, the share of renewable energy in Lithuania could be doubled by the co-treatment of different biodegradable materials.