1,599 research outputs found
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
Full text linkThe 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
Theoretical studies of the historical development of the accounting discipline: a review and evidence
Full text linkMany existing studies of the development of accounting thought have either been atheoretical or have adopted Kuhn's model of scientific growth. The limitations of this 35-year-old model are discussed. Four different general neo-Kuhnian models of scholarly knowledge development are reviewed and compared with reference to an analytical matrix. The models are found to be mutually consistent, with each focusing on a different aspect of development. A composite model is proposed. Based on a hand-crafted database, author co-citation analysis is used to map empirically the entire literature structure of the accounting discipline during two consecutive time periods, 1972–81 and 1982–90. The changing structure of the accounting literature is interpreted using the proposed composite model of scholarly knowledge development
Self-assembly of binary solutions to complex structures
No full textFunding Information: This work was supported by the Academy of Finland under Grant Nos. 309324 (M.S.) and 307806 and 312298 (T.A.-N.). T.A.-N. was also supported by a Technology Industries of Finland Centennial Foundation TT2020 grant. We are grateful for support from the FinnCERES Materials Bioeconomy Ecosystem. Computational resources by CSC IT Centre for Finland and RAMI (RawMatters Finland Infrastructure) are also gratefully acknowledged Publisher Copyright: © 2021 Author(s).Self-assembly in natural and synthetic molecular systems can create complex aggregates or materials whose properties and functionalities rise from their internal structure and molecular arrangement. The key microscopic features that control such assemblies remain poorly understood, nevertheless. Using classical density functional theory, we demonstrate how the intrinsic length scales and their interplay in terms of interspecies molecular interactions can be used to tune soft matter self-assembly. We apply our strategy to two different soft binary mixtures to create guidelines for tuning intermolecular interactions that lead to transitions from a fully miscible, liquid-like uniform state to formation of simple and core-shell aggregates and mixed aggregate structures. Furthermore, we demonstrate how the interspecies interactions and system composition can be used to control concentration gradients of component species within these assemblies. The insight generated by this work contributes toward understanding and controlling soft multi-component self-assembly systems. Additionally, our results aid in understanding complex biological assemblies and their function and provide tools to engineer molecular interactions in order to control polymeric and protein-based materials, pharmaceutical formulations, and nanoparticle assemblies.Peer reviewe
Cross-Domain Co-Author Recommendation Based on Knowledge Graph Clustering
No full textNowadays, due to the growing demand for interdisciplinary research and innovation, different scientific communities pay substantial attention to cross-domain collaboration. However, having only information retrieval technologies in hands might be not enough to find prospective collaborators due to the large volume of stored bibliographic records in scholarly databases and unawareness about emerging cross-disciplinary trends. To address this issue, the endorsement of the cross-disciplinary scientific alliances have been introduced as a new tool for scientific research and technological modernization. In this paper, we use a state-of-art knowledge representation technique named Knowledge Graphs (KGs) and demonstrate how clustering of learned KGs embeddings helps to build a cross-disciplinary co-author recommendation system
Pengaruh Motivasi Belajar terhadap Prestasi Belajar Matematika Siswa Kelas X SMA Negeri 3 Sibolga T.A 2021/2022
Full text linkThis study aims to determine the effect of motivation on mathematics learning achievement of class X students of SMA Negeri 3 Sibolga T.A 2021/2022. The influence of learning motivation on students is very important, because it can improve learning outcomes well through the achievements obtained. The results of observations and observations made by the author show that there are still many students who are still lacking in mathematics learning achievement who are involved in paying attention to the teacher explaining learning directly, focus and self-confidence are still lacking due to a lack of interest in learning mathematics. However, this can be prevented by applying the influence of learning motivation on students, especially in learning mathematics so that they are always active and enthusiastic in undergoing education in order to obtain good learning achievements. The effect of motivation is very important because it can encourage self-awareness to focus on the desired goal
Analysis of the Reduced Wake Effect for Available Wind Power Calculation During Curtailment: Including Validation Experiments
No full textMaster thesis at two faculties: "Civil Engineering and Geosciences" and "Mechanical, Maritime and Materials Engineering". Department: Offshore Engineering. With increasing wind power capacity, the impact of wind power on power system operation increases. For a mature integration of large amounts of wind power, controlling wind farm output by temporary curtailment becomes increasingly relevant. Wind farm curtailment provides valuable technical and economic opportunities for balancing the power system. However, quantifying the exact amount of curtailed wind power at the wind farm level is not trivial. This is because curtailment induces a reduction of the wake effects, complicating the determination of the available power in the wind. Understanding the reduced wake effect is important to improve the technical reliability and business case of wind power curtailment, especially for very large offshore wind farms. The purpose of this research is to present and validate an algorithm to determine the available power of a wind farm during curtailment. Current best practices in available power estimation is to sum the individual turbine available power signals. This leads to an overestimation, as the reduced wake effect is not accounted for. In the algorithm developed in this thesis, existing wake models play a key role in quantifying the reduced wake effect. These wake models have been validated first for wind turbine operation without curtailment and then for operation during curtailment. For the latter, curtailment experiments were prepared and executed on the existing nearshore wind farm Westermeerwind, consisting of 48 wind turbines in commercial operation. Based on that, the developed algorithm has been validated for wind turbines in a straight row and for sub-rated wind speeds. In the experiments, the first turbine in the row was curtailed and the reduced wake effect was clearly observed at the second turbine. The reduced wake effect led to a power increase of the second turbine of 45% to 80% of the curtailed power of the first turbine. However, it also led to a power decrease for the third turbine in a range of 5% to 40% of the curtailed power. No noticeable structural changes in power production were observed from the fourth turbine onward. The algorithm was shown to perform well in calculating the available power at the second turbine, with the Jensen wake model delivering the lowest error. For the third turbine, the algorithm did not perform well, due to relatively large errors of the wake models for the third turbine. The Larsen wake model resulted in the lowest error considering the available power of the whole row of turbines. Overall, it is concluded that the algorithm proposed and validated in this thesis delivers a significantly improved estimation of the available power during curtailment. It is recommended to continue study of the proposed algorithm by testing the performance of other wake models, performing more (types of) curtailment experiments and obtaining higher quality wind data.Civil Engineering and GeosciencesHydraulic EngineeringEuropean Wind Energy Maste
Barron Prize Award Nominations
Full text linkThe Gloria Barron Prize for Young Heroes, founded by young adult author T.A. Barron, seeks nominations for its 2006 awards
Morphology of the Mara River: Assessment of the long term morphology and the effect on the Ecological Flow studies
No full textInvestigation after including long term morphological assessments in the Environmental Flow studies. It is the aim of this research to assess the influence of changes in flow regime on the long-term morphology for the Mara river basin, thereby concluding on the significance of these effects for the establishment of the EFAs. Both a long-term assessment and local EFA assessments are undertaken and the results are linked to each other. Analytical and numerical calculations for the long-term 1-dimensional sediment transport analysis were conducted. Four reaches along a portion of the main stream of the Mara River are distinguished in the analysis. First, a reference scenario was established based on current discharges and parameters measured during site visits. Scenarios for future discharge regimes, were derived from the EFR. Three discharge scenarios are considered; Q_EFA, floods build up by the full EFRs, Q_EFA,maintenance , build up by only taking into account the maintenance flows, and the 95 percentile of flow (Q_95), which is the legislative discharge set by the Kenyan government. The results of the analysis include changes in cross sectional averaged bed levels, velocity, and depth over the length of the river. Although the river shows signs of historical erosion, also seen from field observations, the current state of the river is expected to be stable, since the riverbed is controlled by bedrock. The result for the equilibrium sediment transport flux for the alluvial reach of the river was comparable to fluxes in other rivers in Kenya. A first indication for the corresponding characteristic time scale for adaptation of the bed level is 1000 years, which indicates the time it takes for half of the total perturbation of the riverbed to respond. These results support the assumption that the river is stable for the current situation. Comparing the calculated discharge scenarios, the Q_95 and Q_EFA,maintenance scenario show high response of the bed level. The QEF A, f loods shows the same pattern of steepening, but the bed level changes are much less. From this result it can be concluded that it is important to establish an EFR, that also considers the floods, recognising the importance of the morphological assessment of the EFA. This research has taken the first steps in the direction of assessment of river stability in perspective of EFA assessments under data limited circumstances. Unfortunately no further conclusions can be made upon the long-termassessment of the bed level response on a small time scale, therefore improvements of the numerical model are recommended to be made. It is recognised that 2-dimensional processes such as meandering and river widening are important to take into account as well. Moreover, for better understanding and possibly in the future quantification of the morphological processes, it is recommended to build up a data bases including standardized data collected fromfield surveys of the EFA ormonitoringmoments after flood events. This can greatly contribute to the understanding and verification of expected morphological processes in the river.Civil Engineering and GeosciencesWater Managemen
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