1,720,967 research outputs found
Fatigue reduction in floating offshore wind turbines using tuned mass dampers - A modelling approach in the frequency domain
No full textThis study focuses on the fatigue behaviour of a semi-submersible floating offshore wind turbine.
Using Lagrange’s equation of motion, a simplified model of the system is set up in the frequency
domain, taking into account wind and ocean wave external forces. The frequency domain’s faster
computation times allow to test the model for a wider range of environmental conditions and
subsequently optimise a passive control system over a larger range of parameters.
To operate in the frequency domain, linearisation methods are applied to some forces. If the ensuing
results are not accurate enough, frequency transformations from time-domain outputs are taken
from the literature to correctly represent highly non-linear forces.
Based on the dynamic model results, an analysis of the fatigue loads at the tower base is obtained
from the differential movement between the floating platform and the tower. The frequencies
contributing the most to fatigue are identified, taking into account the probability distribution of the
frequency content of the external forces based on local weather data.
Finally, tuned mass dampers (TMD) are used for fatigue reduction in the identified critical
frequency range. The TMDs’ efficiency is measured by the Damage Equivalent Load (DEL) reduction
at the tower base. A parametric study is done to evaluate the optimal characteristics of
the TMDs, including mass, position, damping coefficient, stiffness and total number of dampers.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
An agent-based simulation framework for industrial consumers’ participation in electricity markets
Get PDFSom storforbrugere af el har industriforbrugerne en nøglerolle at spille i tilpasningen af elsystemet til de ændringer, som energiomstillingen kræver. I forbindelse med liberaliserede elmarkeder forbliver industrielle forbrugere dog stort set passive markedsdeltagere. Kompleksiteten og mangfoldigheden af industrielle processer, de strenge produktionsoverholdelseskrav, manglen på domæneekspertise og mere generelt multikriterieperspektivet for beslutningstagning giver industrielleforbrugere lav risikovillighed i implementeringen af strategier for elmarkedsdeltagelse. Værktøjer, der er skræddersyet til industrielle forbrugeres specifikke krav, er derfor nødvendige til at understøtte beslutningstagning på elmarkedet for derved at tilskynde aktiv industriel forbrugerdeltagelse på elmarkederne.Denne forskning adresserer denne udfordring ved at udvikle en justerbar simuleringsramme for egnethedsvurdering af elmarkedsdeltagelse set fra industrielle forbrugeres perspektiv. Rammen bygger på parametriske præfeasibility-undersøgelser,agentbaseret modellering, diskret-jævn simulering, sekventielle budalgoritmer og multi-kriteriebeslutningstagningsmetoder for at give en konsistent forbrugercentreret evalueringstilgang, der kan tilpasses en industriel forbrugers specifikke industrielle processer og elmarkedskontekst, samtidig med at det påkrævede arbejde for modelimplementering minimeres.Evalueringsrammen består af flere evalueringstrin, hvis resultater supplerer hinanden for at give en multidimensionel evaluering af markedsdeltagelsesstrategier. Værktøjer til præfeasibility-evaluering er udviklet til at bortfiltrere uigennemførligedelmarkeder ved hjælp af parametriske analyser baseret på en systematisk parametrisering af den industrielle procesfleksibilitet og de pågældende elmarkedsdomæner. De resterende delmarkeder er modelleret i en discrete event agentbaseret simulering, der repræsenterer tidsafhængige industrielle forbrugerinteraktioner med de forskellige delmarkeder, som udgør elmarkedets økosystem. Sekventielle budalgoritmer implementeres for hvert delmarked baseret på markedsdesign, forbrugerbegrænsninger og markedsprisinformation, der er tilgået gennem agentinteraktioner, hvilket gør det muligt at evaluere og sammenligne egnetheden af forskellige multimarkedsdeltagelsesstrategier på tværs af forskellige markedstyper og over forskellige tidsskalaer. Forskellige strategiers egnethed sammenlignes ved at analysere simuleringsresultaterne for hver strategi ved hjælp af multi-kriteriebeslutningstagningsmetoder. Denne ramme implementeres på tværs af forskellige industrielle processer og forskellige elmarkedskontekster ved hjælp af en matrice af casestudier. På processiden er et power-to-X-elektrolyseanlæg, et kølehus samt belysning i et drivhus inkluderet. Rammetilpasningsevnen evalueres baseret på forskellene i operationelle fleksibilitetsegenskaber for hver proces. På markedssiden er både det danske elmarkedet og det kinesiske elmarked modelleret. Rammetilpasningsevnen evalueres baseret på forskellen i skala, energimix, markedsarkitektur, markedsreformprioriteter og niveau af markedsintervention mellem de to lande.Resultaterne fra eksperimenterneimplementeret i matricen af casestudier afslører betydningen af case- og kontekstspecifikke markedsdeltagelsesstrategier for industrielle forbrugere, da strategiens egnethed varierer meget på tværs af casestudier. Desuden bør der i markedssammenhænge med mere tidsafhængige markedsprisvariationer som i Danmark implementeres adaptive markedsdeltagelsesstrategier, da strategirangeringerne ændrer sig over tid. Resultaterne understreger også vigtigheden af at overveje strategier for deltagelse på flere markeder for industrielle forbrugere med flere kriterier og derved trække på mangfoldigheden af markedstyper, der er tilgængelige for industrielle forbrugere i et markedsøkosystem. Sammenlignet med ufleksible baseline-strategier kan multimarkedsstrategier forbedre ydeevnen af visse kriterier væsentligt, såsom forøgelse af økonomiske besparelser eller nedsættelse af regningsvariabilitet, til gengæld for afvigelse i produktoutput og øget kompleksitet som potentielle omkostninger. Den foretrukne strategiafhængiger væsentligt af den relative betydning af hvert kriterium. I den kinesiske kontekst tillader multimarkedsstrategier overholdelse af minimumskvoter pålagt for forskellige markedstyper, selv om disse ikke er de højest rangerende strategier set fra industrielle forbrugeres perspektiv.Fra et metodologisk perspektiv har denne forskning givet en systematisk og tilpasningsdygtig modellerings- og evalueringstilgang med det formål at tilbyde markedsdeltagelsesegnethedsevalueringer skræddersyet til industrielle forbrugeres behov. Fra perspektivet af industriel forbrugermarkedsintegration har resultaterne opnået fra forskellige casestudier bidraget til en bedre forståelse af vigtigheden af adaptive multi-markedsdeltagelsesstrategier for multi- kriteriemarkedsdeltagere.As large-scale electricity consumers, industrial consumers have a key role to play in adapting the electricity system to the changes required by the energy transition. However, in the context of liberalised electricity markets, industrial consumers largely remain passive market participants. The complexity and diversity of industrial processes, the strict production compliance requirements, the lack of domain expertise, and more generally the multi-criteria decision-making perspective make industrial consumers risk-averse in the implementation of electricity market participation strategies. Electricity market participation decision-making support tools tailored to the specific requirements of industrial consumers are therefore needed to encourage active industrial consumer participation in electricity markets. This research addresses this challenge by developing an adaptable simulation framework for electricity market participation suitability evaluation from the perspective of industrial consumers. The framework builds on parametric prefeasibilitystudies, agent-based modelling, discrete-even simulation, sequential bidding algorithms and multi-criteria decision making methods to provide a consistent consumer-centric evaluation approach adaptable to an industrial consumer’s specific industrial process and electricity market context, while minimising model implementation efforts.The evaluation framework consists of multiple evaluation steps, whose results feed into each other to provide a multi-dimensional evaluation of market participation strategies. Prefeasibility evaluation tools are developed to filter out unfeasiblesubmarkets using parametric analyses based on a systematic parametrisation of the industrial process flexibility and electricity market domains. The remaining submarkets are modelled in a discrete-event agent-based simulation, representing time-dependent industrial consumer interactions with the different submarkets constituting the electricity market ecosystem. Sequential bidding algorithms are implemented for each submarket based on market design, consumer constraints, and market price information accessed through agent interactions, allowing to test and compare the suitability of different multi-market participation strategies across different market types and over different timescales. The suitability of different strategies is compared by analysing the simulation outputs of each strategy using multi-criteria decision making methods.This framework is implemented across different industrial processes and different electricity market contexts using a matrix of case studies. On the process side, a power-to-X electrolyser, a food cooling house, and greenhouse artificial lighting process are included. The framework adaptability is tested by the differences in operational flexibility properties of each process. On the market side, the Danish electricity market and the Chinese electricity market are included. The framework adaptability is tested by the difference in scale, energy mix, market architecture, market reform priorities, and level of market intervention between the two countries. The experiment results implemented in the matrix of case studies reveal the importance of case- and context-specific market participation strategies for industrial consumers, as strategy suitability varies greatly across case studies. Moreover, inmarket contexts with more time-dependent market price variations such as in Denmark, adaptive market participation strategies should be implemented since strategy rankings change over time. Results also underline the importance of considering multi-market participation strategies for multi-criteria industrial consumers, drawing on the diversity of market types available to industrial consumers in a market ecosystem. Compared to baseline inflexible strategies, multi-market strategies can significantly improve the performance of certain criteria such as financial savings or bill variability, at the potential cost of product output deviation and increased complexity. The preferred strategy is highly dependent on the relative importance of each criterion. In the Chinese context, multi-market strategies allow compliance with minimum quotas imposed for different market types, despite not being the highest-ranking strategies from the perspective of industrial consumers. From a methodology perspective, this research has provided a systematic and adaptable modelling and evaluation approach to provide market participation suitability evaluations tailored to the needs of industrial consumers. From the perspective of industrial consumer market integration, the results obtained from the framework implementation in different case studies have contributed to a better understanding of the importance of adaptive multi-market participation strategies for multi-criteria market participants. <br/
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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