Interfacial tension in water at solid surfaces

A model for the formation of cavitation nuclei in liquids has recently been presented with basis in interfacial liquid tension at non-planar solid surfaces of concave form. In the present paper investigations of water-solid interfaces by atomic force microscopy are reported to illuminate experimentally effects of interfacial liquid tension. The results support that such tension occurs and that voids develop at solid-liquid interfaces.Comment: RevTeX, 5 pages including 8 figure

Stop making sense or Regulation at the level of termination in eukaryotic protein synthesis

AbstractAn increasing number of examples of translational regulation at the level of termination has been recently reported in eukaryotes. This paper reviews our present knowledge on this topic and proposes an understanding of these regulations by relating the study of viral gene expression to a comprehensive view of the mechanisms and components of the translational process

EssayCritic: A Computer-Supported English Essay Critiquing System using Latent Semantic Analysis

The talk presents the EssayCritic system and discusses two recent applications (English composition teaching at HKBU and at Norwegian high school). The EssayCritic makes use of Latent Semantic Analysis (LSA) to compute feedback on student essays. LSA is both a theory of text comprehension and a mathematical technique for comparing two segments of text, one input by students and the other collected and stored by domain experts (e.g. teachers). We describe the components of the system and explain the workings of LSA. Then we present findings from the Norway study (recently completed). The studies differ in that the HK trials were organized with one student per computer, whereas in Norway the students were grouped in pairs, reflecting local teaching styles. Preliminary findings reveal distinct modes of writing (writing, feedback, reflection, revision) for both settings and patterns of working in pairs in the other. Based on the findings we develop a conceptual framework for collaborative essay writing that integrates concepts from design theory (e.g. reflection-in-action) and communication theory (e.g. inter-subjectivity, common ground). Our goals are to understand and characterize collaborative essay writing as a design activity and to provide computational support for it.Anders Mørch is an associate professor at InterMedia, University of Oslo, Norway, and an associate member at the Center for E-Transformation Research, Hong Kong Baptist University, Hong Kong. He received a PhD in Informatics from the University of Oslo. His interests are: information and communication technology in education and workplace learning, human-computer interaction, and participatory design. He is a member of the editorial board on Research and Practice in Technology-Enhanced Learning (RPTEL journal). He is a senior researcher in the European Knowledge Practices Laboratory (KP-Lab) project, and he teaches courses and seminars in human-computer interaction (HCI), computer-supported cooperative work (CSCW), and computer supported collaborative learning (CSCL). His homepage is here: http://www.intermedia.uio.no/people/home/andersm/published_or_final_versionCentre for Information Technology in Education, University of Hong Kon

Pedagogical Agent Design for Distributed Collaborative Learning

Anders Morch is an Associate Professor of Informatics at InterMedia, University of Oslo, Norway ( http://www.intermedia.uio.no/english/ ) as well as an adjunct professor at Department of Information Science, University of Bergen. He received a Ph.D. in 1997 from the University of Oslo, an M.S. degree in 1988 from the University of Colorado, Boulder. He has worked 3 years in industry at the NYNEX Science and Technology Center, New York. Morch has been involved in designing, implementing and evaluating agent-based systems (critics) since 1987. His work has been published in conferences and journals in ITS, HCI, CSCW, and CSCL. His research has focused on real world problems: both in academic context (agents for kitchen design) and industrial context (agents for COBOL programming). His current interests include pedagogical agents for collaborative learning environments, learning at the workplace, component-based learning environments, and end-user development environments. Contact Anders Morch, InterMedia, University of Oslo URL: http://www.intermedia.uio.no/Pedagogical agents are software agents that take on the role of facilitator of collaborative learning processes. They can supplement the teacher with time-consuming tasks such as monitoring participation, group interaction, and knowledge building in distributed settings. The general system building strategy we have employed is to integrate software agents in open source, web-based learning environments. One learning environments we have experimented with in some detail is FLE (Future Learning Environment). FLE is built on the progressive inquiry model and inherits features from CSILE and Knowledge Forum. FLE has been field tested in several schools in Scandinavia. We present findings from a field trial with FLE in two 10th grade school classes in Norway for the domain of natural science studies. The findings have provided us with design guidelines for integration of agents into the system and include: 1) A series of attempts that show it is possible to take advantage of statistical information in collaborative learning environments, 2) categories taken from expert performance (scientific discourse) can be useful as scaffold in weakly structured knowledge domains, and 3) demonstration of a pedagogical agent for scaffolding collaboration and knowledge building.published_or_final_versionCentre for Information Technology in Education, University of Hong Kon

Thermomechanical modelling of the creep-fatigue behaviour and damage of Nickel-alloy receiver tubes used in Concentrated Solar Power plants

The receivers in Concentrated Solar Power (CSP) plants of this study are made of vertical panels of metallic tubes in which molten salt flows. The salt is heated by the solar radiation hitting the surface of the tubes and the heat it carries is then used to produce electricity. The daily thermal loading/unloading of the solar receivers causes a combination of high temperature creep and fatigue in the receiver tubes. Additionally, the presence of molten salt inside the tubes can lead to severe corrosion. For this technology to be profitable, the lifetime of the solar receiver should be at least of 25 years. The objective of this thesis is the modelling of the thermomechanical behaviour of receiver tubes made of nickel alloy 230 and the prediction of their lifetime under the conditions encountered in the field of CSP. In a first stage, an extensive experimental campaign was launched to assess the mechanical behaviour of alloy 230 at different temperatures and under various loading conditions. Additionally, a metallographic analysis of part of the tested samples was conducted to understand the micro-scale phenomena responsible for the macroscopic behaviour of alloy 230. In a second stage, based on the results of the experimental campaign and on results found in the scientific literature, a behaviour model based on the Chaboche framework was selected and implemented in the finite-element code Lagamine developed at the University of Liège. A specific formulation was proposed for the temperature-dependence of the model parameters. Consecutively, a damage model was associated to the behaviour model to predict the lifetime of the tubes under fatigue and creep, and the combination of both. This damage model is based on the unified Lemaitre damage model which is compatible with the Chaboche framework. In a third stage, the modelling of corrosion was added, for which a simplified model was created based on limited experimental data from the literature to simulate uniform corrosion. The resulting full model (behaviour, damage, and corrosion) is highly complex and requires long computational times for the precise modelling of the receiver tubes. In this respect, two methods were developed to make calculations faster using simplifying hypotheses. Both methods proved to be efficient for the reduction of computational time, but only one of the methods is really reliable in terms of accuracy of the results. Finally, one receiver tube was modelled using the finite-element model and its lifetime was evaluated for a specific loading case. The results showed that the estimated lifetime exceeded the target of 25 years, and that uniform corrosion did not have a significant impact on the lifetime and behaviour.Les récepteurs des centrales solaires thermiques à concentration de cette étude sont constitués de panneaux de tubes métalliques verticaux dans lesquels circule du sel fondu. Ce sel est réchauffé par le rayonnement solaire concentré sur la surface des tubes, et la chaleur ainsi emmagasinée est ensuite utilisée pour la production d’électricité. Le chargement/déchargement thermique journalier des récepteurs solaires provoque à la fois du fluage à haute température et de la fatigue. Par ailleurs, la présence de sel fondu à l’intérieur des tubes peut créer d’importants problèmes de corrosion. Pour que ce type de technologie soit rentable, on estime qu’une durée de vie minimale de 25 ans est nécessaire pour le récepteur solaire. L’objectif de cette thèse est de modéliser le comportement thermomécanique des tubes de récepteurs solaires en alliage 230 (alliage de nickel) et de prédire leur durée de vie. Dans un premier temps, une campagne expérimentale a été lancée pour étudier le comportement thermomécanique de l’alliage 230 à différentes températures et sous divers chargements. En outre, une analyse métallographique a été menée sur une partie des éprouvettes testées pour comprendre les phénomènes microscopiques responsables du comportement macroscopique de l’alliage. Dans un second temps, à partir des résultats expérimentaux et de résultats de la littérature, un modèle de comportement basé sur la loi constitutive de Chaboche a été choisi et implémenté dans le code éléments finis Lagamine développé à l’université de Liège. Une formulation spécifique a été proposée pour exprimer la dépendance à la température des paramètres du modèle. Ensuite, un modèle d’endommagement a été associé au modèle de comportement pour prédire la durée de vie sous fatigue, fluage, ou une combinaison des deux. Ce modèle est basé sur le modèle unifié de Lemaitre, qui s’intègre facilement à la loi de Chaboche. Dans un troisième temps, un modèle simplifié a été créé pour simuler la corrosion uniforme en se basant sur les données expérimentales disponibles dans la littérature. Le modèle complet (comportement, endommagement, et corrosion) est très complexe et nécessite de longs temps de calcul pour modéliser précisément les tubes de récepteur. Deux méthodes ont donc été mises en place pour réduire les temps de calcul en utilisant des hypothèses simplificatrices. Les deux méthodes ont permis de réduire significativement les temps de calcul, mais une seule des deux s’est avérée vraiment fiable et précise. Enfin, un tube de récepteur a pu être modélisé en utilisant le code élément fini et sa durée de vie a été estimée pour un cas de charge particulier. Les résultats montrent que la durée de vie estimée est supérieure à l’objectif de 25 ans, et que la corrosion uniforme n’a pas d’impact significatif sur la durée de vie, ni sur le comportement mécanique du récepteurSolar PerformSolar GNex

“Together we can move mountains”, about the early beginning in the school and home cooperation, empirical, qualitative research methods

Bacheloroppgave, grunnskolelærerutdanning, 2013Sammendrag: Temaet for denne oppgaven er hjem-skole samarbeidet og «Hvordan få en god start på skole-hjem samarbeidet?». Skole-hjem samarbeidets aktualitet er i stadig større fokus.. Målet for samarbeidet skal være elevenes trivsel, trygghet og vekst(Nordahl, 1997). Men hvordan bør starten på samarbeidet være for å utfylle disse kravene fra lovverket, og hva har forskere og teoretikere funnet? Hilde Lidèn(1997) mener at samarbeidet først og fremst må handle om å definere måter man kan utfylle hverandre på og hva slags innflytelse man skal ha på hverandres praksis. Oppgaven bygger på en empirisk, kvalitativ forskningsmetode fordi den tar sikte på å fange opp meninger og opplevelser som ikke kan tallfestes(Christoffersen & Johannessen, 2012). I kvalitative intervjuer kommer menneskers erfaringer og oppfatninger frem ved deres egne beskrivelser av opplevelser og erfaringer. Informanter ble hentet fra en skole, foresatte, lærere og rektor. Funnene i forskningen tyder på at mange ulike faktorer kan generaliseres, blant annet myndiggjøring av foresatte, foreldrestøtte, relasjoner og informasjonsflyt i samarbeidet.Summary: The topic of this assignment is home and school cooperation. The research question is «How can we get a good start in the school-home cooperation? ». The actuality of school-home cooperation is important. The goals are the students' well-being, security and growt (Nordahl, 1997). How start this cooperation to fill the requirements from the law, and what are the findings from research and theory? Hilde Lidèn(1997) meant that cooperation primarily should be about how the school and home can complement each other, and how much they should influence each other. This assignment comes from empirical, qualitative research methods, because it collects meanings and experiences witch cannot be made into numbers (Christoffersen & Johannessen, 2012). By using qualitative interviews, people explain their experiences by their own words. The data is collected through qualitative interviews from one school, a principal, some few parents in 1th grade and a team of teachers. The finding indicates that several different factors can be transferred to other schools, for example empowerment of parents, parental support, working with relationships between home and school and what and how the information flow between home and school

Economically efficient design of market for system services under the web-of-cells architecture

Significant power sector developments beyond 2020 will require changing our approach towards electricity balancing paradigms and architectures. Presently, new electricity balancing concepts are being developed. Implementation of these in practice will depend on their timeliness, consistency and adaptability to the market. With the purpose of tailoring the concepts to practice, the development of a balancing market is of crucial importance. This article deals with this issue. It aims at developing of a high-level economically efficient market design for the procurement of system balancing products within the Web-of-Cells architecture. Literature and comparative analysis methods are applied to implement the aim. The analysis results show that a more efficient balancing capacity allocation process should be carried out in a competitive way with closer allocation time to real-time, especially with increased penetration of renewable energy sources. Bid time units, the timing of the market, procurement and remuneration schemes as well pricing mechanisms are the most decisive elements of the market. Their respective advantages and disadvantages are analyzed in the article, as well as their analysis is done against the selected assessment criteria. The results of the analysis show that seeking to improve the operational efficiency of the market, the sequential approach to the market organization should be selected and short-term market time units should be chosen. It is expected that price efficiency could be improved by establishing an organized market where standardized system balancing products should be traded. The balance service providers, who own capital expenditures (CAPEX) sensitive production units, should be remunerated both for the availability of balancing capacities and for their utilization. Uniform pricing rule and cascading procurement principal should be applied to improve the utilization efficiency

O Uso da Contabilidade Estratégica nas Organizações: um Modelo de Análise Estratégica para o Departamento de Contabilidade

Using the SWOT analysis this study proposes a methodology to the accounting department to help the recast its accounting strategy and redefining its positioning. It is a theorical and bibliographical study to discuss how an accounting department could internalize strategic business techniques. It is expected that the use of this proposal, combining analysis methods and the questions arising from the internal and external issues, could help to get a satisfactory result to the goals proposed by the department and adapting to the strategic accounting concepts.El objetivo de este estudio es, con el uso de la herramienta de análisis SWOT, proponer una metodología para el departamento de contabilidad que pueda auxiliarle en el diagnóstico y en la formulación de una estrategia y en la redefinición de su posicionamiento en la administración de la empresa. Se trata de un estudio teórico y bibliográfico en el cual se pretende discutir como las técnicas de administración estratégica para el análisis del ambiente pueden ser aplicadas en la contabilidad de una empresa. Se espera que el modelo propuesto, que combina métodos de análisis con las cuestiones elaboradas a partir del análisis de las variables internas y externas, auxilie el alcance satisfactorio de los objetivos propuestos por departamentos de contabilidad comprometidos con el proceso de reposicionamiento y adaptación a los preceptos de la contabilidad estratégica.O objetivo deste estudo é, com o uso da ferramenta de análise SWOT, propor uma metodologia para o departamento de contabilidade que possa auxiliá-lo no diagnóstico e na formulação de uma estratégia e na redefinição de seu posicionamento na administração da empresa. Trata-se de um estudo teórico e bibliográfico no qual se pretende discutir como as técnicas de administração estratégica para a análise do ambiente podem ser aplicadas na contabilidade de uma empresa. Espera-se que o modelo proposto, que combina métodos de análise com as questões elaboradas a partir da análise das variáveis internas e externas, auxilie o alcance satisfatório dos objetivos propostos por departamentos de contabilidade comprometidos com o processo de reposicionamento e adaptação aos preceitos da contabilidade estratégica

Development of Smart Grid Standards in View of Energy System Functionalities

A range of technologies must be developed and deployed for achieving a decarbonised energy system. A smart grid aims to integrate these different technologies into a single, over-arching system that is at the same time both complex and interoperable, which cannot be achieved without standardisation. Moreover, standardisation is a method of transferring research into successful processes and products. Without this, existing conventional energy systems will not change much longer, as it is more difficult to achieve significant market penetration of new technologies and deployment of new functions and applications. It seems that standardisation issues are not sufficiently addressed in scientific publications and are treated as a very specific topic by community of researchers despite the fact that standards may serve as a knowledge base for further research and improvement of emerging technologies and approaches. This paper presents a bird's-eye smart grid standardisation review based on a unique functionality - technology approach developed within Horizon 2020 project PANTERA.acceptedVersio