Hydrodynamics of an oscillating articulated eel-like structure

This study examines the hydrodynamic performance of a highly simplified eel-like structure consisting of three articulated segments with the two aft segments oscillating. A physical model was built and tested to determine the forces developed with the model stationary, to find the self-propulsion speed, and to explore the effect on hydrodynamic performance of different swimming patterns. It was found that hydrodynamic performance increases with increasing oscillation frequency; the highest forces when stationary, and the highest self-propulsion speeds were produced by swimming patterns in which the amplitude in the aft segment is larger than that in the forward segment, and in which the motion of the aft segment lags the forward segment. A simple semi-empirical model based on Morison’s equation was implemented to predict the hydrodynamic forces. This was shown to predict mean thrust well in cases in which the aft segment oscillates in phase with the forward segment, but less reliably when the phase difference between the segments increases. Force time histories are generally not well-predicted using this approach. Nonetheless, self-propulsion speeds are predicted within 30% in all cases examined

An investigation of the hydrodynamic forces on a jointed oscillating eel-like structure

This study is an investigation of the forces developed by a jointed oscillating structure resembling a mechanical eel. The structure consists of rigid segments that oscillate from side to side to facilitate self-propulsion; this study aims to develop a simple numerical method that can be used for the engineering design of such a structure. The project was undertaken as a natural first step towards the design and construction of autonomous underwater vehicles (AUV) based on this concept.Published literature on fishlike propulsion and its mechanical implementation is investigated before a brief examination of the flow field surrounding such a structure is presented. Simple numerical methods, which try to predict the forces from this type of structure are then evaluated before the numerical implementation of some of them are presented.To evaluate the various numeric methods a physical structure was built and tested in a towing tank. The design of this structure is presented along with the physical measurements from it. The structure had two moving segments and a head segment. The structure was tested in three different scenarios:o The two segments moving as one with no forward speedo The two segments moving independently without forward speedo The two segments moving independently with forward speedAs all the numerical methods depend on quasi-empirical force coefficients, theirsolutions cannot be directly compared to the measured values. The force measurements were therefore used to compute these force coefficients. The consistency of these force coefficients can then be seen as a validation of the numerical method. The method that was found to predict the forces best was the Morison Equation with Keulegan-Carpenter number dependent force coefficients (Graham 1980).With the best-fit force coefficients, the Morison Equation was found to be able to predict the thrust from the scenario when the two segments moved together to within 15 % of the measured value. However, in the second scenario with the two segments moving independently, the generated thrust was substantially over-predicted, in some cases by nearly 200 %. The self-propulsion speed was however only over-predicted by about 30 % in the worst cases and in most cases by significantly less.The Morison Equation with Keulegan-Carpenter number dependent force coefficients can therefore be seen to predict the average forces acting on a single segment oscillating structure well. It can also be seen to predict the self-propulsion speed of a two segment oscillating structure quite well and can thus be used for design purposes. This study however shows that the time history of the forces developed by such a structure is not well predicted by the Morison Equation and neither is the thrust developed in the bollard-pull condition for a two-segment structure

«Ikke tenk på at det blir feil – bare fortsett å prøve!» Om sent ankomne ungdommers erfaringer med språk- og fagopplæring i norsk grunnskole og videregående opplæring

Denne masteroppgaven handler om sent ankomne ungdommer i norsk skolekontekst. Den kvalitative intervjuundersøkelsen tok utgangpunkt i en todelt problemstilling som søkte svar på hvilke erfaringer sent ankomne ungdommer har med opplæringen i norsk skole de første årene etter ankomsten og hvilke didaktiske implikasjoner som kan følge av denne innsikten. Formålet med prosjektet var først og fremst didaktisk. Med utgangspunkt i elevperspektivet søkte intervjuundersøkelsen svar på hva som kan bidra til språklæring og mestring av fag når undervisningsspråket er et andrespråk. Mastergradsprosjektet er forankret i et sosialkonstruktivistisk læringssyn. Det teoretiske rammeverket omfatter andrespråkslæring i et sosio-kognitivt og sosiokulturelt perspektiv. Empirien består av to semistrukturerte mini-fokusgruppeintervjuer. Deltakerne hadde tilhørighet i enten ordinært studiespesialiserende løp på videregående skole eller studiespesialiserende løp for minoritetsspråklige elever. Masteroppgaven peker på at sent ankomne ungdommer er en svært heterogen elevgruppe. En rekke individ-relaterte og kontekstuelle variabler spilte inn da deltakerne i undersøkelsen skulle lære seg norsk. Skoleoverganger kan karakteriseres som viktige vendepunkt, hvor identitetsfølelsen er sårbar. Overgangen fra ungdomsskolen til videregående skole bød i varierende grad på utfordringer for de sent ankomne ungdommene i undersøkelsen. Aktiv deltakelse og mestring i opplæringen på videregående skole forutsatte gode strategier hos ungdommene selv, for å overkomme utfordringer med undervisningsspråket. Fremfor alt viste undersøkelsen betydningen av at nyankomne elever får opplæringen innenfor en kontekst som oppleves trygg, og hvor elevene trives sosialt. Trygge, støttende rammer rundt både den første språkinnlæringen, overganger i skolesystemet og fagopplæringen i videregående skole, så ut til å være en nøkkelfaktor for motivasjon og mestring.This master’s thesis is about late-arriving immigrant youth within the Norwegian school context. The qualitative interview study takes as its starting point a twofold primary research question with the purpose of finding out what experiences this group of teenagers have with their education in Norwegian school in the first years after their arrival, and what didactic implications might follow from this insight. The purpose of the study was primarily of a didactic character. Based on a student’s perspective, the study sought answers to what may contribute to language learning and academic achievement when the language of instruction is a second language. The master’s degree project is grounded in a socio-constructivist view of learning. The theoretical framework for the master project is second language acquisition in a socio-cognitive and socio-cultural perspective. The empirical data consists of two semi-structured mini-focusgroup-interviews. The participants belonged to either the regular academic track in upper secondary school or an academic track for minority language students. The master’s thesis points out that late-arriving teens are a highly heterogeneous group of students. Several individual-related and contextual variables came into play when the participants learned the Norwegian language. School transitions can be characterized as important turning points, where the sense of identity is vulnerable. The transition from secondary to upper secondary school offered varying degrees of challenges for the late-arriving teens in the survey. Active participation and mastery in education at upper secondary school required good strategies on the part of the teens themselves, to overcome challenges with the language of instruction. Above all, the study highlighted the importance of providing education to newly arrived students within a context that is perceived as safe, and where the students thrive socially. Safe and supportive environments for initial language acquisition, transitions within the school system, as well as for academic education in upper secondary school appeared to be a key factor for motivation and sense of mastery

A non-invasive study of the effect of three commercial cleaning products on shellac-coated mahogany

The Royal Palace of Norway has a large 19th century wooden furniture collection and most of it is coated with shellac-based varnishes. Since these objects are part of the royal collections, they are still in daily use at the different residences and, therefore, need to be frequently cleaned. In this work, the effect of three cleaning commercial products (Baolin, Centurio, Fulgentin) used at the royal collections on shellac-coated mahogany is investigated for the first time. A non-invasive methodology (portable ER-FTIR spectroscopy and colorimetry) was applied to assess whether the chemical composition and the color of fresh and artificially aged mahogany wood mock-ups coated with shellac were affected by the above-mentioned cleaning products. This study shows that one of them causes changes in the varnished wood, thus potentially affecting the long-term conservation of this furniture collection.This work has been supported by grant TED2021-129299A-I00, funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR

En god leder gjemmer seg ikke – en kvalitativ studie av destruktiv ledelse og dens konsekvenser

Etter to fine år som masterstudenter er vi endelig i mål med utdanningen og kan tre inn i arbeidslivet. Et av målene med denne oppgaven er å vise at arbeidslivet ikke alltid er slik man ser for seg. Masterstudenter er som oftest ivrige og spente etter å komme inn i arbeidslivet, men ikke alle opplever det like gledelig som de forestiller seg. Formålet med oppgaven var å belyse hva destruktiv ledelse er og hvor skadelig det kan være. Vårt hovedfokus var å se på de menneskelige konsekvensene av det. Dette gjorde vi ved å utføre kvalitative intervju med 8 informanter som hadde opplevd destruktiv ledelse i sitt arbeidsliv. Dataene fra intervjuene brukte vi for å forstå og vise fenomenet fra informantenes perspektiv. Vårt mål var å få et nært inntrykk av både hvordan det påvirker de ansatte, men også virksomheten, og å kunne se situasjonen og erfaringene gjennom deres øyne. Dette ønsket vi å gjøre da destruktiv ledelse er et fenomen som koster samfunnet og mennesker dyrt. Tidligere forskning har for det meste vært satt søkelys på god ledelse, og ikke den mørke siden av ledelse som har fått navnet destruktiv ledelse. Da destruktiv ledelse ikke har noe felles akseptert teoretisk rammeverk eller definisjon er det et fenomen som må forskes på enda mer for å utvikle forståelsen av begrepet og dets betydning. Definisjonene som er til stede nå er så ulike og dekker ulike områder som gjør fenomenet vanskelig å måle forekomsten og kostnadene av. Hovedfunnene går ut på at vi ser at destruktiv ledelse påvirker mange både psykisk og fysisk. Funnene viser at destruktiv ledelse ikke er rendyrkede profiler, men en destruktiv leder kan være destruktiv på flere måter. Vi fant tre typiske reaksjoner på destruktiv ledelse: utbrenthet, resignasjon og ansvar. Et interessant funn var at mange beskrev at leder hadde manglene kunnskap, og at det var en årsak til destruktiv ledelse. Flere informanter forteller og om vedvarende symptomer på fysiske og psykiske lidelser. Det var også en forskjell mellom kvinner og menn, der kvinner ofte ble lengre i jobben og fikk flere psykiske og fysiske konsekvenser enn mennene. Dette blir diskutert i kapittel 5, og en konklusjon blir presentert i kapittel 6.After two great years as master's students, we are finally on track with our education and can enter working life. One of the aims of this assignment is to show that working life is not always as you imagine. Master's students are usually eager and excited to enter working life, but not everyone experiences it as happily as they imagine. The purpose of the assignment was to shed light on what destructive leadership is and how harmful it can be. Our main focus was to look at the human consequences of that. We did this by carrying out qualitative interviews with 8 informants who had experienced destructive leadership in their working lives. We used the data from the interviews to understand and show the phenomenon from the perspective of the informants. Our aim was to get a close impression of both how it affects the employees but also the business, and to be able to see the situation and experiences through their eyes. We wanted to do this as destructive leadership is a phenomenon that costs society and people a great deal. Previous research has mostly focused on good leadership, and not the dark side of leadership which has been named destructive leadership. As destructive management has no commonly accepted theoretical framework or definition, it is a phenomenon that needs to be researched even more to develop the understanding of the term and its meaning. The definitions that are present now are so different and cover different areas that the phenomenon is difficult to measure the occurrence and costs of. The main findings in our study are that we see destructive leadership affects many people, both psychologically and physically. The findings show that destructive leadership is not pure profiles, but a destructive leader can be destructive in several ways. We found three typical reactions to destructive leadership: burnout, resignation, and responsibility. An interesting finding was that many described that the manager had a lack of knowledge, and that this was a cause of destructive management. Several informants also talked about persistent symptoms of physical and mental disorders. There was also a difference between women and men, with women often staying longer in the job and suffering more psychological and physical consequences than men. This is discussed in chapter 5, and a conclusion is presented in chapter 6

A study of the Resilience Analysis Grid method and its applicability to the water sector in England and Wales

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.This paper presents an adaptation of the Resilience Analysis Grid (RAG) method framed on the Resilience Engineering theory as a proposal for tackling the lack of organisational resilience metrics in the water sector of England and Wales. The method was adapted to the sector by selecting 16 indicators and the addition of a ‘Resilience Ethos’ section to the grid. Its applicability was tested by analysing the evolution of resilience in Ofwat’s Price Reviews 2009 (PR09), 2014 (PR14) and 2019 (PR19). Key conclusions obtained were that: (I) PR14 acts as a pivot between PR09 and PR19, as it installs a new regulatory approach; (II) the sector has advanced significantly towards greater consideration of resilience and its management in PR19; and, (III) the PRs lack instruments for in‐period performance assessment. The RAG method proved to be simple and flexible to use, delivering clear and straightforward graphical results.Engineering and Physical Sciences Research CouncilNorthumbrian Water LtdUniversity of Exete

Introducción de los interruptores de proximidad inalámbricos

En general, las máquinas suelen estar festoneadas con cables de energía y de datos, que además de ser caros de instalar y mantener son fuente de frecuentes fallos. El interruptor de proximidad sin cables de ABB elimina la necesidad de cableado para los sensores de posición más corrientes

A study of the effect of three commercial cleaning products on shellac-coated mahogany

The Royal House of Norway has a large furniture collection from the 19th century. Most of this historical furniture is coated with shellac, which was frequently used for such a purpose in the same period. Since these objects are part of the royal collection, they are still in daily use at the different residences. The furniture, therefore, needs a more frequent (and, probably, aggressive) cleaning than what is common for museum objects. For this reason, the effect of three different cleaning products used at the royal collections on shellac-coated mahogany was investigated for the first time. A thorough study with non-invasive methods (portable FTIR spectroscopy, colorimetry, glossimetry) was undertaken to investigate whether the chemical composition, the gloss and the colour have been altered after the cleaning of varnished wood with the selected cleaning products. The investigations were done on fresh and aged mahogany wood samples coated with shellac. The results of this study show that one of the cleaning products probably causes chemical changes in the shellac. This study provides information for the ordinary cleaning and subsequent conservation treatments of the above-mentioned collection and aims to create a preliminary non-invasive protocol for investigating varnish-coated wood