Simulations of the Dynamic Load in a Francis Runner based on measurements of Grid Frequency Variations

Ellingsen, Rakel,Storli, Pal-Tore Korean Society for Fluid machinery 2015 International journal of fluid machinery and syste Vol.8 No.2

In the Nordic grid, a trend observed the recent years is the increase in grid frequency variations, which means the frequency is outside the normal range (49.9-50.1 Hz) more often. Variations in the grid frequency leads to changes in the speed of rotation of all the turbines connected to the grid, since the speed of rotation is closely related to the grid frequency for synchronous generators. When the speed of rotation changes, this implies that the net torque acting on the rotating masses are changed, and the material of the turbine runners must withstand these changes in torque. Frequency variations thus leads to torque oscillations in the turbine, which become dynamical loads that the runner must be able to withstand. Several new Francis runners have recently experienced cracks in the runner blades due to fatigue, obviously due to the runner design not taking into account the actual loads on the runner. In this paper, the torque oscillations and dynamic loads due to the variations in grid frequency are simulated in a 1D MATLAB program, and measured grid frequency is used as input to the simulation program. The maximum increase and decrease in the grid frequency over a 440 seconds interval have been investigated, in addition to an extreme event where the frequency decreased far below the normal range within a few seconds. The dynamic loading originating from grid frequency variations is qualitatively found by a constructed variable $T_{stress}$, and for the simulations presented here the variations in $T_{stress}$ are found to be around 3 % of the mean value, which is a relatively small dynamic load. The important thing to remember is that these dynamic loads come in addition to all other dynamic loads, like rotor-stator interaction and draft tube surges, and should be included in the design process, if not found to be negligible.

입양아의 가족 개념에 대한 사회복지사의 믿음

Ingunn Tollisen Ellingsen 한국주관성연구학회 2010 Journal of Human Subjectivity Vol.8 No.1

In Norway, nearly 8,000 children are in receipt of child welfare services. In this study, I present social workers`` beliefs about the meaning of family for children in foster home placement. A total of 21 social workers participated in a Q study in which their thoughts and beliefs were explored. All participants were qualified social workers and had experience of working with out-of-home placements within the Child Welfare Services in Norway. The Q sort consisted of 39 statements selected to represent different facets of the concourse on family meaning/perceptions for children in foster care. The Q sort matrix ranged from -4 to +4. Factor analysis resulted in one single factor. This suggests one prevailing view existed among social workers on what family means for children who are placed in a foster home. 노르웨이에는 아동복지서비스를 받는 아동이 약 8,000명에 이른다. 본 연구는 입양 가정에 있는 어린이가 가족의 의미를 어떻게 가지고 있는가에 대한 사회복지사의 믿음에 관한 것이다. 총 21명의 사회복지사가 Q 연구에 참여하였는데 이들은 모두 노르웨이 아동복지서비스에 소속된 사람으로서 그들의 생각이나 믿음이 탐구되었다. 총 39개의 진술문으로 구성된 Q 표본은 입양중인 아동들의 가족의 의미와 지각 등 통합체의 상의한 측면들을 담고 있다. Q 분포는 -4에서 +4로 구성되어 측정되었는데 Q 요인분석은 단일요인으로 귀결되었다. 이것은 결국 입양 가정에 있는 아동들의 가족 의미에 대한 사회복지사의 생각에는 하나의 지배적인 시각만이 존재한다는 것을 시사해 준다.

Multi-elemental bio-imaging of rat tissue from a study investigating the bioavailability of bismuth from shotgun pellets.

Urgast, Dagmar S,Ellingsen, Dag G,Berlinger, Bal?zs,Eilertsen, Einar,Friisk, Grete,Skaug, Vidar,Thomassen, Yngvar,Beattie, John H,Kwun, In-Sook,Feldmann, J?rg Springer-Verlag 2012 Analytical and bioanalytical chemistry Vol.404 No.1

<P>In recent years, bismuth has been promoted as a 'green element' and is used as a substitute for the toxic lead in ammunition and other applications. However, the bioavailability and toxicity of bismuth is still not very well described. Following a hunting accident with bismuth-containing shots, a bioavailability study of bismuth from metal pellets inoculated into rat limb muscles was carried out. Bismuth could be found in urine and blood of the animals. Bio-imaging using laser ablation ICP-MS of thin sections of the tissue around the metal implant was carried out to find out more about the distribution of the metal diffusing into the tissue. Two laser ablation systems with different ablation cell designs were compared regarding their analytical performance. Low concentrations of bismuth showing a non-symmetrical pattern were detected in the tissue surrounding the metal implant. This was partly an artefact from cutting the thin sections but also bio-mobilisation of the metals of the implant could be seen. An accumulation of zinc around the implant was interpreted as a marker of inflammation. Challenges regarding sample preparation for laser ablation and bio-imaging of samples of diverse composition became apparent during the analysis.</P>

Simulations of the Dynamic Load in a Francis Runner based on measurements of Grid Frequency Variations

Pål-Tore Storli,Rakel Ellingsen 한국유체기계학회 2015 International journal of fluid machinery and syste Vol.8 No.2

In the Nordic grid, a trend observed the recent years is the increase in grid frequency variations, which means the frequency is outside the normal range (49.9-50.1 Hz) more often. Variations in the grid frequency leads to changes in the speed of rotation of all the turbines connected to the grid, since the speed of rotation is closely related to the grid frequency for synchronous generators. When the speed of rotation changes, this implies that the net torque acting on the rotating masses are changed, and the material of the turbine runners must withstand these changes in torque. Frequency variations thus leads to torque oscillations in the turbine, which become dynamical loads that the runner must be able to withstand. Several new Francis runners have recently experienced cracks in the runner blades due to fatigue, obviously due to the runner design not taking into account the actual loads on the runner. In this paper, the torque oscillations and dynamic loads due to the variations in grid frequency are simulated in a 1D MATLAB program, and measured grid frequency is used as input to the simulation program. The maximum increase and decrease in the grid frequency over a 440 seconds interval have been investigated, in addition to an extreme event where the frequency decreased far below the normal range within a few seconds. The dynamic loading originating from grid frequency variations is qualitatively found by a constructed variable Tstress, and for the simulations presented here the variations in Tstress are found to be around 3 % of the mean value, which is a relatively small dynamic load. The important thing to remember is that these dynamic loads come in addition to all other dynamic loads, like rotor-stator interaction and draft tube surges, and should be included in the design process, if not found to be negligible.

Ethnonationalism in post-war Bosnia-Herzegovina and Kosovo The effects of local violence and ethnic composition

Karin Dyrstad,Tanja Ellingsen,Jan Ketil Rød 한국외국어대학교 국제지역연구센터 2015 International Area Studies Review Vol.18 No.1

In this article we examine attitudes of ethnonationalism in two countries that have experienced ethnic civil war: Bosnia-Herzegovina and Kosovo. We analyse the strength of attitudes of ethnonationalism on the individual level, and how ethnonationalism is related to local ethnic settlement patterns and previous experiences of local inter-ethnic violence. We combine data at the municipality level with data from the South-East European Social Survey Program from 2003 and conduct a multilevel analysis for each case. In both cases, ethnonationalism dominates, but it is stronger in Kosovo than in Bosnia-Herzegovina. We find a clear difference between members of local majorities and minorities, but the effect in Bosnia-Herzegovina is the opposite of the effect in Kosovo. In Bosnia-Herzegovina, members of both minority and majority groups tend to be more ethnonationalist the larger their group. Contrary to our initial expectations, people express less ethnonationalism in municipalities that were more severely hit by violence, whereas in Kosovo no effect of local violence can be found. The more recent conflict and less consolidated institutions in Kosovo may help explain these divergent results. Still, the lack of consistent findings makes it hard to infer beyond the two cases examined.

High-mass Starless Clumps in the Inner Galactic Plane: The Sample and Dust Properties

Yuan, Jinghua,Wu, Yuefang,Ellingsen, Simon P.,II, Neal J. Evans,Henkel, Christian,Wang, Ke,Liu, Hong-Li,Liu, Tie,Li, Jin-Zeng,Zavagno, Annie American Astronomical Society 2017 The Astrophysical journal Supplement series Vol.231 No.1

<P>We report a sample of 463 high-mass starless clump (HMSC) candidates within -60 degrees < l < 60 degrees and -1 degrees < b < 1 degrees. This sample has been singled out from 10,861 ATLASGAL clumps. None of these sources are associated with any known star-forming activities collected in SIMBAD and young stellar objects identified using color-based criteria. We also make sure that the HMSC candidates have neither point sources at 24 and 70 mu m. nor strong extended emission at 24 mu m. Most of the identified HMSCs are infrared dark, and some are even dark at 70 mu m. Their distribution shows crowding in Galactic spiral arms and toward the Galactic center and some wellknown star-forming complexes. Many HMSCs are associated with large-scale filaments. Some basic parameters were attained from column density and dust temperature maps constructed via fitting far-infrared and submillimeter continuum data to modified blackbodies. The HMSC candidates have sizes, masses, and densities similar to clumps associated with Class II methanol masers and H. II. regions, suggesting that they will evolve into star-forming clumps. More than 90% of the HMSC candidates have densities above some proposed thresholds for forming high-mass stars. With dust temperatures and luminosity-to-mass ratios significantly lower than that for star-forming sources, the HMSC candidates are externally heated and genuinely at very early stages of high-mass star formation. Twenty sources with equivalent radii r(eq) < 0.15 pc and mass surface densities Sigma > 0.08 g cm(-2) could be possible high-mass starless cores. Further investigations toward these HMSCs would undoubtedly shed light on comprehensively understanding the birth of high-mass stars.</P>

Energy Consumption and Greenhouse Gas Emission of Korean Offshore Fisheries

Lee, Jihoon,Kim, Taeho,Ellingsen, Harald,Hognes, Erik Skontorp,Hwang, Bokyu Springer-Verlag 2018 Journal of Ocean University of China. JOUC / A sub Vol.17 No.3

High-mass Star Formation through Filamentary Collapse and Clump-fed Accretion in G22

Yuan, Jinghua,Li, Jin-Zeng,Wu, Yuefang,Ellingsen, Simon P.,Henkel, Christian,Wang, Ke,Liu, Tie,Liu, Hong-Li,Zavagno, Annie,Ren, Zhiyuan,Huang, Ya-Fang American Astronomical Society 2018 The Astrophysical journal Vol.852 No.1

<P>How mass is accumulated from cloud-scale down to individual stars is a key open question in understanding highmass star formation. Here, we present the mass accumulation process in a hub-filament cloud G22 that is composed of four supercritical filaments. Velocity gradients detected along three filaments indicate that they are collapsing with a total mass infall rate of about 440M(circle dot) Myr(-1), suggesting the hub mass would be doubled in six free-fall times, adding up to similar to 2 Myr. A fraction of the masses in the central clumps C1 and C2 can be accounted for through large-scale filamentary collapse. Ubiquitous blue profiles in HCO+. (3-2) and (CO)-C-13. (3-2) spectra suggest a clump-scale collapse scenario in the most massive and densest clump C1. The estimated infall velocity and mass infall rate are 0.31 km s(-1) and 7.2 x. 10(-4)M(circle dot) yr(-1), respectively. In clump C1, a hot molecular core (SMA1) is revealed by the Submillimeter Array observations and an outflow-driving high-mass protostar is located at the center of SMA1. The mass of the protostar is estimated to be 11-15M(circle dot) and it is still growing with an accretion rate of 7 x. 10(-5)M(circle dot) yr(-1). The coexistent infall in filaments, clump C1, and the central hot core in G22 suggests that pre-assembled mass reservoirs (i.e., high-mass starless cores) may not be required to form high-mass stars. In the course of high-mass star formation, the central protostar, the core, and the clump can simultaneously grow in mass via core-fed/disk accretion, clump-fed accretion, and filamentary/cloud collapse.</P>

Isolation and Characterization of Marine Pigmented Bacteria from Norwegian Coastal Waters and Screening for Carotenoids with UVA-Blue Light Absorbing Properties

Marit H. Stafsnes,Kjell D Josefsen,Trond E. Ellingsen,Geir Kildahl-Andersen,Svein Valla,Per Bruheim 한국미생물학회 2010 The journal of microbiology Vol.48 No.1

Microbial culture collections are important resources for isolation of natural compounds with novel properties. In this study, a culture collection of around 1,500 pigmented heterotrophic bacteria was established. The bacteria were isolated from the sea surface microlayer at different sampling sites along the mid-part of the Norwegian coast. The bacterial isolates produced pigments of various coloration (e.g. golden,yellow, red, pink and orange). Methanol extracts of sixteen isolates were characterized with LC-Diodearray-TOF mass spectrometry analysis. The number of pigments per isolate varied considerably, and a tentative identification of the pigments was performed based on UV-absorbance profile and molecular formula assignation based on the accurate mass determination. The LC-MS analyses revealed that most of the pigments probably were carotenoids. Furthermore, we developed a high throughput LC-MS method for characterization and screening of a larger sub-fraction (300 isolates) of the culture collection. The aim was to screen and identify bacterial isolates producing carotenoids that absorb light in the UVA-Blue light. Six of the bacterial strains were selected for detailed investigation, including 16s rRNA sequencing, preparative HPLC for purification of major carotenoids and subsequent structural elucidation with NMR. Among the identified carotenoids were zeaxanthin, nostoxanthin and sarcinaxanthin, some with novel glycosylation patterns.

Impact of simultaneous placement of implant and block bone graft substitute: an in vivo peri-implant defect model

Minh Khai Le Thieu,Amin Homayouni,Lena Ringsby Hæren,Hanna Tiainen,Anders Verket,Jan Eirik Ellingsen,Hans Jacob Rønold,Johan Caspar Wohlfahrt,Antonio Gonzalez Cantalapiedra,Fernando Maria Guzon Muñoz 한국생체재료학회 2021 생체재료학회지 Vol.25 No.4

Background: Insufficient bone volume around an implant is a common obstacle when dental implant treatment is considered. Limited vertical or horizontal bone dimensions may lead to exposed implant threads following placement or a gap between the bone and implant. This is often addressed by bone augmentation procedures prior to or at the time of implant placement. This study evaluated bone healing when a synthetic TiO2 block scaffold was placed in circumferential peri-implant defects with buccal fenestrations. Methods: The mandibular premolars were extracted and the alveolar bone left to heal for 4 weeks prior to implant placement in six minipigs. Two cylindrical defects were created in each hemi-mandible and were subsequent to implant placement allocated to treatment with either TiO2 scaffold or sham in a split mouth design. After 12 weeks of healing time, the samples were harvested. Microcomputed tomography (MicroCT) was used to investigate defect fill and integrity of the block scaffold. Distances from implant to bone in vertical and horizontal directions, percentage of bone to implant contact and defect fill were analysed by histology. Results: MicroCT analysis demonstrated no differences between the groups for defect fill. Three of twelve scaffolds were partly fractured. At the buccal sites, histomorphometric analysis demonstrated higher bone fraction, higher percentage bone to implant contact and shorter distance from implant top to bone 0.5 mm lateral to implant surface in sham group as compared to the TiO2 group. Conclusions: This study demonstrated less bone formation with the use of TiO2 scaffold block in combination with implant placement in cylindrical defects with buccal bone fenestrations, as compared to sham sites.