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Browsing Fakultet for naturvitenskap og teknologi by Title
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Trulssen, Mads Fremming (Master thesis; Mastergradsoppgave, 04-Dec-2008)[+][-]
Abstract: Lofoten utgjør en opphevet horst i forhold til omkringliggende bassenger og består hovedsakelig av prekambrisk grunnfjell. Tidligere modeller viser at landområdene og sokkelområdene utenfor Lofoten ser ut til å ha hatt en lik ekstensjonshistorie med flere faser av forkastningsbevegelser, innsynkning og oppheving gjennom mesozoikum og kenozoikum. Steile strukturer i berggrunnen danner svakhetssoner der særlig glasial erosjon med botnerosjon har medvirket til dannelsen av det typisk alpine landskapet. Studier av flybilder og bruddplan indikerer både regionale og lokale variasjoner, men har påvist fire dominerende populasjoner av bruddsett; NNØ-SSV, NØ-SV til ØNØ-VSV, VNV-ØSØ og NNV-SSØ. På bakgrunn av ulike kart fremstilt i ArcGIS er det gjort en analyse av orienterte formelemener. Ulike grupper av landformelementer har liknende orientering og kan hovedsakelig korreleres med strukturelementene og deres populasjoner. Forskjeller i landskapet mellom tre provinser ser også til en viss grad ut til å være knyttet til forskjeller i berggrunnens struktur. En modell over roterte forkastningsblokker er fremstilt basert på helning til trendlinjer og kartlagte segmenter av en paleisk overflate. Det antas at de tolkede paleiske overflatene og trendlinjene gjenspeiler eller har vært styrt av en tidligere overflate (av mulig mesozoisk alder), som opprinnelig var tilnærmet horisontal, eller hadde et svakt bølgende landskap. Noen overflater tolkes til å være rotert mot ØSØ, SSØ og SSV, altså vinkelrett på de nevnte populasjonene og gruppene, i episoder fra perm til paleogen. URI: http://hdl.handle.net/10037/1674 File(s) in this item: 1
thesis.pdf (12.42Mb) -
Waage, Malin (Master thesis; Mastergradsoppgave, 15-Nov-2012)[+][-]
Abstract: I study a sand-wave field in ~600 meters water depth on the continental slope offshore Northern Norway. Using multibeam bathymetry data from 2008 and 2011 and P-Cable high-resolution 3D seismic data from 2011, I characterize the field. Sand waves reach up to 6.6 m in height and have wavelengths as large as 140 m. They are mostly asymmetric in shape with the steepest side dipping to the northwest, indicating that current flow over the field is predominantly to the northwest. Larger sand waves (>2 m in height, >100 m wavelength) are observed on topographic highs in the sand-wave field, whereas smaller sand waves (<2 m in height, <100 m wavelength) are present in topographic lows. These topographic lows occur where three ~1-2-km-wide channels cut down the continental slope through the sand-wave field. Seismic data reveal that there are no buried sand waves beneath the seafloor, suggesting that the sand waves are being continually eroded and redeposit at the seabed. Seismic data reveal that the depositional environment over the last ~1 Ma has been largely controlled by debris flows during the glaciations and melt-water plumes and channel formation during the glaciations. High-resolution imaging of the first few meters below the seabed shows that winnowing and associated sand-wave migration is currently the dominant sedimentary process. Data across the study area show that there are no buried sand waves beneath the seafloor. This suggests that the sand waves are being continually eroded and redeposited at the seabed. By measuring the offset of the crest of sand waves in the 2008 and 2011 bathymetry data, I calculate that sand waves migrate from 0 to 3.3 m/yr and have an average migration rate of 1.6 m/yr to the northwest. This migration direction which I directly observe in the bathymetry data is in agreement with the migration direction that I infer from the asymmetry of the sand waves. Integrating these migration rates over the cross section of the sand-wave field, I estimate that sand is transported along the continental slope at a rate of 22.3-118x106 m3/yr. These results provide hard constraints for numerical sand-wave migration models trying to identify the link between ocean currents and sand-wave migration. Furthermore, I show that sand-wave migration has the potential to rapidly move large volumes of sand across the deep water. This movement of sand can complicate drilling and production procedures in the energy industry and may affect slope stability on continental margins around the world. URI: http://hdl.handle.net/10037/4668 File(s) in this item: 2
Errata_MW.pdf (429.4Kb)thesis.pdf (13.12Mb) -
Farstad, Werner; Johansen, Dag; Hartvigsen, Gunnar (Research report; Forskningsrapport, Dec-1994)[+][-]
Abstract: The paper describes the development of a prototype application for access to vital weather information from the Northern Atlantic sea region. The application gives meteorologists access to weather observations measured on sea vessels. Today the available information is very limited. On a daily basis, only 4-5 weather observations in the whole arctic sea-region are conducted. It is therefore suggested to use the available fishing-boat and the coast-guard as a basis for a full scale application. Communication is based on the Inmarsat-C global satellite system. This kind of communication offers limited data bandwidth, currently 600 bit/sec. In addition delays are introduced by the coast/earth-station due to message-queues and protocol-transformations. Based on the services of fered by the Inmarsat-C system, a simple prototype communication mechanism for data communication between terrestrial computers and computers on sea-vessels has been developed. It is, partly due to the nature of the satellite system, based on unreliable multicast of messages. A message may consist of a request which requires a reply (multicast RPC). Test results showed that doing a request and getting a reply takes from 1.5 - 4 minutes. The results depend on the type of message (supported by the Inmarsat-C system) which is used. The sea-vessels send weather observations in set intervals. This means higher availability on weather observations, and again a big step for meteorologists which today have to rely on observation which may be several hours old (if any at all). URI: http://hdl.handle.net/10037/394 File(s) in this item: 1
report.pdf (258.0Kb) -
Skrøvseth, Stein Olav; Godtliebsen, Fred (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: We describe how scale space methods can be used for quantitative analysis of blood glucose concentrations from type 2 diabetes patients. Blood glucose values were recorded voluntarily by the patients over one full year as part of a self-management process, where the timeand frequency of the recordings are decided by the patients. This makes a unique datasetin its extent, though with a large variation in reliability of the recordings. Scale space andfrequency space techniques are suited to reveal important features of unevenly sampled data, and useful for identifying medically relevant features for use both by patients as part of theirself-management process, and provide useful information for physicians. URI: http://hdl.handle.net/10037/3940 File(s) in this item: 1
article.pdf (1.350Mb) -
Rypdal, Kristoffer; Ratynskaia, Svetlana; Kozelov, Boris; Klumov, Boris; Knapek, Christina (Working paper; Arbeidsnotat, 04-Mar-2008)[+][-]
Abstract: The notions of self-organised criticality (SOC) and turbulence are traditionally considered to be applicable to disjoint classes of phenomena. Nevertheless, scale-free burst statistics is a feature shared by turbulent as well as self-organised critical dynamics. It has also been suggested that another shared feature is universal non-gaussian probability density functions (PDFs) of global fluctuations. Here, we elucidate the unifying aspects through analysis of data from a laboratory dusty plasma monolayer. We compare analysis of experimental data with simulations of a two-dimensional (2D) many-body system, of 2D fluid turbulence, and a 2D SOC model, all subject to random forcing at small scales. The scale-free vortex cascade is apparent from structure functions as well as spatio-temporal avalanche analysis, the latter giving similar results for the experimental and all model systems studied. The experiment exhibits global fluctuation statistics consistent with a non-gaussian universal PDF, but the model systems yield this result only in a restricted range of forcing conditions. URI: http://hdl.handle.net/10037/1859 File(s) in this item: 1
article.pdf (914.0Kb) -
Hindberg, Kristian (Doctoral thesis; Doktorgradsavhandling, 23-Mar-2012)[+][-]
Abstract: The number of scale-space statistical algorithms has been greatly increased over the last 15 years. The concept originated from computer vision, introduced in Lindeberg (1994). The seminal paper by Chaudhuri and Marron (1999) brought the scale-space concept into smoothing of curves and kernel density estimation through the SiZer tool. By using all relevant smoothing bandwidths, i.e., the scale part, SiZer allows the user to look for interesting features in the smoothed curves or density estimates simultaneously on all bandwidths. In the years following, a number of classical statistical problems were also included in the family of scale-space algorithms. In this thesis, new scale-space algorithms for four such classical statistical problems are suggested. Paper II presents two closely related problems, addressed with highly similar approaches. Paper I addresses spectral scale-space analysis. Peaks found in the estimated spectral density function of evenly sampled stationary signals are typically of great interest for scientists. A peak found at a given frequency translates to potential (hidden) periodicities in a data set. Therefore, algorithms to determine which spectral peaks that really are significant are important in real-world applications. The presented algorithm uses the infamous periodogram, for reasons explained later. The different Fourier frequencies are the space part of the algorithm, while the scale part is introduced through a smoothing parameter of an assumed prior distribution. By using the Integrated Nested Laplace Approximation, a full posterior distribution can be constructed, from which the needed p-values are found. Unlike Papers I and III, Paper II presents a scale-space approach without introducing a prior distribution. Through two similar algorithms, two different questions are addressed: 1) Can a multivariate data set be considered to originate from some unspecified multivariate Gaussian distribution? 2) Can k multivariate data sets be considered to originate from some unspecified multivariate distribution? The scale part of both algorithms is connected to a weighted summation across neighboring dimensions. The number of dimensions that are summed across is given by the scale parameter. The space parameter is connected to the time or location index of the data series. The algorithms do not need to invert estimated covariance matrices, thereby they can handle the High Dimension Low Sample Size case, where most comparable methods fail. Paper III brings the scale-space concept into long-range dependence and wavelet analysis. The basis of this third paper is the wavelet coefficients resulting from linear filtering of the data with localized wavelet filters of increasing widths. The variance of these coefficients forms the wavelet variance. The space part is connected to the different wavelet filters/scales. As in Paper I, the scale part is connected to the smoothing parameter of the prior distribution. The degree of long-range dependence is fully characterized by the Hurst parameter. This parameter can be estimated through linear regression of the natural logarithm of the wavelet variance. Determining for which scales this regression should be done is not trivial, an issue which the presented algorithm addresses. A time-divided/local wavelet analysis for detecting non-stationarities in the data is also presented in Paper III. Description: The papers of this thesis are not available in Munin:
1. Sigrunn H. Sørbye, Kristian Hindberg, Lena R. Olsen and Håvard Rue: 'Bayesian multiscale feature detection of log-spectral densities', Computational Statistics and Data Analysis (2009), vol. 53, num. 11, pp. 3746-3754. Available at http://dx.doi.org/10.1016/j.csda.2009.03.020
2. Kristian Hindberg, Jan Hannig and Fred Godtliebsen: 'A novel scale-space approach for multinormality testing and the k-sample problem' (manuscript submitted to Computational Statistics and Data Analysis)
3. Kristian Hindberg, Donald B. Percival, Tor Arne Øigård, Stilian A. Stoev, Fred Godtliebsen and Murad S. Taqqu: 'A scale-space wavelet visualization tool for exploring non-stationarities in long-range dependent time series', (manuscript)URI: http://hdl.handle.net/10037/4324 File(s) in this item: 1
thesis.pdf (834.7Kb) -
Kruglikov, Boris; Morozov, Oleg (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: The group of area preserving diffeomorphisms showed importance in the problems of self-dual gravity and integrability theory. We discuss how representations of this infinite-dimensional Lie group can arise in mathematical physics from pure local considerations. Then using Lie algebra extensions and cohomology we derive the second Plebański equation and its geometry. We do not use Kähler or other additional structures but obtain the equation solely from the geometry of area preserving transformations group. We conclude that the Plebański equation is Lie remarkable. URI: http://hdl.handle.net/10037/4965 File(s) in this item: 1
article.pdf (541.2Kb) -
Sæbø, Torstein Olsmo (Doctoral thesis; Doktorgradsavhandling, 19-Nov-2010)[+][-]
Abstract: The topic of this thesis is relative depth estimation using interferometric sidelooking sonar. We give a thorough description of the geometry of interferometric sonar and of time delay estimation techniques. We present a novel solution for the depth estimate using sidelooking sonar, and review the cross-correlation function, the cross-uncertainty function and the phase-differencing technique. We find an elegant solution to co-registration and unwrapping by interpolating the sonar data in ground-range. Two depth estimation techniques are developed: Cross-correlation based sidescan bathymetry and synthetic aperture sonar (SAS) interferometry. We define flank length as a measure of the horizontal resolution in bathymetric maps and find that both sidescan bathymetry and SAS interferometry achieve theoretical resolutions. The vertical precision of our two methods are close to the performance predicted from the measured coherence. We study absolute phase-difference estimation using bandwidth and find a very simple split-bandwidth approach which outperforms a standard 2D phase unwrapper on complicated objects. We also examine advanced filtering of depth maps. Finally, we present pipeline surveying as an example application of interferometric SAS. URI: http://hdl.handle.net/10037/2793 File(s) in this item: 1
thesis.pdf (9.489Mb) -
Johansen, Dag; Halvorsen, Pål; Johansen, Håvard; Riiser, Haakon; Gurrin, Cathal; Olstad, Bjørn; Griwodz, Carsten; Kvalnes, Åge; Hurley, Joseph; Kupka, Tomas (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)[+][-]
Abstract: Locating content in existing video archives is both a time and bandwidth consuming process since users might have to download and manually watch large portions of superfluous videos. In this paper, we present two novel prototypes using an Internet based video composition and streaming system with a keyword-based search interface that collects, converts, analyses, indexes, and ranks video content. At user requests, the system can automatically sequence out portions of single videos or aggregate content from multiple videos to produce a single, personalized video stream on-the-fly. URI: http://hdl.handle.net/10037/3973 File(s) in this item: 1
article.pdf (1.211Mb) -
Hall, Chris; Manson, A.H.; Meek, C.; Hagan, M.; Koshyk, J.; Franke, S.; Fritts, D.; Hocking, W.; Igarashi, K.; MacDougall, J.; Riggin, D.; Vincent, R. (Journal article; Peer reviewed, 2002)[+][-]
Abstract: In an earlier paper (Manson et al., 1999a) tidal data (1990–1997) from six Medium Frequency Radars (MFR) were compared with the Global Scale Wave Model (GSWM, original 1995 version). The radars are located between the equator and high northern latitudes: Christmas Island (2° N), Hawaii (22° N), Urbana (40° N), London (43° N), Saskatoon (52° N) and Tromsø (70° N). Common harmonic analysis was applied, to ensure consistency of amplitudes and phases in the 75–95 km height range. For the diurnal tide, seasonal agreements between observations and model were excellent while for the semi-diurnal tide the seasonal transitions between clear solstitial states were less well captured by the model. Here the data set is increased by the addition of two locations in the Pacific-North American sector: Yamagawa 31° N, and Wakkanai 45° N. The GSWM model has undergone two additional developments (1998, 2000) to include an improved gravity wave (GW) stress parameterization, background winds from UARS systems and monthly tidal forcing for better characterization of seasonal change. The other model, the Canadian Middle Atmosphere Model (CMAM) which is a General Circulation Model, provides internally generated forcing (due to ozone and water vapour) for the tides. The two GSWM versions show distinct differences, with the 2000 version being either closer to, or further away from, the observations than the original 1995 version. CMAM provides results dependent upon the GW parameterization scheme inserted, but one of the schemes provides very useful tides, especially for the semi-diurnal component. URI: http://hdl.handle.net/10037/561 File(s) in this item: 1
article.pdf (4.031Mb) -
Bekele, Meseret Kassa; Rapp, M.; Hartquist, T W; Havnes, Ove (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)[+][-]
Abstract: We report measurements of dust currents obtained with a small probe and a larger probe during the flight of the ECOMA-4 rocket through the summer polar mesosphere. The payload included two small dust probes behind a larger dust probe located centrally at the front. For certain phases of the payload rotation, the current registered by one of the small dust probes was up to 2 times the current measured with the larger probe, even though the effective collection area of the larger probe was 4 times that of the small one. We analyze the phase dependence of the currents and their difference with a model based on the assumption that the small probe was hit by charged dust fragments produced in collisions of mesospheric dust with the payload body. Our results confirm earlier findings that secondary charge production in the collision of a noctilucent cloud/Polar Summer Mesospheric Echo (NLC/PMSE) dust particle with the payload body must be several orders of magnitude larger than might be expected from laboratory studies of collisions of pure ice particles with a variety of clean surfaces. An important consequence is that for some payload configurations, one should not assume that the current measured with a detector used to study mesospheric dust is simply proportional to the number density of ambient dust particles. The higher secondary charge production may be due to the NLC/PMSE particles containing multiple meteoric smoke particles. URI: http://hdl.handle.net/10037/4964 File(s) in this item: 1
article.pdf (1.713Mb) -
Stabell-Kulø, Tage (Research report; Forskningsrapport, Feb-1995)[+][-]
Abstract: To ensure privacy, users of the File Repository Transfer Protocol (Frtp) may require that communication partners are properly authenticated. If one partner wants the communication to be crypted, the other must honor the request. This report describes how authentication and privacy are realized. It is shown, by means of an authentication logic, that the protocol achives its goal in this respect. URI: http://hdl.handle.net/10037/389 File(s) in this item: 1
report.pdf (261.7Kb) -
Hanssen, Øyvind (Lecture; Forelesning; Peer reviewed, 07-Feb-2008)[+][-]
Description: This is the trial lecture at the presentation of the author's doctoral thesis at the University of Tromsø. The thesis is available in Munin at http://hdl.handle.net/10037/1350 URI: http://hdl.handle.net/10037/2840 File(s) in this item: 1
article.pdf (408.2Kb) -
Fredriksen, Lars A. (Master thesis; Mastergradsoppgave, 15-Aug-2007)[+][-]
Abstract: This thesis describes the research of grading security in private Peer-to-Peer (P2P) networks, and ultimately the development of “The Socialized.Net Embedded – Cryptography Version” (Tsnecv). Tsnecv is a revision of “The Socialized.Net Embedded” (Tsne) which is the embedded version of Njål Borch’s doctorate “The Socialized.Net”. Tsne is a P2P file sharing application which builds it private P2P network as an Ad-Hoc or Distributed Transient Network. Tsnecv focuses on applying different levels of security to the network with respect to authentication of peers and access to resources, primarily through the use of public key cryptography and assignment of varying trust to peers that meet in the network. The goal is to establish secure authenticated communications in such a way that peers may be assigned different policies with respect to access of files and resources, and in this way introduce different levels, or rather grade the security and trust of other peers. An exiting feature is the possibility to use a wireless device to perform a search among the files of all your friends’ and friends’ friends, or other people you have passed by, and automatically having your living room media PC stream the live audio. Files are accessed based on user groups. Someone who forms an Ad-Hoc (spontaneous) network with your wlan unit while passing you by, may autonomously assign you a low trust level, and thus probably access to few or no files. Your close friends however, may grant you access to everything but their most private files. An important aspect was attempting a transparent integration between Tsne and the new levels of security and the mechanisms used to obtain them. It was attempted to inconvenience the users as little as possible, while keeping the accessibility of available resources as high as possible for all peers, while still allowing as much control as possible. Not only is it important to be able to grade the security at different levels, but it would be nice if users did not have to stop and ask each other for passwords, keys, secrets or to carry memory sticks in case they meet someone new and interesting. In other words, to keep the autonomy as intact as possible and the resources plentiful while allowing peers to control access to their shared resources. Public (as in asymmetric) key encryption was the choice of tool to achieve authentication of nodes. Web Of Trust was used as a starting point for the exchange of keys, but Tsnecv grades both nodes and networks at different levels of security, so in some cases you may meet someone new and exchange a key autonomously and publicly, but still consider the security of the key and the association of an identity to the key strong enough to securely authenticate a peer at a later time. Keywords: P2P private peer-to-peer trust security access authentication URI: http://hdl.handle.net/10037/1197 File(s) in this item: 2
src.zip (100.5Kb)thesis.pdf (426.4Kb) -
Stabell-Kulø, Tage (Research report; Forskningsrapport, 04-Feb-1997)[+][-]
Abstract: This paper presents the system model for the work on security in the Pasta project. We present the objectives of the security effort, the threats we will consider, and those we will not consider. As such, the paper describes the environment which applications must be prepared to face, and still provide users with the desired degree of privacy. Description: Publisert 15. oktober 1996, revidert 4. februar 1997 / Published Octobre 1996, revised February 1997 URI: http://hdl.handle.net/10037/377 File(s) in this item: 1
report.pdf (84.79Kb) -
Kempf, Philipp (Master thesis; Mastergradsoppgave, May-2011)[+][-]
Abstract: Swath bathymetry, high resolution seismic and core data are analysed to describe the Late Weichselian and Holocene sedimentary processes and palaeoenvironment in Van Keulenfjorden, Spitsbergen. Bottom currents, the bathymetry of the fjord and the distance from sediment sources are the controlling factors for the sediment distribution as indicated by isopach maps. Sandur deltas at the mouth of tributary valleys cause repeated mass-transport along the slopes. Rapid postglacial isostatic uplift reactivated faults of the West Spitsbergen fold and thrust belt, which acted as pathways for thermogenic gas creating pockmarks. The results from this study confirm previous indications that an ice stream drained the Late Weichselian Barents Sea Ice Sheet through Van Keulenfjorden. The deglaciation of the fjord began ~11.2 cal. ka BP with a retreat rate of ~160 m a-1. A hiatus between 10.7 cal. ka BP and 7.0 cal. ka BP in the outer part of the fjord was most likely caused by bottom currents. Following a warm period between 10.7 cal. ka BP and min. 7.0 cal. ka BP increasing IRD content indicates slow but steady cooling. Glacial activity in the Holocene peaked at 2.8 cal. ka BP, resulting in the deposition of morainal banks. Adjacent to these morainal banks two debris flow lobes were deposited. They are interpreted to be the product of two consecutive surges. This contradicts the conclusions of previous investigations, where the upper lobe is interpreted to be from the Little Ice Age. Since 2.8 cal. ka BP the glacial activity was relatively constant. The terminal position of the Nathorstbreen from 2.8 cal. ka BP was reached in the late 19th century. While the work of this study was conducted Nathorstbreen surged and almost reached the front position from 2.8 cal. ka BP again. URI: http://hdl.handle.net/10037/3422 File(s) in this item: 1
thesis.pdf (12.53Mb) -
Evison, Kenneth André (Master thesis; Mastergradsoppgave, 04-Jun-2012)[+][-]
Abstract: Den nedre delen av Breivikeidet er dominert av postglasiale grunnmarine sedimenter. Den glacio-isostatiske hevning av landmassen har gradvis senket erosjonsbasis og ført til blottleggelse av eldre sedimentene der elvene har skåret seg ned i disse. Den nederste delen av de undersøkte avsettingene er tolket som bottomsets med en rik skeletal fauna dominert av muslinger mens snegler og rester av rur og kråkeboller er mindre vanlig. I øverste del av bottomsetlagene samt i nedre og midtre del av foresetlagene er det påvist konkresjoner. Ved petrografiske undersøkelser er det påvist at konkresjonene inneholder både menisk- og hengende sement som viser at karbonatsementeringen har skjedd i den vadose sonen. I tillegg har katodeluminsensmikroskopi av karbonatsementen også vist at denne er ikke lumineserende, og dette er også evidens for utfelling i et oksyderende porevannsmiljø som er typisk for overflatenært meteroisk porevann. Mange av konkresjonene har en avlang form der den lengste aksen står omtrent vinkelrett på dagens elvebredde, og dette tyder på at retningen på grunnvannsgjennomnstrømningen har vært av betydning for den geometriske utforming av disse konkresjonene. URI: http://hdl.handle.net/10037/4202 File(s) in this item: 1
thesis.pdf (12.39Mb) -
Krogh, Hilde (Master thesis; Mastergradsoppgave, 11-Jun-2010)[+][-]
Abstract: Sedimentologiske og stratigrafiske data er innsamlet fra et lakustrint deltakompleks på Tolokonka i NV-Russland. De innsamlede data fra et 4,2 km langt og 30 m høyt elvesnitt har bidratt til en bedre forståelse av glasiasjonshistorien og bredemte sjøer i NV-Russland gjennom weichsel. Basert på sedimentologiske og stratigrafiske data består faciesfordelingen av sandige facies, vekslinger av kryssjiktet sand, heterolittisks sand og en diamikton. Facies er fordelt innenfor enhetene: A,B,C,D1,D2, E, F og G. Enhetene danner grunnlaget for et utviklingsmiljø fra fluvialt til deltaisk som gradvis endres til et glasilakustrint basseng og til slutt et glasialt miljø. Stratigrafiske grenser har dannet grunnlaget for en miljøtolkning av Tolokonka gjennom weichsel. Ut fra tidligere arbeid er det postulert at en bredemt sjø ble demmet opp i Hvitehavsbassenget av Barents- og Karahavisdekket (ca 70-65 ka BP) i weichsel. Glasilakustrine sedimenter på Tolokonka er i denne oppgaven beskrevet og tolket til å være avsetninger fra denne postulerte bredemte Hvitehavsinnsjøen. URI: http://hdl.handle.net/10037/2495 File(s) in this item: 1
thesis.pdf (5.617Mb) -
Shrestha, Krishna Kumar (Master thesis; Mastergradsoppgave, 25-Jun-2012)[+][-]
Abstract: The study area covers the northern sidewall of the Storegga slide located at the southern limit of the Vøring Plateau. The water depth at mid-Norwegian margin varies approximately between 500 and 1500m. The mid-Norwegian margin area has been known to be prone for submarine sliding and is therefore a key location for studying morphological features to improve our understanding of slide mechanisms. The master thesis aims to investigate fluid migration into the Naust formation from deeper reservoirs and its potential role in slope failure. The 3-D seismic dataset GH01 allowed mapping and visualizing of three slides at the northern sidewall of the Storegga slide. Fluid migration from deeper sources through polygonal and extensional faults and acoustic pipes, gives rise to fluid accumulations under impermeable glacigenic debris flow deposits within Naust formations. The role of fluid flow for slope failures is difficult to decipher. Acoustic pipes north of northern sidewall of the Storegga slide indicate focused fluid flow and a possible active fluid migration system. The layer-bound polygonal faults within Brygge and Kai formations and their extension to the lower Naust formation may be caused by rapid loading adding to the fluid migration pathways to the Naust formation. Thus migrated fluids have been documented to accumulate within the slide prone Naust formations. The three slides identified at the northern flank of the Storegga slide have their basal surface on the marine clays indicating the slope failure on marine deposits. Fluid flow is not considered solely responsible for slope failures but the presence of faults down to the headwall of each slide does support an important buildup of zones of weakness for fluid migration contributing to slope failure. URI: http://hdl.handle.net/10037/4317 File(s) in this item: 1
thesis.pdf (10.85Mb) -
Milovanov, Alexander V.; Chiaravalloti, Francesco; Zimbardo, Gaetano (Journal article; Tidsskriftartikkel; Peer reviewed, 14-Dec-2004)[+][-]
Abstract: We present the results of a numerical investigation of charged-particle transport across a synthesized magnetic configuration composed of a constant homogeneous background field and a multiscale perturbation component simulating an effect of turbulence on the microscopic particle dynamics. Our main goal is to analyze the dispersion of ideal test particles faced to diverse conditions in the turbulent domain. Depending on the amplitude of the background field and the input test particle velocity, we observe distinct transport regimes ranging from subdiffusion of guiding centers in the limit of Hamiltonian dynamics to random walks on a percolating fractal array and further to nearly diffusive behavior of the mean-square particle displacement versus time. In all cases, we find complex microscopic structure of the particle motion revealing long-time rests and trapping phenomena, sporadically interrupted by the phases of active cross-field propagation reminiscent of Levy-walk statistics. These complex features persist even when the particle dispersion is diffusive. An interpretation of the results obtained is proposed in connection with the fractional kinetics paradigm extending the microscopic properties of transport far beyond the conventional picture of a Brownian random motion. A calculation of the transport exponent for random walks on a fractal lattice is advocated from topological arguments. An intriguing indication of the topological approach is a gap in the transport exponent separating Hamiltonian-like and fractal random walk-like dynamics, supported through the simulation. Description: Dette er forfatternes aksepterte versjon. This is the author’s final accepted manuscript. URI: http://hdl.handle.net/10037/2083 File(s) in this item: 1
article.pdf (412.6Kb)
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