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Hybrid Integrity Verification: Anchoring Off-Chain Data to the Ethereum Blockchain Using IPFS and SQL Storage
Get PDFThe high cost and inefficiency of storing large files directly on public blockchains have driven the development of hybrid architectures that anchor integrity proofs on-chain while maintaining the actual data off-chain. This thesis presents a modular system that records cryptographic hashes and file identifiers on an Ethereum smart contract, while the underlying files are stored in a MySQL database or on IPFS. The implementation is built with Node.js, Hardhat, and Docker and provides REST endpoints for file storage and verification, enabling deterministic integrity checks across both centralized and decentralized storage solutions. The evaluation demonstrates that the system achieves low latency, reliable tamper detection, and relatively low operational cost, confirming that blockchain-anchored integrity is achievable for large files. The thesis further discusses system limitations and outlines potential future enhancements, including support for Merkle batching, migration to layer-2 solutions, and integration of privacy-preserving cryptographic techniques.Masteroppgave i informatikkINF399MAMN-INFMAMN-PRO
Nonlinear sound propagation in fisheries acoustics - comparison between numerical solutions
Get PDFIn this thesis the effectiveness of two numerical solutions of the Khokhlov-Zablotskaya-Kutznetsov (KZK) nonlinear equation have been studied. The two codes were the Bergen code developed by University of Bergen, which operates in the frequency domain, and the Texas code developed by University of Texas at Austin, which operates in the time domain. The purpose of this research was to evaluate how these codes can be used to calculate nonlinearity for broadband echosounders. Key differences in the handling of effects in the KZK equation were analysed to identify the sources of variation between the codes.
The results of the two codes were compared by evaluating the amplitudes of individual harmonic frequencies at varying axial distances. For the Texas code this was achieved by doing a FFT of the signal to convert the time signal to the frequency domain. The Bergen code, being in the frequency domain, directly outputs equivalent amplitudes for harmonic frequencies at requested axial distances.
The largest difference between the two codes was observed when only the effect of diffraction was included in the numerical simulations. This difference appeared to originate from the nearfield. Both codes used different numerical methods in the nearfield, compared to the rest of the simulation, to improve stability and reduce the effect of nonlinearity.
It was also noted that despite using the same nonlinearity factor, the Texas code showed a stronger apparent effect of nonlinearity. This may stem from the nearfield errors that appeared with only diffraction, but also suggests that there are other inconsistencies across the two codes.
With the variables used in the simulations the runtime of the Texas code was significantly longer than the Bergen code, which may limit its practicality for broadband echosounder applications. However, unlike the Bergen code, which is restricted to single or multiple harmonic input frequencies, the Texas code can simulate nonlinearity on a wider range of signals.
In conclusion, the thesis highlights key differences in accuracy, runtime, and handling of nonlinearity between the two codes. These findings provide insights into their suitability for practical applications in broadband echosounders.Masteroppgave i havteknologiHTEK399MAMN-HTEK5MAMN-HTE
Omvendt voldsalarm: En analyse av terskelen for å ilegge elektronisk kontroll etter straffeprosessloven § 222 g
Get PDFMasteroppgaveJUS399MAJUR-2MAJU
Numerical analysis of ship resistance using RANS-CFD methods.
Get PDFReducing greenhouse gas (GHG) emissions and improving energy efficiency in the
maritime industry have become key priorities in the transition toward more sustainable
shipping (UNCTAD, 2024). Since ship resistance is directly linked to fuel consumption,
accurate prediction methods are essential to support the design of more efficient vessels.
Computational Fluid Dynamics (CFD) has become a widely used approach for simulating
ship hydrodynamics. In particular, the Reynolds-Averaged Navier-Stokes (RANS) equations
allow for modelling of turbulent, incompressible flows by solving time-averaged forms of
the Navier-Stokes (NS) equations. This makes them suitable for practical ship resistance
simulations.
This thesis investigates the accuracy of ship resistance predictions using RANS-CFD
simulations performed in STAR-CCM+. The study focuses on model-scale simulations of
the Duisburg Test Case (DTC) hull, with resistance results validated against experimental
data from towing tank tests at SVA Potsdam and MarinLab, as well as numerical simulations
from FineMarine provided by LMG Marin. The FineMarine dataset includes both model- and
full-scale cases, with the hull in fixed and free-motion conditions, whereas the STAR-CCM+
simulations are limited to model scale with the hull fixed in all degrees of freedom.
A mesh sensitivity study is conducted to ensure sufficient resolution in the wake region.
Resistance values from STAR-CCM+ were compared with the reference data at various
Froude numbers. The results show that STAR-CCM+ systematically overestimated total
calm water resistance. In addition, the wake behind the hull remained more energetic and
did not reduce with distance, which may be linked to the sudden speed input and limited
simulation time.
The effect of hull motion was assessed using the FineMarine results, which showed minor
differences between fixed and free conditions at low Froude numbers. The results point to
modelling and numerical factors that influence resistance predictions and emphasise the need
for further refinement of CFD approaches to improve accuracy in practical applications.Masteroppgave i havteknologiHTEK3995MAMN-HTEKMAMN-HTE
Eksperimentell responsanalyse av en lukket sjømerd med rammefortøyning
Get PDFFor å imøtekomme den globale etterspørselen etter matfisk, arbeides det med å utvikle bærekraftige løsninger innen havbruksnæringen i Norge. Dagens konvensjonelle merdløsninger møter utfordringer knyttet til lakselus, sykdom og patogensmitte mellom anlegg. Derimot utvikles semi-lukkede og lukkede merder, som Egget til Ovum AS, der fiskebestanden skjermes fra omgivelsene og bidrar til redusert miljøpåvirkning og en lavere smitterisiko. Samtidig introduserer de innovative konseptene nye utfordringer, spesielt i forbindelse med interne væskebevegelser (sloshing).
Denne masteroppgaven undersøker den hydrodynamiske responsen til en konseptuell, lukket sjømerd med rammefortøyning, med fokus på bølgeinduserte bevegelser, sloshing og virvelinduserte bevegelser (VIM). Analysen baseres på en nedskalert modell, der det gjennomføres eksperimentelle forsøk for å vurdere stabilitet, samt kartlegge egenskaper i ulike frihetsgrader gjennom decay-tester. Videre studeres modellresponsen i regulære og irregulære bølger, som inkluderer effekten av fri væskeoverflate og konsekvenser av linebrudd. I tillegg gjennomføres slepetester for å undersøke hvordan virvelavløsninger påvirker modellen, og hvorvidt dette fører til en resonanspåvirket respons.
Resultatene viser at modellresponsen domineres av rotasjonsbevegelsene stamp og rull, som øker risikoen for sloshing i modellen. Samtidig indikerer resultatene en begrenset bevegelse i frihetsgraden hiv. De eksperimentelle bølgetestene gir samsvarende resultater med de numeriske fullskalatestene, både med og uten linebrudd, til tross for at konsekvensene av linebrudd er mer fremtredende i de numeriske testene. Slepetestene avdekker at virvelavløsninger induserer en tverrgående resonansrespons.
Samlet sett viser den konseptuelle sjømerden en betydelig risiko for resonanspåvirket respons rundt bølgefrekvensene og under slep. Dette kan forsterke effekten av sloshing, og øker faren for havari. Den lukkede merdløsningen har et stort potensiale, men det forutsetter en grundig vurdering av utformingen og den dynamiske responsen for å ivareta fiskevelferden. Dette er avgjørende for at havbruksnæringen skal kunne nå målet om fem millioner tonn matfisk innen 2050 på en bærekraftig måte.Masteroppgave i havteknologiHTEK399MAMN-HTEK5MAMN-HTE
LinkedIn som arena for unge voksnes karriereutvikling – en kvalitativ studie av deres profesjonelle selvpresentasjon på plattformen
Get PDFVi befinner oss i en tid der digitale plattformer former og har stor innflytelse på hvordan vi fremstår profesjonelt. Det blir derfor viktig å forstå hvordan unge arbeidstakere bruker LinkedIn til å utføre selvrepresentasjon. Denne masteroppgaven undersøker hvordan unge voksne bruker LinkedIn, hvordan de varierer bruk og aktivitet etter jobbsituasjon, og hva dette har å si for deres profesjonelle fremstilling på plattformen. Gjennom kvalitative, semistrukturerte intervjuer med unge voksne i ulike arbeidssituasjoner og bransjer, analyseres deres refleksjoner og bruk av LinkedIn til å svare på følgende problemstilling: Hvordan anvender unge brukere LinkedIn, hvordan varierer dette etter deres ulike jobbsituasjoner, og hva har denne bruken å si for deres selvrepresentasjon på plattformen?
I denne oppgaven har jeg valgt et todelt teoretisk rammeverk som belyser ulike sider ved bruken av LinkedIn. Den ene delen tar for seg de tekniske og praktiske aspekter ved plattformen, som Gibson (1966) sitt begrep affordanser og Bossetta (2018) sitt verk om digital arkitektur. Den andre delen bygger på sosialpsykologiske og samfunnspsykologiske perspektiver, og inkluderer begreper som Goffman (1959) sin rollespillteori, sosial sammenligning og autentisitet i sosiale medier.
Ved å analysere funnene i lys av det teoretiske rammeverket, fremtrer det noen klare tendenser fra studien. De kvalitative intervjuene viser at de unge voksnes bruk av LinkedIn henger tett sammen med individuell motivasjon og karriereambisjoner. Mens noen unge voksne bruker plattformen for aktiv nettverksbygging, synlighet og potensielle jobbmuligheter, har andre brukere en mer passiv tilnærming for å holde seg faglig oppdatert. Studien viser også at selvrepresentasjonen på LinkedIn ofte fremstår som strategisk. Brukerne tilpasser både innhold og aktivitet for å fremstille et ønsket profesjonelt ytre. Plattformen legger føringer gjennom sine funksjoner, affordanser og digitale arkitektur, men informantene forholder seg ikke passivt til disse rammene. De unge voksne forhandler aktivt med plattformens strukturer og former egen mening om hvordan de ønsker å bruke LinkedIn, uavhengig av hva de ønsker å oppnå ved å bruke plattformen.Masteroppgave i medier og kommunikasjonMEVI350MASV-MEV
Redskaper for de døde: En studie av jordbruksredskaper, sosial identitet og gravskikk i yngre jernalder på Vestlandet
Get PDFThis thesis investigates agricultural tools found in burial sites from the late Iron Age in Vestland County in western Norway, with particular focus on the regions of Midhordland and Nordhordland. The goal is to understand how these findings can provide insight into social structures, gender roles and mortuary practices between c. AD 550–1050. Agricultural equipment emphasized in this investigation includes sickle, scythe, celt, billhook, ard and plough.
The empirical basis for this investigation is mainly built on registries from the Unimus database, supplemented with earlier work from for instance Per Fett and Jan Petersen. A catalogue of agricultural tools from Midhordland and Nordhordland has been developed and included in this thesis. Through an analysis of grave findings containing agricultural tools from previous studies, literature and museum databases, this investigation examines the function and distribution of these equipment in relation to status, gender and ritual performance. The findings are analysed and contextualised through theories of material culture, memory, and social practice, with particular emphasis on Pierre Bourdieu’s concept of habitus and recent studies into burial archaeology including aspects such as social, collective and cultural memory.
The findings in this study demonstrate that agricultural tools were not only functional objects but also acted as symbolic expressions of ideology and social identity. There are also indications of ritual staging of agricultural equipment as a socially meaningful practice. Graves containing agricultural tools show a gendered division of labour, however the variation in findings may indicate a more complex social understanding, where both genders can be represented equally through symbolic equipment.Arkeologi mastergradsoppgaveARK350MAHF-AR
Self-Diagnosis for Three Redundant Underwater Pressure Sensors
Get PDFThe most common method for data quality control currently relies on visual inspection by domain experts. This thesis aims to develop algorithms to automatically detect four distinct failure modes using data from three redundant pressure sensors. The tests were developed using datasets where known failure modes were labelled by experts. For future datasets, these tests aims to automatically flag such failure modes, reducing the reliance on manual visual inspection. In addition, automatically flagged sensor data based on verifiable thresholds enhances trust in data quality while improving the efficiency of anomaly detection compared to current methods.
The developed modules are physics-informed and compare three redundant pressure sensors, under the assumption that the anomaly being tested is present in only one sensor. The four developed modules are testing for the following failure modes: Module 1: Too slow sensor - comparing the ratio between (three) paired sensors. Module 2: Noisy sensor - compares the confidence intervals for every pressure derivative. Module 3: Sensor with transients - compares the mean and standard deviation before and after the transient occurs. Module 4: Oscillating sensor - performs Fast Fourier Transformation and compares the sum of frequencies. The modules were tested on four different datasets: one dataset contains two failure modes, two datasets contain one failure mode, and the final dataset has no identified errors.
The modules are developed with an associated Graphical User Interface (GUI), allowing the users to modify multiple input parameters and adjust the module's sensitivity. This feature is particularly beneficial for experts aiming to optimise thresholds. Based on testing each module across all datasets, specific recommendations have been suggested for these input variables. The default setting for each module are designed to offer reliable data quality control for both experts and non-experts, adjusted to minimise false positives.Masteroppgave i havteknologiHTEK3995MAMN-HTEKMAMN-HTE
Comparison of Analytical Models for Wind Farm Flows
Get PDFThe global transition to renewable energy has established offshore wind as a possible
resource for achieving climate targets, with the Norwegian government planning to allocate
project areas for 30 GW of offshore wind capacity by 2040 (Norwegian Government,
2024). As development accelerates, strategies for designing and optimizing wind farms
become increasingly important for ensuring economic viability. One important aspect is
minimizing wake-induced power losses, which requires wake modeling approaches that are
both accurate and computationally efficient. This thesis investigates the performance of
analytical wake models for offshore wind farm optimization through a systematic comparison
of the Ishihara-Qian and TurbOPark models against Large Eddy Simulation reference data.
For this project, a computational framework is developed in Julia to evaluate wake model
performance across increasingly complex scenarios: single turbine wakes, aligned turbine
rows, and wind farm configurations. The impact of the selected superposition method is
also investigated. The study examines both velocity deficit and power predictions, while
investigating the influence of different mathematical superposition methods for combining
overlapping wake effects.
Results demonstrate that model performance varies considerably with configuration type
and measurement reference. The TurbOPark model’s persistent wake structure requires
quadratic superposition to avoid nonphysical predictions. In contrast, the Ishihara-Qian
model performs effectively with linear superposition due to its rapid wake recovery.
Measurement reference frame influences model evaluation, with different models performing
better depending on whether upstream velocity reduction is included in the reference data.
The findings in this thesis suggest that model selection should be based on specific wind farm
characteristics rather than assuming universal model superiority. The results indicate that
the Ishihara-Qian model is more suitable for aligned turbine arrays with significant wake
overlap, while the TurbOPark model shows advantages for wind farms with lateral offset
configurations. This thesis offers a preliminary framework for wake model selection, though
further validation would strengthen these recommendations. For example, the TurbOPark
model’s ability to predict persistent wake effects suggests potential for modeling cluster wake
interactions between neighboring wind farms.Masteroppgave i havteknologiHTEK3995MAMN-HTEKMAMN-HTE
Kriminalisering av deltagelse i terrororganisasjon etter strl. § 136 a sett i sammenheng med EMK art. 8
Get PDFKriminalisering av deltagelse i terrororganisasjon etter strl. § 136 a sett i sammenheng med EMK art. 8, med særlig fokus på passiv detagelse i forbindelse med kvinners rolle i terrororganisasjonen ISILMasteroppgaveJUS399MAJUR-2MAJU