Morphometric Relationships as Indicators of Sexual Maturation in Atlantic Salmon (Salmo salar)

This study aimed to identify morphometric relationships in fish that could serve as indicators for status on sexual maturation in Atlantic salmon (Salmo salar). To achieve this, 250 salmon were netted out and individually weighed, measured for fork length, and photographed over six months. Further, the distance between morphometric key points were digitally measured for each individual using the photographs. Gonad weight was measured in order to calculate GSI as a degree of sexual maturation status. The ratios of snout-eye length to head length, snout-eye length to fork length, head length to fork length, body-height-central to fork length, body-height-anal to fork length, anal-caudal-fin to fork length, anal-caudal-fin to body-height-central, body-height-anal to body-height-central, where analyzed. Our results reveal that the snout/head ratio and the snout/fork length ratio are statistically significant indicators of sexual maturation. Specifically, a Generalized Linear Model (GLM) test showed that the snout/head ratio, snout/fork length and head/fork length had a significant relationship with GSI in August and November. The study also unveils complex interactions between growth metrics such as length, weight, condition factor (K), and specific growth rate (SGR) with GSI, indicating that the relationship between growth and sexual maturation undergoes seasonal fluctuations. Mature fish were found to allocate energy differently from immature fish, particularly near the spawning season, confirming a shift from somatic growth to reproductive activities. Our study suggests a multi-metric approach is crucial for a nuanced understanding of salmon physiology. The findings point to specific morphometric ratios as reliable indicators for assessing sexual maturation in salmon, especially during August and November.Masteroppgave i biologiBIO399MAMN-BIOMAMN-HAVS

Proposal and comparison of an eXogenous Kalman Filter and a Particle Filter for use with ROV thruster models

Robust and accurate observer design is a prerequisite for safe and efficient underwater navigation. Especially with today's increased focus on automation and autonomy. In this thesis two model based observer designs for underwater vehicles are proposed and compared. One is based on the eXogenous Kalman Filter (XKF) and the other is based on the Particle Filter (PF). The designs are also compared to the Extended Kalman Filter (EKF) which is one of the standard observers used today. The drawback of the EKF is the lack of global stability due to a destabilising feedback loop providing linearization points. In the XKF this problem is solved by instead providing linearization points from a globally stable auxiliary state estimator . In the proposed XKF design, a Nonlinear passive Observer (NLO) is implemented for this purpose. The PF however uses the mathematical model directly to generate a number of plausible state hypotheses. Only the most plausible hypotheses makes up the final state estimates. Using the model directly, i.e. without linearization, theoretically makes the PF a more accurate observer than the EKF and the XKF. Albeit global stability cannot be proven for the PF either. A simulator was developed in Matlab/Simulink to evaluate and compare the filters. In simulations it was assumed that noisy measurements of thrust were available for use with a mathematical ROV model. In addition, it was assumed that noisy measurements of position and heading were available from other measurement sources. Experimental data were also gathered from physical experiments using a ROV in the NTNU MC-lab. While the proposed observers were designed with the intention of using measured thrust as input, such measurements were not available with the equipment in the MC-lab. Hence, measurements from an Inertial Measurement Unit (IMU) were used as a replacement of the thruster model. As a consequence only the PF was tested using experimental data. Simulations shows that the EKF and XKF performs relatively similar when both filters are given correct initial values. In the case of inaccurate initial values the differences are larger. As expected, the EKF diverges if the initial values are too erroneous, while the XKF is always able to converge. In cases where both filters are able to converge, the XKF has much faster convergence rates. The XKF gives slightly longer computational times, but its great stability properties makes it the preferable filter compared to the EKF. The PF proves to be the most accurate observer, and it has the fastest convergence rates when the initial values are erroneous. Using the PF with experimental data verifies that the implementation suggested in the thesis works as intended also outside the simulator. The big drawback of the PF is however that it uses approximately 20 times longer time than the Kalman filters. In addition the PF may diverge if not tuned properly. Taken everything into consideration the XKF is considered the best observer for autonomous vehicles

Condition Monitoring of Hydroelectric Power Plants

Much research can be found on condition monitoring for many industries. There are, however, very little research on the use of condition monitoring in hydroelectric power plants. A literature search investigates this field, and it is found that support vector machines and neural networks have been successfully used for condition monitoring of known failure modes. Most of the existing research involves methods that require both normal and abnormal data, and need abnormal data for all failure modes that one want to monitor. As most hydroelectric power plants are operating normally for the majority of their lifetime, it is not trivial to sample data from all known failure modes. Anomaly detection is presented as it enables the detection of anomalies in the process data with only normal process data available. Three different methods for anomaly detection are presented, support vector machines, kernel density estimation and long short term neural networks. In addition, different techniques for feature and dimensionality reduction are presented. A data-set containing data from 27 power plants is analyzed, and a reported incident with operational problems for the needles of a Pelton turbine is extracted for analysis. Data from two different plants and three different turbines are included in the analysis to investigate cross plant performance. An artificial error replicating the operational problems for the reported incident is created to verify how early the anomaly detection techniques can detect system degradation. In addition, two Pelton turbine start failures are included in the analysis to verify that the methods correctly detect abnormal system data. All three methods are shown able to detect the operational problems for the Pelton needles. However, the one class support vector machine is shown to be very dependent on the choice of hyperparameters with regards to the training data. Kernel density estimation and long short term recurrent neural network show better performance and are more robust with regards to parameterization and training data. It is also shown that they can detect the early signs of the system degradation that can be seen leading up to the reported incident with the Pelton needles

An Open Database of Free-Surface Gravity Waves for Validation of Numerical Wave Tanks

Masteroppgave i havteknologiHTEK399MAMN-HTEK5MAMN-HTE

Association between work situation and life satisfaction during the COVID-19 pandemic: prospective cohort study in Norway

publishedVersio

Modeling and analysis of electrical system for offshore oil and gas platform

The main objective of power system analysis is to ensure that the electrical power system is modeled in a safe, reliable, and efficient manner. Short-circuit analysis is a power system analysis investigating the maximum and minimum currents during a fault or short-circuit. The power system analysis software PowerFactory by DIgSILENT was used for modeling and analyzing an 11kV offshore oil and gas platform that is powered from shore through an HVDC cable. Short-circuit analysis according to IEC 60909 was conducted for variouscombinations of open and closed bus-ties between the 690V switchboards or the 11kV switchboards under normal operation mode. Maximum and minimum short circuit currents were considered to ensure compliance with switchgear ratings and protective devise coordination. The results display short-circuit currents within defined limits, indicating the electrical network is modeled safely and reliably. For further work, it is recommended to develop the electrical model further by doing analysis for other operation types, like essential and emergency operations, and conducting other power system analyses, for instance, arc flash analysis and load flow

Animal Welfare in the Conduct of Whaling : A Review of the Research and Developments to Improve Animal Welfare in the Minke Whale Hunt in Norway 1981–2005

departmental bulletin pape

A New Penthrite Grenade Compared to the Traditional Black Powder Grenade: Effectiveness in the Alaskan Eskimos' Hunt for Bowhead Whales

The Alaskan Eskimos catch bowhead whales of the protected Bering-Chukchi-Beaufort Sea stock using old-fashioned weapons and grenades filled with black powder. Killing is sometimes a lengthy process, and in some years relatively large numbers of animals are lost. A new grenade containing the explosive penthrite was developed for the Eskimos' traditional weapons and first tested in the bowhead whale hunt in 1988, when eight whales were killed by penthrite grenades. Seven of these were landed, and one dead whale was lost. Five whales died instantaneously or within five minutes. Tissue and organ damage was inspected by post-mortem examination. Although data collected after 1988 are less reliable, the survival times recorded for animals landed up to 1992 were markedly shorter for the penthrite grenade than for the traditional black powder grenade. Median survival times were 62 minutes for whales killed by black powder grenades and 15 minutes for those killed by penthrite grenades; 21% and 45% of the animals, respectively, were recorded as dead within five minutes, and 32% and 19% respectively, were lost. The penthrite grenade is likely to become a highly effective weapon for the bowhead whale hunt, although further modification and testing will be needed before large-scale use. An educational and training programme for all prospective users should also be arranged. The possibility of improving other catch equipment to reduce whale loss should also be considered.Key words: bowhead whale, Balaena mysticetus, Eskimo traditional subsistence hunt, Alaska, hunting method, black powder grenade, penthrite grenadeLes Eskimos de l'Alaska chassent la baleine boréale de la population protégée des mers de Béring, des Tchouktches et de Beaufort au moyen d'armes à l'ancienne et de grenades remplies de poudre noire. Il faut parfois beaucoup de temps pour tuer l'animal, et certaines années un nombre relativement élevé d'animaux sont perdus. Une nouvelle grenade contenant de la pentrite a été mise au point pour les armes traditionnelles des Eskimos et testée durant la chasse à la baleine boréale de 1988, au cours de laquelle huit baleines ont été tuées par des grenades à la pentrite. Sept ont été ramenées à terre, la huitième a été perdue. Cinq baleines sont mortes sur le coup ou en moins de cinq minutes. Les dommages aux tissus et aux organes ont été relevés par autopsie. Bien que les données recueillies après 1988 soient moins fiables, la durée de survie enregistrée pour les animaux ramenés jusqu'en 1992 était nettement plus courte avec la grenade à la pentrite qu'avec la grenade traditionnelle à la poudre noire. La durée moyenne de survie était de 62 minutes pour les baleines tuées par des grenades à la poudre noire, et de 15 minutes pour celles tuées par des grenades à la pentrite; 21 et 45 p. cent respectivement des animaux étaient classés comme morts en moins de cinq minutes; 32 et 19 p. cent respectivement étaient perdus. La grenade à la pentrite va probablement devenir une arme très efficace pour la chasse à la baleine boréale, bien que des modifications et des essais restent à faire avant de pouvoir l'utiliser à grande échelle. Il faudrait aussi prévoir un programme d'éducation et d'entraînement pour tous les usagers éventuels. Il faudrait également considérer la possibilité d'améliorer le reste de l'équipement de chasse pour diminuer le nombre de baleines perdues.Mots clés: baleine boréale, Balaena mysticetus, chasse de subsistance traditionnelle des Eskimos, Alaska, méthode de chasse, grenade à la poudre noire, grenade à la pentrit