This report gives the reader a detailed description of a computer engineering master thesis work done at the company Netlight Consulting AB. Netlight Consulting AB is a growing IT consulting company based in Stockholm with offices in major cities across Europe. One of their key success factors is their focus on personal and professional development amongst all employees. An essential part of this development program consist of reoccurring evaluation periods, where every employee receives written constructive feedback from some of their co-workers. This thesis’ focus lies in improving the algorithm that organizes which employee should evaluate who. The original algorithm turned out to harbor a number of flaws, e.g. it was not always able to deliver a satisfactory matching where every participant received the minimum number of evaluations.   In this thesis a new matching algorithm has been implemented that is platform independent and that facilitates future modifications with accessible source code written in Java. The input data for the matching algorithm, i.e. the set of all potential evaluation pairs, is of importance to obtain satisfactory matching results. The number of potential evaluation pairs determines the number of possible matching combinations, which in turn increases the probability to find a satisfactory matching. In this thesis the input data has been extended by utilizing a data mining technique known as SONAR. Two different data mining sources were evaluated, and one of them is shown to extend the number of potential evaluation pairs in the matching input by 20%. Finally, a new feature to support assignment of different evaluation sizes was added to the matching algorithm.

In this master thesis, algorithms for acoustic simulations in underwater environments are ported for GPU processing. The GPU parallel computing platforms used are CUDA, OpenCL and SkePU. The purpose of this master thesis is to adapt and evaluate the ported algorithms' performance on two modern NVIDIA GPUs, Tesla K20 and Quadro K5000. Several optimizations, described in existing literature for GPU processing (e.g. usage of shared memory, coalesced memory accesses), are implemented and multiple versions of each algorithm are created to study their trade-offs. Evaluation on two GPUs showed that different versions of the same algorithm have different performance characteristic and execution with the best performing version can give better performance than the original algorithm executing on 8 CPUs. A performance comparison between CUDA, OpenCL and SkePU versions of one algorithm is also made.

Bottlenose dolphins (Tursiops truncatus) kept in zoos and dolphinarias rarely get an outlet for their echolocation abilities as their pool environment is often quite barren. Not much research has been carried out on enrichments promoting echolocation for dolphins in human care. In the present study a setup with live fish was compared to a setup with air-filled floats (providing strong sonar targets, similar to the swim bladders of large fish) and a control setup. A PCL (porpoise click logger) was used to record the echolocation click trains produced by the dolphins and aimed at the three setups. Behavioural data was also collected from video footage. Both the PCL data and all the behavioural observations indicated that the fish setup was more interesting than the float and the control setup, for the dolphins to echolocate towards. However, there were some contradictions with some parameters, where the floats and control seemed to be more interesting. This was probably due to the location of the PCL hydrophone in relation to the floats and fish, and not because the dolphins had a real bigger interest in these setups. To increase the possibility for dolphins to perform more echolocation in human care and increase their welfare, live fish can be recommended as echolocation enrichment.

The water level at Hjälta power station in Faxälven varies depending on the water flow that passes through the power station. The varying water level causes head losses, lesser energy generation and loss of income. The varying water level is caused by a short but narrow and shallow part of the river, known as Klockarforsen. To increase the water flow and decrease the resulting head losses, it is possible to dredge the stream bed in Klockarforsen in order to achieve a greater depth.  By using a sonar to map the bathymetry in Klockarforsen, it has been possible to create a model of this part of the river. The model has been constructed and processed in ArcGIS and HEC-RAS, in order to examine how a dredging would affect the water level, head losses, energy generation, income and retention water levels.  The results show that a dredging to a depth of four or six meters could raise the water level and the head height at Hjälta power station with an average of 0.32 and 0.41 meters, respectively. During the period between 2014-2019, 1.11-3.84 GWh more energy would have been generated annually if Klockarforsen had been dredged. Which means that the income for the power station would have increased by between MSEK 0.39-1.3 per year. The increased energy generation and income are considerable, but in terms of how much energy and income is generated annually, the figures are more modest. The energy production and income increase by between 0.13-0.3 percent annually.

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The size and organization of bed material, bed texture, is a fundamental attribute of channels and is one component of the physical habitat of aquatic ecosystems. Multiple discipline-specific definitions of texture exist and there is not a universally accepted metric(s) to quantify the spectrum of possible bed textures found in aquatic environments. Moreover, metrics to describe texture are strictly statistical. Recreational-grade side scan sonar systems now offer the possibility of imaging submerged riverbed sediment at resolutions potentially sufficient to identify subtle changes in bed texture with minimal cost,expertise in sonar, or logistical effort. However, inferring riverbed sediment from side scan sonar data is limited because recreational-grade systems were not designed for this purpose and methods to interpret the data have relied on manual and semi-automated routines. Visual interpretation of side scan sonar data is not practically applied to large volumes of data because it is labor intensive and lacks reproducibility. This thesis addresses current limitations associated with visual interpretation with two objectives: 1) objectively quantify side scan sonar imagery texture, and 2) develop an automated texture segmentation algorithm for broad-scale substrate characterization. To address objective 1), I used a time series of imagery collected along a 1.6 km reach of the Colorado River in Marble Canyon, AZ. A statistically based texture analysis was performed on georeferenced side scan sonar imagery to identify objective metrics that could be used to discriminate different sediment types. A Grey Level Co-occurrence Matrix based texture analysis was found to successfully discriminate the textures associated with different sediment types. Texture varies significantly at the scale of ≈ 9 m2 on side scan sonar imagery on a regular 25 cm grid. A minimum of three and maximum of five distinct textures could be observed directly from side scan sonar imagery. To address objective 2), linear least squares and a Gaussian mixture modeling approach were developed and tested. Both sediment classification methods were found to successfully classify heterogeneous riverbeds into homogeneous patches of sand, gravel, and boulders. Gaussian mixture models outperformed the least squares models because they classified gravel with the highest accuracies.Additionally, substrate maps derived from a Gaussian modeling approach were found to be able to better estimate reach averaged proportions of different sediments types when they were compared to similar maps derived from multibeam sonar.

Thesis: S.M., Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Mechanical Engineering; and the Woods Hole Oceanographic Institution), 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 97-103). / The presence of superimposed bedforms, where smaller bedforms exist on larger bedforms, is ubiquitous to energetic tidal environments. Due to their wide range in scale, it is difficult to simultaneously observe these features over tidal timescales. This thesis examines the morphological response of superimposed bedforms to a tidally reversing flow using novel instrumentation and platform systems. A method is outlined in chapter 2 to expand the functionality of low-mounted sidescan sonars by utilizing sonar shadows to estimate bedform height and asymmetry. Empirical models are generated to account for realistic variability in the seabed and the method is validated with bathymetric observations of wave-orbital ripples and tidally reversing megaripples. Given the high temporal and spatial resolution of seafloor frame mounted rotary sidescan sonars, the dynamics and evolution of the bedforms over an approximately 40 m x 40 m area can be resolved. In chapter 3 the method is applied to data of superimposed bedforms at Wasque Shoals, an ebb delta off the southeast corner of Martha's Vineyard, MA. These data reveal the small, superimposed bedforms reversing their asymmetry with the flow while the larger bedforms on which they reside remain oriented in the direction of the dominant flow. Similar bedform dynamics are observed at Nauset Inlet, a dynamic inlet system, on Cape Cod, MA using an autonomous jet-powered kayak, the Jetyak, equipped with a bathymetric swath sonar. The time needed for bedform asymmetry to reverse in the presence of a tidal flow was estimated with a geometric bedform model that incorporates an empirical sediment transport rate. The morphological lag time from the observations agree well with the geometric model with larger bedforms and slower flows resulting in a longer lag time. Finally, the migration of these superimposed bedforms is considered in chapter 4. Data from the rotary sidescan sonar at Wasque Shoals capture the interaction of smaller bedforms, or megaripples, with a dune. The net convergence of megaripples on the tidally dominate lee face of the dune suggests that the smaller bedforms serve as an intermediate step between grain-scale transport processes and larger scale dune migration. / by Katie Renae Jones. / S.M.

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The wastewater- and sewage distribution network is a critical aspect for maintaining a socialandenvironmental well-being. However, in the latest time, many failures (such as leakages) haveoccurred due to poor conditions in the wastewater-infrastructure, causing several consequencessuch as damage to the environment or pose health hazards to the public. This study is dividedinto three parts. Part one compares five different sewage inspection technologies: Closed-CircuitTelevision (CCTV), Zoom Cameras, Digital Scanning, SONAR and Electro Scanning with thepurpose of identifying a new system that Stockholm Vatten & Avfall (SVOA) should considerimplementing. Part two goes through the inspection procedure that SVOA applies, andrecommendations are concluded as to how the process can be optimized. Part three coversessential aspects that should be taken into account before investing in a new technology. Theresearch methodology involves collecting data from literature, internal reports from SVOA, andconducting interviews with supervisors and field workers. The main finding is that SVOA shouldcontinue with the current approach that the utility is using because the current data found in thecurrent literature is too insufficient and not too strong which makes it not convincing to investinto a new technology. On the other hand, the collected data about the technologies can beconsidered whenever the approach is moving towards a proactive approach.

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