[final] Final projects

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Opiskelijavaihdon päättötyöt. / Student exchange final projects.

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    Overmodulation and six-step mode for observer-based V/Hz control
    (2023-02-03) Iaderosa, Angelica; Tiitinen, Lauri; Sähkötekniikan korkeakoulu; Hinkkanen, Marko
    This thesis deals with the control of electrical machines in the overmodulation range. The goal is to have a stable control system able to exploit the full potential voltage of the inverter. After a brief explanation of the system model, the overmodulation algorithm is described. This method allows to have a smooth transition between the linear operation to the extreme operating condition in which the maximum voltage is produced. A synchronized PWM approach is adopted in order to reduce the harmonic spectrum throughout the whole operation. A scalar control based on a flux observer is considered thanks to its stability and its compatibility with the maximum voltage operation. Results show the feasibility of the overall system, six-step mode is able to increase the reachable speed while lowering the currents.
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    Design and verification of test device for rotors
    (2004) Barbero Oliver, Jesus; Juhanko, Jari; Konetekniikan osasto; Teknillinen korkeakoulu; Helsinki University of Technology; Kuosmanen, Petri
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    User Position-Based Loudspeaker Correction
    (2021-12-13) Lindfors, Joel; Liski, Juho; Sähkötekniikan korkeakoulu; Välimäki, Vesa
    In this thesis, a novel loudspeaker correction system is presented and studied.This correction system uses the location of the user to determine the calibrationparameters. Conventional loudspeaker correction uses a static equalizer to correctfor the coloration of the loudspeaker system at all times. However, the response ofthe loudspeaker changes dynamically with the location of the user. By correctingfor the loudspeaker’s response at multiple locations and changing the calibration inreal-time based on the user’s location, we expect a less colored frequency responsecompared to no applied calibration or conventional calibration methods. Thedeveloped method,User Position-Based LoudspeakerCorrection (UC), producesa flatter frequency response than that of no applied calibration: in one of themeasurement conditions the averages of the ranges of the frequency response (thedifference between the largest and the smallest decibel value) went from 10.3 dBin the non-corrected setting to 4.7 dB in the UC setting. Further, it is shownto outperform a conventional method of correcting for the frequency responseof each point in space by using calibration derived from measurements from apredetermined listening position. The average of the ranges with the conventionalmethod of calibration in the aforementioned listening condition was 6.8 dB. Finally,by interpolating the EQ gains for the calibration from a set of measurements for thesuggested correction method, the system’s resolution could be increased with theresulting calibration still outperforming the conventional correction method. Theaverages of the ranges for the interpolation methods in the aforementioned listeningcondition were around 6.1 dB varying approximately 0.1 dB with the method.
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    Treatments for enhancing accesibility an reactivity of cellulose and their analysis
    (2015) Debnath, Subham; Rantanen, Juuso; Kemian tekniikan korkeakoulu; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Maloney, Thaddeus
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    Position control and overall efficiency of electro-hydraulic system
    (2014) Bonato, Carlo; Minav, Tatiana; Insinööritieteiden korkeakoulu; Insinööritieteiden korkeakoulu; School of Engineering; Juhala, Matti
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    Evaluation of ice induced loads on ships in compressive ice
    (2014) Filipovic, Antonio; Suominen, Mikko; Sovelletun mekaniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Kujala, Pentti
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    Developing a framework for prefabrication assesment using BIM
    (2014) Cereceda, Carlos; Singh, Vishal; Insinööritieteiden korkeakoulu; Insinööritieteiden korkeakoulu; School of Engineering; Singh, Vishal
    Building Information Modelling is a disruptive technology in construction at this precise moment, and the opportunity to take advantage of the technology by combining it with prefabrication should not be wasted. The adoption of BIM represents a complete revolution in the construction environment, since it changes construction processes in every aspect. The purpose of this project is to present the prefabrication components clearly, for relating them with the most conceptual and theoretical concepts used in construction. This will help the designer for the design of building components. Then, BIM benefits are presented with the potential of using this technology. Designing a component is only the first step in prefabrication procedure, since the manufacturing process can seriously affect to the whole construction process. The different techniques are explored, paying special attention to 3D-Printing and Contour Crafting. One more time, these technologies align with prefabrication principles. In order to achieve the highest efficiency in the construction process, methodologies such as Buildability, Function and Structure Sharing and Mass Customization are presented, as well as their possible implementation in the construction field.Finally, some real case studies which employ prefabrication methods are studied and analyzed according to the framework and the statements made before. The project also proposes some recommendations for those who plan to conduct such studies in future.
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    Network coding coefficients for compute-and-forward
    (2014) Zacharda, Marek; Pääkkönen, Joonas; ; Sähkötekniikan ja automaation laitos; Sähkötekniikan korkeakoulu; School of Electrical Engineering; Farkas, Peter
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    Economical and ecological optimization of binder system
    (2014) Estellés Belenguer, Marta; Punkki, Jouni; Yhdyskunta- ja ympäristötekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Cwirzen, Andrzej
    The environmental preservation and sustainable design has become an important issue for all industries, including the cement industry. Cement industry contributes 5% of the CO2 emitted to the atmosphere every year. For the production of 1 Tonne of Portland cement, 1 Tonne of carbon dioxide is emitted to the atmosphere. The main purpose of this research was to optimize the utilisation of alternative to OPC cementious binders in the concrete production. Five different kinds of binders were studied, including three ordinary mixes: Portland Cement, Portland Cement + Fly Ash, Plus-Cement + Fly Ash and two alkali-activated (AA) mixes: Portland Cement + Fly Ash + Blast Furnace Slag and Blast Furnace Slag + Limestone filler. The study was done in two steps: Initial Laboratory Studies, where the binder mixes were optimized focusing on compressive strength and workability, and Final Laboratory Studies where chosen optimised earlier mixes were studied in more detail including also their ecology and economy. The results showed that heat treated samples reached higher early compressive strength in comparison with no heat treated specimens. Compressive strength in alkali-activated binders was higher due to the activation with water-glass. The temperature of normal OPC concretes reached up to 55°C. The AA concrete showed much lower temperatures, what is beneficial for thick and heavily restrained concrete elements (such as walls). In the economical study, the ordinary mixes showed similar costs, while the alkali activated mixes were more expensive. On the contrary, in the ecological analysis, the AA mixes showed much lower CO2 emissions.
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    Modelling of air void content related to dielectric value of asphalt
    (2014) Vicente Agost, Hector; Pellinen, Terhi; Yhdyskunta- ja ympäristötekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Pellinen, Terhi
    The purpose of the study was to investigate the ratio between air void content and volumetric properties related to the dielectric values of asphalt. This information was supposed to contribute to a bigger project commissioned by the Finnish Transport Agency. The followed test method was to compact the samples by gyratory compaction, measurement of the densities and calculation of the volumetric properties and measurement of the dielectric values. The target height dimension of the samples was 125 mm. A large testing program of 18 cut samples was carried out in the laboratory of Highway Engineering. In first place Stone Mastic Asphalt 16 was the material used. Because of problems and obstacles found out while it was being used, the material was changed to Asphalt Concrete 16. The obtained values for the dielectric values and for the volumetric properties studied only gave one approximation of one relation already discovered but other studies. Furthermore, not more important conclusions could be observed in the results.
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    Relation between ball catching accuracy and camera position in virtual reality
    (2014) Marjalizo Alonso, Felipe; Kajastila, Raine; Perustieteiden korkeakoulu; Perustieteiden korkeakoulu; School of Science; Hämäläinen, Perttu
    Our research aimed to analyse the effects of virtual camera position on 3D interaction in a virtual environment. The participant's task was to try to catch flying balls using different camera setups. The cameras position ranged from natural first person perspective to a third person perspective. The experiment is motivated by the popularity of third person perspective in video games and the difficulties of natural 3D interaction in such camera position. As our setup, we used the Oculus Rift virtual reality headset and PlayStation Move controllers. This setup allows us to achieve an immersive virtual reality experience with a full 6 degrees of freedom tracking of hand and head. The results show that the natural 3D interaction performance is notably degraded as the camera is positioned far away from the first person perspective.
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    Full-text search engines: Analysis and bencmarking of distributed text-search solutions
    (2014) Canellas, Jorge; Fabra Caro, Francisco Javier; Perustieteiden korkeakoulu; Perustieteiden korkeakoulu; School of Science; Heljanko, Keijo
    The amount of available data has increased notably in the last few years, exposing scalability problems of storage systems. Traditional clusters built with expensive storage solutions have proven not to be a feasible solution. The amount of investment needed to build and expand such clusters is not affordable by many companies. Commodity hardware is much cheaper but fails more often. Fault tolerance has been passed to the application layer, which allows building larger clusters with less investment thus leading to more powerful systems. However the fault tolerance mechanisms have to be taken into account when designing the application. The most common mechanisms used when implementing data storage applications is replication. Creating several copies of the same data ensures that the data is still available if there is at least one replica alive. On the other hand, replication introduces new problems. Managing replicas can be complicated when modifying existing data. It is important to make sure that all the replicas store the same version of the data. Searching in huge amounts of data requires new approaches since non-distributed text search engines are not able to return relevant documents in a reduced amount of time. Scaling a text search engine requires that the storage capabilities of the cluster can be increased horizontally and that the response time does not increase drastically as the number of computers increases. The purpose of this work is to analyse two different full-text search engines, Elastic search and Cloud era's distribution of SolrCloud. Both text search engines use Lucene, a search library written in Java, under the hood to build a text search engine. However, they manage data distribution and scaling in different manners. We have prepared benchmarks to visualize how do they behave with different setups and how does the number of available nodes influence in their search and indexing performance.
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    Effect of carbon nanotubes and nanofibers on autogenous shrinkage of Portland cement based binders
    (2014) Feneuil, Blandine; Ehrlacher, Alain; Rakennustekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Cwirzen, Andrzej
    Effects of four types of carbon nanotubes and nanofibers on autogenous shrinkage of cement paste have been investigated. Device for autogenous shrinkage measurement has been set up and tests have been run for each sample for 48 hours. In addition, to support interpretation of the results, bending and compression tests, workability measurement, FE-SEM observation and X-ray diffraction analysis have been carried out. Collected data showed that carbon nanofibers and nanotube, either non-treated or functionalized, could be used to reduce autogenous shrinkage. The uniformity of their dispersion appeared to be the main factor defining their efficiency in reducing the shrinkage. Hence, suitable nanotube/fiber concentration, amount of superplasticizer and sonication time was crucial to decrease the shrinkage. Also nanotube and nanofiber surface properties had an influence on the behaviour towards autogenous shrinkage: better bonding with cement matrix enabled a better shrinkage reduction.
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    Thermodynamical modeling of alkalonamine solution
    (2013) Dominguez Alabern, Laura; Jakobsson, Kaj; Kemian laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Alopaeus, Ville
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    Methanol steam reforming for polymeric electrolyte membrane fuel cells applications
    (2013) Vidal Vázquez, Francisco de Sáles; Lehtonen, Juha; Simell, Pekka; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Koskinen, Jukka
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    Electrochemical oxidation of refractory gold concentrate
    (2013) Ferrer Munoz, Gerard; Rintala, Lotta; Materiaalitekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Aromaa, Jari
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    Game theory applied to networking
    (2013) Casas Bonet, Marc; Costa-Requena, Jose; Tietoliikenne- ja tietoverkkotekniikan laitos; Sähkötekniikan korkeakoulu; School of Electrical Engineering; Kantola, Raimo
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    Fracture flow DEM modelling for tentative estimation of the pressure field behaviour and inflow in ONKALO nuclear repository
    (2013) Lombardero Reymundo, Manuel; Hatakka, Lassi; Nuijten, Guido; Ström, Jesse; Martinelli, Daniele; Yhdyskunta- ja ympäristötekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Leveinen, Jussi
    In 1994 it was decreed by law that all nuclear waste produced in Finland must be disposed of within the Finnish territory. For this purpose, the ONKALO project is being developed. ONKALO is a hard rock research laboratory, located in Eurajoki, whose excavation began in 2004. It is being constructed at the moment, and will be part of the ONKALO deep geological repository for nuclear waste disposal. The storage in the repository will start with the first disposal in 2020, and it will last until its completion in the 2100'S when it will be closed sealed and the entrance buried. An access tunnel, one shaft and two semi-bored shafts currently integrate ONKALO. The access tunnel is approximately 5 km long and reaches a depth of about 460 m below the surface, as well as the outlet shaft. The other two shafts only reach the level -290. Due to the forthcoming purpose of this excavation for nuclear waste storage, and because of groundwater migration carrying dangerous substance can occur, several limitations have been set to the excavation processes. In the exhaust shaft an inflow limitation has been set in 5 l/min, but there are some fracture zones that are intersecting the shaft and are bringing water into ONKALO through the exhaust shaft. The general purpose of this study is developing a reliable joint fluid flow in hard rock model. The specific scope of this study is to create a numerical DEM model to simulate how the groundwater and pressure field behaves in the vicinity of the shaft after it is excavated, predict the path that groundwater follows within the bedrock in order to locate eventual leakage points, and attempt to simulate how the grout spreads through the fracture network, in order to give further advice in the excavation of other shafts. As a result of this study, it can be confirmed that groundwater flow in deep hard rock mainly occurs along fractured zones towards an excavated void. Practically no flow takes place along tight fractures. Post grouting works improve water tightness of the rock where the injection is done. In general, no new paths for groundwater flow are created and the total inflow substantially decreased.
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    iPhone impact, the impact of the iPhone in the Nascent Smartphone Market
    (2013) Cantería Pastor, Pablo; Perustieteiden korkeakoulu; Perustieteiden korkeakoulu; School of Science; Schmidt, Jens
    In 2007 Apple launched the iPhone and a few years later, we can see that this release meant a huge change in the mobile phone industry. The disruption created by this release has been remarkable. The aim of this study is to give some insight in the development of the Smartphone industry due to the release of the iPhone, the changes that the main competitors did in order to differentiate from Apple or the features they copied from it. 1. Provide a solid background on the mobile phone industry and its main players. 2. Study the development of the market in terms of features adopted. 3. Propose a valid set of features for a Dominant Design. In order to fulfil this goals, a brief literature review has been done. Mostly, scientific publications on Dominant Design and Strategic Management but also blogs on Smartphone trends, releases, reviews, etc. The empirical study consisted on the documentation of more than 1000 models released in the time frame of 6 years (2007 to 2012) and the quantitative analysis of many of the features of these models. Finally, we raise some conclusion and we give some input for further research on the topic.
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    Alkaline pre-extraction of birch wood prior to alkaline pulping
    (2013) Costabel Cabrera, Luciana; Ruuttunen, Kyösti; Biotekniikan ja kemian tekniikan laitos; Kemian tekniikan korkeakoulu; School of Chemical Engineering; Sixta, Herbert
    The existing chemical pulp mills offer a unique starting point for the implementation of future multi-product biorefineries. For the pulp industry, the biorefining process may be envisaged as the removal and use of material that does not contribute to paper and cellulose products, particularly the material which is normally dissolved in the black liquor and combusted in the recovery boiler. In that sense, the recovery of dissolved hemicelluloses in a separate stage prior to pulping for the production of added-value products may potentially improve the overall economy of a chemical pulp mill. The alkaline extraction of hemicelluloses prior to alkaline pulping provides an additional possibility to isolate carbohydrates from wood in reasonably high yields, besides the currently widely investigated acid- and auto-catalyzed prehydrolysis. Furthermore, the use of aqueous sodium hydroxide solution in a pre-extraction process is compatible with kraft or soda-anthraquinone pulping processes, and particularly for the production of paper grade pulp, this process is more likely to preserve fibre strength properties than prehydrolysis followed by alkaline pulping. The objective of this work was the recovery of high molecular weight hemicelluloses, mainly xylan, through alkaline extraction. At the same time, the amount of co-extracted lignin was to be minimized. Birch wood chips were used for the optimization of the pre-extraction conditions. In addition to temperature and sodium hydroxide concentration, the effect of chip thickness was studied. The optimized extraction conditions were found to be NaOH concentration of 2.5 M at 95 °C. Lignin and carbohydrate mass balances were calculated for pre-extraction trials performed at these conditions. Approximately 6% of the original dry wood material was measured in the extracted liquor as polymeric xylan and 1% as co-extracted lignin. The selectively precipitated xylan revealed a weight average molecular weight (Mw) of 20 kDa as determined by size exclusion chromatography. For further purifying the extracted xylan, the diluted solution was concentrated by a factor of 8 by means of pressure-driven membrane filtration. This separation process allows the recovery of a large part of the sodium hydroxide in the permeate stream and makes a subsequent xylan precipitation via acidification more economical. The permeate stream containing the recovered sodium hydroxide may be recycled to the cooking liquor preparation. Preliminary tests confirmed that xylan can be isolated in higher purity when the pH is maintained at a higher level during the precipitation step since lignin remains more soluble under these conditions.