[final] Final projects

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Opiskelijavaihdon päättötyöt. / Student exchange final projects.

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Browsing [final] Final projects by Title

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  • 3D discrete numerical modeling of conical structure-ice rubble interaction
    (2009) Haase, Andrea
     Helsinki University of Technology |
  • 3D Structural and hydrogeological modeling of Metsähovi research site
    (2010) Gerrits, P.C.
     School of Engineering |
  • Active Dielectric Rod Waveguide
    (2009) Expósito Dominguez, Gonzalo
     Helsinki University of Technology |
  • Active power factor correction of a single-phase rectifier
    (1994) Schäffeler, Peter
     Helsinki University of Technology |
  • Adaptive current reference generator for active power filters
    (2013-10-21) Nicolino, Fabrizio
     Sähkötekniikan korkeakoulu |
    The electricity distribution networks are increasingly characterized by the presence of non-linear power electronic devices and power plant equipment capable to create problems of harmonic pollution. However, to have the best performance of attenuation of the harmonics introduced by various non-linear loads it is common to use an Active Power Filter (APF). In this thesis is presented the analysis of one of these filters and the development of possible improvements. I realized a Matlab code that could reproduce the operation of the filter and tested its efficiency. Subsequently the goal was to learn and explain why the original algorithm, in addition to filtering the harmonics present in the input signal, introduced new harmonics. The second goal was to analyze a possible simplification of the filtering algorithm, reducing the number of algebraic multiplications, so that it can be implemented effectively on Field Programmable Gate Arrays (FPGAs).
  • Adaptive ensemble models of extreme learning machines for time series prediction
    (2009) Heeswijk, Mark van
     Helsinki University of Technology |
  • Adaptive loudness compensation in audio reproduction
    (2019-05-06) Fierro, Leonardo
     Sähkötekniikan korkeakoulu |
    This work involves the study of the psychoacoustic phenomenon of nonlinear and frequency dependent loudness perception, its modeling, and the use of digital filters to introduce an adaptive compensation based on the reproduction level. Music and sound are mixed and mastered at a particular loudness level, which is usually louder than the level they are commonly played at. This implies a change in the perceived spectral balance of the audio source, which is largest in the bass and sub-bass ranges. As the volume setting in music reproduction is decreased, a loudness compensation filter can be designed to introduce an appropriate boost, so that the low frequencies are still heard well and the perceived spectral balance is preserved. This thesis describes a loudness compensation function derived from the standard equal-loudness level contours and its implementation via a digital first-order shelving filter, and it documents a formal listening test, designed and conducted to validate the accuracy of such a method. The research work was carried out between October 2018 and January 2019, during a visiting period at the Aalto University, Espoo, Finland.
  • Advanced analysis tools and technologies for gas engines and their waste heat utilisation
    (1997) Leu, Erik
     Helsinki University of Technology |
  • Alkaline pre-extraction of birch wood prior to alkaline pulping
    (2013) Costabel Cabrera, Luciana
     School of Chemical Engineering |
    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.
  • Alumiinin sulatusuunin polttimien optimointi
    (2002) Takala, Anssi
     Helsinki University of Technology |
  • Amplify and decode and forward relays in cellular networks: A performance evaluation
    (2009) Merlán Llorente, Antonio Borja
     Helsinki University of Technology |
  • Analysis of Nonidealities in Undersampling SAR ADCs
    (2018-08-20) Mattersdorfer, Clemens
     Sähkötekniikan korkeakoulu |
    With the foreseeable adaptation of 5 G networks and its increasing use, blockers are becoming more common on their frequency bands. This gives rise to the need of wideband blocker-detection circuits for frequencies up to 6 GHz. The use of under- sampling SAR ADCs to detect blockers has already been demonstrated [1], however the performance showed to be lower than expected. The objective of this work is to investigate nonidealities appearing in SAR ADCs, when used as under-sampling converter. Therefore, a behavioral model of a SAR ADC has been built in Verilog-A, and an accompanying toolchain in Matlab has been devel- oped to assess the impact of system parameter variations on the dynamic performance figures (SNR, SNDR,...). The utilization of a behavioral model also allows an isolated view on otherwise interdependent phenomena, besides reducing the simulation time. System simulations show the effect of various system parameter variations on the converter performance. The conclusions drawn from behavioral simulations have been verified by inserting 65 nm technology transistors into the behavioral model. The sampling error appearing at slow switch transition times has also been investigated. It has been concluded, that the SAR ADC performance is primarily limited by the track-and-hold circuit, as the finite transition time from track- to hold-state causes the fast changing input signal to be averaged nonlinearly, instead of being sampled almost ideally.
  • Antenna array receiver switching synchronization for indoor positioning systems using WLAN technology
    (2011) Kis, Levente Robert
     School of Electrical Engineering |
  • Applicability of pumped storage power in Finland
    (2013) Cramer, Stefan
     School of Engineering |
    The discrepancy between electricity production and consumption asks for regulation power and energy storage capacities. In Finland regulation power is produced comparatively expensively by thermal reserve power plants and is imported. In future Finland has an increasing regulation power demand due to focus on nuclear and on wind power. Pumped storage power is up to date the only economically sound and environmentally compatible technology for large scale energy storage. Although this technology is largely used in other countries Finland has not any single pumped storage power plant in operation. The aim of this study is to evaluate applicability of pumped storage power for Finnish conditions. The built up PSP operation simulation model uses price spreads referred to a moving average energy price. With price series of Nord Pool for Finland in hourly resolution as input the model generates site specific turbining and pumping decision series determing operation benefit. As applicability of pumped storage power depends on site specific conditions possible pumped storage sites are identified and feasibility is evaluated in case studies. In iterative procedure operation scheme, design flow rate as well as hydraulically and electromechanical design 1S optimized. The plants are predesigned in conceptual and feasibility studies. Thereby technical, economic and environmental aspects are respected. The predesigned feasible PSP Tampere between large lakes has an installed power of 12 MW. Simulated annual performance is characterized by an increasing trend with large annual fluctuations. In Pyhäsalmi mine the pre-dimensioned PSP with 1400 m head and an installed power of 660 MW is highly feasible with a direct payback time of 5 years. The power is provided by two reversible multistage pump turbine units and by two dual units with Pelton turbine and multistage pumps. The dual units enable regulation within seconds and input power adjustment by hydraulic shortcut operation. The hourly resolution of the in the model used regulation energy price data leads herewith to an underestimation of pumped storage operation benefit. Average stable hardrock conditions in mine Pyhäsalmi allow drilling of penstock directly into hardrock. Detailed geological conditions have to be investigated in further studies. With good geological conditions and deep ore mines of large storage volume Finland has optimal conditions for underground pumped storage. Due to straight waterways high hydraulic efficiencies can be achieved in mines. On the other hand electromechanical efficiencies get reduced for deep mines due to the need for multistage pump turbines or pumps. Constructing of pumped storage power plants between large lakes requires large design flow rates due to usually low heads. Hydraulic losses are thereby considerable. Using large natural lakes environmental impacts of pumped storage is small with lake level fluctuations of some centimetres. The use of mines does not consume new surface areas. Compared to alternative technologies pumped storage power is free of greenhouse gas emissions. Sustainability requires energy storage capacities and the necessary infrastructure can also in Finland be realized by large scale pumped storage.
  • Application of mobile intelligent agents in IP QoS networks management
    (2001) Pedrós Porres, Ramiro José
     Helsinki University of Technology |
  • Applying the Balanced Scorecard to University
    (1999) Delgado Martinez, Ivan
     Helsinki University of Technology |
  • ATV braking system: introduction and system modelling.
    (2014-08-25) Geromel, Nicola
     Sähkötekniikan korkeakoulu |
    All-terrains-vehicles (ATV) are largely used in forest working and patrolling, supporting rangers, lumberjacks and many other workers. Recently, environmental issues led to the development of electrical ATVs, that are able to provide zero emissions, more silent and cheaper operations. Thus far, these vehicles have always been driven by humans, but the last technological developments allow the implementation of self-driving and autonomous vehicles. This is an attractive possibility to help off-road workers to gain more flexibility and autonomy in their activities and an help in rescue operations as well.A crucial part in the autonomous vehicles field is the braking performance, even more important if we consider the kind of surfaces on which these vehicles are meant to go. The problem of the wheels slippage has been deeply considered for road vehicles, but few solutions and application have been implemented for off-road ones. In this final project, an introduction study in this sense is made, focusing on the brake system modelling and evaluation of some ABS solution. The vehicle in use is a Polaris Ranger. Many slip and braking system controls have been investigated: the newest and most complex of them allow to get really high control performances and they can cope with the system modelling uncertainties. One the most promising is the sliding mode control (SMC) for its trade-off between complexity and ability to face the uncertainties. The modelling part showed us how strongly the road state can affects the braking performance and in the other side that is extremely difficult to get a detailed model of the whole braking system.
  • Automatic Calibration and Equalization of a Line Array System
    (2015-08-24) Vidal Wagner, Fernando
     Sähkötekniikan korkeakoulu |
    This final project presents an automated Public Address processing unit, using delay and magnitude frequency response adjustment. The aim is to achieve a flat frequency response and delay adjustment between different physically-placed speakers at the measuring point, which is nowadays usually made manually by the sound technician. The adjustment is obtained using four signal processing operations to the audio signal: time delay adjustment, crossover filtering, gain adjustment, and graphic equalization. The automation is in the calculation of different parameter sets: estimation of the time delay, the selection of a suitable crossover frequency, and calculation of the gains for a third-octave graphic equalizer. These automatic methods reduce time and effort in the calibration of line-array PA systems, since only three sine sweeps must be played though the sound system. For verifying the functioning of the system, both simulated signals and measurements have been conducted. A 1:10 scale model of a line array system has been designed and constructed in an anechoic chamber to test the automatic calibration and equalization methods and the results are analyzed.
  • Automatic signal processing of magnetocardiogram data with template selection
    (2006) Pison, Daniela
     Helsinki University of Technology |
  • Backwards compatibility experimentation with host identity protocol and legacy software and networks
    (2008) Fínez Moral, Teresa
     Helsinki University of Technology |