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Hikkaduwa, Vithanage Ajith. "DESIGN AND PERFORMANCE ANALYSIS OF PITCHED-PLATE VERTICAL AXIS WIND TURBINE FOR DOMESTIC POWER GENERATION." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-17428.
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Wind energy is identified a promising energy resource in Sri Lanka. Therefore, it is important to use proper technologies for efficient energy capturing in order to minimize cost of energy. Small scale wind turbines are usually installed in constricted places (particularly in urban areas) where wind flow is turbulent and difficult to predict. Savonious type vertical axis wind turbines are important due to several reasons such as good response to turbulent winds, high initial torque, low cost, low noise, less maintenance.In this study, a modified flat plate type Savonius wind rotor was proposed to cost effectively harness wind energy in constricted places. Generally, vertical axis wind turbines (VAWT) are less efficient than horizontal axis wind turbines, one reason behind this issue is wind force difference between the 2 sides of the axis is small and due to this reason torque is small and power generation capacity is less.A prototype of the proposed VAWT was fabricated and the performance was determined by acquiring experimental data. Artificial wind blow which was generated by a huge fan was used to measure rotational speed and torque characteristics at varying wind speeds. Data were collected with 1-second sampling time and a data acquisition system was developed under this study. In the proposed design one side of the turbine blades are facing the wind direction in order to capture maximum force while other side is edging the blades to have minimum opposite torque. With this concept it is expected to maximize the torque of the axis and generate more power. A sort of a passive pitch mechanism is therefore utilized in order to save energy and simplify the system. Turbine blades are simple flat plates and it eliminates usage of complex aero foils. Due to the simplicity of this design it would be possible to use this turbine for domestic electricity generation at affordable costs.Nowadays, net metering systems are being promoted in Sri Lanka and it would be beneficial to introduce low cost VAWT which operates at low winds as well as turbulent wind conditions. Based on typical household hourly load profile, viability of proposed vertical axis wind turbine was evaluated by considering rural and urban wind regimes in Sri Lanka. The costs of wind energy at two selected locations were determined in the context of net metering.
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Taylor, Katharin C. "Method for VAWT placement on a complex building structure." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34752.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. As such, it is in the public domain, and under the provisions of Title 17, United States Code, Section 105, it may not be copyrighted.Approved for public release; distribution is unlimited
This thesis is part of a larger project that will demonstrate the feasibility of powering a commercially sized 7.5-ton cooling system. Excess cooling will be stored thermally using ice. This system has the potential to be used in military bases to reduce energy costs and fossil fuel consumption. A scaled down version would be suitable for data centers and forward operating bases where the transport of fuel can be costly and dangerous. The system will be built and operated at the Turbopropulsion Laboratory (TPL) of Naval Postgraduate School. This thesis concentrates on the choice and location of wind turbines used to power the cooling system. A simulation of Building 216, which is the planned site of the cooling system, was performed. A wind flow analysis found that optimum placement of the wind turbines is at the front of the south end of the building. The method for placing the wind turbines is outlined and applicable to other structures. Vertical Axis Wind Turbines (VAWTS) were found to be the most suitable for site location. A transient analysis of the VAWTS was necessary to accurately simulate their performance. This supported the selection of a three-bladed helical VAWT design. Further simulations of wind turbine separation showed some beneficial effects of close spacing.
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Wahlberg, Nils. "Konstruktion av statorstomme för synkrongenerator : Förslag på design av statorstomme för användning i vertikalaxlade vindkraftverk." Thesis, Uppsala universitet, Elektricitetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-207778.
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This thesis describes a conceptual design of a support frame for a synchronousgenerator used in a vertical axis wind power plant. In this system the generator isplaced on ground level. The thesis also considers the design of housing for thesupport frame and generator. The concept presented in this report is based on anearlier design. Besides geometric design, simplified simulations has been run in orderto optimize some of the parts included in the construction considering naturalfrequencies and structural strength. The result is presented as CAD-models andan assembly drawing.
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Zhao, Jiaming. "Experimental Study of Effects of Leading-Edge Structures on the Dynamic Stall of a Vertical Axis Wind Turbine Airfoil." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/32053.
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Vertical axis wind turbine, developed as one of the main methods to utilize the wind energy, has a promising future; however, the major issue to limit its performance is the uneven loading on the blade during operation. Flow control mechanisms have been employed in the aerodynamic field to improve the performance of airfoils. In this study, two types of leading-edge structures, including flexible leading-edge and leading-edge roughness, are experimentally investigated to analyze their effects on altering the aerodynamic characteristics of NACA 0018 airfoil under steady flow condition and dynamic pitching condition. Current experimental results indicate that 1) during the steady flow condition, both of leading-edge structures contribute to the delay of the static stall; 2) for the dynamic pitching process, the leading-edge structures either delayed the dynamic stall angle or increased the area of the coefficient of pressure loop as a function of angle of attack.
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Almohammadi, Khaled Mohammad. "Optimization of a CFD based design of a straight blade vertical axis wind turbine (SB-VAWT)." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7021/.
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Enhancing the extraction of the wind energy in urban regions using micro and small wind turbines becomes a necessity with the increasing power consumption. The focus of this thesis is to optimize micro and small SB-VAWT performance by analysing CFD techniques, several modelling characteristics and design parameters where the performance is measured by the power coefficient. In this thesis, the SB-VAWT is optimized by employing sophisticated optimization techniques, namely such as the GA and the NLPQL, which are employed on response surfaces created from several design sampling methods. The optimization is based on three parameters, namely, camber, thickness and chord. A novel airfoil geometry has been introduced. The new airfoil geometry increases the power coefficient by about 42% at the optimized tip speed ratio and increases the peak of the turbine power coefficient by 4% at a low tip speed ratio. However, it was necessary to assess the computational process by examining the mesh and the computational method in order to ensure that the optimized design of the SB-VAWT is only resulting from the optimization process. Therefore, several physical phenomena have been investigate including the dynamic stall, laminar-turbulent transition and laminar bubbles. Also, several computational techniques and schemes have been critically analysed. Further, several mesh independency techniques have been implemented and it was found that the fitting method may be suitable for SB-VAWTs due to the presence of oscillations in the convergence of the power coefficient which may be caused by the presence of dynamic stall, laminar-turbulent transition and laminar bubbles. The physics of these flow conditions are only captured when the transitional model is employed. The optimization of the SB-VAWT in this thesis is based on a 2D model. It was found that the 2D model produce a results similar to the 3D model at mid span of the turbine blade. Therefore, the 2D model of the turbine sufficiently represents the flow physics around the blades qualitatively, and thus the 2D model is employed for the optimization of the SB-VAWT.
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Pearson, Charlie. "Vertical axis wind turbine acoustics." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245256.
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Increasing awareness of the issues of climate change and sustainable energy use has led to growing levels of interest in small-scale, decentralised power generation. Small-scale wind power has seen significant growth in the last ten years, partly due to the political support for renewable energy and the introduction of Feed In Tariffs, which pay home owners for generating their own electricity. Due to their ability to respond quickly to changing wind conditions, small-scale vertical axis wind turbines (VAWTs) have been proposed as an efficient solution for deployment in built up areas, where the wind is more gusty in nature. If VAWTs are erected in built up areas they will be inherently close to people; consequently, public acceptance of the turbines is essential. One common obstacle to the installation of wind turbines is noise annoyance, so it is important to make the VAWT rotors as quiet as possible. To date, very little work has been undertaken to investigate the sources of noise on VAWTs. The primary aim of this study was therefore to gather experimental data of the noise from various VAWT rotor configurations, for a range of operating conditions. Experimental measurements were carried out using the phased acoustic array in the closed section Markham wind tunnel at Cambridge University Engineering Department. Beamforming was used in conjunction with analysis of the measured sound spectra in order to locate and identify the noise sources on the VAWT rotors. Initial comparisons of the spectra from the model rotor and a full-scale rotor showed good qualitative agreement, suggesting that the conclusions from the experiments would be transferable to real VAWT rotors. One clear feature observed in both sets of spectra was a broadband peak around 1-2kHz, which spectral scaling methods demonstrated was due to laminar boundary layer tonal noise. Application of boundary layer trips to the inner surfaces of the blades on the model rotor was found to eliminate this noise source, and reduced the amplitude of the spectra by up to 10dB in the region of the broadband peak. This method could easily be applied to a full-scale rotor and should result in measurable noise reductions. At low tip speed ratios (TSR) the blades on a VAWT experience dynamic stall and it was found that this led to significant noise radiation from the upstream half of the rotor. As the TSR was increased the dominant source was seen to move to the downstream half of the rotor; this noise was thought to be due to the interaction of the blades in the downstream half of the rotor with the wake from the blades in the upstream half. It was suggested that blade wake interaction is the dominant noise source in the typical range of peak performance for the full-scale QR5 rotor. Different solidity rotors were investigated by using 2-, 3- and 4-bladed rotors and it was found that increasing the solidity had a similar effect to increasing the TSR. This is due to the fact that the induction factor, which governs the deflection of the flow through the rotor, is a function of both the rotor solidity and the TSR. With a large body of experimental data for validation, it was possible to investigate computational noise prediction methods. A harmonic model was developed that aimed to predict the sound radiated by periodic fluctuations in the blade loads. This model was shown to agree with similar models derived by other authors, but to make accurate predictions very high resolution input data was required. Since such high resolution blade loading data is unlikely to be available, and due to the dominance of stochastic sources, the harmonic model was not an especially useful predictive tool. However, it was used to investigate the importance of the near-field components of the sound radiated by the wind tunnel model to the acoustic array. It was shown that the near-field terms were significant over a wide range of frequencies, and the total spectrum was always greater than that of the far-field component. This implied that the noise levels measured by the acoustic array represented an upper bound on the sound radiated to the far-field, and hence that the latter would also be dominated by stochastic components. An alternative application of the harmonic model, which attempted to determine the blade loading harmonics from the harmonics in the sound field was proposed. This inversion method utilised a novel convex optimisation technique that was found to generate good solutions in the simulated test cases, even in the presence of significant random noise. The method was found to be insensitive at low frequencies, which made it ineffective for inverting the real microphone data, although this was shown to be at least partly due to the limitations imposed by the array size. In addition to the harmonic models, an empirical noise prediction method using the spectral scaling laws derived by \citet*{Brooks_1989} was trialled, and was found to be capable of making predictions that were in agreement with the measured data. The model was shown to be sensitive to the exact choice of turbulence parameters used and was also found to require good quality aerodynamic data to make accurate noise predictions. If such data were available however, it is expected that this empirical model would be able to make useful predictions of the noise radiated by a VAWT rotor.
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Bülow, Fredrik. "A Generator Perspective on Vertical Axis Wind Turbines." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-197855.
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The wind energy conversion system considered in this thesis is based on a vertical axis wind turbine with a cable wound direct drive PM generator. Diode rectifiers are used to connect several such units to a single DC-bus and a single inverter controls the power flow from the DC-bus to a utility grid. This work considers the described system from a generator perspective i.e. the turbine is primarily seen as a torque and the inverter is seen as a controlled load. A 12 kW VAWT prototype with a single turbine has been constructed within the project. The power coefficient of this turbine has been measured when the turbine is operated at various tip speed ratios. This measurement determines both how much energy the turbine can convert in a given wind and at what speed the turbine should be operated in order to maximise the energy capture. The turbine torque variation during the revolution of the turbine has also been studied. A PM generator prototype has been constructed in order to study power loss in the stator core at low electrical frequencies. Heat exchange between the stator and the air-gap between the stator and the rotor has been studied. Heat exchange between the stator and the air-gap is increased by turbulence caused by the rotor. The generator was also used in a demonstration of a DC-grid where two diode rectified PM generators supplied power to a single DC load. An initial study of an inverter suitable for grid connection of the 12 kW PM generator has been performed. Several turbine control strategies are evaluated in simulations. The control strategies only require the parameter "turbine speed" to determine the optimal system load.
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Sjökvist, Stefan. "Demagnetization Studies on Permanent Magnets : Comparing FEM Simulations with Experiments." Licentiate thesis, Uppsala universitet, Elektricitetslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-236301.
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In a world where money often is the main controlling factor, everything that can be tends to be more and more optimized. Regarding electrical machines, developers have always had the goal to make them better. The latest trend is to make machines as efficient as possible, which calls for accurate simulation models where different designs can be tested and evaluated. The finite element method is probably the most popular approach since it makes it possible to, in an easy and accurate way, get numerical solutions to a variety of physics problems with complex geometries and non-linear materials. This licentiate thesis includes two different projects in which finite element methods have had a central roll. In the first project, the goal was to develop a simulation model to be able to predict demagnetization of permanent magnets. It is of great importance to be able to predict if a permanent magnet will be demagnetized or not in a certain situation. In the worst case, the permanent magnets will be completely destroyed and the machine will be completely useless. However, it is more probable that the permanent magnets will not be completely destroyed and that the machine still will be functional but not as good as before. In a time where money is more important than ever, the utilization has to be as high as possible. In this study the demagnetization risk for different rotor geometries in a 12 kW direct driven permanent magnet synchronous generator was studied with a proprietary finite element method simulation model. The demagnetization study of the different rotor geometries and magnet grades showed that here is no risk for the permanent magnets in the rotor as it is designed today to be demagnetized. The project also included experimental verification of the simulation model. The simulation model was compared with experiments and the results showed good agreement. The second project treated the redesign of the rotor in the generator previously mentioned. The goal was to redesign the surface mounted NdFeB rotor to use a field concentrating design with ferrite permanent magnets instead. The motivation was that the price on NdFeB magnets has fluctuated a lot the last few years as well as to see if it was physically possible to fit a ferrite rotor in the same space as the NdFeB rotor. A new rotor design with ferrite permanent magnets was presented together with an electromagnetic and a mechanical design.
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Bah, Elhadji Alpha Amadou. "Numerical investigation on the use of multi-element blades in vertical-axis wind turbines." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53501.
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The interest in sustainable forms of energy is being driven by the anticipated scarcity of traditional fossil fuels over the coming decades. There is also a growing concern about the effects of fossil fuel emissions on human health and the environment. Many sources of renewable energy are being researched and implemented for power production. In particular, wind power generation by horizontal- and vertical-axis wind turbines is very popular.
Vertical-axis wind turbines (VAWTs) have a relative construction simplicity compared to horizontal-axis wind turbines (HAWTs). However, VAWTs present specific challenges that may hinder their performance. For instance, they are strongly affected by dynamic stall. A significant part of the kinetic energy contained in the oncoming wind is lost in swirl and vortices. As a result, VAWTs have lower power production compared to HAWTs.
First, the present work is aimed at the study of the aerodynamics of straight-bladed VAWTs (SB-VAWTs). Empirical calculations are conducted in a preliminary work. Then a two-dimensional double multiple streamtube (DMST) approach supported by a two-dimensional numerical study is implemented. The dynamic stall and aerodynamic performance of the rotor are investigated. A VAWT-fitted dynamic stall model is implemented. Computational fluid dynamics (CFD) simulations are conducted to serve as reference for the DMST calculations. This three-pronged approach allows us to efficiently explore multiple configurations. The dynamic stall phenomenon is identified as a primary cause of performance loss.
The results in this section validate the DMST model as a good replacement for CFD analysis in early phase design provided that a good dynamic stall model is used.
After having identify the primary cause of performance loss, the goal is to investigate the use to dual-element blades for alleviating the effect of dynamic stall, thereby improving the performance of the rotor. The desirable airfoil characteristics are defined and a parametric analysis conducted. In the present study the parameters consists of the size of the blade elements, the space between them, and their relative orientation. The performance of the rotor is calculated and compared to the baseline.
The results highlight the preeminence of the two-element configuration over the single-element provided that the adequate parametric study is conducted beforehand.
A performance enhancement is obtained over a large range of tip speed ratios. The starting characteristics and the operation stability are also improved.
Finally, an economic analysis is conducted to determine the cost of energy and thus the financial viability of such a project. The Great Coast of Senegal is selected as site of operation. The energy need and sources of this region are presented along with its wind energy potential. The cost evaluation shows the economic viability by comparing the cost of energy to the current energy market prices.
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Du, Yingkang. "An Orthogonal Savonius-type Wind Turbine: Design and Experiments." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1459510710.
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Halvarsson, Patrik, and Emma Larsson. "Småskaliga vindkraftverk på byggnader i urban miljö : Möjligheter och hinder för ökad implementering." Thesis, KTH, Byggteknik och design, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127036.
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Intresset för småskaliga vindkraftverk på byggnader har ökat under de senaste åren. Allt fler människor blir mer energi- och miljömedvetna samt ser fördelarna med att elektriciteten produceras där den konsumeras; i den bebyggda miljön. Det är dock en större utmaning att installera ett vindkraftverk i urban miljö, jämfört med i öppet landskap, då det finns många faktorer som skall beaktas. Stadens komplexa uppbyggnad gör att vindens hastighet och riktning varierar och ger upphov till turbulenta strukturer i den omgivande luften. Många av dagens vindkraftverk kan ej operera effektivt vid turbulens, därför måste dessa vindkraftverken placeras på höga höjder för att nå den laminärt strömmande vinden över staden, vilket ger orealistiska längder på de master som krävs, även om vindkraftverket monteras på en byggnad. För att kunna utnyttja de vindar som uppkommer i urbana miljöer bör vertikalaxlade vindkraftverk med en helixformad geometri på rotorn användas. Dessa har visat sig vara både de effektivaste och de vindkraftverk som utsätter omgivningen för lägst nivå av störningar. Att placera ett vindkraftverk på en byggnad i urban miljö, där många människor vistas, kräver god kunskap om säkert montage samt vilka störningar som vindkraftverket kan generera. Ett vindkraftverk som monteras felaktigt kan bidra till hälso- och säkerhetsrisker, och om dessa risker blir för stora kan vindkraftverket tvingas att tas ur drift. För att vara säker på att vindkraftsanläggningen är tillförlitligt bör vindkraftverket och montaget vara stadardiserat och certifierat, något som i dagsläget saknas i Sverige. I dag finns inga direkta stöd för småskaliga vindkraftverk i Sverige, vilket är en bidragande faktor till att ekonomin kring dessa vindkraftverk är bristfällig. Elcertifikatsystemet som skall ge stöd åt förnyelsebar energi är inte utformat för småskalig elproduktion. Men i takt med att detta användningsområde för vindkraft utvecklas samt att priset för energi förväntas stiga kommer troligtvis byggnadsmonterade vindkraftverk bli en lönsam investering i framtiden.The interest for small-scale wind turbines mounted on buildings has increased during the last couple of years. More and more people are giving more consideration to energy and environmental questions and are appreciative of the benefits of producing electricity where it is consumed; in the urban environment. However it is a greater challenge to install a wind turbine in the urban environment, compared to an open landscape, because of the many factors that needs to be taken in consideration. The complex structure of the city has an effect on the speed and direction of the wind and causes turbulent structures in the surrounding air. Many of today’s wind turbines cannot operate effectively in turbulence, this is why these turbines need to be placed on high heights to reach the laminar wind flow over the city, which gives unrealistic lengths of the towers that are required, even if the turbine is mounted on a building. To be able to utilize the existing wind in urban environments a vertical axis wind turbine with a helix shaped rotor should be used. These turbines have shown themselves to not only be the most effective but also the turbines that expose the surroundings to the lowest level of disturbances. To place a wind turbine on a building in an urban environment, where a lot of people reside, requires a good knowledge of how to securely mount the turbine but also what kind of disturbances that a turbine can emit. A turbine that is mounted incorrectly can contribute to health and safety hazards, and if these risks become to great the turbine may be forced to be taken out of operation. To be certain that the wind turbine and its components are trustworthy the turbine and mounting should be standardized and certified, a feature that don’t exist today in Sweden. Currently there is no direct support scheme for small-scale wind turbines in Sweden, which is a contributing factor to the inadequate economics surrounding these wind turbines. The Swedish system with certificates is meant to give support renewable energy but the system is not suited for small-scale production of electricity. But the more this field of application for wind turbines develops, together with the assumption of rising cost of energy will most likely make building mounted wind turbines a profitable investment in the future.
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Möllerström, Erik. "Vertical Axis Wind Turbines : Tower Dynamics and Noise." Licentiate thesis, Högskolan i Halmstad, Energiteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-242267.
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Vertical axis wind turbines (VAWTs) have with time been outrivaled by the today common and economically feasible horizontal axis wind turbines (HAWTs). However, VAWTs have several advantages such as the possibility to put the drive train at ground level, lower noise emissions and better scaling behavior which still make them interesting for research. The work within this thesis is made in collaboration between the Department of Construction and Energy Engineering at Halmstad University and the Division for Electricity at Uppsala University. A 200 kW VAWT owned by the latter and situated close to Falkenberg in the southwest of Sweden has been the main subject of the research even if most learnings has been generalized to fit a typical vertical turbine. This particular turbine has a wooden tower which is semi-guy-wired, i.e. the tower is both firmly attached to the ground and supported by guy-wires. This thesis has two main topics both regarding VAWTs: eigenfrequency of the tower and the noise generated from the turbine. The eigenfrequency of a semi-guy-wired tower is studied and an analytical expression describing this is produced and verified by experiments and simulations. The eigenfrequency of the wire itself and how it is affected by wind load are also studied. The noise characteristics of VAWTs have been investigated, both theoretically and by noise measurement campaigns. Both noise emission and frequency distribution of VAWTs has been studied. The work has resulted in analytical expressions for tower and wire eigenfrequency of a semi-guy-wired tower as well as recommendations for designing future towers for VAWTs. The noise emission of VAWTs has been studied and proven low compared to HAWTs. The noise frequency distribution of the 200 kW VAWT differs significantly from that of a similar size HAWTs with for example lower levels for frequencies below 3000 Hz.
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D'Ambrosio, Marco, and Marco Medaglia. "Vertical Axis Wind Turbines: History, Technology and Applications." Thesis, Halmstad University, Halmstad University, School of Business and Engineering (SET), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-4986.
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In this Master Thesis a review of different type of vertical axis wind turbines (VAWT) and a preliminary investigation of a new kind of VAWT are presented.
After an introduction about the historical background of wind power, the report deals with a more accurate analysis of the main type of VAWT, showing their characteristics and their operations. The aerodynamics of the wind turbines and a review of different type on generators that can be used to connect the wind mill to the electricity grid are reported as well.
Several statistics are also presented, in order to explain how the importance of the wind energy has grown up during the last decades and also to show that this development of the market of wind power creates new opportunity also for VAWT, that are less used than the horizontal axis wind turbine (HAWT).
In the end of 2009 a new kind of vertical axis wind turbine, a giromill 3 blades type, has been built in Falkenberg, by the Swedish company VerticalWind. The tower of this wind turbine is made by wood, in order to get a cheaper and more environment friendly structure, and a direct driven synchronous multipole with permanent magnents generator is located at its bottom. This 200 kW VAWT represents the intermediate step between the 12 kW prototype, built in collaboration with the Uppsala University, and the common Swedish commercial size of 2 MW, which is the goal of the company.
A preliminary investigation of the characteristics of this VAWT has been done, focusing in particular on the value of the frequency of resonance of the tower, an important value that must be never reached during the operative phase in order to avoid serious damage to all the structure, and on the power curve, used to evaluate the coefficient of power (Cp) of the turbine. The results of this investigation and the steps followed to get them are reported. Moreover a energy production analysis of the turbine has been done using WindPro, as well as a comparison with and older type on commercial VAWT.
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Apelfröjd, Senad. "Grid Connection of Permanent Magnet Generator Based Renewable Energy Systems." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-304659.
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Renewable energy is harnessed from continuously replenishing natural processes. Some commonly known are sunlight, water, wind, tides, geothermal heat and various forms of biomass. The focus on renewable energy has over the past few decades intensified greatly. This thesis contributes to the research on developing renewable energy technologies, within the wind power, wave power and marine current power projects at the division of Electricity, Uppsala University. In this thesis grid connection of permanent magnet generator based renewable energy sources is evaluated. A tap transformer based grid connection system has been constructed and experimentally evaluated for a vertical axis wind turbine. Full range variable speed operation of the turbine is enabled by using the different step-up ratios of a tap transformer. This removes the need for a DC/DC step or an active rectifier on the generator side of the full frequency converter and thereby reduces system complexity. Experiments and simulations of the system for variable speed operation are done and efficiency and harmonic content are evaluated. The work presented in the thesis has also contributed to the design, construction and evaluation of a full-scale offshore marine substation for wave power intended to grid connect a farm of wave energy converters. The function of the marine substation has been experimentally tested and the substation is ready for deployment. Results from the system verification are presented. Special focus is on the transformer losses and transformer in-rush currents. A control and grid connection system for a vertical axis marine current energy converter has been designed and constructed. The grid connection is done with a back-to-back 2L-3L system with a three level cascaded H-bridge converter grid side. The system has been tested in the laboratory and is ready to be installed at the experimental site. Results from the laboratory testing of the system are presented.Wind Power
Wave Power
Marine Currnet Power
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Hořava, Pavel. "Simulace malé větrné elektrárny se Savoniovým-Darrieovým rotorem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220933.
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This master‘s thesis deals with the simulation of small wind power plant with Savonius-Darrieus rotor. On the base of the actuator disk theory the performance of modeled power plant is predicted in theoretical part and the power coefficient as well. The process of designing the wind model is also described in this theoretical part. The practical part of this thesis is dedicated to the creating a model of DS300 vertical axis hybrid wind turbine in Matlab/Simulink. This model was used to generating of the power curve of modeled wind power plant and for the computing of power and total produced energy during an average and above-average day as well. The whole thesis is enclosed by evaluating of obtained results.
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Kjellin, Jon. "Vertical Axis Wind Turbines : Electrical System and Experimental Results." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182438.
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The wind power research at the division of Electricity at Uppsala University is aimed towards increased understanding of vertical axis wind turbines. The considered type of wind turbine is an H-rotor with a directly driven synchronous generator operating at variable speed. The experimental work presented in this thesis comprises investigation of three vertical axis wind turbines of different design and size. The electrical, control and measurement systems for the first 12 kW wind turbine have been designed and implemented. The second was a 10 kW wind turbine adapted to a telecom application. Both the 12 kW and the 10 kW were operated against dump loads. The third turbine was a 200 kW grid-connected wind turbine, where control and measurement systems have been implemented. Experimental results have shown that an all-electric control, substituting mechanical systems such as blade-pitch, is possible for this type of turbine. By controlling the rectified generator voltage, the rotational speed of the turbine is also controlled. An electrical start-up system has been built and verified. The power coefficient has been measured and the stall behaviour of this type of turbine has been examined. An optimum tip speed ratio control has been implemented and tested, with promising results. Use of the turbine to estimate the wind speed has been demonstrated. This has been used to get a faster regulation of the turbine compared to if an anemometer had been used.
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Jaohindy, Placide. "Modélisation des systèmes éoliens verticaux intégrés aux bâtiments : modélisation du couple production / Bâtiment." Thesis, La Réunion, 2012. http://www.theses.fr/2012LARE0005/document.
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La technique d'intégration des systèmes éoliens verticaux (VAWT) au service des logements individuels, collectifs et tertiaires est une approche intéressante pour les acteurs de la maitrise d'énergie pour promouvoir une utilisation rationnelle de l'énergie. Le choix de l'implantation d'une éolienne en milieu urbain est déterminé par la hauteur des bâtiments, la vitesse du vent et l'intensité de turbulence du site. Les conditions de vents sévères à faible altitude sont favorables à une implantation de VAWT. Dans certaines villes, la hauteur moyenne des bâtiments est relativement faible et ceci fait qu'en ces lieux, les VAWTs sont appréciables par rapport aux HAWTs. La mécanique des fluides numériques (CFD) est mise en œuvre pour modéliser les écoulements d'air au travers d'éoliennes et des bâtiments. Un problème CFD modélisé avec un modèle de turbulence approprié donneront des résultats de simulations qui s'approcheront des réalités physiques et des résultats de l'expérimentation. Dans cette étude, les modèles standard k-" et SST k-! ont été utilisés. Après analyse des possibilités d'intégration d'une VAWT, la toiture reste la zone d'intégration la plus intéressante. En plus de l'étude aérodynamique, nous avons entamé une modélisation électrique de la chaîne de conversion de l'éolienne en utilisant le logiciel Matlab/Simulink. Le travail a été effectué dans le but de déterminer la puissance électrique susceptible d'être produite par l'éolienne. Pour finaliser cette étude, un modèle de couplage électrique de VAWTs avec un bâtiment considéré comme un modèle de charge est présentéThe building integration of the vertical axis wind turbine (VAWT) to supply the individual, collective and tertiary residences consumption is an interesting approach that can help architects and the actors of the energy control to promote a rational use of renewable energy in the in homes. The choice of the location of the urban wind turbine type is determined by building height, wind speed and turbulence intensity of the site. The severe conditions of wind at low altitude are favorable for a VAWT installation. In some cities, the average buildings height is low, in these places, the VAWTs must be appreciable compared to the HAWTs. The modelling of the air flow through the wind turbine and the couple building-wind turbine involves the computation fluid dynamics (CFD). A problem modeled with a suitable turbulence model will give results that approach the physical reality and the experiment results. In this study, the standard k-" and SST k-! models were used. After analyzing the possibilities of VAWT integration, the roof is the most interesting integration area. In addition to CFD method, we have started to study the electrical model of the VAWT. The work was conducted to determine the electrical power generated by the wind turbine using Matlab/Simulink software. To complete the study, a VAWT model coupled with a building where the building is considered as a consumption model is presented
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Möllerström, Erik. "Noise, eigenfrequencies and turbulence behavior of a 200 kW H-rotor vertical axis wind turbine." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316385.
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Vertical-axis wind turbines (VAWTs) have with time been outrivaled by the today more common and economically feasible horizontal-axis wind turbines (HAWTs). However, VAWTs have several advantages which still make them interesting, for example, the VAWTs can have the drive train at ground level and it has been argued that they have lower noise emission. Other proposed advantages are suitability for both up-scaling and floating offshore platforms. The work within this thesis is made in collaboration between Halmstad University and Uppsala University. A 200-kW semi-guy-wired VAWT H-rotor, owned by Uppsala University but situated in Falkenberg close to Halmstad, has been the main subject of the research although most results can be generalized to suit a typical H-rotor. This thesis has three main topics regarding VAWTs: (1) how the wind energy extraction is influenced by turbulence, (2) aerodynamical noise generation and (3) eigenfrequencies of the semi-guy-wired tower. The influence from turbulence on the wind energy extraction is studied by evaluating logged operational data and examining how the power curve and the tip-speed ratio for maximum Cp is impacted by turbulence. The work has showed that the T1-turbine has a good ability to extract wind energy at turbulent conditions, indicating an advantage in energy extraction at turbulent sites for VAWTs compared to HAWTs.The noise characteristics are studied experimentally, and models of the two most likely aerodynamic noise mechanisms are applied. Here, inflow-turbulence noise is deemed as the prevailing noise source rather than turbulent-boundary-layer trailing-edge noise (TBL-TE) which is the most important noise mechanism for HAWTs. The overall noise emission has also been measured and proven low compared to similar sized HAWTs. The eigenfrequencies of a semi-guy-wired tower are also studied. Analytical expressions describing the first-mode eigenfrequency of both tower and guy wire has been derived and verified by experiments and simulations.
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Christoffer, Fjellstedt. "Simulations of vertical axis wind turbines with PMSG and diode rectification to a mutual DC-bus." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-323735.
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Transient simulations were performed with MATLAB Simulink on a mutual wind park topology, where three vertical axis wind turbines equipped with permanent magnet synchronous generators were connected to a mutual DC-bus through passive diode rectification. The aim with the work was to show the effects of two different kinds of loads on the system in respect to generator torque, rotor speed, produced power by the generators and the power on the DC-bus. The loads were a variable voltage source and a resistance with the value 2.0 Ω. It was shown that the transient behavior of the system in respect to both kinds of loads exhibited a high level of stability when the wind speed was altered. It was also shown that the system when equipped with a voltage source load began to oscillate with the natural frequency of a two mass rotating spring system if a sudden increase of the voltage made the DC-bus voltage larger than the peak of the internal induced voltage of the generators. Small variations of the DC voltage however exhibited a stable behavior.
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Rastegar, Damoon. "Modification of Aeroelastic Model for Vertical Axes Wind Turbines." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3388.
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In wind turbines, flow pressure variations on the air-structure interface cause aerodynamic forces. Consequently the structure deforms and starts to move. The interaction between aerodynamic forces and structural deformations mainly concerns aeroelasticity. Since these two are coupled, they have to be considered simultaneously in cases which the deformations are not negligible in comparison to the other geometric dimensions. The purpose of this work is to improve the simulation model of a vertical axis wind turbine by modifying the structural model from undamped Euler-Bernoulli beam theory with lumped mass matrix to the more advanced Timoshenko beam theory with consistent mass matrix plus an additional damping term. The bending of the beam is then unified with longitudinal and torsional deformations based on a fixed shape cross-section assumption and the Saint-Venant torsion theory. The whole work has been carried out by implementing the finite element method using MATLAB code and implanting it in a previously developed package as a complement. Finally the results have been verified by qualitative comparisons with alternative simulations.
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Kazlova, Ala, and Bettina Ullmann. "When Wind Goes Vertical: : Can a start-up company make use of its born global potential to revolutionize the wind turbine industry?" Thesis, Linnéuniversitetet, Ekonomihögskolan, ELNU, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-6605.
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The 21st century would be a nightmare for Don Quijote: thousands of windmills are installed all over the globe and the number will increase tremendously over the next years. If climate change was an issue in the early 17th century, Don Quijote might have specialized in fighting nuclear or fossil fuel power plants. The change in power production is clearly pronounced, and it inspires the market to respond immediately. Numerous wind turbine manufacturers emerge, developing one technological innovation after another. The trend clearly goes in one direction: horizontal axis wind turbines in all possible variations. However, there are a few companies that do not follow the mainstream – they swim against the current and introduce new concepts, with the potential to set new standards in the industry. Nevertheless, the question whether these companies can establish operations and survive in an industry dominated by large multinational corporations arises. If these companies want to become recognized, they need to compete on an international scale from the outset – they become born globals. This master’s thesis investigates the preconditions under which an innovative start-up company can become born global in the wind turbine industry. For that, distinctive resources and capabilities of such companies, as well as key success factors for the industry are defined. Furthermore, enhancing or restricting parameters lying within company’s environment – in particular, within its networks – are discovered. These findings are based on and supported by the case study of an innovative vertical axis wind turbine manufacturer. In addition, the influence of this company’s university spin-off origin is investigated.
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Andersson, Carl, and Mikael Sahlin. "Vid vägskälet : vart du kommer från påverkar vart du bör gå." Thesis, Högskolan i Borås, Institutionen Handels- och IT-högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-19411.
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SYSteam DTS AB är ett IT-konsultföretag etablerat i Borås. De har cirka 35 anställda,cirka 300 kunder och erbjuder verksamhetsanpassade helhetslösningar inom IT-området.Varje års affärsplan behöver som oftast skrivas ihop under en kort tid vilket medför attunderlaget kanske inte innehåller exakta och uppdaterade uppgifter. Tidsfaktorn påverkaralltså affärsplanens kvalitet.Genom att definiera den typiska kunden till DTS inom modebranschen fastställs likhetermellan kunderna. Därigenom går det att identifiera vilket typ av företag DTS inriktar sigmot och hur mycket pengar det finns kvar att tjäna på dem. Det är nu också möjligt attidentifiera företag som inte är kunder i dagsläget men som har stora likheter med dentypiska kunden, samt hur mycket pengar som finns att tjäna på dem. Informationenfungerar främst som beslutsunderlag för DTS gällande vilken affärsmöjlighet de börprioritera om att antingen satsa på att utöka försäljningen på befintliga kunder eller satsapå nya kunder.Uppsatsens syfte är att visa hur företag kan gå tillväga för att identifiera vissa styrkor ochframgångsfaktorer. Uppsatsen använder två olika synsätt, positivism och hermeneutikoch har ett empiriskt perspektiv då den tillämpar en deduktiv ansats. För att definiera dentypiska kunden och liknande icke-kundföretag samt försäljningsmöjligheter på demanvänds en kvantitativ datainsamlingsmetod. Även en kvalitativ metod används, närföretag som representerar den typiska kunden intervjuas för att ta reda på vad de anser fåut av samarbetet med DTS. Den teoretiska referensramen består av en genomgång avföretagsekonomiska begrepp, såsom SWOT-verktyget, DPM-matrisen och inre/yttreeffektivitet.Analysen visar att satsning på befintliga kunder är den bästa affärsmöjligheten.Anledningen är bland annat att DTS bör förstärka sitt varumärke och sin inre effektivitetinnan de satsar på nya kundrelationer. Dessutom är det både dyrare och svårare atterbjuda tjänster och produkter till icke-kundföretag då de redan har IT-leverantörer DTSmåste konkurrera ut. För övrigt är det även tidskrävande att arbeta upp nya arbetsrutineroch kundrelationer.
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Aboujaoude, Hady. "Contribution à l’amélioration des performances aérodynamiques d'une éolienne Savonius à l'aide d'un déflecteur axisymétrique." Electronic Thesis or Diss., Reims, 2024. http://www.theses.fr/2024REIMS018.
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Face aux enjeux environnementaux actuels et à la croissance constante de la demande énergétique, le développement de sources d'énergie renouvelable s'impose comme une priorité. Parmi ces sources, l'énergie éolienne occupe une place de choix. Cependant, l'implantation d'éoliennes en milieu urbain pose des défis spécifiques liés à la nature intermittente et turbulente du vent en ville.C'est dans ce contexte que cette thèse se penche sur l'optimisation des éoliennes Savonius, un type d'éolienne à axe vertical particulièrement adapté aux environnements urbains en raison de sa robustesse et de sa capacité à fonctionner à basse vitesse de vent.L'objectif principal de cette recherche était d'améliorer significativement le rendement de ces éoliennes en concevant des déflecteurs aérodynamiques optimisés. En combinant des simulations numériques avancées (CFD) et une approche méthodologique rigoureuse, les chercheurs ont pu étudier en détail l'interaction entre le vent, l'éolienne et le déflecteur.Les résultats obtenus sont prometteurs. Les déflecteurs optimisés ont permis d'augmenter considérablement la production d'énergie des éoliennes Savonius, tout en réduisant les contraintes structurelles. Cette avancée ouvre de nouvelles perspectives pour le déploiement de ces éoliennes en milieu urbain, où l'espace est limité et où la production d'énergie locale est particulièrement recherchée.En résumé, cette thèse apporte une contribution significative au domaine de l'énergie éolienne en démontrant le potentiel des éoliennes Savonius équipées de déflecteurs optimisés pour répondre aux besoins énergétiques des villes. Les résultats de cette recherche ouvrent la voie à un avenir énergétique plus durable et plus résilientIn the face of growing environmental concerns and increasing global energy demand, the transition towards renewable energy sources has become a pressing global issue. Among these sources, wind energy stands out for its ability to provide clean and renewable electricity. However, integrating wind turbines into urban environments presents unique challenges, particularly in terms of efficiency and reliability due to the often irregular and turbulent nature of urban winds.This thesis focuses on optimizing Savonius wind turbines, a type of vertical-axis wind turbine well-suited for urban environments due to their robustness and ability to operate at low wind speeds. The primary objective of this research was to significantly enhance the performance of these turbines by designing optimized aerodynamic deflectors.Through advanced computational fluid dynamics (CFD) simulations and a rigorous methodological approach, the researchers were able to thoroughly investigate the interaction between the wind, the turbine, and the deflector.The results obtained are promising. The optimized deflectors led to a substantial increase in the energy output of Savonius wind turbines, while simultaneously reducing structural stresses. These advancements open up new possibilities for the widespread deployment of these turbines in urban areas, where local energy production is highly desirable.In conclusion, this thesis makes a significant contribution to the field of wind energy by demonstrating the potential of Savonius wind turbines equipped with optimized deflectors to meet the energy needs of cities. The findings of this research pave the way for a more sustainable and resilient energy future
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dal, monte andrea. "Development of an open source environment for the aero-structural optimization of wind turbines." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3425842.
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An advanced open source optimization environment, for the design of Horizontal and Vertical Axis Wind Turbines, is hereby presented: several geometric parameters can be used as design variables while the proposed objective functions allow to run a multi-disciplinary study considering structural and aerodynamic analysis and the impact of the design on the total cost.
In order to improve the performances of the considered wind turbine model, the airfoils can be parametrized in serveral ways and both in-house functions and open source tools are integrated in the optimization environment, based on DAKOTA. A BEM code evaluates the aerodynamic performances of the HAWT blades and it can be coupled with both FEM analysis and functions for the analysis of the cost of energy. The open source CFD code OpenFOAM has also been included, as a module, in the overall environment: a CFD analysis can be run in an completely automatic way, from the denition of the geometry, through the generation of the mesh and the solving phase to the post-processing analysis.
The proposed optimization environment succeeded in improving the performances of both the considered Horizontal and Vertical Axis Wind Turbines in terms of structural, aerodynamic and cost objective functions.Nella tesi è presentato un ambiente avanzato per l'ottimizzazione delle turbine eoliche sia ad asse orizzontale che verticale. Le variabili di design sono rappresentate da diversi parametri geometrici mentre le funzioni obiettivo implementate permettono di eseguire un’analisi multidisciplinare considerando gli aspetti strutturali, aerodinamici e l'impatto del design sul costo complessivo. Allo scopo di aumentare le prestazioni delle turbine considerate, i profili aerodinamici possono essere parametrizzati in diversi modi. Diverse funzioni appositamente sviluppate e tools open source sono stati integrati nell'ambiente di ottimizzazione, basato su DAKOTA. Un codice BEM valuta le prestazioni aerodinamiche dei modelli ad asse orizzontale e può essere accoppiato sia con codici FEM, sia con funzioni allo scopo di valutare il costo dell’energia. Il codice CFD open source OpenFOAM è stato incluso, come modulo, nell’ambiente: un analisi CFD può essere eseguita in un modo completamente automatico dalla definizione della geometria, generazione della mesh, fase di risoluzione numerica all’analisi dei risultati. L’ambiente di ottimizzazione proposto ha dimostrato di poter migliorare le prestazioni di entrambi i modelli di turbina eolica considerati, in termini di obiettivi strutturali, aerodinamici e di costo.
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Hamidi-Nia, Gilda. "Vart tog aktivisterna vägen?" Thesis, Stockholms universitet, Institutionen för mediestudier, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-130936.
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Fem år har gått sedan hela världens strålkastare riktades mot länder i Mellanöstern och Nordafrika. Storögda och förväntansfulla var världspubliken när de såg hur tiotusentals människor samlades runt flera gator och torg och krävde att få sina röster hörda och att de styrande diktatorerna skulle avgå. Det skanderades då, år 2011, om demokrati och frigörelse från decennielånga förtryck. Men i dagens Egypten vittnar människor om att det under de här fem åren regredierat till ett lika illa, om inte värre, samhälle än innan. Oppositionella röster motverkas och tystas genom att sprida skräck hos dem som en gång vågat tala. En oförutsägbar statsapparat fängslar, griper och styr. Tunisien lyckades som det enda land att reformera statsskicket och gå från diktatur till ett demokratiskt styre. Men däremot är vissa viktiga institutioner, som polisväsendet, kvar i det gamla och påverkar de som redan är utsatta då landet befinner sig i ett politisk och ekonomisk limbo. I flera andra länder i regionen, brinner det än i dag fullbordade inbördeskrig. Vilka var det som så hängivet stod där på torgen och dessutom inspirerade fler till att ansluta sig? Och hur gick det sen för dem och deras länder?
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Krüger, Pontus. "VART TAR PENGARNA VÄGEN?" Thesis, Malmö högskola, Fakulteten för hälsa och samhälle (HS), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-26384.
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Penningtvätt i Sverige är sedan tidigare föga utforskat. I denna studie är syftet att undersöka penningtvätt i Sverige vad det gäller brottsstrukturen, gärningspersoner samt statistiska samband för dessa. Studien är ett uppdrag utfärdat av Länskriminalpolisen i Skåne. Materialet har bestått av straffrättsliga domslut hämtade ifrån Blendow Lexnovas rättsfallsdatabas. Utifrån domsluten kodades variabler vilka matades in i SPSS där statistiska analyser genomfördes. Resultaten visar bland annat att mest pengar återinvesteras i företag, gärningspersonerna är typiskt män i 40-årsåldern med brottslig bakgrund samt det finns ett flertal statistiska samband mellan olika aspekter av brottsstrukturen för penningtvätt. I diskussionen framhävs att resultaten möjligen kan användas i uppdragsgivarens operativa verksamhet samt att mer forskning generellt behövs om penningtvätt. En slutsats som dras är att resultaten bör generaliseras med försiktighet då brister återfinns i materialet.Money laundering in Sweden has previously been little explored. The purpose of this study is to investigate money laundering in Sweden in terms of crime structure, perpetrators and statistical correlations for these. The study is a commission issued by the County Criminal Police in Skåne. The material has consisted of criminal judgments downloaded from Blendow Lexnova’s database of court cases. Variables were encoded which were entered in SPSS where statistical analyses were conducted, based on the criminal judgments. The results demonstrate, among other things, that most of the money is precipitated in companies, the perpetrators are typically men which are 40 years of age with criminal background and there are a number of statistical correlations between the different aspects of crime structure for money laundering. In the discussion, following things are highlighted: the results can possibly be used in the operational activities of CCP and more research is needed on money laundering in general. A conclusion to be drawn is that the results should be generalized with caution when deficiencies are found in the material.
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Sandqvist, Sofia. ""Vad har ni valt?"." Thesis, Malmö högskola, Fakulteten för lärande och samhälle (LS), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-27213.
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Studiens syfte är att analysera valtavlans funktion samt position ur ett delaktighets- och maktperspektiv. För att precisera syftet har jag utgått från frågeställningarna; Vilken funktion har valtavlan ur ett delaktighetsperspektiv? och Hur kommer makt till uttryck genom valtavlan? Utifrån begreppen makt och delaktighet med användbara analytiska verktyg jag synliggjort hur valtavlan skapar makt individer emellan och hur delaktigheten kommer till uttryck. Metoden som används är kvalitativ och empirin som används i analysen har samlats in genom observationer på en förskola i Skåne.I studien kan jag se att alla individer är styrda av valtavlans regler, vilket försvårar barns möjlighet till delaktighet i förskolan. Makten att möjliggöra delaktighet har visat sig inte enbart ligga hos pedagogerna utan kontexten i vilken individerna vistas i. Med en tanke på att även de är styrda av regler och normer och hur en normalisering av dessa verkar ha skett, finns det svårigheter för dem att möjliggöra barns delaktighet. Genom valtavlan förenklas en styrning mellan barn och pedagog men även mellan barn och barn.
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Göransson, Robert, Jonas Ljungfeldt, and Sebastian Ödquist. "Agil metodanpassning, vart finns riskerna? En fallstudie om vart risker uppstår vid agil metodanpassning?" Thesis, Örebro universitet, Handelshögskolan vid Örebro Universitet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-65072.
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Åkerström, Jenny, and Lena Gröndahl. "Repatriering : Vart tar kunskapen vägen?" Thesis, Uppsala University, Department of Business Studies, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7869.
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Globaliseringen innebär möjligheter för företag att verka på en större marknad, men detta innebär också att organisationen blir mer utspridd och svårkontrollerad. Ett ökat fokus på kunskap som resurs för att skapa konkurrensfördelar samt att använda expatriering som ett verktyg för hantering av den utspridda organisationen har lett fram till valet av syfte med denna uppsats. Vi vill utifrån vår modell över hur repatrioters kunskap kan överföras och bidra till organisationens utveckling, beskriva och analysera hur företag idag tar tillvara på repatrioters kunskap. Vi har valt att göra vår undersökning på företag noterade på Stockholmsbörsen som använder sig av expatriering utanför Norden.
Som grund för vår modell ligger teori om den kunskap repatrioter införskaffar under utlandstjänstgöring, hur kunskap kan överföras samt hur den kan utveckla organisationen och stärka dess konkurrenskraft. Utifrån vår modell har vi sedan skapat ett frågeformulär som ligger till grund för vår empiri. Frågeformuläret besvarades av 18 företag och resultatet visar att respondenterna överlag anser att repatrioters kunskaper gynnar organisationen samt att den bidrar till en stärkt konkurrenskraft. Trots detta är det enbart 3 av de 18 företagen som har en formell strategi för kunskapsöverföring vid repatriering. Ett flertal av företagen använder sig däremot av informella metoder, då främst genom personifierad kunskapsöverföring. Detta kommer dock troligtvis att ändras då många av företagen uppgett att de inom de närmsta fem åren med stor sannolikhet kommer att utveckla en strategi för kunskapsöverföring vid repatriering. Behovet av en bättre genomarbetad strategi tycks komma av en framtida utökad användning av expatriering inom organisationen.
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Törnert, Roger. "Vart är skolan på väg." Thesis, Linköpings universitet, Institutionen för beteendevetenskap och lärande, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-145663.
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Utgångspunkten för min uppsats är följande frågeställningar: Står utbildningen inför en total förändring ”ett paradigmskifte” vad gäller inriktningen på gymnasieskolans innehåll och verksamhet? Hur har i så fall detta paradigmskifte vuxit fram? Hur hanterar skolan de nya risker som uppstår i anslutning till att samhället gått in i en ny modernitet? Hur förhåller sig gymnasieskolan till det postmoderna nya individualiserade samhället? Förutom styrdokument har min undersökning utgått från litteratur som analyserar samhället utifrån postmodernistiska teorier. Resultatet av undersökningen visar att ett paradigmskifte från jämlikhetsideologi till kunskapsideologi håller på att utvecklas på gymnasieskolan. Paradigmskiftet innebär att gymnasieskolan återgår till en klassisk modernitet som står i konflikt till eleverna som är de främsta bärarna av postmodernismen. Att inte uppnå kunskapsmålen definierar regeringen (Björklund) som det nya gymnasiets största risk. Problemen/riskerna med det nya gymnasiet ska främst hanteras genom t åtgärdsprogram och uppdelningen av gymnasiet i studieförberedande- och yrkesprogram.
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Siegfried, Ellinor, Andreas Svenberg, and Gabriella Tjernbäck. "Motivationens pussel : Vad passar vart?" Thesis, Örebro universitet, Restaurang- och hotellhögskolan, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-33334.
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Motivation kräver engagemang, mål och att ha kunskap att agera. En anställd behöver alla tre delarna för att bli motiverad. I hotell- och restaurangbranschen är det viktigt med motiverade anställda, då de är organisationens ansikte utåt. Syftet med studien var att undersöka hur motivation fungerar och bör användas inom hotell- och restaurangbranschen. Fem vetenskapliga artiklar i ämnet valdes ut, studerades och diskuterades med avsikt att besvara syftet. Det visade på hur betydande det är för en organisations framgång att motivera sin personal för att de skall vilja stanna kvar i branschen. Slutsatsen visade att hotell- och restaurangbranschen är beroende av motiverade och engagerade anställda. Det är dessa anställda som bemöter och ger service till gästen.B-uppsatser
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Westin, Philip. "Nätra – Vart tog järnåldern vägen?" Thesis, Umeå universitet, Institutionen för idé- och samhällsstudier, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-187660.
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Nätra was one of the larger parishes in Västernorrland during the Middle Ages and have a ruin of an medieval church next to Nätraån in height with Bjästa, which during medieval times served as a gathering place for the surrounding villages. If you look at registered settlements, there are no remains that prove that Nätra have had permanent iron age settlements. Has Nätra been uninhabited before the medieval church was built? Where did the Iron Age go? The work intends to investigate which indicators there is for Nätra to have been inhabited during the Iron Age - with the medieval church as the entry point.
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Rashid, Sumaya. "Vart är den muslimska mångfalden?" Thesis, Södertörns högskola, Institutionen för kultur och lärande, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-35584.
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Akdemir, Bulduk, and Boris Filipovic. "Humankapital : Vart är utvecklingen på väg?" Thesis, Högskolan i Borås, Institutionen Handels- och IT-högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-19519.
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En tillbakablick på den ekonomiska utvecklingen ger en klar bild av att ekonomin har utvecklats från ett industribaserat samhälle till ett mer komplext samhälle med större krav på kompetens från anställda. Ett sådant samhälle kallas för ett kunskapsintensivt samhälle och har sedan början av 1990-talet växt allt starkare. Redovisningen har däremot halkat efter och det gör den fortfarande. Än idag finns det inga standarder eller normer som kan användas för att framhäva en av företagets viktigaste resurser, nämligen humankapital.Kunskap, skicklighet och innovativ samt de anställdas förmåga är beteckningen för humankapital. Även värderingar, kultur och filosofi inom företaget sammanhänger med benämningen. Med andra ord så är företagets personal, som inte är ägt av företaget, det som kännetecknar humankapital.Syftet med uppsatsen är att bidra med en förståelse för hur redovisningen av humankapitalet har gått till samt att belysa om hur utvecklingen har sett ut. Slutligen har uppsatsen som syfte att ge en beskrivning av vart utvecklingen av en humankapitalanpassad redovisning är på väg.Vi har använt oss av hermeneutisk synsätt då vi har haft ett tolkande synsätt. Först sammanställde vi den teoretiska referensramen för att sedan gå ut i verkligheten och se hur teorin tillämpas och slutligen återkomma till teorin för att få förståelse kring tillvägagångssätten. Till uppsatsen anser vi att kvalitativa metoden passar bäst då syftet är att upplysa om utvecklingen av humankapitalet.Det finns lagstadgat information om humankapital som måste förekomma i årsredovisningar som oftast kompletteras med textuell information. Den textuella informationen är oftast utsprid i hela årsredovisningen och svenska företagen nöjer sig med sådana årsredovisningar. Utvecklingen av humankapital har gått spikrakt uppåt under 1990-talet för att sedan sjunka under 2000-talet. Det är inte heller mycket som tyder på att utvecklingen kommer att ändra riktning i framtiden då intressenterna ser ut att bli tillfredsställda av den information som redan ges. Så länge som rapporteringen angående humankapitalet är frivilligt kommer företag att ta den enklare vägen eftersom rapportering av humankapitalet är inte det enklaste att ta fram.
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Railert, Philip, Dennis Andersson, and Zakari Kristian Wikström. "Vart tog aktieägarna vägen under 2020?" Thesis, Umeå universitet, Företagsekonomi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184606.
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Syftet med studien var att undersöka vilka typer av bolag som har fått flest antal nya aktieägare på den svenska börsmarknaden under år 2020. Syftet vad vidare att undersöka vilka faktorer som avgjort vilka bolag som fått fler respektive färre nya aktieägare under år 2020. Studien baserar sig på ett urval av aktiebolag noterade på Nasdaq Stockholm, urvalet har hämtats från Nasdaq Stockholms som i sin tur blivit insamlad från databasen Thomas Reuters Eikon. Studien har innefattat ett flertal variabler som vi bedömt intressanta att undersöka för att se vilka egenskaper individuella investerare söker när de vill börja investera igen efter nedgången som uppstod efter att världsekonomin bromsade in i samband med COVID-19s intåg i det globala samhället. Vi fann att, statististiskt sett, beter sig investerarna liknande som i tidigare studier avseende volatilitet. Vidare ser vi att i många fall söker sig investerarna till liknande företag som tidigare, även om det också finns fall av contrarian trading. I våra statistiska undersökningar finner vi signifikanta bevis för att investerare söker sig efter företag med hög lönsamhet samt företag som ger ut utdelning. Detta känns igen från tidigare studier som tar upp att efter den initiala nedgången, så söker sig investerare gradvis tillbaka till de företag och aktier de känner till sen tidigare. På så sätt känner vi att arbetet bidrar till att stärka befintliga teorier om att även i det nya informationssamhället kan man skönja liknande beteendemönster från tidigare kriser. Volatilitet på aktiemarknaden har existerat lika länge som aktiemarknaden själv. Det finns tidigare studier som förklarat hur investerarbasen förändrats under tidigare kriser. Coronapandemin däremot en ny kris som är helt annorlunda tidigare kriser. Få tidigare studier har haft ett perspektiv på Sverige. År 2020 var ett volatilt år där aktiemarknaden i världen och inte minst i Sverige föll mycket snabbt under en kort tid för att sedan återhämta sig snabbt. Trots den höga volatiliteten på marknaden ökade antalet sparare kraftigt under samma år. Avsikten med denna studie är därför att undersöka vilka aktiebolag noterade på Nasdaq Stockholm som har fått flest antal nya ägare samt undersöka om det finns något som förenar dessa bolag med varandra. Studien har en kvantitativ metod samt ett positivistiskt synsätt med en deduktiv ansats. Vidare presenterar studien tidigare forskning kring sparande, risk, diversifiering och volatilitet för att sedan koppla den tidigare forskningen till studiens frågeställning.
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Paula, Guilherme de. "Comportamento em fratura do aço VART 100." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-14012015-144142/.
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Ao longo dos anos o crescente interesse pelo aumento das propriedades mecânicas de resistência dos aços, bem como busca por uma tenacidade à fratura aumentada, tem levado o desenvolvimento de novos aços de ultra-alta resistência. Essa classe de aços se demonstra bastante adequada a uma série de aplicações em componentes de alta responsabilidade, como os da indústria aeronáutica. O aço VART 100 é um desenvolvimento da Villares Metals S.A. e é um aço diferenciado, por seu maior teor de níquel, cromo e molibdênio e pela introdução de cobalto em sua composição química que se apresenta como um aço nacional para substituição com vantagens do aço SAE 300M. No mercado internacional existe um aço que tem sido utilizado para este tipo de aplicação com grande sucesso que é o aço AerMet 100. Vários ciclos de tratamentos térmicos podem ser utilizados no VART 100 levando a uma elevada resistência mecânica que pode ter sérias implicações na sua tenacidade à fratura e resistência a fadiga. Este trabalho faz parte de um estudo maior do aço VART100, onde as propriedades mecânicas de tenacidade ao impacto, tenacidade à fratura, vida em fadiga e resistência a propagação de trinca por fadiga estão sendo estudados. Especificamente neste trabalho foram realizadas analises microestruturais, ensaios de dureza Rockwell, ensaios de tração, propagação de trinca por fadiga, curvas da/dN x ΔK e de tenacidade à fratura,KIC, além da avaliação dos micromecanismos de fratura. Os resultados da análise microestrutural mostrou que os grãos da austenita anterior possuem um tamanho médio de 11,6 μm e uma distribuição homogênea de finos precipitados na matriz de martensita envelhecida. Os parâmetros de resistência mecânica obtidos no ensaio de tração do aço VART 100 se apresentaram muito similares aos dos aços SAE 300M e AerMet 100, entretanto os parâmetros de ductilidade apresentaram valores superiores em relação tanto ao 300M quanto em relação ao Aermet 100. Do ensaio de tenacidade à fratura, observa-se que em relação ao aço SAE 300M, o aço VART 100 apresenta uma superior tenacidade à fratura, entretanto com relação ao AerMet 100, ainda que os parâmetros de resistência são similares, o AerMet 100 apresenta uma destacada superioridade na tenacidade à fratura (cerca de 57% superior). Dos parâmetros obtidos nos ensaios de propagação de trinca por fadiga, observamos que os valores de ΔK0 da Região I são semelhantes independente das direções ensaiadas R-C e LR, mas há uma pequena redução nesse valor quando a razão de carga aumentou de 0,1 para 0,5. A região de Paris foi insensível a variação da razão de carga. Assim, os parâmetros C e m obtidos na Região II, fornece valores bastante similares, que comparados através da utilização da equação de Forman modificada, nos permite notar um desempenho levemente superior do Aermet 100 comparado ao VART 100.Over the years a growing interest in increasing the mechanical strength of steels, as well as, the search for an increased fracture toughness, has led to the development of new ultra-high resistance steels. This class of steels demonstrated to be well suited to a variety of applications in components of high responsibility, such as the ones for the aerospace industry. The VART 100 steel is a Villares Metals S.A. development and is a distinctive steel, for its higher content of nickel, chromium and molybdenum and the introduction of cobalt and Ti in its chemical composition that presents as a national option for replacement, with advantages, for the SAE 300M steel . In the international market there is a steel that has been used for this type of application with great success, it is named AerMet 100. Different heat treatment cycles can be used in VART 100 leading to high mechanical resistance that may cause serious implications on their fracture toughness and fatigue resistance. This work is part of a larger study with the VART100 steel, where the mechanical properties, such as impact resistance, fracture toughness, fatigue life, and fatigue crack propagation resistance are being studied. Specifically in this work the microstructural analysis, Rockwell hardness testing, tensile, fatigue crack propagation curves da / dN x ΔK and fracture toughness, KIC, were carried out. The microstructural results showed that the prior austenite grains have an average size of 11.6 μm and a homogeneous distribution of fine precipitates in a aged martensite matrix. The mechanical strength obtained in the tensile test of the VART 100 steel are very similar to both the SAE 300M steels and AerMet 100, however the ductility parameters showed higher values than the ones for 300M and Aermet 100 steels. From the fracture toughness test, it was observed that the VART 100 exhibits superior fracture toughness than the SAE 300M, but in relation to the AerMet 100 steel, although the strength parameters are similar, the AerMet 100 presented an outstanding superior fracture toughness (about 57% higher). From the fatigue crack propagation tests, we observed that the values of K0 (Region I) are similar regardless of the tested R-C and L-R directions, but there is a small reduction in value when the load ratio increased from 0.1 to 0.5 . The Paris region was insensitive to variation of the load ratio. Thus, the C and m parameters, obtained in Region II, provided very similar values, if compared by using the modified Forman equation, allows us to observe a slightly higher performance of AerMet 100 when compared to VART 100.
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Braga, José Renato Garcia. "Navegação autônoma de VANT por imagens LiDAR." Instituto Nacional de Pesquisas Espaciais (INPE), 2016. http://urlib.net/sid.inpe.br/mtc-m21c/2018/05.18.16.04.
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Nas últimas décadas, observou-se um aumento gradativo na utilização de Veículo Aéreo Não Tripulado (VANT) em diversas áreas, entre elas, monitoramento do uso da terra, operações de busca e resgate, acompanhamento de impactos ambientais, vigilância de fronteiras, entre outras. Há expectativas no aumento do emprego de VANT em aplicações civis e militares devido ao baixo custo de desenvolvimento e operacional, quando comparados com aeronaves tripuladas. A ausência de tripulação embarcada durante o emprego de VANT, principalmente em missões de grande periculosidade, também é uma vantagem, pois diminui os riscos à vida humana. Com o aumento do emprego de VANT o desenvolvimento de sistemas para a sua navegação autônoma tem sido tema de diversas pesquisas. Uma das tarefas dos sistemas de navegação autônoma de VANT é estimar sua posição. A grande maioria dos sistemas de navegação autônoma de VANT utilizam a fusão de dados do Sistema de Navegação Inercial (INS, do inglês, Inertial Navigation System) com os dados do Sistema de Navegação Global por Satélite (Global Navigation Satellite System) (principalmente o Sistema de Posicionamento Global (GPS, do inglês, Global Positioning System)) para estimar a posição do VANT. Mas o GNSS pode sofrer interferência em seu sinal devido a ataques maliciosos e a fenômenos naturais. O desenvolvimento de um sistema de visão computacional, que utiliza imagens capturadas e processadas em tempo de voo para determinar a localização do VANT, pode substituir a informação do GNSS. Entretanto, ainda é um desafio o desenvolvimento de um sistema de estimação da posição do VANT por processamento de imagens para operar durante a navegação da aeronave sobre regiões cobertas por água (por exemplo, o oceano) e em condições de baixa ou sem luminosidade. Neste contexto, esta tese de doutorado apresenta uma metodologia que estima a posição geográfica de um VANT quando este sobrevoa regiões cobertas por água e regiões com baixa ou sem luminosidade utilizando imagens provenientes de um sensor ativo denominado Light Detection And Ranging (LiDAR). A metodologia proposta utiliza a fusão de dados, por um Filtro de Partículas Não-Extensível (FPNE), de duas técnicas de visão computacional, odometria visual e registro automático de imagens, para estimar a posição da aeronave. O sistema de estimação da posição requer que o processamento seja feito em sistemas embarcados e em tempo de voo, por este motivo, a metodologia proposta é desenvolvida em computadores portáteis e de baixo consumo e que permitam a computação de alto desempenho. Para a validação da metodologia proposta são realizados testes com dois conjunto de dados diferentes: o primeiro com dados reais do voo de VANT, mas capturado por uma câmera de vídeo; o segundo, uma simulação utilizando imagens de um sensor LiDAR. Os resultados obtidos com as técnicas empregadas mostram-se promissores para emprego na navegação autônoma de VANT em regiões cobertas por água ou e em regiões com baixa ou sem luminosidade.In the last years, there was a gradual increase in the employment of Unmanned Aerial Vehicles (UAV) in several areas, among them, land-use monitoring, search and rescue operations, monitoring of environmental impacts, border surveillance, and others. There is an expectation that the use of UAVs will increase in the future, due to the low costs of development and low operational costs when compared to manned aircraft. The main advantage of the UAV employment is the absence of onboard crew, which reduces the risks to human life. With the increase of UAV employment, the development of systems for its autonomous navigation has been subject of several investigations. One of the tasks of autonomous navigation systems for UAV is to estimate its position. The main strategy applied for estimating the UAV position is the use of information from Inertial Navigation System (INS) combined with information from Global Navigation Satellite System (GNSS).The signal of GNSS can suffer an outage due to malicious attacks and natural phenomena. Thus, the development of a computer vision system, which uses images captured and processed in flight time, can be used to determine the UAV location and replace the information from GNSS. However, the development of a computer vision system for estimating the UAV position in a situation of flight over water-covered areas (eg the ocean) and flight in low light conditions is a challenge. In this context, this doctoral thesis presents an approach for estimating the geographical position of a UAV, when it flies over regions covered by water and regions with low light conditions. The approach uses images from an active sensor called Light Detection And Ranging (LiDAR) to allow the flight in those conditions. The proposed approach estimates the aircraft position by employing data fusion of two techniques of position estimation by computer vision: visual odometry and the image matching. The data fusion algorithm is performed by an Non-Extensible Particle Filter (NEPF). The approach requires that the processing be done in embedded systems and in flight time, thus, the proposed method is developed in portable and low-power high-performance computer. For the validation of the proposed method, two different data sets are applied: the first one composed by real flight data from an UAV, with images captured by its video camera; and the second one, a simulation using images from a LiDAR sensor. The approach results are promising for the UAV position estimation in regions covered by water or in regions with low light conditions.
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Stenius, Johanna. "Pressfotograf eller fotojournalist : vart är yrket på väg?" Thesis, Södertörn University College, School of Communication, Media and it, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-3865.
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Studien handlar om pressfotografer i Sverige idag. Den blickar bakåt på debatten kring pressfotografer i historien, studerar pressfotografers arbete och diskuterar framtiden. Huvudfrågorna är:
- Vilka arbetsuppgifter ingår i en pressfotografs arbete?
- Hur har yrket förändrats de senaste 25 åren?
- Hur ser pressfotograferna på fotojournalistikens framtid?
Metoderna har bestått av observationer, intervjuer och en enkätundersökning. Den första delen av resultaten gör nedslag på ett par bildredaktioner: Ingress Media, Nya Wermlands-Tidningen och Aftonbladet. Den innehåller också ett porträtt av pressfotografen Paul Hansen.
Den andra delen består av en mindre kvantitativ undersökning med 28 pressfotografer i olika anställningsformer från hela landet. Den berättar om deras arbete och syn på framtiden. Resultaten ger en bild av ett fotografsverige i förändring. På redaktionerna omfördelas fotografernas ansvar, till nytta för många och till förargelse för andra. Den digitala revolutionen omkullkastar gamla arbetssätt och håller på att stöpa in de framtida pressfotografernai en ny, bredare yrkesroll.
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Gryparis, Georgios, and Robin Johansson. "Made in Växjö : Vart tar EBD-studenter vägen?" Thesis, Linnéuniversitetet, Institutionen för organisation och entreprenörskap (OE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-36083.
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Problembakgrund Precis som många andra EU-länder är Sverige mitt i en utveckling av tjänstesektorn och en minskning av industrisektorn. Detta ställer nya krav på människor för framtida arbetsmarknaden. Ett sätt att bemöta detta är genom utbildning och stöd till entreprenörskap. Personer som kommer från en bakgrund med företagande föräldrar startar oftare företag och i synnerhet män. I Sverige tenderar unga människor att flytta från mindre orter till större städer. Detta kan innebära att mindre studieorter går miste om humant kapital om de inte lyckas attrahera de utexaminerade studenterna till att stanna. Problemformulering - Vilken attityd har utexaminerade EBD-studenter till att starta företag och var väljer de att bosätta sig? Syfte - Att få en fördjupad bild över hur många utexaminerade EBD-studenter som blir företagare och var de väljer att bosätta sig. Metod I denna rapport angreps forskningsproblemet med utgångspunkt i teorin. De delar av teorin som ansågs intressantast byggdes vidare med olika hypoteser som ställdes mot verkligheten. Angreppssättet för att närma sig den empiriska verkligheten kan därför beskrivas som deduktiv. I denna undersökning representeras verkligheten genom en undersökning av utexaminerade EBD-studenter på Linnéuniversitetet. De utexaminerade studenterna valdes ut för att undersöka om entreprenörskapsstudenterna 3 avviker i sitt företagarmönster mot övriga Sverige. Efter datainsamlingen i form av telefonintervjuer analyserades svaren som ställdes emot statistik främst från GEM-forskningen och Entreprenörskapsbarometern. Teori I den teoretiska referensramen presenteras statistik om i vilken utsträckning svenskar är företagare. Dessutom beskrivs generella beteenden hos företagande vad gäller kön och urbanisering. Analys Analysen har genomförts genom statistik och vetenskapliga artiklar som berör företagande i Sverige. Detta har analyserats mot statistik från telefonintervjuerna med de utexaminerade studenterna. Populationens svar på frågor i intervjun har bildat variabler som sammanställts till statistik i tabeller i empirikapitlet. Slutsats - Av de antal kvinnor som gick EBD-utbildningen har 41 procent av kvinnorna ett entreprenöriellt engagemang, medan männen på EBD ligger på 36 procent, vid jämförelse av respektive kön för sig. - Bland utexaminerade EBD-studenter är den totala andelen företagare, de som bedriver större verksamhet samt haft utdelning i mer än 3 månader, 13 procent. Genomsnittet i Sverige för personer mellan 18 och 35 år är 4,9 procent. Det betyder att det är vanligare att EBD-studenter startar företag än genomsnittet i Sverige - De studenter som bedriver större verksamheter har oftare företagande föräldrar än de som inte gör det. - Färre personer bor kvar i Växjö med omnejd efter studierna på EBDprogrammet, än antalet personer som bodde i Växjö innan studierna. Detta trots att det är vanligt att mindre studieorter får behålla de personer som kommer från närområdet.Problem background - Like many other European countries, Sweden is in the midst of a development of the service sector and a decline in the industrial sector. This places new demands on people for the future labour market. One way to treat this is the training and support of entrepreneurship. People who come from a background with entrepreneurial parents often start businesses, this applies especially to men. In Sweden, young people tend to move from small towns to large cities. This may mean that small study locations are missing out on human capital if they do not succeed in attracting graduates to stay. Problem - What attitude do graduated EBD students have to start a business and where do they choose to settle? Purpose - To get a detailed picture of how many graduated EBD students become entrepreneurs and where they choose to settle. Methodology - In this report the research problem was approached by starting with the theory. The parts of the theory that was considered interesting was developed further with different hypotheses posed against reality. The reach to approach empirical reality can therefore be described as deductive. This study represented reality through a survey of graduated EBD students at Linnaeus University. The graduates were selected to investigate whether entrepreneurship students differ in their entrepreneurial pattern against the 5 rest of Sweden. After the data collection in the form of telephone interviews, the responses were analyzed and compared with statistics mainly from the GEM research and a Swedish research from Entreprenörskapsbarometern. Theory - In the theoretical framework statistics are presented to show to what extent Swedes are entrepreneurs. It also describes the general behavior of entrepreneurs in terms of gender and urbanization. Analysis - The analysis has been carried out by statistics and scientific articles related to entrepreneurship in Sweden. This has been analyzed against data from telephone interviews with graduates. Population responses to questions in the interview has formed variables compiled into statistics in tables of the empirical chapter. Conclusion - Of the number of women who took the EBD program 41 percent of women have entrepreneurial commitment, while the men on the EBD program is at 36 percent, when comparing each gender separately. - Among the graduated EBD students the total number of entrepreneurs, that are engaged in major businesses and have had dividends in more than 3 months is 13 percent. The average in Sweden for people aged 18 - 35years is 4.9 percent. This means that it is more common for EBD students to start businesses than the average in Sweden. - The students who engaged in major businesses have more often entrepreneurial parents than those who do not. - Fewer people still live in vicinity of Växjö after studying the EBD program than the number of people who lived in Växjö prior to their studies. This despite the fact that it is common for smaller study locations to keep the people from the area.
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Hörnström, Andreas, and Viktor Ekman. "Vart leder högre studier i medie- och kommunikationsvetenskap?" Thesis, Umeå universitet, Institutionen för kultur- och medievetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-158242.
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The Umea university Faculty of humanities offers programs, courses, cross-disciplinary educations and post graduate studies. The university mentions on their website that newly graduated students rapidly establish themself in the labour market. Meanwhile a survey made by statistics Sweden (Statistiska centralbyrån) shows that graduates in humanities i general and graduates in journalism and media particularly experiences the longest gap between graduation and permanent employment. The labor market of media and communications branches off in a variety of businesses and the ever so fast development of technologies has created an evenly fast developing anticipation in the employees. The purpose of this study is to use the program of media- och communication in Umea university as case, and study the graduates entrance in the labour market. Furthermore the purpose is to build understandings for how the graduates value the expertise they have acquired and how this is to be understood in relation to the development of the industry. The study is based on an online survey in which 11 years of graduates answers 11 questions. In total 104 respondents answered the survey and the main conclusions interrelates to theories of the implications of competences, and how the information society has restructured the circumstances of the labour market. The main conclusions summarizes that the graduates rapidly establishes themself in the labour market, an that even though 50% of the graduates has chosen to complement their studies they generally experience satisfaction with the choice of subject. Furthermore the results shows that the workers assignments has changed over time, however only in some areas.
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Carlsson, Henrik. "Vart är jag på väg? Återkoppling i skolan." Thesis, Malmö högskola, Fakulteten för lärande och samhälle (LS), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-29487.
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Problemområde som behandlas i studien är hur lärare använder återkoppling och om de använder den på ett sådant sätt att den har en positiv effekt på elevers lärande. Men också hur lärare förstår och uppfattar återkoppling. Återkoppling ska besvara tre frågor: vart är jag på väg?, hur går det för mig? och vart är jag på väg?. Återkopplingen kan riktas till fyra nivåer: uppgift, process, självreglerande och/eller individ. Det finns andra aspekter av återkoppling som är värda att beakta som tas upp i studien varav återkopplingens timing, muntlig och skriftlig återkoppling, återkoppling i klassrum och återkoppling i bedömningssituationer är några. Syftet med studien var att undersöka hur lärare använder återkoppling och deras syn på återkoppling. Metoden som används i projektet är kvalitativ. Observationer och semi-strukturerade intervjuer har genomförts, i en kvalitativ studie, för att samla in empiriskt material. En stor del av återkopplingen i skolan är skriftlig. Jag har läst individuella utvecklingsplaner med skriftliga omdömen, skriftliga kommentarer på tester, diagnoser, prov och uppgifter. Resultatet visar att lärarna har olika kunskaper om återkoppling. Men lärarna återkopplar oavsett hur väl insatta de är i återkopplingens teorier. De besvarar återkopplingens tre frågor i olika hög grad. ”Hur går det för mig?” var den fråga som fick mest svar. Mycket av den muntliga återkopplingen sker på uppgiftsnivå vilket kan bero på att många av de observerade lektionerna handlade om procedurräkning. I den skriftliga återkopplingen återkopplades det på processnivå till ganska stor del. Men här förekom det också återkoppling på uppgift och individnivå. Återkoppling på självreglerande nivå var sparsam.
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Zu, Yige. "Developing a practicable benchmark VAT." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/22448/.
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This thesis develops a practicable benchmark VAT that bridges the gap between theory and practice in VAT design and provides concrete guidance for countries to evaluate, assess, and, where appropriate, reform their VATs. The potential use of the practicable benchmark in devising a reform agenda is illustrated by means of a case study based on the Chinese VAT, a tax that is at odds with the theoretical model in many respects. Experience has shown that real-world VATs most often deviate substantially from the theoretical VAT model, revealing the disconnect between the theoretical model based primarily on economic criteria and actual VAT designs that recognise the administrative, political and technical constraints encountered in the real world. A single rate and broad-based VAT is not readily achievable in many countries and VAT designers are further faced with issues that are not addressed directly in the model, including the application of VAT to small businesses, non-resident businesses, financial supplies, low value imports, and cross-border services as well as the challenges of devising workable arrangements for VAT systems in a federal or economic community setting. The thesis applies a tax expenditure analysis to evaluate the effectiveness, efficiency implications and revenue impact of VAT concessions. The negative consequences of concessions could be reduced with better targeting if the removal of concessions is politically unattainable. Registration threshold should be set at a level where the revenue costs are offset by the administrative savings from excluding small businesses from the VAT. Small business regimes often do not achieve the intended objectives and moreover yield efficiency and revenue costs. The best option to bring the financial and insurance sectors into full taxation is to use a separate (reduced) rate approach to tax intermediary loan services, a cash-flow model to tax insurance services and to categorise the issue and transfer of financial securities as zero-rated supplies. Effective collection of VAT on cross-border B2C imports of low value goods and services and removal of VAT from business acquisitions by non-resident businesses could be achieved with a higher level of international cooperation through bilateral treaties and a clearing house mechanism. No single benchmark is possible in terms of the design of VAT sharing in federations or economic communities because appropriate design relies heavily on the political and structural factors in federations. The clearing house model appears to be the best option to distribute VAT revenue in most circumstances where sub-central jurisdictions have their own VATs. The benchmark needs to be modified to accommodate local factors when applied to any particular country. It nevertheless provides a starting point for countries to evaluate and reform their VATs. The case study of China shows the process of applying the benchmark to an ill-designed real-world VAT. VAT design often reflects features of predecessor taxes and in this respect China may have an advantage notwithstanding the significant deviation of its current VAT from the benchmark. Some features inherited from the predecessor tax may make reform, particularly in respect of financial supplies, easier than in counterparts that evolved from European turnover taxes.
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Gonzalez, Campos Jose Alberto. "Design and Experimentation of Darrieus Vertical Axis Wind Turbines." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1594690510943748.
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Gobbi, Vagner João. "Comportamento em fluência e caracterização microestrutural das superligas VAT 36, VAT 32 e NIMONIC 80A." reponame:Repositório Institucional da UnB, 2013. http://repositorio.unb.br/handle/10482/15039.
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Tese (doutorado)-Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2013.Submitted by Albânia Cézar de Melo (albania@bce.unb.br) on 2013-11-19T12:56:33Z No. of bitstreams: 1 2013_VagnerJoaoGobbi.pdf: 96126826 bytes, checksum: dc2ee55d3661eaba1d0ae1bf74964a19 (MD5)
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Materiais com comportamento adequado em temperaturas elevadas tornaram-se uma necessidade nos dias atuais. Superligas são conhecidas desde a década de 1930 e utilizadas, principalmente, em aplicações aeroespaciais e automobilísticas. Com as novas regulamentações para redução das emissões atmosféricas e aumento da eficiência, surgiram projetos que submetem certos componentes de motores como válvulas, a temperaturas e pressões mais elevadas. Assim, exige-se que as ligas utilizadas na fabricação desses componentes possuam maior resistência à alta temperatura, a exemplo da NIMONIC 80A. Esta é uma liga de custo elevado devido à alta quantidade de níquel (70 a 80% em peso) além de possuir tratamento térmico extenso. Uma alternativa é a utilização de ligas com menor teor de níquel (30 a 40% em peso) e tratamento térmico reduzido. Neste contexto a Villares Metals desenvolveu duas novas superligas, as VATS 32 e 36. Essas ligas são concebidas para válvulas de motores de combustão interna, porém podem ser utilizadas nos casos que necessitem de resistência mecânica a quente, resistência à fluência, corrosão a quente, especialmente por gases sulfurosos, e resistência a fadiga substituindo às ligas NIMONIC 80A em diversas aplicações. A Empresa Villares Metals fez algumas caracterizações à quente das ligas VAT 32 e VAT 36 porém, não foram realizados ensaios por fluência medindo a deformação com o tempo. Portanto, este trabalho tem como objetivo fazer um estudo do comportamento em fluência, em termos de taxa de deformação secundária e tempo de fratura, das superligas VAT 36, VAT 32 e NIMONIC 80A. As ligas são submetidas a ensaios de fluência na modalidade de carga constante, na faixa de temperatura de 675 a 750 ºC e na faixa de tensão de 500 a 600 MPa definidas de acordo com suas aplicações. Os ensaios de fluência são realizados conforme a norma ASTM E139. Obtem-se um conjunto de curvas de deformação verdadeira pelo tempo como função das tensões e temperaturas aplicadas. Foi avaliado a ductilidade, a taxa de fluência estacionária e o tempo de vida. Complementou-se o trabalho com caracterização microestrutural das superligas através das técnicas de microscopia ótica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, difração de raios X, refinamento de Rietveld e ensaios de dureza. Os resultados mostram que a liga VAT 32 apresenta maior resistência à fluência (menor taxa de deformação secundária e maior tempo de fratura) em relação à VAT 36 e NIMONIC 80A. Isto se deve além do efeito benéfico dos compostos intermetálicos γ' (Ni 3(Al,Ti)), ao maior tamanho de grão e a maior fração de carbonetos ligados MC encontrado na VAT 32. Estes precipitados ricos em titânio e nióbio são estáveis a temperaturas elevadas, aumentam a resistência ao movimento de discordâncias e retardam processos difusionais associados à deformação por fluência. Ancoram os contornos de grãos dificultando o deslizamento relativo entre eles afetando a facilidade com que as vacâncias possam ser geradas nestas mesmas regiões. Por meio da análise dos expoentes de tensão, energias de ativação e imagens obtidas por microscopia eletrônica de transmissão após fluência o mecanismo de deformação dominante no estado secundário de fluência das ligas VAT 32, VAT 36 e NIMONIC 80A é movimento de discordâncias envolvendo provavelmente processo de Orowan loops e cisalhamento de precipitados pelas discordâncias, além da presença de deformação por twinning para as ligas VATS e escorregamento e escalagem de discordâncias para a NIMONIC 80A. ______________________________________________________________________________ ABSTRACT
Materials with appropriate behavior at elevated temperatures have become a necessity nowadays. Superalloys have been known since the 1930 and used primarily in automotive and aerospace applications. With the new regulations to reduce air emissions and increased efficiency projects emerged that submit certain engine components such as valves, temperatures and higher pressures. Thus, it is required that the alloys which are used in manufacturing these components have high temperature resistance, such as the NIMONIC 80A. This alloy has high cost due to the high amount of nickel (70 to 80% wt) and extensive heat treatment. An alternative is to use alloys with lower nickel content (30 to 40% wt) and reduced heat treatment. In this context, Villares Metals has developed two new superalloys, the VATS 32 and 36. These alloys are designed for valves internal combustion engines, but can be used in cases requiring mechanical strength hot, strength creep and corrosion, substitute alloy NIMONIC 80A in various applications. Villares Metals Company made some characterizations of the hot alloy VAT 32 and VAT 36 however, no tests were performed measuring creep deformation with time. The objective of this paper is to make a study of the behavior in creep in terms of secondary strain rate and rupture time of the superalloys VAT 36, VAT 32 and NIMONIC 80A. The alloys are subjected for creep tests in constant load mode, of the temperature range 675-750°C and stress range 500-600 MPa defined according to their applications. The creep tests are performed according to ASTM E139. Is obtained a set of curves of deformation real by the time in function of the applied stress and temperatures. Are evaluated ductility, the stationary creep rate and life time. Work is complemented with icrostructural characterization of superalloys through the techniques of optical microscopy, SEM, TEM, X-ray diffraction, Rietveld refinement and hardness tests. The results show that the alloy VAT 32 has a higher creep resistance (lower strain rate secondary and higher fracture time) from the VAT 36 and NIMONIC 80A. This is due to the beneficial effect of the intermetallic compounds γ' (Ni3 (Al, Ti)), the largest grain size and the largest fraction of MC carbides found in the VAT 32. These precipitates rich in titanium and niobium are stable at elevated temperatures, increased resistance to movement of dislocations and retard diffusional processes associated with creep deformation. Anchor the grain boundaries impairing the relative sliding between them affect the ease with which the vacancies may be generated in these same regions. Through analyzing the stress exponents, activation energies and images obtained by transmission electron microscopy after the creep deformation mechanism dominant in state secondary creep alloys VAT 32, VAT 36 and NIMONIC 80A is movement of dislocations probably involving process Orowan loops and shearing of precipitates by dislocations and the presence of deformation twinning for alloys VATS and slip of dislocations and climb for NIMONIC 80A.
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Zheng, Junping <1987>. "The Right of Deduction within the European VAT: A Perspective for the VAT Reform in China." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7307/1/zheng_junping_tesi.pdf.
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Value added tax (VAT), with its specific and unique feature as a neutral taxation, has spread rapidly around the world since its first adoption in Europe. China has also chosen to adopt VAT in an attempt to promote its economic development. In 2012, China started a new round of reform of VAT to extend its scope to industries which previously were liable to business tax. One of the most difficult problems is the rebuilding of the VAT deduction system therein. Although Europe faces its own problems and difficulties in the process of perfection and coordination of VAT, as the cradle of VAT it could still provide helpful insights for the ongoing VAT reform in China. Based on the analysis of the VAT system and, in particular, the right to deduct input VAT in Europe, combined with the development and special conditions of VAT in China, I propose several recommendations for the ongoing VAT reform in China and its future legislation. First, on the overall level, it is important to review the principle of neutrality in VAT, and rather than to view it as a natural result of the operation of the VAT system, its role as a rule to be complied with. Second, with regard to the design of the VAT deduction system, I argue that: (1) it is not necessary to establish VAT deduction as a substantive right of the taxpayer; (2) it is necessary to expand the scope of deductible items in China, especially in relation to fixed capital investment; (3) it is urgent to improve the treatment of the excess amount of deductible input VAT. Finally, suggestions are given supporting the construction of the related procedural legislation.
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Zheng, Junping <1987>. "The Right of Deduction within the European VAT: A Perspective for the VAT Reform in China." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7307/.
Full textAbstract:
Value added tax (VAT), with its specific and unique feature as a neutral taxation, has spread rapidly around the world since its first adoption in Europe. China has also chosen to adopt VAT in an attempt to promote its economic development. In 2012, China started a new round of reform of VAT to extend its scope to industries which previously were liable to business tax. One of the most difficult problems is the rebuilding of the VAT deduction system therein. Although Europe faces its own problems and difficulties in the process of perfection and coordination of VAT, as the cradle of VAT it could still provide helpful insights for the ongoing VAT reform in China. Based on the analysis of the VAT system and, in particular, the right to deduct input VAT in Europe, combined with the development and special conditions of VAT in China, I propose several recommendations for the ongoing VAT reform in China and its future legislation. First, on the overall level, it is important to review the principle of neutrality in VAT, and rather than to view it as a natural result of the operation of the VAT system, its role as a rule to be complied with. Second, with regard to the design of the VAT deduction system, I argue that: (1) it is not necessary to establish VAT deduction as a substantive right of the taxpayer; (2) it is necessary to expand the scope of deductible items in China, especially in relation to fixed capital investment; (3) it is urgent to improve the treatment of the excess amount of deductible input VAT. Finally, suggestions are given supporting the construction of the related procedural legislation.
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Gontijo, Campos Andre. "Quantum Control over Vast Time Scales and Length Scales." Thesis, Princeton University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10619678.
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Quantum control theory (QCT) is concerned with the active manipulation of phys- ical and chemical processes on the atomic and molecular scale. For a specified con- trol objective, and with restrictions imposed by many possible constraints, the time- dependent field required to manipulate the system in a desired way can be designed using quantum control theory. This dissertation proposes several novel applications of QCT to actively manipulate the dynamics of both quantum and classical systems with and without interactions with an external environment, in both relativistic and non-relativistic regimes. In Chapter 2, the paradigm of spectral dynamic mimicry (SDM) in which laser fields are shaped to make any atomic and molecular systems look identical spectrally is put forward. SDM successfully avoids optimization rou- tines, and provides a powerful tool to find a laser pulse that induces a desired optical response from an arbitrary dynamical system. As illustrations, driving fields are com- puted to induce the same optical response from a variety of distinct systems (open and closed, quantum and classical). The formulation may also be applied to design materials with specified optical characteristics. These findings reveal unexplored flex- ibilities of nonlinear optics. Little is known about the control of relativistic quantum systems. Therefore, an extension of QCT to the Dirac equation is proposed. The main contributions are: (i) Chapters 3 and 4 reach an unprecedented level of control while providing exciting new insights on the complex quantum dynamics of relativis- tic electrons. The method developed provides a very powerful tool to generate new analytical solutions to the Dirac equation, (ii) Chapters 5 and 6 present an open system interaction formalism for the Dirac equation. The presented framework en- ables efficient numerical simulations of relativistic dynamics within the von Neumann density matrix and Wigner phase space descriptions, an essential requirement for the application of QCT, (iii) Chapter 7 proposes a Lindblad model of quantum elec- trodynamics (QED). The presented formalism enables a very efficient and practical numerical method to simulate QED effects, such as the Lamb shift and the anomalous magnetic moment of the electron, for a broad variety of systems.
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Ragab, Amr. "Three essays on the incomes of the vast majority." Thesis, The New School, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3632551.
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This dissertation is mainly concerned with the distribution of between individuals in the economy.
The first chapter (Chapter 1) examines the various problems with Gross Domestic Product per capita (GDPpc) as a measure of economic welfare. The chapter proposes the Vast Majority Income (VMI) as a new measure of economic welfare that combines both national income and income distribution in a single, intuitive measure. The VMI measures the average income per capita of the vast majority of the population, defined as the first 80 percent of the population within the income distribution.
Chapter 2 proposes a model of the labor market that has a statistical equilibrium wage rather than a single point equilibrium wage as in the standard microeconomic model of wage equalization. Using heterogeneous agent-based modeling techniques, the chapter presents a labor market model where wages equalize around an exponential distribution of wages. Compared to previous models of statistical equilibrium in economics, this model does not require a fixed average wage levels.
Chapter 3 proposes a measure of inclusive growth that is based on the concept and methodology of the VMI discussed in Chapter 1. The growth rate of the VMI across time is proposed as a measure of the inclusivity of growth. We then compare and contrast the growth rate of the VMI to the growth rate of GDP per capita, economic growth. The Chapter shows how the last thirty years were mostly a period of non-inclusive growth in the majority of developing economies. Growth in developing nations was accompanied by a worsening of the equality of income distribution and as a result the growth in the incomes of the vast majority (the bottom 80% of income earners) was 1% less than the growth in GDP per capita for the population as a whole in developing countries.
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Garza, Simon, and Lundrim Shaqiri. "Korrosionsstudie om nickel-krom-molybden legeringar i våt skrubber." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-31255.
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Arbetet som utförts är en material studie som inriktar sig på nickel-krom-molybdenbaserade legeringar som används i dagens våt skrubber. Eftersom kraven på mängden utsläpp av svaveldioxid är en viktig miljöfråga, skapar detta ett behov för användandet av en våt skrubber. Den här produkten befinner sig i anläggningar där förbränningsmotorer finns och förekommer i princip i alla större fartyg. Rökgasen som motorerna släpper ifrån sig är skadlig för miljön och därför absorberas flödet in till en våt skrubber där en förbränning sker. Rökgasen separeras med hjälp av ett antal sprinklers som är placerade ovanpå gas ingången i en skrubber. Med hjälp av havsvatten som samlas upp och sluts till skrubbern injiceras detta genom sprinklers sen vidare nedåt på rökgasen som separerar föroreningar ifrån den gasen som är tänkt ska kondensera genom och ut i atmosfären. Havsvatten tillsammans med föroreningarna samlas på botten av skrubbern och samlas i tankar. Denna miljö är väldigt skadlig för materialet som produkten består av, framför allt på botten där materialet riskerar att korrodera som mest. Arbetet beskriver ett antal typer av korrosion och förklarar innebörden av de olika typerna så att det enklare går att förstå sammanhanget med miljön och omständigheternas påverkan på legeringarna. Syftet i arbetet är att studera de olika legeringarna och beskriva de med hjälp av den litteraturstudie som gjorts. Med hjälp av insamlad data av tester som tidigare utförts enligt standard, har detta tolkats och bidragit till evalueringen av de olika legeringarna. De grundläggande tester som används vid evaluering av legeringarnas karaktär är tester där en bit av materialet doppas ned i en specifik lösning med olika omständigheter och villkor. Detta räcker inte för att säkerställa en hållbar livscykel för en våt skrubber och därför evalueras legeringarna även med hjälp av olika fälttester. Teoretiska studier på tester i aggressiva miljöer används för att resultera rangordningen av de olika materialen och även ett nytt material undersöks vid namnet alloy 2120.This thesis work is a study of materials which focus on nickel-chromium-molybdenum-based alloys used in today’s wet scrubbers. Since the requirements for emissions of sulfur dioxide is a major environmental issue, this creates a need for the use of a wet scrubber. This product is in installations where combustion engines are available and are basically in all larger vessels. The flue gas that engines emit are harmful to the environment and for that reason, the flow is absorbed into a wet scrubber where combustion takes place. The flue gas is separated by a number of sprinklers placed above of the gas in a scrubber. Collected seawater is used to separate the gas through the sprinklers that injects the water on top of the flue gas where impurities is separated from the gas that will condense out to the atmosphere. The water fluid together with the contaminants is collected on the bottom of the scrubber and into the tanks. This environment is very harmful to the material that the product is made of, in particular on the bottom where the material is more susceptible for corrosion. The work describes several types of corrosion and the meaning of the different types so that the reader easily can understand the impact of the environment on the alloys. The type of corrosion that occurs primarily in scrubbers is pitting corrosion and is considerate to be a highly local type of corrosion, and the most dangerous type. Pitting occurs when the protective oxide layer does not have time to repassivate and can also lead to other types of corrosion. Due to the dangerous work environment, the risk for corrosion to occur is high and therefore, focus is put on this specific material group. The purpose of this work was to study the alloys and describe them with the help of a literature study. Using data collected from tests previously performed in accordance with standards, the collected data has been interpreted and contributing to the evaluation of the various alloys. The basic tests used in the evaluation of the nature of the alloy are tests in which a piece of material immersed in a specific solution with different circumstances and conditions. This is not enough to ensure a sustainable life cycle for a wet scrubber and therefore, alloys is evaluated using various field tests as well. Theoretical studies on tests in aggressive environments is used to result the ranking of the various materials and also a new material is examined by the name alloy 2120.
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Coraucci, André de Oliveira. "Projeto estrutural da asa de VANT em material compósito." Instituto Tecnológico de Aeronáutica, 2011. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2924.
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Este trabalho apresenta uma solução de projeto estrutural em material compósito para a asa de 4,044m de envergadura do Veículo Aéreo Não-Tripulado (VANT) em desenvolvimento pelo Instituto Tecnológico da Aeronáutica (ITA). Está proposta uma configuração estrutural nervurada constituída por um caixão estrutural formado pelos revestimentos do extradorso e intradorso e por duas longarinas. A configuração sugerida foi validada por meio de análises computacionais lineares em elementos finitos feitas para quatro casos de laminados distintos. Um método para cálculos aproximados das cargas de manobra simétrica e assimétrica está apresentado. Os resultados das análises indicam superdimensionamento para as tensões e pouca deformação devido à necessidade de garantir a estabilidade dos componentes estruturais sob cargas limites.