22 resultados para Topografia irregular
Resumo:
This master’s thesis was done for a small company, Vipetec Oy, which offers specialized technological services for companies mainly in forest industry. The study was initiated partly because the company wants to expand its customer base to a new industry. There were two goals connected to each other. First was to find out how much and what kind of value current customers have realized from ATA Process Event Library, one of the products that the company offers. Second was to determine the best way to present this value and its implications for future value potential to both current and potential customers. ATA helps to make grade and product changes, starting after machine downtime, and recovery from production break faster for customers. All three events sometimes occur in production line. The faster operation results to savings in time and material. In addition to ATA Vipetec also offers other services related to development of automation and optimization of controls. Theoretical part concentrates on the concept of value, how it can be delivered to customers, and what kind of risk customer faces in industrial purchasing. Also the function of reference marketing towards customers is discussed. In the empirical part the realized value for existing customers is evaluated based on both numerical data and interviews. There’s also a brief case study about one customer. After that the value-based reference marketing for a target industry is examined through interviews of these potential customers. Finally answers to the research questions are stated and compared also to the theoretical knowledge about the subject. Results show that those customers’ machines which use the full service concept of ATA usually are able to save more time and material than the machines which use only some features of the product. Interviews indicated that sales arguments which focus on improved competitive status are not as effective as current arguments which focus on numerical improvements. In the case of potential customers in the new industry, current sales arguments likely work best for those whose irregular production situations are caused mainly by fault situations. When the actions of Vipetec were compared to ten key elements of creating customer references, it was seen that many of them the company has either already included in its strategy or has good chances to include them with the help of the results of this study.
Resumo:
Successful management of rivers requires an understanding of the fluvial processes that govern them. This, in turn cannot be achieved without a means of quantifying their geomorphology and hydrology and the spatio-temporal interactions between them, that is, their hydromorphology. For a long time, it has been laborious and time-consuming to measure river topography, especially in the submerged part of the channel. The measurement of the flow field has been challenging as well, and hence, such measurements have long been sparse in natural environments. Technological advancements in the field of remote sensing in the recent years have opened up new possibilities for capturing synoptic information on river environments. This thesis presents new developments in fluvial remote sensing of both topography and water flow. A set of close-range remote sensing methods is employed to eventually construct a high-resolution unified empirical hydromorphological model, that is, river channel and floodplain topography and three-dimensional areal flow field. Empirical as well as hydraulic theory-based optical remote sensing methods are tested and evaluated using normal colour aerial photographs and sonar calibration and reference measurements on a rocky-bed sub-Arctic river. The empirical optical bathymetry model is developed further by the introduction of a deep-water radiance parameter estimation algorithm that extends the field of application of the model to shallow streams. The effect of this parameter on the model is also assessed in a study of a sandy-bed sub-Arctic river using close-range high-resolution aerial photography, presenting one of the first examples of fluvial bathymetry modelling from unmanned aerial vehicles (UAV). Further close-range remote sensing methods are added to complete the topography integrating the river bed with the floodplain to create a seamless high-resolution topography. Boat- cart- and backpack-based mobile laser scanning (MLS) are used to measure the topography of the dry part of the channel at a high resolution and accuracy. Multitemporal MLS is evaluated along with UAV-based photogrammetry against terrestrial laser scanning reference data and merged with UAV-based bathymetry to create a two-year series of seamless digital terrain models. These allow the evaluation of the methodology for conducting high-resolution change analysis of the entire channel. The remote sensing based model of hydromorphology is completed by a new methodology for mapping the flow field in 3D. An acoustic Doppler current profiler (ADCP) is deployed on a remote-controlled boat with a survey-grade global navigation satellite system (GNSS) receiver, allowing the positioning of the areally sampled 3D flow vectors in 3D space as a point cloud and its interpolation into a 3D matrix allows a quantitative volumetric flow analysis. Multitemporal areal 3D flow field data show the evolution of the flow field during a snow-melt flood event. The combination of the underwater and dry topography with the flow field yields a compete model of river hydromorphology at the reach scale.
Resumo:
The reduction of greenhouse gas emissions in the European Union promotes the combustion of biomass rather than fossil fuels in energy production. Circulating fluidized bed (CFB) combustion offers a simple, flexible and efficient way to utilize untreated biomass in a large scale. CFB furnaces are modeled in order to understand their operation better and to help in the design of new furnaces. Therefore, physically accurate models are needed to describe the heavily coupled multiphase flow, reactions and heat transfer inside the furnace. This thesis presents a new model for the fuel flow inside the CFB furnace, which acknowledges the physical properties of the fuel and the multiphase flow phenomena inside the furnace. This model is applied with special interest in the firing of untreated biomass. An experimental method is utilized to characterize gas-fuel drag force relations. This characteristic drag force approach is developed into a gas-fuel drag force model suitable for irregular, non-spherical biomass particles and applied together with the new fuel flow model in the modeling of a large-scale CFB furnace. The model results are physically valid and achieve very good correspondence with the measurement results from large-scale CFB furnace firing biomass. With the methods and models presented in this work, the fuel flow field inside a circulating fluidized bed furnace can be modeled with better accuracy and more efficiently than in previous studies with a three-dimensional holistic model frame.
Resumo:
Solar and wind power produce electricity irregularly. This irregular power production is problematic and therefore production can exceed the need. Thus sufficient energy storage solutions are needed. Currently there are some storages, such as flywheel, but they are quite short-term. Power-to-Gas (P2G) offers a solution to store energy as a synthetic natural gas. It also improves nation’s energy self-sufficiency. Power-to-Gas can be integrated to an industrial or a municipal facility to reduce production costs. In this master’s thesis the integration of Power-to-Gas technologies to wastewater treatment as a part of the VTT’s Neo-Carbon Energy project is studied. Power-to-Gas produces synthetic methane (SNG) from water and carbon dioxide with electricity. This SNG can be considered as stored energy. Basic wastewater treatment technologies and the production of biogas in the treatment plant are studied. The utilisation of biogas and SNG in heat and power production and in transportation is also studied. The integration of the P2G to wastewater treatment plant (WWTP) is examined mainly from economic view. First the mass flows of flowing materials are calculated and after that the economic impact based on the mass flows. The economic efficiency is evaluated with Net Present Value method. In this thesis it is also studied the overall profitability of the integration and the key economic factors.
Resumo:
This thesis addresses the coolability of porous debris beds in the context of severe accident management of nuclear power reactors. In a hypothetical severe accident at a Nordic-type boiling water reactor, the lower drywell of the containment is flooded, for the purpose of cooling the core melt discharged from the reactor pressure vessel in a water pool. The melt is fragmented and solidified in the pool, ultimately forming a porous debris bed that generates decay heat. The properties of the bed determine the limiting value for the heat flux that can be removed from the debris to the surrounding water without the risk of re-melting. The coolability of porous debris beds has been investigated experimentally by measuring the dryout power in electrically heated test beds that have different geometries. The geometries represent the debris bed shapes that may form in an accident scenario. The focus is especially on heap-like, realistic geometries which facilitate the multi-dimensional infiltration (flooding) of coolant into the bed. Spherical and irregular particles have been used to simulate the debris. The experiments have been modeled using 2D and 3D simulation codes applicable to fluid flow and heat transfer in porous media. Based on the experimental and simulation results, an interpretation of the dryout behavior in complex debris bed geometries is presented, and the validity of the codes and models for dryout predictions is evaluated. According to the experimental and simulation results, the coolability of the debris bed depends on both the flooding mode and the height of the bed. In the experiments, it was found that multi-dimensional flooding increases the dryout heat flux and coolability in a heap-shaped debris bed by 47–58% compared to the dryout heat flux of a classical, top-flooded bed of the same height. However, heap-like beds are higher than flat, top-flooded beds, which results in the formation of larger steam flux at the top of the bed. This counteracts the effect of the multi-dimensional flooding. Based on the measured dryout heat fluxes, the maximum height of a heap-like bed can only be about 1.5 times the height of a top-flooded, cylindrical bed in order to preserve the direct benefit from the multi-dimensional flooding. In addition, studies were conducted to evaluate the hydrodynamically representative effective particle diameter, which is applied in simulation models to describe debris beds that consist of irregular particles with considerable size variation. The results suggest that the effective diameter is small, closest to the mean diameter based on the number or length of particles.
Resumo:
Opinnäytetyössä tutkittiin miten Yyterin santojen esidyyni on muuttunut Porin kaupungin omistamalla alueella santojen keskiosassa viimeisen kymmenen vuoden ajalla. Yyterin dyynejä ja niissä tapahtuvia muutoksia ei ole aiemmin seurattu systemaattisesti. Esidyynin kehitykseen vaikuttavat hiekan laatu ja sen saatavuus sekä akkumulaation ja eroosion suhde. Eroosioon ja akkumulaation vaikuttuvat useat tekijät kuten tuuli, kasvipeite sekä ihminen. Tutkimuksen on tarkoitus tuottaa tietoa alueen hoidon- ja käytön suunnittelun tueksi. Alueella on järjestetty suuria yleisötapahtumia, jotka ovat jättäneet jälkensä alueen luontoon sekä vaikuttaneet dyynien kehitykseen. Yyterin hiekkaranta kuuluu kokonaisuudessaan Preiviikinlahden Natura 2000 – suojelualueeseen. Porin kaupungin omistamalle alueelle on perustettu keväällä 2013 luonnonsuojelualue, joka osaltaan ohjaa käyttöä. Esidyynin kasvillisuus ja topografia ovat muuttuneet tutkimusajanjaksona merkittävästi. Kasvillisuuspeitteen pienentyminen on altistanut dyynit eroosion eri muodoille. Esidyyni on lähtenyt liikkeelle samalla madaltuen sekä loiventuen. Esidyynin suojeltu, valkeiden dyynien -luontotyyppi on kehityksen seurauksena katoamassa. Dynaamisilla luontotyypeillä, kuten rantadyyneillä, suojelun ja virkistyskäytön yhteensovittaminen on haastavaa. Luontaisen kehityksen ja ihmisen vaikutuksen erottaminen on hankalaa, koska rantadyyneille on tyypillistä ajallisesti ja spatiaalisesti vuorottelevat eroosion ja akkumulaation jaksot. Yyterissä on päätetty ryhtyä suojelutoimenpiteisiin alueilla, joilla dyynien kehitykseen suurtapahtumien on katsottu vaikuttaneen merkittävästi.
Resumo:
Aktiivisia sonar-järjestelmiä käytetään monipuolisesti vedenalaisen valvonnan, sukellusveneentorjunnan ja miinantorjunnan osana. Itämeren olosuhteet ovat tunnetusti vaikeat aktiivisten sonar-järjestelmien käyttöä ajatellen. Tutkielman tarkoituksena on selvittää millaisia ominaisuuksia niiltä vaaditaan Suomen merialuilla toimittaessa. Tutkielmassa on esitetty vedenalaisen akustiikan perusteet, sonar-tekniikkaa ja Suomen merialueiden olosuhteet. Suomen merialueilta tutkielmassa on selvitetty vesiääniolosuhteet ja pohjan topografia sekä geologia. Tutkimusmenetelmänä käytettiin kirjallisuustutkimusta. Aineistoa on koostettu Puolustusvoimien oppaista, alan perusteoksista, kirjallisuudesta, Internet tietokannoista ja Ilmatieteenlaitoksen tilastoista. Tutkielman tuloksena luodaan käsitys niistä ominaisuuksista, joita aktiivisilta sonar-järjestelmiltä vaaditaan Suomen merialueilla. Tutkielmassa on tuotettu myös tietoa siitä, mitkä ovat eri merialueiden haasteet sonar-järjestelmien käytön osalta. Tutkielmassa havaitaan tarve runsaille määrälle ominaisuuksia sonar-järjestelmien käytettävyyden nostamiseksi.