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676 Uppsatser om Wind load - Sida 17 av 46
Skogsskötsel för att minimera stormfällning över järnväg :
The society of today is dependent of secure transports and deliveries of electrical power. Interruptions in different activities because of fallen trees cost a great deal of money in form of reparations and claimed damages for transport companies and electrical suppliers. Fallen trees along some railway sections are a severe problem. For instance, to repair the damages of the storm of week 5 year 2002, costed 2 800 000 SEK for the line region of Hässleholm. Today, the Banverket railroad company has no norms in general for how close to the railway the forest is allowed to grow.
Konstruktion av statorstomme för synkrongenerator : Förslag på design av statorstomme för användning i vertikalaxlade vindkraftverk
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..
Förändringar i markanvändning över tid och dess påverkan på vattenkvalitet
The EU Water Framework Directive has led that management follows the boundaries of natural catchments.The Swedish waters suffer from a nutrient overload that originates mainly from diffuse sources such as agriculture and the subcatchment of Hackstabäcken in Vallentuna Kommun, just north of Stockholm, has been chosen for this study because of its high nutrient load and because it has undergone obvious changes in land use through the years.In this study, the land use in 1902 is compared with the land use in 2011 in order to investigate if it has influenced the ability of the landscape to produce ecosystem services related to nutrient removal. These services will continue to be produced as long as the system is stable and resilient, but when landuse changes and manure from horses increases it will lead to disturbances that can convert a system from one regime in to a completely different one. That will result in loss, or degradation, of ecosystem services such as denitrification, phosphor sedimentation and adsorption, vegetation uptake and infiltration.The results of this study are based upon area calculations of landuse from old maps from 1902 and 2011. Through these maps it becomes clear that the forests in Hackstabäcken, has increased with 170 ha together with an urbanization of 311 ha, at the same time as wetlands and arable land has diminished and lakes has suffered from reductions. Wetlands have been reduced with 76 ha and the ones remaining are of insufficient quality from a nutrient removal perspective.Data from 1902 and 2011 regarding number of horses and bovines indicated a decrease in bovines and an increase in horses.
En analys av nattliga koldioxidflöden i en boreal barrskog avseende spatial och temporal variation
Carbon dioxide in the atmosphere contributes to the greenhouse effect, which is essential tolife on our planet. Furthermore, it plays an important part of the photosynthesis andrespiration of the world?s organisms. Since the start of the industrial revolution the amount ofcarbon dioxide in the atmosphere has increased exponentially. The main source is theextensive burning of fossil fuels.
Vindkraft under utveckling
Vindkraft är ett miljövänligt energislag med stor utvecklingspotential, både i Sverige ochutomlands. I det här examensarbetet sammanfattas de viktigaste bitarna av kunskapen sombehövs för att förstå sig på vindkraft, med fokus på meteorologi och kommunikation medkonsultföretag i branschen. På grundval av litteratur i ämnet, konsultrapporter beställda av ettsvenskt företag i branschen och diskussion med experter ges här en grundläggande översikt imeteorologi för vindkraft, vilken innefattar kunskaper om klimatet i allmänhet ochvindklimatet i synnerhet, förståelse för luftens flöde, den geostrofiska vinden och hurtopografi och dylikt påverkar luftens strömning i gränsskiktet. Vidare diskuteras hur energin ivinden tas till vara, med en sammanfattning av viktiga tekniska detaljer; vindkraftsspecifikastorheter och uttryck, energiförluster och effekterna av att placera många vindkraftverk i engrupp; vakeffekten. En av de dominerande delarna av alla konsultrapporter som studerats ärhur man analyserar och behandlar vinddata för maximering av tillförlitlighet och relevans.
Scenarioanalys över Sveriges elproduktion år 2050 : Kan Sverige försörja sig med 100 % förnybar
The aim of this report was to investigate if Sweden can have 100 % renewable electricity production in the year 2050. The conclusion is that it is possible but under certain conditions. For instance wave power must be in commercial use. When wind power and solar power represent a large percentage of the electric production there will be a lack of electric power during the winter but during the summer there will be a surplus of electric power. Both the surplus and the lack of electric power need to be taken into account.
Avspecialisering som framgångskoncept för jämnare arbetsfördelning?
The application of the LSS law and how the public organization (Municipality of Hudiksvall) later had to reform their organization to fit the new demands is the foundation to this master's thesis. An internal evaluation was performed due to this reorganisation process within the social care department (LSS unit). The aim was to investigate and evaluate if the reorganization resulted in a better working environment and if the work load (distribution of work) became more evenly divided between the different unit managing directors. The primary empirical information to this master's thesis is collected from that evaluation report. The main aim of this master?s thesis is to answer if the organisational choice between specialised or de-specialised working tasks has an effect (experienced and measured) on the level of stress among the unit managing directors.
Kylapotentialen i Drefviken för Vattenfall Heat AB
Vattenfall Heat AB is a district heat provider in Drefviken, but has yet to establish any cooling systems in this area. This thesis examines the potential client base within the area today and over the coming 20 years. The feasibility of the most common cooling technologies is evaluated and results show a total potential for an installed capacity of 30 MW providing 50 GWh of cooling per year. One of the examined areas shows good prospect for heat driven absorption chillers during the summer months when the heat load is limited..
WSC Wind Science Centre : Centret för vindenergi
Målet med projektet har varit att designa en byggnad där information om vindkraft kan presenteras. Utgångspunkten iprojektet har varit upplevelsen med ett antal studier som grund. Området som berörs är Borgsjö som är optimalt läge fördenna typ av informationsbyggnad. Genom studiebesök, enkätundersökning, intervjuer och analys har ett antal konceptframställts. För att engagera besökarna så har även en enhet för utomhusbruk tagits fram där användaren med sin egenstyrka kan generera elektricitet och jämföra med miniverket.
Näringsretention i återskapad våtmark på betesmark : studier av en mad vid Bornsjön
It is important to construct or recreate different types of wetlands and study their retention of nutrients, since knowledge of their effectiveness in this matter is poor. In 2003 a wetland was constructed on an old meadow on the western shore of Lake Bornsjön in central Sweden. The main purpose of the wetland was to reduce the amount of phosphorus entering the lake, which is the back-up water supply for Stockholm when the city cannot obtain water from Lake Mälaren. Large areas around Lake Bornsjön consist of agricultural land and the nutrient concentrations in the inflows to the lake are usually relatively high (approx. 1 mg/l total nitrogen and 0.05-0.1 mg/l total phosphorus).
Elasticitetsmodulen i en kalkstabiliserad vägterrass : en fältstudie
Stabilization of subgrade is an internationally common technique to improve the characteristics of a soft soil. Improving the stiffness and bearing capacity of the subgrade enables the pavement to be designed with reduced depths of subbase and basecourse aggregates. This makes the stabilization technique both economically and environmentally interesting. Both natural and stabilized soils have high inherent property variability that should be considered when the characteristic value is derived. By analyzing the spatial variability in stabilized and natural subgrades it is possible get the parameters needed for reliability?based modeling of soil properties.
Metodik för utmattningsberäkning av svets i vibrationsmiljö
In this work, a method was developed and evaluated for calculating the life of welds under the influence of fatigue loads from a vibration environment. Typically, a shaker table is used for testing a component against vibration loads. The shaker table creates a vibration environment that is defined in the frequency domain by a power spectrum.Similarly, a virtual vibration table can be used to calculate the same type of load environment, which can then be used to calculate the expected lifetime. The benefit of this method is that it can be used in design, as well as in simulation of tests before physical verification tests are carried out.Today there are methods for calculating fatigue life of non-welded base material, but since many components contain welded joints, there is a need to apply this method to those types as well. To achieve this, the thesis combines two different areas, which together provide a method for fatigue assessment of welds using a virtual shaker table.The methodology is carried out by modeling the component, and its welded joints, in a finite element program.
Direct-EGR tillämpat på HCCI
The Homogeneous Charge Compression Ignition (HCCI) engine is promising in terms of lowNOx, low particulates and high efficiency. Due to its homogeneous charge, where thecombustion starts almost simultaneously from a number of points in the combustion chamber,only lean mixtures are possible to burn because of the resulting rapid combustion, which is muchfaster than the combustion in an SI-engine or a diesel engine. When richer mixtures are used thecombustion will start earlier and also be more violent.To phase the combustion later and lower the combustion speed, external cooled EGR can beused. The EGR-system used in this thesis uses a divided exhaust channel where one channel andits corresponding valve are used only for transporting EGR back to the intake system.Consequently the EGR-valve is connected to the intake pressure. This system is called Direct-EGR (D-EGR).Engine tests verified that the CA50 indeed is phased later when cooled EGR is used.
Självgående fordon hos Sandvik do Brasil
At the plant of Sandvik do Brasil in São Paulo there is a need for improving the transport of inserts between the plant building and the stock building. The idea is to install a system with an Automated Guided Vehicle (AGV) to take care of this transportation. The purpose of this report is to present which demands there are on the system and to find the best solution according to the demands.To conclude this work a study was made of the plant and the AGV technology was examined. Several providers of AGV solutions were contacted to get information about prices and detailed solutions.The conclusion was that the most suitable system for this application is a small unit load vehicle using inductive wire as guiding system..
Val av liggplats och väderskydd hos dikor vid utedrift vintertid
If you keep cattle in a herd outside all year round on big varying grounds, their possibilityto perform their natural behaviour increases. This way of keeping cattle requires that youprovide them with their other needs, like shelter and a dry and clean resting place.According to the animal welfare authority´s regulations on livestock farming, only animalsthat are suited to stay outside during the cold season are allowed to be kept outside. Theyshould also have access to a shelter or another building that gives them protection from theweather and wind and provides a dry and clean resting place.Research has shown that as long as cattle do not get exposed to precipitation and wind theywill manage low temperature well. Some of the things that will affect how well the animalshandle different climates are the isolation ability of the fur, the animals´ body size and thefeed intake. A dry lying place that is both insulating and moisture absorbent is also of greatimportance.