Sök:

Sökresultat:

2065 Uppsatser om Particel size distribution - Sida 6 av 138

Grey-sided vole and bank vole abundance in old-growth forest patches of different size and connectivity

Vole populations in northern Scandinavia vary in cycles with peaks every third or fourth year as described by the National Environmental Monitoring Programme of small mammals (NEMP). Some vole species have declined in population numbers since the NEMP started in 1971, especially the grey-sided vole (Myodes rufocanus) which is nearly extinct in the forested region. Since small mammals are an important food source for several avian and mammalian predators, the decline in vole numbers is expected to have consequences for the whole food chain, especially if other vole species start to decline in numbers. This study tried to test the hypothesis that presence and abundance of M. rufocanus (a specialist species) and Myodes glareolus (a generalist species) can be predicted by patch size and connectivity of forest patches >60 years old with a minimum of 15% pine >100years old.

Biomass losses during short-term storage of bark and recovered wood

Storage of biomass is associated with problems like heat development, biomasslosses, and reduction of the fuel quality. Certain processes such as biological- andchemical degradation are responsible for these storage problems. This master?sthesis was carried out at Vattenfall Research and Development AB and is alignedtowards quantifying the biomass losses from short-term storage (1-2 months) ofbark and recovered wood. The biomass was stored in outdoor piles during differentseasons, campaign 1 (summer) and campaign 2 (autumn).

Kunskapens rum - en studie av Orkanenbiblioteket

The aim of this master´s thesis is to explore how a library through it´s spatial distribution expresses, and is an expression for, a view of knowledge. This is done by an analysis of the Orkanen library at Malmö Högskola. Questions posed in this study are: What view of knowledge is mediated through the spatial system and in the shelving of books? What view of learning is expressed in the spatial distribution of functions and artefacts?The theoretical framework of this thesis has two fundamental features. One, which focuses on theories of social space, a part that is mainly influenced by the theories of space syntax.

Rumslig utbredning av tuberkulos : Stockholms kommun år 2002-2011

This bachelor thesis is written as a part of the geography program at Stockholm University, Sweden, and the study was conducted from April to June 2012.Tuberculosis (TB) is an airborne disease and one of the most widespread infectious diseases in the world with more than nine million new cases each year (SMI 2012, digital source). The disease is a major source of death and suffering in many places and the number of deaths remains high despite the availability of highly efficacious treatment. To control and prevent further spread of TB, the mapping of the disease spatial distribution is of essential importance.In this study, maps were produced that shows the spatial distribution of TB between the years 2002 to 2011 in the municipality of Stockholm. These maps allow an analysis of the spatial distribution at a local scale over time.The aim of this paper is to study how the spatial distribution of TB has looked like in the municipality of Stockholm the last 10 years and to analyze why the spatial distribution of the disease looked like it did. This study is based on the hypothesis ?drift?.

Fluidrörelse- och värmetransportsmodellering i götugn

The purpose of this thesis for Sapa Heat Transfer is to examine a furnace in which aluminium is pre-heated before hot rolling. The project is modeled in a computer environment in which the air flow in the furnace and the heat transfer to the aluminium solids are included. The computer environment and its governing equations, as well as boundary conditions and generalizations, are presented and explained.The simulations are based on two models. The first model has an asymmetric solid placement, which is how it looks in today's ovens. It is validated against collected data.

Omkonstruktion och arkitekturbyte av autopilot för obemannade farkoster

This thesis has been written at Linköping University for the company Instrument Control Sweden AB (ICS).ICS is a small company located in Linköping that develops software and hardware for Unmanned Aerial Vehicles, UAV. At present, ICS has a fully functional autopilot called EasyPilot but they want to reduce the autopilot?s size to make it more attractive.The purpose of this thesis was to investigate if it was possible to reduce the size of the autopilot and how, in that case, it would be done. It was also necessary to examine whether the old processors should be replaced by new ones and how hard it would be to convert the old software to these new processors.To succeed with the goals many of the old components had to be changed for new, smaller ones. Some less necessary parts were also completely removed.

Ny princip för spänningsreglering i Fortum Distributions mellanspänningsnät i Stockholm.

The voltage regulation in Fortum Distributions medium voltage network in Stockholm does not work satisfactory. This results in too high distribution voltages with many customer complaints as a consequence. The reason is the model responsible for compensating for voltage drops in the distribution network. Despite several adjustments Fortum has not been able to find the source of the high voltages and has therefore appointed an investigation in the form of a thesis work.The aim of this investigation is to locate the error and to produce a proposal regarding the solution of this error using the existing system, common industrial knowledge, state of the art research and the option to use voltage readings from the different substations.The conclusion of this master thesis is that the largest contribution to the high voltage levels is made by the large compensation for distribution loses. Furthermore an additional error in the model has been found.

Inverkan av flisig krossballast på betong

Concrete is one of the world?s most common construction materials and is composed of 70-80 % stone material. Today crushed stone is used as aggregate in concrete in order to replace natural aggregates due to strong environmental reasons. Stone crushing yields flaky material and in this thesis studies are made on the flaky particle shape and how it influence properties of concrete such as workability, rheology and strength. The concrete recipes used in this thesis have fixed values, the only variable is the flakiness of the crushed stone.

Att lyckas med ett europeiskt ordförandeskap En jämförande studie mellan fyra EU-länder

The presidency of the European Union (EU) is one of the most important institutional actors for the improvement of democracy and equality between the member states. To hold a presidency is a big task and for many countries a tough challenge. What makes a presidency successful? The purpose of the thesis is to examine this question using Ole Elgströms? ?four properties for defining a successful presidency? as the theoretical background. This thesis will employ a comparative framework of four countries, using size and age (age understood as ?time being an EU Member State?) as the defining factors.

Utvärdering av en Magnetic Harmonic Traction Drive

In this report a new gear concept is evaluated using the magnetic finite element method (FEM)software MagNet and Ansys as well as the mechanical FEM software Abaqus. The gear conceptis evaluated in terms of maximum torque capability, torsional stiffness, gear ratio and efficiency.ABB Corporate Research has proposed a new gear concept which should be less expensive thangearboxes used today. The new concept is called aMagnetic Harmonic Traction Drive and usesthe principles of a harmonic drive gear to achieve a high reduction ratio. The gear conceptreplaces the wave generator used in traditional harmonic drives with magnets and uses tractioninstead of gear teeth to transfer the torque. The main components in the gearbox are the magnets,the flexspline, the magnetic portion and the circular spline.

Skillnader i upptag, metabolism, distribution och utsöndring av makrocykliska laktoner hos olika djurslag

Makrocykliska laktoner har varit flitigt använda avmaskningsmedel hos olika djurslag sedan mitten av 1980-talet och används fortfarande. För att avmaskningsmedel ska vara så effektiva som möjligt är det viktigt att veta hur de tas upp och omsätts i kroppen hos olika djurarter. Detta för att kunna anpassa doseringen till olika djurslag. Några farmakokinetiska parametrar har undersökts för att se om det förekommer skillnader i upptag, distribution, metabolism och utsöndring mellan nötkreatur, får och gris. Genom att jämföra olika studier fann jag skillnader i halveringstid, AUC, Cmax och tmax mellan gris, nötkreatur och får.

Trefaktorsmodellen : Undersökning på svenska börsnoterade aktiebolag

Previous work by researchers as Eugene F. Fama and Kenneth R. French, show that average return on stocks are related to a firms characteristics like size and book-to-market ratio. These kinds of patterns in average return is not explained by The Capital Asset Pricing Model (CAPM), and are therefore seen as anomalies. Fama and French have proposed a three-factor model, which captures patterns observed in U.S average returns associated with size and value.

Spatiella mönster och lager av organiskt klor och klorid i barrskogsjord i sydöstra Sverige

The concentration and storage of organic chlorine and chloride were determined in soil, to a depth of 40 cm, in a coniferous forest in the Stubbetorp catchment area in south-east Sweden. Also, the spatial distribution of the two forms of chlorine was determined. Soil samples were collected at 49 of the nodes in a grid with approximately 105 m between the nodes. The analysis of spatial variability suggested that no spatial autocorrelation was present either within the variable organic chlorine or chloride. This means that no sample was more influenced by another nearby sample, as compared to other samples further away.

Uppfödning av slaktgrisar (Sus scrofa domestica) i stora grupper : gruppstorlekens betydelse för grisars välfärd och produktionsresultat

This literature study deals with the pig industry and how group size and available floor area affects the animal welfare and the production results. It shows that both the pigs? welfare and production result can be affected negatively if the environment seems stressful for the pigs, and if they are housed in a narrow area. If the pigs are being exposed to either physiological or psychological stress factors their immune system can be decreased and the growth can be impaired. Influence by the social status of the pigs is also reviewed.

Fotogrammetrisk analys av kornstorleksfördelningeni erosionsskydd vid kraftverksdammar

This master thesis was made to investigate the possibilities of using the Matlab-basedsoftware Basegrain to determine grain size distributions of erosion protections onhydropower dams. Basegrain is a photogrammetric tool developed to generate grainsize distributions and other information about coarse flood sediments by analyzing adigital photo of the stone bed. The investigation was made by validating the ability forBasegrain to assess grain size distributions of various materials smaller than the blocksused in an erosion protection by comparing sieving results or manual measurementswith the results obtained by the program. A statistical comparison was then made bycomparing the results from sieving and the program. The possibilities of using thesame method on existing hydropower dams were then investigated by determiningwhether the method was practically viable or not.The results showed that Basegrain generated grain size distributions for coarse gravelthat were very close to the sieving results.

<- Föregående sida 6 Nästa sida ->