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370 Uppsatser om Numerical simulations - Sida 13 av 25
Towards sustainable rye cultivation : soil carbon and yield modelling for crop rotations with rye
Using the Introductory Carbon Balance Model, ICBM, five different crop rotations with rye
1. Rye-Ley-Ley-Rye-Beans-Rye
2. Rye-Rye-Rapeseed-Rapeseed
3. Rye-Ley-Ley-Rye-Potatoes-Rye
4. Rye-Rye-Potatoes-Wheat
5. Rye-Rye-Potatoes-Beans-Wheat-Rye-Potatoes-Rapeseed
were tested theoretically in four different cultivation scenarios
? Straw left on the field, biogas digestate added as fertilizer. Labelled ?+straw+BD?.
? Straw left on the field, only synthetic fertilizer. Labelled ?+straw-BD?.
? Straw harvested, biogas digestate added as fertilizer.
Sänkt returtemperatur : Potentiell besparing i fjärrvärmesystem
Optimizing energy systems is, in Sweden, as in many other countries, of growing interest. District heating systems are no exception. In 2012, 285 out of 290 municipals in Sweden had district heating in use and the majority of these systems have a higher return temperature than that which is possible with an error-free substation of day current technology. To, when possible, lower the return temperature is a way of increasing the effectiveness of the district heating system.This study means to investigate, through simulations and calculations, how big of a reduction in production cost a lower temperature in the city of Ystad?s district heating system would correspond to.
Studie av skyddsavstånd mellan bergvärmeanläggning och skyddsobjekt i ett vattenskyddsområde
During installation and operation of a geothermal heat pump system leakage of an antifreezing agent can appear in a borehole and leak out in surrounding groundwater. To guarantee high quality drinking water for generations to come Sweden has dedicated some areas as water protection areas. The local authority gives permits for the installation of heat pump systems within water protection areas. Before giving a permit the local authority makes an evaluation of the risks involved in installation and operation of the system within the area. By keeping a certain distance between the protected object in the area and the heat pump system the risk of polluting the protected object with an anti-freezing agent can be reduced.This thesis makes a comparison between three different methods of calculating an appropriate distance between the protected object and the heat pump system.
Matvanor bland 15-åriga pojkar och flickor i Uppsala län
Aim: To describe perceptions about written and verbal information regarding diet and physical activity in women with breast cancer and to study possible differences between ages and perception. Method: A cross-sectional study was conducted and consisted of 57 women with breast cancer stages I-III who started adjuvant chemotherapy within a year (2007-2008). A questionnaire, regarding their perceptions about the written and verbal information they had received about diet and physical activity, was responded to three months following treatment completion. Between 67-93 % of the participants responded to the questions. The answers was analyzed with descriptive statistics and Mann Whitney U-test.
Krafter på rörsystem vid transient flöde : En jämförelse mellan RELAP5 och Fluent
At Forsmarks Kraftgrupp AB (FKA) forces on pipe systems due to transient flow are frequently calculated as a step to verify their structural integrity. In nuclear industries these forces are often calculated with a one dimensional thermal-hydraulic analysis-code called RELAP5. When calculations regarding more complex geometries are needed, the three dimensional code Fluent is often used. This code is highly time consuming and requires large computational power.This projects aim is to compare calculations of pressure, flow and forces carried out by RELAP5 and Fluent for an arbitrary pipe section during transient flow conditions. This has been accomplished by constructing a simple geometry for which a transient flow is simulated in both programs.
Kariesprevalensen hos barn och ungdomar 3-19 år i de nordiska länderna
Aim: The aim of this present study was to assess the dental caries prevalence in children and adolescents aged 3-19 in the Nordic countries, and to examine if the caries prevalence is affected by socioeconomic and cultural differences.Method: The study is a literature review based on 20 scientific medical reports based on the aim of this study.Result: Decayed missed filled surfaces (dmfs) of the 3-year-olds varies from 0.3 to 0.99 and from 0.9 to 7.3 in 5-year-old children. The Nordic 12-year-olds have similar numerical values. In Nordic 14-year-olds caries prevalence increases. In the late teens there is a reduction in caries prevalence. Children at Greenland have five times more teeth decayed than other Danish children.
Att gestalta en socialt hållbar begravningsplats
This thesis aims to present the essential background on how to perform climate changeimpact assessments, and to present the results from a climate impact assessment on waterbalance and nitrate leaching for an arable Swedish soil. The soil is a sandy soil in southwesternSweden, grown with spring cereals. This study is meant to be a benchmark example,and cannot be seen as a regional or national assessment for Sweden, rather as an approachto present and analyze the most important parts of these kinds of assessments.A dynamical simulation model (COUP, Jansson and Karlberg, 2004) was used for thisstudy. The model was parameterized and calibrated against data from an experimental site,located in Mellby in Hallands county, south western Sweden. Measurements were carriedout between 1st of April 1988 and 1st of April 1991.
Modellering och simulering av hovrande helikopter
At the department of Electronic Warfare Assessments at the Swedish Defence Research Agency in Linköping one of the activities is modelling and simulation of the duel between a robot and a target. The aim with this Master's thesis is to develop a simulation model of an hovering helicopter. First a theoretical description of the forces and moments acting on an helicopter is given. Then the equations of motion are derived. These equations are simplified to be valid only for a hovering helicopter and the result is a mathematical model.
Optimering av spjällhus för dragracing
Detta examensarbete utreder en ny typ av spjällhus som optimerats för dragracing. Spjällhuset styr luftflödet till förbränningsmotorn och regleras av gashandtaget. Konceptet är utvecklat av Emtes Ingenjörsbyrå och i examensarbetet ingår att konstruera ett spjällhus med det nya konceptet för motorcykelmodellen Suzuki Hayabusa. Det standardmonterade spjällhuset är anpassat för gatubruk och ett brett effektregister. För dragracing är den maximala effekten avgörande och det standard monterade spjällhuset är en flaskhals vid WOT (Wide Open Throttle).För konceptet saknas dock fullständiga lösningar för diverse funktioner.
Water balance and nitrate leaching from arable land in a changed climate : a model study
This thesis aims to present the essential background on how to perform climate changeimpact assessments, and to present the results from a climate impact assessment on waterbalance and nitrate leaching for an arable Swedish soil. The soil is a sandy soil in southwesternSweden, grown with spring cereals. This study is meant to be a benchmark example,and cannot be seen as a regional or national assessment for Sweden, rather as an approachto present and analyze the most important parts of these kinds of assessments.A dynamical simulation model (COUP, Jansson and Karlberg, 2004) was used for thisstudy. The model was parameterized and calibrated against data from an experimental site,located in Mellby in Hallands county, south western Sweden. Measurements were carriedout between 1st of April 1988 and 1st of April 1991.
En indirekt metod för adaptiv reglering av en helikopter
When a helicopter is flying, the dynamics vary depending on, for example, speed and position. Hence, a time-invariant linear model cannot describe its properties under all flight conditions. It is therefore desirable to update the linear helicopter model continuously during the flight. In this thesis, two different recursive estimation methods are presented, LMS (Least Mean Square) and adaptation with a Kalman filter. The main purpose of the system estimation is to get a model which can be used for feedback control.
Hjälpkraftsystem med två lågspänningsnivåer
Because of increasing demand of power on Malmbanan the capacity of the existing wires which supply the trains must be increased. This increases the stress on the existing poles and for this reason the system for supplying the loads along the railway is to be removed from the poles and be replaced by some other system. This thesis is a study on a two-level low voltage (1 kV and 0.4 kV) electrical system with the aim to investigate if it can be an alternative to the system used today taking into account the voltages, fault currents and costs.In this thesis the following tasks have been performed:? Gathering of data? Description of basic theory? Loadow and fault current calculations of the system with MATLAB? Life Cycle Cost estimate of the system? Analysis and conclusions from the resultsThe results show that the new system can be an alternative to replace today's system. The simulations and calculations show that the voltage drop is at an acceptable level and that the fault currents are large enough to supply a safe disconnection if a fault occurs at the far end of the system..
Är vi artiga mot virtuella agenter?
The CASA-paradigm, Computers Are Social Actors, was introduced in the book "TheMedia Equation" by Reeves and Nass. One of their experiments concluded that we tend to be polite to computers in the same way as we are to people. In this study I have replicated Reeves and Nass experiment but instead of a text-based interface I have used a virtual agentin order to find out if we are polite to the agents, or still to the computer. Two experimental setups was conducted. The two setups had a common first part that was carried out on onecomputer with one agent.
Stöldskydd
To save energy it?s popular to build houses with low energy loss. In these houses the walls are keeping a lower temperature in the external side which leads to a higher relative humidity. In addition more material, such as wood studs, are used which means that there is more moisture to dry. More moisture in combination with higher relative humidity may pose a higher risk of microbial growth.
Rackmonterad elektrolyscell
This report shows methods and workflow when exploring the potential to change Outotecs HCD Silver Electrolysis machine to a module type. It?s done as an attempt to lower the workshop and installation costs and to give customer a more accurate prize directly. To do this a concept was produced which was set to a stress test. Additional objectives were to investigate freight and installation procedures, pneumatic connections and to calculate the difference in cost.Once the concept, a reinforced type of the original frame, was chosen stress tests in computer simulations were made and appropriate alterations were made.