In Sweden, reduced tillage usually means non-inversion tillage, where primary tillage is carried out using chisel ploughs or disc implements. Primary tillage method is mainly determined by the desired soil loosening and the handling of soil residues. The effect of tillage depth was studied in field experiments in Skåne, Väderstad, Uppsala, Örebro och Västerås in different crops; spring oilseed rape, spring wheat, winter wheat and spring barley.The experiments generally had a randomized block design with the treatments mouldboard ploughing, deep chisel ploughing and shallow chisel ploughing, in some cases also shallow discing and no-tillage. In the experiments the following parameters were determined: seedbed properties, saturated hydraulic conductivity, penetration resistance, number of emerged plants and crop yield (all parameters were not determined in all experiments. Root growth and draught requirement were determined in two separate studies. There were no significant differences between tillage depths in non-inversion tillage in seedbed properties, plant emergence or root development.

Syftet med denna studie var att kontrollera om och i så fall hur mycketvisus förbättras med toriska linser jämfört med sfäriska linser vid astigmatism -0,50 D - -1,00 D.I studien ingick tolv försökspersoner, fördelat på nio kvinnor och tre män, medcylinder mellan -0,50 D och -1,00 D på ett eller båda ögonen korrigerades först medAir Optix® (sfärisk) beräknad på sfärisk ekvivalent och sedan med Air Optix forAstigmatism®(torisk) med styrkor baserade på refraktionen. Högkontrastvisus ochlågkontrastvisus mättes både monokulärt och binokulärt.I studien framkom att i både monokulärt och binokulärt finns en statistisktsignifikant förbättring med den toriska linsen jämfört med den sfäriska. Ävenlågkontrastvisus visar en förbättring både monokulärt och binokulärt med den toriskalinsen, denna skillnad är inte statistiskt signifikant. Även vid 0,50 D cylinder finnsäven här en förbättring med den toriska linsen men denna är inte heller statistisktsignifikant, varken för hög eller lågkontrastvisus. För 1,00 D cylinder är förbättringensignifikant vid högkontrast men inte vid lågkontrastS.

Projektet genomfördes på Ingenjörsfirma Edman & Sjöberg AB i Filipstad. Syftet med projektet var dels att utreda möjligheterna med att använda sig av vattenhydraulik, men även presentera nytänkande lösningar för ingående detaljer av en hydraulcylinder. Kvaerner Pulping AB, som var kund, efterfrågade en enklare cylinder som fortfarande klarade kraven till låg kostnad. Önskemålet om nytänkande lösningar rörde främst hur kolvstången kan hållas ren från avlagringar samt att lösa genomströmningen i toppläget av rörelsen. Arbetet skulle mynna ut i ritningsunderlag för att senare generera en prototyp av cylindern.

Severe floods caused by heavy autumn rains in year 2000 raised the question whether measures to reduce the damage from high water levels, in the area surrounding lake Glafsfjorden and along the river Byälven down to lake Vänern, are possible. One option is to reduce flow resistance along the river and thereby lower the maximum water level a given inflow would cause. Good knowledge of hydraulic and hydrological conditions is necessary in order to estimate the effect of such flow-reducing measures. In order to quantify such effect a 1-dimensional hydraulic flow model has been set up for the river Byälven using the software package MIKE 11. The model is more detailed, especially concerning topography and bathymetry, than earlier models used for studies of the river.

The euthropthication of the Baltic Sea is a threat that is beginning to be taken seriously by the governments concerned. In Sweden, regulations concerning the allowed nitrogen (N) concentration in the effluent water from wastewater treatment plants are being tightened up. The Rimbo wastewater treatment plant has been imposed to reduce the annual mean concentration of total N in the effluent water to levels below 15 mg l-1. A more and more common way to reduce the nitrogen level in wastewater is to let the water pass through a wetland. This study investigates the possibility to build this kind of wetland at the outlet of the Rimbo wastewater treatment plant.A prestudy of the topography, soil characteristics and groundwater flow indicates that the land area in question is well suited for the construction of a wetland.

Marinediesel has, to meet there customers needs for a suitable sterndrive to powerboats, developed a prototype. The prototype is currently in the testing phase. The opportunity to test the sterndrive under load inside the workshop has not previously been possible. Until now the drive has been tested in a test bench without any load on the propeller axle. The prototype has also been tested under real conditions mounted on a boat.The idea with my thesis was to create a test bench that can run around the clock in order to be able to test things like wear and service intervals and other things that require that the test interval is long.

One of the environmental problems today in seas, lakes and streams is eutrophication. This is often caused by nutrients such as phosphorus (P) and nitrogen (N) that leak from agricultural areas. A measure to partly prevent the nutrient discharge is to construct or restore wetlands.In order to control the efficiency of nutrient reduction of existing wetlands in the county, the administrative board in Västra Götaland wants to find different criterias for reference wetlands. These reference wetlands should represent other wetlands and be used in future evaluations of reduction of nutrients and design of constructed wetlands. According to the administrative board in Västra Götaland the reference wetlands should have a catchment area of about 50 hectare consisting of at least 70 % arable land, to represent wetlands created to remove nutrients.

This master thesis consists of the creation of shock absorber models for percussive rock drills. A model of the rock was also developed. These models were connected to existing models of the rock drill to create a complete simulation of the rock drilling process.When the models had been created the rock model was evaluated by comparison with measured values from lab tests. The verified rock model was then used to evaluate the shock absorber models.Four new shock absorber concepts have been developed. Three of these have been modelled, while the fourth have only been sketched and described.The evaluation of the models showed the following:? Simulations of the single shock absorber don?t correlate to reality very well.

Utvecklingsavdelningen för hydraulcylindrar på Bosch Rexroth AB har identifierat ett marknadssegment för en lågpriscylinder som kan arbeta med högt tryck. Företaget har idag en lågpriscylinder på marknaden och vill vidareutveckla denna för att klara högre tryck. Detta examensarbete har utförts som en förstudie med syftet att presentera olika konstruktionslösningar av nuvarande cylinders ingående delar, för att erhålla de önskade egenskaperna. Arbetet började med att ingående bryta ner den nuvarande cylindern i mindre delar för analys. Det gjordes även en studie av konkurrenterna och vad deras sortiment har att erbjuda.

Mosquitoes are found in extremely large numbers in the lower parts of the River Dalälven. In the year 2000 the mosquito nuisance was especially high, resulting in foundation of the Biological mosquito control project. Since 2001 mosquito larvae are controlled by using a biological pesticide BTI (Bacillus thuringiensis ssp israelensis). The mosquito fauna in the area is dominated by flood water mosquitoes, a group of mosquitoes that are very aggressive and form new generations of mosquitoes during every single flooding event during the summer. To be able to efficiently control the mosquitoes it is essential to know the extension and locality of the flooding.

The main object of this diploma work thesis is about how computer programs can bea tool to use for work on stormwater investigations. The advantage of using acomputer program compared with calculations made by hand is evaluated anddiscussed. The computer programs that have been used for studies and a sequence oftesting of the possibilities are Autodesks Storm and Sanitary Analysis and DHIs MikeUrban.Focus on sustainable development now permeates the building industry. As a resultstormwater investigations have been conducted in an increasing extent the recentyears. Stormwater is water produced due to precipitation, such as rain and snowmelt.Stormwater investigations normally contain descriptions of existing land use, plannedland use and suggestions of measures and technical solutions for the future disposal ofstormwater.The initial part of the thesis consisted of literature studies on stormwater andstormwater investigations to understand the science.

Simulation is a vital tool during development of JAS 39 Gripen, since money and time can be saved.The Auxiliary and Emergency Power System, AEPS, is a subsystem of the secondary power system in Gripen. It has the function of providing the aircraft with electrical and hydraulical power before activation and after deactivation of the main engine. The system also functions as backup in case of a safety critical problem in the main power supply system. The system basically consists of a control unit and an auxiliary gearbox. The gearbox is driven by an air turbine.

Hydroware Elevation Technology AB sells control and regulation equipment for hydraulic elevators. The company now wants to investigate the possibility of changing their present softstarters to frequency inverters to supply power to their pump engines. They also want to investigate the possibility of future use in so called ?intelligent? houses.The purpose of this report is to investigate these possibilities..

In this master thesis a robot arm belonging to an automatic milking machine from DeLaval is investigated. The robot arm is controlled by a pneumatic cylinder and a valve. The goal of the master thesis is to investigate instability problems and to find out if it is possible to solve them by using gain scheduling. Gain scheduling is a type of controller where the parameters of the controller are changed during operation, for example depending on the working point. First a nonlinear mathematical model of the system was made.

This thesis work is the last part of the Master of Science education inmechanical engineering at KTH, Stockholm.The aim of this project was the development of a Multi-zone modelfor NOxformation in Diesel engines. Because of the stringent emissionlegislations, great effort is made to decrease the fuel consumption and theharmful emissions of internal combustion engines. Computer simulationsplay a decisive role in this context because they substitute the expensiveand time-consuming laboratory tests.The model is based on a multi-zone approach and uses the wellknownExtended Zeldovich Mechanism which gives a relation to calculatethe NO formation rate using the concentration of different gas speciesinvolved in the process.All the most important phenomena involved in the Diesel combustionhave been modelled. A special attention is then paid to the equilibriumconcentration calculation; this is a significant part of the model whichstrongly influences the following steps.A Simulink model has also been developed. This second version isbased on the previous model and it is made especially to allow theconnection with other external softwares, GT-power in this case.