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92 Uppsatser om Navier-Stokes equations - Sida 3 av 7

Modellering, identifiering och reglering av skannern i ett laserbatymetrisystem

The purpose with this masters thesis was to model the scanner in a system for laser bathymetry. The model was then used to develop a controller for the scanner so a good search pattern was achieved. Two different types of models have been tested, a physical model and a Black Box model of Box Jenkins type. The physical model has been derived from Lagranges equations. Identification experiments have been used to compute the Black Box model and to find the unknown parameters in the physical model.

Klimatsimulering av ett kontorsrum : Hur de termiska stigkrafterna påverkar ventilationseffektiviteten

AbstractIn urban societies people spend more and more time indoors, which put great demands on the indoor environment. If the ventilation is to manage the removal of unwanted substances in the indoor air, a good mixing of the air is required. The question arises that, whether the buoyancy forces will counteract a good mixing of the indoor air or not?This report aims to clear up the difficulties whether you need to consider the buoyancy forces or not, when adjusting a ventilation unit. For studying the indoor mixing of the air a two dimensional model is constructed in COMSOL Multiphysics.

Längdmätning i engreppsskördare

Detta examensarbete har gjorts på uppdrag av SP Maskiner AB och berör längdmätningsenheten på skördaraggregatet SP451LF. Pulsgivaren i den befintliga längdmätningen anses inte nå en acceptabel livslängd och därför skall ett sensorlager prövas som ersättare.Uppdraget består i att söka ett lämpligt sensorlager, dimensionera en komplett mäthjulslagring samt att ta fram ett konstruktionsförslag till prototyp på längdmätning.Arbetet begränsas av att den omkonstruerade längdmätningen skall passa på SP451LF aggregatet. Det betyder att längdmätningens infästning mot aggregatet inte får förändras och dess yttermått måste hållas inom de gränser som aggregatets chassi tillåter..

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.

Innovativt Drivpaket för Rullstol

This is a thesis for a Bachelor Degree Project, performed in the subject MechanicalEngineering. The students Roger Malmberg and Simon Hagberg have carried out adesign project on behalf of the recently established company J&D Assisting systems,located in Halmstad.The project consisted in developing J&D's first prototype of a power assisting solutionfor wheelchairs. A power assisted wheelchair combines human power, which is deliveredby the arms through the pushrims, with electrical motors, which are powered by a battery.The power assisted wheelchair is aimed at customers, who have used a regularwheelchair for a long time, but who have become weaker or just need additional powerwhen driving uphill. This kind of wheelchair will provide additional power for users,which will spare their wrists, elbow and shoulders. The product is torque sensor free andinstead it relies on the velocity.

GPU accelerated SPH simulation of fluids for VFX

Fluids are important to the Visual Effects Industry but extremely hard to control and simulate because of the complexity of the governing equations. Fluid solvers can be divided into two categories, those of the Eulerian point of reference and those of the Lagrangian. Both categories have different advantages and weaknesses and hybrid methods are popular. This thesis examines Smoothed Particle Hydrodynamics, a Lagrangian method for physically based uid simulations. To allow the artist the exibility given by shorter simulation times and increased number of iterations, the performance of the solver is key.

Automatiserad konstruktion av analoga förstärkare

The last few decades the development in the field of electronics has been huge. The components performance gets better at the same time as the manufacturing cost decreases. Many of the design moments that have to be done, are done automatically today, but it can get better. Especially for analog circuit design.At Electronic System in Linköpings universitet, research is in progress to develop a tool that can design analog circuits in reasonable time. It means that it has to size the components (transistors, resistances, capacitances etc), so that the circuit can fulfill the performance requirements.

A comparison of methods to assess site index in young Norway spruce stands

This study investigates whether the site index curve method (SICM) and the growth intercept method (GIM) can be used for site index predictions in younger Norway spruce (Picea abies (L.) Karst.) stands than recommended by current guidelines. For SICM it was thus investigated whether the method could be used for stands younger than ten years, and for GIM it was tested whether a starting point for the intercept measurements could be used below the recommended 2.5 meter. This was tested based on measurements taken from experimental stands in Tönnersjöheden Research Forest. For GIM it was found that the method can only be used when the TH-trees of a stand have five complete intercepts above 2.5 meters. For the method to be applicable beyond this, it will be necessary to adapt the underlying equations, perhaps following the Canadian example where a 1.3 meter intercept start is used. In conclusion it is not currently possible to apply the approach beyond the current recommendations. For SICM, SI predictions are accurate for the study area already form year three.

Modellering av Panna 5 Mälarenergi AB : utveckling av en beräkningsmodell med simuleringsverktyget IPSEpro

Heat and power stations are often in need of optimizations. A simulation model is a tool for findingways to optimize the plant. The scope of this diploma work is to develop a simulation model ofBoiler 5 at Mälarenergi AB. Boiler 5 is a circulated fluidized bed boiler that was taken into service inyear 2001. Among the included parts in the boiler are cyclone, convection part andINTREX-chambers.

Uppbyggnaden av ett foderstatsprogram för dikor :

The object with this work was to create a simple feeding program for beef cows. Another object was that I could learn more about the properties and functions of Excel and Visual Basic. I used parts of a program I designed a few years ago. This old program was neither user friendly nor had it an appealing layout. Initially I decided how I wanted the new program to appear and on which foundation it should be built. I designed various forms into a spread sheet, such as lists and multiple choice buttons. Using VBA (Visual Basic for Application) I could create macros, which used the information chosen in the lists and with the multiple choices to calculate the feeding requirement or the feeding plan.

A foreign aid dilemma : a study of budget support versus project aid

Foreign aid is a very debated and controversial topic. The most recent studies have focused more on GDP growth and foreign aid correlation, however not much of the debate has focused on what kind of foreign aid should be given. The most common foreign aid is budget support, often a bilateral funds transfer between two countries. This kind of foreign aid can be both conditional and unconditional from the donors? perspective.

Algebra och ekvationer ? att underlätta lärande : Lärandet börjar byggas vid första kunskapsmötet

Abstract This study aims with a pragmatic approach to investigate the learning about how to solve simple equations, and what the teacher can do to help the student. Four questions asked are: (i) How and why will learning take place? (ii) What will complicate learning? (iii) How to support and facilitate learning? (iv) Is it possible to identify an influence between identity and learning? To answer these questions a qualitative study in elementary school is done. The results of the investigation are compared with previous research, and an interview with the teacher is presented. The recorded lessons are analyzed with PEA (practical epistemology analysis), and letters from the students with the Ecological Systems Theory of Bronfenbrenner.

Är etiska fondinvesteringar försvarbara : vad kostar etik?

Recently, the selections of ethical funds are increased; at the same time investors with social and moral preferences have increased in the capital market. There are currently debates on whether ethical funds perform better or worse than funds without ethical criteria. This also involves a vivid discussion on whether investors know about the consequences of investing in ethical funds. Therefore, this study involves theories about the rationality and decision theory, in addition to what mainly control the investment decisions. The study also discusses portfolio theory since this is one of the underlying theories behind fund management and its development.The purpose of this study is to explain if ethical limitations in the selection of securities affect risk and return in the fund portfolio.

Analys av prispåverkande faktorer på bostadsrättsmarknaden i Uppsala

AimThe purpose of this study is to analyze factors that affect the price on tenant-owner apartments in the central parts of Uppsala. Special attention is put on analyzing how the monthly fee and the location affect the price. The hypotheses are that the monthly fee and the distance to the central part of the city have a negative effect on the price. A number of additional price affecting factors was taken in consideration during this study.MethodThis study is mainly based on data supplied to us by Mäklarstatistik. The supplied data consists of information about tenant-owner apartment sales in Uppsala during a year under 2008 and 2009.

Analys av turbulensmodeller för CFD

This thesis has been a part of Forsmarks Kraftgrupp AB's evaluation of a turbulencemodel used in simulation of turbulent flow called PRNS (Partially Resolved NumericalSimulation). This model has promising properties and may be of use in savingcomputational resources. The purpose of this thesis was to analyze this model andcompare it with industrially applied models such as k-omega SST and LES (Large EddySimulations).PRNS works as a hybrid of the k-omega SST and DNS (Direct Numerical Simulation)where a constant, RCP (Resolution Control Parameter) with a value between 0 and 1are selected. This constant is then used in the calculations and determines thebehavior of the simulation. When RCP is set to zero the equation are the same as fora DNS simulation and when RCP is set to one the equations for k-omega SST issolved.

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