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.

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.

Saab Aerosystems has a long tradition and a lot of competence in the field of flight simulation. Their ambition to broaden the market horizon has led to a discussion about also selling vehicle simulation solutions, both for military and civilian use.The aim of this thesis is to investigate the driver?s experiences of the accelerations he or she is exposed to whilst driving in rough terrain. The results may be used as a basis for future decisions and can act as a platform for the construction of an effective simulation model.To investigate the driver?s exposure of acceleration, some kind of dynamic simulation is needed.

This report is a Master?s Thesis performed by Andreas Adolfsson and David Jacobsson atChalmers University of Technology. The purpose of this master?s thesis is to evaluate anew method for load-shedding, the voltage controlled underfrequency load-sheddingdeveloped by ABB. This report presents a comparison between conventionalunderfrequency load-shedding and this new method for load-shedding.

In this final thesis two simulation models have been integrated. The simulation models are models of JAS 39 Gripen?s fuel system, software and hardware. The time consuming and costly work to develop software has made the department of fuel system to build two models in Xmath/Systembuild. The software model also simplifies the comprehension of how the software in the control computer of the fuel system works.

There exist several known methods for calculation of radio coverage for ground-based systems. As far as we know there are no equivalent methods for the case of flying platforms when the altitudes and speeds are significantly different to those of ground-based systems. This thesis describes the theoretical concepts behind calculations of radio coverage for flying platforms. An investigation is made to sort out what is important and possible to employ in a model for simulations. A method is described and implemented in a program for evaluation of flying radio systems.

In this thesis, the Train Power System Simulator (TPSS) has been compared and verified with the commercial simulator TracFeed® Simulation (TracFeed). The basis for the comparison was a given part of the Swedish railway system, with steel transportation trains. Primarily, emphasis was placed on running time and energy consumption in simulation results. Two transformer systems were analyzed, booster and auto transformers. The high voltage transmission line, parallel to the railroad track, was disconnected in some simulations.

When models are used to describe physical phenomenon during development or modification of a technical system, it is often possible to reduce both the time needed and the overall development cost. With the use of models it is also possible to investigate the potential of the selected solution, without the need for any expensive details and testrigs. In many cases it is also not possible to test all the aspects regarding the functionality that are desired from the system, without using the complete and final product.In this case a model based approach has been used to optimize the different parameters in the new snubbing mechanism for the Nose Landing Gear Retract Actuator on the JAS39 Gripen.During the simulations, upper and lower boundaries were calculated for the length of the spring and the diameter for the restrictor. The governing constraints were given by the requirements for the retraction time during cold conditions and that the amplitude of the alternating loads in the uplock mechanism were brought to an acceptable level.The most promising results from the simulations were then used in a limited number of trials in the hydraulic rig to verify that the configurations comply with the requirements.The final parameters for the snubbing mechanism were chosen to 35±1mm for the spring and 0.4-0.5 mm diameter for the restrictor..

Nynas produces bitumen at two refineries in Sweden. The bitumen is shipped to seven depots along the swedish coast line, and from the depots special trucks handle the transportation to customers. Recently Nynas has transformed its supply chain and closed down a few depots. At the moment the company is considering a further reduction of the number of depots. In connection to these discussions an analyse of the companys distributionsystem and of possible changes is required.

This master thesis is a study on how a rategyro triad, an accelerometer triad, and a magnetometer triad can be integrated into a navigation system, estimating a vehicle?s attitude, i.e. its roll, tipp, and heading angles. When only a rategyro triad is used to estimate a vehicle?s attitude, a drift in the attitude occurs due to sensor errors.

In this thesis some different modulation schemes for xDSL-techniques are compared. The investigated techniques are ADSL, G.lite, ADSL2, HDSL, SHDSL and VDSL. The modulation methods used are DMT, CAP and different versions of PAM. Several broadband techniques also use Trellis Coded Modulation (TCM) to increase the coding gain of the transmission. For each one of the different modulation methods the signal-to-noise ratio is calculated for generating a bit error rate probability of 10-7.

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.

In the spring of 2014 Sweco Systems AB were commissioned to design a ventilation system for a newly built preschool in Linköping. Terms from the client was that it cost efficiency would cope with the energy demands that are placed on the building. The unit chosen was a cross-flow heat exchanger, and this work is to compare it with two other heat exchangers to see if a more energy and cost efficient could have been chosen. The heat exchangers that was chosen for the comparison was a rotating- and a counterflow heat exchanger. Simulations have been made to the different heat exchangers by the manufacturers.

This thesis has been performed at Scania CV AB Technical Centre in Södertälje and its aim hasbeen to study the causes and effects of deformations in the interface between the rear axlehousing ADA1100 and the central gear house R780 during operation. Design changes that wouldincrease the sealing capability of the studied interface are also suggested. Finite element (FE)and CAD software have been the primary tools in this study.Finite element (FE) simulations are used in the industry to predict and develop engineeringdesigns. The main motive for FE simulations has traditionally been to identify weak spots in thedesign, regarding high tensions and large deformations.The FE model is an aggregation of submodels and interface models that represents the rear axlehousing, suspension, central gear, central gear housing, wheels, bolts and weldings, and theirinteractions. The submodels have different material properties and they are connected withcontact interface models.Boundary conditions are defined on the bushings in front of the rear axle and on the air bellowsbehind the rear axle.

Valmets own foundry in Karlstad has during a long period of time had problems being profitable. The goal today is to turn this around. Today there are three different productionlines; engine blocks, Yankeecylinders and components for the wind turbine industry. This master thesis has focused on examining if value stream mapping is a useful tool to use in a foundry, and therefore outside the typical manufacturing industry. The target has also been to evaluate if there is a possibility to improve the flow in the foundry and also the results.During the 20 weeks this work has been done at the foundry data has been collected and analyzed.