Our purpose with this qualitative study is to investigate how teachers experience their work situation, using Karasek and Theorell?s demand-, control- and support model. The study is based upon ten semi-structured interviews with gymnasium teachers. The interviews were transcribed and coded with three different themes; demand, control and support. We analyzed the results with Karasek and Theorell?s mentioned model.

This study deals with one of the most discussed work environmental issues in the modern society of Sweden today - work related stress, its causes and how stress can affect people in their working situation. Our study is based on a questionnaire among aid handling officers in two municipalities of the middle of Sweden, and two interviews with their directors. We found that aid handling officers has a complex occupational role. We also found that the officers in these two municipalities experiences about the same level of stress.Further in the study, we will deal with whatever could be the cause of the stressful situation, using the demand/control model of Karasek and Theorell. The result shows that despite the similarity of the stress experience, the cause was shown to be different.

The control of indoor temperature must be able to handle large time constants and both measureable disturbances like outdoor temperature, and non-measurable disturbances, like waste heat from appliances. Due to cheaper microcontrollers (small computers with designated tasks) with better performance, more advanced and computation-demanding methods for control can be used.In this thesis, Generalized Predictive Control (GPC) has been implemented and tested on a theoretically derived model of a house. GPC states that a model of the system is estimated in every sample, and the control is carried out simultaneously, based on predictions of the model. Disturbances like solar radiation can be estimated and used in the control as well. The control signals are determined by quadratic programming, which makes it possible to consider conditions, for example limitations on the control signals.GPC requires a number of parameters to be defined, like model order and control signal penalty, but is relatively robust for variations in them.

This thesis has been conducted at Saab Bofors Dynamics AB. The purpose was to investigate if a non-linear missile model could be stabilized when the optimal control signal is computed considering constraints on the control input. This is particularly interesting because the missile is controlled with rudders that have physical bounds. This strategy is called Model Predictive Control. Simulations are conducted to compare this strategy with others; firstly simulations with step responses and secondly simulations when the missile is supposed to hit a moving target.

In industrial control systems PID-control remains the prevalent strategy, also for processes that would benefit from model based control. The purpose of this thesis is to evaluate whether model based control can be readily implemented in an industrial control system. To this end a simulated surge tank with a simulated industrial control system is studied. For evaluation two scenarios with specified objectives are selected.Following a review of LQR and versions of MPC, Predictive Functional Control (PFC) is considered the most suitable for implementation. PFC is a form of MPC developed with industrial applications in mind and therefore has several advantages for implementation in an industrial control system.

A cars powertrain consists of everything that is needed for its propulsion. The components in the driveline that transfer the power from the engine to the driven wheels are not absolutely stiff, hence they will wind up due to the torque and act as torsion springs. If you suddenly demand a bigger torque by stepping on the accelerator pedal, a so called tip in manoeuvre, and that torque is acquired from the engine as quickly as possible, the driveline will not be able to transfer that fast torque change due to its weakness and as a result it will start to oscillate. These oscillations will be transferred to the driven wheels and make the car to accelerate jerkily which will be experienced as uncomfortable by the passengers. Furthermore, there is a backlash in the driveline that will make the weakness in the driveline even more excited than it should have been if the backlash did not existed.To avoid too big problems with these oscillations there is a control system that controls the demanded torque.

Many organizational changes have been accomplished in elder care since the 1980's and many of those have been influenced by market mechanisms. The purpose of this study is to examine how the implementation of these market mechanisms has affected three important aspects in the work situation for personnel. These aspects are, demand, control and support. To attain the purpose of this study, five qualitative interviews with home care personnel have been carried out. The interview material has been analyzed and structured with the help of Karasek and Theorells demand-control-support model.

This master?s thesis describes the development of a model of the catalystsystem aiming at control by an MPC. A well functioning model, which is suitable in control purpose, is important while emission legislation become more and more hard to fulfill for the car manufacturers. Much research has been done in the field of physical modeling of the system, but in this work a linear adaptive time discrete ARX-model is developed and validated.The systems tendency to change its dynamic during usage implies that the model must be adaptive. The developed model proved to be well functioning and shows promising conditions for the MPC design.

The purpose of this study was to determine if and how the city district of Södra Innerstaden in Malmö, by using the Skärholms model, demand their client to reciprocate. The first problem set was to see how the demand was shown in the social service act from year 1998. From there the motives behind the introduction of the Skärholms model in city district of Södra Innerstaden were researched and also if there were a demand on reciprocity in city district of Södra Innerstaden public administration. The study was conducted in an exploratory way. The method used was to describe the idea behind Skärholms model after examining documents from the public administration.

This essay answers the question: How can a manufacturing business fulfill the information demand in the processes; purchasing, production, warehousing, order and delivery?The question has been answered through different kind of studies, such as literature, documents, Internet search, interviews and observations. The essay is written from a hermeneutic point of view and by using qualitative research. The result has been validated by two different manufacturing businesses.A simple information logistic model is the result of a comparison made between theory and empery. The aim of the model is to describe how a manufacturing business can fulfill the information demand by using different methods.

This master thesis deals with problems in the arc length control in Pulsed MIG/MAG Welding. The main problem is that it is not possible to measure the arc length. In the present solution the voltage over both the electrode and the arc represents the arc length. To improve the arc length control a model of the electrode melting has been built. One output from the model is the voltage over the electrode and with this voltage together with the measured voltage it is possible to calculate the voltage over just the arc.

AbstractThe purpose with this study was to get knowledge if there are any possible differences in, and correlation between, experienced stress, experienced demands, experienced control and experienced social support in correlation to shiftwork.The study was made at two central hospitals in south of Sweden and had 90 participants (78 women and 12 men) that answered a questionnaire in the current variables. The result in experienced stress showed that there were no differences between shift workers. The results showed a difference between the day- and the nightshift in the correlation between control and stress. The writers speculates that the reason why the nightshift experience high stressvalues with high control can depend on the lack of presence by higher managers, compared with the dayshift. .

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.

Intelligent IT-based solutions, often called Smart Grids, are considered to be the future balancers of renewable energy sources. One area within the Smart Grid concept is called demand response, which is focused on making customers more consumption flexible by making them more active in their consumption. In this thesis the aim is to analyze a business model by investigating the income potential for a demand response solution as well as its market potential. This has been done through literature studies, interviews and development of a computational model.The use of 5000 households with flexible consumption can provide a cost reduction of 17.2% or 2.4 million SEK for a balance responsible party during an average year. If the solution is used to make strategic bids on the regulation markets the study indicates that the largest potential for revenues lies within this strategy.

This report treats two assignments that concerns the biofuel furnace at Billerud Skärblacka AB and how these assignments were solved. The assignments were: reducing the number of CO-spikes and tuning the overfire air control loop. To reduce the number of CO-spikes the possibility that skewness in mass distribution affects the number of CO-spikes were study. The skewnwss of mass distribution was controled and adjusted with two experiments. The conclusion that was made is that the skewness of mass distribution were not sufficient enough to affect the number of CO-spikes.