Ett centralt processteg för sågverk är att sönderdela stockar med olika sågmönster. Vid sönderdelning uppstår ett visst råvaruspill, men genom att använda rätt sågmönster till varje enskild stock kan detta spill minimeras. Som ett steg i att göra detta försorteras därför timmer i ett antal timmerklasser som samlar stockar med liknande egenskaper. Råvarustyrning innebär att välja vilka mönster varje klass ska sågas med, hur stor andel av varje klass som ska sågas med dessa mönster samt att bestämma hur stockar sorteras till klasserna. I detta arbete utvecklas ett optimeringsverktyg som angriper problemet att optimera råvarustyrningen med avseende på de framställda produkternas försäljningsvärde. Problemet delas upp i två nivåer där linjärprogrammering kan användas i den ena nivån med syfte att, givet en uppsättning klasser, optimera valen av sågmönster. Linjärprogrammering används eftersom kubikmeterpriset på de sågade trävarorna antas vara konstant med avseende på producerad volym. Den andra problemnivån innebär att optimera timmersorteringen och för detta ändamål implementeras och utvärderas fyra lokalsökningsalgoritmer. Genom ett gränssnitt mot användare och databaser kan sågverk ladda in timmerdata, simulerade produktutfall när timmer sågas med olika sågmönster, samt lägsta och högsta tillåtna produktvolymer. Utöver optimering av råvarustyrning kan optimeringsverktyget användas som stöd för att skapa väl underbyggda kundofferter vid nya orderingångar eller väntade förändringar av råvarufördelning. Optimeringsverktyget klarar alltid av att hitta det optimala valet av postningar och postningsandelar givet en uppsättning klasser om det existerar minst ett val som uppfyller bivillkoren på framställda produktvolymer. Emellertid visar tester att denna beräkningsrutin gör anspråk på för mycket tid, men sannolikt kan den effektiviseras tillräckligt mycket för att användas skarpt i praktiken. Den bästa lokalsökningsalgoritmen fungerar tillfredsställande i tester, men det krävs mer utvecklingsarbete för att den ska rubriceras som helt klar. Främst i form av att möjliggöra för algoritmen att finna en lösning om sågverkets grundinställda klasser inte kan uppfylla bivillkoren på produktvolymer.Testdatat som används kommer från ett verkligt sågverk, men på grund av brister i detta data kan inga slutsatser dras angående ökad lönsamhet för sågverket genom användning av optimeringsverktyget. / A key process step in sawmills is the sawing of logs into wood, using various sawing patterns. A certain amount of waste always results when sawing, but by using the right sawing pattern for each individual log this waste can be minimized. One way to address this is to presort the incoming logs into a number of sawing classes, where all of these collect logs with similar properties. Raw material control at sawmills involves choosing the patterns to be used on each class, the share of each class to be sawn with the various patterns and also deciding the way logs are assigned to the sawing classes. In this work an optimization tool is constructed that addresses the problem of optimizing the raw material control with respect to the sales value of the manufactured products. The problem is divided into two sub-problems where linear programming can be used for one of these sub-problems with purpose to optimize the choices of sawing patterns given a set of classes. Linear programming can be used because the unit price of sawn goods is assumed to be constant with respect to the volume produced. The second sub-problem is to optimize the sorting of logs and in order to do this four different local search algorithms are implemented and evaluated. Through an user and database interface the sawmill can access sawlog data, simulated product outcomes and constraints for product volumes. In addition to optimization of the raw material control the optimization tool can help the user to create well-founded quotations whenever new orders arrive or the anticipated raw material distribution changes. The optimization tool always manages to find the optimal choice of sawing patterns and shares for a set of sawing classes given the existence of at least one choice that fulfills the constraints for manufactured product volumes. Tests show however, that this computational step requires too much time, but it can probably be streamlined enough to be used in practice.The best local search algorithm serves satisfactory in tests, but needs more development in order to be labeled as finished. Foremost by enabling the algorithm to find a solution even if the sawmill's default sawing classes can not fulfill the product volume constraints. The test data used when evaluating the algorithms come from a real sawmill, but due to shortcomings in the data no conclusions about increased profit for the sawmill can be drawn.

Since the beginning of the nuclear era, starting during the 1940s, large amount of radioactivity has been released into the environment. This thesis deals with the temporal and spatial distribution of the anthropogenic radioisotope 129I (T1/2= 15.7 Myr) in northern Europe. A routine sample preparation procedure for extraction of iodine from milligram amounts of solid materials has been developed and aimed for measuring the 129I concentration by the ultra-sensitive accelerator mass spectrometry method. The technique was further used for the analysis of 129I in sediments collected from two lakes in Sweden and one lake in Finland as well as sediments from two sites in the Baltic Sea. In addition, 129I concentrations in aerosol samples from northern and southern Sweden covering the period 1983 to 2000 have been measured. The results reveal a gradual increase in the anthropogenic 129I fluxes since the 1950s that are linked to emissions from the nuclear fuel reprocessing facilities in Sellafield (UK) and La Hague (France). A sharp increase coinciding with the Chernobyl accident is identified from the Swedish lakes located in areas characterised by relatively high Chernobyl fallout. Numerical modeling of the 129I deposition predicts that >50% of the flux to the lake sediments is related to the liquid emissions from the reprocessing facilities. The modeling also reasonably simulates the contribution of the Chernobyl event to the total 129I flux. The novel time series from northern Europe on 129I in aerosols show about one order of magnitude higher concentration in northern compared to southern Sweden. Estimate of 129I dry fallout based on the aerosol data suggests <25% contribution to the total fallout. The distribution of 129I in the sediment archives demonstrates the potential of the isotope as a new time marker for chronological and environmental investigations.

Wind power is a renewable energy source that is increasingly used all over the world. Most wind turbines have a horizontal axis of rotation but a few have a vertical axis of rotation. The concept presented in this thesis is a straight-bladed vertical axis wind turbine with a direct driven cable-wound permanent magnet synchronous generator. A comparison of the two different types of wind turbines, vertical axis wind turbines and horizontal axis wind turbines, have been performed considering several different aspects. However, the main focus in this thesis is on the generator. Several generators have been modelled with a combined field and circuit model, which has been solved by using the finite element method. A 12 kW generator has been designed, which has a high overall efficiency and a high overload capability. The generator has been constructed at the department and was tested in the laboratory before being mounted in a vertical axis wind turbine. Results from experiments correspond well with results from simulations. The generator has been tested for different loading conditions and the harmonic content of the voltage has been analysed. A 12 kW vertical axis wind turbine was completed and tests have been performed. The results are encouraging and further studies on the prototype will be performed in the future. The simulation method has been used to study electromagnetic losses in several generators. The comparison showed that the average losses should be considered when a variable speed generator for wind power is designed and it concluded that the design optimization process becomes a compromise between lowering the electromagnetic losses and having high overload capability. When constructing a wind turbine, it is important to consider vibrations in the structure. Torsional vibrations in the drive shaft connecting the turbine to the rotor of the generator have been studied. It is shown that a direct driven generator is to prefer over an induction generator with a gearbox when torsional vibrations are concerned. This thesis is based on eight papers all concerning vertical axis wind turbines with three of them focusing on the generator.

The existence of at or curved extra spatial dimensions provides new insights into several of the problems which face the Standard Model of particle physics, including the gauge hierarchy problem, the smallness of neutrino masses, and the dark matter problem. However, higher-dimensional gauge theories are not renormalizable and can only be considered as low-energy effective theories, with limited applicability. Dimensional deconstruction provides a class of manifestly gauge invariant possible ultraviolet completions of higher-dimensional gauge theories, formulated within conventional quantum eld theory. In dimensional deconstruction, the fundamental theory is a four-dimensional quantum eld theory and extra spatial dimensions are generated dynamically at low energies. In this thesis, we study di erent applications of dimensional deconstruction in the contexts of neutrino masses, mixing and oscillations, Kaluza{Klein dark matter, and e ective eld theories for discretized higher-dimensional gravity. A different possibility to understand the smallness of neutrino masses is provided by the see-saw mechanism. This is a genuinely four-dimensional mechanism, where the light neutrino masses are induced by the addition of heavy right-handed Majorana neutrinos or by other heavy degrees of freedom, such as scalar SU(2)L triplet elds. It has the attractive feature of simultaneously providing a mechanism for generating the observed baryon asymmetry of the Universe. We study in this context a specific left-right symmetric see-saw model. / QC 20100716

The purpose of this thesis is to gain understanding of the load on flat target surfaces produced by projectile impact. Models are proposed from which upper and lower bounds can be derived for the transition be-tween interface defeat and normal penetration. It is shown that the dominating contribution to the normal load is generally provided by the hydrodynamic pressure due to the effect of inertia. In addition it is shown that the contributions from yield strength and compressibility are also significant. For a cylindrical tungsten alloy projectile at an impact velocity representative of to-day’s ordnance velocities, the contributions to the load intensity on the axis of symmetry from yield strength and compressibility are shown to be 15% and 3.4%, respectively, of that of inertia. Impact tests have shown that for conical projectiles transition from interface defeat to penetration occurs at a significantly lower impact velocity than for cylindrical projectiles. In order to better understand the influence of projectile shape, a conical projectile in axi-symmetric impact is studied by use of an analytical model for self-similar flow, and the results obtained are compared to results of numerical simula-tions. It is shown how the maximum load intensity, and the position of the maximum, depends on the apex angle. For an apex angle of 90º, the maximum load intensity is found to be almost three times that pro-duced by a cylindrical projectile with the same impact velocity. This maximum occurs well off the axis of symmetry and is 20% larger than the load intensity at this axis. Both the self-similar model and the nu-merical simulations show that the contribution to the load intensity from compressibility is positive below and negative above an apex angle of around 80º. The contribution of yield strength to the load in-tensity at centre of impact depends only weakly on the apex angle and is therefore similar to that of a cylindrical projectile.

Engine components are exposed to vibrations which may lead to fatigue damage. Accurate dynamic simulations are necessary especially during the development process, in order to find a satisfactory component. Currently Scania uses a standard method for dynamic calculations that is based on a frequency response approach. A measured or calculated excitation yields a certain response through the transfer function of the system. The transfer function is obtained through an eigenfrequency calculation and an experience-based estimate of the modal damping. An obvious drawback of this method is that the estimated modal damping strongly affects the calculated response of the system. In this thesis, the method outlined above is compared to an alternative, so-called, inverse method in which the excitation of the system is calculated using a measured response. The advantage is that the modal damping does not affect the result directly since the excitation has been adjusted according to the response. As a demonstration object a charge air pipe and its bracket are used. Acceleration response data is collected from an engine vibration measurement. The calculated safety factor of the demonstration object is reasonable for both the standard method and the inverse method. An estimate of the quality of the model is obtained for the inverse method through statistical measures, which is not the case for the standard method. The excitation for the inverse method is adjusted to the estimated modal damping which is a major advantage since damping is notoriously difficult to quantify in engineering practice. The inverse method has proven to be a useful simulation method for calculations when a prototype of the engine component of interest already exists.

Grid-connected photovoltaic (PV) capacity is increasing worldwide, mainly due to extensive subsidy schemes for renewable electricity generation. A majority of newly installed systems are distributed small-scale systems located in distribution grids, often at residential customers. Recent developments suggest that such distributed PV generation (PV-DG) could gain more interest in Sweden in the near future. With prospects of decreasing system prices, an extensive integration does not seem impossible. In this PhD thesis the opportunities for utilisation of on-site PV generation and the consequences of a widespread introduction are studied. The specific aims are to improve modelling of residential electricity demand to provide a basis for simulations, to study load matching and grid interaction of on-site PV and to add to the understanding of power system impacts. Time-use data (TUD) provided a realistic basis for residential load modelling. Both a deterministic and a stochastic approach for generating different types of end-use profiles were developed. The models are capable of realistically reproducing important electric load properties such as diurnal and seasonal variations, short time-scale fluctuations and random load coincidence. The load matching capability of residential on-site PV was found to be low by default but possible to improve to some extent by different measures. Net metering reduces the economic effects of the mismatch and has a decisive impact on the production value and on the system sizes that are reasonable to install for a small-scale producer. Impacts of large-scale PV-DG on low-voltage (LV) grids and on the national power system were studied. Power flow studies showed that voltage rise in LV grids is not a limiting factor for integration of PV-DG. Variability and correlations with large-scale wind power were determined using a scenario for large-scale building-mounted PV. Profound impacts on the power system were found only for the most extreme scenarios. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 711

Part I of this thesis is a theoretical background to parts II and III. Part II treats the phenomenon of decreased visibility through a glazing due to external water condensation, dew, on the external surface. Some simulations are presented where it is shown that under certain circumstances condensation can be expected. A combination of coatings on the external surface is suggested to overcome the problem of external condesation. It consists of both a coating which decreases the emissivity of the surface and a hydrophilic coating which reduces the detrimental effects to the view through the window. Fresnel calculations of the optical properties are used to discuss the feasibility of using different coatings. A new test box was used to verify that the proposed window coatings perform as expected. Part III is a study on the angular dependence of solar absorptance in windows. Optical properties vary with the angle of incidence of the incoming light. The variation is different from one window pane to another. A model is proposed to approximate the angular variation of the solar absorptance in window panes. The model is semi-empirical and involves dividing the wide range of windows into nine groups. To which group a window belongs, depends on how many panes it has and on the features of the outer pane. The strength of the model is that it can be used without knowing the exact optical properties of each pane of the window. This makes it useful in the many cases when these data are not given by the manufacturer and Fresnel calculations to get the optical properties of the window are not feasible. The model is simple and can be added as an appendix to existing standards for measuring optical properties of windows.

In recent years, the interest for miniaturization of spaceborne instruments and subsystems has increased steadily, as this enables development of small and lightweight satellite classes as well as more versatile payloads on traditional spacecraft. In essence, this thesis work is an investigation of the applicability of magnetoresistive technology to a magnetometer intended for space. Two types of magnetoresistive sensors, promising with respect to performance competiveness also after considerable miniaturization, were developed and evaluated, namely magnetic tunnel junctions and planar Hall effect bridge sensors. In the case of the magnetic tunnel junctions, much effort was put on the micromanufacturing process. Two schemes were developed and evaluated for sensor contouring: one employing focused ion beam processes for rapid prototyping, and the other combining sputtering and x-ray photoelectron spectroscopy for precise etch depth monitoring during ion etching. For the former, the resulting implantation damages were investigated with chemical analysis and correlated to the sensor properties. In the latter, the depth of the etching was monitored live with a resolution sufficient to stop the etching in the 1 nm thick tunneling barrier. The effect and extent of redeposition were investigated by transmission electron microscopy and micromagnetic analysis. With the knowledge so gained, the tunneling magnetoresistance of the manufactured junctions could be improved significantly and their inherent noise could be reduced. As a step in space flight qualification, the magnetic tunnel junctions were subjected to both g and particle radiation, leaving them unaffected by the first, but rendering them a reduced tunneling magnetoresistance ratio and an increased coercivity by the latter. In the case of the planar Hall effect bridge sensors, their inherent noise was thoroughly investigated, revealing both electric and magnetic 1/f noise at low frequencies along with thermal noise at higher frequencies. In addition, an analytical model of the magnetic properties of the planar Hall effect bridges was developed, and a design process, based on the model, was established to optimize the bridges for a particular application. In conclusion, both types of sensors show great promises for use in space. Of the two, the planar Hall effect bridge sensors had a better detection limit at low frequencies, whereas the magnetic tunnel junctions were more precise at higher frequencies. However, both sensors had a bandwidth greatly exceeding that of traditional spaceborne magnetometers. A magnetometer employing the magnetic tunnel junctions from this work is currently included as payload onboard the Vietnamese satellite F-1 scheduled for launch this year. A magnetometer using magnetoresistive sensors – planar Hall effect sensors, magnetic tunnel junctions, or both – enables a mass reduction of more than two orders of magnitudes compared with traditional systems.

Scratch is a block programming language which introduces beginners to programming. Instead of code the user has access to a set of blocks with text and icons, explaining how the block will affect the program that is written. The connection between one block and the corresponding code can be hard to understand for the beginner. The goal of this project is therefore to develop a user-friendly, flashcard-based mobile application to show the target group of 8- to 16-year-olds that behind every block there is code. The application is developed in TypeScript, using React Native as framework and the developer tool Expo for setting up and publishing of the application. The final application consists of 6 different screens; a starting screen, an information screen, a menu, a submenu, an "under development"-screen and a flashcard view. The user can navigate between the screens and by choosing a specific block the flashcard view displays a flashcard with the block and the corresponding translation in Python. The goal of the project is fulfilled, and with a testing group it is also confirmed that the application is user-friendly. Although the goal is achieved, the conclusion that the step between block programming and syntax is hard can be drawn, with difficulties in translating the blocks appearing along the way.