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Coming dissertations at TekNat

  • Phenomenology of new Neutral Vector Bosons and Parton Distributions from Hadronic Fluctuations

    Author: Andreas Ekstedt
    Publication date: 2019-06-04 13:42

    The Higgs particle was first predicted in 1964, and was discovered in the summer of 2012 at the Large Hadron Collider (LHC). This discovery was the latest in a long list of successful Standard Model predictions spanning the last fifty years. However, some of the Standard Models predictions, such as massless neutrinos, are not in agreement with experiment. Thus, extensions of the Standard Model should be considered. Furthermore, some issues, such as how quarks are bound within the proton, are difficult to study from first principles.

    In paper I and II of this thesis, a class of models that contains a new TeV scale neutral vector boson is studied. The parameter space of this class of models is constrained using electroweak precision constraints and 13 TeV LHC data. Gauge anomalies are cancelled both by choosing appropriate fermion charges, and by adding Green-Schwarz terms.

    The Higgs mechanism is often studied at leading order, but there are also important radiative corrections. These radiative corrections, which change the ground state energy, can both be IR divergent and gauge dependent. In paper III it is shown how to solve both of these problems. In particular, IR...

  • Designing grinding tools to control and understand fibre release in groundwood pulping

    Author: Magnus Heldin
    Publication date: 2019-05-29 11:00

    Mechanical pulping is a very energy demanding process in which only a fraction of the energy is used for the actual separation of wood fibres. The rest of the energy is lost, partly in damaging already separated fibres and partly as heat during viscoelastic deformation of the wood. Groundwood pulping is one of the major mechanical pulping processes. In this process, a piece of wood is pressed against a rotating grinding stone. The stone surface has traditionally been made of grinding particles fused to a vitrified matrix. Though the process is close to 200 years old, the detailed mechanisms of the interactions between the grinding particles and the wood surface are still not fully understood. The random nature of the grinding stones combined with the heterogeneous nature of wood creates a stochastic process that is difficult to study in detail. This work utilizes well-defined tools, that facilitate testing and analysis, to increase the understanding of the tool-wood-interaction. In-situ tomography experiments were performed with such well-defined tools, to study the deformations and strains induced in the wood as the tool asperities engage the wood surface. Numerical...

  • Hybrid observers for systems with intrinsic pulse-modulated feedback

    Author: Diana Yamalova
    Publication date: 2019-05-27 11:07

    Dynamical processes resulting from the interaction of continuous and discrete dynamics are often encountered in living organisms. Time evolutions of such processes constitute continuous variables that are subject to instant changes at discrete points of time. Usually, these discrete events cannot be observed directly and have to be reconstructed from the accessible for measurement continuous variables.

    Thus, the problem of hybrid state estimation from measurements of continuous outputs is important to and naturally arises in life sciences but, so far, scarcely covered in the existing literature.

    This thesis deals with a special class of hybrid systems, where the continuous linear part is controlled by an intrinsic impulsive feedback that contributes discrete dynamics. The impacting pulsatile feedback signal is not available for measurement and, therefore, has to be reconstructed. To estimate all the elements of the hybrid state vector, an observation problem is considered.

    The focus of the work is on a state observation problem for an analytically tractable example of a hybrid oscillator with rich nonlinear dynamics including, e.g.,...