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  • Presentation: 2019-10-07 10:00 KTH, sal A124, plan 1, 100 44 Stockholm
    Lundgren, Marja
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies. White arkitekter AB.
    Performance in the Swedish Building Code: An Inquiry into the Consequences for Architectural Design of the Formulation and Assessment of Performance Requirements2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis investigates performance-based regulation in Sweden and its consequences for architectural design. In the last 50 years, there has been a transition from prescriptive to performance-based regulation, propelled by the drive to further innovation, productivity and competitiveness by expressing the functions expected of the buildings as performances. This thesis examines the promise of freedom in design and solution that this regulatory construction offers, considering two specific performance aspects of the Swedish building code: the requirements regarding energy performance in relation to user-comfort, and the requirement in terms of daylight in relation to health and hygiene. Each case investigates the implications of the performance-based system of regulation for the synesthetic and multidisciplinary process of design, focussing on how it affects the work of architects.This thesis also addresses the disciplinary knowledge necessary for assessing performance requirements, which in turn connects to the entry into building regulation of abstract natural science models quantifying societal goals in legislation, and to the disciplinary histories of the engineering and architectural professions.Speculating on ways forward that address the concerns that emerge from this analysis, the thesis turns to a historical example that dealt with a similar problem to evaluate its potential for developing current architectural practice. The dual nature of design, reaching into both expressional and technical concerns, has been the subject of research and eloquent discussion within the architectural concept of tectonics. The concluding section of this thesis raises questions about the architectural discourse in relation to tectonics. It suggests that there is work to be done to reconcile the division between architectural design and technical characteristics connected to building physics that permeates systems of building regulation in Sweden and more generally. The thesis suggests that if performance-based regulation is to offer freedom in architectural design, the architecture community needs to be much more involved in both the research and critique of performance requirements and of their formulation and assessment methods when addressing this.

  • Presentation: 2019-10-10 10:00 F11
    Berglund, Daniel
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Models for Additive and Sufficient Cause Interaction2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this thesis is to develop and explore models in, and related to, the sufficient cause framework, and additive interaction. Additive interaction is closely connected with public health interventions and can be used to make inferences about the sufficient causes in order to find the mechanisms behind an outcome, for instance a disease.

    In paper A we extend the additive interaction, and interventions, to include continuous exposures. We show that there does not exist a model that does not lead to inconsistent conclusions about the interaction.

    The sufficient cause framework can also be expressed using Boolean functions, which is expanded upon in paper B. In this paper we define a new model based on the multifactor potential outcome model (MFPO) and independence of causal influence models (ICI).

    In paper C we discuss the modeling and estimation of additive interaction in relation to if the exposures are harmful or protective conditioned on some other exposure. If there is uncertainty about the effects direction there can be errors in the testing of the interaction effect.

  • Presentation: 2019-10-11 10:00 V2, Stockholm
    Umsonst, David
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Tuning of Anomaly Detectors in the Presence of Sensor Attacks2019Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Critical infrastructures, such as the power grid and water distribution networks, are the backbone of our modern society. With the integration of computational devices and communication networks in critical infrastructures, they have become more efficient, but also more vulnerable to cyberattacks. Due to the underlying physical process, these cyberattacks can not only have a financial and ecological impact, but also cost human lives. Several reported cyberattacks on critical infrastructures show that it is vital to protect them from these attacks. Critical infrastructures typically rely on accurate sensor measurements for optimal performance. In this thesis, we, therefore, look into attacks that corrupt the measurements.

    The first part of the thesis is concerned with the feasibility of a worst-case sensor attack. The attacker's goal is to maximize its impact, while remaining undetected by an anomaly detector. The investigated worst-case attack strategy needs the exact controller state for its execution. Therefore, we start by looking into the feasibility of estimating the controller state by an attacker that has full model knowledge and access to all sensors. We show that an unstable controller prevents the attacker from estimating the controller state exactly and, therefore, makes the attack non-executable. Since unstable controllers come with their own issues, we propose a defense mechanism based on injecting uncertainty into the controller. Next, we examine the confidentiality of the anomaly detector. With access to the anomaly detector state, the attacker can design a more powerful attack. We show that, in the case of a detector with linear dynamics, the attacker is able to obtain an accurate estimate of the detector’s state.

    The second part of the thesis is concerned with the performance of anomaly detectors under the investigated attack in the first part. We use a previously proposed metric to compare the performance of a χ2, cumulative sum (CUSUM), and multivariate exponentially weighted moving average (MEWMA) detectors. This metric depends on the attack impact and average time between false alarms. For two different processes, we observe that the CUSUM and MEWMA detectors, which both have internal dynamics, can mitigate the attack impact more than the static χ2 detector. Since this metric depends on the attack impact, which is usually hard to determine, we then propose a new metric. The new metric depends on the number of sensors, and the size of an invariant set guaranteeing that the attack remains undetected. The new metric leads to similar results as the previously proposed metric, but is less dependent on the attack modeling. Finally, we formulate a Stackelberg game to tune the anomaly detector thresholds in a cost-optimal manner, where the cost depends on the number of false alarms and the impact an attack would cause.

  • Presentation: 2019-10-17 10:00 FB42, Stockholm
    Pernow, Marcus
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Phenomenology of SO(10) Grand Unified Theories2019Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Although the Standard Model (SM) of particle physics describes observations well, there are several shortcomings of it. The most crucial of these are that the SM cannot explain the origin of neutrino masses and the existence of dark matter. Furthermore, there are several aspects of it that are seemingly ad hoc, such as the choice of gauge group and the cancellation of gauge anomalies.

    These shortcomings point to a theory beyond the SM. Although there are many proposed models for physics beyond the SM, in this thesis, we focus on grand unified theories based on the SO(10) gauge group. It predicts that the three gauge groups in the SM unify at a higher energy into one, which contains the SM as a subgroup. We focus on the Yukawa sector of these models and investigate the extent to which the observables such as fermion masses and mixing parameters can be accommodated into different models based on the SO(10) gauge group. Neutrino masses and leptonic mixing parameters are particularly interesting, since SO(10) models naturally embed the seesaw mechanism.

    The difference in energy scale between the electroweak scale and the scale of unification spans around 14 orders of magnitude. Therefore, one must relate the parameters of the SO(10) model to those of the SM through renormalization group equations. We investigate this for several different models by performing fits of SO(10) models to fermion masses and mixing parameters, taking into account thresholds at which heavy right-handed neutrinos are integrated out of the theory. Although the results are in general dependent on the particular model under consideration, there are some general results that appear to hold true. The observ- ables of the Yukawa sector can in general be accommodated into SO(10) models only if the neutrino masses are normally ordered and that inverted ordering is strongly disfavored. We find that the observable that provides the most tension in the fits is the leptonic mixing angle θ2l3, whose value is consistently favored to be lower in the fits than the actual value. Furthermore, we find that numerical fits to the data favor type-I seesaw over type-II seesaw for the generation of neutrino masses.