Examensarbetet går ut på att utreda hur störningsnivån varierar över tid i elnätet samt ett antal olika ställen inom Norrlands universitetssjukhus, Umeå. Elektrisk fältmätning ingick också i arbetet för att undersöka om det fanns ett samband mellan det elektriska fältet och övertoner i sjukhusets elnät. Examensarbetet presenterar grundläggande teori om elnät, elkvalité och parametrar som beskriver elkvalité, t.ex. övertoner, flimmer och transienter. Förslag på hur övertonshalten kan reducera tas även upp. Mätningarna av elkvalitets parametrar genomfördes med ett antal mätinstrument. Insamlat mätdata analyserades i några olika programvaror. Undersökningen visar att övertonshalten varierade mycket över dygnet och var högst på intensivvårdsavdelning där maxvärdet på spänningsövertonshalten THDu var 4,01%. Ström, spänning och frekvens var inte stabila, dvs. transienter och flimmer har uppstått under mätningen. Analysen av mätdata visar att den totala spänningsövertonshalten THDu var under 5% och inte överskred gränsvärdet 8% som anges i standarden SS-EN 50 160. / The aim of the thesis was to examine whether the level of disturbance in the power grid vary between different types of care environment over time at University Hospital of Umeå. Electric field measurement was also included in the thesis to investigate whether there was a connection between the electric field and harmonics in the hospital’s power grid. The thesis presents basic theory about power grid, power quality and parameters which describe power quality, such as, harmonics, flicker and transients. Suggestions on how to reduce the harmonic content will also be discussed. The measurements of the power quality parameters were performed by using different measuring equipment. The data were analyzed using different software. The study shows that the harmonic content often varied and was highest in intensive care unit, where the maximum value of the harmonic voltage distortion THD was 4,01%. The measurement shows that current, voltage and frequency were not stable, that is transients and flicker occurred several times during the measurement. The analysis of the data shows that the harmonic voltage distortion THDu was below 5% and never above the limit 8% which is specified in the standard SS-EN 50 160.

The Blended-Wing-Body is a conceptual aircraft design with rear-mounted, over wing engines. Turboelectric distributed propulsion system with boundary layer ingestion has been considered for this aircraft. It uses electricity to transmit power from the core turbine to the fans, therefore dramatically increases bypass ratio to reduce fuel consumption and noise. This dissertation presents methods on designing the TeDP system, evaluating effects of boundary layer ingestion, modelling engine performances, and estimating weights of the electric components. The method is first applied to model a turboshaft-driven TeDP system, which produces thrust only by the propulsors array. Results show that by distributing an array of propulsors that ingest a relatively large mass flow directly produces an 8% fuel burn saving relative to the commercial N+2 aircraft (such as the SAX-40 airplane). Ingesting boundary layer achieves a 7-8% fuel saving with a well-designed intake duct and the improved inlet flow control technologies. However, the value is sensitive to the duct losses and fan inlet distortion. Poor inlet performance can offset or even overwhelm this potential advantage. The total weight of the electric system would be around 5,000-7,000 kg. The large mass penalties further diminish benefits of the superconducting distributed propulsion system. The method is then applied to model a turbofan-driven TeDP system, which produces thrust by both the propulsors array and the core-engines. Results show that splitting the thrust between propulsors and core-engines could have a beneficial effect in fuel savings, when installation effects are neglected. The optimised thrust splitting ratio is between 60-90%, the final value depends on the propulsor intake pressure losses and the TeDP system bypass ratio. Moreover, splitting the thrust can reduce the weight of the electric system with the penalty of the increased core-engine weight. In short, if the power density of the superconducting system were high enough, turboshaft-driven TeDP would be preferable to power the N3-X aircraft.

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Azimuthal anisotropy, assumed to be associated with vertical, aligned cracks, fractures, and subsurface stress regimes, causes vertically propagating shear waves to split into a fast component, with particle motion polarized parallel to fracture strike, and a slow component, with particle motion polarized perpendicular to fracture strike. Determining the polarization of each split shear wave and the time lag between them provides valuable insight regarding fracture azimuth and intensity. However, analysis of shear wave polarizations in seismic data is hampered by reflection-induced polarization distortion. Traditional polarization analysis methods are limited to zero offset and are not valid if implemented over the full range of offsets available in typical 3D seismic data sets. Recent proposals for normalizing amplitudes recorded at non-normal incidence to values recorded at normal incidence may provide an extension to correcting offset-dependent shear wave polarization distortion. Removing polarization distortion from shear wave reflections allows a larger range of offsets to be used when determining shear wave polarizations. Additional complexities arise, however, if fracture orientation changes with depth. Reflections from layers with different fracture orientations retain significant energy on off-diagonal components after initial rotations are applied. To properly analyze depth-variant azimuthal anisotropy, time lags associated with each interval of constant anisotropy are removed and additional iterative rotations applied to subsequent offset-normalized reflections. Synthetic data is used to evaluate the success of these methods, which depends largely on the accuracy of AVA approximations used in the correction. The polarization correction effectively removes SV polarity reversals but may be limited in corrections to SH polarizations at very far offsets. After the polarization correction is applied, energy calculations including incidence angles up to 20° more effectively compensates individual SV and SH reflection components, allowing for more faithful polarization information identification of the isotropy plane and the symmetry axis. The polarization correction also localizes diagonal component energy maxima and off-diagonal component energy minima closer to the true orientation of the principal axes when a range of incidence angles up to 20° is used. / text

The considerable progress in the research and development of thin-walled beam structures responds to their growing use in engineering construction and to their increased need for efficiency in strength and cost. The result is a structure that exhibits large shear strains and important non uniform warping under different loadings, such as non uniform torsion, shear bending and distortion... A unified approach is formulated in this thesis for 3D thin walled beam structures with arbitrary profile geometries, loading cases and boundary conditions. A single warping function, defined by a linear combination of longitudinal displacements at cross sectional nodes (derived from Prokic work), is enhanced and adapted in order to qualitatively and quantitatively reflect and capture the nature of a widest possible range of behaviors. Constraints are prescribed at the kinematics level in order to enable the study of arbitrary cross sections for general loading. This approach, differing from most published theories, has the advantage of enabling the study of arbitrary cross sections (closed/opened or mixed) without any restrictions or distinctions related to the geometry of the profile. It generates automatic data and characteristic computations from a kinematical discretization prescribed by the profile geometry. The amount of shear bending, torsional and distortional warping and the magnitude of the shear correction factor is computed for arbitrary profile geometries with this single formulation. The proposed formulation is compared to existing theories with respect to the main assumptions and restrictions. The variation of the location of the torsional center, distortional centers and distortional rotational ratio of a profile is discussed in terms of their dependency on the loading cases and on the boundary conditions. A 3D beam finite element model is developed and validated with several numerical applications. The displacements, rotations, amount of warping, normal and shear stresses are compared with reference solutions for general loading cases involving stretching, bending, torsion and/or distortion. Some examples concern the case of beam assemblies with different shaped profiles where the connection type determines the nature of the warping transmission. Other analyses –for which the straightness assumption of Timoshenko theory is relaxed– investigate shear deformation effects on the deflection of short and thin beams by varying the aspect ratio of the beam. Further applications identify the cross sectional distortion and highlight the importance of the distortion on the stresses when compared to bending and torsion even in simple loading cases. Finally, a non linear finite element based on the updated lagrangian formulation is developed by including torsional warping degrees of freedom. An incremental iterative method using the arc length and the Newton-Raphson methods is used to solve the non linear problem. Examples are given to study the flexural, torsional, flexural torsional and lateral torsional buckling problems for which a coupling between the variables describing the flexural and the torsional degrees of freedom occurs. The finite element results are compared to analytical solutions based on different warping functions and commonly used in linear stability for elastic structures having insufficient lateral or torsional stiffnesses that cause an out of plane buckling.

Detection of earth-size exoplanets using the astrometric signal of the host star requires sub-microarcsecond measurement precision. One major challenge in achieving this precision using a medium-size (< 2-m) space telescope is the calibration of dynamic distortions. A diffractive pupil can be used to generate polychromatic diffraction spikes in the focal plane, which encode the distortions in the optical system and may be used to calibrate astrometric measurements. The first half of this dissertation discusses the design and construction of a laboratory to test this concept. The main components of the system are a high stability star simulator, a diffraction limited off-axis optical system, and the data reduction algorithms to obtain the distortion map calibration. Currently, the laboratory is operational and first tests of distortion measurements have been done validating this concept to improve the astrometric accuracy of a telescope. The second part of this dissertation describes the use of the multi-laser guide star (LGS) system available at the 6.5 m MMT telescope to characterize GLAO performance and advance Laser Tomography Adaptive Optics (LTAO) technology. The system uses five range-gated and dynamically refocused Rayleigh laser beacons to sense the atmospheric wavefront aberration. Corrections are then applied to the wavefront using the 336-actuator adaptive secondary mirror of the telescope. So far, the system has demonstrated successful control of ground-layer aberration over a field of view (FoV) substantially wider than is delivered by conventional adaptive optics, yielding reduction in the width of the on-axis point-spread function from 1.07" to < 0.2" in H band. Both techniques can be combined to improve the astrometric accuracy of ground based telescopes, especially when using Multi-Conjugated Adaptive Optics (MCAO). A diffractive pupil can be used to calibrate the distortions induced by multiple Deformable Mirrors (DM), which is the main limitation to use this kind of AO system for high precision astrometric measurements.

This thesis compares insurance premium principles with current financial risk paradigms and uses distorted probabilities, a recent development in premium principle literature, to synthesize the current models for financial risk measures in banking and insurance. This work attempts to broaden the definition of value-at-risk beyond the percentile measures. Examples are used to show how the percentile measure fails to give consistent results, and how it can be manipulated. A new class of consistent risk measures is investigated.

<p>This dissertation consists of two independent musical compositions and an article detailing the process of the design and assembly of an electric guitar with particular emphasis on the carefully curated suite of embedded effects. </p><p>The first piece, 'Phase Locked Loop and Modulo Games' is scored for electric guitar and a single echo of equal volume less than a beat away. One could think of the piece as a 15 minute canon at the unison at the dotted eighth note (or at times the quarter or triplet-quarter), however the compositional motivation is more about weaving a composite texture between the guitar and its echo that is, while in theory extremely contrapuntal, in actuality is simply a single [superhuman] melodic line.</p><p>The second piece, 'The Dogma Loops' picks up a few compositional threads left by ‘Phase Locked Loop’ and weaves them into an entirely new tapestry. 'Phase Locked Loop' is motivated by the creation of a complex musical composite that is for the most part electronically transparent. 'The Dogma Loops' questions that same notion of composite electronic complexity by essentially asking a question: "what are the inputs to an interactive electronic system that create the most complex outputs via the simplest musical means possible?"</p><p>'The Dogma Loops' is scored for Electric Guitar (doubling on Ukulele), Violin and Violoncello. All of the principal instruments require an electronic pickup (except the Uke). The work is in three sections played attacca; [Automation Games], [Point of Origin] and [Cloning Vectors]. </p><p>The third and final component of the document is the article 'Finding Ibrida.' This article details the process of the design and assembly of an electric guitar with integrated effects, while also providing the deeper context (conceptual and technical) which motivated the efforts and informed the challenges to hybridize the various technologies (tubes, transistors, digital effects and a microcontroller subsystem). The project was motivated by a desire for rigorous technical and hands-on engagement with analog signal processing as applied to the electric guitar. ‘Finding Ibrida’ explores sound, some myths and lore of guitar tech and the history of electric guitar distortion and its culture of sonic exploration.</p> / Dissertation

Titel: Hur engageras medarbetare i ledningens vision? En studie inom intern kommunikation.  Nyckelord: Internal communication, hierarchical communication, corporate communication, organizational communication, sensemaking, employee engagement, message distortion  Syfte: Skapa ökad förståelse för hur en ledning, via sin interna kommunikation, kan öka medarbetarnas engagemang.  Metod: Studien har utförts med en kvalitativ ansats där data samlats in via intervjuer med tretton respondenter fördelade på ledningsgrupp, enhetschefer, gruppchefer och medarbetare.  Bidrag: Genom praktisk tillämpning av en teoretisk modell (Welch &amp; Jackson 2007) har en visions väg genom en organisation granskats. Aktiviteter har identifierats vilka kan förklara graden av engagemang samt hur väl visionen förankrats på medarbearnivå.  Originalitet: Intervjuerna är utförda på samtliga nivåer i en hierarkisk organisation. Studien täcker således mer än en nivås perspektiv på den interna kommunikationen. / Title: How do employees become engaged in the top management ́s vision? A study within internal communication.  Key words: Internal communication, hierarchical communication, corporate communication, organizational communication, sensemaking, employee engagement, message distortion  Purpose: To increase the understanding of how a management, through the use of internal communication, can increase the employees’ engagement.  Method: The study has been conducted with a qualitative approach. Data has been assembled through 13 interviews with top management, unit managers, group managers, and employees.  Contributions: By practical application of a theoretical model (Welch &amp; Jackson 2007), a vision's path through an organization has been reviewed. Activities have been identified that can explain the level of engagement and how well the vision has anchored on employee level.  Originality: The interviews have been conducted on all levels of a hierarchical organization. Therefore, the study covers more than one group’s perspective on the internal communication.

Path models assessed different models of influential order for parental bonding; adult romantic attachment; views of self, world/others, and the future; the fear of intimacy; and cognitive distortions among child molesters and non-offending controls. Child molesters receiving sex offender treatment reported more problematic parental bonding; insecure adult romantic attachment; negative views of self, world/others, and the future; a greater fear of intimacy, and more cognitive distortions regarding adult-child sex. The predicted path models were not established as the models did not adequately fit the data. However, post hoc logistic regressions indicated that Maternal Optimal Bonding, Preoccupied attachment, and cognitive distortions regarding adult-child sex significantly predicted child molester status. Overall, the findings provide support for a multi-factorial model of child molestation derived from attachment theory. Limitations of the study and areas for future research are also discussed.