Model Reduction of Muscle-Driven Tissue Models

Biomechanical simulations are a necessary tool for a proper understanding of biomechanics and hence are subject to intense research. One field that relies on this research is articulatory speech synthesis as it attempts to simulate the physics of the speech production process. Out of the many aspects involved, muscle driven tissue is one of the most important as it is required to simulate the deformable structures of the vocal tract. Modelling of muscle driven tissue requires continuum models of high complexity for the purpose of accuracy. On the other hand, time-efficient models are desirable in order to provide fast simulations which enable the user to test input parameters interactively. These requirements impose limitations on each other as the time-efficiency of a model is reduced with increasing complexity, hence techniques that can bridge the gap between these requirements are needed. This thesis attempts to bridge this gap through two major contributions. Model reduction techniques, that up until now have only been applied to inactive materials, have been implemented and tested for muscle driven tissue models. The implementation has been made in a general way to ensure that it can be used for biomechanical simulations in other fields than articulatory speech synthesis. In addition, the implementation has been made such that it can handle more advanced simulations than those investigated in this thesis. The simulations show acceptable but not ideal accuracy in both dynamic simulations and in measurements of equilibrium configurations. In addition, the reduced simulations using hyperreduction show good speedup for the more complex models investigated

An investigation of Fe XV emission lines in solar flare spectra

Previously, large discrepancies have been found between theory and observation for Fe XV emission line ratios in solar flare spectra covering the 224-327 A wavelength range, obtained by the Naval Research Laboratory's S082A instrument on board Skylab. These discrepancies have been attributed to either errors in the adopted atomic data or the presence of additional atomic processes not included in the modelling, such as fluorescence. However our analysis of these plus other S082A flare observations (the latter containing Fe XV transitions between 321-482 A), performed using the most recent Fe XV atomic physics calculations in conjunction with a CHIANTI synthetic flare spectrum, indicate that blending of the lines is primarily responsible for the discrepancies. As a result, most Fe XV lines cannot be employed as electron density diagnostics for solar flares, at least at the spectral resolution of S082A and similar instruments (i.e. ~ 0.1 A). An exception is the intensity ratio I(321.8 A)/I(327.0 A), which appears to provide good estimates of the electron density at this spectral resolution.Comment: 6 pages, 3 figures, Astronomy & Astrophysics, in pres

Recent Extreme Ultraviolet Solar Spectra and Spectroheliograms

Extreme ultraviolet solar spectra and spectroheliogram analyse

Evidence of Impulsive Heating in Active Region Core Loops

Using a full spectral scan of an active region from the Extreme-Ultraviolet Imaging Spectrometer (EIS) we have obtained Emission Measure EM$(T)$ distributions in two different moss regions within the same active region. We have compared these with theoretical transition region EMs derived for three limiting cases, namely \textit{static equilibrium}, \textit{strong condensation} and \textit{strong evaporation} from \cite{ebtel}. The EM distributions in both the moss regions are strikingly similar and show a monotonically increasing trend from $\log T[\mathrm{K}]=5.15 -6.3$. Using photospheric abundances we obtain a consistent EM distribution for all ions. Comparing the observed and theoretical EM distributions, we find that the observed EM distribution is best explained by the \textit{strong condensation} case (EM$_{con}$), suggesting that a downward enthalpy flux plays an important and possibly dominant role in powering the transition region moss emission. The downflows could be due to unresolved coronal plasma that is cooling and draining after having been impulsively heated. This supports the idea that the hot loops (with temperatures of 3{-}5 MK) seen in the core of active regions are heated by nanoflares.Comment: 17 pages, 4 figures, Accepted for publication in The Astrophysical Journa

Urban green in Vientiane, Lao PDR : a minor field study

This is a Minor field study addressing the current situation in Vientiane, Laos where focus lies on the green structures past, present and future. The city of Vientiane is growing rapidly and as a result of this there is a increasing development. The once peaceful capital known for it’s lush and green environment is standing in a crossroad where important decision must be made to preserve valuable areas. During 8 weeks inventories and observations where made resulting into a proposal for future development. The proposal is divided into three parts. The urban fringe and surrounding landscape are still quite undeveloped and have a great potential of green wedges etc. The city of Vientiane and the green network linking important recreational, commercial and cultural places. Detailed proposal over certain green objects such as parks and squares.Detta är ett examensarbete där den nuvarnade situationen I Vientaiane med fokus på grönstrukturens förflutna, nutid och framtid bearbetas. Vientaines invånare ökar dagligen I antal och som resultat av detta ökar bebyggelse trycket på stan. Den en gång lugna och lummiga staden star inför ett vägskäl där viktiga beslut måste fattas för att bevara den speciella karaktären. Under 8 veckor inventerade och observerades Vientianes grönstruktur för att kunna ge förslag på framtida utveckling. Förslagen är uppdelade i tre delar. Det omgivande landskapet, staden Vientaine och groan object såsom parker och torg

Kohonneen verenpaineen seulonta keski-ikäisessä väestössä

Syventävien opintojen tavoitteena oli perehtyä kohonneen verenpaineen seulontaan suomalaisessa keski-ikäisessä väestössä. Kohonnut verenpaine on maailmanlaajuisesti merkittävin terveitä elinvuosia vähentävä riskitekijä ja yksi merkittävimmistä kardiovaskulaarisairauksien riskin suhteen. Kohonnut verenpaine ei juurikaan itsessään aiheuta oireita, joten ainoa keino kohonneen verenpaineen havaitsemiselle on systemaattinen seulonta. Syventävien opintojen tutkielmassa käytetään Harjavallassa ja Kokemäellä vuosina 2005–2007 Kokemäenjokilaakson valtimotautien ehkäisyprojektin yhteydessä kerättyä tutkimustietoa. Tutkimuksessa 45–70-vuotiaille kotona asuville kuntalaisille lähetettiin postitse kutsukirje tutkimukseen sekä kyselykaavake kardiovaskulaarisairauksien riskinarviointia varten. Tutkimuskutsuun vastanneiden keskuudesta seulottiin tutkimuskaavakkeiden avulla tutkittavat, joilla oli suurentunut riski kardiovaskulaarisairauksiin ja heidät kutsuttiin tarkempiin tutkimuksiin. Tutkimusaineistossa verenpaine oli kohonnut jopa 60 % tutkittavista. Keski-ikä tutkimusaineistossa oli 57 vuotta ja naisia tutkittavista oli 50 %. Kohonneen verenpaineen yhteydessä oli useammin todettavissa metabolinen oireyhtymä tai sokeriaineenvaihdunnan häiriö verrattuna tutkittaviin, joilla verenpaine oli normaalirajoissa. Kohonneen verenpaineen yhteydessä oli todettavissa myös keskimäärin heikompi nilkka-olkavarsipainesuhde ja täten myös enemmän perifeeristä valtimotautia verrattuna tutkittaviin, joilla verenpaine oli normaalirajoissa. Tutkimustulos tukee aiempia suosituksia verenpaineen seulonnasta ja sen tarjoamista hyödyistä

Використання алгоритмів евристичного типу у процесі розв’язування рівнянь та нерівностей

(uk) В статті розглядається використання приписів алгоритмічного типу при розв’язуванні рівнянь та нерівностей з параметром у контексті застосування сформованих в учнів умінь дослідження властивостей функцій.(en) The using of algorithmic directions in equations and inequalities with a parameter solving in the movement of application of students’ skills in exploration of functions’ properties is considered in the article

Abundance variations and first ionization potential trends during large stellar flares

The Solar First Ionization Potential (FIP) effect, where low-FIP elements are enriched in the corona relative to the photosphere, while high-FIP abundances remain unchanged, has been known for a long while. High resolution X-ray spectroscopy has revealed that active stellar coronae show an opposite effect, which was labeled the Inverse-FIP (IFIP) effect. The correlation found between coronal activity and the FIP/IFIP bias suggested perhaps that flaring activity is involved in switching from FIP to IFIP. This work aims at a more systematic understanding of the FIP trends during stellar flares and complements an earlier study based on Chandra alone. The eight brightest X-ray flares observed with XMM-Newton are analyzed and compared with their respective quiescence states. Together with six previous flares observed with Chandra, this establishes the best currently available sample of flares. We look for abundance variations during the flare and their correlation with FIP. For that purpose, we define a new FIP bias measure. A trend is found where coronae that are IFIP biased in quiescence, during flares show a FIP bias with respect to their quiescence composition. This effect is reversed for coronae that are FIP biased in quiescence. The observed trend is thus consistent with chromospheric evaporation rather than with a FIP mechanism operating during flares. It also suggests that the quiescent IFIP bias is real and that the large flares are not the direct cause of the IFIP effect in stellar coronae.Comment: 12 pages, 6 figures, submitted to A&

The Solar Photospheric-to-Coronal Fe abundance from X-ray Fluorescence Lines

The ratio of the Fe abundance in the photosphere to that in coronal flare plasmas is determined by X-ray lines within the complex at 6.7~keV (1.9~\AA) emitted during flares. The line complex includes the He-like Fe (\fexxv) resonance line $w$ (6.70~keV) and Fe K$\alpha$ lines (6.39, 6.40~keV), the latter being primarily formed by the fluorescence of photospheric material by X-rays from the hot flare plasma. The ratio of the Fe K$\alpha$ lines to the \fexxv\ $w$ depends on the ratio of the photospheric-to-flare Fe abundance, heliocentric angle $\theta$ of the flare, and the temperature $T_e$ of the flaring plasma. Using high-resolution spectra from X-ray spectrometers on the {\em P78-1} and {\em Solar Maximum Mission} spacecraft, the Fe abundance in flares is estimated to be $1.6\pm 0.5$ and $2.0 \pm 0.3$ times the photospheric Fe abundance, the {\em P78-1} value being preferred as it is more directly determined. This enhancement is consistent with results from X-ray spectra from the {\em RHESSI} spacecraft, but is significantly less than a factor 4 as in previous work.Comment: Accepted for publication by MNRA

Coronal loop hydrodynamics. The solar flare observedon November 12 1980 revisited: the UV line emission

We revisit a well-studied solar flare whose X-ray emission originating from a simple loop structure was observed by most of the instruments on board SMM on November 12 1980. The X-ray emission of this flare, as observed with the XRP, was successfully modeled previously. Here we include a detailed modeling of the transition region and we compare the hydrodynamic results with the UVSP observations in two EUV lines, measured in areas smaller than the XRP rasters, covering only some portions of the flaring loop (the top and the foot-points). The single loop hydrodynamic model, which fits well the evolution of coronal lines (those observed with the XRP and the \FeXXI 1354.1 \AA line observed with the UVSP) fails to model the flux level and evolution of the \OV 1371.3 \AA line.Comment: A&A, in press, 6 pages, 5 figure