| 1. |
- Abbas, Qaisar, et al.
(författare)
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Energy Stability of the MUSCL Scheme
- 2010
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Ingår i: Proc. 7th South African Conference on Computational and Applied Mechanics. - Berlin : South African Association for Theoretical and Applied Mechanics. ; , s. 65:1-8, s. 61-68
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Abbas, Qaisar, 1975-
(författare)
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Weak Boundary and Interface Procedures for Wave and Flow Problems
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, we have analyzed the accuracy and stability aspects of weak boundary and interface conditions (WBCs) for high order finite difference methods on Summations-By-Parts (SBP) form. The numerical technique has been applied to wave propagation and flow problems.The advantage of WBCs over strong boundary conditions is that stability of the numerical scheme can be proven. The boundary procedures in the advection-diffusion equation for a boundary layer problem is analyzed. By performing Navier-Stokes calculations, it is shown that most of the conclusions from the model problem carries over to the fully nonlinear case.The work was complemented to include the new idea of using WBCs on multiple grid points in a region, where the data is known, instead of at a single point. It was shown that we can achieve high accuracy, an increased rate of convergence to steady-state and non-reflecting boundary conditions by using this approach.Using the SBP technique and WBCs, we have worked out how to construct conservative and energy stable hybrid schemes for shocks using two different approaches. In the first method, we combine a high order finite difference scheme with a second order MUSCL scheme. In the second method, a procedure to locally change the order of accuracy of the finite difference schemes is developed. The main purpose is to obtain a higher order accurate scheme in smooth regions and a low order non-oscillatory scheme in the vicinity of shocks.Furthermore, we have analyzed the energy stability of the MUSCL scheme, by reformulating the scheme in the framework of SBP and artificial dissipation operators. It was found that many of the standard slope limiters in the MUSCL scheme do not lead to a negative semi-definite dissipation matrix, as required to get pointwise stability.Finally, high order simulations of shock diffracting over a convex wall with two facets were performed. The numerical study is done for a range of Reynolds numbers. By monitoring the velocities at the solid wall, it was shown that the computations were resolved in the boundary layer. Schlieren images from the computational results were obtained which displayed new interesting flow features.
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| 3. |
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| 4. |
- Abramsson, Marianne, 1963-, et al.
(författare)
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Bostadsmarknad och bostadsformer för andra halvan av livet
- 2012. - 1
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Ingår i: Äldres boende - forskningsperspektiv i Norden. - Lund : Studentlitteratur. - 9789144075952 ; , s. 155-168
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- I denna antologi diskuteras äldres boendeförhållanden utifrån ett samhälls- och individperspektiv. Äldres boende inkluderar såväl kvarboende i vanliga bostäder som boende i bostäder särskilt avsedda för äldre.I boken behandlas fysiska och sociala aspekter på boendet, äldres bostadsmarknad och boendepreferenser. De olika kapitlen exemplifierar olika sätt att studera äldre och deras boendesituation och visar på den variation av områden inom vilka forskning om äldres boende bedrivs.Tillsammans ger de en bred bild av äldres boendesituation och lyfter fram de frågor som särskilt berör äldre, alltifrån de friska och mer rörliga äldre med stora valmöjligheter till de multisjuka äldre som lever längre med sina sjukdomar.Denna heterogenitet ställer stora krav på äldres bostäder och boendemiljöer.Antologin är avsedd att utgöra ett underlag för kurser om äldres boende ur ett samhällsvetenskapligt perspektiv. Den vänder sig också till aktörer i kommunal produktion av bostäder och omsorg samt andra med intresse för äldres bostadsfrågor.
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| 5. |
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| 6. |
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| 7. |
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Aided Communication in Everyday Interaction
- 2013
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- This book argues for the importance of the participants' perspective within both theory and practice on the function of augmentative and alternative communication (AAC) aids in everyday talk-in-interaction. Interactional approaches such as Conversation Analysis (CA) and Topical episode analysis are used to analyze and demonstrate the way participants make sense and display their understanding of AAC-mediated action. The book documents various practices and methods of the everyday use of AAC which can be applied clinically when establishing evidence-based assessment and intervention procedures. The book aims to bridge the gap between research and clinical practice, analyzes and explains the use of AAC aids, uses video recordings and transcriptions of naturally occurring, everyday talk-in-interacton, and demonstrates how the communicative context of the user's home is a powerful environment for learning and developing AAC use.
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| 8. |
- Alm, Albert, et al.
(författare)
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Uveoscleral outflow - A review
- 2009
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Ingår i: EXPERIMENTAL EYE RESEARCH. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 88:4, s. 760-768
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Forskningsöversikt (övrigt vetenskapligt/konstnärligt)abstract
- The uveoscleral outflow route was described more than 40 years ago. Part of aqueous leaves the eye through the iris root. The ciliary muscle, and there are large species differences in the fraction of aqueous outflow that leaves the eye through this route. In non-human primates 40-50% of aqueous leaves the eye by the uveoscleral route. In human eyes most data has been collected by indirect calculations, with results suggesting a similar fraction, at least in eyes from younger individuals. An age-dependent reduction in uveoscleral flow in human eyes may explain the initial difference seen between non-human primate and human eyes. Unlike trabecular outflow, intraocular pressures within the normal range have little effect on uveoscleral outflow. This may be explained by the fact that changes in intraocular pressure have little effect on the pressure gradient for flow through the ciliary muscle, which is likely to be the rate-limiting step in uveoscleral outflow. The state of the ciliary muscle is important and contraction reduces while relaxation increases uveoscleral flow. Similar effects are achieved with cholinergic agonists and antagonists. Epinephrine increases uveoscleral flow, most likely through stimulating beta(2)-adrenergic receptors. Prostaglandin F-2 alpha and prostaglandin F-2 alpha-analogues effectively reduce intraocular pressure by increasing uveoscleral flow. This is mediated by structural changes in the extracellular matrix of the ciliary muscle, and is likely to contribute to a valuable excess route for aqueous and proteins during intraocular inflammation. Whether uveoscleral flow plays a significant role in any other eye disease is not clear. Thus, 40 years later we are able to successfully increase aqueous flow through the uveoscleral route, a valuable contribution to glaucoma treatment, but we still have only a limited understanding on its physiological role.
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| 9. |
- Amandusson, Åsa, 1974-
(författare)
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Estrogen receptor expression in relation to pain modulation and transmission : experimental studies in rats
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Estrogens have a remarkably wide range of actions in the mammalian brain. They not only play a pivotal role in reproductive behavior and sexual differentiation, but also contribute to e.g. thermoregulation, feeding, memory, neuronal survival and the perception of somatosensory stimuli. A multitude of studies on both animals and human subjects has demonstrated potential effects of gonadal hormones, such as estrogens, on pain transmission. These effects most likely involve multiple neuroanatomical circuits as well as diverse neurochemical systems and therefore need to be evaluated specifically in relation to the localization and intrinsic characteristics of the neurons engaged. The overall aim of this thesis is to gain specific knowledge of the possible cellular mechanisms by which estrogens may influence the transmission of nociceptive stimuli at the level of the spinal cord. The estrogen receptors, by which estrogens regulate non-genomic as well as genomic mechanisms, are crucial to estrogen signaling in general and essential to the estrogen-induced effects in the brain. In Paper I, we use immunohistochemistry to label neurons containing estrogen receptor-! (ERα) in the medullary and spinal dorsal horn of female rats. Large numbers of ER!-expressing neurons were found in lamina I and lamina II, i.e. in the areas involved in the processing of primary afferent nociceptive information. This distribution in part overlaps that of enkephalin, a potent pain-inhibiting endogenous opioid. The effects of gonadal hormones on pain modulation may, to a great extent, be blocked by the opioid antagonist naloxone, suggesting an involvement of the endogenous opioid system in the prosecution of hormonal pain regulation. By combining immunohistochemical labeling of ERα with in situ hybridization of preproenkephalin mRNA (Paper II), we demonstrate that the majority of enkephalinergic neurons in the superficial laminae of the spinal and medullary dorsal horn express ER!. This co-localization and the fact that the preproenkephalin gene contains a sequence that binds ERs, suggest that estrogens may potentially regulate enkephalin expression in these cells. This is further supported by the findings in Paper III in which we show that a single subcutaneous injection of estradiol induces a significant increase (on average 68%) in preproenkephalin mRNA content in the spinal cord after 4 hours. The expression of the enkephalin gene in the spinal cord is thus sensitive to fluctuating estradiol levels. In Paper IV, a noxious injection of formalin is used to induce activation of a neuronal population involved in nociceptive transmission from the face. By using a dual-labeling immunohistochemistry protocol, we were able to identify ER!-expressing cells within this neuronal population suggesting that nociceptive-responsive neurons in the medullary dorsal horn express ER!. In all, our findings provide morphological as well as biochemical evidence in support for an estrogen-dependent modulation of nociceptive processing at the level of the dorsal horn.
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| 10. |
- Amouzgar, Kaveh, 1980-, et al.
(författare)
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Multi-objective optimization of a disc brake system by using SPEA2 and RBFN
- 2013
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Ingår i: ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. - New York : ASME Press. - 9780791855898
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Many engineering design optimization problems involve multiple conflicting objectives, which today often are obtained by computational expensive finite element simulations. Evolutionary multi-objective optimization (EMO) methods based on surrogate modeling is one approach of solving this class of problems. In this paper, multi-objective optimization of a disc brake system to a heavy truck by using EMO and radial basis function networks (RBFN) is presented. Three conflicting objectives are considered. These are: 1) minimizing the maximum temperature of the disc brake, 2) maximizing the brake energy of the system and 3) minimizing the mass of the back plate of the brake pad. An iterative Latin hypercube sampling method is used to construct the design of experiments (DoE) for the design variables. Next, thermo-mechanical finite element analysis of the disc brake, including frictional heating between the pad and the disc, is performed in order to determine the values of the first two objectives for the DoE. Surrogate models for the maximum temperature and the brake energy are created using RBFN with polynomial biases. Different radial basis functions are compared using statistical errors and cross validation errors (PRESS) to evaluate the accuracy of the surrogate models and to select the most accurate radial basis function. The multi-objective optimization problem is then solved by employing EMO using the strength Pareto evolutionary algorithm (SPEA2). Finally, the Pareto fronts generated by the proposed methodology are presented and discussed.
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