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| 2. |
- Gustafsson, Susanne, et al.
(författare)
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Vägtrafikens hastigheter : kunskapsinventering
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I syfte att uppnå etappmålet för vägtrafiksäkerheten finns delmålen att hastighetsefterlevnad skall öka på såväl det statliga som det kommunala vägnätet. VTI har därför fått i uppdrag av Trafikverket att analysera viktiga problemområden och utmaningar inom hastighetsområdet samt att identifiera viktiga insatsområden.Vi har vid genomgången av den kunskap som finns om hastighet och hastighetsefterlevnad samt ny kunskap som vi fått via diskussioner i fokusgrupper funnit att olika typer av incitament krävs för att privatbilister och yrkesförare ska hålla hastigheten.Såväl utbildning som information är viktiga för att motivera föraren att agera på rätt sätt och skapa en norm i samhället som tar avstånd ifrån hastighetsöverträdelser. Det behövs dock att detta sker i kombination med övervakning och tekniska åtgärder.
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| 3. |
- Johannesson, Tomas, 1975-
(creator_code:sds_t, creator_code:cre_t)
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Time Flies : Mikael Isaksson
- 2022
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Konstnärligt arbete (ljud/tal) (refereegranskat)abstract
- CD med Mikael IsakssonTitel: Time FliesFörlag: Imogena RecordsLåtlistaCoffee TimeFinlandConfusedNo WayEternityTime FliesMusikerMikel Isaksson, GitarrJoakim "Jocke" Ekberg, TrummorHans Backentoth, BasLennart Simonsson, PianoInspelad av Erik HäuslerMixad av Tomas JohannessonMastrad av Stockholm Mastering
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| 6. |
- Simonsson, Louise, 1972-
(författare)
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Environmental Assessments of Landscape Changes : Interdisciplinary studies in rural Tanzania
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis aims to show how biogeophysical and social processes are interlinked in landscape change, and to propose approaches for interdisciplinary environmental assessments (such as EIAs), concentrating on developing countries’ situations, and representation of findings from such studies. Landscape in its holistic sense is a very good concept and basis for intellectual and practical use in environmental dialogues. However, landscapes are valued and assessed differently, depending on cultural background along with individual characteristics. Methods of conducting interdisciplinary environmental assessments need to vary, but it is important to follow a structure to avoid too broad and general studies that only assemble a few factors and present them without an integrated synthesis. This thesis has suggested one research sequence and structure that has proven to be practical and possible to execute in areas where data is scarce and where local involvement is a major component. It extends the observation period in time and space where remote sensing analyses are integrated with interviews, archive material, land-cover assessments and soil analyses.Case studies from Tanzania have been used to investigate how perceptions of land and resources manifest themselves at local scales and how this information can contribute to sustainable environmental planning. Preferences and perceptions of land as being ‘important’ and ‘good’ do not always correlate with favourable biogeophysical conditions, indicating that both social services, such as health care, access to markets, education and employment, as well as “non-rational” factors are essential to consider in environmental planning and management.This study has partly been part of a larger research project investigating the links between human livelihood and biodiversity in miombo woodlands. It has been shown how miombo woodland is important to local populations as it provides material goods as well as many intangible services. However, it is also associated with problems and dangers, which are important to consider and understand in planning for the environment and sustainable development.
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| 7. |
- Simonsson, Lennart, et al.
(författare)
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Grassmann algorithms for low rank approximation of matrices with missing values
- 2010
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Ingår i: BIT NUMERICAL MATHEMATICS. - : Springer Science and Business Media LLC. - 0006-3835 .- 1572-9125. ; 50:1, s. 173-191
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Tidskriftsartikel (refereegranskat)abstract
- The problem of approximating a matrix by another matrix of lower rank, when a modest portion of its elements are missing, is considered. The solution is obtained using Newtons algorithm to find a zero of a vector field on a product manifold. As a preliminary the algorithm is formulated for the well-known case with no missing elements where also a rederivation of the correction equation in a block Jacobi-Davidson method is included. Numerical examples show that the Newton algorithm grows more efficient than an alternating least squares procedure as the amount of missing values increases.
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| 9. |
- Simonsson, Lennart, 1972-
(författare)
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Subspace Computations via Matrix Decompositions and Geometric Optimization
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is concerned with the computation of certain subspaces connected to a given matrix, where the closely related problem of approximating the matrix with one of lower rank is given special attention. To determine the rank and obtain bases for fundamental subspaces such as the range and null space of a matrix, computing the singular value decomposition (SVD) is the standard method. When new data are added, like in adaptive signal processing, a more economic alternative to the SVD is to use a rank-revealing UTV (ULV or URV) decomposition since it can be updated more easily. The scenario in part I of the thesis is that the matrix to be updated is either a product or a quotient of two other matrices. There exist implicit algorithms for computing the SVD of a product or quotient that operate on the two matrices separately. For the corresponding problem of an URV decomposition of a product or quotient, originally sketched by S. Qiao, we give the details of the updating algorithms. Sample numerical experiments confirm that the quality of the approximate subspaces compared to the ones obtained by the implicitly computed URV, is degraded if the product is formed explicitly in some cases. We argue that the same pros and cons that affect the choice between the URV and ULV decomposition of one matrix, carry over to the choice between the implicit URV decomposition and the more established ULLV decomposition in the quotient case. As a signal processing application, we track the range of an estimated cross-covariance matrix. We also describe the updating issues of a decomposition that reveals the ranks of the individual matrices in a product. That decomposition suffers from a difficult decision about the rank of the product and will not be tested as a competitor to the implicit URV decomposition referred to above. A common situation in scientific computing is that the matrix is too lagre to admit a full factorization within reasonable time. In that case iterative methods must be employed, where Lanczos type algorithms are the most widely used. In part II we discuss the formulation of standard numerical optimization methods on the Grassmann manifold whose objects are subspaces and focus on the application to numerical linear algebra problems. This approach allow us to (re-)derive algorithms for the partial symmetric eigenvalue problem and the inexact Newton method is given special attention. A recent method is the Jacobi-Davidson (JD) algorithm that can be seen both as a variation of an inexact Newton method for solving a set of nonlinear equations/minimizing a function and as an expanding subspace algorithm that is equivalent to Lanczos if the equation in each step is solved exactly. Our contribution is an algorithm that is fairly robust with a subspace that is only twice as large as the desired one. A large part treats the implementation issues associated with the solution of a correction equation including stopping rules and the use of preconditioners. Other numerical linear algebra problems call for a pair of subspaces. We give Grassmann type algorithms for the partial SVD problem and low rank approximation of matrices with missing entries, but will restrain ourselves by demonstrating their efficiency for exact solution of the Newton equation.
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