| 1. |
- Adolfsson, Vilhelm, et al.
(författare)
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Localized Galerkin Estimates for Boundary Integral Equations on Lipschitz Domanis
- 1992
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Ingår i: SIAM Journal on Mathematical Analysis. - : SIAM. ; 5:23, s. 751-764
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Tidskriftsartikel (refereegranskat)abstract
- The Galerkin method is studied for solving the boundary integral equations associated with the Laplace operator on nonsmooth domains. Convergence is established with a condition on the meshsize, which involves the local curvature on certain approximating domains. Error estimates are also proved, and the results are generalized to systems of equations.
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| 2. |
- El Gaidi, Khalid, 1949-
(författare)
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Lärarens yrkeskunnande : bildning och reflekterade erfarenheter
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Teacher’s Skills – Liberal Education and Reflected Experience is a case study of the practical skills of teachers, in which the responsible action is central. This is an action which, while informed by science, cannot be fully determined by it, since the circumstances that relate to the interaction between teacher and students cannot always be fully predicted. With Liberal Education, reflection on experience, and trained intuition, the teacher bridges the gap between scientific knowledge and the unforeseen and immediate demands of the situation. The role of Liberal Education in this ambition cannot be overestimated. To be a part of such a practice is to dedicate one’s life to a struggle with language. Therefore, insights into the theory of knowledge and the philosophy of language, as well as analogies with literature and other professional fields, help us examine the glasses through which we observe and interpret reality in order gain greater knowledge. It is in the reflective dialogue, where we meet others with whom we are not always in agreement, that we can see ourselves, our knowledge and our prejudices. The interpretation and re-interpretation of our experience in the light of the experience of others is the bridge across which we can escape from our imprisonment on the island of convenience. Once the teacher has developed a consistency in his actions, his skills can be acknowledged. When these skills are raised to the level of a style, they become an art. The main purpose of this case study is to describe the teacher’s skills; how it can be developed, and the conditions required for its assessment. A possible assumption is that reflection on our own experience and the experience of others can give us insights into ourselves, an essential prerequisite to striking the spark that motivates the investment of time and resources in the development of one’s skills as a teacher
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| 3. |
- Eriksson, Mattias, 1975-, et al.
(författare)
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A new formula for the statistical weight for a sequence of Rydberg levels in an atom or ion
- 2017
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Ingår i: Journal of Physics. - : Institute of Physics Publishing.
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Konferensbidrag (refereegranskat)abstract
- We present a new formula for the total statistical weight of all Rydberg levels Gion (nl, nh ) for which the principal quantum number n is between higher, nh , and a lower, nl , limits. This formula can be used for all atoms in the periodic table and for all corresponding ions.
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| 4. |
- Fredriksson, Henrik, et al.
(författare)
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Modeling of road traffic flows in the neighboring regions
- 2021
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Ingår i: Procedia Computer Science. - : Elsevier. ; 198, s. 43-50
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Konferensbidrag (refereegranskat)abstract
- Traffic flows play a very important role in transportation engineering. In particular, link flows are a source of information about the traffic state, which is usually available from the authorities that manage road networks. Link flows are commonly used in both short-term and long-term planning models for operation and maintenance, and to forecast the future needs of transportation infrastructure. In this paper, we propose a model to study how traffic flow in one location can be expected to reflect the traffic flow in a nearby region. The statistical basis of the model is derived from link flows to find estimates of the distribution of traffic flows in junctions. The model is evaluated in a numerical study, which uses real link flow data from a transportation network in southern Sweden. The results indicate that the model may be useful for studying how large departing flows from a node reflect the link flows in a neighboring geographic region.
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| 5. |
- Klonowska, Kamilla, et al.
(författare)
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Comparing the optimal performance of parallel architectures
- 2004
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Ingår i: Computer journal. - Oxford : Oxford University Press. - 0010-4620 .- 1460-2067. ; 47:5, s. 527-544
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Tidskriftsartikel (refereegranskat)abstract
- Consider a parallel program with n processes and a synchronization granularity z. Consider also two parallel architectures: an SMP with q processors and run-time reallocation of processes to processors, and a distributed system (or cluster) with k processors and no run-time reallocation. There is an inter-processor communication delay of t time units for the system with no run-time reallocation. In this paper we define a function H(n,k,q,t,z) such that the minimum completion time for all programs with n processes and a granularity z is at most H(n,k,q,t,z) times longer using the system with no reallocation and k processors compared to using the system with q processors and run-time reallocation. We assume optimal allocation and scheduling of processes to processors. The function H(n,k,q,t,z)is optimal in the sense that there is at least one program, with n processes and a granularity z, such that the ratio is exactly H(n,k,q,t,z). We also validate our results using measurements on distributed and multiprocessor Sun/Solaris environments. The function H(n,k,q,t,z) provides important insights regarding the performance implications of the fundamental design decision of whether to allow run-time reallocation of processes or not. These insights can be used when doing the proper cost/benefit trade-offs when designing parallel execution platforms.
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| 6. |
- Klonowska, Kamilla, et al.
(författare)
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Extended Golomb Rulers as the New Recovery Schemes in Distributed Dependable Computing
- 2005
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Konferensbidrag (refereegranskat)abstract
- Clusters and distributed systems offer fault tolerance and high performance through load sharing. When all computers are up and running, we would like the load to be evenly distributed among the computers. When one or more computers break down the load on these computers must be redistributed to other computers in the cluster. The redistribution is determined by the recovery scheme. The recovery scheme should keep the load as evenly distributed as possible even when the most unfavorable combinations of computers break down, i.e. we want to optimize the worst-case behavior. We have previously defined recovery schemes that are optimal for some limited cases. In this paper we find a new recovery schemes that are based on so called Golomb rulers. They are optimal for a much larger number of cases than the previous results.
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| 7. |
- Klonowska, Kamilla, et al.
(författare)
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Optimal recovery schemes in fault tolerant distributed computing
- 2005
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Ingår i: Acta Informatica. - : Springer. - 0001-5903 .- 1432-0525. ; 41:6, s. 341-365
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Tidskriftsartikel (refereegranskat)abstract
- Clusters and distributed systems offer fault tolerance and high performance through load sharing. When all n computers are up and running, we would like the load to be evenly distributed among the computers. When one or more computers break down, the load on these computers must be redistributed to other computers in the system. The redistribution is determined by the recovery scheme. The recovery scheme is governed by a sequence of integers modulo n. Each sequence guarantees minimal load on the computer that has maximal load even when the most unfavorable combinations of computers go down. We calculate the best possible such recovery schemes for any number of crashed computers by an exhaustive search, where brute force testing is avoided by a mathematical reformulation of the problem and a branch-and-bound algorithm. The search nevertheless has a high complexity. Optimal sequences, and thus a corresponding optimal bound, are presented for a maximum of twenty one computers in the distributed system or cluster.
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| 8. |
- Klonowska, Kamilla, et al.
(författare)
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The maximum gain of increasing the number of preemptions in multiprocessor scheduling
- 2009
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Ingår i: ACTA INFORMATICA. - : Springer. - 0001-5903 .- 1432-0525. ; 46:4, s. 285-295
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Tidskriftsartikel (refereegranskat)abstract
- We consider the optimal makespan C(P, m, i) of an arbitrary set P of independent jobs scheduled with i preemptions on a multiprocessor with m identical processors. We compare the ratio for such makespans for i and j preemptions, respectively, where i < j. This ratio depends on P, but we are interested in the P that maximizes this ratio, i. e. we calculate a formula for the worst case ratio G(m, i, j) defined as G(m, i, j) = max C(P, m, i)/C(P, m, j), where the maximum is taken over all sets P of independent jobs.
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| 9. |
- Klonowska, Kamilla, et al.
(författare)
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Using Golomb Rulers for Optimal Recovery Schemes in Fault Tolerant Distributed Computing
- 2003
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Ingår i: Proceedings International Parallel and Distributed Processing Symposium. - : IEEE. - 0769519261
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Konferensbidrag (refereegranskat)abstract
- Clusters and distributed systems offer fault tolerance and high performance through load sharing. When all computers are up and running, we would like the load to be evenly distributed among the computers. When one or more computers break down the load on these computers must be redistributed to other computers in the cluster. The redistribution is determined by the recovery scheme. The recovery scheme should keep the load as evenly distributed as possible even when the most unfavorable combinations of computers break down, i.e. we want to optimize the worst-case behavior. In this paper we define recovery schemes, which are optimal for a number of important cases. We also show that the problem of finding optimal recovery schemes corresponds to the mathematical problem called Golomb rulers. These provide optimal recovery schemes for up to 373 computers in the cluster.
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| 10. |
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