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| 2. |
- Thörnblad, Karin, 1971, et al.
(författare)
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Scheduling optimization of a real flexible job shop including side constraints regarding maintenance, fixtures, and night shifts
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We present a generic iterative scheduling procedure for the scheduling of a real flexible job shop, the so-called multitask cell at GKN Aerospace Engine Systems in Sweden. A time-indexed formulation of the problem is presented including side constraints regarding preventive maintenance, fixture availability, and unmanned night shifts. This paper continues the work in [35], with an improvement of the iterative solution procedure and the inclusion of constraints regarding night shifts during which only unmanned processing is allowed. The resulting schedules are compared with schedules constructed using two priority dispatching rules. Computational results show that the gain of including the night shifts constraints is significant and that the methodology developed is able to produce near-optimal schedules for industrial data instances for the coming shift within an acceptable practical time frame.
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| 3. |
- Cheraghchi, M., et al.
(författare)
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Approximating linear threshold predicates
- 2012
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Ingår i: ACM Transactions on Computation Theory. - : Association for Computing Machinery (ACM). - 1942-3454 .- 1942-3462. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- We study constraint satisfaction problems on the domain {-1, 1}, where the given constraints are homogeneous linear threshold predicates, that is, predicates of the form sgn(w 1 x 1 + · · · + w n x n ) for some positive integer weights w 1 , . . . , w n . Despite their simplicity, current techniques fall short of providing a classification of these predicates in terms of approximability. In fact, it is not easy to guess whether there exists a homogeneous linear threshold predicate that is approximation resistant or not. The focus of this article is to identify and study the approximation curve of a class of threshold predicates that allow for nontrivial approximation. Arguably the simplest such predicate is the majority predicate sgn(x 1 + · · · + x n ), for which we obtain an almost complete understanding of the asymptotic approximation curve, assuming the Unique Games Conjecture. Our techniques extend to a more general class of "majority-like" predicates and we obtain parallel results for them. In order to classify these predicates, we introduce the notion of Chow-robustness that might be of independent interest.
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| 4. |
- Nyström, Ulrika, 1981
(författare)
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Modelling of Concrete Structures Subjected to Blast and Fragment Loading
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Betong är tack vare sin låga kostnad och sitt stora användningsområde ett av de mest använda byggmaterialen i modern tid. Dess stora energiabsorberande förmåga vid höga tryck, samt det sega beteende betongkonstruktioner har vid väl utformad armering, gör betongen också lämplig i skyddande konstruktioner. Responsen hos konstruktioner utsatta för extrem dynamisk belastning, så som stötvågs- och splitterbelastning, är dock förknippad med hög komplexitet och trots många år av forskning världen över är de fenomen som uppstår ännu inte helt klarlagda.Med målsättningen att öka kunskapen om betongkonstruktioners respons vid stötvågs- och splitterbelastning har litteraturstudier, teoretiska analyser och numeriska simuleringar använts på ett iterativt sätt. Den teoretiska grunden för betongmaterialets beteende, karaktärisering av stötvågs- och splitterlaster, lasternas verkan på betongkonstruktioner och dynamiska aspekter på vågpropagering behandlas i sammanläggningsdelen i denna avhandling. Därtill presenteras två numeriska studier. Den första numeriska studien var en jämförande studie av vilken relativ inverkan som tillsättning av stålfibrer i betong har på dess motståndsförmåga mot projektilinträngning. Det kunde konstateras att inträngningsdjupet var relativt opåverkat av fibertillsättningen medan kraterstorleken, på både fram och baksidan av den beskjutna kroppen, minskade. I den andra studien undersöktes responsen hos en armerad betongväggsstrimla vid kombinerad belastning av stötvåg och splitter. Det kunde konstateras att den totala skadan i väggelementet var starkt relaterat till skadan orsakad av enbart splitterbelastningen. Vidare framgick att väggstrimlans mittnedböjning var större för det kombinerade lastfallet än för den sammanlagda nedböjningen orsakad av stötvågs- respektive splitterbelastningarna separat. Detta tyder på en synergieffekt för de kombinerade lasterna. En tredje numerisk studie har utförts inom ramen för det presenterade arbetet. I denna studie har armeringens inverkan på betongens motståndsförmåga vid projektilbeskjutning undersökts. Slutsatsen drogs att armering kan ha viss betydelse för detta motstånd förutsatt att armeringen är lämpligt inlagd.I avhandlingen presenteras även en ny materialmodell (CDPM2) för dynamiskt belastad betong. Modellen har visat god förmåga att beskriva responsen vid ett stort antal lastfall, statiska så väl som dynamiska. I utvärdering av modellen har det visats att genom vissa modifieringar skulle modellens förmåga att beskriva responsen vid stora dynamiska laster kunna förbättras. Vissa riktlinjer för möjliga modifieringar har presenterats, men implementeringen och den vidare utvärderingen av dessa är inte en del av det presenterade arbetet.
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| 5. |
- Dupuch, Marie, et al.
(författare)
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Comparison of Clustering Approaches through Their Application to Pharmacovigilance Terms
- 2013
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Ingår i: Artificial Intelligence in Medicine. Lecture Notes in Computer Science, vol. 7885. - Berlin Heidelberg : Springer. - 9783642383250 - 9783642383267 ; , s. 58-67
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Bokkapitel (refereegranskat)abstract
- In different applications (i.e., information retrieval, filteringor analysis), it is useful to detect similar terms and to provide the possibilityto use them jointly. Clustering of terms is one of the methods whichcan be exploited for this. In our study, we propose to test three methodsdedicated to the clustering of terms (hierarchical ascendant classification,Radius and maximum), to combine them with the semantic distance algorithmsand to compare them through the results they provide whenapplied to terms from the pharmacovigilance area. The comparison indicatesthat the non disjoint clustering (Radius and maximum) outperformthe disjoint clusters by 10 to up to 20 points in all the experiments.
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| 6. |
- Freij, Ragnar, 1984, et al.
(författare)
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Partially ordered secretaries
- 2010
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Ingår i: Electronic Communications in Probability. - 1083-589X. ; 15, s. 504-507
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Tidskriftsartikel (refereegranskat)abstract
- The elements of a finite nonempty partially ordered set are exposed at independent uniform times in [0, 1] to a selector who, at any given time, can see the structure of the induced partial order on the exposed elements. The selector’s task is to choose online a maximal element. This generalizes the classical linear order secretary problem, for which it is known that the selector can succeed with probability 1=e and that this is best possible. We describe a strategy for the general problem that achieves success probability at least 1=e for an arbitrary partial order.
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| 7. |
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| 8. |
- Dmytryshyn, Andrii, 1986-, et al.
(författare)
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Miniversal deformations of matrices of bilinear forms
- 2012
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Ingår i: Linear Algebra and its Applications. - : Elsevier. - 0024-3795 .- 1873-1856. ; 436:7, s. 2670-2700
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Tidskriftsartikel (refereegranskat)abstract
- Arnold [V.I. Arnold, On matrices depending on parameters, Russian Math. Surveys 26 (2) (1971) 29–43] constructed miniversal deformations of square complex matrices under similarity; that is, a simple normal form to which not only a given square matrix A but all matrices B close to it can be reduced by similarity transformations that smoothly depend on the entries of B. We construct miniversal deformations of matrices under congruence.
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| 9. |
- Jorgensen, Palle, et al.
(författare)
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Operator algebras and representation theory : frames, wavelets and fractals
- 2011
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Ingår i: Oberwolfach Reports. - 1660-8933 .- 1660-8941. ; 8:1, s. 901-978
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Tidskriftsartikel (refereegranskat)abstract
- Operator Algebras and Representation Theory: Frames, Wavelets and Fractals Organized by: Palle E.T. Jorgensen (1), Gitta Kutyniok (2), Gestur Olafsson (3) and Sergei Silvestrov (4) (1) Department of Mathematics, University of Iowa, IA 52242-1466, IOWA CITY, UNITED STATES(2) Fachbereich Mathematik / Informatik, Universität Osnabrück, Albrechtstr. 28a, 49069, OSNABRÜCK, GERMANY(3) Department of Mathematics, Louisiana State University, LA 70803-4918, BATON ROUGE, UNITED STATES(4) Centre for Mathematical Sciences, Lund University, P.O. Box 118, 22100, LUND, SWEDEN The central focus of the workshop was Kadison-Singer conjecture and its connection to operator algebras, harmonic analysis, representation theory and the theory of fractals. The program was intrinsically interdisciplinary and represented areas with much recent progress. The workshop includes talks on operator theory, wavelets, shearlets, frames, fractals, representations theory and compressed sensing.
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| 10. |
- Lundh, Torbjörn, 1965, et al.
(författare)
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Cross- and triple-ratios of human body parts during development
- 2011
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Ingår i: Anatomical Record. - 1932-8494 .- 1932-8486. ; 294, s. 1360-1369
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Tidskriftsartikel (refereegranskat)abstract
- Recently developed landmark-based geometric morphometry has been used to depict the morphological development of organisms. In geometry,four landmarks can be mapped to any other four by Mo¨bius transformations,if the cross-ratio of the landmarks is invariant and vice versa. To geometrically analyze the morphological development of the human body,we examined the cross-ratio of three consecutive body parts that are segmented by four landmarks in their configuration. Moreover, we introduced the triple-ratio of five landmarks that segments four consecutive parts (e.g., the shoulder, upper arm, forearm, and hand) and examined their growth patterns. The cross- and triple-ratios of the upper limb andshoulder girdle in fetuses were constant when biomechanical landmarks were used, although the cross-ratio of the upper limb varied when anatomical landmarks were used. The cross-ratios of the lower limbs, trunk,and pelvic girdles in fetuses differed from their corresponding cross-ratiosin adults. These results suggest Mo¨bius growth in the fetal upper limb and shoulder girdle but not in the other body parts examined. However, the growth balance of the three contiguous body parts was represented by the developmental change in the cross-ratio. Therefore, the cross- andtriple-ratios may be applicable for simple but significant assessments of growth balance or proportion of the body parts. Anat Rec, 294:1360–1369, 2011.
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