| 1. |
- Gustavsson, Andreas, 1982-
(författare)
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Static Execution Time Analysis of Parallel Systems
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The past trend of increasing processor throughput by increasing the clock frequency and the instruction level parallelism is no longer feasible due to extensive power consumption and heat dissipation. Therefore, the current trend in computer hardware design is to expose explicit parallelism to the software level. This is most often done using multiple, relatively slow and simple, processing cores situated on a single processor chip. The cores usually share some resources on the chip, such as some level of cache memory (which means that they also share the interconnect, e.g., a bus, to that memory and also all higher levels of memory). To fully exploit this type of parallel processor chip, programs running on it will have to be concurrent. Since multi-core processors are the new standard, even embedded real-time systems will (and some already do) incorporate this kind of processor and concurrent code.A real-time system is any system whose correctness is dependent both on its functional and temporal behavior. For some real-time systems, a failure to meet the temporal requirements can have catastrophic consequences. Therefore, it is crucial that methods to derive safe estimations on the timing properties of parallel computer systems are developed, if at all possible.This thesis presents a method to derive safe (lower and upper) bounds on the execution time of a given parallel system, thus showing that such methods must exist. The interface to the method is a small concurrent programming language, based on communicating and synchronizing threads, that is formally (syntactically and semantically) defined in the thesis. The method is based on abstract execution, which is itself based on abstract interpretation techniques that have been commonly used within the field of timing analysis of single-core computer systems, to derive safe timing bounds in an efficient (although, over-approximative) way. The thesis also proves the soundness of the presented method (i.e., that the estimated timing bounds are indeed safe) and evaluates a prototype implementation of it.
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| 2. |
- Gustavsson, Andreas, 1982-
(författare)
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Static Timing Analysis of Parallel Systems Using Abstract Execution
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Power Wall has stopped the past trend of increasing processor throughput by increasing the clock frequency and the instruction level parallelism.Therefore, the current trend in computer hardware design is to expose explicit parallelism to the software level.This is most often done using multiple processing cores situated on a single processor chip.The cores usually share some resources on the chip, such as some level of cache memory (which means that they also share the interconnect, e.g. a bus, to that memory and also all higher levels of memory), and to fully exploit this type of parallel processor chip, programs running on it will have to be concurrent.Since multi-core processors are the new standard, even embedded real-time systems will (and some already do) incorporate this kind of processor and concurrent code.A real-time system is any system whose correctness is dependent both on its functional and temporal output. For some real-time systems, a failure to meet the temporal requirements can have catastrophic consequences. Therefore, it is of utmost importance that methods to analyze and derive safe estimations on the timing properties of parallel computer systems are developed.This thesis presents an analysis that derives safe (lower and upper) bounds on the execution time of a given parallel system.The interface to the analysis is a small concurrent programming language, based on communicating and synchronizing threads, that is formally (syntactically and semantically) defined in the thesis.The analysis is based on abstract execution, which is itself based on abstract interpretation techniques that have been commonly used within the field of timing analysis of single-core computer systems, to derive safe timing bounds in an efficient (although, over-approximative) way.Basically, abstract execution simulates the execution of several real executions of the analyzed program in one go.The thesis also proves the soundness of the presented analysis (i.e. that the estimated timing bounds are indeed safe) and includes some examples, each showing different features or characteristics of the analysis.
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| 3. |
- Gustavsson, Andreas, et al.
(författare)
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Towards WCET Analysis of Multicore Architectures using UPPAAL
- 2010
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Ingår i: OpenAccess Series in Informatics, vol. 15, 2010. - 9783939897217 ; , s. 101-112
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Konferensbidrag (refereegranskat)abstract
- To take full advantage of the increasingly used shared-memory multicore architectures, software algorithms will need to be parallelized over multiple threads. This means that threads will have to share resources (e.g. some level of cache) and communicate and synchronize with each other. There already exist software libraries (e.g. OpenMP) used to explicitly parallelize available sequential C/C++ and Fortran code, which means that parallel code could be easily obtained. To be able to use parallel software running on multicore architectures in embedded systems with hard real-time constraints, new WCET (Worst-Case Execution Time) analysis methods and tools must be developed. This paper investigates a method based on model-checking a system of timed automata using the UPPAAL tool box. It is found that it is possible to perform WCET analysis on (not too large and complex) parallel systems using UPPAAL. We also show how to model thread synchronization using spinlock-like primitives.
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| 4. |
- Hellsmark, Hans, 1974, et al.
(författare)
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Teknologiska innovationssystem inom energiområdet: En praktisk vägledning till identifiering av systemsvagheter som motiverar särskilda politiska åtaganden
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med denna rapport är att illustrera hur ett praktiskt inriktat ramverk, tekno- logiska innovationssystem (TIS), kan användas av analytiker och beslutsfattare vid departement och myndigheter för att analysera strategiskt viktiga teknikområden ?????????????????????????????????????????????????????????????????????????????I rapporten analyseras fem TIS centrerade kring havsbaserad vindkraft, marin energi, ????????????????????????????????????????????????????????????????????????????????????? systemsvagheter som bromsar områdets vidare utveckling, vilka som kan åtgärdas av systemets aktörer och vilka som motiverar särskilda politiska åtaganden. Rapporten utgör därmed ett underlag för att formulera åtgärder för att åstadkomma ökad innova- tion, teknikspridning och industrialisering inom ovan nämnda teknikområden.Studien har även möjliggjort en jämförande analys av likheter och skillnader ???????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????? mellan områdena – de är starka respektive svaga av olika orsaker. Detta visar att ???????????????????????????????????????????????????????????????????????Samtidigt har områdena gemensamma drag. Systemets aktörer, där även politiska ???????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????- skapsnätverk. Men de har varit sämre på att skapa tidiga nischmarknader som ger utrymme för fortsatt lärande och kostnadsreduktion. Sådana nischer kan ibland skapas av marknadens aktörer, men ofta krävs politiska styrmedel. De behövs för att investeringar i kunskapsutveckling ska kunna nyttiggöras och för att en bred industriell utveckling inom nya områden skall göras möjlig i Sverige.Vidare presenteras lärdomar kring vad en aktiv teknikpolitik innebär. Två huvud- ??????????????????????????????????????????????????????????????????????????????- hällsbygget och därför bör vara ett politikområde bland många samt att den skarpa ??????????????????????????????????????????????????????????????????????????????- ?????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????? olika faser av innovationssystemets utveckling.För att lyckas med en aktiv teknikpolitik behövs en hög grad av koordinering ??????????????????????????????????????????????????????????????????????? teknikområden så att ”rätt” typ av åtgärder kan sättas in vid ”rätt” tidpunkt av ”rätt” aktör. TIS-ramverket lyfts här fram som en metod för att skapa ett sådant underlag. Slutligen presenteras en metod för projektbedömningar som syftar till att stötta handläggare i utvärderingar av projekt inom nya teknikområden.Rapporten i sin helhet riktar sig särskilt till beslutsfattare och handläggare vid myndigheter, departement och politiker, men även andra organisationer och indi- vider med intresse av att högt ställda klimatmål ska kunna nås samtidigt som en positiv näringslivsutveckling möjliggörs.
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| 5. |
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| 6. |
- Agemark, Maria, et al.
(författare)
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Reconstitution of water channel function and 2D-crystallization of human aquaporin 8.
- 2012
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Ingår i: Biochimica et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 0005-2736. ; 1818:3, s. 839-850
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Tidskriftsartikel (refereegranskat)abstract
- Among the thirteen human aquaporins (AQP0-12), the primary structure of AQP8 is unique. By sequence alignment it is evident that mammalian AQP8s form a separate subfamily distinct from the other mammalian aquaporins. The constriction region of the pore determining the solute specificity deviates in AQP8 making it permeable to both ammonia and H(2)O(2) in addition to water. To better understand the selectivity and gating mechanism of aquaporins, high-resolution structures are necessary. So far, the structure of one human aquaporin (HsAQP5) has been solved at atomic resolution. For mammalian aquaporins in general, high-resolution structures are only available for those belonging to the water-specific subfamily (including HsAQP5). Thus, it is of interest to solve structures of other aquaporin subfamily members with different solute specificities. To achieve this the aquaporins need to be overexpressed heterologously and purified. Here we use the methylotrophic yeast Pichia pastoris as a host for the overexpression. A wide screen of different detergents and detergent-lipid combinations resulted in the solubilization of functional human AQP8 protein and in well-ordered 2D crystals. It also became evident that removal of amino acids constituting affinity tags was crucial to achieve highly ordered 2D crystals diffracting to 3Å.
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| 7. |
- Ahlberg, Carl, et al.
(författare)
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The Black Pearl: An Autonomous Underwater Vehicle
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Black Pearl is a custom made autonomous underwater vehicle developed at Mälardalen University, Sweden. It is built in a modular fashion, including its mechanics, electronics and software. After a successful participation at the RoboSub competition in 2012 and winning the prize for best craftsmanship, this year we made minor improvements to the hardware, while the focus of the robot's evolution shifted to the software part. In this paper we give an overview of how the Black Pearl is built, both from the hardware and software point of view.
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| 8. |
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| 9. |
- Al-Adili, Ali, et al.
(författare)
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Analysis of prompt fission neutrons in U-235(nth,f) and fission fragment distributions for the thermal neutron induced fission of U-234
- 2016
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Ingår i: CNR*15 - 5th International Workshop On Compound-Nuclear Reactions And Related Topics. - : EDP Sciences.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the ongoing analysis of two fission experiments. Both projects are part of the collaboration between the nuclear reactions group at Uppsala and the JRC-IRMM. The first experiment deals with the prompt fission neutron multiplicity in the thermal neutron induced fission of U-235(n,f). The second, on the fission fragment properties in the thermal fission of U-234(n,f). The prompt fission neutron multiplicity has been measured at the JRC-IRMM using two liquid scintillators in coincidence with an ionization chamber. The first experimental campaign focused on U-235(nth,f) whereas a second experimental campaign is foreseen later for the same reaction at 5.5 MeV. The goal is to investigate how the so-called saw-tooth shape changes as a function of fragment mass and excitation energy. Some harsh experimental conditions were experienced due to the large radiation background. The solution to this will be discussed along with preliminary results. In addition, the analysis of thermal neutron induced fission of U-234(n,f) will be discussed. Currently analysis of data is ongoing, originally taken at the ILL reactor. The experiment is of particular interest since no measurement exist of the mass and energy distributions for this system at thermal energies. One main problem encountered during analysis was the huge background of U-235(nth, f). Despite the negligible isotopic traces in the sample, the cross section difference is enormous. Solution to this parasitic background will be highlighted.
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| 10. |
- Al-Adili, Ali, et al.
(författare)
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Fission Activities of the Nuclear Reactions Group in Uppsala
- 2015
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Ingår i: Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays, THEORY-3. - : Elsevier BV. ; , s. 145-149
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Konferensbidrag (refereegranskat)abstract
- This paper highlights some of the main activities related to fission of the nuclear reactions group at Uppsala University. The group is involved for instance in fission yield experiments at the IGISOL facility, cross-section measurements at the NFS facility, as well as fission dynamics studies at the IRMM JRC-EC. Moreover, work is ongoing on the Total Monte Carlo (TMC) methodology and on including the GEF fission code into the TALYS nuclear reaction code. Selected results from these projects are discussed.
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