545 research outputs found
Picard - an electrostatic particle in cell simulation code
No full textThis is a particle-in-cell plasma code 'picard' that was developed
by Jesper Lindkvist and Herbert Gunell with start in 2016 using
resources provided by the Swedish National Infrastructure for
Computing (SNIC) at the High Performance Computing Center North
(HPC2N), Umeå University, Sweden. Jesper Lindkvist was funded by
the Swedish National Space Board (SNSB project 201/15) and
Herbert Gunell by the Swedish National Space Agency (SNSA
project 108/18).
A paper based on the first version was published in A&A .
The present version has been updated to include ionisation as a source of cometary ions, and hdf5 files are used for writing the output. The changes in this version were made by Herbert Gunell.
The files included are:
picard.tgz Package containing all source file, some matlab m-files
that can be used for plotting of the results, and an input
file that was used for a simulation that will be used in an
upcoming publication by Herbert Gunell and Charlotte Götz.
fig-cur.mp4 Videoclip showing results from the simulation defined by the input file, specifically
three-dimensional current paths from different angles.
@author : Jesper Lindkvist
Email : [email protected]
@author : Herbert Gunell
Email : [email protected]
Nye tilgange til leverandører kræver nye tilgange til markeder: Eller er det omvendt?
Full text linkDenne artikel introducerer et integreret perspektiv på leverandør og markedsudvikling. Udgangspunktet er tesen, at for at udnytte det potentiale, der kan ligge i nye former for samspil med leverandører, må der åbnes for at tænke en virksomheds marked på nye måder – og omvendt. Traditionelle tilgange til strategiarbejde ofte tage afsæt i det artiklen kalder en strategisk konstant. Et mere eller mindre bevidst valgt fikspunkt for strategiudvikling. Afsættet i en strategisk konstant gør det muligt at opstille strategiprocesser, der følger en trinvis plan, der optimerer i forhold til den strategiske konstant. Med afsæt i eksempler hentet fra et interaktivt forskningsprojekt diskuteres en udviklingsmodel, der dels søger potentialer ved at opgive den strategiske konstant og dels ved at balancere potentialer på leverancesiden med potentialer på markedssiden af virksomheden
Strategisk ledelse som organisering på distancen
Full text linkMålet med denne artikel er at tilbyde et alternativt perspektiv på strategisk ledelse. Ved at trække på aktør-netværksteori foreslås det, at det er et grundlæggende vilkår for strategisk ledelse, at de begivenheder, der skal ledes, simpelthen ikke er til stede, der hvor der ledes fra. Derfor kan strategisk ledelse tænkes som en opgave med at organisere på distancen. Organisering på distancen involverer to forflytninger. For det første skal fjerne begivenheder flyttes ind til strategen, så de kan overskues i et her-og-nu. For det andet skal de ideer om hensigtsmæssige
begivenheder, som strategen udvikler i et her-og-nu, gives en form, så de kan flyttes ud og gribe ind i udfoldende begivenheder. Dette alternative perspektiv på strategisk ledelse illustreres gennem en alternativ teoretisk tolkning af et strategiudviklingsseminar i en mindre, dansk it-virksomhed
Type Theory Unchained: Extending Agda with User-Defined Rewrite Rules
Full text linkDependently typed languages such as Coq and Agda can statically guarantee the correctness of our proofs and programs. To provide this guarantee, they restrict users to certain schemes a- such as strictly positive datatypes, complete case analysis, and well-founded induction a- that are known to be safe. However, these restrictions can be too strict, making programs and proofs harder to write than necessary. On a higher level, they also prevent us from imagining the different ways the language could be extended. In this paper I show how to extend a dependently typed language with user-defined higher-order non-linear rewrite rules. Rewrite rules are a form of equality reflection that is applied automatically by the typechecker. I have implemented rewrite rules as an extension to Agda, and I give six examples how to use them both to make proofs easier and to experiment with extensions of type theory. I also show how to make rewrite rules interact well with other features of Agda such as-equality, implicit arguments, data and record types, irrelevance, and universe level polymorphism. Thus rewrite rules break the chains on computation and put its power back into the hands of its rightful owner: Yours.Programming Language
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