23 research outputs found
FelszĂni Ă©s felszĂn alatti áramlások számĂtásának Ăşj eszköze: a hálĂłnĂ©lkĂĽli vĂ©ges elem mĂłdszer = A new tool for the computation of surface and subsurface flows: the meshless finite element method
A kutatásban a tĂ©mavezetĹ‘ által korábban kidolgozott multi-elliptikus interpoláciĂłs mĂłdszeren alapulĂł hálĂłnĂ©lkĂĽli mĂłdszereket konstruáltunk elliptikus parciális differenciálegyenletek megoldására. Ezek jellegzetessĂ©ge, hogy a megoldási tartományt nem kell sem ráccsal vagy vĂ©geselemes hálĂłval diszkretizálni, ehelyett elĂ©g azokon egy struktĂşra nĂ©lkĂĽli ponthalmazt megadni. A struktĂşranĂ©lkĂĽlisĂ©g ellenĂ©re lehetsĂ©ges jĂłl közelĂtĹ‘ mĂłdszereket definiálni, melyek mĂ©g többszintű, gyors megoldási technikákkal is kombinálhatĂłk. A partikuláris megoldások elvĂ©t alkalmazva, az eredeti problĂ©ma visszavezethetĹ‘ homogĂ©n problĂ©ma megoldására. Ehhez elegendĹ‘ volt egy speciális perem tĂpusĂş interpoláciĂłt konstruálni, mely numerikusan kevĂ©s műveletigĂ©nyű Ă©s ugyanakkor stabil mĂłdszer. A technikát általánosĂtottuk nemkonstans egyĂĽtthatĂłs elliptikus problĂ©mákra is, Ă©s ez a megközelĂtĂ©s lett az alapja a peremrekonstrukciĂł mĂłdszerĂ©nek Ă©s a regularizált alapmegoldás-mĂłdszernek is. MĂ©g általánosabban alkalmazhatĂłnak bizonyultak a radiális bázisfĂĽggvĂ©nyeken alapulĂł lokális hálĂłnĂ©lkĂĽli sĂ©mák, Ă©s kĂĽlönösen a multi-elliptikus interpoláciĂłra alapozott Ăşjraglobalizált sĂ©mák, melyeket az utĂłbbi Ă©vben fejlesztettĂĽnk ki. Ezeket sikerrel alkalmaztuk a Stokes-problĂ©ma megoldására is. A tĂ©mavezetĹ‘ nagyrĂ©szben ezekre a kutatási eredmĂ©nyekre alapozva 2007 februárjában MTA-doktori Ă©rtekezĂ©st adott be, melyet szakmai jelentĂ©skĂ©nt fájlban csatoltunk. | In the present project, meshless methods based on the multi-elliptic interpolation proposed earlier by the project leader were constructed in order to solve elliptic partial differential equations. Their main feature is that there is no need to discretize the domain by either a grid or a finite element mesh. In spite of the lack of the structure, it is possible to define meshless methods with good approximation properties, moreover, they can be combined with fast, multi-level solution techniques. Applying the idea of the particular solutions, the problem can be converted to the solution of a homogeneous problem. To this end, it is sufficient to construct a special boundary interpolation, which requires low computational cost and remains numerically stable. The technique was generalized to elliptic problems with nonconstant coefficients, moreover, this approach became the basis of the boundary reconstruction method as well as the regularized method of fundamental solutions. The local meshless schemes based on the radial basis functions and especially the re-globalized schemes based on the multi-elliptic interpolation have proved even more generally applicable. These methods were developed in the last year and they were succesfully applied to the Stokes problem. Based mainly on these research results, the project leader submitted his Doctoral Theses to the Hungarian Academy of Sciences in February, 2007, which is attached as a research report in a separated file
A magyar futrinka (Carabus hungaricus Fabricius, 1792) elterjedése, természetvédelmi helyzete. (Nature conservation status of Carabus hungaricus in Hungary),
CikkĂĽnkben összesĂtettĂĽk majd tĂ©rinformatikai mĂłdszerekkel feldolgoztuk a magyar futrinka (Carabus hungaricus Fabricius, 1792) általunk fellelhetĹ‘ adatait. IntenzĂv Ă©lvefogĂł csapdázást vĂ©geztĂĽnk 47 magyarországi helyszĂnen. Ezek közĂĽl összesen 42 helyen Ă©szleltĂĽk a magyar futrinka jelenlĂ©tĂ©t, ebbĹ‘l 17 elĹ‘fordulás Ăşjnak számĂt. MegállapĂtottuk, hogy hazánkban a magyar futrinka potenciálisan veszĂ©lyeztetett. A faj megĹ‘rzĂ©se Ă©rdekĂ©ben további Natura 2000 hálĂłzatba tartozĂł terĂĽleteket volna cĂ©lszerű kijelölni. A magyar futrinka legerĹ‘sebb populáciĂłi homokpusztagyepekhez kötĹ‘dnek, a sziklagyepi populáciĂłk jĂłval kisebb egyedszámĂşak Ă©s sĂ©rĂĽlĂ©kenyek. Tapasztalataink szerint a faj erĹ‘s, nagy egyedszámĂş populáciĂłibĂłl kĂ©pesek pĂ©ldányok elvándorolni, Ă©s kedvezĹ‘ körĂĽlmĂ©nyek esetĂ©n ott megtelepedni
NUMERICAL MODELLING OF FLOW PATTERNS TO ASSIST THE REVITALISATION OF SECONDARY RIVER BRANCHES IN GEIVIENC AREA
Depth-averaged numerical modelling of steady-state horizontal flow patterns carried out in
the framework of the revitalisation project of the secondary branches in Gemenc Protected
Landscape Area is presented. The feasibility of different variants is investigated in order
to increase the water exchange in the secondary branches without creating unfavorable
hydraulic and related sediment transport as well as navigation conditions. The applied
mathematical model is based on the usual shallow water assumptions. The numerical
solution is performed using finite differences and multigrid iteration technique. The model
is able to reproduce recirculation zones and the horizontal velocity distribution in an
acceptable manner
The distribution, habitat, and the nature conservation value of a Natura 2000 beetle, Carabus hungaricus Fabricius, 1792 in Hungary.
Carabus hungaricus Fabricius, 1792 usually inhabits sandy grasslands and dolomitic grass-lands in Hungary. It is listed in the Habitat Directive and it is a characteristic species of the Pannonian biogeographic region. This paper summarizes all available data (literature data, personal communications, all available museum specimens, original research) on the current distribution of Carabus hungaricus in Hungary making use of GIS. The most numerous populations of this carabid beetle live in Pannonic sand steppe biotopes, the most vulnerable of the dolomitic grasslands. In Hungary, Carabus hungaricus is a vulnerable species according to the IUCN criteria. Known habitat types, habitat preferences, cooccurring ground beetle species, and endangering environmental factors are discussed