Sähköinen tiedonkeruu MTT Sotkamon kenttäkokeissa

Mestariluokka -täydennyskoulutuksen kehitysty

Ricorrenza di processi aleatori con il Laplaciano frazionario e derivata temporale di Caputo

We are addressing a parabolic equation with fractional derivatives in time and space that governs the scaling limit of continuous-time random walks with anomalous diffusion. For these equations, the fundamental solution represents the probability density of finding a particle released at the origin at time 0 at a given position and time. Using some estimates of the asymptotic behaviour of the fundamental solution, we evaluate the probability of the process returning infinite times to the origin in a heuristic way. Our calculations suggest that the process is always recurrent.Ci occupiamo di un'equazione parabolica con derivate frazionarie in tempo e in spazio che governa il limite scalato di passeggiate aleatorie a tempo continuo con diffusione anomala. Per queste equazioni, la soluzione fondamentale rappresenta la probabilità di trovare una particella liberata all'origine al tempo 0 in una data posizione a un certo tempo. Utilizzando alcune stime sul comportamento asintotico della soluzione fondamentale, calcoliamo la probabilità del processo di ritornare infinite volte nell'origine. Il nostro metodo suggerisce che il processo sia sempre ricorrente

The significance of culinary herbs to bees

vokKirjasto Aj-

Field-scale spatial variation in yields and nitrogen fixation of clover-grass leys and in soil nutrients

Biological nitrogen fixation (BNF) plays a crucial role in organic farming and red clover (Trifolium pratense) is cultivated widely in boreal grasslands for BNF. A geostatistical method, model-based kriging, was used to determine the spatial variation in yield, clover content and BNF of clover-grass leys as well as soil chemical properties throughout two fields in 2004-2006. Based on this variation, principal component analysis (PCA) was used to determine the similar patterns of variation. On one location, total dry matter yields of the leys decreased over three production years from 9 700 to 4 100 kg ha-1, clover content from 53 to 26% and BNF from 150 to 40 kg N ha-1, whereas on the other location the yields increased from 6 500 to 7 100 kg ha-1, clover content from 52 to 62% and BNF from 100 to 120 kg N ha-1. Nutrient concentrations in soil also varied greatly within the fields, although this depended on the nutrient species. Kriging combined with PCA described the spatial variation of ley parameters very informatively, but was not as powerful for describing the pattern of nutrients. Based on the spatial dependence determined in the two fields investigated, it seems that the sampling distance should be 80 m for soil nutrients, 100 m for yield and 60 m for clover content and BNF determination, respectively