111 research outputs found
Accuracy of the lattice Boltzmann method based on analytical solutions
PACS:02.70.-c, 47.35.+i, 47.40.-xIn this paper, a simple method is proposed to obtain steady analytical solutions for the lattice Boltzmann method. Based on such analytical results, it is demonstrated how the accuracy of the lattice Boltzmann method can depend on the relative orientation of the lattice and the flow field. It is also demonstrated that the method can be useful to obtain a general class of analytical solutions for the lattice Boltzmann method. Finally, a simple relation is given between the compressibility error and the velocity field.This
work was supported by the Research Training Network
STOPP in the 5th Framework program of the European
Union under Grant No. HPRN-CT-1999-00041.Peer reviewe
Connection between oxygen uptake rate and carbon dioxide evolution rate in aerobic thermophilic sludge digestion
The main aim of studying the relation of carbon dioxide evolution rate CER to oxygen uptake rate (OUR) is the possible application of CER in mathematical modelling of aerobic biodegradation processes instead of OUR. Biodegradation tests using glucose and sewage sludge as feed were performed to compare the OUR and CER.
The respiratory quotient (RQ) was 0.9 mol CO2 × mol O2-1 in endogenous stage while its value was increased to 1.2 mol CO2 × mol O2-1 during glucose degradation. At higher F/M ratios and high respiration rates RQ values up to 2.95 were observed which may indicate the appearance of anaerobic degradation pathways.
These results prove that there is no direct, simple relation between OUR and CER in case of sewage sludge degradation so direct substitution of OUR with CER in modelling studies is not feasible
A dolomitsziklagyepek degradációjának és a muflon (Ovis musimon) jelenlétének összefüggései a Budai-hegységben | The context of dolomite grassland degradation and the rate of moufflon (Ovis musimon) population in the Budai-mountains
Jelen munkában a Budai TájvĂ©delmi Körzeten belĂĽl kĂ©t terĂĽlet összehasonlĂtásával
megvizsgáltuk, milyen eltéréseket mutatnak a sziklagyepek a rájuk nehezedő vad által okozott
legelési és taposási nyomás hatására. A Szénások Európa Diplomás Terület köré a nem
Ĺ‘shonos nagyvad fajok kizárása cĂ©ljábĂłl 2005-ben kerĂtĂ©st Ă©pĂttetett a nemzeti park. Ennek
cĂ©lja az erdĹ‘ termĂ©szetes felĂşjulásának elĹ‘segĂtĂ©se Ă©s a gyepterĂĽletek termĂ©szetessĂ©gi
állapotának helyreállĂtása volt. Az EurĂłpa Diplomás TerĂĽleten belĂĽl találhatĂł Kutya-hegyen
Ă©s a vadkerĂtĂ©sen kĂvĂĽl fekvĹ‘ Meszes-hegyen vĂ©geztĂĽnk cönolĂłgiai vizsgálatokat 2008 Ă©s
2011 között, Braun-Blanquet (1964) mĂłdosĂtott mĂłdszerĂ©vel, valamint mikrocönolĂłgiai
mintákat (Juhász-Nagy 1980) is kĂ©szĂtettĂĽnk. CĂ©lunk volt, hogy igazoljuk a termĂ©szetvĂ©delmi beavatkozás fontosságát Ă©s pozitĂv hatását.
Az eredmĂ©nyeink szerint a Kutya-hegyen találhatĂł nyĂlt Ă©s zárĂłdĂł dolomit-sziklagyepek a
természetvédelmi beavatkozást követő hatodik évben a kiinduló állapotot meghaladó
diverzitás Ă©rtĂ©kkel bĂrtak. A fajok szociális magatartási formái Ă©s a termĂ©szetvĂ©delmi
Ă©rtĂ©kkategĂłriák osztályozása alapján az Ă©rtĂ©kes fajok borĂtási arányai a pionĂr fajok
dominancia értékének csökkenésével párhuzamosan emelkedtek. A hasonlósági alapon
törtĂ©nĹ‘ osztályozás alapján megállapĂthatĂł volt a 2005-ös Ă©s 2010-2011-es minták
elkülönülése, ami a többi eredmény tükrében a gyep javuló természetességi állapotába történő elmozdulás következménye.
A vadkizárás hatásainak tanulmányozásával párhuzamosan szerettük volna megvizsgálni a
nagyvadaknak, elsősorban a muflonnak (Ovis musimon) a gyepekre gyakorolt hatásait is. Az
összehasonlĂtás során a Meszes-hegyen fekvĹ‘ nyĂlt dolomit sziklagyeprĹ‘l kĂ©szĂtett minden
elemzés természetvédelmi szempontból kedvezőtlenebb eredményeket mutatott, mint a
Kutya-hegy regenerálódó élőhelye (TVK értékek, diverzitásfüggvények, mikrocönológiai
adatfeldolgozás eredményei). | In the present work we examined by comparing two area within the Budai Landscape Area,
which varies the rocky grassland show because the game pressure (grazing, trampling). A
fence was built by the national park to excluse the non-native game from the Szénások
European Diploma Area. We performed coenological examination in the Kutya-mountain
(inside the fence) and the Meszes-mountain (outside the fence) between 2008 and 2011 by the
modified method of Braun-Blanquet (1964), also mikrocoenological samples (Juhász-Nagy
1980) were made.
Our goal was to verify the importance and the positive effect of the nature conservation
intervention. The results show after the sixth year of the initial state in the Kutya-mountain
had a value in excess of diversity. By the category of social behavior of species the valuable
species coverage ratios of the pioneer species dominance in parallel with the decrease in the
value increased. The classification showed difference between the sampling years of 2005 and 2010-2011. Parallel the study of game exclsuion, I wanted to examine the effect of moufflon
(Ovis musimon)to the rocky grasslands. Below the comparsion all of the nature conservation
analysis were worse in the Meszes-mountain like the Kutya-mountain (nature conservaion
vaule, diversity, mikrocoenological results)
Filtering effect of temporal niche fluctuation and amplitude of environmental variations on the trait-related flowering patterns: lesson from sub-Mediterranean grasslands
Timing of flowering is a critical component of community assembly, but how plant traits respond to heterogeneity of resources has been identified mostly through observations of spatial variations. Thus, we performed a trait-based phenological study in sub-Mediterranean grasslands to assess the importance of temporal variation of resources in the species assemblage processes. We found that early flowering species have traits allowing for slow resource acquisition and storage but rapid growth rate. Instead, mid- and late-flowering species exhibited sets of strategies devoted to minimizing water loss by evapotranspiration or aimed at maximizing the species’ competitive ability, thanks to slow growth rate and more efficient resource acquisition, conservation and use. Our findings were consistent with the fluctuation niche theory. We observed that the amplitude of the environmental fluctuations influences the type and number of strategies positively filtered by the system. In fact, in the most productive grasslands, we observed the highest number of indicator trait states reflecting strategies devoted to the storage of resources and competition for light. Results seem also indicate that temporal variation of resources plays a role in trait differentiation and richness within a plant community, filtering traits composition of grasslands in the same direction, as formerly proved for spatial heterogeneity of resources
Cut mowing and grazing effects with grey cattle on plant species composition in case of Pannon wet grasslands
Examined area can be found at Balaton Uplands National Park (Hungary). 5 sample areas were
examined in Badacsonytördemic: 1: 32 hectare under-grazed pasture, 2: 38 hectare overgrazed pasture, 3:
34 hectare hayfield, 4: trampled area, 5: beaten track. Livestock population was 118 in the monitored
pastures. Sampling was executed along five 52m long circular transects, within 5cm Ă— 5cm interlocking
quadrates. Based on the data we can state that the curve of the drinking area was the highest of speciesarea
examinations however weed appeared because of degradation which provided more species.
According to species-area examinations overgrazed areas were richer in species then other examined
areas. Based on diversity data drinking area considered degraded, while meadow and overgrazed areas
was considered as proper state. Diversity of meadow was larger, but dominance of economically useful
species was smaller. The amount of less valuable species – Carex hirta – increased
Galilean invariance of lattice Boltzmann models
It is well-known that the original lattice Boltzmann (LB) equation deviates
from the Navier-Stokes equations due to an unphysical velocity dependent
viscosity. This unphysical dependency violates the Galilean invariance and
limits the validation domain of the LB method to near incompressible flows. As
previously shown, recovery of correct transport phenomena in kinetic equations
depends on the higher hydrodynamic moments. In this Letter, we give specific
criteria for recovery of various transport coefficients. The Galilean
invariance of a general class of LB models is demonstrated via numerical
experiments
A legeltetés hatása a gyepekre és természetvédelmi vonatkozásai a Tapolcai- és a Káli- medencében
A Tapolcai- Ă©s a Káli-medence gyepterĂĽletein (Badacsonytomaj, Nemesgulács, Kisapáti, Gyulakeszi, KáptalantĂłti, KĹ‘vágóörs, Köveskál) vĂ©geztĂĽnk botanikai vizsgálatokat, valamint termĂ©sbecslĂ©st. A cönolĂłgiai felvĂ©teleket a növĂ©nyek fajszáma, összborĂtása, a gyĂłgy- Ă©s mĂ©rgezĹ‘ fajok száma, a relatĂv talajnedvessĂ©g, relatĂv nitrogĂ©nigĂ©ny Ă©s takarmányozási mutatĂłk alapján Ă©rtĂ©keltĂĽk. A termĂ©sbecslĂ©s alapján kiszámĂtottuk a terĂĽletre terhelhetĹ‘ állatlĂ©tszámot Ă©s azt összehasonlĂtottuk a jelenleg ott legelĹ‘ lĂ©tszámmal. A vizsgált medencĂ©kben a legelterjedtebb hasznosĂtási mĂłd a szabad legeltetĂ©s. Gyepjeikre általában jellemzĹ‘ volt a kedvezĹ‘tlen fajösszetĂ©tel, melynek kialakulása rendszerint visszavezethetĹ‘ a rossz gazdálkodási stratĂ©giára, a felhagyott terĂĽletek nagy arányára, mely kiválĂł lehetĹ‘sĂ©g a ruderális fajok felszaporodására
High resolution vegetation assessment with beta-diversity - a moving window approach
Monitoring designs are often suffering from the inherent non-stationarity of the monitored systems. To overcome this limition, we propose a sampling designs based on high resolution mapping and spatial analyses with double spatial scaling process. Applying for vegetation, we record the presence of plant species along 26 m or 52 m long belt transects of 520 (or 1040) units of 0.5 cm x 0.5 cm contiguous microquadrats. Beta diversity (represented as the diversity of species combinations) is estimated by subsequent computerised samplings from the baseline transect data sets. Beta diversity is scaled with changing resolutions across a range of scales from 5 cm x 5 cm to 5 cm x 500 cm. Second, it is also scaled using moving window. Local maximum of beta diversity is repeatedly calculated in 5 m extent observational windows shifted along the transect with 1 m lag, and the spatial variability of vegetation is visualized by the related beta-diversity profile. Using field example, we demonstrate that beta diversity, when applied with our methodology, is a sensitive indicator, and it can reveal more information than alpha or gamma diversity.</jats:p
- …