Seasonal carbon-balance of a semi-desert temperate grassland ecosystem over a year period

Temperate grassland ecosystems are important components of the global carbon cycle. Our object of investigation, the semi-arid sand grassland community (Festucetum vaginatae danubiale) occurs widely in Hungary. A closed-loop portable IRGA system connected to a chamber appropriate for stand-scale measurements was used to measure C02-exchange over a semi-desert temperate grassland from November 2000 to November 2001. Daily and yearly carbon balances were calculated by integration of net CO, assimilation rates. The investigated sandy grassland proved to be a relatively strong source of carbon (-131.48g C.m 2.year1) as calculated over the year, probably caused also by nutrient limitations (characteristic of thes e grasslands) during the short periods when water supply was not limiting photo-synthesis

Comparison of carbon dioxide fluxes over sandy grassland vegetation as measured by the eddy-covariance technique and by open system chamber

Within the frame of an EU sponsored study (Greengrass) CO2 flux measurements were started on differently managed grassland ecosystems. We utilized two techniques– eddy-covariance (EC) and open system gas exchange chamber (OC) – to measure CO2 fluxes and compare the results of the two different methods. The study period presented in this paper covers 2003 and 2004, when the weather conditions were substantially different. OC measurements were made during the nine measurement campaigns in the two years. In comparison with EC the open system chamber proved to be a good tool for gas exchange measurements in grasslands

Optimal design of curved folded plates

The plated structures are one of the most frequently used engineering, structures. The object of this research work is the optimal design of curved folded plates. This work is an ongoing investigation. There are various solution methods to analyze this type of structures. Here the finite strip method is used. At first single load condition is considered, but later the multiple load conditions are used for the design. The base formulation is a minimum volume design with displacement constraint what is represented by the compliance. For the multiple loading two equivalent topology optimization algorithms can be elaborated: minimization of the maximum strain energy with respect to a given volume or minimization of the volume of the structure subjected to displacement constraints. The numerical procedures are based on iterative formulas which is formed by the use of the first order optimality condition of the Lagrangian-functions. The application is illustrated by numerical examples