Neuartige HF-angeregte Plasmaquellen fuer Atmosphaerendruck. Teilvorhaben: Grundlegende Untersuchungen zum Einsatz der Mie-Ellipsometrie zur Partikeldiagnostik Abschlussbericht

SIGLEAvailable from TIB Hannover: DtF QN1(97,43) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Regularized penalty methods for optimal control of ill-posed elliptic systems

Application of prox-regularization to ill-posed stationary control problems is investigated. Stable variants of penalty methods with one-step and multi-step regularizations in the auxiliary problems are developed and their convergence is proved for distributed as well as boundary control problems with state constraints and Dirichlet or Neumann conditions. (orig.)SIGLEAvailable from TIB Hannover: RO 7722(522) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Investigations on the environmental chemistry of atmospheric mercury on local, regional and global scales

Mercury is outstanding among the global environmental pollutants of continuing concern. Long-range atmospheric transport, its transformation to more toxic methylmercury compounds, and their bioaccumulation in the aquatic food-chain have motivated intensive international research in this field. The starting point of this habilitation thesis is a research study carried out to assess the mercury emissions and environmental impact from a partly demolished industrial plant in the Halle/Leipzig area as an example for the atmospheric dispersion of atmospheric mercury on a local scale. It was estimated that between 2 to 4 kg were emitted per day from the industrial complex and that about 30% of the emissions were deposited in the local vicinity of the plant, whereas 70% were available for long-range-transport at least on a regional scale. Since gaseous elemental mercury has an estimated average in the atmosphere of about 1 year, it is also subject to long-range-atmospheric transport on regional, hemispherical and even global scales. Observational data on the spatial and temporal distribution of atmospheric mercury are extremely limited. Analytical capabilities have been developed to generate input data for numerical simulation models to quantify the distribution, transport and deposition of atmospheric mercury over north-western and central Europe. The data sets presented in this work are currently in use as reference data for an international model intercomparison exercise under the UN-ECE Convention on Long-Range Transport of Air Pollutants, coordinated by EMEP-Meteorological Synthesizing Centre East in Moscow, Russia. Long-term measurements at a site located at the western Irish coast line have shown stable concentration levels of atmospheric mercury over several years despite reduced emissions in Europe. An increase of 4% per year was detected for air masses clearly of marine origin, possibly reflecting a trend in global emissions. A significant concentration gradient has been measured between the northern and southern hemisphere with an about 30% higher northern hemispheric mean. Finally, first measurements of atmospheric mercury have been carried out in Antarctica and are supplemented by data of a Canadian group obtained in the Arctic to assess the importance of polar regions as sinks in the global cycling of mercury. With the first annual time series of atmospheric mercury in the Antarctic it could be shown that the phenomenon of mercury depletion events (MDEs) do occur in the South polar region and that these events are positively correlated with ground level ozone concentrations during Antarctic spring. (orig.)SIGLEAvailable from TIB Hannover: RA 3251(03/23) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman