TY - JOUR A1 - Otto, Andreas H. A1 - Prescher, Dietrich A1 - Gey, E. A1 - Schrader, Sigurd T1 - Proton affinities of some polyfluoroalkanes in comparison to the unsubstituted alkanes. The estimation of the proton affinities of polyfluorethylene and polyethylene by applying theoretical methods Y1 - 1997 ER - TY - JOUR A1 - Otto, Andreas H. A1 - Schrader, Sigurd A1 - Steiger, Th. A1 - Schneider, M. T1 - Gas phase deprotonation energies of Sulfuric Acid, Perchloric Acid, Chlorsulfuric Acid and Fluorosulfuric Acid Y1 - 1997 ER - TY - JOUR A1 - Otto, Andreas H. A1 - Steiger, Th. A1 - Schrader, Sigurd T1 - The gas phase acidity of trifluoromethanesulphonic acid : an ab initio MO and density functional theory study Y1 - 1998 ER - TY - JOUR A1 - Otto, Andreas H. A1 - Steiger, Th. A1 - Schrader, Sigurd T1 - HAICI4 in the gas phase is stronger than HTaF6. Y1 - 1998 ER - TY - JOUR A1 - Schrader, Sigurd A1 - Wortmann, Hanna Rosalie A1 - Prescher, Dietrich A1 - Lukaszuk, K. A1 - Otto, Andreas H. T1 - Solvatochromy and electro-optical study of new fluorine-containing chromophores Y1 - 1998 ER - TY - JOUR A1 - Cser, Adrienn A1 - Donner, Reik Volker A1 - Schwarz, Udo A1 - Feudel, Ulrike A1 - Otto, Andreas H. T1 - Statistical parameters of a control strategy of laser beam melt ablation N2 - Laser beam melt ablation - a contact-free machining process - offers several advantages compared to conventional processing mechanisms: there exists no tool wear and even extremely hard or brittle materials can be processed. During ablation the workpiece is molten by a CO2-laser beam, this melt is then driven out by the impulse of a process gas. The idea behind laser ablation is rather simple, but it has a major limitation in practical applications: with increasing ablation rates surface quality of the workpiece processed declines rapidly. At high ablation rates, depending on the process parameters different periodic-like structures can be observed on the ablated surface. These structures show a dependence on the line energy, which has been identified as a fundamental control parameter. In dependence on this parameter several regimes with different behaviours of the process have been separated. These regimes are distinguishable as well in the surfaces obtained as in the signals gained by the measurement of the process emissions. Further aim is to identify the different modes of the system and reach a deeper understanding of the dynamics of the molten material in order to understand the formation of these surface structures. With this it should be possible to influence the system in the direction of avoiding structure formation even at high ablation rates. Relying on the results on-line monitoring and control of the process should be studied. Y1 - 2001 UR - http://www.agnld.uni-potsdam.de/~shw/Paper/2001-EIS.ps ER - TY - JOUR A1 - Cser, Adrienn A1 - Donner, Reik Volker A1 - Schwarz, Udo A1 - Otto, Andreas H. A1 - Geiger, M. A1 - Feudel, Ulrike T1 - Towards a better understanding of laser beam melt ablation using methods of statistical analysis N2 - Laser beam melt ablation, as a contact free machining process, offers several advantages compared to conventional processing mechanisms. Although the idea behind it is rather simple, the process has a major limitation: with increasing ablation rate surface quality of the workpiece processed declines rapidly. The structures observed show a clear dependence of the line energy. In dependence of this parameter several regimes of the process have been separated. These are clearly distinguishable as well in the surfaces obtained as in the signals gained by the measurement of the process emissions which is the observed quantity chosen. Y1 - 2002 SN - 88-87030-44-8 ER - TY - BOOK A1 - Donner, Reik Volker A1 - Cser, Adrienn A1 - Schwarz, Udo A1 - Otto, Andreas H. A1 - Feudel, Ulrike T1 - An approach to a process model of laser beam melt ablation using methods of linear and non-linear data analysis N2 - As a non-contact process laser beam melt ablation offers several advantages compared to conventional processing mechanisms. During ablation the surface of the workpiece is molten by the energy of a CO2-laser beam, this melt is then driven out by the impulse of an additional process gas. Although the idea behind laser beam melt ablation is rather simple, the process itself has a major limitation in practical applications: with increasing ablation rate surface quality of the workpiece processed declines rapidly. With different ablation rates different surface structures can be distinguished, which can be characterised by suitable surface parameters. The corresponding regimes of pattern formation are found in linear and non-linear statistical properties of the recorded process emissions as well. While the ablation rate can be represented in terms of the line-energy, this parameter does not provide sufficient information about the full behaviour of the system. The dynamics of the system is dominated by oscillations due to the laser cycle but includes some periodically driven non-linear processes as well. Upon the basis of the measured time series, a corresponding model is developed. The deeper understanding of the process can be used to develop strategies for a process control. Y1 - 2003 SN - 3-928921-88-6 ER - TY - BOOK A1 - Donner, Reik Volker A1 - Cser, Adrienn A1 - Schwarz, Udo A1 - Otto, Andreas H. A1 - Feudel, Ulrike T1 - An approach to a process model of laser beam melt ablation using methods of linear and non-linear data analysis N2 - As a non-contact process laser beam melt ablation offers several advantages compared to conventional processing mechanisms. During ablation the surface of the workpiece is molten by the energy of a CO2-laser beam, this melt is then driven out by the impulse of an additional process gas. Although the idea behind laser beam melt ablation is rather simple, the process itself has a major limitation in practical applications: with increasing ablation rate surface quality of the workpiece processed declines rapidly. With different ablation rates different surface structures can be distinguished, which can be characterised by suitable surface parameters. The corresponding regimes of pattern formation are found in linear and non-linear statistical properties of the recorded process emissions as well. While the ablation rate can be represented in terms of the line-energy, this parameter does not provide sufficient information about the full behaviour of the system. The dynamics of the system is dominated by oscillations due to the laser cycle but includes some periodically driven non-linear processes as well. Upon the basis of the measured time series, a corresponding model is developed. The deeper understanding of the process can be used to develop strategies for a process control. Y1 - 2004 SN - 3-527-40430-9 ER -