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Quasar Microlensing
(2001)
Lese-Rechtschreibschwäche
(2001)
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.
We analyse the X-ray light curves of compact objects using linear and nonlinear time series analysis methods. A Power Density Spectrum (PDS) describes the overall second order properties of the observed data well. To look beyond we propose the nonlinear Q-statistic to detect an asymmetry of the time series. This allows us to find relevant time scales. This method even grants a subclassification of the known states of X-ray sources.
Potsdamer UNO-Konferenzen
(2001)
Vorwort
(2001)
Schleiermachers Kritik an der Aufklärung und Aufklärungspädagogik : eine Überwindung der Aufklärung?
(2001)
Lernprozesse steuern
(2001)
"Selbstmanagement" versus "Staatsamateur" : Spitzensportkarrieren in Deutschland und Frankreich
(2001)
Bildungsziel Europa
(2001)
Die Informatik durchdringt zusehends fast alle Bereiche der Ausbildung und der Berufswelt. Die Stichwörter berücksichtigen die Geschichte der Informatik und den heutigen Stand ihrer Methoden und beziehen aktuelle und absehbare Entwicklungen mit ein. Das ausführliche Register sorgt dafür, dass man den gewünschten Begriff sofort im Blick hat. Rund 3 000 Stichwörter, etwa 700 Abbildungen, Register.
Ageing and executive control
(2001)
Dissociating retention and access in working memory : an age-comparative study of mental arithmetic
(2001)
Untitled - Introduction
(2001)
Correctness proofs and probabilistic tests for constructive specifications and functional programs
(2001)
Vorwort
(2001)
Preface
(2001)
Zur Rolle des Pronomen to/eto in spezifizierenden Kopulaktionstrukturen im polnischen und russischen
(2001)
Der Kulturkritiker und Schriftsteller Max Nordau : zwischen Zionismus, Deutschtum und Judentum
(2001)
Toxic heavy metals are extracted simultaneously by reactive liquid-liquid-extraction from a model landfill leachate. This is taken as an example to generate an unproblematic waste water. Alkylphosphoric acids (commercial D2EHPA and D2EHTPA), ß-diketones, 4-Acyl-5-pyrazolones and a novel commercial alkyl-methyl-phosphonic acid are used as extractants. By means of the functions E%=f (pH, t) and lg D=f (pH, cL) some thermodynamic parameters of the extraction are determined. In the case of the alkylthiophosphoric acid the thiophilic cations are extracted advantageously in contrast to chromium, magnesium or calcium. There is no significant separation between the heavy metals and the alkaline earth metals. The complexes are extracted with the composition ML(HL)n. According to their ligand force, the presence of complexing agents in the aqueous phase (for example cyanide, tartrate, ammonia or chloride) hinders the extraction. The influence of humic acid is comparable to that of tartaric acid. Because of the formation of less soluble compounds, sulphate ions make the extraction of calcium more difficult. The extraction data points out that aromatic or chloric solvents are not advantageous in contrast to the non toxic aliphatic hydrocarbons. With the novel aminomethylphosphonic acid (ironex, BASF) the extraction of iron, indium and gallium is possible at a pH > 1.5 as ML2(HL) and ML(HL)2 resp. Copper and zinc were extracted quantitatively as 1:2 complexes only in a small pH-range between 4 to 6. Generally, the best results were found for the ß-diketones (LIX 54 included) and 4-acyl-5-pyrazolones. In these cases the toxic heavy metals could be separated quantitatively. Only 6% of calcium and 23% of magnesium are coextracted by the ligands. The extraction process can further be optimized by synergistic effects.
Volcano seismology
(2001)