Influence of the Pulse Duration in the ps-Regime on the Ablation Efficiency of Metals

AbstractAblation characteristics of copper and stainless steel with laser pulses from 10 to 100 ps at 1064nm wavelength were studied. The influence of the pulse duration and the number of pulses on the threshold fluence and the penetration depth has been investigated. The results show a strong decrease of the ablation efficiency and quality with increasing pulse duration

Process Control For Ozonation Systems: A Novel Real-Time Approach

For real-time control of ozonation processes in water works, a sequencing batch reactor was constructed to measure the ozone decay rate constant (k(O3)) in short time intervals of about 15 min. The batch reactor is filled during the production process, immediately after dissolving ozone in water by a static mixer. On the basis of k(O3) and the initial ozone concentration ([O-3](0)), and the experimentally determined ratio of the concentrations of (OH)-O-center dot radicals to ozone (R-ct), the degradation of micropollutants in ozone reactors (modeled as Continuously Stirred Tank Reactors - CSTRs) were calculated for compounds with known reaction rate constants with ozone and (OH)-O-center dot radicals. Calculated degradation of atrazine, iopromide, benzotriazole and acesulfame are in good agreement with measured data. For acesulfame the following rate constants were determined in this study at 20 C-o: reaction rate constant with ozone = 88 M(1)s(1), reaction rate constant with (OH)-O-center dot radical = 4.55x10(9) M(1)s(1). For the ozone reaction an activation energy of 35 kJ/mol was determined. Similarly to micropollutants, the relative inactivation of microorganisms (N/N-0) can be calculated based on the inactivation rate constant for ozone and if applicable the lag phase. The pI-value (=logN/N-0) was introduced and implemented in the process management system to calculate online the log inactivation of reference microorganisms such as B. subtilis spores. The system was tested for variation of pH (6.58.5), DOC (1.24.2 mg/L) flowrate 3.212 m(3)/h and temperature (5.79 C-o). Furthermore, a given pI-value, e.g. 1 for a 1-log inactivation of B. subtilis spores, can be set as control parameter in the process management system. The ozone gas flow is then adjusted until the set pI-value is reached. The process control concept was validated with B. subtilis spores. Generally, a good agreement was found between calculated and measured inactivation data. It was also demonstrated, that a constant ozone residual may lead to insufficient disinfection or overdosing of ozone. The new process control concept for ozonations based on onsite measurement of the ozone decay rate constant and the pI-value allows to assess disinfection and degradation processes quantitatively in real-time

GENESIS-1 mission for improved reference frames and Earth science applications.

&amp;lt;p&amp;gt;Improving and homogenizing time and space references on Earth and, more directly, realizing the terrestrial reference system with an accuracy of 1 mm and a long-term stability of 0.1 mm/yr are relevant for many scientific and societal endeavours. The knowledge of the terrestrial reference frame (TRF) is fundamental for Earth system monitoring and related applications. For instance, quantifying sea level change strongly depends on an accurate determination of the geocenter motion but also of the position of continental or island reference stations, such as those located at tide gauges, as well as the ground stations of the tracking networks. Also, numerous applications in geophysics require absolute millimetre precision from the reference frame, as for example monitoring tectonic motion or crustal deformation for predicting natural hazards. The TRF accuracy to be achieved (mentioned above) represents the consensus of various authorities, including the International Association of Geodesy, which has enunciated geodesy requirements for Earth science (see GGOS-2020). Moreover, as stated in the A/RES/69/266 United Nations Resolution: &amp;amp;#8220;A global geodetic reference frame for sustainable development&amp;amp;#8221;, the UN recognizes the importance of &amp;amp;#8220;the investments of Member States in developing satellite missions for positioning and remote sensing of the Earth, supporting a range of scientific endeavours that improve our understanding of the Earth system and underpin decision-making, and&amp;amp;#8230; that the full societal benefits of these investments are realized only if they are referenced to a common global geodetic reference frame at the national, regional and global levels&amp;amp;#8221;. These strong statements by international bodies underline that a dedicated mission is highly needed and timely. Today we are still far away from this ambitious goal. It can be achieved by combining and co-locating, on one satellite platform, the full set of fundamental space-time geodetic systems, namely GNSS and DORIS radio satellite tracking systems, the satellite laser ranging (SLR) technique, and the very long baseline interferometry (VLBI) technique, that currently operates by recording the signals from quasars. This platform can then be considered as a dynamic space geodetic observatory carrying all these geodetic instruments referenced to one another on a unique well-calibrated platform through carefully measured space ties and a very precise atomic clock. It is necessary to set up a co-location of the techniques in space to resolve the inconsistencies and biases between them. Such a mission will be proposed as the first one of a series of missions in the GNSS/NAV Science Programme. The purpose of this abstract/talk is to revive the support of the scientific community for this mission.&amp;lt;/p&amp;gt;</jats:p