The Metrology Light Source of PTB – a Source for THz Radiation

The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, operates the low-energy electron storage ring Metrology Light Source (MLS) in Berlin-Adlershof in close cooperation with the Helmholtz-Zentrum Berlin (HZB). The MLS is designed and prepared for a low-α machine optics mode based on a sextupole and octupole correction scheme, for the production of coherent synchrotron radiation in the far-IR and THz region. In our contribution we present commissioning results, which clearly indicate that the MLS, in combination with dedicated beamlines, offers intense, stable, and well-focused THz radiation. We discuss the planned use of the MLS for metrology in the THz spectral range.     

Effect of frying parameters on crispiness and sound emission of cassava crackers

Cassava crackers, based in cassava starch and water, were produced by deep-fat frying in oil at 140, 150 and 160 °C. Physical properties of cassava crackers were monitored at 5, 10 and 15 s of the frying process, moisture contents, bulk density, linear expansion and penetration forces and sound emission were evaluated. The results showed that with increasing frying (time and temperature), the moisture content, the linear expansion, the number of force and sound peaks significantly increased while the density and maximum and mean of force peaks decreased. Further it could be seen that with higher temperature the number of small size air cells increased. Correlations were found between physical and textural properties and sound emission. Moisture content, bulk density, maximum of sound peak, maximum force and mean force were negatively correlated with linear expansion, number of sound peaks and number of force peaks.     

The collisions of high-velocity clouds with the galactic halo

Spiral galaxies are surrounded by a widely distributed hot coronal gas and seem to be fed by infalling clouds of neutral hydrogen gas with low metallicity and high velocities. We numerically study plasma waves produced by the collisions of these high-velocity clouds (HVCs) with the hot halo gas and with the gaseous disk. In particular, we tackle two problems numerically: 1) collisions of HVCs with the galactic halo gas and 2) the dispersion relations to obtain the phase and group velocities of plasma waves from the equations of plasma motion as well as further important physical characteristics such as magnetic tension force, gas pressure, etc. The obtained results allow us to understand the nature of MHD waves produced during the collisions in galactic media and lead to the suggestion that these waves can heat the ambient halo gas. These calculations are aiming at leading to a better understanding of dynamics and interaction of HVCs with the galactic halo and of the importance of MHD waves as a heating process of the halo gas.     

Safe Transport of Acrylic Acid in Railroad Tank Cars. Part 1: Determination of the Self‐Accelerating Decomposition Temperature

Experiments according to a test specified in the UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, and numerical simulations by means of a finite element method are employed to determine the self‐accelerating decomposition temperature of acrylic acid in a railroad tank car. The results demonstrate that the transport of acrylic acid in big tank cars is safe as long as some basic conditions are taken into account.     

A Model to Characterize and Predict Fugitive Emissions from Flange Joints

The new model describing the gaseous transport through graphite gaskets is based on the assumption of a flow in the transition regime through nano‐scale capillaries, using the Maxwellian wall‐slip boundary condition for rarefied gases. Together with an earlier published model describing the liquid transport in graphite gaskets, it enables the characterization of fugitive emissions of volatile organic compounds from fluid‐charged flange joints in chemical and petrochemical plants as a function of medium properties, pipe pressure, and gasket stress. Additionally, combination of the models allows predicting the emission rates of gases by experiments with liquids as the emitting fluid. Finally, recommendations are made to improve the gaskets with respect to their sealing performance towards gases.