Experimental and numerical investigation of edge tones

We study both, by experimental and numerical means the fluid dynamical phenomenon of so-called edge tones. Of particular interest is the clarification of certain scaling laws relating the frequency ƒ to geometrical quantities, namely 푑, the height of the jet, 푤, the stand-off distance and the velocity of the jet. We conclude that the Strouhal number S푑 is given by S푑 = C · (푑/푤)푛 with 푛 ≈ 1 in our case. Moreover, the constant C of the experiment agrees within 10-15% with the result of the simulation. As for the frequency dependence on the geometry and on the jet velocity there is a very good agreement of experimental and numerical results

Risikotransparenz in der Versicherungswirtschaft. Welche Rolle spielen Geodaten heute?

Wir sprechen heute – auch in der Versicherungswirtschaft – von Geointelligenz, die inzwischen eine wichtige Rolle im Risikomanagement spielt und zunehmend in der gesamten Wertschöpfungskette der Branche greift. Auch dem Wunsch von Aufsichtsbehörden, Analysten und Kunden nach mehr Transparenz können wir mit diesen Methoden nachkommen...

Vertical aerosol particle exchange in the marine boundary layer estimated from helicopter-borne measurements in the Azores region

Aerosol particles are important for radiation effects, cloud formation, and therefore the climate system. A detailed understanding of the spatial distribution of aerosol particles within the atmospheric boundary layer, which depends on sources and sinks, as well as long-range transport and vertical exchange, is important. Especially in marine regions, where the climate effect of clouds is comparably high, long-range transport with subsequent vertical mixing dominates over local aerosol sources. In this study, three different methods were applied to estimate the vertical aerosol particle flux in the marine boundary layer (MBL) and the vertical exchange between the MBL and the free troposphere (FT): eddy covariance (EC), flux–gradient similarity (K theory), and the mixed-layer gradient method (MLG). For the first time, MBL aerosol fluxes derived from these three methods were compared in the framework of the “Azores Stratocumulus Measurements of Radiation, Turbulence and Aerosols” (ACORES) field campaign in the Azores region in the northeastern Atlantic Ocean in July 2017. Meteorological parameters and aerosol and cloud properties were measured in the marine troposphere using the helicopter-borne measurement platform ACTOS (Airborne Cloud Turbulence Observation System). All three methods were applied to estimate the net particle exchange between MBL and FT. In many cases, the entrainment fluxes of the MLG method agreed within the range of uncertainty with the EC and K-theory flux estimates close to the top of the MBL, while the surface flux estimates of the different methods diverged. It was not possible to measure directly above the surface with the helicopter-borne payload, which might be a source of uncertainty in the surface fluxes. The observed particle fluxes at the top of the MBL ranged from 0 to 10×106 m−2 s−1 both in the upward and the downward direction, and the associated uncertainties were on the same order of magnitude. Even though the uncertainties of all three methods are considerable, the results of this study contribute to an improved understanding of the transport of particles between the MBL and FT and their distribution in the MBL

Влияние интенсивной пластической деформации методом кручения под квазигидростатическим давлением на структуру и фазовый состав высокоазотистой аустенитной стали Х20АГ20Ф2

We investigate the microstructure and microhardness of high-nitrogen austenitic steel Fe-20Cr-20Mn-2.6V-0.3C-0.8N (in wt. %) after upset and high-pressure torsion (HPT) (6GPa) for ?, ?, and 1 revolutions at room temperature. As the result of deformation, steel microhardness increases by 1.5 times after HPT. Slip, twinning, formation of localized deformation microbands, and precipitation hardening are the main deformation mechanisms under HPT, and the level of solid solution strengthening of steel remains high after deformation

Harbour porpoise thyroids: Histological investigations and potential interactions with environmental factors

The thyroid plays an important role in development and is of primary importance in metabolism and heat loss for cetaceans, including the harbor porpoise (Phocoena phocoena). Several studies have demonstrated that environmental contaminants can alter various aspects of thyroid function in mammals and may contribute to various histologic changes. The present study completes the data set of a 2006 study by Das et al., by performing histological and immunohistologic investigations on thyroids of 36 harbor porpoises from Belgian and United Kingdom waters. The number and mean diameter of follicles (µm) and the relative proportion of follicular, connective, and vascular tissue (%) were quantified in the thyroid gland of each individual. Interfollicular fibrosis has been observed in these thyroid glands, and the collective findings support the hypothesis of an endocrine disruption of thyroid function through organochlorinated compounds. Our study aimed also to reveal potential relationships between thyroid morphometric data and metal levels (Cd, Fe, Zn, Cu, Se, and Hg) using multivariate statistical analysis. The multiple regressions revealed statistically significant relationships between trace elements (cadmium, selenium, and copper) and thyroid fibrosis. The largely negative relationships are interesting findings but do not support the hypothesis that these elements have an adverse effect on thyroid morphometry. Further research is needed to understand the nature of any relationship between organochlorine and trace element exposure and thyroid gland morphology and function in harbor porpoises.Peer reviewe