NASYP: Online expert tool on the control of major-accident hazards involving dangerous substances

NASYP is an online Geoportal tool being developed in cooperation with state and regional authorities to improve insufficient practices based on implementation of Directive nr. 2003/105/ES on the control of major-accident hazards involving dangerous substances. The tool is applicable for managing the permits, reporting and regular monitoring issues. Furthermore, it’s applicable for a risk assessment and a rapid management of disasters in the initial phase. There’re simple modeling tools included to simulate early stages of the contamination caused by disasters occurred to be used for decision making and effective use of emergency services. In this manner, there’re low atmospheric and surface water pollutions taken into account. For the study area, Liberec region was chosen covering the area of 3,163km2 and containing 533 potentially dangerous objects categorized accordingly to the Directive nr. 2003/105/ES. The model simulations are responding to daily hydrological and meteorological situation, a capability of automated updates from databases operated by the Czech Hydro Meteorological Institute, and communicate with databases of substances operated by the regional authorities. NASYP is suitable especially for the “N†class of the operators defined in the Directive, where because of smaller amounts of stored dangerous substances the safety measures and regular inspections are limited.Spatial data, geoportal, risk management, modelling, Research and Development/Tech Change/Emerging Technologies, Research Methods/ Statistical Methods, Risk and Uncertainty, GA, IN,

Multiple Components in Narrow Planetary Rings

The phase-space volume of regions of regular or trapped motion, for bounded or scattering systems with two degrees of freedom respectively, displays universal properties. In particular, drastic reductions in the volume (gaps) are observed at specific values of a control parameter. Using the stability resonances we show that they, and not the mean-motion resonances, account for the position of these gaps. For more degrees of freedom, exciting these resonances divides the regions of trapped motion. For planetary rings, we demonstrate that this mechanism yields rings with multiple components.Comment: 4 pages, 7 figures (some in colors

Impact inducted surface heating by planetesimals on early Mars

We investigate the influence of impacts of large planetesimals and small planetary embryos on the early Martian surface on the hydrodynamic escape of an early steam atmosphere that is exposed to the high soft X-ray and EUV flux of the young Sun. Impact statistics in terms of number, masses, velocities, and angles of asteroid impacts onto the early Mars are determined via n-body integrations. Based on these statistics, smoothed particle hydrodynamics (SPH) simulations result in estimates of energy transfer into the planetary surface material and according surface heating. For the estimation of the atmospheric escape rates we applied a soft X-ray and EUV absorption model and a 1-D upper atmosphere hydrodynamic model to a magma ocean-related catastrophically outgassed steam atmosphere with surface pressure values of 52 bar H2O and 11 bar CO2. The estimated impact rates and energy deposition onto an early Martian surface can account for substantial heating. The energy influx and conversion rate into internal energy is most likely sufficient to keep a shallow magma ocean liquid for an extended period of time. Higher surface temperatures keep the outgassed steam atmosphere longer in vapor form and therefore enhance its escape to space within about 0.6 Myr after its formation.Comment: submitted to A&

Accurate pre- and post-eruption orbital periods for the dwarf/classical nova V1017 Sgr

V1017 Sgr is a classical nova (from 1919) that displayed an earlier dwarf nova eruption (from 1901) and underwent two more dwarf nova events (in 1973 and 1991). Previous work on this bright system in quiescence (V = 13.5) has consisted only of a few isolated magnitudes, a few spectra and an ambiguous claim of an orbital period of 5.714 d based on nine radial velocities. To test this period, we have collected 2896 magnitudes (plus 53 in the literature) in the UBVRIJHKL bands from 1897-2016, making an essentially complete photometric history of this unique cataclysmic variable. We find that the light curve in all bands is dominated by the ellipsoidal modulations of a G giant companion star, with a post-eruption (after the 1919 nova event) orbital period of 5.786290 ± 0.000032 d. This is the longest period for any classical nova; the accretion must be powered by the nuclear evolution of the companion star and dwarf nova events occur only because the outer parts of the large disc are cool enough to be unstable. Further, we measure the pre-eruption orbital period (from 1907-1916). The orbital period has decreased by 273 ± 61 parts per million across the 1919 eruption, with the significance of the period change being at the 5.7σ confidence level. This is startling and mystifying for nova theory, because the three known period-change effects cannot account for a period decrease in V1017 Sgr, much less one of such a large size

An Overview of the 13:8 Mean Motion Resonance between Venus and Earth

It is known since the seminal study of Laskar (1989) that the inner planetary system is chaotic with respect to its orbits and even escapes are not impossible, although in time scales of billions of years. The aim of this investigation is to locate the orbits of Venus and Earth in phase space, respectively to see how close their orbits are to chaotic motion which would lead to unstable orbits for the inner planets on much shorter time scales. Therefore we did numerical experiments in different dynamical models with different initial conditions -- on one hand the couple Venus-Earth was set close to different mean motion resonances (MMR), and on the other hand Venus' orbital eccentricity (or inclination) was set to values as large as e = 0.36 (i = 40deg). The couple Venus-Earth is almost exactly in the 13:8 mean motion resonance. The stronger acting 8:5 MMR inside, and the 5:3 MMR outside the 13:8 resonance are within a small shift in the Earth's semimajor axis (only 1.5 percent). Especially Mercury is strongly affected by relatively small changes in eccentricity and/or inclination of Venus in these resonances. Even escapes for the innermost planet are possible which may happen quite rapidly.Comment: 14 pages, 11 figures, submitted to CMD

Numerical analysis of propellers for electric boats using computational fluid dynamics modelling

This is the final version. Available from Elsevier via the DOI in this record. Data availability: Data will be made available on request.In the maritime industry, propellers are the most commonly used form of propulsion and are core to the optimum performance of a ship. Generally, the performance characteristics of a marine propeller are determined and analysed by experiments like open water and self-propulsion scale model tests which are costly and timeconsuming at the initial design stage. In this study, the computational fluid dynamics (CFD) simulations were performed to evaluate propeller performance. Three Wageningen B-series propellers with varying Expanded Area Ratios (EAR) were modelled with respect to the design constraints, such as ship speed and rotational velocity. The performance of the hydrodynamic coefficients, thrust, torque and open water efficiency are then analysed using the CFD modelling. These characteristics are then validated against experimental data obtained from the Netherlands Ship Model Basin open water test in Wageningen and used to investigate the flow behaviour. The analysis considers the Multiple Reference Frame (MRF) model. This study provided a well-founded framework for applying CFD in the analysis and selection of Wageningen B-series propellers, as well as investigated the relationship between the EAR, flow behaviour, thrust coefficient, and torque coefficient for electric boats. The results show that a lower thrust and torque coefficient can improve the flow behaviour with increasing the efficiency by up to 62%. Furthermore, the outcomes reveal that the lower expanded area ratio of 0.6 is more suitable for electric boats, creating a larger pressure difference of 1.079 MPa and generating extra potential thrust at the same advance ratio, which leads to greater open water efficiency.Technical University of Libere

Stability of Terrestrial Planets in the Habitable Zone of Gl 777 A, HD 72659, Gl 614, 47 Uma and HD 4208

We have undertaken a thorough dynamical investigation of five extrasolar planetary systems using extensive numerical experiments. The systems Gl 777 A, HD 72659, Gl 614, 47 Uma and HD 4208 were examined concerning the question of whether they could host terrestrial like planets in their habitable zones (=HZ). First we investigated the mean motion resonances between fictitious terrestrial planets and the existing gas giants in these five extrasolar systems. Then a fine grid of initial conditions for a potential terrestrial planet within the HZ was chosen for each system, from which the stability of orbits was then assessed by direct integrations over a time interval of 1 million years. The computations were carried out using a Lie-series integration method with an adaptive step size control. This integration method achieves machine precision accuracy in a highly efficient and robust way, requiring no special adjustments when the orbits have large eccentricities. The stability of orbits was examined with a determination of the Renyi entropy, estimated from recurrence plots, and with a more straight forward method based on the maximum eccentricity achieved by the planet over the 1 million year integration. Additionally, the eccentricity is an indication of the habitability of a terrestrial planet in the HZ; any value of e>0.2 produces a significant temperature difference on a planet's surface between apoapse and periapse. The results for possible stable orbits for terrestrial planets in habitable zones for the five systems are summarized as follows: for Gl 777 A nearly the entire HZ is stable, for 47 Uma, HD 72659 and HD 4208 terrestrial planets can survive for a sufficiently long time, while for Gl 614 our results exclude terrestrial planets moving in stable orbits within the HZ.Comment: 14 pages, 18 figures submitted to A&