Tsunami Efficiency Due to Very Slow Earthquakes

Often, tsunami “sources” have been treated as a quasistatic problem. Initial studies have demonstrated that, for earthquake rupture velocities in the span of 1.5–3 km/s, the kinematic and static part of the tsunami can be treated separately. However, very slow earthquake rupture velocities in the span of 0.1–1 km/s have not been included in tsunami analytical or numerical modeling. Here, we calculated the tsunami efficiency, extending Kajiura’s definition for different models. We demonstrated that rupture velocity cannot be neglected for very slow events, that is, rupture velocities slower than 0.5 km/s. We also examined the relation of magnitude, earthquake rupture velocity, and tsunami amplitude to the efficiency of very slow tsunamigenic earthquakes. Hypothetical megathrust earthquakes (Mw>8.5) with very slow rupture velocities amplify energy from 10 to 60 times larger than moderate to large earthquakes (7.0<Mw<8.5) in the direction of rupture propagation.

MOVING OBJECTS AWARE SENSOR MESH FUSION FOR INDOOR RECONSTRUCTION FROM A COUPLE OF 2D LIDAR SCANS

Indoor mapping attracts more attention with the development of 2D and 3D camera and Lidar sensor. Lidar systems can provide a very high resolution and accurate point cloud. When aiming to reconstruct the static part of the scene, moving objects should be detected and removed which can prove challenging. This paper proposes a generic method to merge meshes produced from Lidar data that allows to tackle the issues of moving objects removal and static scene reconstruction at once. The method is adapted to a platform collecting point cloud from two Lidar sensors with different scan direction, which will result in different quality. Firstly, a mesh is efficiently produced from each sensor by exploiting its natural topology. Secondly, a visibility analysis is performed to handle occlusions (due to varying viewpoints) and remove moving objects. Then, a boolean optimization allows to select which triangles should be removed from each mesh. Finally, a stitching method is used to connect the selected mesh pieces. Our method is demonstrated on a Navvis M3 (2D laser ranger system) dataset and compared with Poisson and Delaunay based reconstruction methods.

Estruturas romanas de Carnide – Lisboa

The archeological excavations carried out at Sant’Anna Palace, Carnide (Lisbon) revealed Roman occupation documented by the remains of an opus signinum coated pavement. Possibly a tank or a well dug in bed rock, circle shaped built with dry stone masonry. It was deactivated and filled with dirt, stones and other archeological materials. Standing out among the collected Roman materials we can find: terra sigillata ceramic fragments, Lusitana and Bética type amphoras, common ceramic, as well as static part of a sandstone millstone, which lead us to the conclusion that this place was occupied between the 1st and 3rd centuries A. C.

An improved test of the general relativistic effect of frame-dragging using the LARES and LAGEOS satellites

We report the improved test of frame-dragging, an intriguing phenomenon predicted by Einstein’s General Relativity, obtained using 7 years of Satellite Laser Ranging (SLR) data of the satellite LARES (ASI, 2012) and 26 years of SLR data of LAGEOS (NASA, 1976) and LAGEOS 2 (ASI and NASA, 1992). We used the static part and temporal variations of the Earth gravity field obtained by the space geodesy mission GRACE (NASA and DLR) and in particular the static Earth’s gravity field model GGM05S augmented by a model for the 7-day temporal variations of the lowest degree Earth spherical harmonics. We used the orbital estimator GEODYN (NASA). We measured frame-dragging to be equal to $$0.9910 \pm 0.02$$0.9910±0.02, where 1 is the theoretical prediction of General Relativity normalized to its frame-dragging value and $$\pm 0.02$$±0.02 is the estimated systematic error due to modelling errors in the orbital perturbations, mainly due to the errors in the Earth’s gravity field determination. Therefore, our measurement confirms the prediction of General Relativity for frame-dragging with a few percent uncertainty.

Dynamic instability of castellated beams subjected to transverse periodic loading

In this study, an analytical solution is developed for the investigation of free vibration, static buckling and dynamic instability of castellated beams subjected to transverse periodic loading. Bolotin’s method is used to perform the dynamic instability analysis. By assuming the instability modes, the mass, stiffness, and geometric stiffness matrices are derived using the kinetic energy, strain energy and potential of applied loads. Analytical equations for determining the free vibration frequency, critical buckling moment, and excitation frequency of castellated beams are derived. In addition, the influences of the flange width of the castellated beam and the static part of the applied load on the variation of dynamic instability zones are discussed.

Numerical study of dynamic noseleaf models in greater horseshoe bats, Rhinolophus ferrumequinum

Echolocating greater horseshoe bats (Rhinolophus ferrumequinum) emit biosonar pulses through nostril. The nostrilis surrounded by sophisticated and delicate appendages, i.e. noseleaf. It is known that the static part of noseleaf can cause different effects on bat biosonar pulse. In addition, the dynmaic noseleaf was found to be able to shape their emission beam. For detailed investigation of the effects of dynamic lancet on the ultrasonic beam, a 3D noseleaf model was constructed using the micro CT scanning of the noseleaf samples, and a simple model was constructed digitally for comparison. The model consists of two parts, for which one is the triangle on the top and the other one is the rectangle at the bottom. Quantitative numerical investigation on the lancet dynamic effect on the ultrasonic beam was performed using finite element analysis for both models.

Differential and integral cross sections for electron elastic scattering by ammonia for incident energies ranging from 10 eV to 20 keV

Differential and integral cross sections for elastic scattering of electron by NH3 molecule are investigated for the energy ranging from 10 eV to 20 keV. The calculations are carried out in the framework of partial wave formalism describing the target molecule by means of one center molecular Hartree-Fock functions. A spherical complex optical potential used includes a static part – obtained here numerically from quantum calculation – and fine effects like correlation, polarization and exchange potentials. The results obtained in this model point out clearly the role played by the exchange and the correlation-polarization contributions in particular at lower scattering angles and lower incident energies. Both differential and integral cross sections obtained are compared with a large set of experimental data available in the literature and well agreement is found throughout the scattering angles and whole energy range investigated here.

On a ‘time’ reparametrization in relativistic electrodynamics with travelling waves

We briefly report on our method [23] of simplifying the equations of motion of charged particles in an electromagnetic (EM) field that is the sum of a plane travelling wave and a static part; it is based on changes of the dependent variables and the independent one (light-like coordinate ξ instead of time t). We sketch its application to a few cases of extreme laser-induced accelerations, both in vacuum and in plane problems at the vacuum-plasma interface, where we are able to reduce the system of the (Lorentz-Maxwell and continuity) partial differential equations into a family of decoupled systems of Hamilton equations in 1 dimension. Since Fourier analysis plays no role, the method can be applied to all kind of travelling waves, ranging from almost monochromatic to socalled “impulses”.