A framework for digital sunken relief generation based on 3D geometric models

Sunken relief is a special art form of sculpture whereby the depicted shapes are sunk into a given surface. This is traditionally created by laboriously carving materials such as stone. Sunken reliefs often utilize the engraved lines or strokes to strengthen the impressions of a 3D presence and to highlight the features which otherwise are unrevealed. In other types of reliefs, smooth surfaces and their shadows convey such information in a coherent manner. Existing methods for relief generation are focused on forming a smooth surface with a shallow depth which provides the presence of 3D figures. Such methods unfortunately do not help the art form of sunken reliefs as they omit the presence of feature lines. We propose a framework to produce sunken reliefs from a known 3D geometry, which transforms the 3D objects into three layers of input to incorporate the contour lines seamlessly with the smooth surfaces. The three input layers take the advantages of the geometric information and the visual cues to assist the relief generation. This framework alters existing techniques in line drawings and relief generation, and then combines them organically for this particular purpose

Monopole giant resonances and nuclear compressibility in relativistic mean field theory

Isoscalar and isovector monopole oscillations that correspond to giant resonances in spherical nuclei are described in the framework of time-dependent relativistic mean-field (RMF) theory. Excitation energies and the structure of eigenmodes are determined from a Fourier analysis of dynamical monopole moments and densities. The generator coordinate method, with generating functions that are solutions of constrained RMF calculations, is also used to calculate excitation energies and transition densities of giant monopole states. Calculations are performed with effective interactions which differ in their prediction of the nuclear matter compression modulus K_nm. Both time-dependent and constrained RMF results indicate that empirical GMR energies are best reproduced by an effective force with K_nm \approx 270 MeV.Comment: 30 pages of LaTeX, 18 PS-figure

Frequency dependence of microflows upon acoustic interactions with fluids

Rayleigh surface acoustic waves (SAWs), generated on piezoelectric substrates, can interact with liquids to generate fast streaming flows. Although studied extensively, mainly phenomenologically, the effect of the SAW frequency on streaming in fluids in constrained volumes is not fully understood, resulting in sub-optimal correlations between models and experimental observations. Using microfluidic structures to reproducibly define the fluid volume, we use recent advances modeling the body force generated by SAWs to develop a deeper understanding of the effect of acoustic frequency on the magnitude of streaming flows. We implement this as a new predictive tool using a finite element model of fluid motion to establish optimized conditions for streaming. The model is corroborated experimentally over a range of different acoustic excitation frequencies enabling us to validate a design tool, linking microfluidic channel dimensions with frequencies and streaming efficiencies. We show that in typical microfluidic chambers, the length and height of the chamber are critical in determining the optimum frequency, with smaller geometries requiring higher frequencies

Isoscalar dipole mode in relativistic random phase approximation

The isoscalar giant dipole resonance structure in $^{208}$Pb is calculated in the framework of a fully consistent relativistic random phase approximation, based on effective mean-field Lagrangians with nonlinear meson self-interaction terms. The results are compared with recent experimental data and with calculations performed in the Hartree-Fock plus RPA framework. Two basic isoscalar dipole modes are identified from the analysis of the velocity distributions. The discrepancy between the calculated strength distributions and current experimental data is discussed, as well as the implications for the determination of the nuclear matter incompressibility.Comment: 9 pages, Latex, 3. p.s figs, submitted to Phys. Lett.

Fényhullámhosszon és rezgésidőn belüli skálákon szuperintenzív lézerterekben keltett legújabb nemlineáris ''attofizikai'' folyamatok elméleti és kísérleti vizsgálata. = Theoretical and experimental study of the newest nonlinear processes of ''attophysics'' generated by superintense laser fields within the light wavelength and oscillation period scale.

Számos fény-anyag kölcsönhatásra vonatkozó kísérleti vizsgálatot végeztünk el, femtoszekundumos, kevés ciklusú impulzusok által indukált fotoemisszió és felületi plazmonok által erősített elektrongyorsítás jelenségére vonatkozóan. Ezen kívül fejlesztéseket hajtottunk végre egy femtoszekundumos hosszú rezonátoros csörpölt impulzusú lézer oszcillátoron. Ez a fényforrás nagyon hasznos eszköz a fent említett kísérletekben. A elméleti kutatások során az attoszekundumos fizika, a nagy intenzitású fény-anyag kölcsönhatás és a kvantumoptika területén végezünk vizsgálatokat. A projekt során ezekből az elméleti és kísérleti témákból 19 referált nemzetközi folyóiratbeli publikáció jelent meg. | We investigated several light-matter interaction phenomena experimentally, including few-cycle pulse-induced photoemission and surface plasmon enhanced electron acceleration. We have carried out femtosecond laser development based on long-cavity, chirped-pulse laser oscillators. These sources provide very useful tools for the above mentioned experiments. In terms of theoretical studies, we investigated various field in attosecond physics, high-intensity light-matter interaction and quantum optics. These experimental and theoretical studies yielded 19 peer-reviewed journal publications during the duration of the project

Shock waves from non-spherical cavitation bubbles

We present detailed observations of the shock waves emitted at the collapse of single cavitation bubbles using simultaneous time-resolved shadowgraphy and hydrophone pressure measurements. The geometry of the bubbles is systematically varied from spherical to very non-spherical by decreasing their distance to a free or rigid surface or by modulating the gravity-induced pressure gradient aboard parabolic flights. The non-spherical collapse produces multiple shocks that are clearly associated with different processes, such as the jet impact and the individual collapses of the distinct bubble segments. For bubbles collapsing near a free surface, the energy and timing of each shock are measured separately as a function of the anisotropy parameter $\zeta$, which represents the dimensionless equivalent of the Kelvin impulse. For a given source of bubble deformation (free surface, rigid surface or gravity), the normalized shock energy depends only on $\zeta$, irrespective of the bubble radius $R_{0}$ and driving pressure $\Delta p$. Based on this finding, we develop a predictive framework for the peak pressure and energy of shock waves from non-spherical bubble collapses. Combining statistical analysis of the experimental data with theoretical derivations, we find that the shock peak pressures can be estimated as jet impact-induced hammer pressures, expressed as $p_{h} = 0.45\left(\rho c^{2}\Delta p\right)^{1/2} \zeta^{-1}$ at $\zeta > 10^{-3}$. The same approach is found to explain the shock energy quenching as a function of $\zeta^{-2/3}$.Comment: Accepted for publication in Physical Review Fluid