Fractal Methods for Flaw Detection in NDE Imagery

Detection and measurement of flaws play a major role in an emerging “fail-safe” philosophy of structural design and evaluation [1]. This philosophy allows the existence of flaws in parts in service but requires that the flaws be identified, measured and evaluated to determine if they could lead to catastrophic failure during the design life of the part. In this way greater use is made of the part, leading to considerable savings in materials and manufacturing costs. These savings come at the expense of the development of nondestructive inspection technologies that are required for flaw detection, identification and sizing

Quantum mechanical and quasiclassical investigation of the time domain nonadiabatic dynamics of NO2 close to the bottom of the X2A1-A2B2 conical intersection

We use the effective Hamiltonian that we recently fitted against the first 306 experimentally observed vibronic transitions of NO2 [J. Chem. Phys. 119, 5923 (2003)] to investigate the time domain nonadiabatic dynamics of this molecule on the coupled X2A1 and A2B2 electronic states, using both quantum mechanical and quasiclassical techniques. From the quantum mechanical point of view, we show that the transfer of population to the electronic ground state originating from a wave packet launched on the excited state occurs in a stepwise fashion. The evolution of wave packets launched on the electronic ground state is instead more complex because the crossing seam is located close to the bottom of the electronic excited state. We next use the mapping formalism, which replaces the discrete electronic degrees of freedom by continuous ones, to obtain a classical description of the coupled electronic states. We propagate gaussian swarms of trajectories to show that this approach can be used to calculate the populations in each electronic state. We finally propose a very simple trajectory surface hopping model, which assumes that trajectories have a constant probability to jump onto the other state in a particular region of the phase space and a null hopping probability outside from this region. Quasiclassical calculations show that this model enables a precise estimation of complex quantities, like for example the projection of the instantaneous probability density on given planes.Comment: accepted for publication in J. Chem. Phy

Shifting Bordering and Rescue Practices in the Central Mediterranean Sea, October 2013–October 2015

This counter‐mapping project illustrates the areas of intervention of different operations geared toward rescue and enforcement between 2013 and 2015, including the Italian Navy's “Mare Nostrum” search and rescue mission, the EU border agency Frontex's “Triton” enforcement operation, the humanitarian interventions of commercial vessels, and the action of civil‐society rescue vessels such as those operated by Médecins Sans Frontières (MSF—Doctors Without Borders). The project offers a spatial understanding of the Mediterranean border‐scape, the practices of rescue and enforcement that occur within it, and the risk of sea‐crossing at this particular moment. Through these maps, the Central Mediterranean Sea emerges as a striking laboratory from which novel legal arrangements, surveillance technologies, and institutional assemblages converge

Shifting Bordering and Rescue Practices in the Central Mediterranean Sea, October 2013-October 2015

This counter‐mapping project illustrates the areas of intervention of different operations geared toward rescue and enforcement between 2013 and 2015, including the Italian Navy's “Mare Nostrum” search and rescue mission, the EU border agency Frontex's “Triton” enforcement operation, the humanitarian interventions of commercial vessels, and the action of civil‐society rescue vessels such as those operated by Médecins Sans Frontières (MSF—Doctors Without Borders). The project offers a spatial understanding of the Mediterranean border‐scape, the practices of rescue and enforcement that occur within it, and the risk of sea‐crossing at this particular moment. Through these maps, the Central Mediterranean Sea emerges as a striking laboratory from which novel legal arrangements, surveillance technologies, and institutional assemblages converge

Baryonic Operators for Lattice Simulations

The construction of baryonic operators for determining the N* excitation spectrum is discussed. The operators are designed with one eye towards maximizing overlaps with the low-lying states of interest, and the other eye towards minimizing the number of sources needed in computing the required quark propagators. Issues related to spin identification are outlined. Although we focus on tri-quark baryon operators, the construction method is applicable to both mesons and penta-quark operators.Comment: 3 pages, poster presented at Lattice2003(spectrum), Tsukuba, Japan, July 15-19, 200

On the glueball spectrum in O(a)-improved lattice QCD

We calculate the light `glueball' mass spectrum in N_f=2 lattice QCD using a fermion action that is non-perturbatively O(a) improved. We work at lattice spacings a ~0.1 fm and with quark masses that range down to about half the strange quark mass. We find the statistical errors to be moderate and under control on relatively small ensembles. We compare our mass spectrum to that of quenched QCD at the same value of a. Whilst the tensor mass is the same (within errors), the scalar mass is significantly smaller in the dynamical lattice theory, by a factor of ~(0.84 +/- 0.03). We discuss what the observed m_q dependence of this suppression tells us about the dynamics of glueballs in QCD. We also calculate the masses of flux tubes that wind around the spatial torus, and extract the string tension from these. As we decrease the quark mass we see a small but growing vacuum expectation value for the corresponding flux tube operators. This provides clear evidence for `string breaking' and for the (expected) breaking of the associated gauge centre symmetry by sea quarks.Comment: 33pp LaTeX. Version to appear in Phys. Rev.

Scattering Theory of Kondo Mirages and Observation of Single Kondo Atom Phase Shift

We explain the origin of the Kondo mirage seen in recent quantum corral Scanning Tunneling Microscope (STM) experiments with a scattering theory of electrons on the surfaces of metals. Our theory combined with experimental data provides the first direct observation of a single Kondo atom phase shift. The Kondo mirage at the empty focus of an elliptical quantum corral is shown to arise from multiple electron bounces off the walls of the corral in a manner analagous to the formation of a real image in optics. We demonstrate our theory with direct quantitive comparision to experimental data.Comment: 13 pages; significant clarifications of metho

Correlation of fluctuating forces with the sound radiation from rigid flow spoilers

Effects of aerodynamic forces on jet engine noise from rigid flow spoiler

Extracting FπF_\pi from small lattices: unquenched results

We calculate the response of the microscopic Dirac spectrum to an imaginary isospin chemical potential for QCD with two dynamical flavors in the chiral limit. This extends our previous calculation from the quenched to the unquenched theory. The resulting spectral correlation function in the $\epsilon$-regime provides here, too, a new and efficient way to measure $F_\pi$ on the lattice. We test the method in a hybrid Monte Carlo simulation of the theory with two staggered quarks.Comment: 7 pages, 5 figure