Follower-Force Experiments with Geometric Non-Linear Coupling for Analytical Validation

This study was a follow-up of a previous study where static deflection data of a joined-wing test article was collected from a series of experiments using a laser scanner and a laser tracker while the test articles were subjected to follower-forces. One of the goals of this study was to collect accurate experimental data which could be used to validate analytical methods, such as geometrically exact beam theory, which are used to predict the nonlinear response of joined-wings. The load application system used on the previous study was not able to provide a follower-force on the test articles, and therefore the loads were not representative of what the joined-wing would experience under more realistic loading conditions. The test articles used for the experiments are the qualification model and the joined-wing model. The qualification model is simply a thin aluminum beam, which is 72 in long, 8 in wide, and 0.5 in thick, and the joined-wing model is made up of two aluminum beams, which are similar in dimension to the qualification model and are joined at the tip. The qualification model was used mainly for validating the experimental procedures in preparation for the actual experiment on the joined-wing model. The deflection data of the test articles were collected using a laser tracker, and some of the measurement locations were chosen for easy comparison with the results from the previous study. The experimental data is compared to the results obtained using finite element analysis to determine how close the finite element analysis predictions are to the actual data

Local Hall effect in hybrid ferromagnetic/semiconductor devices

We have investigated the magnetoresistance of ferromagnet-semiconductor devices in an InAs two-dimensional electron gas system in which the magnetic field has a sinusoidal profile. The magnetoresistance of our device is large. The longitudinal resistance has an additional contribution which is odd in applied magnetic field. It becomes even negative at low temperature where the transport is ballistic. Based on the numerical analysis, we confirmed that our data can be explained in terms of the local Hall effect due to the profile of negative and positive field regions. This device may be useful for future spintronic applications.Comment: 4 pages with 4 fugures. Accepted for publication in Applied Physics Letter

Pattern Formation in a Two-Dimensional Array of Oscillators with Phase-Shifted Coupling

We investigate the dynamics of a two-dimensional array of oscillators with phase-shifted coupling. Each oscillator is allowed to interact with its neighbors within a finite radius. The system exhibits various patterns including squarelike pinwheels, (anti)spirals with phase-randomized cores, and antiferro patterns embedded in (anti)spirals. We consider the symmetry properties of the system to explain the observed behaviors, and estimate the wavelengths of the patterns by linear analysis. Finally, we point out the implications of our work for biological neural networks

2,4-Bis(4-fluoro­phen­yl)-3-aza­bicyclo­[3.3.1]nonan-9-one

In the title compound, C20H19F2NO, a crystallographic mirror plane bis­ects the mol­ecule, passing through the N, O and two C atoms of the central ring system. The mol­ecule exists in a twin-chair conformation with equatorial dispositions of the 4-fluoro­phenyl groups on both sides of the secondary amino groups; the dihedral angle between the aromatic ring planes is 28.67 (3)°

Hybridization gap and Fano resonance in SmB6{_6}

We present results of Scanning Tunneling Microscopy and Spectroscopy (STS) measurements on the "Kondo insulator" SmB$_6$. The vast majority of surface areas investigated was reconstructed but, infrequently, also patches of varying size of non-reconstructed, Sm- or B-terminated surfaces were found. On the smallest patches, clear indications for the hybridization gap and inter-multiplet transitions were observed. On non-reconstructed surface areas large enough for coherent co-tunneling we were able to observe clear-cut Fano resonances. Our locally resolved STS indicated considerable finite conductance on all surfaces independent of their structure.Comment: 5 pages, 4 figure

Time-delayed Spatial Patterns in a Two-dimensional Array of Coupled Oscillators

We investigated the effect of time delays on phase configurations in a set of two-dimensional coupled phase oscillators. Each oscillator is allowed to interact with its neighbors located within a finite radius, which serves as a control parameter in this study. It is found that distance-dependent time-delays induce various patterns including traveling rolls, square-like and rhombus-like patterns, spirals, and targets. We analyzed the stability boundaries of the emerging patterns and briefly pointed out the possible empirical implications of such time-delayed patterns.Comment: 5 Figure