Ab initio description of nonlinear dynamics of coupled microdisk resonators with application to self-trapping dynamics

Ab initio approach is used to describe the time evolution of the amplitudes of whispering gallery modes in a system of coupled microdisk resonators with Kerr nonlinearity. It is shown that this system demonstrates a transition between Josephson-like nonlinear oscillations and self-trapping behavior. Manifestation of this transition in the dynamics of radiative losses is studied.Comment: 10 pages, 5 figures, accepted for publication in Phys. Rev.

U-Pb Zircon Geochronology of Roxbury Conglomerate, Boston Basin, Massachusetts: Tectono-stratigraphic Implications for Avalonia in and Beyond SE New England

High-precision CA-TIMS 206Pb/238U zircon dates from sandstone and Brighton igneous rocks associated with Roxbury Conglomerate in the Boston Basin, eastern Massachusetts provide constraints on the age and tectonic significance of these deposits. Detrital zircon suites from Roxbury-related sandstones representing, in ascending order, the Franklin Park Member (proposed name), the Brookline Member and the Squantum Member establish closely comparable maximum depositional ages of 595.14 ± 0.90, 598.87 ± 0.71 and 596.39 ± 0.79 Ma, respectively. The youngest of these is the best maximum age estimate of the conglomerate. Brighton dacite near the base of the Brookline Member and amygdaloidal andesite near the top yield respective crystallization ages of 584.19 ± 0.70 Ma and 585.37 ± 0.72 Ma. These virtually identical dates support previous interpretations of these particular units as shallow intrusions and thus represent minimum ages of associated conglomerate. The Roxbury-Brighton sequence is traditionally shown as inter-fingering northward with ≤570 Ma mudstone of the Cambridge “Argillite,” but the age range of the conglomerate makes this impossible. Conglomerate lacking quartzite clasts typical of the Roxbury proper and associated with 593.19 ± 0.73 Ma rhyolite on the south side of the basin is re-assigned to the Lynn-Mattapan Volcanic Complex which rests unconformably on Dedham Granite in basement exposed west and north of the basin as well. Calc-alkaline geochemistry and ages of the 609 to 584 Ma Dedham-Lynn-Mattapan-Brighton assemblage link it with 630 to 580 Ma arc sequences in other northern Appalachian Avalonian terranes. Roxbury Conglomerate accumulated in fault-bounded intra-arc basins near the end of this magmatic cycle

PT-Symmetric Talbot Effects

We show that complex PT-symmetric photonic lattices can lead to a new class of self-imaging Talbot effects. For this to occur, we find that the input field pattern, has to respect specific periodicities which are dictated by the symmetries of the system. While at the spontaneous PT-symmetry breaking point, the image revivals occur at Talbot lengths governed by the characteristics of the passive lattice, at the exact phase it depends on the gain and loss parameter thus allowing one to control the imaging process.Comment: 5 pages, 3 figure

Efficient Rotating Frame Simulation in Turbomachinery

This paper deals with the simulation of steady flows in tur- bomachinery. Two approaches are proposed, the first one is the classical multiple-rotating frame method (MRF) by multi- zone approach where the different zones are separated by non- overlapping interfaces and solved independently. Since each zone is loaded separately, a transferring system should be prop- erly implemented at the interface boundaries. Two techniques are considered, in the first one the conservative variables are in- terpolated between zones while in the second one the fluxes are transferred through the interfaces. The other proposed approach is a new version of the MRF using a virtual interface (VMRF). This is a simplified of the pre- vious one where the interfaces are created virtually at the solver level, rendering the method easy to implement especially for edge-based numerical schemes, and avoiding any re-meshing in case one needs to change interface position, shape or simply re- move or add new one. Finally, numerical tests are performed to demonstrate the efficiency of the proposed methods by compari- son with commercial codes (ANSYS FLUENT)

New Simplified Algorithm for the Multiple Rotating Frame Approach in Computational Fluid Dynamics

This paper deals with rotating effects simulation of steady flows in turbomachinery. To take into account the rotating nature of the flow, the frozen rotor approach is one of the widely used approaches. This technique, known in a more general context as a multiple rotating frame (MRF), consists on building axisymmetric interfaces around the rotating parts and solves for the flow in different frames (static and rotating). This paper aimed to revisit this technique and propose a new algorithm referred to it by a virtual multiple rotating frame (VMRF). The goal is to replace the geometrical interfaces (part of the computer-aided design (CAD)) that separate the rotating parts replaced by the virtual ones created at the solver level by a simple user input of few point locations and/or parameters of basic shapes. The new algorithm renders the MRF method easy to implement, especially for edge-based numerical schemes, and very simple to use. Moreover, it allows avoiding any remeshing (required by the MRF approach) when one needs to change the interface position, shape, or simply remove or add a new one, which frequently happened in practice. Consequently, the new algorithm sensibly reduces the overall computations cost of a simulation. This work is an extension of a first version published in an ASME conference, and the main new contributions are the detailed description of the new algorithm in the context of cell-vertex finite volume method and the validation of the method for viscous flows and the three-dimensional (3D) case which is of significant importance to the method to be attractive for real and industrial applications.BCAM-BALTOGAR CFD Platform for Turbomachinery Simulation and Design (BFA/DFB - 6/12/TK/2012/00020

Scattering of a Dirac electron on a mass barrier

The interaction of a wave packet (and in particular the wave front) with a mass barrier is investigated in one dimension. We discuss the main features of the wave packet that are inherent to two-dimensional wave packets, such as compression during reflection, penetration in the case when the energy is lower than the height of the barrier, waving tails, precursors, and the retardation of the reflected and penetrated wave packets. These features depend on the wave-packet envelope function which we demonstrate by considering the case of a rectangular wave packet with sharp front and trailing edges and a smooth Gaussian wave packet. The method of Fourier integral for obtaining the nonstationary solutions is used.Comment: 12 pages, 9 figure

BBIPED: BCAM-Baltogar Industrial Platform for Engineering Design

Currently, commercial software for computational fluid dynamics offers a good set of features to deal with traditional designs. Within a competitive market industrial innovation is a key factor that must be faced by companies. However, the design of solutions to deal with industrial challenges cannot be done within commercial software due to the lack of flexibility. Open source initiatives are a good option but the learning curve is high, specially for industrial engineers profiles. In this paper, we present the BBIPED platform which has been designed to deal with turbomachinery applications in a simple and friendly way. The main goal is to keep the platform as simpler as possible providing the enough flexibility to include out-of-the-box solutions to cope with industrial challenges. BBIPED platform provides links with currently existing remarkable open source initiatives altogether with our own developments. Particularly, it is remarkable a first approach for automatic mesh generation based on geometry parametrization solution, and the provision of novel techniques to deal with multiple rotating frame (MRF): Multizone MRF an Virtual MRF. Case tests were designed to test the solutions and to assess and validate the results against commercial suites with promising results

Resonant valley filtering of massive Dirac electrons

Electrons in graphene, in addition to their spin, have two pseudospin degrees of freedom: sublattice and valley pseudospin. Valleytronics uses the valley degree of freedom as a carrier of information similar to the way spintronics uses electron spin. We show how a double barrier structure consisting of electric and vector potentials can be used to filter massive Dirac electrons based on their valley index. We study the resonant transmission through a finite number of barriers and we obtain the energy spectrum of a superlattice consisting of electric and vector potentials. When a mass term is included the energy bands and energy gaps at the K and K' points are different and they can be tuned by changing the potential.Comment: 20 figure

Spectrofluorimetric Determination of Human Serum Albumin Using Terbium-Danofloxacin Probe

A spectrofluorimetric method is proposed for the determination of human serum albumin (HSA) and bovine serum albumin (BSA) using terbium-danofloxacin (Tb3+-Dano) as a fluorescent probe. These proteins remarkably enhance the fluorescence intensity of the Tb3+-Dano complex at 545 nm, and the enhanced fluorescence intensity of Tb3+-Dano is proportional to the concentration of proteins (HSA and BSA). Optimum conditions for the determination of HSA were investigated and found that the maximum response was observed at: pH = 7.8, [Tb3+] = 8.5 × 10−5 mol L−1, [Dano] = 1.5 × 10−4 mol L−1. The calibration graphs for standard solutions of BSA, HSA, and plasma samples of HSA were linear in the range of 0.2 × 10−6 − 1.3 × 10−6 mol L−1, 0.2 × 10−6 − 1.4 × 10−6 mol L−1, and 0.2 × 10−6 − 1 × 10−6 mol L−1, respectively. The detection limits (S/N = 3) for BSA, HSA, and plasma sample of HSA were 8.7 × 10−8 mol L−1, 6.2 × 10−8 mol L−1, and 8.1 × 10−8 mol L−1, respectively. The applicability of the method was checked using a number of real biological plasma samples and was compared with the UV spectrometric reference method. The results was showed that the method could be regarded as a simple, practical, and sensitive alternative method for determination of albumin in biological samples

Numerical investigation of the aerodynamic performance for a Wells-type turbine in a wave energy converter

Ocean waves constitute an extensive energy resource, whose extraction has been the subject of intense research activity in the last three decades. Among the different variants of Wave Energy Converters, the principle of the Oscillating Water Col- umn (OWC) is one of the most promising ones. An OWC comprises two key elements: a collector chamber, which transfers the wave oscillations’ energy to the air within the chamber by back and forth displacement, and a power take off system, which converts the pneumatic power into electricity or some other usable form. The Wells turbine is a self-rectifying air turbine, a suitable solution for energy extraction from reciprocating air flow in an OWC. In the present work, the steady state, inviscid flow in the Wells turbine is investigated by numerical simulations. The relatively novel Virtual Multiple Reference Frame (VMRF) technique is used to account for the rotary motion of the turbine, and the overall performance is compared with results in the literature