Affine crystal structure on rigged configurations of type D_n^(1)

Extending the work arXiv:math/0508107, we introduce the affine crystal action on rigged configurations which is isomorphic to the Kirillov-Reshetikhin crystal B^{r,s} of type D_n^(1) for any r,s. We also introduce a representation of B^{r,s} (r not equal to n-1,n) in terms of tableaux of rectangular shape r x s, which we coin Kirillov-Reshetikhin tableaux (using a non-trivial analogue of the type A column splitting procedure) to construct a bijection between elements of a tensor product of Kirillov-Reshetikhin crystals and rigged configurations.Comment: 26 pages, 3 figures. (v3) corrections in the proof reading. (v2) 26 pages; examples added; introduction revised; final version. (v1) 24 page

How Close to Two Dimensions Does a Lennard-Jones System Need to Be to Produce a Hexatic Phase?

We report on a computer simulation study of a Lennard-Jones liquid confined in a narrow slit pore with tunable attractive walls. In order to investigate how freezing in this system occurs, we perform an analysis using different order parameters. Although some of the parameters indicate that the system goes through a hexatic phase, other parameters do not. This shows that to be certain whether a system has a hexatic phase, one needs to study not only a large system, but also several order parameters to check all necessary properties. We find that the Binder cumulant is the most reliable one to prove the existence of a hexatic phase. We observe an intermediate hexatic phase only in a monolayer of particles confined such that the fluctuations in the positions perpendicular to the walls are less then 0.15 particle diameters, i. e. if the system is practically perfectly 2d

Point Defect Dynamics in Two-Dimensional Colloidal Crystals

We study the topological configurations and dynamics of individual point defect vacancies and interstitials in a two-dimensional colloidal crystal. Our Brownian dynamics simulations show that the diffusion mechanism for vacancy defects occurs in two phases. The defect can glide along the crystal lattice directions, and it can rotate during an excited topological transition configuration to assume a different direction for the next period of gliding. The results for the vacancy defects are in good agreement with recent experiments. For the interstitial point defects, which were not studied in the experiments, we find several of the same modes of motion as in the vacancy defect case along with two additional diffusion pathways. The interstitial defects are more mobile than the vacancy defects due to the more two-dimensional nature of the diffusion of the interstitial defects.Comment: 8 pages, 9 postscript figures. Version to appear in Phys. Rev.

Linear-in-frequency optical conductivity in GdPtBi due to transitions near the triple points

The complex optical conductivity of the half-Heusler compound GdPtBi is measured in a frequency range from 20 to 22 000 cm$^{-1}$ (2.5 meV - 2.73 eV) at temperatures down to 10 K in zero magnetic field. We find the real part of the conductivity, $\sigma_{1}(\omega)$, to be almost perfectly linear in frequency over a broad range from 50 to 800 cm$^{-1}$ ($\sim$ 6 - 100 meV) for $T \leq 50$ K. This linearity strongly suggests the presence of three-dimensional linear electronic bands with band crossings (nodes) near the chemical potential. Band-structure calculations show the presence of triple points, where one doubly degenerate and one nondegenerate band cross each other in close vicinity of the chemical potential. From a comparison of our data with the optical conductivity computed from the band structure, we conclude that the observed nearly linear $\sigma_{1}(\omega)$ originates as a cumulative effect from all the transitions near the triple points.Comment: 5+ pages, 5 figures, band-structure and optical-conductivity calculations adde

Two-channel conduction in YbPtBi

We investigated transport, magnetotransport, and broadband optical properties of the half-Heusler compound YbPtBi. Hall measurements evidence two types of charge carriers: highly mobile electrons with a temperature-dependent concentration and low-mobile holes; their concentration stays almost constant within the investigated temperature range from 2.5 to 300 K. The optical spectra (10 meV - 2.7 eV) can be naturally decomposed into contributions from intra- and interband absorption processes, the former manifesting themselves as two Drude bands with very different scattering rates, corresponding to the charges with different mobilities. These results of the optical measurements allow us to separate the contributions from electrons and holes to the total conductivity and to implement a two-channel-conduction model for description of the magnetotransport data. In this approach, the electron and hole mobilities are found to be around 50000 and 10 cm$^{2}$/Vs at the lowest temperatures (2.5 K), respectively.Comment: 6 page

ECU-oriented models for NOx prediction. Part 2: adaptive estimation by using an NOx sensor

The implantation of nitrogen oxide sensors in diesel engines is necessary in order to track emissions at the engine exhaust line for diagnosis and control of the after-treatment devices. However, the use of models is still necessary since the sensor outputs are delayed and filtered. The present paper deals with the problem of the nitrogen oxide estimation in two parts; Part 1 deals with a control-oriented model for the nitrogen oxide estimation, while Part 2 presents data fusion of the model and the sensor to improve the estimation, which is presented in the following. The use of models for the nitrogen oxide estimation is an alternative but the drift and the ageing are still issues. In order to overcome this problem, the fusion of different signals can be carried out in a smart way by means of a Kalman filter. There exist different ways of presenting this fusion, from directly tracking the bias to updating the model parameters. For this, different algorithms are proposed in this paper with the aim of correcting the model output. Furthermore, the estimation of the actual nitrogen oxide concentration, by preventing sensor delay and filtering, is also integrated in the algorithm, which is a suitable strategy for combining nitrogen oxide sensors and models on an onboard basis.Guardiola, C.; Climent, H.; Pla Moreno, B.; Blanco-Rodriguez, D. (2015). ECU-oriented models for NOx prediction. Part 2: adaptive estimation by using an NOx sensor. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering. 229(10):1345-1360. doi:10.1177/0954407014561278S134513602291

The NASA integrated test facility and its impact on flight research

The Integrated Test Facility (ITF), being built at NASA Ames-Dryden Flight Research Facility, will provide new test capabilities for emerging research aircraft. An overview of the ITF and the challenges being addressed by this unique facility are outlined. The current ITF capabilities, being developed with the X-29 Forward Swept Wing Program, are discussed along with future ITF activities

Regular-to-chaotic tunneling rates using a fictitious integrable system

We derive a formula predicting dynamical tunneling rates from regular states to the chaotic sea in systems with a mixed phase space. Our approach is based on the introduction of a fictitious integrable system that resembles the regular dynamics within the island. For the standard map and other kicked systems we find agreement with numerical results for all regular states in a regime where resonance-assisted tunneling is not relevant.Comment: 4 pages, 4 figure