Punctured Trellis-Coded Modulation

In classic trellis-coded modulation (TCM) signal constellations of twice the cardinality are applied when compared to an uncoded transmission enabling transmission of one bit of redundancy per PAM-symbol, i.e., rates of $\frac{K}{K+1}$ when $2^{K+1}$ denotes the cardinality of the signal constellation. In order to support different rates, multi-dimensional (i.e., $\mathcal{D}$-dimensional) constellations had been proposed by means of combining subsequent one- or two-dimensional modulation steps, resulting in TCM-schemes with $\frac{1}{\mathcal{D}}$ bit redundancy per real dimension. In contrast, in this paper we propose to perform rate adjustment for TCM by means of puncturing the convolutional code (CC) on which a TCM-scheme is based on. It is shown, that due to the nontrivial mapping of the output symbols of the CC to signal points in the case of puncturing, a modification of the corresponding Viterbi-decoder algorithm and an optimization of the CC and the puncturing scheme are necessary.Comment: 5 pages, 10 figures, submitted to IEEE International Symposium on Information Theory 2013 (ISIT

Numerical Investigation of the Aerodynamic Properties of a Flying Wing Configuration

The numerical investigations of a generic UCAV configuration are presented. These investigations are part of the DLR internal project UCAV-2010. Compressible speed conditions are considered and presented. The DLR-F17E UCAV configuration is a flying lambda delta wing with sweep angle of 53° and varying leading edge radius. The flow field of this UCAV configuration is dominated by vortex structures and vortex-to-vortex interaction. The paper aims to give a comparison between numerical- and experimental investigations in order to gain a deeper understanding of the complex flow physics. Furthermore, it will highlight the influence of Mach- and Reynolds number change on the flow and the overall aerodynamic behavior of the configuration. The DLR TAU-Code is used to simulate the flow field, using an unstructured grid and the turbulence model of Spalart-Allmaras. Forces and moment measurements taken in the DNW-TWG, Göttingen, on the DLR-F17E configuration serve as the experimental basis to validate the numerical findings. Findings on the SACCON configuration serve as a comparison case aiming to show possible portability between different model scales but also to find analogies between low speed (M=0.15) and compressible speed (M=0.5) scenarios. This paper builds up upon the finding within the NATO/RTO AVT-161 Research Task Group on “Assessment and Control Predictions for NATO Air and Sea Vehicles” and its findings shall serve as a basis for further experimental investigations of medium to high speed wind tunnel experiments. Furthermore, this paper addresses the importance of understanding and the ability to predict controlled- and uncontrolled flow separation and the interaction of vortex systems in order to estimate the aerodynamic behavior within the entire flight envelope and to meet Stability- and Control needs

On the Analytic Structure of Scalar Glueball Operators

The correlator of the square of the Yang-Mills field-strength tensor corresponds to a scalar glueball, i.e., to a bound-state formed by gluonic ingredients only. It has quantum numbers 0++ and its mass, as predicted by different theoretical approaches, is expected to lie between 1 and 2 GeV. Here we restrict our considerations to the Born level, that is, we consider the correlator to zeroth order in the coupling. Gluonic self-interaction is taken into account indirectly by using non-perturbative gluon propagators. The employed closed expressions are motivated by lattice and Dyson-Schwinger studies. The analytic continuation of the integrals themselves is complicated by additional obstructive structures like branch cuts and poles that are induced by the inner integral in the complex plane of the outer integration variable. We deal with this problem by deforming the outer integration contour accordingly. For different input gluon propagators we find a positive glueball spectral density which is required for physical states. Poles are, however, absent which is most likely an artifact of working at Born level.Comment: 8 pages, 5 figure

The Relocation of Russian Industry 1987-1993

This study is about the effects reforms have had on industry's dispersion in Russia. We use data on regional production by industry reaching from 1987 to 1993 to consider to what extent the division of labor among regions has changed during this time period. In particular we address three issues on an industry by industry basis: Have there been significant changes in the localization of industries and have the changes been associated with concentration or diversification? Are there significant changes in the relative productivity's of industries in regions? Is there a connection between productivity changes and changes in localization?Russia; industry; relocation; productivity; reform

Inequalities for the Ranks of Quantum States

We investigate relations between the ranks of marginals of multipartite quantum states. These are the Schmidt ranks across all possible bipartitions and constitute a natural quantification of multipartite entanglement dimensionality. We show that there exist inequalities constraining the possible distribution of ranks. This is analogous to the case of von Neumann entropy (\alpha-R\'enyi entropy for \alpha=1), where nontrivial inequalities constraining the distribution of entropies (such as e.g. strong subadditivity) are known. It was also recently discovered that all other \alpha-R\'enyi entropies for $\alpha\in(0,1)\cup(1,\infty)$ satisfy only one trivial linear inequality (non-negativity) and the distribution of entropies for $\alpha\in(0,1)$ is completely unconstrained beyond non-negativity. Our result resolves an important open question by showing that also the case of \alpha=0 (logarithm of the rank) is restricted by nontrivial linear relations and thus the cases of von Neumann entropy (i.e., \alpha=1) and 0-R\'enyi entropy are exceptionally interesting measures of entanglement in the multipartite setting