A Polarimetric Phased Array Antenna for E-SAR in L-Band

The design of a new L-band antenna for DLR’s airborne synthetic aperture radar system (E-/F-SAR) is presented. Beside operations in L-band new components for a system upgrade were developed. These components are intro-duced. Special interest of this paper is the development of the dual-polarized L-Band antenna with enhanced bandwidth of 150MHz. The antenna feed network is equipped with 2bit hybrid phase shifters to steer the beam between 25° and 40° in elevation. For mounting the antenna at the fuselage of a Dornier Do 228-212 aircraft a rack is described to house several antenna configuration

Positron Fraction in the CMSSM

A fit to the present data on the cosmic ray positron fraction can be considerably improved,if in addition to the positron production by nuclear interactions in the universe the possible contribution from supersymmetric dark matter annihilation is taken into account. We scan over the complete SUSY parameter space of the Constrained Minimal Supersymmetric Model (CMSSM) and find that in the acceptable regions the neutralino annihilation into b-bbar quark pairs is the dominant channel with hard positrons emerging from the semileptonic decays of the B-mesons.Comment: 6 pages, Latex, Proceedings of the 4th International Workshop on Identification of Dark Matter (idm2002), York, England, 2-6 September, 200

Change of the congruence canonical form of 2-by-2 and 3-by-3 matrices under perturbations and bundles of matrices under congruence

We construct the Hasse diagrams $G_2$ and $G_3$ for the closure ordering on the sets of congruence classes of $2\times 2$ and $3\times 3$ complex matrices. In other words, we construct two directed graphs whose vertices are $2\times 2$ or, respectively, $3\times 3$ canonical matrices under congruence and there is a directed path from $A$ to $B$ if and only if $A$ can be transformed by an arbitrarily small perturbation to a matrix that is congruent to $B$. A bundle of matrices under congruence is defined as a set of square matrices $A$ for which the pencils $A+\lambda A^T$ belong to the same bundle under strict equivalence. In support of this definition, we show that all matrices in a congruence bundle of $2\times 2$ or $3\times 3$ matrices have the same properties with respect to perturbations. We construct the Hasse diagrams $G_2^{\rm B}$ and $G_3^{\rm B}$ for the closure ordering on the sets of congruence bundles of $2\times 2$ and, respectively, $3\times 3$ matrices. We find the isometry groups of $2\times 2$ and $3\times 3$ congruence canonical matrices.Comment: 34 page

Extrinsic Infrastructure Calibration Using the Hand-Eye Robot-World Formulation

We propose a certifiably globally optimal approach for solving the hand-eye robot-world problem supporting multiple sensors and targets at once. Further, we leverage this formulation for estimating a geo-referenced calibration of infrastructure sensors. Since vehicle motion recorded by infrastructure sensors is mostly planar, obtaining a unique solution for the respective hand-eye robot-world problem is unfeasible without incorporating additional knowledge. Hence, we extend our proposed method to include a-priori knowledge, i.e., the translation norm of calibration targets, to yield a unique solution. Our approach achieves state-of-the-art results on simulated and real-world data. Especially on real-world intersection data, our approach utilizing the translation norm is the only method providing accurate results.Comment: Accepted at 2023 IEEE Intelligent Vehicles Symposiu

Nouvelles découvertes de Lycopodes aplatis (Diphasiastrum) dans l’Odenwald de Hesse

In den Jahren 2003 und 2004 gelangen Nachweise mehrerer Flachbärlapp- Arten (Diphasiastrum) im hessischen Odenwald bei Beerfelden und Olfen. Von herausragender Bedeutung ist der Fund von D. oellgaardii, welches seit rund 50 Jahren in Hessen als erloschen galt. Daneben wurden D. complanatum und D. tristachyum an je einer Lokalität neu entdeckt. Die Diphasiastrum-Arten besiedeln an den Wuchsorten bei Beerfelden und Olfen anthropogene Sekundärstandorte (Skipiste oder Straßenböschung). Syntaxonomisch lassen sich die Bestände innerhalb der Ordnung Ulicetalia minoris zum Genisto pilosae-Callunetum oder zu einer Deschampsia-flexuosa-Vaccinium-myrtillus- Gesellschaft stellen. An beiden Wuchsorten wachsen die Flachbärlappe auf stark sauren, mäßig frischen, sandigen Lehmböden. Die Wuchsorte erhalten volle Freilandhelligkeit oder sind mäßig beschattet. Neben populationsbiologischen Parametern wie Anzahl der Sprosse und Fertilität werden Daten zur Gefährdung der Bestände genannt. Eine Neueinstufung für zwei der drei beobachteten Diphasiastrum-Arten in der Roten Liste für Hessen wird vorgeschlagen.Between 2003 and 2004 new records of several Diphasiastrum species in the Hesse Odenwald region near Beerfelden and Olfen were made. Especially important is the record of D. oellgaardii which was assumed to be extinct in Hesse since 50 years. Beside this, D. complanatum and D. tristachyum were recorded at one new site each. The growing sites near Beerfelden and Olfen are secondary habitats of anthropogeneous origin (a skiing track and a road slope). The respective plant communities belong to the order Ulicetalia minoris (Genisto pilosae-Callunetum and Deschampsia flexuosa-Vaccinium myrtillus community). At both sides the Diphasiastrum species are growing on strongly acidic, moderately moist and sandy to loamy soil. One of the growing sites is full sunny, the other is half shaded. For each population, size, degree of fertility and information about threat factors are given. Suggestions for a new threat assessment for the Red Data Book of Hesse were made for two of the three observed Diphasiastrum species.Dans les années 2003–2004, plusieurs espèces de Lycopodes aplatis ont été découvertes dans l’Odenwald près de Beerfelden et Olfen. La présence de D. oellgaardii est d’une signification éminente car il était réputé comme disparu de la Hesse depuis bien 50 ans. En outre D. complanatum et D. tristachyum ont été découverts chacun dans un lieu différent. Les espèces de Diphasiastrum peuplent des sites secondaires anthropogènes (pistes de ski, talus en bordure des routes) près de Beerfelden et Olfen. Du point de vue syntaxonomique, la végétation peut être classée dans l’ordre des Ulicetalia minoris au Genisto pilosae-Callunetum ou à la communauté de Deschampsia flexuosa-Vaccinium myrtillus. Dans les deux stations, les Lycopodes aplatis poussent sur des sols sableux argileux fortement acides, moyennement frais. Les stations sont ensoleillées ou peu ombragées. A côté de paramètres biologiques de population tels que nombre de pieds et fertilité, des indications de menace de disparition sont présentées. Une nouvelle classification dans la Liste rouge de Hesse pour 2 des 3 espèces de Diphasiastrum est proposée