Technische Universität Darmstadt

About: Technische Universität Darmstadt is a education organization based out in Darmstadt, Germany. It is known for research contribution in the topics: Neutron & Finite element method. The organization has 17316 authors who have published 40619 publications receiving 937916 citations. The organization is also known as: Darmstadt University of Technology & University of Darmstadt.

Similarity-transformed chiral NN + 3N interactions for the ab initio description of 12C and 16O.

Abstract: We present first ab initio no-core shell model (NCSM) calculations using similarity renormalization group (SRG) transformed chiral two-nucleon ($NN$) plus three-nucleon ($3N$) interactions for nuclei throughout the $p$-shell, particularly $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$. By introducing an adaptive importance truncation for the NCSM model space and an efficient $JT$-coupling scheme for the $3N$ matrix elements, we are able to surpass previous NCSM studies including $3N$ interactions. We present ground and excited states in $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ for model spaces up to ${N}_{\mathrm{max} }=12$ including full $3N$ interactions. We analyze the contributions of induced and initial $3N$ interactions and probe induced $4N$ terms through the sensitivity of the energies on the SRG flow parameter. Unlike for light $p$-shell nuclei, SRG-induced $4N$ contributions originating from the long-range two-pion terms of the chiral $3N$ interaction are sizable in $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$.

Preparation and enhanced electrical properties of grain-oriented (Bi1/2Na1/2)TiO3-based lead-free incipient piezoceramics

Abstract: (Bi 1/2 Na 1/2 )TiO 3 (BNT) based lead-free incipient piezoceramics are promising candidates for actuator applications due to their giant electromechanical strains originating from the reversible relaxor-ferroelectric phase transition. To decrease the electric field required for this large strain, the templated grain growth method was employed to prepare 〈1 0 0〉 oriented 0.91Bi 1/2 Na 1/2 TiO 3 –0.06BaTiO 3 –0.03AgNbO 3 piezoceramics using plate-like BNT templates. Textured samples provided a high unipolar strain of 0.38% and a corresponding large signal piezoelectric coefficient, d 33 ∗ of 766 pm/V at 5 kV/mm, which are 78% higher than the values of the randomly oriented ones. The enhanced electric-field-induced strain at relatively lower field was attributed primarily to the facilitated phase-transition to form a long range ferroelectric order along the 〈1 0 0〉 direction. It was also found that the textured piezoceramics exhibited significantly reduced frequency dependence in the unipolar strain behavior at room temperature, resulting from the decreased electric field required for the relaxor-ferroelectric phase transition.

Cryptology and network security: 11th international conference, CANS 2012, Darmstadt, Germany, December 12-14, 2012 : proceedings

Abstract: This book constitutes the refereed proceedings of the 11th International Conference on Cryptology and Network Security, CANS 2012, held in Darmstadt, Germany, in December 2012. The 22 revised full papers, presented were carefully reviewed and selected from 99 submissions. The papers are organized in topical sections on cryptanalysis; network security; cryptographic protocols; encryption; and s-box theory.