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: Computer science & Context (language use). 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.

Runtime Verification for LTL and TLTL

Abstract: This article studies runtime verification of properties expressed either in lineartime temporal logic (LTL) or timed lineartime temporal logic (TLTL). It classifies runtime verification in identifying its distinguishing features to model checking and testing, respectively. It introduces a three-valued semantics (with truth values true, false, inconclusive) as an adequate interpretation as to whether a partial observation of a running system meets an LTL or TLTL property.For LTL, a conceptually simple monitor generation procedure is given, which is optimal in two respects: First, the size of the generated deterministic monitor is minimal, and, second, the monitor identifies a continuously monitored trace as either satisfying or falsifying a property as early as possible. The feasibility of the developed methodology is demontrated using a collection of real-world temporal logic specifications. Moreover, the presented approach is related to the properties monitorable in general and is compared to existing concepts in the literature. It is shown that the set of monitorable properties does not only encompass the safety and cosafety properties but is strictly larger.For TLTL, the same road map is followed by first defining a three-valued semantics. The corresponding construction of a timed monitor is more involved, yet, as shown, possible.

Synthesis of cubic silicon nitride

Abstract: Silicon nitride (Si3N4) is used in a variety of important technological applications The high fracture toughness, hardness and wear resistance of Si3N4-based ceramics are exploited in cutting tools and anti-friction bearings1; in electronic applications, Si3N4 is used as an insulating, masking and passivating material2 Two polymorphs of silicon nitride are known, both of hexagonal structure: α- and β-Si3N4 Here we report the synthesis of a third polymorph of silicon nitride, which has a cubic spinel structure This new phase, c-Si3N4, is formed at pressures above 15 GPa and temperatures exceeding 2,000 K, yet persists metastably in air at ambient pressure to at least 700 K First-principles calculations of the properties of this phase suggest that the hardness of c-Si3N4 should be comparable to that of the hardest known oxide (stishovite3, a high-pressure phase of SiO2), and significantly greater than the hardness of the two hexagonal polymorphs

FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2

Abstract: In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today’s technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics.

Chiral symmetry restoration and dileptons in relativistic heavy ion collisions

Abstract: The current theoretical status in the analysis and interpretation of low-mass dilepton measurements in (ultra-) relativistic heavy-ion experiments is reviewed. Special emphasis is put on potential signals of (partial) restoration of dynamically broken chiral symmetry in a hot and dense hadronic medium. It follows from chiral symmetry alone that parity partners of hadronic correlation functions must become identical when the symmetry is restored. The assessment of medium effects in the vector channel, which governs the dilepton production, thus necessitates a simultaneous treatment of the vector and axialvector degrees of freedom. While significant progress in this respect has been made some open questions remain in establishing a rigorous link in the mass region below 1 GeV. From the present calculations a suggestive 'quark-hadron duality' emerges near the phase boundary. It implies substantial medium effects in the dilepton signal from the hadronic phase which smoothly matches a perturbative description within the plasma phase.

Nature of the Band Gap of In2O3 Revealed by First-Principles Calculations and X-Ray Spectroscopy

Abstract: Bulk and surface sensitive x-ray spectroscopic techniques are applied in tandem to show that the valence band edge for In2O3 is found significantly closer to the bottom of the conduction band than expected on the basis of the widely quoted bulk band gap of 3.75 eV. First-principles theory shows that the upper valence bands of In2O3 exhibit a small dispersion and the conduction band minimum is positioned at Gamma. However, direct optical transitions give a minimal dipole intensity until 0.8 eV below the valence band maximum. The results set an upper limit on the fundamental band gap of 2.9 eV.