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.

Understanding the trend in the Curie temperatures of Co2-based Heusler compounds: Ab initio calculations

Abstract: The Curie temperatures for the Heusler compounds Co{sub 2}TiAl, Co{sub 2}VGa, Co{sub 2}VSn, Co{sub 2}CrGa, Co{sub 2}CrAl, Co{sub 2}MnAl, Co{sub 2}MnSn, Co{sub 2}MnSi, and Co{sub 2}FeSi are determined ab initio from the electronic structure obtained with the local-density functional approximation and/or the generalized gradient approximation. Frozen spin spirals are used to model the excited states needed to evaluate the spherical approximation for the Curie temperature. The spherical approximation is found to describe the experimental Curie temperatures very well which, for the compounds selected, extend over the range from 95 to 1100 K; as a function of the valence electron count, they show an approximately linear trend which finds an explanation by our calculations.

On the infrared behavior of Landau gauge Yang-Mills theory

Abstract: We discuss the properties of ghost and gluon propagators in the deep infrared momentum region of Landau gauge Yang-Mills theory. Within the framework of Dyson-Schwinger equations and the functional renormalization group we demonstrate that it is only a matter of infrared boundary conditions whether infrared scaling or decoupling occurs. We argue that the second possibility is at odds with global BRST symmetry in the confining phase. For this purpose we improve upon existing truncation schemes in particular with respect to transversality and renormalization.

Market-based transmission expansion planning

Abstract: Restructuring and deregulation has exposed transmission planner to new objectives and uncertainties. Therefore, new criteria and approaches are needed for transmission planning in deregulated environments. A new market-based approach for transmission planning in deregulated environments is presented in this paper. The main contribution of this research is: i) introducing a new probabilistic tool, named probabilistic locational marginal prices, for computing the probability density functions of nodal prices; ii) defining new market-based criteria for transmission expansion planning in deregulated environments; and iii) presenting a new approach for transmission expansion planning in deregulated environments using the above tool and criteria. The advantages of this approach are: i) it encourages and facilitates competition among all participants; ii) it provides nondiscriminatory access to cheap generation for all consumers; iii) it considers all random and nonrandom power system uncertainties and selects the final plan after risk assessment of all solutions; and iv) it is value based and considers investment cost, operation cost, congestion cost, load curtailment cost, and cost caused by system unreliability. The presented approach is applied to IEEE 30-bus test system.

Mossbauer mineralogy of rock, soil, and dust at Meridiani Planum, Mars: Opportunity's journey across sulfate-rich outcrop, basaltic sand and dust, and hematite lag deposits

Abstract: Additonal co-authors: P Gutlich, E Kankeleit, T McCoy, DW Mittlefehldt, F Renz, ME Schmidt, B Zubkov, SW Squyres, RE Arvidson