Impact of the Synthesis Process on Structure Properties for AFCI Fuel Candidates

Advanced Fuel Cycle Initiative research on transmutation fuels includes mono-nitride ceramic fuel forms, and consists of closely coordinated “hot” actinide and “cold” inert and surrogate fuels work. Matrix and surrogate materials work involves three major components: (1) fuel matrix synthesis and fabrication, (2) fuel performance, and (3) fuel materials modeling. The synthesis and fabrication component supports basic material studies, as well as actinide fuel fabrication work through fuel fabrication process development. Fuel performance studies are examining the tolerance of nitride-type fuel to heavy irradiation damage. The fuel materials simulation work involves both atomistic and continuum scale modeling employing first principles, molecular dynamics, and thermo-chemical calculations. This modeling work is closely integrated with fuel design and experimental work where it provides prediction of phase transformation and stability, reaction kinetics, radiation damage mechanism and tolerance, and fission product retention. Results for fuel fabrication and radiation tolerance studies based on the proposed ZrN fuel matrix material will be reviewed as well as experimental surrogate studies for volatilization and phase stability. The actinide fuel effort at LANL emphasizes synthesis and fabrication of actinide-bearing nitride fuel pellets. These pellets are designed to be inserted into the Advanced Test Reactor and contain varying amounts of Pu, Am, Cm, and Np. Presently, fuel materials simulation work which involves atomistic and continuum scale modeling, molecular dynamics, and thermo-chemical calculations are based on a theoretical understanding of crystal structure and microstructure of inert matrix fuels. This task’s contribution is to provide real structural data on surrogate and radioactive fuels. Crystallographic properties are being determined and nano structures of oxide-based and nitride based fuels, as considered for next generation reactor fuels, are being imaged after applying different synthesis routes. The chemical behavior of the ceramics under repository, reprocessing, and reactor conditions will be examined. Two fully equipped sample preparation laboratories can be taken advantage of, one for the preparation of surrogate fuel, and one for the preparation of radioactive fuel specimens

Photonic currents in driven and dissipative resonator lattices

Arrays of coupled photonic cavities driven by external lasers represent a highly controllable setup to explore photonic transport. In this paper we address (quasi)-steady states of this system that exhibit photonic currents introduced by engineering driving and dissipation. We investigate two approaches: in the first one, photonic currents arise as a consequence of a phase difference of applied lasers and in the second one, photons are injected locally and currents develop as they redistribute over the lattice. Effects of interactions are taken into account within a mean-field framework. In the first approach, we find that the current exhibits a resonant behavior with respect to the driving frequency. Weak interactions shift the resonant frequency toward higher values, while in the strongly interacting regime in our mean-field treatment the effect stems from multiphotonic resonances of a single driven cavity. For the second approach, we show that the overall lattice current can be controlled by incorporating few cavities with stronger dissipation rates into the system. These cavities serve as sinks for photonic currents and their effect is maximal at the onset of quantum Zeno dynamics.Comment: 12 pages, 11 figure

Diversification in Firm Valuation: A Multivariate Copula Approach

We introduce a new discounted cash flow model which adopts the diversification effect of multi-business firms. We face two challenges: One is examining how different diversification extents can affect the firm value due to risk reduction, and the other is modeling segment-specific cash flows and discount rates to reflect the differences in risk and growth characteristics across the different businesses that a firm operates in. Since the co-movement of business segments depends on the state of the economy, we use a multivariate copula approach taking the state-varying dependence of business segments explicitly into account. A high level of a firm's diversification determined by a low dependence between the firm's business segments leads to a lower probability of firm default which results in a higher firm value through reduced bankruptcy costs. We demonstrate this effect by comparing the values of three U.S. firms when modeling independence, dependence with copulas, and perfect dependence between businesses.diversification, firm valuation, dependence modeling, multi-business firm, bankruptcy costs, default probability, copulas, Monte Carlo simulation, discounted cash flow model

Validation Framework for RDF-based Constraint Languages

In this thesis, a validation framework is introduced that enables to consistently execute RDF-based constraint languages on RDF data and to formulate constraints of any type. The framework reduces the representation of constraints to the absolute minimum, is based on formal logics, consists of a small lightweight vocabulary, and ensures consistency regarding validation results and enables constraint transformations for each constraint type across RDF-based constraint languages

Validation Framework for RDF-based Constraint Languages - PhD Thesis Appendix

This paper serves as appendix for the PhD thesis entitled \u27Validation Framework for RDF-based Constraint Languages\u27, submitted to the Department of Economics and Management at the Karlsruhe Institute of Technology (KIT)