Adaptive Intelligent Tutoring System for learning Computer Theory

In this paper, we present an intelligent tutoring system developed to help students in learning Computer Theory. The Intelligent tutoring system was built using ITSB authoring tool. The system helps students to learn finite automata, pushdown automata, Turing machines and examines the relationship between these automata and formal languages, deterministic and nondeterministic machines, regular expressions, context free grammars, undecidability, and complexity. During the process the intelligent tutoring system gives assistance and feedback of many types in an intelligent manner according to the behavior of the student. An evaluation of the intelligent tutoring system has revealed reasonably acceptable results in terms of its usability and learning abilities are concerned

Nuclear Magnetic Resonance and Impedance Spectroscopy Studies on Lithium Ion Diffusion in γ-LiAlO2

In this work we show conductivity spectra of γ-LiAlO2 single crystals purchased from CrysTec and microcrystalline powder prepared by solid state synthesis

Multinuclear Solid-State NMR Study of Local Structure and Dynamics in Li0.7Nb3S4

The present work focuses on channel-structured Li0.7Nb3S4, where, among others, the question of the dimensionality of the diffusion pathway arises

Unravelling ultraslow lithium-ion diffusion in γ-LiAlO2 : experiments with tracers, neutrons, and charge carriers

Lithium aluminum oxide (γ-LiAlO2) has been discussed and used for various applications, e.g., as electrode coating, membrane, or tritium breeder material. Although lithium-ion diffusion in this solid is essential for these purposes, it is still not sufficiently understood on the microscopic scale. Herein, we not only summarize and assess the available studies on diffusion in different crystalline forms of γ-LiAlO2, but also complement them with tracer-diffusion experiments on (001)- and conductivity spectroscopy on (100)-oriented single crystals, yielding activation energies of 1.20(5) and 1.12(1) eV, respectively. Scrutinous crystal-chemical considerations, Voronoi–Dirichlet partitioning, and Hirshfeld surface analysis are employed to identify possible diffusion pathways. The one-particle potential, as derived from high-temperature powder neutron diffraction data presented as well, reveals the major path to be strongly curved and to run between adjacent lithium positions with a migration barrier of 0.72(5) eV. This finding is substantiated by comparison with recently published computational results. For the first time, a complete model for lithium-ion diffusion in γ-LiAlO2, consistent with all available data, is presented.DFG, FOR 1277, Mobilität von Lithiumionen in Festkörpern (molife

Lithium diffusion pathways in metastable ramsdellite like Li2Ti3O7 from high temperature neutron diffraction

Ramsdellite-like Li2Ti3O7 is an excellent, strongly anisotropic lithium-ion conductor with various proposed applications in energy storage and lithium processing. Diffusion pathways have not yet been thoroughly studied, in spite of their importance for these purposes; even the precise crystal structure of this material is a subject of ongoing discussion. Herein, we use variable-temperature neutron diffraction in the metastability range of ramsdellite-like Li2Ti3O7 to probe the nontrivial lithium-ion distribution. Refinement with anisotropic displacement parameters including anharmonic terms identifies the room-temperature structure as statically disordered snapshot of the dynamic behavior at synthesis temperature. Mapping of scattering-length density, reconstructed using maximum-entropy methods (MEM), shows the signature of partial relaxation and activation of lithium movement with increasing temperature. Scrutinous topological analyses of procrystal voids and Voronoi–Dirichlet partitioning (VDP) reveal lithium diffusion along ribbons in the interstitial channels as the major and diffusion through framework vacancies as the most probable minor mechanism. By rationalizing former empirical results, we provide deeper insight into this paradigmatic example of strongly anisotropic lithium-ion conductors.DFG, FOR 1277, Mobilität von Lithiumionen in Festkörpern (molife

Synthesis, Crystal Structure and Magnetic Properties of Bixbyite-type Vanadium Oxide Nitrides

Ammonolysis of vanadium sulfide leads to the formation of bixbyite-type vanadium oxide nitrides. Small amounts of nitrogen incorporated in the structure result in the stabilization of the bixbyite type not known for vanadium oxides. The crystal structure was investigated using X-ray diffraction and X-ray absorption spectroscopy. At temperatures above 550 °C the powders decompose to corundumtype V2O3 containing no detectable amount of nitrogen. Below 39 K magnetic ordering is observed

Nuclear Magnetic Resonance and Impedance Spectroscopy Studies on Lithium Ion Diffusion in γ-LiAlO2

In this work we show conductivity spectra of γ-LiAlO2 single crystals purchased from CrysTec and microcrystalline powder prepared by solid state synthesis

Multinuclear Solid-State NMR Study of Local Structure and Dynamics in Li0.7Nb3S4

The present work focuses on channel-structured Li0.7Nb3S4, where, among others, the question of the dimensionality of the diffusion pathway arises