Modeling and Analysis of a Three-Terminal-Memristor-Based Conservative Chaotic System

In this paper, a three-terminal memristor is constructed and studied through changing dual-port output instead of one-port. A new conservative memristor-based chaotic system is built by embedding this three-terminal memristor into a newly proposed four-dimensional (4D) Euler equation. The generalized Hamiltonian energy function has been given, and it is composed of conservative and non-conservative parts of the Hamiltonian. The Hamiltonian of the Euler equation remains constant, while the three-terminal memristor’s Hamiltonian is mutative, causing non-conservation in energy. Through proof, only centers or saddles equilibria exist, which meets the definition of the conservative system. A non-Hamiltonian conservative chaotic system is proposed. The Hamiltonian of the conservative part determines whether the system can produce chaos or not. The non-conservative part affects the dynamic of the system based on the conservative part. The chaotic and quasiperiodic orbits are generated when the system has different Hamiltonian levels. Lyapunov exponent (LE), Poincaré map, bifurcation and Hamiltonian diagrams are used to analyze the dynamical behavior of the non-Hamiltonian conservative chaotic system. The frequency and initial values of the system have an extensive variable range. Through the mechanism adjustment, instead of trial-and-error, the maximum LE of the system can even reach an incredible value of 963. An analog circuit is implemented to verify the existence of the non-Hamiltonian conservative chaotic system, which overcomes the challenge that a little bias will lead to the disappearance of conservative chaos.

Predicting Math Student Success in the Initial Phase of College With Sparse Information Using Approaches From Statistical Learning

In math teacher education, dropout research relies mostly on frameworks which carry out extensive variable collections leading to a lack of practical applicability. We investigate the completion of a first semester course as a dropout indicator and thereby provide not only good predictions, but also generate interpretable and practicable results together with easy-to-understand recommendations. As proof-of-concept, a sparse feature space together with machine learning methods is used for prediction of dropout, wherein the most predictive features have to be identified. Interpretability can be reached by introducing risk groups for the students. Implications for interventions are discussed.

Density Functional Theory; a New Route for Structural and Thermodynamic Parameters Calculations

Structural and thermodynamic parameters of the studied virgin polymeric matrices poly e-caprolactone (PCL), Chitosan (Chi) and their polymer blend were investigated using theoretical density functional theory (DFT). Thermodynamic functions were calculated based on vibrational frequencies and optimized geometrical coordinates in the temperature range 25-1000 °K which cannot be amended easily. Calculated free energy was found to be convex in terms of extensive variable and concave in terms of intensive ones.

Comparative analysis of the genome regions associated with virulence in original classic and El Tor Biovars of Vibrio cholerae strains

The comparative analysis of the genome regions associated with virulence in various V. cholerae strains: classical biovar, as well as typical and genetically altered strains of El Tor biovar was performed with the use of PCR assays and fragment sequencing. V. cholerae classical biovar genome was demonstrated to be more stable in comparison with the same in V. cholerae El Tor biovar. Within the genome of El Tor vibrios there were identified extensive variable regions carrying pathogenicity genes. It was also found that unlike classical cholera vibrios, in the V. cholerae El Tor genome there is absent CRISPR-system limiting horizontal transfer of the genes. The obtained data concerning these structural peculiarities of V. cholerae El Tor genome may be used in the delivery of the new generations of gene-diagnostic preparations and for improvement of molecular-epidemiological monitoring in case of cholera.

Novel synthesis of 2-naphthol Mannich bases and their NMR behaviour

A novel two-step procedure involving the formation of 1-arylidene-2-tetralones from 2-tetralone and subsequent Michael addition of a cyclic secondary amine on the alkenone followed by in situ aerial oxidation was developed to produce 2-naphthol Mannich bases. A simple microwave-assisted one-pot synthesis of 2-naphthol Mannich bases was also carried out under solvent-free conditions from 2-naphthol and corresponding aldehydes and amines in the presence of p-toluenesulfonic acid. The compounds of this series displayed interesting NMR behaviour. Extensive variable-temperature NMR investigations, including HSQC experiments, are herein reported. NMR results on the conformation in solution phase were found to be consistent with the X-ray crystal structure in the solid state.Key words: Mannich bases, microwave-assisted Mannich reaction, temperature-variable NMR spectroscopy, NMR dynamics, X-ray crystallography.

The Influence of a Variable Capacity Turbine in the Performance of a Variable Cycle Engine

An investigation was conducted to examine the effects of a variable flow low pressure turbine on a variable cycle engine’s performance. One of the greatest challenges, during the design of a variable cycle engine is how to optimise the various cycles and then to match then to the capabilities of the engine components, the use of extensive variable geometry is required to achieve this. A method of matching variable cycle engines that was developed Cranfield University was adapted to cater for the use of a variable flow low pressure turbine. It was discovered that the implementation of variable geometry within the low pressure turbine could significantly reduce the requirements for variable geometry within the compressor system, at the cost of replacing well proven compressor variable geometry with high risk technology within the LP turbine. Utilising the variable flow turbine to expand the bypass ratio range of the engine was studied. Increasing the LPM bypass ratio to 1.1 and 1.2 yielded SFC reductions of 3% and 5% respectively, reducing the bypass ratio of the HPM to 0.1 gave a 20% increase in specific thrust. It was found that the performance benefits gained from expanding the bypass ratio are large enough to warrant further investigation into this concept.