Finite element modeling of electromagnetic fields and waves using NASTRAN

The various formulations of Maxwell's equations are reviewed with emphasis on those formulations which most readily form analogies with Navier's equations. Analogies involving scalar and vector potentials and electric and magnetic field components are presented. Formulations allowing for media with dielectric and conducting properties are emphasized. It is demonstrated that many problems in electromagnetism can be solved using the NASTRAN finite element code. Several fundamental problems involving time harmonic solutions of Maxwell's equations with known analytic solutions are solved using NASTRAN to demonstrate convergence and mesh requirements. Mesh requirements are studied as a function of frequency, conductivity, and dielectric properties. Applications in both low frequency and high frequency are highlighted. The low frequency problems demonstrate the ability to solve problems involving media inhomogeneity and unbounded domains. The high frequency applications demonstrate the ability to handle problems with large boundary to wavelength ratios

Response of composite plates subjected to acoustic loading

The objectives of the project were to investigate numerical methodology for the determination of narrowband response in the geometrically nonlinear regime, to determine response characteristics for geometrically nonlinear plates subjected to random loading and to compare the predictions with experiments to be performed at NASA-Langley. The first two objectives were met. The response of composite plates subjected to both narrowband and broadband excitation were studied and the results are presented and discussed

Freerider or Strategic Balancer? Austria vis-à-vis NATO and Russia; US - perspective on Austrian neutrality politics

Russia's invasion of Ukraine on 24 February 2022 highlighted the fragility of peace and security in Europe. The resurgence of war in Europe prompted a reassessment of the security postures of traditionally neutral countries. Norms on military spending and assistance have been shattered, leading to Finland and Sweden reversing decades of military non-alignment to join NATO. Even Switzerland is eyeing a strategic overhaul and is considering joint exercises with NATO (Revill, 2022). Despite Sweden and Finland’s decision to join NATO Austria remains committed to neutrality. The public debate on Austria's strategic culture has remained largely the same and policymakers in Vienna have not changed their stance on NATO. Russia’s war in Ukraine has underscored Austria's need to reevaluate its policy of neutrality and strategic approach vis-a-vis NATO and Russia

Stability and electronic structure of the complex K2_2PtCl6_6 structure-type hydrides

The stability and bonding of the ternary complex K$_2$PtCl$_6$ structure hydrides is discussed using first principles density functional calculations. The cohesion is dominated by ionic contributions, but ligand field effects are important, and are responsible for the 18-electron rule. Similarities to oxides are discussed in terms of the electronic structure. However, phonon calculations for Sr$_2$RuH$_6$ also show differences, particularly in the polarizability of the RuH$_6$ octahedra. Nevertheless, the yet to be made compounds Pb$_2$RuH$_6$ and Be$_2$FeH$_6$ are possible ferroelectrics. The electronic structure and magnetic properties of the decomposition product, FeBe$_2$ are reported. Implications of the results for H storage are discussed

Measurement and Analysis of Oxygen/Nitrogen/5A-Zeolite Adsorption Equilibria for Air Separation

Multicomponent adsorption equilibrium data are essential for the reliable design of processes and equipment for gas separation by adsorption. We discuss techniques for the measurement and analysis of multicomponent adsorption equilibrium data, and present a comprehensive set of equilibrium data for the adsorption of oxygen and nitrogen on 5A-zeolite