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Dynamics and Dynamical Systems Commons™

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Full-Text Articles in Dynamics and Dynamical Systems

Coupling Methylammonium And Formamidinium Cations With Halide Anions: Hybrid Orbitals, Hydrogen Bonding, And The Role Of Dynamics, Chinnathambi Kamal, Dirk Hauschild, Linsey Seitz, Ralph Steininger, Wanli Yang, Clemens Heske, Lothar Weinhardt, Michael Odelius Nov 2021

Coupling Methylammonium And Formamidinium Cations With Halide Anions: Hybrid Orbitals, Hydrogen Bonding, And The Role Of Dynamics, Chinnathambi Kamal, Dirk Hauschild, Linsey Seitz, Ralph Steininger, Wanli Yang, Clemens Heske, Lothar Weinhardt, Michael Odelius

Chemistry and Biochemistry Faculty Research

The electronic structures of four precursors for organic-inorganic hybrid perovskites, namely, methylammonium chloride and iodide, as well as formamidinium bromide and iodide, are investigated by X-ray emission (XE) spectroscopy at the carbon and nitrogen K-edges. The XE spectra are analyzed based on density functional theory calculations. We simulate the XE spectra at the Kohn-Sham level for ground-state geometries and carry out detailed analyses of the molecular orbitals and the electronic density of states to give a thorough understanding of the spectra. Major parts of the spectra can be described by the model of the corresponding isolated organic cation, whereas high-emission …


Experimental And Finite Element Analysis Of Preloaded Bolted Joints Under Impact Loading, Brendan O'Toole, Kumarswamy Karpanan, Masoud Feghhi May 2006

Experimental And Finite Element Analysis Of Preloaded Bolted Joints Under Impact Loading, Brendan O'Toole, Kumarswamy Karpanan, Masoud Feghhi

Mechanical Engineering Faculty Research

One of the primary parameters in analyzing bolted joints is preload in the bolt. We have considered several possible preload modeling techniques to analyze the effect of preload on the dynamic response of the bolted joints. Five different methods of applying preload in the nonlinear finite element analysis are evaluated. These methods are “force on bolt and nut”, “force on bolt shank”, “interference fit”, “thermal gradient” and “initial stress method”. Explicit and implicit analyses are used for transient response and preload generation in bolt respectively. Time history and shock response spectrum are used to compare experimental and simulation results. Simulation …


Modeling, Optimization, And Flow Visualization Of Chemical Etching Process In Niobium Cavities, Sathish K. Subramanian May 2004

Modeling, Optimization, And Flow Visualization Of Chemical Etching Process In Niobium Cavities, Sathish K. Subramanian

UNLV Theses, Dissertations, Professional Papers, and Capstones

Niobium cavities are important component of the linear accelerators. Researchers have concluded that buffered chemical polishing on the inner surface of the cavity improves its performance. However the mechanism of chemical polishing is not well understood. A finite element computational fluid dynamics (CFD) model was developed to simulate the fluid flow characteristics of chemical etching process inside the cavity. The CFD model is then used to optimize the baffle design. The analysis confirmed the observation of other researchers that the iris section of the cavity received more etching than the equator regions. The baffle, which directs flow towards the walls …