Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

Browse

Filters

20142

Settings

Subject: search.filters.subject.collisions

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    ISOTOPE EFFECTS IN THE STATE-RESOLVED COLLISION DYNAMICS OF HIGHLY EXCITED MOLECULES
    (2014) Echebiri, Geraldine Onyinyechi; Mullin, Amy S; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The importance of highly excited molecules in the fields of combustion and atmospheric chemistry makes it essential to study pathways by which energy is lost from the excited molecule. One such pathway is by inelastic collisions with a bath molecule. In this dissertation, the collisional relaxation of highly excited pyrazine-h4 (Evib = 37900 cm-1) and pyrazine-d4 (Evib = 37900 cm-1) with HCl (300 K) is studied. The outcomes of the inelastic collision studies reveal quantum state-energy gaps of molecules and their intermolecular interactions affect the mechanism and dynamics of collisional energy transfer. The results from collisional relaxation of pyrazine-h4 (Evib = 37900 cm-1) with HCl were compared to those from collisional relaxation of pyrazine-h4 (Evib) with DCl in order to deduce the effects of quantum state-energy gaps on the dynamics of collisional energy transfer. The comparison shows the dynamics for collisional deactivation of pyrazine-h4 (Evib) with HCl and DCl are different, and are possibly due to their intermolecular interactions with pyrazine-h4 (Evib. The data for collisional relaxation of pyrazine-d4 (Evib = 37900 cm-1) with HCl were compared to those for pyrazine-h4 (Evib) + HCl collisions in order to determine the contributions of near-resonant vibrational energies of the collision partners on the collision dynamics. The comparison shows the energy transfer dynamics for collisional quenching of pyrazine-h4 (Evib) and pyrazine-d4 (Evib) with HCl are similar. The similarity in their energy transfer dynamics suggests near-resonance effects are not contributing significantly to the collision dynamics.
  • Thumbnail Image
    Item
    Finite-Discrete Element Method Simulations of Colliding Red Blood Cells
    (2014) Warner, Benjamin; Solares, Santiago D; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The implantation of artificial heart valves can lead to a large decline in red blood cell life. There has been much research in the last few years dedicated to understanding the cause of this decline. One theory states that collisions at large velocity can lead to spontaneous hemolysis which leads to the premature recycling of cells by the body. Currently, there is no suitable method for modeling the complex intersection interaction of blood cells in a computer code. The Finite-Discrete Element Method (FDEM) is a relatively new computer modeling technique that seeks to combine modeling of continuum-based deformability and discontinuum based motion and element interaction. This thesis utilizes FDEM to model the collision of erythrocytes with other erythrocytes. A method of approximating volume of arbitrary discrete element meshes is proposed and tested for general colliding bodies for accuracy. Red Blood cell simulations are presented with experimentally verifiable data to allow for validation of the model. Future steps are presented for further development of themodel for more specialized applications, such as sedimentation and resting contact. The volume-based FDEM method appears to recreate reasonable results for colliding deformable bodies.