Formation of giant molecular clouds in global spiral structures: The role of orbital dynamics and cloud-cloud collisions

The different roles played by orbital dynamics and dissipative cloud-cloud collisions in the formation of giant molecular clouds (GMCs) in a global spiral structure are investigated. The interstellar medium (ISM) is simulated by a system of particles, representing clouds, which orbit in a spiral-perturbed, galactic gravitational field. The overall magnitude and width of the global cloud density distribution in spiral arms is very similar in the collisional and collisionless simulations. The results suggest that the assumed number density and size distribution of clouds and the details of individual cloud-cloud collisions have relatively little effect on these features. Dissipative cloud-cloud collisions play an important steadying role for the cloud system's global spiral structure. Dissipative cloud-cloud collisions also damp the relative velocity dispersion of clouds in massive associations and thereby aid in the effective assembling of GMC-like complexes

Sensor-Craft Analytical Certification

This study developed a multi-disciplinary conceptual design of a joined-wing sensor-craft. Initial analysis was conducted using an aluminum model. Linear fully stressed design and flexible aerodynamic trim were used to converge to a minimum weight design that was aerodynamically stable. This optimized design was buckling safe. A similar optimization process using non-linear fully stressed design and flexible aerodynamic trim was conducted. The non- linear structurally deformation was over ten times greater than the linear structural deformation. Again, the model was structurally and aerodynamically optimized. The linear optimization was repeated using a composite structural model incorporating Conformal Load-bearing Antenna Structures. This research demonstrated the importance of considering non- linearity and the coupling of aero dynamic and structural design

Quantum Mechanical Calculations of Monoxides of Silicon Carbide Molecules

Modern semiconductor devices are principally made using the element silicon. In recent years, silicon carbide (SiC), with its wide band-gap, high thermal conductivity, and radiation resistance, has shown prospects as a semiconductor material for use in high temperature and radiation environments such as jet engines and satellites. A limiting factor in the performance of many SiC semiconductor components is the presence of lattice defects formed at oxide dielectric junctions during processing. Recent theoretical work has used small quantum mechanical systems embedded in larger molecular mechanics structures to attempt to better understand SiC surfaces and bulk materials and their oxidation. This research uses quantum mechanical models to calculate geometries and electronic properties of small Si(m)C(n)O molecular clusters of silicon carbide oxides with 0 less than or equal to m, n less than or equal to 4. Calculations are primarily done using Hartree-Fock and Density Functional Theory (DFT) with the B3LYP exchange and correlation functionals. Moller-Plesset Second Order Perturbation (MP2), Configuration Interaction (CI), Multi-Configurational Self-Consistent Field (MCSCF), and Coupled Cluster (CC) are used on the CSi2Q molecule to confirm the accuracy of selected levels of DFT. Molecular properties examined include ground state multiplicity, vibrational modes and frequencies, and geometry for both the neutral and anion, adiabatic and vertical electron affinities, and thermodynamic heats of formation. Qualitative predictions are made regarding the photoelectron spectrum experimentalists may see. Finally, preferred geometries, functional groups, and bonding locations are qualitatively determined. Later research will be able to use these results to study the oxidation of larger SiC structures and surfaces and their defects

Like Fire in Dry Stubble - The Stone Movement 1804-1832 (Part 1)

Roberts, J W. and Roberts, R. L. Jr. (1963) Like Fire in Dry Stubble - The Stone Movement 1804-1832 (Part 1), Restoration Quarterly: Vol. 7 : No. 3. This repository hosts selected Restoration Quarterly articles in downloadable PDF format. For the benefit of users who would like to browse the contents of RQ, we have included all issue covers even when full-text articles from that issue are unavailable. All Restoration Quarterly articles are available in full text in the ATLA Religion Database, available through most university and theological libraries or through your local library’s inter-library loan service