Other Engineering Commons^™

Crystallization Of Polyamide 66 Copolymers At High Supercoolings, Xiaoping Guan

Doctoral Dissertations

Crystallization kinetics and morphologies of a series of random copolymers of PA 66 (or Nylon 66) have been investigated at high supercoolings. Optical microscopy with rapid cooling apparatus was employed to observe spherulitic morphologies and measure growth rates. Final spherulitic morphologies of PA 66 and copolymers could be changed with increasing supercoolings from impinged spherulites to isolated spherulites with decreasing size until total amorphous.

Spherulite growth results indicated that the rates of crystallization of PA 66 copolymers were reduced with increasing content of comonomer, and crystallization was moved to lower temperatures. The melting temperature, crystallinity, crystal structure and lamellar thickness …

The Effects Of Sediment And Nutrient Loading On Aquatic Organisms In Nails And Ellejoy Creeks, Blount County, Tennessee, Susanna Hannah Sutherland

Masters Theses

The health of an entire ecosystem is influenced by its water supply. Nonpoint source pollution, such as sediments and nutrients, cause impairment of water quality and harm aquatic diversity. This study was designed to assess the impacts of excess sediment and nutrients on aquatic health in the Nails (HUC12, 060102010105) and Ellejoy (HUC 12, 060102010104) Creeks, subwatersheds of the Little River (HUC10, 0601020101) watershed and the Watts Bar Lake watershed (HUC8, 06010201) in Blount County, Tennessee. Previous research has shown a negative correlation between these pollutants and benthic indicator species. In 2002, the 303(d) list indicated that both streams were …

Estimating Cost Growth In Engineering And Schedule Cost Categories Using A Two-Pronged Regression Approach, Chris J. Mcdaniel

Theses and Dissertations

This research confirms the usefulness of the logistic and multiple regression two-step procedure for assessing cost growth in major DoD weapon systems. We compile programmatic data from the Selected Acquisition Reports (SARs) between 1990 and 2002 for programs covering all defense departments. Our analysis concentrates on cost growth in the procurement appropriations of the Engineering and Manufacturing Development phase of acquisitions. We investigate the use of logistic regression in cost growth analysis to predict whether or not cost growth will occur in a program. If applicable, multiple regression is implemented to predict how much cost growth will occur. Our study …

Creating Cost Growth Models For The Engineering And Manufacturing Development Phase Of Acquisition Using Logistic And Multiple Regression, Brandon M. Lucas

Theses and Dissertations

Cost growth remains a concern for cost analysts, program managers, senior DoD decision-makers, Congress, and even the American public. All of these people have a vested interest in the cost of DoD programs and most would like to see those costs decrease; as such, we need additional tools to help combat cost growth. Previous research creates the foundation for the use of a two-step methodology to help predict cost growth, which we follow closely. First, utilizing logistic regression we analyze whether specific program characteristics predict cost growth within the Engineering and Manufacturing Development (EMD) phase for combined RDT&E and procurement …