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The state-of-the-art in high voltage and high energy density capacitors is dominated by biaxially oriented polypropylene (BOPP), a linear dielectric with electronic polarizability but low dielectric constant (2.2). BOPP provides an energy density of 5 J/cm3 at the breakdown, which occurs at 720 MV/m for films 10 micrometer thick. While there are many approaches to increase the energy, they either offer solutions to specific applications or suffer from fundamental limitations. The principal focus of the dissertation will be centered on rational design for the development of such materials. We study all three verticals of dielectric properties, namely: dielectric permittivity; dielectric loss; and breakdown strength. We then use the information obtained to design a copolymer with enhanced dielectric properties. We start by using simulations and experiments to delineate the mechanism by which the addition of a small number of polar --OH groups to a nonpolar polymer increases the static relative permittivity (or dielectric constant) by a factor of 2. However, the dielectric loss in the frequency regime of interest to power electronics is less than 1%. We observe that a small amount of adsorbed water plays a critical role in this attenuated loss. Further, we study the effect of other polar pendant groups on dielectric properties of polyethylene. By systematically comparing the static relative permittivity of crystalline and semi-crystalline samples we find amorphous phase as the dominant player in these types of material. The constraints provided by the surrounding chains significantly impede dipolar relaxations in the crystalline regions, whereas amorphous chains must sample all configurations to attain their fully isotropic spatial distributions. We also explore the use of the time--temperature superposition (tTS) principle for calculating the dielectric loss of the dielectric materials. This approach helps us explore time scales in simulations which were previously inaccessible using classical MD. We find that the tTS method performed well in determining dielectric losses in the system as long as unrelaxed components are not included in the calculation. This methodology, which provides us with a significantly faster and reliable pathway for calculation of dielectric loss, allows us to identify the role of polar sidegroups on the dielectric loss of common non-polar polymeric dielectrics. Further, we explore the dielectric breakdown mechanism in polymer dielectrics by introducing external electric fields in the materials. Conventionally the prediction of dielectric strength has focused on ground state energy calculation, thus restricting the analysis of the breakdown process to purely electronic in nature. While this provides reasonable predictions for low-temperature systems, we observe that electromechanical breakdown plays a crucial role in the high-temperature regimes. Our simulation results suggest that fracture mechanics drive electromechanical breakdown, which dominates over electronic breakdown at relevant operating temperatures.  Finally, we utilized these fundamental insights into dielectric properties for designing copolymer with enhanced dielectric properties.

The decline in fertility in dairy cows is of international concern. Since 1950, milk production demands have increased while first service rates of conception have decreased. It is unclear why fertility has decreased, however current dairy management practice requires cows to be kept on a tight yearly calving schedule to ensure maximum milk production over the lifetime of the cow. The current postulate suggests that this regime places a high metabolic burden on the cows, which in turn requires the breakdown of tissues such as fat and muscle to provide substrates to meet the increased energy demands of lactation. Immediately after calving, dairy cows enter a state of negative energy balance (EB), as they cannot consume enough energy to sustain lactation. During this period of negative EB, fat is mobilised in the form of non-esterified fatty acids to help supply the body with the extra energy it needs, but fat mobilisation decreases after four weeks while cows remain in a state of negative EB for several more weeks. It is unclear whether or not muscle breakdown occurs and plays a role in the restoration of EB in lactating cows during peak lactation. I hypothesized that the breakdown of muscle does occur in cows during peak lactation, and that it occurs to a greater extent in cows producing higher amounts of milk. Dairy cows from three strains, NZL, NZH and OSH, representing cows with differing milk production abilities (low, intermediate and high, respectively), were studied for 12 weeks postpartum. Blood was drawn at weekly intervals and muscle biopsies taken at -1, 1, 4, 8, and 12 weeks postpartum. Analysis of plasma revealed an increase in the abundance of troponin I-fs (a marker of muscle breakdown) over the period of study, suggesting that breakdown of skeletal muscle was occurring. Real-time polymerase chain reaction analysis showed that expression of the ubiquitin-proteasome (UbP) ligases atrogin-1 (atro1) and muscle ring finger protein 1 (murf1) increased initially, but returned to normal levels by four weeks postpartum. Concentration of mRNA of the lysosomal proteases, cathepsin B, D, H and L, did not change over the period of study. Therefore, the UbP pathway may contribute to the breakdown of muscle detected by troponin I-fs in plasma. Proteins involved in translation initiation were examined by Western blotting. The ratio of phosphorylated over total eIF2alpha and 4E-BP1 remained unchanged throughout the study, indicating that the breakdown of muscle was not a result of decreased protein synthesis. However, there was a greater ratio of phosphorylated to total eIF2alpha in NZL cows compared with NZH and OSH, suggesting that protein synthesis was less overall in NZL cows than other strains. Measurement of myosin heavy chain composition indicated there was no change in the abundance of type I and type IIx muscle fibres and plasma myostatin levels did not change over the period of study. However, the OSH cows had less myostatin in their plasma than the NZL and NZH cows, suggesting that there may be inhibition of muscle growth occurring in this strain. The results of this study suggest that breakdown of muscle could be important in restoring the EB in high-producing dairy cows during peak lactation. Upregulation of the UbP pathway during the first four weeks of lactation may contribute to this muscle breakdown. However, it remains unclear what processes then continue to regulate breakdown of skeletal muscle to maintain the elevated abundance of troponin I-fs in plasma from four to 12 weeks postpartum in lactating dairy cows.

Melvin A. Herlin [and] Sanborn C. Brown. / "July 30, 1948." / Includes bibliographical references. / Army Signal Corps No. W-36-039 sc 32037.

M.A. Herlin and S.C. Brown. / "June 14, 1948." / Includes bibliographical references. / Army Signal Corps Contract W-36-039 sc-32037.

Diamond interchanges and their associated ramps are where the surface street arterial system and the freeway system interface. Historically, these two elements of the system have been operated with little or no coordination between the two. Therefore, there is a lack of both analysis tools and operational strategies for considering them as an integrated system. One drawback of operating the ramp-metering system and the diamond interchange system in isolation is that traffic from the ramp, particularly if it is metered, can spill back into the diamond interchange, causing both congestion and safety concerns at the diamond interchange. While flushing the ramp queues by temporarily suspending ramp metering has been the primary strategy for preventing queue spillback, it can result in freeway system breakdown, which would affect the entire system's efficiency. The aim of this research was to develop operational strategies for managing an integrated diamond interchange ramp-metering system (IDIRMS). Enhanced modeling methodologies were developed for an IDIRMS. A computer model named DRIVE (Diamond Interchange and Ramp Metering Integration Via Evaluation) was developed, which was characterized as a mesoscopic simulation and analysis model. DRIVE incorporated the enhanced modeling methodologies developed in this study and could be used to perform system analysis for an IDIRMS given a set of system input parameters and variables. DRIVE was validated against a VISSIM microscopic simulation model, and general agreement was found between the two models. System operational characteristics were investigated using DRIVE to gain a better understanding of the system features. Integrated control strategies (ICS) were developed based on the two commonly used diamond interchange phasing schemes, basic three-phase and TTI four-phase. The ICS were evaluated using VISSIM microscopic simulation under three general traffic demand scenarios: low, medium, and high, as characterized by the volume-to-capacity ratios at the metered ramps. The results of the evaluation indicate that the integrated operations through an adaptive signal control system were most effective under the medium traffic demand scenario by preventing or delaying the onset of ramp-metering queue flush, thereby minimizing freeway breakdown and system delays.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--California Polytechnic State University, 2010. / Mode of access: Internet. Title from PDF title page; viewed on Jan. 21, 2010. Major professor: John Oliver. "Presented to the Electrical Engineering Department faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the Master of Science degree in Electrical Engineering." "January 2010." Includes bibliographical references (p. 119-121).

Thesis--Auburn University, 2010. / Abstract. Includes bibliographic references (p.55-56).

Diamond interchanges and their associated ramps are where the surface street arterial system and the freeway system interface. Historically, these two elements of the system have been operated with little or no coordination between the two. Therefore, there is a lack of both analysis tools and operational strategies for considering them as an integrated system. One drawback of operating the ramp-metering system and the diamond interchange system in isolation is that traffic from the ramp, particularly if it is metered, can spill back into the diamond interchange, causing both congestion and safety concerns at the diamond interchange. While flushing the ramp queues by temporarily suspending ramp metering has been the primary strategy for preventing queue spillback, it can result in freeway system breakdown, which would affect the entire system's efficiency. The aim of this research was to develop operational strategies for managing an integrated diamond interchange ramp-metering system (IDIRMS). Enhanced modeling methodologies were developed for an IDIRMS. A computer model named DRIVE (Diamond Interchange and Ramp Metering Integration Via Evaluation) was developed, which was characterized as a mesoscopic simulation and analysis model. DRIVE incorporated the enhanced modeling methodologies developed in this study and could be used to perform system analysis for an IDIRMS given a set of system input parameters and variables. DRIVE was validated against a VISSIM microscopic simulation model, and general agreement was found between the two models. System operational characteristics were investigated using DRIVE to gain a better understanding of the system features. Integrated control strategies (ICS) were developed based on the two commonly used diamond interchange phasing schemes, basic three-phase and TTI four-phase. The ICS were evaluated using VISSIM microscopic simulation under three general traffic demand scenarios: low, medium, and high, as characterized by the volume-to-capacity ratios at the metered ramps. The results of the evaluation indicate that the integrated operations through an adaptive signal control system were most effective under the medium traffic demand scenario by preventing or delaying the onset of ramp-metering queue flush, thereby minimizing freeway breakdown and system delays.