Development of thermally stable phosphonitrile elastomers for advanced aerospace structures

Attempts to prepare low molecular weight, curable poly-(fluoroalkoxyphosphazenes) have been successful. Derivatization of /Cl2PN/n polymer with alkoxides gave functionally reactive terpolymers. These terpolymers could be crosslinked with polyisocyanates at room temperature. Attempts to control molecular weight have not been as successful. The effects of (Cl2PN)3 monomer purity, use of (Cl2PN)3,4 mixture, and early termination of the bulk polymerization of (Cl2PN)3 were studied briefly. Both low and high molecular weight polymers were obtained. Reaction of NH4Cl with PCl5 with subsequent heating to give chain extension gave either gels of oils with molecular weights of several thousand. The stabilization of poly-(fluoroalkoxyphosphazene) was investigated. The results generally were inconclusive, but acids were found to be deleterious while bases had little discernible effect. Improvements in stability by modification of end groups was inconclusive

Supporting reflection and creative thinking by carers of older people with dementia

This vision paper frames requirements engineering as a creative problem solving process. Its purpose is to enable requirements researchers and practitioners to recruit relevant theories, models, techniques and tools from creative problem solving to understand and support requirements processes more effectively. It uses 4 drivers to motivate the case for requirements engineering as a creative problem solving process. It then maps established requirements activities onto one of the longest-established creative problem solving processes, and uses these mappings to locate opportunities for the application of creative problem solving in requirements engineering. The second half of the paper describes selected creativity theories, techniques, software tools and training that can be adopted to improve requirements engineering research and practice. The focus is on support for problem and idea finding - two creative problem solving processes that our investigation revealed are poorly supported in requirements engineering. The paper ends with a research agenda to incorporate creative processes, techniques, training and tools in requirements projects

Introducing creativity techniques and software apps to the care of people with dementia

This poster reports research to introduce creative problem solving techniques and software to the care for people with dementia in residential homes

Fluidic Proportional Thruster System Final Report

Fluidic proportional thrust control system with vortex valve

Saying Hello World with UML-RSDS - A Solution to the 2011 Instructive Case

In this paper we apply the UML-RSDS notation and tools to the "Hello World" case studies and explain the underlying development process for this model transformation approach.Comment: In Proceedings TTC 2011, arXiv:1111.440

Solving the TTC 2011 Model Migration Case with UML-RSDS

In this paper we apply the UML-RSDS notation and tools to the GMF model migration case study and explain how to use the UML-RSDS tools.Comment: In Proceedings TTC 2011, arXiv:1111.440

Development of thermally stable phosphonitrile elastomers for advanced aerospace structures

Both high and low molecular weight, curable poly(fluoroalkoxy phosphazene) terpolymers were prepared. These terpolymers resulted from reaction of (Cl2PNn) polymer with alkoxides derived from CF3CH2OH and C3F7CH2OH, and an alkoxide derived from CH3CH(OH)C2H4OH. The terpolymers were crosslinked with polyisocyanates at room temperature. High molecular weight materials were converted into isocyanate prepolymers which as films underwent moisture cures at room temperature. Prepolymer solutions were stable for several days, and showed good adhesion. Also the effects of polymerization of (Cl2PN)3 were studied. Purified octachlorophosphazene, thiocyanate salts, or hydrogen chloride were employed in attempts to decrease molecular weight. Hydrogen chloride was found to be a good agent for preparation of low molecular weight poly(dichloro phosphazene)

Population Dynamics of \u3ci\u3eMicrotus Ochrogaster\u3c/i\u3e in Eastern Kansas

Four eastern Kansas populations of the prairie vole, Microtus ochrogaster were live trapped from 1970—73 to gain insight into the population regulation of this species. All four populations exhibited a 2—yr cycle in numbers with peak densities generally occurring in June 1972. Peak densities were followed by a decline in numbers, a recovery, and a population crash in spring 1973. Reproductive parameters changed dramatically as density rose and fell. The summer breeding season in the crash year of 1973 was shortened by at least 3 mo. A reduction in breeding activity occurred during the summer of every year of the study. The highest amount of reproduction occurred during the spring and fall. More voles were breeding during the winter before the peak year (1971—72) than during either the preceding or succeeding winter. There was no deviation from a sex ratio of 1 in the populations. Mortality rates had a strong impact on changes in numbers. Survival rates of juveniles and subadults in the population were significantly lower than adults in the summer breeding season. Adults survived better during winter than during summer. Survival of ♂ ♂ and ♀ was correlated and was relatively low during episodes of decreasing density. The survival of voles between weaning and trappable size was high during periods of increasing density and low during periods of declining density. A multiple regression analysis was performed to determine the relative usefulness of four demographic variables in predicting mean rate of population increase. The analysis indicated that early juvenile and ♀ survival are the best predictors of population growth. Growth of voles in the populations was assessed from body weight distributions and instantaneous growth rate per body weight. There was no shift in body weight toward heavier animals in peak populations and instantaneous growth rates were erratic. Finally, inconsistencies in these results compared with other microtine studies, such as the short peak phase, lack of a well—defined breeding season, a summer breeding depression, and the absence of a shift towards heavier animals in the peak phase, are discussed in relation to a single or multifactor hypothesis for explaining population cycles

The Reproductive Cycle of \u3ci\u3eMicrotus ochrogaster\u3c/i\u3e in Eastern Kansas

About 800 Microtus ochrogaster were live—trapped at biweekly intervals from May 1971 through March 1973 in 3 grassland study areas in eastern Kansas, USA. Details of reproduction were determined by autopsy. Population density increased through the first winter, reached a peak in April 1972, then declined sharply during that summer and beyond. Body length, but not body mass, tended to be positively related to density. Both sexes matured at about the same weight; development was somewhat prolonged during the winter months, especially in the winter preceding the population peak. Pregnancy rates were high, approaching maximal iteroparity, throughout the study, with intervals of nonbreeding in both Julys, and in August and December of the population decline. Embryo counts increased significantly during the months of peak density but did not diminish in the period of the population decline. There was no association between either maternal weight or parity and number of embryos. Corpora counts were not higher in heavy or multiparious ♀ ♀, nor did the level of prenatal mortality increase during the period of greatest density. Except for a few individuals taken in July and August 1971, ♂ ♂ with a mass 30 g or more were judged to be fertile, as were a majority of the 20 to 29—g ♂ ♂. Body weight and testes weight were significantly correlated in fertile ♂ ♂ but not in nonfertile ♂ ♂. These reproductive findings were applied to a model of population regulation of microtine cycles. The pattern of reproduction of Kansas and Indiana prairie voles was compared. Three concordant lines of evidence seem to indicate that Kansas and possibly other geographical populations of prairie voles have adjusted the breeding schedule to accommodate both hot and dry summers and cold, snowy winters. Pregnancy rate, litter size, and adjusted testes weight all show a significant increase in March–April and September–October and a decrease in midsummer and midwinter. Thus the pattern of reproduction of Kansas prairie voles may represent a composite of the patterns shown by the dry—adapted species, such as Microtus californicus, and the cold—adapted microtines, such as Microtus pennsylvanicus. Based on the observations of this study, Kansas prairie voles seem to have adjusted to both harsh seasons by breeding more or less continuously, with the midsummer depression possibly reflecting the Great Plains origin of the species, and the winter depression being a facultative response to weather, density, or quality of habitat