Thesis (M.Econ..)--University of Hong Kong, 2001. / Includes bibliographical references. Also available in print.

Thesis (Ph. D.)--University of Texas, 2001. / Vita. Includes bibliographical references (leaves 123-127).

Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, June 2005. / Thesis Advisor(s): Roberto Cristi. Includes bibliographical references (p. 71-72). Also available online.

Within the aerospace industry, the reduction of costs associated with operation, manufacture and development of gas turbine engines is a primary objective. Component and assembly design optimisations can satisfy weight reductions which correspond to operational and manufacturing cost reductions. Development cost can be reduced by implementing additional numerical validation stages as an alternative to experimental validation alone. Therefore, the overarching purpose of this research is the development of a computationally efficient constitutive modelling tool, which predicts the macroscopic deformation and failure of fan system components and assemblies during dynamic and highly non-linear thermo-mechanical loading. At the macroscopic scale a series of physical deformation and failure phenomena have been identified from the literature which are necessary for accurate representation of the dynamic behaviour of Ti-6Al-4V. Across the surveyed literature these capabilities have not been implemented together within a single constitutive framework prior to the commencement of this research. Experimental support provides validation data for the subsequent constitutive modelling activities, whilst also demonstrating the importance of strain-rate sensitivity, tension-compression asymmetry and anisotropic behaviour associated with texture orientation in Ti-6Al-4V. Numerical studies were also conducted to develop a robust procedure for rapid assimilation of uni-axial experimental data within constitutive benchmarking models, for development purposes. Further parametric studies of sub-component plate impact benchmarks revealed several limitations within the commercially available solutions. These limitations are related to mesh sensitivity and damage evolution. A technique has been proposed which couples damage evolution and imposes a directional length-scale. This provides enhanced mesh insensitivity and damage evolution rate control. However, a single damage evolution mechanism was demonstrated to be insufficient when representing shear damage mechanisms in uni-axial and multi-axial loading regimes. Therefore, an additional damage mechanism has been developed and coupled with the mesh sensitivity and localisation technique. The resulting cumulative and competitive damage evolution and localisation capabilities reflect the localisation characteristics observed in the literature. The variability of alloy manufacture and the subsequent macroscopically observed behaviour remain a limitation within an isotropic framework. This has motivated the development of both asymmetric and anisotropic formulations, integrated within the newly proposed multi-mode damage localisation framework. The ability of the newly implemented non-isotropic framework successfully provides both asymmetric yielding and hardening capabilities and anisotropic evolution. These developments have been demonstrated against experimentally obtained results for validation and calibration purposes. Together these capabilities allow for accurate representation of a wide range of macroscopically observable phenomena based upon micro mechanical mechanisms.

Pre-maturity <i>alpha</i>-amylase activity (PMAA) in the absence of sprouting is one of four causes of low Hagberg falling number (HFN) in UK winter wheat (<i>Triticum aestivum</i>), reducing the quality and value of milled flour. Other causes include the retention of pericarp <i>alpha</i>-amylase activity (RPAA), pre-maturity sprouting (PrMS) and post-maturity sprouting (PoMS). This thesis investigated the effects of environmental factors on PMAA which currently occurs in a variable and unpredictable fashion under UK weather conditions. A multi-site field experiment on four cultivars (Haven, Hornet, Pastiche and Riband), at four sites (Harper Adams University College, University of Nottingham, University of Aberdeen and ADAS-Bridgets) between 1994-1996 was undertaken to:- establish the frequency of the causes of low HFN; examine the relationship between grain drying-rate and PMAA; determine if it was possible to predict combine harvest HFN. A range of techniques including a visual sprouting assessment, fluorescein dibutyrate staining, iso-electric focusing and a beta-limit dextrin gel and iodine staining test were used to allow the cause of low HFN to be established. Of the forty crops analysed, 22 cases (45%) had detectable amounts of <i>alpha</i>-amylase activity. PMAA was identified solely in 2 cases (5%), in combination with PoMS in 8 cases (20%), in combination with RPAA in one case (2%), with PoMS occurring solely in 11 cases (28%). The HFN fell below the breadmaking standard of 250 s in 18 of the 36 site x year x cultivar combinations analysed. This was attributed solely to PMAA in two cases (11 %), a combination of PMAA and PoMS in a further eight cases (44%) and solely to PoMS in eight cases(44%). There were no cases where PrMS or RPAA reduced the HFN to below 250 s. The hypothesis that PMAA is related to the grain drying-rate between 40-20 % moisture content was tested. Grain drying-rate was determined by linear regression analysis using moisture content measurements made at regular intervals during grain development. In site x year x cultivar combinations where PMAA was detected the grain drying-rate was significantly (P = 0.047) lower (mean = 1.90 <i>cf</i>. 2.30% moisture loss day^-1), suggesting a slow grain drying-rate enhances PMAA. However, the low frequency of occurrence of PMAA in isolation prevented quantification of this relationship. Initiation of PMAA in the grain, was shown to occur from a grain moisture content of 47.8%. A pre-harvest sample taken by hand at 850 °C-days (35 % moisture, Zadoks growth stage 85-87) was shown to enable a prediction of combine harvest HFN to be made in the absence of subsequent rainfall and PoMS. The 95 % confidence limits associated with this HFN prediction were however wide. The hypothesis that transient changes in temperature early in grain development may affect PMAA, before the onset of any grain drying-rate effects, was tested in five controlled-environment cabinet experiments. Of 36 cultivar x time of transfer combinations undertaken from a 16/ 10°C to a 26 /20°C temperature regime, six led to a significant increase (P < 0.05) arid one led to a significant decrease in PMAA. Of the 18 cultivar x time of transfer combinations undertaken from a 25 / 20°C to a 16 / 10°C temperature regime, one led to a significant increase and one led to a significant decrease in PMAA. A comparison between the field and controlled-environment experiment results highlighted that after conditions putatively stimulating PMAA had been encountered, subsequent environmental factors, such as mean temperature and relative humidity may also affect PMAA. It was concluded that PMAA can be enhanced by transient increases in temperature before the grain reaches 40% moisture content and by a slow grain drying-rate between 40-20% moisture content. The variability in the results, however, also suggested other environmental factors were influencing PMAA.

Master of Science / Department of Agronomy / Ignacio Ciampitti / Genotype by seeding rate interaction can play a critical role in wheat (Triticum aestivum L.) yield potential. The objectives of this study were to i) quantify wheat yield response and ii) early-season plant establishment related to the planting technology under diverse seeding rates and with contrasting varieties relative to their tillering ability. Four studies were established at two locations during two growing seasons (2015-16 and 2016-17) at Ashland Bottoms (dryland and conventional till in the first year and no-till in the second year) and at Topeka (irrigated and no-tillage for both years) field research stations (KS, US). Two winter wheat varieties were planted with two different planting systems (singulated and conventional drill) at four different seeding rates (45, 90, 135, and 180 kg ha⁻¹). Early-season measurements consisted of stand counts, canopy coverage (estimated via imagery collection via small-unmanned aerial vehicle systems - sUAVS), determination of early-season gaps within the stand of plants, and spacing between plants. Early season measurements (emergence progression, stand count, and canopy coverage) and biomass did not present differences among treatments. At Ashland, across 2-yrs, single factors seeding rate and genotype significantly impacted yields. Seeding rate factor positively affected yields, ranging from 4.7 to 5.4 Mg ha⁻¹ with seeding rates going from 45 to 135 kg ha⁻¹, respectively. For the genotype factor, the variety WB Cedar (high-tillering) presented an overall yield of 605 kg ha⁻¹ greater than WB 4458 (low-tillering). Across locations, the seeding system did not influence yields for both years of the study. At Topeka, the seeding system significantly influenced yields in 2017, with singulation outyielding the drill system, in 161 kg ha⁻¹. Further research is needed at a farmer-scale testing more winter wheat varieties and focusing on lower seeding rates to better understand the potential benefits of the implementation of this new technology.

No description available.

Using data from the Leicestershire Growth Study, which was established in 1981, this thesis sets out to evaluate the growth of children in Leicestershire and to highlight any differences which may exist between those children indigenous to Great Britain and those whose families have emigrated from the subcontinent of India. The latter population can be subdivided further, i.e. peoples from the countries of India, Bangladesh and Pakistan, the first group primarily, having either migrated from India directly to this country or having spent an interim period in East Africa, and into adherents of the Muslim, Hindu or Sikh faiths. Seven anthropometric parameters, selected to represent skeletal and soft tissue components of the body, and whose dimensions reflect best the changing patterns of growth with age and environmental factors, were measured on 3775 children aged from 3-10 years inclusive. There are distinct anthropometric differences between the indigenous population and that from the Indian subcontinent, with the indigenous population having greater skeletal dimensions, e.g. stature, head circumference, and differences in body composition, reflected in greater weight. These ethnic differences appear to have been exacerbated by religious factors which impinge upon both genotype and phenotype by imposition of their respective individual cultures:, involving such factors as dietary intake and marriage customs, resulting in the Indian Sikh children resembling more closely the indigenous population than do the Hindus and Muslims. Other environmental factors such as length of time of residence in this country, or period of time spent in East Africa appear to have had some impact upon growth, since the Indians in Leicestershire are taller and heavier than their counterparts still resident in India. Finally, it is recommended that some of the growth charts in current use in Great Britain be modified for use with certain groups of children from the Indian subcontinent.

Abstract The evolution of sociality is often associated with close relatedness and genetic similarity of interacting individuals. However, colonies of advanced social insects (e.g. ants, bees and wasps) characterized by large colony size and division of tasks, are also shaped by acquisition of genetic diversity by polyandry, polygyny, recombination and even by hybridization. The balance between forces selecting for high relatedness on one hand and for improved colony performance though increased genetic diversity on the other hand forms an intriguing area of research. My study has produced the first genetic linkage maps for ants (Acromyrmex echinatior and Pogonomyrmex rugosus) and social wasps (Vespula vulgaris). Together with the findings of earlier honeybee research, it is shown that advanced eusocial insects have higher recombination rates than any other insect (or animal) studied so far. The estimates obtained here were 14 cM/Mb for P. rugosus, 9.7 cM/Mb for V. vulgaris and 6.2 cM/Mb for A. echinatior. Pogonomyrmex harvester ants have a genetic caste determination system in which workers arise from mating between two hybridizing lineages whereas sexuals are produced by within-lineage mating. I evaluated the origin of the lineages and the caste determination system by using 751 variable nuclear genetic markers. Fertile hybrids would lead to introgression, particularly in genomic regions characterized by a high recombination rate and lack of strongly selected loci. The hybridizing lineages (lineage pairs J1/J2 and H1/H2) showed many fixed differences. Nineteen of them were in the constructed linkage map, scattered in different linkage groups. The results suggest that there has been no recent introgression. As the hybrids are viable (as workers), caste differentiation can be affected by many loci scattered throughout the ant genome or by a small number of very strongly selected loci. Genetic diversity in colonies of the ant Formica cinerea is affected by varying levels of polygyny. I tested the hypotheses that the prevalence of endosymbiotic bacteria can vary in polygynous colonies but be either very low or very high in monogynous colonies. However, I found no association between the level of polygyny and endosymbiont prevalence. In addition to Wolbachia, I found two other endosymbiotic bacteria Cardinium and Candidatus Serratia symbiotica which have not been earlier reported from ants. Genetic diversity in insect colonies is affected by polyandry and polygyny. My results indicate that high a recombination rate is also an important factor influencing diversity. Genotypically diverse progenies can enhance colony success, e.g. through effects on division of labour or defence against pathogens. Recombination differs from the other factors in its effects on genetic relatedness among colony members.

Class of 2013 Abstract / Specific Aims: To determine if temperature and direct sunlight influence the rate of evaporation of normal saline in 100mL IV bags. Methods: Four study groups were created; refrigeration, dark shelf, shelf near window, and EMT box simulation. 80 bags (50 ml bags of normal saline) placed in different areas of temperature change and sun exposure. 20 of the bags stored in a drawer in a refrigerator. 20 stored on a shelf in a dark temperature controlled room. 20 stored next to a window in direct sunlight, and 20 stored outside where temperature and sun exposure will be highest in an EMT simulated box. Weights were recorded (in gms) weekly for 8 weeks using an analytical balance. Each saline bag was weighed individually and recorded at the time of measurement. Main Results: Rates of volume loss were lower in the normal saline IV bags stored in a refrigerated environment compared to the other two groups stored at room temperature and the one group stored in outside conditions (p<0.001). IV bags stored at room temperature exposed to light had the second lowest rate of loss compared to the other two groups (p<0.001 compared to outside conditions and p=0.003 compared to closed drawer). Bags stored at room temperature in a closed door had the third lowest rate of loss (p<0.001). Conclusion: Rate of fluid loss from IV normal saline bags appears to be temperature sensitive and storage of these bags may have an impact on shelf life of the product.