The accelerated durability test is an important part for design and manufacturing ground vehicles. It consists of test designed to quantify the life characteristics of a ground vehicle component under normal use conditions by testing the unit at higher stress levels to accelerate the occurrence of failures. The challenge of conducting accelerated durability tests is to create the driven profile. In general, the mission profiles of the accelerated durability test can be generated via the acceleration data of the events experienced by the vehicle during the field test. Accurately separating the time series signal that correlate the load events becomes essential to efficiently generate the mission profiles for the accelerated test analysis. The representative Power Spectrum Density (PSD) profile can be generated based on the mission profiles. Then, the driven profile for the sub-scaled accelerated durability test, i.e., the acceleration data can be generated based on the PSD data.

The accelerated durability test is an important part for design and manufacturing ground vehicles. It consists of test designed to quantify the life characteristics of a ground vehicle component under normal use conditions by testing the unit at higher stress levels to accelerate the occurrence of failures. The challenge of conducting accelerated durability tests is to create the driven profile. In general, the mission profiles of the accelerated durability test can be generated via the acceleration data of the events experienced by the vehicle during the field test. Accurately separating the time series signal that correlate the load events becomes essential to efficiently generate the mission profiles for the accelerated test analysis. The representative Power Spectrum Density (PSD) profile can be generated based on the mission profiles. Then, the driven profile for the sub-scaled accelerated durability test, i.e., the acceleration data can be generated based on the PSD data.

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The study examined the demographic profiles associated with academic performance for third grade students in North Forest and Aldine Independent School Districts (ISDs) in Texas. Specifically, the study showed the impact that gender, ethnicity, and whether students receive free or reduced lunch (parent income level), had on third grade reading Texas Assessment of Academic Skills (TAAS) scores. The population for this study was 368 of the 9,007 third grade students from both the North Forest and Aldine Independent School Districts. Students in this study were of the predominant ethnicities at the schools: Black, Hispanic, and White. Utilizing this sample size allowed the study results to be generalized as trend data for all third grade students in the two districts. Data were collected during the spring semester of the 2002-2003 school year. Information for the study was provided through the Public Education Information Management System (PEIMS) and Academic Excellence Indicator System (AEIS) reports of both school districts. Results showed that gender does not relate to the TAAS score in North Forest, but the income level is related to third grade reading TAAS performance. Income showed a significant relationship in that North Forest had a higher percentage of students receiving free and reduced lunch. This impacted the third grade TAAS reading scores. Gender was significantly related to third grade TAAS performances at Aldine ISD in that Aldine had 66 more girls to take the test than boys. There were only 54 boys who took the test. Gender had no significance in North Forest ISD because there was an even number of girls and boys who took the test. Ethnicity would not be analyzed at North Forest ISD due to the small percentage of non-Black students in the third grade. At Aldine ISD, no relationship was found between ethnicity and third grade TAAS performers. The success rate on third grade TAAS was significantly higher at Aldine ISD (percent passed 85.1) than at North Forest ISD (percent passed 39.6).

Abstract Themango gall fly (Procontarinia) is a growing concern in many countries that importmango trees.Mangoes flush (produce opening buds) twice a year: once in spring, and the main flush, which occurs in early autumn flush and corresponds to the photoperiod necessary for the gall fly to emerge. Gall flies attack only very young mango flush leaves. Three cultivars displaying varying susceptibility were used in this study: Heidi, which typically is heavily infected; Keitt, which displays antixenosis properties; and Sensation, which is resistant to gall fly attack. Headspace profiles of the three cultivars were obtained over two full growing seasons. It was found that flush leaves emit higher levels of volatile organic compounds than mature leaves. Volatile emissions peaked during the main flush, after which they declined as the tree went into the winter dormant period. The levels of a- and b-pinene increased in gall fly-susceptible cultivars as the season progressed, while very low levels of these terpenes were emitted by resistant cultivars. The changes in the profiles of these emissions suggest that aand b-pinene may be linked to gall fly susceptibility. In addition, chemometric analysis confirmed the correlation between volatile emissions and gall fly susceptibility.

Abstract Mango gall fly (Procontarinia matteiana) is an orchard pest that parasitises flush leaves of mango and serious outbreaks may result in reduced fruit yield. The trigger for infestation is unknown, but terpenes emitted by the leaves appear to play a role in attraction. Metabolic profiles of three mango cultivars of varying susceptibility to mango gall fly attack were obtained by headspace profiling using GC-FID and GC-MS analysis. Chemometric models constructed from the data revealed that three terpenes, α- and β-pinene and camphene could be useful as biomarkers for susceptibility. Headspace profiles of twenty other cultivars, naturally exposed to gall fly, were obtained in the same way. Susceptibility or resistance of these cultivars was predicted using the developed orthogonal partial least squares model. Predictive outcomes were thereafter verified by visual examination of the leaves to detect gall formation, an indication of gall fly infestation. The model was found to predict the susceptibility or resistance of 90% of the cultivars accurately. This finding indicates the contributory role of the three terpene biomarkers in mango gall fly interaction and may direct future studies to determine their inter-relationship.

The properties of a polymer surface can be manipulated by the addition of a small quantity of surface active functionalised polymer to the bulk. On annealing above the glass transition these low surface energy functional groups attach to the air/polymer interface forming a brush like layer. To quantify this effect perdeuterated polystyrenes with fluoroalkane groups at specific locations in the polymer have been blended with unmodified polystyrene. Three key areas have been studied; effect of molecular architecture; effect of the molecular weight of the matrix polymer; and the rate of formation of the segregating layer. The complementary techniques of neutron reflectometry and nuclear reaction analysis have been used to determine the near surface depth profile of the deuterated polymer. Architectures studied were linear polystyrene with functional groups at both ends of the polymer chain, a 3-armed star with a functional core and linear polystyrene with functional groups evenly spaced along the chain. The architecture affected the shape of the composition profile but had little effect on the surface volume fraction and surface excess values obtained for the same bulk volume fraction. Self-consistent field theory simulations were carried out to determine the 'sticking energy' of the functional groups and good comparisons were obtained between the experimental volume fraction profiles and those predicted. Some segregation of functional polymer was observed during sample preparation and equilibrium segregation was obtained in less than one hour for 50000 M(_W) linear polymer up to eight hours for the 3-armed star after annealing under vacuum at 413K. For the difunctional polystyrene the functional groups did not have a significant affect on the rate of diffusion compared to non-functional polystyrene and diffusion coefficients obtained ranged from 6x10(^-16) to 9x10(^-15) cm(^2)s(^-1) The 3-armed star had the lowest diffusion coefficient value of 2xl0(^-16) cm(^-2)s(^-1) because of the inability for branched molecules to diffuse by reptation.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 78-80). Also available via the Internet.