654 research outputs found
Investigation into the Influence of Double Bagging Processes on Co-cured Scarf Repairs
The prevalence of non-monolithic materials such as carbon fibre reinforced polymers (CFRP) in aerospace has introduced many new complexities to the materials industry. Sustainment and through life costs of military vehicles are often substantially greater than acquisition costs, and as such, efforts to improve reliability and minimise costs are significant. Regarding composite structures, scarf repairs are often used to restore strength to a damaged component, with a shifting focus to out-of-autoclave processes to reduce cost. The aim of this project was to identify the effects of processing techniques through the application of novel and standard assessment techniques.
Through the application of novel techniques, including pressure mapping and cure kinetics modelling, relationships surrounding bond quality and quality control were established. It was observed throughout this project that comparable strength and quality for DVB co-cured specimens with improved quality control was achieved when a caul plate was utilised. With consistent cohesive substrate failure (CSF) observed, 0.03 +/- 0.038 % average bond-line porosity, and an average tensile strength of 401 +/- 28 MPa, the quality and consistency of these specimens was significantly greater than other co-cured groups. It was also observed that the DVB cure cycle, when applied to the hard patch approach, resulted in decreased average tensile strength, indicative of an improper cure cycle. Cure kinetics modelling applied to the adhesive saw that the DVB process delayed the onset point by approximately 5oC and 30 minutes.
Additional work is required surrounding the cure kinetics for the prepreg system, in order to establish an optimized theoretical cure process. Additionally, further mechanical testing, porosity evaluation, and dielectric cure sensing will offer additional insights into the DVB co-curing process, allowing for standardized repair procedures to be developed
Mathematical Modeling of a Sociological and Hydrologic Decision System
The general goal of this study was to develop a functional model of the sociological and related hydrologic elements in flood control decision-making. Conceptual system models were developed for the hydrologic system and for the sociological system. The sociological variables were identified as they related to the steps in the process of the model. Following the conceptual decision process model the social elements of the model were calibrated from data obtained from field studies and mathematical equations were developed and tested. Finally simulations of the process were run. After adjustments were made the model was found to function. Several methodological factors were devised to make the model more realistic and operable. These were: 1) Distortion Factors, which are differences that exists between various actual situations and perception of these situations; 2)Importance Factors, which are measures of the relative degrees of importance of each of the major characteristics of a proposal such as economic, aesthetic, effectiveness, etc,; 3) Acceptance Functions, defined as a combination of the perceived value of a characteristic and the Importance Factors; 4) Expansion Effect, which provides for changes in behavior related to values that are in a latent state of unimportance to a state of high importance stimulating high level action; 5) Threshold Levels, that determine the point between no activity and public action. These concepts permit the model to adjust to changes in social behavior related to the social structure of the decision process. The system provides for the function of social values as they relate to the social structures and the hydrologic components
Determinants of Childhood Adiposity: Evidence from the Australian LOOK Study
To contribute to the current debate as to the relative influences of dietary intake and physical activity on the development of adiposity in community-based children.Participants were 734 boys and girls measured at age 8, 10 and 12 years for percent body fat (dual emission x-ray absorptiometry), physical activity (pedometers, accelerometers); and dietary intake (1 and 2-day records), with assessments of pubertal development and socioeconomic status.Cross-sectional relationships revealed that boys and girls with higher percent body fat were less physically active, both in terms of steps per day and moderate and vigorous physical activity (both sexes p<0.001 for both measures). However, fatter children did not consume more energy, fat, carbohydrate or sugar; boys with higher percent body fat actually consumed less carbohydrate (p = 0.01) and energy (p = 0.05). Longitudinal analysis (combined data from both sexes) was weaker, but supported the cross-sectional findings, showing that children who reduced their PA over the four years increased their percent body fat (p = 0.04). Relationships in the 8 year-olds and also in the leanest quartile of all children, where adiposity-related underreporting was unlikely, were consistent with those of the whole group, indicating that underreporting did not influence our findings.These data provide support for the premise that physical activity is the main source of variation in the percent body fat of healthy community-based Australian children. General community strategies involving dietary intake and physical activity to combat childhood obesity may benefit by making physical activity the foremost focus of attention
Modeling the Total Hydrologic-Sociologic Flow System of Urban Areas - Phase II
Introduction and Overview: This is an interim report on Phase II of the three phase study. The objectives covered in this phase were: 1. To gather social and hydrologic data needed to calibrate and test the model. 2. The expand the physical model to include the rural part of the watersheds. 3. To test and improve techniques of the logical linking of the hydrologic and sociologic systems. 4. To begin adapting the model to the computer. During the second phase for the hydrologic component of the model major emphasis was placed on the expansion of the hydrologic area and the collection and analysis of additional physical data. The major emphasis for the sociologic part of the model was on the gathering of social data by the re-designing and testing of an improved research instrument (schedule or questionaire_ and administration of this schedule to a random sample of the general population in the urbanized area. The urbanized area is related to the physical hydrologic area of the study. The data were collected to improve the basic methodology and conceptualizations for linking the hydrologic and sociologic systems together in one model. Division of this report: Section II of this interim report deals with development of the physical component of they hydrologic-sociologic model. It describes the expansion of the hydrologic to include the rural parts of the watershed and tests for validation of they physical submodel. Section III review the ype of work done in Phase II of the sociological work. This consisted of: (1) reviewing the accomplishments and limitations of the first phase; (2) redesigning the questionaire to correct deficiencies in the one used in the first study, to measure additional variables throught to perhaps be relevant to the problem, and where desireable, to adapt them to the general population of the area rather than to specialized populations; (3) pretesting of component parts of the revised schedule; (4) drawing of a random sample from the population; (5) interviewing of the sample; (6) coding and processing of data for analysis; and (7) preliminary analysis of the results of the data. Progress made in the mathematical formulations of social elements is vital. The refinement of meaurement of the population data for use in the model is of central importance since the effectiveness of the testing, verification, and consequent improvement of the model depends on the accuracy of the measurement of the variables involved. Section IV shows some details on the work performed in interrelating the sociologic and hydrologic components of the model, and on one possible mathematical formulation which shows some of the interrelationships between these components. It is hoped that the formulation achieved will be useful to planners, not only in increased understanding of the total system, but also in the analysis of the merits of flood-control proposals relative to the social characteristics of particular areas. Section V discusses the purposes of the work in Phase II and the objectives expected to be met during the coming phase
Determinants of Childhood Adiposity: Evidence from the Australian LOOK Study
BACKGROUND To contribute to the current debate as to the relative influences of dietary intake and physical activity on the development of adiposity in community-based children. METHODS Participants were 734 boys and girls measured at age 8, 10 and 12 years for percent body fat (dual emission x-ray absorptiometry), physical activity (pedometers, accelerometers); and dietary intake (1 and 2-day records), with assessments of pubertal development and socioeconomic status. RESULTS Cross-sectional relationships revealed that boys and girls with higher percent body fat were less physically active, both in terms of steps per day and moderate and vigorous physical activity (both sexes p<0.001 for both measures). However, fatter children did not consume more energy, fat, carbohydrate or sugar; boys with higher percent body fat actually consumed less carbohydrate (p = 0.01) and energy (p = 0.05). Longitudinal analysis (combined data from both sexes) was weaker, but supported the cross-sectional findings, showing that children who reduced their PA over the four years increased their percent body fat (p = 0.04). Relationships in the 8 year-olds and also in the leanest quartile of all children, where adiposity-related underreporting was unlikely, were consistent with those of the whole group, indicating that underreporting did not influence our findings. CONCLUSIONS These data provide support for the premise that physical activity is the main source of variation in the percent body fat of healthy community-based Australian children. General community strategies involving dietary intake and physical activity to combat childhood obesity may benefit by making physical activity the foremost focus of attention.The financial support provided by the Commonwealth Education Trust (London, UK) was vital to the completion of this work, and the authors thank the Board of Trustees for supporting them over several years. The authors also thank members of The Canberra Hospital Salaried Staff Specialists Private Practice Fund for their financial contribution to the study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
High Chili Intake and Cognitive Function among 4582 Adults: An Open Cohort Study over 15 Years.
We aimed to examine the association between chili intake and cognitive function in Chinese adults. This is a longitudinal study of 4852 adults (age 63.4 ± 7.7) attending the China Health and Nutrition Survey during 1991 and 2006. Cognitive function was assessed in 1997, 2000, 2004 and 2006. In total, 3302 completed cognitive screening tests in at least two surveys. Chili intake was assessed by a 3-day food record during home visits in each survey between 1991 and 2006. Multivariable mixed linear regression and logistic regression were used. Chili intake was inversely related to cognitive function. In fully adjusted models, including sociodemographic and lifestyle factors, compared with non-consumers, those whose cumulative average chili intake above 50 g/day had the regression coefficients (and 95% CI) for global cognitive function of -1.13 (-1.71-0.54). Compared with non-consumers, those with chili consumption above 50 g/day had the odds ratio (and 95% CI) of 2.12(1.63-2.77), 1.56(1.23-1.97) for self-reported poor memory and self-reported memory decline, respectively. The positive association between chili intake and cognitive decline was stronger among those with low BMI than those with high BMI. The longitudinal data indicate that higher chili intake is positively associated with cognitive decline in Chinese adults in both genders
Optimisation Modelling to Assess Cost of Dietary Improvement in Remote Aboriginal Australia
BackgroundThe cost and dietary choices required to fulfil nutrient recommendations defined nationally, need investigation, particularly for disadvantaged populations.ObjectiveWe used optimisation modelling to examine the dietary change required to achieve nutrient requirements at minimum cost for an Aboriginal population in remote Australia, using where possible minimally-processed whole foods.DesignA twelve month cross-section of population-level purchased food, food price and nutrient content data was used as the baseline. Relative amounts from 34 food group categories were varied to achieve specific energy and nutrient density goals at minimum cost while meeting model constraints intended to minimise deviation from the purchased diet.ResultsSimultaneous achievement of all nutrient goals was not feasible. The two most successful models (A & B) met all nutrient targets except sodium (146.2% and 148.9% of the respective target) and saturated fat (12.0% and 11.7% of energy). Model A was achieved with 3.2% lower cost than the baseline diet (which cost approximately AUD$13.01/person/day) and Model B at 7.8% lower cost but with a reduction in energy of 4.4%. Both models required very large reductions in sugar sweetened beverages (−90%) and refined cereals (−90%) and an approximate four-fold increase in vegetables, fruit, dairy foods, eggs, fish and seafood, and wholegrain cereals.ConclusionThis modelling approach suggested population level dietary recommendations at minimal cost based on the baseline purchased diet. Large shifts in diet in remote Aboriginal Australian populations are needed to achieve national nutrient targets. The modeling approach used was not able to meet all nutrient targets at less than current food expenditure
A Preliminary Model of the Hydrologic-Sociologic Flow System of an Urban Area
This report describes the first phase of a larger study which is directed toward the development of a general technique for analyzing and solving urban metropolitan hydrologic problems through a joint consideration of both the physical and social dimensions. This report is limited to the preliminary work of identification of social variables, the first steps in assigning mathematical values to them, and developing a mathematical format for these variables. In addition, the physical-hydrologic system is identified for purposes of clarifying the elements in that system. The ultimate objective of the entire study is directed toward discovering a theoretical and generally applicable mathematical model of both the physical and social dimensions involved in metropolitan flooding problems
International Olympic Committee Consensus Statement: Molecular Basis of Connective Tissue and Muscle Injuries in Sport
Tendon and ligament injures cause significant loss of performance in sport and decreased functional capacity in the workplace. Many of these injures remain difficult to treat, and many individuals have long-term pain and discomfort. Animal studies of growth factor and cell-based therapies have shown promising results, but these treatments also can be misused to enhance athletic performance. The International Olympic Committee (IOC) now has high-level scientific advisors who can advise the IOC as to the use and abuse of these technologies
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