7,158 research outputs found
Evaluation of circumferential airflow uniformity entering combustors from compressors. Volume 2: Data supplement
A study of the airflow uniformity leaving compressors and entering combustors was made using compressors from two advanced engines, the J58 and F100/F401. The data used in the analysis of each case is presented in tabular form and computer-generated profile plots. A plot of the square root of the dynamic pressure ratio, which is similar to airflow deviation, is also presented
Acoustic emission spectral analysis of fiber composite failure mechanisms
The acoustic emission of graphite fiber polyimide composite failure mechanisms was investigated with emphasis on frequency spectrum analysis. Although visual examination of spectral densities could not distinguish among fracture sources, a paired-sample t statistical analysis of mean normalized spectral densities did provide quantitative discrimination among acoustic emissions from 10 deg, 90 deg, and plus or minus 45 deg, plus or minus 45 deg sub s specimens. Comparable discrimination was not obtained for 0 deg specimens
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Bearing damage characteristics of fibre-reinforced countersunk composite bolted joints subjected to quasi-static shear loading
This paper studies the progression of damage in carbon fibre-reinforced polymer (CFRP) countersunk composite bolted joints (CBJs) with neat-fit clearance, subjected to quasi-static loading. Damage mechanisms, comprising of fibre buckling and breakage, matrix damage, shear damage and inter-laminar delamination within the CFRP composite parts of the joints have been studied. Load-displacement curves, X-ray and optical microscopic images in single- and three-bolt CBJs were used to investigate damage and deformation characteristics. The observations were then employed to further investigate the type of failure and the extent of damage. The evolution of damage within the composite parts was correlated to the failure characteristics of the joints: It was found that the type and extension of damage is strongly correlated with the ultimate failure load point of the joint in single-bolt CBJs. A combined inter/intra-laminar damage consisting of fibre cluster breakage, extensive fibre buckling, debonding and delamination was observed at the ultimate failure load. This study was then extended to three-bolt CBJ where damage surrounding each bolt and its corresponding failure load was strongly correlated: The final study showed that the ultimate failure point in single-bolt CBJ and the first-bolt-failure point in three-bolt CBJ correspond to the composite plies undergoing intra-laminar damage with the size reaching to the edge of the countersunk head. This damage developed extensively through the thickness of the composite parts underneath the countersink, and in the direction opposite to the loading direction. Outside the countersunk head, debonding and delamination were found to be the dominant damage driving mechanisms. Finally, a new design rule has been proposed to predict the response of multi-bolt joints (damage area and failure load) by using the response in single-bolt CBJ as an initial baseline
The Feasibility of Concurrent Enrollment of High School Students in College-Level Introductory Plant Science
The purpose of this study was to test the feasibility of allowing concurrent enrollment in the College of Agriculture to selected high schools in the state of Utah. Introduction to Agricultural Plant Science (Plant Science 100 ) was the course being tested. A purposive sampling technique was used to identify four vocational agriculture programs to participate. There were 86 high school students in the study and 38 college students who took the course on campus at Utah State University.
In this study, 47.7% of the high school students passed the course with a 70% average or above. Comparisons between high school and college student performance showed a marked difference in percentage points accumulated on exams and the final, with the college students performing more consistently
Internalising the brand
Internal branding has become a focus of research interest especially in service led organisations. However, interest in employee understanding and brand supportive behaviour is an under researched area (Punjaisri and Wilson 2007). This paper aims to add insights regarding internal branding and brand delivery from a new employee perspective in a retail context. It reveals new employees’ understanding of brand values, their use in everyday work and the congruence with management expectations. As a result of this research specific recommendations were made to the organisation in order to develop an improved internal branding programme
How robust is the evidence of an emerging or increasing female excess in physical morbidity between childhood and adolescence? Results of a systematic literature review and meta-analyses
For asthma and psychological morbidity, it is well established that higher prevalence among males in childhood is replaced by higher prevalence among females by adolescence. This review investigates whether there is evidence for a similar emerging female ‘excess’ in relation to a broad range of physical morbidity measures. Establishing whether this pattern is generalised or health outcome-specific will further understandings of the aetiology of gender differences in health. Databases (Medline; Embase; CINAHL; PsycINFO; ERIC) were searched for English language studies (published 1992–2010) presenting physical morbidity prevalence data for males and females, for at least two age-bands within the age-range 4–17 years. A three-stage screening process (initial sifting; detailed inspection; extraction of full papers), was followed by study quality appraisals. Of 11 245 identified studies, 41 met the inclusion criteria. Most (n = 31) presented self-report survey data (five longitudinal, 26 cross-sectional); 10 presented routinely collected data (GP/hospital statistics). Extracted data, supplemented by additional data obtained from authors of the included studies, were used to calculate odds ratios of a female excess, or female:male incident rate ratios as appropriate. To test whether these changed with age, the values were logged and regressed on age in random effects meta-regressions. These showed strongest evidence of an emerging/increasing female excess for self-reported measures of headache, abdominal pain, tiredness, migraine and self-assessed health. Type 1 diabetes and epilepsy, based on routinely collected data, did not show a significant emerging/increasing female excess. For most physical morbidity measures reviewed, the evidence broadly points towards an emerging/increasing female excess during the transition to adolescence, although results varied by morbidity measure and study design, and suggest that this may occur at a younger age than previously thought
An Anesthesia Display for a Space Station: Clinical Validation of Sedation and Analgesia Models
Real-time visualizations of drug pharmacokinetics and pharmacodynamics may help anesthesiologists more accurately titrate intravenous anesthetics for sedation and analgesia in a critical care setting. To assess synergism between propofol and opioids, our laboratory has developed response surface pharmacodynamic interaction models for remifentanil and propofol. These models use surrogate measures of analgesia and sedation from a volunteer study but must be validated before they are applied to patients in a real-time display; the surrogate measures used in the volunteer study must be related to clinical patient responses. The aim of this study is to explore the pharmacodynamic relationship between the surrogate and clinical responses. We hypothesize that the surrogate stimuli from the volunteer study can be mapped to surgical stimuli; we expect the levels of anesthesia required to moderate responses to the surrogate measures relate to levels of sedation and analgesia needed to prevent responses to surgical stimuli in the operating room
Tuning Fermi-surface properties through quantum confinement in metallic meta-lattices: New metals from old atoms
We describe a new class of nanoscale structured metals wherein the effects of
quantum confinement are combined with dispersive metallic electronic states to
induce modifications to the fundamental low-energy microscopic properties of a
three-dimensional metal: the density of states, the distribution of Fermi
velocities, and the collective electronic response.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let
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