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排序方式: 共有951条查询结果,搜索用时 375 毫秒
81.
Graesser Arthur C.; Bowers Cheryl; Olde Brent; Pomeroy Victoria 《Canadian Metallurgical Quarterly》1999,91(2):284
One dimension of reading literacy involves the tracking of agents associated with the text. In a literary short story, there is a society of character agents and pragmatic agents. This study investigated the relative salience of different classes of agents in memory. Two experiments measured source memory as an index of agent salience in long-term memory. Patterns of source memory scores supported an invisible third-person narrator hypothesis and an agent amalgamation hypothesis, but not a structural prominence hypothesis: First-person narrator > nonnarrator character > third-person narrator > 0. Statement detection parameters did not significantly differ among the 3 classes of agents, so differences in source memory could not be explained by differences in the content of the speech acts. Source memory scores also could not be explained by surface features of the text, differences among readers, and sophisticated guessing on the basis of a story abstract. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
82.
Longitudinal data from a national sample of Germans (N = 20,434) were used to evaluate stability and change in the Big Five personality traits. Participants completed a brief measure of personality twice, 4 years apart. Structural equation modeling techniques were used to establish measurement invariance over time and across age groups. Substantive questions about differential (or rank-order) and mean-level stability and change were then evaluated. Results showed that differential stability was relatively strong among all age groups but that it increased among young adults, peaked in later life, and then declined among the oldest old. Patterns of mean-level change showed that Extraversion and Openness declined over the life span, whereas Agreeableness increased. Mean levels of Conscientiousness increased among young adults and then decreased among older adults. Trajectories for Neuroticism were relatively flat, with slight increases during middle age and a slight decline in late life. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
83.
Forced-air space-conditioning systems are ubiquitous in U.S. residential and light-commercial buildings, yet gaps exist in our knowledge of how they operate in real environments. This investigation strengthens the knowledge base of smaller air-conditioning systems by characterizing a variety of operational characteristics measured in 17 existing residential and light-commercial air-conditioning systems operating in the cooling mode in Austin, Texas. Some key findings include: measured airflow rates were outside of the range recommended by most manufacturers for almost every system; actual measured cooling capacities were less than two-thirds of rated cooling capacities on average; hourly fractional operation times increased approximately 6% for every °C increase in indoor–outdoor temperature difference; and lower mean indoor surrogate thermostat settings and higher supply duct leakage fractions were most associated with longer operation times. The operational characteristics and parameters detailed herein provide insight into the magnitude of the effects of HVAC systems on both energy consumption and indoor air quality (IAQ) in residential and light-commercial buildings. 相似文献
84.
In the design of the direct methanol fuel cell and the evaluation of new materials and their appropriateness for inclusion, it is helpful to consider the impact of material properties on the performance of a complete system: to some degree, methanol crossover losses can be mitigated by proper system design. As such, an analytical model is developed to evaluate the methanol concentration profile across the anode backing layer and membrane of the direct methanol fuel cell. The model is integrated down the anode flow channel to determine fuel utilization as a function of the feed concentration, backing layer properties, and membrane properties. A minimum stoichiometric ratio is determined based on maintaining zero-order methanol kinetics, which allows the fuel efficiency to be optimized by controlling these physical properties. This analysis is then used to estimate the required flow rates and the size of system components such as the methanol storage tank, based on the minimum methanol flow rate that those components must produce to deliver a specified current; in this way, the system-level benefits of reduced membrane crossover can be evaluated. 相似文献
85.
Steven DelloRusso Gunjeet Juneja Brent Gabby Donald Dusenberry 《Canadian Metallurgical Quarterly》2008,22(4):197-206
The Milwaukee City Hall was built between 1893 and 1898 and is located in downtown Milwaukee, one block east of the Milwaukee River. The 300?ft (91.4?m) long building, nine stories high over its main portion, is a trapezoid in plan. On the south side, there is a 393?ft (119.8?m) tall South Tower located above the main entrance to the building. On three sides, the South Tower rises from the street level to the 13th level and the roof above, and on the north side, it is connected to the rest of the building up to the ninth floor. The South Tower is a hybrid steel and masonry structure consisting of masonry perimeter walls and a central core, four-sided steel truss supporting the floors and roof. The building is a perimeter-load-bearing masonry structure supported on wood piles. The city of Milwaukee had been aware of distress, in the form of cracks and loose masonry, in the South Tower for a number of decades. In 2002, the city took action to investigate the causes and significance of distress, and to develop a repair program. The scope of our work included review of the available structural drawings and documents, inspection of the tower, measurement and monitoring of movements, monitoring of thermal response, structural analyses of the hybrid steel and masonry structure, and development of repair recommendations. The repair program presently is under construction. This paper describes the monitoring program, analyses of the causes for distress, and the implemented repair concepts for the observed distress in the South Tower of the Milwaukee City Hall. 相似文献
86.
A facile approach to prepare thiol-terminated poly(styrene-ran-vinyl phenol) (PSVPh) copolymers and PSVPh-coated gold nanoparticles is reported with the goal of creating stabilizing ligands for nanoparticles with controlled hydrophilicity. Dithioester-terminated poly(styrene-ran-acetoxystyrene) copolymers were synthesized via RAFT polymerization using cumyl dithiobenzoate as a chain transfer agent. These copolymers were converted to thiol-terminated PSVPh copolymers by a one step hydrazinolysis reaction using hydrazine hydrate to simultaneously convert dithioester-terminal and acetoxy-pendant groups to thiol-terminal and hydroxyl-pendant groups, respectively. Spectroscopic observations including NMR and IR confirm end- and pendant-group conversion. PSVPh-coated gold nanoparticles were synthesized in the presence of a mixture of thiol-terminated PSVPh and PSVPh copolymers containing disulfides as stabilizing ligands in a water/toluene, two-phase system. The size and size distribution of core gold nanoparticles were determined by TEM and image analysis. The hydrodynamic radius of PSVPh-coated gold nanoparticles was also determined by dynamic light scattering experiment, which confirms the particle analysis by TEM. This procedure provides a facile technique to control the polarity and hydrophilicity of metal nanoparticle surfaces and could prove critical in advancing the control of nanoparticle placement in biological and hierarchically ordered systems, such as diblock copolymers. 相似文献
87.
John Obielodan Brent Stucker 《The International Journal of Advanced Manufacturing Technology》2013,66(9-12):2053-2061
The design of engineering structures with function-specific material members is on the increase. This requires advanced fabrication technologies with capabilities for multi-material processing. A major challenge however is obtaining effective transition from one material to another. Dissimilar material systems made using laser metal deposition processes have been investigated. The fusion of materials having different physical properties and chemical compositions under high laser power often results in defects at the joints due to thermal expansion mismatch, the formation of intermetallics, or other mechanisms. Some solutions have been proffered in previous works based on evaluations using qualitative techniques. However, quantitative experimental studies are imperative to accurately assess the mechanical behavior of dual-material structures for real-life applications as predictive tools have not yet been validated. In this work, different designs of material transitions from Ti6Al4V alloy to Ti6Al4V/TiC composites were established. Experimental evaluations of their strengths at these joints were made using LENS-fabricated tensile and flexural test samples. The mode of transition from one material to another was found to have a significant effect on the tensile strengths of the structures. Also, material transition designs with optimum strengths were applied for the fabrication of simplified dual-material minimum-weight structures and tested. The structures failed at locations away from the material transition regions, thus proving the effectiveness of the joints. 相似文献
88.
Tong-Tsung Wang Peter R. Morris Brent L. Adams 《Metallurgical and Materials Transactions A》1990,21(8):2265-2275
The morphological and lattice orientational microstructure of commercial-purity aluminum ingot (1100 series) is investigated
by section analysis and individual measurements of crystallite orientation from electron backscattering diffraction (EBD).
These measurements render possible the determination of the sectional grain-area distribution, the number-of-sides per grain
section distribution, the mean grain-interception length, the orientation distribution function, and the nearest-neighbor
orientation coherence function. It is found that the morphological measures of the aluminum ingot are consistent with predictions
based upon the classical Johnson-Mehl model. A small anisotropy of grain shape is observed, with the grains exhibiting a 17
pct larger dimension in the axial direction of the ingot compared with radial and hoop directions. The orientational measures
indicate that the ingot has a random texture with random spatial orientation coherence relationships.
Formerly Visiting Scholar, Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602, is retired. 相似文献
89.
Analysis of Residential Irrigation Distribution Uniformity 总被引:1,自引:0,他引:1
Melissa C. Baum Michael D. Dukes Grady L. Miller 《Canadian Metallurgical Quarterly》2005,131(4):336-341
Irrigation has become commonplace for residential homeowners desiring high quality landscapes in Florida. The goal of this project was to document irrigation system uniformity in Central Florida and to quantify distribution uniformity of residential sprinkler equipment under controlled conditions. The catch-can testing procedure used was a modified version of both the American Society of Agricultural Engineers standard and Florida Mobile Irrigation Laboratory (MIL) procedures. The modified version included a larger sample size to ensure complete sample collection over the entire irrigated area. The standard MIL procedure may overestimate the uniformity for residential systems. From the tests on residential irrigation systems, the average low quarter distribution uniformity (DUlq) value was calculated as 0.45. Rotary sprinklers resulted in significantly higher DUlq compared to fixed pattern spray heads with 0.49 compared to 0.41, respectively. From uniformity tests performed on rotor and spray heads under ideal conditions, rotor heads had more uniform distributions than the spray heads of 0.55 compared to 0.49, respectively. Spray heads had better uniformity when fixed quarter circle nozzles were used as opposed to adjustable nozzles. Both residential irrigation system and controlled tests resulted in (DUlq) at the low end of industry guidelines. Residential irrigation system uniformity can be improved by minimizing the occurrence of low pressure in the irrigation system and by ensuring proper spacing is used in design and installation. 相似文献
90.
Participants were surveyed after joining a self-help group for unemployed professionals over the age of 40 and again 1 year later. A hidden cost of job loss, especially for older workers, may be decreased satisfaction with the new job obtained after a period of unemployment. Of the 24 initially unemployed participants who sought jobs, 1 year later 16 were reemployed, and 8 were still seeking jobs. The 16 reemployed participants indicated significantly less satisfaction in their new positions, compared to the ones held previously, with regard to pay and benefits. There was no change in satisfaction with co-workers. Satisfaction with supervision, the nature of the work, and prospects for promotion had increased. Positive self-esteem and internal locus of control at the initial survey were positively correlated with job satisfaction after reemployment. Contrary to expectations, age was also positively correlated with satisfaction in the new job. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献