1,720,955 research outputs found
Constitutive Behavior of Fabric Vs. Fiber Reinforced Sand.
No full textLaboratory triaxial compression tests were performed to determine the stress-strain response of sand reinforced with continuous, oriented fabric vs. discrete, randomly oriented fiber, and to observe the influence of various inclusion properties, soil properties, and test variables on the constitutive behavior of fabric or fiber reinforced s and . Uniaxial compression tests were also run on encapsulated s and specimens to examine the effect of external fabric encapsulation on the constitutive behavior of internally reinforced granular materials. Fabric inclusions markedly increased the ultimate strength, increased the axial strain at failure; and in some cases, limited reductions, in post peak shearing resistance. At very low strain (<1%) fabric reinforcement produced a loss of stiffness with the effect being more pronounced the greater the number of layers and the stiffer the reinforcement. Reinforcements placed at a spacing/diameter ratio more than one had little effect on strength. Fabric inclusions increased the ultimate compressive strength of encapsulated sand. The overall stiffness of an encapsulated/internally reinforced s and can be controlled to a large extent by the modulus of the encapsulating fabric, and number of layers and modulus of the internal reinforcing fabric. Randomly oriented fiber reinforcements increased both ultimate strength and the stiffness of reinforced s and . Increasing the aspect ratio increased the ultimate strength and the stiffness of reinforced s and . At the same aspect ratio, confining stress, and volume ratio, "rougher," not stiffer fibers were more effective in increasing strength. Random fiber reinforcement did not result in a loss of stiffness at low strains as was observed with oriented fabric layers. Fiber reinforced sands also failed along planar shear surfaces in contrast to fabric reinforced sands that failed by bulging between layers. The existence of a critical confining stress is common to both reinforcement systems. Failure envelopes for reinforced s and s parallel the unreinforced envelope above this stress. The lower the surface roughness of the inclusion, the greater is the critical confining stress. Strength increase is generally proportional to amount of reinforcement up to some limiting content. Thereafter, the strength increase approaches an asymptotic upper limit.PhDCivil engineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/160632/1/8520859.pd
Model tests on strip footing on reinforced sand
No full textCivil Engineering Department, College of Engineering, King Saud University, P.O. Box 8OO, Riyadh 11471, Saudi Arabia.Results of bearing capacity tests on model strip footing on sand layers show beneficial effect of reinforcement with fibrillated polyproyplene fibers. The ratio of the width of the reinforced zone to the footing width (LIB) has been varied from zero to six. Also, the ratio ofthe reinforced zone depth to footing width (H/B) has been varied from zero to three. The test results indicate a significant increase in the bear-ing capacity and stiffness of the subgrade and a modification of load-settlement behaviour of footing with size of the reinforced zone and amount of reinforcement. On the basis of the present test results, the opti-mal width and depth of the reinforced layer are 4B and 2B respectively
Prediction of CRR using dynamic cone penetrometer
No full textCalifornia Bearing Ratio (CBR) value is very popular among highway engineers as a soil support value for pavement design. However, since CBR cannot be easily determined in the field, prediction of CBR values from other soil support tests such as Dynamic Cone Penetrometer (DCP) is a valuable alternative. In this study penetration depth (D) of the dynamic cone penetrometer from the laboratory prepared samples were correlated with laboratory CBR's for a number of different soil types ranging from clay to gravely sand. Unique models were found for each type of soil with good coefficient of determination (R2) and low standard error of estimate. The combined data gave also a correlation between CBR and D which compare very well with those obtained from other studies.Corresponding Author:
Prof. Talal Obeid Al-Refeai, Civil Engineering Department, College of Engineering, P.O. Box 800, Riyadh-11421, Saudi Arabia.
Email: [email protected]
RESILIENT CHARACTERISTICS OF SUBGRADE SOILS IN SAUDI ARABIA
No full textSubgrade soil samples were collected along major highways of Saudi Arabia. The properties of AASHOTO class A-2-4 soil samples, including resilient modulus, were determined and analyzed. The main purpose was to correlate resilient behaviour with other soil properties. First, resilient modulus was modeled in terms of stress state (deviator and confining stresses). Then, model constants were related by regression equations to soil properties. The developed models can be used to predict resilient modulus values based on soil properties and expected stress state under the pavement
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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