1,354,337 research outputs found
Calibration of AC Reflection Cracking Model in AASHTOWare Pavement ME Design for Nevada’s Conditions
No full textThe empirical design guide published by the American Association of State Highway Transportation Officials (AASHTO 1993), has been predominantly used by the majority of state highway agencies across the United States. Efforts were done by the National Cooperative Highway Research Program (NCHRP) under Project 1-37A to implement an improved design guide: “The Mechanistic-Empirical Pavement Design Guide (MEPDG).” The MEPDG uses a mechanistic-empirical (ME) procedure that predicts future pavement conditions based on analyzing the pavement responses.This Thesis describes the research efforts done in order to calibrate the new asphalt concrete (AC) reflection-cracking model implemented in the AASHTOWare Pavement ME Design and developed under the NCHRP project 1-41: “Models for Predicting Reflection Cracking of Hot-Mix Asphalt Overlays.” For this purpose, several Nevada Department of Transportation (NDOT) pavement sections including State Routes, Interstate Routes, and US Routes were selected to conduct the calibration. The calibration of the reflection-cracking model was done to better match Nevada’s local conditions for climate, traffic, materials and was performed by optimizing/scaling the global calibration factors to reduce the sum of square error between predicted and measured distress data. As a result, local calibration coefficients were established for AC total fatigue cracking (bottom-up + reflective) and AC total transverse cracking (thermal + reflective). Elevation at the project’s location was found to influence the predictions, thus necessitating different local calibration coefficients
Numerical Modeling of Large-Scale Pavement Experiments Using Fast Lagrangian Analysis of Continua (FLAC3D)
No full textThe movement of superheavy loads (SHLs) on the pavement structure can cause severe damage to the infrastructure if the pavement was not designed to sustain such loads. Researchers at University of Nevada, Reno (UNR) conducted full large-scale pavement experiments with various pavement characteristics (layer configurations and loadings) to simulate field conditions and address the problem.In this thesis, pavement loading responses of five different large-scale pavement experiments were evaluated using a numerical method and were compared to the responses measured by the experimental program undertaken by UNR researchers. The first experiment was on a subgrade layer. A crushed aggregate base was added on top of the subgrade in experiment No.2. The subsequent experiments consisted of a full three layers pavement structure whereas experiment No.4 simulated a full pavement structure with a sloped shoulder. The final experiment was on a full pavement structure with two buried utilities located in the subgrade layer. The utilities consisted of flexible and rigid pipes. The numerical approach was undertaken using Fast Lagrangian Analysis of Continua in Three Dimension (FLAC3D) along with FISH functions, which use built-in scripting language that give the user powerful control over many aspects of program operation. Special considerations had to be given to generate mesh configurations for model experiments No.3 and No.4 as they included sloping pavement shoulder and buried utilities. In this study, the top two layers were modeled using the built-in isotropic elasticity model (constant modulus), but the bottom layer (subgrade) was modeled using the FISH function to characterize its non-linear stress-dependent behavior using an iterative solution approach. The focus in predicted results was given to stresses, in particular vertical stresses at various locations within the pavement. The main reasons for this focus are: (1) availability of recorded data from TEPCs; and (2) the importance of vertical stresses relative to pavement performance predictions. Although many factors affect the results generated by FLAC3D when modeling pavement structures, the vertical stresses predicted present reliable results when compared to the measured results. This means that FLAC3D can be used for multi-layer pavement investigations when complex loading (normal and shear interface stresses) and layer profiles (sloping and existence of water table, etc.) are present. It may be important to model the vehicle-pavement interaction as a dynamic moving load and such loading scenario can be undertaken using dynamic loading options available in FLAC3D
A framework for dynamic query re-optimization - Joseph Georges El Sebaaly
No full textThesis (M.S.)--American University of Beirut, Dept. of Computer Science, 2006.;"Advisor: Dr. Jihad Boulos, Assistant Professor, Computer Science--Member of Committee: Dr. Joumana Dargham, Assistant Professor, Computer Science--Member of Committee: Dr. MarBibliography : leaves 103-106.This Thesis provides a framework that dynamically re-optimizes query plans in th e context of data streams. Although many systems have already touched upon this topic, our work provides a novel framework to effectively adapt to changes in th e stream cha
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Task planning strategies for flexible manufacturing cells - by Milad Fares Sebaaly
No full textThesis (M.E.)-- American University of Beirut. Department of Electrical and Computer Engineering, 1994.;"Advisor: Dr. FuadMrad, Assistant Professor, Electrical Engineering -- Members of Committee: Dr. Karim Kabalan, Associate Professor, Electrical EngineBibliography: leaves 114-116.This thesis addresses the planning strategies associated with Flexible Assembly Systems. Its aim is merely to obtain a theoretical representative and practical picture of the performance of some assembly planning tasks and the role of robotic manipulator
Polysaccharides of the red algae "pterocladia" growing on the lebanese coast: Isolation, structural features with antioxidant and anticoagulant activities
No full textIn addition to their high nutritional value, red algae are of great interest as a source of therapeutic substances.
However, despite their abundance on the Lebanese coast red algae have never been studied before. Therefore,
we attempted to study among the available biomass one of the species of red algae growing on the Lebanese
coast “Pterocladia”. We performed the extraction of trace elements, fatty acids, sulfated galactans and watersoluble
polysaccharides of the phycocolloids family (carrageenans) whose physicochemical gelling or
stabilizing effects attract many industrial sectors. The analysis of trace elements shows large amounts of
potassium, calcium, silicon and iron. Moreover, Pterocladia appears to be rich in saturated fatty acids (69%)
with palmitic acid as major fatty acid and 31% of monounsaturated fatty acids. The extraction yields were
2.7% for sulfated galactans and 11.5% for carrageenan. In order to elucidate their structures, H1 NMR
spectroscopy was performed as well as Infra-Red spectroscopy which allowed us to reveal their functional
groups. A study of the antioxidant effect by the electrolysis method showed a greater effect for sulfated
galactans. Furthermore, the study of the anticoagulant effect by APTT test, activated partial thromboplastin
time, showed more pronounced anticoagulant power of sulfated galactans. The results of the present study
confirmed the potential use of the red algae Pterocladia as a source of active known molecules
Variations on the Author
No full text“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
No full textWe 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
No full textWe 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
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
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