1,721,066 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Thermo-rheological analysis of WMA-additive modified binders
Get PDFThermo-rheological characteristics of unmodified and modified bitumen have significant impacts on the mechanical response of asphalt. This study investigates the impacts of an organic and a chemical Warm Mix Asphalt additive on bitumen thermo-rheological and mechanical characteristics. Modified binders with different concentrations of each additive were studied and analysed comparatively to a 40/60 penetration grade bitumen. Frequency sweep tests were performed at different ageing levels to characterise the Linear Viscoelastic properties. The multiple stress creep and recovery, linear amplitude sweep (LAS) and low temperature creep stiffness tests, together with the Glover–Rowe (G–R) fatigue parameter (determined from fitting of the 2S2P1D model to the complex shear modulus and phase angle master curves) were used to analyse the performance of the binders at critical operating temperatures. The results demonstrated the necessity to analyse the behavior of the studied binders beyond the limits of linear viscoelasticity to better characterise these types of bitumen. The results also indicated that both additives retarded bitumen ageing with the organic additive increasing bitumen elastic response while the chemical additive increased its viscous response. The results also showed an excellent correlation between the G–R parameter and LAS results which suggests the ability to use this parameter in characterising fatigue performance of the studied binders. This also suggests that bitumen fatigue life may be improving over time due to the increased elastic behahviour during ageing so long as a certain critical level of ageing is not reached
An Evaluation of the Springbox test for Unbound Materials
No full textThe Springbox is a relatively new piece of equipment, designed to generate realistic values of modulus for
use in pavement design. The specimen, which can be of soil, granular or lightly stabilized material, is a 17cm
cube, confined by steel sides, two of which are spring-loaded and free to move during the test. Repeated
load is applied vertically through a full-face loading plate. Detailed descriptions are given elsewhere, but this
paper will include an overview of the equipment. However, the principal content of the paper concerns an
evaluation of the true meaning of the test based both on comparisons between Springbox data and on finite
element analysis (FE) of the stress conditions within the specimen. The comparative test data are obtained
on three different granular materials (Clay soil, Sub-Base and Cement Treated Base). The FE analysis was
performed using experimentally obtained values of resilient modulus and Poisson’s ratio and comparing the
simulation with the real test in terms of longitudinal and vertical strain in order to assess the FE model.
Reference is then made to the FE analysis of the equipment in order to explain the material’s local behaviour
inside the specimen with respect to the global mechanical behaviour, which is evaluated during the test by
means of point measurements, which are, therefore, assumed to be representative of the stress and
deformation state of the material. The model is able to take into account the effect of friction between the
steel sides and the material (cf = 0.4), which can highly affect the interpretation of results. Moreover, a FE
parametric study was carried out under different static and dynamic load conditions on unbound materials
with different characteristics. Finally, conclusions are drawn regarding the potential use of the equipment in
generating values of stiffness modulus for design
Variations on the Author
Get PDF“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
Get PDFWe 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
Design considerations of high RAP-content asphalt produced at reduced temperatures
Get PDFIn many countries recycling of reclaimed asphalt pavement (RAP) for road surface layers is limited to a maximum of 10–30%. This is due to technical limitation of common asphalt plant but also to specifications that are still restrictive when it comes to increasing RAP in surface courses. The mistrust in this practice is mainly related to uncertainty in performance of these mixes as well as to existing fundamental issues with the mix design, especially when production temperatures are lowered. This paper analyses some of the factors affecting the design of warm asphalt mixtures for surface course layers containing 50% RAP, and suggests a framework to justify the common assumption of full blending by optimising production conditions. A control hot mix asphalt which was manufactured with 49 dmm penetration binder and asphalt mixtures containing 50% RAP produced at temperatures between 95 and 135 °C and at different mixing times were investigated in terms of volumetric properties, indirect tensile stiffness modulus, and indirect tensile strength. The high-content RAP mixtures were produced within the warm mix region by using only a very soft binder as a rejuvenator, which reduces production costs. Statistical analysis was deployed, and different models were developed to estimate degree of blending between RAP binder and rejuvenator binder, and to predict the equivalent penetration of the blend without binder extraction and recovery. The analysis results showed that the selected performance indicators correlate significantly with mixing time and temperature, and provide evidence that only in certain circumstances and if the production conditions are accurately controlled, the practical full blending approach is acceptable
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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