1,726,723 research outputs found
Consequences of drying on the hydro-mechanical response of fibrous peats upon compression
Full text linkPeats are encountered in waterlogged deltaic areas, where degradation is delayed by favourable environmental conditions. The recent increase in frequency and severity of droughts is expected to accelerate peat degradation, in turn increasing subsidence and flood risk, urging better understanding of the response of peats to drying events. To this aim, compression tests on natural and reconstituted peat samples were performed, supported by X-ray micro-computed tomography. The peat fabric
was found to be the key factor in the response to drying, with fibres playing the most significant role. Drying in peats starts affecting the macro-fabric, with an irreversible reduction in volume and disruption of the fibrous network occurring under saturated conditions until a threshold void ratio is reached, below which desaturation occurs of the intra-fibres and intra-peds pores. The first drying stage dramatically decreases the compressibility, while the hydraulic conductivity is hardly affected due to the enlargement of macropores. Secondary compressibility is affected by the peat fabric besides the organic content. The total organic content does not change substantially during drying; hence, it is not the best proxy to describe the consequences of drying on the response of fibrous peats. The fibre content can be better used to serve the aim
Experimental investigations on controlled auto-ignition combustion in a four-stroke gasoline engine
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The effects of air and exhaust gas dilution on the CAI combustion of a range of fuels including three gasoline compositions, four primary reference fuels, and two alcohols are experimentally investigated using a single cylinder research engine. Two of the three gasolines tested are manufactured from standard gasoline during engine operation by a novel fuel system, designed to improve the performance of both controlled autoignition and spark ignition engines. A series of experimental tests are performed to establish the satisfactory combined air and exhaust gas dilution regions for each fuel. Detailed in-cylinder pressure and exhaust gas speciation measurements are taken, and the fuels are compared and contrasted for their performance in terms of power output, fuel consumption, and harmful exhaust emissions. Results show that alcohol fuels are superior to hydrocarbon fuels for controlled autoignition combustion because their autoignition characteristics are less affected by the presence of exhaust gas species. Furthermore, the timing of autoignition is shown to be of minor importance for achieving efficient and stable controlled autoignition combustion, contrary to widely held beliefs. In addition, the novel fuel system is developed and commissioned for use on a single cylinder research engine operating with a spark ignition system. The two gasoline fuels produced by the system are evaluated individually for their knocking combustion characteristics over a range of compression ratios and spark advances. Results from these tests indicate that the fuel system used in conjunction with a specially modified production engine may allow the normal compression ratio of that engine to be increased by up to 1.0, increasing its efficiency.Financial support obtained from Ford Motor Company
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Flux ratios as a probe of dark substructures in quadruple-image gravitational lenses
No full textWe demonstrate that the flux ratios of quadruple-image lensed quasars provide a powerful means of probing the small-scale structure of dark matter halos. A family of smooth lens models can precisely predict certain combinations of flux ratios using only the positions of the images and the lens as inputs. Using five observed lens systems, we show that real galaxies cannot be described by smooth singular isothermal ellipsoids, nor by the more general elliptical power-law potentials. Large-scale distortions from the elliptical models cannot yet be ruled out. Nevertheless, we find by comparing with simulations that the data can be accounted for by a significant (≳5%) amount of dark substructures within a projected distance of several kiloparsecs from the center of the lenses. This interpretation favors the cold dark matter model over the warm or self-interacting dark matter models
- …
