1,720,956 research outputs found
Bank stability for predicting reach-scale land loss and sediment yield
No full textWhen extensive lengths of river become stabilized (e.g., by channel incision), riverbank erosion can result in considerable riparian land loss and the delivery of large volumes of sediment downstream. The ability to predict the stability and failure geometry of eroding riverbanks is therefore an important prerequisite in estimating the rate of bank erosion and sediment yield associated with bank erosion. In this paper, a new stability analysis for layered river banks is introduced. The new analysis differs from many previous analyses in that it takes into consideration the effects of positive pore water pressure in the saturated portion, and negative pore water pressure in the unsaturated portion, of the bank as well as the influence of hydrostatic confining pressure due to the water level in the river. In addition, the failure plane is not constrained to pass through the toe of the bank and the bank profile geometry is not restricted to an idealized special case. The predictive ability of the new bank stability analysis is assessed using data from two field sites. Subsequently, a methodology for applying the bank stability analysis at the scale of the river reach (0.1 to 10 km) is discussed. This method involves the use of empirical models of bed level adjustment to estimate the magnitude of incision at specific locations along the reach, with these estimates used to drive the stability analysis. Application of the new method is demonstrated with an example
An appraisal of the Southern Valley Development Project in Egypt
No full textThe increasing population in Egypt is leading to overcrowding in the Old Valley and delta area. The per capita reduction in arable land and water is likely to lead to serious problems. Egypt's chosen solution to this problem is the development of Southern Egypt. This will be known as the Southern Valley Development Project (SVDP) and will involve the irrigation and colonising of an area to the north-west of lake Nasser over a period of 30 years. This will increase the occupied area of the country from 4% to 24%. The area will be supplied with water via a new canal known as the South Valley Canal. It is planned to reclaim 0.21m?ha by the year 2002, and at the end of the project some 1.43m?ha will have been reclaimed. The surface water requirement of the project is 5bn?m3, this will be provided by a strict water saving policy which aims to save about 11bn?m3. The first part of this paper describes the background and detail of the project with particular regard to water resources. The latter part examines the pros and cons of the project highlighting some areas of concern.<br/
Measurement of road surface texture: an examination
No full textThis paper discusses the measurement of road surface texture and specifically the use of the standard sand patch test as a method to determine whether a road surface lies within contractual texture tolerances. The test is criticized by the industry due to the variability of the results which can be obtained. A series of tests on concrete specimen tiles with brushed and exposed aggregate finishes has been conducted which demonstrates the problem...<br/
Climatic impact assessments
No full textThis paper proposes that all new construction or development projects should be subjected to a climatic impact assessment (CIA) as part of the design process. CIA is a procedure that assesses the impacts of all the effects of future climate change on a proposed project, that is the effect of the environment on the development. This is the opposite of an environmental impact assessment, which examines the effect of the development on the environment. The outcome of a CIA will be recommendations to ensure that the project will perform satisfactorily over its designed life span. This paper details the philosophy and mechanisms that constitute a CIA
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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