1,721,235 research outputs found
Practical Design of Nongrouted Micropile Foundations Based on Monte Carlo Analysis
No full textThe main objective of the present paper is the application of a design method, traditionally used for medium- and large-diameter piles, to nongrouted hollow steel bar micropiles with very small diameters. The compressive resistance of this piling system, which is generally used for underpinning works, can be controlled during installation. The adopted analytical design method is based on the results of cone penetration tests to calculate the resistance of the micropiles under compression. Thanks to the availability of field data from micropiles installed at different sites, it was possible to fit the analytical method and to compute the characteristic value of micropile resistance. A Monte Carlo analysis has been used to test the reliability of the method and determine the reduction correlation factor for the calculation of the characteristic resistance. The obtained results show how the analytical method can be effectively adopted for micropiles installed in prevalently coarse-grained soils. An appropriate value of the correlation factor that fulfills the reliability requirements has been derived. On the one hand, this correlation factor is only slightly lower than that prescribed by European regulations (Eurocode 7); on the other hand, it appears much less conservative than that prescribed by the Italian Code. The adopted statistical approach appears rather promising to develop appropriate design methods for similar micropile systems in different soils
A simplified model for the evaluation of the degree of saturation in slope stability analysis of shallow soils
No full textIt is well known that the degree of saturation of a soil is time-varying in consequence of atmospheric conditions. Experimental data of matric suction at a site in Pilastro, Parma, Emilia Romagna Region, Northern Italy, have been used to compare against a simplified model, which is able to directly correlate the degree of saturation of a clayey-silt soil with rainfall events. The paper deals with the in-situ measurements of matric suction, the procedure to obtain the degree of saturation on the basis of assumed soil-water retention curves and comparison against the simplified model. This model, in turn, has been introduced in a simplified physically based stability method, recently set up by the authors to describe the most important factors influencing the rainfall-triggered mechanism of shallow landslides. © 2008 Taylor & Francis Group, London
The potential role of European professors in the context of Rwandan civil engineering education: Reflections after a teaching experience
Full text linkThe number of students in civil engineering in some sub-Saharan African developing countries is stronglyincreasing, as consequence of an increasing demand of their capabilities. However, current efforts to educate civilengineers in Africa and, specifically, in Rwandan higher education institutions are hindered by the lack of localqualified teachers. On the other hand, in some European countries, university teachers are increasingly consid-ering the effects of globalization on both civil engineering education and profession. In this situation, theeducational potential of a European teacher can gain an innovative perspective, since it would be of great use if itwere beneficial to a big number of students in a country where qualified teachers are scarce. It cannot be hiddenthat thanks to such a change of perspective, the inner motivation to carry out academic activity would alsobenefit.The Authors try answering three main questions: In which way a European teacher can contribute to civilengineering education in sub-Saharan Africa, with particular reference to the Rwandan context? What impact cana European type of teaching have in the Rwandan context, especially with regard to the methodologicalapproach? How do Rwandan students perceive a learning experience with different characteristics from the usualones?Beyond writing a report of the activities done during a personal teaching experience of one of the authors in aRwandan university, this paper aims at explaining the lesson learnt from this experience, under both human andprofessional viewpoint. Although the experience of a single teacher has proved to be a privileged way to build alarger project in the framework of the Erasmus Plus program, which was subsequently eligible for funding, thispaper is not focused on the network construction, but only on the preceding indispensable step. In fact, the paperdescribes on the one hand the challenges faced by the teacher during a direct teaching experience and, on theother hand, the results obtained and the perception by the students, expressed through an evaluationquestionnaire.The paper proposes an example of successful and profitable experience of a European professor in thefield ofcivil engineering in the context of a Rwandan higher education institution, with the awareness that it cannotbecome paradigmatic of a wider academic practice orientation, but at least an example of a professional way ofbeing. This model offers opportunity of knowledge sharing, in the wider perspective of future Rwandan devel-opment, but it is also an opportunity for exchange in terms of culture and values
A model for triggering mechanisms of shallow landslides
No full textRainfall-induced shallow landslides, also called "soil slips", are becoming ever more frequent all over the world and are receiving a rising interest in consequence of the heavy damage they produce. At the University of Parma, a simplified physically based model has been recently set up for the evaluation of the safety factor of slopes which are potentially at risk of a soil slip. This model, based on the limit equilibrium method applied to an infinite slope, takes into account some simplified hypotheses on the water down-flow and defines a direct correlation between the safety factor of the slope and the rainfall depth. In this paper, this model is explained in detail and is used in a back analysis process to verify its capability to foresee the triggering instant of rainfall-induced shallow landslides for some recent case studies in the Emilia Romagna Apennines (Northern Italy). The results of the analyses and of the model implementation are finally shown
Predicting landslide susceptibility and risks using GIS-based machine learning simulations, case of upper Nyabarongo catchment
Full text linkSustainable landslide mitigation requires appropriate approaches to predict susceptible zones. This study compared the performance of Logistic Model Tree (LMT), Random Forest (RF) and Naïve-Bayes Tree (NBT) in predicting landslide susceptibility for the upper Nyabarongo catchment (Rwanda). 196 past landslides were mapped using field investigations. Thus, the inventory map was split into training and testing datasets. Fifteen predisposing factors were analysed and information gain (IG) technique was used to analyse the correlation between factors and observed landslides. Therefore, the area under receiver operating characteristic (AUROC) with other statistical estimators including accuracy, precision, and root mean square error (RMSE) were employed to compare the models. The AUC values were 78.7%, 80.9% and 82.4% for RF, LMT and NBT models, respectively. Additionally, the NBT produced the highest accuracy and precision values (0.799 and 0.745, respectively). Regarding RMSE values, the NBT model achieved an optimized prediction than RF and LMT models (0.301; 0.428 and 0.364, respectively). The results of the current study may inform further studies and appropriate landslide risk reduction and mitigation measures. They can also be instrumental for policy and decision making in regards with natural risk management
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
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