3,004 research outputs found
Diego Todaro: Recensione a Red Mirror, il nostro futuro si scrive in Cina (di Simone Pieranni)
No full textCerchar Abrasivity test in tunnelling: a modified version for evaluating the performance of conditioning agents as wear preventers
No full textThe Cerchar Abrasivity test is used for assessing the abrasion of rock due to its simplicity and fast execution and it is considered one of the main wear indexes in tunnelling. Despite in standard condition the test is performed on a dry surface of a rock sample, this study introduces the possibility
to carry out the test on a conditioned surface. In details, this work compares the Cerchar Abrasivity Index (CAI) results of rock specimens subjected to three conditions: dry, saturated with water, and saturated with a polymeric slurry.
First, dry samples were prepared according to the standard procedure while the second and the third sets have been planned in order to simulated the injection of water and polymers respectively, a practise that is nowadays accepted in construction site where rock TBMs are adopted. Results put alight that the use of conditioning such as water and polymeric slurry on the rock leads to a reduction of the wear potential of the rock itself. Notably, the rock specimen treated with the polymer slurry exhibited the lower value of CAI (with a reduction of 34% compared to the dry sample). The potential benefits of use specific preventing-wear polymer in rock excavation is in conclusion analysed
Rozpor ako východisko, láska ako smer u Simone Weilovej (Contradiction as base, Love as direction in writings of Simone Weil)
No full textArticle is explaining contradiction and love, Simone Weil‘s essential terms of hermeneutics of human Being. It introduces close relation of these terms with her understanding of God as well as with her overall concept of religion. Author also mentions Simone Weil‘s inspirations with philosophical and spiritual concepts of the East
Performance analysis of parallel hole-cuts based on dimensionless ratios
No full textFor over 150 years, a wide array of parallel hole-cut patterns for tunnel driving has been designed, tested, and (successfully) used. The geometrical aspect of the parallel cut problem is crucial, and the paper, in its first part, meticulously analyses the correlations linking dimensionless ratios (characterising the patterns) to performance indicators. This rigorous and comprehensive procedure is the most logical way to derive practical general-purpose design rules from the vast array of successfully used patterns. The statistical basis for this analysis is derived from literature and directly observed cases, further enhancing the reliability of the proposed rules. The second part of the paper delves into the sensitivity of pattern performance to drilling precision, a critical factor in pattern selection. Drawing from literature and observed cases, the paper proposes tolerance standards for drilling machinery related to drilling pattern features and highlights their immediate practical relevance. These standards, when implemented, can significantly improve the efficiency and effectiveness of tunnel excavation, demonstrating the practical relevance of this research. The paper succinctly summarizes the investigation’s key findings in the concluding remarks. It highlights the general guidelines and correlations that have emerged from the analysis. These insights guide future tunnel excavation projects, providing a direction for further research and practical application
“I beg you to tell me what has become of Djamila”: The Political Mobilization of Simone de Beauvoir’s Readers During the Boupacha Affair
No full textBy Sophia Millman This is a condensed version of a Masters thesis dedicated to the political mobilization of Simone de Beauvoir’s readers. The citations from the letters were translated from French by the author. *** On June 2, 1960, the French government ordered all copies of the daily Algiers edition of Le Monde seized and destroyed to suppress the publication of Simone de Beauvoir’s article “Pour Djamila Boupacha.” Beauvoir, a self-professed “woman of letters”, not “of action[1]”, and one ..
A comparative study of form and theology in the works of Flannery O'Connor and Simone Weil
No full textIn this comparative study of the form and theology of Flannery O'Connor and Simone Weil I interrogate how Weil's philosophical writings and her theology illuminate O'Connor's use of both narrative and non-fictional forms, and her Catholicism. The Introduction analyses how Weil's concept of superposed reading provides a new method of approaching both O'Connor, her writings, and O'Connor
studies, and focuses on how such apparently different women interconnect. Chapter One explores how both Weil and O'Connor attempt to write their theologies on the
souls of their readers yet are each subject to constraints imposed by form. Weil's concept of locating equilibrium between incommensurates is discussed, and her
distinctively philosophical approach to fictions and fictionality is used to investigate O'Connor's notion of prophetic fictions and the writer's role. Chapter Two assesses how both writers revivify Christian paradoxes. Weil's monstrous concept of affiiction, and O'Connor's use of the grotesque genre to jolt secular man into an
awareness of the sacred are scrutinised. Chapter Three studies how both writers consider an encounter between God and man is possible through the action of grace. My Conclusion interrogates how Weil's work can deepen our understanding of O'Connor's writings, and examines how successful O'Connor is at realising a truly
Christian literature. I conclude that despite being a writer of powerful fictions, O'Connor can not be totally successful in her mission as writer-prophet because
ultimately fiction escapes orthodoxy
The phenomenon of tools’ wear in a marble quarry: laboratory tests to evaluate the performance of conditioning as a wear preventer
No full textExploitation with a chain saw cutting machine has been the ordinary industrial practice in marble excavation for over thirty years, due to its ability to adapt to difficult environments and to guarantee a high level of safety during the cutting phase. Nevertheless, the presence of impurities in the calcite matrix, e.g. quartz, leads to the problem of rapid and unusual wear on cutting tools. In this study, two laboratory tests were selected and carried out to estimate the rock's wear potential: the CERCHAR Abrasivity test and the Soil Abrasion Test Apparatus (SATA). The results highlight a high degree of abrasivity in dry conditions, which was satisfactorily reduced by using water and additives. This mixture, typically used in tunnelling applications, is intended to decrease the wear from rock excavation and a significant reduction of this phenomenon has been noticed
An analysis of metal wear in rock excavation by TBM
No full textAbrasivity, or its reciprocal concept, “wear resistance”, are not intrinsic proper-ties of a material, but rather parameters describing the interaction of two materials, i.e. the wear part and the material exerting the wearing action. Moreover, “wear” or, at least, that part of the wear, which is due to the cumulated effect of minute scratches, is linked to the “hardness dispar-ity” concept: an example is provided by the well-known Mohs hardness scale (the “harder” body wears the “softer” body). In the case of rock-metal interaction, a difficulty arises from the inhomogeneity of the interacting bodies. The paper, after a synthetic explanation of the basic principles, deals first with the problem of measuring and representing the hardness of inhomo-geneous bodies; a simple procedure is described, with practical examples. Then, after a review of data on TBM disc service life and rock abrasivity evaluation, cases of TBM used in hydropower tunnel driving in Italy are presented. Data pertaining to the rock bored and to the metal compos-ing the discs, together with machine data, tools consumption and machine productivity are pro-vided and compared to find correlations enabling to forecast tools service life
Precision Rock Excavation: Beyond Controlled Blasting and Line Drilling
No full textThe strictness of the result of an excavation, whether mechanical or by means of explosives, is naturally conditioned by its objective and, therefore, by the type of technique applied to achieve it. To attain the best results in terms of rock breakage, and with respect to the final profile, it is important to evaluate the specific excavation energy and its optimization. This study, being a revision of different techniques to achieve good quality of the final walls, focuses on evaluating the effects of those techniques on the quality of the result, in both open-pit and underground operations. Different geometries and configurations can be applied to both quarrying and tunneling blasts. This study aims to push contour blasts to their limits, and the main aspects are discussed in order to improve the blast parameters in daily practice
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