Two different pre-conditioning techniques have been applied at the Sur Andes mine sector (SuaPi) of the El Teniente mine in order to improve caving performance of the primary copper ore, which can be ...considered as a typical heavily veined massive, competent and unfractured rock masses. Hydraulic fracturing (HF) and blasting under confined conditions (BUCC) have been applied to a significant portion of the ore column to be mined. Both techniques introduce new open fractures into the massive rock mass with the aim of improving fragmentation performance at the draw points.
A range of rock mass characterisation activities were undertaken before and after pre-conditioning took place in order to evaluate any change in rock mass condition. These geotechnical campaigns included both drill core logging and borehole camera (BHC) inspection and mapping. Mapping of the borehole walls allow the identification of the massive rock mass including the healed veins, the sub-horizontal HF fractures and also the sub-vertical (both radial and concentric to the blast hole) BUCC fractures.
Using these rock mass characterisation properties, a Discrete Fracture Network (DFN) model was developed for both HF and BUCC fractures in order to quantify the occurrence of new open fractures within the primary ore. The DFN models allow the estimation of in situ fragmentation following preconditioning and these data were compared with fragmentation performance measured at the draw points in the SuaPi mine Sector. This paper presents the results of the pre-conditioning on the rock mass, the DFN modelling procedure undertaken (particularly the BUCC fractures), the characterisation of the preconditioning intensity and how it is related to the fragmentation performance at the SuaPi mine sector.
A program developed in MATLAB® is presented; the function of this program is to reproduce the music that is contained in a sheet of music. Initially, the program only uses the G- Clef and for the ...notes only the Semibreve, Minim, Crochet, and Quaver are taken into account. A description of the program function is given, and then the results of the program are analyzed. Finally future work is proposed in order to increase the robustness and scope of the program.
The LAGO (Latin American Giant Observatory) observatory is an experiment that spans over Latin America in a wide range of latitudes that gives different rigidity cut offs for the enter of cosmic rays ...in the atmosphere. The motivation of the Observatory is to study atmospheric radiation and space weather through the measurement of the secondary emission of low energy cosmic rays at ground level using Water Cherenkov Detectors (WCD). This work presents the contributions of the LAGO collaboration to the 2019 36th ICRC.
Recensión de la obra de: ANGHEL, B. Y VÁZQUEZ VEGA, P., ARGANDOÑA RÁMIZ, A., FERNÁNDEZ DÍAZ, A., HURTADO JORDÁ, J., LABEAGA AZCONA, J. M., LIZCANO ÁLVAREZ, J., MOYANO JURADO, C., PELÁEZ MARTOS, J. ...M., SERRANO SANZ, J. M., SOLÉ I PUIG, C. (2010), Implicaciones de la economía sumergida en España. Madrid, Editorial Círculo de Empresarios, 273 pp.
To study the prevalence os smoking in school children in Sevilla and the influence of personal and social environment on smoking patterns.
This study was part of a preventative anti-smoking campaign ...in schools. Students filled in anonymous questionnaires based on the World Health Organization survey instrument for population attitudes and habits.
We surveyed 3385 students between 10 and 19 years of age at 47 schools in Seville and 28 villages in the surrounding province. Current smoking was reported by 19.1% of the students; slightly more girls (19.8%) than boys (18.3%) smoked. Smoking was related to having an older brother or sister who smoked and particularly to having friends who smoked (OR 20.5). The adolescents reported that parents were less permissive than the rest of their environment. Smokers associated tobacco with values such as independence and freedom; they believed that smoking might have an impact on health, although their conviction was less strong than that of non-smokers, regular smokers had high expectations of continuing.
We found a high proportion of smokers among students of both sexes. Starting and continuing to smoke during adolescence is considerably influenced by the social environment of peers and is possibly affected by messages of independence and freedom transmitted through tobacco industry advertising.
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