969 resultados para Underground cables


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Fluctuations of trace gas activity as a response to variations in weather and microclimate conditions were monitored over a year in a shallow volcanic cave (Painted Cave, Galdar, Canary Islands, Spain). 222Rn concentration was used due to its greater sensitivity to hygrothermal variations than CO2 concentration. Radon concentration in the cave increases as effective vapour condensation within the porous system of the rock surfaces inside the cave increases due to humidity levels of more than 70%. Condensed water content in pores was assessed and linked to a reduction in the direct passage of trace gases. Fluctuations in radon activity as a response to variations in weather and microclimate conditions were statistically identified by clustering entropy changes on the radon signal and parameterised to predict radon concentration anomalies. This raises important implications for other research fields, including the surveillance of shallow volcanic and seismic activity, preventive conservation of cultural heritage in indoor spaces, indoor air quality control and studies to improve understanding of the role of subterranean terrestrial ecosystems as reservoirs and/or temporary sources of trace gases.

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This paper focuses on the cave houses of Crevillente (Spain) as a traditional housing experience which takes advantage of local environmental conditions through simple architectural proposals, paying particular attention to the presence of radon gas inside these underground constructions. Our aim is twofold: first, to analyse the architectural conditions of the different excavated typologies found in the municipality and second, to relate them to the existing radon gas levels after checking internal concentration by means of E-PERM® long-term devices placed inside the cave houses in 2011. The measurements corresponding to the main typologies in normal use conditions show that the highest values are 881.9 Bq/m3 in the cave typology, 484.1 Bq/m3 in the cave + attached constructions typology and 373.4 Bq/m3 in the cave + house typology, with geometric mean values of 572.1, 114.0 and 75.5 Bq/m3, respectively. It can be inferred from these results that cave house levels sometimes exceed those included in the 90/143/Euratom European Commission Recommendation on the protection of the public against indoor exposure to radon. The reason why cave houses are more susceptible to radon accumulation in their spaces lies in their direct and permanent contact with the ground where they are located.

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Combustion runs at 700 °C in a horizontal laboratory furnace were carried out on two different electric wires (PVC and halogen-free wire). Tests were performed in the presence and in the absence of the metal conductor of the wires. The analyses of the polycyclic aromatic hydrocarbons (PAHs), chlorobenzenes (CBzs), chlorophenols (CPhs), mono- to octa-chlorodibenzo-p-dioxin and dibenzofurans (PCDD/Fs), and dioxin-like PCBs are shown. Regarding semivolatile compounds, PAHs production decreases in the presence of metal, while a higher amount of chlorinated compounds are emitted. Respect to the PCDD/Fs, the PVC wire in the presence of metal presents the highest emission, with a much more emission of furans than dioxins. The maximum emission is with 2 or 3 chlorine atom PCDD/Fs. PCBs emission correlates with PCDD/F production and represents 3–4% of total toxicity, determined by using WHO2005 factors.

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Cette approche histométrique traite la description des tissus constituants les êtres vivants de deux espèces végétales vivaces (Lygeum spartum et Ammophila arenaria). Elle permettra d’aider à comprendre certainement le comportement tant morphologique que physiologique de l’espèce vivante dans un biotope naturel. Présentant des racines adaptatives à l’absorption de l’eau et des sels minéraux du sol, ces deux espèces montrent une fixation de la plante au substrat et à l’accumulation des réserves. Elles sont sous la dépendance de corrélations com plexes (trophiques, hormonales) qui s’établissent entre l’appareil souterrain et l’appareil aérien. L’étude histométrique du Lygeum spartum et d’Ammophila arenaria nous a permis de déterminer une nette différence entre les tissus des deux espèces. Pour Ammophila arenaria, il existe de très bonnes corrélations pour la majorité des tissus, expliquant ainsi une croissance cellulaire qui existe entre ces différents tissus.Le coefficient de corrélation est faible entre les différents tissus du Lygeum spartum. Le développment des tissus de celle-ci n’est pas synchrone, il montre toute même une certaine hétérogéneité au niveau du développement tissulaire des racines.

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Excavated towns are an attractive example of underground urbanism that managed to solve, in a very interesting way, thermal problems thanks to natural ground inertia or transition spaces. The aim of this paper is to show the typological evolution of excavated dwellings worldwide, as an architectural proposal and urban solution. The proposed methodology provides an analysis of underground architectures from natural caves to excavated housing, focusing on the study of global constructive solutions to specific problems. Thus, architectures as a natural geography correction (horizontal excavation), buried underground architectures (vertical excavation), subtractive architectures (shallow excavation) and combined architectures (mixed excavation) are studied. In conclusion, there are many examples of typological combinations since troglodyte architects tried to adapt the most elementary constructive rules to get greatly enriched results. These proposals of different underground structures deal with each territory and its geographical features, and obtain urban and architectural solutions transferable to current configurations.

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Underground architecture has sheltered man for many centuries, but the current need to emphasize the bioclimatic approach makes the study of excavated housing essential. This traditional construction is a part of the collective human living experience but also a reference in using the natural conditions of each region through simple proposals based on ground thermal inertia. The aim of this paper is to show the typological evolution of the excavated dwelling in Crevillente, in southeast Spain, compared to other worldwide architectural proposals or urban solutions. To show their adaptation to the regional geography and to comprehend both formal and material characteristics of these simple typologies, which do not need extra energy contribution for interior conditioning. This work is part of the doctoral thesis of the author.

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Se estima que las viviendas subterráneas a lo largo del mundo albergan entre 40 y 60 millones de personas. Tras un análisis general de las tipologías de viviendas subterráneas, de su localización y de los factores que influyen en su desarrollo se ha introducido el análisis de la vulnerabilidad de este tipo de viviendas ante los riesgos naturales, cuestión que no ha sido estudiada exhaustivamente con anterioridad. Cabe destacar que la localización de las viviendas subterráneas a lo largo del mundo coincide en la mayor parte de los casos con regiones activas sísmicamente, por lo que se lleva a cabo una primera aproximación al estudio de la vulnerabilidad de las viviendas subterráneas frente al riesgo sísmico, teniendo como antecedente el terremoto de la región china de Shaanxi ocurrido en 1556, que afectó a grandes agrupaciones de viviendas subterráneas.

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This layer is a georeferenced raster image of the historic paper map entitled: Philip's new plan of London, 1873. It was published by George Philip & Son in 1873. Scale [ca. 1:18,900]. The image inside the map neatline is georeferenced to the surface of the earth and fit to the British National Grid coordinate system (British National Grid, Airy Spheroid OSGB (1936) Datum). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as roads, railroads and underground tramways, railway stations, drainage, selected buildings and industry locations, built-up areas, postal districts, parks, cemeteries, docks, and more. Relief is shown by hachures. Includes legend. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

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This paper describes the design, tuning, and extensive field testing of an admittance-based Autonomous Loading Controller (ALC) for robotic excavation. Several iterations of the ALC were tuned and tested in fragmented rock piles—similar to those found in operating mines—by using both a robotic 1-tonne capacity Kubota R520S diesel-hydraulic surface loader and a 14-tonne capacity Atlas Copco ST14 underground load-haul-dump (LHD) machine. On the R520S loader, the ALC increased payload by 18 % with greater consistency, although with more energy expended and longer dig times when compared with digging at maximum actuator velocity. On the ST14 LHD, the ALC took 61 % less time to load 39 % more payload when compared to a single manual operator. The manual operator made 28 dig attempts by using three different digging strategies, and had one failed dig. The tuned ALC made 26 dig attempts at 10 and 11 MN target force levels. All 10 11 MN digs succeeded while 6 of the 16 10 MN digs failed. The results presented in this paper suggest that the admittance-based ALC is more productive and consistent than manual operators, but that care should be taken when detecting entry into the muck pile

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Far-field stresses are those present in a volume of rock prior to excavations being created. Estimates of the orientation and magnitude of far-field stresses, often used in mine design, are generally obtained by single-point measurements of stress, or large-scale, regional trends. Point measurements can be a poor representation of far-field stresses as a result of excavation-induced stresses and geological structures. For these reasons, far-field stress estimates can be associated with high levels of uncertainty. The purpose of this thesis is to investigate the practical feasibility, applications, and limitations of calibrating far-field stress estimates through tunnel deformation measurements captured using LiDAR imaging. A method that estimates the orientation and magnitude of excavation-induced principal stress changes through back-analysis of deformation measurements from LiDAR imaged tunnels was developed and tested using synthetic data. If excavation-induced stress change orientations and magnitudes can be accurately estimated, they can be used in the calibration of far-field stress input to numerical models. LiDAR point clouds have been proven to have a number of underground applications, thus it is desired to explore their use in numerical model calibration. The back-analysis method is founded on the superposition of stresses and requires a two-dimensional numerical model of the deforming tunnel. Principal stress changes of known orientation and magnitude are applied to the model to create calibration curves. Estimation can then be performed by minimizing squared differences between the measured tunnel and sets of calibration curve deformations. In addition to the back-analysis estimation method, a procedure consisting of previously existing techniques to measure tunnel deformation using LiDAR imaging was documented. Under ideal conditions, the back-analysis method estimated principal stress change orientations within ±5° and magnitudes within ±2 MPa. Results were comparable for four different tunnel profile shapes. Preliminary testing using plastic deformation, a rough tunnel profile, and profile occlusions suggests that the method can work under more realistic conditions. The results from this thesis set the groundwork for the continued development of a new, inexpensive, and efficient far-field stress estimate calibration method.

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In the tropics, bats are an essential component of many native ecosystems, through providing various ecological services including pollination and insect pest control, in addition to seed dispersal. Many Philippine bat species roost in caves and underground habitats. However, many caves are disturbed by people, to exploit resources for food, recreation, and mineral and guano extraction. The misunderstanding of the importance of bats to the ecosystem is also considered a threat to many cave roosting species. Understanding the conflicts between humans and ecosystems which provide essential services is important to maintain ecosystem service provision. A total of 100 local respondents from the village of Pisan, Kabacan North Cotabato in south central Mindanao were interviewed through semi-structured interviews and focus group discussions. Respondents were asked about their views, levels of knowledge, use, interaction, and awareness towards both the caves and bats in their locality. Our survey found that most of the respondents are aware of the presence of bats from the caves in their locality. Unfortunately, a large proportion of the respondents noted that bats are hunted in caves for bush meat and trade, and most people perceived bats as pest to fruit crops such as durian. These factors are among the main factors of the execution of many bat colonies in caves of south central Mindanao. In general, cave bats are under appreciated species in caves. The unregulated tourism, hunting for bush meat and trade, and guano extraction are among the alarming threats occurring for both caves and bats in the locality and possibly to other localities in the country. Furthermore, the establishment of strong and effective model conservation education programs and the strengthening the participation of local government, academic, and community are essential steps to preserve the current state of cave bats in the area.

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The effects of climate change and the growing demand for water for domestic, industrial, agricultural and recreational activities have been led the use of treated wastewater (reclaimed water) for such applications. The artificial recharge of aquifers with treated wastewater can be an alternative way for restoring underground water volumes that can be used for satisfying some activities, particularly in water shortage areas or where their quality is not suitable for use. After a two-year monitoring period in the Vila Fernando WWTP (Guarda, Portugal), the characteristics of the treated effluent suggest that it could be used for infiltration for aquifer recharge. A multi-criteria analysis based on GIS was developed for site location of infiltration sites. The procedure has involved the combination of six thematic maps and environmental, technical and economic criteria, over an area of 6687.1 ha. About 6.4 ha were selected for suitable sites for infiltration and one of these sites (Quinta de Gonçalo Martins, Guarda) was selected for collecting soil samples. The characterization of the soil indicates that is favorable to the infiltration of treated wastewater for artificial recharge of aquifers.

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Tese de mestrado em Geologia Aplicada, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016

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Tese de mestrado, Geologia Aplicada (Hidrogeologia) Universidade de Lisboa, Faculdade de Ciências, 2016

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Tese de doutoramento, Geologia (Hidrogeologia), Universidade de Lisboa, Faculdade de Ciências, 2016