226 research outputs found
Rediseño y fabricación de semirremolque bombona con acero de alta resistencia en la empresa Famedi SAC
No full textUn semirremolque bombona (SB) se define como un medio de transporte que es
remolcado por una unidad motora. Estos elementos se utilizan para el transporte
de materiales de diversa naturaleza. Una aplicación común es para transportar
explosivos en forma líquida, llamado con el nombre genérico de "emulsión matriz"
hasta una capacidad de 26.5 metros cúbicos y se fabrican en empresas
carroceras dentro del territorio nacional. Estas unidades se han rediseñado
tienen las siguientes partes principales: sistema de suspensión neumática, que
se encarga de absorber las cargas de las irregularidades del terreno en su
trayecto; el chasis, es la estructura que soporta las cargas dinámicas y estáticas
de toda la unidad; y un cilindro cónico (casco), recipiente que contiene el producto
a transportar. Para el análisis estructural se usó el Método de los Elementos
Finitos (MEF) a toda la estructura de un semirremolque bombona para transporte
de explosivos en forma líquida. Para la estimación de cargas no existe normas
nacionales, por lo tanto, se considerarán dos estándares internacionales: ADR
2015 y la norma norteamericana CFR, los cuales están detallados en el marco
teórico, se logró bajar el peso del SB en 800kg, además se aumentó la carga útil
de 23 m3 a 26.5 m3 el esfuerzo máximo obtenido es de 392Mpa, y una
deformación de 17mm los cuales no afecta el funcionamiento.Tesi
Cómo vamos a vivir juntos?
No full textThis book by Alejandro Aravena explores the critical question of coexistence in modern societies, particularly in the context of urban planning, social participation, and the collective challenges we face in the 21st century. The book originates from a keynote speech given by the author at the Chilean Constitutional Convention in 2021, where he reflected on the future of society and urban development over the next century.
Drawing from his extensive experience in architecture and participatory design, Aravena presents key lessons learned through real-world projects and community engagement. These principles emphasise the importance of inclusive urban planning, equitable resource distribution, and the balance between regulation and self-regulation. The book argues that solving complex social issues requires more than just good intentions. It demands a deep understanding of diverse perspectives and a willingness to embrace dialogue and collaboration.
A central theme is the idea that neither the market nor the state alone can provide sustainable solutions for urban and social challenges. Instead, the book advocates for a "third way" that trusts in people's agency, acknowledging their role as active contributors to the built environment rather than passive recipients of top-down policies. The text highlights the need to shift from mere tolerance to genuine admiration for cultural diversity, particularly in the context of the Chilean-Mapuche relationship. To this aim, the author explores the potential of indigenous knowledge, historical negotiation practices, and the power of storytelling in shaping a shared future.
By blending architectural insight with sociopolitical analysis, this book serves as a manifesto for collective responsibility, urging readers to rethink how cities, policies, and communities can be designed to foster sustainable and harmonious living conditions
Hydrodynamic and isotopic characterization of a site contaminated by chlorinated solvents: Chienti River Valley, Central Italy
No full textContaminant sources have been attributed to shoe manufacturers in an alluvial aquifer located along 26km2 in the Chienti River Valley, Central Italy. During the 1980s and 1990s, the main chlorinated compound used in the study area was 1,1,1-Trichloroethane (1,1,1-TCA), which was substituted by Perchloroethene (PCE) in the last 15years. A hydrogeological conceptual model has been developed for the alluvial aquifer taking into account the presence of low permeability lenses, forming a multilayer semi-confined aquifer. Hydrodynamic tests (pumping and flowmeter heat-pulse tests) coupled with standard and multilevel hydrochemical and isotopic samplings were performed. Flowmeter tests showed the existence of vertical flow between aquifer levels having different permeability. Physical-chemical parameter logs agreed with the existence of a multilayer aquifer. Concentration data collected in 21 wells located downgradient of the different sources revealed VOC (Volatile Organic Compound) levels lower than 100μg/L in the upper part of the valley and levels reaching about 200μg/L in the near shore areas. PCE is the main compound present in the aquifer. No evidence of the presence of TCA was found in the upper areas of the Chienti Valley, but in the areas near the shore, TCA and its degradation products are predominant. Data collected at multilevels located at two sites (upper and near shore areas) to refine the results obtained in the regional survey show a stratification of the VOC concentrations; values of each compound are higher than those measured in the conventional wells during the standard sampling (e.g. PCE: 150μg/L instead of 2μg/L). In addition, the vertical distribution of the contaminant reflects the vertical flow pattern inferred from hydrogeological data. The hydrogeological, VOC and isotope data showed that dilution is the main process controlling VOCs concentration in the aquifer. Degradation also played a role in the attenuation of the parent compounds in some localized areas of the aquifer. The role of the low permeability layers on VOC degradation was documented by the presence of cis-1,2-DCE, a main daughter product of PCE, in some zones of the upper area, and 1,1-Dichloroethene (1,1-DCE) and 1,1-Dichloroethane (1,1-DCA), byproducts of 1,1,1-TCA degradation, in the near shore areas. © 2012 Elsevier Ltd
Compound-Specific Isotope Analysis (CSIA) Application for Source Apportionment and Natural Attenuation Assessment of Chlorinated Benzenes
No full textIn light of the complex management of chlorobenzene (CB) contaminated sites, at which
a hydraulic barrier (HB) for plumes containment is emplaced, compound-specific stable isotope
analysis (CSIA) has been applied for source apportionment, for investigating the relation between
the upgradient and downgradient of the HB, and to target potential CB biodegradation processes.
The isotope signature of all the components potentially involved in the degradation processes has been
expressed using the concentration-weighted average 13C of CBs + benzene (13Csum). Upgradient of
the HB, the average 13Csum of 25.6‰and 29.4‰were measured for plumes within the eastern
and western sectors, respectively. Similar values were observed for the potential sources, with
13Csum values of 26.5‰for contaminated soils and 29.8‰for the processing water pipeline in
the eastern and western sectors, respectively, allowing for apportioning of these potential sources to
the respective contaminant plumes. For the downgradient of the HB, similar CB concentrations but
enriched 13Csum values between 24.5‰and 25.9‰were measured. Moreover, contaminated
soils showed a similar 13Csum signature of 24.5‰, thus suggesting that the plumes likely originate
from past activities located in the downgradient of the HB. Within the industrial property, significant
13C enrichments were measured for 1,2,4-trichlorobenzene (TCB), 1,2-dichlorobenzene (DCB),
1,3-DCB, and 1,4-DCBs, thus suggesting an important role for anaerobic biodegradation. Further
degradation of monochlorobenzene (MCB) and benzene was also demonstrated. CSIA was confirmed
to be an effective approach for site characterization, revealing the proper functioning of the HB and
demonstrating the important role of natural attenuation processes in reducing the contamination
upgradient of the HB
Interaction between shallow and deep aquifers in the Tivoli Plain (Central Italy) enhanced by groundwater extraction: A multi-isotope approach and geochemical modeling
No full textIn the Tivoli Plain (Rome, Central Italy) the interaction between shallow and deep groundwater flow systems enhanced by groundwater extraction has been investigated using isotopic and chemical tracers. A conceptual model of the groundwater flowpaths has been developed and verified by geochemical modeling. A combined hydrogeochemical and isotopic investigation using ion relationships such as DIC/Cl , Ca/(Ca + Mg)/SO4/(SO4 + HCO3), and environmental isotopes (delta O-18, delta H-2, Sr-87/Sr-86, delta S-34 and delta C-13) was carried out in order to determine the sources of recharge of the aquifer, the origin of solutes and the mixing processes in groundwater of Tivoli Plain. Multivariate statistical methods such as principal component analysis and Cluster analyses have confirmed the existence of different geochemical facies and the role of mixing in the chemical composition of the groundwater. Results indicate that the hydrochemistry of groundwater is characterized by mixing between end-members coming directly from carbonate recharge areas and to groundwater circulating in a deeply buried Meso-Cenozoic carbonate sequence. The travertine aquifer is fed by both flow systems, but a local contribution by direct input in the Plain has also been recognized. The stable isotope data (O-18, H-2, C-13 and S-34) supports the flow system conceptual model inferred from the geochemical data and represents key data to quantify the geochemical mixing in the different groundwaters of the Plain. The results of numerical modeling (PHREEQC) are consistent with the flowpaths derived from the hydrogeochemical conceptual model. The inverse models performed generated the main geochemical processes occurring in the groundwater flow system, which also included mixing. Geochemical and isotope modeling demonstrate an increasing influence of groundwater from the deeply buried aquifer in the travertine aquifer, enhanced by lowering of the travertine aquifer water table due to quarry pumping. (C) 2011 Elsevier Ltd. All rights reserved
Reactive and Mixing Processes Governing Ammonium and Nitrate Coexistence in a Polluted Coastal Aquifer
No full textA comprehensive hydrochemical, stable isotope and microbial analyses characterisation has been performed to evaluate the sources of groundwater, nitrogen pollution and degradation processes occurring in an industrial polluted coastal aquifer in the framework of a complex hydrodynamic system. The coexistence of ammonium and nitrate has been observed in almost all the investigated monitoring wells, reaching maximum values of 100 and 200 mg/L for both species. Chloride and potassium concentration coupled with groundwater stable isotopes data show the influence of local and urban recharge and the occurrence of seawater intrusion in areas near the coastline. δ15N–NH4+ values ranging between −4.9 and +14.9% suggest that different processes such as partial nitrification of ammonium, probably anammox activities and sorption, are occurring at the site. The isotope data for NH4+ also showed the existence of the remnant of an old fertilizer plume in the downgradient area. The nitrate isotope data ranging between +9 and +46% and +6 and +26% for δ15N–NO3− and δ18O–NO3−, respectively, suggest that nitrate content is attenuated by denitrification and probably annamox. The fast groundwater flow field is one of the reasons for the coexistence of NH4+ and NO3− in groundwater, since both compounds can penetrate the reducing zone of the aquifer. The influence of leakage of sewage pipelines on the aquifer cannot be discerned due to the complexities of the nitrogen attenuation processes, also influenced by pumping activities
Interaction between deep and shallow groundwater systems in areas affected by Quaternary tectonics (Central Italy): a geochemical and isotope approach
No full textHydro- and isotope geochemistry are used to refine groundwater conceptual models in two areas of central Italy (Acque Albule Basin and Velino River Valley) affected by extensional Quaternary tectonics, where deep and shallow groundwater flow systems are interacting. The role of geology, of recent deposits filling the plains and of main tectonic features controlling groundwater flowpaths and deep-seated fluids emergences are investigated and discussed. Environmental isotopes ((2)H and (18)O) confirm recharge in the surrounding carbonate aquifers, and meteoric origin of both shallow and deep groundwater. Major ion chemistry indicates a mixing between shallow Ca-HCO(3) groundwater from carbonate aquifers and deep Ca-HCO(3)-SO(4) groundwater, characterised by higher salinity and temperature and high concentration in sulphates. Isotopic composition of dissolved sulphates (delta (34)S and delta (18)O) and dissolved inorganic carbon (delta (13)C), henceforth indicated as DIC, are used to verify the presence of different sources of groundwater, and to validate the mixing model suggested by the major ion analyses. Sulphate isotope composition suggests a marine origin for the groundwater characterised by elevated sulphate concentration, whose source is present in the deep buried sequences. Carbon isotope composition confirms the role of a DIC source associated to CO(2) degassing of a deep reservoir. Groundwater conceptual models are improved underlining the importance of Plio-Pleistocene sequences filling the tectonic depression. In the Acque Albule area, the travertine plateau represents a mixing stratified aquifer, where deep groundwater contribution is spread into the shallow aquifer. The alluvial-clastic-lacustrine leaky aquifer of Velino Valley enables a complete mixing of shallow and deep groundwater allowing spot-located discharge of deep groundwater along tectonic patterns and facilitating sulphate reduction in the lacustrine sediments, explaining locally the presence of H(2)S
Evaluation of the sources of nitrogen compounds and their influence on the biological communities in the hyporheic zone of the Sagittario River, Italy. An isotopic and biological approach
No full textIn groundwater-dependent ecosystems (GDEs) a significant contribution of nitrogen contamination of the surface waters arises from groundwater input by shallow and deep flow systems. In general, nitrogen surface-groundwater exchanges and processes at the hyporheic scale are difficult to monitor. In order to have a better understanding about these interactions, it is proposed to use stable isotopes (15N-NO3 -, 18O-NO3 -, 15N-NH4 +) as environmental tracers to identify the sources and fate of the nitrogen compounds in ground-water in the sagittario river basin, central Italy. the detrimental effect of the groundwater ammonium on the meiofaunal organisms is also evaluated in the hyporheic zone, where N-NH4 + concentrations reach a maximum value of 0.6 mg L-1. the main source of the nitrogen contamination originates from agricultural and urban activities at the catchment scale. the nitrogen compounds reach the gaining stretches of the hyporheic zone along the streambed as nitrate associated to a shallow flow system and ammonium related to a deep flow system. δ15N data demonstrate that sewage and fertilizers including manure are the main sources of NO3 - and NH4 +, the latter being the major pollutant in the study area. δ18O-NO3 - data are consistent with the nitrification of ammonium to nitrate, along with the contribution from inorganic fertilizers. Furthermore, δ15N-NO3 - and δ18O-NO3 - data reveal that denitrification does not play any role on nitrate attenuation in the shallow aquifer and near the discharge areas to the river. the meio-faunal communities, represented by the crustacea copepoda selected as the target group, were shown to be sensitive to the high concentration of ammonium found at several hyporheic sites. the statistical analyses indicated a significant reduction of species abundance in the sites polluted by N-NH4 + concentrations > 0.0653 mg L-1
Use of water stable isotopes for evaluation of surface water/groundwater interaction during a storm event at the Alder Creek watershed, Southern Ontario
No full textA study of the interaction between groundwater and surface water was
undertaken within a small agricultural watershed at Mannheim, southern
Ontario, Canada. The study was conducted in a test site managed by the
University of Waterloo. Groundwater contribution to the stream was
measured along a section of Alder Creek during a rainfall event. After a
general characterization by water stable isotopes, the hydrograph separation
has been conducted using 18O/16O isotopic ratios before, during and after
the rainfall event recorded the fourteenth of July 2015. The elaboration
showed that pre-event water (corresponding to groundwater contribution)
dominated the streamflow, accounting for 82% of discharge, respect with
18% of event water (precipitation) recorded during the storm flow peak
Dual-flow in karst aquifers toward a steady discharge spring (Presciano, Central Italy): influences on a subsurface groundwater dependent ecosystem and on changes related to post-earthquake hydrodynamics
No full textThe Presciano spring system (Central Italy) is fed by a fractured carbonate regional aquifer and shows peculiar hydrogeological, physicochemical, hydrogeochemical and biological features that led to hypothesis about local superimposition of a dual groundwater flow system. The components of this system are fast-flow and baseflow groundwater paths. Hydrogeochemical and isotopic (δ18O and δD for H2O, and δ34(Formula presented.) and δ18(Formula presented.)) data were used to test this conceptual model. Differences in physico-chemistry and ion concentrations were recorded for two main spring sectors, attributable to different groundwater flowpaths. Environmental isotope analyses allowed distinguishing different recharge areas for the two groups: more depleted values (-10.4 ‰ δ18O and -71 ‰ δD) indicated the existence of a flowpath influenced by a higher elevation recharge area, whereas enriched isotope signals (-9.9 ‰ δ18O and -66 ‰ δD) supported a regional recharge area of local water infiltration. The existence of a dual flow system is also reflected in the relationship between SO4 2- concentration and SO4 2- isotope data. The isotopic pattern of SO4 2- reflects the seasonal contributions by the two flow paths to the springs: after snowmelt, the isotopic sulphate value in the spring outlet is very similar to the spring sector fed by the fast flow component, while, after the spring exhaustion period, its isotopic composition is very similar to the base flow spring sectors fed by the fracture network. The influence of the different flowpaths has also been highlighted by changes in water isotope composition after the 2009 L'Aquila earthquake in this area: the strong homogeneous response of the spring system can be attributed to a cleaning of the fracture system, which affected the aquifer at regional scale. Additional investigations adopting the geoelectrical tomography technique highlighted the possibility of the existence of a buried karst channel or at least high-permeability shear zone at the contact between the carbonate aquifer and the fluvio-lacustrine quaternary deposits, where the spring system is located. Biological indicators, such as groundwater copepods also showed a response to the dual flowpath regime. The results of this study have great relevance for a better management of the Presciano spring habitat, which is increasingly threatened by anthropogenic disturbance. © 2014 Springer-Verlag Berlin Heidelberg
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