3,252 research outputs found
Determinación de compuestos organoclorados en sedimentos de la Ría de Vigo
No full textSe presenta la distribución espacial de concentraciones de
los Clorobilenilos de Nº IUPAC 28, 31, 52, 101, 105, 118,
138, 153, 156 Y 180, y de los pesticidas organoclorados
Hexaclorobenceno (HCB), a -Hexaclorociclohexano (a -
HCH), Lindano (g-HCH), p,p'-DDE, p,p'-DDD, p,p'-DDT Y
Transnonaclor en sedimentos superficiales de la Ría de Vigo.
Los análisis se han realizado sobre la Iracción total del
sedimento ( < 2 mm), mediante Cromatografía de Gases de
alta resolución (Detector ECD y columnas capilares). El
método es el habitualmente empleado por el C.O. de Vigo
del I.E.O. en sus programas nacionales y supranacionales
de seguimiento y control de la contaminación marina.The spatial distributions 01 concentrations 01 the
Chlorobiphenyls with IUPAC numbers 28,31,52, 101, 105,
118, 138, 153, 156 and 180, and 01 the Organochlorine
Pesticides Hexachlorobenzene (HCB), a
Hexachlorociclohexane (a- HCH), Lindane (g- HCH), p,p'-
DDE, p,p'-DDD, p,p-DDT and Transnonachlor have been
determined in surface sediments 01 the Ría de Vigo.
The analyses have been performed in the total Iraction 01
the sediment « 2mm) by high resolution Gas
Chromatography (ECD detector and capillary columns). The
method is the same been used on a regular basis by the
C.O. de Vigo of the I.E.O. both in its national programme
and in the contributions to international control and
assessment programmes of contamination in the marine
environment
Analysis of the Vigo-Marín bottom trawl fleet operating in ICES Division VII for possible standardization
No full textIn order to consider the possible standardization of the cpue
of the Vigo-Marín trawl
fleet operating in ICES Division VII for its potential use as an abundance index for the assessments of the stocks of megrim (Lepidorhombus whiffiagonis) and anglerfish (Lophius piscatorius
and
L. budegassa) in ICES Divisions VIIb–k and VIIIabd, a series of
preliminary analyses were conducted on data collected on both landings and discards
historic time-series. This document complements the work conducted in Fernández
et
al. (2008). Updated information through to 2010 is now
available, which is taken into
consideration. At the same time, the present document considers the main species
caught by this fleet (L. whiffiagonis, L. boscii,
L. budegassa,
L. piscatorius,
Merluccius merluccius
and
Nephrops norvegicus) in order to try to ascertain whether possible changes
in the directionality of the fleet may have occurred over time. There does not seem to
be a clear change in species composition through the time-series analysed (1986–2010)
but an increase in cpue for most species could
be observed in approximately the last
decade. Qualitative information from the fishing industry confirms that cpues have
increased in the last decade and notes the fact that this fleet was substantially renovated during the 1990s, which may well have led
to an increase in its efficiency. For
megrim (L. whiffiagonis), the information examined by Fernández
et al. (2008) and
further extensions considered in this work suggests that the strong increase in cpue
from 1999 onwards is more likely due to the technological improvement mentioned
above rather than to a strong increase in stock abundance. Thus, the recommendation
made by Fernández
et al. (2008) that if this cpue series were to be used for tuning the
megrim assessment, it should better be split in two periods, one covering from 1984
to 1998 and another one from 1999 onwards, still seems appropriate
La sociologia visuale di Jean Vigo
No full textUn'analisi interdisciplinare delle opere di Jean Vigo, regista francese, censurato dalle autorità governative francesi e considarato antipatriottico. Solo molti anni dopo, il cinema francese e mondiale, si renderà conto del valore di quel giovane regista, messo all'indice dall'ottusità del potere
Occurrence of organotin compounds in waters of the spanish coast under the European Water Framework Directive
No full textOrganotin compounds (OTCs), such as tributyltin (TBT), are persistent organic pollutants that are
present in water samples (surface water, river water, sea water, waste water, etc.) because of
anthropogenic activities (antifouling agents in ship paints, biocides in polymers, etc.). The toxicity
and endocrine disruption potential of these chemicals have been demonstrated even at very low
levels (<1 ng L−1) (Devos et al. 2012). Due to the extensive presence of OTCs in all environmental
media as well as their adverse effects on human health and biota, quantitative and qualitative
determination of those com-pounds in complex environmental matrices has become a matter of
great concern, mainly butyl and phenyl-substituted. Also, these compounds are included in the list of
priority substances according to the EU Directive 2013/39/EU amending Directives 2000/60/EC and
2008/105/EC as regards priority substances in the field of water policy. This directive specifies
annual average environmental quality standard (AA-EQS) of 0.2 ng L−1 TBT and a maximum
allowable environmental quality standard (MAC-EQS) of 1.5 ng L−1 TBT for all surface waters.
Samples were collected in two semiconfined coastal areas, one of them an area with high industrial
and port activities (Ría de Vigo) and the other one with high touristic and agricultural activity (Mar
Menor).The sampling campaigns were performed in spring and autumn of 2015. The levels of MBT,
DBT, TBT, MPhT, DPhT and TPhT in the seawater samples were analyzed by HS-SPME-GC–QqQMS/
MS method (Moscoso-Pérez et al. 2015).
MPhT, DPhT and TPhT were not detected in any sample at levels higher than LOQ. For butylated
compounds, MBT, DBT and TBT were detected in 100% of the analyzed samples in the Mar Menor.
In the Vigo estuary, MBT has been detected in 83.3% of the samples, the DBT in 75% and the TBT
in 88%. The TBT is present in 92% of the total of 39 analyzed samples, being detected in 100% of
the samples of the Mar Menor and in 88% of the samples of the Ría de Vigo. These levels are
similar than those detected in other locations, and lower than the detected in ports near the coast of
Gijón characterized by a great maritime traffic (Centineo et al. 2004).Program of Consolidation and Structuring of Units of Competitive Investigation of the University System of Galicia (Xunta de Galicia) potentially cofinanced by ERDF in the frame of the operative Program of Galicia 2007-2013 (reference: GRC2013-047) and by the Ministry of Economy and Competitiveness (IMPACTA, project reference: CTM2013-48194-C3-2-R, and ARPA-ACUA, project reference: CTM2016-77945-C3-3-R)
New classes of similar solutions for laminar free convection problems
No full textAs shown by the senior author, the proper formulation of free convection boundary-layer theory depends on order of magnitude of the Eckert number defined as Ec = Hg/cpΔT, the conventional theory being valid in the limit Ec → 0. The present paper investigates the solutions of the laminar on flat plate problem, over the entire Ec-range, for the case in which similarity prevails. It is shown that for Ec ≡ O(1) the similar solutions are attainable for linearly varying wall temperature (in particular constant) whereas in the limit for Ec → ∞ any wall temperature distribution leads to similar solutions. Similar profiles for Ec ≡ O(1) depend on the Prandtl number and on the ratio (Ec/β′) where β′ is the constant wall temperature gradient. Similar profiles for Ec → ∞ are universal insofar as they do not depend on any parameter. Universal profiles are given in closed form. Numerical solutions for Pr = 0.72 and several values of (Ec/β′) are presented and analysed in terms of velocity and temperature profiles, wall shear stress and Nusselt number. In particular the paper shows that the results of conventional theory cannot be used for β′ smaller than (0.05-0.
Caratterizzazione delle polveri ultrafini emesse da un impianto di incenerimento di combustibile derivato dai rifiuti (CDR)
No full textNegli ultimi anni sono stati sviluppati numerosi studi epidemiologici nell’ottica di stimare gli effetti del particolato atmosferico (PM) sulla salute umana, in particolare dal punto di vista cardiovascolare e respiratorio. Particolare attenzione è stata prestata al particolato fine (PM2.5) e ultrafine (UFPs, polveri con diametro aerodinamico equivalente inferiore a 100 nm), ma non c’è unanime consenso nella comunità scientifica su quale caratteristica e/o proprietà del particolato possa causare i maggiori danni sulla salute umana. I dati storici delle emissioni evidenziano che il principale contributo in termini di particolato fine e ultrafine è dovuto alle attività antropiche, a processi industriali e al traffico veicolare. È, quindi, rilevante caratterizzare sia le sorgenti di emissione sia l’evoluzione dimensionale del particolato al fine di determinare la distribuzione di aerosol e una valutazione dell’esposizione in un’area a elevata pressione antropica.
Negli ultimi 10-15 anni si è assistito a un rapido sviluppo tecnologico nel settore dell’incenerimento dei rifiuti, grazie anche alla specifica legislazione in alcuni paesi europei che obbliga le industrie a ridurre le emissioni tossiche derivanti dagli impianti d’incenerimento cittadini (MWIs). Di conseguenza, sono utilizzate le migliori tecnologie disponibili per il trattamento delle emissioni al camino al fine di rendere questi impianti ecologicamente sostenibili. Tuttavia, ad oggi non sono stati sviluppati né specifici apparati di abbattimento di UFPs, né condotte specifiche campagne di misura e monitoraggio presso gli impianti.
Il presente lavoro descrive la campagna sperimentale volta al monitoraggio delle UFPs condotta presso l’inceneritore di CDR di San Vittore del Lazio (FR). In particolare, sono state misurate distribuzioni dimensionali e concentrazioni totali di polveri sia in emissione sia a monte del filtro a maniche. Inoltre, è stata eseguita una caratterizzazione chimica delle UFP in termini di metalli pesanti mediante la tecnica di analisi per attivazione neutronica strumentale (INAA)
Le emissioni di metano nelle reti di gas naturale
No full textIl metano è considerato responsabile per circa l’8% dell’e" etto serra in quanto, malgrado le ridotte quantità rispetto ad altri gas serra come l’anidride carbonica, presenta un potenziale di riscaldamento globale circa 20 volte maggiore rispetto a quest’ultima.
Numerosi studi dimostrano che una delle principali fonti di emissione di metano è rappresentata dalla filiera del gas naturale, ovvero produzione, trasporto-stoccaggio e distribuzione.
Molti Paesi, come la Spagna, il Canada, la Germania e la Grecia, hanno aumentato le proprie emissioni di gas metano fino al 10% tra il 1990 e il 2002, e di conseguenza la concentrazione di metano in atmosfera continua ad aumentare con un tasso medio annuo superiore all’1%. Tali emissioni costituiscono, oltre a
uno spreco energetico e un elemento di impatto ambientale, un fattore
di disequilibrio nel bilancio di massa delle reti. Per questo, in numerose reti di trasporto e distribuzione del gas naturale sono state incentivate e programmate campagne e studi per la ricerca e la stima delle perdite e per la loro riduzione
Influence of the type of living prey during first stages of rearing Sepia officinalis L., 1758
No full textEste trabajo presenta los resultados de una experiencia de cultivo de juveniles de Sepia officinalis L., 1758 nacidos en cautividad. Tras la eclosión, los juveniles se distribuyeron en tres grupos que fueron alimentados con dietas iniciales diferentes: anfípodos, misidáceos y Artemia salina (L., 1756); posteriormente, a los 168 días de vida, la dieta se homogeneizó, pasando a ser básicamente inerte. Los mejores resultados se obtuvieron en el grupo alimentado inicialmente con misidáceos, que alcanzó, al cabo de 221 días de experiencia, un peso medio final de 29, 30 g, significativamente superior (p<0, 05) a los 4, 53g y 7, 78 g que alcanzaron, en promedio final, los alimentados con anfípodos y artemia respectivamente.This paper presents the results of a rearing experiment involving first feeding of cuttlefish Sepia officinalis
L., 1758. After hatching in captivity, juveniles were divided into three groups, each feed with a different
initial diet: amphipods, mysids and Artemia salina (L., 1756). Afterwards, their diet was mostly inert.
The best results were obtained in the mysids group, which after 221 days showed an average weight (29.30 g)
that was significantly higher (p < 0.05) than the other groups (4.53 g with amphipods and 7.78 g with A.
salina)
The two-echelon capacitated vehicle routing problem: models and math-based heuristics
No full text Multiechelon distribution systems are quite common in supply-chain and logistics. They are used by public administrations in their transportation and traffic planning strategies, as well as by companies, to model own distribution systems. In the literature, most of the studies address issues relating to the movement of flows throughout the system from their origins to their final destinations. Another recent trend is to focus on the management of the vehicle fleets required to provide transportation among different echelons. The aim of this paper is twofold. First, it introduces the family of two-echelon vehicle routing problems (VRPs), a term that broadly covers such settings, where the delivery from one or more depots to customers is managed by routing and consolidating freight through intermediate depots. Second, it considers in detail the basic version of two-echelon VRPs, the two-echelon capacitated VRP, which is an extension of the classical VRP in which the delivery is compulsorily delivered through intermediate depots, named satellites. A mathematical model for two-echelon capacitated VRP, some valid inequalities, and two math-heuristics based on the model are presented. Computational results of up to 50 customers and four satellites show the effectiveness of the methods developed. </jats:p
Metrological characterization of a new direct heat accounting device
No full textThe new Energy Efficiency Directive leads to a strong incentive to the installation of heat accounting systems as an essential tool to increase energy efficiency of buildings. This is also facilitated by the spreading of district heating networks more and more extended and to the return to central heating plants in buildings, more efficient and less polluting than traditional individual ones. Heat metering and accounting is now carried out by the so-called direct systems (i.e. heat meters) and indirect (i.e. heat cost allocators, insertion time counters compensated whit flow temperature or with the degree-days). On the other hand, both the metrological characteristics of such systems and the constraints in terms of installation and managing of heating plants lead direct and indirect systems to uncertainties in heat accounting sometimes far above the accuracy limit of 5%. In this paper the authors present the results of an experimental characterization of an innovative integrated system for heat accounting made up of an electronic valve, a static flow-meter and a temperature sensor pair. The system can be installed on the return pipe of each radiator of the heating plant and connected with a remote control unit and with a single temperature sensor installed on the feed pipe immediately below the central boiler
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