排序方式： 共有43条查询结果，搜索用时 15 毫秒
11.
Prof. Dr. Arnaldo Belluigi 《Pure and Applied Geophysics》1953,26(1):67-74
Riassunto Tra le diverse possibilità di realizzazione di Matranslog (costantemente a maggior potere risolutive delle caratteristiche geoelettriche nei fori di sonda che non i procedimenti a «regime»), l'A. illustra quello a massimo rendimento, agli effetti interpretativi delle diagrafie transitorie. Le funzioni trans infatti risultano del tipo più completo, con decorso da zero ad un massimo assoluto (a «sovratensione») fino a valori asintotici di regime.
Summary Among the manifold possibilities of realization of Matranslog, the Author develops that which enables to come to a Matranslog of highest effectiveness. Indeed, the Eltrans-functions, that the Author reckons, result to be of type having a time cours from zero to an absolute maximum (with «surtension»), up to asymptotic values of regime. This type of Trans-diagraphy is the most complete one that can be reached. The analyses of such diagraphies present the highest resolutive power of the Geomatrans-parameters, measurable in well holes.
Résumé Entre les différentes possibilités de réalisation de «Matranslog» (toujours à plus grand pouvoir résolutif des caractéristiques geoélectriques que non les anciens méthodes à régime), l'Auteur décrit un Matranslog à plus grand rendement, pour les interprétations des diagraphies trans. Les fonctions trans, en effect, résultent du type plus complet, avec une démarche de zero à un maximum absolu (surtension) jusqu'aux valeurs asymptotiques de régime.相似文献
12.
Prof. Dr. Arnaldo Belluigi 《Pure and Applied Geophysics》1953,25(1):29-36
Riassunto L'A., dopo ricordato un suo studio pubblicato un anno addietro circa la possibilità di realizzazione di unMatranslog (misure transitorie e. m.-elettromagnetiche nei fori sonda), sviluppa la teoria considerando un emittore e. m. di dimensioni finite. Sia il dipolomatrans che il bipolomatrans presentano analoghi comportamenti temporali. L'A. mostra le proprietà delle caratteristiche impulsive delMatranslog per suoli uniformi. Accenna quindi alle equivalenti caratteristiche di frequenza coll'ideazione d'un adeguatoPhaselog.
Summary After recollecting a study published a year ago by himself about the possibility of constructing aMatranslog (electromagnetic measures of transients in boreholes), Author develops the relative theory, considering an e. m. generator of limited dimensions. Bothmatrans dipole andmatrans bipole offer similar time behaviour. Writer shows the properties of the pulse characteristics of theMatranslog for homogeneous grounds. He hints to the equivalent frequency characteristics deducted by means of an adequatePhaselog.相似文献
13.
Arnaldo Belluigi 《Pure and Applied Geophysics》1960,47(1):55-68
Riassunto Viene studiato l'andamento EGO quando all'anodo si crea uno strato isolante progrediente nel tempo:EGO a limite mobile. Dalla teoria discende una prassi operativa EGO atta a contenere lo strato tampone (elettricamente resistivo).
Summary The electro-osmotic phenomenon (EGO) is studied with regard to an insulating layer which builds up at the anod (mobile-limit EGO). An efficient operative method may be to lower the input voltage by the same ratio as the ohmic resistance increases. Practically it may be sufficient to lower the input voltage by a fixed percentage now and then, i. e.; at the time the ohmic resistance increases, or some time before. The aim is to prevent the formation of «stopper resistances» in order bo get a suitable electric current flow i. e., keep low the ohmic resistance lowering continually the voltage.相似文献
14.
Sanz-Lázaro C Belando MD Marín-Guirao L Navarrete-Mier F Marín A 《Marine environmental research》2011,71(1):22-30
The aim of this work was to study the dispersion of particulate wastes derived from marine fish farming and correlate the data with the impact on the seabed. Carbon and nutrients were correlated with the physico-chemical parameters of the sediment and the benthic community structure. The sedimentation rates in the benthic system were 1.09, 0.09 and 0.13 g m?2 day?1 for particulate organic carbon (POC), particulate organic nitrogen (PON) and total phosphorus (TP), respectively. TP was a reliable parameter for establishing the spatial extent of the fish farm particulate wastes. Fish farming was seen to influence not only physico-chemical and biological parameters but also the functioning of the ecosystem from a trophic point of view, particularly affecting the grazers and the balance among the trophic groups. POC, PON and TP sedimentation dynamics reflected the physico-chemical status of the sediment along the distance gradient studied, while their impact on the benthic community extended further. Therefore, the level of fish farm impact on the benthic community might be underestimated if it is assessed by merely taking into account data obtained from waste dispersion rates. The benthic habitat beneath the fish farm, Ma?rl bed, was seen to be very sensitive to aquaculture impact compared with other unvegetated benthic habitats, with an estimated POC-carrying capacity to maintain current diversity of 0.087 g C m?2 day?1 (only 36% greater than the basal POC input). Environmental protection agencies should define different aquaculture waste load thresholds for different benthic communities affected by finfish farming, according to their particular degree of sensitivity, in order to maintain natural ecosystem functions. 相似文献
15.
The aim of the present work was to determine the activities of selected antioxidant enzymes (SOD, Se-GPX, CAT) in two species of bivalves, Scapharca inaequivalvis and Tapes philippinarum, from two sites of the lagoon of Venice that are characterized by different pO(2) (Marghera and Chioggia). The specimens were collected at four times during a 1-year period. In the two species studied, enzyme activities were found to be present in both digestive glands and gills, but with some species-specific differences that may also represent a different adaptation to seasonal variations. The presence of high SOD activities in the gills of both species may be related to their physiological role in respiration. Scapharca inaequivalvis is less sensitive than T. philippinarum to environmental changes, perhaps due to the presence of hemoglobins in this species. Moreover, in the digestive gland of T. philippinarum we found a significant negative correlation between the activities of SOD and GPX that may indicate the presence of oxidative stress. Some correlations between temperature/dissolved oxygen and antioxidant enzyme activity were present in specimens sampled in Marghera. Only GPX adequately responded to changes in dissolved oxygen and temperature, while the decrease in the activity of SOD and CAT in winter may be directly responsible for an enhanced susceptibility of mussels to oxidative stress during this period. We can conclude that the observed differences between Chioggia and Marghera are due to different concentrations of dissolved oxygen. Marghera is an appropriate location to study seasonal variations in water temperature. In fact, in this site, the differences between hot and cold months are quite evident. 相似文献
16.
Roberto Wagner Lourenço Paulo M. Barbosa Landim André Henrique Rosa José Arnaldo F. Roveda Antonio César Germano Martins Leonardo Fernandes Fraceto 《Environmental Earth Sciences》2010,60(3):495-504
Spatial analysis and fuzzy classification techniques were used to estimate the spatial distributions of heavy metals in soil.
The work was applied to soils in a coastal region that is characterized by intense urban occupation and large numbers of different
industries. Concentrations of heavy metals were determined using geostatistical techniques and classes of risk were defined
using fuzzy classification. The resulting prediction mappings identify the locations of high concentrations of Pb, Zn, Ni,
and Cu in topsoils of the study area. The maps show that areas of high pollution of Ni and Cu are located at the northeast,
where there is a predominance of industrial and agricultural activities; Pb and Zn also occur in high concentrations in the
northeast, but the maps also show significant concentrations of Pb and Zn in other areas, mainly in the central and southeastern
parts, where there are urban leisure activities and trade centers. Maps were also prepared showing levels of pollution risk.
These maps show that (1) Cu presents a large pollution risk in the north–northwest, midwest, and southeast sectors, (2) Pb
represents a moderate risk in most areas, (3) Zn generally exhibits low risk, and (4) Ni represents either low risk or no
risk in the studied area. This study shows that combining geostatistics with fuzzy theory can provide results that offer insight
into risk assessment for environmental pollution. 相似文献
17.
Coastal zones are widely recognised as being particularly vulnerable to future environmental change. Although a significant number of previous papers warn of an increasing tendency in the appearance of eutrophication processes in such systems, very few papers have evaluated the influence of global climate change on eutrophication. 相似文献
18.
Terezinha Cássia de Brito Galvão Aloisio Rodrigues Pereira Arnaldo Teixeira Coelho Paula Rodrigues Pereira Joaquim Fernandes Teixeira Coelho 《Geotechnical and Geological Engineering》2011,29(1):49-55
Soil erosion, transport and deposition of sediments represent invisible threats that along time can affect negatively the
existing infrastructure of roads and dams, and the quality of air and water resources. In the last decades, a great number
of researches were devoted to study erosion and sediments transportation processes. However, they addressed mostly areas of
agriculture, water impoundments for dams, and land conservation. A lack of studies for erosion processes in urban areas is
evident, in special those aiming to diminish the deposition of sediments originated from urban areas into the rivers and air,
in special as airborne particulate. Traditionally, the costs associated in controlling erosion and sediments in urban areas
are high and in some case, out of the range for most developing countries. Factors responsible for those high prices are the
use of heavy equipments for soil grading and transportation, the use of costly building materials, and the need for employing
more specialized personnel. In the case of gullies in urban areas, another concern is to ensure proper equipment access to
the area for remediation operations. Hereby, it is presented a cost-effective method to recover an extensive gully erosion
area of about 11,000 m2 located in urban area. Estimated sediments released from this area to the water resources and air were estimated on about
66,000,000 tons. In this study area, bioengineering works were performed in 60 days, with hardly any sediment generated outside
the work area resulting from bioengineering operations. A combination of bioengineering techniques were chosen for this study
area, which was a mixture of rigid and biological products including biologs, silt fence, biodegradable straw blankets sewn
with plastic threads derived from recycled PET bottles, among others. An efficient drainage system was implemented for preventing
upland flow, sub-seepage and seepage. Biologs were used aiming to fulfill a double role, the first as barrier to soil sediments
flow, and the second as filler for empty spaces, avoiding expensive grading operations. All engineering works were concluded
in about 60 days at a cost of US0.89/m < sup > 2 < /sup > . This price is cost-effective if compared with the traditional engineering cost of approximately US 0.89/m2. This price is cost-effective if compared with the traditional engineering cost of approximately US 2.92/m2 because it includes extensive use of grading and soil transportation. An environmental advantage of the bioengineering method
is the immediate reduction of airborne particulates. Furthermore, the overall visual aesthetics improved shortly after the
implementation of the works because the bare ground was substituted by native vegetation. After 6 months the vegetation in
the gully erosion area was totally established. Monitoring was performed after 12 months and no erosion and sediment transport
was visually noticed. The ease implementation of this technique without the need for specialized workers in combination with
low prices makes this method a model for developing countries. 相似文献
19.
Carlos Sanz-Lázaro María Dolores BelandoFrancisco Navarrete-Mier Arnaldo Marín 《Estuarine, Coastal and Shelf Science》2011
A manipulative caging experiment was carried out to evaluate the role of wild fish and motile epibenthic invertebrates on the benthic system influenced by an open water fish farm. Chemical and biological parameters of the sediment were measured as indicators of the ecological benthic status. The combination of wild fish and currents notably lowered aquaculture waste sedimentation below the fish farm. The limited waste sedimentation rate could have limited the scavenger and predation activity of wild fish on the benthos, whose role may be taken over by motile epibenthic invertebrates. The interaction of these motile epibenthic invertebrates with the sediment differed from that observed with fish. The motile epibenthic invertebrates led to more reduced conditions with lower redox values, significantly decreased the number of species of macrofaunal benthic assemblages and significantly modified macrofaunal benthic assemblages. Therefore, epibenthic invertebrates do not seem to have an ameliorative effect on the benthic status produced by fish farming. Since the effects of epibenthic species on the benthic system can greatly vary according to their identity, further experiments should be performed to better understand the drivers that influence the epibenthic species identity that modulate the benthic system affected by fish farming. 相似文献
20.
Cleber Gonzales de Oliveira Waldir Renato Paradella Arnaldo de Queiroz da Silva 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(1):67-72
The Brazilian Amazon is a vast territory with an enormous need for mapping and monitoring of renewable and non-renewable resources. Due to the adverse environmental condition (rain, cloud, dense vegetation) and difficult access, topographic information is still poor, and when available needs to be updated or re-mapped. In this paper, the feasibility of using Digital Surface Models (DSMs) extracted from TerraSAR-X Stripmap stereo-pair images for detailed topographic mapping was investigated for a mountainous area in the Carajás Mineral Province, located on the easternmost border of the Brazilian Amazon. The quality of the radargrammetric DSMs was evaluated regarding field altimetric measurements. Precise topographic field information acquired from a Global Positioning System (GPS) was used as Ground Control Points (GCPs) for the modeling of the stereoscopic DSMs and as Independent Check Points (ICPs) for the calculation of elevation accuracies. The analysis was performed following two ways: (1) the use of Root Mean Square Error (RMSE) and (2) calculations of systematic error (bias) and precision. The test for significant systematic error was based on the Student’s-t distribution and the test of precision was based on the Chi-squared distribution. The investigation has shown that the accuracy of the TerraSAR-X Stripmap DSMs met the requirements for 1:50,000 map (Class A) as requested by the Brazilian Standard for Cartographic Accuracy. Thus, the use of TerraSAR-X Stripmap images can be considered a promising alternative for detailed topographic mapping in similar environments of the Amazon region, where available topographic information is rare or presents low quality. 相似文献