Riassunto Il lavoro riguarda una serie di misure su campioni di 5 tipi diversi di rocce italiane aventi lo scopo di determinare la rispettiva conducibilità termica. Dopo la descrizione dell'apparecchiatura usata, vengono esposti i risultati ottenuti, analizzando in dettaglio l'influenza della scistosità. In base alle misure fatte su campioni di ardesia questa influenza può esprimersi con la formola:k=k90+m cos , dove è l'angolo fra la direzione del flusso termico ed il piano di stratificazione, mentrem è una costante caratteristica della scistosità.
Summary Experiments made for obtain the thermal conductivity of different kinds of italian rocks are described and discussed. The effect of schistosity was derived for slate rocks and it can be represented with the formula:k=k90+m cos , where is the angle between the direction of thermal flux and the plain of stratification, whereasm is a constant characterizing the schistosity.
Lavoro eseguito con un contributo del Consiglio Nazionale delle Ricerche (Comitato per la Geologia). 相似文献
The apparent features of a rural landscape are the final result of the interaction among several natural and anthropic factors. The analysis of a landscape, as well as the identification of its best management strategies, can be improved when useful information about its modifications along a wide time period is available, so as to assess the effect of the transformations that have taken place there. The implementation within a geographic information system (GIS) of geographical information derived from ancient historical maps, combined with modern digital cartography and recent remote sensing images may provide a very powerful tool for a better-informed analysis and targeted decision-making strategies about the most appropriate rural landscape planning. With the purpose to detect the land use changes in a typical rural landscape in the Basilicata Region (Southern Italy), spatial analysis using free and open-source GIS tools, in which data covering a period of about two centuries, from 1829 to 2017, were implemented. This multi-temporal analysis was carried out to investigate the landscape structure transformations through the assessment of land use change and the implementation of a methodology for the identification of areas in which there has been a natural evolution of the rural landscape. Then, using landscape metrics and spatial analysis tools, some areas in which the landscape has naturally evolved without any anthropic intervention during these 188 years have been identified, and changes occurred on the rural landscape were assessed quantitatively.
Steady-state talc dissolution rates, at far-from-equilibrium conditions, were measured as a function of aqueous silica and magnesium activity, pH from 1 to 10.6, and temperature from 25 to 150 °C. All rates were measured in mixed flow reactors and exhibited stoichiometric or close to stoichiometric dissolution. All measured rates at pH > 2 obtained at a fixed ionic strength of 0.02 M can be described to within experimental uncertainty using
The relationship between atmospheric blocking over Europe and the Atlantic eddy-driven jet stream is investigated in the NCEP/NCAR Reanalysis and in a climate model. This is carried out using a bidimensional blocking index based on geopotential height and a diagnostic providing daily latitudinal position and strength of the jet stream. It is shown that European Blocking (EB) is not decoupled from the jet stream but it is mainly associated with its poleward displacements. Moreover, the whole blocking area placed on the equatorward side of the jet stream, broadly ranging from Azores up to Scandinavia, emerges as associated with poleward jet displacements. The diagnostics are hence applied to two different climate model simulations in order to evaluate the biases in the jet stream and in the blocking representation. This analysis highlights large underestimation of EB, typical feature of general circulation models. Interestingly, observed blocking and jet biases over the Euro-Atlantic area are consistent with the blocking-jet relationship observed in the NCEP/NCAR Reanalysis. Finally, the importance of sea surface temperatures (SSTs) is investigated showing that realistic SSTs can reduce the bias in the jet stream variability but not in the frequency of EB. We conclude highlighting that blocking-related diagnostics can provide more information about the Euro-Atlantic variability than diagnostics simply based on the Atlantic jet stream. 相似文献
Population abundance, distribution and habitat preference of the Mediterranean sympatric seahorses Hippocampus guttulatus and Hippocampus hippocampus were investigated in a semi‐enclosed sea system (Apulian coast, Ionian Sea). A total of 242 individuals of seahorses were sighted in the 11 transects surveyed in summer 2011. Hippocampus guttulatus (n = 225) were 14 times more abundant than H. hippocampus (17). The mean abundance of H. guttulatus for all the pooled sites was 0.018 m?2 (SE ± 0.003) ranging from a maximum of 0.035 (SE ± 0.007) to a minimum of 0.008 (SE ± 0.002). The size structure of long‐snouted seahorse shows a population ranging from 7 to 14 cm (SL) with a peak at 10 cm (TL). Juveniles (96.0 ± 8.0 mm) represent a significant fraction of the population, accounting more than 21% of the sighted individuals. In Mar Piccolo, H. guttulatus is able to shelter both in monotonous habitats, including the algal beds, and diversified ones, such as the rich filter‐feeder communities that colonize hard substrates. By contrast, H. hippocampus is mainly associated with habitats of low complexity. Today, the Mar Piccolo di Taranto is among the most heavily polluted water bodies in South Italy, with trace metals, hydrocarbons, pesticides and organic wastes affecting both biotic and abiotic matrices. However, despite the high level of degradation, the presence of a large mussel farm has avoided the impact of towed fishing gears, and eutrophication of water bodies has ensured a high trophic level that supports large crustacean populations, potential prey for seahorses. 相似文献
We present a parameter estimation procedure based on a Bayesian framework by applying a Markov Chain Monte Carlo algorithm to the calibration of the dynamical parameters of the LISA Pathfinder satellite. The method is based on the Metropolis-Hastings algorithm and a two-stage annealing treatment in order to ensure an effective exploration of the parameter space at the beginning of the chain. We compare two versions of the algorithm with an application to a LISA Pathfinder data analysis problem. The two algorithms share the same heating strategy but with one moving in coordinate directions using proposals from a multivariate Gaussian distribution, while the other uses the natural logarithm of some parameters and proposes jumps in the eigen-space of the Fisher Information matrix. The algorithm proposing jumps in the eigen-space of the Fisher Information matrix demonstrates a higher acceptance rate and a slightly better convergence towards the equilibrium parameter distributions in the application to LISA Pathfinder data. For this experiment, we return parameter values that are all within ~1σ of the injected values. When we analyse the accuracy of our parameter estimation in terms of the effect they have on the force-per-unit of mass noise, we find that the induced errors are three orders of magnitude less than the expected experimental uncertainty in the power spectral density. 相似文献
In this paper, a bivariate-heuristic model (modified Stevenson’s method) and two multivariate statistical procedures (discriminant analysis and logistic regression) were used in order to assess and map landslide susceptibility in the north-western side of Daunia region (Apulia, Southern Italy). The whole Daunia region is characterized by complex and composite landslides, which are located on clayey slopes, near urban centers, affecting structures and infrastructures. The high predisposition to landsliding of the Daunia hillslopes is related to the very poor strength properties of clayey formations. The comparative analysis of landslide susceptibility using different methods, on the same test site and with the same inventory map allowed understanding the dependence of the results from the dataset and the capability of models under different levels of use, from expert to simple operator. By comparing the performance of the three models through the success rate curves, it emerges that the simple modified Stevenson’s method produces reliable outcomes, comparable with those deriving from more complex multivariate statistical models. This result is related to the characteristics of clayey slopes, in which the landslide occurrence is so much controlled by the poor strength properties of the clayey formations that the multivariate analysis of a large set of morphometric, geological and land-use variables results to be somehow superfluous. This suggests that, for clayey slopes, a simple, easy-to-manage bivariate-heuristic model based on expert opinion can be used with reliable results. 相似文献
We investigate the geology of Altar North (Cu–Au) and Quebrada de la Mina (Au) porphyry deposits located in San Juan Province (Argentina), close to the large Altar porphyry copper deposit (995 Mt, 0.35% Cu, 0.083 g/t Au), to present constraints on the magmatic processes that occurred in the parental magma chambers of these magmatic-hydrothermal systems. Altar North deposit comprises a plagioclase-amphibole-phyric dacite intrusion (Altar North barren porphyry) and a plagioclase-amphibole-biotite-phyric dacite stock (Altar North mineralized porphyry, 11.98 ± 0.19 Ma). In Quebrada de la Mina, a plagioclase-amphibole-biotite-quartz-phyric dacite stock (QDM porphyry, 11.91 ± 0.33 Ma) crops out. High Sr/Y ratios (92–142) and amphibole compositions of Altar North barren and QDM porphyries reflect high magmatic oxidation states (fO2 = NNO +1.1 to +1.6) and high fH2O conditions in their magmas. Zones and rims enriched in anorthite (An37–48), SrO (0.22–0.33 wt.%) and FeO (0.21–0.37 wt.%) in plagioclase phenocrysts are evidences of magmatic recharge processes in the magma chambers. Altar North and Quebrada de la Mina intrusions have relatively homogeneous isotopic compositions (87Sr/86Sr(t) = 0.70450–0.70466, εNd(t) = +0.2 to +1.2) consistent with mixed mantle and crust contributions in their magmas. Higher Pb isotopes ratios (207Pb/204Pb = 15.6276–15.6294) of these intrusions compared to other porphyries of the district, reflect an increase in the assimilation of high radiogenic Pb components in the magmas. Ages of zircon xenocrysts (297, 210, 204, 69 Ma) revealed that the magmas have experienced assimilation of Miocene, Cretaceous, Triassic and Carboniferous crustal rocks.Fluids that precipitated sulfides in the Altar deposit may have remobilized Pb from the host rocks, as indicated by the ore minerals being more radiogenic (207Pb/204Pb = 15.6243–15.6269) than their host intrusions. Au/Cu ratio in Altar porphyries (average Au/Cu ratio of 0.14 × 10?4 by weight in Altar Central) is higher than in the giant Miocene porphyry deposits located to the south: Los Pelambres, Río Blanco and Los Bronces (Chile) and Pachón (Argentina). We suggest that the increase in Au content in the porphyries of this region could be linked to the assimilation of high radiogenic Pb components in the magmas within these long-lived maturation systems. 相似文献