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Data preprocessing for river flow forecasting using neural networks: Wavelet transforms and data partitioning 总被引：7，自引：0，他引：7
Barbara Cannas Alessandra Fanni Linda See Giuliana Sias 《Physics and Chemistry of the Earth》2006,31(18):1164-1171
The evaluation of surface water resources is a necessary input to solving water management problems. Neural network models have been trained to predict monthly runoff for the Tirso basin, located in Sardinia (Italy) at the S. Chiara section. Monthly time series data were available for 69 years and are characterized by non-stationarity and seasonal irregularity, which is typical of a Mediterranean weather regime. This paper investigates the effects of data preprocessing on model performance using continuous and discrete wavelet transforms and data partitioning. The results showed that networks trained with pre-processed data performed better than networks trained on undecomposed, noisy raw signals. In particular, the best results were obtained using the data partitioning technique. 相似文献
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Manuel Martín-Martín Francesco Guerrera Tomás Rodríguez-Estrella Francisco Serrano Francisco J. Alcalá Giuliana Raffaelli 《Geodinamica Acta》2018,30(1):265-286
An interdisciplinary study of Miocene successions in the eastern External Betic Zone (South Iberian Margin) was carried out. Evidences of syn-sedimentary tectonic activity were recognized. The results enabled a better reconstruction of the stratigraphic architecture (with an improved chronostratigraphic resolution) in the framework of the Miocene foredeep evolution of the eastern EBZ. Two main depositional sequences were dated as uppermost Burdigalian-upper Serravallian p.p. and middle-upper Tortonian. p.p., respectively. The vertical and lateral diversification of lithofacies associations and thicknesses resulted from the syn-depositional tectonic complexity of the area. A great variety of sedimentary depositional realms is due to different subsidence rates, and the growing of anticlines and synclines during the Langhian p.p.-Serravallian. After a regression with an early Tortonian erosional gap, platform to hemipelagic realms developed during the middle Tortonian. The end of the sedimentation coincided with the emplacement of an important olisthostrome-like mass consisting of Triassic material related to either the development of thrust systems or diapirs emerged in the middle-late Tortonian, during the nappe emplacement. Correlations with other external sectors of the Betic Chain, and the external domains of the Rif, Tell, and northern Apennine Chains highlighted a similar Miocene foredeep evolution during the building of these orogens. 相似文献
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Federica Donda Edy Forlin Emiliano Gordini Giuliana Panieri Stefan Buenz Valentina Volpi Dario Civile Laura De Santis 《Basin Research》2015,27(4):531-545
In the Northern Adriatic Sea, the occurrence of gas seepage and of unique rock outcrops has been widely documented. The genesis of these deposits has recently been ascribed to gas venting, leading to their classification as methane‐derived carbonates. However, the origin of seeping gas was not clearly constrained. Geophysical data collected in 2009 reveal that the gas‐enriched fluid vents are deeply rooted. In fact, the entire Plio‐Quaternary succession is characterized by widespread seismic anomalies represented by wipe‐out zones, and interpreted as gas chimneys. They commonly root at the base of the Pliocene sequence but also within the Palaeogene succession, where they appear to be associated to deep‐seated faults. We suggest that there is a structural control on chimney distribution. Chimneys originate and terminate at different stratigraphic levels; commonly they reach the seafloor, where authigenic carbonate deposits form locally. Gas analyses of some gas bubble streams just above the rock outcrops reveal that gas is composed mainly of methane. Geochemical analyses performed at four selected outcrop sites show that these deposits formed as a consequence of active gas venting. In particular, geochemical analyses indicate carbonate precipitation from microbial oxidation of methane‐rich fluids, although a straightforward correlation with the source depth of gas feeding the authigenic carbonates cannot yet be clearly defined. 相似文献
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Eugen Vujić Giuliana Verbanac Vladis Vujnović Antun Marki 《Studia Geophysica et Geodaetica》2009,53(4):497-517
During the time interval 2003–2005 a ground survey of the total magnetic field intensity in the middle-northern part of Croatia
was performed, in order to get a detailed insight of the field distribution over the region. A special effort was done to
understand the uncertainty and errors in data reduction, namely different amplitudes of the diurnal variations and different
secular variations at the ground stations with respect to the observatories. For data reduction to epoch 2004.5 the total
field recordings from AQU, FUR, NCK and THY geomagnetic observatories have been used. We estimate the mean determination error
to be one order of magnitude smaller than the maximal reduction error. Multiple linear regression and the method of empirical
orthogonal functions were applied on the ground survey and observatory time series. This allowed us to explain the correlations
among them and the variance of the total field. Furthermore, we identified two sources of serious artificial disturbances
caused by DC leakage: the tramway system of the capital and one railway station in neighbouring Slovenia. Also, we estimate
the region free of these disturbances. The magnitude of one of them is estimated to be more than five nT at the distance of
about 10 km. 相似文献
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Luca Paolino Monica Sebillo Genoveffa Tortora Giuliana Vitiello 《Transactions in GIS》2010,14(6):731-753
The integrated management of heterogeneous spatial data, such as continuous fields and discrete data, is an important issue for the Geographic Information (GI) community. Indeed, GI users are forced to navigate among and operate with several tools in order to solve their spatial problems, due to the lack of systems capable of integrating different components, each meant to provide a specific solution. The aim of this article is to propose an OpenGeospatial‐compliant solution which supports expert users in handling problems involving heterogeneous data by means of a seamless approach. A class hierarchy modeling spatial discrete objects, continuous data, relationships, and operations, is described, whereby data are organized in agreement with the binary representation. A running example is illustrated to support readers' understanding of the proposed solution. Finally, some guidelines about an implementation modality are given, to demonstrate the applicability of the proposal to an existing DBMS. 相似文献
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A new multi‐proxy investigation of Late Quaternary palaeoenvironments along the north‐western Barents Sea (Storfjorden Trough Mouth Fan) 
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José?M.?CarcioneEmail author Stefano?Picotti Davide?Gei Giuliana?Rossi 《Pure and Applied Geophysics》2006,163(1):175-207
We present a new petro-elastical and numerical-simulation methodology to compute synthetic seismograms for reservoirs subject
to CO2 sequestration. The petro-elastical equations model the seismic properties of reservoir rocks saturated with CO2, methane, oil and brine. The gas properties are obtained from the van der Waals equation and we take into account the absorption
of gas by oil and brine, as a function of the in situ pore pressure and temperature. The dry-rock bulk and shear moduli can be obtained either by calibration from real data or
by using rock-physics models based on the Hertz-Mindlin and Hashin-Shtrikman theories. Mesoscopic attenuation due to fluids
effects is quantified by using White's model of patchy saturation, and the wet-rock velocities are calculated with Gassmann
equations by using an effective fluid modulus to describe the velocities predicted by White's model. The simulations are performed
with a poro-viscoelastic modeling code based on Biot's theory, where viscoelasticity is described by generalizing the solid/fluid
coupling modulus to a relaxation function. Using the pseudo-spectral method, which allows general material variability, a
complete and accurate characterization of the reservoir can be obtained. A simulation, that considers the Utsira sand of the
North Sea, illustrates the methodology. 相似文献
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Following the increase in seismic activity which occurred near Isernia (Molise, Central Italy) in January 1986, a digital seismic network of four stations with three-component, short-period seismometers, was installed in the area by the Osservatorio Vesuviano. The temporary network had an average station spacing of about 8–10 km and, in combination with permanent local seismic stations, allowed the accurate determination of earthquake locations during an operating period of about one month. Among the 1517 detected earthquakes, 170 events were selected with standard errors on epicentre and depth not greater than respectively 0.5 and 1.5 km. The most frequent focal depths ranged between 4 and 8 km, while the epicentres distribution covered a small area NE of Isernia of about 10 km2. A main rupture zone could not be clearly identified from the spatial distribution of the earthquakes, suggesting a rupture mechanism involving heterogeneous materials. The activity was characterized by low energy levels, the largest earthquake, on January 18, 1986, havingM
D
=4.0. The time sequence of events and pattern of seismic energy release revealed a strong temporal clustering of events, similar to the behaviour commonly associated with seismic swarms. 相似文献