Search results for "electrical resistivity"
showing 10 items of 357 documents
Non-invasive Geophysical Surveys in Search of the Roman Temple of Augustus Under the Cathedral of Tarragona (Catalonia, Spain): A Case Study
2018
An integrated geophysical survey has been conducted at the Tarragona’s Cathedral (Catalonia, NE Spain) with the aim to confirm the potential occurrence of archaeological remains of the Roman Temple dedicated to the Emperor Augustus. Many hypotheses have been proposed about its possible location, the last ones regarding the inner part of the Cathedral, which is one of the most renowned temples of Spain (twelfth century) evolving from Romanesque to Gothic styles. A geophysical project including electrical resistivity tomography (ERT) and ground probing radar (GPR) was planned over 1 year considering the administrative and logistic difficulties of such a project inside a cathedral of religious…
Integrated geophysical surveys in the tarragona cathedral
2009
An integrated geophysical survey has been conducted at the Tarragona’s Cathedral (Catalonia, NE Spain) with the aim to detect the existence of archaeological remains of the Roman’s temple devoted to August. Many hypotheses have been proposed about its possible location, the last ones regarding the inner part of the Cathedral, which is one of the most famous temple of Spain (12th century) evolving from Romanesque to Gothic styles. A project including electrical resistivity tomography (ERT), ground probing radar (GPR) and frequency domain electromagnetics (FDEM) has been planned over one year and conducted during a week of intensive field survey. From all the methods applied, both ERT and GPR…
The New "Maximum Yield Grid" (MYG) Array in Full 3D Resistivity Tomography
2008
Over the past few years geoelectrical prospecting has experienced many innovations, ranging from instrumental refinements to improvement of data interpretation. The consequence of this has been a strong increase in the method s resolution power and, therefore, its field of application has broadened. Nevertheless, the diffusion of 3D surveys in electrical resistivity tomography has been very much limited by the long acquisition time required by this kind of investigation, as compared to 2D ERT or other geophysical exploration methods like GPR. However, 3D ERT has a great advantage in terms of resolution power, that is very important in many applications, such as archeological or cultural her…
Thermoelectric properties of CoTiSb based compounds
2009
Several CoTiSb based compounds were synthesized and investigated on their thermoelectric properties. The aim was to improve the thermoelectric properties of CoTiSb by the systematic substitution of atoms or the introduction of additional Co into the vacant sublattice. The solid solutions Co1+xTiSb, Co1?yCuyTiSb and CoTiSb1?zBiz were synthesized. X-ray diffraction was used to investigate the crystal structure. The resistivity, the Seebeck coefficient and the thermal conductivity were determined for all compounds in the temperature range from 2 to 400?K. The highest figure of merit for each solid solution is presented. We were able to improve the figure of merit by a factor of approximately s…
Magnetic and structural study of (Fe1−Co )62 Nb8B30 bulk amorphous alloys
2004
Abstract The electric and magnetic properties of rapidly quenched (Fe 1− x Co x ) 62 Nb 8 B 30 bulk metallic glasses were studied with x =0, 0.33 and 0.50. The Curie temperature in the amorphous state was found to be about 245 °C for the Co-free alloy, 290 °C for x =0.33 and 201 °C for x =0.50, while the crystallization temperature is varying within 15° only around 600 °C. The change in T C correlates with the change in Mossbauer parameters. An interesting flattening effect of annealing on the hysteresis loop was observed which increases with the Co content. The resistivity could not be improved above 152 μΩ cm, which limits the high frequency applications of these alloys.
Electrical resistivity of amorphous simple metals at moderately low temperatures
1999
Abstract The dependence of electrical resistivity ρ ( T ) on temperature T in a region of moderate temperatures is considered for amorphous simple metals. It is shown within the Faber–Ziman theory that the ratio [ ρ ( T )− ρ (0)]/ T 2 has a maximum in the temperature region 10 K⩽ T ⩽100 K The theory is illustrated by numerical calculations performed for hard-sphere models of amorphous Mg and Zn.
Correlated barrier hopping in NiO films
1991
The ac conduction in NiO films has been investigated in the frequency range 10 Hz < v < 10^9 Hz and at temperatures between 10 and 300 K. The frequency and the temperature dependence of the electrical conductivity can be consistently explained within a model developed for the mechanism of charge transfer in amorphous semiconductors which proposes that charge carriers hop over potential barriers between defect sites, the height of the barriers being correlated with the intersite separation.
Recent progress in electrical impedance tomography
2003
We consider the inverse problem of finding cavities within some body from electrostatic measurements on the boundary. By a cavity we understand any object with a different electrical conductivity from the background material of the body. We survey two algorithms for solving this inverse problem, namely the factorization method and a MUSIC-type algorithm. In particular, we present a number of numerical results to highlight the potential and the limitations of these two methods.
Joint interpretation of electrical and seismic data aimed at modelling the foundation soils of the Maredolce monumental complex in Palermo (Italy)
2020
The monumental complex of Maredolce (Palermo) includes an Arab-Norman castle that stands on the banks of an artificial lake carved out of the calcarenitic rock that rests on impermeable clays. The lake was originally filled with water, thanks to the channelling of a spring. Over time, the lowering of the water table and the high hydraulic permeability of the calcarenites have caused the lake to dry up. A project to renovate the monumental complex has recently been launched. It also provides the study of a possible restoration of the original conditions of the lake. To this end, a multidisciplinary geophysical study was carried out to investigate the geotechnical conditions of permeability o…
Seismic and non‐invasive geophysical surveys for the renovation project of Branciforte Palace in Palermo
2020
The renovation project of the historic Branciforte Palace (16th–17th century) in Palermo (Italy) was owned by the Banco di Sicilia Foundation, with the aim for it to become a multi-purpose centre for the promotion of exhibitions and cultural events. In the context of the restoration work, a multi-methodological and non-invasive geophysical study has been carried out. The seismic characterization of the foundation soils was obtained by means of joint interpretations of a vertical seismic profile (VSP), multichannel analysis of surface waves (MASW) and horizontal to vertical spectral ratio (HVSR) microtremor analysis. The mutually constrained inversion of seismic surveys carried out with diff…