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Uniform long length Ag clad mono-filamentary BSCCO tapes have been produced by the powder in tube method making use of drawing, cold rolling and annealing processes. The influence of the starting BSCCO powders, packing method and Ag addition on BSCCO/Ag superconducting tapes have been analyzed using XRD and scanning electron microscopy combined with EDX and Image Analysis. In addition, extensive electrical transport measurements have been carried out. Average values of J/sub c//spl ap/12 kA/cm/sup 2/ with a dispersion of /spl plusmn/5% over a 1 m length have been obtained. [ABSTRACT FROM PUBLISHER]

Digital speckle pattern interferometry has been used to detect inhomogeneous heating in YBa2Cu3O7-δ coated conductors. The analysis was performed in a sample with a controlled defect, which causes a significant local reduction in the critical current value, Ic. The experiments, which were performed with the sample surrounded by nitrogen vapor, have shown that the location of the initial hot spot leading to the complete transition to the normal state of the conductor (quench) is strongly dependent on the sample cooling configuration. When the sample is mainly cooled by gas convection, the quench always starts in the low-Ic region, while for improved cooling configurations the initial hot spot does not always coincide with this region. The results have been compared with those obtained by direct electric field measurements along the sample in nitrogen vapor and liquid. [ABSTRACT FROM AUTHOR]

It is well known that in order to increase the chances of survival after an avalanche accident, the rescue time has to be minimized. Therefore, the accurate and prompt location of an avalanche victim is of vital importance. Nowadays, searching with avalanche transceivers is the only reliable method for locating a completely buried victim immediately after an accident. The present work is firstly focused on the magnetic field pattern generated by an avalanche transceiver and how it is perceived depending on the number of receiving antennas. The influence of the snow and soil media is theoretically studied. The computations show that the magnetic field is notably distorted by the soil at distances from the transmitter that can take place during the signal and coarse search. The location of the victim is usually directly inferred from the maximum signal position. However, the computations clearly show that this can be wrong. There is a location error limited to 50% of the burial depth for one and two-antenna receivers whereas for three-antenna transceivers, assuming location takes place within the third antenna range, this figure is reduced to 25% of the burial depth. Furthermore, real tests show that the cross-like search method using three-antenna receivers can be inefficient depending on the algorithm used for the distance calculation for burial depths greater than 1.5 m. As a result, a new search technique, called the bisector method, is proposed and experimentally validated. In addition, a new transmission mode mainly directed to minimize the location error is suggested. This is a vertical transmission that can optimize the search. The present theoretical and experimental outcomes will contribute to further progress in rescue operations conducted with avalanche transceivers. [ABSTRACT FROM AUTHOR]

Underground mapping is of paramount importance at archaeological sites with natural or man‐made caves. Techniques of different complexity are available for underground surveying, from compass and tape to light detection and ranging (LiDAR). However, there are scenarios where it is impossible to use heavy and/or delicate instrumentation, or with some of the more advanced techniques, long‐distance and time‐consuming fieldwork would be required. This is the case of the study of the height of water at key points inside the aquifer located in the subsoil of the Roman city of Colonia Clunia Sulpicia to assess its relation with the evolution of the city. Although subsurface radiolocation, a technique originally intended for cave mapping, seems promising for this application, its accuracy in depth estimation is not sufficient for this purpose. Therefore, the main objectives of this work are to improve the accuracy of depth estimation using radiolocation, to obtain sound data to study changes in water supply in the early centuries of the city and to hypothesize possible causes and probable consequences. Then, this work analyses the sources of error affecting the radiolocation process and develops a new method experimentally validated to improve the depth estimation accuracy. As a result, the depth of key points at Clunia has been accurately measured by radiolocation, where LiDAR or direct measurements from the water level are not possible. Finally, based on the resultant data, a chronology of the city in relation to the aquifer, and vice versa, is outlined. The new radiolocation and calculation procedure proposed in this paper is an improved subsurface location technique that can lead to a significant innovation in archaeological prospection. [ABSTRACT FROM AUTHOR]

Time domain reflectometiy (TDR) is a technique that allows simultaneous estimates of apparent permittivity (ϵa) and hence volumetric water content (θ) and bulk electrical conductivity (σa). Difficulties arise for θ and σa determination, however, when uncoated TDR probes (UP) are used in highly conductive media. This work shows that σa can be estimated in highly conductive media using a TDR probe coated with a high-dielectric insulator (CP). To this end, the Dalton method for σa estimations was applied to a 10-cm-long three-rod TDR probe insulated with a 0.2-mm-thick epoxy-ceramic composite coating with a relative permittivity, ϵr, of 32.3. This method was calibrated on different NaCl-water solutions (0-15 dS m-1) and compared with the standard long-time TDR method for σa estimations using an UP. The method was subsequently used for determining σa in four different soils with different values of θ and σa (0-6 dS m-1) and again compared with the standard TDR procedure. The low error (RMSE = 1.5) for the comparison between the ϵa measured with the CP and that calculated with the analytical solution for coaxial probes indicates that the CP is accurate enough for ϵa estimations. For σa values <4 dS m-1, the UP allows determinations of ϵa and the most accurate estimations of σa using the standard TDR method (R2 = 0.99). For higher σa values, however, estimations of ϵa were only possible using the CP, where σa was satisfactorily determined (R2 = 0.99) using the Dalton method. To this end, a previous calibration between the real and the apparent bulk electrical conductivity estimated with the CP was required. [ABSTRACT FROM AUTHOR]

Discusses a study which determined the crystal structure and magnetic properties of the layered compound Co(HPO[sub3]) H[sub2]O. Formation and refinement of the structure; Description of the structure; Characterization of the magnetic properties of the sample.

Presents an abstract of a study on the structure and magnetic properties of Bi[sub2]CuO[sub4]. Reason for the great interest in the magnetic properties of copper oxides; Description of the nuclear structure.