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Time domain reflectometry (TDR) is a technique that allows simultaneous estimates of apparent permittivity ([epsilon].sub.a]) and hence volumetric water content ([theta]) and bulk electrical conductivity ([[sigma].sub.a]). Difficulties arise for [theta] and [[sigma].sub.a] determination, however, when uncoated TDR probes (UP) are used in highly conductive media. This work shows that [[sigma].sub.a] 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 [[sigma].sub.a] 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, [[epsilon].sub.r], of 32.3. This method was calibrated on different NaCl--water solutions (0-15 dS [m.sup.-1]) and compared with the standard long-time TDR method for ([[sigma].sub.a] estimations using an UP. The method was subsequently used for determining [[sigma].sub.a] in four different soils with different values of [theta] and [[sigma].sub.a] (0-6 dS [m.sup.-1]) and again compared with the standard TDR procedure. The low error (RMSE = 1.5) for the comparison between the [[epsilon].sub.a] measured with the CP and that calculated with the analytical solution for coaxial probes indicates that the CP is accurate enough for [[epsilon].sub.a] estimations. For [[sigma].sub.a] values Abbreviations: CP, high-dielectric coated time domain reflectometry probe; DC, direct current; TDR, time domain reflectometry; UP, uncoated time domain reflectometry probe.

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]

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]

Digital speckle pattern interferometry is used for detecting inhomogeneous heating in Y[Ba.sub.2][Cu.sub.3][O.sub.7-[delta]] coated conductors. The experiments have shown that the location of the initial hot spot leading to the complete transition to the normal state of the conductor is dependent on the sample cooling configuration and the results are compared with those obtained by direct electric field measurements along the sample in nitrogen vapor and liquid.

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.

Abstract: Time Domain Reflectometry is a technique widely used in hydrology and agronomy that allows real time estimation of soil volumetric water content (θ), which is related to soil's apparent permittivity (ɛa) and bulk electrical conductivity (σ). This work presents an enhanced release of TDR-Lab, software which controls instrumentation for field measurements of θ and σ, enabling a convenient recording and retrieving of data. TDR-Lab 2.0 supports Tektronics 1502C, TDR-100 Campbell Sci. and TRASE Soil-moisture Equipment Corp., which can be connected to a multiplexing system (SDMX50, Campbell Sci) allowing automated scheduled measurements from up to 251 different probes. This new release, when connected to TDR-100, allows increasing the waveform accuracy up to 2048 points/waveform. Multiple comparison of TDR waveform within the same TDR screen is now allowed. Graphical or numerical methods can be used for the estimation of θ and σ from soil measurements coming taken with different probes. Additional features to carry out water-surface-level measurements such as matric potential and soil solution electrical conductivity are also available when measurements are made using the corresponding specific probes. Two different versions, a lite and a full release, for field and laboratory applications have been developed. The light version with a reduced set of features (TDR-Lab Lite) was designed to run in low-end ultraportable devices. TDR- Lab Lite works with XML-files instead of the SQL database engine of the extended TDR-Lab, and has lower system requirements and a faster boot-up time. A robust import/export graphical user interface (GUI) facilitates transferring projects between the centralized SQL database and XML files. A new project manager window has been implemented, where the bar menu has been complemented with a useful set of icons. The display system projects has been improved and simplified. Within the project, a new friendly configuration manager for cables and TDR probes has been developed. Finally, an improved calibration procedure for TDR probes has been implemented. TDR Lab 2.0 supports more devices and provides additional estimated features from soil's measurements. Besides, the low hardware requirement of TDR-Lab Lite facilitates faster in-the-field tests and measurements. [Copyright &y& Elsevier]

The water retention curve (θ(ψ)), which defines the relationship between soil volumetric water content (θ) and matric potential (ψ), is of paramount importance in characterizing the hydraulic behaviour of soils. However, few methods are so far available for estimating θ(ψ) in undisturbed soil samples. We present a new design of TDR-pressure cell (TDR-Cell) for estimating θ(ψ) in undisturbed soil samples. The TDR-Cell consists of a 50-mm-long and 50-mm internal diameter stainless steel cylinder (which constitutes the outer frame of a coaxial line) attached to a porous ceramic disc and closed at the ends with two aluminium lids. A 49-mm-long and 3-mm-diameter stainless steel rod, which runs longitudinally through the centre of the cylinder, constitutes the inner rod of a coaxial TDR probe. The TDR-Cell was used to determine the θ(ψ) curves of a packed sand and seven undisturbed soil samples from three profiles of agricultural soils. These θ(ψ) curves were subsequently compared to those obtained from the corresponding 2-mm sieved soils using the pressure plate method. Measurements of bulk electrical conductivity, σa, as a function of the water content, σa(θ), of the undisturbed soil samples were also performed. An excellent correlation ( R2 = 0·988) was found between the θ values measured by TDR on the different undisturbed soils and the corresponding θ obtained from the soil gravimetric water content. A typical bimodal θ(ψ) function was found for most of the undisturbed soil samples. Comparison between the θ(ψ) curves measured with the TDR-Cell and those obtained from the 2-mm sieved soils showed that the pressure plate method overestimates θ at low ψ values. The σa(θ) relationship was well described by a simple power expression ( R2 > 0·95), in which the power factor, defined as tortuosity, ranged between 1·18 and 3·75. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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]

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.

The time domain reflectometry (TDR) technique allows simultaneous estimation of apparent permittivity (εa) and bulk electrical conductivity (δa). In highly conductive media, however, the signal is completely attenuated, which precludes permittivity measurements. This study showed that δa can be estimated in conductive media by applying long-time TDR waveform analysis to a TDR probe partially insulated with a high-dielectric coating. Four 10-cm-long three-rod TDR probes with identical geometry but different percentages of rod coating were tested: an uncoated sensor (P0) and probes with 50% (P50), 75% (P75), and 95% (P95) of the rod length coated with an insulator with a relative permittivity (εr) of 32.3. A good relationship (r² = 0.99) was found between the εa estimated, if possible, with P0 immersed in several conductive and nonconductive media and the corresponding values estimated with P50, P75, and P95 The results also show that, for δa values ranging between 0.4 and 0.75 S m-1, simultaneous measurements of εa and δa were only possible using the partially coated probes. A good correlation was found between the δa estimated with P0 inserted in different soil columns wetted with highly saline solutions (i.e., δa > 0.2 S m-1) and those values estimated with P50, P75, and P95 (r² = 0.96, RMSE = 1.08, and SD = 0.38). For δa < 0.2 S m-1, the accuracy of the partially coated TDR probes for estimations of δa decreased as the percentage of the rod coating increased, with errors up to 292% when δa determined by P95 was compared with that estimated by P0. [ABSTRACT FROM AUTHOR]