Abstract: An acoustic navigation system includes a vessel and an interrogation unit towed behind the vessel below the surface of the water, a tail acoustic transponder trailing behind the interrogation unit, and a pair of surface acoustic transponders towed behind the vessel on the surface of the body of water. The interrogation unit generates an acoustic interrogation signal and receives responses from each of the tail acoustic transponder and the surface acoustic transponders from which it triangulates its position. The surface acoustic transponders may further include GPS receivers for receiving positioning information from GPS satellites. Additional acoustic transponders on instruments located on the floor of the body of water respond to the interrogation signal to allow triangulation of the location of the instruments.

Abstract: A method of estimating a property of an earth formation penetrated by a borehole includes: disposing into the borehole a sensor having a plurality of return electrodes and at least one transmitter electrode disposed in a concentric arrangement; injecting a first current of a first frequency into the formation by applying an alternating current voltage between first selected ones of the plurality of return electrodes and the at least one transmitter electrode; injecting a second current of a second frequency into the formation by applying an alternating current voltage between second selected ones of the plurality of return electrodes and the at least one transmitter electrode; measuring effective impedance for each of the currents; and estimating the property using the measurements of the effective impedance for each of the currents; wherein the estimating compensates for an influence of standoff distances of the sensor on the measurements.

Abstract: An apparatus for ascertaining and/or monitoring fill level of a medium in a container. The apparatus includes an antenna, which transmits and receives high frequency signals in a predetermined oscillatory mode in a bounded space in a predetermined radiation direction, wherein, in front of the antenna in the radiation direction, an antenna protection element of a material transmissive for the high frequency signals is provided, and wherein a control/evaluation unit is provided, which evaluates the received high frequency signals and ascertains the fill level.

Abstract: A method of estimating standoff in a borehole through an earth formation, includes: disposing a sensor including a plurality of return electrodes and at least one transmitter electrode disposed in a concentric arrangement into the borehole; injecting current, I, into the formation by applying at least two frequencies of alternating current (AC) voltage between at least two of the electrodes; measuring impedance, Z, for each of the frequencies; and using a predetermined relationship between impedance, Z, and standoff, estimating the standoff. A system and a computer program product are provided.

Abstract: Method for removing air wave noise from shallow water controlled source electromagnetic survey data, using only the measured data and conductivity values for sea water (140) and air. The method is a calculation performed numerically on CSEM data and resulting in an estimate of those data that would have been acquired had the water layer extended infinitely upward from the seafloor. No properties of the sub-sea sediments are used. Synthetic electromagnetic field data are generated for (a) an all water model (141) and (b) an air-water model (146-147) of the survey region. These simulated results are then used to calculate (148-150) electromagnetic field values corresponding to a water-sediment model with water replacing the air half space, which represent measured data adjusted to remove air wave noise.

Abstract: The apparatus for analyzing a delay defect of the present invention obtains the RC of the maximal incidence among region codes (RCs) to which check circuits detecting errors caused with gradual increase in the frequency of an operational clock pulse fed to an integrated circuit belongs. The apparatus obtains information on latch in which an error is caused with the RC of the maximal incidence, with reference to a mapping table that describes the mapping relationship between an RC and a latch. The apparatus extracts a circuit portion in which an error can be captured with the region code of the maximal incidence by exhaustively tracing back circuit portions connected with each obtained latch, from the latch to the latch described in the mapping table. The apparatus gives delay defects to the input and the output pin of each of logic elements included in the extracted circuit portion, generates test patterns for detecting the given delay defects, and performs delay tests.

Abstract: Resistivity measurements are made at a plurality of frequencies. An asymptotic high-frequency limit is determined and the electrical efficiency is estimated as a ratio of the high frequency resistivity limit to the low frequency resistivity. From the electrical efficiency, petrophysical parameters of a rock such as porosity and water saturation can be estimated. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: The use of Electrical Impedance Tomography (EIT) to map subsurface hydraulic conductivity. EIT can be used to map hydraulic conductivity in the subsurface where measurements of both amplitude and phase are made. Hydraulic conductivity depends on at least two parameters: porosity and a length scale parameter. Electrical Resistance Tomography (ERT) measures and maps electrical conductivity (which can be related to porosity) in three dimensions. By introducing phase measurements along with amplitude, the desired additional measurement of a pertinent length scale can be achieved. Hydraulic conductivity controls the ability to flush unwanted fluid contaminants from the surface. Thus inexpensive maps of hydraulic conductivity would improve planning strategies for subsequent remediation efforts. Fluid permeability is also of importance for oil field exploitation and thus detailed knowledge of fluid permeability distribution in three-dimension (3-D) would be a great boon to petroleum reservoir analysts.

Abstract: An improved method and apparatus for electromagnetic surveying of a subterranean earth formation beneath a body of water. An electric dipole current source is towed from a survey vessel in a body of water substantially parallel to the surface of the body of water and separated from the floor of the body of water by a distance less than approximately one-quarter of the distance between the surface and the floor. Alternating electric current, preferably including a plurality of sinusoidal components, is caused to flow in the source. An array of electric dipole detectors is towed from the survey vessel substantially collinearly with the current source. Each electric dipole detector of the array is separated from the current source by a distance substantially equal to an integral number of wavelengths of electromagnetic radiation, of frequency equal to that of a sinusoidal component of the source current, propagating in the water.

Abstract: The depth to and size of an underground object may be determined by sweeping a CSAMT signal and locating a peak response when the receiver spans the edge of the object. The depth of the object is one quarter wavelength in the subsurface media of the frequency of the peak.