Abstract: A magnetic rotational position sensor senses each rotational position of a control shaft about a first rotational axis over a definable range of rotation of the control shaft. The magnetic rotational position sensor includes a magnetic circuit, a magnetic flux sensor, a drive circuit, and an output signal amplifier. The magnetic circuit encloses an equally balanced magnetic field, and is adjoined to the control shaft to synchronously rotate the magnetic field about a second rotational axis. The magnetic flux sensor is disposed within the magnetic field to sense each rotational position of the control shaft as the control shaft is rotated about the first rotational axis over the definable range of rotation. The drive circuit is operable to generate a constant current drive signal and a constant voltage drive signal.

Abstract: The present invention relates to an acoustic logging system having a sonde for arranging in a borehole of a well such as an oil well. The sonde has at least one transmitter for providing at least one transmitter acoustic signal, and has receivers for responding to the at least one transmitter acoustic signal, for providing receiver signals containing information about properties of earth formations in the borehole. The acoustic logging system features one or more transducers, a light source, an optical fiber and a detection and management unit. The one or more transducers responds to the receiver signals from the receiver of the sonde, for providing one or more mechanical transducer forces containing information about the receiver signals. At least one transducer may be a piezoelectric or magnetostrictive transducer. The light source provides an optical signal.

Abstract: An apparatus for positioning a detection device for monitoring a rotatable machine element. The apparatus for positioning a detection device for monitoring a rotatable machine element includes a rod having one end removably mountable on the rotatable machine element. A plate is securable to the rod. A bearing assembly is engagable with the rod. A carriage is attachable to the bearing assembly for holding the detection device adjacent the plate for monitoring rotation of the rotatable base piece.

Abstract: A fan speed detecting circuit includes a resistor installed in the grounding line of the power circuit of the DC fan motor of a cooling fan, a capacitor, a diode connected between the resistor and the capacitor, and a comparator having an inverter terminal connected to the output end of the diode through the capacitor and a non-inverter terminal connected in parallel to the input end of the diode, wherein a transient pulse current is produced at the resistor upon operation of the DC fan motor, causing the comparator to output a pulse frequency wave indicative of the revolving speed of the DC fan motor.

Abstract: The invention relates to an electromagnetically controlled measuring apparatus for the volumetric measurement of the quantity of fuel injected by a fuel injection pump that has a displacement transducer which is surrounded by cooling chambers. The apparatus also includes a differential coil pair and a magnetically conductive core, which can be guided axially therein. The coil and the conductive core constitute part of a lifting rod connected to a measuring piston, with a coil carrier and a housing surrounding the coil carrier. The magnetically conductive core consisting of a ferritic material and being firmly surrounded by a sleeve, which forms the lifting rod, is not magnetizable and is provided with a slot extending continuously in the longitudinal direction of the sleeve.

Abstract: A transducer configuration for use in acoustically imaging a target region behind an acoustically reflective layer includes a sonde having a geometrical center and constructed and arranged to support a plurality of transducers. The system includes a first transducer disposed within the sonde at a first distance from the geometrical center for generating a first acoustic pulse and for receiving a first acoustic signal. The acoustic signal comprises a first reflection from the reflective surface, a first set of fluid multiples arising from reflections between the reflective layer and a surface of the first transducer, and a first signal associated with the target area. The system also includes a second transducer disposed within the sonde at a second distance from the geometrical center for generating a second acoustic pulse and for receiving a second acoustic signal.

Abstract: A method for determining thermal neutron capture cross-section of an earth formation penetrated by a wellbore from counts of capture gamma rays detected at spaced apart locations from a source irradiating the formations with bursts of high energy neutrons. An apparent capture cross-section is determined from counts detected at one of the spaced apart locations. The apparent capture cross-section is adjusted by a correction factor calculated from counts detected at each of the spaced apart locations. The correction factor is calculated from an empirical relationship of known values of formation capture cross-section, wellbore diameter and wellbore capture cross section, with respect to counts detected at each of the spaced apart locations. Coefficients of the empirical relationship are determined by simulating counts which would be detected in response to the known values of formation capture cross-section, wellbore diameter and capture cross section.

Abstract: A variable length data packet in a seismic system includes a fixed-length data portion and a variable-length data portion, the amount of data in the variable-length portion depending on the number of active channels. The data packet identifies the number channels which are in operation in the system, which may be the same or fewer than the number of installed channels. This signals the central recorder as to the length of the block of data in the data packet which includes seismic data. This feature permits the scaling of the system to accommodate varying numbers of channels, without reconfiguring the system. In another aspect, a method of sending data in a data system having a plurality of installed channels includes the steps of determining the number of active channels; assembling a packet of data comprising a fixed-length field and a variable-length field, the number of data bytes in the variable-length field being a function of the number of active channels; and sending the packet of data.

Abstract: A magnoresistance effect element made up of an anti-ferromagnetic layer, a fixed magnetic layer, a non-magnetic and a free magnetic layer, laminated successively onto a base layer. The ant-ferromagnetic layer is a layer film or multiple layer film comprising Ni oxide, Co oxide, or Fe oxide as a principal component, or a mixture of these. An adhesive layer for preventing peeling due to heat generated by the flow of current is provided between the base layer and the anti-ferromagnetic layer. By providing an adhesive layer between the base layer and the ferromagnetic layer in this way, the adhesive force between the base layer and the anti-ferromagnetic layer is increased, and therefore peeling does not occur, even if there are temperature changes in the magnetoresistance effect element.

Abstract: Method for generating seismic intersection waves in an underground formation, wherein poles that are previously driven into the formation for other purposes or poles that are driven down for this purpose, said poles being used as a transfer medium for the intersection waves into the formation. The poles are put into transversal vibration by means of an oscillating mass, the oscillations being suitable for forming mainly horizontal polarized waves. In order to achieve a best possible impression of the formation, transversal waves may be generated in a first direction in a first period of time, and a second direction, different from the first direction, in a second period of time. Alternatively, the oscillating mass can be arranged to swing parallel to the pole in order to be able to generate pressure waves. The poles can be equipped with a "skirt", and/or with radially extending flanges in order to secure the best possible attachment in loose formations.

Abstract: A method and a device for operating a position sensor made of at least two parts that move in relation to one another. The first part of the position sensor has at least two sections magnetized in different directions, and the second part has at least one magnetic field sensor which detects the magnetic field of the first part and converts it into signals having two levels depending on the polarity of the component of the magnetic field in a predefined spatial direction. The levels are supplied to a signal-processing arrangement which evaluates them to determine the relative position of the first part in relation to the second part.

Abstract: A method for determining a representation of an anisotropic earth formation is described, wherein the inversion step for generating the representation from recorded seismic data is performed using several values of a pre-defined anisotropy parameter addition to components of the moveout velocity. The anisotropy parameter is preferably introduced into the moveout equation or dispersion relation, which in turn is used in the inversion process.

Abstract: The general object of the present invention is to provide a method for determining and displaying the relative changes of elastic moduli and that of density of geologic formations and for utilizing these relative changes and plottings for gas/oil exploration, especially for direct gas and light oil detection. The said relative changes of elastic moduli are the relative change of Lame constant .DELTA..lambda./(.lambda.+2.mu.), the relative change of shear modulus .DELTA..mu./(.lambda.+2.mu.) and/or .DELTA..mu./[.kappa.+(4/3).mu.], the relative change of bulk modulus .DELTA..kappa./[.kappa.+(4/3).mu.]; and the relative change of density is .DELTA..rho./.rho..

Abstract: A system and method for periodically providing information about subsurface formations in a marine environment using a non-towed seismic signal source (3) and a static array of seismic signal receivers (4) is disclosed. The seismic signal source (3) comprises a support frame (10) and a line (7) attaching the support frame to a stationary platform (2), wherein the line (7) restrains the support frame (10) in a position that is static in relation to the formation (8). The seismic signal source (3) includes eight air guns (12) attached to the support frame (10) such that the air guns (12) are discharged to provide a tapered, heavy centered, point source seismic signal at a specific location relative to the formation (8) that is reflected to the static array of seismic signal receivers (4) such that changes in the formation characteristics may be observed over time.

Abstract: In a method for detecting the rotational angle (.alpha.) of a rotatable shaft, in which two sinusoidal signals are generated by rotation of the shaft, the signals having a phase shift of 90.degree. with respect to one another, and being standardized, and in which the signal values of the two signals are measured at the desired rotational angle (.alpha.), the following provisions are made:a) the signal values that are larger than the standardized maximum value or smaller than the standardized minimum value are limited to the maximum or minimum values;b) from the value of the measured signals, the quadrant is determined in which the desired angle (.alpha.) is located;c) depending on the sign of the respective curve slope, the sign of the signal value is changed or retained;d) the adapted signal values thus obtained are added to produce a first sum (S);e) the following equation is valid for the angle difference (.beta.) between the middle of the determined quadrant and the desired angle (.alpha.

Abstract: A device for retrieving ocean bottom seismic cable as the cable is pulled up from the bottom and hauled aboard a vessel. The cable is first led over a front wheel located on an arm which is pivotally mounted for movement about an axis. The cable is then passed under a second wheel before it is brought aboard the vessel, optionally via one or more additional wheels. A damper is provided between a fixed point on the arm, spaced apart from the axis and a fixed point on the vessel, so that the front wheel is raised in response to lower tension in the cable and is lowered in response to an increase in tension in the cable, thereby counteracting any variations in the tension of the cable.

Abstract: A method of determining an optimum processing sequence by calculation of processing sequence sensitivity and processing sequence error. A reference seismic processing sequence is applied to input raw gathers to obtain reference seismic output data. A series of test seismic processing sequences are applied to the input raw gathers to obtain test seismic output data. The RMS value of the test seismic output data is normalized to that of the reference seismic output data on a trace by trace basis. The normalized difference between the test and the reference seismic output data is calculated on a sample by sample basis in the time domain and are displayed on color coded plots in the time scale format over the CDP range. Linear regression is performed for each CMP gather to obtain the stack and the zero offset calculated for each time index and the difference is recorded. The normalized differences between the error for the test and the reference sequences are calculated and displayed on color coded plots.

Abstract: A computationally efficient semi-recursive Kirchhoff migration algorithm is capable of obtaining accurate images of complex structures in complex geological environments which commonly give rise to multivalued arrivals. The method alternates wave-equation datuming (downward continuation) and Kirchhoff migration. Breaking up the complicated velocity structure into small depth regions allows traveltimes to be calculated in regions where the computation is well behaved and where the computation corresponds to energetic arrivals. Because traveltimes are computed for small depth domains, the effects of multivalued arrivals are implicitly accounted for in the migration and the adverse effects of caustics and headwaves do not develop. The invention can use any simple first-arrival traveltime algorithm, and thus benefits from the computational efficiency, robustness, and simplicity of such algorithms.

Abstract: A Petragrid method and apparatus generates grid cell property information that is adapted for use by a computer simulation apparatus. An interpretation workstation includes at least two software programs stored therein: a first program called "Petragrid" and a second simulation program for generating a set of simulation results for display. The first Petragrid software program will: receive well log and seismic data which indicates each layer of a formation, grid each layer of the formation where the grid is comprised of a plurality of cells, and generate more accurate data associated with each grid cell, such as the transmissibility. The more accurate data for each cell will be transmitted to the second simulation program which will respond by generating a set of more accurate simulation results for each cell of the grid, and overlaying the more accurate simulation result for each cell onto each of the corresponding cells of the grid being displayed on the workstation display by the Petragrid software.

Abstract: The method consists in building a common midpoint gather of seismic traces of which the CMP point is said given point, subjecting the traces of this gather to dynamic and/or static corrections, and characterized in that the gather associated with the given point (A) is built by recording four CMP sub-gathers associated with said given point along four angular directions (1 to 4) passing through said given point, and dynamic and/or static corrections are applied to each of the four CMP sub-gathers in order to determine, for each sub-gather, a value of the curvature and/or the velocity optimizing the energy of the trace stack of the corrected sub-gather concerned, the four values thus obtained representing the components of the stacking velocity field desired for each of the reflector elements corresponding to the given point, and characterized by a vertical propagation time t0 with reflection for zero offset.Application in particular to the exploration of a medium with a complex tectonics.