Abstract: The bearing structure such as a wing is fitted with toothed platelets (16) at its free edges to break tip vortex produced at these places by fluid pressure distribution. Vortex dissipation is accelerated, vortex remanence is considerably reduced. In the case of a deflector for a line of hydrophones (30) towed by a ship (31) to carry out seismic tests at sea, the noise disturbing the hydrophones (30) is reduced. In the case of marine applications, risks of cavitation are much reduced, particularly with regard to stabilizers or propellers. In the case of aeronautics applications, vortex remanence on take-off and on landing of planes is reduced.

Abstract: A method of seismic surveying using one or more vibrational seismic energy sources activated by sweep signals. The highest order harmonic that has sufficient strength to cause significant harmonic distortion of a sweep segment is determined. A number of sweep segments in excess of the number of sources is selected. Initial phase angles are selected for each sweep segment of each seismic energy source so that substantially all harmonics up to and including the highest order harmonic are suppressed. Using cascaded sweeps, seismic data are acquired and processed to substantially attenuate harmonics upto the selected order.

Abstract: A rear view mirror for a vehicle has a reflective member mounted for angular movement about a pivot axis perpendicular to a plane containing both a first line and a second line. The first line bisects the angle between an incident ray and a reflection of said incident ray extending to a first end of the major axis of a vertical section through the eyellipse, and the second line bisects the angle between said incident ray and a reflection of said incident ray extending to a second end of said major axis.

Abstract: An apparatus and system for integrating acoustic pods within marine seismic streamers. The integrated acoustic pod eliminates the attachment and detachment of acoustic pods from the streamer exterior surface when the seismic streamers are deployed into and retrieved from the water. Control electronics are integrated within the streamer interior and receive electric power from a streamer electrical conductors and receive control signals from a streamer control wire. The control electronic components can be integrated within the streamer interior or within modules connecting each streamer section. Acoustic transducer elements can extend through the connector module or can be attached to the connector module exterior. The acoustic transducer elements can be oriented to steer transmission of acoustic energy into the water, such as in a horizontal azimuth, and to permit correction of the steering direction.

Abstract: An expandible diverter for use in marine seismic operations. The diverter is stored in a retracted position for transport and handling, and is expandible to increase the amount of surface area in contact with the water. The diverter can be formed with two or more moving components, and can comprise an expandible body. A controller can increase or decrease the amount of surface area in contact with the water to meet different conditions, and can control movement of the diverter as seismic vessel tows the diverter through the water.

Abstract: A rear view mirror for a vehicle has a reflective member mounted for angular movement about a pivot axis perpendicular to a plane containing both a first line and a second line. The first line bisects the angle between an incident ray and a reflection of said incident ray extending to a first end of the major axis of a vertical section through the eyellipse, and the second line bisects the angle between said incident ray and a reflection of said incident ray extending to a second end of said major axis.

Abstract: The processing of surface seismic data may be monitored where vertical seismic profile data are available for the same region. A trace (45) of the vertical seismic profile data recorded from a geophone at the surface is compared with data generated by the data processing before completion of migration and provides a measure of the quality of the data processing. Alternatively, a derived trace may be derived by taking sections of the vertical seismic profile data traces along a section curve (47). The derived trace may be thought of as partially migrated data and may similarly be used for monitoring the quality of surface seismic data processing.

Abstract: An exterior mirror for a motor vehicle has a housing received within a recess in a vehicle body. A mirror support is mounted in the housing for angular movement between a deployed position and a stowed position in which the mirror support is contained within the housing.

Abstract: A device and method of replacing an electronics module in a seismic cable on the open sea, where the replacement is carried out with the aid of a small boat equipped with cable rollers, the method including positioning the part of the cable including the electronics module on a first and a second cable roller respectively in such a way that the electronics module and its couplings are located between the two rollers, clamping the sections of cable on either side of the electronics module in a first and a second clamping arrangement, respectively, with the clamping arrangements connected together via a mechanical tensioning device, moving the clamped sections of cable towards each other using the tensioning device in such a way that the tension in the seismic cable is taken up by the tensioning device, after which the electronics module can be removed and replaced after which the tensioning device is slackened slightly and the clamping arrangement is released from the sections of cable before the part of the s

Abstract: A plurality of seismic traces are arranged in order of increasing of feet and features therein are analyzed so as to identify corresponding features in each of the curves. The travel time to each of the features is derived in order to extract an actual travel time curve as a function of offset.

Abstract: A technique is provided for controlling the quality of processed seismic data without requiring subjective intervention. Seismic data, for instance acquired by land or marine techniques, are supplied as input (1) and a portion for testing is selected (2). First and second combinations of seismic data processing steps are selected (3 and 6). The selected data portion is processed (4 and 7) using these combinations and the thus-processed portions are analyzed to calculate the attributes thereof (5 and 8). These measures are compared (9) and the combination of processing steps giving the better attributes is then used to process the input seismic data (10 or 11).

Abstract: A method and apparatus for controlling the operation of a multiple-element marine seismic pulse generating source in rough sea surface conditions. The method first determines the shape of the path along which the elements are traveling at the point in time just before each element of the source is activated. Once the shape of the path is known, the relative vertical position of each element relative to a fixed reference is determined. Adjustments can then be entered into the firing times for each element such that the primary pressure peaks constructively interfere with one another. In a preferred embodiment, a plurality of inclinometers associated with the harness from which the devices are suspended provides a tilt angle measurement from which the shape of the path can be determined and the firing times adjusted accordingly.

Abstract: The present invention enables both deep marine seismic surveys and site seismic surveys to be performed simultaneously. A survey vessel tows a first seismic array (6, 16, 20) for a deep survey and a second seismic array (6, 16, 20) for the site survey. The arrays are operationally distinct but may share common physical components.

Abstract: In a method for integrity monitoring in position determination by means of the Global Positioning System (GPS), especially by means of differential GPS (DGPS) or multi-station DGPS, wherein there is employed a monitor station (M) with a first GPS receiver, provided at a location with a known geographical position, GPS-based position measurement results are transferred on a communication line from the monitor station (M) to a user location (F) the integrity of whose geographical position has to be monitored by means of a second GPS receiver provided at the location (F).

Abstract: An exterior rearview mirror for a vehicle comprises a base member (10) adapted to be secured to a vehicle body, and a mirror head (56, 78, 82) mounted on the base member (10) for angular movement about a substantially vertical axis between a position of normal use and a position folded alongside the motor vehicle body. A detent (102) is adapted to hold the mirror head (56, 78, 82) in its normal position, an electric motor (142). A cam powered by the electric motor (142) is arranged to cause movement of the detent (102) out of engagement during an initial phase of movement and to cause angular movement of the mirror head (56, 78, 82) away from its normal position during a subsequent phase of movement.

Abstract: A method for acquisition of seismic data from an area surveyed using a group of seismic energy sources and a group of seismic streamer cables, particularly a marine area, includes forming a first group A from at least two elements of either seismic energy sources S or seismic streamer cables C having a spacing X between said elements, forming a second group B from at least two of the other elements of sources S or cables C than that forming group (A), spacing the elements in group B a distance equal to X multiplied by the number of elements in group A, forming a group C from at least two subgroups each consisting of a group A, spacing said subgroups in group C in distance equal to the distance between two elements in group B multiplied by the number of elements in group B, the spacing between two adjacent subgroups being equal to the lateral distance between midpoints between the subgroups, and forming further groups as desired D, E, F etc.

Abstract: A semi-dry marine seismic streamer cable (5) consists of a number of connected streamer cable sections (5a) which each comprises a mechanical jacket (10) surrounding a hollow core (11) enclosing seismic sensor (15) and signal transfer (16) means. Elongated axial stress elements (18) for transmitting axial loads and a radial reinforcement member (12) for relieving radial loads are provided in the jacket (10). The core (11) is filled with a fluid or a fluid-saturated foam and the sensor means (15) are mounted in the core (11) by vibration isolating elements (14).

Abstract: A method for determining the position of seismic equipment wherein acoustic transmitters transmit spread spectrum sequences which are received by the seismic sensors in the equipment whose position has to be determined. By collecting and processing the signals thus produced, it is possible to determine the position of seismic equipment with reference to each individual sensor in the seismic equipment each time a measurement is take. The already existing conventional seismic sensors which are provided in a streamer are used to record the transmitted spread spectrum signals. By calculating time differences between the sensors' reception of a spread spectrum signal it is possible to calculate the position of the seismic equipment.

Abstract: A method is described that attenuates reverberations in ocean bottom cable data used to generate a seismic profile. First, a seismic wave is generated and recorded by pressure and particle velocity sensor pairs. Adding the product of the pressure data times the absolute value of the velocity data and the product of the velocity data times the absolute value of the pressure data eliminates reverberations, leaving a combined signal that is a function of only the primary wave response signal. Dividing this combined signal by the number 2 and a sensitivity scaling factor, and then taking the square root of the result produces the magnitude of the primary signal. Replacing the positive/negative sign of the combined signal that existed before taking the absolute value provides the proper polarity. The data are then incorporated into a seismic profile.

Abstract: The seismic profile system and method using vertical sensor arrays relate to obtaining a seismic profile under two highly reflective boundaries. The system includes a source of seismic energy disposed beneath the air/water boundary, a first pair of sensors arranged in vertical relation and spaced apart by a predetermined vertical spacing distance, and a second pair of sensors similarly situated and spaced from the first pair by a predetermined horizontal spacing distance. The first and second pairs of sensors are disposed below at least two highly reflective boundaries, which may be the air/water boundary and a mud/water boundary. According to the method, the source is moved between two points and data is collected from the first and second pairs of sensors.