Abstract: Apparatus for generating an acoustic pulse in a medium including an upstanding cylindrical housing within which an impact piston supported by retainer springs is adapted to be propelled downwardly by high pressure expanding gas supplied from external high volume accumulators so as to a strike target plate resting on the ground adjacent the lower end of the housing. A small valve in the top of the cylinder is opened to supply sufficient gas pressure to overcome the spring bias and initiate piston motion. When the piston moves downward far enough to expose multiple large area ports in the housing side wall interconnected with the accumulators, the sudden inflow of gas pressure produces rapid piston acceleration and high energy impact with the target.

Abstract: Apparatus for generating an acoustic pulse in a medium including an upstanding cylindrical housing within which an impact piston retained in the upper end of housing by an electrically controlled latch is driven downwardly by compressed gas to strike a target plate positioned adjacent the bottom of the housing. The compressed gas is provided by high volume accumulators interconnected with large area ports penetrating the sidewall of the housing near its top. The tapered upper portion of the piston presses against static seals mounted on the correspondingly tapered housing bore above and below these ports. This taper enables the compressed air to exert a positive break away force on the piston. Quick release of the latch triggers the downward thrust of the piston to deliver a blow against the target plate.

Abstract: The present invention relates to means for coupling the horizontally directed force of a seismic transducer into the earth with a downward going shear wave. The coupling means consists of a plurality of downwardly convergent wedge-shaped earth engaging cleats of differing depth mounted on the transducer support means. The lateral load-bearing surfaces of the cleats have sloping faces equally inclined to the vertical, so that they tend to compact and compress the earth to a similar degree with horizontal vibrator motion. However, on some or all of the cleats these sloping faces are interrupted by horizontal faces in a stair-case fashion so as to vary the overall sharpness of such cleats.

Abstract: Apparatus for generating combined compressional and shear wave signals in the earth which employs a seismic source, such as a cylindrical gas exploder, having a free-moving wedge shaped base which tapers symmetrically downwardly to a thin blade. When the exploder is fired at an angle inclined to the vertical, a force is generated along its longitudinal axis which drives the base downwardly in the same direction so as to propagate seismic signals having a compressional component and a shear component. The blade is disposed transversely to the direction of the horizontal component of this applied force. The penetration achieved by the thin blade portion of the base insures sufficient earth coupling to generate high energy shear seismic signals and minimizes horizontal translation of the exploder under a wide range of soil conditions.

Abstract: A marine seismic source employs a cylindrical gas exploder adapted to be supported from a surface vessel in a submerged state adjacent a marine bottom. The force of expanding gases within the exploder applies a thrust along the exploder longitudinal axis to a ground contact member operatively interconnected with the exploder to produce a seismic signal. The energy producing force is reacted by piston means within the exploder interconnected rigidly with a large area external water interacting disk. The mass of the reaction piston-disk system is sufficiently great so that the slow moving disk experiences viscous damping in the water and thus generates no significant undesirable secondary seismic signal in the water. The exploder may be oriented horizontally for maximum generation of shear waves or inclined at an acute angle to the vertical for generation of a combination of shear waves and compressional waves.

Abstract: A luminescent sheet having two essentially parallel opposed large area surfaces separated by one or more thin edge faces, the sheet being penetrated by one or more tapered, asymmetrically disposed cavities extending from one such surface at least partially through such sheet toward the opposite surface and a corresponding number of photovoltaic cells positioned on such opposite surface in respective concentric alignment with such cavities so that light internally reflected from the convergent side walls of such cavities toward such opposite surface is concentrated onto such cells.

Abstract: A marine seismic streamer to be tested is towed through the water in a fully deployed state past a lightweight, portable acoustic energy source submerged beneath a stationary float. The electrical output of multiple pressure transducers distributed along the streamer is recorded on the towing vessel in response to acoustic pulses generated every few seconds by the source, a separate channel being indicative of the combined transducer output of each streamer section. Output signals failing to exhibit normal wave shape or decay characteristics as the distance varies between individual streamer sections and the stationary source may be indicative of faulty transducers or electrical or mechanical cable failures.

Abstract: A thin, luminescent sheet having upper and lower large area surfaces separated by upstanding edge faces, said sheet being contoured in the vicinity of at least one of said edge faces so as to widen such edge face substantially, and at least one photovoltaic cell carried on and occupying a substantial portion of such widened edge face.

Abstract: A seismic wave generator assembly with self-contained guidance and shock-absorbing means is confined within an elongated, upstanding cylindrical housing which may be lowered into position at the end of a lateral arm or a cable supported from a transport vehicle.

Abstract: Within a stationary upstanding cylindrical housing, a piston and a base member resting on the ground are separated by an expansible detonation chamber. Means are provided for feeding successive charges of a combustible gas mixture into the chamber at a rapid rate and initiating a corresponding series of gas explosions therein. Recoil of the piston following each explosion compresses a first air spring which then forcibly thrusts the piston downwardly. Piston recovery for the next cyclic operation is thereafter slowed by means of a second air spring-dashpot combination.

Abstract: Method and apparatus for electrical logging in a mud-filled borehole by sensing redox potential and other formation characteristics. An elongated, tubular probe body contains reference and potential measuring electrodes which extend longitudinally thereof and are adapted to make external contact with the borehole fluid at the streamlined surface of the probe nose. The metal reference electrode member is immersed in an electrolyte-filled compartment separated from the external borehole fluid by a pressure-compensating diaphragm in the probe side wall, a fluid bridge with the mud of the borehole being established through a permeable ceramic wick. Probe design insures adequate mud flow past the electrodes in a nonturbulent state as the probe is lowered, thus eliminating clogging and providing good electrical contact. Alternate means are provided for maintaining a positive leak pressure regardless of borehole conditions.

Abstract: Within the stationary, upstanding cylindrical housing of a rapid fire seismic gas exploder an expansible detonation chamber is formed between a base resting on the earth and a piston adapted to move reciprocally. A plurality of separate external gas entry conduits communicate with the detonation chamber at spaced apart inlets in the wall of the housing. Each conduit is supplied from its own separate gas mixer which in turn is interconnected with sources of fuel gas and oxidizing gas through a pair of remotely operable flow control valves. As the pairs of control valves are actuated in timed sequence at a desired rate of fire, successive charges of combustible gas mixture are injected into the detonation chamber, utilizing one mixer and its associated gas entry conduit at a time. Correspondingly timed spark ignition is provided in or adjacent each mixer, resulting in a series of gas explosions in the chamber which coordinates with the reciprocal movement of the piston.

Abstract: Within a stationary, upstanding cylindrical housing, a piston and a base member resting on the ground are separated by an expansible detonation chamber. One or more gas inlets communicate with the chamber through which successive charges of a combustible gas mixture may be fed into the chamber at a rapid rate and thereafter ignited to initiate a corresponding series of gas explosions. Each gas inlet is connected to a main gas flow conduit which is supplied from at least two independent mixers through separate branching conduits. The mixers are supplied in rotation from sources of fuel gas and oxidizing gas so that only one branch conduit is in use at a time. Spark ignition occurs at each mixer in the same rotation. The branch conduits are connected to the main gas flow conduits in geometrical arrangements which prevent preignition even in long rapid fire shot sequences.

Abstract: A bi-directional shearing machine mines a longwall face at the bottom of a thick mineral seam in a retreat operation under the protection of a row of adjacent powered roof supports each of which extends in a direction transverse to the solid face. Progressive advance of these roof supports allows the overlying mineral strata to cave. Each roof support is separated into articulated forward and aft units provided with separate sets of hydraulic props and having their solid canopies interfitted in end-to-end relation. The bases of the two units are interconnected with a push-pull hydraulic ram which enables relative longitudinal movement between the two units so that they may be advanced independently along a common axis toward the solid longwall face as the work progresses. During the advance of the forward units to provide face support, plowing and loading of caved mineral on the gob side may proceed without interruption.

Abstract: In the mining of a thick underground mineral seam, parallel submain entries are developed at the top of the seam or at an upper level where a competent roof exists. Spaced apart parallel sets of panel entries are driven at right angles to these submain entries along a downwardly sloping path to the bottom of the seam. The entries are continued coincident with the bottom of the seam to any desired point at which their extremities are connected with bleeder entries so as to define a series of longwall panels. These panels are mined in retreat under the protection of advancing roof support structures so as to induce caving of overlying strata.

Abstract: Radioactive gaseous decay products emanating from a buried deposit of uranium or other radioactive ore migrate upwardly through the earth and are exhaled into the atmosphere. These products may be trapped at the surface in a series of low profile, dome-shaped plastic shelters 5 to 20 feet in diameter. Radiant energy permeating each shelter cover heats the soil beneath the enclosed surface area to accelerate the escape of gas through the soil. The air confined within the shelters is continuously recirculated over the exposed surfaces of a plurality of highly adsorbent discs. After equilibrium decay conditions are reached, the discs are analyzed to determine the radioactivity of the discs, which is proportional to the concentration of radioactive gas in the vicinity.

Abstract: A pair of movable pistons are separated within an enclosed, submerged cylinder by an expansible combustion chamber. Piston rods extend from these pistons through the opposite ends of the cylinder. A pair of dish-shaped, circular plates are carried on the respective extremities of these two rods so that their convex surfaces face inwardly toward the ends of the cylinder in spaced relation. Expansion of an explosive gas mixture within the combustion chamber drives the pistons apart so as to accelerate the plates through the water, producing cavitation bubbles at their convex surfaces. Collapse of these bubbles combines efficiently to produce a single energetic acoustic pulse adapted for seismic prospecting.

Abstract: An expandable ignition chamber within an upstanding cylinder is formed between its base and a massive free piston. Initial detonation of a combustible gas mixture within the chamber drives the piston upwardly to expose in sequence a series of vertically spaced gas inlets in the cylinder wall, through which the supply of gas is replenished to support a corresponding sequence of additional rapidly timed detonations. Repetitive seismic pulses are thereby supplied by the downward thrust of the base which is itself slidable with respect to the cylinder walls.

Abstract: Condensate accumulating in the combustion chamber of a marine gas exploder of the cylinder and piston type is collected by gravity flow in a sump formed in a cylinder side wall or in a face of the piston, depending upon whether the cylinder is oriented horizontally or vertically. One end of an exhaust tube is positioned adjacent the base of the sump so that gaseous combustion products flow through the sump into the exhaust tube so as to collect and remove the accumulated condensate.

Abstract: Spaced apart single entries are driven into a mineral deposit to be developed by means of a short wall mining machine. A specially designed concrete-receiving slip-form located in the center of the entry is pulled along by a battery of roof supports which are advanced in line behind the mining machine. Quick setting concrete pumped into the anchored slip-form sets up into a wall isolating the two sides of the entry. The slip-form is then released for each successive mining run.