Abstract: The present invention relates to a seismic transducer for generating waves in an elastic medium and is particularly applicable to the generation of low frequency shear waves. The transducer is comprised of a mass member having more than one parallel hydraulic cylinder disposed therein, a piston member disposed in each cylinder, each piston member including a piston and a pair of oppositely extending rods, and a frame interconnecting the ends of the piston rods which frame has a base surface thereon for engaging a surface of the elastic medium in energy coupling relationship. A system of hydraulic fluid bleed-back ports associated with the piston members serve to aid lubrication and keep high pressures off of the rod end seals. The present construction permits total enclosure of the mass member and plural piston member assembly.

Abstract: Apparatus for truck-mounting of vibrational seismic energy transducers, particularly shear wave transducers, that provides improved vibrational damping and energy coupling into the earth. The apparatus consists of a four column, hydraulically actuatable suspension system operative from the truck or carrier frame as opposite side pairs to support a box frame under which the vibrator and earth coupling assembly is supported by a system of lateral and vertical springs. The vibrator assembly is entirely supported by means of left and right transverse springs to transmit reactive forces resulting from isolation through the box weldment and four columns to the vehicle body. Thus, the vibrator and its associated base plate structure is entirely supported from the vehicle and positioning assembly by resilient means having the requisite interactive constants.

Abstract: Apparatus for supporting a vibrational shear wave transducer and coupling shear-wave energy into the earth's surface. The apparatus includes separate lateral base plate assemblies having the vibrator assembly operatively disposed therebetween, and the vibrator frame structure includes necessary hydraulic porting structure and supports manifold and servo valve control structure to provide a unitary, improved form of transducer apparatus. Each of the lateral base plate assemblies further includes a removable earth-coupling structure in the form of inverted pyramid or cleat structure having characteristic apex angles in both the lateral and longitudinal dimension so that earth coupling of energy is optimally effected.

Abstract: A method and apparatus for improved detection of reflected seismic energy through detection of air pressure variations in air above an air/earth surface interface. One form of apparatus suitable for detection in air of seismic energy waves emanating from beneath the earth surface consists of supporting a collecting reflecting member over a designated earth surface site and detecting air pressure variations at a focal point within the reflector member; and, thereafter, transmitting or conducting the reflected seismic energy indications for processing in accordance with the seismic energy source requirements to obtain seismic energy reflection data for the particular locale.

Abstract: An air retaining skirt for use with an air cushion vehicle of a type which utilizes a peripheral series of loop and segment sections in combination to provide retention of the air cushion over uneven terrain or water. The loops are adapted to extend from the air cushion vehicle outward and downward in flexible, air inflatable composure, and each loop supports a plurality of ground-contacting segments affixed to the lower edge thereof and extending back up for retention at or near the lower edge of the air cushion vehicle.

Abstract: A hydraulically actuated control valve normally includes a hydraulic cylinder which has an internal piston connected through a shaft to the actuating mechanism in the control valve. Ports are provided on each side of the piston through which fluid flows to move the piston axially inside the cylinder. The piston can be controlled electrically by an electro-hydraulic servo-controlled valve which includes an electrical input, a mechanical feedback input, and first and second outputs. The outputs are connected to the two ports in the cylinder, a mechanical feedback is coupled to the shaft and the mechanical feedback input of the control valve, and an electrical circuit is coupled to the electrical input of the servo-controlled valve to signal the hydraulic portion of the valve to either move the shaft in a manner to close the valve or move the shaft in a manner to open the valve.

Abstract: Apparatus for supplying a large amount of air periodically at a controlled rate to the air cushion beneath an air-cushion vehicle as particularly employed for coupling of controlled frequency seismic energy into the earth. The apparatus consists of a vehicle body which includes a compressed air supply or input to a self-contained plenum chamber space for applying air pressure through a multi-port rotary valve thereafter to be directed into an air cushion formed between the vehicle and the earth surface with periodic exhaust to the atmosphere. The rotary air modulator or valve is comprised of a cylindrical stator, a rotor, and a shutter, each of which includes a plurality of equispaced ports, and air flow from the plenum chamber to the air cushion is modulated by passage through the stator and rotor in accordance with an intermediate shutter position; pressure exhaust is similarly controlled.

Abstract: The present invention relates to an improved hydraulic vibrator of the type which includes a fixed double rod piston and a reaction mass reciprocally disposed around the piston forming a hydraulic cylinder therein so that when hydraulic fluid is introduced to the cylinder relative to the piston the reaction mass is reciprocated. By the present invention a pair of sleeves are slidably disposed on the piston rods, portions of which can be selectively moved into the cylinder to decrease the displacement of the cylinder and thereby increase the frequency range of vibrations producible by the vibrator.

Abstract: A control system for providing precise speed control for a rotary air modulator, and particularly for providing synchronized speed control as between two or more rotary air modulators. A common reference frequency is used for controlling rotational speed of one or more rotary air modulators wherein each modulator deploys an individual feedback system responsive to the reference frequency input to provide precise rotational speed and angular position coordination and, therefore, synchronism of frequency and phase output as between two or more individual modulators. The individual feedback systems include feedback and summation circuitry which derives angular velocity correction, angular position correction and hydraulic pressure drive variation for thereafter correcting and maintaining precise speed control of the rotary drive system.

Abstract: A transport vehicle for movement along the surface of the earth has a forward portion with apparatus mounted for mixing dry coal with fluid to form a slurry. The terminus of a cart-supported slurry hose apparatus is connected to the rear portion. A portion of the cart-supported slurry hose apparatus includes linkages which are attached to the rear portion of the transport vehicle. An improvement in the attaching apparatus includes means for pivotally attaching the terminus of the linkage to the vehicle. An arcuate support is attached to the vehicle over the rear end of the vehicle. A coupling is attached between the arcuate support and the linkage to permit the linkage to pivot freely while supporting the linkage from contact with the surface of the earth.

Abstract: Gas flow from a coal seam to a mine face in the seam is blocked by drilling a hole from the face into the seam in a direction generally parallel to the direction of the flow of the gas to be blocked; forming a notch at the interior end of the hole; injecting a fluid into the hole and notch under a pressure sufficient to hydraulically fracture the seam along a plane extending substantially perpendicular to the hole and to the direction of gas flow; and filling such fracture with a barrier-forming fluid. The hole is then plugged to prevent retrograde flow of the fluid to the mine face.

Abstract: A feeder apparatus for transferring particulate material and water from a sump outlet to the inlet of a pump is formed in the sump by making a well at the outlet of the sump and placing an impeller in the well. A partition is formed separating the inlet to the feeder from its outlet, the partition having a height equal to or exceeding that of the water level in the sump. The outlet from the sump is connected to a channel which has a continually decreasing cross-sectional area, the terminus of which is connected to the inlet of the pump. A fluid jet can be mounted at the inlet of the feeder for reducing the concentration of particulate fluids at the pump inlet or for fluidizing the particles at the entrance of the pump.

Abstract: An improved digital-controlled power amplifier for low frequency, high power applications. The circuit consists of an alternator with stator windings rewound in a binary sequence for generation of primary power, whereupon pulsed semi-conductive controlled rectifiers are digitally controlled to turn on selected binary combinations of the stator output voltages for summation to produce an output voltage of selected amplitude versus duration; and further, the summed voltage output is switched by a polarity switching bridge to enable generation of a bi-polar output to the circuit load.

Abstract: A shear wave vibrator is constructed having a frame with first and second oppositely facing plenum chambers secured to the frame and each having an outer periphery. A skirt is attached to each of the outer peripheries. A fan is attached to the frame with conduits supplying a volume of air under pressure to each of the plenum chambers. A modulation apparatus is mounted in each of the first and second plenum chambers to cause a variation in air pressure in each of the plenum chambers in accordance with a predetermined signal in a manner to cause the air pressure in one chamber to decrease at the same instant the air pressure in the oppositely facing chamber is increasing and vice versa. The entire apparatus is mounted between opposite walls of a trench.

Abstract: A method of induced polarization geophysical surveying which derives meaningful parameters relative to the subsurface strata in both time domain and frequency domain for comparison and/or deductive data compilation and graphic depiction. The system includes a current source as energized by an input wave generator providing an input signal of predetermined frequency content, amplitude relationship and duration; in addition, a plurality of energy receiving detectors are utilized in equi-spaced array such that differential electrical measurement between successive detectors may be gained during each single input energy operation. Such differential electrical measurements are further susceptible of cross correlation relative to the input current signal to provide increased signal-to noise differentiation with respect to usable induced polarization resultant values.

Abstract: In an auger mining system which forms an opening in the earth comprising a pair of axially aligned cylindrical holes and wherein the opening has a bottom, the system has a pair of side-by-side conveyors. Each auger conveyor has a shaft and a flight around the shaft which shafts are journaled through bearings at each end to a spacing member and where the spacing members are rigidly tied to each other by a longitudinal member having an underside. A supporting apparatus including a skid is attached to the auger pair and extending to the bottom of the opening. The skid may be attached either to the underside of the longitudinal member or to each of the bearings. If the skids are attached to the bearings, then skids which are on adjacent bearings of mating auger pairs are arcuately staggered to permit side-by-side positioning of the skids.

Abstract: Apparatus for controlling the lateral position of a marine seismic cable relative to water current which is effective through utilization of one or more cable paravanes having a thrust adjustable hydrofoil and/or stabilizer elements. The hydrofoil is constructed as a pivotally supportable frame having an elastomeric skin which is supported on the sides of the hydrofoil by movable support members, and a servo-controlled reversible motor is controlled to reciprocate the opposite side support members relative to the hydrofoil longitudinal center line. One or more hydrofoils may then be controlled as to angle of attack and camber from the towing ship by means of acoustic energy transmission and reception at the paravane.

Abstract: A pair of side-by-side augers, each having a shaft, a mateable rotational coupling on each end of the shaft, and flights along the shaft, are unitized by journaling bearings on each end of the shaft with spacers pivotally attached between each of the bearings on the same end of the shaft in order to align the axis of the shafts substantially parallel with each other. A longitudinal support member is rigidly secured between the spacers and between each of the flightings. A communications channel is provided in such a unitized auger assembly by mounting a channel along the top of the longitudinal support member. Apparatus is provided for inserting and removing the cable from the channel.

Abstract: An overhead support apparatus for a slurry hose transportation system has a monorail anchored to a support system a predetermined distance above the surface of the earth. A plurality of spaced rollers are movably engaged and supported by the support system. A slurry hose is attached to the plurality of spaced rollers by means of a plurality of beams, each of which has pivotally attached hose supporting clamps spaced along the beam. The apparatus may further include a brake for restraining a beam until the particular section of hose supported by the beam is under tension. A cable is also provided for retracting the plurality of beams to a storage area as required by the use of the slurry transportation system.

Abstract: Apparatus for unitizing a pair of side-by-side augers when each auger includes a shaft, a mateable rotational coupling on each end of the shaft, and flightings along the shaft, the unitizing apparatus includes bearings which are journaled on each end of the shaft and spacers pivotally attached between each of the bearings on the same end of the shaft in order to align the axis of the shafts substantially parallel with each other. A longitudinal support member is rigidly secured beween the spacers and between each of the flightings. A joining clevis is attached to the spacers so that they face in a manner to mate for interconnection with subsequent or preceding unitized assemblies.