Abstract: A high capacity continuous solid bowl centrifuge is disclosed having longitudinal vanes which cooperate with helical flights to form longitudinal channels. The longitudinal vanes may be curved vanes or they may be planar vanes disposed either radially or at an acute angle relative to a radius from the longitudinal axis of the centrifuge. In operation, the solids/liquid mixture fed into the centrifuge is separated, and the liquids move in a "plug-flow" manner in the longitudinal channels parallel to the axis of rotation, toward effluent discharge ports disposed at one end of the centrifuge. The separated heavier solids are moved by the flights toward the opposite end of the centrifuge where they exit through a solids discharge port.

Abstract: An improvement for the drive control system of a vibratory sound source used in seismic exploration comprising apparatus for generating a feedback signal proportional to the instantaneous acceleration of the reaction mass structure of the sound source's hydraulic drive system. Degenerative feedback of the signal so developed is used to reduce distortion of the vibratory seismic signal imparted into the earth.

Abstract: A spring system for use with a geophone for suspending a reference mass axially and laterally. One spring of the spring system flexes more axially than laterally, and the other spring of the spring system flexes more laterally, although heavily damped, than axially.

Abstract: A clamping apparatus for locking tools in a well is disclosed. A first piston sealably engages a hollow body member to form a chamber, which is filled with a working fluid. A bias member or spring moves the first piston, extending a clamping arm connected to the first piston against the well wall. A second piston is sealably engaged in a bore in the first piston; the bore is in fluid communication with the chamber. The second piston is driven into the bore by a motor, increasing the pressure in the chamber through a passage in the first piston between the bore and the chamber. This increased pressure further urges the first piston and locks the clamping arm against the well wall. The hydraulic pressure is released, and the clamping arm is unlocked, by opening a valve in a line between the chamber and a reservoir. The clamping arm is retracted by driving the second piston into the bore into contact with the first piston, forcing the first piston back against the spring.

Abstract: An electronic roll-a-long switch for use in a seismic exploration system and method of seismic exploration are disclosed. For a group of N sequentially numbered receiver points, N/2 input channels are provided. Each input channel receives input from one of two receiver points which are spaced N/2 receiver points apart. The input channels are multiplexed to a data bus in an order corresponding to the sequential numbers of the receiver points comprising the input channels.

Abstract: The claimed invention is directed to seismic exploration wherein an earth surface vibrator sweeps through a frequency range with varies with time as a function of frequency.

Abstract: An improved duty cycle controlled filter, wherein a resistance is included in every circuit path that exists between a switch terminal and an amplifier terminal. Such improved filter produces low distortion and has been found to be especially useful in data acquisition circuits of seismic exploration systems.

Abstract: Solids mixing well structure and methods are disclosed for mixing a solid having a first specific gravity with a fluid having a second specific gravity to produce a slurry having an intermediate specific gravity and a resultant pressure greater than atmospheric pressure. The solids can then be transported in the form of a slurry using the resultant pressure. At no time do the solids come in contact with a pump member. The apparatus and methods are particularly suited for transporting coal and solid waste material. No moving parts are required other than a pump to supply fluid pressure. A first cylindrical member receives at its inlet fluid at a pressure greater than atmospheric pressure and delivers the fluid at a first pre-determined pressure to a mixing region. A second structure receives at its inlet solids at atmospheric pressure and delivers the solids at the first pre-determined pressure to the mixing region down stream of the fluid.

Abstract: A transducer apparatus utilizing fiber optics for data transmission is disclosed in which an output optical signal is encoded with information representative of a parameter being measured and the encoded optical signal transmitted to a remote measurement and control apparatus site for decoding. The transducer is adapted to receive an input optical signal, and converts the input optical signal into electrical energy to power a driver. An electrical drive signal, generated by the driver, has a selectively variable frequency representative of the parameter being measured. Using the electrical drive signal, the output optical signal is generated. The driver includes a variable frequency oscillator whose frequency of oscillation is dependent upon the parameter being measured.

Abstract: A transducer for optical data transmission is disclosed in which an optical signal is encoded with information representative of a parameter being measured and transmitted to a remote measurement and control apparatus site for decoding. An input optical signal is received by the transducer and separated into first and second portions. The first portion of the optical input signal is converted to electrical energy and is used to power the transducer. The second portion of the input optical signal is modulated in response to the measured parameter and the modulated signal transmitted back to the remote site.

Abstract: A geophone spring is disclosed in which an inner ring member and an outer ring member are connected by a plurality of leg members. Each leg member includes a tapered segment that is wider at its middle than it is at either end. The tapered segment is connected to the inner ring by an inner segment, and to the outer ring by an outer segment. The inner and outer segments may also be tapered.

Abstract: An apparatus and method for testing a geophone during assembly is disclosed. The apparatus includes a light source cooperating with a photocell for generating a voltage signal in response to light. A member for support of the geophone to be tested is located in a defined path between the light source and the photocell for generating a voltage signal. The apparatus further includes a display unit for indicating the voltage signal generated, which is representative of the resilient characteristics of the geophone springs, characterizing the position of the geophone coil and its resonant frequency.

Abstract: Method and apparatus for determining the location of a break in a pair of wires of a multi-wire cable are disclosed. The method and apparatus permit such breaks to be found with a high degree of accuracy. The method and apparatus are especially useful in connection with locating breaks in seismic cables.

Abstract: A multistage volumetric feeder has a storage hopper for storing a mass of semi-flowable material, such as strand fiberglass, asbestos, or titanium dioxide. The material is bottom unloaded and passed through several stages of pressure reduction, aeration, and conditioning to loosen the material and place it in a state of substantially constant density. The conditioned material is further prevented from bridging and compacting as it is volumetrically delivered to a metering stage through a segregation stage. Because the semi-flowable material is placed in an uncompacted state of substantially constant density, the feeder is capable of delivering a precise mass of material over a wide range of flow rates.

Abstract: An automatic tractor guidance system for controlling the steering of a tractor to follow a previously plowed furrow is disclosed. A furrow follower is provided with a sensor for sensing the direction of the path relative to the direction of travel of the tractor. The steering direction of the tractor is likewise sensed. The two sensor signals are combined and compared to a convergence frequency signal to produce a digital control signal. Each logic state of the control signal effects a turn in the steering of the tractor, right then left. If the duty cycle of the control signal is 50%, no net turn either right or left is effected. However, when the duty cycle deviates from 50%, a net rotation in one direction or the other will occur depending on which logic state of the digital signal occurs for a longer portion of each cycle of the control signal.

Abstract: A plug and ball injector valve is provided which utilizes seals mounted in standard grooves and an arrangement of pressure balancing cavity areas brought into communication with the seals to balance the fluid pressure across the seals before such seals are exposed to unpressurized ports or passageways. A drain port is arranged in the vicinity of the loading port of the valve to limit spillage and leakage of the line fluid passing through the valve.

Abstract: A seismic cable connector is provided for use with a dual fiber cable in a fiber optic seismic exploration system. The connector contains a digital transceiver which includes an optical detector connected to one fiber of the cable and a fiber optic transmitter connected to the other fiber. The digital transceiver is housed in an environmentally sealed case to protect the transceiver and the ends of the optical fibers from being affected or damaged during use in the field. The transceiver is activated by transistor-transistor logic contained within the connector. The optical fibers are protected by buffer tubes extending the length of the cable. A sixty-one pin electrical plug is provided in the cable connector for mating the connector with remote seismic data gathering units.

Abstract: An improved instantaneous floating point amplifier is provided having a plurality of cascaded amplifier stages, wherein the gain of a given stage of the amplifier is the square of the gain of the immediately succeeding stage of the amplifier. The number of amplifier stages which are required to implement the amplifier is minimized, and the control logic which is required to decide if a given stage is needed to amplify the input signal to a level within preselected limits is simplified. The amplifier has an automatic nulling feature which permits nulling of the amplifier without loss of data.

Abstract: A totally pneumatic crane warning system is disclosed capable of use in oil well environments. The crane warning system utilizes a pneumatic function generator. The pneumatic function generator includes a means for receiving a linear pneumatic signal that may be representative of a boom angle and translating that signal to a non-linear output representative of the maximum load capacity of the crane at that angle. This function is accomplished through the use of a rolling cam machined to represent the functional relationship between the boom angle and the maximum load capacity at that angle. This relationship has been found to be non-linear in nature. A pneumatic control circuit is utilized in conjunction with the rolling cam to effect the pneumatic output signal that is representative of the maximum load capacity at a given boom angle.

Abstract: An apparatus and method for mixing liquid or a drilling mud with solids and a second liquid is disclosed. The apparatus provides an annular housing having a plurality of mixing chambers. An inlet passageway is tangentially connected to the innermost mixing chamber for feeding slurry material to be mixed with solids axially fed into the same mixing chamber. A discharge port is further provided and connected to the outermost mixing chamber for tangentially discharging the homogeneous mixture of slurry and solid materials from the outer mixing chamber at high velocities to an elevation above the inlet. The mixing operation is enhanced by the liquid/solid mixture spilling over a first partition wall and retaining its rotational velocity and direction of rotation while passing under a second partition wall and finally out the discharge port.