Abstract: A real time ultrasonic surface contour mapping system is provided including a digitally controlled phased-array of transmitter/receiver (T/R) elements located in a fixed position above the surface to be mapped. The surface is divided into a predetermined number of pixels which are separately scanned by an arrangement of T/R elements by applying phase delayed signals thereto that produce ultrasonic tone bursts from each T/R that arrive at a point X in phase and at the same time relative to the leading edge of the tone burst pulse so that the acoustic energies from each T/R combine in a reinforcing manner at point X. The signals produced by the reception of the echo signals reflected from point X back to the T/Rs are also delayed appropriately so that they add in phase at the input of a signal combiner. This combined signal is then processed to determine the range to the point X using density-corrected sound velocity values.

Abstract: A three-axis velocity probe system for determining three-axis positional velocities of small particles in fluidized bed systems and similar applications. This system has a sensor head containing four closely-spaced sensing electrodes of small wires that have flat ends to establish a two axis plane, e.g. a X-Y plane. Two of the sensing electrodes are positioned along one of the axes and the other two are along the second axis. These four sensing electrodes are surrounded by a guard electrode, and the outer surface is a ground electrode and support member for the sensing head. The electrodes are excited by, for example, sinusoidal voltage having a peak-to-peak voltage of up to 500 volts at a frequency of 2 MHz. Capacitive currents flowing between the four sensing electrodes and the ground electrode are influenced by the presence and position of a particle passing the sensing head.

Abstract: A sensing system is provided for determining the bed temperature profile of the bed of a stirred, fixed-bed gasifier including a plurality of temperature sensors for sensing the bed temperature at different levels, a transmitter for transmitting data based on the outputs of the sensors to a remote operator's station, and a battery-based power supply. The system includes an isolation amplifier system comprising a plurality of isolation amplifier circuits for amplifying the outputs of the individual sensors.

Abstract: Three-axis particle impact probes detect particle impact vectors along x-, y-, and z-axes by spherical probe head mounted on the outer end of a shaft that is flexibly mounted in silicone rubber at the top of a housing so as to enable motion imparted to the head upon impact to be transmitted to a grounded electrode secured to the shaft within the housing. Excitable electrodes are mounted in the housing in a fixed position, spaced apart from the ground electrode and forming, with the ground electrode, capacitor pairs. Movement of the ground electrode results in changes in capacitance, and these difference in capacitance are used for measurement or derivation of momentum vectors along each of the three axes. In one embodiment, the ground electrode is mounted at the base of the shaft and is secured to a silicone rubber layer at the top of the housing, providing for cantilevered movement.

Abstract: A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved.

Abstract: A multiple channel data transmission system is provided in which signals from a plurality of pulse operated transducers and a corresponding plurality of pulse operated signal processor channels are multiplexed for single channel FM transmission to a receiving station. The transducers and corresponding channel amplifiers are powered by pulsing the dc battery power to these devices to conserve energy and battery size for long-term data transmission from remote or inaccessible locations. Auto zeroing of the signal channel amplifiers to compensate for drift associated with temperature changes, battery decay, component aging, etc., in each channel is accomplished by means of a unique auto zero feature which between signal pulses holds a zero correction voltage on an integrating capacitor coupled to the corresponding channel amplifier output. Pseudo-continuous outputs for each channel are achieved by pulsed sample-and-hold circuits which are updated at the pulsed operation rate.

Abstract: A microbending optical fiber is attached under tension to a diaphragm to se a differential pressure applied across the diaphragm which it causes it to deflect. The fiber is attached to the diaphragm so that one portion of the fiber, attached to a central portion of the diaphragm, undergoes a change in tension; proportional to the differential pressure applied to the diaphragm while a second portion attached at the periphery of the diaphragm remains at a reference tension. Both portions of the fiber are caused to vibrate at their natural frequencies. Light transmitted through the fiber is attenuated by both portions of the tensioned sections of the fiber by an amount which increases with the curvature of fiber bending so that the light signal is modulated by both portions of the fiber at separate frequencies. The modulated light signal is transduced into a electrical signal.

Abstract: An acoustic system is provided for measuring the fluid level in oil, gas or water wells under pressure conditions that does not require an electrical link to the surface for level detection. A battery powered sound transmitter is integrated with a liquid sensor in the form of a conductivity probe, enclosed in a sealed housing which is lowered into a well by means of a wire line reel assembly. The sound transmitter generates an intense identifiable acoustic emission when the sensor contacts liquid in the well. The acoustic emissions propagate up the well which functions as a waveguide and are detected by an acoustic transducer. The output signal from the transducer is filtered to provide noise rejection outside of the acoustic signal spectrum. The filtered signal is used to indicate to an operator the liquid level in the well has been reached and the depth is read from a footage counter coupled with the wire line reel assembly at the instant the sound signal is received.

Abstract: An ash level meter for a fixed-bed coal gasifier is provided which utilizes the known ash level temperature profile to monitor the ash bed level. A bed stirrer which travels up and down through the extent of the bed ash level is modified by installing thermocouples to measure the bed temperature as the stirrer travels through the stirring cycle. The temperature measurement signals are transmitted to an electronic signal process system by an FM/FM telemetry system. The processing system uses the temperature signals together with an analog stirrer position signal, taken from a position transducer disposed to measure the stirrer position to compute the vertical location of the ash zone upper boundary.

Abstract: A modulated control system is provided for improving regulation of the bed level in a fixed-bed coal gasifier into which coal is fed from a rotary coal feeder. A nuclear bed level gauge using a cobalt source and an ion chamber detector is used to detect the coal bed level in the gasifier. The detector signal is compared to a bed level set point signal in a primary controller which operates in proportional/integral modes to produce an error signal. The error signal is modulated by the injection of a triangular wave signal of a frequency of about 0.0004 Hz and an amplitude of about 80% of the primary deadband. The modulated error signal is fed to a triple-deadband secondary controller which jogs the coal feeder speed up or down by on/off control of a feeder speed change driver such that the gasifier bed level is driven toward the set point while preventing excessive cycling (oscillation) common in on/off mode automatic controllers of this type.

Abstract: An improved air-flow regulator for a fixed-bed coal gasifier is provided which allows close air-flow regulation from a compressor source even though the pressure variations are too rapid for a single primary control loop to respond. The improved system includes a primary controller to control a valve in the main (large) air supply line to regulate large slow changes in flow. A secondary controller is used to control a smaller, faster acting valve in a secondary (small) air supply line parallel to the main line valve to regulate rapid cyclic deviations in air flow. A low-pass filter with a time constant of from 20 to 50 seconds couples the output of the secondary controller to the input of the primary controller so that the primary controller only responds to slow changes in the air-flow rate, the faster, cyclic deviations in flow rate sensed and corrected by the secondary controller loop do not reach the primary controller due to the high frequency rejection provided by the filter.

Abstract: An ash level control system is provided which incorporates an ash level meter to automatically control the ash bed level of a coal gasifier at a selected level. The ash level signal from the ash level meter is updated during each cycle that a bed stirrer travels up and down through the extent of the ash bed level. The ash level signal is derived from temperature measurements made by thermocouples carried by the stirrer as it passes through the ash bed and into the fire zone immediately above the ash bed. The level signal is compared with selected threshold level signal to determine if the ash level is above or below the selected level once each stirrer cycle. A first counter is either incremented or decremented accordingly. The registered count of the first counter is preset in a down counter once each cycle and the preset count is counted down at a selected clock rate.

Abstract: A single transmission line interrogated multiple channel data acquisition system is provided in which a plurality of remote station/sensors monitor specific process variables and transmit measurement values over the single transmission line to a master station when addressed by the master station. Power for all remote stations (up to 980) is provided by driving the line with constant voltage supplied from the master station and automatically maintained independent of the number of remote stations directly connected to the line. The transmission line can be an RG-62 coaxial cable with lengths up to about 10,000 feet with branches up to 500 feet. The remote stations can be attached randomly along the line. The remote stations can be scanned at rates up to 980 channels/second.

Abstract: A multiple segment three-terminal type capacitance probe with segment selection, capacitance detection and compensation circuitry and read-out control for level/density measurements in a fluidized-bed vessel is provided. The probe is driven at a high excitation frequency of up to 50 kHz to sense quadrature (capacitive) current related to probe/vessel capacitance while being relatively insensitive to the resistance current component. Compensation circuitry is provided for generating a negative current of equal magnitude to cancel out only the resistive component current. Clock-operated control circuitry separately selects the probe segments in a predetermined order for detecting and storing this capacitance measurement. The selected segment acts as a guarded electrode and is connected to the read-out circuitry while all unselected segments are connected to the probe body, which together form the probe guard electrode.

Abstract: A signal processor is provided which uses an analog integrating circuit in conjunction with a set of digital counters controlled by a precision clock for sampling timing to provide an improved presentation of an ultrasonic transmitter/receiver signal. The signal is sampled relative to the transmitter trigger signal timing at precise times, the selected number of samples are integrated and the integrated samples are transferred and held for recording on a strip chart recorder or converted to digital form for storage. By integrating multiple samples taken at precisely the same time with respect to the trigger for the ultrasonic transmitter, random noise, which is contained in the ultrasonic receiver signal, is reduced relative to the desired useful signal.

Abstract: A single transmission line interrogated multiple channel data acquisition system is provided in which a plurality of remote station/sensor circuits each monitors a specific process variable and each transmits measurement values over a single transmission line to a master interrogating station when addressed by said master interrogating station. Typically, as many as 330 remote stations may be parallel connected to the transmission line which may exceed 7,000 feet. The interrogation rate is typically 330 stations/second. The master interrogating station samples each station according to a shared, charging transmit-receive cycle. All remote station address signals, all data signals from the remote stations/sensors and all power for all of the remote station/sensors are transmitted via a single continuous terminated coaxial cable. A means is provided for periodically and remotely calibrating all remote sensors for zero and span.

Abstract: The present invention is directed to a method for remotely mapping subterranean coal beds prior to and during in situ gasification operations. This method is achieved by emplacing highly directional electromagnetic wave transmitters and receivers in bore holes penetrating the coal beds and then mapping the anomalies surrounding each bore hole by selectively rotating and vertically displacing the directional transmitter in a transmitting mode within the bore hole, and thereafter, initiating the gasification of the coal at bore holes separate from those containing the transmitters and receivers and then utilizing the latter for monitoring the burn front as it progresses toward the transmitters and receivers.

Abstract: An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors.

Abstract: A multiple channel coincidence detector circuit is provided for analyzing data either in real time or recorded data on a magnetic tape during an experiment for determining location and progression of fractures in an oil field or the like while water is being injected at high pressure in wells located in the field. The circuit is based upon the utilization of a set of parity generator trees combined with monostable multivibrators to detect the occurrence of two events at any pair of channel input terminals that are within a preselected time frame and have an amplitude above a preselected magnitude. The parity generators perform an exclusive OR function in a timing circuit composed of monostable multivibrators that serve to yield an output when two events are present in the preselected time frame. Any coincidences falling outside this time frame are considered either noise or not otherwise useful in the analysis of the recorded data.

Abstract: A device is provided for automatic control and detection in a three-terminal resistance measuring instrument. The invention is useful for the rapid measurement of the resistivity of various bulk material with a three-terminal electrode system. The device maintains the current through the sample at a fixed level while measuring the voltage across the sample to detect the sample resistance. The three-electrode system contacts the bulk material and the current through the sample is held constant by means of a control circuit connected to a first of the three electrodes and works in conjunction with a feedback controlled amplifier to null the voltage between the first electrode and a second electrode connected to the controlled amplifier output. An A.C. oscillator provides a source of sinusoidal reference voltage of the frequency at which the measurement is to be executed.