Abstract: An improved alternating current amplifier employs capacitive feedback to balance the intrinsic input capacitance, and a multiplier circuit responsive to a digital control signal coupled in the feedback path to vary the effective capacitance of the capacitive feedback. Thus, the frequency response of the amplifier may be adjusted and set digitally, such as under computer control, obviating the need to make manual adjustments to improve amplifier performance.

Abstract: In order to mitigate the problem of back-corona discharge in electrostatic precipitators, method and apparatus are provided for energizing the precipitator electrodes with repeated bursts of high voltage electrical pulses, superimposed upon a direct current voltage level. Additionally, the voltage of the pulses in a single burst is increased from each pulse to the next pulse during the time period that the pulse burst is applied. The effect of the ramping of the pulse burst voltage is to increase the average electric field and ion density during the pulse burst. The result is substantially higher particle charging which leads to improved particle charging collection efficiency.

Abstract: A protection device for interrupting power to a load connected to a pair of terminals when the temperature of a terminal exceeds a predetermined threshold comprises an alloy having a eutectic at the predetermined threshold and a neon gas-filled glow tube electrically coupled in parallel with the thermal fuse. The thermal fuse is electrically serially connected between the terminal and the load and thermally coupled to the terminal so that an excessive temperature rise at the terminal causes the fuse to melt, thereby removing power from the load and causing the glow tube to be lit.

Abstract: The effluent stream from a process for producing phenolic compounds is reacted with an aldehyde in the presence of a base to form a water soluble resol which is useful in enhanced oil recovery.

Abstract: A generalized real-time thermal model of an induction motor produces values indicative of the transient and steady state temperature condition of the motor. Each of these values is compared with respective predetermined limits and power to the motor is removed when any value exceeds its respective limit in order to prevent damage to the motor.

Abstract: Samples from a first and second cycle of a system signal are used to generate discrete Fourier transforms for the respective first and second cycle. Multiplication of the discrete Fourier transform of the second cycle by the complex conjugate of the discrete Fourier transform of the first cycle produces a frequency deviation phasor whose angle with respect to the real axis is representative of the frequency deviation of the system signal from a predetermined reference frequency. Actual system frequency may be determined by obtaining the inverse tangent of the angle of the frequency deviation phasor with respect to the real axis.Apparatus for determining the frequency and frequency deviation of a system signal is disclosed as is a method and apparatus for determining frequency and frequency deviation of a system signal comprising a plurality of phases.

Abstract: A mobile radio system uses a predetermined number of control channels over which a hand-shake routine is performed to determine called station availability, before one of a limited number of talk channels (local and repeater) is assigned for communication between a calling and the called station. After locating an idle talk channel (local channels are searched first), the control channel to which the called station is predeterminedly assigned is attempted to be accessed. Transmission times on the control channel are a function of the called station's identification code, thus creating a logical ring. Provision is made for message based priorities, emergency numbers and high priority for stations having experienced a previous unsuccessful attempt to access a control channel.

Abstract: An apparatus for predicting the remaining useful life of a motor uses the temperature and past history of the motor to determine the amount of insulation degradation for its prediction. The remaining useful life projection is provided at a display and may be used to trip the circuit breakers supplying power to the motor when projected life is shorter than the expected life or may be used to issue a warning that the rate of motor degradation exceeds the rate necessary to achieve the expected life for the motor.Motor protection is provided by tripping the circuit breakers supplying power to the motor before the actual temperature of the motor windings exceeds the temperature at which catastrophic and irreversible insulation failure would occur while not tripping the breakers for momentary transients.

Abstract: In a bus communication system, a unidirectional transmit bus is coupled to a unidirectional receive bus such that information packets leaving the transmit bus are placed on the receive bus. A plurality of bus interface units (BIUs) are coupled in series at spaced locations to the transmit and receive buses. The BIUs communicate with one another by transmitting information packets on the transmit bus and receiving transmitted information packets from the receive bus. A BIU transmits an information packet when both buses are silent. In the event of a collision between two information packets, downstream BIUs abort transmission and defer to the most upstream BIU having transmitted. Each BIU having had a transmission aborted attempts to gain access to the bus by placing a beep on the transmit bus which informs other BIUs that a BIU requests access to the bus. Only the most upstream BIU requesting access is permitted to transmit a packet.

Abstract: A heat exchanger system exhibits an improved coefficient of heat transfer over a conventional convection heat exchanger while maintaining the beneficial high temperature driving force of conventional convection heat exchanger. A plurality of heat extraction means are provided in heat flow communication with a plurality of shallow beds of particulate matter, which beds are fluidized by a heat-laden gas stream.A method for extracting heat from a heat-laden gas stream is also disclosed.

Abstract: A plurality of bus interface units (BIUs), capable of placing information packets on a unidirectional transmit bus, are coupled to the transmit bus at locations spaced therealong. Each BIU comprises a transmit bus input port and a transmit bus output port, wherein the transmit bus input port of each BIU is coupled to the transmit bus output port of the next upstream BIU, and a receive bus input port connected to a receive bus. Each BIU includes a memory for storing at least one information packet to be transmitted and a control circuit associated with the memory. In a passive mode, the control circuit operates the BIU like a repeater, wherein packets received on its transmit bus input are reconstituted and retransmitted on its transmit bus output. In an active mode, the control circuit causes the BIU to transmit information packets stored in its memory. Each information packet may have a predetermined priority.