Abstract: The present disclosure provides maize plants exhibiting broad spectrum resistance to Northern Leaf Blight (NLB). Maize plants with multiple NLB resistance loci located in cis linkage on chromosome 8 are provided. Compositions, including novel polymorphic markers and methods for producing, breeding, identifying, and selecting plants or germplasm with a disease resistance phenotype are further provided.

Abstract: A process control device is disclosed. The process control device comprises a measuring circuit (102) and a power regulator circuit (100). The measuring circuit (102) is coupled to the power regulator (100), and produces a control signal indicative of a measured value. The power regulator circuit (100) redirects a portion of the available power from the power regulator circuit (100) in proportion to the control signal produced by the measuring circuit (102) such that it does not limit available power to the measuring circuit (102). The process control device also may comprise a power control circuit (101) coupled to the measuring circuit (102). The power control circuit (101) redirects an amount of available power from the power regulator circuit (100) in proportion to the control signal. The process control device also comprisies two or more conductors (106, 107) that are in electrical communication with the power regulator circuit (100) and the power control circuit (101).

Abstract: A measuring system for measuring a variable physical parameter by varying a reference signal above and below the magnitude of the physical parameter. The difference between the varying reference and the varying physical parameter is used to create an output signal representative of the magnitude of the parameter. A preferred embodiment of the invention uses a feedback-controlled system to vary the reference in such manner as to cause the time integral of the difference to be minimized. The reference is varied at a controlled rate, and the direction in which the reference is being varied is reversed when a function of the difference reaches some predetermined level. A function of the limits between which the reference has recently been varied is representative of the magnitude of the physical parameter.

Abstract: A sludge blanket level is determined in a waste water treatment clarifier using sonic pulse reflections. Additionally, using similar techniques, the clarity of the waste water is determined. A sonic pulse is directed into the waste water. Echos are generated as the pulse encounters the impedance mismatches indicative of changes in the density of the water. The echos are compensated for attenuation as a function of travel time through the water, energy lost due to prior peak reflections, and are processed to remove random signals using correlation techniques. A sludge blanket is selected from the compensated echo signal as a function of the size and location of echo peaks. Additionally, the clarity is determined as a function of the area under the echo signal between two points corresponding to predefined levels in the clarifier tank.

Abstract: A sludge blanket level is determined in a waste water treatment clarifier using sonic pulse reflections. Additionally, using similar techniques, the clarity of the waste water is determined. A sonic pulse is directed into the waste water. Echos are generated as the pulse encounters the impedance mismatches indicative of changes in the density of the water. The echos are compensated for attenuation as a function of travel time through the water, energy lost due to prior peak reflections, and are processed to remove random signals using correlation techniques. A sludge blanket is selected from the compensated echo signal as a function of the size and location of echo peaks. Additionally, the clarity is determined as a flnction of the area under the echo signal between two points corresponding to predefined levels in the clarifier tank.

Abstract: An ultrasonic measurement method in an ultrasonic measurement system having an ultrasonic transducer includes emitting an ultrasonic pulse from the ultrasonic transducer. An ultrasonic pulse is received in accordance with a pulse travel time wherein the amplitude of the received ultrasonic pulse varies according to the pulse travel time. A first electrical signal is provided representative of the received ultrasonic pulse wherein the amplitude of the first electrical signal varies in accordance with the pulse travel time. A second electrical signal is provided in accordance with the first electrical signal wherein the amplitude of the second electrical signal is substantially independent of the pulse travel time. In order to determine the second electrical signal variable amplification is applied to the first electrical signal in accordance with the travel time.

Abstract: An ultrasonic measurement method in an ultrasonic measurement system having an ultrasonic transducer includes emitting an ultrasonic pulse from the ultrasonic transducer. An ultrasonic pulse is received in accordance with a pulse travel time wherein the amplitude of the received ultrasonic pulse varies according to the pulse travel time. A first electrical signal is provided representative of the received ultrasonic pulse wherein the amplitude of the first electrical signal varies in accordance with the pulse travel time. A second electrical signal is provided in accordance with the first electrical signal wherein the amplitude of the second electrical signal is substantially independent of the pulse travel time. In order to determine the second electrical signal variable amplification is applied to the first electrical signal in accordance with the travel time.

Abstract: A multiple set point material condition monitoring system is responsive both to the level of material with respect to a sensor and the extent of material coating which has accumulated on the sensor. The system provides an output when a predetermined coating thickness has been exceeded, so that the sensor may be cleaned before the coating can accumulate to the extent where a false level output is generated. The systems include three electrode guarded sensors, a bridge comparing the sensor output with a reference, and a bridge reference which is automatically and repeatedly caused to assume a sequence of values corresponding to material condition set points, one of which causes an output when a predetermined coating thickness has occurred and another of which generates a level output. In one embodiment, separate outputs are provided corresponding to each set point. In another embodiment, a single tri-state output is responsive to both set points.

Abstract: An instrument system provides compensation for signal processing errors by processing both sensor signals and reference signals in a common signal processor. Reference signals may be provided which enable zero compensation, gain compensation, or both. The system outputs compensated signals to a two wire signal loop in either analog or digital form, and selects the form of output signal in accordance with digital input signals received from the signal wires. The system may be embodied as a radio frequency admittance instrument system for monitoring the condition of materials.

Abstract: A probe developing an admittance with a material whose condition is to be continuously measured is capacitively coupled with a variable frequency oscillator, preferably one having a digital output stage, for generating a variable frequency signal having a period varying with the admittance developed at the probe. Both the oscillator input and output are capacitively coupled to the probe. In a preferred embodiment, a set point circuit including a plurality of resistors coupled in parallel with the oscillator output and a plurality of switches coupled in parallel with the probe conductor and each with a different one of the resistor, provides easy circuit adjustment for use of the system with a variety of materials. A preferred digital circuit employing a pair of flip flops, fixed timer and one shot generate a fixed period variable duration duty cycle digital voltage level signal for transmission, if desired, or for conversion into a variable current signal.

Abstract: A probe developing an admittance with a material whose condition is to be continuously measured is capacitively coupled with a variable frequency oscillator, preferably one having a digital output stage, for generating a variable frequency signal having a period varying with the admittance developed at the probe. Both the oscillator input and output are capacitively coupled to the probe. In a preferred embodiment, a set point circuit including a plurality of resistors coupled in parallel with the oscillator output and a plurality of switches coupled in parallel with the probe conductor and each with a different one of the resistor, provides easy circuit adjustment for use of the system with a variety of materials. A preferred digital circuit employing a pair of flip flops, fixed timer and one shot generate a fixed period variable duration duty cycle digital voltage level signal for transmission, if desired, or for conversion into a variable current signal.

Abstract: A multiple set point material condition monitoring system includes a material responsive sensor developing a material condition dependent admittance and a reference admittance generator, generating a plurality of different admittance values in a predetermined sequence repeatedly during operation of the system. The circuitry coupled with the sensor and the reference admittance generator outputs a signal which is a function both of the material condition generated admittance and each of the plurality of reference admittance values, in sequence. Storage means are provided for storing a characteristic of the output signal for feedback to the circuitry when that particular reference admittance value for generating that output signal is again generated by the reference admittance generator. Preferably, the sensor and reference admittance generator are coupled across each of a pair of arms of bridge network which constitutes part of the circuitry developing the output signal.

Abstract: A probe developing an admittance with a material whose condition is to be continuously measured is capacitively coupled with a variable frequency oscillator, preferably one having a digital output stage, for generating a variable frequency signal having a period varying with the admittance developed at the probe. Both the oscillator input and output are capacitively coupled to the probe. In a preferred embodiment, a set point circuit including a plurality of resistors coupled in parallel with the oscillator output and a plurality of switches coupled in parallel with the probe conductor and each with a different one of the resistor, provides easy circuit adjustment for use of the system with a variety of materials. A preferred digital circuit employing a pair of flip flops, fixed timer and one shot generate a fixed period variable duration duty cycle digital voltage level signal for transmission, if desired, or for conversion into a variable current signal.

Abstract: In an instrument system consisting of a transmitter in one location and a receiver in another location connected by a transmission medium, fail-safe operation is obtained by restricting the output of the transmitter to well-defined levels and interpreting any substantial departure of the received signal from these well-defined levels as a failure. When a failure is detected, alarms or other equipment may be activated, including a control circuit which causes replacement of the defective transmitter or transmission medium, thereby restoring the system to service. An embodiment wherein the transmitter is an admittance-responsive transmitter in a two-wire current loop for monitoring the condition of materials is described.

Abstract: A hollow probe which is adapted to respond to the degree to which a pipe is filled with fluid includes the use of a tubular conductive probe measuring electrode and a pair of tubular conductive guard electrodes axially displaced from the probe electrode. The tubular electrodes are hollow and are adapted to form a fluid conducting portion of the fluid-carrying pipe. The probe electrode and guard electrodes are separated by solid insulation. The guard electrodes are separated from sections of the pipe on either side of the hollow probe by solid insulation. The guard electrodes are exposed to the contents of the pipe and, by driving the guard electrodes at substantially the same potential as the probe electrode, the adverse effects of a coating of fluid adhering to the probe are substantially eliminated.

Abstract: In an instrument system consisting of a transmitter in one location and a receiver in another location connected by a transmission medium, fail-safe operation is obtained by restricting the output of the transmitter to well-defined levels and interpreting any substantial departure of the received signal from these well-defined levels as a failure. When a failure is detected, alarms or other equipment may be activated, including a control circuit which causes replacement of the defective transmitter or transmission medium, thereby restoring the system to service. An embodiment wherein the transmitter is an admittance-responsive transmitter in a two-wire current loop for monitoring the condition of materials is described.

Abstract: A single, elongated admittance sensing probe element comprises an elongated probe structure including a conductive level measuring probe electrode and a conductive composition probe electrode longitudinally spaced from the level measuring probe electrode closer to one end of the probe. A conductive shield extends between the level measuring and composition probe elements and beyond the composition probe element at the end of the probe. The entire structure is enclosed within an insulating material. In one embodiment, a cylindrical ground electrode or shield is mounted around the probe structure.

Abstract: A two-wire transmitter includes an admittance sensing probe adapted to sense the conditions and corresponding admittance of materials. The probe is coupled into an admittance responsive network which generates an admittance signal representing the condition of materials. The output current from the transmitter is varied in response to the admittance signal. In one embodiment of the invention, the admittance responsive network comprises a variable frequency oscillator whose frequency varies with the admittance of the materials. In another embodiment, the admittance responsive network comprises a ramp generator with a frequency which varies with the admittance of the materials. In another embodiment, the admittance responsive network comprises a bridge whose balance changes in response to the admittance of the materials.

Abstract: An intrinsically safe system for monitoring the condition of materials includes a low power, stable frequency RF oscillator of the class C type comprising a resonant circuit which is coupled to a bridge network including the admittance of materials between a probe electrode and a grounded support member juxtaposed to the materials. The output of the network generates an AC error signal which is applied to a phase sensitive detector including a chopper and a low power chopper drive for generating a DC signal representing the magnitude of the AC signal at a predetermined phase angle. The bridge network which may be linearly calibrated is isolated from the oscillator and the output error signal circuitry so as to allow the oscillator and the output error signal circuitry to float with respect to the grounded support member and the power supply associated therewith.