Abstract: A method and apparatus for measuring relative humidity of a mixture that provides a quick response time for thermal lag while affording protection to fragile sensors. In one aspect, the invention is a method for calculating the relative humidity of a mixture comprising measuring a chamber relative humidity (RHC) within a chamber enclosing an humidity sensor; measuring a first temperature (TC) within the chamber; measuring a second temperature (TA) separate from said chamber, said second temperature being the temperature of the mixture; and calculating the mixture relative humidity (RHA) based on the chamber relative humidity, a first value representing the first temperature and a second value representing the second temperature.

Abstract: A method and apparatus for measuring relative humidity of a mixture that provides a quick response time for thermal lag while affording protection to fragile sensors. In one aspect, the invention is an apparatus comprising: a chamber having a membrane covering an opening in the chamber, the membrane being permeable to water vapor while impermeable to liquid water; a humidity sensor for measuring relative humidity of the mixture within the chamber; a first temperature sensor for measuring a temperature relating to the mixture within the chamber; a second temperature sensor for measuring temperature of the mixture at a point exterior to the chamber; and a processor for receiving signals representing the measurements taken by the humidity sensor, the first temperature sensor, and the second temperature sensor and programmed to calculate relative humidity of the mixture at the point exterior to the chamber as a function thereof.

Abstract: A magnetic sensor for the collection and measurement of ferrous particles through the use of an electronic tuned circuit is disclosed. The sensor contains an electrical inductance coil along with an integral magnet to attract ferrous particles suspended in the fluid. The ferrous particles collecting on the magnetic surface of the sensor causes a change in the inductance of the integral coil which is measured by an electronic circuit. The electronic circuit operating in conjunction with the sensor utilizes a series resonant circuit. A measurement of the voltage across the series resonant circuit is responsive to changes in temperature of the inductance coil. A microprocessor is used to determine the change in period of the resonant oscillation with change in inductance of the coil. The microprocessor uses the data on temperature variation to correct the observed change in oscillator period for the effects of temperature.

Abstract: A method of joining shielding materials used for minimizing passage of electromagnetic and radio frequency energy through the walls of an enclosure, comprising the steps of securing a metallic backing plate to one wall of the enclosure, positioning an end portion of a first sheet of shielding material to the backing plate, then positioning an end portion of second sheet of shielding material atop the end portion of the first sheet of shielding material, and then applying a vibrating tool to the overlapped end portions of the first and second sheets of shielding material to metallurgically bond the facing surfaces of the overlapped shielding materials. A joint structure resulting from practice of the method is also disclosed.

Abstract: A linear capacitance displacement transducer for measuring absolute displacement is formed from a coaxial variable capacitor and a precision capacitance measuring electronic circuit. The plates of the coaxial capacitor are attached to the members of an assembly whose displacement relative to one another is to be determined. Linear displacement of the members causes a linear displacement between the capacitor plates which is reflected in a linear capacitance change. A capacitor controlled oscillator utilizes the coaxial variable capacitor at its input. The capacitor controlled oscillator whose period of oscillation is been determined by the capacitance and locked in phase with changes of capacitance is utilized as a precision measure of capacitance. The period of the square wave output of the oscillator is a linear function of the capacitance of the variable capacitor at any time. The transducer may be adapted to determine the absolute position of a piston rod in a hydraulic cylinder.

Abstract: An optical liquid level sensor utilizing both a prismatic member for the light refraction when immersed in and surrounded by a liquid and its effects for the indication of the presence and absence, selectively, of the liquid level. This level indication is provided in the subject case through a target plate bearing letter codes and legends, respectively, which are recognized and standardized in this trade and which become visible at the onset and for the duration of an acceptable liquid level situation; otherwise; a messageless image appears in the sensor. The illuminated target plate allows also for the observation of the color and any color change of the liquid and the taking of remedial actions.

Abstract: A method and apparatus for locating defects in electrical conduits, hollow ables, or pipes above the ground, using a transmission line wherein one of the lines is the conduit under test. A high-frequency AC generator is used to feed the transmission line and set up a standing wave thereon. The transmission line is terminated in a short circuit at the wall of a shielded room. One conduit carries an internal conductor therein, the conductor and conduit forming another transmission line terminated by its characteristic impedance at both ends.A field intensity meter is connected across the characteristic impedance within the shielded room. The location of the defect is determined by monitoring the magnitude of the induced signal on the conductor inside the conduit containing the defect as the applied frequency is increased from a predetermined low value to the frequency at which the first minimum occurs.

Abstract: An improved intrusion detection apparatus for detecting when a fence is cut r has been climbed over, as well as the location of the intrusion. A cable comprising at least one optical fiber having an electrical transmission line running therealong is strung along the fence to be protected. If an intruder either cuts the cable or stresses the fence so that the cable breaks, an optical signal running along the optical fiber or fibers is lost, thus providing an alarm indication at a central station. The loss of the optical signal automatically triggers an electrical pulse generator means which feeds pulses down the transmission line running along the optical fiber. Part of the pulse energy is reflected at the transmission line break, and the time elapsed between transmission and receipt of the pulses is determined by time domain reflectometry techniques (TDR).