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The present invention relates to a method and apparatus for detecting anomalies, defects or electromagnetic properties of electrically conductive and magnetically permeable materials by using a magnet to partially saturate the material, thereby lowering its permeability, and sending a second, higher

The present invention relates to a method and apparatus for detecting anomalies, defects or electromagnetic properties of electrically conductive and magnetically permeable materials by using a magnet to partially saturate the material, thereby lowering its permeability, and sending a second, higher frequency oscillating electromagnetic wave into the material. The oscillating magnetic flux field permeating into the electrically conductive material induces eddy waves. As the apparatus passes over the material, the properties of the induced eddy currents, and the corresponding magnetic flux field induced by such eddy currents, changes as the properties of the material change. These changes can be the result of defects or anomalies in the material or in connecting welds.

대표청구항 ▼

The present invention relates to a method and apparatus for detecting anomalies, defects or electromagnetic properties of electrically conductive and magnetically permeable materials by using a magnet to partially saturate the material, thereby lowering its permeability, and sending a second, higher

The present invention relates to a method and apparatus for detecting anomalies, defects or electromagnetic properties of electrically conductive and magnetically permeable materials by using a magnet to partially saturate the material, thereby lowering its permeability, and sending a second, higher frequency oscillating electromagnetic wave into the material. The oscillating magnetic flux field permeating into the electrically conductive material induces eddy waves. As the apparatus passes over the material, the properties of the induced eddy currents, and the corresponding magnetic flux field induced by such eddy currents, changes as the properties of the material change. These changes can be the result of defects or anomalies in the material or in connecting welds. ving the first and second electrode patterns deposited thereon, and a proof mass portion at a distal end thereof. 11. The accelerometer recited in claim 10, wherein the electrodes of the first pattern are serially interconnected, and the electrodes of the second pattern are serially interconnected. 12. The accelerometer recited in claim 11, wherein the cantilevered beam further comprises a proof mass portion distal from the suspended end. 13. The accelerometer recited in claim 12, wherein the proof mass portion further comprises one or more of a dimension of length, width, and thickness greater than a respective length, width, and thickness dimension of the portion having the first and second electrode patterns deposited thereon. 14. A monolithic high frequency surface acoustic wave (SAW) accelerometer comprising: a frame formed in a substrate of piezoelectric material; an integral beam suspended by one end from an interior surface of the frame; substantially identical patterns of surface acoustic wave delay lines formed on opposing surfaces of the beam; and a digital processing circuit coupled to each of the patterns of surface acoustic wave delay lines. 15. The accelerometer recited in claim 14, wherein the patterns of surface acoustic wave delay lines are formed at a location on the beam adjacent to the suspended end, and the beam further comprises an integral proof mass portion spaced away from the suspended end. 16. The accelerometer recited in claim 15, wherein the proof mass portion is dimensionally larger than the portion having the patterns of surface acoustic wave delay lines formed thereon. 17. A method for forming an accelerometer, the method comprising: forming a frame of a piezoelectric material; forming a cantilevered beam-shaped sensing member of the piezoelectric material integrally with the frame; depositing substantially identical patterns of surface acoustic wave delay lines on opposing surfaces of the beam; and connecting a circuit to each of the patterns of surface acoustic wave delay lines, the circuit adapted to apply a high frequency drive signal to each of the patterns of surface acoustic wave delay lines. 18. The method recited in claim 17, further comprising connecting a frequency detection circuit to each of the patterns of surface acoustic wave delay lines. 19. The method recited in claim 18, wherein the circuit adapted to apply a high frequency drive signal to each of the patterns of surface acoustic wave delay lines further comprises the frequency detection circuit. 20. The method recited in claim 19, further comprising mass loading the sensing member with an integrally formed proof mass. y a detector means and storing the value in a computing unit; b) drawing a volume of liquid Vactinto a pipette; c) determining the volume of liquid contained in the vessel V1eby a detector means and storing the value in a computing unit; d) calculating the volume of liquid actually drawn off V1actby means of the computing unit in accordance with the equation V1a-V1e=V1act; e) calculating the difference between the volume of liquid actually drawn off V1actand a volume of liquid predetermined to be drawn off V1targby means of the computing unit in accordance with the equation |V1act-V1targ|=V1diff; f) comparing the difference V1diffwith a predetermined volume of liquid ε1by means of the computing unit and displaying an error message in case V1diff>ε1. 2. Method for determining a volume of liquid, which is delivered from a pipette into a vessel, wherein the method comprises the following steps: a') determining a volume of liquid contained in the vessel V2aby a detector means and storing the value in a computing unit; b') delivering a volume of liquid V2actinto the vessel; c') determining the volume of liquid contained in the vessel V2eby a detector means and storing the value in a computing unit; d') calculating the volume of liquid actually delivered V2actby means of the computing unit in accordance with the equation V2e-V2a=V2act; e') calculating the difference between the volume of liquid actually delivered V2actand a volume of liquid predetermined to be delivered V2targby means of the computing unit in accordance with the equation |V2act-V2targ|=V2diff; f') comparing the difference V2diffwith a predetermined volume of liquid ε2by means of the computing unit and displaying an error message in case V2diff>ε2. 3. Method for determining a volume of liquid, which is transferred from a first vessel to a second vessel by means of a pipette, said method comprising the steps of: a) determining a volume of liquid contained in the vessel V1aby a detector means and storing the value in a computing unit; b) drawing a volume of liquid Vactinto a pipette; c) determining the volume of liquid contained in the vessel V1eby a detector means and storing the value in a computing unit; d) calculating the volume of liquid actually drawn off V1actby means of the computing unit in accordance with the equation V1a-V1e=V1act; e) calculating the difference between the volume of liquid actually drawn off V1actand a volume of liquid predetermined to be drawn off V1targby means of the computing unit in accordance with the equation |V1act-V1targ|=V1diff; f) comparing the difference V1diffwith a predetermined volume of liquid ε1by means of the computing unit and displaying an error message in case V1diff>ε1, wherein the pipette is then moved from the first vessel to the second vessel, and, subsequent thereto, the following steps are performed in order to determine volume of liquid delivered from the pipette into the second vessel: a') determining a volume of liquid contained in the vessel V2aby a detector means and storing the value in a computing unit; b') delivering a volume of liquid V2actinto the vessel; c') determining the volume of liquid contained in the vessel V2eby a detector means and storing the value in a computing unit; d') calculating the volume of liquid actually delivered V2actby means of the computing unit in accordance with the equation