Abstract: An NMR device is presented that includes a drill collar having non-rotating sleeve containing permanent magnets. The non-rotating sleeve is clamped against a borehole wall and decoupled from drilling vibrations during NMR measurements. The transmitter and receiver are located on the rotating part of the drill collar. Alternatively the permanent magnets and the RF receiver antenna and/or receiver electronics are placed on the non-rotating sleeve which is clamped against the borehole wall and decoupled from drilling vibrations, with the transmitting antenna located on the rotating drill collar. Alternatively a non-rotating stabilizer is provided above or below an NMR sensor. A stabilizer is activated to stabilize the rotating NMR sensor located on the drilling collar in the bore hole.

Abstract: A NMR device is presented that includes a drill collar having non-rotating sleeve containing permanent magnets. The non-rotating sleeve is clamped against a borehole wall and decoupled from drilling vibrations during NMR measurements. The transmitter and receiver are located on the rotating part of the drill collar. Alternatively the permanent magnets and the RF receiver antenna and/or receiver electronics are placed on the non-rotating sleeve which is clamped against the borehole wall and decoupled from drilling vibrations, with the transmitting antenna located on the rotating drill collar. Alternatively a non-rotating stabilizer is provided above or below a NMR sensor. A stabilizer is activated to stabilize the rotating NMR sensor located on the drilling collar in the bore hole.

Abstract: A method and apparatus for protecting a sensor from impact and abrasion while drilling a borehole including a drill collar having a section of electrically non-conductive material, such as a composite material. The electrically non-conductive material has a rugged structural strength for conveying required drilling operation torque and load. The sensor which, for example, induces an RF field, is located inside the drill collar within the section of electrically non-conductive material wherein the sensor is protected from impact and abrasion while drilling a borehole without interference to the electromagnetic energy. The sensor is located, for example, within a load bearing section of the drill collar. Alternatively, the sensor is located inside a removable probe positioned inside the fluid channel through the drill collar. Stabilizers are used for stabilizing the probe within the channel.

Abstract: A method and apparatus for determining a characteristic of an earth formation surrounding a borehole in which a pulsed nuclear magnetic resonance (NMR) tool is received. A static magnetic field is produced in the borehole using at least two spaced-apart magnets in the NMR tool. The static magnetic field has a first region of substantially uniform magnetic intensity at a first location in the borehole, the first location in the borehole having a first temperature. The NMR tool is moved to a second location in the borehole having a second temperature, and a static magnetic field having a second region of substantially uniform magnetic is produced. The at least two spaced-apart magnets are controllably moved relative to each other wherein the first region of substantially uniform magnetic intensity and the second region of substantially uniform magnetic intensity are substantially equal in size and distance from the NMR tool.

Abstract: A method and apparatus for determining a characteristic of an earth formation surrounding a borehole in which a pulsed nuclear magnetic resonance (NMR) tool is received. A static magnetic field is produced in the borehole using at least two spaced-apart magnets in the NMR tool. The static magnetic field has a first region of substantially uniform magnetic intensity at a first location in the borehole, the first location in the borehole having a first temperature. The NMR tool is moved to a second location in the borehole having a second temperature, and a static magnetic field having a second region of substantially uniform magnetic is produced. The at least two spaced-apart magnets are controllably moved relative to each other wherein the first region of substantially uniform magnetic intensity and the second region of substantially uniform magnetic intensity are substantially equal in size and distance from the NMR tool.

Abstract: An angular displacement sensor for limited angle applications (e.g., for sensing automotive throttle positions) comprising first (14) and second (16) relatively rotatable components arranged to confront each other axially. The first component (14) provides a plurality of poles (14A, B, C) which are angularly disposed about the rotation axis and extend towards the second component. These poles (14A, B, C) have axes which extend in the same direction as the rotation axis. Some poles have windings (14A, B), while others (14B) provide flux return paths. The second component comprises an inductance affecting component (16) which overlies only some of the wound poles at any given time, the relative rotation varying the poles which are overlaid. The sensor includes an output unit (17) for providing output signal data related to the inductances of the excitation poles and thus related to the rotary configuration of the components.

Abstract: An inductive displacement sensor has first and second elements which define a path for movement. The first element has coil portions which interact with an inductance affecting part of the second element so that the inductances of the coil portions vary with movement of the inductance affecting part, only some of the coil portions being affected by the inductance affecting part at any time. The coil portions are arranged in two series connections, each series connection being at least two coil portions electrically connected in series. Coil portions of the two series connections are then arranged alternately. In this way, substantially sinusoidal output signals may be obtained.

Abstract: This invention provides a means for restoring the output waveform of a DC capacitive tip clearance sensor 26 which has been effected by electrical noise in an ion rich environment such as for example a gas turbine engine turbine section 16. The means comprises a pair of electrodes 28,30 each of which is polarized to either a high positive or a high negative potential. The probes 28,30 are situated upstream of the sensor 26 and act to remove any charge carriers from the gas stream before the gas reaches the sensor 26. The sensor 26 may then operate without experiencing undesirable fluctuations in its voltage output.