Abstract: An x-ray generator including a light source; a high temperature photocathode arranged so as to be illuminated by light from the light source; an accelerator for accelerating electrons emitted by the photocathode; and a target onto which accelerated electrons impinge so as to produce x-rays, the target being held at substantially ground potential. The accelerator is arranged so that the photocathode is at a low voltage end of a voltage multiplier, typically held at about -100 kV, and the target is at the high voltage end at ground potential. The voltage multiplier can include a bank of nested tubular capacitor members which surround the photocathode and accelerator section and are arranged such that the outer surface is at ground potential, the same as the target.

Abstract: An NMR pulse sequence technique for use in the borehole environment is provided which uses CPMG pulses according to?W.sub.i -90-(t.sub.cp -180-t.sub.cp -echo).sub.j !.sub.iwhere j is the index of the CPMG echoes gathered, i is the index of the wait times in the pulse sequence, W.sub.i are the varying wait times before the CPMG pulses, and tcp is the Carr-Purcell spacing. Measurements are made of the signals induced in the formation as a result of the magnetic fields to find the spin-echo relaxation time T1. Using T1, the gas effect on formation parameters may be derived. Also, gas saturation and gas chemical composition can be derived. In addition, the diffusion coefficient of gas under reservoir conditions can be more than ten times larger than that of water, making the T.sub.2 relaxation time of gas more sensitive to static magnetic field gradients. In formations where gas occupies pores larger than about 10 .mu.m, this T.sub.2 effect (effect of diffusion on the measured T.sub.

Abstract: A portion of a borehole wall is isolated from surrounding borehole fluids by placing a chamber of a borehole tool against the borehole wall. The chamber comprises a cylindrical recess in an exterior surface of the borehole tool. The recess is open at one end to receive borehole fluids, and closed at the opposite end by a concave ultrasonic acoustic transducer. Mudcake present within the chamber and on the isolated portion of the borehole wall is disintegrated by the concave ultrasonic transducer. This approach can be used to remove mudcake from a borehole wall with a moving or stationary borehole tool.

Abstract: Images of rock formations below the earth's surface can be obtained on a microscopic scale. A borehole tool uses a seal to isolate an interval of the formation from borehole fluids which are outside the seal. A probe of the tool engages a wall of the formation and then draws formation fluid from the formation into the interior of the tool. The tool then produces an optical image of the formation which indicates rock texture. The seal can comprise a pad, inflatable packers, compressional packers, or cement plugs. The images of the formation can be obtained with electro-optic imagers such as charge-coupled devices (CCD) or a camera operating in the visible and/or near infrared range, or with ultrasonic transducers operating in the sub-MHz to mid GHz range, for example. The near infrared range provides an optical image of the formation through opaque fluids such as oil based muds or oil itself.

Abstract: A method for producing, in a hydrocarbon well, a signal indicative of a local flow parameter of a multiphase fluid, includes the steps of placing at least one local sensor in the fluid and producing a signal whose level is characteristic of the phase in which the sensor is immersed, the signal being generated at a spike whose radius of curvature is less than 100 microns. The method is applicable to determining hold-ups of different phases of the fluid.

Abstract: Methods and apparatus for generating an error bar (variance) log for a formation parameter are disclosed. According to the method, acoustic waveforms are detected at a plurality (M) of detectors which are a function of a source signal which has interacted with the formation and noise, and the detected waveforms are sampled and processed in order to obtain a semblance or a normalized mean square error. Using the semblance or the NMSE which is related to the semblance, a signal to noise ratio 2E/N.sub.0 can be found by recognizing that the semblance function has a non-central beta distribution whose mean is a function of the signal to noise ratio 2E/N.sub.0, the time-bandwidth product N, and M. The signal to noise ratio is then used to find the Cramer-Rao lower bound which is taken as an estimate of the variance. An error bar log is formed by repeating these steps at a plurality of locations along the borehole.

Abstract: A permanent magnet of a pulsed nuclear magnetic resonance (NMR) device is positioned within a drill collar for evaluating earth formations. In this way, the torsional and bending strengths of the drill collar are maximized with relatively little sacrifice of the magnetic moment of the permanent magnet. The resulting tool makes NMR measurements while the formation is being drilled. An antenna for producing and detecting an oscillating RF field in the earth formation is either located in a groove in the outer surface of the drill collar, or in an alternative embodiment, the drill collar itself serves as an RF antenna.

Abstract: Methods for processing sonic logging data obtained by a sonic imaging tool or an MWD tool are provided. The sonic logging data are bandpass filtered and sampled according to techniques such as integer band decimation, quadrature modulation, and single side band modulation to provide compressed signals which can be reconstructed if desired. The compressed signals are alternatively stored for downloading and further processing, sent uphole for processing, or processed downhole. The processing preferably involves processing the analytic portion of the compressed signals according to an improved semblance processing technique where the semblance function is calculated over a time window utilizing coarse slowness and time sampling steps. The slowness and time sampling steps are dictated by the parameters of the bandpass filter and the inter-receiver spacing of the tool. The waveform for each receiver is preferably interpolated based on the time step size to provide those data points necessary for stacking.

Abstract: A device for measuring flow rate of multiphase fluids such as oilwell effluents, containing liquid hydrocarbons, gas, and water includes first and second sections situated at a distance one from the other in the flow direction, each including a passage provided with structure such as venturis for inducing a change of speed therein, and respective means for measuring the resulting pressure differences, the pressure difference signals obtained in the respective sections being suitable for cross-correlation to produce a signal representative of the total volume flow rate.

Abstract: Methods for determining an optimal frequency band for processing of flexural waves according to bias-corrected STC or QSTC are disclosed. A preliminary estimate of the formation shear slowness S and a determination of the borehole diameter D are first obtained, and the flexural waves are processed in a frequency band having a center frequency f.sub.c which is a function of preliminary estimate of S and the product of that estimate of S and diameter D. Where the preliminary estimate of S indicates a slow formation, f.sub.c is chosen as 0.6/SD. Where the estimate indicates a fast formation, f.sub.c is chosen as 0.2/SD. In other or all formations, a smooth function such as [0.2+((0.8/.pi.) arctan ((S-100)/100))/SD] can be used to choose the center frequency. Alternatively, if errors in the environmental parameters can be estimated statistically, they can be used to select an optimum center frequency. Once f.sub.

Abstract: A method of determining alignment of first and second parts of a borehole tool system in which three mutually orthogonal signals are transmitted by a transmitter in the first tool part and each signal is received and measured in three mutually orthogonal directions at a receiver in the second tool part, the components of each signal in the three mutually orthogonal directions at the receiver being used to determine the alignment of the first and second parts. The method has applications in deep electromagnetic or acoustic measurements, either from a single well or in a cross-well system.

Abstract: An adapter for a meter chamber provides proportional metering of a flow through a maincase that is sufficiently accurate at large flow rates to avoid the unmetered loss of significant quantities of water. An essentially unobstructed passageway is provided under the meter chamber to provide a free flow of water through a path that can be made large enough to avoid flow blockage by debris, even if the path through the meter becomes blocked. Thus, the adapter is particularly useful for installation in residential fire service mains. The adapter includes a chamber housing into which the meter chamber may be inserted, a bypass plate to hold the meter chamber in place, and a bypass to provide the passageway through which the free flow of water flows. The chamber housing includes inlet and outlet apertures, as does the bypass.

Abstract: A method and system is disclosed for indication and prevention of tampering with an electricity meter having control circuitry for automatic remote reading. The control circuitry, provided externally of the meter in a base or base extension, to which the meter is connected, is also used for tamper detection. Embodiments of the invention include use of optical sensing, voltage detection and proximity detection. Ambient light sensing may be performed to detect separation of the meter from the external receptacle. Reflected light to a reflective surface of the meter is sensed to determine if the meter is properly engaged. Presence of a meter connection plug element may be sensed either optically or by position responsive switch. Voltage of the utility supply and meter user output may be monitored to determine tampering.

Abstract: An air-coupled current transformer is provided with a primary current conductor and two secondary coils connected such that the emf induced in each coil by an external disturbing magnetic flux is subtractive, whereas the emf induced by the current in the primary is additive. Two ferromagnetic core pieces enhance the rejection of the emf induced by the disturbing flux. Ceramic spacers are inserted into air gaps between the core pieces for maintaining the gaps fixed to keep the scale factor of the transformer independent of temperature.

Abstract: A method and apparatus for producing a temperature stabilized frequency from a signal generator in a monitoring station is described. The signal generator monitors the voltage response of an RC circuit where the resistive portion is formed by a thermistor, to produce a time-dependent signal. A comparator compares the time-dependent signal to a reference voltage to determine a rise time of the voltage across the capacitor. Based upon a software timer loop, the signal generator determines a temperature range by selecting data from a look-up table based upon the rise time of the RC circuit.

Abstract: A dry (unpressurized) hydrant utilizes a hydrant pipe wherein a submerged end carrying a strainer assembly is placed at a predetermined depth within a body of water, such as a lake or a pond, with the unsubmerged end being located above ground adjacent the water surface. A check valve installed behind the underwater strainer allows the pipe to be filled with water delivered from a tank onboard a pumper truck. Flooding the pipe in this manner allows the pumper truck to then pump water from the lake or pond, through the hydrant, with little or no priming necessary so as to meet fire suppression demands. A vent valve located on the pumper intake connected to the unsubmerged end allows air to escape from the pipe during the filling process.

Abstract: The invention provides a method consisting successively in producing two electromagnetic radiations of the same wavelength that is modulated as a function of time over a range of wavelengths, a "measurement" one of said radiations passing through a gas that presents selective absorption for said radiation in the range, while the other radiation constitutes a "reference" radiation. Each of said radiations is transformed into a respective "measurement" or "reference" electrical signal. The measurement signal is divided by the reference signal to obtain a first quotient electrical signal which is in turn split into two portions: a time-varying AC portion and a DC portion that does not vary with time. The AC portion is divided by said DC portion in order to obtain a second quotient electrical signal representative solely of the electromagnetic radiation absorbed by the gas.

Abstract: An electro-mechanical induction watt-hour meter has a rotatable disc and a projection on the base directed into the meter terminating in proximity of the rotatable disc. The projection is part of a pulse initiator system where a pulse signal is transmitted through a selected area of the base that is transparent to the signal. A signal is generated externally of the meter and chopped by rotation of the disc providing a pulse signal that passes through the base of the meter to a receptor external to the meter. The signal generator and the pulse signal receptor are both located in the enclosure defined by the base of the meter and the receptacle socket for the meter. The generated signal is disclosed as a light beam that, by way of light guides on the meter base, is directed to one side of the rotating disc and is directed by one light guide and to the other side of the disc where another light guide returns the chopped or pulsed signal to the receptor.

Abstract: Generation, validation and fault-grading of test patterns, and test and debug of logic circuits, are enhanced by emulation of the logic circuits in programmable gate arrays. Two emulations of the logic circuit are preferably created, one of which is a "good" model containing no faults and the other of which is a "faultable" model into which possible faults may be selectively introduced. A fault is introduced in the faultable model, and the two models are exercised in parallel by applying the same pattern of test vectors to both models. The test vector pattern may be generated by an emulation of the intended operating environment of the logic circuit. Differences in the output signals of the two models indicate that the fault has been detected by the applied test pattern. Application of the test pattern is repeated for each of a sequence of possible faults, to determine the extent to which the test pattern enables detection of faults in the logic circuit.

Abstract: Driver circuits are provided which also serve as termination and clamp in an IC tester. When it is to drive a port of a device under test (DUT) between two predetermined voltage levels, the driver's I/O terminal is switched between two predetermined voltage levels with an output impedance that matches the transmission line between the driver circuit and the DUT. When the DUT's port is supplying an output signal, the driver circuit can be programmed to provide one of two types of termination. If the DUT's port is specified as capable of driving the load, the transmission line between the driver circuit and the DUT is terminated by switching the driver circuit's I/O terminal to a predetermined voltage level with an impedance of Z.sub.0. If the DUT's port is not specified as being capable of driving such a termination load, the driver circuit functions like a Z-clamp circuit.