Abstract: The presence of a crack in a material and the orientation of the crack is determined by placing a transducer on the surface of the material for propagating a shear wave for reflection off of the back wall of the material. The reflected signal is evaluated such that no signal or a weak signal indicates the presence of a crack. The transducer is then held in place and rotated while propagating a shear wave in order to determine the orientation of the crack. The reflected shear wave is then evaluated in the same manner.

Abstract: A method for compensating for the differences in temperature across a cell used to sense pressure. A microprocessor calculates a dynamic temperature factor signal by multiplying a signal representative of temperature change across the cell by a coefficient based on measurements made of the effect of temperature change on the cell. The dynamic temperature factor signal is then subtracted from the signal representative of the differential pressure sensed by the cell to thereby provide the dynamic temperature compensation.

Abstract: The disclosed flow monitoring apparatus has a flow-varied sensing capacitance and an inductor in a series-resonant circuit that modulates the frequency of an oscillator. In one apparatus, the sensing capacitance comprises a flow-activated vaned rotor whose blades sweep past a very small capacitive sensing electrode, for monitoring flow rates. In other apparatus a flow-activated blade is biased to remain opposite a very small capacitive sensing electrode, to provide on/off flow indication.

Abstract: An air flow meter comprises a main passage for an axial main air flow; an axial subpassage for air flow, disposed in the main passage and formed so that part of the air in the main passage is taken in at an upstream side thereof and flows in the same direction as the axial main air flow; a radial subpassage for air flow, intersecting the axial subpassage at a downstream side of the axial subpassage so that air from the axial subpassage flows into the radial subpassage and is divided into two radial air flows running in different radial directions; the air having passed through the radial subpassage joining the axial main air flow. An air flow sensing means is disposed in the radial subpassage for sensing a flow rate of air therein, and a projection is disposed in the radial subpassage around the intersection of the axial and radial subpassages, for suppressing turbulence of air flow around the intersection.

Abstract: A differential pressure sensor for measuring respiratory gas flow including a tubular housing containing a diametrically-oriented, longitudinally extending strut containing first and second lumens having longitudinally-spaced pressure ports opening into respective axially-located notches at each end of the strut.

Abstract: A Coriolis mass flow rate meter for measuring the mass flow rate of material flowing through a conduit. The flow meter includes at least one flow tube through which the material to be measured passes. The flow tube is vibrated at its natural frequency so that the concurrent flow of material through the vibrating tube produces a displacement of the tube with the magnitude of the displacement being dependent upon the magnitude of the generated Coriolis forces and the mass flow rate of the measured material. The phase of the displacement of the flow tube is measured using optical fiber sensors comprising at least one loop of optical fiber which is flexed by the displacement of the flow tube. This flexing of the fiber causes a corresponding change in its optical conductivity and a corresponding change in the intensity of the light transmitted through the fiber from a light signal source to a signal detector.

Abstract: A piezoelectric pressure sensor includes a generally elongated sensor housing, a pressure receiving plate disposed at a first end of the sensor housing with a first surface thereof serving as a pressure receiving surface for receiving a pressure applied from outside of the sensor housing, a pressure transmission member accommodated in the sensor housing with a first end thereof held in contact with a second surface of the pressure receiving plate, and a tubular piezoelectric element accommodated in the sensor housing with a first end thereof held in contact with a second end of the pressure transmission member. A pair of electrodes are formed on the external and internal surfaces of the piezoelectric element, respectively.

Abstract: An optical communications system including a plurality of modulated radio frequency carriers which span more than an octave in bandwidth. In one implementation, the carriers are grouped into ranges which span less than an octave in bandwidth and the individual groups are transmitted over unique optical links. In another implementation, the groups are multiplexed on one optical link by using different wavelengths. In still another implementation, several of the bands are up-converted to the highest band of interest and then transmitted, either over single or multiple links. The resulting optical signals are demodulated and then down-converted before they are recombined into the broadband signal in excess of an octave in bandwidth.

Abstract: The miniaturizable sensor comprises an insulating substrate (10) supporting first measurement electrode (24) and comprising a flexible measurement arm (18) of conductive or semiconductor material, one end of which is secured to the substrate (10) and the other end of which constitutes a second electrode facing the first electrode. The first end of the measurement arm is secured to the substrate via a beam (16) having a bending modulus at least ten times greater than that of the measurement arm (18) and substantially parallel to the measurement arm and via a foot (14) rigidly secured to the substrate (10) and situated between the two ends of the measurement arm, the connections of the beam (16) to the measurement arm (18) and to the foot (14) being of the fixed-end type.

Abstract: An apparatus for determining the flow rate of a flowing medium in the presence of pulsating flows and/or backflows, having a substrate as a carrier and a resistor arrangement located on the substrate for sensing medium flows. The resistor arrangement includes a temperature-sensitive resistor (R.sub.s), a heating resistor (R.sub.h), and compensation (R.sub.k) and bridge resistors (R.sub.1, R.sub.2, R.sub.3), which are arranged to create a feedback circuit that establishes a constant temperature environment, allowing electrical measurement of the flow mass. The substrate includes a fixed portion at one end, and two unfixed legs at the other end, the two legs divided by a notch. The width of each of the first leg and the notch is from 30 to 50 percent of the total width of the substrate, while the width of the second leg is at least 10 percent of the total width of the substrate.

Abstract: A sensor device for a mass flow controller suitable for stably sensing gas flowrate of the mass flow controller regardless of variation of peripheral temperature.

Abstract: An input signal provided by a generator is applied to a laser emitting diode via a predistortion circuit for improving the linearity of the response of the source. The predistortion circuit includes a linear pi attenuator member constituted by resistances and a non-linear compensating element constituted by a Schottky diode connected in parallel with said attenuator member. The invention is particularly applicable to making light transmitting cable heads for optical fiber telecommunications systems.

Abstract: A geostrophic wind forecasting method determines an atmospheric density (D) and a Coriolis parameter (F) at a given location. The atmospheric pressure is detected at the location over a predetermined period of time (t). The period of time (t), e.g., two hours, corresponds to the time required for a pressure surface to travel a distance (X) at an empirically determined velocity, e.g., 35 knots. The change in pressure (.DELTA.P) is detected over the period of time (t). The geostrophic wind velocity (VG) is then determined, according to the invention, based on the following relationship: VG=[1/(D.times.F)].times.[.DELTA.P/X]. The resulting geostrophic wind velocity (VG) is then displayed. At 35 knots, over a given two hour period, the distance X traveled by the pressure surface is approximately equal to 129,640 meters. The method is embodied in an apparatus that can be associated with a conventional barometer to produce a weather forecasting station.

Abstract: An amplitude control scheme for a high bit rate digital optical transmitter is disclosed. The data to be transmitted by the laser is pulse-width modulated by a low frequency signal. The pulse-width modulated signal is applied to the laser via a laser driver and to a mark density reference generator. The magnitude of the low frequency components from the mark density reference generator is a signal indicative of the desired amplitude of the laser light pulses. A back-face photodiode converts a portion of the laser light into an electrical signal, the magnitude of the low frequency portion thereof being a signal indicative of the actual amplitude of the laser light pulses. The actual amplitude of the laser light pulses is computed to the desired amplitude and the laser driver output amplitude may then adjusted to compensate for variations in the laser performance.

Abstract: An angular momentum mass flowmeter for measuring the mass flowrate of a fluid stream includes a flowmeter housing having an inlet or upstream end for receiving the fluid stream and an outlet or downstream end for discharging the fluid stream. A rotatable impeller is provided for measuring the mass flowrate. A swirl cap is disposed downstream of the impeller for imparting angular momentum to the fluid stream passing thereover and for causing the angular momentum to rotate the impeller. A control valve, disposed intermediate the impeller and the swirl cap, modifies the flow area of the fluid stream passing over the swirl cap to regulate the angular momentum of the fluid stream.

Abstract: A torque arm, for a dynamometer defining an axis of rotation, having a first, support, end configured for rigid attachment of the arm to the dynamometer, a second, free, end for engaging a reaction stop, a longitudinal axis, an axis intersecting and perpendicular to the longitudinal axis, the axes intersecting and being perpendicular to the axis of rotation when the arm is attached to the dynamometer and a strain gauge for measuring strain of the arm on the transverse axis whereby the strain measurement is a function of torque applied to the arm by an attached dynamometer about an axis of rotation independent of the distance between the axis of rotation and a reaction stop engaging the second end. A dynamometer assembly comprising a dynamometer and such a torque arm attached to a housing of the dynamometer.

Abstract: When digital signals are transmitted over optical fibers (3), which have a considerable chromatic dispersion at the wavelength being used, the length of the transmission path is very limited when the digital signal to be transmitted is converted into an optical signal by means of intensity modulation. If frequency modulation (also called FSK=Frequency Shift Keying) is used instead of the intensity modulation, the bridgeable path can be greatly increased, but requires a suitable optical receiver at the receiving end. The invention utilizes a simple optical receiver (4), which is not sensitive to frequency modulation, but to intensity modulation. This is possible, because an intensity variation is created, due to the chromatic dispersion of the optical fiber (3) and the resulting running time differences of signal portions at different wavelengths (.lambda..sub.0, .lambda..sub.

Abstract: The invention is directed to a flow sensor having a heater, two temperature measuring sensors, a heater temperature sensor and a medium temperature sensor. A control circuit is provided which controls the overtemperature of the heater in dependence upon the temperature of the flowing medium. With this arrangement, the influence of the temperature dependency of the following on the sensor characteristic are compensated: viscosity, thermal conductance and thermal capacity of the medium. The relationship between the heater temperature and the temperature of the medium is adjusted in a slightly nonlinear manner by means of special evaluation circuits. In this way, a further improvement of the temperature compensation is obtained.

Abstract: A Coriolis effect mass flow meter having a brace bar of improved flexibility which reduces the stress concentration in a brace bar as well as in areas of meter's flow tubes proximate the brace bar and flow tubes of the flow meter. A brace bar means is disclosed that has a void in an area between its holes that receive the flow tubes. This void increases the flexibility of the brace bar and shifts the concentration of operational and manufacturing induced stresses away from the braze joints between the brace bar and the flow tubes. The stresses are reduced and shifted away from the flow tubes to an area within the brace bar that is less critical to the overall life and reliability of the flow tubes. Meter sensitivity is improved due to enhanced flexibility of the present invention's brace bar in response to the motion induced by the Coriolis effect.

Abstract: A gas flow meter uses the principle of Boyle's law to measure the gas flow rate along a path. Gas flows through a valve into a reservoir until the pressure is maximized in the volume. The valve then vents the reservoir to ambient while blocking the inlet path. The pressure at maximum and minimum values is measured by a pressure sensor and used to generate the flow rate signal. An enlarged volume in the inlet path limits the pressure rise during the exhaust phase of the measurement cycle.