Abstract: A hydrocarbon liquid-seal device is provided. The device includes first and second conduits in fluid communication with each other such that the first and second conduits define a flow path therethrough configured to pass a hydrocarbon vapor. The first and second conduits are in a spaced relationship and are not rigidly coupled to one another for isolating a vibration or movement respectively therein. The device further includes a liquid disposed within a space between first and second end portions of the first and second conduits, respectively, such that the liquid blocks the space between the first and second end portions and seals the hydrocarbon vapor in the flow path.

Abstract: An environmental monitoring system and methods of a site are disclosed. The system includes one or more environmental measurement instruments, of which at least one instrument is capable to measure a concentration of particles in a certain size range. The system may also include an instrument that is capable of measuring a first concentration of particles in a first size range and a second concentration of particles in a second size range. The system may also include an instrument that is capable to measure a wind speed and a wind direction. The system may also include one device capable of recording an image of a location related to the site. The system includes a controller in communication with the one or more environmental measurement instruments, and a display device capable of displaying data generated by the one or more environmental measurement instruments. The system contains a network. Alerts can be provided based on conditions of the environment.

Abstract: In a measuring apparatus, an atmosphere to be inspected taken out from a space to be inspected in a processing system is analyzed for organic gas concentration. The apparatus is provided with a collector having an approach connected to the space to be inspected. The collector is connected to a gas exhaust system and an adsorption material for preparing a captured organic gas is held in the collector. A temperature control mechanism including a heater controls the adsorption/desorption of organic gas through temperature control of the adsorption material. A carrier gas is supplied from a carrier gas supplying system in order to transfer the desorbed gas taken from the captured organic gas and the concentration of organic gas in the carrier gas transferring the desorbed gas is determined in a concentration measuring unit.

Abstract: A miniaturized Schottky diode hydrogen and hydrocarbon sensor and the method of making same is disclosed and claimed. The sensor comprises a catalytic metal layer, such as palladium, a silicon carbide substrate layer and a thin barrier layer in between the catalytic and substrate layers made of palladium oxide (PdOx). This highly stable device provides sensitive gas detection at temperatures ranging from at least 450 to 600° C. The barrier layer prevents reactions between the catalytic metal layer and the substrate layer. Conventional semiconductor fabrication techniques are used to fabricate the small-sized sensors. The use of a thicker palladium oxide barrier layer for other semiconductor structures such as a capacitor and transistor structures is also disclosed.

Abstract: A non-contact shape sensor and shape sensing device employing a plurality of such sensors. A non-contact shape sensor of the present invention may include a fluid-emitting sensor head that is biased toward a surface of a moving strip of material by a linear actuator. Pressurized fluid emitted from said fluid-emitting sensor head forms a cushion that causes said strip of material to remain separated from and glide over said fluid-emitting sensor head without actual contact therewith. A linear displacement sensor is associated with each non-contact shape sensor to measure the linear displacement of its fluid-emitting sensor head by said linear actuator in response to a loose section of said strip of material passing by said fluid-emitting sensor head.

Abstract: A method for detecting separation in a structure that comprises at least two portions or layers affixed together comprises forming a cavity into the structure that passes through an interface formed between the two portions and plumbing the cavity to a monitoring system. A pressure differential is established between the cavity and a reference pressure to which the structure is exposed. A monitoring system monitors for a change in the pressure state of the cavity. Changes in the pressure state are indicative of a separation between the portions or layers.

Abstract: Methods and apparatuses are disclosed for detecting small leaks in double wall containers using enhanced tracer dispersal and detection techniques. More specifically, economical, substantially closed leak detection apparatuses, methods and systems are disclosed that conserve interstitial fluid between container walls enhancing the duration and sensitivity of leak detection testing.

Abstract: The present invention includes systems and methods for determining the viscosity of a fluid within a fluid flow path. Such method may comprise flowing fluid through the fluid flow path and past a fixed flow restriction therein. The method may also comprise first sensing of a fluid pressure within the fluid flow path at a selected location upstream of the flow restriction. The method may also include limiting fluid flow in the fluid flow path upstream of such selected location. The method may further comprise second sensing of a fluid pressure within the fluid flow path at such selected location after such limiting. Such method includes determining the viscosity of the fluid based, at least in part, on any pressure difference from such first and second sensing.

Abstract: A sensor for detecting a substance in liquid includes a sensing oscillation circuit and a reference oscillation circuit. The sensing oscillation circuit includes a sensing SAW element in which a reaction film arranged so as to cover at least one IDT and to react with a substance in liquid is disposed and a first amplifier circuit. The reference oscillation circuit includes a reference SAW element and a second amplifier circuit. The reference SAW element includes at least one IDT and no reaction film. The oscillation frequency of the sensing oscillation circuit and the oscillation frequency of the reference oscillation circuit are separated by at least about 200×k2 (ppm), where k2 (%) is the electromechanical coupling coefficient of a piezoelectric substrate used in each of the sensing SAW element and the reference SAW element.

Abstract: A stirring determination method uses an analyzer in which a liquid contained in a vessel is stirred by an acoustic wave generated by an acoustic wave generating unit attached to the vessel, optical characteristics of a reaction solution obtained by stirring the liquid are measured, and the reaction solution is analyzed based on the optical characteristics of the reaction solution. The method includes measuring a temperature of the liquid in a position where the temperature of the liquid is different before and after the liquid is stirred; and determining whether the liquid is properly stirred based on a rate of increase in the measured temperature of the liquid.

Abstract: Test methods for testing rotor and stator assemblies that utilize magnetic bearings prior to installation. The test method generally includes operating the rotor and stator assembly prior to installation in a test atmosphere at a pressure greater than 2 bar. The test atmosphere can be formed of air, an inert gas, or an expanded cryogenic gas.

Abstract: By forming an appropriate material layer, such as a metal-containing material, on a appropriate substrate and patterning the material layer to obtain a cantilever portion and a tip portion, a specifically designed nano-probe may be provided. In some illustrative aspects, additionally, a three-dimensional template structure may be provided prior to the deposition of the probe material, thereby enabling the definition of sophisticated tip portions on the basis of lithography, wherein, alternatively or additionally, other material removal processes with high spatial resolution, such as FIB techniques, may be used for defining nano-probes, which may be used for electric interaction, highly resolved temperature measurements and the like. Thus, sophisticated measurement techniques may be established for advanced thermal scanning, strain measurement techniques and the like, in which a thermal and/or electrical interaction with the surface under consideration is required.

Abstract: Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

Abstract: Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to decrease/suppress Vortex Induced Forces and Motion. Suppression is required when fluid-structure interaction becomes destructive as in VIM of flexible cylinders or rigid cylinders on elastic support, such as underwater pipelines, marine risers, tubes in heat exchangers, nuclear fuel rods, cooling towers, SPAR offshore platforms.

Abstract: A method for diagnosing a diverter valve of an internal combustion engine having a compressor is provided, for which diagnosis a variation over time of a charging pressure of the internal combustion engine as a result of a predefined triggering of the diverter valve is analyzed, the triggering of the diverter valve taking place in such a way that a diverter valve moved in the direction of its closing position is expected. Depending on the resulting variation over time of the charging pressure, an open jamming diverter valve is diagnosed if the variation over time of the charging pressure is not plausible with an expected variation over time for a diverter valve moved in the direction of its closing position.

Abstract: In a wheel support bearing assembly including a plurality of rolling elements (5) interposed between an outer member (1) and an inner member (2), a sensor unit (21) is fitted to one of the outer member and the inner member, which serves as a stationary member. The sensor unit includes a sensor mounting member (22) and a strain sensor (23) fitted to the sensor mounting member. The sensor mounting member has a plurality of contact fixing portions (22a, 22b) that are fixed to at least two locations spaced a distant from each other in a direction circumferentially of the outer member. A cutout (24) is provided in the outer member at respective positions corresponding to the neighboring contact fixing portions of the sensor mounting member, so as to extend in an axial direction. The strain sensor is arranged intermediate between the neighboring contact fixing portions.

Abstract: A tire system includes a plurality of piezoelectric devices mounted to the tire. The piezoelectric devices provide output signals in response to deformation of the tire. A processor has input terminals for receiving the signals from the piezoelectric devices, and the processor is programmed to determine tire parameters in response to the output signals from the piezoelectric devices. A power converter has input terminals for receiving the signals from the piezoelectric devices, and the power converter is connected to the processor to power the processor.

Abstract: A device for testing the adhesion of a coating to a substrate and a method of using the device are disclosed. The device is adapted to substantially replicate and consistently conduct the adhesion test procedure described in ASTM standards D3359 and F1842. The device includes a support with a source of a pressure sensitive adhesive tape rotatably mounted to the support. A tape dispenser and means to cause the tape to contact a test surface are mounted to the support. Means to remove the tape from the test surface is provided that includes a take-up spool adapted to receive the tape removed from the test surface.

Abstract: A sensor for measuring a property of a chemical, the sensor including: a light source; and a mixing medium in optical communication with the light source and exposed to the chemical; wherein four wave mixing of light interacting with the mixing medium provides a signal that indicates the property.

Abstract: A method for determining the flow characteristics of a geological formation; in a particular embodiment the method comprising the steps of: providing a container such as a core barrel within the formation; adding a portion of the formation, such as a core sample, into the container; and whilst the container remains in the formation, injecting fluid into the container such that a portion of the fluid flows through said portion of the formation and measuring the flow of the injected fluid to give information on the nature, such as permeability, of the core sample. In preferred embodiments fluid is received from the portion of the formation in the container to give more information on the core sample. Certain embodiments include packers to direct the flow of the fluids within the container. Such in situ measurements provide more accurate data on the reservoir characteristics, such as reservoir permeability.

Abstract: A method of analysing a reservoir pressure in an underground formation surrounding a well, comprising: determining the permeability of mud cake on the wall of the well in the region in which the pressure measurement is made; determining the thickness of mud cake on the well of the well in the region in which the pressure measurement is made; determining the hydrostatic pressure in the well in the region in which the pressure measurement is made; measuring the formation pressure at the wall of the well; calculating a pressure decay index from the mud cake permeability and thickness, the hydrostatic pressure and the measured pressure; and using the pressure decay index to analyse the measured pressure to derive the reservoir pressure.

Abstract: Testing process for testing zero emission hydrocarbon wells in order to obtain general information on a reservoir, comprising the following steps: injecting into the reservoir a suitable liquid or gaseous fluid, compatible with the hydrocarbons of the reservoir and with the formation rock, at a constant flow-rate or with constant flow rate steps, and substantially measuring, in continuous, the flow-rate and injection pressure at the well bottom; closing the well and measuring the pressure, during the fall-off period (pressure fall-off) and possibly the temperature; interpreting the fall-off data measured in order to evaluate the average static pressure of the fluids (Pav) and the reservoir properties: actual permeability (k), transmissivity (kh), areal heterogeneity or permeability barriers and real Skin factor (S); calculating the well productivity.

Abstract: A sensor for measuring at least one of temperature and pressure in a borehole, the sensor including a mixing medium disposed in a housing adapted for insertion into the borehole, the mixing medium exposed to at least one of the temperature and the pressure; wherein the mixing medium is used for four wave mixing of light to provide a signal that indicates at least one of the temperature and the pressure.

Abstract: Filling level indicator having an explosion-proof housing comprising a glass and a metallic frame, wherein the glass is fused into the frame.

Abstract: An instrument for measuring gravitational acceleration from within a borehole, the instrument including: a light source having a semiconductor that comprises a bandgap greater than about two electron volts (eV); and a gravimeter for receiving light from the light source and providing output light with a characteristic related to the gravitational acceleration, the gravimeter implemented at least one of a nano electromechanical system (NEMS) and a micro electromechanical system (MEMS); wherein the light source and the gravimeter are disposed in a housing adapted for insertion into the borehole.

Abstract: A sensor for measuring force, the sensor including: a light source; and a mixing medium in optical communication with the light source and exposed to the force; wherein four wave mixing of light interacting with the mixing medium provides a signal that indicates the force.

Abstract: A method and a circuit arrangement for the start-up of a rate-of-turn sensor (DRS) comprising at least one oscillator element are disclosed, wherein the operational control of the rate-of-turn sensor amplifies a signal (v(t), x(t)) proportional to the instantaneous speed or deflection of the oscillator element used as operating signal (F(t)) to operate the oscillator element. During the start-up process for the rate-of-turn sensor (DRS) the amplification of the amplitude (AF) of the operating signal (F(t)) is set to a constant pre-settable value (AFC) the stimulation frequency of the operating signal (F(t)) being essentially continuously raised from a starting value (f1) below the main resonance frequency of the oscillation movement to a final value (f2) above the main resonance frequency and below a spurious resonance frequency with simultaneous monitoring of the deflection (x(t)) and/or the speed (v(t)) of the oscillator element, in order to determine the main resonance frequency.

Abstract: A sensor that measures angular velocity about an axis that is normal to a sensing plane of the sensor. The sensor comprises a sensing subassembly that includes a planar frame parallel to the sensing plane, a first proof mass disposed in the sensing plane, a second proof mass disposed in the sensing plane laterally to the first proof mass, and a linkage within the frame and connected to the frame. The linkage is connected to the first proof mass and to the second proof mass. The sensor further includes actuator for driving the first proof mass and the second proof mass into oscillation along a drive axis in the sensing plane. The sensor further includes a first transducer to sense motion of the frame in response to a Coriolis force acting on the oscillating first proof mass and the oscillating second proof mass.

Abstract: The invention relates to a method for operating a vibrating gyroscope and to a sensor arrangement comprising such a vibrating gyroscope. Said vibrating gyroscope is used as a resonator and is part of at least one control circuit that excites the vibration gyroscope by feeding an excitation signal with its natural frequency. An output signal can be tapped from the vibrating gyroscope from which the excitation signal can be derived by filtering and amplification. The invention is characterized in that, once a sensor arrangement comprising the vibrating gyroscope is switched on, an initial value for the natural frequency is calculated from a previously measured value of the natural frequency stored in a memory and parameters that effect a modification of the natural frequency since start of the measurement, and the excitation signal is fed to the vibrating gyroscope with the calculated initial value of the frequency.

Abstract: A panel inspection apparatus includes a resonant frequency extracting unit for extracting a plurality of resonant frequencies of a panel, a resonant frequency selecting unit for selecting a combination of resonant frequencies consisting of two resonant frequencies A and B with different vibration propagation paths among the extracted plurality of resonant frequencies, a non-defective range generating unit for generating a non-defective range on a coordinate system in which resonant frequencies A and B are taken on coordinate axes by statistically processing a set of the resonant frequencies A and B selected for each of a plurality of non-defective panels determined as non-defective in advance, and a panel quality determining unit for determining whether the quality of the panel to be inspected is good based on comparison between resonant frequencies A and B selected for the panel to be inspected and the non-defective range generated by the non-defective range generating unit.

Abstract: A method for measuring variations of the surface of an object using acoustic energy in the audio range is provided. Imaging fine surface roughness on the order of few microns is achievable by using a vibroacoustography technique. This technique provides a method for imaging surface roughness on the basis of an ultrasound radiation force that stimulates acoustic emissions at an ultrasound standing wave field. The present invention may be employed as a tool for the nondestructive inspection and imaging of the surface variations of an object.

Abstract: Provided is a bearing state diagnostic apparatus in which a sound generated from a bearing is detected by a sound sensor, a detected value of the sound sensor is compared with data which was previously formed, thereby diagnosing a state of the bearing, wherein at least one sound sensor is disposed at a position separated away from an outer surface of a cylindrical support body in which at least one bearing is accommodated, the corresponding bearing and sound sensor are in communication with each other through a detection sound propagation path.

Abstract: The invention relates to a method and system for ultrasonic time of flight diffraction inspection of a plastics wall, such as a pipe wall. The method comprises providing an ultrasound transmitter and transmitting an ultrasound signal having a nominal frequency into the wall, providing an ultrasound receiver and receiving the ultrasound signal transmitted through the wall. The ultrasound signal provided by the transmitter has a bandwidth of more than 80%, preferably more than 100% of the nominal frequency of the ultrasound signal provided by the transmitter.

Abstract: A combined electromagnetic acoustic transducer (EMAT) is disclosed that uses magnetic shielding to increase the efficiency (defined as the received signal per unit of excitation current). In addition, electromagnetic shielding may also be used to reduce the direct coupling between the transmit and receive coils. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: An ultrasonic test apparatus includes a container containing de-ionized water, a pressing member, a supporting member, and a fixing member. The limiting member, the loading member, and the cover member are disposed in the de-ionized water. The fixing member tightly fixes the pressing member and the supporting member together for mounting at least part of integrated circuits to be detected between the pressing member and the supporting member.

Abstract: A high spatial resolution phase-sensitive technique employs a scanning near field ultrasound holography (SNFUH) methodology for imaging elastic as well as viscoelastic variations across a sample surface. SNFUH uses a near-field approach to measure time-resolved variations in ultrasonic oscillations at a sample surface. As such, it overcomes the spatial resolution limitations of conventional phase-resolved acoustic microscopy (i.e. holography) by eliminating the need for far-field acoustic lenses.

Abstract: The invention is objected to enable the provision of an vessel steel plate measuring device capable of measuring the thickness of vessel steel plate, even in the case of a vessel having a vessel mirror part formed by a spherical or conical curved surface such as a reactor (reaction vessel) and various kinds of obstructions at a vessel barrel. The structure of the device is characterized in that a supporting point member 20 is detachably provided from a supporting point set at the central axis of the vessel mirror part 1a of a reactor 1, and a traveling carrier 6 traveling on a steel plate of the vessel mirror part 1a and having plural ultrasonic probes 7 mounted thereon is connected to one end of a turning radius regulating member 19 rotatively provided around the supporting point member 20.

Abstract: A method & apparatus for conveying an ultrasonic sensor about an outer peripheral surface of a tube to perform a non-destructive evaluation thereof is disclosed. The ultrasonic sensor is mounted on a flexible tension link and the method involves extending the flexible tension link while urging an extended portion of the flexible tension link towards the outer peripheral surface of the tube at a plurality of locations along it's length, thereby causing the ultrasonic sensor to move through an arc in a direction circumferentially around the tube while maintaining ultrasonic coupling between the ultrasonic sensor and the tube.

Abstract: A noninvasive system and method for measuring vacuum pressure in a fluid in accordance with the present invention generally includes a chamber with two interconnected diaphragms having different surface areas and a force transducer that makes contact with the smaller area diaphragm. When a pressure level less than atmospheric occurs inside the chamber, the smaller area diaphragm presses with a force on the force sensor. As the pressure level in the chamber decreases, the force on the sensor increases. The present system is intended for, but not limited to, use in a Phacoemulsification machine, where it will serve to measure the vacuum in a fluid without contaminating the fluid with previous uses of the system or with any components of the system which are unable to undergo a sterilization process.

Abstract: A pressure header assembly has a closed front and back surface. The back surface has an aperture for accommodating a separate dual die pressure header. The dual die pressure header has an absolute and differential pressure sensor positioned thereon. A differential pressure port is located on a side surface of the pressure header assembly and is directed to a bore in the pressure header assembly. The bore contains an elongated tube which is positioned in the pressure header assembly and locked in place by means of a crush nut and locking nut assembly. One end of the tube is coupled to the differential pressure port, while the other end of the tube accommodates a differential pressure tube which is bent in an arcuate position and directed to the underside of the sensor of the differential sensor assembly mounted in the dual die pressure header.

Abstract: An electrostatic capacitance diaphragm type pressure sensor which includes a stationary electrode and a diagraph that are arranged to oppose each other, and in which the diaphragm is deformed by an external force and a pressure is obtained from an electrostatic capacitance between the stationary electrode and diaphragm which changes in accordance with deformation of the diaphragm, includes an outer case which surrounds the main body of the sensor, a heater arranged on the inner surface of the outer case, a temperature sensor to measure the temperature inside the outer case, and a temperature adjustment circuit which compares a temperature signal obtained by the temperature sensor with a predetermined value and outputs a drive signal to drive the heater on the basis of the comparison result.

Abstract: A chip with resistive, metallic strain gauges distributed on surfaces on and buried within the chip. Also, vertically arranged vias and vertical thin film resistive strain gauges are described. The resistive strain gauges can be multiplexed wherein strain can be measured across the topology of the chip in each of the top, bottom and buried layers and any vertical strain. The resistive strain gauges may be in serpentine patterns and may be arranged on via or on vertical edges of grooves that extend from an upper or lower surface of the chip to buried layers. In this fashion, the distributed strain gauges may be used to map the strain throughout the body of a chip. A Kelvin bridge may be used to measure the strain, but other such measuring techniques and devices may be used.

Abstract: An accelerometer is provided including a strain sensor with a substantially linear configuration. The strain sensor is mounted on a transducer such that the strain sensor extends laterally across the transducer. The transducer has a base and a plurality of flaps joined at a first end to the base and supporting the strain sensor at a second end. The flaps translate acceleration in a predefined direction to strain in the strain sensor. Further embodiments have flaps defining an interrupted surface with greater height at the center and flaps that have features for enhancing the strain caused by acceleration.

Abstract: A method of evaluating material properties of polymeric materials includes making one or more material samples or slabs, with each of the samples or slabs having a pair of material layers in contact with one another. The layers are layers of organic matrix polymer material that have different characteristics from each other, for example having a difference in composition and/or cure characteristics. Characteristics of the test slabs and the interface between the layers can be determined by examining curvatures of the test slabs. A number of samples may be made up having the same material in a first layer, and range of different materials in the respective second layers. The range may cover a range of various material compositions and/or cure characteristics.

Abstract: Provided is a stress history recording system for recording a stress history, which includes a light emitting means including a stress-stimulated luminescent material that emits light in response to a mechanical external force, and a recording means for recording a history of a photoreaction generated due to light emission from the light emitting means. This achieves a technology for recording a stress history by using the stress-stimulated luminescent material.

Abstract: Embodiments of shaft torque profiling apparatuses and methods of use are generally described herein. In one embodiment, a method for determining the torsional stiffness of a least a portion of a shaft comprises: immobilizing a first portion of the shaft; immobilizing a second portion of the shaft to define a first region between the first portion and the second portion; rotating a first portion of the first region about an axis of the shaft; and measuring a rotation of the first portion of the first region. Other embodiments herein may be described and claimed.

Abstract: A testing device (10) for high-pressure injectors (50) of a common rail injection system of an engine unit, with the high-pressure injectors (50) each having a fuel return connection (52) for a fuel return line (54) is characterized by a throughflow quantity measuring/display unit (12) which can be detachably connected between the fuel return connection (52) and fuel return line (54).

Abstract: A flow sensing apparatus detects movement of a faucet handle of a faucet of a hot water container in order to detect flow from the hot water container. A reed switch and an associated magnet can be mounted to detect open and closed positions of the faucet handle to provide electronic logic information regarding the status of the faucet handle position as an indication of a flow condition to a control unit that controls heating of water in the hot water container.

Abstract: A photo-acoustic flow meter for use in dialysis is described, that uses an optical beam to generate an acoustic signal in the fluid for which the flow rate is to be measured. The phase angle of the acoustic signal changes when traversing upstream and when traversing downstream. The phase difference between the acoustic signals received upstream and downstream, compared with a reference source signal is measured, and it yields the flow rate of the fluid.

Abstract: Systems and methods are disclosed for measuring densities and flow rates of gas-liquid fluid mixtures. In the systems and methods, the fluid mixture is caused to exhibit swirling flow as it flows through a conduit that includes a constriction, a first pressure difference is measured between two vertically-spaced measurement positions in the conduit, a second pressure difference is measured between two horizontally-spaced measurement positions in the conduit, the first horizontally-spaced measurement position being at the constriction region and the second horizontally-spaced measurement position being upstream or downstream of the constriction region, and one or more of the pressure differences is used to determine a density or a flow rate of the gas-liquid fluid mixture.