Abstract: A method for operating a thermal flow sensor includes: bringing a measuring medium into thermal contact with a sensor element of the flow sensor and periodically heating the medium using an AC voltage introduced into the sensor element; simultaneously detecting a maximum amplitude of a temperature and/or a phase shift between a curve of the AC voltage and the curve of the temperature; adjusting the detected maximum amplitude and/or the detected phase shift using calibration data; determining an isoline using the adjusted maximum amplitude and/or the adjusted phase shift based on model of the flow sensor, wherein the isoline has a plurality of value pairs of thermal conductivity and thermal capacitance of the medium; deriving a medium information from the isoline; and performing a flow measurement by converting signal values from the sensor element into measurement values of an effective flow velocity of the medium using the medium information.

Abstract: A flow sensor system for detecting the presence or absence of flow of a liquid nutrient formula through a conduit of an enteral feeding system. The flow sensor system includes a channel configured to retain the conduit therein, a heat source disposed at a first location at a first portion of the conduit, and a heat detector disposed at a second location at a second portion of the conduit. The heat source may include an IR LED, and the heat detector may include a thermopile sensor. A method for using the flow sensor system to detect the presence or absence of flow of a liquid nutrient formula through a conduit of an enteral feeding system is also disclosed.

Abstract: A gas sensor having a heater, a receiver, and a space arranged between the heater and the receiver, is described, the heater being configured to generate a thermoacoustic sound wave propagating through the space by using a stimulation signal. The receiver is in this case configured to receive the thermoacoustic sound wave that has propagated through the space and to convert it into a reception signal that has a time-of-flight-dependent shift with respect to the stimulation signal and therefore information relating to the gas concentration in the space.

Abstract: A method and apparatus for determining multiphase flow characteristics inside production equipment containing at least two fluids. A pulse of heat from a heat source adjacent to the production equipment is provided, and a thermal response to the pulse is measured at each of a plurality of temperature sensors located adjacent to the production equipment. The thermal response measurement includes a time constant obtained from a measured decline in the temperature after the pulse of heat has been provided. The measured thermal responses are used to determine parameters of a fluid contained in the production equipment in proximity to each of the temperature sensors. The determined fluid parameters are in turn used to determine multiphase flow characteristics.

Abstract: A system for controlling administration of medical fluid includes a fluid passageway to which is attached a first flow regulator, a second flow regulator, and a flow detector. The system also includes a controller for controlling the first and second flow regulators in response to a measurement taken by the flow detector of fluid movement in the fluid passageway. The first flow regulator, such as a pump, is configured to maintain fluid movement at flow values greater than an unrestricted flow value. The second flow regulator, such as a variable adjustable valve, is configured to maintain fluid movement at a flow value less than the unrestricted flow value. A method of controlling administration of medical fluid includes obtaining a target flow value, moving fluid through the disposable assembly, taking a measurement of fluid movement in the disposable assembly, and actuating a flow regulating apparatus.

Abstract: The invention relates to a system (102) for measuring a velocity of a fluid (104) flowing through a flow channel (106). The system comprises a heating element (108) configured for generating a thermal marker in the fluid (104) in response to a predetermined time-varying level of power provided to the heating element (108). The system (102) furthermore comprises a sensor arrangement (110) for generating a measurement signal (112) indicative for the velocity of the fluid (104) flowing through the channel (106). Herein, the sensor arrangement (110) is configured for measuring a time series of the primary temperature (114) of the fluid (104) at a predetermined primary location. The primary location and the heating element (108) are situated on an axis having at least a component parallel to the longitudinal axis (119) of the flow channel (106). The measurement signal (112) is based on the maximum value (120) of the time series of time series of the primary temperature (114) in response to the thermal marker.

Abstract: A method and apparatus for predicting the arrival time of a transit vehicle at a transit stop of a transit route is presented. The arrival time is predicted using historical location information of a plurality of vehicles that have previously traveled the route, location information of several of the most recent vehicles that have arrived at the stop, and current location information of a particular vehicle currently traveling the route. Values such as average arrival times and arrival time errors or variances are determined from the historical and recent location data. These values are used with the current location information to predict the arrival time of the particular vehicle.

Abstract: The present disclosure relates to a method and an apparatus for measuring a flow rate through a conduit, such as a pipeline. The method comprises providing a reference parameter, measuring a first parameter at a first position at the conduit and determining a difference between the first parameter and the reference parameter. The flow rate through the conduit is determined based on the difference between the first parameter and the reference parameter.

Abstract: An apparatus comprising a micromachined (a.k.a. MEMS, Micro Electro Mechanical Systems) silicon flow sensor, a flow channel package, and a driving circuitry, which operates in a working principle of thermal time-of-flight (TOF) to measure gas or liquid flow speed, is disclosed in the present invention. The micromachining technique for fabricating this MEMS time-of-flight silicon thermal flow sensor can greatly reduce the sensor fabrication cost by batch production. This microfabrication process for silicon time-of-flight thermal flow sensors provides merits of small feature size, low power consumption, and high accuracy compared to conventional manufacturing methods. Thermal time-of-flight technology in principle can provide accurate flow speed measurements for gases regardless of its gas compositions. In addition, the present invention further discloses the package design and driving circuitry which is utilized by the correlated working principle.

Abstract: Methods, apparatus, and systems are provided for measuring the supply of a consumable product/energy source, such as electrical power, to a facility over time and analyzing the measurements to determine the consumption or supply of the product by one or more loads and/or sources in the facility, and to determine induced and residual heat flow through the facility's envelope. Various aspects compare the measured supply of the consumable product to a database of consumption signatures, which characterize access to the consumable product by particular users. Operating conditions and facility characteristics, such as temperatures, load factors, insulation factors, etc., may be further considered in determining a particular user's access of the consumable product. To aid in the controlling of energy use, thermal resistance factors of the building are determined, which are based on the induced and residual heat flow through the facility.

Abstract: The invention relates to a pipe assembly (102) for use in a boiler. The pipe assembly (102) comprises a pipe (104) having an outer wall (106) adapted for heat exchange. The pipe (104) having heat sensing means (116) located in a recess section of the outer wall (106) thereof, wherein an internal bore (108) of the pipe (104) has a substantially constant cross section in the region of the heat sensing means (116).

Abstract: The present disclosure relates to a method and an apparatus for measuring a flow rate through a vessel, such as a conduit or pipeline. The method comprises providing a reference parameter, measuring a first parameter at a first position at the vessel and determining a difference between the first parameter and the reference parameter. The flow rate through the vessel is determined based on the difference between the first parameter and the reference parameter.

Abstract: The invention relates to a system (102) for measuring a velocity of a fluid (104) flowing through a flow channel (106). The system comprises a heating element (108) configured for generating a thermal marker in the fluid (104) in response to a predetermined time-varying level of power provided to the heating element (108). The system (102) furthermore comprises a sensor arrangement (110) for generating a measurement signal (112) indicative for the velocity of the fluid (104) flowing through the channel (106). Herein, the sensor arrangement (110) is configured for measuring a time series of the primary temperature (114) of the fluid (104) at a predetermined primary location. The primary location and the heating element (108) are situated on an axis having at least a component parallel to the longitudinal axis (119) of the flow channel (106). The measurement signal (112) is based on the maximum value (120) of the time series of time series of the primary temperature (114) in response to the thermal marker.

Abstract: The present disclosure relates to a method and an apparatus for measuring a flow rate through a conduit, such as a pipeline. The method comprises providing a reference parameter, measuring a first parameter at a first position at the conduit and determining a difference between the first parameter and the reference parameter. The flow rate through the conduit is determined based on the difference between the first parameter and the reference parameter.

Abstract: An apparatus comprising a micromachined (a.k.a. MEMS, Micro Electro Mechanical Systems) silicon flow sensor, a flow channel package, and a driving circuitry, which operates in a working principle of thermal time-of-flight (TOF) to measure gas or liquid flow speed, is disclosed in the present invention. The micromachining technique for fabricating this MEMS time-of-flight silicon thermal flow sensor can greatly reduce the sensor fabrication cost by batch production. This microfabrication process for silicon time-of-flight thermal flow sensors provides merits of small feature size, low power consumption, and high accuracy compared to conventional manufacturing methods. Thermal time-of-flight technology in principle can provide accurate flow speed measurements for gases regardless of its gas compositions. In addition, the present invention further discloses the package design and driving circuitry which is utilized by the correlated working principle.

Abstract: A fluid flow meter is described that uses thermal tracers to measure flow speed. For fluid flowing through a conduit, the fluid is heated at a heating location in the conduit with a time-dependent heating strength. A speed of sound in fluid flowing in the conduit is measured at multiple sensing locations downstream from said heating location. The flow speed of the fluid is determined from a delay with which the time dependence is detected in the sound speeds measured at the sensing locations. A frequency of the variation of heating strength that is used to determine the flow speed is selected automatically based on the flow speed and/or other circumstances.

Abstract: Example methods and apparatus to measure fluid flow rates are disclosed. A disclosed example apparatus includes a circulator to selectively circulate a fluid in a flowline, a generator thermally coupled to the flowline at a first location and controllable to form a heat wave in the fluid, a sensor thermally coupled to the flowline at a second location to measure a first value representative of the heat wave, a phase detector to determine a second value representative of a wavelength of the heat wave based on the first value, a frequency adjuster to control the generator to form the heat wave in the fluid at a first frequency, the first frequency selected so that the second value is substantially equal to a distance between the first and second locations, and a flow rate determiner to determine a flow rate of the fluid based on the first frequency.

Abstract: A measurable flow-rate range is increased to enhance usability. A flow-rate measuring method for measuring the flow rate of a fluid inside a tube is provided. This method uses a thermal-marker generator that heats the fluid flowing through the tube from the outside thereof to generate a thermal marker in the fluid inside the tube and a thermal-marker detector disposed downstream of the thermal-marker generator and configured to detect the thermal marker in the fluid inside the tube generated by the thermal-marker generator, so as to measure the flow rate on the basis of the distance between the thermal-marker generator and the thermal-marker detector, a time period between a point at which the thermal marker in the fluid inside the tube is generated by the thermal-marker generator and a point at which the thermal marker is detected by the thermal-marker detector, and the cross-sectional area of the tube.

Abstract: A heat signal writing device forming a clear writing pattern of a heat signal is provided. A heat signal writing device 10 for writing a heat signal in a medium traveling through a channel, which is secured to an appropriate position on the channel through which the medium flows, includes a Peltier element 11 for writing the heat signal having a temperature change according to a desired pattern by heating or cooling; a channel supporting member 12 shaped as a pyramid formed of a heat conductive material and having a bottom surface in close contact with a surface of the Peltier element 11, the tip of the pyramid being in direct contact with the channel 1; a heat sink 13 in close contact with another surface of the Peltier element 11; and a heat-resistant cover for covering the periphery of the Peltier element 11, excluding a channel contact surface 12a at the tip, and the channel supporting member 12.

Abstract: A flow rate/liquid type detecting method for detecting the flow rate of a fluid and, at the same time, detecting any one of or both the type of the fluid and the concentration of the fluid, characterized in that, by using a flow rate/liquid type detecting apparatus comprising: a main passage through which a fluid to be detected flows, an auxiliary passage branched from the main passage, and a flow rate/liquid type detecting sensor device provided in the auxiliary passage, is provided, and in conducting any one of or both the detection of the type of the fluid and the detection of the concentration of the fluid, the auxiliary passage opening/closing valve is closed, and the fluid is allowed to temporarily stay within the flow rate/liquid type detecting sensor device to conduct any one of or both the detection of the liquid type and the detection of the concentration, and in detecting the flow rate of the fluid detected, the auxiliary passage opening/closing valve is opened to allow the fluid to flow into the f

Abstract: Fluid flows through a conduit. To measure flow speed the fluid is heated at a heating location in the conduit with a time-dependent heating strength. A speed of sound in fluid flowing in the conduit is measured at a plurality of sensing locations downstream from said heating location. The flow speed of the fluid is determined from a delay with which the time dependence is detected in the sound speeds measured at said sensing locations. In an embodiment a frequency of the variation of heating strength that is used to determine the flow speed is selected automatically dependent on the flow speed and/or other circumstances.

Abstract: A measurable flow-rate range is increased to enhance usability. A flow-rate measuring method for measuring the flow rate of a fluid inside a tube is provided. This method uses a thermal-marker generator that heats the fluid flowing through the tube from the outside thereof to generate a thermal marker in the fluid inside the tube and a thermal-marker detector disposed downstream of the thermal-marker generator and configured to detect the thermal marker in the fluid inside the tube generated by the thermal-marker generator, so as to measure the flow rate on the basis of the distance between the thermal-marker generator and the thermal-marker detector, a time period between a point at which the thermal marker in the fluid inside the tube is generated by the thermal-marker generator and a point at which the thermal marker is detected by the thermal-marker detector, and the cross-sectional area of the tube.

Abstract: A flow rate/liquid type detecting method for detecting the flow rate of a fluid and, at the same time, detecting any one of or both the type of the fluid and the concentration of the fluid, characterized in that, by using a flow rate/liquid type detecting apparatus comprising: a main passage through which a fluid to be detected flows, an auxiliary passage branched from the main passage, and a flow rate/liquid type detecting sensor device provided in the auxiliary passage, is provided, and in conducting any one of or both the detection of the type of the fluid and the detection of the concentration of the fluid, the auxiliary passage opening/closing valve is closed, and the fluid is allowed to temporarily stay within the flow rate/liquid type detecting sensor device to conduct any one of or both the detection of the liquid type and the detection of the concentration, and in detecting the flow rate of the fluid detected, the auxiliary passage opening/closing valve is opened to allow the fluid to flow into the f

Abstract: A method and apparatus for monitoring and controlling nano-scale flow rate of fluid in the operating flow path of a HPLC system provide fluid flow without relying on complex calibration routines to compensate for solvent compositions gradients typically used in HPLC. The apparatus and method are used to correct the flow output of a typical, analytical-scale (0.1-5 mL/min) HPLC pump to enable accurate anti precise flow delivery at capillary (<0.1 mL/min) and nano-scale (<?L/min) HPLC flow rates.

Abstract: A flowing electrically-conductive fluid is controlled between an upstream and downstream location thereof to insure that a convection timescale of the flowing fluid is less than a thermal diffusion timescale of the flowing fluid. First and second nodes of a current-carrying circuit are coupled to the fluid at the upstream location. A current pulse is applied to the current-carrying circuit so that the current pulse travels through the flowing fluid to thereby generate a thermal feature therein at the upstream location. The thermal feature is convected to the downstream location where it is monitored to detect a peak associated with the thermal feature so-convected. The velocity of the fluid flow is determined using a time-of-flight analysis.

Abstract: A flow rate/liquid type detecting method for detecting the flow rate of a fluid and, at the same time, detecting any one of or both the type of the fluid and the concentration of the fluid, characterized in that: by using a flow rate/liquid type detecting apparatus comprising a main passage through which a fluid to be detected flows, an auxiliary passage branched from the main passage, and a flow rate/liquid type detecting sensor device provided in the auxiliary passage, is provided, and in conducting any one of or both the detection of the type of the fluid to be detected and the detection of the concentration of the fluid to be detected, an auxiliary passage opening/closing valve is closed, and the fluid to be detected is allowed to temporarily stay within the flow rate/liquid type detecting sensor device to conduct any one of or both the detection of the liquid type and the detection of the concentration, and in detecting the flow rate of the fluid to be detected, the auxiliary passage opening/closing valv

Abstract: The invention relates with the feed-back control system of a heat exchanger by use of the flow resonance phenomenon which maximizes the heat transfer efficiency by generating the flow disturbances of a heat transfer medium. If a heat transfer medium is periodically stimulated at the characteristic frequency of a heat exchanger, the flow resonance frequency, which is dependent upon the flow conditions of heat transfer medium and the geometries of a heat exchanger, the disturbances of heat transfer medium is increased to the extent that heat transfer is dramatically high. This system is composed of the detecting part for the detection of flow characteristics, the processing part for the determination of flow resonance frequency, and the stimulating part which excites a heat transfer medium at the calculated flow resonance frequency.

Abstract: A method and apparatus for measuring in situ flow of non-aqueous phase liquids (NAPLs) through a porous medium is described. A tracer is introduced into a well or boring located in the medium and the tracer concentration in the well kept uniform by mixing. The rate at which the tracer is depleted from the well has been determined to be proportional to the flow rate of the NAPL through the well or boring and surrounding formation.

Abstract: In thermal pulse flow measurements a relatively small bolus of flowing fluid is heated or cooled and the time required for the bolus to move downstream a known distance is measured. In many fluids, changing the temperature changes the acoustic transmission properties of the bolus from those of the rest of the fluid, so the bolus can be detected when it intersects an acoustic beam. The use of an acoustic beam or beams, which are usually defined between acoustic transmitting receiving transducers, typically provides a high frequency carrier which is modulated by the change in acoustic properties of the bolus when it passes between the two transducers. When compared to conventional thermal measurements, this acoustic approach provides faster response times and can thus be used for measuring higher flow rates.

Abstract: A transducer is disclosed for sensing flow of a fluid. The transducer includes means for applying a heat pulse to the fluid and at least one temperature sensor. The temperature sensor is adapted to detect a decaying response to the heat pulse to provide an indication of the flow. The decaying response may be detected by comparing measured voltages at a set moment in time or by comparing measured times at a set voltage threshold. A method for sensing flow of a fluid is also disclosed.

Abstract: A thermistor is pulsed with energy, and a time constant of decay of temperature is calculated based on measured resistance of the thermistor over a number of known intervals. The time constant is representative of the mass air flow. The ambient air temperature may be found without waiting for the thermistor to reach the ambient air temperature.

Abstract: A method for measuring the flow rate of a fluid flowing in a conduit includes separating the fluid into two portions then flowing into two branches (20, 22). Both portions are then recombined in an outlet manifold (14). A difference is created between the temperature of the fluid in one of the two branches (20, 22) and the temperature of the fluid in the other branch, and the passage section for the fluid in each of both branches is modulated while maintaining the total passage section constant for the fluid in both branches so that the temperature of the fluid in the outlet manifold (14) varies in a modulated way. The temperature changes of the fluid in the outlet manifold (14) are detected versus time, and the flow rate of the fluid in the conduit is determined from the detection of temperature versus time.

Abstract: A thermal transient anemometer provides mass flow rate or volume flow rate over smaller discrete regions of a larger flow field, i.e., the distribution of such rates over a predefined, larger area. The thermal transient anemometer comprises two components: a frame with a plurality of sensing cells each having a resistance wire grid and a control unit which includes an energy source which heats the resistance wire grid of each cell, measurement circuitry for determining the decay of resistance of the grid wires as they cool and computational circuitry which determines the mass or volume flow rate through each cell based upon such decay function.

Abstract: The fluid flow rate within a microfluidic passageway of a microfabricated device is determined by measuring the time-of-flight of a heat pulse coupled into the fluid. Since the propagation velocity of the heat trace is generally slower than the mean flow rate of the flow, additional processing provides the appropriate scaling needed to obtain an accurate fluid flow rate measurement. The scaling factor is based on the geometry of the structure and the thermal properties of the fluid and the materials used for the device.

Abstract: Systems and methods for measuring the flow of a liquid along a conduit are disclosed. A heat source applies thermal energy to a portion of a liquid flowing along a conduit thereby elevating its temperature. An optical sensing means comprising a light source illuminating the liquid in the conduit downstream from the position of application of the thermal energy and an optical detector receiving a portion of this illumination senses the heated portion of liquid by measures a change in an optical property of the illumination caused by a change in the index of refraction of the heated portion of liquid. The time required for the heated portion of the liquid to move from the point of application of thermal energy to the point of optical sensing is measured. This measured time, along with the distance of separation of the heat source and the optical sensing means permits calculation of the velocity of the liquid in the conduit.

Abstract: The spirometer has a low thermal capacity. A circuit supplies power to the spirometer in pulses to heat the spirometer to body temperature. The circuit senses the temperature of the spirometer between intervals. The circuit can also be used in a calorimeter to measure the heat exchange during chemical reactions using the palladium hydrogen. The heating and sensing functions are performed by a single element to result in a small pocket sized device. The portability of the device increases its usefulness.

Abstract: When a bolus dose of cold saline is injected into a catheter where a wire, carrying a sensor unit and electrical leads for signal transmission, is located, the lead resistance is affected by the cold saline thereby altering the resistivity. However, by countering this effect and measuring the change needed to affect this countermeasure, a resistance variation curve can be generated. An accurate starting point for the determination of a transit time can be derived from the curve. Using conventional flow measurement calculations with the accurate starting point yields a better understanding of the flow profile in an artery based on the transit time.

Abstract: A method of determining a rate of flow of a first gas in a pipe includes placing a flow-restricting device in the pipe such that the device and/or the pipe define a first channel section and a second channel section. The second channel section is disposed downstream from the first channel section. The first channel section has a first cross-sectional area. The second channel section having a second cross-sectional area less than the first cross-sectional area. A source of a second gas is provided in fluid communication with the second channel section. A low pressure in the second channel section is caused by an increased flow velocity and creates a flow of the second gas into the second channel section. A rate of a flow of the second gas into said second channel section is measured. A mathematical relationship between the rate of the flow of the second gas into the second channel section and the rate of flow of the first gas in the pipe is ascertained.

Abstract: A method and apparatus is disclosed for measuring the flow of fluid in the conduit, giving the example of oil in a well bore (12). A heat exchanger such as a cooling station (66) is placed in the well bore (12) and caused to create a slug of cooled oil whose passage, through the well (12) can be monitored by a temperature sensor in the form of a continuous fiber optic loop (62). Knowledge of the movement of the cooled slug of oil and of the free cross-section of the conduit (54) wherein the oil is flowing permits the volume flow-rate of oil to be calculated. Cooling stations (66) are cooled by Joule-Thompson cooling employing high pressure nitrogen gas. Cooling stations (66) may be placed at plural locations within the well bore (12) to monitor individual flows (68) from multiple flow sources.

Abstract: The present invention relates to methods and apparatus useful for detecting and measuring flow of a fluid along a flow path. In a method according to the invention, the temperature of a flowing fluid is altered at a selected location for a selected duration so as to generate a pulse in the fluid moving in a downstream direction along a flow path, and the fluid is monitored at a sensing region to detect the pulse passing therethrough. An apparatus according to the present invention may comprise a conduit, a sensor element disposed therein, an energy source proximate to the conduit, and a controller operative to generate an on signal and an off signal respectively operative to activate and deactivate the energy source. The present invention also relates to a liquid chromatography device having a fluid flow detecting and measuring apparatus according to the present invention.

Abstract: Disclosed is a method for preparing a thermal pulsed micro flow sensor comprising determining positions to allocate a plurality of thermal sensors along a microchannel, relatively to a heater positioned in said microchannel, and positioning said thermal sensors at the determined positions, respectively.

Abstract: A flow meter enables a time-of-flight method for non-invasively measuring liquid flow in a fluid conduit. The flow meter comprises a perturbing element in the form of a phase changing device, a heat transfer device, an electrochemical perturbing device or a photochemical perturbing device, and a conductivity detection device spaced downstream from the perturbing element. The perturbing element is applied to a small section of the conduit to cause a perturbation in a portion of the liquid flowing therethrough. This perturbation causes a change in conductivity a liquid plug, and the affected liquid plug continuous to flow in the fluid conduit toward the conductivity detection device. The conductivity detection device then senses the change in conductivity resulting from the perturbation, and flow rate or velocity is determined from the time of detection and the distance between the point of perturbation and the point of conductivity change detection.

Abstract: A contactless, resistive heating device applies heat energy non-invasively to a target zone of liquid contained by a non-conductive substrate or capillary. The heating device supplies an AC signal to two spaced-apart electrodes, which are disposed externally of the substrate. A circuit is established in which the source of the AC signal is capacitively coupled with the liquid through each electrode. The zone of liquid between the electrodes is heated due to the resulting flow of electrical current across the zone.

Abstract: A system and method for measuring flow rate within a fluid-bearing passageway include introducing heat fluctuations into the flow and then non-invasively monitoring the effects of the heat fluctuations propagating to or from one or more interrogation regions. In one embodiment, the non-invasive monitoring detects fluctuations in the refractive index of the flowing fluid as a result of variations in the temperature of the fluid. In another embodiment, electrical conductivity of the fluid is monitored. The heat fluctuations may be introduced using an optical heat generator, such as an infrared laser, or may be introduced using an electrical member, such as a heater coil. Determining the refractive index along the interrogation region may be achieved by monitoring characteristics on an interference pattern, but other optical arrangements may be utilized.

Abstract: When a bolus dose of cold saline is injected into a catheter where a wire, carrying a sensor unit and electrical leads for signal transmission, is located, the lead resistance is affected by the cold saline thereby altering the resistivity. However, by countering this effect and measuring the change needed to affect this countermeasure, a resistance variation curve can be generated. An accurate starting point for the determination of a transit time can be derived from the curve. Using conventional flow measurement calculations with the accurate starting point yields a better understanding of the flow profile in an artery based on the transit time.

Abstract: A thermal pulsed micro flow sensor includes thermal sensors positioned in a fluid channel at downstream positions relative to a heater. Flow rate is measured by determining the time that it takes a thermal pulse to pass between two of the sensors. Since the resolution of the measurement increases with increasing distance between sensors while the accuracy of the measurement decreases, there is a conflict between the requirements of accuracy and short response time, as well as between accuracy and resolution. By providing at least three sensors and by varying the distances between the sensors, however, it is possible to select a pair of sensors having the highest resolution required by the application in which the sensor is used, while still ensuring that the velocity measurement is within the range of velocities accurately measurable by the selected sensors.

Abstract: Gasmeter for determining a flow rate of gas within a channel is provided. The gasmeter includes a channel for passing through it a flow of gas along a first sensor and a chamber which is arranged for receiving and containing at substantially stand still gas from the channel and in which a second sensor is arranged. The sensors are heated during heating periods and subsequently let cooled down in cooling periods. The cooling rate of the sensors is determined and are used to calculate a value of the flow rate through the channel which is compensated for change of density of the gas.