An apparatus for calculating a thermal conductivity of a gaseous substance is provided. The apparatus includes a substrate; a cover member disposed on the substrate, wherein the cover member comprises a flow tunnel for the gaseous substance; a flow sensing element disposed on the substrate, wherein the flow sensing element is exposed to the gaseous substance in the flow tunnel; and a pressure sensing element disposed on the substrate, wherein the pressure sensing element is exposed to the gaseous substance in the flow tunnel.

Provided herein are negative air pressure devices and uses thereof. In particular, provided herein are negative air pressure devices that modulate CO.sup.2 delivery for use in the treatment of sleep apnea.

A quantity of gas is introduced into a gas reservoir via a filling station provided with a filling line. The quantity is measured. A signal is generated indicating a corrected quantity of transferred gas. The signal is obtained by adding a predetermined, positive or negative, corrective amount to the measured quantity of gas transferred.

It is possible to reduce a degradation in accuracy after switching of a heating state or after change of the flow rate.

A physical quantity detection device includes a flow rate measuring element which is equipped with a heating element and measures a flow rate of a measurement target fluid; a heating element control unit which switches a control state of the heating element to one of a heat generation state or a heat generation suppression state; and a signal processing unit which includes a buffer and a frequency analysis block, and processes a measured value of the flow rate measuring element, using a main frequency calculated by the frequency analysis block, in which the measured value for a past predetermined period is recorded in the buffer, the frequency analysis block calculates the main frequency by performing a frequency analysis of the measured value recorded in the buffer, when an occurrence of an event is detected, the signal processing unit performs a calculation, using the main frequency calculated immediately before for a predetermined period from the occurrence of the event, and the event is a sudden change in the measured value and switching of the control state performed by the heating element control unit.

An anesthetic dispensing device (100) includes a measuring unit (150) for determining an anesthetic concentration in an area of an outlet (142) of the anesthetic dispensing device. The measuring unit is configured to measure a first parameter (154) of a gas concentration-dependent characteristic between a mixer unit (140) and a second parameter (155) of the gas concentration-dependent characteristic in a second gas branch (120) or in an area of a breathing gas feed (112) of the anesthetic dispensing device by at least one sensor element (152). The measuring unit is further configured to determine the anesthetic concentration between the mixer unit and the outlet and to output a corresponding concentration signal (160) as a function of calibration information assigned to the second parameter and of the first parameter.

In some examples, a system includes an airflow sensor disposed at least partially within an air intake system for an engine. The airflow sensor may be configured to measure a flow rate of air flowing past the airflow sensor in the air intake system, and includes a sensor element and a heater associated with the sensor element. A heater control circuit may control the heater to control a temperature of the sensor element. Further, a processor may be configured by executable instructions to cause the heater control circuit to, in a first operation mode, maintain the sensor element at a higher temperature range, and, in a second operation mode, maintain the sensor element at a lower temperature range that is above an ambient temperature and that is lower than the higher temperature range.

A measurement control device measures an air flow rate using an output value of a sensing portion that outputs a signal according to the air flow rate, and outputs the measurement result of the air flow rate to a predetermined external device. The measurement control device includes: a pulsation state calculator that calculates a pulsation state, which is a state of pulsation generated in the air flow rate, by using the output value of the sensing portion instead of acquiring an output value from an external device; and a flow rate correcting unit that corrects the air flow rate using the pulsation state calculated by the pulsation state calculator.

The disclosure relates to a sensor apparatus and a method for measuring the flow rate of a shielding gas in a welding apparatus. The sensor apparatus comprises at least one inlet and at least one outlet in fluid connection with one or more bypass channels and with one or more sensor channels, and at least one input hose and one output hose. The apparatus also comprises one or more thermal mass flow sensors connected to the one or more sensor channels, and a control unit configured to retrieve sensor responses from the one or more thermal mass flow sensors and to determine the flow rate of the shielding gas through the sensor apparatus based on the retrieved sensor response and calibration data, wherein the calibration data comprises one or more characteristic curves comprising gas flow values and sensor response values. The control unit is configured to retrieve from a memory unit: the composition of the shielding gas; the number of active thermodynamic degrees of freedom which the molecules of each gas component in the shielding gas possess at the retrieved shielding gas temperature; a characteristic curve for each gas component separately, which consists of sensor response data as a function of gas flow rate, measured in a calibration experiment conducted with a pure gas consisting only of that gas component. The control unit is configured to calculate a new, mixture-specific characteristic curve for the gas mixture as a weighted average of the pure-gas characteristic curves, wherein the weight assigned to each value on a pure-gas characteristic curve is a product of the concentration percentage of that gas component in the shielding gas mixture and the number of active thermodynamic degrees of freedom which the molecules of that gas component possess at the retrieved shielding gas temperature; and to use the mixture-specific characteristic curve as the characteristic curve for the shielding gas mixture by retrieving from this characteristic curve the calibration gas flow rate which corresponds most closely to the retrieved new sensor response; and to identify this flow rate as the current flow rate of the shielding gas through the sensor apparatus. The sensor apparatus also comprises a display unit configured to display the determined flow rate of the shielding gas to a user and/or a memory unit for storing the determined flow rate of the shielding gas.

In a measurement control device that measures an airflow, an amplitude calculator calculates, by use of an output value of a sensor, a pulsation amplitude that is a difference between a pulsation maximum and an average airflow or a difference between the pulsation maximum and a pulsation minimum. The pulsation maximum is a maximum value of pulsation generated in the airflow, the average airflow is an average value of the pulsation, and the pulsation minimum is a minimum value of the pulsation. A correction parameter acquirer acquires a correction parameter corresponding to the calculated pulsation amplitude by use of a correction characteristic. An airflow corrector corrects the airflow by use of the acquired correction parameter.

In some examples, a system includes an airflow sensor disposed at least partially within an air intake system for an engine. The airflow sensor may be configured to measure a flow rate of air flowing past the airflow sensor in the air intake system, and includes a sensor element and a heater associated with the sensor element. A heater control circuit may control the heater to control a temperature of the sensor element. Further, a processor may be configured by executable instructions to cause the heater control circuit to, in a first operation mode, maintain the sensor element at a higher temperature range, and, in a second operation mode, maintain the sensor element at a lower temperature range that is above an ambient temperature and that is lower than the higher temperature range.