A method of operating a sensor to detect an analyte in an environment, wherein the sensor includes a working electrode and circuitry in operative connection with the working electrode, includes performing a sensor interrogation cycle including applying electrical energy to the working electrode to generate a non-faradaic current, measuring a response to the generation of the non-faradaic current to determine a state of the sensor, and actively controlling the circuitry to dissipate the non-faradaic current.

An apparatus includes an aggregation circuit and a calibration circuit. The aggregation circuit is structured to interpret fuel data indicative of a fuel composition of a fuel provided by a fuel source from a plurality of gas quality sensors. Each gas quality sensor is associated with an individual engine system. Each engine system is positioned at a respective geographic location. The calibration circuit is structured to compare the fuel data received from each of the plurality of gas quality sensors that are located within a geographic area, determine a gas quality sensor miscalibration value for the plurality of gas quality sensors within the geographic area based on the fuel data received from each of the plurality of gas quality sensors within the geographic area, and remotely calibrate a miscalibrated gas quality sensor based on the gas quality sensor miscalibration value.

In a method for operating a portable electronic device comprising a chemical sensor, at least one reference reading is taken by the chemical sensor at least one predetermined point in time. At least one compensation value is determined based on at least one reference value wherein each reference value is derived from a result of a corresponding reference reading. A result of an operational reading of the chemical sensor is modified by the at least one compensation value.

The present invention provides devices and methods for the impregnation of air with the vapor or aerosol of a substance in a ‘controllable manner to enable the testing or training of detection means to evaluate and quantify the presence of the substance in an enclosed volume, and iη• particular to enable production of training aids and quality assurance test items for use in canine-olfaction based security screening.

The disclosure relates to a method of detecting a clot in a measurement chamber of a liquid sample analyzer, wherein the liquid sample analyzer comprises at least two analyte sensors, a first analyte sensor, for measuring a first analyte in a liquid sample, and one or more second analyte sensors, for measuring one or more second analytes in the liquid sample in the measurement chamber, the method comprising the steps of, (a) at least partly filling the measurement chamber with a known solution having a composition comprising the first analyte at a pre-determined level, and the second one or more analytes at pre-determined levels, (b) obtaining a first sequence of measurement results by the first analyte sensor, and simultaneously obtaining a second sequence of measurement results by the second, one or more analyte sensors, (c) determining a change of the first sequence of measurement results, (d) determining a change of the second or more sequence of measurement results, and (e) comparing the change of the first sequence of measurement results with the second sequence of measurement results.

A sensor system is for sensing a substance in a fluid (1), comprising a first sensor (10) and a second sensor (12) of the same type. The first sensor (10) is used until a calibration event, during which the second sensor (12) is used. The second sensor (12) is used only during the calibration event. The first sensor (10) is calibrated using the sensor information from the second sensor (12).

An apparatus for sampling landfill gas from a landfill flowing through a pipe. The apparatus may comprise: an enclosure configured to receive a section of the pipe; a gas sampling port in the section of the pipe; at least one sensor device disposed in a region of the enclosure, the at least one sensor being coupled to the section of the pipe through the gas sampling port; and thermal insulation positioned to retain heat from the section of the pipe in the region of the enclosure. A method of operating a landfill gas recovery system. The method may comprise: flowing gas from a well riser pipe through a sampling subsystem to a collection system; and heating a portion of the sampling subsystem with the gas flowing from the well riser pipe to the collection system.

A method for determining a calibrated measurement value for a concentration of the target gas comprises obtaining a measurement signal based on the concentration of the target gas. The method further comprises determining the calibrated measurement value based on the measurement signal and based on a calibration model. The calibration model is based on calibration data of a plurality of test sensor units having the same type as the sensor unit.

There is disclosed a method and system for determining the partial pressure of at least one gas in a mixture of gasses contained in a pressure vessel, the mixture being pressurised to a level which is above local atmospheric pressure. The method comprises the steps of positioning a gas analysis sensor (14) within a pressure vessel (10); exposing the sensor to the mixture of gasses at the pressure level found in the pressure vessel; operating the sensor to measure the actual partial pressure of the at least one gas in the mixture contained in the vessel; and periodically calibrating the sensor by directing a calibrating gas mixture (20, 22) to the sensor in the chamber, the calibrating gas mixture being breathable by a human being.

In order to allow an analyzer to be calibrated or a sampling channel to be purged without removing a sampling probe from a sampling location, provided are a sampling channel through which an exhaust gas from an internal combustion engine flows, an analyzer that is connected to the sampling channel and analyzes the exhaust gas, a diluter provided upstream of the analyzer in the sampling channel, a recirculated channel that branches from a branch point set between the analyzer and the diluter in the sampling channel and joins the diluter, a pump that is provided in the recirculated channel and guides part of the exhaust gas from the branch point to the diluter, an additional channel that is connected to the recirculated channel or the sampling channel and through which a calibration gas or a purge gas flows, and an opening and closing mechanism provided in the additional channel.