Abstract: A distributed monitoring and analytics system is configured to automatically monitor conditions in a remote oil field. The distributed monitoring and analytics system generally includes one or more mobile monitoring units that each includes a vehicle, a sensor package within the vehicle that is configured to produce one or more sensor outputs as the mobile monitoring unit traverses the remote oil field, and an onboard computer configured to process the output from the sensor package. The sensor package can include any number of sensors, including a camera that outputs a video signal for computer vision analysis and a gas detector that outputs a gas detection signal based on the detection of fugitive gas emissions within the remote oil field.

Abstract: Systems, devices, and methods including: an optical gas imaging (OGI) camera; a processor in communication with the OGI camera, the processor configured to: capture at least two images of a scene with the camera; compare the captured at least two images to determine at least one of: a motion associated with a movement of the camera and a motion associated with a movement of a gas plume; apply a color to each pixel of the captured images based on at least one of: a direction of movement and a velocity of movement between the at least two captured images; subtract pixels from the colored pixels associated with the movement of the camera; and generate an image of an output of a gas plume based on the subtracted pixels and the applied color pixels.

Abstract: Systems, devices, and methods for receiving, by a ground control station (GCS) having a processor with addressable memory, a plurality of point source gas concentration measurements; receiving, by the GCS, a meteorological data corresponding to each point source concentration gas measurement; determining, by the GCS, if each point source gas concentration measurement is an elevated ambient gas concentration; generating, by the GCS, a back trajectory for each elevated ambient gas concentration; storing, by the GCS, the position of each generated back trajectory in a grid; determining, by the GCS, a probability of a gas source location corresponding to the stored positions in the grid; and generating, by the GCS, an overlay showing the probability of the gas source location.

Abstract: A sensor discriminator for detecting a gaseous substance includes a power source, a discrimination module, a sensor simulator that simulates a metal organic framework under at least one simulation condition, a simulation circuitry electrically coupling the sensor simulator to the power source and the discrimination module, and a discriminator circuitry that electrically couples the power source and the discrimination module to a gas capture probe. The discrimination module compares a discrimination pulse and a simulation pulse from the power source after the discrimination pulse passes through a metal organic framework of the gas capture sensor and the simulation pulse passes through a simulation component of the sensor simulator. The discrimination module causes a discriminator output that includes the comparison of the discrimination pulse to the simulation pulse.

Abstract: Embodiments of the invention are directed to collecting, by a computer system, sensor data of a manufacturing system, the sensor data being measured at intervals smaller than a time interval of a target measurement of the manufacturing system. The sensor data is determined to have a relationship to the target measurement. A synthetic target measurement is generated at an interval smaller than the time interval based on the relationship. An advance warning is automatically generated for the target measurement based on the synthetic target measurement within the interval smaller than the time interval.

Abstract: A sensing device configured to monitor a battery pack is disclosed. The sensing device may include a plurality of carbon-based sensors enclosed within the battery pack. Each sensor coupled may be between a corresponding pair of electrodes, and may include a plurality of 3D graphene-based sensing materials. In some instances, the 3D graphene-based sensing materials of a first sensor may be functionalized with a first material configured to detect a presence of each analyte of a first group of analytes, and the 3D graphene-based sensing materials of a second sensor may be functionalized with a second material configured to detect a presence of each analyte of a second group of analytes.

Abstract: A method for evaluating signals of a sensor unit including at least two sensors. The method includes reading in a first sensor value of a first of the sensors and a second sensor value of a second sensor, the first and second sensor value each representing one parameter of a substance to be measured by the sensors or a linking of the parameters. A threshold value range is read in, which maps a range of combinations of at least the first and second sensor values, which represents the presence or a value of the substance to be measured in surroundings of the first and second sensors. A combination of the read-in first and second sensor values is recognized as being outside the threshold value range. The threshold value range is changed into a changed threshold value range so that the combination is situated within the changed threshold value range.

Abstract: An apparatus and method for determining a temperature in a system having an object, an optical sensor, and a gas flow passing between the object and the optical sensor, sensing, with the optical sensor, a wavelength emitted from the object and indicative of an attenuation, sensing, with the optical sensor, a wavelength emitted from the object and indicative of a temperature of at least one of the object or the gas; and calculating a temperature of the gas using the wavelengths.

Abstract: A method for generating a graph data structure comprises receiving, by one or more processors, data associated with a building, generating one or more space nodes in the graph data structure corresponding to spaces within the building based on the data, generating one or more asset nodes in the graph data structure corresponding to assets within the building based on the data, associating sensor data with the one or more asset nodes based on the data, classifying the sensor data based on the data, and generating a relationship between at least two of the one or more space nodes, the one or more asset nodes, and the classified sensor data.

Abstract: A system and method for measuring the greenhouse gas emitting activities of a user is described. Data for different sources of greenhouse gas emitting user activities, including electricity usage, motor vehicle usage, food consumption, and flight usage, are gathered, normalized, weighted, and presented. The system and method include providing the user with feedback regarding these activities and rewarding the user for changing these activities to thereby reduce their greenhouse gas emissions.

Abstract: The present invention discloses a method and system for protecting the operation of a train under an air pollution environment.

Abstract: An optical concentration measurement device includes an LED light source, alight receiving unit having a rectangular light receiving surface and outputting a detection signal representing intensity of received light, and light guiding units guiding light emitted by the LED light source to the light receiving unit, wherein a shape on the rectangular light receiving surface of light radiated on the light receiving surface is rectangular, the optical concentration measurement device measures concentration of an object to be measured existing in a light path formed by the light guiding units, based on the detection signal output from the light receiving unit, and the light guiding units guide light at a diffraction limit or greater in such a way that area of the light on the rectangular light receiving surface is ½ or less of area of the rectangular light receiving surface.

Abstract: Methods and systems for performing pest infestation forewarning are described. In one embodiment, intuition based forewarning method includes collecting and storing core data and surroundings data, wherein the core data includes parameters describing a system and ring data includes parameters describing surroundings of grain storage container-based (e.g., silo-based) environments. The collected core data and ring data are analyzed to determine one or more changing situations of the storage container-based (e.g., silo-based) environments. A system forewarning is generated based on the changing situations that are observed.

Abstract: Various embodiments disclosed herein describe an infrared (IR) imaging system for detecting a gas. The imaging system can include an optical filter that selectively passes light having a wavelength in a range of 1585 nm to 1595 nm while attenuating light at wavelengths above 1600 nm and below 1580 nm. The system can include an optical detector array sensitive to light having a wavelength of 1590 that is positioned rear of the optical filter.

Abstract: Techniques and apparatus for diagnostic processes for analytical instruments are described. In one embodiment, for example, an apparatus may include at least one memory, and logic coupled to the at least one memory. The logic may be configured to receive diagnostic information associated with at least one analytical instrument, and process the diagnostic information using a computational model to generate at least one diagnostic model for at least one diagnostic. Other embodiments are described.

Abstract: A method for monitoring a gas sensor (14) which comprises two electrochemical measuring cells (20, 30) and which is arranged in an exhaust tract (10) of an internal combustion engine (11), wherein the sensor elements (20, 30) exhibit a substantially identical sensitivity towards a first gas component and a different sensitivity towards a second gas component and are insensitive towards further gas components. In an operating state in which an exhaust gas stream at the gas sensor (14) contains less of the second gas component than of the first gas component a concentration of the first gas component is calculated from each of the sensor signals from the sensor elements (20, 30) and a defect in a sensor element (20, 30) is deduced from the concentrations of the first gas component.

Abstract: In an approach to archive a digital twin in response to a determination to decommission its associated physical asset, a processor monitors for data sent from an Internet of Things (IoT) sensor associated in the physical asset. A processor determines that a pre-configured threshold is met. A processor reviews a digital twin agreement for the digital twin. A processor archives the digital twin.

Abstract: An embodiment of a system for measuring trace gas concentration is described that comprises a laser absorption spectrometer configured to detect an absorbance measure from a trace gas, as well as a temperature value and a pressure value that correspond to an environment in a gas cell; and a computer having executable code stored thereon configured to perform a method comprising: receiving the absorbance value, the temperature value, and the pressure value; defining a fitting range associated with the trace gas; applying a curve fitting model in the fitting range to the absorbance value using the temperature value and the pressure value as model parameters; and producing a concentration measure of the trace gas.

Abstract: An integrated method for assessing metabolic rate and maintaining indoor air quality and efficient ventilation energy use. A physical sensor assesses room occupancy. An actuated ventilation system is set to a constant CO2 level in a predetermined healthy range, where the actuated ventilation system includes a CO2 sensor. The actuated ventilation system sets a first air ventilation rate and the sensor measures a first CO2 level. The system determines whether CO2 level is in a healthy range, if not then the CO2 level is adjusted by setting a subsequent air ventilation rate. A subsequent CO2 level is measured. If the CO2 level is determined to meet a predetermined healthy range, then an assessment of change of air ventilation rate (? ACH) is determined. The determination of air change rate can be further augmented by a physical pressure based measurement. The overall metabolic rate is generated.

Abstract: A method for determining a transformer state on the basis of correction of dissolved gas data includes receiving, by a transformer state determination apparatus, dissolved gas data, determining, by the transformer state determination apparatus, a measurement error value which is a correction target in the dissolved gas data, correcting, by the transformer state determination apparatus, the measurement error value, and determining, by the transformer state determination apparatus, a transformer state on the basis of the dissolved gas data including the corrected measurement error value.

Abstract: Methods and systems for monitoring a flare burner with a camera. The methods and systems which may indicate to operators the presence or absence of one or more of smoke, flare flame, and steam plume and record those indications or measurements. Additionally, the methods and systems may confirm whether compliance with local regulations on visual emissions, smoke plume is achieved. The methods and systems automatically adjust the delivery rate of key inputs including measures assist fuel gas, purge gas, steam and/or air simultaneously to maintain or attain compliance with said local regulatory requirements. Also, methods for a machine learning process for using controller inputs to identify normal and abnormal flare states and provide visual indications and flare operation recommendations.

Abstract: Embodiments of the present invention provide apparatus, systems and methods for measuring dissociation of a process gas generated by a RPS. In one embodiment, a method of measuring dissociation of a process gas includes receiving a process gas from a RPS, the process gas including a polyatomic molecule that dissociates into at least one free radical. The method further includes irradiating the process gas with IR radiation at one or more wavelengths, detecting the IR radiation that passes through the process gas, and determining a degree of dissociation of the polyatomic molecule in the process gas based, at least in part, on the detected IR radiation. In one embodiment, the method further comprises modifying one or more settings of the RPS, based, at least in part, on the determined degree of dissociation.

Abstract: The invention provides a gas detection system and a method with eliminating influence of ambient temperature and humidity change, the gas detection system comprises a bare sensor, a reference sensor and a calculation module; the bare sensor is used to detect a target gas in an ambient gas to obtain a first feedback signal; the reference sensor is used to selectively isolate the target gas in the ambient gas to produce a zero gas and to detect the zero gas to obtain a second feedback signal, the calculation module is used to calculate a difference between the first feedback signal and the second feedback signal to obtain a third feedback signal, and to obtain a target gas concentration by calculating the third feedback signal according to a calibration formula. The invention improves the measurement accuracy to the target gas concentration, which are efficient and reliable and have good technical effects.

Abstract: A refrigerator includes a temperature sensor; a door sensor; a compressor sensor; an ice sensor; a water sensor; and a defrost sensor. The refrigerator also includes a communication unit; a display unit; at least one processor; and at least one memory connected to the at least one processor and storing instructions that, when executed, perform operations including: sensing, through the plurality of sensors, sensing information related to the refrigerator; storing, in the at least one computer memory, (i) the sensing information, and (ii) time information; transmitting to at least one server, (i) the sensing information and the time information, and (ii) setting information for the refrigerating compartment or the freezer compartment; receiving information regarding an abnormal state of the refrigerator that is generated by a cloud server or a monitoring server based on the sensing information; and outputting display information related to the received information regarding the abnormal state.

Abstract: In order to enable concentrations of components to be measured to be accurately calculated even when higher boiling compounds are contained in a test gas, a gas analysis device that analyzes components to be measured that are contained in a test gas using a light spectrum obtained by irradiating light onto the test gas is provided with a calibration curve data storage section in which is stored first calibration curve data in which effects on concentrations of the components to be measured from higher boiling compounds whose boiling point is higher than a heating temperature of an analyzer into which the test gas has been introduced have been corrected, and with a concentration calculation section that calculates concentrations of components to be measured using the first calibration curve data.

Abstract: Naturally-occurring, electromagnetic signals generated by interaction of solar wind with earth's magnetosphere adjacent a borehole are measured by an electromagnetic sensor positioned adjacent the borehole in the hydrocarbon-bearing formation. Electromagnetic signals generated within the borehole are measured over a period of time by a borehole sensor positioned within the borehole. The electromagnetic signals change over the period of time due to variations in fluid distributions within the hydrocarbon-bearing formation. Electromagnetic changes to the electromagnetic signals generated within the borehole and to the passive, naturally-occurring electromagnetic signals over the period of time are determined by one or more processors. A computational model of the hydrocarbon-bearing formation is generated based in part on the electromagnetic changes.

Abstract: A method for monitoring intoxication of a user, the method including: receiving a set of samples from a body region of a user; generating an intoxication metric based on the set of samples; and providing a notification to the user based on the intoxication metric. The method can additionally or alternatively include: modifying operation of the transdermal alcohol sensing device based on the intoxication metric; determining contextual data; maintaining a hydration level of the transdermal alcohol sensing device; and any other suitable processes. A system for monitoring intoxication of a user including a sensor and a housing. The system can additionally or alternatively include any or all of: an inlet, a fastener, an electronics subsystem, a user device, and/or any other suitable component.

Abstract: A method monitors gases produced in an insulating medium circuit. The insulating medium circuit is in contact with a transition resistor of an on-load tap-changer. The method includes: ascertaining a time profile of a resistor temperature of the transition resistor during a loading time period; and determining at least one characteristic value for characterizing the gases produced based upon the time profile of the resistor temperature.

Abstract: Methods and apparatus for asset management are provided. The apparatus, for example, a processor to receive an input including intervention information for a first plurality of assets in a first circuit and for a second plurality of assets in a second circuit in a network; create a first plurality of bundling strategies for interventions to be performed for the first plurality of assets in the first circuit and create a second plurality of bundling strategies for interventions to be performed for the second plurality of assets in the second circuit; calculate for a created first plurality of bundling strategies and a created second plurality of bundling strategies at least one of an outage duration and cost associated with the interventions; and create a schedule for performing interventions for the first plurality of assets in the first circuit and the second plurality of assets in the second circuit.

Abstract: An apparatus for analysis of metals is provided. The apparatus includes a molding cavity for receiving a sample of a molten metal, a gating system for allowing the molten metal to be poured, and a vent for allowing gases to escape from the apparatus when the molten metal is poured. The apparatus further includes at least one chill plate, adjacent to the molding cavity, for enabling faster cooling and solidification of the sample of the molten metal. The apparatus also includes a longitudinal slot, extending from the molding cavity, for allowing a sensor element to be introduced into the sample of the molten metal, the sensor element is a thermocouple wire that is used to monitor a cooling curve of the molten metal, while the molten metal solidifies.

Abstract: Systems and methods of selective driver coaching are provided. Driver coaching systems learn the characteristics of a deceleration event. With the goal of increasing recouped energy while operating a hybrid electric vehicle (HEV), driver coaching systems predict when the HEV can begin coasting at the start of the deceleration event. In this way, the amount of time during which regenerative braking can be applied may be increased. Coaching cues are provided to the driver so that the HEV can be operated in way that achieves the goal of increasing recouped energy. However, engaging in excessive regenerative breaking can negate its advantages if the amount needed to reaccelerate the HEV to a cruising/steady speed is too great. Selective driver coaching provides coaching cues only if the operating efficiency of the HEV exceeds the operating efficiency of the HEV when controlled by the driver without coaching cues.

Abstract: A process for identifying an unknown compound in a sample includes matching a peak in a primary Fourier Transform Infrared spectral region of the sample spectrum with reference spectra in the same spectral region to generate an initial list of potential candidates, based, for example on goodness of fit criteria. The initial list can be reduced by retention time information and/or global peak matching techniques that analyze the sample spectrum in regions outside the primary region.

Abstract: An absorption spectroscopic system is provided with a detector that detects an intensity of light transmitted through a gas, a total pressure sensor that measures a total pressure of the gas, an interference gas partial pressure-absorbance relationship storage unit that stores interference gas partial pressure-absorbance relationship data, an interference gas partial pressure estimation unit that estimates the partial pressure of the interference gas based on the total pressure measured by the total pressure sensor, an interference gas absorbance conversion unit that converts an estimated partial pressure of the interference gas estimated by the interference gas partial pressure estimation unit into an absorbance of the interference gas based on the interference gas partial pressure-absorbance relationship data, and a target gas absorbance calculation unit that calculates an absorbance of the target gas based on output values from the detector and on the absorbance of the interference gas.

Abstract: Techniques for implementing and/or operating a pipeline system including a pipe segment, in which the pipe segment includes tubing that defines a pipe bore and fluid conduits in a tubing annulus, a pipe fitting secured to the pipe segment, in which the pipe fitting includes a vent port connected to the fluid conduits in the tubing annulus, and a testing apparatus. The testing apparatus includes a fluid valve connected to the vent port, an upstream sensor fluidly connected between the vent port and the fluid valve, in which the upstream sensor determines a fluid parameter associated with fluid within the fluid conduits in the tubing annulus, and a downstream sensor connected between the fluid valve and external environmental conditions, in which the downstream sensor determines another fluid parameter associated with fluid released from the fluid conduits in the tubing annulus while the fluid valve is in an opened state.

Abstract: An exhaust purification system of an internal combustion engine comprises a filter 23 arranged in an exhaust passage 23 of an internal combustion engine in which a plurality of cylinders 61, 62, 63, 64 cooled by cooling water are provided and trapping particulate matter in exhaust gas, a wall temperature calculation part 51 configured to calculate or detect wall temperatures of a predetermined number of equal to or more than two cylinders among the plurality of cylinders, and a PM amount calculation part 52 configured to calculate an amount of particulate matter discharged from the plurality of cylinders to the exhaust passage based on the wall temperatures calculated or detected by the wall temperature calculation part.

Abstract: A gas detecting device includes a casing, at least one gas transporting actuator, at least one valve and at least one external sensor. The casing has an airflow chamber, an inlet, a branch channel and a connection channel. The airflow chamber communicates with the exterior of the casing through the inlet, and the branch channel communicates with the airflow chamber and the connection channel. The gas transporting actuator is disposed within the branch channel for transporting air into the airflow chamber and the branch channel from the inlet. The valve is disposed between the connection channel and the branch channel for controlling the air to flow into the connection channel. The external sensor is detachably disposed within the connection channel and has a sensor for measuring the air in the connection channel.

Abstract: A detection system includes at least one sensor configured to measure a presence of airborne particles and at least one amplifier circuit in communication with the at least one sensor. The amplifier circuit is configured to monitor a charge generated by the at least one sensor over a time interval. The system further includes a controller configured to monitor the charge accumulated in the at least one amplifier circuit from the at least one sensor at the time interval. In response to the charge of the at least one amplifier circuit, the controller detects the presence of the airborne particles.

Abstract: A gas analysis apparatus includes a calibration curve data storage section designed to store N types of calibration curve data which are previously created for N types of measurement target components and obtained by correcting influences of other N?1 types of measurement target components with respect to a concentration of each of the measurement target components, and a concentration calculation section designed to calculate a concentration of each of the measurement target components by using the N types of calibration curve data. When there exists a subthreshold component whose concentration calculated by the concentration calculation section is not more than a predetermined threshold value, the concentration calculation section calculates a concentration of each of the measurement target components other than the subthreshold component by using calibration curve data obtained without correcting an influence of the subthreshold component.

Abstract: An extreme ultraviolet light generation apparatus may include: a chamber device including an internal space; a target supply unit disposed at the chamber device and configured to supply a droplet of a target substance to the internal space; a target collection unit disposed at the chamber device, communicated with the internal space through an opening provided to an inner wall of the chamber device, and configured to collect the droplet passing through the opening; a detection unit disposed at the chamber device and configured to detect the target substance accumulating in the vicinity of the opening of the inner wall; and a control unit configured to stop the target supply unit depending on a result of the detection by the detection unit.

Abstract: An on-chip spectroscopic sensor includes a tunable diode laser. A laser driver for drives the tunable diode laser. An analyte test cavity receives a chemical sample and exposes the received chemical sample to light from the tunable diode laser. An optical detector detects light emerging from the analyte test cavity as a result of the laser exposure. A spectral analyzer determines a spectrum of the emerging light, matches and removes one or more known optical fringe patterns from the determined spectrum, and determines a composition or concentration of the chemical sample from the optical fringe pattern-removed spectrum.

Abstract: In some embodiments, data from a vehicle-borne gas leak detection survey are used to generate an aggregate leak indication search area (LISA) indicator for a plurality of leak indications (measurement peaks) characterizing a single leak or localized set of leaks. A clustering algorithm (e.g. Markov, DBScan) may be used to group a set of indications into a cluster characterizing the leak. Leak indications may be pre-filtered for quality control before assignment to a cluster according to a number of parameters including background gas level, inter-peak distance, peak shape, wind speed, wind direction and/or variability, vehicle speed and/or acceleration, and/or a lower detection threshold for leak flow rate.

Abstract: Systems and methods for reducing contamination on reflective mirrors disposed on chamber walls in a millisecond anneal system are provided. In one example implementation, the reflective mirrors can be heated by one or more of (1) heating the fluid in the closed fluid system for regulating the temperature of the reflective mirrors; (2) electrical cartridge heater(s) or heater ribbon(s) attached to the reflective mirrors; and/or (3) use of lamp light inside the chamber.

Abstract: A method includes providing a length of pipeline that has a housing defining a central bore extending the length of the pipe and a space formed within the housing and extending the length of the pipe. At least one condition within the space is continuously monitored within the space to detect in real time if a change in the housing occurs.

Abstract: A medical vaporizer is provided. In one embodiment, dual-purpose sensors are employed, such as in a configuration in which one is positioned in the mixed gas flow channel and one is positioned in the main gas flow channel. The sensors provide measurements that may be used to determine both gas flow and gas concentration in the mixed and main gas channels, even when the identity and/or properties of the gas in the main gas channel are unknown. The measurements derived from the dual-purpose sensors may be used to measure and report the total anesthetic being delivered at the vaporizer output and/or improve vaporizer accuracy.

Abstract: The present disclosure is directed to a gas sensor device that detects gases with large molecules (e.g., a gas with a molecular weight between 150 g/mol and 450 g/mol), such as siloxanes. The gas sensor device includes a thin film gas sensor and a bulk film gas sensor. The thin film gas sensor and the bulk film gas sensor each include a semiconductor metal oxide (SMO) film, a heater, and a temperature sensor. The SMO film of the thin film gas sensor is an thin film (e.g., between 90 nanometers and 110 nanometers thick), and the SMO film of the bulk film gas sensor is an thick film (e.g., between 5 micrometers and 20 micrometers thick). The gas sensor device detects gases with large molecules based on a variation between resistances of the SMO thin film and the SMO thick film.

Abstract: A gas detecting device includes a casing, at least one gas transporting actuator, at least one valve and at least one external sensor. The easing has an airflow chamber, an inlet, a branch channel and a connection channel. The airflow chamber communicates with an environment outside the casing through the inlet, and the branch channel communicates with the airflow chamber and the connection channel. The gas transporting actuator is disposed within the branch channel for transporting air into the airflow chamber and the branch channel from the inlet, and has a nozzle plate, a chamber frame, an actuator, an insulation frame and a conducting frame. The valve is disposed between the connection channel and the branch channel for controlling the air to flow into the connection channel. The external sensor is detachably disposed within the connection channel and has a sensor for measuring the air in the connection channel.

Abstract: The present invention is relative to a method of ring-down spectroscopy in saturated-absorption condition, for measuring a first concentration of a gas through a measurement of the spectrum of a molecular transition of said gas.

Abstract: A method of controlling hydrogen concentration of a fuel cell includes calculating hydrogen or nitrogen concentration of gas stored in a fuel tank; estimating hydrogen or nitrogen concentration at an anode of the fuel cell based on the calculated hydrogen or nitrogen concentration of the gas; and controlling a hydrogen supply unit based on the estimated hydrogen or nitrogen concentration at the anode such that the hydrogen or nitrogen concentration at the anode follows desired hydrogen concentration or desired nitrogen concentration.

Abstract: Method and device for the analysis of a gas sample; the method provides for the sample to be conveyed from an inlet along a feeding duct and from the feeding duct, divided into equal portions, along a plurality of passage channels and through a plurality of detecting stations; in the area of each detecting station a sensor is arranged, which detects a different characteristic of the sample; the gas sample portions are conveyed directly and precisely onto the sensors so as to increase the speed and sensitivity of the detection.

Abstract: A sensor element includes a NOx sensor part, a NH3 gas sensor part, and a single common electrode shared by the both parts. The former has a pump cell including a measurement electrode facing an internal space, a pump electrode formed on a surface of the element, and a solid electrolyte therebetween. The latter includes a sensing electrode formed on a surface of the element and having catalytic activity inactivated for a NH3 gas. The common electrode is located to be in contact with a reference gas. The NOx concentration is determined based on a potential difference occurring between the sensing electrode and the common electrode, and a current flowing through the pump cell in a state of controlling a voltage applied across the electrodes to maintain a potential difference between the measurement electrode and the common electrode constant.