Methods for determining and classifying by type aircraft air contaminants, and aircraft air contaminant analyzers, are disclosed.

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.

A respiratory assistance apparatus has a gases inlet configured to receive a supply of gases, a blower unit configured to generate a pressurised gases stream from the supply of gases; a humidification unit configured to heat and humidify the pressurised gases stream; and a gases outlet for the heated and humidified gases stream. A flow path for the gases stream extends through the respiratory device from the gases inlet through the blower unit and humidification unit to the gases outlet. A sensor assembly is provided in the flow path before the humidification unit. The sensor assembly has an ultrasound gas composition sensor system for sensing one or more gas concentrations within the gases stream.

Systems and methods use sound waves for evaluating a fuel. The fuel supplied from a storage tank to an engine by a feed pipe can be evaluated by determining its properties based on the velocity of one or more sound waves in the fuel.

Methods and systems for determining concentrations of gases within a process chamber are provided. In one or more embodiments, a method includes introducing a first gas into a first cavity of a gas monitoring module, where the first cavity is thermally coupled to a second cavity of the gas monitoring module, and where the first cavity contains a first inlet and the first gas is introduced via the first inlet. The method includes introducing a gas mixture containing the first gas and a second gas into a second cavity, where the second cavity contains a second inlet and the gas mixture is introduced via the second inlet. The method also includes determining a first speed of sound inside the first cavity, determining a second speed of sound inside the second cavity, and determining a concentration of the second gas in the second cavity based on the first and second speeds of sound.

A method of measuring the transit time of an ultrasonic wave in a medium, by passing an ultrasonic wave pulse through a timing path in the medium, receiving the ultrasonic wave pulse at the exit of the timing path and comparing a first signal representative of the ultrasonic wave pulse on entry to the timing path with a second signal representative of the ultrasonic wave pulse received at the exit of the timing path. At least one cycle and associated zero-crossing point of the first signal is correlated with a corresponding cycle and zero-crossing point of the second signal, and the time interval is measured between the zero crossing points, in order to determine the transit time of the ultrasonic wave through the medium. The method is useful in a sensor for measuring gas composition, as well as bulk gas flow velocity. The sensor and method may be used in a dual channel apparatus for investigating vapour sorption by a substrate.

The teachings herein include methods for ascertaining a concentration (c.sub.A) of potentially infectious aerosol particles in a volume (V), for example in a conference room, methods for ascertaining an inhalation dose (Z), a device (200), a controller, and a display device. To improve the determination of a concentration (c.sub.A) of potentially infectious aerosol particles in a volume (V) with emitters (E1, . . . , En), the method may include: recording at least one time course of an acoustic variable (AS) in the volume (V), said variable being associated with one or more of the emitters (E1, . . . , En), ascertaining an emission (Q) of aerosol particles for at least one of the emitters (E1, . . . , En) on the basis of the recorded time course of the acoustic variable (AS) and ascertaining the concentration (c.sub.A) on the basis of the at least one emission (Q).

Disclosed are methods for determining and classifying aircraft air contaminants using contaminant analyzers comprising a contaminant collector comprising a membrane and a heater vaporizing captured contaminants; a gravimetric sensor generating a proportionate response when contaminant mass is added to or removed from the sensor, the sensor arranged to receive contaminants desorbed from the membrane when the membrane is heated; a frequency measurement device, measuring the response generated by the sensor as the contaminant is added to and removed from the sensor; a computer readable medium bearing a contaminant recognition program and calibration data; a processor executing the recognition program, the program including a module classifying contaminants by type, and a module using the calibration data for comparison with magnitude of the response generated by the sensor to calculate contaminant concentration; and, a pump, generating flow of aircraft air through the contaminant collector before and after the membrane is heated.

A gas analyzer uses continuous sonic signals through a conduit to determine the composition of a gas in the conduit. A transmitting transducer drives sonic signals at a fixed frequency and a second transducer receives the sonic signals. The phase shift between two signals corresponds to the speed of sound through the gas and is related to the composition of the gas. The electronic versions of these signals are processed by lowering, or dividing, the fixed frequency which expands the range of phase shift measurement and allows the determination of an expanded range for the gas composition. In an ozone generation system, the gas analyzer is highly suitable for determining the composition of gases derived from air as a gas of known composition and a calibration point.

A method of monitoring airflow along an airflow path includes measuring a speed or frequency of sound through air on the airflow path. A flow condition of the airflow as active or non-active is determined, based on a measured speed or frequency of sound through air on the airflow path. A presence of a flammable compound is also determined, based on a measured speed or frequency of sound through air on the airflow path. A combination sensor for gas composition flow includes a housing including an active flow inlet, an active flow outlet, and a measured flow path within the housing. First and second ultrasonic transceivers are configured to send and receive a sonic signal along a sonic pathway through the measured flow path. A plurality of diffusion openings in the housing are configured to provide operative molecular diffusion communication between outside of the housing and the sonic pathway.