An environmental condition may be measured with a sensor (10) including a wire (20) having an ultrasonic signal transmission characteristic that varies in response to the environmental condition by sensing ultrasonic energy propagated through the wire using multiple types of propagation, and separating an effect of temperature on the wire from an effect of strain on the wire using the sensed ultrasonic energy propagated through the wire using the multiple types of propagation. A positive feedback loop may be used to excite the wire such that strain in the wire is based upon a sensed resonant frequency, while a square wave with a controlled duty cycle may be used to excite the wire at multiple excitation frequencies. A phase matched cone (200, 210) may be used to couple ultrasonic energy between a waveguide wire (202, 212) and a transducer (204, 214).

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

An air contaminant collector device for use in an aircraft air contaminant analyzer, and a method for its use, are disclosed.

A method and an aircraft air contaminant analyzer for determining and classifying by type aircraft air contaminants, providing a first sample flow path and second sample flow path, are disclosed.

A method and an aircraft air contaminant analyzer for determining and classifying by type aircraft air contaminants, providing a sample flow path and bypass flow path bypassing the sample flow path, are disclosed.

Acoustic wave sensors comprise: a piezoelectric layer, first and second electrodes arranged with the piezoelectric layer in a piezoelectric transducer circuit; and a polymeric sensing layer for adsorbing a gas-phase analyte, the adsorption of which analyte causes a change in resonant frequency of the piezoelectric transducer circuit, wherein the polymeric sensing layer comprises: (a) a polymer chosen from substituted or unsubstituted: polyarylenes comprising the reaction product of monomers comprising a first monomer comprising an aromatic acetylene group and a second monomer comprising a cyclopentadienone group; polyamides; polypyrazoles; or novolacs; or a cured product thereof; (b) a polymer chosen from substituted or unsubstituted: polyamic acids; or polyamic acid-polyimide copolymers; (c) a polymer formed from one or more monomers comprising a monomer comprising a polar group-substituted arylcyclobutene group, or a cured product thereof; or (d) a polymer comprising polymerized units of a monomer chosen from substituted or unsubstituted: maleimides; or norbomenes; or a cured product thereof. The acoustic wave sensors and methods of using such sensors find particular applicability in the sensing of gas-phase analytes.

A method for determining properties of a hydrocarbon containing gas mixture, especially natural gas or biogas, comprising: allowing the gas mixture to flow through a measuring arrangement; determining a pressure- and temperature dependent viscosity measured value, an associated measured value of temperature and an associated pressure measured value of the flowing gas mixture; ascertaining a first value of a first variable, which characterizes the energy content of the flowing gas mixture, based on viscosity measured value, the associated measured value of temperature, and the associated pressure measured value, wherein the first variable characterizing the energy content is the Wobbe index or the calorific value of the flowing gas mixture, wherein the Wobbe index is preferable.

The present invention provides a nanomechanical sensor in which a negative influence of water in a sample on measurement is suppressed. In an embodiment of the present invention, as a receptor material of the nanomechanical sensor, a low-hygroscopic material such as polysulfone, polycaprolactone, poly(vinylidene fluoride), or poly(4-methylstyrene) is used. According to this embodiment, a negative influence, such as saturation of a receptor layer by water in the sample, or masking of an output signal based on trace components by an output signal based on water contained in the sample in a large amount, can be suppressed.

An apparatus and method for detection of methane in an environment, including a housing with a sensor printed circuit board and a processor printed circuit board interconnected to and thermally insulated from the sensor printed circuit board. The sensor printed circuit board includes a first tuning fork isolated from the environment, and a second tuning fork exposed to the environment. The tuning forks are attached to opposite sides of the sensor printed circuit board. The processor printed circuit board includes processing circuitry interconnected to the first tuning fork and the second tuning fork, which receives vibration frequency signals therefrom, and is programmed to determine a frequency difference between the frequency of vibration of the first tuning fork and the frequency vibration of the second tuning fork, and if the frequency difference is greater than a predetermined threshold, then setting an alarm to indicate the presence of methane.

A collimated beam (23) of a surface acoustic wave propagates on a piezoelectric substrate (22) while passing through sensitive film (25) to adsorb a sensing gas. Signal processing unit (40) transmits an exciting burst signal to sensor electrode (24) to excite the collimated beam (23), receives first and second returned burst signals after the collimated beam (23) has propagated, and calculates a target gas parameter by a target leakage factor of the background gas and a relation between reference gas parameters and reference leakage factors of reference gases, the leakage factor is provided by first and second attenuations of the first and second returned burst signals, respectively, using waveform data of the first and second returned burst signals.