A material evaluating device for an agricultural work machine comprising: a light source for illuminating one or more constituent materials to be examined; a spectrometer for providing a spectral signal related to the wavelength-specific intensity of light reflected by the constituent materials; and an evaluation device configured to determine the content of one or more constituent materials using the spectral signal of the spectrometer and a calibration data, wherein a property signal relating to a property of the one or more constituent materials is supplied to the evaluation device and the evaluation device is configured, using the property signal, to determine the content of the one or more constituent materials.

The gas content of a liquid is quickly and reliably controlled by delivering at least one sub-quantity of the liquid into a measurement cell in which a negative pressure is set. A wave-shaped measurement signal is applied to the sub-quantity, and the wave-shaped measurement signal is measured by at least one detector after coming into contact with the sub-quantity of the liquid. A turbidity value of the liquid is determined and compared with a threshold. If the turbidity value is greater than or equal to the threshold, a pressure and a temperature in the measurement cell are measured, and the gas content in the liquid is ascertained using stored characteristics for the solubility of the gas in the liquid dependent on the pressure and temperature.

Validation verification data quantifying an intensity of light reaching a detector of a spectrometer from a light source of the spectrometer after the light passes through a validation gas across a known path length can be collected or received. The validation gas can include an amount of an analyte compound and an undisturbed background composition that is representative of a sample gas background composition of a sample gas to be analyzed using a spectrometer. The sample gas background composition can include one or more background components. The validation verification data can be compared with stored calibration data for the spectrometer to calculate a concentration adjustment factor, and sample measurement data collected with the spectrometer can be modified using this adjustment factor to compensate for collisional broadening of a spectral peak of the analyte compound by the background components. Related methods, articles of manufacture, systems, and the like are described.

A bi-directional photoacoustic gas sensor includes a first photoacoustic cell, where an electromagnetic radiation source emits radiation to interact with an external gas and generate pressure waves that are detected by a MEMS diaphragm. A second photoacoustic cell has an interior volume and acoustic compliance that corresponds to the interior volume and acoustic compliance of the first photoacoustic cell. Processing circuitry within a substrate uses a first acoustic signal, received by the first photoacoustic cell, and a second acoustic signal, received by the second photoacoustic cell, to determine a bi-directional response of the gas sensor to remove noise and improve the sensor's signal-to-noise ratio.

A method includes receiving a gas mixture at a first pressure including at least a primary gas and a secondary gas and changing a pressure of the received gas mixture from the first pressure to a second pressure. Further, the method includes determining a spectra of the gas mixture at the second pressure, wherein at least the first spectral line of the primary gas is spectrally distinguished from at least the second spectral line of the secondary gas, identifying a peak wavelength associated with the spectrally distinguished first spectral line of the primary gas based on at least two wavelengths of the secondary gas corresponding to at least two peak amplitudes in the spectra of the gas mixture, and determining a concentration of the primary gas based on the identified peak wavelength associated with the spectrally distinguished first spectral line of the primary gas.