The paper on new developments in acoustic chemometric prediction of particle size, takes advantage of the vibrations (and the variation on frequency) produced by particles with different kinetic impacts on an accelerometer.
The model relates the frequencies measured to a known particle size thus enabling a prediction of unknown particle size and this is only one way to use sound frequencies to model some physical measured parameter. Any type of change (introduction of variation) in the sound frequency and/or amplitude can be used as input to a model some parameter e.g. imperfections in solid materials (cheese, molded items or 3D printed products).
Frequency Applications
Pulp and Paper
The paper industry used huge volumes of water, electricity, chemicals and mechanical processing, however this ressource load have been reduced over the years similar to other industries.
The Process Analytical Tools (PAT) are described in the pH.D. thesis by Anders Björk, listed below and takes advantage of several acoustic devices to model the pulp and paper processing.
The use of acoustic or vibration sensors that can related to the quality of the fibers, pulp and final paper. The real challange if to find information from acoustic sensors related to specific properties or classes, which can be used for prediction of final or intermediate quality.
The current work has been focused on the development of calibration routes for extraction of information from acoustic sensors and on signal processing algorithms for enhancing the information-selectivity for a specific pulp property or class of properties. Multivariate analysis methods like Principal Components Analysis (PCA), Partial Least Squares (PLS) and Orthogonal Signal Correction (OSC) have been used for visualization and calibration. Signal processing methods like Fast Fourier Transform (FFT), Fast Wavelet Transform (FWT) and Continuous Wavelet Transform (CWT) have been used in the development of novel signal processing algorithms for extraction of information from vibration- acoustic sensors.” (Björk, A. 2007)
Case 1: Size Distribution Monitoring by Resonant Acoustics
The measurement of sizes are not a trivial task and most often problems arise with large differences in particle sizes and in addition is time consuming to perform. Not to mention the expensive instrumentation.
The use to resonance acoustics in combination with chemometrics and data science show a good application for measurering size distributions, e.g. in powder blends.
The last paper, but not least, are the use of FTIR for determination of microplastics in sea sediment followed by chemometrics / machine learning in Python. This application is a very cool way to classify microplastic material types.
Please refer to the following scientific peer-rewieved papers for the full details
In-line and Real-time Monitoring of Resonant Acoustic Mixing by Near-infrared Spectroscopy Combined with Chemometric Technology for Process Analytical Technology Applications in Pharmaceutical Powder Blending Systems
References
Halstensen, M., & Esbensen, K. (2000).
New developments in acoustic chemometric prediction of particle size distribution – “The problem is the solution.” Journal of Chemometrics, 14(5–6), 463–481.
https://doi.org/10.1002/1099-128X(200009/12)14:5/6<463::AID-CEM628>3.0.CO;2-Y
Tanaka, R., TAKAHASHI, N., NAKAMURA, Y., HATTORI, Y., ASHIZAWA, K., & Otsuka, M. (2017). In-line and Real-time Monitoring of Resonant Acoustic Mixing by Near-infrared Spectroscopy Combined with Chemometric Technology for Process Analytical Technology Applications in Pharmaceutical Powder Blending Systems. Analytical Sciences, 33, 41–46. https://doi.org/10.2116/analsci.33.41
Primpke, S., Lorenz, C., Rascher-Friesenhausen, R., & Gerdts, G. (2017). An automated approach for microplastics analysis using focal plane array (FPA) FTIR microscopy and image analysis.
https://doi.org/10.1039/c6ay02476a
Björk, A. (2007). Chemometric and signal processing methods for real time monitoring and modeling using acoustic sensors. In Analytical Chemistry (Vol. 153).
Anders Björk, “Chemometric and signal processing methods for real time monitoring and modeling using acoustic sensors” – Applications in the pulp and paper industry, Ph.D. Thesis
In-line and Real-time Monitoring of Resonant Acoustic Mixing by Near-infrared Spectroscopy Combined with Chemometric Technology for Process Analytical Technology Applications in Pharmaceutical Powder Blending Systems