Systems and techniques for measuring process characteristics including electrolyte distribution in a battery cell. A non-destructive method for analyzing a battery cell includes determining acoustic features at two or more locations of the battery cell, the acoustic features based on one or more of acoustic signals travelling through at least one or more portions of the battery cell during one or more points in time or responses to the acoustic signals obtained during one or more points in time, wherein the one or more points in time correspond to one or more stages of electrolyte distribution in the battery cell. One or more characteristics of the battery cell are determined based on the acoustic features at the two or more locations of the battery cell.

Systems and techniques for measuring process characteristics including electrolyte distribution in a battery cell. A non-destructive method for analyzing a battery cell includes determining acoustic features at two or more locations of the battery cell, the acoustic features based on one or more of acoustic signals travelling through at least one or more portions of the battery cell during one or more points in time or responses to the acoustic signals obtained during one or more points in time, wherein the one or more points in time correspond to one or more stages of electrolyte distribution in the battery cell. One or more characteristics of the battery cell are determined based on the acoustic features at the two or more locations of the battery cell.

A method for measuring a fracture permeability and a matrix permeability of a naturally fractured cylindrical rock sample, includes sealing both flat ends of the cylindrical sample; immersing the naturally fractured cylindrical rock sample in a fluid, and attaching an axial and a radial strain sensor to the curved surface of the sample. Furthermore, the method includes attaching a signal generator to one flat end of sample, and a signal receiver to the other flat end of the sample, and generating a harmonic excitation using the signal generator at a plurality of frequencies and recording the excitation at each of the plurality of frequencies. The method includes calculating an elastic wave propagation attribute at each of the plurality of frequencies, and inverting the elastic wave propagation attribute at each of the plurality of frequencies to determine the fracture permeability and the matrix permeability of the naturally fractured cylindrical rock sample.

Systems and methods for prediction of state of charge (SOH), state of health (SOC) and other characteristics of batteries using acoustic signals, includes determining acoustic data at two or more states of charge and determining a reduced acoustic data set representative of the acoustic data at the two or more states of charge. The reduced acoustic data set includes time of flight (TOF) shift, total signal amplitude, or other data points related to the states of charge. Machine learning models use at least the reduced acoustic dataset in conjunction with non-acoustic data such as voltage and temperature for predicting the characteristics of any other independent battery.

Systems and methods for prediction of state of charge (SOH), state of health (SOC) and other characteristics of batteries using acoustic signals, includes determining acoustic data at two or more states of charge and determining a reduced acoustic data set representative of the acoustic data at the two or more states of charge. The reduced acoustic data set includes time of flight (TOF) shift, total signal amplitude, or other data points related to the states of charge. Machine learning models use at least the reduced acoustic dataset in conjunction with non-acoustic data such as voltage and temperature for predicting the characteristics of any other independent battery.

A multi-frequency acoustic velocity measurement device for a core includes: a fixing device, for fixing a core and heating and pressurizing the core according to a preset condition; a transmitting end acoustic wave probe, connected to a first end of a control unit and one end of the fixing device, and configured to transmit an acoustic wave signal to the core; a receiving end acoustic wave probe, connected to a second end of the control unit and the other end of the fixing device, and configured to receive the acoustic wave signal transmitted by the transmitting end acoustic wave probe; and the control unit, for controlling the transmitting end acoustic wave probe to transmit acoustic wave signals of different frequencies, receiving the acoustic wave signal received by the receiving end acoustic wave probe, and determining an acoustic velocity of the core according to the acoustic wave signal.

A method for measuring a fracture permeability and a matrix permeability of a naturally fractured cylindrical rock sample, includes sealing both flat ends of the cylindrical sample; immersing the naturally fractured cylindrical rock sample in a fluid, and attaching an axial and a radial strain sensor to the curved surface of the sample. Furthermore, the method includes attaching a signal generator to one flat end of sample, and a signal receiver to the other flat end of the sample, and generating a harmonic excitation using the signal generator at a plurality of frequencies and recording the excitation at each of the plurality of frequencies. The method includes calculating an elastic wave propagation attribute at each of the plurality of frequencies, and inverting the elastic wave propagation attribute at each of the plurality of frequencies to determine the fracture permeability and the matrix permeability of the naturally fractured cylindrical rock sample.

Methods are disclosed for evaluating a material on a remote side of a partition separating first and second domains wherein flexural waves within the partition are received by spaced-apart ultrasonic receivers and processed to determine the velocity of the waves propagating into the second domain from a first receiver to a second receiver located more remote from the transmitter than the first receiver and whose separation from the first receiver is known. Comparison of a theoretical phase velocity with the measured phase velocity of the recorded waves allows determination as to whether the flexural wave is propagating through solid. This may be based on a measurable deviation between the two curves occurring at a critical frequency, which may be identified by a perturbation in a group velocity plot. Discrimination may also be based on the gradient of a straight line that best-fits the attention dispersion of the frequency spectrum.

Methods are disclosed for evaluating a material on a remote side of a partition separating first and second domains wherein flexural waves within the partition are received by spaced-apart ultrasonic receivers and processed to determine the velocity of the waves propagating into the second domain from a first receiver to a second receiver located more remote from the transmitter than the first receiver and whose separation from the first receiver is known. Comparison of a theoretical phase velocity with the measured phase velocity of the recorded waves allows determination as to whether the flexural wave is propagating through solid. This may be based on a measurable deviation between the two curves occurring at a critical frequency, which may be identified by a perturbation in a group velocity plot. Discrimination may also be based on the gradient of a straight line that best-fits the attention dispersion of the frequency spectrum.

Systems and techniques for measuring process characteristics including electrolyte distribution in a battery cell. A non-destructive method for analyzing a battery cell includes determining acoustic features at two or more locations of the battery cell, the acoustic features based on one or more of acoustic signals travelling through at least one or more portions of the battery cell during one or more points in time or responses to the acoustic signals obtained during one or more points in time, wherein the one or more points in time correspond to one or more stages of electrolyte distribution in the battery cell. One or more characteristics of the battery cell are determined based on the acoustic features at the two or more locations of the battery cell.