An apparatus for estimating electrical properties of an electrolyzer includes a data processing system for estimating electrical values, for example a membrane resistance, of the electrolyzer based on a difference voltage, a current, and an initial value and an attenuation time constant of a double-layer capacitance voltage of the electrolyzer during a shutdown of the electrolyzer. The difference voltage is a difference between a voltage of the electrolyzer and a total reversible voltage of the electrolyzer. The initial value and the attenuation time constant of the double-layer capacitance voltage are estimated based on values of the difference voltage when the current is zero and thus the difference voltage equals the double-layer capacitance voltage. The electrical values can be estimated even if a stepwise interruption of the current of the electrolyzer is not possible.

An apparatus for estimating electrical properties of an electrolyzer includes a data processing system for estimating electrical values, for example a membrane resistance, of the electrolyzer based on a difference voltage, a current, and an initial value and an attenuation time constant of a double-layer capacitance voltage of the electrolyzer during a shutdown of the electrolyzer. The difference voltage is a difference between a voltage of the electrolyzer and a total reversible voltage of the electrolyzer. The initial value and the attenuation time constant of the double-layer capacitance voltage are estimated based on values of the difference voltage when the current is zero and thus the difference voltage equals the double-layer capacitance voltage. The electrical values can be estimated even if a stepwise interruption of the current of the electrolyzer is not possible.

According to one embodiment, a sensor includes an element part, and a control circuit part. The element part includes first and second elements. Each of the first and second elements includes a first magnetic element and a first conductive member. The control circuit part includes a first current circuit, a differential circuit, and a phase detection circuit. The first current circuit is configured to supply a first current to the first conductive member. The differential circuit is configured to output a differential signal corresponding to a difference of a first signal and a second signal. The first signal corresponds to a change in a first electrical resistance of the first magnetic element of the first element, The second signal corresponds to a change in a second electrical resistance of the first magnetic element of the second element. The phase detection circuit is configured to perform a phase detection of the differential signal.

A method for determining an emission coefficient of a device under test (DUT) using a test circuit comprises coupling a parameter measurement circuit associated with the test circuit to an input pin associated with the DUT, wherein the input pin is coupled to a diode element within the DUT and performing voltage and current measurements associated with the input pin using the parameter measurement circuit. In some embodiments, the method further comprises determining a plurality of contact resistance values respectively based on the voltage and current measurements and an emission coefficient estimate using a contact resistance estimation circuit; and determining an emission coefficient associated with the DUT based on the determined plurality of contact resistance values using an emission coefficient determination circuit.

A method for determining an emission coefficient of a device under test (DUT) using a test circuit comprises coupling a parameter measurement circuit associated with the test circuit to an input pin associated with the DUT, wherein the input pin is coupled to a diode element within the DUT and performing voltage and current measurements associated with the input pin using the parameter measurement circuit. In some embodiments, the method further comprises determining a plurality of contact resistance values respectively based on the voltage and current measurements and an emission coefficient estimate using a contact resistance estimation circuit; and determining an emission coefficient associated with the DUT based on the determined plurality of contact resistance values using an emission coefficient determination circuit.

Hundreds of thousands of concrete bridges and hundreds of billions of tons of concrete require characterization with time for corrosion. Accordingly, protocols for rapid testing and improved field characterization systems that automatically triangulate electrical resistivity and half-cell corrosion potential measurements would be beneficial allowing discrete/periodic mapping of a structure to be performed as well as addressing testing for asphalt covered concrete. Further, it is the low frequency impedance of rebar in concrete that correlates to corrosion state but these are normally time consuming vulnerable to noise. Hence, it would be beneficial to provide a means of making low frequency electrical resistivity measurements rapidly. Further, prior art techniques for electrical rebar measurements require electrical connection be made to the rebar which increases measurement complexity/disruption/repair/cost even when no corrosion is identified. Beneficially a method of determining the state of a rebar without electrical contact is taught.

A method for determining a converter Thevenin equivalent model for a converter system, includes: receiving measurement values of a coupling point voltage and a coupling point current measured at a point of common coupling between a grid emulator system and the converter system, wherein the grid emulator system supplies the converter system with a supply voltage; and determining a converter Thevenin impedance and a converter Thevenin voltage source of the converter Thevenin equivalent model by inputting the measurement values of the coupling point voltage and of the coupling point current into a coupled system model, which includes equations modelling the converter system and the grid emulator system and from which the converter Thevenin impedance and a converter Thevenin voltage source are calculated.

A method for estimating resistances of a circuit having a plurality of resistances comprising a first resistance and a second resistance may include applying a first bias voltage across the circuit and measuring a first voltage at a common node between the first resistance and the second resistance in order to determine a mathematical relationship between the first resistance and the second resistance, applying a second bias voltage across the circuit and a third resistance in parallel with the circuit and measuring a second voltage at the common node between the first resistance and the second resistance in order to determine a mathematical relationship between the third resistance and at least one of the first resistance and the second resistance, and based on at least the measurement of the first voltage and the measurement of the second voltage, determining the first resistance and the second resistance as a function of the third resistance.

A method for estimating resistances of a circuit having a plurality of resistances comprising a first resistance and a second resistance may include applying a first bias voltage across the circuit and measuring a first voltage at a common node between the first resistance and the second resistance in order to determine a mathematical relationship between the first resistance and the second resistance, applying a second bias voltage across the circuit and a third resistance in parallel with the circuit and measuring a second voltage at the common node between the first resistance and the second resistance in order to determine a mathematical relationship between the third resistance and at least one of the first resistance and the second resistance, and based on at least the measurement of the first voltage and the measurement of the second voltage, determining the first resistance and the second resistance as a function of the third resistance.

A resistance mapping device includes: a first chip including a first surface, a second surface positioned at a side opposite to the first surface, and a plurality of first electrodes provided at the first surface; a second chip including a third surface facing the first surface, a fourth surface positioned at a side opposite to the third surface, and a plurality of second electrodes provided at the third surface; and a measurement part, the measurement part being configured to measure a resistance of a portion of a measurement object, the portion of the measurement object being between the first electrode and the second electrode that correspond to each other among the plurality of first electrodes and the plurality of second electrodes, and acquire mapping data in which measured values of the resistances are associated with positions of the measurement object corresponding to the plurality of first electrodes.