The present disclosure provides a system and method for verifying alternating current (AC)/direct current (DC) conversion of an ultralow-frequency voltage. The system includes a quantum voltage generation system, a low-frequency signal source, a follower, three switches, a double-heater-strip thermoelectric converter, a nanovoltmeter, a clock source, a high-precision digital sampling system, and an upper computer. Based on DC and AC quantum voltage technologies and with reference to the double-heater-strip thermoelectric converter, an ultralow-frequency voltage is traced to a DC quantum voltage through AC/DC conversion, and a conversion result is compared with an AC quantum voltage to verify rationality of precision and an uncertainty evaluation result of AC/DC conversion of the ultralow-frequency voltage, so as to ensure reliability of AC/DC conversion of the ultralow-frequency voltage. This resolves a problem that the AC/DC conversion result of the ultralow-frequency voltage cannot be verified.

An extracorporeal blood treatment apparatus is provided comprising a filtration unit (2) connected to a blood circuit (17) and to a dialysate circuit (32); a control unit (12) is configured for calculating a sodium concentration value for the blood; the estimation of the sodium concentration includes the sub-step of calculating the sodium concentration value as an algebraic sum of a main contribution term based on the isoconductive sodium concentrate and of an offset contribution term based on a concentration of at least a substance in the dialysis fluid chosen in the group including bicarbonate, potassium, acetate, lactate, citrate, magnesium, calcium, sulphate and phosphate.

A high temperature fixture, said fixture comprising: at least three noble metal electrodes, arranged in parallel, among which two adjacent noble metal electrodes are used for clamping a test sample; noble metal wires connected to the noble metal electrodes at one end, and to a test device at the other end for transmitting test signals generated by the test sample to the test device through the noble metal electrodes; and a thermocouple for measuring the temperature of the test materials.

A control system for controlling an adjustable output voltage provided to a heater includes a controller configured to determine an input parameter based on an electrical characteristic of the heater, where the heater includes a resistive heating element that is operable to emit heat and as a sensor. The controller is further configured to determine an output voltage for the heater based on the input parameter and a desired setpoint, and to transmit a signal to a power converter to generate the output voltage. The desired setpoint is based on an operational state of the heater, and the input parameter includes data indicative of a temperature of the resistive heating element that is determined based on the electrical characteristic.

A control system includes a power converter being a step-down voltage converter and including a power switch. The power converter is operable to generate an adjustable output voltage and includes a sensor circuit configured to measure at least one of a voltage and an electric current of the heater. The control system includes a controller connected to the power converter and the sensor circuit. The controller is configured to determine an input parameter based on the at least one of the voltage and the electric current. The input parameter is indicative of a temperature of the heater. The controller is configured to set the output voltage applied for the heater based on the input parameter and a desired setpoint. The desired setpoint is based on an operational state of the heater. The controller is configured to operate the power switch of the power converter to generate the output voltage.

A method includes selecting a state model control, as an operational state of the heater, from among a plurality of state model controls, measuring an electrical characteristic of the heater, where the electrical characteristic includes at least one of an electric current and a voltage, and controlling power to the heater based on the selected operational state and based on the measured electrical characteristic.

The present disclosure generally describes a method and system for converting power to operate a load being supplied by line power having a line energy. The method includes rectifying the line power, bucking the rectified line power to generate a desired voltage output such that current is drawn from the line power in phase with the desired voltage output, and bypassing switching energy created during the bucking of the rectified line power.