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A new ground temperature profile sensor comprising of a row of thermistors enables a large number of equidistantly arranged measuring points. The row of thermistors was formed using a group of negative temperature coefficient thick film segmented thermistors connected in series. After that calibration of the DC thermistor resistance R was performed at room temperature and the sensor was placed in a hole drilled on the lawn. DC resistances R of the row of thermistors were measured versus depth z as a parameter and converted to actual temperature T(z) in the ground using the Steinhart-Hart equation. The temperature profile of the ground depending on deepness z and time t as a function T(t, z) was measured on different days during one year in the early morning and in the afternoon. The temperature at the ground surface was compared with the temperature of the deepest sensor point in the ground. Thermal diffusivity D of the ground was determined using measured data T(t, z) in the periods of steady ground temperatures. The new ground temperature profile sensor was realized to investigate the correlation between air and ground temperature, observation of ground temperature profile changes and heat exchange (heat transfer, diffusion, gradient, and heat flow direction) through the ground top layer and finally humidity estimation versus deepness. [ABSTRACT FROM PUBLISHER]

A heat loss flowmeter for measuring the volume flow rate of water in real time ( t) was formed using two thick film segmented thermistors, range constant voltage (RCV) power supply, acquisition card, PC, and software. The input water temperature T_{w}(t) was measured by a cold thermistor, while the water flow rate Q(t) was determined using the heat loss principle by measuring the self-heated thermistor current I(t) . The flowmeter inertia, stability, and accuracy were measured and analyzed on a flowmeter prototype in real-time and real conditions on the water mains. The flowmeter response was measured for different durations of step input water flow-out functions and intervals between steps. An independent ultrasonic flowmeter was connected in series with the thermal flowmeter to measure the ordered input water flow functions. The realized intelligent functions in real time were: measuring the input water temperature T_{w}(t) and self-heating temperature T_{s}(t) , auto-selection of RCV supply voltage U(Tw) , determination and modeling of the water flow rate in real time Q(t) , determination of the water volume $V(t)$ , and determination of the thermal gradient on the self-heating thermistor as a water flow indicator \Delta R_{s}(t) . [ABSTRACT FROM PUBLISHER]

A simple thermal (heat loss) sensor system was designed in a small plastic tube housing using a negative thermal coefficient (NTC) thick-film thermistor as a self-heating sensor. The voltage power supply [range constant voltage (RCV)-range constant voltage] uses the measured input water temperature to select the applied voltage in steps (up and down) in order to enable operation of the sensor at optimal sensitivity for different water temperatures. The input water temperature was measured using a “cold” NTC thick-film segmented thermistor. The measured calibration curves were modeled. Additional calculated curves were interpolated between the experimental curves in fine steps to cover each temperature of input water and can be used for determining the water volume flow rate or water velocity. The realized prototype flow meter inertia, stability, repeatability, and tolerance were measured and analyzed. The proposed intelligent RCV thermal flow meter system will include a smart power supply with range-constant-voltages (auto-range), a simple acquisition card and custom designed flow meter software. [ABSTRACT FROM PUBLISHER]