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This paper presents a new water-level-sensing mechanism based on planar coils fabricated on a printed circuit board (PCB). In addition to level, the sensor detects any relative increase in conductivity compared to that of clean water, which is an indicator of its quality. The sensing mechanism utilizes the eddy current induced in the water column, the corresponding change in the coil inductance, and the change in the turn-to-turn capacitance of the coil in the presence of water. Although several level sensors are available, there is none that gives the level and quality information using a single sensing element. Since both water quantity and quality measurements are fundamental in realizing efficient water and wastewater management, obtaining these two parameters from the same sensor is very beneficial. A scalable, planar coil-based sensor that helps achieve this goal is designed, fabricated, and tested in a laboratory setting. The results illustrate that the reactance of the sensor coil measured at a frequency (1 kHz for the prototype) much lower than the self-resonance of the coil gives reliable information about the level of water, while the measurement made at resonance, using an inductance-to-digital converter, is a clear indicator of its conductivity and, hence, quality. [ABSTRACT FROM AUTHOR]

• Non-destructive evaluation techniques in measurement applications require transferring complex signals to usable quantities. • Equivalent circuit models for eddy current sensors evaluated for their voltage transfer functions are those of lossy transformers. • Splitting transformer coupling and eddy-current losses enables simple models, which can be automatically constructed. • Implementation of parameter identification in a real-time soft sensor is possible. • This soft sensor can be used to measure material properties in a repeatable fashion. The use of eddy-current techniques as a measurement method for material characterization instead of simple fault detection requires transformation of the electrical response signals to quantifiable physical parameters that correlate with material properties. Apart from calibration-curve methods, exact approaches that correctly represent all interactions between excitation field and response field are computationally intensive and not well suited to real-time application. In this work, an equivalent circuit network model is constructed and its analytical equation for the voltage transfer function is derived. This model is then implemented in a soft sensor system. Finally, measurement results from various materials with different electromagnetic properties are presented. [ABSTRACT FROM AUTHOR]

This paper presents a new water-level-sensing mechanism based on planar coils fabricated on a printed circuit board (PCB). In addition to level, the sensor detects any relative increase in conductivity compared to that of clean water, which is an indicator of its quality. The sensing mechanism utilizes the eddy current induced in the water column, the corresponding change in the coil inductance, and the change in the turn-to-turn capacitance of the coil in the presence of water. Although several level sensors are available, there is none that gives the level and quality information using a single sensing element. Since both water quantity and quality measurements are fundamental in realizing efficient water and wastewater management, obtaining these two parameters from the same sensor is very beneficial. A scalable, planar coil-based sensor that helps achieve this goal is designed, fabricated, and tested in a laboratory setting. The results illustrate that the reactance of the sensor coil measured at a frequency (1 kHz for the prototype) much lower than the self-resonance of the coil gives reliable information about the level of water, while the measurement made at resonance, using an inductance-to-digital converter, is a clear indicator of its conductivity and, hence, quality.

Tangential profile ring rolling (Profiled Radial Ring Rolling, PRRR) enables the fast and compared to machining inexpensive production of bearing rings or similar ring-shaped parts with near net-shape geometry and advantageous material properties due to a high degree of work hardening at a high cadence. Conventionally, a specific heat treatment regime is required to achieve the desired microstructural and mechanical properties such as grain size, hardness or strength. Novel control strategies allow thermomechanical treatment during the forming operation itself. To monitor the evolution of properties during forming, a sensor system based on eddy current methods is presented and its ability to discriminate between various influences is demonstrated. It is shown that different process conditions result in different end-product microstructures, and that these differences both relate to application relevant properties and can be identified using non-destructive eddy current sensing, even in the presence of superposed disturbances such as local variations in electromagnetic properties.