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Capacitive sensing has become a favorable measurement technology for flow metering in pneumatic conveying systems. Multielectrode sensing structures and tomographic signal evaluations enable spatially resolved flow parameter estimation, which is of particular interest for pneumatically conveyed solids due to inhomogeneous particle distributions within the pipeline. The noninvasive working principle of capacitive sensors is an important feature for the application in industrial processes with harsh environments. However, cross sensitivities of the capacitive probe cause effects, such as temperature drifts of the measurements. For a reliable operation of capacitive flow meters in harsh environments, induced drifts have to be compensated. In this article, we present the detailed analyses of thermal effects within capacitive sensors. Based on the findings, a model-based temperature compensation approach is developed within the Bayesian framework. The performance of the proposed compensation approach is analyzed by a measurement-based validation within a climate chamber and by a simulation-based uncertainty quantification. The capability to obtain temperature-independent estimates with calibration measurements acquired at room temperature is demonstrated. [ABSTRACT FROM AUTHOR]

In recent years, lithium ion batteries have become wide-spread energy sources for various battery-powered applications. In particular, LiFePO4 batteries are increasingly used for high-power automotive and storage applications. Unfortunately, the state of charge (SOC) is not uniquely determined by measuring just the LiFePO4 battery’s open-circuit voltage. However, an alternative approach for SOC determination is introduced by investigating the battery’s magnetic susceptibility. This is motivated by the iron atom’s magnetic state in the LiFePO4 cathode material, which changes during charging and discharging. The magnetic susceptibility of differently charged battery samples will be investigated to correlate the magnetic moment with the SOC in view of a new sensor concept. [ABSTRACT FROM PUBLISHER]

Systems for radio-frequency identification (RFID) realize a bidirectional wireless communication between a reader device and cheap passive tags (e.g., an RFID chip with an antenna printed on badges for access-control systems) in the near field of an antenna. This paper deals with the automatic and fast tuning of the resonant reader antennas in the widely used 13.56-MHz frequency band, resulting in a performance improvement and an increased read/write range. A novel RFID reader system is proposed with a tuning transformer for the automatic adjustment of the resonant circuit center frequency. This is achieved by shifting the magnetic operating point (i.e., the biasing direct-current (dc) magnetization) of a Ni–Zn ferrite transformer by means of an additional dc winding. The operation principle and the performance potential of this device are demonstrated by measurements on a prototypical RFID system. [ABSTRACT FROM PUBLISHER]