Water is a sensitive and limited resource, mainly in intensively used agricultural areas in Austria, where groundwater is used as drinking water as well as for irrigation purposes. In order to guarantee a sustainable use of irrigation water, soil water measurement devices can be used to opti-mise irrigation, which means that controlling the soil water content in the entire root system may prevent water stress due to water deficiency on the one hand, and over wetting on the other hand. Furthermore, losses of nutrients due to leaching can be avoided. Several research studies on that topic were initiated during the last few years. The soil water status on selected fields planted with different crops (onions, carrots, sugar beets, sweet maize, zucchini) was monitored continuously by FDR (Fre-quency Domain Reflectometry) soil water measurement devices. Sensors in different depths measure the plant water uptake in the root zone under standard irrigation practices on different sites and dif-ferent soils, respectively. The deepest sensor is installed to avoid deep percolation caused by over irrigation. By means of these data, irrigation could be regulated based on the actual plant water re-quirements to keep the soil water content within an ideal range for crop development.

Air core solenoids, possibly single layer and with significant spacing between turns, are often used to ensure low stray capacitance, as they are used as part of many sensors and instruments. The problem of the correct estimation of the stray capacitance is relevant both during design and to validate measurement results; the expected value is so low to be influenced by any stray capacitance of the external measurement instrument. A simplified method is proposed that does not perturb the stray capacitance of the solenoid under test; the method is based on resonance with an external capacitor and on the use of a linear regression technique.

Safety and operation efficiency of the particle accelerators strongly depend on the quality of the supplied electric current and is affected by the electric properties of all elements of the circuit. In this paper the capacitance of the superconducting bus-bars applied in the cryogenic by-pass line for the SIS100 particle accelerator at FAIR is analysed. The unit capacitance of the bus-bars is calculated numerically and found experimentally. A 2D numerical model of a cross-section of the cable is applied. The capacitance is found with three methods. The stored energy, electric displacement field and charge gathered on the surfaces of the device are calculated and analysed. The obtained values are consistent. Experimental measurements are performed using the resonance method. The measuring system is undamped using a negative conductance converter. Small discrepancies are ob- served between numerical and experimental results. The obtained values are within the requirements of the accelerator design.

Dynamic charge carrier transport behavior in the zirconium (Zr) oxide was investigated based on the frequency-dependent capacitance-voltage (C-V) and temperature-dependent current-voltage (I-V) measurements. The Zr oxide was formed on the ZIRLO and newly developed zirconium-based alloy (NDZ) by corrosion in the PWR-simulated loop at 360°C. The corrosion test for 90 days showed that the NDZ exhibits better corrosion resistance than ZIRLO alloy. Based on the C-V measurement, dielectric constant values for the Zr oxide was estimated to be 11.28 and 11.52 for the ZIRLO and NDZ. The capacitance difference between low and high frequency was larger in the ZIRLO than in the NDZ, which was attributed to more mobile electrical charge carriers in the oxide layer on the ZIRLO alloy. The current through the oxide layers on the ZIRLO increased more drastically with increasing temperature than on the NDZ, which indicating that more charge trap sites exist in the ZIRLO than in NDZ. Based on the dynamic charge carrier transport behavior, it was concluded that the electrical charge carrier transport within the oxide layers was closely related with the corrosion behavior of the Zr alloys.

The problem of a closed-form accurate determination of self and mutual capacitance of conductors in air and earth is considered: the application is the complete modeling of a railway line including buried conductors. The Generalized Potential Method (GPM) is presented and analyzed with regard to conditions of validity and solution methods. The accuracy of the GPM is evaluated solving some reference cases using the Complex Image Method and a commercial Finite Element Method simulator, comparing the model results with experimental data, and including the sensitivity on soil conductivity and permittivity, distance of conductors from the air–earth interface and frequency.

The paper presents a review of current achievements in the Electrical Capacitance Tomography (ECT) in relation to its possible applications in the study of phenomena occurring in fluidised bed reactors. Reactors of that kind are being increasingly used in chemical engineering, energetics (fluidised bed boilers) or industrial dryers. However, not all phenomena in the fluidised bed have been thoroughly understood. This results in the need to explore and develop new research methods. Various aspects of ECT operation and data processing are described with their applicability in scientific research. The idea for investigation of temperature distribution in the fluidised bed, using multimodal tomography, is also introduced. Metrological requirements of process tomography such as sensitivity, resolution, and speed of data acquiring are noted.

In this paper a measurement system for determination of supercapacitor equivalent parameters is proposed. Specific properties of materials used for supercapacitor construction require some advanced tools and measurement procedures to be applied during tests. The measurement system allows to measure values of equivalent parameters by both the DC and AC method whilst keeping appropriate time criteria required by this type of devices. Furthermore, in this paper the most relevant properties and measurement capabilities of the proposed system are described as well as some exemplary values of the supercapacitor equivalent parameters measured experimentally are presented.

By the use of different distribution methods of dynamical characteristics in the form of slowness function, mechatronic discrete systems have been synthesized. Each model consists of mechanical discrete part and a piezostack actuator connected to LxRxCx external network that has to comply with dynamical requirements in the form of poles and zeros. External network can work within different configurations. In this paper, one investigates the influence of negative parameters of stiffness in mechanical replacement models and capacitance in final mechatronic structures, after dimensionless transformations and retransformations.

The arc suppression coil determines whether it can effectively extinguish the arc when it is grounded in the neutral non-effective grounding system. An artificial grounding test is an importantway to verify its performance. In this study, 13 substations with the 10 kV system in the Ningxia areawere selected and considered. Based on the artificial single-phase grounding test, the residual current, the compensation current and the off-resonance degree were measured in the arc suppression coil, and the performance of the arc suppression coil in the 10 kV system was verified. The experimental results show that the error of arc suppression coil automatic measurement is large, the off-resonance degree is large, the resistive component in the compensation current is excessive, the harmonic component exists in the compensating current and capacitive current. To solve these problems, this paper puts forward the corresponding countermeasures for reference.

A new approach to solve the inverse problem in electrical capacitance tomography is presented. The proposed method is based on an artificial neural network to estimate three different parameters of a circular object present inside a pipeline, i.e. radius and 2D position coordinates. This information allows the estimation of the distribution of material inside a pipe and determination of the characteristic parameters of a range of flows, which are characterised by a circular objects emerging within a cross section such as funnel flow in a silo gravitational discharging process. The main advantages of the proposed approach are explicitly: the desired characteristic flow parameters are estimated directly from the measured capacitances and rapidity, which in turn is crucial for online flow monitoring. In a classic approach in order to obtain these parameters in the first step the image is reconstructed and then the parameters are estimated with the use of image processing methods. The obtained results showed significant reduction of computations time in comparison to the iterative LBP or Levenberg-Marquard algorithms.

Most of the basic control methods of the grid-connected converter (GCC) are defined to work with a sine wave grid voltage. In that case if the grid voltage is distorted by higher harmonics, the grid current may be distorted too, which, in consequence, may increase the value of the THD of the grid voltage. The paper deals with an improved finite control set model predictive control (FCS-MPC) method of an LCL-filtered GCC operating under distorted grid conditions. The proposed method utilizes supplementary grid current feedback to calculate the reference converter current. The introduced signal allows to effectively improve the operation when the grid is subject to harmonic distortion. The paper shows a simulation analysis of the proposed control scheme operating with and without additional feedback under grid distortions. To validate the practical feasibility of the proposed method an algorithm was implemented on a 32-bit microcontroller STM32F7 with a floating point unit to control a 10 kW GCC. The laboratory test setup provided experimental results showing properties of the introduced control scheme.