Anton Fuchs

Analysis of hardware concepts for electrical capacitance tomography applications

This paper presents two front-end circuit concepts for electrical capacitance tomography sensors. Input stage circuit models are used to analyze the robustness against stray capacitances, indicating clear advantages of the displacement current based approach. Hence, a further examination of this concept is carried out

Design and analysis of a capacitive moisture sensor for municipal solid waste

This paper presents a capacitive sensor conception to measure the moisture content (MC) in municipal solid waste that is primarily used for energy recovery by means of combustion. The sensor principle is based on a two-channel I/Q measurement of the complex impedance of the waste. The specific design of the sensor front-end allows for a robust MC determination in a non-contacting manner. In this paper, a detailed analysis of the sensor performance, including an estimation of the sensor cross-sensitivity on saline contamination and on metal components in the waste, is provided. Experiments are conducted under laboratory conditions and measurement results are presented.

Wireless Communication and Power Supply Strategy for Sensor Applications Within Closed Metal Walls

Passive or semiactive wireless sensors, i.e., sensors that require neither wires nor external power supply/batteries, are attractive for many measurement problems. Standard approaches based on Radio Frequency Identification technology usually have difficulties when a fairly conductive matter such as steel or a large amount of water is in the vicinity of the devices. This paper investigates methods for power and data transmission, even through the metal walls, e.g., of a tank or a pipe using super low frequency carrier signals. The feasibility is demonstrated by means of finite-element analysis and laboratory experiments and validated with a prototype setup for both a steel pipe and a tin container. Experimental results for capacitive fill-level measurement inside a metallic container are reported.

New Developments and Applications in Sensing Technology

This book has focussed on different aspects of smart sensors and sensing technology, i.e. intelligent measurement, information processing, adaptability, recalibration, data fusion, validation, high reliability and integration of novel and high performance sensors in the areas of magnetic, ultrasonic, vision and image sensing, wireless sensors and network, microfluidic, tactile, gyro, flow, surface acoustic wave, humidity and ultra-wide band. While future interest in this field is ensured by the constant supply of emerging modalities, techniques and engineering solutions, as well as an increasing need from aging structures, many of the basic concepts and strategies have already matured and now offer opportunities to build upon. The book has primarily been focussed for postgraduate and research students working on different aspects of design and developments of smart sensors and sensing technology.

An Investigation on Wireless Communication and Power Supply Through Metal Tank Walls

Passive wireless sensors, i.e. sensors that do neither require wires nor external power supply/batteries, are attractive for many measurement problems. Standard approaches based on radio frequency identification technology usually have difficulties when fairly conductive matter such as steel or large amount of water is in the vicinity of the devices. This paper investigates methods for power and data transmission even through metal walls, e.g. of a tank or a pipe using super low frequency carrier signals. The feasibility is demonstrated by means of finite element analysis and laboratory experiments and validated with a prototype setup for both a steel pipe and a tin container.

Current Reconstruction Algorithms in Electrical Capacitance Tomography

Figure 1 depicts a scheme of an electrical capacitance tomography (ECT) sensor. A number of electrodes are mounted on the exterior of a nonconductive process pipe. By measurements of the capacitances between certain electrode, it is aim to compute an image of the material distribution.

Influence of the discretization error on the reconstruction accuracy in electrical capacitance tomography

Purpose – The investigation of the influence of the modeling error on the solution of the inverse problem given uncertain measured data in electrical capacitance tomography (ECT).Design/methodology/approach – The solution of the nonlinear inverse problem in ECT and hence, the obtainable accuracy of the reconstruction result, highly depends on the numerical modeling of the forward map and on the required regularization. The inherent discretization error propagates through the forward map, the solution of the inverse problem, the subsequent calculation of process parameters and properties and may lead to a substantial estimation error. Within this work different finite element meshes are compared in terms of obtainable reconstruction accuracy. In order to characterize the reconstruction results, two error measures are introduced, a relative integral error and the relative error in material fraction. In addition, the influence of the measurement noise given different meshes is investigated from the statistic...

Capacitance-Based Sensing of Material Moisture in Bulk Solids: Applications and Restrictions

This paper presents applications of capacitive techniques for moisture sensing of bulk solids. Based on experimental measurement data for three test materials, theoretical considerations on moisture models in bulk solids are undertaken and the reliability of these models is discussed. The sensitivity of the capacitive setup on the moisture distribution inside the particles is analyzed by means of a multilayer model and Finite Element Analysis methods. A planar sensor topology featuring spatial resolution is proposed and the cross-sensitivity on material compression as well as the influence of the inter-electrode distance are investigated. Strengths and weaknesses of capacitive moisture sensing are discussed.

Mass Flowmeter for Screw Conveyors Based on Capacitive Sensing

This paper presents a measurement principle for the reliable determination of the mass flow of material through screw conveyors. The device is based on capacitive sensing with the characteristic that parts of the pipe content can be analyzed in a spatially resolving manner. Finite element analysis is used to investigate the sensor head and to estimate the performance of the sensor.

Single-layer measurement of particle velocity and concentration in pneumatic dilute phase conveying

This paper presents a capacitive single-layer sensor conception that allows for the measurement of particle velocity and particle concentration in a pneumatically conveyed granular flow. Two sensor topologies are analyzed and their applicability for non-invasive parameter estimation in dilute phase flow are discussed