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A characterizing feature of the German electricity transition is that it started as a movement arising from the civil society. Initially the movement was directed against nuclear energy and later on turned into a movement favoring decentralized forms of energy production and distribution as well as local control over energy questions. Once these demands found official recognition and regulatory support, a dynamic development ensued in which a host of new actors with new ideas and strategies became involved in the field of electricity generation. Regions, cities and villages experimenting with socio-technical innovations and aiming to implement new concepts developed governance structures under high uncertainty. These governance structures mirror space-specific social, political, technological and economic constellations. Once the old incumbent actors in the field began to falter, both government and electricity providers started to stem the tide of decentralized initiatives, whose dynamic in fact has recently been seriously weakened. In order to help us better understand these developments in a more generic context, the theory of strategic action fields will be applied. [ABSTRACT FROM AUTHOR]

Abstract: In recent decades piezo- and pyroelectricity found application in yet another important field of research. A number of methods have been developed which employ these properties to investigate the micro- and macroscopic polarization of materials. Advances in piezo- and pyroelectric imaging enabled researchers to examine the polarization distribution of a sample with unprecedented detail. This review attempts to inform the general reader about some of those experimental techniques and their findings. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study of kerosene–water upward two-phase flow in a vertical pipe was carried out using hot-film, dual optical and Pitot tube probes to measure the water, kerosene drops and mixture velocities. Experiments were conducted in a vertical pipe of 77.8 mm inner diameter at 4.2 m from the inlet (L/D=54). The tests were carried out for constant superficial water velocities of 0.29, 0.59 and 0.77 m/s (flow rates = 83, 167 and 220 l/min) and volume fractions of 4.2%, 9.2%, 18.6% and 28.2%. The Fluent 6.3.26 was used to model the single and two-phase flow and to reproduce the results for the experimental study. Two methods were used to evaluate the accuracy of the probes for the measurement of the velocities of water, drops and mixture for two-phase flow: (i) comparison of measured local velocities with predictions from the CFD simulation; (ii) comparison between the area-averaged velocities calculated from the integration of the local measurements of water, drops and mixture velocities and velocities calculated from flow meters’ measurements. The results for single phase flow measured using Pitot tube and hot-film probe agree well with CFD predictions. In the case of two-phase flow, the water and drops velocities were measured by hot-film and dual optical probes respectively. The latter was also used to measure the volume fraction. These three measured parameters were used to calculate the mixture velocity. The Pitot tube was also used to measure the mixture velocity by applying the same principle used for single phase flow velocity. Overall the mixture local velocity measured by Pitot tube and that calculated from hot-film and dual optical probe measurements agreed well with Fluent predictions. The discrepancy between the mixture area-averaged velocity and velocity calculated from flow meters was less than 10% except for one test case. It is concluded that the combined hot-film and optical approach can be used for water and drop velocity measurements with good accuracy for the flow conditions considered in this study. The Pitot tube can also be used for the measurement of mixture velocities for conditions of mixture velocities greater than 0.4 m/s. The small discrepancy between the predictions and experimental data from the present study and literature demonstrated that both instrumentation and CFD simulations have the potential for two-phase flow investigation and industrial applications. [Copyright &y& Elsevier]

Abstract: A method for air–water two-phase flow measurement is proposed using a Venturi meter combined with an Electrical Resistance Tomography (ERT) sensor. Firstly, the real-time flow pattern of the two-phase flow is identified using the ERT sensor. Secondly, the void fraction of the two-phase flow is calculated from the conductance values through a void fraction measurement model, developed using the LS-SVM regression method. Thirdly, the mass quality is determined from the void fraction through void fraction-quality correlation. And finally, the mass flowrate of the two-phase flow is calculated from the mass quality and the differential pressure across the Venturi meter. Experimental results demonstrate that the proposed method is effective for the measurement of the mass flowrate of air–water flow. The proposed method introduces the flow pattern information in the measurement process, which minimizes the influence of flow pattern on the conventional differential pressure based methods. In addition, the mass quality is calculated from the void fraction, so the difficulty to obtain the mass quality in conventional methods is also overcome. Meanwhile, the new method is capable for providing concurrent measurements of multiple parameters of the two-phase flow including void fraction, mass quality and mass flowrate as well as an indication of the flow pattern. [ABSTRACT FROM AUTHOR]

Abstract: Radial variation of the gas hold-ups and mean hold-ups are investigated in a 90 mm outer loop bubble column using electrical resistance tomography (ERT) with two axial locations (Plane 1 and Plane 2). In all the experiments, air is used as the gas phase, tap water as liquid phase, and polypropylene particles as solid phase where the superficial gas velocity is varied from 0.02 to 0.25 m/s. The effect of operating conditions, solid concentration on mean hold-ups and radial gas hold-ups distribution is discussed. Gas hold-ups and solid hold-ups results using ERT are in very good agreement with conventional estimation and correlations obtained using pressure transmitter methods. Meanwhile, the results show that the gas hold-ups in the centre region increase constantly with an increase in the superficial gas velocity, namely there is a maximum hold-up at the centre of cross-section. But, solid hold-ups distribution is very homogeneous for high gas velocity. According to the visible image, the gas–liquid flow behaviours are obtained for gas–liquid–solid outer loop bubble column. Furthermore, the results also indicate that ERT is a very powerful tool for diagnosing the ‘inside’ flow behaviour of gas–liquid–solid three phase bubble column. [ABSTRACT FROM AUTHOR]

Abstract: In the present study, a combined model of computational fluid dynamics and the discrete element method (CFD–DEM) was used to simulate the particle distributions in a down-flow fluidized bed (DFB) with a newly designed particle–air distributor. In the simulation model, particle motion is calculated by solving Newton’s equations and the flow field of air is predicted by the Navier–Stokes equations. The calculation was made for the same geometric and operating conditions as the experiment which was carried out for comparison with the simulation using electrical capacitance tomography (ECT). The numerical predictions for the axial and radial profiles of the particle distribution agreed well with the experimental results. [ABSTRACT FROM AUTHOR]

Abstract: This paper covers the results of tests with the slender cylindrical silo emptied both gravitationally and in a controlled manner. The measurement technique chosen as an examination tool is the Electrical Capacitance Tomography (ECT). The major aim of this paper is to demonstrate the measurement capabilities of ECT system dedicated to detect oscillations in non-cohesive sand during silo flow. The actual experimental measurements were preceded by analysis of signal noise for static and dynamic tests. The influence of the initial density, wall roughness, elevation and velocity on the emptying process and vibrations is examined, as well. Results are presented in the form of continuous, concentration vs. time, graphs. Graphs are plotted on the basis of the raw measurement data and values of chosen reconstructed image pixels. [ABSTRACT FROM AUTHOR]

Discusses the nineteenth century discoveries of the relationship between electricity and life. Details on speculations about the links between the forces of electricity, heat, light and magnetism; Information on experiments which seeks to prove the relationship; What was revealed.