1,721,220 research outputs found
Development of an Arduino-based electrical impedance tomography system with application to dam internal erosion detection
Full text linkElectrical Impedance Tomography (EIT) is a technique for the imaging of the electrical properties of conductive
materials. In EIT, the spatial distribution of the electrical resistivity or electrical conductivity within a domain is
reconstructed using measurements made with electrodes placed at the boundaries of the domain. Data acquisition
is typically made by applying an electrical current to the object under investigation using a set of electrodes, and
measuring the developed voltage between the other electrodes. The tomographic image is then obtained using an
inversion algorithm.
This work describes the implementation of a simple and low cost 3D EIT measurement system suitable for
laboratory-scale studies. The system was specifically developed for the time-lapse imaging of soil samples
subjected to erosion processes during laboratory tests. The tests reproduce the process of internal erosion of soil
particles by water flow within a granular media; this process is one of the most common causes of failure of
earthen levees and embankment dams. The measurements needed strict requirements of speed and accuracy due
to the varying time scale and magnitude of these processes.
The developed EIT system consists of a PC which controls I/O cards (multiplexers) through the Arduino micro-
controller, an external current generator, a digital acquisition device (DAQ), a power supply and the electrodes.
The ease of programming of the Arduino interface greatly helped the implementation of custom acquisition
software, increasing the overall flexibility of the system and the creation of specific acquisition schemes and
configurations. The system works with a multi-electrode configuration of up to 48 channels but it was designed
to be upgraded to an arbitrary large number of electrodes by connecting additional multiplexer cards (> 96
electrodes). The acquisition was optimized for multi-channel measurements so that the overall time of acquisition
is dramatically reduced compared to the single channel instrumentation.
The accuracy and operation were tested under different conditions. The results from preliminary tests show that
the system is able to clearly identify objects discriminated by different resistivity. Furthermore, measurements
carried out during internal erosion simulations demonstrate that even small variations in the electrical resistivity
can be captured and these changes can be related to the erosion processes
Organizational innovation in energy companies: a literature review
No full textInstitutional, technological, and competitive change poses a threat to established ways of managing and organizing processes, and activities within the electric utilities sector. These challenges require the ability to innovate organizational structures, human resource management strategies, and leadership competencies to remain at the forefront of complex process and product innovation in different domains, and across different national and global contexts. While the required change exerts a growing pressure on top managers, and Human resource managers more directly, research has not analyzed in detail patterns of organizational innovation, competence development, and their consequences for competitive positioning, and success in the coming years. Our paper is part of a research project that has been launched in partnership with Enel Foundation to fill this gap. The overall project is based on an extensive analysis of the existing literature, coupled with qualitative interviews with key actors in the industry to develop a global survey that will be sent to the most relevant players in the industry. In this paper, we describe what organizational innovation is, and how it has been subject to study. We then move to analyze the existing literature on Electric utilities, and describe some of the key players. Finally, we present our questionnaire and the sampling that will be used in collecting the data
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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