1,720,980 research outputs found
ON THE INFLUENCE OF CHANNEL TORTUOSITY ON ELECTRIC FIELDS GENERATED BY LIGHTNING RETURN STROKES AT CLOSE DISTANCE
No full textIn this paper the results of the estimated electric field associated with tortuous lightning paths at close distance (50 m to 500 m) are shown. Such results are compared with experimental data available in the literature and are illustrated along with a quantitative analysis of the field waveforms and their frequency spectra. The limits of the usual straight-vertical channel assumption and the influence of tortuosity at different azimuth and distances from the lightning channel base are also highlighted
Model of the 2 × 25 kV high speed railway supply system taking into account the soil-air interface
No full textNumerical Behavior of Models of Composite Materials in E'NDT at 'Low' Frequencies
No full textIn this paperthe numerical modeling of composite materials in view of Nondestructive Testing is considered. The composite material is assumed to be modeled at the macroscopic scale by a possibly complex dielectric permittivity tensor. The material is probed by means of an electromagnetic field having wavelength much larger than the relevant geometrical dimensions. As well known, the numerical modeling is critical especially in this “low-frequency” regime where a strong ill-conditioning of the relevant stiffness matrix typically occur (the so-called low-frequency breakdown problem). The proposednumerical model is robust w.r.t. this underlying ill-conditioning
Numerical assessment of a novel technique for the reconstruction of 3D magnetic fields in tokamaks
No full textGoing 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
A finite element model of abdominal human tissue for improving the accuracy in insulin absorption assessment: A feasibility study
No full textPreliminary sizing and operation analysis of the DTT electrical network system
No full textThe Divertor Tokamak Test (DTT) facility plays a crucial role in the European Roadmap for fusion energy. Its primary goal is to explore solutions for the power exhaust in the DEMO divertor. The two most power-consuming systems in DTT are: the Heating and Current Drive systems, which deliver up to 45 MW of power to the plasma (totaling to approximately 150 MVA installed), and the coil Power Supply System. An Electrical Network System was designed for this purpose, fed at 150 kV by the National Grid (NG), requiring up to 300 MVA. The large power time derivatives in a very short time, peculiar of the abovementioned loads, hardly allow for the adoption of solutions to stabilize the voltage. On the other hand, such loads are controlled by electronic converters with specific needs on the waveform quality but also with the capability to partially compensate the voltage fluctuations. To this end, these loads are grouped in a sub-network with less stringent requirements than other loads. To validate the preliminary design choices, a simulation model was implemented in the DIgSILENT PowerFactory software. This paper presents the results of preliminary static and dynamic simulations of the ENS, to validate adequate sizing, stability, and impact towards the NG
A finite element model of abdominal human tissue for improving the accuracy in insulin absorption assessment: A feasibility study
Full text linkA Finite Element Model of the human abdomen biomechanics for patients undergoing diabetes therapies was developed. In particular, FEM was used to improve a previous insulin absorption measurement method based on bioimpedance spectroscopy (BIS). As a matter of facts, the noise introduced during the insulin injection phase significantly affects the BIS measurements. The noise, due to the pressure exerted on the abdomen tissue, arises sensibility issues on the signal correlated to the drug presence under the skin. In this study, the abdomen is modeled with three layers (skin, fat and muscle). A feasibility study about the decoupling of the mechanical deformation and the electrical dynamics is presented in order to model the effect of mechanical uncertainty sources (e.g., pressure exerted during the injection phase and/or breathing) on the impedance measurements. The proposed simplified model is realised by referring to the average values of skin, fat and muscle thickness, along with mechanical abdomen parameters al-ready presented and validated in scientific literature. The obtained results confirm the possibility to decouple me-chanical and electrical analyses when the excitation voltage is characterized by a frequency higher than 1 kHz. The results will be used to improve the accuracy of an exhaustive approach, already developed by the authors, for real-time insulin absorption measurement
Preliminary Investigation of the impact of mechanical stresses on bioimpedance spectroscopy-based insuline bioavailability assessment
No full textIn the framework of bioimpedance spectroscopy-based insulin bioavailability assessment, a preliminary experimental campaign aimed to investigate the relationship between applied pressure and impedance variation was conducted. The experimental tests were carried out on a volunteer's abdomen in a controlled environment. They exploited four pre-gelled electrodes and a non- invasive instrument built with off-the-shelf components, namely DUSM, previously successfully used by the authors in different biomedical applications. Experimental results are compatible with the scientific literature, and show a progressive increase of the impedance magnitude according to an increasing external force which is comparable to the typical mechanical action of an insulin injection
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