MODELLING APPROACH IN THE DEVELOPMENT OF ELECTROCHEMICAL 3D-PRINTING SYSTEMS

Background. New 3D-printing technologies are becoming more and more advanced and widespread in the twenty-first century. One of the types of 3D-printing is electrochemical 3D-printing, in which electrochemical deposition of metals is used to form metal products. Potentially, this method of 3D-printing is the most energy efficient, the least material-intensive, and also the easiest to implement. There- fore, research aimed at creating and improving systems for electrochemical 3D-printing is promising. Objective. The aim of the paper is to study the influence of geometric parameters of the system and the composition of the elec trolyte on the current distribution on the surface of the working electrode (cathode) in the process of electrochemical 3D-printing, and therefore print accuracy. Methods. Volt-amperometric measurements and multi-physical computer modelling of the secondary distribution of current density using COMSOL MULTYPHYSICS for different geometric parameters of the working part of the 3D-printer and different composition of electrolytes. Results. Based on the simulation of the secondary distribution of current density in copper sulphate electrolyte, it was found that the content of sulfuric acid in the solution should be minimal in order to purposefully deposit metal in the area directly under the working electrode. Based on the condition of maximum energy efficiency and accuracy of electrochemical 3D-printing, the optimal ratio between the deposition surface (cathode) and the edge of the non-conductive body of working electrode was found. Conclusions. It was established that in order to narrow the zone of current scattering (increase the accuracy of electrochemical 3D-printing) it is necessary to ensure the optimal ratio between the diameter of the capillary and the edge of the non-conductive body of the counter electrode. It was shown that this ratio should not be less than 5 [mm / mm]. Further applied research will be aimed at adaptation and practical implementation of the obtained model data, optimization of the electrolyte composition and design of the 3D-printer.

Root system monitoring using a mise-à-la-masse (MALM) extension to time-domain IP

<p>The development, architecture, and activity of the plant root system has a key role in plant-soil-water interactions, and thus, in plant ecology both in agricultural and natural systems. The characterization of the flow of electric current in the root-soil system may provide non-invasive methodologies to observe the state and dynamics of this critical zone hidden in the shallow subsurface.</p><p>Inversion of Current source density (CSD) from Mise-a-la-masse (MALM) surveys provides a straightforward way to describe the shape of a conductive body that charges up. While numerous studies show a correlation between root mass density and electrical capacitance (Ehosioke et al., 2020), physical proofs of the underlying assumptions of such concepts are still missing. In particular, some authors questioned the hypothesis that the xylem behaves as a continuous conductive body with regard to its physiological state. Application of the MALM in conjunction with CSD helps distinguish the current pathway through the root system (Mary et al., 2019; Peruzzo et al., 2020).</p><p>As roots are electrically polarisable, their responses depend on the frequency of the current injection. Extending the CSD inversion to secondary voltages produced by secondary currents (after shutting down the primary current) may provide insights into transient phenomena associated with the polarization of the roots.</p><p>Based on a Self-Potential (SP) processing algorithm (Shao et al., 2018), we build and test a new inversion scheme of secondary voltages using synthetic models. Small-scale laboratory experiments are in progress on grapevine cuttings placed in water-filled rhizotrons. Root growth will be monitored using MALM in TDIP domain.  </p>

EXPERIMENTAL STUDY OF EDDY CURRENT BRAKING APPLICABLE TO GRAVITY ROLLER CONVEYOR

One of the main elements of safe operation of gravity conveyors used in gravity racks for pallets is the brake roller. The most promising design is a brake roller of magnetic (eddy current) type. A mathematical model of the process of moving pallets on a magnetic brake roller is developed. The equation of the speed of movement of the pallets on the brake magnetic roller obtained. The main parameter that determines the braking functions of the brake magnetic roller, and therefore the speed of movement of the pallet on the gravity roller conveyor is the coefficient of roller, experimental studies have been carried out to determine the magnetic viscosity coefficient. It was found that the coefficient of magnetic viscosity decreases with increasing air gap between the conductive body and the permanent magnets, and this dependence has a power-law character; decreases by 10... 25% with increasing speed of the conductive body; independent of changes in the distance between the centers of the conductive body and the permanent magnet; decreases when an edge effect appears in accordance with the air gap.

Source constraints for the 2015 phreatic eruption of Hakone volcano, Japan, based on geological analysis and resistivity structure

On June 29, 2015, a small phreatic eruption occurred in the most intensively steaming area of Hakone volcano, Japan. A previous magnetotelluric survey for the whole volcano revealed that the eruption center area (ECA) was located near the apex of a bell-shaped conductive body (resistivity < 10 Ωm) beneath the volcano. We performed local, high-resolution magnetotelluric surveys focusing on the ECA before and after the eruption. The results from these, combined with our geological analysis of samples obtained from a steam well (500 m deep) in the ECA, revealed that the conductive body contained smectite. Beneath the ECA, however, the conductive body intercalated a very local resistive body located at a depth of approximately 150 m. This resistive body is considered a vapor pocket. For the 2 months prior to eruption, a highly localized uplift of the ECA had been observed via satellite InSAR. The calculated depth of the inflation source was coincident with that of the vapor pocket, implying that enhanced vapor flux during the precursory unrest increased the porosity and vapor content in the vapor pocket. In fact, our magnetotelluric survey indicated that the vapor pocket became inflated after the eruption. The layer overlaying the vapor pocket was characterized by the formation of various altered minerals, and mineral precipitation within the veins and cracks in the layer was considered to have formed a self-sealing zone. From the mineral assemblage, we conclude that the product of the 2015 eruption originated from the self-sealing zone. The 2015 eruption is thus considered a rupture of the vapor pocket only 150 m below the surface. Even though the eruption appeared to have been triggered by the formation of a considerably deeper crack, as implied by the ground deformation, no geothermal fluid or rocks from significantly deeper than 150 m were erupted.

An airborne electromagnetic system with a three-component transmitter and three-component receiver capable of detecting extremely conductive bodies

Extremely conductive bodies, such as those containing valuable nickel sulfides, have a secondary response that is dominated by an in-phase component, so this secondary response is very difficult to distinguish from the primary field emanating from the transmitter (because by definition they are identical in temporal shape and phase). Hence, an airborne electromagnetic (AEM) system able to identify the response from the extremely conductive bodies in the ground must be able to predict the primary field to identify and measure the secondary response of the extremely conductive body. This is normally done by having a rigid system and bucking out the predicted primary (which will not change significantly due to the rigidity). Unfortunately, these rigid systems must be small and are not capable of detecting extremely conductive bodies buried deeper than approximately 100 m. Another approach is to measure the transmitter current and geometry and subtract the primary mathematically, but these measurements must be extremely accurate and this is difficult or expensive, so it has not been done successfully for an AEM system. I exploit the geometric relationship of the primary fields from a three-component (3C) dipole transmitter. If the transmitter is mathematically rotated so that one axis points to the receiver, then linear combinations of the fields measured by a 3C receiver can be combined in such a way that the primary fields from the transmitter sum to zero and cancel. Alternatively, the measured transmitter current and response could be used to estimate the transmitter-receiver geometry and then to predict and remove the primary field. Any residual must be the secondary coming from a conductive body in the ground. Hence, extremely conductive bodies containing valuable minerals can be found. An AEM system with a 3C transmitter and a 3C receiver should not be too difficult to build.