Evaluation of lithostratigraphic units and groundwater potential using the resolution capacities of two different electrical tomographic electrodes at dual-spacing

The selection of a choice electrode is pertinent to attenuating noise and improving geophysical tomographic inversion results. Besides, the detailed understanding of the geodynamic condition of subsurface formation is crucial to sustainable potable groundwater abstraction. Hence, the subsurface lithostratigraphic units and groundwater potential of two sites (i.e., Site 1 and Site 2) within the Universiti Sains Malaysia were evaluated using borehole-constrained electrical resistivity tomography (ERT) and induced polarisation (IP) tomography. Both methods employed the resolution capacities of stainless-steel and copper electrodes at dual-spacing. The ERT and IP field data and inversion results for copper electrodes were generally robust due to the generated higher positive data points and lower RMS errors, percentage relative differences, and mean absolute percentage errors (MAPE) than the stainless-steel electrodes, especially at Site 1 with a profile length of 200 m and an electrode spacing of 5 m. However, both electrodes tend to produce inversion models with almost the same parameters at Site 2, using half the profile length and electrode spacing of Site 1, i.e., 100 m and 2.5 m, respectively. Thus, the sensitivities and resolution capacities of the tomographic electrodes are heavily influenced by electrode spacing, profile length, amount of injected current, and depth of investigation. The borehole lithostratigraphic units, typically sandy silt, sand, and silty sand, have good correlations with the ERT and IP inversion results. The variability in observed resistivity and chargeability values were due to heterogeneous weathered materials and saturating water fills within the fractured and deeply-weathered granitic bedrock, with <200 Ωm and a chargeability of >1.8 msec. The models' median depth of >40 m mapped for the weathered and/or fractured sections was suggestive of high groundwater-yielding capacity in boreholes to sustain a part of the university community.

Contact Engineering Approach to Improve the Linearity of Multilevel Memristive Devices

Physical mechanisms underlying the multilevel resistive tuning over seven orders of magnitude in structures based on TiO2/Al2O3 bilayers, sandwiched between platinum electrodes, are responsible for the nonlinear dependence of the conductivity of intermediate resistance states on the writing voltage. To improve the linearity of the electric-field resistance tuning, we apply a contact engineering approach. For this purpose, platinum top electrodes were replaced with aluminum and copper ones to induce the oxygen-related electrochemical reactions at the interface with the Al2O3 switching layer of the structures. Based on experimental results, it was found that electrode material substitution provokes modification of the physical mechanism behind the resistive switching in TiO2/Al2O3 bilayers. In the case of aluminum electrodes, a memory window has been narrowed down to three orders of magnitude, while the linearity of resistance tuning was improved. For copper electrodes, a combination of effects related to metal ion diffusion with oxygen vacancies driven resistive switching was responsible for a rapid relaxation of intermediate resistance states in TiO2/Al2O3 bilayers.

OPTIMALISASI PARAMATER RESISTANCE SPOT WELDING UNTUK PENGELASAN TIGA TUMPUK LEMBAR BAJA SPCC

In the automotive industry, the latest breakthroughs and innovations are strongly influenced bymaintaining and increasing production results so that the use and application of technology is anabsolute must, as is welding technology. Thin sheet-shaped components are found in many car bodies.One of the methods used in joining plate sheets is to use the resistance spot welding method, which is awelding process that is only carried out at a certain point using copper electrodes. In the welding method,maintaining quality in order to produce products and services that can meet the needs and expectationsof consumers related to the product's life time or service. SPCC steel (Cold Roller Stell Sheet) is one ofthe most widely used materials in car body welding applications. The characteristics and mechanicalproperties of SPCC steel from the results of the three-sheet welding were examined using the parametersof welding current, welding time, welding distance. The results showed that the increase in current wouldaffect the diameter of the electrode traces and the nuggets that were formed. The greater the current used,the larger the diameter of the trail, so that the optimum pull-shear load is at a current of 6.5 kA at adistance of 20mm with a value of 365.53 MPa, also the highest hardness value is in the nugget area witha hardness value of 595, 14 HVN at a current of 6.5 kA and from the results of measuring grain diameterin microstructural testing for the HAZ area the best at a welding current of 6.5 kA. Because the smallerthe weld grain diameter, the greater the strength of the weld joint. Then the data from the results of theshear-shear test are analyzed using the Taguchi method, and the most effective parameters in the tensilesheartest with a combination of A (6.5) B (1.5) C (15) and from the experimental results for tensile loads.slide obtained 397 MPa.

Electrochemical method of obtaining copper (II) oxide powders in alkaline electrolyte

Within the framework of these studies, an electrochemical method for the synthesis of highly dispersed powders of copper compounds in aqueous solutions of alkalis is presented. The factors influencing the rate of production of nanoscale copper (II) oxide particles are determined. It is shown that during the anodic oxidation of copper by direct current, the speed of highly dispersed powders formation depends on current density, the nature of alkali cation, and the concentration of electrolyte solution. The mass loss of copper electrodes in NaOH solution is higher than in solutions of potassium hydroxide and lithium hydroxide by 10% and 12%, respectively. This experiment suggests that the studied alkalis act similarly on the anodic behavior of copper and the nature of cation does not significantly affect the speed of anodes destruction. The change in the concentration of alkali solution practically does not affect the mass loss of copper electrodes. The speed of copper oxidation remains almost constant over time, but noticeable weight loss and, accordingly, the speed of copper dissolution is achieved within 15 minutes. The speed of copper oxidation does not depend on current density. It is determined by the amount of electricity that has passed. The current density of 1 A/cm2 can be considered optimal.

Synergistic Effect of Magnetite and Bioelectrochemical Systems on Anaerobic Digestion

Conventionally, the anaerobic digestion of industrial effluent to biogas constitutes less than 65% methane, which warrants its potential methanation to mitigate carbon dioxide and other anthropogenic gas emissions. The performance of the anaerobic digestion process can be enhanced by improving biochemical activities. The aim of this study was to examine the synergistic effect of the magnetite and bioelectrochemical systems (BES) on anaerobic digestion by comparing four digesters, namely a microbial fuel cell (MFC), microbial electrolysis cell (MEC), MEC with 1 g of magnetite nanoparticles (MECM), and a control digester with only sewage sludge (500 mL) and inoculum (300 mL). The MFC digester was equipped with zinc and copper electrodes including a 100 Ω resistor, whereas the MEC was supplied with 0.4 V on the electrodes. The MECM digester performed better as it improved microbial activity, increased the content of methane (by 43% compared to 41% of the control), and reduced contaminants (carbon oxygen demand, phosphates, colour, turbidity, total suspended solids, and total organic carbon) by more than 81.9%. Current density (jmax = 25.0 mA/m2) and electrical conductivity (275 µS/cm) were also high. The prospects of combining magnetite and bioelectrochemical systems seem very promising as they showed a great possibility for use in bioelectrochemical methane generation and wastewater treatment.

On problem of using copper electrodes to maintain protection against corrosion of steel hulls of ships and vessels

The paper focuses on the reasons for the lack of proper control of the operation of the electrochemical protective systems of sea vessels, such as the absence of convenient technical equipment, primarily the reference electrodes, as well as the imperfection of the silver chloride reference electrode. There is considered the approach to the development of easy-to-use reference electrodes. A standard silver chloride reference electrode was used as the first electrode; experimental electrodes made of a copper wire strand stripped of insulation were used as the second and third electrodes. The experimental vessel is docked in the commercial port of Petropavlovsk-Kamchatsky. The corrosion protection of the ship’s hull was evaluated by measuring the potentials between the metal hull and the reference electrode at a given point. The measurements were performed at a time interval from 06/10/2021 to 06/18/2021, evaluating the control of the hull corrosion protection was made by taking 50 successive measurements, which were entered into the control tables. It has been stated that the results of ship’s hull sacrificial protection control by using experimental copper electrodes from cabling comply with the regulatory requirements. The ship’s crew didn’t have any financial, organizational or technical problems, which could usually arise from the operation of standard silver chloride reference electrodes. It has been inferred that using regulated and non-regulated electrodes in the organization of corrosion control on ships and metal offshore structures is possible.

Performance Evaluation of Copper and Stainless-steel Electrodes in Electrical Tomographic Imaging

Geophysicists use electrical methods to investigate and characterise the earth’s subsurface geology. This study aims to evaluate the performance of copper and conventional stainless-steel electrodes in subsurface tomographic investigations using electrical resistivity tomography (ERT) and induced polarisation (IP) at two sites in Penang, Malaysia. Site 1 and Site 2 employed profile lengths of 200 m and 100 m, with electrodes spacing of 5.0 m and 2.5 m, respectively. In the results of the final data inversion, it was observed that the ERT and IP tomographic models of Site 1 have the best convergence limits with percentage relative differences (copper as reference model) ranging from –70% to 70%, while Site 2 recorded –8% to 8%. The electrodes performance evaluation showed that population root mean square (RMS) error and population mean absolute percentage error (MAPE) of data points between copper and stainless-steel electrodes yielded large values for Site 1 with values above 28% and that of Site 2 was less than 4%. Hence, copper (good electrical conductivity and non-polarisable) electrodes have improved the quality and quantity of infield data which give low values of population RMS error and population MAPE compared to conventional stainless-steel electrodes, especially for large unit electrode spacing surveys. Most notably, this work has contributed to the understanding of the capability of copper electrodes in providing precise and reliable inversion models for subsurface tomographic investigations in pre- and post-land uses (engineering work), hydrogeology/groundwater, environmental studies, etc.