Electrical Test Research Articles

Arc erosion behavior of Ag-8 wt.%ZrO2 contact materials with CuO additions

To clarify the effect of CuO on the arc erosion behavior of AgZrO2 contact materials, the Ag-8 wt.%ZrO2 contact materials without and with CuO addition were prepared by the combination of three-dimensional vibrating mixing and hot-pressing sintering, and the electrical contact tests were performed 5000 times on a JF04D electrical contact testing system. The effect of CuO additive on the arc erosion behavior of Ag-8 wt.%ZrO2 contact material was studied, and the arc erosion mechanism was discussed as well. The results show that an appropriate CuO addition can significantly improve the hardness, electrical conductivity and arc erosion resistance of Ag-8 wt.%ZrO2 contact material. At 0.5 wt%CuO, the optimal combination of relative density, hardness and electrical conductivity can be achieved, which are 99.48 %, 79.0 HV and 79.3 %IACS, respectively. Furthermore, the Ag-8 wt.%ZrO2 contact material with 0.5 wt%CuO addition exhibits the lowest arc energy and shortest arc duration, least mass loss, and silver splashing as well as the formation of pores are also significantly inhibited, displaying excellent arc erosion resistance. This can be ascribed to the improved electrical conductivity and enhanced interface bonding together with CuO decomposition under high temperature arc.

Development of High Strength and Super Electrical Conductive Cu-3Ti-2Si-1.5Ni-xNb Alloys

The study explored the mechanical and electrical behavior of niobium-doped Cu-3Ti-2Si-1.5Ni alloys by Scanning Electron Microscopy (SEM), Energy-Dispersive Spectroscopy (EDS), micro-Vickers hardness, and electrical conductivity tests. The stir-casted alloys underwent solution treatment at 900 °C/5 h and cooled in air. Results showed that niobium additions led to significant improvements in the properties of the parent alloy. The ultimate tensile strength, yield strength, hardness, and electrical conductivity reached maximum values of 528 MPa, 437 MPa, 358 HV, and 58.5 %IACS, respectively, at 1.1 wt% Nb addition. The enhancements were attributed to increased precipitation of second phases and refined grain structure. However, the percentage elongation decreased with niobium addition. These findings demonstrate that Cu-3Ti-2Si-1.5Ni alloys with niobium nanopowder exhibit a promising balance of mechanical and electrical performances, making them suitable for advanced engineering applications.

Investment Decision-Making to Select Converted Electric Motorcycle Tests in Indonesia

Investment Decision-Making to Select Converted Electric Motorcycle Tests in Indonesia

3D printed poly(lactic acid)/poly(ε-caprolactone)/graphene nanocomposite scaffolds for peripheral nerve tissue engineering

This research aimed to fabricate and evaluate Poly(lactic acid)/poly(ε-caprolactone)/graphene (PLA/PCL/G) nanocomposite scaffolds for peripheral nerve tissue engineering. To achieve this goal, scaffolds were fabricated using the fused deposition modeling (FDM) 3D printing method with the following compositions: 50 wt% PLA-50 wt% PCL (PLA-PCL), 98.5 wt% PLA-1.5 wt% G (PLA-G), 98.5 wt% PCL-1.5 wt% G (PCL-G), and 50 wt% PLA-48.5 wt% PCL-1.5 wt% G (PLA-PCL-G). The microstructure and chemical composition of the scaffolds were characterized using SEM, XRD, and FTIR. SEM images revealed that the PLA-PCL-G scaffold exhibited a more regular and uniform morphology compared to the others, with the PLA-PCL scaffold displaying the least regularity. The porosity percentage and pore size of the scaffolds ranged from 50 % to 86 % and 300 to 500 µm, respectively. Mechanical properties were assessed via compression testing, indicating that the elastic modulus of the PLA-PCL-G scaffold was approximately 22.36 MPa, suitable for peripheral nerve tissue applications. Electrical conductivity testing showed that PLA-PCL-G had a conductivity of about 8.2E-5 S/cm, similar to PLA-G. Biodegradability was evaluated by immersing samples in phosphate-buffered saline (PBS), revealing that PLA-PCL-G exhibited a weight loss of approximately 1.3 % and a degradation rate of 0.14 mm/day over four weeks, closely matching peripheral nerve tissue regeneration rates. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay results confirmed that PLA-PCL-G scaffolds were non-cytotoxic to PC12 cells. Overall, these findings suggest that the 50 wt% PLA-48.5 wt% PCL-1.5 wt% G scaffold holds promise for peripheral nerve tissue engineering applications.

A 12-month randomized controlled trial to assess the efficacy of revitalization of retreated mature incisors with periapical radiolucency in adolescents

The use of regenrative endodontics is restoring the health status of the root canals of retreated mature teeth is a novel approach. Therefore, the current trial aimed to compare the effectiveness of regenerative endodontic procedures (REPs) to non-surgical root canal retreatment (NS-RCR) in reducing periapical radiolucency over one year for the retreatment of mature incisors with periapical periodontitis. The secondary purpose was to assess clinical success and regain pulp sensibility. A parallel randomized controlled trial, 66 mature incisors with periapical radiolucencies were randomly divided into two equal groups and retreated with either REPs or NS-RCR. At baseline and after 6 and 12 months, teeth were assessed clinically and radiographically using a periapical index (PAI). The Mann–Whitney test was used to analyze nonparametric PAI scores. The Electric pulp test readings were analyzed using the repeated measure analysis of variance (ANOVA). Over the follow-up intervals, there was no significant intergroup difference in the PAI medians, the majority of the teeth displayed a reduction in periapical radiolucency. At the end of the follow-up period, the clinical successes for the REP and NS-RCR groups were 93.9% and 97%, respectively (p = 0.555). Positive pulp sensibility was recorded in 54.54% of cases in the REPs after 12 months. Both approaches showed a comparable diminishing of periapical radiolucencies and equivalent clinical results. A conventional, non-surgical endodontic retreatment may not always be necessary.

Phase-Change/Salt-Based Slow-Release Composite Material for Anti-Icing and Snow-Melting

Currently, self-desiccating asphalt mixtures on roads mainly incorporate phase-change materials or salt-based slow-release agents individually for de-icing. However, pure phase-change material mixtures have limited anti-freezing efficiency and short heat-release duration, making them impractical for large-scale snow melting; meanwhile, salt-based slow-release agents suffer from rapid deterioration in de-icing performance. To address these issues encountered, herein, we introduce the phase-change/salt-based slow-release composite materials via the integration of these two materials and investigate their pavement and de-icing performance with the asphalt mixture. For the pavement performance, the optimal asphalt–aggregate ratio for the anti-icing asphalt mixture was found to be 5.1% For anti-bonding and de-icing performance, the electrical conductivity tests, bonding pull-off tests, and interfacial contact melting experiments were conducted. The results indicate that the latent heat of the TH-ME5 (phase-change material) can delay the decrease in environmental temperature and inhibit salt release from T-SEN (salt-based slow-release material), thereby extending the lifespan of the anti-icing asphalt mixture. These results demonstrate that the synergistic effect between the two components of the composite material not only enhance the snow-melting and de-icing performance of the asphalt pavement but also prolong the snow-melting time of the pavement in a low-temperature environment.

Enhancing the electrical performance of AgNi contact material by doping Ag2WO4

To improve the anti-welding ability of AgNi contact material, the Ag2WO4 was doped for the Ag-8 wt%Ni contact material. The electrical contact tests were performed at 36 V/25A for 5000 operations on an electrical testing system, and the welding and material transfer behaviors were studied. The results show that doped Ag2WO4 significantly decreases the welding frequency (115 times to 34 times) and welding force (max 0.49 N to 0.13 N) for the Ag-8 wt%Ni contact material, which is derived from the fine eroded morphology acted by Ag2WO4. Furthermore, doping Ag2WO4 increases the material transfer from anode to cathode, which can be attributed to the influence of Ag2WO4 on the plasma ion density, and the balance of metallic and gaseous arcs reflected from the arc power.

Experimental and numerical simulation studies of electrical resistance of cementitious materials under varying temperature history

Many in-service concrete structures are normally exposed to varying temperature condition. The time-dependent and non-uniform temperature distribution in concrete structures could affect the accurate assessment of their electrical properties. Therefore, the influences of temperature change over time and the spatial variation in temperature on the measured electrical resistance of cementitious materials are still in need of investigation. The coupled thermal-electrical responses of two types of cementitious materials under varying temperature history were investigated by a series of thermal and electrical tests in this study. Then a coupled thermal-electrical finite element (FE) model was developed to simulate the coupled thermal-electrical responses. The results show that the input direct current has a minor effect on the measured electrical resistance by embedded four-probe method and the specimen temperature when it is no greater than 3 mA. The relationship between the measured temperature at 10-mm depth of the specimen and the apparent resistance is well captured by a linear equation. The coupled thermal-electrical finite element model can predict well the developments of specimen temperature and apparent electrical resistance under varying temperature history. The FE results reveal that the non-uniform temperature variation results in the redistribution of electrical current within the tested specimen. However, electrical field between the two inner electrodes is always uniform when the embedded four-probe method is used, which is not affected by the non-uniform temperature variation.

A granularity data method for power frequency electric and electromagnetic fields forecasting based on T–S fuzzy model

The impact of electromagnetic radiation generated by signal transmission base stations and power stations to meet the needs of communication equipment and energy consumption on the environment has caused people concerns. Monitoring and prediction of electric and magnetic fields have become critical tasks for researchers. In this paper, we propose a granularity data method based on T–S (Takagi–Sugeno) fuzzy model, named fuzzy rule-based model, which utilizing finite rules that are determined by the deviations between the predicted values and the true values after the data goes through a granulation-degranulation mechanism, to predict the intensity of power frequency electric field and electromagnetic field. A series of experiments show that fuzzy rule-based models have better robustness and higher prediction accuracy in comparison with several existing prediction models. The improvement of the performance of the fuzzy rule-based model quantified in terms of Root Mean Squared Error is 20.86%, 51.91%, 62.28%, 65.10%, and 71.92% in comparison with that of the Ridge model, Lasso model, and a family of support vector machine model with different kernel functions, including linear kernel (SVM-linear), radial basis function (SVM-BRF), polynomial kernel (SVM-polynomial) respectively, on the electromagnetic field testing data, and 37.42%, 55.16%, 58.79%, 59.28%, 64.27% lower than that of the Ridge model, Lasso model, SVM-linear model, SVM-BRF model and SVM-polynomial model on the power frequency electric field testing data.

Sustainable microwave processing and surface characterization of powdered tungsten reinforced copper metal matrix (Cu-Wx) castings

The present work focuses on in-situ melting and casting of powdered copper metal matrix composites using a microwave hybrid heating approach. The composites of copper metal matrix are developed in such a way that the conductivity is least affected and related mechanical properties like flexural strength, tensile strength and hardness can be improved. Present work reports the processing and characterization of tungsten (W) powder reinforcement copper metal composites with weight percentages of W varied from 1%, 3% and 5%. The complete mechanism of interactions of Cu-Wx (x = 1%, 3% and 5% weight of copper powder) based composite powders with microwave heating is explained. The processed composite castings are characterized metallurgically through metallurgical microscope, SEM/EDS and XRD analysis; which reveals even dispersion of W particles in Cu matrix phase with some agglomerations. Some intermetallic formations are observed due to intense heating characteristics of microwaves. Further, mechanical and electrical characterizations of developed castings are carried out through Vicker's microhardness testing and electrical conductivity tests respectively. Addition of reinforced particles in metal matrix leads to an increase in microhardness on the expense of conductivity of composite. The 5% W addition led to 1.5 times increase in microhardness and 18.25% increase in resistivity. The mechanical testing revealed that the 5% W reinforced casting led to ∼22% higher ultimate tensile stress in comparison to pure copper casting. However, there was a significant decrease in ductility of metal matrix composites.

Design of a power processing unit with integrated telemetry for a vacuum arc thruster as part of the SeRANIS mission

In this work the design and development of a power processing unit for a vacuum arc thruster is presented. The thruster is part of the Seamless Radio Access Networks for Internet of Space (SeRANIS) mission of the University of the Bundeswehr Munich, which will work as first multifunctional laboratory in orbit with public access. In addition to the basic functionality of generating a voltage peak for igniting the thruster, the power processing unit is equipped with techniques for controlling the ignition sequence and monitoring desired key values. The ignition procedure starts with generating the first trigger signal up to the point where a full-blown plasma is established. The PPU guarantees reliable performance by blocking every additional incoming signal while the ignition sequence is under way and the separation of the satellite’s power bus before the thruster discharges. The status of the power processing unit is constantly controlled and information is provided whether ignition was successful or not. The functionality of this circuit is based on simulation before assembly and testing. In addition, the presented system was designed to pass a test cycle of mechanical, thermal and electrical tests before being declared ready for the space mission.

Research on the method of air gap clearance selection for bushing at high-altitude areas

Abstract As an important component of the core equipment of the UHV substation, the operation reliability of the bushing is directly related to the safe operation of the main equipment. There are some technical problems in the development of casing in the Sichuan-Chongqing project, such as technical problems at high altitudes and a lack of relevant experience in the correction of air gap and equipment external insulation altitude. Therefore, there is an urgent need to research the selection of gap distance for UHV AC substation bushing electrical characteristics test in high altitude areas. In this paper, based on the standard meteorological conditions and the rod-plate gap switching impulse discharge test data at an altitude of 4300 m, the minimum gap distance of UHV AC substation bushing withstanding 1800 kV and 1950 kV under different methods is obtained. The results show that by comparing the two calculation methods, the minimum distance calculation method of the true test combined with the gap coefficient method avoids the error of altitude correction, and the minimum gap distance is reduced by 7.84%-14.17% compared with the former. The research content can provide a reference for selecting the dry arc distance of the casing. The next step should be to carry out the discharge characteristic test of the true-size electrode at a high altitude, so as to simulate the field situation more realistically and provide more powerful technical support for the project.

A deformation mismatch strategy enables over 120% stretchability of encapsulated serpentine silicon strips for stretchable electronics

AbstractIt is significant to develop stretchable electronics based on silicon materials for practical applications. Although various stretchable silicon structures have been reported, electronic systems based on them exhibit limited stretchability due to the constraints between them and polymer substrates. Here, an innovative strategy of deformation mismatch is proposed to break the constraints between silicon structures and polymers and effectively reduce the strain concentration in silicon structures. As a result, encapsulated serpentine silicon strips (S‐Si strips) achieve unprecedented stretchability, exceeding 120%. The encapsulated S‐Si strip also exhibits remarkable mechanical stability and durability, enduring 100 000 cycles of 100% stretch without fracture. The effect of key parameters, including the central angle, thickness, and width of the S‐Si strip, on the deformation mismatch is revealed through combing experiments and theoretical analysis, which will guide the rational implementation of the deformation mismatch strategy. Electrical testing showcases the strain‐insensitive nature and good electrical stability of encapsulated S‐Si strips, benefiting practical applications. This work provides a new paradigm of silicon materials with excellent stretchability and will facilitate the development of stretchable electronics.

Non-intrusive demand response management strategy to mitigate the impacts of residential electric vehicle charging on distribution systems

The proliferation of electric vehicles (EVs) is expected to significantly increase electricity demand. However, if left uncontrolled, the aggregated demands from EVs have the potential to affect the power balance and quality of distribution systems adversely. Given this complex framework, this work presents a non-intrusive demand response management (DRM) approach to mitigate the impacts of residential EV charging on distribution systems. After analyzing a database comprising 157,250 operations, 74,316 charging patterns described by 17 attributes are obtained. These patterns are used for sampling EV fleets distributed in the Institute of Electrical and Electronics Engineers (IEEE) 33-bus test system. From scenarios with different levels of EV penetration, critical regions in the demand curve are identified, while actions for demand response (DR) are taken. Despite the increase in total energy consumption, larger EV fleets have greater potential for participation in DR. At a penetration level of 5%, it is not possible to shift excess energy consumption during the peak period, even with the participation of about 47% of the fleet, which corresponds to all users involved in EV charging during the peak period. At a penetration level of 50%, the energy goal can be achieved with the participation of about 15% of the fleet. In this latter scenario, the proposed management strategy can achieve a peak demand reduction of 9–11%.

Peculiarities of identification and customs commodity examination of children’s goods

Special attention is paid to the issue of identification and safety of children's products, which is aimed at ensuring the safety and quality of this category of goods. In the scientific article, the issue of classification of goods of group 95 in accordance with the Ukrainian Commodity Nomenclature of Foreign Economic Activity was considered, and a study of the practice of appointing customs examinations was conducted. The main identifying features of the classification of scooters in the category of goods for children are: purpose; design features, their modification; type of movement; number and diameter of wheels; type of ride Attention should also be paid to the following identification features of children’s goods, which are necessary both during customs control and during the examination of toys: the size of the toy, the material of manufacture, design features, application and main functional purpose. The development and improvement of current methods of identification of toys will simplify the procedure of their inspection and increase the objectivity of the results. The work summarizes the ways to classify children’s scooters in the procedure of commodity examination. The diagnostic tasks of the forensic commodity examination to determine safety, compliance with standards, which the expert must solve during the study of a children’s scooter, are defined. State-of-the-art research methods, in particular, visual inspection, functional tests, measurement of geometric parameters, mechanical tests, chemical analysis of materials, technical expertise, safety tests, computer modeling and analysis, electrical and electronic tests, expert evaluation are used to establish indicators. quality and safety of goods and obtaining objective information. The main identification tasks of the commodity examination of children’s scooters, the most typical defects of these products and defects that indicate their low quality are indicated. The mechanism of forensic commodity examination of children's scooters is described.

Analog Implementation of a Spiking Neuron with Memristive Synapses for Deep Learning Processing

Analog neuromorphic prototyping is essential for designing and testing spiking neuron models that use memristive devices as synapses. These prototypes can have various circuit configurations, implying different response behaviors that custom silicon designs lack. The prototype’s behavior results can be optimized for a specific foundry node, which can be used to produce a customized on-chip parallel deep neural network. Spiking neurons mimic how the biological neurons in the brain communicate through electrical potentials. Doing so enables more powerful and efficient functionality than traditional artificial neural networks that run on von Neumann computers or graphic processing unit-based platforms. Therefore, on-chip parallel deep neural network technology can accelerate deep learning processing, aiming to exploit the brain’s unique features of asynchronous and event-driven processing by leveraging the neuromorphic hardware’s inherent parallelism and analog computation capabilities. This paper presents the design and implementation of a leaky integrate-and-fire (LIF) neuron prototype implemented with commercially available components on a PCB board. The simulations conducted in LTSpice agree well with the electrical test measurements. The results demonstrate that this design can be used to interconnect many boards to build layers of physical spiking neurons, with spike-timing-dependent plasticity as the primary learning algorithm, contributing to the realization of experiments in the early stage of adopting analog neuromorphic computing.

Geomechanical Characterization of a Brazilian Experimental Site: Testing, Interpretation, and Material Properties

Clarity in monitoring existing foundation structures demands innovative safety analysis methodologies for deep foundations, necessitating advanced models calibrated with real-world field parameters. Understanding controlled conditions, including geotechnical profiles, seismic attributes, and soil mechanics, is crucial. A dedicated research group at the University of São Paulo spent three years refining these conditions, characterizing an experimental field along a canal in São Paulo. This study pioneers geotechnical and geomechanical characterization of the region’s tertiary sediments in São Paulo, offering valuable insights for current and future applications. Standard penetration tests with torque (SPT-Torque), piezocone tests (CPTu), and measurement of wave velocity (Vs) with piezocone tests (S-CPTu) were carried out. The exploration of the subsoil shows that in up to 2 m of excavation, there are clays and silts, and in up to 25 m, there is a significant layer of compact fine sand that has high values of tip resistance and wave velocities more significant than 100 m/s. In the electric cone tests, the abacus used displayed a reasonable classification. All propositions identified the transition from the surface soil to the sandy soil at between 3 and 25 m. The soil classification values were obtained with the data of the field parameters, and the geotechnical and mechanical parameters were estimated. No differences were detected among the values found in the SPT-T and CPTu tests for the values obtained via cone resistance. This demonstrates the reliability of both methods. In addition, using the CPTu test to identify the stratigraphic profile horizons employing the soil’s mechanical behavior when the cone is driven proved appropriate.

Study on the Preventive Effect of Au/CeO2 on Lithium-Ion Battery Thermal Runaway Caused by Overcharging

In this study, a flower-like Au/CeO2 supported catalyst composite anode was prepared to explore its impact on thermal runaway triggered by overcharging and flame. Through structural and performance characterization, it was found that the catalyst has a high specific surface area and good CO catalytic oxidation capability, with a CO removal rate higher than 99.97% at room temperature. Through electrical performance testing, it was discovered that, compared to batteries without the catalyst, batteries using the composite anode did not exhibit significant capacity degradation. In overcharge testing, the catalyst prolonged the voltage rise time and peak voltage occurrence time of the battery. In thermal runaway testing, the addition of the catalyst delayed the detection time of CO and significantly reduced the concentration of thermal runaway products, especially the peak concentration and integrated concentration of CO, demonstrating its effectiveness in reducing thermal runaway products. Therefore, this study provides a new approach for improving the safety of lithium-ion batteries. The catalyst exhibits good performance in reducing toxic gases generated after thermal runaway and delaying the occurrence of thermal runaway, providing strong support for the safe application of lithium-ion batteries.

Fabrication of Polymer/Cholesteric Liquid Crystal Films and Fibers Using the Nonsolvent and Phase Separation Method.

In recent years, liquid crystal materials have drawn great interest because of their wide range of applications. Among various thermochromic materials, cholesteric liquid crystalline (CLC) materials have been well studied and reported. CLC materials have the advantages of ready manipulation and multiple color transitions. For the further development of smart clothing and wearable electronics, however, the incorporation of CLC materials into polymers still remains challenging. The difficulties lie in the prevention of leakage of CLC and retention of the cholesteric liquid crystalline phase. In this work, we demonstrate a versatile nonsolvent and phase separation method using polar solvents to incorporate CLC microspheres into polymer matrix. Poly(vinyl alcohol) (PVA), a water-soluble polymer, is chosen as the polymer because of its high transparency and ease to handle. Using spin-coating and wet spinning techniques, PVA/CLC films and fibers can be fabricated. The formation of CLC microspheres in the polymer matrix is characterized through optical and polarized microscopy. Compared with the CLC films, the PVA/CLC composites demonstrate superior thermal stability. Moreover, both PVA/CLC films and fibers exhibit good color stability from the electrical tests. This work provides an effective strategy to prepare polymer/CLC composites, paving a wide avenue toward applications in smart textiles, display technologies, and medical devices.

A feasible strategy for triboelectric separation of coal-series kaolin using a cascade electrostatic field

The coal-series kaolin in China possesses abundant resources, and its efficient utilization can be promoted by separation. In this paper, a cascade electrostatic field was designed for the triboelectric separation of coal-series kaolin. The motion behavior of charged particles with different size fraction in cascade electrostatic field was investigated by high-speed dynamic camera system, and the distribution characteristic of charge-to-mass ratio of products was analyzed by the coulometer. The influence of key operating parameters (e.g., feed speed, rotation speed and plate voltage) on product distribution were studied by electric separation test. The results indicated that the charge-to-mass ratio of the product after separation has the characteristics of cascade distribution. In addition, compared with 0.05–0.25 mm and 0.25–0.125 mm, the dispersion performance of 0.125–0.074 mm coal-series kaolin in the cascade electrostatic field was poor. For 0.5–0.25 mm, 0.125–0.25 mm and 0.074–0.125 mm coal-series kaolin, the decarburization efficiency after separation in cascade electric field was 47.09 %, 53.48 % and 44.63 %, respectively. Our study indicates that the setting of cascade electrostatic field achieved efficient purification and enrichment of coal-series kaolin.