Electrical Test Research Articles

Modified Complex Electrical Resistivity Technique: Applications to Saturated and Unsaturated Soils

Abstract Direct current (DC) electrical resistivity is a common laboratory soil characterization method to support geotechnical infrastructure design and to supplement site investigations. The complex electrical resistivity method has the potential to provide additional electrical soil properties to enhance electrical soil characterization. Both methods are conventionally performed under fully saturated soil conditions; however, many environments exist where soil is not fully saturated, such as ballast structure supporting railways. In this study, a new experimental setup featuring a current enhancing agent (agar) for complex electrical resistivity testing is evaluated by testing five different soil specimens reconstituted at saturated and unsaturated conditions. Results showed that the new experimental setup is valid and can be used to obtain repeat measurements, particularly for specimens reconstituted in the unsaturated conditions where the traditional DC electrical resistivity setup yields results that are unreliable. This is one of the very few studies where tolerances for triplicate specimens are reported to establish differences in measurements from sample preparation versus discernable variability between different geomaterials. Additionally, all results are supported by a Cole-Cole model. The results show that the additional data collected in a complex electrical resistivity test can be used to differentiate different soil types that are ambiguous with the DC electrical resistivity method. The additional data have the potential to more fully characterize the electrical properties of saturated and unsaturated soils, as well as to help distinguish unique geophysical signatures of various geomaterials to enhance a geophysical site investigation for identifying soil variability in the subsurface.

Morphophysiological variation, vigor test, and influence of light and temperature on the germination of four cultivars of Glycine max (L.) Merrill

Soybean (Glycine max. (L.) Merrill) is a crop whose productivity depends on the quality of the seeds used. In this context, the objective of this study was to characterize the seeds physically, evaluate viability using tetrazolium, identify physiological vigor through an electrical conductivity test, and determine the influence of temperature and photoperiod on the germination of four cultivars (Ultra, Olimpo, Extrema and Foco). 200 seeds were used, measuring size, weight of a thousand seeds, moisture content, and fresh mass. In tetrazolium (1%), 100 seeds were soaked for 4 h at 25°C. For electrical conductivity, 50 seeds were submerged on 75 mL of deionized water at 25°C for periods of 4, 8, 12, 16, 20 and 24 h. In the germination process, the treatments (four replications of 50 seeds) were incubated (B.O.D.) at temperatures of 25°C, 27°C, 30°C and 35°C, under photoperiods of 12 and 14 h. The experimental design adopted was completely randomized for all experiments, and the means were subjected to analysis of variance and Tukey's test at 5% probability. The Ultra cultivar presented perimeter (38.21±3.72 mm), length of 9.98±0.24 mm, and width of 7.94±0.27 mm. The cultivars presented viability above 90%. For electrical conductivity, the 12 h period was effective for identifying vigor. The Ultra cultivar (25°C and 12 h of photoperiod) achieved 77% germination, 10 germinated seeds per day, an average germination time of 4 days and 43 germinated seeds by the third day.

Comparison of a novel side-to-side tenorrhaphy with Pulvertaft weave: an in vitro biomechanical study

PurposeThe aim of this study was to characterize the biomechanical properties of a novel side-to-side tenorrhaphy (SST), this tenorrhaphy is designed to achieve reliable strength utilizing fewer knots and greater operationalization. This is compared with a well-established tendon reconstruction technique called the Pulvertaft weave technique (PWT).MethodsTwenty fresh porcine hindfoot flexor tendons were collected, and 10 novel SST and 10 PWT were performed in each group. The repaired tendons were tested cyclically by applying a force of 35 N using an electric tensile testing machine. Tendons were loaded until they ruptured and failed. The cyclic elongation, ultimate elongation, ultimate failure load, stiffness, and operation time were recorded and analyzed for both groups, and the failure patterns of the tendons were observed.ResultsThe mean operation time were 1.86 in the SST group and 3.25 min for the PWT group, respectively. The ultimate failure load was 179.93 N ± 12.05 for the SST group and 113.46 N ± 7.89 for the PWT group. The ultimate elongation was 17.79 mm ± 0.51 for the SST group and 26.83 mm ± 0.64 for the PWT group. The stiffness of the SST group was 35.27 N/mm ± 0.90 in the SST group and 20.11 N/mm ± 0.84 in the PWT group. There was no statistically significant difference in cyclic elongation.ConclusionThe SST group performed better than the PWT group in terms of the ultimate elongation, ultimate failure load, and stiffness. It is clear that the novel SST is a reliable alternative to PWT for tendon repair. The operation time of the SST group was significantly shorter than that of the PWT group.

Evaluation of Field Performance of Groundnut Varieties through Different Vigour Tests

A field experiment was carried out to evaluate the field performance of groundnut varieties through different vigour tests during Rabi, 2023-24 at S.V. Agricultural College, Tirupati, Acharya N.G. Ranga Agricultural University, Andhra Pradesh. The experimental material consisted of 10 groundnut varieties Narayani, Dharani, Dheeraj, TCGS-1694, Nithya Haritha, Kadiri-9, Kadiri-6, Kadiri Amaravathi, Kadiri-1812 and TAG-24 collected from different sources. In the preliminary experiment seed multiplication was done and the multiplied seed was used for conducting six vigour tests namely Germination test, speed of germination test, Seedling vigour index-Ⅰ, Seedling vigour index-Ⅱ, Accelerated ageing test, Electrical conductivity test in the laboratory using Completely Randomised Design with four replications. The multiplied seed was used for evaluating field performance using Randomised block design with three replications. Significant differences were found among the varieties based on vigour levels. Results with respect to field experiment showed that growth parameters i.e. field emergence percentage, days to 50 % flowering, days to maturity, number of branches per plant, number of pods per plant, pod yield per plant, kernel yield per plant, pod yield per plot, plant height, shelling percentage, 100 seed weight and harvest index varied significantly among different varieties based on different vigour levels. Varieties with higher vigour had shown higher field emergence percentage. Among the ten varieties Kadiri-6 had shown highest field emergence percentage. Significant correlation was observed among laboratory and field experiments. Vigorous varieties were able to perform better in terms of some of the field parameters and among all the vigour tests performed speed of germination test had high correlation with field emergence.

Temperature dependent effect of nano-scale phase change materials on fresh and hardened cement based mortar

One of the smart and innovative materials used to produce environmentally friendly energy-saving concrete is temperature dependent phase change (PCM) materials. In this study, the fresh and hardened concrete properties of the mortars including PCM in different ratios (0%, 2.5%, 5%) were investigated experimentally. Rheological properties such as slump-flow, specific viscosity, and yield stress tests were determined at different temperatures (from 20 to 50 °C). Time-dependent physical, mechanical, and thermal properties such as ultrasound pulse velocity (UPV), electrical resistivity, dynamic modulus of elasticity, compressive and flexural strength, thermogravimetric (TGA), and thermal conductivity tests were carried out. According to the experimental findings, the workability and hardened properties of mortars were decreased by using PCM. However, the rheological properties of fresh mortar change depending on temperature due to PCM absorbing the heat. Therefore, the fresh properties of mortar with PCM can be controlled by temperature. It was also found that the phase change of mortars with PCM can be obtained by measuring the electrical or UPV tests at different temperatures.

Fault Diagnosis Method for Marine Electric Propulsion Systems Based on Zero-Crossing Tacholess Order Tracking

In marine electric propulsion systems (MEPS) driven by variable-frequency drives, motor current signals often exhibit complex modulation components, ambiguous spectra, and severe noise interference, rendering it challenging to extract fault-related modulation components. To address this issue, we propose a zero-crossing tacholess order tracking method based on motor current signals. This method utilizes zero-crossing estimation of the instantaneous frequency to perform angular resampling of stator current signals and demodulates the envelope spectrum to extract fault characteristic spectra, enabling the diagnosis of mechanical faults in MEPS. Given the synchronization of the synchronous motor speed with the inverter fundamental frequency, this method estimates instantaneous frequencies in the time domain without requiring integration or time–frequency representation, which is simple and computationally efficient. Data validation on a small-scale marine electric propulsion test platform demonstrates that the proposed method exhibits good robustness under variable-speed conditions and effectively detects imbalance faults caused by propeller breakages and gear faults resulting from bevel gear tooth defects. Therefore, the proposed method can be applied to diagnose faults in downstream mechanical equipment driven by motors.

Investigation of the Discharge Voltage in Electric Vehicle Motor Bearings

As the automotive industry undergoes a significant transition towards electric vehicles (EV), the matter of electric current discharge in motor bearings has emerged as a focal point of concern. This issue has gathered increased attention due to its potential to inflict damage upon bearing surfaces. The extent of damage inflicted by the discharges is intricately tied to the discharge energy, a factor directly influenced by both bearing capacitance and discharge voltage. In pursuit of a deeper understanding of discharge voltage dynamics within EV motor bearings, electric discharge tests were conducted using in-house modified single ball-on-disc contact and full bearing test equipment. Our test results at the single ball-on-disc contact show that discharge voltage adheres to a probabilistic distribution. Moreover, parallel investigations at the bearing level have yielded corroborative findings, reinforcing conclusions drawn from the single contact tests. These collective efforts contribute to a comprehensive understanding of electric discharge phenomena in motor bearings, essential for developing effective mitigation strategies and advancing the reliability of EV propulsion systems.

Detection and Prediction of Probe Mark Damage in Wafer Testing

In wafer testing, the test probe needs to contact the surface of the semiconductor wafer to measure electrical parameters such as resistance, capacitance, and current. The probe mark damage frequently occurs on the machine during wafer testing. This phenomenon causes inaccuracies in electrical parameter testing, significantly reducing the yield in IC packaging processes and resulting in substantial manufacturing cost losses. Therefore, this study proposed an effective probe mark damage detection and prediction method to prevent significant yield reduction due to inaccurate testing. This study uses importance analysis from random forests and correlation analysis to identify the critical parameters influencing probe mark damage. Introducing these parameters into a Sparse Transformer with hybrid normalization can successfully train an intelligent model for predicting the occurrence of probe mark damage. The model accurately predicts the probability of probe mark damage and promptly adjusts machine parameters to avoid inaccuracies in electrical parameter settings. The proposed approach can outperform other methods, achieving two very high accuracies of 95.1% (at room temperature) and 93.5% (at high temperature) and significantly reducing the occurrence of large-area probe mark damage.

Behavior of Polymeric Substrates and Sintered Silver Printed Hybrid Electronic Assemblies Subject to Extreme Acceleration Levels and Elevated Temperatures

Abstract This paper focuses on the response of printed hybrid electronic (PHE) assemblies with polymeric substrates and additively manufactured sintered silver electrical traces subject to extreme mechanical shocks (up to 100,000 g) and high temperatures (up to 150 °C). The substrates are hemispherical domes of injection-molded polycarbonate and polysulfone thermoplastics. Trace deposition onto the domes is accomplished by a novel process that combines conventional milling with extrusion printing to recess silver traces and dielectric insulation within the surface of the substrate. Mechanical shock testing is performed using an accelerated-fall drop tower equipped with a dual mass shock amplifier (DMSA) able to generate accelerations from 10,000 g up to 100,000 g with pulse durations of ∼0.05–0.1 ms and impact velocities of 6.5–20.5 m/s. Specimen performance is characterized by electrical and physical testing before and after testing. While polycarbonate domes survive multiple drops at all acceleration levels and temperatures, they are sensitive to heat and susceptible to warping and structural deformation at 150 °C which can compromise trace performance. Polysulfone domes can survive these temperatures without issue, but are less shock resistant and only survive 3–4 drops at 100,000 g (compared to 30+ for polycarbonate domes). Trace resistance is used as a metric to assess trace performance. All traces exhibit progressive long-term degradation over the course of multiple shocks, followed by instantaneous discontinuity during the final shock event. Trace failure (defined as the doubling of static trace resistance) occurs at ∼105–106 J/kg cumulative impact energy for all acceleration levels.

Full pulpotomy versus root canal therapy in mature teeth with irreversible pulpitis: a randomized controlled trial

BackgroundVital pulp therapy (VPT) is recommended as an alternative treatment to root canal therapy (RCT) for management of teeth with carious pulp exposure. This randomized clinical trial aimed to compare the outcomes and postoperative pain, and to evaluate the time and cost after full pulpotomy (FP) and RCT in mature molar teeth with irreversible pulpitis (IP).MethodsA total of 160 mature molar teeth with IP were randomly divided into two treatment groups. The FP group (test group) was treated with FP using iRoot BP Plus by an endodontist, the RCT group (control group) was treated with RCT using iRoot SP as sealer by the same endodontist. Pain was recorded preoperatively and daily until day 7 postoperatively. The treatment time and cost were recorded. Clinical and radiographic assessments were collected, and pulp sensibility tests were done by electric pulp test (EPT) at 3-, 6-, 12- month postoperatively. Data were analyzed through chi-square test, Mann-Whitney U test, Fisher exact and independent t test.ResultsFP and RCT had comparable success rates (Clinical, 97.3% vs. 98.6%; radiographic, 93.3% vs. 94.6%) (P > 0.05). Pain levels decreased over time from day 1 to day 7 postoperative in both groups, and the FP group had larger reductions in pain intensity than RCT at day 1 (P < 0.05). In the FP group, there were 5, 3 and 3 unresponsive teeth with EPT at 3-, 6- and 12- month follow-ups, respectively. The treatment time and cost in the FP group were significantly lower than in the RCT group (P < 0.05).ConclusionsFP could be an appropriate alternative treatment for management of mature teeth with IP in short follow-up.Trial registrationThe trial was registered in Chinese Clinical Trial Registry (ChiCTR2200063380 at 05/09/2022).

On safety of swelled commercial lithium-ion batteries: A study on aging, swelling, and abuse tests

Lithium-ion battery technology has advanced significantly, making these power sources essential for portable electronic devices such as smartphones. In 2023, global smartphone shipments reached nearly 1.2 billion units, underscoring the widespread reliance on these batteries. However, as batteries age, they may swell and potentially pose explosion risks. To investigate the safety of swollen batteries, this study conducts accelerated aging and swelling tests on lithium-ion batteries from five leading brands, which together represent over half of the global smartphone market share. The research involves a series of comprehensive tests, including Accelerated Rate Calorimeters (ARC) test, mechanical, electrical, and thermal abuse tests in accordance with Chinese national standards, as well as gas composition and theoretical flammability analyses on both new and swollen batteries. The findings indicate that swollen batteries generally exhibit safer behavior under floating charging conditions, and both new and swollen batteries pass the abuse tests within the standard framework. This study suggests that the safety of swollen lithium-ion batteries cannot be categorically labeled as dangerous or safe and should be assessed within the context of specific environments.

Impact of Ultrasonic Welding Parameters on Weldability and Sustainability of Solid Copper Wires with and without Varnish.

This article contains an advanced analysis of the properties of solid wire electrical contacts produced by ultrasonic welding, both with and without varnish. The main disadvantage of ultrasonic welding of thin wires is the inability to achieve acceptable peel force and tensile strength, which is mainly due to the deformation and thinning of the wires. This study deals with ultrasonic welding using a ring of thin solid copper wires that minimises the deformation and thinning of the wires. The influence of welding parameters such as energy, pressure and amplitude were systematically analysed. Based on these parameters, the optimum welding programme and control method was determined to weld unvarnished and varnished wires. The investigations included electrical resistance tests, optical microscopy, micro-hardness measurements, peel tests and tensile tests, and the measurement of energy consumption. The results showed no significant differences in microstructure and hardness between varnished and unvarnished joints. Ultrasonic joints of varnished wires achieved lower electrical conductivity (by 38%), lower tensile strength (by 3%) and higher peel strength (by 7%), while the welding process was more sustainable in terms of energy (by 6.6%) and time consumption (without preprocessing).

Photobiomodulation therapy on puncture-associated pain: A controlled randomized double-blind clinical trial.

Dental fear and phobia are prevalent worldwide, with local anesthesia being the most feared procedure. This study aimed to determine whether photobiomodulation therapy (PBMT), used as a pre-anesthetic, could modulate puncture pain and enhance the effectiveness of local anesthesia. In this controlled, randomized, double-blind study, 49 participants were divided into an experimental group (n = 24), which received infrared laser therapy (100 mW, at 808 nm, 8 J, 80 s at a single point) immediately before standard anesthesia; and control group (n = 25), which received the standard anesthetic technique and sham laser. Pain levels were measured using the visual analog scale, and anesthetic efficacy was assessed through electrical tests (latency), percentage of failures, and cartridge usage. Anxiety levels were evaluated using the Beck Anxiety Inventory. Cardiovascular parameters were evaluated through blood pressure, oxygen levels, and heart rate. This randomized, double-blind study found no difference between groups in these experimental conditions. The bias toward a positive PBMT result was sufficiently removed. Autonomic responses of the PBMT group were maintained stable during the procedure.

Effect of Diatomite on the Mechanical and Electrical Properties of Polyurethane/Epoxy Resin Composites

ABSTRACT Epoxy resin is widely utilized for the encapsulation of power semiconductor devices, necessitating excellent insulation properties, mechanical performance, and moisture resistance. In this study, hexadecyltrimethoxysilane was employed to modify diatomite, which was then combined with polyurethane-modified epoxy resin to fabricate a series of filled composites with varying diatomite content. The influence of diatomite content on the mechanical properties, thermal properties, and insulation performance of the polyurethane/epoxy resin composites was investigated. Experimental results showed that, under the synergistic effect of polyurethane and diatomite, the composite containing 4 wt.% diatomite exhibited improvements of 13.95% and 61.11% in tensile strength and flexural strength, respectively, compared to the epoxy resin. The elongation at break and flexural displacement also increased by 22.46% and 68.23%, respectively. Furthermore, the incorporation of diatomite effectively compensated for the thermal losses caused by polyurethane, enhancing thermal stability. Electrical property tests indicated that the addition of diatomite reduced the dielectric constant and conductivity of the epoxy resin while simultaneously improving its breakdown strength.

Impact of electrical testing strategies on the performance metrics of bio-organic-based resistive switching memory

Impact of electrical testing strategies on the performance metrics of bio-organic-based resistive switching memory

Cyclic loading effects on the heat-generation performance of carbon nanotube-embedded cement composites

Abstract This study investigates the heat-generation stability of carbon nanotube (CNT)/cement composites after exposing to cyclic loading conditions. The specimens were fabricated with varying CNT contents and levels of fly ash replacement. Results showed that increasing CNT content reduced electrical resistivity, while the impact on the electrical characteristics was found to be insubstantial, even though a considerable portion of fly ash was replaced. In addition, the electrical resistivity of the specimens after exposed to cyclic loading increased. Electrical heating tests revealed both negative and positive temperature coefficient effects depending on the applied voltages. Higher CNT contents improved the heat-generation capability, but the heating capability decreased after exposed to the cyclic loadings which is deduced from the damage of CNT networks during cyclic loadings. In this regard, the authors concluded that the heat-generation stability can be significantly affected by the applied loadings. Thus, the future research will be conducted to improve the heat-generation stability of the cement-based electrical heating systems as exposed to artificial deteriorations.

Study on the Commercial Metalized Plastic Current Collector PET-Cu and PP-Cu Toward High-Energy Lithium-Ion Battery.

Commercial metalized plastic current collector (MPCC) is receiving widespread attention from the business and academic communities, due to its properties of excellent electrical conductivity and low mass density. However, the application of MPCC on the side of copper is rarely studied. Herein, sandwich-like polyethylene terephthalate-based (PET) and polypropylene-based (PP) copper (Cu) current collectors via magnetron sputtering and electroplating are fabricated. Most importantly, the electrical performance, mechanical safety quality, and revealed the corresponding failure mechanism for the MPCC cells are first systematically evaluated. First, during the 45°C electrical cycling tests, PET-Cu CC (82.67%) and PP-Cu CC (82.32%) cells both have comparable capacity retention with the traditional Cu CC (Tra-Cu CC) cell (84.55%) after 500 cycles. The slight reduction in the cycling performance is induced by the crack of the Cu layer around the embedded SiO2 particle for PET-Cu CC cell and the detachment of Cu layer for PP-Cu CC cell. Second, during the nail-penetration test, MPCC cells maintain no fire and explosion for more than 5min, since the heat-shrinkable function of polymeric film can interrupt the continuous Joule heat released by internal short-circuit. This work provides important guidance for the large-scale application of MPCC in the field of lithium-ion batteries.

Enhancing polypropylene-based separator efficiency in lithium-ion batteries through maleic anhydride addition and corona radiation modification

Polypropylene-grafted-maleic anhydride (PPMA) as a modifier of polypropylene (PP) at different contents and the corona radiation for surface ionization at various modification times were applied to promote the PP-based separator efficiency. The determined microstructural characteristics showed an improvement in the separator's porosity of 6–139 % at the tension amounts of 700–900 %, however, more stretching hurts the mechanical properties. The electrostatic interactions formed between the electrolytes and anhydrides increased the electrolyte sorption capacity in the samples and the surface wettability by 740 % and 25 %, respectively. The electrical test results indicated that the anhydrides led to capturing the electrolytes in the separator and created a resistance against the ion diffusion. This phenomenon reduced the separator resistance from 475 to 165 Ω, and enhanced the charge capacity and ion conductivity from 585 to 871 mAh/g and 0.29 to 0.34 S cm−1, respectively, while the PPMA content increased from 20 to 60 wt.%. The achieved FT-IR illustrated that the ionization caused the creation of more polar groups in the LIB separator, which increased the bulk and surface wettability by 420 % and 21 %, respectively, without any change in the microstructure of the separator. However, raising the exposure time in the radiation process decomposed the sample surface and led to damage in the separator microstructure. This issue reduced the separator porosity as well as the electrolyte absorption amount and ion conductivity.

Novel anti-oxidation coating prepared by polymer-derived ceramic for harsh environments up to 1200 °C

Environmental barrier coatings (EBCs) are protective barriers that could prevent internal materials from oxygen and harmful agents. However, the combination between EBCs and polymer-derived ceramics (PDCs) is relatively hard but essential. In this work, an anti-oxidation coating based on PDCs is fabricated on target SiBCN ceramics by spraying. The coating reveals a uniform and continuous structure with an approximate thickness of 11.7 μm. Experiments and characterization such as oxidation, thermal shock, scratch, and electrical resistance tests were carried out to investigate the performance of coating. The results show that during the high-temperature oxidation process, the coating surface undergoes a molten phase transformation that effectively seals pores and cracks, preventing oxygen diffusion into the ceramic interior. Moreover, the coating can withstand 20 thermal shocks without failure, and firmly adheres to the substrate even after prolonged oxidation and repeated thermal cycling. Comparative analysis of temperature-resistance results demonstrates the efficacy of the coatings in protecting against oxidation up to 1200 °C. The developed PDC-EBCs here exhibit remarkable resistance to oxidation and thermal shock, along with high insulation resistivity. This strategy offers a straightforward and efficient solution for protecting electronic materials in harsh environments.

Effect of orthodontic space closure on dental pulp sensitivity. Prospective clinical trial.

Orthodontic tooth movement (OTM) is a biological process that can influence the function of the pulp, including its innervation. The excitability of the nerve fibres of the pulp may be altered by forces exerted on the nerve fibres or by reduced blood flow to the pulp. The aim of this clinical study was to evaluate the sensitivity of the dental pulp during levelling and during the phase of space closure, to assess the role of certain controlled risk factors. Twenty-two adolescent participants requiring orthodontic space closure in transcanine sector were enrolled in a prospective clinical study. Patients were observed before OTM, after levelling and 1 month during active space closure. The sensitivity threshold of the pulp was measured using the electric pulp test (EPT). Dental models were obtained using an intraoral scanner, allowing measurement of interdental distances and calculation of OTM speed. The teeth were categorized according to position and tooth type. The EPT values increased significantly during orthodontic treatment (one-way RM-ANOVA, P = .014). There was a significant difference in EPT values between the tooth categories. Teeth with a single root adjacent to the residual space had the highest EPT thresholds (two-way RM-ANOVA, P < .001; Holm-Sidak, P < .05). OTM reduced pulpal sensitivity. Pulpal sensitivity during active space closure was similar to sensitivity during the levelling phase. The pulpal sensitivity of molars was less affected by OTM than that of single-rooted teeth, while teeth closer to the gap had a significantly higher pulpal sensitivity threshold during active OTM.