Electrical Aging Research Articles

Chemistry in the new ‘Age of Electricity’

Chemistry in the new ‘Age of Electricity’

Multi-modality deep learning prediction of heart age: insights from UK-Biobank

Abstract Background Identification of apparently healthy individuals at high cardiovascular risk who may benefit from targeted preventive strategies remains challenging. Predicted heart age, the chronological age of individuals with similar absolute cardiovascular disease (CVD) risk but with no risk factors, has been proposed to appropriately describe the absolute CVD risk over conventional prediction tools. Purpose To develop multi-modality based deep learning predictors for heart age in UK-Biobank individuals. Methods We used deep learning to develop a heart age predictor based on videos from heart magnetic resonance imaging (MRI) (anatomical dimension), electrocardiograms (ECG) (electrical dimension) or both from 45000 individuals of the UK Biobank cohort (age range 45-81 years) (Figure). We estimated the heritability of heart aging and identified single-nucleotide polymorphisms associated with accelerated heart aging. We performed X-wide association study to identify non-genetic factors potentially associated with accelerated heart aging. Results We predicted age with a mean absolute error (MAE) of 2.5±0.03 years (R2=85.6±0.6%) and found that accelerated heart aging is heritable at more than 35%. MRI-based anatomical features predicted age better than ECG-based electro-physiological features (MAE=2.29±0.03 years versus 4.90±.0.08 years), and heart anatomical and electrical aging were weakly correlated (Pearson correlation=0.249±0.002). Our attention maps highlighted the aorta, the mitral valve, and the interventricular septum as key anatomical features driving heart age prediction in videos that capture the entire heartbeat cycle. We found accelerated anatomical and electrical heart aging to be genetically correlated (Pearson correlation=0.508±0.089). The most significant locus was in TTN (Titin) and it was associated with heart anatomical aging. Cardiovascular diseases, general health status, and mental health disorders were highly associated with accelerated heart aging. Conclusions A multi-modality based deep learning approach was highly predictive of heart age. Accelerated heart age has a complex biological basis with genetic and environmental correlates. Leveraging of the described pipeline to predict survival and the onset of age-related cardiovascular diseases may shed light on heart aging role in health outcomes and effectively guide personalized preventive strategies.

Electrical Performance and Degradation Analysis of Field-Aged PV Modules in Tropical Climates: A Comparative Experimental Study

Performance degradation is a prevalent phenomenon in solar photovoltaic systems globally, with varying aging profiles and effects depending on environmental and climatic conditions. This paper presents an extensive investigation of the electrical performance, aging mechanisms, and degradation analysis of field-aged PV modules under the tropical climate of Malaysia. Utilizing a combination of visual inspection, I-V curve measurement, and thermal imaging techniques, this research provides a comprehensive assessment of the electrical and thermal properties of field-aged PV modules from two locations in Malaysia over extended periods (8 years at UMPSA and 10 years at Pasir Mas). The multi-faceted approach of the study allows for a deeper understanding of the degradation process, offering insights into the causes and effects of higher current and lower voltage in aged modules. The study found the average annual degradation rates at UMPSA were 0.3% for open circuit voltage (Voc), 0.23% for short circuit current (Isc), 0.81% for maximum power (Pmax), and 0.35% for fill factor (FF) and at Pasir Mas, the average annual degradation rates were 1.124% for Voc, −0.166% for Isc, 1.276% for Pmax, and 0.43% for FF. The study also found that monocrystalline silicon (m-Si) panels experienced an average power degradation of 6.48%, while polycrystalline silicon (p-Si) panels showed a higher degradation of 12.76%. However, Thermal imaging revealed significant temperature variations across the modules, with hotspots reaching up to 11.2 °C above cooler areas in UMPSA panels and an even more pronounced 26.1 °C difference in Pasir Mas modules. These temperature disparities highlight the uneven heat distribution and potential performance issues in the panels. This research contributes to the understanding of PV module degradation in tropical climates and aligns with sustainable development, climate change mitigation efforts, and SDG 7 by promoting sustainable energy solutions.

Health-awareness energy management strategy for battery electric vehicles based on self-attention deep reinforcement learning

The economical and safe energy management strategy (EMS) is essential for a battery electric vehicle (BEV). With an improved deep deterministic policy gradient (DDPG)-based EMS proposed for a dual-motor BEV, energy consumption and electric component aging are minimized. Firstly, this study incorporates health awareness of electric components into EMS. Then, this study employs a gated recurrent unit (GRU) as well as a self-attention (SA) mechanism for improving the original DDPG's performance. The GRU enhances the performance of DDPG agents, post-convergence, by furnishing them with additional state information. The SA mechanism empowers agents to distinguish the importance of state information, thus improving its adaptability in new environments. The proposed EMS decreases battery energy consumption to 7.95 kW-hour and enhances battery state of health (SOH) to 96.83 % of the dynamic programming (DP)-based EMS. The two motors of the proposed EMS possess the highest end-value SOH, i.e., 99.99929 % and 99.99978 %, respectively. The proposed EMS demonstrates superior adaptability to other EMSs, regardless of the initial state of charge (SOC). It shows the best adaptability at an initial SOC of 0.6, and achieves 95.87 % and 94.67 % of the energy consumption of DP-based EMS in the mixed and actual test cycles, respectively.

Effects of different valence of starting oxides on the structure and properties of Co-Mn-Fe-Zn-Ni-O high-entropy ceramics

In this work, using different manganese sources, Co-Mn-Fe-Zn-Ni-O high-entropy ceramics (HECs) were synthesized via the solid-phase method. X-ray diffraction (XRD) data showed that the HECs consist of rock salt and spinel phases, and the choice of raw materials has a great influence on the phase composition and lattice distortion of HECs. Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) analyses showed that the HECs have dense microstructures, with the major elements conforming to iso-atomic ratios. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy data showed that Mn3+ ions with Jahn-Teller effects distort the [MnO6] octahedra, affecting the electrical properties and aging stability of the material. The room-temperature resistivity of the HEC systems ranged from 20.81 kΩ cm to 35.43 kΩ cm, and the B25/50 resistivity values varied between 4037 K and 4048 K. The resistance drift was observed to be less than 0.70 % after aging at 125 °C for 1000 h. Impedance analyses suggested that the electrical properties of the high-entropy ceramics can be modulated by tailoring the grain size and grain boundary morphology. Selecting suitable raw materials based on valence-induced effects and the tendency of ions to occupy specific sites offers new insights into the design and synthesis of tailor-made high-entropy NTC ceramics.

Maintenance Practices of High-Voltage Cross-Linked Polyethylene (XLPE) Cable Buffer Layers

As urbanization accelerates globally, the demand for electricity continues to rise, especially within high-voltage power transmission systems. Cross-linked polyethylene (XLPE) cables have become crucial due to their exceptional insulation properties and mechanical characteristics. However, the buffer layers of XLPE cables may undergo aging and faults caused by various factors, including electrical aging, thermal aging, chemical impacts, and improper design. This paper synthesizes existing literature to provide an in-depth analysis of the material properties, aging mechanisms, fault causes, design principles, and maintenance practices related to XLPE cable buffer layers. Through finite element method (FEM) simulations, it evaluates the electric field distribution across XLPE cables under different operating voltages and the contact state between the buffer layer and the metal sheath. Additionally, this study explores the recyclability and environmental impact of XLPE materials, as well as how improvements in material properties and detection technologies can enhance cable reliability and safety. The findings offer comprehensive theoretical and practical guidance to the power industry, aiding in optimizing cable design, improving system reliability, and reducing failure rates, while also suggesting future research directions.

Research on the Aging Judgment Method of Electrical Performance of C4F7N/CO2 Mixed Gases

Abstract Perfluoroisobutyronitrile (C4F7N) gas exhibits favorable environmental characteristics and excellent electrical performance, which renders it a prominent subject of research in the development of new environmentally friendly insulation materials as a substitute for SF6 gas. In this study, the decomposition products of a gas mixture comprising 15% C4F7N and 85% CO2 were investigated within a 12kV ring main unit. A total of 140 arc tests were conducted on the gas mixture, allowing for the identification of the relationship between the generation of decomposition products and the number of arc tests. Through the determination of the proportional relationship between the different types and quantities of products, a novel method for assessing the extent of electrical performance aging in C4F7N/CO2 gas was developed, thus serving as a valuable reference for gas aging assessment. This study is of great significance for promoting the application of C4F7N/CO2 mixed gas in power systems.

Electrical aging of a piezoelectric MEMS fast steering mirror and its impact on reliability

Reliability is a critical characteristic of aerospace-grade components, particularly fast steering mirror (FSM), which is one of the key devices in Free-Space laser communication terminals. The previous long-term work of FSM exposes noteworthy reliability issues about degradation of this device. This paper first demonstrates the electrical aging effect that occurs in piezoelectric-driven micro electro mechanical system (MEMS) FSM during prolonged operation. This is a significant reliability issue as it causes the decay of mechanical angle of MEMS FSM, ultimately resulting in functional failure. In order to study the electrical aging effect, firstly, a mechanical angle monitoring system is developed for the rapid and accurate identification of electrical aging failure. Secondly, we performed failure analysis by using scanning electron microscope - focused ion beam (FIB - SEM) and conducted thermal analysis experiments to confirm heat accumulation within the MEMS FSM actuator, where the electrical aging effect takes place. Thirdly, by setting up a finite element simulations (FEM) model of the step region in the actuator, the electrical aging effect resulting from heat accumulation caused by high current density under a significant electric field at the lower step is confirmed. Finally, the critical reliability issue of electrical aging, which affects the lifetime of piezoelectric-driven MEMS FSM, is improved by adjusting the layout to eliminate large electric field intensity in local region.

Effect of pulse current density on creep ageing behavior of 2195 Al-Li alloy

Electrical pulse-assisted creep ageing forming can effectively improve the mechanical properties and forming efficiency of large aluminum components. However, it is difficult to achieve uniform and consistent current density at different positions in complex components. Thus, the creep behavior, mechanical properties, and microstructure evolution of 2195 Al-Li alloy under three pulse current densities (0A/mm2, 3A/mm2 and 8A/mm2) was systematically studied. The experimental results showed that the creep deformation increases with increasing current density during the 1st hour stage of electric pulse-assisted creep ageing process. However, the total creep strain of 8 h shows a trend of decreasing and then increasing. Low density pulsed currents (non-thermal effect) can promote the precipitation of the T1 phases and θ′ phases, and narrow the precipitates free zone compared to conventional creep aged sample (0A/mm2). High density (Both of non-thermal effect and Joule heating effect) pulsed currents can promote the precipitation of T1 phases, inhibit θ′ phases and form the precipitated phase penetrate the grain boundaries. A gratifying finding is that an increase in current density accelerates the aging hardening process, but the peak strength after creep ageing is the same for different current densities. This indicates that high pulse current density can improve creep ageing forming efficiency and ageing hardening process, and can use non-uniform current densities to solve the problem of significant differences in overall structural component formability while maintaining final performance consistency.

The Effect of Electric Aging on Vinylidene Fluoride Copolymers for Ferroelectric Memory.

Copolymers based on vinylidene fluoride are potential materials for ferroelectric memory elements. The trend in studies showing that a decrease in the degree of crystallinity can lead to an unexpected increase in the electric breakdown field is noted. An analysis of the literature data reveals that in fluorine-containing ferroelectric polymers, when using a bipolar triangular field, the hysteresis loop has an unclosed shape, with each subsequent loop being accompanied by a decrease in the dielectric response. In this work, the effect of the structure of self-polarized films of copolymers of vinylidene fluoride with tetrafluoroethylene and hexafluoropropylene on breakdown processes was studied. The structure of the polymer films was monitored using infrared spectroscopy (IR) and X-ray diffraction. Kelvin probe force microscopy (KPFM) was applied to characterize the local electrical properties of the polymers. For the films of the first copolymer, which crystallize in the polar β-phase, asymmetry in the dielectric response was observed at fields greater than the coercive field. For the films of the copolymers of vinylidene fluoride with hexafluoropropylene, which crystallize predominantly in the nonpolar α-phase, polarization switching processes have also been observed, but at lower electric fields. The noted phenomena will help to identify the influence of the structure of ferroelectric polymers on their electrical properties.

Diagnosis of a DC-DC converter boost using the Artificial Neural Networks ANNs

As we know in most the components of electrical equipment age during their operational life, which can be more or less long depending on the nature and degree of stress to which they are subjected, resulting in a degradation of performance to improve the reliability of the system. Industrial applications the DC machines are powered by a chopper voltage source. These machines are sensitive to different types of defects occurring to switches, capacitors and coils the need to conduct studies for the detection, localization and maintenance of defects become crucial. To avoid serious faults in DC-DC converters, several concepts have been applied to the diagnosis of these. The ANN method is used to diagnose DC-DC converters.

Investigation of electrical ageing effects on the structural and electrical properties of polystyrene by charging and discharging current method

This study focuses on isothermal charging and discharging currents in polystyrene (PS). It is a well known fact that the discharging current is almost the mirror symmetry of the charging current at low electric fields. However, the experimental results presented and discussed in this study have revealed the possibility of an abnormal discharging current (ADC) flowing in the same direction as the charging current. Furthermore, electrical measurements implied that the electrical ageing of PS resulted in a significant increase in the charging current, even for extended ageing periods. Moreover, the intensity and duration of the reverse discharging current have evolved with electrical ageing. This characteristic can be attributed to the presence of ionic impurities both trapped at the polymer surface and in the bulk structure. To highlight the structural changes induced by electrical ageing, detailed structural analyses were conducted using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analysis.

Deciphering proteome changes and meat texture of traditional halal slaughtered spent sheep subjected to low-voltage electrical stimulation and ageing

The present study evaluated the effect of low-voltage electrical stimulation (LVES, 42 V peak, 0.6 Amp, 50 Hz) and ageing in traditional halal slaughtered Nellore crossbred spent-sheep (Ovis aries). The LVES accelerated the post-mortem glycolysis with a significant decline in pH and shear force values and improvement in water-holding capacity, cooking yield, protein extractability, and an early onset of rigor-mortis relative to non-stimulated control. Two-dimensional gel electrophoresis coupled with tandem mass spectrometry identified myosin regulatory light chain 2, NADH dehydrogenase, myoglobin, and glyceraldehyde-3-phosphate dehydrogenase from traditional halal slaughtered sheep meat. PANTHER analysis of differentially expressed proteins indicated their involvement in structural (50%), catalytic (25%), and binding (25%) activities. The current study provides a novel insight into the contribution of different proteins in orchestrating meat texture from traditional halal slaughtered spent sheep meat subjected to LVES and ageing.

Grafting of voltage stabilizer onto EPDM surface and its inhibition effect on the breakdown of EPDM/XLPE interface

Surface discharge on the EPDM/XLPE interface is threatening the safe operation of power cable system and limiting the further improvement of its voltage level. To improve the electrical strength of EPDM/XLPE interface, the surface of EPDM was modified by grafting of voltage stabilizer 4-allyloxy-2-hydroxybenzophenone (AOHBP) based on liquid-phase impregnation and subsequent free radical grafting reaction thermally initiated by DCP. EPDM samples were modified by mixed reagents of DCP and AOHBP with different mass ratios of 1:2, 1:3 and 1:4, respectively. The SEM observation and XRD analysis results indicate that the crystals of AOHBP with a uniform distribution are covered on the surface of EPDM during the sample preparation process and then dissolved after extraction by acetone. The FTIR and ATR results show that the AOHBP molecules are successfully grafted onto the surface of EPDM samples, but there remain a lot of ungrafted reagent molecules on the surface of EPDM before solvent extraction. The grafting rate of AOHBP increases with the proportion of DCP in the mixed reagents. As for the unextracted modified EPDM samples, both the AC and DC breakdown voltage of the EPDM/XLPE interface are increased compared with pure EPDM, and further increased after the ungrafted molecules are extracted because the effect of voltage stabilizer on scavenging high-energy electrons is more efficiently utilized at a smoother interface. The interface breakdown voltage of the sample modified with 1:2 mass ratio of DCP/AOHBP mixed solution is the highest because of its highest grafting rate of voltage stabilizer. This work has proposed a new technical path to improve the electrical aging resistance of polymer insulating surface.

Research progress in modified mineral oil, natural ester and mixed oil in transformers

AbstractThree kinds of typical insulating oil including mineral oil (MO), natural ester (NE), and mixed insulating oil used in transformers are reviewed. The basic physicochemical, electrical properties and engineering application of the oil were firstly introduced. Then, the nano‐modified mechanism for MO and NE is explored. The effects of various nanofillers on electrical properties, thermal conductivity and ageing stability of MO and NE are compared. Moreover, the preparation process of mixed insulating oil is described, and the enhancement of electrical performance, thermal ageing properties, and kinematic viscosity of mixed insulating oil are analysed. Finally, the performance parameters of nano‐modified MO, NE and mixed insulating oil are analysed, and the future development trend of insulating oil is also discussed.

THE IMPACT OF LIGHTNING STRIKE ON HYBRID HIGH VOLTAGE OVERHEAD TRANSMISSION LINE – INSULATED GAS LINE

The electrical network is the set of elements where loads are connected to the generation plants by transmission lines. They can be either overhead or underground cables. A new technology has been introduced to replace these transmission lines with underground cables gas insulated line “GIL”. The latest has many advantages over underground cables and overhead transmission lines, such as low transmission losses, less capacitive load, reliability, personal safety, same operation as overhead lines and negligible electrical aging. GIL can handle much more power than overhead lines due to its large conductive area. GIL is the best for high voltage. In this paper, the simulation of lightning strike effects on a 400 kV hybrid transmission line located in the Wilaya of Setif in northern Algeria is presented in the absence and presence of line arresters and GIL arresters. The results of this paper can provide a rich and valuable theoretical reference for GIL simulation modeling and evaluation of lightning strike impact on hybrid overhead – GIL lines.

Electrical Characteristics of the Insulation Paper Modified by Nano-TiO2 under Electrical-Thermal Aging

The research on the modified insulating paper by adding nano-materials has garnered increasing attentions. Scholars have investigated its performances under electrical aging or thermal aging, but there are few reports on its behaviors under electrical-thermal combined aging. In the laboratory, we prepared the modified insulating paper with different mass fractions of nano-TiO2, and subjected to 10-day accelerated electrical-thermal combined aging test. Samples were experimented at different aging stages to investigate the variations in AC breakdown field strength, relative permittivity and surface microstructure. The results demonstrate that the modified insulating paper samples exhibit better AC breakdown field strength, relative permittivity and other parameters compared to the unmodified samples. Among the modified samples, the one with 3% mass fraction of nano-TiO2 shows the best electrical properties and aging resistance under electrical-thermal combined aging. By adding an appropriate weight percentage of nano-TiO2, it was able to fill microscopic holes and gaps on the surface of the insulating paper, strengthen the connection between the cellulose fibers, and improve the electrical properties and aging resistance of the insulating paper.

Study on the method of evaluating the failure of stator bar insulation materials based on mechanical damage characteristics

The damage impact of mechanical shocks on stator bar insulation is a key factor in high-voltage motor accidents. This study conducted electrical aging acceleration and breakdown experiments on damaged stator insulating materials to understand failure causes and evaluation methods. The relationship between sample defect area and depth and electrical properties was analyzed, along with the morphology of the damaged surface using a scanning electron microscope. Results show that the defect area correlates with impact mode but does not directly impact electrical performance. Effective insulation thickness is positively linked to electrical performance. This study serves as a valuable reference for evaluating mechanical impact faults in high-voltage motors.

Impact of electrical aging on x-ray image quality and dose rate with vertically aligned carbon nanotube based cold cathode electron beam (C-beam)

The adoption of vertically aligned carbon nanotubes (VACNTs) as electron emitters in x-ray generation has opened a new path for medical imaging technology advancement. With their outstanding electron emission capabilities, VACNTs provide a distinct advantage in miniaturizing and improving the performance of x-ray devices. This research focuses on the effect of electrical aging on x-ray imaging quality and the dose rate while using VACNTs as the electron source. The study includes a thorough examination of the electrical aging effects on VACNT-based x-ray systems, with an emphasis on changes in emission characteristics, beam stability, and the resulting variations in x-ray output. Experiment results show that electrical aging has a considerable impact on the performance of VACNT-based x-ray sources, with visible changes in electron emission parameters and subsequent consequences on x-ray imaging quality. Furthermore, the study investigates the relationship between electrical aging and the x-ray dose rate, providing vital insights into radiation exposure optimization in medical diagnostics.

Aging and life control of cross-linked polyethylene as cable insulation material

Cross-linked polyethylene (XLPE) has been widely used in the field of power cables due to its excellent mechanical properties and insulating properties. However, during the manufacturing of high voltage cables, XLPE will inevitably be affected by electrical aging, thermal aging and electro-thermal combined aging, which makes the resistance and life of the material decline. Therefore, it is necessary to enhance the aging resistance of XLPE without affecting its mechanical properties and insulating properties, so as to extend its service life. In this work, the structural characteristics and cross-linking mechanism of XLPE are introduced, the aging process and influencing mechanism are systematically analyzed, and the life decay problems of XLPE due to aging are explored by using methods such as the temperature Arrhenius equation and the inverse power law of voltage. The improvement strategies such as grafting, blending, and nanoparticle modification can be used to enhance the thermal stability, antioxidant properties, and thermal aging resistance of XLPE, thereby extending its service life. Finally, the strategies of adjusting and controlling the service life of XLPE cable insulation materials in the future are discussed, which provide theoretical guidance for further improving long-term stable operation of XLPE cable insulation materials.