Mode Shift Research Articles

“Yb modification of bismuth Ferrite: Unveiling Optical, Dielectric, and electrochemical properties for advanced applications”

This study explores the detailed impact of Yb3+ substitutional doping on the structural, optical, dielectric, and electrochemical characteristics of bismuth ferrite. Rigorous structural analysis conducted via X-ray diffraction confirmed the formation of a rhombohedral distorted perovskite structure, within the R3C space group. The investigation of crystallite size showed a reducing trend as Yb3+ content increased. Morphological studies revealed the presence of finely dispersed nanocrystalline grains, exhibiting particle size within the range from 281 to 197 nm. Raman spectroscopy unveiled notable phonon mode shifts towards higher wavenumbers, correlating with increased Yb3+ doping concentrations. Additionally, a discernible reduction in bandgap energy, from 2.15 to 1.98 eV, was observed with increasing doping levels. An improved dielectric response was observed with Yb3+ doping. Electrochemical assessments, employing cyclic voltammetry and galvanostatic charge–discharge techniques, revealed the superior electrochemical performance of the 30 % Yb-doped bismuth ferrite-modified electrode, demonstrating a specific capacitance of 575 Fg−1 at a scan rate of 10 mVs−1. These findings underscore the tailored engineering of Yb-doped bismuth ferrite nanoparticles, positioning them as promising candidates for the next generation of supercapacitor devices.

Effect of longitudinal reinforcement ratio on residual flexural capacity of high-strength reinforced concrete beams exposed to impact loading

In this study, it was aimed to investigate the dynamic impact and post-impact performances of high-strength reinforced concrete (RC) beams, which have different ductility and load-bearing capacities. The dynamic behavior and impact damages of RC beams were compared after exposure to a constant magnitude of impact energy. The applied impact energy was obtained by dropping a mass of 360 kg from a certain height of 3 m. The cross-section dimensions and length of the specimens were selected to carry out the experiments in full-scale. The tested specimens were designed with five different longitudinal reinforcement ratios for demonstrating distinct structural behavior mechanisms that vary from pure flexure to pure shear, representing different ductilities, load-bearing capacities and potential failure characteristics. The post-impact behavior of the impacted RC beams was also assessed by performing quasi-static bending tests on the impact-damaged specimens and the obtained results were compared with the identical undamaged reference RC beams. The results demonstrated that the longitudinal reinforcement ratio (which was intentionally designed for different specimens to exhibit different structural responses from pure shear to pure flexural and different shear-flexure mechanisms) significantly influences the dynamic response and damage intensity of the beams, which, in turn, affect their post-impact static performance. Key structural characteristics, including residual displacement, ductility, energy dissipation, load-carrying capacity, and stiffness, were analyzed. It was found that the mechanical properties of the beams deteriorated markedly after impact exposure. A crucial finding of this research is the notable shift in failure modes from flexural to shear after impact, depending on the damage severity. In RC beams, shear damage remains insignificant under both impact loading and subsequent static loading when the ratio of shear strength to flexural strength (Vr/Mr) exceeds 1.5. Conversely, when this ratio is less than 1.5, the behavior transitions to being shear-critical or shear-dominant. This study presents, for the first time, comprehensive experimental results on the impact-induced damage progression, failure mechanisms, and residual behavior of high-strength RC beams. These insights are vital for understanding the performance of RC structures under impact loads and contribute significantly to the field of structural engineering, particularly in designing impact-resilient structures.

Effect of intercalant-assisted exfoliation of Sb2Se3 on preparation of thin layers

The atomically thin sheets of Sb2Se3 hold a great potential in semiconductor applications. The present work reports intercalant-assisted exfoliation methods using various types of intercalants for the preparation of Sb2Se3 thin layers. Bulk Sb2Se3 was intercalated with H2O, PVP, Na+ and Li+ and thereby exfoliated ultrasonically. The structural analysis indicated the absence of certain planes in exfoliated samples, whereas the Raman analysis illustrated a distinct layer-dependent Raman shifts of vibrational modes. The bulk and exfoliated samples, when exposed electrochemically to H+ and K+ ions exhibited unique redox activity, which was correlated to the thickness of the exfoliated layers. The intercalating ability of intercalants was compared to the degree of exfoliation and found to be highest for ionic intercalants.

Earth’s metamorphic secular evolution accessed by rutile

Rutile provides crucial insights into the evolution of plate tectonics and variations in tectonomagmatic modes over Earth’s history primarily because rutile predominantly tracks higher-pressure metamorphism (>1.0–1.2 GPa). Comparison of rutile age and compositional data with diverse proxies tracks the presence of low temperature/pressure (T/P) metamorphic conditions, enabling the tracing of plate tectonics onset and evolution. We present a new compilation of rutile U-Pb ages that lag zircon ages by approximately 50 Myr, potentially indicating cooling ages of metamorphic belts. The earliest rutile age peak (ca. 1.8 Ga) aligns with the oldest evidence for low T/P metamorphic conditions. This coincides with a shift in the T/P distribution of rutile whereas the T/P of Archean rutile forms a tight normal distribution. In the Paleoproterozoic, the rutile T/P distribution is skewed to lower T/P, following the broader pattern of the full metamorphic record. The degree of lower T/P skew increases through time until the lower T/P population dominates the rutile record from the Neoproterozoic to the present. These data further highlight shifts in dominant metamorphic modes that can be tied to the evolution of the tectonic system, with early Archean metamorphism being associated with plume-driven vertical tectonics or hot, shallow subduction and post-Archean metamorphism being associated with progressive less plume-driven vertical tectonics and colder, steeper subduction. Although the frequency of rutile is lower during the Mesoproterozoic, the rutile T/P during this time follows the progressive skewing pattern from the Paleoproterozoic to the present and is likely inconsistent with a phase of interrupted tectonics characterized by stagnant lid.

Experimental investigation on the macro- and micromechanical properties of water-cooled granite at different high temperatures

To investigate the damage mechanisms in granite’s physical and mechanical properties after high-temperature water quenching, this study employed MTS815.04 for uniaxial compression tests on thermally treated specimens, with concurrent acoustic emission monitoring, and utilized nanoindentation for micromechanical analysis. The results show that with increasing temperature, granite's peak strength and elastic modulus decrease, with a sharp decline after 400–500 °C, corresponding to a significant increase in the internal damage, which can be detected by acoustic emission monitoring. Below 500 °C, macroscopic mechanical degradation is due to mineral thermophysical property differences, while above 500 °C, microcrack development is the main deterioration factor. The failure mode shifts from tensile to tensile-shear complex to shear failure, with transition points at 400 °C and 800 °C. The results of this study are of certain reference value for improving the efficiency of extracting thermal energy from dry-hot rocks and providing security guidance for the tunnel restoration process following fire damage.

Physical and chemical characteristics of plasma-activated water generated by hybrid dielectric barrier discharge and gliding arc discharge

This research explores the synergistic application of Dielectric Barrier Discharge (DBD) and Gliding Arc Plasma Jet (GAPJ) in a Hybrid Plasma Discharge (HPD) setup for enhanced water activation. The HPD system demonstrated balanced and sustained generation of reactive oxygen and nitrogen species (RONS), maintaining efficiency at higher specific input energy (SIE) values. Comparative analyses with DBD and GAPJ systems highlighted the superior performance of the HPD system in generating RONS and modifying water’s molecular structure. Key observations included a decrease in water’s pH and an increase in oxidation-reduction potential, total dissolved solids, and conductivity, stabilizing beyond 5 l min−1 airflow and 10 min of treatment. UV−Vis spectroscopy identified nitrites, nitrates, hydrogen peroxide, and nitrous acid, while Raman spectroscopy captured shifts in vibrational modes, particularly in librational and O–H stretching bands. These changes correlated with alterations in reactive species concentrations and pH levels. Overall, the HPD system emerged as a versatile and efficient approach for generating plasma-activated water, suitable for applications in microbial deactivation, surface sterilization, and electrocatalytic process optimization, offering stable and continuous production of reactive species across a range of SIE values.

Street redesign, active mobility and well-being for Pacific elders

ABSTRACT This qualitative study uses Talanoa methodologies to explore the everyday experiences of Pacific elders travelling around Māngere Central, Aotearoa New Zealand. A suite of street infrastructure changes for walking and cycling took place in the area between 2015 and 2017. While the evidence linking attributes of urban street design to physical activity behaviour is strong, there is little research on the impact of the built environment on Pacific elders’ active mobility. The study seeks to address this knowledge gap by focusing on the impacts of streetscape changes on the active travel and social connectivity of this group of residents. Findings indicate that post-intervention, elders feel significantly safer while walking, with active travel increasing for some. All elders in the study feel that important amenities are now more accessible, with some of significant cultural and social importance. As such, opportunities for social connection appear to have increased. Furthermore, the enhanced look and feel of the local environment is important to the elders interviewed, enhancing feelings of community pride and well-being for some. Further desired changes to support active mobility are discussed, and a logic model highlighting factors theorised to be particularly important for achieving mode shift among Pacific elders is proposed.

Post-fire performance of GFRP reinforced concrete deep beams: experimental and numerical study

Fire resistance of Glass Fiber Reinforced Polymer (GFRP) reinforced concrete members is an important concern in concrete structures. The experimental study of the structural response of GFRP reinforced concrete deep beams exposed to the ISO 834 standard fire is presented in this paper. To this end, a number of 7 specimens including 2 control and 5 fired specimen, have been subjected to monotonic static loading after exposure to fire. Shear span-to-depth ratio (a/d), horizontal distributed web reinforcement, and concrete compressive strength were the primary variables in the experiments. The results showed that after exposure to fire, ultimate capacity of the members decreases; and no changes occur in the initial stiffness of the members. Furthermore, the failure mode of specimens becomes more brittle and less ductile. Additionally, increasing a/d results in a decrease in the load bearing capacity and a shift in failure mode from pure shear to more ductile modes. By comparing the crack widths at failure point, obtained from image processing, it was found that in the beams with the small a/d ratio which are more shear dominant, after fire exposure, the maximum width of the cracks decreases.

Shear behavior of seawater sea-sand concrete beams reinforced with BFRP bars after seawater dry-wet cycling

The shear behavior of 27 basalt fiber-reinforced polymer reinforced seawater sea-sand concrete (BFRP-SSC) beams after seawater dry-wet cycling was comprehensively investigated. Parameters considered included stirrup diameter and spacing, shear span-to-depth ratio, stirrup surface treatment, cycling duration, concrete cover thickness, and seawater temperature. Results indicate that seawater dry-wet cycling increases cracking load and decreases bending stiffness in BFRP-SSC beams. Increasing shear span-to-depth ratio from 1.55 to 2.35 led to load reductions of 31.3 % and 49.7 % at 6.5 mm mid-span deflection. Seawater dry-wet cycling, particularly temperature and duration, significantly impacts the mechanical properties of stirrups. This results in diminished shear contribution and reduced efficacy in inhibiting diagonal crack propagation, leading to a shift in beam failure mode from diagonal compression failure to shear compression failure and diagonal tension failure. Increasing cycling duration from 60 to 120 days decreased tensile strength retention by 19.1 % and 33.3 % respectively. Based on experimental data, Arrhenius theory, and the time shift factor (TSF) method, a predictive model was developed for the shear capacity retention of beams subjected to seawater dry-wet cycling. Results indicate that after 100 years in a tidal environment (70 % and 90 % relative humidity), shear capacity damage factors of 0.77 and 0.52, respectively, can be applied to account for the impact of seawater dry-wet cycling on the shear capacity of BFRP-SSC beams.

Towards a digital zemiology

Surveillance capitalism (Zuboff, 2019) represents an unprecedented shift in modes and asymmetries of power. Operating within and through the digital sphere, this new era of capitalism has drastic implications for our understandings of modern surveillance, corporate power, and social control. The digital, in its diffuse simultaneously online and offline form, represents the spatialisation of control within which the user and the data they produce are commodified and their identities consolidated and dissected into knowable, marketable demographics which, once reassembled, no longer represent the human being once behind them (Hammond, 2016; Brusseau, 2020). The digital represents a new frontier of harm production, as user-generated data is exploited to serve corporate interests and the normalisation of digital surveillance has given way to user apathy and technological reliance, undermining user autonomy and opportunities for resistance, while commodifying not only our identities but the entirety of the human experience. Within this context an opportunity emerges to develop a zemiology informed by the digital context that can confront the deepening harms of technologisation and consider the future of resistance. By interrogating the intersection between developments in digital technology and harm production, this article aims to acknowledge the proliferation of normalised corporate surveillance through a development in capitalism (Zuboff, 2015; 2019), and to outline opportunities for theoretical development presented by the digital context, drawing upon works within zemiology (Pemberton, 2016), surveillance studies (Murakami Wood, 2007; Murakami Wood and Ball, 2013), postphenomenology (Ihde, 1990; Verbeek, 2011; Wood, 2021; 2022), and disconnection studies (Kuntsman and Miyake, 2022), to present an invitation to both a unique theoretical orientation and an emerging field of study: digital zemiology.

Experimental study of ultra-high-performance fibre-reinforced concrete (UHPFRC)-encased CFST short columns under axial and eccentric compression

This study presents a comprehensive experimental programme and analysis of ultra-high-performance fibre-reinforced concrete (UHPFRC)-encased concrete-filled steel tube (CFST) columns subjected to axial and eccentric compression. Twelve short columns were tested, with six of them utilising UHPFRC encasement while the other six employing normal strength fibre-reinforced concrete (FRC) encasement for comparison purpose. The study focused on the effects of load eccentricity ratio, concrete encasement type, and steel tube configuration. Key findings from the test results including failure modes, load-deflection behaviour, moment-curvature relationships and curvature ductility were examined. The findings showed that UHPFRC-encased CFST columns exhibited significantly enhanced strength and bending capacity, while FRC-encased columns showed remarkable ductility. A notable shift in failure mode was observed with increasing load eccentricity ratio, transitioning from crushing of concrete to compression, and then to balanced failure. Furthermore, applicability of prevalent design codes such as EC4, AIJ, and ACI 318 in calculating the peak loads of UHPFRC- and FRC-encased CFST columns was assessed. The plastic stress distribution methods in EC4 and AIJ overestimated peak loads, while ACI 318's strain compatibility approach accurately predicted FRC-encased columns but not UHPFRC-encased columns. To address this, modifications of the parameters α and β were incorporated into the ACI design method to reflect the relative brittle nature of UHPFRC, resulting in accurate predictions.

Skin thickness effects on failure mechanisms in foam infilled composite sandwich structures

Sandwich structures are often prone to catastrophic failure due to premature separation between the core and skin layers. Geometric parameters, such as the thickness of the skin and core, along with the materials used in their manufacturing, directly influence the resistance to separation between the skin and core. This study explores how variations in skin thickness affect both failure modes and maximum load capacity in sandwich structures, utilizing both experimental testing and numerical simulations. Specimens were categorized as intact and pre-debonded samples. Each specimen featured four different skin thicknesses (3, 6, 8, and 10 layers of composite laminated skins, with corresponding thicknesses of 0.68, 1.33, 1.73, and 2.1 mm respectively). The specimens incorporated a foam-filled square corrugated core and underwent 3-point bending tests. Results revealed a significant shift in the failure mode: initially observed as upper skin fracture (V-shaped failure), it transitioned to separation between skins and cores with increased skin thickness, particularly in the presence of pre-debonding. Notably, the predominant failure mode did not involve separation between the skin and core in specimens without a pre-existing crack. Furthermore, numerical simulations effectively demonstrated the accurate capture of failure modes and loads using the Hashin and cohesive zone model (CZM).

Leptin gene expression in the brain is associated with the physiological onset of estivation in western sand lance Ammodytes japonicus.

Dormancy is an essential ecological characteristic for the survival of organisms that experience harsh environments. Although factors that initiate dormancy vary, suppression or cessation of feeding activities are common among taxa. To distinguish between extrinsic and intrinsic causes of metabolic reduction, we focused on estivation, which occurs in summer when the feeding activity is generally enhanced. Sand lances (genus Ammodytes) are a unique marine fish with a long estivation period from early summer to late autumn. In the present study, we aimed to elucidate the control mechanisms of estivation in western sand lance (A. japonicus), and firstly examined behavioral changes in 8 months including a transition between active and dormant phases. We found that swimming/feeding behavior gradually decreased from June, and completely disappeared by late August, indicating all individuals had entered estivation. Next, we focused on leptin, known as a feeding suppression hormone in various organisms, and examined leptin-A gene (AjLepA) expression in the brain that may regulate the seasonal behavioral pattern. AjLepA expression decreased after 7 days of fasting, suggesting that leptin has a function to regulate feeding in this species. The monthly expression dynamics of AjLepA during the feeding (active) and non-feeding (estivation) periods showed that the levels gradually increased with the onset of estivation and reached its peak when all the experimental fish had estivated. The present study suggests that the suppression of feeding activity by leptin causes shift in the physiological modes of A. japonicus before estivation.

Microstructure and Mechanical Properties of Multilayered Ti-Based Bulk Metallic Glass Composites Containing Various Thicknesses of Ti-Rich Laminates.

In order to optimize the balance between strength and toughness, a series of multilayered Ti-based bulk metallic glass composites (BMGCs) with varying thicknesses of Ti-rich layers were successfully fabricated. The findings reveal that with an increase in the thickness of the Ti-rich layers, both the flexural yield strength and ultimate strength decreased from 2066 MPa and 2717 MPa to 668 MPa and 1163 MPa, respectively. Conversely, there was a noticeable increase in flexural strain. The fracture toughness of these multilayered Ti-based BMGCs decreased as the thickness of the Ti-rich layers increased; nevertheless, it stabilized at approximately 80 MPa·m1/2 when the thickness reached 100 μm. It was observed that a shift in the dominant deformation mode may be accountable for this phenomenon. These noteworthy characteristics suggest that adjusting the thickness of Ti-rich layers in multilayered BMGCs can effectively optimize mechanical performance, shedding light on the manufacturing of novel BMGCs with high performance.

Labrador Coastal Current and productivity variations offshore Nain (Nunatsiavut) during the late Holocene

The Labrador Coastal Current (LCC) transports cold and fresh waters of Arctic origin towards the North Atlantic and has a strong influence on the coastal ecosystems and climate of eastern Canada. Here, we present a multi-decadally resolved record of changes in sea-surface and near-bottom conditions of the LCC during the last 3000 years based on the analysis of biogenic tracers (organic-walled dinoflagellate cysts, carbon, and nitrogen geochemistry) and sedimentary content (sortable silt, magnetic susceptibility, elemental ratios) in the upper 2 m of sediments in a core retrieved offshore Nain, Nunatsiavut. Our data reveal multi-centennial bottom flow strength variability in the LCC, with strong linkages to changes in regional ocean circulation patterns. At about 2100- and 550-years BP, the sedimentological and biogenic tracer data suggest changes in the LCC bottom current intensity (decline and strengthening, respectively) that coincide with shifts in the persistent mode of the North Atlantic Oscillation. Our proxy data suggests increased biological production during the last 500 years compared to the preceding 2500 years, possibly reflecting a gradual decrease length of the sea-ice season. The data show a decline in the LCC strength during periods of increased polar water influence identified in previous palaeoceanographic studies conducted further north, which may be attributed to the trapping of freshwater in sea ice during these periods. Our results highlight the dynamical oceanographic and atmospheric factors that influence the LCC and the coastal ecosystems along its path and confirm that the processes in Baffin Bay impact the Labrador Shelf oceanography.

Impact of glyphosate on the rhizosphere microbial communities of a double-transgenic maize line D105

Plant roots shape the rhizosphere microbiome, recruiting microbes with beneficial functions. While genetically engineered crops offer yield advantages, their impacts on rhizosphere microbial communities remain understudied. This study evaluated the effects of transgenic maize, alongside a non-transgenic counterpart, on rhizosphere bacterial and fungal community composition using 16S rRNA and ITS amplicon sequencing. Additionally, glyphosate was used to evaluate its impact on microbial assembly and the magnitude of its effect at various maize growth stages. The results showed that transgenic maize D105 line significantly increased bacterial alpha diversity but not fungal diversity. Beta diversity analysis showed clear separation between bacterial and fungal communities at higher glyphosate treatment. Specific bacterial taxa such as Pseudomonas and Sphingomonas were enriched, while fungal taxa such as Ascomycota, Lasiosphaeriaceae, Verticillium were differentially abundant in glyphosate treatments. LEfSe analysis identified distinct enrichment patterns of bacterial (Proteobacteria and Actinobacteria) and fungal taxa (Verticillium and Guehomyces) associated with the transgenic line and glyphosate levels. KEGG functional analysis suggested potential impacts on bacterial metabolic pathways and shifts in fungal trophic modes (saprotrophs, pathogens) within the rhizosphere microbiome. This research provides insights into the classification, functional relationships, and underlying mechanisms shaping microbial communities carrying insect resistance and glyphosate resistance traits.

Enhanced Interlayer Interaction in Top‐Layer Twisted Trilayer MoS2 with Moiré Superlattice

AbstractMoiré superlattices, induced by an angular mismatch in layered materials provide a new index of freedom to manipulate the correlated electron states and many‐body properties of excitons. Here, trilayer MoS2 homostructures with the 3R configuration between the middle (M) and the bottom (B) layer and the top‐to‐middle (T‐M) interlayer twists ranging from 10° to 40° are fabricated via NaCl‐assisted chemical vapor deposition. The twist‐dependent interlayer interactions are systematically investigated by polarized low frequency (PLF) and high frequency (HF) Raman spectroscopy. PLF Raman results show that the energy shift in the shear mode, the breathing modes of LB31 and LB32 is respectively the much in 14°‐ and 28°‐T‐M twisted trilayer, among as‐prepared trilayer MoS2 homostructures. Moreover, the T‐M twist further affects the optical properties of the twisted MoS2 trilayer, evidenced by the photoluminescence (PL) spectroscopy. Moiré excitons are enhanced in the top‐layer twisted MoS2 trilayer with a T‐M twists of 28°, which may originate from the interlayer exciton trapped by the periodical moiré potential. The present work demonstrates that the trilayer homostructures tuned by interlayer twists can be an ideal system to tune the energy band structures and exciton properties for their potential applications in the nano‐optical electronics.

RECAR: Robust and efficient collision-avoiding routing for 3D underwater named data networking

Internet of Underwater Things (IoUT) has important application prospects in fields of both scientific research and commercial business. As a future network architecture, Named Data Networking (NDN) is starting to be applied to IoUT. Although Underwater Named Data Networking (UNDN) has unique advantages in dealing with bandwidth usage, multi-path forwarding, and node mobility, there is still no specific routing protocol for UNDN. The existing underwater routing protocols are either difficult to combine with NDN, or are limited by channel collision and redundant forwarding, especially broadcast suppression routing. In this paper, we propose a routing method named Robust and Efficient Collision-Avoiding Routing (RECAR) for 3D UNDN. RECAR consists of three combined forwarding modes: Directive Mode (DM), Directive Flooding Mode (DFM), and Flooding Mode (FM). In DFM, we propose Segmentation Suppression for Optimal Position (SSOP), an elaborate waiting time algorithm of broadcast suppression which can effectively reduce channel collisions and redundant forwarding. For DM, failure path recovery and unreliable path elimination are proposed to address failure paths. Additionally, several forwarding efficient mechanisms are designed including flexible mode shift, unified data forwarding and scope control. Simulation results show that RECAR has excellent and robust performance, even in the cases of node failure and void hole. Compared with a recent underwater routing method (adaptive location-based routing protocol), RECAR improves the average interest satisfied rate by 19.57% while reducing the request time, collisions, redundant forwarding, total traffic, and energy consumption by 19.5%, 91.7%, 71.4%, 78.4%, and 27.3%, respectively.

Modelling policy scenarios: refocussing the model-policy logic for the case of German passenger transport

BackgroundNational energy and climate scenarios are typically simulated or optimised using sectoral or energy system models, which include a large number of model settings and scenario assumptions. However, their realisation is contingent upon framework conditions and policy settings, which are often included in accompanying narrative scenarios. This paper therefore proposes refocussing the model-policy logic towards directly modelling policy effects. Applying this approach to the case of German passenger transport, I focus on demand-side policies and use open-source databases and models to develop a module for the translation of policies into model parameters.ResultsSeparate model runs were used to test a ceteris paribus policy reference scenario for 2035, the marginal impacts of modelled single policy effects, and a joint policy package scenario. Relative to the reference, demand-side policies show significant impacts: an annual reduction of 355 bn person-kilometres (30%) and a reduction of car-owning households from 95 to 90% in rural areas and from 76 to 64% in urban areas. The resulting mode shift decreases car-driven kilometres by 400 bn and increases public transport by 45 bn per year. This may reduce GHG emissions by an additional 30 Mt (or 33%) relative to the reference in 2035.ConclusionsTransport demand policies can significantly mitigate GHG, calling for a stronger policy focus beyond the much-studied shift to electric vehicles. While further research and model development are needed, the feasibility of policy scenario modelling increases its utility for policy-making.

Enhanced surface performance of insulating ceramic by plasma polymerization with nanosecond-pulse dielectric barrier discharge: Insight into the effect of the repetition frequency

Insulating ceramics are widely used in power systems, but their high polarity makes them prone to wet and pollution flashover. In this paper, an Ar/polydimethylsiloxane dielectric barrier discharge excited by a parametric nanosecond-pulse power source is utilized for plasma polymerization to enhance ceramic surface insulating performance. Diagnosis of the discharge characteristics and surface physiochemical properties is conducted at different repetition frequencies to investigate the mechanism associated with the relationship between repetition frequency and the plasma polymerization process. The results indicate that a superhydrophobic surface can be achieved at repetition frequencies above 2 kHz. This transformation brings about multiple effects, including a decrease in surface polarity, an increase in charge dissipation, and an improvement in surface dry and wet flashover voltages. It is discovered that the discharge mode shifts from homogeneous to filamentary due to the memory effect of high repetition frequencies. Additionally, several filaments are generated simultaneously during a single pulse, facilitating the polymerization reactions. For high repetition frequencies, a low-polarity silicon-containing film with micro-nanometer structures is deposited on the ceramic surface, while scattered polymer fragments are generated on the surface without a cross-linked film for repetition frequencies below 2 kHz, despite longer treatment durations.