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Rubber asphalt has excellent durability and can maintain excellent performance under harsh service conditions. In order to further promote the application of rubber asphalt, the dynamic rheological shear test was used to test the complex shear modulus G *, rutting factor G */sin δ, fatigue dissipation factor G * sin δ of rubber asphalt under different test temperatures and loading frequencies. The conclusions are as follows: (1) For the dynamic rheological properties of rubber asphalt, the content of rubber powder is an important factor. When the rubber powder content is 30%, the rheological properties of rubber asphalt are optimal. (2) For the rutting factor and fatigue dissipation factor of rubber asphalt, temperature and frequency are the primary influencing factors. The rutting factor and fatigue dissipation factor of rubber asphalt samples in each group decrease with increasing temperature and increases with increasing frequency. (3) Among the three types of rubber powder-mixed rubber asphalt, the 30% rubber asphalt has higher high-temperature performance and fatigue performance, which can meet the performance requirements of the pavement surface layer.

Transformer reliability is strongly governed by the condition of insulating oil; however, limited studies have directly compared real-time aged transformer oil with standardized accelerated-aged oil or evaluated nanofluid performance in aged insulation systems. This study presents a novel comparative framework that first standardizes accelerated aging by matching its dielectric behavior and fault gas signatures with real-time aged transformer oil, and subsequently evaluates the effectiveness of mineral oil-based nanofluids in mitigating aging-induced degradation. Real-time aged and accelerated-aged oils were comparatively evaluated using dielectric constant, dielectric dissipation factor, resistivity, thermal conductivity, and dissolved gas analysis. To restore degraded insulation performance, nanofluids containing cerium oxide and zirconium oxide nanoparticles were prepared and aged under identical conditions. Optimal nanoparticle concentrations of 25 mg/L for cerium oxide and 37.5 mg/L for zirconium oxide were identified. At these concentrations, cerium oxide nanofluids exhibited improvements of + 21.05% in dielectric constant, + 88.47% in resistivity, − 39.27% in dielectric dissipation factor, and + 7.75% in thermal conductivity, while zirconium oxide nanofluids showed enhancements of + 28.07%, + 143.46%, − 40.24%, and + 9.58%, respectively, compared with aged mineral oil. Dissolved gas analysis further revealed a 30–40% reduction in key fault gas concentrations, resulting in a diagnostic shift from severe thermal faults to no-major-fault conditions. These improvements correspond to a 25–40% reduction in aging acceleration factor and an estimated 20–30% extension in insulation life. The results demonstrate the strong potential of cerium oxide- and zirconium oxide-based nanofluids as effective insulating fluids for enhancing the reliability and longevity of oil-immersed power transformers.

The widespread use of cross-linked polyethylene (XLPE) as insulation in cables may be attributed to its outstanding mechanical and dielectric properties. In order to quantitatively evaluate the insulation status of XLPE after thermal ageing, an accelerated thermal ageing experimental platform is established. Polarization and depolarization current (PDC) as well as elongation at break of XLPE insulation under different ageing durations are measured. XLPE insulation state is determined by the elongation at break retention rate (ER%). Based on the extended Debye model, the paper proposed the stable relaxation charge quantity and the dissipation factor at 0.1 Hz to evaluate the insulation state of XLPE. The results show that the ER% of XLPE insulation decreases with the growth of ageing degree. The polarization and depolarization current of XLPE insulation will increase obviously with thermal ageing. Conductivity and trap level density will also increase. The number of branches of the extended Debye model increases, and new polarization types appear. Stable relaxation charge quantity and dissipation factor at 0.1 Hz proposed in this paper have a good fitting relationship with ER% of XLPE insulation, which can evaluate the thermal ageing state of XLPE insulation effectively.

In this study, a series of ester-linked tetracarboxylic dianhydrides (TCDAs) with 2,6-naphthalene-containing longitudinally extended structures consisting of different numbers of aromatic rings (NAr = 6–8) was synthesized to obtain novel modified polyimides, poly(ester imide)s (PEsIs). These TCDAs were fully compatible with the conventional manufacturing processes of conventional polyimide (PI) systems. As an example, the PEsI film obtained from the ester-linked TCDA (NAr = 8) and an ester-linked diamine achieved unprecedented outstanding dielectric properties without the support of fluorinated monomers, specifically an ultra-low dissipation factor (tan δ) of 0.00128 at a frequency of 10 GHz (50% RH and 23 °C), in addition to an extremely high glass transition temperature (Tg) of 365 °C, extremely low linear coefficient of thermal expansion (CTE) of 6.8 ppm K−1, suppressed water uptake (0.24%), requisite film ductility, and a low haze. Consequently, certain PEsI films developed in this study are promising candidates for heat-resistant dielectric substrates for use in 5G-compatible high-speed flexible printed circuit boards (FPCs). The chemical and physical factors denominating tan δ are also discussed.

Understanding the fatigue behaviour of metallic materials is highly important when it comes to a reliable assessment of material degradation as a result of dynamic loading. Because the provision of such data is associated with great testing effort leading to increased time and cost requirements in terms of conventional methods, accelerated lifetime prediction methods are becoming increasingly important. However, the reduced number of fatigue specimens and tests complicates statistical validations of the obtained results. In this contribution, combinatorial approaches are used to estimate both lifetime prediction bands and virtually-determined S-N curves with a reduced number of specimens, displaying the material-related scatter due to microstructural inhomogeneities. In addition, a variable energy dissipation factor based on cyclic deformation curves is presented, which enables evaluation of materials that exhibit more pronounced scatter, for instance cast materials. An in situ evaluation of the cyclic deformation curves is provided via integration of non-destructive testing methods into the testing rig. Unalloyed SAE 1045 steel, low-alloyed 20MnMoNi5-5 steel, and the cast material EN-GJS-1050-6 are investigated in this research, as these materials posses gradually increasing complexity regarding their respective microstructures.

The current power cables IEC standards do not provide adequate recommendations for after-laying testing and diagnosis of offshore export and inter-array power cables. However the standards IEEE 400 and IEEE 400.4 recommend partial discharge monitored testing, e.g., by continuous or damped AC voltages (DAC). Based on the international experiences, as collected in more than 20 years at different power grids, this contribution focuses on the use of DAC for after-laying testing and diagnosis of submarine power cables both the export and inter-array cables. Higher risk of failure, long unavailability, higher repair costs, and maintenance costs imply that advanced quality control is becoming more important. The current state of the existing and drafting international standards are based on onshore experiences and not related to the actual serious problems experienced with failures on export up to 230 kV and inter-array cables up to 66 kV. The application of damped AC as a testing solution in this concern is specially discussed. The advantages of this testing technique, in combination with actual testing examples, show the findings on export and inter-array cables at offshore wind farms.

The dielectric behavior and properties of three types of Sarawak woods, under various conditions (untreated, alkaline treated, potassium carbonate treated, and heat treated), were investigated and discussed. The dielectric constant, loss, and dissipation factor tests were conducted via a dielectric impedance analyzer. The results revealed that the dielectric properties decreased in relation to an increase in frequency. With considerations to the treatment method, the highest dielectric constant values for the untreated samples were found in Kumpang wood, the highest dielectric constant values for the heat-treated samples and potassium carbonate treated samples were found in Keranji wood, and the highest dielectric constant values for sodium hydroxide treated samples were found in Kayu Malam wood. Therefore, it was evident that the physical properties, e.g., internal structure, density, moisture, temperature, etc., could affect the dielectric behavior and properties of the wood materials.

Experimental data on the electrical insulation in mineral oil are important for the optimal design of high voltage equipment in industrial power systems. In this paper, dielectric properties of mineral oil including breakdown voltage, dielectric dissipation factor, dielectric losses, relative permittivity and resistivity were analyzed. Effects of electrode system, distance between electrodes and the rate of voltage rise on dielectric properties of insulating oil were evaluated in accordance with ASTM D877 and ASTM D1816 standards. Breakdown voltages of insulating oil measured using both VDE (Verband Deutscher Elektrotechniker) electrodes and disk electrodes were compared in conformity with measurement standards. Measurements of dissipation factor, dielectric losses and relative permittivity were performed with IEC 60247 standard considering environmental temperature, applied voltage, power and higher frequency values that satisfy operating conditions. Resistivity of mineral oil also was calculated by using the results of the measurements. In the study, a detailed analysis of mineral oil at real operating conditions was realized. These results contribute to explore insulating characteristic of mineral oil in service.

Energy-dissipation elastomers relying on their viscoelastic behavior of chain segments in the glass transition region can effectively suppress vibrations and noises in various fields, yet the operating frequency of those elastomers is difficult to control precisely and its range is narrow. Here, we report a synergistic strategy for constructing polymer-fluid-gels that provide controllable ultrahigh energy dissipation over a broad frequency range, which is difficult by traditional means. This is realized by precisely tailoring the relaxation of confined polymer fluids in the elastic networks. The symbiosis of this combination involves: elastic networks forming an elastic matrix that displays reversible deformation and polymer fluids reptating back and forth to dissipate mechanical energy. Using prototypical poly (n-butyl acrylate) elastomers, we demonstrate that the polymer-fluid-gels exhibit a controllable ultrahigh energy-dissipation property (loss factor larger than 0.5) with a broad frequency range (10 −2 ~ 10 8  Hz). Energy absorption of the polymer-fluid-gels is over 200 times higher than that of commercial damping materials under the same dynamic stress. Moreover, their modulus is quasi-stable in the operating frequency range. In most cases the frequency range of a damping material is adapted to a specific application. Huang et al. design a gel filled with a polymeric fluid that bypasses this problem and offers an unusually broad window over which vibrational energy is effectively dissipated.

Topological phases feature robust edge states that are protected against the effects of defects and disorder. These phases have largely been studied in conservatively coupled systems, in which non-trivial topological invariants arise in the energy or frequency bands of a system. Here we show that, in dissipatively coupled systems, non-trivial topological invariants can emerge purely in a system’s dissipation. Using a highly scalable and easily reconfigurable time-multiplexed photonic resonator network, we experimentally demonstrate one- and two-dimensional lattices that host robust topological edge states with isolated dissipation rates, measure a dissipation spectrum that possesses a non-trivial topological invariant, and demonstrate topological protection of the network’s quality factor. The topologically non-trivial dissipation of our system exposes new opportunities to engineer dissipation in both classical and quantum systems. Moreover, our experimental platform’s straightforward scaling to higher dimensions and its ability to implement inhomogeneous, non-reciprocal and long range couplings may enable future work in the study of synthetic dimensions. Topological phenomena have mostly been studied in conservative systems. Experiments on optical resonator networks now show that topologically non-trivial characteristics can also emerge in dissipation.