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This paper presents new findings on partial discharge (PD) phenomena under high-repetition nanosecond pulsed voltages, essential for the insulation design of electrical motors fed by silicon carbide (SiC) inverters with high-switching frequencies. Here, a twisted pair sample simulating the turn-to-turn insulation of a random-wound motor coil winding was subjected to high-repetition nanosecond pulsed voltages generated by a SiC inverter-based pulse generator. In this experiment, the rise time at a pulsed voltage of 1.5 kV is 23 ns, the pulse width is 500 ns, and the pulsed repetition frequency (PRF) ranges from 60 pps to 1 Mpps. In this PRF range, the partial discharge inception voltage (PDIV) was found to be almost constant. Meanwhile, the repetitive partial discharge inception voltage (RPDIV) significantly reduced when the PRF exceeded several tens of kpps. Under high PRF conditions, the high-density ions produced by the preceding PD remain in the gap space between enameled wires during the pulse-off period and contribute significantly to the initiation of subsequent PD. The resulting increase in the probability of PD occurrence reduces the RPDIV. Unlike previous reports, this study clarified the difference in the frequency characteristics between PDIV and RPDIV, providing valuable reference data for the insulation design of SiC inverter-fed motors. Based on the obtained results, we propose revising the IEC60034-18-41 standard, which verifies a PD-free system, to incorporate the effect of the pulsed voltage waveform of SiC inverters.

Abstract Arc discharge in the power transformer can bring enormous economic losses and safety risks. The transformer protection system for arc discharge faults is still not ideal. The physical characteristics of the whole process from partial discharge defects transition to arc faults are not fully recognized, mainly because it is difficult to establish and sense the relevant characteristic parameters. This paper built a research platform for studying the transition process from partial discharge to early arc discharge based on fibre‐optic ultrasonic, temperature, pressure sensors with traditional electrical voltage and current sensors. Five discharge models are designed and the changing pattern of multiple parameters in the transition process of different models is studied. The experiment results show that the amplitude and frequency of acoustic waves drop significantly after the arc breakdown. Ultrasonic and high‐frequency current sensing in the early warning of arc fault each has its own limitations. The pressure caused by the arc is not only related to the arc energy but also related to the discharge types. The overall oil temperature change after the early arc discharge is small and hard to detect. This work highlights the promise of using fibre‐optic sensors for physical process research within a harsh electromagnetic environment.

Introduction. We won’t be able to solve global ecological problems without solving the energy issue. It is necessary to expand the energy sector and switch to energy saving technologies. Power generation is among sources of negative impacts on the environment and man. The emission of carbon dioxide into the atmosphere, discharge of polluted liquid waste into rivers, creation of huge water reservoirs, warming of water bodies, depletion of fuel resources, deforestation, emission of toxic substances into the atmosphere and water, burial of radioactive waste - this list of negative impacts, produced by the energy sector on the environment, is not exhaustive. At the end of the 20th century, humanity finally realized how serious the problem of carbon dioxide in the atmosphere was. The consolidation of these two issues, namely, environmental protection and conservation of natural resources, tightened the requirements for the construction of buildings in terms of thermal insulation, reduction of energy consumption for heating, and introduction of a closed power cycle at production facilities. The article deals with construction of passive multi-storey houses in different climatic conditions of the Russian Federation. The problem of energy saving and thermal insulation of buildings in construction is addressed. The analysis of energy consumption by passive buildings in the climatic conditions of Central Russia is made..Materials and methods. Currently, heating consumption by all types of buildings during the heating season in Russia is analyzed in accordance with Annex G of SNiP 23-02-2003. In addition, a national standard of the Russian Federation was developed, approved and put into effect by Decree of the Federal Agency for Technical Regulation and Metrology No. 1211-st dated October 25, 2013. This standard is amended in relation to ISO 13790:2008. This Russian standard is a regulatory document on annual heat and electricity costs of maintaining the microclimate on heated or cooled premises.Results. The technology has advanced, and now the construction market offers houses with seamless facades and improved sound and heat insulation. These are monolithic frame houses with good thermal insulation, since monolithic concrete is poured directly into the formwork on the construction site, lined with glass wool thermal insulation and clad with facade panels, which reduces heat loss from a building.Conclusions. The analysis of the energy consumption calculation method has proven an efficient tool to determine the heat demand of heating systems. The calculation allows to determine heat losses associated with the transfer of heat through an external envelope and the need for thermal energy. In other words, given that the data for each climatic zone is correct, including selected construction materials, thickness of enclosure structures with account for solar energy, and the proper use of modern intake-exhaust systems, the construction of buildings, featuring higher energy efficiency in the climatic conditions of Central Russia, is possible and absolutely realistic.

This paper attempts to ascertain the thermal and acoustic impacts of introducing a vegetative roof layer on insulated and uninsulated metal roofs for tropical climates, through field measurements in Skudai, Johor, Malaysia, that were conducted for both dry and wet days. Four small-scale roof modules were tested, namely an uninsulated metal roof (uiMDR), an insulated metal roof (iMDR), and two identical corresponding modules with an additional vegetative component (uiGR and iGR, respectively). Outdoor ambient temperature (Tamb) was the most influential correlated variable affecting the roof outer surface temperature (RTOS) in 50% of the assessed scenarios. On the selected dry day, the inter-quartile ranges (IQR) of iGR, iMDR, uiGR, and uiMDR were 6.21 °C, 8.32 °C, 6.69 °C, and 1.66 °C, respectively; the IQRs were 1.6 °C, 4.11 °C, 2.59 °C, and 1.78 °C, respectively, on the selected wet day. Based on design U-value calculations, iGR was better than iMDR and uiMDR for both dry and wet days. The U-value of uiGR was also better than iMDR under dry-day conditions. The Wilcoxon signed-rank test also indicated a statistically significant difference in the roof inner surface temperature (RTIS) measurements (p-value = 0.00) during Malaysian daylight hours, between 8.00 a.m. and 6.00 p.m., regardless of the weather. In terms of sound level reduction under dry-day conditions, the Kruskal–Wallis and Wilcoxon signed-rank tests showed statistically significant differences in sound level reductions, with iGR and uiGR performing better than iMDR and uiMDR (p-values = 0.00). The sound level reductions for iGR, iMDR, and uiGR were 51%, 32%, and 31%, respectively, while uiMDR experienced sound level amplifications by 6%, possibly due to the acoustic resonance effect. This proof of concept may encourage a broader application of extensive GRs in Malaysia using metal roofs, beyond the conventional RC base construction method.

On a global scale, millions of tons of diverse agricultural residues are generated annually. Most of these wastes are burned or dumped in landfills, which causes environmental pollution. Addressing environmental issues arising from agricultural waste materials, in addition to mitigating heating and cooling expenses in the construction sector, is an interesting challenge for researchers. The utilization of agricultural wastes in different parts of construction is producing positive findings day by day, and investigating research in this field is a curiosity for researchers. This short study reviewed the most recent achievements in using agricultural wastes as a substitute or additive material for construction. Using these wastes as aggregate, ash (as a supplementary for cement), or fibers for foam concrete, insulation materials, etc. has been reviewed. This review has focused on very recent published papers. Several studies have demonstrated the effective influences of agro-waste materials in construction, like retaining the compressive strength (155 MPa) of concrete at standard levels and reducing heat losses in buildings (69% energy savings for brick insulated using wheat straw), as well as sound insulation. The use of agro-waste materials for insulation positively improved thermal conductivity, costs, and energy savings. However, some wastes did not provide a high added value, which shows that more investigations still need be performed to fill this gap in the research. Considering the global scale of agricultural waste generation and the potential benefits to both the environment and construction industry, continued research in this area is essential.

This paper investigates the performance of novel nano ZnO filled polyamide nanocomposites under hydrothermal conditions for cable insulation applications. Neat polyamide (PA0) and its nanocomposite with 0 wt% (PA0), 1 wt% (PA1), 3 wt% (PA3), 5 wt% (PA5), and 7 wt% (PA7) of nano ZnO were prepared and subjected to accelerated hydrothermal aging conditions in a programmable chamber at 85 °C and 85% relative humidity for 300 h. The samples were analyzed with visual inspection, hydrophobicity evaluation, optical microscopy, Fourier Transform Infrared (FTIR) spectroscopy, leakage current and UV–vis spectroscopy after every 100 h of aging. Scanning Electron Microscopy (SEM) and x-ray Diffraction (XRD) were employed for analyzing filler dispersion. Maximum filler dispersion was achieved in the case of 3 wt% of nanofiller. All the samples expressed surface degradation and increase in leakage current after aging. Maximum surface roughness and highest leakage current of 7 μ A were noticed for PA0, however PA3 expressed lowest leakage current and surface degradation. PA0 expressed the lowest hydrophobicity class of HC-3 and lowest contact angle of 75° after aging. Among the nanocomposites, PA3 expressed the highest hydrophobicity class (HC-1) and contact angle (112°) after aging. FTIR results expressed that all the samples suffered from oxidation and the C=O peaks at ∼1728 cm ^−1 increased by 120%, 100% and 120% for PA1, PA3 and PA7 respectively. The peaks of –OH group at ∼3500 cm ^−1 increased for all the sample indicating moister absorption. However, it is observed that the addition of nanofiller enhanced the overall performance of composites and among the composites PA3 performed better.

The present research aimed to investigate a charging of the cylindrical insulation layer of wires for space applications under the influence of isotropic electron radiation with an electron injection uniform in the volume of the dielectric. An analytical solution of the first-order differential equation resulting from the proposed charging model is obtained. A software has been developed and received state registration that allows for a complete calculation of the physical parameters of space-application wires resistant to electrification effects. The obtained results are proposed to be used for modeling and testing of wires for space applications in order to completely exclude the physical possibility of the occurrence of electrostatic discharges (ESR) of the "insulation–core" type during the operation (of the spacecraft) in orbit during geomagnetic disturbances in the Earth's magnetosphere. [ABSTRACT FROM AUTHOR]

Abstract Over the last few decades, the rivalry between regulatory convergence and divergence has dominated scholarly debate. In accordance with this divide, countries tend to either converge toward Basel rules, becoming globally standardized players, or diverge from them, leaving their local institutions untouched, particularly within developmental States. Banking regulation in Argentina, Brazil, Chile, and Mexico, however, brings challenging evidence to that debate. Brazil, which, from among the group, has most converged toward Basel rules, relies on a sizeable developmental State. Argentina, which has also widely converged, relies on significant State intervention in the financial system. Conversely, Chile, a market-friendly country, has not adhered to international capital rules on the same level. Finally, Mexico has been in-between, reinforcing State-owned banks and adopting the new Basel standards, however, to a lesser degree, compared to Brazil. These findings support the claim that such countries combine global and local institutions more diversely than the convergence-divergence divide predictions would suggest.

Sandwich panels (modular panels) promote optimal solutions to some major issues prevailing in the construction industry such as increased energy consumption by building elements, excessive disposal of constructional waste and unproductive time spent during construction. Hence, the inclination towards sandwich elements has been increased vastly deviating from conventional building construction materials and methods. However, the potentiality of using locally available natural materials for the development of sandwich panels is a salient sustainable approach that needs to be addressed. This study evaluates the current and potential materials used in modular panels and key properties of sandwich panels including mechanical, thermal insulation, and sound insulation properties. Moreover, various test methods followed, and standards specified to investigate the mechanical, thermal and acoustic insulation properties are also discussed. The possibility of using coconut fibre as a locally available natural alternative core material to polyurethane core of sandwich panels has been evaluated using simulations based on the material properties obtained from literature. The study identifies coconut fibre as a potential alternative core material for sandwich roof panels as it reflects nearly similar thermal behaviour to polyurethane.

Packed-bed thermocline tank with sensible fillers is a cost-effective option for thermal energy storage (TES). In real charging and discharging, the thermocline stability is disturbed and thermocline expansion occurs due to various factors, leading to the decreased global performances of storage tank. The purpose of this work is to experimentally and numerically study the impact of inlet configuration and insulation on the thermocline expansion in a lab-scale tank under various operating parameters. Firstly, a DC-3P model considering the wall effect and heat loss is developed and validated by experimental results, capable of precisely predicting the performance of storage tank under the tested conditions. Especially, the temperature difference between the fluid and solid filler center is detected both in experiments and in modeling, indicating the existence of temperature gradient inside large solid particles. Results also show that the injecting flow causes the radial temperature non-uniformity and thermocline expansion at the near-entrance region of the tank, but its effect on the global performance of the storage tank is rather limited. Good insulation of the tank could reduce the thermocline thickness by about 20%, and increase the energy efficiency and the capacity ratio by 5–7% and 3–5%, respectively. [ABSTRACT FROM AUTHOR]

Partial discharges were caused by abnormalities of electric fields in insulating material; typically, sharp points and edges provide a concentration of electric field intensity. This work intends to investigate partial discharge (PD) current that results from irregular surfaces in nanocomposites insulation material; PD current in XLPE insulation of power cables has been caused by air voids, water voids, and rubber impurities. This research applied novel single and multiple nanocomposites to enhance electrical products utilizing nanotechnology techniques. In order to improve electrical products using nanotechnology techniques, new individual and multiple nanocomposites have been designed in this research. Therefore, it has been examined on the effects of partial discharge current in single-core power cables utilizing modern theoretical approaches. [ABSTRACT FROM AUTHOR]

Background: Kidney transplantation is the current optimal treatment for suitable patients with end‐stage renal disease. The second warm ischemic time (SWIT) is known to negatively impact delayed graft function, and long‐term graft survival, and methods are required to ameliorate the impacts of SWIT on transplantation outcomes. Materials and Methods: This study primarily focused on determining the effect of a novel thermally insulating jacket on the thermal profile of the human kidney and quantifying the reduction in thermal energy experienced using this device (KPJ™). An ex vivo simulated transplantation model was developed to determine the thermal profiles of non‐utilized human kidneys with and without KPJ™ (n = 5). Control kidney temperature profiles were validated against the temperature profiles of n = 10 kidneys during clinical kidney transplantation. Results: Using the ex‐vivo water bath model, the thermally insulated human kidney reached the 15°C metabolic threshold temperature at 44.5 ± 1.9 min (vs control: 17.3 ± 1.8 min (p = 0.00172)) and remained within the 18°C threshold until 53.3 ± 1.3 min (vs control: 20.9 ± 2.0 min (p = 0.002)). The specific heat capacity of KPJ™ protected kidney was four‐fold compared to the control kidney. The clinical temperature audit, closely correlated with the water bath model, hence validating this ex‐vivo human kidney transplant model. Conclusion: Intraoperative thermal protection is a simple and viable method of reducing the thermal injury that occurs during the SWIT and increasing the specific heat capacity of the system. Such technology could easily be translated into clinical kidney transplant practice. [ABSTRACT FROM AUTHOR]

To investigate the dielectric strength and mechanical features of modified nitrile butadiene rubber (NBR), titanium dioxide (TiO 2) and magnesium oxide (MgO) nanoparticles have been used. Specimens have been experimentally prepared with loading various concentrations (0.5, 1, 1.5 and 3 parts per hundred part of rubber "Phr") to NBR base material. The dielectric strength has been evaluated by applying AC high voltage on the prepared samples up to reaching the breakdown state. On the other hand tensile strength, elongation at break and modulus at 100% elongation have been experimented to exploration the mechanical features of the NBR enhanced by nanoparticles. Although all the recorded results of modified NBR samples showed improvement more than the base material at dielectric, tensile strength and modulus at 100% elongation tests. The elongation at break result showed a negative impact; it was caused by forming a new links between NBR and nanoparticles. The dielectric constants of applied nanoparticles are greater than NBR base materials, which can physically explain the improvement in all recorded breakdown results. But the enhancement in the measured mechanical features can be attributed to chemical bonds which were reconstructed and the gaps of NBR base material that had been filled. [ABSTRACT FROM AUTHOR]

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The conversion process from parahydrogen to orthohydrogen accompanies an endothermic effect. Embedment of a para-ortho hydrogen converter into the thermal insulation could enhance the thermal protection of a liquid hydrogen storage tank. A physical model was proposed to simulate the heat transfer behavior of the insulation structure that integrates a polyurethane foam, a blanket of multilayer insulation, a vapor-cooled shield, and a para-ortho hydrogen converter. The effect of the para-ortho conversion process was considered. The model was validated by experimental data and then used to investigate how the para-ortho hydrogen conversion influences the temperature distribution inside the composite insulation. It was found that a single converter improves the cooling performance most effectively if it is placed at the middle length of the venting pipe mounted on the vapor-cooled shield. Either incorporating more converters or extending the length of the vapor-cooled shield pipes brings limited further improvement. The optimum position of the vapor-cooled shield inside the multilayer insulation moves towards the cold boundary in the presence of para-ortho conversion, compared to conventional vapor-cooled shield and multilayer insulation structures. A net heat flux reduction of over 10% could be achieved when the para-ortho conversion is located at the optimal position inside the vapor-cooled shield. [Display omitted] • Thermal insulation with para to ortho conversion (POC) for LH 2 tanks is studied. • Factors influencing POC cooling performance are analyzed. • Vapor-cooled shield (VCS) temperature decreases in presence of POC. • Optimum VCS position moves towards the cold boundary in presence of POC. • Net heat flux reduces up to 10% for an insulation structure by introducing POC. [ABSTRACT FROM AUTHOR]

The degradation of the insulation system in liquid-filled power transformers is a serious concern for electric power utilities. The insulation system's ageing is accelerated by moisture, acids, oxidation products, and other decay particles (soluble and colloidal). The presence of these ageing by-products is detrimental to the insulation system and may further lead to premature ageing and serious consequences. The ageing mechanisms of oil-paper insulation are complex, highly interrelated, and strongly temperature-dependent. The operating temperature of the transformer insulating system has a direct relationship with the loading profile. The major aspect that is witnessed with the fluctuating temperatures is moisture migration and subsequent bubble evolution. In other words, gas bubbles evolve from the release of water vapor from the cellulosic insulation wrapped around the transformer windings. The models presented in the existing standards, such as the IEC Std. 60076-7:2018 and the IEEE Std. C57.91:2011, are mainly based on the insulation temperature, which acts as a key parameter. Several studies have investigated the moisture dynamics and bubbling phenomenon as a function of the water content in the paper and the state of the insulation system. Some studies have reported different prototypes for the estimation of the bubble inception temperatures under selected conditions. However, there are various attributes of the insulation system that are to be considered, especially when expanding the models for the alternative liquids. This paper reviews various evaluation models reported in the literature that help understand the bubbling phenomenon in transformer insulation. The discussions also keep us in the loop on the estimation of bubbling behavior in alternative dielectric liquids and key attributable factors for use in transformers. In addition, useful tutorial elements focusing on the bubbling issue in transformers as well as some critical analyses are addressed for future research on this topic. [ABSTRACT FROM AUTHOR]

An electrical insulation made as a hollow circular cylinder with unlimited length is considered under a constant difference of electric potentials on cylindrical surfaces. The cylinder material is a composite with a polymer matrix modified by heat-conducting dispersed granules improving characteristics of the electrical insulation. The nonlinear mathematical model of the temperature state of the electrical insulation is constructed for given density of the heat flow on the inner surface of the cylinder and the heat exchange conditions specified on its outer surface. Results of the quantitative analysis of this model allow us to determine the maximal potential difference just before the thermal explosion of the electrical insulation and to find out possible applications of polymer composites with heat-conducting dispersed inclusions as dielectrics in various high-voltage electrical and electro-physical devices, among others, as electrical insulation of conducting strands of high-voltage DC cables. [ABSTRACT FROM AUTHOR]

The efficient use of our existing energy resources is as important as finding new energy sources, since the demand for energy is increasing day by day. Heating and cooling loads in buildings constitute a large part of energy consumption. Therefore, it is very important to improve the energy performance of buildings. The utilization of phase change materials to increase the energy efficiency of buildings is one of the recent research topics. In this study, the effect of phase change materials on room temperature for winter and summer months was investigated numerically by defining real environmental conditions in the virtual environment. Phase change material with thermophysical properties suitable for Mediterranean climate conditions was selected for summer and winter. It can keep the room temperature at a slightly lower level during the daytime in summer and the room temperature higher in winter than in the insulated state case. As a result, phase change materials can be used as a natural air conditioner in the summer, as well as a natural heater at night in the winter. On the other hand, smart bricks can be produced that can absorb the heat transmitted from the inside to the outside by using different phase-change materials. [ABSTRACT FROM AUTHOR]

Purpose: High permittivity dielectric pads are known to be effective for tailoring the RF field and improving image quality in high field MRI. Despite a number of studies reporting benign specific absorption rate (SAR) effects, their "universal" safety remains an open concern. In this work, we evaluate the impact of the insulation material in between the pad and the body, using both RF simulations as well as phantom experiments. Methods: A 3T configuration with high permittivity material was simulated and characterized experimentally in terms of B1+ fields and RF power absorption, both with and without electrical insulation in between the high permittivity material and the sample. Different insulation conditions were compared, and electromagnetic analyses on the induced current density were performed to elucidate the effect. Results: Increases in RF heating of up to 49% were observed experimentally in a tissue‐mimicking phantom after removing the material insulation. The B1+ magnitude and RF transceive phase were not affected. Simulations indicated that an insulation thickness of 0.5–2 mm should be accounted for in numerical models in order to ensure reliable results. Conclusion: A reliable RF safety assessment of high permittivity dielectric pads requires accounting for the insulating properties of the plastic encasing. Ignoring the electrical insulation can lead to erroneous results with substantial increases in local SAR at the interface. Conversely, the material insulation does not need to be modeled to predict the B1+ effects during the design of the pad geometry. [ABSTRACT FROM AUTHOR]

This paper presents a finite element analysis of a steel beam's behavior under fire. The studied structure is an unprotected HEB300 type, which was taken from the literature. In the first part of this study, the numerical model of the unprotected HEB300 beam was validated using numerical and experimental results from the literature and in the second part, the validated numerical model was used to study the concrete insulation effect on the beam thermo-elastoplastic behavior. In both parts, two analyses were carried out consisting of a thermal study to assess the temperature distribution along the beam as a function of time, followed by a thermo-elastoplastic analysis to evaluate the beam displacement. The result for the first part shows that the present finite element method predicts well the beam thermo-elastoplastic behavior. These results are very close to those of the literature. The use of a concrete insulator in the second part reduced the section average temperature from 800 °C to 125 °C and the vertical displacement from 120 mm to 3 mm for a duration of 35-minute fire exposure. [ABSTRACT FROM AUTHOR]

The use of Magnesium in the automotive field is diverse, it is necessary to source raw materials. One of the raw materials for magnesium can be obtain from nature which can be done by electrolysis and thermal reduction processes. Electrolysis is a chemical reaction process of decomposition by electric current in electrolytes with the help of electrodes. The electrolysis process to obtain magnesium requires a minimum temperature of around 725°C. This article discusses the design and manufacture of electrolysis devices with fuel using coke and wood charcoal. The methodology carried out includes design in the form of soft drawings, determination of tool dimensions, furnace design, air supply line design, temperature control device placement, argon gas line placement, coal fuel placement, and material selection. The manufacturing stage of electrolysis equipment includes the manufacture of furnaces consisting of the manufacture of the outer frame of steel plates, the installation of refractory stone insulation, the placement of air supply lines, the installation of blowers, the placement of argon gas lines, the placement of graphite electrodes. Placement of power supply in the form of an adapter that can be adjusted the voltage. The results of MgCl2 electrolysis equipment have dimensions of a diameter of 325 mm and a height of 500 mm. The insulation thickness of the refractory stone is 120 mm. The size of the crucible diameter is 125 mm, and the height of the crucible is 160 mm. The time to reach a furnace temperature of 725°C is achieved within 20 minutes with a mixture of coal and wood charcoal fuel. [ABSTRACT FROM AUTHOR]

The Electroluminescence (EL) technique has garnered significant interest over time for its reliable outcomes that enrich our understanding of the onset of electrical degradation in polymeric material. There is growing interest in combining both the EL technique and space charge measurement methods to obtain a more profound knowledge of the degradation and ageing of insulation. The generation of charge carriers in polymeric materials is widely acknowledged to be a crucial aspect of EL, involving injection, de-trapping, and field dissociation processes. This research investigates the variables that influence how EL emissions behave, including applied voltage or electric field, applied electrical frequency, ageing of material, and selection of materials and gases employed. It was found that these factors can be helpful in predicting the process of electrical ageing in insulation to avoid any catastrophes that may occur. A mathematical approach relating these factors and the intensity of EL is proposed through the aid of Dimensional Analysis method. A close relationship is obtained that suggests this mathematical approach can be utilised as a tool to predict electrical ageing of insulation material. [ABSTRACT FROM AUTHOR]

The excessive migration of small molecular plasticizers in solid propellants may lead to debonding and changes in combustion characteristics, affecting the safety of solid rocket motors. Herein, two functionalized graphene oxides (GO) were used to enhance the anti-migration performance of EPDM insulation. GO, 3-Aminopropyltriethoxysilane-modified GO (AGO) and octadecylamine-modified GO (HGO) were filled into EPDM to fabricate EPDM insulation. The anti-migration properties and migration kinetics of EPDM insulations were studied using immersion tests. Moreover, the mechanical properties, including the tensile properties, crosslink density, hardness, and aging resistance of different EPDM insulations, were also explored. Compared with GO, AGO, and HGO obviously enhanced the anti-migration and mechanical properties of the EPDM insulations. This study shows that the anti-migration performance of EPDM insulation can be enhanced by functionalized GO. [ABSTRACT FROM AUTHOR]

Ever since energy efficiency provisions were introduced into the National Construction Code in 2003, there have been increased requirements for energy-efficient measures with each iteration of the code, particularly around insulation. This is based on the often-repeated objective of reducing Australia's greenhouse gas emissions in the light of climate change. However, there is limited evidence whether the code achieved its stated objectives and whether these will continue to be suited to a changing climate. In fact, there is evidence that the intended and achieved goals are substantially different. This paper is a critical essay, set in the context of the Australian Building Codes Board's scoping study into "Energy efficient measures for 2022 and beyond", and makes the case that current insulation requirements are already excessive against considerations that should be made, as a higher priority, for fire safety, thermal bridging, condensation, heat stress resilience and thermal comfort. [ABSTRACT FROM AUTHOR]

Calculations of the technical and economic effect from the use of thermal and electroosmosis-based drying methods in relation to agricultural production have been carried out according to the developed algorithms. For this purpose, the study compares oven drying (OD) (drying box SNOL 3.5?3.5 for EM 0,25–2,2 kW, drying box with heaters 10 kV for EM 3–55 kW), electrodynamic drying (ED) (three-phase transformer for device power supply TTD-2,5, transformer TD-102), electroosmotic drying (EOD device), convective drying (CD) (CD device), convective-electroosmotic drying (CED) (CED device). EOD is free from shortcomings being characteristic of heat drying methods; since it does not require disassembly and dismantling of the electric motors at the workplace, increased power consumption and does not contribute to thermal degradation of the insulation. Based on the electroosmotic method of drying, electroosmothermal and convective-electroosmotic drying have been developed. The economic effect from the introduction of the developed devices for electroosmotic drying is ensured by increasing labor productivity by 1.5–11.4 times, saving electricity by 80–1,230 times, depending on the power of the ED, and also increasing the durability of insulation by reducing destruction to zero (electroosmotic drying and moisture protection) or reducing it by 10 times (convective-electroosmotic drying).

The construction of protected housing in Spain during the period analysed (1939–1989) reached its maximum between 1950–1980 with the construction of almost three million homes per year. The analysis of the homes built for railroad workers from this housing stock is distinct for four main reasons: it is a housing stock with a representative number of homes in relation to the total of social housing built in Spain, which is still mostly in use and covers all the typologies used in the country and which is dispersed throughout it. Thus, for the present analysis, there is a sample that is adequately representative of the whole stock of social housing constructed in Spain, this sample enables a comparative global analysis that can be extrapolated to the remaining stock. The objective of this study is to analyse the energy efficiency of homes through the thermal analysis of the envelope, as well as to acknowledge the specific constructive limitations of these homes and if possible, their rehabilitation that guarantees compliance with the required standards regarding sustainability and energy efficiency set by the Sustainable Development Goals (SDGs) established in the 2030 Agenda. This is a crucial goal to achieve, as the Spanish building stock currently consumes 30% of the total energy consumed, in addition to the socioeconomic profile and the potential for energy poverty, there is a portion of social housing with a precarious construction lacking the heating facilities, which is required due to the weather, with a significant potential for savings and the incorporation of renewable energies.

Glia are essential to protecting and enabling nervous system function and a key glial function is the formation of the glial sheath around peripheral axons. Each peripheral nerve in the Drosophila larva is ensheathed by three glial layers, which structurally support and insulate the peripheral axons. How peripheral glia communicate with each other and between layers is not well established and we investigated the role of Innexins in mediating glial function in the Drosophila periphery. Of the eight Drosophila Innexins, we found two (Inx1 and Inx2) are important for peripheral glia development. In particular loss of Inx1 and Inx2 resulted in defects in the wrapping glia leading to disruption of the glia wrap. Of interest loss of Inx2 in the subperineurial glia also resulted in defects in the neighboring wrapping glia. Inx plaques were observed between the subperineurial glia and the wrapping glia suggesting that gap junctions link these two glial cell types. We found Inx2 is key to Ca2+ pulses in the peripheral subperineurial glia but not in the wrapping glia, and we found no evidence of gap junction communication between subperineurial and wrapping glia. Rather we have clear evidence that Inx2 plays an adhesive and channel-independent role between the subperineurial and wrapping glia to ensure the integrity of the glial wrap. [ABSTRACT FROM AUTHOR]

This study examined the potential of hydrolysable tannin in comparison to condensed tannins for the production of furanic foams. The results indicate that chestnut tannin presents lower reactivity and requires a stronger acid for the polymerization. Additionally, foamability and density were found to be dependent on both surfactant concentration and tannin type, allowing lower densities for mimosa tannin and lower thermal conductivities for chestnut-based foams. Mimosa tannin was found to have the highest compression strength, followed by quebracho and chestnut, promising thermal conductivity of around 50 mW/m·K for 300 kg/m3 foams, which suggests that chestnut foams have the potential to performing highly when the density is reduced. Chemical analysis revealed that the methylene moieties of the furanics are non-specific and produces new covalent bonds with nucleophilic substrates: -OH groups and free-positions in the flavonoids. Overall, this study opens new perspectives for the application of hydrolysable tannins in polymer and material science. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) applied in energy storage and temperature control system are important for energy conservation and environmental protection. In this work, structure-adjustable water-borne polyurethane (WPU)/boron nitride (BN) aerogels were synthesized via directional freeze-drying method, and used as supporting scaffolds to confine paraffin wax (PW) and obtain composite phase change materials. The three-dimensional (3D) porous thermal conductivity network of BN was derived by the in-situ ice crystal mound in aerogel, which endows the PW/WPU/BN composite PCM-2.5 with high thermal conductivity (0.96 W m−1 K−1) and high energy storage density (140.04 J/g). Shape-stabilized PCMs with high thermal conductivity and excellent electrical insulation prepared by the simple method have great potential for the thermal management of electronic products. [ABSTRACT FROM AUTHOR]

Electrical insulation failure is the most common failure mechanism in electrical machines (motors and generators). High temperatures and/or temperature gradients (HTTG) are the main drivers of insulation failure in electrical machines. HTTG combine with and augment other destructive effects from over-voltage, to voltage transients, overload and load variations, poor construction techniques, and thermal cycling. These operating conditions cause insulation damage that leads to electrical insulation failure. The insulation failure process is greatly accelerated by pollutants and moisture absorption. A simple and robust way to reduce HTTG and moisture adsorption is by maintaining constant internal temperatures. The current method to maintain elevated internal temperatures and reduce condensation issues is by internal electrical heating elements. This paper examines the effectiveness of applying thermoelectric coolers (TECs), solid-state heat pumps (Peltier devices), as heaters to raise a motor's internal temperature by pumping heat into the motor core rather than heating the internal air. TEC technology is relatively new, and the application of TECs to heat a motor's internal volume has not previously been explored. In this paper, we explore the hypothesis that TECs can pump heat into a motor when out of service, reducing the HTTG by maintaining high winding slot temperatures and eliminating condensation issues. This paper describes a test motor setup with simple resistive heating (traditional method), compared with the application of TECs with heat sinks, heat pipes, and a water circulation heat exchanger, to gauge the capability of TECs to heat the inner core or winding area. In this paper, we demonstrate the full integration of TECs into a motor. The results show that each of the systems incorporating the TECs would effectively pump heat into the core and keep the winding hot, eliminating condensation issues and water ingress due to thermal cycling. [ABSTRACT FROM AUTHOR]

Because of the low utilization rate, a large amount of metallurgical slag was piled up or buried each year, resulting in serious environmental pollution and resource waste. This study focused on the value‐add utilization of secondary aluminum dross (SAD) and ferronickel slag (FNS) by preparing porous cordierite–mullite ceramics (CMC) for thermal insulation. The detailed thermodynamic calculation of the preparing process was carried out by using the phase diagram and equilibrium component function module in FactSage 8.1 software, which provided precise theoretical guidance for the practical synthesis experiment. The phase component, microstructure, and mechanical and thermal insulation properties of the prepared CMC at an FNS addition from 5 to 30 wt% were investigated by an X‐ray diffractometer, scanning electron microscopy assembled with an energy‐dispersive spectrometer, and a laser thermal conductivity testing instrument, respectively. It was shown that the original mineral phase of the raw materials applied can be converted to cordierite, mullite, and spinel after sintering at 1350°C, which results in higher strength and lower thermal conductivity of the prepared ceramics. Moreover, the increase of FNS addition promoted the content of cordierite and the microstructure densification of CMC. With the increase of FNS addition, the apparent porosity of CMC decreased from 41.7% to 34.4%, and the average pore size varied from 46.7 to 29.0 μm. The CMC with the lowest thermal conductivity of 0.86 W/(m K) was achieved at 20 wt% of FNS addition, which also had a good compressive strength of 52.8 MPa. The results proved the feasibility of preparing high‐strength thermal insulation ceramics by recycling hazardous metallurgical slag of SAD and FNS, proposing a novel route for high value‐added utilization of industrial solid waste. [ABSTRACT FROM AUTHOR]

In this article, an air-isolated module with adjustable insulation based on magnetic coupling resonance is proposed for high-voltage pulse generators. The insulation level can be adjusted rapidly over a wide range by changing the air gap. By virtue of invariable dielectric properties of air, the module can avoid electrical aging and reduce the risk of electrical breakdown. Tests are performed from insulation and power supply, respectively. Finally, a 24-stage air-isolated pulse generator prototype is tested. The results reveal that dc isolation level of the proposed module can be easily changed in a wide range, while maintaining stable power supply to multiple gate drivers. This module, which is no less cheap and light than existing isolators, provides a high compatible isolating solution in solid-state pulse generators under different applications. [ABSTRACT FROM AUTHOR]

Inter-turn short circuit (ITSC) is a common fault in electrical machines, which may result in further devastation to the whole winding and magnets. In this article, a method for real-time residual insulation capacity monitoring of ITSC fault in permanent magnet synchronous machines (PMSMs) is proposed, which is robust to speed/torque variation and independent of machine parameters and extra sensors. It is based on the theory that the ITSC fault initiates as an insulation deterioration among adjacent turns and the fault severity can be described by the residual insulation capacity being relevant to the 2nd harmonic component in the dq-axis currents. Thus, a short-time Adaline-based harmonic extraction method is proposed for the separation of the needed 2nd harmonic component from time-varying current signals, being used as the fault indicator afterward. Finally, the performance of the proposed method is experimentally evaluated on a PMSM and shows quite good performance in fast-tracking and detection of faults in various stages. [ABSTRACT FROM AUTHOR]