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It is state-of-the-art to describe the dielectric behavior of an insulation material by its permittivity and its specific electric conductivity in order to estimate the dielectric stress of an insulation system. Thus, the electric field at DC voltage stress is determined according to the stationary electrical conduction field with the electric conductivity of the insulation materials. However, at oil-insulated arrangements a higher field strength in front of bare metal electrodes at high DC voltage stress occurs, which is not explainable with this model. Therefore, a charge carrier-based approach is presented to describe the dielectric behavior of the oil-paper insulation. It describes the movement of charge carriers and their effect on the electric field strength. Their drift leads to an accumulation of charge carriers in front of electrodes which results in a higher field strength in these areas, which can be calculated numerically using the Poisson-Nernst-Planck equation system. Compared to the conductivity-based model fundamental differences can be shown. Breakdown experiments qualitatively confirm the expectations according to the charge carrier-based approach. The results show that the charge carrier-based field distribution has to be considered for modelling the electrical field strength distribution at high DC voltage stress. They also show, that the dielectric behavior of these arrangements cannot be explained according to the state-of-the-art model. [ABSTRACT FROM AUTHOR]

Activation energy is popularly used for the estimation of remaining life of transformer insulation. It is defined as the average rate of all reactions that happen with cellulose. Existing literature shows that the activation energy of oil–paper insulation can be obtained from polarization depolarization current (PDC) and return voltage measurement (RVM) data that are measured at a specific temperature. It is practically difficult to ensure the same measurement temperature for both PDC and RVM data. On the other hand, PDC data and its analysis get influenced by de-trapping current. This de-trapping current is generated by ionic charge carriers that get freed from trap sites during PDC measurement process. Formation of these trap sites is related to physical, chemical reactions that happen at oil–paper interface. This paper proposes a methodology which uses de-trapped charge, dislodged from deep and shallow traps, to assess insulation condition and for the prediction of activation energy. Thus, eliminating the need of RVM data. The proposed method is tested using data collected from various real-life in-service transformers. [ABSTRACT FROM AUTHOR]

The converter transformer epoxy impregnated paper bushing is a multi-media electrical equipment, and the main materials include the internal conductor, the external conductor, transformer oil, SF6 gas, the air inside internal conductor, the main insulation material epoxy impregnated paper, sheath, and fittings. In actual operating, the converter transformer bushing is undertaken by the harmonic current with large number of high harmonics and the temperature distribution of the epoxy impregnated paper converter transformer bushings under actual current waveform needs to be researched. What's more, the temperature distribution of the epoxy impregnated paper converter transformer bushings is affected by several factors and to provide basis for the optimization of bushings it's necessary to research about the impact of these factors on the temperature distribution of the epoxy impregnated paper converter transformer bushings. In this paper, on the basis of our previous paper [8], the 3-D temperature distribution of the 400 kV epoxy impregnated paper converter transformer bushing under actual current waveform with large number of harmonics has been simulated by using the computational fluid dynamics (CFD) and finite element method (FEM) analysis. The temperature distribution regularity of the 400 kV converter transformer bushing under different influencing factors has been computed and analyzed. The dissipation structure of the bushing has been optimized and the DC steady-state electric field distribution of the 400 kV converter transformer bushing has been obtained considering the temperature gradient in epoxy impregnated paper. [ABSTRACT FROM PUBLISHER]

A quantitative analysis supports the argument that very low acceptance rates of conference papers are more likely to impede publication of bold and innovative research results than to indicate the chosen papers' prestige and elite status. [ABSTRACT FROM AUTHOR]

The recipients of the 2019 NSREC Outstanding Conference Paper Award are Joel M. Hales, Ani Khachatrian, Stephen Buchner, Jeffrey Warner, Adrian Ildefonso, George N. Tzintzarov, Delgermaa Nergui, Daniele M. Monahan, Stephen D. LaLumondiere, John D. Cressler, and Dale McMorrow for their paper entitled “New Approach for Pulsed-Laser Testing That Mimics Heavy-Ion Charge Deposition Profiles.” [ABSTRACT FROM AUTHOR]

Special Feature that lists the names of people involved in the review of technical papers for the IEEE Transactions on Industry Applications and Industry Applications Magazine. [ABSTRACT FROM AUTHOR]

This article presents a comparison between the results obtained at the application of a conservation treatment in cold high-frequency (HF) and afterglow plasma on historical papers dating in the 19th century. This article is focused on plasma biocide effects and on the impact of active species from the two types of plasma on the surface, highlighted by mechanical and physical–chemical analyses. The working gas was nitrogen and the treatment time was varied from 5 to 10 and 15 min. The result of physical–chemical analyses as SEM, pH determination, color, and tensile strength analyses, as well as microbiological investigations, converges to the conclusion that a treatment of 10 min achieves a complete decontamination, and the impact of active species is less intense in the afterglow plasma as compared to the direct discharge in cold HF plasma. [ABSTRACT FROM AUTHOR]

As a corrosive sulfur, dibenzyl disulfide (DBDS) is an efficient antioxidant in oil-immersed insulation. This study explored the reaction mechanism of corrosive sulfur with copper through heating experiments stipulated by IEC 62535. Thermal aging experiments were further conducted at 130 °C under nitrogen to investigate the comprehensive effect of the oxidation resistance and corrosivity of DBDS on the properties of oil-paper insulation. Experimental results showed that DBDS can decompose into corrosive benzyl mercaptan at a high temperature. Dibenzyl sulfide cannot corrode copper to form copper sulfide at 150 °C. Furthermore, the oxidation resistance and corrosivity of DBDS depend on the dynamic change in DBDS concentrations. This study suggests that 25 mg/kg should be used as the maximum additive content of DBDS in oil. With this additive content, the oxidation resistance of oil can be improved, and the corrosion damage of insulation winding can be controlled to a certain extent. [ABSTRACT FROM AUTHOR]

Vegetal oils are considered a suitable substitute for mineral oil that is widely used in power transformers as insulation and cooling medium. Due to the fact that more and more power transformers containing this alternative insulating fluid are being constructed a mathematical ageing models is needed to help predict transformer failures. The continued performance of power transformers depends on the condition of its paper insulation mainly. In this sense, this paper analyses Kraft paper degradation through the loss of its mechanical strength. Accelerated thermal ageing test of the paper in two different vegetal oils were carried out at three temperatures during diverse periods of time, in order to obtain information on the kinetics of the ageing degradation of the paper. The evolution of the mechanical properties of paper failure are analysed as a function of temperature and ageing time. In addition, the results obtained are compared with the traditional method of degradation analysis, based on the measurement of the degree of polymerisation. [ABSTRACT FROM AUTHOR]

This paper investigates the aging properties of oil-paper insulation under thermocorona discharge. The oil-paper insulation samples were heated and kept at 140°C, and a corona discharge was generated with a needle-plate at a frequency of 15 times/day, with each discharge lasting 5 minutes. The aging properties of oil-paper insulation were investigated by measuring the degree of polymerization (DP) of insulation paper samples along with the furfural content and acid value of the transformer oil samples. The results show that corona discharge at 140°C in oil rapidly decreased the insulation paper DP and increased the furfural content and acid value of the oil compared with thermal aging and corona discharge aging at 20°C. The DP of the insulation paper was reduced to 392.12, the furfural content in oil rose to 33.75 mg/L, and the acid value grew to 4.41 mgKOH/g after 15 days under the combined thermal stress and corona discharge. Both electric and thermal stress accelerated the aging of oil-paper insulation. This research has practical significance for understanding the process of insulation failure caused by the accelerated aging of oil-paper insulation. [ABSTRACT FROM AUTHOR]

This paper reports on a new method to measure the mobilities of both positive and negative charges in insulating materials based on space charge measurement in two-layer samples. To fulfill the condition of a unipolar carrier system, a blocking material is used as a barrier on one electrode thereby preventing charge injection to ensure the unipolar charges injected from the other electrode are transported through the bulk and accumulate at the barrier. Experimentally, the carrier mobility of oil immersed cellulose paper was obtained using the proposed method, and the result of mobilities of both positive and negative charges is presented. The temperature and field dependence of carrier mobility were also investigated, and the activation energies for negative and positive charges were calculated. The obtained carrier mobility of negative charges (majority electron carriers) is approximately 2 times of that of positive charges, and the charge migration can be interpreted by the thermally activated hopping conduction mechanism. [ABSTRACT FROM AUTHOR]

In order to develop a novel detection method for the degree of polymerization (DP) of insulating papers, methanol was used as an indicator to explore the relationship between methanol concentration and DP in this paper. After extraction from oil, the methanol was oxidized and reacted with chromotropic acid to generate a purple-red compound. The spectral detection method was used to detect the concentration of methanol by absorbance, and then, the corresponding relationship between the concentration of methanol and the DP of insulating paper was established. Moreover, the detection methods based on furfural and methanol were compared. The results showed that methanol appeared during the initial aging period of the insulation paper, and the linear relationship between the methanol concentration and the DP of insulating paper was good. Compared with furfural, methanol was more sensitive to the change of DP in the early aging period, which proved that methanol could be used as a new type of indicator of insulating paper. [ABSTRACT FROM AUTHOR]

In this paper, seven groups of sheet insulation for use in liquid nitrogen immersed power transformers have been tested under three different standard electrodes from ASTM D149-97a. The seven groups consist of three different types of paper/film, nonadhesive Kapton 100 HN (Kapton), THERNOMID 14.20 paper (NMN), and Nomex 410 paper (Nomex). The porous paper, Nomex 410, is found to have ac dielectric strength of 62–68 kV/mm, which is likely to be independent from its thickness. The nonporous film, Kapton, shows the dielectric strength of 288 kV/mm, whereas NMN paper has a dielectric strength of 74–78 kV/mm, larger than Nomex with similar thickness. Liquid nitrogen gaps near the triple junction of electrodes as well as liquid nitrogen pockets between the fibers are the main sources of partial discharge (PD) for NMN and Nomex. For Kapton, PDs are more likely to occur in the cavities filled with liquid nitrogen, either on the surface of the electrode or around the impurities on the surface of the film. Electrodes with a small stressed volume are more appropriate for dielectric tests of thin paper/film insulation, such as Kapton, due to the lower influence of cavities on the electrode surface. In contrast, electrodes with a large stressed volume and uniform electric field distribution are suitable for the papers such as Nomex and NMN. [ABSTRACT FROM AUTHOR]

Furfural content in oil has been shown to be a powerful indicator of the deterioration of cellulose paper. The furfural content in oil may increase greatly when the moisture content increases in transformers. The increase of furfural content in oil can be attributed to various factors, such as aging of cellulose paper with the increase of moisture content and the difference in furfural production mechanism. In this research, thermal aging tests of oil-paper system with different moisture contents are conducted under laboratory conditions to determine the cause of such increase. Furfural content, both in insulation oil and in insulation paper, and the degree of polymerization values of insulation paper were regularly measured. Results show that the moisture content plays a significant role on the production of furfural, and the high initial moisture content in insulation paper leads to large amount of furfural produced when DP decreases to the same values. The difference in the moisture content apparently affects the distribution of furfural between oil and paper, and the increase in the moisture content in oil-paper system increases the diffusion of furfural from the insulation paper to the oil. [ABSTRACT FROM AUTHOR]

Recent studies have reported that thermal aging of insulation paper affects its moisture absorption property, which can affect moisture equilibrium in oil-paper insulation. In engineering practice, Fessler's model is one of the most widely used methods to estimate the moisture content of paper through measurement of moisture content of oil. However, this model lacks consideration of the thermal aging effect on equilibrium moisture. This study comprehensively investigated the effect of thermal aging on moisture equilibrium in oil-paper insulation. Based on the accelerated ageing and moisture measurements, the equilibrium moisture content of insulation paper with different aging and temperatures were obtained. The effects of aging condition and the temperature on equilibrium moisture are discussed and Fessler's model was modified accordingly. The results show that: 1) the decreasing of specific surface area is the dominant factor that affects the moisture equilibrium in oil-paper insulation, which is caused by thermal aging; 2) the modified Fessler model is reasonable and suitable to estimate the equilibrium moisture content of insulation paper with different aging. [ABSTRACT FROM AUTHOR]

Designing clean, reusable, and repeatable experiments for a research paper does not have to be difficult. We report on our efforts to create an integrated toolchain for running, processing, and including the results of computer experiments in scientific publications. [ABSTRACT FROM AUTHOR]

The mechanical performance of two commercial papers used as solid insulation in power transformers, namely standard Kraft and a thermally upgraded Kraft paper, were studied during accelerated aging in Luminol oil at 170 ?C. The results show a relationship between the degree of polymerization and the mechanical properties measured by tensile testing. A linear relationship was found between the mechanical properties of paper, the tensile index (Tidx), and the concentration of methanol present in the oil. The methanol chemical marker has been proven to be an accurate assessment tool for the aging of cellulosic paper. The results show a promising tool for correlating the methanol concentration in oil, as an indirect indicator, with the mechanical performance of the paper. This approach can be used to monitor the real state of the cellulose chains in the power transformer insulation paper. [ABSTRACT FROM AUTHOR]

Presents the recipients of the Outstanding Conference Paper Award from the 2015 IEEE Nuclear and Space Radiation Effects Conference. [ABSTRACT FROM PUBLISHER]

Mobile and wireless communications are playing an irreplaceable role in our daily life. 5G is highly expected and can be considered as the convergence of mobile and wireless communications. This topic becomes one of the hottest research topics recently, and papers on this topic have been paid much attention. lists the top ten papers published in the IEEE Transactions on Microwave Theory and Techniques (TMTT) in 2019 with the highest numbers of Full Text View since published. Seven papers are about millimeter-waves (mm-waves), and because mm-waves multiple-input–multiple-output (MIMO) will be adopted globally, the 24.25–27.5-GHz band and 27–29.5-GHz bands are now approved worldwide as the standard 5G communication bands. The most popular paper is published by Asbeck et al. [item 1) in the Appendix] for mm-wave power amplifiers. [ABSTRACT FROM AUTHOR]

This study investigated the influence of the main metal materials of transformers on the oil-paper insulation performance. Ten types of insulating specimens were subjected to accelerated thermal aging at 120°C. Some aging parameters, including oil acid number, furfural content and degree of polymerization (DP) of insulating paper, were measured and compared. At the same time, we conducted frequency domain spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry on the insulating paper. The following conclusions were drawn: silicon lamination slightly deteriorates the insulating oil, copper increases the acidity and accelerates the production of furfural, metal materials can decrease DP of insulating paper and the effect of copper is greater than that of silicon lamination. During thermal aging, the dielectric dissipation factor of insulating paper increases and the carbon content of insulating paper increases. Metal materials can significantly increase the dielectric dissipation factor and carbon content of insulating paper and the effect of copper is greater than that of silicon lamination. [ABSTRACT FROM AUTHOR]

This paper reports on the behavior of red and black ink from a historical printed book, subjected to a plasma discharge treatment, applied for the decontamination and cleaning of naturally aged paper. As some preliminary experiments using high-frequency (HF) plasma showed a slight fading of red ink, the study was focused on the comparison of HF cold plasma and afterglow plasma treatments in order to get conclusive information on the effect of plasma active species on the red ink. Energy Dispersive X-ray Scanning Electron Microscopy SEM-EDX and Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy FTIR-ATR analyses were used for the identification of inks and binder, while the impact of plasma on inks was assessed by SEM analysis and color determinations. The experiments have been performed on an especially designed modular equipment, allowing the samples to be subjected alternately to HF cold plasma or afterglow plasma treatment. The study proved that direct HF plasma could result in a more important deterioration at treatment duration exceeding 5 min, while in afterglow plasma, this discoloration is not observable. The color fading is imputable to the corrosion of pigment crystallites produced by direct plasma discharge. [ABSTRACT FROM AUTHOR]

Epoxy resin-impregnated crepe paper (RIP) composites have been used as the inner insulation of dry condenser bushing in the ultra-high voltage direct current (UHVDC) power transmission system. In order to study the dielectric properties of pure epoxy resin and RIP composites, four kinds of samples (pure epoxy resin, RIP composites with 1, 2, 3 layers of crepe paper respectively) were prepared via the vacuum casting process. The Fourier transform infrared spectroscopy (FTIR) as well as three typical dielectric properties, i.e. complex permittivity, dc conductivity, thermally stimulated depolarization current (TSDC) have been investigated. It shows that the addition of crepe paper nearly brings about larger values of relative permittivity as well as dielectric loss factor than the pure epoxy resin. Samples containing crepe paper also have larger dc conductivities and TSDC currents. These differences are related to the abundant hydroxyl groups in the cellulose paper. The hydroxyl groups are polar groups and easy to absorb water or other impurities which resulting in larger permittivity and dc conductivity. Moreover, the crosslinking degree of the epoxy resin matrix decreases with the introduction of crepe paper. Then, the polarized dipole moments are easier to relax, which is responsible for the decrease of the trap depth corresponding to the process of glass transition. [ABSTRACT FROM AUTHOR]

We report on investigation of the mechanical properties of paper electronics (printed and made out of paper). One key objective of such paper electronics is to achieve ultraflexibility. Therefore, it is important to understand electrical functionality and reliability of paper electronics under various physical (mechanical) deformations. Here, we show the general mechanical properties of the cellulose paper used and its electrical behavior under applied strain, tackling the main effects that need to be identified when building paper-based systems, from product performance and stability perspective. An overview of the stress–strain behavior of silver ink on paper is discussed, and then, we tackle a more specific analysis of the performance variations of paper sensors made with recyclable household materials when exposed to various mechanical conditions of tensile and compressive bending. This paper is important for developing stable wearable sensors for incorporation into Internet of Everything applications. [ABSTRACT FROM PUBLISHER]

Breakdown (BD) and partial discharge (PD) characteristics of insulating paper and transformer board materials are investigated as cost-effective alternatives to high-price materials like polyimide (PI) or polytetrafluoroethylene and fiber reinforced plastic materials typically used in superconducting devices based on high temperature superconductors cooled with liquid nitrogen (LN2). Three different cotton and cellulose based insulating papers are tested in LN2 at atmospheric pressure and compared to synthetic sheet materials and polypropylene laminated paper (PPLP). Additionally, the BD performance and PD characteristics of three different transformer board materials are investigated in LN2 . The results reveal that the paper and board materials have nearly the same or even slightly higher BD voltages in LN2 in comparison to the values in insulating oil. The pure paper materials with thicknesses of 130 μm have a dielectric strength of 70-90 kV/mm, whereas values of 130-140 kV/mm are measured for PPLP and PI with nearly the same thickness. The dielectric strength of the board materials has a maximum value of 76 kV/mm. In the frame of the investigations, the BD performance of the pure paper materials in LN2 is not influenced by the water content of the materials, dried and undried specimens have nearly the same BD voltage. Only the PPLP material has a 15% higher BD voltage in the dried state in comparison to the undried state. [ABSTRACT FROM AUTHOR]

Since the first application of oil-paper composite insulation in power transformers 100 years ago, researchers are now trying to improve the performance of transformer oil by suspending nanoparticles in the dielectric. However, the performance of paper impregnated with nano-modified oil remains unclear. We previously found nano-oil impregnated paper had a good capability to sustain repeated impulses. The amount of space charges accumulated in the nano-oil impregnated paper is much smaller than that in fresh oil impregnated paper. We considered this behavior to be the main reason for the better electrical performance of the nano-oil-impregnated paper. In this work, based on those achieved results, we focus on the modification mechanism of nano-oil impregnated paper. We analyzed the effects of TiO2 nanoparticles on the relative permittivity and their relationship with the charge injection process. We also discuss the influence of TiO2 nanoparticles on charge trap states and the space charge behavior. The dielectric characteristics and trap energy of both nano-oil-impregnated paper and fresh-oil-impregnated paper are determined in this work. [ABSTRACT FROM AUTHOR]

In this work, samples of oil-immersed paper with different moisture levels and aging condition were studied. Frequency domain spectroscopy (FDS) of the samples was examined at 40 °C under different excitation voltages. A non-linear phenomenon in frequency domain dielectric response with different moisture contents and aging condition was observed. The non-linear phenomenon appears to be related to the hindrance effect of cellulose on the movement of ions and the Poole-Frenkel effect on the concentration of ions. With aging, the nonlinear loss peaks at different frequencies caused by the effect of nonlinear conductance and interface polarization appear in the FDS results. The non-linear phenomenon was modeled and verified experimentally. The characteristic parameters and quantitative method to estimate moisture content and the degree of aging degree of oil-immersed paper can be obtained by the proposed method. [ABSTRACT FROM AUTHOR]

Thermal aging of insulation paper has obvious effects on its moisture absorption property. The presented studies aim to investigating the effects of aging on moisture diffusion in oil-immersed insulation paper. Based on the experimental designs and preparation of experimental materials, the transient moisture contents of insulation paper with different aging status were obtained at different conditions. Then, the experimental results were discussed. Furthermore, the diffusion factors and equilibrium time constants were extracted based on the model of moisture diffusion in oil-immersed insulation paper, which are applicable to our studies. Finally, the effects of thermal aging on the diffusion factor and equilibrium time constant were analyzed. The results show that: 1) With the aging of insulation paper, the rate of moisture absorption increases, and the equilibrium moisture content of insulation paper decreases at the same temperature. Besides, the equilibrium time constant decreases with aging at the same temperature. 2) Considering the effects of aging, thickness of insulation paper and temperature, the empirical expression of diffusion factor was obtained and verified. [ABSTRACT FROM AUTHOR]

Acids have attracted an increasing interest from researchers for the standard evaluation of transformer oil, especially in natural ester. This study aims to investigate the types of generated acids in natural ester under hydrolysis, oxidation, and accelerated thermal aging tests with varying paper moistures. The oxidation and hydrolysis degrees were evaluated by acid number and kinematic viscosity, and acids were distinguished from aging condition hydrolysis of oil paper insulation by combining pH values. Meanwhile, the electrical lifetime of oil-paper insulation with seven types of acid were analyzed by step-stress test. The two-parameter Weibull distribution was used to analyze the mean lifetime of specimens statistically. Experimental results reveal that the majority of acids generated from hydrolysis and the main acids are long-chain fatty acids of natural ester impregnated paper insulation. Furthermore, the electrical lifetime models of oil-paper insulation with different types acid were established, and the voltage endurance coefficient with seven types of acids were also obtained. The electrical lifetime test indicated that acids can reduce the electrical lifetime of natural ester impregnated paper insulation and that the effect of low-molecular-weight acids on insulation lifetime is approximately 2–3 times higher than high-molecular-weight acids. [ABSTRACT FROM AUTHOR]

The paper presents the results of investigations on the thermal properties of cellulose and aramid paper impregnated with various liquid insulations. The liquid insulations investigated were mineral oil, synthetic ester, and natural ester. The heat transfer coefficient of the liquid was calculated on the basis of measurements of the thermal expansion, specific heat, density, thermal conductivity and kinematic viscosity of the liquid insulations. Temperatures in the paper and liquid insulations were calculated. The results allow to select the best paper and liquid insulations which provide the most effective cooling in transformers. [ABSTRACT FROM AUTHOR]

The “carbon copy onto dirty paper” (CCDP) channel is the compound “writing on dirty paper” channel in which the channel output is obtained as the sum of the channel input, white Gaussian noise and a Gaussian state sequence randomly selected among a set possible realizations. The transmitter has non-causal knowledge of the set of possible state sequences but does not know which sequence is selected to produce the channel output. We study the capacity of the CCDP channel for two scenarios: 1) the state sequences are independent and identically distributed; and 2) the state sequences are scaled versions of the same sequence. In the first scenario, we show that a combination of superposition coding, time-sharing, and Gel’fand-Pinsker binning is sufficient to approach the capacity to within 3 bits per channel use for any number of possible state realizations. In the second scenario, we derive capacity to within 4 bits per channel use for the case of two possible state sequences. This result is extended to the CCDP channel with any number of possible state sequences under certain conditions on the scaling parameters, which we denote as “strong fading” regime. We conclude by providing some remarks on the capacity of the CCDP channel in which the state sequences have any jointly Gaussian distribution. [ABSTRACT FROM AUTHOR]

This paper presents a method to improve the mechanical properties and breakdown strength of aramid insulation paper. By combining molecular dynamics simulation and experimental analysis, the mechanisms for these improvements were studied. By investigating the relationships between the micro parameters of the models and the nanoparticle content, the optimum nanoparticle content was established to be 1 wt.%. Subsequently, an insulation paper with the same content of nanoparticles as the simulation experiment was prepared in the laboratory and its tensile strength, breaking elongation, power frequency breakdown strength, and other characteristic parameters were tested. The results showed that the properties of the insulation paper modified by nano-SiO2 had greatly improved. Finally, the interface interaction and microscopic mechanism by which the nano-SiO2 improved the properties of the insulation paper were analyzed. On the one hand, a strong interfacial interaction formed between the nanoparticles and the aramid fiber, which allowed them to combine well; on the other hand, the addition of nanoparticles effectively reduced the free volume of the aramid fiber. Therefore, the mechanical properties, thermal stability, and electrical properties of the aramid insulation paper were improved. [ABSTRACT FROM AUTHOR]

Neutron depolarization experiments have shown that the intragranular magnetic domain structure of polycrystalline ferrites exhibits a marked grain size dependence. Below a grain size of around $3~\mu \text{m}$ , the magnetic domain structure changes from the two-domain to the mono-domain state. Ferrites composed of mono-domain grains exhibit low dissipation at megahertz frequencies. This is attributed to the absence of intragranular domain wall movement, i.e., a microscopic origin for dissipation in ferrites has been identified. The implications of this clear observation and evidence for a transition from the mono- to two-domain state in ferrites for micromagnetic theory when a single particle becomes monodomain, as well as for the initial permeability mechanisms in polycrystalline ferrites, are discussed. [ABSTRACT FROM AUTHOR]

Aviation is often seen as an innovative sector eager to seek technological solutions. It is often assumed that aircraft cockpits have panels with electronic displays and many buttons, some labeled "auto." While this might be the case for commercial aviation (Figure 1), the vast majority of noncommercial civil aircraft cockpits look nothing like these modern cockpits. Non-commercial civil aircraft, known as general aviation (GA), typically have cockpits that mainly consist of analog instruments that show the heading of the aircraft, the altitude, and the air speed (Figure 2). While flying, the pilots make calculations using a compass and an aviation calculator. Due to the slow entry rate of new, glass-cockpit aircraft [1], the composition of the GA aircraft fleet is not going to change any time soon. [ABSTRACT FROM AUTHOR]

The article concerns the presence of water in insulating systems consisting of cellulose materials impregnated with different electro-insulting liquids. This is a particularly important issue regarding power transformers with their strategic importance for an electrical power system. Water is a serious threat and can be the reason of a dangerous breakdown. Thus there is a need to have insulating system diagnostics in terms of water content. The article discusses the issue of water solubility in different electro-insulating liquids. The author determined the water saturation limits for these liquids. Moreover, the author determined water sorption isotherms for cellulose materials of different aging degree. On the basis of the obtained results, equilibrium curves were constructed for some selected kinds of insulation. The research results presented here allow to improve the reliability of determining moisture in cellulose insulation of various polymerization degree on the basis of water content measurement in an electro-insulating liquid. [ABSTRACT FROM PUBLISHER]

Promoting a wider range of contribution types can facilitate healthy growth of the visualization community, while increasing the intellectual diversity of visualization research papers. In this paper, we discuss the importance of contribution types and summarize contribution types that can be meaningful in visualization research. We also propose several concrete next steps we can and should take to ensure a successful launch of the contribution types. [ABSTRACT FROM AUTHOR]

In this work, thermal aging aspects of mineral oil, ester oils (synthetic and natural), mixed oil have been reported. All the samples were thermally stressed at 110°C, 140°C, 160°C, and 185°C for 2 weeks each. Concentration of dissolved decay contents in oil, flash point of insulation oil, and linear thermal expansion coefficients of solid insulation with aging have been studied using ultraviolet visible spectroscopy, flash point and dilatometry analysis respectively. Change in functional groups of the insulation oils with aging have been understood by Fourier Transform Infrared Spectroscopy analysis. Additionally, diffusion of oil-moisture mixture into paper with aging and corresponding effect on dielectric strength of paper has been also examined. Further, design and monitoring aspects of ester and mixed oil filled transformers have been also emphasized. It is observed that ester dielectric fluids and ester content as an additive in mineral oil improves the performance of solid insulation. Importantly, blended oil offer an advantage of retarding the degradation of oil as well as solid insulation accompanied by reduced cost of oil when compared to pure synthetic esters. [ABSTRACT FROM AUTHOR]

Breakdown in dielectrics, the mechanism of which is still not yet fully revealed, exhibits very complicated test phenomena and characteristics. The breakdown voltage of a dielectric is believed to be related not only to the dielectric properties but also to the waveform of the applied voltage. For most dielectrics, the impulse breakdown voltage decreases with increasing wavefront time. However, we found for oil-impregnated paper (OIP) used in power transformers, increasing wavefront time in lightning impulses (at microsecond timescales) may lead to a significant increase in breakdown voltage. In contrast, the variation in the wavetail time produces very little effect on breakdown voltage. Combined with our previous test results on the space charge distributions in OIP, we tried to provide two explanations regarding this interesting phenomenon: First, the wavefront time of the applied impulse voltage affects the movement process of the positive particles in the oil-filled micro cavities in OIP, which is strongly related to the local electric field in the oil filled micro cavities and the breakdown voltage of the OIP. Moreover, the wavefront time is closely related to the trapping and detrapping process of the dielectrics. Therefore the effects of the traps in dielectric on the breakdown characteristics are different when the wavefront time varies. [ABSTRACT FROM AUTHOR]

The paper presents the results of a comparative study on accelerated aging of specially designed experimental transformers and their corresponding laboratory models. The experimental transformers are 300 kVA, with insulation in line with medium size and large mineral oil immersed power transformers, having different initial water contents in the standard Kraft paper insulation of ca. 1 and 4 %. These transformers were subjected to the rated current and voltage conditions, operating in the irregular parallel operation, whereby the temperature of windings were measured with fiber optics sensors and kept at 105 °C for 460 days. Each transformer was equipped with a removable tank which allowed access to the outer surface of the HV windings. Laboratory experiments were simulating experimental transformers and were performed in Erlenmeyer flasks, containing oil, paper materials, copper and iron in the same proportions as in the active part of the experimental transformers. The parameters that were monitored during aging were the following: degree of polymerization of paper, hot-spot temperature of transformers, water content in paper, and water and furans content in the oil. Estimations of water content in solid insulation of experimental transformers using frequency domain spectroscopy and the Perrier-Lukic moisture equilibrium chart were performed. The experimental results show that shortening of the insulation life, defined by the value of degree of polymerization, increased 2.5 times with increasing moisture content in the cellulose from ca. 1 to 4 %. For both experimental transformers and laboratory models, the relationships between the paper degree of polymerization and the furans content for dry and wet insulation was developed and is presented in the paper. [ABSTRACT FROM AUTHOR]

The 2019 International Conference on Modeling and Analysis of Semiconductor Manufacturing (MASM 2019) was part of the 2019 Winter Simulation Conference (WSC) that was held December 8–11 in National Harbor, MD, USA. The MASM conferences provide a forum for the exchange of ideas and industrial innovations between researchers and practitioners from around the world involved in modeling and analysis of complex high-tech manufacturing systems. While the papers from MASM conferences are of high quality and are often cited in journal papers, they are limited in size. As a premier journal for topics covered in the MASM conferences, IEEE Transactions on Semiconductor Manufacturing, agreed to consider extended article submissions based on the 21 papers accepted and presented at the MASM 2019 conference for a Special Section of an upcoming issue of the journal. were sessions on Scheduling and Dispatching, Fab Scheduling, Maintenance and Engineering, Capacity and Production Planning, Qualification and Wafer-to-Order Allocation, Semiconductor Manufacturing Models, and Semiconductor Modeling Representations. Dr. Sabine Herlitschka, Chief Executive Officer and Chief Technology Officer of Infineon Technologies Austria AG, gave an excellent keynote talk titled “A European View on Future Semiconductor Industry Needs for MASM.” An archive of the MASM 2019 papers can be found at https://informs-sim.org/wsc19papers/by_area.html. [ABSTRACT FROM AUTHOR]

Transistor random threshold voltage variations due to process fluctuations seriously affects the stability of Static Random Access Memory (SRAM). In this paper, a SRAM bit transistors threshold voltage $({Vth})$ deviation monitoring scheme and system is proposed. This scheme ingeniously achieves on-chip measurement of all transistors threshold voltages without altering compact SRAM bit array layout. Control signal strategies and Transistor ${Vth}$ Determination Circuit (TVDC) for different types of Devices Under Test (DUTs) have been proposed. The system is implemented using a 65 nm CMOS process with a core area of 0.01875mm2. Through Monte Carlo analysis, the Weighted Average (WA) difference of the proposed scheme and the direct measurement method is not more than 10mV, and the Root Mean Square Error (RMSE) difference is not more than 3mV. This system can also effectively detect the cell position of the transistor threshold voltage mismatch simulated by modifying the substrate voltage. For SRAM arrays of different scales, the method proposed in this paper has area efficiency and flexible reconfigurability. [ABSTRACT FROM AUTHOR]

Condition of insulation materials can be obtained by analyzing partial discharge (PD) characteristics since features of PD are closely related to it. In this paper, electrical deterioration caused by partial discharge of oil-paper insulation under long-term AC voltage is studied. Feature characteristics of PD, such as phase-resolved partial discharge analysis and equivalent time-frequency, were recorded during the test process. Electrical deterioration is divided into four stages: initial, develop, stagnation and erupt stage. Four stages are separated by pulse repetition rate and discharge magnitude of PD. In different deterioration stage, statistical characteristics of PD change significantly. Surface properties of pressboard in different deterioration stage were studied. Test results indicate that the depolarization of cellulose in pressboard is the main reason for development of partial discharge, and discharges occur in different position of pressboard in different deterioration stages. [ABSTRACT FROM AUTHOR]

The interaction between technology and healthcare has a long history. However, recent years have witnessed the rapid growth and adoption of the Internet of Things (IoT) paradigm, the advent of miniature wearable biosensors, and research advances in big data techniques for effective manipulation of large, multiscale, multimodal, distributed, and heterogeneous data sets. These advances have generated new opportunities for personalized precision eHealth and mHealth services. IoT heralds a paradigm shift in the healthcare horizon by providing many advantages, including availability and accessibility, ability to personalize and tailor content, and cost-effective delivery. Although IoT eHealth has vastly expanded the possibilities to fulfill a number of existing healthcare needs, many challenges must still be addressed in order to develop consistent, suitable, safe, flexible, and power-efficient systems that are suitable fit for medical needs. To enable this transformation, it is necessary for a large number of significant technological advancements in the hardware and software communities to come together. This keynote paper addresses all these important aspects of novel IoT technologies for smart healthcare-wearable sensors, body area sensors, advanced pervasive healthcare systems, and big data analytics. It identifies new perspectives and highlights compelling research issues and challenges, such as scalability, interoperability, device-network-human interfaces, and security, with various case studies. In addition, with the help of examples, we show how knowledge from CAD areas, such as large scale analysis and optimization techniques can be applied to the important problems of eHealth. [ABSTRACT FROM AUTHOR]

In this paper, the influence of partial discharges (PD) on the subsequent dielectric properties of oil-impregnated paper (OIP) is investigated. Dielectric frequency response (DFR) of OIP is investigated at varied levels of moisture, thermal aging, temperature, oil conductivity and electrode material, to allow comparison of these influences. It is shown that PD activity inside OIP can significantly change the real and imaginary parts of permittivity of the paper layers, especially in the frequency range below 100 Hz. It is shown that even if the PD activity is concentrated on a few percent of the test sample, the real part of permittivity measured on the entire sample after a few tens of hours of PD activity can increase up to 10 times at very low frequencies (∼ 1 mHz) and the imaginary part of the permittivity can increase up to 100 times at low frequencies (∼ 1 Hz). The change of the real and imaginary parts of permittivity due to PD activity is permanent. It is very similar to the change caused by thermal aging, and somewhat similar to the change caused by moisture and higher oil conductivity. It is also shown that the dissipation factor of OIP in contact with copper and brass increases, even in the absence of PD, but contact with aluminum and stainless steel has no influence on DFR of OIP. The results suggest that the influence of PD can be significant when estimating the moisture content or the level of thermal aging of OIP with DFR method. [ABSTRACT FROM PUBLISHER]