Search

The papers in this special issue were submitted to all the conferences organized by IEEE Technology and Engineering Management Society (TEMS) in a given calendar year. In 2017, IEEE TEMS initiated its flagship conference TEMSCON (held in Silicon Valley), which serves as rebranding from its original International Technology Management Conferences (ITMC). Following that, in 2018, two more conferences were initiated globally, one in Asia known as IEEE TEMS International Symposium on Innovation and Entrepreneurship (ISIE), and one in Europe as IEEE TEMS International Conference on Technology and Entrepreneurship (ICTE). For this special issue, we invited authors attending any of the three aforementioned conferences in 2018 to submit full manuscripts for reviews, and the present special issue with eleven papers is the result of a careful selection following our usual rigid double-blinded peer-review process.

The eight papers in this special section were presented at the IEEE International Solid-State Circuits Conference (ISSCC)that was held in San Francisco, California, from February 16 to February 20, 2020.

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 T ransactions on S emiconductor M anufacturing , 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 .

The papers in this special issue were presented at the 2018 17th International Workshop on Data Mining in Bioinformatics (BIOKDD), held in conjunction with the ACM SIGKDD International Conference on Knowledge Discovery and Data Mining. The Workshop was held on August 20, 2018 in London, UK.

Frequency Domain Spectroscopy (FDS) is proposed as a suitable diagnostic method in this paper for implementation on energized oil-paper insulation systems. In present FDS tests, the measurement method is only designed for offline applications. To overcome the deficiencies with the offline testing, this work investigates the feasibility of performing FDS measurements on energized transformers with the view to developing an online diagnostic tool using neutral connections as injection and measurement paths. In the proposed technique, a low-pass filter system is designed to remove the high frequency noise as well as the power frequency signals present in the measured neutral currents. The technique has been successfully applied in a laboratory environment on transformers with oil-paper insulation systems with different operational ages and is feasible for single-phase as well as 3-phase transformers with the accessible neutral points. Compared with the conventional FDS results, a nonlinear dielectric phenomenon is observed from the energized insulation systems as higher dissipation factor Tanδ values primarily due to the increased losses under power frequency voltage excitation. The degree of the nonlinearity is found to correlate well with the degradation status of insulation systems under test.

The six papers in this special section were presented at the IEEE International Solid-State Circuits Conference (ISSCC 2019) that was held in San Francisco, California, from February 17 to February 21, 2019.

The three papers in this special section were presented at the 2019 CVPR conference that was held in Long Beach CA, in June of 2019.

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.

Aging of transformer paper insulation is commonly investigated through indirect measurements conducted in the oil, e.g. furanic compounds. In addition to the conventional indicators, recent investigations showed that alcohols like methanol and ethanol in oil could be used as paper aging indicators. This paper focuses on the applicability of these new paper aging indicators in a novel, gas-to-liquid (GTL) technology based transformer oil through an accelerated laboratory aging experiment. The experiment was conducted at 120 °C for up to 280 days. A conventional mineral oil was also tested as a reference. Kraft paper aged in both oil types showed similar reductions in degree of polymerization (DP) and tensile strength (TS). Amount of methanol in oil is higher than that of 2-FAL in oil when DP is over 375, confirming the promise of using methanol as an early paper aging indicator. Both the new paper aging indicator, methanol and the conventional paper aging indicator, 2-FAL are applicable for the GTL oil without any modifications. In addition, oil only aging experiments showed that oil does produce methanol but it is negligible compared with oil paper aging experiment; however the amount of ethanol measured in the present oil paper aging experiment is believed to be originated from oil oxidation rather than from paper aging.

This paper studies automated tuning of cross-directional model predictive control for industrial paper-making processes under user-specified model parameter uncertainties. Automated parameter tuning algorithms are developed to reduce the variability of the actuator and measurement profiles in the spatial domain and to achieve satisfactory performance in terms of worst case settling times and worst case control signal overshoots in the temporal domain for given parametric uncertainties. Due to decoupling properties of the spatial and temporal frequency components, the controller design and parameter tuning can be realized separately. For the spatial design and parameter tuning in the presence of parametric uncertainties, the undesirable high-frequency components in the actuator profile are suppressed via an appropriate design of the weighting matrix $S_{b}$ using the real-valued Fourier matrix approach. For the temporal design, a temporal filter is adopted to smooth the reference trajectory, where the parameter in the temporal filter is carefully tuned to achieve a tradeoff between the worst case settling time and the worst case control signal overshoot. Finally, the effectiveness of the proposed tuning algorithms is verified using a system model extracted from the pulp and paper industry.

This paper describes a flow control of the dye in the paper mill with the quasi-Z-source indirect matrix converter (QZSIMC) fed induction motor drive. More than a decade the voltage-source inverter (VSI) and current-source inverter (CSI) have been used to control the speed of the induction motor, which in turns controls the flow of dye. Recently, the matrix converter (MC) has been an excellent competitor for the VSI or CSI for its compactness. The voltage transfer ratio of the VSI, CSI, and MC has been limited to 0.866. Thus, the efficiency of these converters is less. To improve the voltage transfer ratio the quasi-Z-source network (QZSN) is to be used between voltage source and indirect MC (IMC). The modification in the shoot-through duty ratio of the QZSN varies the voltage transfer ratio greater than 0.866. Different voltage transfer ratios are needed for different voltage sag conditions. For a variation of the duty ratio of the QZSN, the fuzzy logic controller has been presented. To control the IMC vector control with space vector modulation has been presented. This paper proposes the implementation of QZSIMC adjustable speed drive for the flow control of dye in paper mill during different voltage sag conditions. A 4-kW prototype has been built and the effectiveness of the proposed system is verified with simulation results and experimental setup. Simulation is done in MATLAB, Simulink platform. Experimental setup is done with the aid of a TMS320F2812 (Texas Instrument) processor. The experimental results validate the maintenance of the speed of an induction motor at the set condition, thus controlling the perfect flow of dye in paper manufacturing technology.

Millimeter-wave imaging may be used to assist in\ud the problem of wastepaper recognition during the sorting and\ud recycling process. Currently, there are a variety of techniques,\ud which are used within materials recovery facilities to sort waste\ud paper and card; however, improvements in sorting capability can\ud be realized using a multiple sensors to provide complementary\ud (orthogonal) data. This paper discusses the issues related to\ud the processes, which are currently used for sorting of recycled\ud wastepaper and the phenomenology for millimeter-wave imaging\ud of a wastepaper material. Experimental measurements and\ud images in the millimeter wave band are presented, which support\ud the proposed application.

Thermal and electrical degradation properties in low-viscosity (20 mm2/s, (20 cSt) at 25 °C) silicone liquid and insulation paper were investigated to improve reliability and to enable preventive maintenance technology in transformers. Heat-accelerated degradation in samples of 20 cSt silicone liquid and insulation paper in sealed glass tubes with copper, silicon steel, and pressboard was examined to replicate the environment of the transformer tank. After the examinations, the tensile strength of the paper was measured, and the quantity of decomposition compounds was also measured. It was concluded that diagnosing faults by analyzing decomposition compounds with silicone liquid should be possible in the same way that it is with conventional mineral oil.

The papers in this special section were presented at the IEEE International Solid-State Circuits Conference (ISSCC 2018) that took place in San Francisco, California, from February 11 to February 15, 2018.

In 2015, the Board of Governors of IEEE Intelligent Transportation Systems Society had approved the proposal to name the Best Paper Award in IEEE Transactions on Intelligent Transportation Systems as the George N. Saridis Best Transactions Paper Award. After nearly five years of preparation and planning, and almost one year of hard and concentrated effort by the Award Committee, we are pleased to announce the 2014–2017 George N. Saridis Best Transactions Paper Award for papers published in the IEEE Transactions on Intelligent Transportation Systems.

We are pleased to announce that the June 2022 issue of the IEEE Transactions on Dielectrics and Electrical Insulation (TDEI) will be a special issue on electrets and related phenomena. This issue is open to all authors. Presenters of papers at the IEEE 18th International Symposium on Electrets (ISE18) to be held during September 24–28, 2021 in Shanghai (China) are especially encouraged to submit their work to this special issue. For more information on ISE18 please go to https://ise18.tongji.edu.cn/.

Superchannel transmission is a candidate to realize Tb/s-class high-speed optical communications. In order to achieve higher spectrum efficiency, the channel spacing shall be as narrow as possible. However, densely allocated channels can cause non-negligible inter-channel interference (ICI) especially when the channel spacing is close to or below the Nyquist bandwidth. In this paper, we consider joint decoding to cancel the ICI in dense superchannel transmission. To further improve the spectrum efficiency, we propose the use of Han–Kobayashi superposition coding. In addition, for the case when neighboring subchannel transmitters can share data, we introduce dirty-paper coding for pre-cancelation of the ICI. We analytically evaluate the potential gains of these methods when ICI is present for sub-Nyquist channel spacing.

This paper presents the design of a wideband Hilbert fractal antenna for the purpose of detecting and classifying different common partial discharge (PD) types in an oil-paper insulated system. Three common types of PDs are considered for the multi-class classification problem, namely, PD from a sharp point to ground plane, surface discharge, and PD from a void in the insulation. The different PD types showed variation in the detected frequency contents. The collected samples were processed using pattern recognition techniques to identify their corresponding PD types. A recognition rate of 95% was achieved when K-nearest neighbors was used as the classifier.

The minimum variance controller has been extensively used as a benchmark in the performance assessment of both univariate and multivariate control loops when time delay is the fundamental performance limitation. In this paper, the spatial and temporal performance limitations in the cross-directional (CD) control of paper machines are analyzed. The idea of minimum variance benchmarking is extended to the CD process based on these performance limitations. Based on an industrial CD controller, a user-specified benchmark, which is more practical and less aggressive, is also proposed. In addition, several related performance indices are proposed for the CD process based on both the minimum variance benchmark and the user-specified benchmark. Illustrative examples from a paper machine simulator and industrial data sets are provided to show the effectiveness of the proposed performance indices.

Gassing problems and premature insulation failures in wind turbine transformers indicate reliability concerns about the insulation of such components. This fact necessitates investigating degradation of transformer insulation systems under high-dV/dt pulse voltages that exist in today's wind energy plants. For this purpose, PD activity, generally assumed to be the main long-term cause of insulation deterioration, needs to be analyzed. This work evaluates the effects of impulse voltage parameters such as rate of rise and repetition frequency on inception voltage and intensity of PD activities. PD parameter measurement under high-dV/dt voltages is challenging due to interferences from fast oscillations, and difficulties of PD energy measurements. To avoid such issues, which are related to electromagnetic detection methods under pulse energization, this work uses a chemical approach to compare PD activities, based on the rate of hydrogen generation in a controlled test chamber with oil/paper samples. Gas monitoring of the oil containing impregnated paper samples reveals that a faster rate of rise increases PD energy as well as inception voltage. Results based on experiments conducted in small oil chambers show good correlation between the amount of hydrogen detected and PD energy level; hence it can be used as a benchmark for comparing PD energy levels under various impulse waveforms.

This paper presents a radio frequency plasma equipment designed to be used for the conservation procedures, such as decontamination, cleaning, and consolidation of cellulose-based materials. Decontamination and cleaning are carried out by the low-temperature nitrogen plasma generated between two electrodes, connected to a 1.5-MHz generator. The paper consolidation is performed by coating with compatible polymers in view of long term protection. Surface analyses (color analysis and electron microscopy) were undertaken to assess the uniform display of the polymer on the paper surface. The microbiological tests made on representative samples collected from historical books attested the complete inhibition of bacteria and fungi after, at most, 7-min treatment duration, depending on the initial infestation degree.

Sensors and instrumentation play an important role to improve the lifestyle of people and their surroundings. The IEEE IMS Faculty Course Development Award supports and encourages faculty members to develop a new course or significantly revise existing accredited engineering/physics/science curricula with specific focus on instrumentation and/or measurement. The Faculty Course Development Award 2013 provided funding that helped to develop this paper named "Advanced Sensors and Instrumentation" with a special emphasis on measurement of remote environmental parameters at Massey University, New Zealand. (In New Zealand, we call classes a paper, not a course. For example, in the Bachelor degree program, each year we have eight papers and the students need to do thirty-two papers for the degree. The "course" means the complete program.) The objectives are to provide an overview of the importance of environmental monitoring; to have students develop necessary skills to select appropriate sensors and develop the associated signal conditioning to monitor important environmental parameters; to train the students/engineers on the best methods to transmit, store, analyze, and interpret the data from the sensors; and to provide a hands-on experience in electronic system design concepts, particularly for environmental monitoring. Engineering students will gain knowledge to take up the challenges to design, fabricate and implement sensing systems and necessary instrumentation circuits for monitoring the environment. The content of the paper has been presented at other universities, and the materials are available for any faculty to use in their own teaching. The content of the paper can be collected from Prof. Subhas C. Mukhopadhyay (S.C.Mukhopadhyay@massey.ac.nz).

Voltage-time (v-t) characteristic plays an important role during the insulation coordination of a power system. Power transformer is the crucial equipment in the design of a reliable power system. During the operation of a transformer, Oil Impregnated Paper (OIP), the widely used winding insulation of transformer, undergoes significant irreversible aging. Aging alters the dielectric properties of the OIP reducing it's withstand capability. Hence in this work, the impulse v-t characteristic of fresh OIP and 8 years service aged OIP of the same manufacturer are compared. Moreover, when the transformers are directly connected to Gas Insulated Substations (GIS) and during the switching operation of vacuum circuit breakers, OIP is stressed by Very Fast Transient Overvoltage (VFTO). In addition, transformers are subjected to repeated impulses generated during multiple lightning strokes, switching operations of circuit breakers and HVDC converters. Various studies have pointed out the adverse effect of VFTO and repeated impulses on transformer insulation. Therefore, the effects of VFTO and repeated impulses (both LI and VFTO) on the v-t characteristics of fresh and service aged OIP are quantitatively assessed and discussed with reference to the Basic Impulse Insulation Level (BIL) and protection level of the transformer insulation.

Many papers have been written about the phenomenon of arc flash, the causes of arc flash, how to mitigate specific arc flash problems, and how to design arc flash issues out from the beginning. This paper will discuss the overall process of completing an engineering incident energy analysis and remediation project in a pulp and paper mill. Most mills are not fortunate enough to receive sufficient funding to do the whole study and a remediation process all at once. This paper explores how a Midwestern pulp and paper mill worked over several years to get through the process of the study, remediation efforts, and the establishment of an overall electrical safety program.

The eleven papers in this special section were presented at the 2019 IEEE Biomedical Circuits and Systems Conference (BioCAS) in Nara, Japan, from October 17–19, 2019. Similar to previous years, BioCAS 2019 was jointly sponsored by the IEEE Circuits and Systems (CAS) Society and the IEEE Engineering in Medicine and Biology (EMB) Society.

A course on the emerging topic “Smart Sensors and Internet of Things (IoT)” has been designed, developed, and delivered from 21st March 2016 to 31st March 2016 in the Department of Electrical Engineering, Jamia Millia Islamia (Central University), New Delhi-110025, India. This course was organized under a program initiated by the Government of India, entitled “Global Initiative of Academic Networks” for higher education. The basic objective is to bring the internationally and nationally acclaimed scientists on a single platform to motivate young minds of India so that India’s scientific and technological capacity reach global excellence. The course was designed to develop the technical skills for the students, the researchers, the engineers, and the faculties, who desire to address some of the issues faced by the people around the world in the fields of smart sensors and IoTs with applications in smart homes, smart cities, smart grids, smart environment, smart transport, and so on. The assessment of the course by the participants shows extreme usefulness of it.

It is a general belief that mineral oil filled power transformers are designed to operate reliably for up to 40 years. However, there are many transformers installed worldwide operating well beyond such age. Therefore, transformer end-of-life should not be simply indicated by the designed 40 years, but determined by the insulation system end-of-life.

Since 2017, the IEEE Transactions on Electron Devices (TED) has published a selection of extended versions of papers presented at the Symposia on VLSI Technology and Circuits held in the corresponding years (vol. 64, no. 10; vol. 65, no. 11; vol. 66, no. 12). Since 2018, the papers have been collected in a Special Section of TED titled “Papers from Symposium on VLSI Technology.” This initiative, which was the result of a fruitful cooperation between the Electron Device Society and the VLSI Symposium chairs and committees, has brought to TED a number of carefully selected (by the VLSI TPC first and then through the TED usual review process), high-quality submissions. We have been able to continue this cooperation also in this difficult 2020, and we are therefore happy to announce the publication in the December issue (Vol. 67, No. 12) of a Special Section on papers from the 2020 Symposium, held virtually on June 15–19, 2020. A special thanks to the Guest Editors of the section, Peide Ye, Purdue University (Publication Chair, 2020 VLSI Symposium), and Masaharu Kobayashi, The University of Tokyo, Japan (Publication Co-Chair, 2020 VLSI Symposium).

IEEE Transactions on Nuclear Science is pleased to announce that Dr. Sang-Ho Kim has been appointed as an Associate Editor for Accelerator Technology papers.

The winner of the 2020 TPS Best Paper Award has been selected (please refer to our TPS home page for details about the award at https://ieee-npss.org/publications/transactions-on-plasma-science/ ). This year is the second year that the award is being given, and I am pleased to announce that Prof. Chandrashekhar Joshi, Department of Electrical and Computer Engineering, University of California at Los Angeles, Los Angeles, CA, USA, is the winner for his article “Laser-driven plasma accelerators operating in the self- guided, blowout regime.” This article appeared in IEEE TPS, vol. 45, pp. 3134–3146, in December 2017. The award plaque, certificate, and cheque will be presented to Prof. Joshi at an upcoming International Conference on Plasma Science in South Lake Tahoe, CA, USA, in June 2021. This is an open-access article and is freely available to our readers. Congratulations to Prof. Chan Joshi on this accomplishment.

As striking lightning impulse waveforms in power transformers are quite different from the standard lightning impulse waveform (SLIW) used in the withstand voltage tests, it is essential to identify the breakdown characteristics of oil-impregnated paper (OIP) under non-SLIW and to quantitatively compare them with those under SLIW. On that basis, the impulse insulation levels of power transformers can be rationally determined and then the insulation specifications can be evaluated to maintain high equipment reliability. In this paper, with damped alternating oscillation waveform as a representative basis, the breakdown characteristics of oil-impregnated paper were experimentally obtained by changing the frequency and damping rate of the applied voltage. All experiments were conducted using a column-column electrode model. In addition to the 50% breakdown voltages (U50), Minimum breakdown voltage Umin and V-t characteristics under different circumstances, the influence of various parameters on breakdown characteristics and the possible reasons were discussed. After comparing waveforms and corresponding results, the specific relationship between waveform parameters and U50 were expressed as a single equation. As a result, the breakdown voltage was 1.106 to 1.435 times higher than that under SLIW depending on frequency and damping rate. The steepness of the wave peak and the duration of high voltage around wave crests are considered to be two important factors affecting the breakdown voltage. An effective way was proposed to predict U50 of oil-impregnated paper as a reference for insulation specifications irrespective of wave shape. These results support the rationalization of insulation for actual lightning impulse waveforms in the power transformers.

This paper presents a novel technique to determine the optimized slope of triangular excitation in frequency domain spectroscopy that can provide better information about condition of oil-paper insulation. In conventional frequency domain spectroscopy, estimation of frictional losses due to the interactions of oscillating dipoles helps in investigating insulation condition. But, different types of dipoles in insulation cannot have similar dielectric relaxation times. Therefore, excitation having multiple frequencies is necessary for the dipoles to undergo more synchronized oscillations. This synchronized oscillation of dipoles reduces the inter-dipolar interactions and provides better information regarding insulation condition. Hence, in this work, triangular excitation is used for frequency domain spectroscopy since its harmonic contents can be varied by changing the slope. The slope of the triangular excitation is optimized to obtain more accurate information about the insulation condition. The optimized triangular excitation for insulation is determined using the proposed equivalent circuit model. To experimentally determine the effectiveness of the model, three test samples having preset moisture content in paper have been prepared in the laboratory. The optimized triangular excitations are then applied to the test samples to estimate their insulation condition. Experimental results show that the use of optimized triangular excitation provides information regarding the condition of oil-paper insulation with greater accuracy. In order to investigate the applicability of the proposed equivalent circuit model, the experiment has also been performed on real-life transformers.

This paper presents an experimental work investigating the failure data of oil-impregnated paper under pulsating DC voltage. The failure data of the oil-impregnated paper specimens were obtained through constant voltage stress tests; the Weibull distribution was used to estimate the statistical distribution of failure data. The exponential function (EF) and the inverse power function (IPF) were used to modify the Weibull distribution of failure data, so as to obtain two dual-variable Weibull failure distributions (WFDs), which were used to analyze failure data of oil-paper specimens obtained under pulsating DC and individual DC and AC voltages. Their adequacies were evaluated by using failure data obtained through the constant stress tests under various voltages. Both EF-modified and IPF-modified WFDs show more adequacy for failure data of oil-paper insulation under DC and pulsating DC voltages than AC voltages. The EF-modified WFD was more adequate than IPF-modified WFD in estimating the statistical distribution of failure data.

Air-gap discharge in oil-paper insulation is one of the main types of partial discharge (PD) in power transformer. The discharge development stage for monitoring and diagnosis of transformer potential faults is a significant area of study. The method of wavelet packet energy entropy, which is based on different frequency bands energy distribution of PD signals at different insulation states, is provided to explore the variation characteristics of the whole PD process. In this paper, air-gap discharge model is built in the simulative transformer tank that collects PD signals based on constant voltage method. This model also utilizes wavelet packet decomposition method to partition PD signal bands obtaining signal energy distribution in each frequency band, as well as total signal energy tendency along with PD development process. Wavelet packet energy entropy, which is the new PD feature parameter describing the development process, represents the order degree of PD signals which corresponds to dielectric strength. Finally, because of the cyclic change of this method, the step points of wavelet packet entropy are taken as the way to effectively divide the PD development stage.

This paper describes mounting of standard surface mount component packages on a paper substrate using an industrial solder process with a low-temperature solder. The use of paper as a substrate for printed flexible electronics is becoming more and more widespread as an alternative to the more commonly used plastic substrates, such as polyethylene and polyimide. Paper has the benefits of being environmentally friendly, recyclable, and renewable, as well as inexpensive. It is shown that it is possible to mount standard surface mount device components on paper substrates using low-temperature solder in an industrial soldering process. The contact resistances obtained are mostly low, although the yield of functioning contacts is low. The reason is cracking of the substrate coating layer that goes through the printed silver tracks. It was observed that the cracks appear mostly close to the contact pads, the most likely cause is thermal mismatch between the coating layer and solder and also thermal expansion of the photo paper resin coating. The smallest component package size, 0201, resulted in the highest yield of >80% with decreasing yield for larger package sizes.

The service life of a transformer is determined by the condition of its oil–paper insulation. A modified Cole–Cole model was introduced to describe the frequency domain spectroscopy (FDS) curves based on the classic Debye relaxation model and thereby accurately determined the ageing state of the insulation of a power transformer using FDS. Oil–paper insulation samples with different ageing states are prepared under laboratory conditions, and a characteristic parameter is extracted to quantify their ageing states after a detailed investigation of the frequency domain dielectric properties of the samples. Results reveal that the modified Cole–Cole model, including the α relaxation components, dc and hopping conductivity components, can be employed to effectively model the frequency dielectric characteristics of oil–paper insulation. Furthermore, the extracted characteristic parameter from this model, τα, can be utilized in the quantitative evaluation of the ageing states of transformer insulation. A case example is discussed to demonstrate the applicability of the proposed technique in the condition assessment of field power transformers.

The paper presents new diagnostic method applied to assess aging degree for paper-oil insulation used in professional electrical power device, primarily including medium and high power transformers. The described method is based on modified diagnostics using the recovery voltage effect occurring in dielectrics (RVM – Recovery Voltage Methods). Modification of the RVM method applied so far, which is now used only to assess moistening degree for paper-oil insulation in power transformers, consists in a new parametric analysis of recovery voltage time characteristics. Simulation and experimental tests carried out in laboratory conditions for adequately prepared insulation samples have proven that the time-constant of recovery voltage decay (τR_MIN) is the most susceptible parameter as regards quantitative change in the function of aging of the examined insulation. This conclusion is also confirmed by statistical studies, in which a multi-parameter variance analysis method has been applied. An original equivalent circuit diagram of the insulation has been used to simulate aging degree of paper-oil insulation samples in numerical tests. The diagram is based on the Cole-Cole type dielectric response model.

IEEE Transactions on Nuclear Science (TNS) is pleased to announce that Prof. Gian-Franco Dalla Betta (S’94–M’98–SM’06) was appointed as Senior Editor receiving papers on Radiation Instrumentation in June 2020. He replaced Prof. Arnold Burger who had served in this position since early 2016. Prof. Burger handled over 1600 original papers and revisions during his tenure, and we are grateful for his service.

With this Special Issue, we are publishing 81 peer-reviewed manuscripts, a selection from the best work presented in June 2019 at the 28th IEEE Symposium on Fusion Engineering (SOFE), Jacksonville, FL, USA. This is the sixth SOFE Special Issue that IEEE TRANSACTIONS ON PLASMA SCIENCE (TPS) has published, a tradition that started with the 2009 SOFE in order to afford attendees the opportunity to publish an expanded version of their oral or poster presentations in a refereed journal. It has become a popular option. With each successive SOFE, more authors take advantage of the possibility offered by TPS to have their conference papers gain wider exposure and be cited by others working in fusion engineering and its related disciplines. Readers benefit as well. For example, this issue features a total of 22 papers on ITER and Wendelstein 7-X, a unique collection of papers on two projects that sit at the forefront of fusion engineering.

To investigate the characteristics of micro bridges and their interactions with partial discharge (PD) in oil-paper insulation under DC voltage, an experimental platform with two-copper-electrode models is established. Generation and growth of micro bridge impurities are observed. PDs in experimental process are detected and analyzed. The result shows that the generation and growth of micro bridges have three stages based on their quantity and shape. At first stage PD accelerates the generation of micro bridges. At second stage the grown bridges trigger stronger discharges. At the last stage a so-called "hazardous bridge" that triggers highly intensive PDs emerges, through which breakdown happens. Therefore, bridges and PDs promote each other to cause insulation failure. In addition, impurities at the second stage are observed to transform into pile-like, bridge-like or particle-like shapes. The transformation process is considered to relate with the change of composition force on fiber bundles. Besides, a "cluster discharging" phenomenon is observed at the second stage, which is associated with the generation and disappearance of micro bridge impurities.

At IEEE I2MTC 2019 in Auckland this past May, we had the sophomore edition of the TIM@I2MTC program, which started at IEEE I2MTC 2018 in Houston. Under this program, authors of all published or e-published papers during a given calendar year in the IEEE Transactions on Instrumentation and Measurement (TIM) have the option to present their TIM paper at the next year's I2MTC in a specially designated poster session. For example, at IEEE I2MTC 2019 in Auckland, TIM papers published or e-published in 2018 were eligible for presentation. Authors who would like to take advantage of this opportunity will simply have to register their paper by the given deadline. There is no review process—the paper will be automatically accepted for presentation, and its title, abstract, and authors list will appear in the conference program—though the paper itself will not appear in the conference proceedings since it is already published on IEEE Xplore as a TIM paper.

The IEEE Transactions on Nuclear Science Best Paper Award is an annual award to recognize the best paper published in the Transactions in a given year. The Award is sponsored by the IEEE Nuclear and Plasma Sciences Society and the winning paper is selected according to its quantifiable usefulness to the community. The authors of papers published in the Transactions in the third year prior to the year of the award are eligible for consideration. The 2019 award is, therefore, awarded to the paper published in calendar year 2016 judged to be the most useful to our community based on metrics calculated for the years 2016, 2017, and 2018.

This conference presents the recipients of the Outstanding Conference Paper Award from the 2015 IEEE Nuclear and Space Radiation Effects Conference.

Repeated impulses have long been considered to affect the insulation properties of electrical equipment. This interesting but rarely studied phenomenon may pose great risks to the reliable operation of power equipment. Therefore, in this work, we focus on the accumulative effect of repeated lightning impulses on the oil-impregnated paper (OIP) used in power transformers. Specifically, we study the effect of space charge on the accumulative characteristics of OIP. A repetitive impulse accumulating test platform was set up, and the tests were conducted to obtain the accumulative characteristics of OIP under repeated lightning impulses. The accumulative characteristics of OIP with various interval time were experimentally identified to study the influence of interval time on the accumulative effect. Then, space charge in OIP samples were investigated using the pulsed electro-acoustic technique. Charge behavior in OIP was analyzed under different conditions, i.e., changing the applied times, amplitude and interval time of the applied lightning impulses. Charge injection and transport occurred during lightning impulse accumulation. The increased application of lightning impulses, high applied voltage, and short interval time contributed to the accumulation and transport of space charges. At last, the possible mechanisms of the accumulative effect are discussed in this article based on the experimental results.

The non-standard lightning impulse waveforms (N-SLIWs) including oscillating lightning impulses, very fast transient voltages (VFTOs) and steep waveforms in the power system gravely endanger the inner insulation of power transformer. To prevent insulation failure and provide guidance for robust transformer design, in this paper, two typical insulation models of oil-immersed transformer were established and their breakdown characteristics under N-SLIWs were investigated. The research mainly focused on the influence of front time and oscillation frequency of N-SLIWs on the breakdown characteristics. The experimental results showed that the breakdown voltage increased with the decrease of front time. For low frequency-oscillating lightning impulse waveforms (LF-OLIWs), breakdown voltage increased with the increase of oscillation frequency and was up to 30% higher than that under standard lightning impulse waveform (SLIW). For VFTOs, with the increase of frequency, breakdown voltages presented a law of inverted "U" type. Insulation model could withstand the highest value of VFTO when the oscillation frequency was around 2.4 MHz. But when the frequency was as high as 9 MHz, breakdown voltage was close to that under SLIW. A very high frequency oscillation was the main reason for the reduction of breakdown voltage as its steepness dV/dt assisted the effective transmission of the sphere’s potential to the head of the streamer channel.

Arguably, usability testing is most effective when integrated into the user-centered design process. One way to encourage this integration is to reemphasize the value of paper prototyping. In a recent test of a university library website, we married low-fidelity paper prototyping with medium-fidelity wireframe prototyping. When user navigation led to nonexisting pages or dead ends, users were encouraged to create what they thought should be where there was nothing. This blank-page technique gave us insights into users' mental models regarding site content and design, providing developers with useful data concerning how users conceptualized information they encountered.

The combined IEEE International Conference on Plasma Science (ICOPS) (held annually) and Pulsed Power Conference (held biennially) are merged once every six years, sponsored by the Plasma Science and Applications Committee (PSAC) and the Pulsed Power Science and Technology Committee (PPS&T) of the IEEE Nuclear and Plasma Science Society (NPSS). The joint conference, called the Pulsed Power and Plasma Science Conference, was held on June 23–28, 2019, in Orlando, FL, USA. The conference’s technical program included a wide range of topics, which ranged from fundamental research to traditional and emerging technology applications. The conference had over 800 accepted abstracts, representing scientists from over 30 countries. The program also included a minicourse on “Computational Methods in Plasma Physics.” This year the PPPS sessions were enhanced by a number of exceptional plenary talks.

Compared to conventional ac cables, the current rating of HVDC cable circuits is more complicated because the permissible current is not only limited by the operating temperature, but also by the electrical stress within the insulation. Therefore the IEC60287 current rating standard is considered insufficient for some HVDC applications because it fails to include the stress limitation. This paper presents an analytical methodology to calculate an electrical stress-limited rating for HVDC cables, which considers the maximum dielectric stress as the current limiting factor. This paper represents the first part of a project which has comprehensively reviewed cable rating calculations for mass impregnated HVDC cable systems.