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The review of materials, design and testing of joints for HVDC extruded cable systems provided in previous Part 1 paved the way to this Part 2 position paper by the DEIS HVDC Cable Systems Technical Committee, whose aim is to remedy the scarcity of existing standardized tests on joints. After a sound analysis, here routine tests are identified as the first practical target for the onset of new testing procedures, AC-PD measurements as the readily-available measurement from manufacturers' experience for quality control of joints during routine tests and VHF/UHF wireless sensors as the best tool for such measurements in the noisy environment of factories. Thereby, a novel protocol for PD measurement using AC voltages and VHF/UHF electromagnetic sensors, for quality control during routine tests on HVDC extruded joints, is proposed. The insulation of HVDC extruded cable system joints. Part 2: Proposal of a new AC voltage PD measurement protocol for quality control during routine tests © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

This position paper by the DEIS HVDC Cable Systems Technical Committee provides a review of existing diagnostic electrical and dielectric techniques for testing the insulation of polymeric extruded HVDC cable joints in the present Part 1. Here, the state of the art on the insulation of HVDC extruded cable system joints is covered with reference to types, design and testing techniques. This helps to identify routine tests as the first target for the onset of new testing procedures, AC-PD measurements as the readily-available measurement from manufacturers' practices for quality control of the insulation of accessories during routine tests and VHF/UHF wireless sensors as the best tool for performing such measurements on joints in the noisy factory environment. Thereby, a novel protocol for the measurement of partial discharges using AC voltages and VHF/UHF sensors, for quality control during routine tests on such joints, is derived in the next Part 2. This protocol is the main novelty of this investigation. © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Scanning acoustic microscopy (SAM) is a useful observational tool in cellular study as non-invasive living observation is feasible, unlike in conventional optical microscopy. In a previous study, cell morphological changes were successfully visualized using acoustic impedance measurements. These acoustic impedance changes correspond to cell elasticity, mainly reflecting changes in the cytoskeleton. In this study, we evaluate the elastic changes in murine breast cancer cell C127I during mitosis. C127I cells were cultured to ∼75% confluency before measurement, using a transducer with a central frequency of 320 MHz. Dynamic changes during mitosis were successfully mapped using SAM and confirmed by laser confocal microscopy. Cells in prometaphase, anaphase, and telophase, which could previously only be confirmed through immunostaining, were successfully visualized using SAM. This suggests that SAM is capable of distinguishing cells in different mitotic phases based on the changes in acoustic impedance.

Electric tree is a phenomenon of local dielectric breakdown with partial discharge (PD). It is also the final stage of insulation deterioration. The electrical treeing has been discussed by using conventional PD parameters such as the generation phase, charge amount and so on. Since the obtained PD waveforms were processed by an analog filter designed according to the frequency characteristics of the measurement instrument such as an oscilloscope, its waveform is a convolution of the original PD waveform and the transfer function of the measurement system. However, the feature values such as a rise time, fall time and frequency spectrum in the original PD waveform should show the behavior of electrons and ions in the discharge space. In this paper, the original PD waveforms generated in micro-silica/epoxy composite with the electrical tree were acquired, and the feature values of the original PD waveform were analyzed. In addition, the behavior of the electric charges in the discharge space was assessed from the change of the feature values.

In immersion cooling superconducting equipment, the refrigerant plays the double role of cooling and electrical insulation, but electric field concentration on the refrigerant causes partial discharge (PD), which can be a weak point in electrical insulation. Although slush nitrogen, which is a mixed refrigerant of liquid nitrogen and solid nitrogen particles, has high cooling performance; however, the effects of the introduction of solid nitrogen particles on the insulation performance has not been clarified. From the analysis of PD waveform characteristics, it was shown that the solid nitrogen particles have a certain barrier effect against discharge, but basically act as a weak point in electrical insulation. On the other hand, the breakdown voltage of slush nitrogen with high solid phase ratio is about 80% of that of liquid nitrogen. It was suggesting that the high cooling performance and sufficient insulation performance may be compatible depending on the insulation design.

The clarification of the discharge phenomenon in micro-gap is strongly required in a wide range of application fields such as surface processing technology, MEMS, actuators, and thin film sensors. An optical measurement using a high-speed camera is suitable for observing the occurrence and development of the discharge. It is possible to find the discharge characteristics such as the shape, propagation velocity and so on. However, in order to discuss the insulation performance, the charge amount of the discharge, in other words, the electric field is important. Although the emission intensity caused by the discharge has a correlation with the electric field, it is difficult to evaluate the field quantitatively by an optical measurement only. In this research, a prototype for a creepage discharge measurement system using a multi-array coaxial probe was developed. The propagation characteristics of the creepage discharge was evaluated in the millimeter gap, and the feasibility of the measurement technique was shown.

Dielectric elastomers have potential for devices such as a pressure sensor or an actuator for an artificial muscle. To understand the electrical properties, the space charges in slide-ring materials (SRMs) are measured using the pulsed electro acoustic (PEA) method under various applied voltage applications. The positive space charge in the bulk is dominated under a dc constant voltage application, and the positive charge amount increases with the voltage application time. However, as the applied voltage increases, the positive charge amount decreases with the voltage application time. A negative charge injection by the hetero space charge effect due to the local field enhancement by the positive charge near the cathode occurs. The positive space charge in the SRM is observed under a voltage of +3 kV in the square wave voltage of +3 kV/0 kV. When the magnitude of the negative voltage in the square wave voltage increases, the space charge is not observed. Hence, negative charge injection may neutralize the positive space charge or the positive space charge may be swept out when a negative voltage is applied.

An electrode system and a buffer amplifier are designed and developed for the nanosecond time measurement of the prebreakdown current of polymers. The system is verified with the time and frequency characteristics by applying a 6-ns pulse voltage. The nanosecond time measurement was demonstrated with a 25-µm-thick polyimide with a linearly rising voltage at the rate of 10, 30, 100, and 500 V/s at room temperature. Pulse currents were obtained before the breakdown at the rising rate of 100 V/s and 500 V/s but not at 10 V/s and 30 V/s. The results may indicate that the electron process may be dominant at the rising rate of 100 V/s and 500 V/s but not at 10 V/s and 30 V/s. Thus, it may be possible to distinguish the primary factor of the breakdown process by performing a measurement using the developed system.

Space charge will inevitably appear in practical applications, like cables that have been applied HVDC, in which space charge is concerned to be existed. As the space charge distribution has a strong link with the degradation of insulation material and it also is a core point for insulation technology upgrade. So, a method to observe space charge in insulation material is needed, to certain if it exists or not. The presentation will deal with the acquisition of the reference signal when the pulsed electroacoustic measurement on space charge in insulating materials is carried out. By superposing pulse voltage on specimens made by XLPE films which is applicated -3kV and -4kV DC voltage, a method as lock-in acquisition to take the reference signal at the same time of the acquisition of the target signal is proposed.

Deconvolution process is often applied to time-resolved dielectric measurements like the pulsed electroacoustic method. As the original signals, both target and reference signals, have acquired after being subjected to high pass filter, low frequency components have been significantly suppressed. It creates strong unnecessary low frequency components if the process has been done in frequency domain, leading to very uncomfortable bias noise in time domain. This presentation will propose an effective solution. It is proposed that combining the low frequency components deconvolved in time domain after being down-sampled and the high frequency components deconvolved in frequency domain gives a quick and precise signal. The process was embedded onto space charge measurement. Although a good signal was obtained even with only time-domain deconvolution, it was proved that the proposed method significantly improves its speed in calculation. As a conclusion dual-domain deconvolution process has been proposed and successfully applied to the space charge measurement without being disturbed by low frequency spurious.

A space charge measurement method which The new device of space charge measurement for full-size cable was proposed, this measurement by means of the Pulsed Electro Acoustic (PEA) method. It basically employs the concept of pulsed electroacoustic method that includes acoustic coupling between the specimen and acoustic detector. In this proposal a polymeric material was applied as the acoustic coupler in order to retain electric insulation between the outer shield of the cable and the acoustic detector that made it possible to apply the pulse voltage onto the measuring point whereas the other part of the cable was grounded. In addition, by applying a periodically changing voltage onto the shield. electrode superposed with the pulse voltage, a precise calibration was made possible simultaneously with every shot of the space charge measurement. Keywords: Power cable, space charge, pulsed electroacoustic method.

Herein, we propose a method to estimate the reflection coefficient of the ultrasonic wave transmitted onto an object and to display this with acoustic impedance distribution. The observation targets were glial cells, which have a rigid cytoskeleton and spread out well on a culture substrate. A reflection coefficient derived only from the cells was then obtained using a deconvolution process. In the conventional method, the deconvolution process that was performed only in the frequency domain would cause an error in the reconstructed signal, and it formed an artifact when the result was converted into the acoustic impedance image. To solve this problem, two types of deconvolution techniques were applied in either the full frequency or time–frequency domain. The results of both methods were then compared. Since the characteristic acoustic impedance is a physical property substantially equivalent to the bulk modulus, it can be considered that the internal elastic parameter is thus estimated. An analysis of the nucleus based on its position in the acoustic impedance image was then performed. The results indicated that the proposed time–frequency domain deconvolution method is able to maintain the structure of the cell, while the cell itself is free from unwanted artifacts. The nucleus was also estimated to be located toward the center of the cell, with lower acoustic impedance value than the cytoskeleton. The results of this study could contribute to establishing a method for monitoring the internal condition of cultured cells in regenerative medicine and drug discovery.

Recently, a method for estimating three-dimensional acoustic impedance profiles in cultured cells and human dermal organs was proposed by interpreting the reflected ultrasonic signal based on a 1-D transmission line model for acoustic impedance microscopy (AIM). However, AIM has a disadvantage that reflected signals from cells overlap with that from a reference substrate. Additionally, the amplitudes of the reflected signals from the specimens are significantly weaker than that from the substrate. In this paper, we proposed a new method for separation of those signals based on a concept of clutter filter, which had been developed for a color Doppler method in medical ultrasonic imaging. The proposed filter using singular value decomposition (SVD) could separate original signals into desired signals such as those from the substrate and cells. Additionally, an effect from a tilt of the substrate was investigated in this study. Separability of the proposed filter was evaluated by two investigations. First one was to evaluate the separability by estimating a correlation coefficient between the filtered signal and signal reflected from a position only with the substrate. Second one was to compare a slope of the substrate estimated from the original signal with that estimated from the filtered signals from the substrate. The experimental results showed that the proposed filter could separate signals from the substrate, and the compensation of the tilt of the substrate could improve the performance of the proposed filter.

This paper presents the effect of coal fly Ash filler (CFA) on the electrical properties of silicon rubber composite. The observed electrical properties are volume resistance, surface resistance, and the surface breakdown voltage. The temperature The effect on the surface breakdown voltage of silicon rubber with CFA filler also was observed. The type of silicon used is RTV 683. The filler concentrations of the matrix are 0,​​10.20,30,40 per-hundred gram of resin (phr). The test results show that the surface resistance increased significantly with the increasing of CFA loading filler. The increasing of volume resistance is nonlinear; the volume resistance tends to decrease when the CFA loading filler exceeds 30 phr. Flashover test results show that flashover inception voltage (FOIV) increases with the increasing of CFA filler concentration and the increasing of temperature.

Ultrasonic technology has already been used for many applications. Most of them are mainly used for object measurement. Some techniques have been widely applied to particular measurement by utilizing a very specific component. In this research, the previous technique to develop a conversion curve to obtain the acoustic impedance of the target is adopted. Then, we propose a 3 MHz concave shaped ultrasonic transducer for measuring liquids and a confirmation is needed to confirm if the system used is correct. Therefore, several saline solutions which property has been known are used. A low voltage of 10 Volt pulse is used to trigger the transducer. The ultrasonic wave is then transmitted through the multilayered mediums, which is pure water, clear acrylic, and the target. The echo from the interface between the acrylic and the target is then received by the same transducer. Some parameters such as peak and RMS are used to develop the conversion curve. A peak detection and comparison between the original echo and the processed one by using Wavelet transform (UWT and DWT) is then performed. Some analysis of the echo signal by using multiresolution and time-frequency analysis is also proposed. The result obtained from the measurement is then compared to that from the theoretical calculation. Based on the result, in terms of developing the calibration graph, only the RMS value (UWT) which has the closest trend to the result of the calculation, with the mean percentage error of 0.65512%, which is the smallest value among all parameters.