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In this work, a dual-mode (DM) radio frequency (RF) mixer is studied and validated over the $K$ -band to meet the ultralow-power requirement of direct-conversion receiver architectures. The proposed RF mixer combines two operation modes, namely, RF energy harvesting mode and RF mixing mode, which are implemented within a single passive multiport interferometric circuit. This approach aims at harvesting part of the RF energy for powering specific low-power active devices toward the energy autonomy of RF receiver systems. For this proof-of-concept study, a circuit is prototyped and tested. The experimental results show promising performance. Inter-port isolation better than 20 dB is achieved over a frequency range of 22–26 GHz, together with good RF-to-dc conversion efficiency (up to 45% with RF input power of 40 mW), and appreciable RF mixer conversion loss over a wideband (average 12.8 dB). [ABSTRACT FROM AUTHOR]

We propose and investigate an easy technique to mitigate the mutual coupling of integrated antenna elements caused by surface waves in a high-permittivity grounded dielectric substrate, which can be deployed for high-density integration of antenna and front end on a substrate. Two approaches are examined to realize the proposed concept: 1) the removal of the ground plane between two collinear antennas and a series of uniform corrugations are introduced at the edges of the remaining parts to create a transition region between grounded and ungrounded regions and to form a sort of transversal surface waveguide and 2) to partially remove the ground plane with long, longitudinal, and closely spaced slots etched over the ground plane to offset the inductivity of the ground plane. Simulation and measurement results on an example based on two 25-GHz patch antennas show reductions in the mutual coupling of around 9 dB and improvement in broadside radiation pattern by 4 dBi. [ABSTRACT FROM AUTHOR]

Cross-linked polyethylene (XLPE) is widely used as insulation material in high-voltage cables. Impurities, moisture, microvoids, extrusion technology, and other factors all have an effect on insulation properties. However, the primary of this article focus is the self-decomposition characteristic of the cross-linking agent in the cross-linkable polyethylene during the storage process. In general, cross-linkable polyethylene used for 220-kV power cables must be manufactured to cable within one year. However, no studies have been conducted on the performance and stability of cross-linkable polyethylene and its usability during the long-term storage process. As a result, an accelerated storage experiment is carried out in this article to simulate the long-term storage of the cross-linkable polyethylene at room temperature. The electrical and mechanical properties of XLPE samples made from the cross-linkable polyethylene with different equivalent storage times are then measured. The storage activity refers to the activity of dicumyl peroxide (DCP) acting on the properties of the cross-linkable polyethylene after long-term storage because the DCP will be decomposing slowly over time. The result shows that, as storage time increases, the storage activity of the cross-linkable polyethylene decreases due to the gradual decomposition of cross-linking agents in granules. When the XLPE is made from cross-linkable polyethylene stored for an extended period, the cross-linking degrees decrease, and mechanical properties deteriorate significantly. Long-term storage, on the other hand, aids in the improvement of crystal structures and, to some extent, increases ac breakdown strength. The final XLPE properties still meet the Chinese National Standard after one-year storage of the cross-linkable polyethylene. After two years, the thermal extension property, i.e., the elongation under load, is close to the requirements of the Chinese National Standard. However, after five years, the thermal elongation property has degraded to the point where it is no longer acceptable. [ABSTRACT FROM AUTHOR]

Interface pressure between cable and accessory is the key to ensure the long-term reliable operation of cable accessories. The traditional measurement method of interface pressure is off-line measurement through a built-in piezoelectric sensor. However, this method is difficult to operate and damages the interface structure. In addition, the offline measurement cannot reflect the real-time dynamic change of interface pressure during the operation of cable accessories. Therefore, this paper proposes a new method for the on-line measurement of interface pressure between cable and accessory by means of an exterior optical fibre curvature sensor, whose design mechanism is based on the pure bending theory of optical fibre. Then the relationship model involving the exterior curvature of the cable accessory, the radial displacement and the inner interface pressure is established. Finally, interface pressures of the 8.7/10 kV cable accessory under different expansion ratios are measured by the calibrated optical fibre curvature sensor. The measurement results show that the optical fibre curvature sensor measures the exterior curvature of the accessory accurately; the average sensitivity reaches 7.679 nm/mm−1, and the measurable curvature ranges from 0.03 to 0.05 mm−1. The conversion results of interface pressure are basically consistent with the results measured directly by a traditional piezoelectric sensor or simulated mechanically by finite element software. Therefore, the exterior optical fibre sensing technology proposed in this paper is expected to be used for the on-line measurement of the interface pressure between cable and accessory. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

With the advantages of high transmission capacity, low loss, resistance to aging, long lifetime, and unlimited transmission distance, high voltage direct current (HVDC) cable has many advantages in the field of DC power transmission [1]–[3]. However, space charge accumulation in the insulation of DC cables still presents a problem [4]–[9]. [ABSTRACT FROM AUTHOR]

To accomplish experimental advanced superconducting tokamak (EAST) physical targets, the plasma control system (PCS), adapted from DIII-D PCS and deployed on EAST in 2005, keeps in continuous development. Some new control abilities for steady-state operation have been achieved. To avoid the integrator linear drift in long pulse discharge, the linear rate for each integrator channel is precalculated and used to decrease the effect of the acquired raw data during shots. Another strategy applied for long pulse operation is real-time data archiving using data segment technology of MDSplus, which provides the possibility to save all data in segments without increasing the computer memory or reducing the saving frequency. For plasma high-performance and noninductive operations, the plasma beta and loop voltage control was implemented in PCS. Using low hybrid wave, the control algorithm was successfully verified in 2016 EAST campaign. Besides, another two control algorithms are integrated to reduce the divertor heat flux. One is radiation power control, which is successfully feedback controlled by using divertor inert gas puffing and mid-plane supersonic molecular beam injection. The other is quasi-snowflake shape control using PEFIT/ISOFLUX, which shows significant heat load reduction to divertor target according to the experimental result. The present EAST PCS has become a huge system capable of long pulse, high-performance advanced plasma control operation, which is ready to demonstrate ITER-like control contents. [ABSTRACT FROM AUTHOR]

An electronic impedance tuner using the negative resistance of tunneling diodes is proposed in this paper. Aside from the fact that it is an interesting solution to synthesize impedance with reflection coefficient larger than one, this scheme is proven to be simpler and consume less power than the state-of-the-art techniques. The overall circuit topology consists of two parts, namely, impedance tuning circuit including a hybrid block of PIN and tunneling diode for generating a set of impedance points, and wideband nonlinear transmission line-based 360° phase shifter for rotating the set of impedance points around the Smith chart from 1.5 to 5 GHz. The operating power of the electronic tuner is below −25 dBm, which is limited by the tunneling diode. The worst-case maximum power consumption of the electronic tuner is as low as 3 mW. Such an electronic tuner should be useful for the development of on-wafer noise characterization systems. [ABSTRACT FROM PUBLISHER]