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This paper proposes a time-domain method to calculate the fault response in multiterminal dc (MTdc) grids and the performance of hybrid dc breakers. The proposed method, based on traveling waves: 1) provides a sound representation of fault performance by considering all created traveling waves; 2) introduces a new approach to estimate the reflection coefficients; and 3) provides an approximation of the worst case fault location. Then, based on the analytical results, three parameters of the hybrid dc circuit breaker, i.e., current limiting reactor, arrester rated voltage, and time delay are optimally selected with respect to maximum overcurrent, maximum overvoltage, fault clearance time, and energy absorption in arresters through multiobjective optimization. Accuracy and performance of the proposed method are evaluated and verified by time-domain simulation studies in the power systems computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) environment using frequency-dependent models. The results confirm reasonable accuracy of the proposed fault performance calculation and represent a further step towards optimized design of hybrid dc circuit breakers. [ABSTRACT FROM AUTHOR]

In this work, we propose a spin-based voltage comparator using a hybrid spin-CMOS circuit model. In particular, we use a 3T-MTJ (three-terminal magnetic tunnel junction) model with an in-plane magnetic anisotropy (IMA) free layer employing a spin-orbit torque (SOT) based writing scheme in the thermal activation regime to demonstrate a comparator circuit with a resolution close to 50mV. The 3T-MTJ model of the comparator was validated against existing experimental results. In addition, we analyze the delay performance of the comparator along with matching the switching delay of the MTJ with an analytical model. We also discuss potential extensions to the model and general directions for future work. [ABSTRACT FROM AUTHOR]

In this paper, the overvoltage distributions due to the lightning stroke are analyzed for a 500 kV hybrid OHTL-Cable-GIL circuit beside substation, in which the section length is variable. Corona effect is incorporating in order to estimate the attenuation and deformation of overvoltage's travelling waves on transmission lines near substations. The influence of connecting substations surge arrester, direct, and indirect lightning strokes are investigated. ATP/Electro Magnetic Transients Program(EMTP) simulation program is applied to analyze the lightning overvoltage of a 500 kV hybrid OHTL-Cable-GIL system. It was discovered that OHTL-Cable, OHTL-GIL, and hybrid systems produces lightning overvoltages higher than those of a fully cable system and very likely lower than those of a fully OHTL system with the same transmission lengths. This means that the risk of experiencing high lightning overvoltages and stressing system components is higher in a fully-Overhead Line (OHL)circuit than in a partial or full cable or GIL line. Furthermore, using the Cable with MOSA (Metal Oxide Surge Arrester), the results have more regular voltage waveform at substation entrance; also Hybrid line has the same effect of fully GIL. Finally, the corona has a less attenuation effect of overvoltage reached to substation by about 2.7% in case short length OHTL. [ABSTRACT FROM AUTHOR]

Cu–graphene (Cu-G) hybrid nanointerconnects are promising alternative interconnect solutions for the development of future integrated circuit technology. However, the modeling and simulation of their high-frequency electrical performance remains a challenging problem. To enable the design of complicated Cu-G interconnects, we propose a multiphysics modeling and simulation algorithm to cosimulate Maxwell’s equations, dispersion relation of graphene, and Boltzmann equation. We also develop an unconditionally stable time marching scheme to remove the dependence of time step on space step for an efficient simulation of the multiscaled and multiphysics system. Extensive numerical experiments and comparisons with measurements have validated the accuracy and efficiency of the proposed work. This article has also been applied to predict the crosstalk effect and propagation delay of graphene-encapsulated Cu nanointerconnects. [ABSTRACT FROM AUTHOR]

This paper examines two new bidirectional hybrid dc circuit breaker (CB) topologies for application in meshed dc grids. The goal is to retain performance of hybrid dc CB with bidirectional current interruption while reducing semiconductor count, dc CB size, and weight. The fault current is routed to the unidirectional internal valve using multiple additional ultrafast disconnectors. Operation of both topologies is studied using a 320-kV, 16-kA simulation model, as well as demonstrated on a 900-V, 500-A lab prototype. The control systems are presented and discussed in detail. The low-voltage hardware prototypes verify performance of several new technical and operating solutions in laboratory conditions. A comparison is made with the existing dc CB topologies and performance and reliability compromises of each topology are assessed. The conclusion is that it might be possible to halve the dc CB semiconductor count while retaining same 2 ms opening speed and bidirectional operation. [ABSTRACT FROM AUTHOR]

Due to the ISM band being unlicensed for communication applications, a lot of applications have been developed in this band and a good example is WiFi IEEE 802.11a, b, g, n of Bluetooth. This numeracy of applications motivated this paper. The paper is concerned with the design of a low distortion 20 dBm 2.4 GHz class-J power amplifier (PA) since PAs are indispensable in radio communications. The design is based on the AVAGO ATF-52189 transistor with a transition frequency of 6 GHz. The design is done as a hybrid circuit network realized using microstrip elements and surface mount device (SMD) capacitors. The schematic design and simulation are carried out using Keysight's Advanced Design System version 2016.01. The simulated PA exhibited a drain efficiency of 69% and a power output of 21 dBm. [ABSTRACT FROM AUTHOR]

Adiabatic quantum-flux-parametron (AQFP) logic is a promising technology for future energy-efficient high-performance information processing systems. Its static power is zero because of ac flux bias, and its dynamic power is considerably reduced, thanks to the adiabatic switching of the junctions. The lack of high-density memories in the AQFP logic, however, makes it challenging to realize large-scale information processing systems with the use of pure AQFP circuits. We have been developing a Josephson-CMOS hybrid memory to overcome the memory bottleneck in AQFP digital systems. By utilizing the high sensitivity of the AQFP gate, the output current from CMOS memories can be significantly decreased resulting in the reduction of the power consumption. In this article, we designed and fabricated a low-power area-efficient AQFP-CMOS hybrid field-programmable gate array (FPGA), where a CMOS memory is utilized as a rewritable read-only memory to control the AQFP circuits. The AQFP circuit for the AQFP-CMOS hybrid FPGA is composed of logic blocks, switch blocks, and connection blocks, which are clocked by four-phase excitation currents. The AQFP-CMOS hybrid FPGA is fabricated by using the AIST 10 kA/cm2 Nb high-speed standard process and the Rohm 0.18 μm CMOS process. The area and power consumption of the two-by-two AQFP logic-cell system are estimated to be approximately 6.56 mm2 and 12.4 nW at 5 GHz operations, respectively. The power consumption of the CMOS memory was estimated to be 1.02 μW assuming the CMOS source voltage of 3 mV. We demonstrated the operation of the AQFP-CMOS hybrid FPGA at low speed by combining the AQFP logic and the CMOS memory. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) can be used as conductive islands to build-up single-electron transistors (SETs). The characteristics of the QDs define the functional performance of the SETs. In consequence, analyzing the influence of the variations of QD dimensions on the performance of hybrid SET-FET circuits is of high relevance. We employ a self-developed SET compact model which is calibrated to 3-D quantum-mechanics-based simulations in order to obtain realistic model parameters. A method to improve the circuit behavior, i.e., to increase the output current, is proposed. It is concluded that the variation of the QD size presents the largest influence on the overall circuit behavior. [ABSTRACT FROM AUTHOR]

• A CAOC-MPHDCB is proposed by combining with the principle of controllable active oscillation and the MPHDCB based on negative voltage source, which can not only greatly cut down the total cost and operation loss, but also reduce the insulation requirement of commutation circuit. The CAOC only needs an energy storage capacitor to store several kV pre-charge voltage, and can generate a high voltage on a pulse capacitor after several oscillations. Like a NVS, the CAOC can generate a negative voltage on the transfer branch to accelerate the current commutating from the main branch into the transfer branch. In addition, the IGBT full-bridge in the CAOC only needs to withstand the pre-charge voltage with low amplitude at any time. The simulation results verify the effectiveness of CAOC-MPHDCB, and shows its great application prospect in the field of HVDC interruption. The hybrid high voltage DC circuit breaker (HDCB) is widely regarded as the most promising solution to the fault current interruption of VSC-based DC grids. However, because of a large number of power electronic modules connected in series in transfer branch, the cost of existing HDCBs are pretty high, which limiting their large-scale commercial application. In this paper, a novel multi-port hybrid high voltage DC circuit breaker commutated by controllable active oscillation circuit (CAOC-MPHDCB) is proposed. Based on the principle of controllable active oscillation, the proposed CAOC-MPHDCB can realize the reliable commutation and fast interruption of fault current while significantly reducing the total cost and operation loss. In addition, the CAOC-MPHDCB can not only isolate line faults that occur continuously in a short time, but also maintain system ring-network structure after isolating the faulty DC bus. The influencing mechanism of parameters on the performance of CAOC-MPHDCB are analysed in detail, and the selection methods of corresponding parameters are obtained. The simulation results show that the principle of CAOC-MPHDCB is effective and feasible. [ABSTRACT FROM AUTHOR]

Owing to the increased demand for DC interruption, a prototype current-limiting hybrid DC circuit breaker incorporating a fuse and a semiconductor device was developed, based on a completely novel design concept. Recently, hybrid DC breakers have been attracting attention because of their low conduction loss and high-speed current interruption capability. The superiority of this hybrid DC circuit breaker lies in the simultaneous use of the high-speed current-limiting performance of the fuse and the highly reliable current-interruption performance of the semiconductor device. Furthermore, the hybrid DC circuit breaker performs the current interruption without any mechanical contact, thus preventing any delay in operation induced by the mechanical contact. The feasibility of the proposed concept was demonstrated by the successful application of the circuit breaker in a 1 kA fault current interruption procedure. Hence, the current-limiting hybrid DC circuit breaker is suitable for low voltage and medium voltage DC system protection. As the fuses and semiconductor modules progress, the hybrid DC circuit breaker may also adapt to HVDC systems. [ABSTRACT FROM AUTHOR]

This article concerns a hybrid vehicle suspension system that can regenerate energy from vibrations. To further improve the performance of the hybrid vehicle suspension system, the design of the energy-regenerative circuit is investigated. First, the force tests of the linear motor used in the hybrid vehicle suspension were carried out, and the key parameters of the linear motor were obtained. Then, the selection procedures of the protective resistance, inductance, and initial terminal voltage of the super capacitor were discussed. These aforementioned parameters' values were determined by considering the impact of the hybrid suspension on the dynamic performance indexes and the energy-regenerative efficiency. Simulations showed that, in comparison to the original hybrid suspension system, the designed hybrid suspension effectively improved the energy-regenerative efficiency, and that the dynamic performance indexes of the suspension were synchronously improved. Given the result of the simulation analysis, which were validated by bench tests, it is shown that the optimized energy-regenerative circuit presents an enhanced regeneration efficiency, with an improvement of nearly 13% compared to the original suspension system. [ABSTRACT FROM AUTHOR]

This paper proposes a coupled inductor-based hybrid dc circuit breaker topology with zero current switching for fast fault interruption in dc systems. A series resonant circuit comprising of the secondary winding of a two-winding coupled inductor and a charged capacitor (commutation capacitor) is switched on during fault to inject a counter-current pulse, and, consequently, force a zero crossing of fault current. Proposed solution facilitates arcless breaking for a mechanical circuit breaker due to zero current turn-off. The proposed circuit breaker exhibits fast fault response ($\sim$ 30  $\mu$ s), and the response time is programmable based on the design of the coupled inductor and commutation capacitor. Furthermore, presented solution mitigates the requirement of energy-absorbing elements for demagnetizing the dc network following fault interruption, in contrast to conventional dc breakers. The paper also presents two modified circuit-breaker topologies to achieve unipolar voltage profile on the capacitor, which will enable the use of electrolytic capacitors for commutation so that the capacitor stack size is reduced in high-voltage applications. Detailed analysis and design equations are presented to explain the operation of the proposed topologies. Functionality of the proposed circuit breakers is verified through simulation, and experimental results are based on two laboratory prototypes. [ABSTRACT FROM AUTHOR]

A design of a hybrid Gaussian pulse transmitter using a transistor-based pulse generator and two pulse-shaping networks, a shorted stub delay circuit and a 90° hybrid coupler, is presented. A transistor-based pulse generator drives the pulse-forming network to achieve a sub-nanosecond pulsewidth. The shorted stub delay line was modified to optimize the frequency response and phase linearity. The transistor-based pulse generator is an inexpensive way of producing a square pulse of sharp rise time; this design achieved 280-ps rise time. A Schottky diode was used to eliminate the negative part of the output pulse as well as to reduce the ringing. Multiple simulations and measurements were performed to study the circuit behavior. The measurement results demonstrated a pulsewidth as sharp as 153 ps with 0.83-V amplitude and a low ringing on the order of 10%. The Gaussian monopulse was obtained by feeding the Gaussian pulse to a broadband 90° hybrid, which acts as a differentiator in the time domain. The pulse has a width on the order of 100 ps. The transmitter circuit was completed by connecting the monopulse circuit with an antenna. The measured radiated pulse in the far field of the transmitter is a second derivative Gaussian pulse with 85 ps of pulsewidth. [ABSTRACT FROM AUTHOR]

The magnetic potential drop in nonlinear iron can be replaced by equivalent current sheets on linear iron edges. Based on this principle, this paper proposes a nonlinear subdomain and magnet circuit hybrid model (SMCHM) for open-circuit field prediction in surface-mounted permanent-magnet machines. The values of current sheets are calculated from a magnetic circuit and used as boundary conditions in the subdomain model. The finite element (FE) validation is performed, which shows the SMCHM can accurately predict the magnetic field distribution and electromagnetic performance as nonlinear FE method does. The accuracy of SMCHM is significantly higher than the conventional subdomain model neglecting a nonlinearity effect, and the computation speed of SMCHM is dramatically faster than the FE model. [ABSTRACT FROM AUTHOR]

In this work, the massive modelling and computation costs required by the calculation of the magnetic leakage coefficient were avoided by using the three-dimensional finite element method (3D-FEM) in the initial design and optimisation of hybrid magnetic couplers (HMCs). The equivalent magnetic circuit network model of HMCs was established, and the equivalent reluctance of the model was calculated to obtain the analytic expression of the magnetic leakage coefficient of HMCs. A set of 1:2 prototypes was designed and manufactured. Simulation analysis and experimental tests were conducted to verify the correctness of the calculation of magnetic leakage. The calculated and experimental values of the magnetic leakage coefficient and the 3D-FEM were in good agreement. The output torque value of the HMC was analysed and calculated by considering that the air-gap leakage was closer to the test value and was more accurate than the value calculated without considering the airgap leakage effect. This study provided a theoretical reference for the design and investigation of HMCs. [ABSTRACT FROM AUTHOR]

In recent years, dc distribution grids have become increasingly popular because of the interest in the diffusion of distributed renewable energy. In this scenario, dc distribution grids are also favored because of the increased use of batteries and power electronic loads. The main limit to the spread of dc grids is their protection devices, which still present several problems. At present, protection devices are represented by traditional mechanical breakers or static electronic components. The first, which interrupt dc currents, have good reliability but need maintenance and have long intervention periods. In contrast, electronic switches are fast and reliable, but they reduce the efficiency because of their voltage drop. In this scenario, some hybrid breakers have been proposed to obtain the advantages of both devices. The previous solutions of hybrid breakers still suffer several critical issues and, usually, are not capable of protecting a system from short circuits without significantly reducing their lifetime. In this paper, a new low-voltage hybrid circuit breaker topology is proposed. The procedure to dimension all of the active and passive components in the device is analyzed, and the effectiveness of the proposed solution is proven by means of experimental results obtained using a prototype. [ABSTRACT FROM AUTHOR]

Recurrent neural networks are currently subject to intensive research efforts to solve temporal computing problems. Neuromorphic processors (NPs), composed of networked neuron and synapse circuit models, natively compute in time and offer an ultralow power solution particularly suited to emerging temporal edge-computing applications (wearable medical devices, for example). The most significant roadblock to addressing useful problems with neuromorphic hardware is the difficulty in maintaining healthy network dynamics in recurrent neural networks. In animal nervous systems, this is achieved via a multitude of adaptive homeostatic mechanisms which act over multiple time scales to counteract network instability induced via drift, component failure, or learning processes such as spike-timing dependent plasticity. One such mechanism is neuronal intrinsic plasticity (IP) where a neuron adapts its parameters which govern its excitability to fire around a target rate. The approach employed in state of the art NPs, based on a central volatile memory remotely setting model parameters, critically constrains parameter variety and bandwidth rendering realization of these essential mechanisms impossible. This paper demonstrates how reconfigurable nonvolatile resistive memories can be incorporated into neuron and synapse circuits allowing memory to be truly colocalized with the computational units in the computing fabric and facilitating the realization of massively parallel local plasticity mechanisms in neuromorphic hardware. Exploiting nonconventional programming operations of HfO2 based RRAM (stochastic SET and the RESET random variable), we propose a technologically plausible IP algorithm and demonstrate its use in the case of a recurrent neural network topology whereby the system self-organizes to sustain stable and healthy network dynamics around a target firing rate. [ABSTRACT FROM AUTHOR]

This article reviews dc transmission technologies for future power grids. The article emphasises the attributes that each technology offers in terms of enhance controllability and stability, resiliency to ac and dc faults, and encourages increased exploitations of renewable energy resources (RERs) for electricity generation. Discussions of ac/dc and dc/dc converters reveal that the self-commutated dc transmission technologies are critical for better utilisation of large RERs which tend to be dispersed over wide geographical areas, and offer much needed controllability for operation of centralised and decentralised power grids. It is concluded that the series power flow controllers have potential to restrict the expensive isolated dc/dc converters to few applications, in which the prevention of dc fault propagation is paramount. Cheaper non-isolated dc/dc converters offer dc voltage tapping and matching and power regulation but they are unable to prevent pole-shifting during pole-to-ground dc fault. To date hybrid dc circuit breakers target dc fault isolation times ranging from 3 to 5 ms; while the resonance-based dc circuit breakers with forced current zeros target dc fault clearance times from 8 to 12.5 ms. [ABSTRACT FROM AUTHOR]

In this paper, online fault detection and isolation (FDI) of multiple faults for a hybrid dynamical system based on partly decentralized model-based diagnosis architecture is presented. A quantitative model-based diagnosis method for both discrete and parametric faults occurring sequentially is proposed here, in which system global model is partitioned into various subsystems by analyzing the global fault sensitivity signature matrix (GFSSM) and mode change sensitivity signature matrix (MCSSM) of the global system. A local diagnoser is designed for each subsystem resulting in local GFSSM and MCSSM; and supervisory diagnoser is required only when if more than one local diagnoser generate alarm. The proposed method can also be used to solve the problem of sequentially occurring faults detection and isolation for a centralized or distributed architecture-based diagnosis. Residual sensitivity signature with the GFSSM and MCSSM is used to determine a smaller set of possible fault candidates after detection of a fault by the respective local diagnoser. It is shown that use of fault direction information from GFSSM and MCSSM improves the fault isolation process for discrete or parametric fault and also improves the local parameter estimation process. The identified discrete fault or estimated parameters are then used to update the corresponding nominal model which allows for FDI of the next fault. For robust FDI, adaptive residual threshold is used which accounts for the process, measurement uncertainties and mode change, including the parameter estimation uncertainties. Algorithms and codes have been developed in industry preferred MATLAB-LabVIEW interface for real time monitoring of the hybrid system. The developed method is first tested on the four-tank hybrid system model through simulation. Then it is experimentally validated with real experimental data collected from a reduced-scale equivalent hybrid electronic circuit model of a bench mark two-tank system for checking the robustness of the proposed approach. The developed method is shown to produce accurate diagnosis of sequentially occurring faults in hybrid systems and saves valuable CPU time as compared with centralized approach. [ABSTRACT FROM AUTHOR]

Recently, exploiting emerging nonvolatile memories to implement the process-in-memory (PIM) paradigm have shown great potential to address the von Neumann bottleneck and have attracted extensive research and development. In this paper, we present a novel PIM platform—spintronic processing unit (SPU), within spin transfer toque magnetic random access memory (STT-MRAM). This energy-efficient and reconfigurable PIM platform can perform different tasks—data storage and logic computing—using the same physical fabric that is programmable at the finest grain, i.e., the individual memory cell level, without the need to move data outside the memory fabric. The proposed SPU works just like a typical memory and all the logic functions are achieved through regularmemory-like write and read operations with minimal modifications. The functionality and performance are evaluated via hybrid circuit simulations under the 40-nm process technology node. Our proposed SPU is expected to be a feasible PIM platform in the near future, owing to the increasing maturity of STT-MRAM. [ABSTRACT FROM AUTHOR]

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The dc fault current has a high amplitude and a fast rising speed, therefore with regard to the hybrid dc circuit breaker, it is hard to meet the requirement of a high breaking capacity while maintaining economically efficient. The SI-SFCL can prevent the speed of the fault current from rising too fast, and ensure the current remains under the interrupting capability of the dc circuit breaker, so the couse of the SI-SFCL and the dc circuit breaker is an effective solution for fault clearing in dc grids. In this paper, the current-limiting requirement of the DCCB is given, and a simplified equivalent circuit of the active SI-SFCL is proposed, based on which the matching between the electrical parameters of the active SI-SFCL and the dc circuit breaker is studied. Parameter constraint and the protection voltage range of the active SI-SFCL are given. Finally, the conclusion on the matching between the electrical parameters of the active SI-SFCL and the DCCB is verified by MATLAB/Simulink. [ABSTRACT FROM AUTHOR]

Abstract A SiC fiber-reinforced composite containing a SiC-ZrB 2 mixed matrix (SiC f /(SiC-ZrB 2)) with high density and enhanced mechanical properties was fabricated. ZrB 2 at 5 or 40 vol% was added to a (SiC + C) slurry to be infiltrated into the voids of 2D woven Tyranno™-SA grade-3 fabrics by electrophoretic deposition. Subsequent hot pressing at 1300 °C and 10 MPa for 1 h, followed by liquid silicon infiltration (LSI) at 1600 °C for 5 h in an Ar atmosphere resulted in the formation of the reaction-bonded SiC matrix, which revealed a composite density close to 97%. SiC f /(SiC-ZrB 2) having open porosities of 0.2–0.6% showed peak strengths of 398 and 320 MPa for 5 and 40 vol% ZrB 2 addition, respectively. The large mismatch in the coefficient of thermal expansion and Young's modulus between the SiC and ZrB 2 phases was attributed to a reverse trend in the strength of composites. Brittle behavior of the composites in flexure can be explained by the strong bonding between the matrix and fibers formed by the reaction of interphase with molten Si during LSI. Strength retention after oxidation at 1000 and 1400 °C for 2 h was also compared in terms of ZrB 2 amount contained in the composites. [ABSTRACT FROM AUTHOR]

The frequency regulation service (FRS) is playing an increasingly important role in maintaining the power balance between generation and consumption. Moreover, the recent progress in information and communication technologies has enabled residential customers to participate in FRS through direct control over appliances, such as inverter air conditioners (ACs), whose market share is growing rapidly and has made up a large fraction of electricity consumption. Inverter ACs can change compressor's speed continuously to adjust operating power and provide FRS for the system operation. In this paper, the thermal model of a room and the electrical model of an inverter AC for providing FRS are developed. The model of the inverter AC is equivalent to a generator. In this manner, the aggregation of inverter ACs can be controlled just as traditional generators. Besides, a stochastic allocation method of the regulation sequence among inverter ACs is proposed to reduce the effect of FRS on customers. A hybrid control strategy by taking into account the dead band control and the hysteresis control is also developed to reduce the frequency fluctuations of power systems. The effectiveness of the proposed models and control strategies is illustrated in the numerical studies. [ABSTRACT FROM AUTHOR]

The paper presents a new family of low voltage direct current, hybrid circuit breakers for urban traction vehicles (DCH-T) that also can be used in related industrial applications. A hyper-speed current breaking operation is performed by the means of a serial hybrid system, additionally protected by a fuse and a surge arrester. This process is arcless under any conditions. DCH-T circuit breakers are characterized by unique constructional and operational features and superior short-circuit parameters that are unreachable for classical magnetic blow-out devices. They effectively reduce short-circuit currents and the thermal and electrodynamic consequences of this phenomenon. They can protect all types of semiconductor converters used in electric traction vehicle drives. Moreover, they operate selectively in relation to the substation circuit breakers. Their contact life (even under short-circuit conditions) is equal to their mechanical life. Despite all the breaker standard functions, they offer special functions, such as cooperation with an on-board vehicle computer or a traffic control system. They are environmentally neutral and they can meaningfully improve passenger safety. Chosen thermal problems of DCH-T breakers has been modeled with the aid of simulation software and analyzed. DCH-T short-circuit parameters have been verified experimentally and the results are presented herein. [ABSTRACT FROM AUTHOR]

This technical note presents the conceptual design of bidirectional hybrid dc circuit breaker for quench protection circuit (QPC) of the China fusion engineering test reactor. The rated parameter of bidirectional hybrid dc circuit breaker is up to 70 kA and 15 kV. The novel scheme based on a mechanical breaker and the controlled static circuit breaker (SCB) in parallel is proposed. The mechanical breaker consists of three independent control contacts to realize the rapid transfer of the large current and fast recovery of dielectric strength. The SCB is composed of the insulated-gate bipolar transistors (IGBTs) unit and four diode units in a rectifier scheme for both current directions. Moreover, the feasibility of bidirectional dc circuit breaker, such as the turn-on reliability of IGBTs unit, and voltage sharing and current sharing of each IGBTs are investigated in this technical note, finally, the conceptual design result of the QPC is given. [ABSTRACT FROM AUTHOR]

Memristor is a novel passive electronic element with resistance-switching dynamics. Due to the threshold property and the variable conductivity of the memristive element, its composite circuits are promising for the implementation of logic operations. In this paper, a flexible logic circuit based on the threshold-type memristor and the mature complementary metal-oxide-semiconductor (CMOS) technology is designed for the realization of Boolean logic operations. Specifically, the proposed method is able to perform the NAND, AND, OR, and NOR gate operations through two phases, i.e. the writing operation and the reading operation. In such implementation, the total delay is very small especially for time-sequence inputs. Furthermore, for existing memristor-based logic implementation, a contrastive analysis with relevant computer simulations is carried out. The experimental results indicate that the proposed method is capable of realizing all basic Boolean logic operations, and some more complicated cascaded logic operations with more compact circuit structures, higher efficiency, and lower operating cost. [ABSTRACT FROM AUTHOR]

Exploration and exploitation are two cornerstones for multi-objective evolutionary algorithms (MOEAs). To balance exploration and exploitation, we propose an efficient hybrid MOEA (i.e., MOHGD) by integrating multiple techniques and feedback mechanism. Multiple techniques include harmony search, genetic operator and differential evolution, which can improve the search diversity. Whereas hybrid selection mechanism contributes to the search efficiency by integrating the advantages of the static and adaptive selection scheme. Therefore, multiple techniques based on the hybrid selection strategy can effectively enhance the exploration ability of the MOHGD. Besides, we propose a feedback strategy to transfer some non-dominated solutions from the external archive to the parent population. This feedback strategy can strengthen convergence toward Pareto optimal solutions and improve the exploitation ability of the MOHGD. The proposed MOHGD has been evaluated on benchmarks against other state of the art MOEAs in terms of convergence, spread, coverage, and convergence speed. Computational results show that the proposed MOHGD is competitive or superior to other MOEAs considered in this paper. [ABSTRACT FROM AUTHOR]

Porous structure materials indicate brilliant distribution and great absorption ability, that suggesting the potential application of aerogel state graphene based materials. Aerogel intermedium assisted method was developed and optimised to prepare bendable electrode. Hydrothermal schedule was utilised suggesting potential application at low cost and large-scale factory print issues, rather than consuming high money cost and long labour time. Nickel sulphide has been anchored onto the graphene aerogels via one-pot hydrothermal method. The membrane electrode was made with the carbon ink and aerogel intermedium on the Poly(ethylene terephthalate) (PET) plate. The bendable electrode was fabricated with intermedium and commercial carbon ink, and indicates good performance and economic consumption. The complex membrane capacitor shows the much more brilliant performance than the pure carbon membrane capacitor, with specific capacitance (31.40 mF/cm2 at 4 mV/s and 17.74 mF/cm2 at 2 mA/cm2). [ABSTRACT FROM AUTHOR]

Renewable energy sources and storage devices are combined as a hybrid energy system to provide reliable electricity to the load. Naturally, such sources have distinct voltage–current characteristics. In this paper, a dual input positive output voltage DC–DC converter is used as power electronic interface for integration of the above nature of sources. Different modes of operation of the above converter such as buck, boost and buck–boost are discussed with necessary circuit and equations. A detailed current and voltage stress analysis of various switching devices available in the converter is also discussed. This analysis helps to select the switching devices in an optimized and cost-effective manner. The effect of equivalent series resistance of such storage elements on the output voltage is investigated in detail. The MATLAB simulation of the power converter is carried out, and a prototype of the converter is also fabricated. A power control strategy is proposed for the power converter with the objective of voltage regulation during the load side and source side disturbances. Different experimental analyses of the fabricated converter in the laboratory environment have been conducted, and the test results are presented in this paper. [ABSTRACT FROM AUTHOR]

This paper presents, for the first time, the hybrid use of loading techniques (which involve terminating the spiral arms with different structures to give a resistive or capacitive effect) and a novel technique of cavity groove in order to enhance the performance of two-arm, cavity-backed, 2–18 GHz spiral antenna. The antenna is made on Duroid 5880 and has the smallest form factor (50 mm diameter), meeting all the performance metrics, which are targeted for efficient performance of a spiral antenna for ultra-wideband (UWB) applications. Measured results match the simulated results and show that by the utilization of hybrid loading and cavity groove, the gain is increased by a factor of 3.65 dBi and the axial ratio is improved by 2.73 dB at (2 GHz) as compared to a simple Archimedean antenna made on Duroid 5880, without increasing the size. The proposed antenna shows 2.25 dB more gain and improved axial ratio performance as compared to a simple Archimedean spiral antenna made on Tmm4, without the utilization of the hybrid techniques proposed earlier in the literature. [ABSTRACT FROM AUTHOR]

While interior permanent magnet (IPM) machines have been considered state of the art for traction motors, synchronous reluctance (SynRel) motors with advanced materials can provide a competitive alternative. IPM machines typically utilize neodymium iron boron permanent magnets, which pose an issue in terms of price, sustainability, demagnetization at higher operating temperatures, and uncontrolled generation. On the other hand, SynRel machines do not contain any magnets and are free from these issues. However, the absence of magnets as well as the presence of bridges and centerposts limit the flux-weakening capability of a SynRel machine, and limit the achievable constant power speed ratio without having to significantly oversize the machine and/or the power converter. In this paper, a new material referred to as the dual-phase magnetic material, where nonmagnetic regions can be selectively introduced within each lamination, will be evaluated for SynRel designs. The dual-phase feature of this material enables nonmagnetic bridges and posts, eliminating one of the key limitations of the SynRel designs in terms of torque density and flux weakening. This paper will present the design, analysis, and test results of an advanced proof-of-concept SynRel design utilizing dual-phase material with traction applications as the ultimate target application. [ABSTRACT FROM PUBLISHER]

This paper proposes an interleaved hybrid converter (IHC) with simultaneous dc and ac outputs for dc microgrid applications. The IHC is realized by interleaving two conventional boost converters and replacing the active switch of lower boost converter by an H-bridge voltage source inverter. This arrangement enables the proposed IHC to operate at the condition where the sum of duty ratio (\boldsymbolD ) and modulation index (\boldsymbolM ) can be more than or equal to one, i.e., \boldsymbolD + \boldsymbolM \geq 1, unlike the conventional hybrid converters. The proposed IHC is capable of giving dc with high voltage gain and improved ac with reduced harmonic distortion. Due to interleaving nature of the IHC, input current is shared between the power converters and thus enables the use of low current rated switching devices and lower values of inductors. This results in reduced power losses and increased efficiency as compared to the conventional hybrid converters. The IHC also has inherent shoot-through protection capability, better electromagnetic interference immunity, and reliability. A modified unipolar sinusoidal pulse width modulation technique is used to control the power flow of the IHC. Detailed mathematical modeling of the proposed IHC is carried out and its steady-state behavior is validated through experimental results on a 500 W laboratory prototype. [ABSTRACT FROM PUBLISHER]

Direct current (DC) circuit breakers are a key enabling technology for fault management in multiterminal highvoltage DC (HVDC) systems. DC fault isolation is challenging due to the high rate of rise of the fault current and the lack of natural current zero-crossings found in ac systems. In this paper, we present a novel superconducting hybrid dc circuit breaker that utilizes the intrinsic characteristics of the superconductor material. The automatic quench of the superconductor coil as a result of a high fault current transfers the current from the mechanical switch to the semiconductor switch. The isolating mechanical switch is able therefore to open at low current and recover its dielectric capability rapidly. A low voltage DC circuit breaker prototype has been built using a multistrand magnesium diboride (MgB2 ) coil, a vacuum interrupter, and an insulated-gate bipolar transistor module. This prototype successfully demonstrated interruption of 500 A DC within 4.4 ms. This paper presents the design of the superconducting hybrid breaker prototype and a detailed analysis of the experimental results. This superconducting hybrid dc circuit breaker has significant potential for scaling up the high-voltage and high-current applications. [ABSTRACT FROM AUTHOR]

Mobile terminals are often in the dynamic environment of heterogeneous networks. For some reasons, they need to switch between different networks, namely vertical handover. At this moment, it is a very crucial issue for the mobile terminal to select the best suitable one rapidly from all detected alternative networks on condition that the selection result can avoid the ping-pong effect as much as possible. This paper proposes a heterogeneous network selection algorithm based on the combination of network attribute and user preference. Taking full account of user preferences for each candidate network and the actual situation of heterogeneous networks, the algorithm combines three typical MADM methods, namely FAHP, Entropy and TOPSIS. We first use FAHP to calculate the subjective weights of network attributes and the subjective utility values of all alternatives for four typical traffic classes, and then use Entropy and TOPSIS to respectively get the objective weights of network attributes and the objective utility values of all alternatives. Finally, according to the comprehensive utility value of every candidate network and a threshold, the most appropriate network, whose comprehensive utility value is maximum and greater than the corresponding value of the current network of the mobile terminal, is selected to access. The proposed algorithm not only avoids the one-sided nature of a single algorithm, but also dynamically adjusts the proportion of each algorithm in the final result according to the actual requirements. Simulation results indicate that the proposed algorithm can accurately select the optimal access network, significantly reduce the number of vertical handovers and provide the required QoS and QoE in terms of the quantified benefit from vertical handoff, compared with three existing hybrid algorithms. [ABSTRACT FROM AUTHOR]

Printed electronics based on nanomaterials has been a potential alternative to conventional electronic technology and is favorable for flexible polymer substrates. However, a printed circuit has insufficient electrical performance and mechanical reliability under flexible stress. We designed hybrid Ag pastes containing Ag nanoparticles (NPs, 30–50 nm) and Ag flake (F, 2.5–3.5 μm in diameter) particles to overcome the obstacles of printed electronics. Six types of Ag paste (Ag NPs-x wt% F paste, x = 0, 10, 25, 50, 75, and 100) were screen-printed onto a polyimide substrate and sintered at 200 °C for fabricating a flexible circuit. We simulated a coplanar waveguide pattern before measuring the S-parameter using high frequency structural simulation. To investigate the radio frequency characteristics of various Ag circuits under sliding stress, a network analyzer and Cascade’s probe system in the frequency range from 1 to 10 GHz were employed before and after 100,000 sliding cycles. Hybrid Ag circuits showed stable electrical conductance and signal transmission, while pure Ag particle circuits showed a definite drop of electrical conductance (over 30% increase of electrical resistance) under cyclic sliding stress. The microstructural crack behavior demonstrated that the Ag F content within the Ag hybrid circuits effectively suppressed crack propagation, leading to improved flexibility of the sintered Ag circuit. [ABSTRACT FROM AUTHOR]

The paper deals with a key issue, how to limit the hazard and assure reliability, safety and repeatability of operation of selected critical devices protecting electrical power systems. The main research is focused on the incorrect operation of hybrid switches caused by random disturbances of the thyristor gate signals in the electrodynamic drive coil power supply circuit. Firstly, a pilot experiment on the operation of hybrid circuit breaker actuators under random disturbance conditions was carried out and the results are presented. Next, an in-depth operation analysis, based on experimental and simulation research, according to setting conditions of the circuit breaker actuator parameters such as capacitance, voltage and switching time was performed. A simulation study with the use of a field-circumferential model in the Ansys Maxwell program of electrodynamic propulsion of rectilinear motion, which enables energy transfer from the capacitor bank to the actuator coil power supply at selected time intervals, was executed. The study analysed the impact of the discontinuity of energy transfer on the dynamic properties of the actuator and some recommendations for designers and users on how to limit this hazard are formulated. [ABSTRACT FROM AUTHOR]

This research addresses the chaotic synchronization of an uncertain chaotic system as the master system with multiple chaotic systems as slave systems, simultaneously. Adaptive control and parameter estimation laws based on the hybrid modified projective synchronization (HMPS) method are derived to synchronize the states of a master chaotic system with a proportional rate of their corresponding states from multi-slave chaotic systems. The feasibility and stability of the proposed scheme are analytically proved by means of the Lyapunov stability theorem. Furthermore, the validity of the proposed HMPS method and the theoretical discussions are verified by numerical simulations. The simulation results confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

An active damping method for Thomson coil actuated ultrafast mechanical switches is proposed, including its control. Ultrafast mechanical switches are crucial for both dc and ac circuit breakers that require fast-acting current-limiting capabilities. However, fast motion means high velocity at the end of travel resulting in over-travel, bounce, fatigue, and other undesirable effects. The active damping proposed in this paper not only avoids such issues but actually enables faster travel by removing limitations that would otherwise be necessary. This active damping mechanism is applicable in particular to medium- and high-voltage circuit breakers, but can be extended to actuators in general. A 15 kV/630 A/1 ms mechanical switch designed to enable the fast protection of medium voltage dc circuits is used as a testbed for the concept. The switch is based on the principle of repulsion forces (Thomson coil actuator). By energizing a second coil, higher opening speeds can be damped, resulting in limited over-travel range of the movable contact. The overall structure is simple and the size of the overall switch is minimized. To validate the concept and to study the timing control for best active damping performance, both finite element modeling and experimental studies have been carried out. [ABSTRACT FROM PUBLISHER]

GaN high electron mobility transistors were integrated into monolithic microwave integrated circuits (MMICs) by molding hetero-substrates and using a redistribution layer (RDL). Driver amplifiers (DAs) and high-power amplifiers (HPAs) on SiC substrates were molded with matching circuits on Si substrates including Cu-filled through-substrate vias (TSVs), and their circuits on hetero-substrates were connected using a Cu RDL. This was the first attempt to fabricate hetero-substrate MMICs with five chips for two-stage power amplifiers. This method will be very useful to increase the achievable quantity of small DAs and HPAs—as opposed to using large MMICs with matching circuits on a SiC substrate—and to reduce production costs. Furthermore, various frequency bands, such as the millimeter-wave band, can be accommodated by changing the Si chips of the matching circuits. [ABSTRACT FROM AUTHOR]

Cloud computing provided a framework for seamless access to resources through network. Access to resources is quantified through SLA between service providers and users. Service provider tries to best exploit their resources and reduce idle times of the resources. Growing energy concerns further makes the life of service providers miserable. User’s requests are served by allocating users tasks to resources in Clouds and Grid environment through scheduling algorithms and planning algorithms. With only few Planning algorithms in existence rarely planning and scheduling algorithms are differentiated. This paper proposes a robust hybrid planning algorithm, Robust Heterogeneous-Earliest-Finish-Time (RHEFT) 1 Robust Heterogeneous-Earliest-Finish-Time (RHEFT). 1 for binding tasks to VMs. The allocation of tasks to VMs is based on a novel task matching algorithm called Interior Scheduling. The consistent performance of proposed RHEFT algorithm is compared with Heterogeneous-Earliest-Finish-Time (HEFT) 2 Heterogeneous-Earliest-Finish-Time (HEFT). 2 and Distributed HEFT (DHEFT) 3 Distributed HEFT (DHEFT). 3 for various parameters like utilization ratio, makespan, Speed-up and Energy Consumption. RHEFT’s consistent performance against HEFT and DHEFT has established the robustness of the hybrid planning algorithm through rigorous simulations. [ABSTRACT FROM AUTHOR]

In this paper, vibration suppression of shear deformable beams with hybrid material-foundation viscoelastic damping is studied. The precise behavior of viscoelastic polymeric structures is taken into consideration by Boltzmann superposition integral and utilizing dynamic mechanical analysis (DMA) results while foundation viscoelasticity is adapted by Kelvin-Voigt model. The integro-partial differential equations of motion are derived based on the Timoshenko theory via Hamilton principle. Assessment of the solution procedure is carried out by comparison with elastic Timoshenko and viscoelastic Euler-Bernoulli cases. Transient response, natural frequency and modal loss factor are attained by Fourier transform, weighted residual method and numerical iterative algorithm. Influences of hybrid viscoelastic damping, foundation properties, geometrical parameters and boundary conditions on vibration characteristics and dynamic response are investigated via comprehensive parametric study. Due to the absence of similar results in the literature, this paper is likely to fill a gap in the state of the art of this problem. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic dielectric recovery synergy (DDRS) of hybrid circuit breakers (HCBs) with CO2 gas and vacuum gaps in series. The interaction between the vacuum arc and CO2 gas arc is simulated by the continuous transient arc model and Mayr arc model. The simulation results indicate that the extra methods, for example, dividing capacitors, are needed to obtain optimal DDRS of HCB. The prototype of HCB and the test circuit are established. The influence of the coordination of arcing time, dividing capacitors, and the CO2 gas pressures on the transient recovery voltage (TRV) distribution and the breaking capacity is investigated. The differences of HCBs with SF6 gas and CO2 gas are also compared. According to the results, favorable DDRS in HCB can be obtained in the condition that the vacuum gap endures the initial TRV while the following major TRV distribution is mainly depended on the dynamic dielectric in CO2 gas gap. However, the dynamic dielectric recovery of CO2 gas gap is limited by the structure of rotating arc CO2 gas interrupter in this paper. In the future, the interruption capacity of HCB based on CO2 gas can be improved by synergy control, as the development of CO2 gas circuit breakers. [ABSTRACT FROM PUBLISHER]

This paper focuses on the vacuum arc commutation between the vacuum arc and the parallel-connected insulated gate bipolar transistor (IGBTs) of dc microgrid hybrid circuit breakers (HCBs). The principle of the dc HCB is analyzed and the vacuum arc commutation is the important process in dc HCB interruption, in which the arcing time and the interrupting time are depended. The test circuit of the vacuum arc commutation is established by simplifying the parallel-connected IGBTs to an on-state resistance with large thermal capacity. The influence of the magnitude of the main current, the resistance of the IGBTs, and the externally applied transverse magnetic field (TMF) on the vacuum arc commutation is investigated by the electrical measure and the development of vacuum arc which is observed by a high-speed CMOS camera. The criteria of the vacuum arc commutation are obtained. The interaction between the vacuum arc commutation and the externally applied TMF is researched and the optimal magnitude of the TMF is gained. The vacuum arc commutation characteristics of dc HCB can be useful for parameters design and control strategy. [ABSTRACT FROM PUBLISHER]

This paper examines the interval forecasting of carbon futures prices in one of the most important carbon futures market. Specifically, the purpose of this study is to present a novel hybrid approach, which is composed of multioutput support vector regression (MSVR) and particle swarm optimization (PSO), in the task of forecasting the highest and lowest prices of carbon futures on the next trading day. Furthermore, we set out to investigate if considering some potential predictors, which have strong influence on carbon futures prices, in modeling process is useful for achieving better prediction performance. Aiming at testing its effectiveness, we benchmark the forecasting performance of our approach against four competitors. The daily interval prices of carbon futures contracts traded in the Intercontinental Futures Exchange from August 12, 2010, to November 13, 2014, are used as the experiment dataset. The statistical significance of the interval forecasts is examined. The proposed hybrid approach is found to demonstrate the higher forecasting performance relative to all other competitors. Our application offers practitioners a promising set of results with interval forecasting in carbon futures market. [ABSTRACT FROM AUTHOR]