Bearingless switched reluctance motors (BSRMs) have both magnetic bearing as well as conventional motor characteristics which make them suitable for diverse industrial applications. This study proposes a design methodology for a BSRM in order to calculate the appropriate geometrical dimensions essential for realising a minimum levitation force at every orientation of rotor. It is based on the stator–rotor overlap angle and helps in reducing the complexities associated with the self-bearing operation of a switched reluctance motor (SRM). Different from a conventional SRM, the motor under study deploys a special single set parallel winding scheme for simultaneous production of torque as well as radial force. An analytical model incorporating this single set winding is developed for calculating the torque and the radial force. The proposed bearingless design is verified by developing a two-dimensional finite-element model of a 12/8 SRM in ANSYS Maxwell.

This study presents a novel approach to content-aware image sizing by combining the continuous approach using saliency histogram equalisation (SHE) and the discrete approach using seam carving (SC). It constructs a non-uniform quad mesh to represent an image by equalising its saliency histogram (SH), and changes the mesh size to represent the resized image by carving seams of insignificant quads in the SH domain. As SHE is simple to implement, and SC can be obtained via dynamic programming, the proposed SHE combined with SC (SHE-SC) algorithm is computationally efficient. Experimental results show that SHE-SC is preferable to other existing algorithms.

Without the aid of licensed channel, deploying long-term evolution (LTE) networks over unlicensed spectrum (named standalone LTE-U networks) faces the difficulty of establishing and maintaining synchronisation between user equipments and base stations. In this work, considering the two modes of listen-before-talk-based channel access scheme, frame-based equipment (FBE) and load-based equipment (LBE), the authors propose analytical frameworks to study the successful probability of synchronisation and the energy consumption of synchronisation in a standalone LTE-U network. Specifically, for the LBE mode, the authors also propose a Lattice-Poisson algorithm-based approach to derive the distribution of the channel non-occupancy period of a standalone LTE-U network. Furthermore, the authors explore the impact of diverse protocol parameters of both FBE and LBE modes on the two studied performance metrics. Simulation results demonstrate the accuracy of the analysis, and shed some light on the selection of FBE and LBE for standalone LTE-U networks, in terms of synchronisation, energy consumption, and throughput of standalone LTE-U and Wi-Fi networks.

Standalone microgrids that comprise distributed generation sources (DGSs) or energy storage systems (ESSs) exist on off-shore islands or remote areas. When a fault occurs in a standalone microgrid, the microgrid is separated into several zones with pre-specified DGS or ESS supplying power to local loads. After the fault is cleared, the three-phase voltages and frequencies may differ among these zones. To restore the original microgrid topology, these zones must be reconnected to each other by synchronisation. A synchronisation controller of the DGS/ESS that accounts for slightly different three-phase voltages and frequencies in two separate zones is presented. The Clark transform and Mamdani fuzzy rules are used to implement the controller, providing fast and seamless synchronisation. Simulation results using a standalone microgrid show the practical applicability of the proposed method.

A method to excite dual band for a microstrip antenna on a two-layer substrate by combining the proximity feed and the inset feed in a simple way is presented. Both linearly polarised and circularly polarised (CP) dual-band waves can be excited. The CP antenna consists of two stacked perturbed patches. If the lower patch were directly connected to the feed line, it is hard to form two bands. A single resonant frequency is found dependent on the size of the lower patch and is insensitive to the loading effect of the upper patch. The lower patch is inset coupled to the feed line. The authors found that two bands can easily be excited. To demonstrate the idea, a dual-band global positioning system antenna is designed and tested. The achieved impedance bandwidths are 60 MHz centred at 1215 and 65 MHz centred at 1563 MHz. The 3 dB axial-ratio bandwidths are 15 MHz centred at 1228 and 20 MHz centred at 1575 MHz.

The authors present a tunable linearity improvement of complementary metal–oxide–semiconductor low-noise amplifier (LNA) using derivative superposition method and an active MOS field-effect transistor feedback transistor. The proposed LNA achieves a third-order input intercept point (IIP3) of 21 dBm, 9.43 dB gain, and 2.4 dB minimum noise figure. In addition, the proposed LNA method dissipates 28.4 mW supplied from 1.8 V voltage source. The proposed LNA provides flexibility to tune the power dissipation and linearity according to the work environment. They perform the simulation with keysight ADS2016.01 software utilising 180 nm TSMC model files.

We present a two-stage inverter with high-voltage conversion ratio employing modified finite-set model predictive control (MPC) for utility-integrated low-power photovoltaic (PV) applications. The proposed system is suitable for low PV power applications, the calculated efficiency at 150 W input power and 21 times boosting ratio was around 88%. The presented system is a high gain, transformerless, and with less leakage current system. Switched inductor quadratic boost converter composes the first stage of the proposed system, due to its high step-up ability. It can boost the input voltage up to 30 times. A five-switch current-source inverter represents the dc/ac stage. The MPC algorithm are designed to control the system and perform the following tasks, take out the maximum power (MP) from the PV, controls the proposed system to operate at maximum power, step-up the PV voltage, and introduces low current with low total harmonic distortion (THD) and with unity power factor with the grid voltage. Switching states are selected to reduce the switching losses, but forcing the h-bridge switches to operate at the fundamental frequency.

Variational and partial differential equation (PDE)-based algorithms have been widely applied in image restoration. However, it may produce undesirable staircase effect or blur image edges. To avoid these problems, a second-order PDE model based on directional diffusion has been proposed for image restoration. This model can just diffuse along the edge's tangential direction of the original image. Thus it can preserve the edges, avoid the staircase effect in the restored image. Visual and quantitative results demonstrate that the proposed second-order PDE model is superior to other models in preserving edges and avoiding staircase effect for image restoration.

The fast Fourier transform (FFT) is a mostly used tool to measure power system harmonics. FFT, however, is not applicable to analyse interharmonics due to spectral leakage effect. Although International Electrotechnical Commission (IEC) standard is recommended for interharmonic measurement, the individual interharmonic frequency and respective amplitude cannot be worked out under this framework. For this reason, this paper proposes an enhanced-FFT model to build up the relationship between interharmonic frequency and dispersed leakage energy. The mathematical equation is thus established to find actual value of interharmonic frequency. Moreover, the true interharmonic amplitude can be retrieved from the dispersed energy collection. In other words, the sampling window length is no longer required to match the interharmonic period and the correct measurement results can be achieved. The proposed model is developed using a simple arithmetic equation so that it is feasible for more efficient calculation for interharmonic analysis. Performance results verify that the proposed scheme can achieve accurate, rapid and reliable outcomes.

In this study, a laser-assisted bending process is proposed, in which the external force is applied by magnets. The process can be used for bending the magnetic and non-magnetic materials. The experiments indicated that a large bend angle with reduced edge effect can be obtained by this process. The process was simulated by finite element method and a reasonable agreement was obtained between the experimental and simulated bend angles. It was experimentally observed that the micro-hardness after bending was greater than the original micro-hardness for mild steel as well as stainless steel work plates. In all the cases, micro-hardness reduced from laser-irradiated surface to opposite surface. Performance of the process as well as its ability to get accurately simulated bring out its potential of adaptability in industries.

As compared with the traditional boost converter, the three-level boost converter possesses several advantages, such as lower switch voltage stresses and lower inductor current ripple. To improve the efficiency, this paper proposes a zero voltage transition (ZVT) three-level boost converter. With the proposed ZVT circuit, the switches can achieve soft switching. Moreover, by using the voltage balance control, the output voltage can be equally across the output capacitors. In this study, the effectiveness of the proposed topology is verified by the experimental results based on the field-programmable gate array control.

Boost DC–DC converters are widely used in non-conventional power conversions namely in solar and wind power generation systems. It is also used in switched mode power supplies. Since there is no filter inductor on output side, output current of boost converter is pulsed and it is not desirable. The quality of power required is very high when DC–DC converters are employed for transferring the requisite amount of power. In this study, the conventional cuk converter (CCC) having a continuous current at both input and output sides is taken as the candidate for performance analysis. Accordingly an interleaved cuk converter (ICC) is proposed and designed to reduce the input current ripple and also to improve transient performances. Both the CCC and the proposed ICC are simulated and validated experimentally. The proposed converter is having better efficiency attributable to cancellation of source current ripple, reduction of ripple content in both output voltage and current, and improvement of transient performance.

Motion estimation is a basic issue for many computer vision tasks, such as human–computer interaction, motion objection detection and intelligent robot. In many practical scenes, the object movement goes with camera motion. Generally, motion descriptors directly based on optical flow are inaccurate and have low discrimination power. To this end, a novel motion correction method is proposed and a novel motion feature descriptor called the motion difference histogram (MDH) for recognising human action is proposed in this study. Motion estimation results are corrected by background motion estimation and MDH encodes the motion difference between the background and the objects. Experimental results on video shot with camera motion show that the proposed motion correction method is effective and the recognition accuracy of MDH is better than that of the state-of-the-art motion descriptor.

To improve the accuracy of torque control for vector control of interior permanent-magnet synchronous machine (IPMSM), this study proposes a torque-sensorless control method based on cascaded sliding mode observer (SMO). First, the active flux model is discussed, which converts the model of IPMSM into the equivalent model of surface-mounted permanent-magnet synchronous machine. Second, to reduce chattering caused by system parameters variations and external disturbances, the cascaded observer is designed, which is composed of a variable gain adaptive SMO and an active flux SMO. The variable gain adaptive SMO is designed to estimate the speed, rotor position and stator resistance in the d–q reference frame. The active flux SMO is designed to estimate the active flux and torque in the α–β reference frame. Global asymptotic stability of the observers is guaranteed by the Lyapunov stability analysis. Finally, simulations and experiments are carried out to verify the effectiveness of the proposed control scheme.

Underwater wireless power transfer (UWPT) is an important technique to power underwater devices while its frequency splitting phenomena are not fully elucidated. In this study, frequency splitting phenomena of a symmetrical planar two-coil wireless power transfer (WPT) system resonated at 90 kHz are investigated in seawater and freshwater. A concise frequency splitting analysis of this WPT system in air based on circuit model is given first and then experimental data are reported to show there is little difference between power transfer in air, freshwater and seawater in the range of 40–140 kHz of this WPT system. Consequently, the frequency splitting analysis and observations in air are also applicable in freshwater and seawater. It is found a V-type frequency splitting pattern exists in this WPT system under seawater and freshwater. Frequency shift is observed in this UWPT system in overcoupled region, and no frequency shift is observed in undercoupled region. In undercoupled region, in the low frequency zone of 40–90 kHz the load voltage characteristics in three media are identical; in the high-frequency zone of 90–140 kHz, the load voltage in air is slightly larger than those in freshwater and seawater.

A time-division polynomial (TDP) model is proposed for modelling and linearising a 1.5 T magnetic resonance imaging (MRI) power amplifier (PA) with strong non-linearity in high input signal dynamic range. In order to demonstrate the merit of this non-linear model, a 64 dBm 1.5 T MRI PA (63.89 MHz) and two different Sinc-pulse signals are used in modelling and linearisation measurements. The TDP is compared with the conventional non-memory polynomial (NMP) and no digital pre-distortion for the 1.5 T MRI PA, which is driven by test signal with 2 ms time length and 2% duty cycle. The proposed TDP leads to up to 9 dB improvement in the normalised mean square error compared with the NMP in two different test signals. More importantly, TDP illustrates significantly better reduction in amplitude modulation/amplitude modulation (AM/AM) and amplitude modulation/phase modulation (AM/PM) conversion compared with the NMP.

Quantum-dot cellular automata (QCA) is a new and promising computation paradigm, which can be a viable replacement for the complementary metal–oxide–semiconductor technology at nano-scale level. This technology provides a possible solution for improving the computation in various computational applications. Two QCA full adder architectures are presented and evaluated: a new and efficient 1-bit QCA full adder architecture and a 4-bit QCA ripple carry adder (RCA) architecture. The proposed architectures are simulated using QCADesigner tool version 2.0.1. These architectures are implemented with the coplanar crossover approach. The simulation results show that the proposed 1-bit QCA full adder and 4-bit QCA RCA architectures utilise 33 and 175 QCA cells, respectively. Our simulation results show that the proposed architectures outperform most results so far in the literature.

A method to engineer the peak-to-valley ratio (PVR) by design of the epitaxial layers is presented. The impact of Al content on PVR of InAs/AlSb/Al _x Ga_1−x Sb tunnelling diode is studied. A simplified analytical model is used to explain the PVRs dependence on Al content. It was found that PVR reaches its maximum when Al content x is zero with a quantised InAs layer. The peak positions appeared in the negative differential region are effectively controlled by the applied gate bias. A PVR ratio as high as 7.1 was achieved, which is beneficial for a wide range of circuit applications. Adjusting Al content provides a new way to engineer the PVR as opposed to the conventional way of being optimised by varying barrier thicknesses or doping levels.

A visible Q-switched pulse train at 639 nm was successfully generated in a Pr-doped double-clad structured waterproof fluoride glass fibre with a semiconductor saturable absorber mirror. The slope efficiency was calculated as 36.3%. The pulse duration and the radio frequency were measured as 270 ns and 107 kHz at 596 mW of absorbed power, respectively. The pulse energy and the pulse peak power were calculated as 1.32 μJ and 4.87 W, respectively.

In this study, a method for loss minimisation of six- and three-phase two-motor drive systems is presented. In two-motor drive systems (or multiphase multi-motor drive systems), currents of one motor pass through the other motor(s), which lead to increment of copper loss. In the proposed method for loss minimisation of six- and three-phase two-motor drive systems, extra copper loss of the six-phase motor, caused by reference currents of three-phase motor, is considered in loss-minimisation equations of three-phase motor; therefore the total controllable loss (including copper and iron losses) of whole system will be minimised in a unified form. In this paper, amount of efficiency improvement of proposed method for a system of two six- and three-phase motors in different speeds and load torques are compared with a conventional method of nominal flux. Also experimental results verify performance of the proposed method.