A novel compact monopole antenna with wide circularly polarised (CP) bandwidth is designed, fabricated and measured. The wide impedance bandwidth and broadband CP characteristic are achieved based on a simple tilted monopole structure, which consists of a slotted rectangular patch and an improved ground plane. The measured impedance bandwidth with return loss better than 10 dB is 97.4% (1.10–3.19 GHz), the measured 3 dB axial-ratio bandwidth is 59.1% (1.11–2.04 GHz) and the measured peak gain within the operating band is 4.84 dBic, which indicates that it is a good candidate for the application of various global navigation satellite systems.

A low-noise inducing receiver (Rx) for human body communication is proposed. By minimising switching noise from the digital circuit of the Rx and coupling of the signal to the Rx ground, stable and reliable communication was accomplished even when the transmitter (Tx) and the Rx were attached to the human body. A prototype Tx and Rx were implemented with a PCB size of 5 × 6 cm. They were tested with this low-noise inducing Rx design and accomplished a data rate of 1 Mbits/s without any cyclic redundancy check (CRC) error.

With the help of proposed translinear circuit, intrinsic temperature coefficient of logarithmic converter is compensated by that of a proportional-to-absolute-temperature current source in bandgap reference, which contributes to the proposed fully integrated logarithmic converter. Using a 0.13 μm CMOS technology with 1.2 V single supply, the proposed logarithmic converter exhibits less than 350 ppm temperature coefficient with a 0.5–1.2 V input range.

The pinched hysteresis loops drawn in the voltage–current, voltage–charge, and flux–current characteristics belong to well-known fingerprints of the memory elements known as the memristor, memcapacitor, and meminductor. It is shown that generating such loops is in fact a natural attribute of all nonlinear elements from Chua's table, and that the hysteresis need not necessarily be a manifestation of the internal memory of the element. A generalised homothety theorem is introduced, which describes the regularities of such a hysteresis and its frequency dependence.

Two-step injection clock generation technique is presented for fine resolution fractional-N multiplying delay-locked loop (MDLL). The coarse DLL generates multiple coarse clock phases, and then fine DLL performs fine phase control for MDLL injection clock. The proposed technique is applied to fractional-N MDLL and efficiently achieves 8b fractional frequency resolution. The MDLL designed in a 0.18 μm CMOS process occupies 0.065 mm² and generates 10 MHz frequency with 61 μW power consumption.

Tendon-driven flexible manipulators have diverse applications. However, kinematic errors are one of main sources of the positioning inaccuracy for the manipulators. An interval-analysis-based approach is applied to evaluate the positioning performance by imposing bounds on the kinematic parameters and control input. Simulation results confirm that the calculated intervals and refined bounds fully enclose the tip positions.

Starting from the electric field integral equation (EFIE), it is shown how, for quasi-static cloaking (i.e. zero scattered fields), the EFIE can be reduced to classical Kirchhoff's current law (KCL). The KCL, if considered according to all-dielectric or metal-dielectric structures, is demonstrated to realise devices based on plasmonic or mantle cloaking, respectively. The KCL generalises scattering cancellation theory for arbitrary shape devices in homogeneous backgrounds and it can be extended as a local cloaking condition beyond quasi-static regime. A cloaking device can be seen as a node (i.e. no current source or sink) that ensures all current densities to be compensated even for more complicated low scattering devices.

A direct and analytical algorithm for pose estimation of single space circle in the context of monocular machine vision is proposed. Circular feature with detected centre in the image is used to find two special diameters, one is primarily found for estimating the location of space circle, the other is for estimating the normal vector. The proposed algorithm formulates the problem with solving equations instead of matrix transformation; by solving the equations efficiently, it obtains the single-valued true solution automatic without choosing the process. Experiments on real images prove that the proposed algorithm can achieve high accuracy. Automatic, efficiency and accuracy together make the proposed algorithm applicable especially in real-time system.

A novel method called modality-independent Kernel discriminant analysis joint sparse auto-encoder, for solving heterogeneous face recognition problem is proposed. A projection matrix to map multimodal data into a common feature space for representing cross-modal image data is first learnt. Then extend the model via sparse auto-encoder in an unsupervised manner with the combination of a regularisation term and a Kullback–Leiber divergence term. Different from classical approaches, this model does not require the data correspondences when collecting external cross-modal data. Thus, it is practical for real-world cross-modal classification problem. Experiments conducted on two heterogeneous face datasets demonstrate the effectiveness of the proposed approach.

This Letter introduces a novel framework for blind blur assessment in colour images using higher order singular values. The RGB colour image is seen as a third-order tensor to exploit the spatial and inter-channel correlations, so that blurring effects are captured more robustly. The tensor is decomposed into different two-dimensional matrices, also called unfoldings. The conventional singular value decomposition is carried out for these unfoldings instead of computing it for the luminance component alone. The experiments were performed on several publicly available databases and the results validate the superiority of the proposed metric among different state-of-the-art blind blur assessment metrics. The proposed framework for image quality assessment (IQA) from colour images fits well with the current trends and research efforts put in enhancing the quality of experience for different multimedia applications and in benchmarking new imaging and sensing technologies including camera and other vision systems with IQA capabilities.

Wrapper-based methodology for attribute selection is achieved by employing ‘support vector machine (SVM)’ and ‘binary flower pollination algorithm (BFPA)’. A greedy crossover is proposed to reset the suboptimal solution obtained on pre-mature convergence. Also, ‘one to all’ initialisation is developed to devise the initial pollen population for diversified exploration. The proposed methodologies are validated with datasets from uc irvine (UCI) repository and results show superior performance on comparison with the literature on both ‘BFPA’ and other metaheuristic algorithms for attribute selection.

An analytical model is developed for the average packet delay for Dual-Mode Energy Efficient Ethernet to complement the power consumption model for Dual-Mode EEE developed previously. The model can be used for determining the tradeoff between power reduction and performance degradation caused by utilising the method. The analytical mode's results closely match the results from simulation.

A novel automatic modulation classification algorithm named cumulant-based maximum likelihood classification (CMLC) is proposed for overlapped sources. The sample estimate of cumulant is utilised for classification and classification decision is made by maximising the asymptotic distribution function of the cumulant. Simulation results prove the superior performance of CMLC over existing algorithms.

The Taylor–Fourier transform (TFT) is suitable to analyse the spectrum of signals with non-stationary harmonics. It can be considered as an FIR filter bank consisting of maximally flat (MF) high-order filters which are computationally extensive and difficult for implementation. An adapted method is proposed for the TFT harmonic analysis which is based on the previously proposed multiple-resonator observer structure. The MF conditions are imposed to reshape frequency responses. This method by using a parallel structure with common feedback is very robust and, in addition, allows a reduction of the computational burden. Besides, this estimation method is adaptive and convenient for application in case of large frequency excursions, since the closed-form solutions allow that the fundamental frequency fluctuations can be followed by the filter central passband frequency.

Rate region precisely measures the transmission ability of a network. Three graph processing techniques are presented: reduced graph, union reduced graph, and virtual node. Applying these techniques, an operable method to completely solve the calculation of rate regions for unicast routing networks is developed. The correctness of the method is proved theoretically and illustrated with an example. This method is helpful in both theoretical perspective and industrial implementation.

A method for autonomous segmentation of motion primitives from continuous observation of goal-directed behaviours is proposed. In the proposed method, the iterative patterns of the observed behaviours, which are viewed as motion primitives, are segmented using a stochastic topology preserving map (TPM). The stochastic TPM, which is derived from a combination of self-organising map and Gaussian mixture, provides substantial capabilities for unsupervised learning and clustering of high-dimensional data sequences. The results of experiments conducted, in which the proposed method was applied to a dataset of daily activities captured using a Kinect, verify that the proposed method is reliable.

Backbones of a propositional theory are those literals, whose assignments are always true in every satisfying assignment, and have been applied for characterising the hardness of decision and optimisation problems. A new strategy called variable quality checking (VQC) is proposed for backbone computation. The VQC strategy to check the variable quality is used to obtain from the level information of variables when a Davis-Putnam-Logemann-Loveland-based satisfiablity problem solver returns satisfiable, and then decide which variable is the next variable to be computed, i.e. to select the most likely or unlikely backbone variable, whereas the previous algorithms randomly select a variable to compute. Furthermore, we use the VQC strategy to improve an efficient backbone algorithm called OTPV (one test per variable) and design a new algorithm for backbone computation, called BVQC (backbone with the VQC). The VQC strategy can also improve the performance of state-of-the-art backbone algorithm core-based with chunking, which calls OTPV to test whether the remaining literals are in the backbone or not. Experimental results show that BVQC significantly outperforms OTPV and gains a 1.30 times on average speed-up, even up to one order of magnitude for some instances.

A flow measurement method based on fringing field capacitors is proposed. Alternate annular electrodes are fabricated on the surface of the tube to constitute the capacitor structure, and the fringing field penetrates the wall to achieve the detection of fluid. The electric field between two electrodes distributes along the annular wall, which is conducive to analyse the relationship of the capacitance and the flow. The proposed measurement method is suitable for the industrial applications due to the simple structure and low cost. A water flow measurement experiment was implemented by making foil capacitor on the surface of a plastic tube.

Multiple off-the-shelf test-fixtures are available to interface a device-under-test (DUT) to an impedance analyser to characterise its electrical properties. The impact of three available fixtures on the measured impedance of a low-resistance, low-inductance DUT requiring high-frequency (≥100 MHz) characterisation are compared with a custom fixture. The custom fixture is shown to provide a higher accuracy than the off-the-shelf fixtures, highlighting that low-resistance, low-inductance devices require carefully constructed fixtures for characterisation. The experimental results collected using the fixtures are validated against a finite-element-analysis model of the DUT.

Spin transfer torque based magnetic tunnel junction (STT-MTJ) is under intense investigation for the design of hybrid spintronics/CMOS circuits. A novel non-volatile magnetic decoder (MD) based on MTJs is presented. Its output data is stored into a pair of MTJs in non-volatile state. The proposed MD promises area efficiency by sharing the same sense amplifier for normal CMOS-based dynamic decoder mode and non-volatile data sensing mode. Moreover, the symmetric structure largely weakens the impact of sneak current and ensures reliable sensing. By using a compact STT-MTJ model and the STMicroelectronics CMOS 28 nm design kit for CMOS counterparts, transient and Monte Carlo simulations are performed to validate its functionality and evaluate its performance merits.

A compact microstrip patch annular array is proposed to excite the TE01 (TE, transverse electric) high-order mode in circular waveguide. This annular array is composed of four microstrip patches which are laid and fed rotationally. The electromagnetic simulation software, high-frequency structure simulator is used to model the electric field radiated by the annular array. It is found that the electric field is turbulent and according to the performance of the TE01 mode. A wireless transmitting and receiving experiment is carried out in a long steel hollow pipe to prove the existence of the TE01 mode. In this experiment, the transmit–receive antenna is selected as the proposed annular array and dipole antenna. It is shown that the transmission loss of the annular array is much less than the dipole.

A high selective inline substrate integrated waveguide (SIW) filter based on novel stepped-impedance non-resonating node (NRN) is presented. The stepped-impedance NRN is realised by inserting a stepped-impedance substrate integrated coaxial line resonator into the volume of a third-order SIW filter. It introduces extra signal transmission path between source and load. Thus, one more transmission zero (TZ) is produced compared with conventional NRN that further improves the selectivity of the filter. Also, the proposed filter achieves a compact circuit size as the stepped-impedance NRN is embedded in the SIW cavity without occupying extra layout. To validate the proposed concept, a prototype filter with two TZs locating at both the lower and upper stop-bands, is designed, fabricated and measured. The measured results are well consistent with the simulation ones.

A novel compact filtering rat-race hybrid coupler with improved upper stopband is presented. Four coupled λ/2-resonator pairs are utilised to replace the λ/4- and 3λ/4-transmission lines in the conventional hybrid. Each coupled λ/2-resonator pair exhibits a bandpass filtering response and acts as a K-inverter. Eight resistors are placed at the centre of the λ/2-resonators to suppress the second-harmonic. For verification, a filtering rat-race hybrid is implemented with a centre frequency of 1.27 GHz and 20 dB rejection band of 2.73 f ₀. Good in-phase and out-of-phase characteristics are obtained. The proposed device has a simple circuit topology, compact size and good performance.

The impedance space of inverse class-FJ mode power amplifiers (PAs) is extended by introducing a resistive part into the voltage waveform. Unlike traditional inverse class-FJ mode, the new continuous inverse class-FJ possesses a complex fundamental and third-harmonic terminals. For validating the theory, a broadband PA working across 1.6–2.7 GHz is designed. The experimental results show a drain efficiency of 69–84.9% in the whole working band. The measured output power of the fabricated PA is 40.1–42.5 dBm with a gain of 10.6–12.5 dB across 1.6–2.7 GHz.

A dual-band 90° unit module with harmonic suppression (HS) is proposed. This unit module consists of a pair of back-to-back stepped impedance sections and an open stub. The unit module is realised by synthetic transmission lines, and it is successfully implemented into a novel miniature dual-band (2.45/5.8-GHz) rat-race coupler with HS (suppression level ≥16 dB, 6.8–13 GHz). Compared with traditional 1.5λ microstrip ring hybrid, the proposed dual-band rat-race with HS only occupies 13.84% of its area.

The design of a split ring resonator bandpass filter is reported. The design is based on coupling coefficient filter and the novelty of the proposed design is possibility to miniaturise the structure by including a new kind of dielectric resonator fabricated with a commercial high dielectric constant epoxy paste. Equivalent circuit model is discussed, establishing a clear relation between each component and physical parameter of the proposed design. Excellent agreement between electromagnetic simulation and measured of band pass filter at 1.65 GHz is found.

Static random-access memory (SRAM) based memories are widely used in electronic systems and if their contents change due to external reasons, the electronic system can functionally fail. One of the external reasons is the radiation induced soft errors as the SRAM memories are susceptible to radiation effects. Majority of the recently proposed methods use error correction codes (ECC) to mitigate soft errors. Error correction/detection capabilities of such methods are at most 3 bits in a codeword which will be insufficient while number of memory bits affected by a radiation particle is increased, as CMOS process technology shrinks towards around 5 nm. Since memory bits affected by a radiation particle are physically close, adjacent error detection/correction becomes a hot research topic. In this Letter, Euclidean geometry-low density parity check code, more capable ECC than Hamming code used in recent works, is explored in context of adjacent error detection performance. The results show that proposed method successfully detects up to 14-bit adjacent errors in a 15-bit codeword. As such, this method is suitable where high detection performance is needed. The proposed method is also simplified for efficient hardware implementation while detection performance is not sacrificed. Both methods are compared in terms of resource usage.

Periodic silver nanorods array have been used to improve the hole injection and the electroluminescence of organic LEDs (OLED). The nanorods have been fabricated on the indium tin oxide anode by electron beam lithography technique with a precise control of the nanoparticles parameters. The μ-OLEDs fabricated on top of the nanorods show higher-current density and lower turn-on voltages in comparison with the reference device. Moreover, the results emphasise the existence of the localised surface plasmon resonance enhancement effect as well as an important improvement of the hole injection from the anode.

The local optima escaping ability, which is critical for both accuracy and efficiency of CMOS-type Ising chips, is greatly affected by the probability to accept a worse state. Theoretically, such probability is determined by both energy barriers and temperature. However, due to the implementation complexity, the energy barrier is not considered in existing CMOS-type Ising chips. We propose a double random source based method, which re-correlates the probability above with the energy barrier, while eliminating calculating the energy barrier for low cost is proposed. The experiments demonstrate that the method can improve the accuracy of CMOS-type Ising chips by 7.6%, confining the error within 1%. Moreover, it can accelerate the convergence process by 100×.

A gallium antimonide-based semiconductor disk laser (SDL) emitting 17 W of continuous wave output power at a heat sink temperature of 20°C and an emission wavelength of 2.02 μm are presented. This high-output power is achieved by optimising the thermal management and reducing the quantum deficit of the SDL structure.

Two-level three phase rectifiers are widely used in industrial applications due to their superior performance. Their reliability has attracted lots of attention in recent decades. Transistor is one of the most fragile component because they suffer from voltage surge and thermic cycling. A fault diagnosis method based on current kernel density estimation for transistor open-circuit faults is proposed. The proposed method needs no extra sensors and it includes three steps: current kernel density estimation, Euclidean distance, fault detection and isolation. Experimental results show the proposed diagnosis method is highly efficient in single open-circuit fault and multiple open-circuit fault on the same leg.

An isolated fully soft-switching single-stage three-level power amplifier (SS3L) based on dual auxiliary networks (DAN) is proposed in this Letter. Compared with the conventional class-D power amplifier, the proposed DAN-SS3L achieves high level of integration without bulky dc link capacitor, and high-efficiency by single-stage conversion and zero voltage switching for all the switches under different operating conditions from light load to full load, which is suitable for high-voltage audio distribution systems. By adopting active auxiliary network, the energy stored in the leakage inductor can be recycled, which eliminates the pulse width modulation voltage spikes. The passive auxiliary network provides enough reactive current for primary-side switches, extending soft-switching range. In addition, commutation overlap strategy is employed to enable natural commutation of bidirectional switches. Experimental results of a 200 W prototype are presented to verify the analysis results.

Reducing circuit supply voltage to near-threshold (NT) region is an effective technique for achieving better energy efficiency in current ultra-low power circuit design. However, circuit variation problem becomes extremely worse in NT region and requires more design margin. Error detection and correction (EDAC) designs can remove circuit margin by solving transient error dynamically, but many of the traditional EDAC designs cause large area overhead and cycle per instruction (CPI) penalty. A compact timing error mask flip-flop (EMFF) based on error masking with ultra-low overhead by only adding six transistors (four for error detection and two for error correction) to the conventional flip-flop with 0 CPI penalty is presented. The proposed EMFF reduces system area overhead significantly. Therefore, the timing error tolerance ability is expanded and higher energy efficiency can be archived. EMFF is realised in an industrial processor in SMIC 40 nm CMOS with only 6.8% area overhead, compared with the original processor. At 0.5 V, the EMFF system gains 18.6% performance increasing than the most compact previous work with 3% higher efficiency.

The lack of transmission antenna gain in passive coherent location (PCL) systems can be circumvented somewhat by the fact that most broadcast waveforms are continuous waveforms and that the lengthening of the integration time can help to increase signal energy. However, with the increase of integration time, a PCL system encounters some limitations in detecting manoeuvring targets. To investigate this, the uniformly most powerful invariant (UMPI) detector presented by Zaimbashi et al. is considered. The detection performance of the UMPI detector in a closed-form expression for a manoeuvring target is obtained. The theoretical findings accompanied by simulation results demonstrate that a manoeuvring target can seriously degrade the detection performance of the UMPI detector when using long integration times.

The measurement performance of the dual-frequency correlation radar altimetry for the estimation of the sea wave heights is not as accurate in satellite as in airborne platform. Multi-frequency sensing signals can be applied to obtain sea surface state information while maintaining sensitivity over wide range of sea wave turbulences from space. The proposed method uses a sensing signal with angle modulation with optimum modulation index of m = 4.5, which enables to obtain a spectrum from 11 harmonics, instead of generating 11 frequency transmit signals for spaceborne multi-frequency radar altimetry. Maximum sensitivity of the measurement to the root-mean-square of the sea wave heights was obtained for the optimal frequency gaps between transmit signals.

By applying digital beam-forming (DBF) technique, the along-track multi-channel synthetic aperture radar (SAR) system can simultaneously achieve high-resolution and wide-swath (HRWS) imaging. However, the presence of unavoidable phase biases tends to degrade the DBF performance. To address this issue, a novel phase bias estimation algorithm based on Doppler spectrum optimisation is proposed. By exploiting the fact that phase bias would cause Doppler spectrum broadened, the phase biases can be successfully estimated by maximising a sharpness optimisation of the Doppler spectrum. The effectiveness of the algorithm is validated by experimental result carried out on the SAR data collected by an air-borne multi-channel system.

An image segmentation method is proposed based on exploiting the spatial patterns in synthetic aperture radar (SAR) images. First, a similarity map is constructed for evaluating the similarity between the spatial pattern of the SAR image and the reference clutter images. Then, a segmentation threshold is selected based on the similarity map. Finally, image segmentation is achieved by preserving pixels that have larger similarity values. The superiority of the proposed method is verified by the experimental results for high-resolution SAR images.

This Letter presents a new method for radar cross-section reduction (RCSR) of patch antenna in the case of glancing incidence (θ ≥ 70°). The reduction is realised by using frequency selective absorber which consists of lumped capacitance, inductance and resistance. Series inductances and capacitances act as frequency selectors and lumped resistances act as absorbers. By controlling the value of LRC, the circuit can only absorb the power of induced current generated by plane wave without affecting the radiation current. Considering the distribution effect of antenna, the number and position of LRC circuit must be carefully selected. Simulated and measured results show that in the case of glancing incidence, the RCS of antenna can be reduced in the angular range of −180° ≤ φ ≤ + 180° from 8 to 18 GHz. The average reduction of RCS is more than 15 dB and the maximum reduction is as far as 30 dB. Meanwhile, the gain of antenna can be well maintained.

Harmonic resistive multipliers that exploit the unique current–voltage (I–V) characteristics of Ag/Ge–(Sb)–Te/Pt resistive-switching devices are demonstrated. For a Ge₁₇Sb₂₉Te₅₄-based device, an antisymmetric non-linear I–V curve with a hump-like structure at ±0.4 V is obtained, whereas for a Ge₅₁Te₄₉-based device, an asymmetric non-linear I–V curve with SET switching at +0.4 V and RESET switching at –0.1 V is observed. The Ge₁₇Sb₂₉Te₅₄-based device performs third harmonic multiplication for a 160 MHz input at 0 dBm, and sixth harmonic multiplication at 5 dBm under unbiased conditions without any matching circuit. For the latter device, biasing at a voltage of ±0.4 V leads to fifth harmonic multiplication, which is absent for a 0 dBm input under unbiased conditions. No harmonic multiplication is observed for an unbiased Ge₅₁Te₄₉-based device due to its high resistance, but biasing at the switching voltage of 0.4 V leads to fourth harmonic multiplication for a 0 dBm input. The unique non-linear characteristics of these devices suggest their potential for radio frequency applications.

A novel device technology has been developed to enable the fabrication of high performance mm-wave GaN high electron mobility transistors (HEMTs) for solid-state power amplifiers operating in W-band. By utilising the reverse polarisation of N-polar GaN, an in-situ GaN cap layer added in the device access regions acts to improve the channel conductivity and reduces the impact of surface states on device performance. A low dispersion HEMT with 149 GHz peak f _T and 285 GHz peak f _max demonstrated simultaneous high efficiency and output power density with 34.2% peak power-added efficiency and an associated 2.5 W/mm output power at 87 GHz.

The implementation of on-chip inductors in integrated circuit application remains a challenge to satisfy the requirements of high Q-factor, small area consumption, limited parasitic coupling, ease of layout, and manufacture. Fortunately, the emerging technology of through-silicon via (TSV) offers a possible solution to this issue by developing 3D inductor with solenoid architecture. A simple and accurate inductance model of 3D inductor based on TSV is exploited by analytical method. The inductance results obtained from the proposed model and finite element method exhibit good agreement with various design parameter ranges, and the errors between the results of the proposed analytical model and measurement are <7.5%, which verifies the accuracy of the model.

Directional-discontinuous reception (D-DRX) is proposed for millimetre-wave enabled fifth-generation communications. In addition to conventional active, short-sleep and long-sleep states, the proposed mechanism considers a separate beam searching state, to address alignment of directional beams between user equipment (UE) and evolved node B after a sleep cycle. Semi-Markov process is explored to capture various states of UE and probabilistically estimate its power saving and delay. A numerical analysis is conducted to validate the performance of D-DRX proposal. About 10% improvement is achieved in power saving with a marginal decrease in delay compared with maximum possible beam search time.