The key goal in designing a dual polarisation antenna array is to achieve a low cross-polarisation level. The cross-polarisation suppression method in dual linear polarisation phased array antenna is illustrated by using a dual linear penalisation probe-fed patch element. The array consists of a number of identical 2 × 2 element sub-arrays in which the H-port and V-port locations on each element are changed. A 2 × 2 element sub-array has been fabricated and the measurements and simulation results are provided to show the accuracy of this cross-polarisation suppression method. In addition, the co- and cross-polarisation patterns of the cylindrical array are presented.

A 165 mg coin-size bionic water-skating robot driven by piezoelectric (PZT) bending actuator is presented. The robot with light weight and elastic legs uses surface tension to keep itself on the water surface. The driving force produced by flapping wings enables it to glide easily due to tiny resistance coefficient of water surface. The robot consists of PZT bending actuator, four-bar transmission structure, two flapping wings, four elastic legs and the body. The actuator bending at resonance frequency of 105 Hz achieves 346 μm displacement at the end of actuator at voltage of 280 V so that the flapping angle of the wings reaches 73° at that frequency. Tests show that, the maximum equivalent payload of robot is 830.6 mg, about five times of its own mass, before breaking the water surface, and the water drag when robot skates on the water surface is about 29 μN, 1.76% of its gravity. The maximum forward speed of the robot is measured as 151 mm/s.

Some blind individuals have the ability to detect and classify objects in complex scenes by using echolocation based on ‘tongue clicks’. A waveform analysis of the tongue clicks collected from three blind individuals is presented who use tongue-click based echolocation on a daily basis. It is found that the tongue clicks are wideband signals and that that the spectrum of clicks varies within and between individuals. However, by using the wideband ambiguity function, it is found that all of the clicks from three different individuals share some common characteristics.

Artificial cognitive systems are increasingly drawn towards ‘human-like’ gestural exhibits while performing various manipulative acts. Representing such actions in a natural settings requires temporal extractions of their grasp progressions. A novel optimisation-based hidden Markov framework is offered, to generate natural hand prehensions through maximisation of a composite grasp function built of individual finger trajectory likelihoods. In order to produce the desired motion in an intuitive framework, the final grasp frame (represented in terms of standard discriminants z ∈ ℜ² in a condensed grasp eigen-space) is extended in a temporal sequence by equi-spaced increments of z, over their conventional joint-space representations.

Given an input object whose shape is partly similar to some of the samples in the training set, a dictionary-group-based sparse model is introduced that can use the local information of those less similar shape neighbours to represent the object and guide the segmentation. The model follows from a new sparse energy function that combines a series of sparse local constraints with the fuzzy log-polar decomposition-based shape elements. Finally, a unified framework is built to connect the high-level shape representation with the low-level image segmentation. The model on the public datasets is tested, and the experimental results show the superior shape segmentation capabilities of the proposed model.

The problem of enhancement of low light level images (LLLIs) with the characteristics of extremely low brightness and low contrast is addressed. A coarse-to-fine framework to settle the problem is proposed. First, a point-wise linear relationship is constructed between an LLLI and its enhancement result, and a prior named bright channel prior (BCP) is introduced to guide the enhancement process. The BCP to avoid over enhancement is improved, and the idea of matrix completion to remove the outlier noises in the enhanced image is used. Experimental results on real images demonstrate that the method is effective for the enhancement of LLLIs.

A scheme for low power consumption JPEG quantisation is introduced. Multiplications and additions are not required – only bit-shifting operations. A fully multiplierless JPEG-like image encoding framework is also proposed, using a discrete cosine transform approximation. Simulations demonstrate that the introduced quantisation scheme produces a very low image degradation. The proposed architecture is also physically realised in FPGA technology.

This study presents a modified classification and regression tree (M-CRT) framework based on difference expression images, to address the facial expression recognition (FER) problem. The authors firstly obtain facial expressional details by calculating the difference between the images of basic expressions and images of neutral expression, which reflect the information irrelevant to identities. Local binary patterns and supervised descent method are, respectively, used to obtain the global and local features from difference expression images. M-CRT model is developed for FER, which uses recursive segmentation to find the best classification decision according to the attributes of the global and local features, respectively. Compared with traditional methods, M-CRT can simultaneously maximise intra-class purity and distance between classes, which improves the discriminating power for classification. Experimental results on Japanese Female Facial Expression and CK+ database verify the effectiveness of their method.

The problem of quality assessment of screen content images from two respects is addressed, the edge-preserving filter based free energy and structural degradation model. For screen content images which always contain texts, edge information plays an important role in the process of evaluating the screen images quality. Inspired by this, the edge-preserving filter based free energy entropy and structural degradation model were combined to extract the quality features and accordingly the statistical model of screen content images was established. Experimental results prove that the proposed method can produce highly consistent with human perception, particularly superior to state-of-the-art full- and no-reference quality metrics on the SIQAD database dedicated to the quality assessment of screen images.

A fast joint sorting and reduction (FJSR) algorithm is proposed, which involves elementary column operations only, to assist the successive interference cancellation (SIC) detection for multiple-input multiple-output (MIMO) systems. Simulation results show that the FJSR-aided SIC detector achieves good error performance especially when the system scales up, yet requires only a few extra basis updates over the optimal-ordered SIC detector regardless of the system size. This suggests that FJSR is particularly advantageous to small-to-medium scale MIMO systems with strict delay constraints.

A new structure for a regenerative two-way relay (TWR) system, called a wired TWR (WTWR) system is introduced. The WTWR consists of two relay nodes that are connected through an optical link, and it operates as a single conventional TWR node. For the WTWR system, beamforming vectors maximising the sum rate of two source/destination nodes (i.e. users) are designed. The WTWR exploiting the proposed beamforming is applicable to various systems that can employ a TWR protocol, such as heterogeneous networks, distributed antenna systems, and coordinated multipoint transmission systems.

To resolve frequency ambiguity of tiered polyphase code (TPC), a differential encoding method to the secondary code of the TPC is proposed. By performing differential decoding, the frequency ambiguity is removed and the code sequence boundary is correctly found. In addition, the correlation results at the receiver can be used as a frequency offset estimator. Analysis on the receiver operations and the simulation results show that the proposed tiered differential-PC makes the code sequence boundary detection correctly under the frequency offset of up to several hundred hertz. The root mean squared error of the frequency offset estimation is reduced to <10 Hz under operating signal-to-noise power ratio which is about −35 dB.

The aim the present research is to develop a new approach for the localisation of faults in wiring networks based on adaptive neuro fuzzy inference system (ANFIS) and time domain reflectometry (TDR). In this approach a forward model has been developed and validated with measurements in order to generate a TDR response of any wiring network then the inverse problem is solved using ANFIS. The developed approach has been tested using a complex configuration that is YY-shaped network. The results show the efficiency and accuracy of the proposed approach.

In cloud data centre networks, virtual machine (VM) placement can be investigated to tackle traffic scalability issue. In this Letter, by taking advantage of data centre network architecture, the authors formulate the traffic scalability issue as a combinatorial optimisation model of online VM placement with multi-dimensional resource constraints. By leveraging Markov approximation technique, the optimum is efficiently obtained. Performance evaluation demonstrates that the proposed method achieves significant traffic scalability improvement over two common heuristics.

The erection of a substitution box based on linear fractional transformation applied on the subgroup of multiplicative part of Galois field GF(2⁸) is studied. The establishment of constrained linear fractional transformation on the elements of the subgroup is intricacy of the problem. The robustness of the proposed substitution box against renowned algebraic and statistical attacks is gauged to enumerate its confusion creating ability. The analysis is accomplished by finding non-linearity, approximation probabilities and strict avalanche criterion. The majority logic criterion is employed to guesstimate the efficacy of substitution box in image encryption applications.

A dynamic deviation memory polynomial (DDMP) model for digital predistortion is proposed to compensate the non-linear distortion of the power amplifier. It is based on the memory polynomial model and dynamic deviation reduction-based Volterra (DDRV) model. Compared to the DDRV model, the proposed model shows better modelling accuracy under the same complexity. The effectiveness of the DDMP model has been verified by simulation and experiment results.

A microstrip lowpass filter (LPF) with ultra-wide stopband suppression and compact size based on dual-plane structure is presented. The LPF is composed of high-impedance resonators loaded by folded patches on the topside plane, combined with hybrid slot and step-impedance resonators on the ground plane. Multiple transmission zeros are created in the stopband region by different resonators. Thus, an ultra-wide stopband with 11th-harmonic suppression is achieved. A demonstration filter with 3 dB cutoff frequency (f _c) at 2.45 GHz has been designed, fabricated and measured. Results show that the relative stopband bandwidth is 163.8% with attenuation level of 20 dB. The insertion loss is lower than 0.3 dB and the return loss is better than 17 dB in the passband. The size of the LPF is only 8.90 mm × 8.93 mm, which corresponds to 0.115λ _g × 0.116λ _g (λ _g is the guided wavelength at f _c).

A coplanar waveguide (CPW)-to-stripline (SL) via-based signal transition operating from DC to 150 GHz is presented. The signal transition is manufactured using low-temperature co-fired ceramic (LTCC) technology and it is the largest-bandwidth LTCC vertical signal transition published to date, according to the best of the authors’ knowledge. Probe-based S-parameter measurements of the transition show that the single-ended CPW-to-SL signal transition has below 1 dB insertion loss for frequencies up to 150 GHz, thereby demonstrating it as a suitable component for realisation of a low-cost, fully integrated, surface-mountable millimetre-wave system-in-package.

A novel substrate integrated waveguide (SIW) 3 dB directional coupler based on air-filled vias (AFVs) is proposed and experimentally validated at Ka band. The AFV units can be used for tuning the effective permittivity by adjusting the dimensions of vias and period. Two rows of optimised AFVs are inserted in each branch of SIW directional coupler to cut off TE₃₀ mode and achieve 3 dB coupling with 90° phase difference. A 90° phase shifter is designed based on the AFVs as well and the quarter wavelength impedance transformer is introduced. Finally, a 3 dB directional coupler prototype with 180° phase difference was designed and fabricated. The experimental results show that about 11.43% fractional bandwidth is obtained with a return loss of input port better than 19 dB, power equality within ±0.33 dB, isolation better than 25 dB and phase differences within 180° ± 10°. The agreements between simulations and measurements validate the design and it is a good candidate for millimetre-wave applications.

A packaged optical comb source is demonstrated. A low-linewidth optical comb source is designed and fabricated. The device is packaged in a seven-pin high-speed butterfly package with an subminiature version A (SMA) connector for RF modulation and fibre pigtail. Fibre coupling efficiency is estimated at 43%. The packaged comb source is shown to have a linewidth of 300 kHz for the comb line set when modulated at 4 GHz, with eight comb lines within 3 dB of each other. The prototype packaged comb source has applications in high bandwidth telecommunications.

The wireless power transfer (WPT) transmitter (Tx) coil and near field communication (NFC) Tx coil are combined in one transmitter. The coil system consists of an NFC Tx coil and a WPT coil system that includes an A4WP Tx coil and an A4WP receiver (Rx) coil. The WPT coil system uses a magnetic resonance method. A4WP coils are tuned to resonate at 6.78 MHz. The NFC Tx coil is tuned to resonate at 13.56 MHz and positioned between the A4WP Tx and Rx coils. Moving the position of NFC Tx coil near the A4WP Tx coil, interference phenomena among coils are investigated and changes of WPT efficiencies are measured. Optimal placements of the NFC Tx coil that minimise the loss of WPT efficiency are determined based on the analysis data.

Transient interference cancellation is necessary for high-frequency sky-wave radar and usually requires accurate interference detection and localisation which is complicated due to the non-uniform noise level caused by sea-clutter mitigation in Doppler domain. A novel approach is proposed by converting the detection of interference into a problem of straight line extraction in the constructed fast- and slow-time images. The line edges are detected by an edge detector, such as Canny method, followed by Hough transform. Then, each edge is classified as a rising, falling or false-alarm edge based on multi-threshold segmentation of image sub-blocks. Experimental results demonstrate the effectiveness of the proposed approach.

A robust transmit beampattern matching synthesis approach is described for a multiple-input and multiple-output radar with manifold vectors perturbation. This synthesis technique minimises the worst-case matching performance between the transmit beampattern and the desired beampattern (in a least absolute deviations sense), through designing the waveform covariance matrix. Also, the resulting minimax problem can be translated into a convex problem is showed. Finally, simulation results verify good performance of the proposed robust transmit beampattern synthesis approach.

A tunnel field-effect transistor (TFET)-based pixel circuit for well capacity adjustment that does not require subthreshold operation on the part of the reset transistor is presented. In CMOS, this subthreshold operation leads to temporal noise, distortion and fixed pattern noise, becoming a primary limiting performance factor. In the proposed circuit, the asymmetric conduction associated with TFETs is exploited. This property, arising from the inherent physical structure of the device, provides the selective well adjustments during photo-integration which are demanded for achieving high dynamic range. A GaN-based heterojunction TFET has been designed according to the specific requirements for this application.

A compact dual-mode dual-band bandpass filter is proposed based on the inside–outside–reversed dual-ring topology. Different from the traditional design, the total size of the filter is limited by the second passband with shorter wavelength at higher frequency, instead of the first passband with longer wavelength at lower frequency. By loading four square patches in the inner ring, the degenerate modes of the inner ring move down and form the first passband, whereas the second passband is constructed by the outer ring. By utilising the coplanar-waveguide feeding at ground plane, a prototype of the dual-band filter with two operating frequencies at 0.92 and 1.47 GHz is designed and verified experimentally.

Non-orthogonal multiple access (NOMA) is a candidate technology for the 5th generation cellular networks to reduce the big gap between network capacity and fast growing traffic. It applies superposition coding in transmitters and successive interference cancellation at the receivers to cancel intra-cell interference. The same frequency resource can be allocated simultaneously to multiple intra-cell users, holding large potentials on improving network performance. A major technical challenge of NOMA is on user pairing and power allocation (UPPA). Most of existing UPPA algorithms are based on exhaustive search with extensive computation. A new algorithm, which has the lowest computation complexity achievable for NOMA UPPA is proposed. The main idea is to pair the first users having the highest proportional fairness priority coefficient with potential second users having the highest channel conditions. A fixed power allocation strategy is adopted. The proposed algorithm is significantly faster than existing algorithms without sacrificing NOMA throughput gain.

A novel, non-coherent bit-level detection scheme is proposed to compensate for the frequency offset efficiently in IEEE 802.15.4 binary phase shift keying (BPSK) receivers. In the proposed scheme, the frequency-offset estimation process only requires comparison, division, and addition operations. The proposed scheme first creates a suitable estimation-region division, thus the mathematical approximation tan⁻¹(x) ≈ x is efficiently utilised to simplify the conventional optimal estimation. The frequency offset and signal-to-noise ratio conditions do not need a priori knowledge. Simulations demonstrate that the proposed scheme is as reliable as the conventional optimal algorithm, but with a significant reduction of complexity.

To enable efficient and accurate secure localisation in wireless sensor networks, a sparsity-incorporated localisation algorithm is proposed. Unlike most of the existing schemes, the localisation problem is solved in an L1 minimisation framework which is based on the attack sparsity and the linearisation of a distance measurement model including the bogus data from malicious anchors. The localisation errors, speed and detection rates of the scheme are analysed in the simulations. Results demonstrate that the method can simultaneously achieve target localisation and malicious anchor identification in an efficient and accurate way.

In the Tx timesharing for universal mobile telecommunications system (UMTS) and global system for mobile communications 1Tx-2Rx dual-SIM dual-active (DSDA) scenario, UMTS UMTS enhanced uplink (EUL) had performance degradation due to discontinuous transmission. Therefore, the code rate-based mitigation scheme was evaluated to reduce the performance degradation. Even though this scheme had significant gain, high complexity implementation was required. Thus, the boost power-based mitigation scheme is proposed and analysed from the throughput improvement and implementation complexity point of view.