The high cost of the powered prosthetic leg is one of the challenges for the lower-limb amputees in developing countries. This Letter presents a robust design and simplified control strategy for a cost-effective magnetorheological-damper-based prosthetic leg for transfemoral amputees. Herein, a simple sensing technique having an accelerometer and two force-sensing resistors is incorporated to obtain the gait events. Based on gait phase detection, a simplified if-else rule-based control strategy is implemented. A comparison between angles of prosthetic and intact knee is presented to demonstrate the effectiveness of the proposed design.

An embedded micro-deep hole drilling force measurement system is proposed and verified experimentally, it is based on resistance strain gauge, weak signal detection method and embedded technology. The system can measure the thrust force, tangential force and two orthogonal components of radial force precisely, continuously and stably in real time, while other similar systems can measure only thrust force usually. The system can replace the complex modelling of drilling process to obtain random changing details of drilling forces, and can also be used effectively in intelligent drilling control research.

A shaping technique is proposed to remedy the attenuation-factor error in the split capacitor-digital-to-analogue converter (CDAC) of a successive-approximation-register (SAR) ADC. By feeding back the previous quantised value of the least significant bit part to the most significant bit part, the inaccurate attenuation-factor error caused by mismatches and parasitic components is shaped to high frequency. The in-band dynamic performance is significantly improved without any calibration. Simulation results show that the proposed attenuation-factor shaping technique improves the spurious-free-dynamic-range by 10 dB, whereas the number of capacitors increases only 1.2%.

The pseudo resistor (PR) is widely used in integrated circuits. It comprises two transistors back-to-back to force them into the sub-threshold region, which provides large resistance with a small die area. However, its linearity is limited by the non-linear MOS transistors in weak inversion. In this Letter, a new PR topology is proposed, employing a feedback loop that continuously adjusts the voltage at the shared gate node of the PR with the input signal. The proposed architecture substantially increases the linearity and impedance of the PR.

The increasing demand for electricity has led humans to a growing exposure to artificial sources of electromagnetic emission, making it essential to determine the intensity of electromagnetic fields (EMFs), which is subject to the population of a given area. This Letter proposes an analysis of EMF exposure levels and spatial distribution over the region of the input and power circuits of a 230 kV/60 Hz air-insulated substation. For this, measurement protocols were determined based on current standards and from spatial interpolation methods, a contour map was developed, allowing a complete evaluation of the behaviour and levels of EMF throughout the region. The results obtained indicate that exposure levels in this region are below those recommended by regulatory agencies.

A fourth-order finite-difference time-domain (FDTD) scheme is proposed for the solution of Maxwell's equations in cold plasma (Drude medium), based on the multistage method of Jameson, Schmidt and Turkel, which was originally introduced in the framework of fluid dynamics. First, the system of governing differential equations is formed as a general first-order, operator-based approach, and then a four-stage algorithm is established. The accuracy of the method is verified in benchmark problems compared with analytical solutions and with the conventional second-order FDTD algorithm.

The authors present a model where object segmentation and recognition are connected with a bottom-up inference and a top-down generation pathway so that the two models can communicate and cooperate with each other. They are integrated into an energy function and optimised at the same time. To achieve the cooperation, objects are modelled in two aspects: shape and appearance, so that the recognition result could feedback to the segmentation process. Restricted Boltzmann machine is employed to learn the shapes of the objects with corresponding labels and perform object recognition based on the object shapes. Another pathway involved with the appearance knowledge of the objects is also established so that both the shape and appearance information will guide and constrain the evolution of the segmentation developing towards the region of interest, which will further facilitate the performances of both tasks. Experiments demonstrate the effectiveness of the proposed model.

This Letter presents a balanced-to-single-ended (BS) crossover for dual-band applications by using two rings included of composite right- and left-handed (CRLH) transmission lines (TLs) with controllable frequency ratio feature. Two dumbbell defected ground structures (DGSs) are employed through balanced TLs to suppress out-of-band common-mode. Theoretical analysis expresses that the frequency ratio can be controlled by suitable selecting of the element values and the number of designing cells of the CRLH TLs. Furthermore, desired impedances and electrical lengths of DGSs are obtained at the frequency of common-mode rejection by using even- and odd-mode analyses. To validate the proposed structure, a dual-band BS crossover operating at 1.8 and 4.2 GHz is fabricated. Measurement results show that the fabricated proposed structure has good performance at the designed frequency bands.

In this Letter, a novel empty substrate-integrated waveguide (ESIW) phase inverter (PI) applied in millimetre-wave has been proposed. ESIW PI, based on the structural symmetry design, is made of four parts: top cover, middle layer, ESIW PCB, and bottom layer. Owing to the reversed-phase transmission channel, the phase difference between the two outputs is absolutely equal to 180°. The simulation and measurement results are in a good agreement. In the entire Ka band, the return losses, insertion losses and amplitude imbalance of ESIW PI are better than 12.7, 2.66, and 0.64 dB ± 0.6 dB, respectively. Besides, the phase difference is within 180.5° ± 2.9° in the same frequency band. In addition, the input and output ports are located in the identical circuit plane, which is easy to integrate with other devices and components.

To decrease cost and consumption of future wireless infrastructures, radio-over fibre systems utilising 850 nm vertical cavity surface emitting lasers and standard single-mode fibre (SSMF) are deserving particular attention in replacing the typical use of graded-index multimode fibre (GI-MMF). In the present work, a characterisation of noise and non-linearities of these links is performed, followed by an estimation of their impact on the system dynamics and the quality of the received signal. This allows to show that very good and similar performances can be obtained through the utilisation of SSMF and GI-MMF for the transmission of five long-term evolution channels with 20 MHz bandwidth, confirming that the former, by the higher diffusion and lower cost per metre of the SSMF, can be put among the leading candidates for the realisation of fourth-generation (4G) and 5G wireless networks.

The vacuum pocket retaining molecular beam epitaxial regrowth of the nano-patterned GaSb surface was demonstrated. The high contrast 2D photonic crystal layer was incorporated into the test 2 µm emitting laser heterostructure. The photonic dispersion determined from angle-resolved electroluminescence experiment showed four well-resolved bands corresponding to the model predictions for the square lattice. The single-mode lasing near 2 µm has been observed at the temperature corresponding to the alignment of the photonic crystal band-edge states and the quantum well gain peak. The reference devices without the photonic crystal layer emitted trivial spectra and did not lase at any temperature.

Noise estimation of an amplified sensor output is essential for not only operating the position sensitive detection (PSD) system efficiently but also for improving accuracy. The noise can vary from device to device and depends on the operating environment; thus, its estimation should be conducted in real time. However, the rectified noise owing to the limited dynamic range of the analogue-to-digital converter makes this estimation challenging. This Letter presents the use of noise parameter estimation, such as non-uniform offset compensation, detection threshold calculation, and variance estimation of a beam's estimated angular position in PSD systems. Moreover, the estimation of rectified Gaussian noise parameters is proposed. Experiments with the implemented PSD system verify the performance of the proposed estimation method for the rectified Gaussian noise characteristics and the offset compensation method for the estimated beam position.

This Letter proposed a novel method to accurately estimate the pole-to-ground fault current in symmetrical monopole high-voltage direct current grids. To avoid simulation's time consuming and difficult modelling, the converter is equivalent to the simple resistor LC circuit, and the state space including negative pole and positive pole is established for pole-to-ground current estimation. To enhance the accuracy of the estimation, the influence of converter control is considered in the estimation. It is found that the dc voltage control mode would impact the fault current rather than the power control mode. In addition, the accuracy can be improved a lot when the control is taken into consideration in fault current estimation. The simulations validate the proposed method finally.

Artefact phenomena resulting from synthetic aperture radar (SAR) image formation can pose a challenge for image interpretation. One such artefact is produced when a vibrating target is imaged. Suppression of these artefacts has previously been described, however little has been developed in the area of modelling the location and shape of such artefacts. The authors present an experimentally validated model that provides accurate location and shape of vibrating target paired echoes in both SAR near-field and SAR far-field imagery.

The forward-biased diode has been widely applied in electrostatic discharge (ESD) protection projects. In this Letter, various diodes with finger-shaped topology are studied by transmission line pulse (TLP) and emission microscope (EMMI) experiments. Among them, a novel mix-mode diode with P-well and floating deep N-well, called MMDIO, is fabricated by the same process and footprint, except that some discrete N⁺ regions are being added to the original anode P⁺ region. This approach forms a combination of a parasitic NPN transistor and a PNPN structure, which can significantly optimise the ESD current efficiency and clamping voltage (V _CL). According to the comprehensive comparison, the MMDIO with overlapped anode N⁺ layout could endure the failure current 1.25 times higher than that of a regular diode under the same junction capacitance (C _j), while the V _CL is reduced by 20%. Accordingly, the MMDIO is an attractive solution to pass the higher ESD level without any negative influence.

As the most feasible alternative to FinFETs, gate-all-around (GAA) multi-stacked nanosheets known as multi bridge channel FETs were recently introduced. To enjoy improved short channel control with high mobility and GAA characteristics, two critical processing challenges on channels should be overcome: the epitaxial growth of silicon/silicon germanium (Si/SiGe) multi stacks and the clean removal of SiGe. Si surface engineering after SiGe removal is a particularly crucial process. Various methods for removing the sacrificial SiGe layer to form nanosheets were tested in this Letter. Through the measurement of D _it and a flat band voltage (V _fb) shift, a remaining sacrificial SiGe layer was detected. After clean removal of the sacrificial SiGe layer and post cleaning, a D _it of 5 × 10¹¹ cm⁻² was achieved, which was similar to that achieved without the removal of SiGe.

An improved subspace-based method for 2D direction of arrival (DOA) estimation of an L-shaped array is proposed in this Letter. Based on real-valued singular value decomposition (SVD), the signal subspaces corresponding to the 2D DOA are obtained from the left and right singular vectors, respectively. Then, the weighted least squares method is utilised to estimate the DOAs from the reconstructed complex-valued signal subspaces, which are automatically paired. Owing to the real-valued SVD, the complexity of the proposed algorithm is reduced and numerical results confirm the effectiveness and accuracy of the proposed approach.

In this study, the authors mainly discuss the robust signal recovery by minimisation with incorporating prior support information, which is not considered in previous works. A robust recovery condition is established and an recovery error estimation is obtained, in particular, the obtained results generalise the state-of-the-art ones. In addition, by proposing a modified algorithm, the numerical experiments show that incorporating prior support information for minimisation exhibits better recovery performance than standard minimisation.

Despite all the benefits of small cells in heterogeneous networks (HetNets) such as coverage improvement and spectral efficiency, they may cause additional interferences. Interference alignment (IA) by cell clustering is a possible candidate to manage HetNets interferences. Several picocells coexist within a microcell area while the nodes that cause interferences in a similar range of the desired signals are grouped in a cluster. IA removes the intra-cluster interferences, and the strong remaining interferences are estimated by interference detection. The simulation results show improvement in the symbol-error rate by the proposed scheme.

In this Letter, the authors present a study on linear channel estimators and their respective mean square error expressions acknowledging spatially correlated channels and pilot contamination. They also investigate the impact of imperfect channel covariance matrix knowledge.