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It has been reported that stimulating nociceptive unmyelinated C nerves (C) near the sarcolemma could induce the secretion of endogenous opioids that relieve chronic pain. However, a substantial concern remains: concomitant stimulation might cause acute pain to nociceptive myelinated Aδ nerves (Aδ), which generally have a lower activation threshold than the C. However, few studies have reported on C selectivity over Aδ (C-selectivity). In this study, the C and Aδ nerves were modeled using the Hodgkin-Huxley (HH) and McIntyre-Richardson-Grill (MRG) models, respectively. Two potential stimulation schemes, including bipolar square waves and burst modulated alternating current, together with a new stimulation scheme named inhibit-Aδ (i-Aδ) that inhibits the excitability of theAδ, were systematically investigated. Their stimuli were given to the C and Aδ nerves through point electrodes located near the nerve fibers. Simulation results revealed that i-Aδ presented the highest C-selectivity, which provides a basis for non-invasive effective chronic-pain relief.

Increased density of printed circuit board assembles (PCBAs) is diminishing physical contact test access of the in-circuit testing (ICT) solutions for defects detection. As a result, it is necessary to design contactless test solutions with high spatial resolution to overcome the current test limitations. In this paper, a compact contactless sensor is presented for monitoring the fabrication quality of PCBAs. The sensor consists of an inductor-capacitor-(LC)-based resonant circuit and it can detect defects on metallic traces of PCBAs in close proximity without a contact. The sensor is designed such that, strong electric field is confined around the sensor tip, which creates strong capacitive coupling between the sensor tip and devices under test (DUTs) within a small region for sensing, i.e. high resolution sensing. The sensitivity of the proposed sensor is verified by the simulated and experimental 2D surface mapping results with sample DUTs, and it shows that the sensor can detect the open or short defects with a size as small as 0.15 mm $\times $ 0.2 mm. Circuit models are proposed to predict the sensing behavior and for guiding the design. The proposed sensor shows great potential to be used in the real-time monitoring of defects along the manufacturing supply chain.

We present a design and the optimization of an irregular-shaped inward-outward (IO) ring-pair magnet array that generates a 1D monotonic field pattern for 2D head imaging in a low-field portable magnetic resonance imaging (MRI) system. The magnet rings are discretized into fan-shaped ring segments with varying outer radii for the design and optimization. Besides, the inner radii of ring-pairs are tapered from outside in to provide the controlled field inhomogeneity. Genetic algorithm (GA) was used, and a current model for a fan-shaped ring segment was derived to have a fast forward calculation in the optimization. A monotonic field pattern is successfully obtained along the x-direction in a cylindrical field of view (FoV), with a relatively strong magnetic field (132.98 mT) and the homogeneity of 151840 ppm. The proposed array was further evaluated by applying its field as a spatial encoding magnetic field (SEM) for imaging by using simulation. Due to the field monotonicity, the reconstructed image by applying the fields of the proposed array shows clearer features (a higher structural similarity index) with a reduced error rate compared to that using a sparse dipolar Halbach array. The proposed magnet array is a promising alternative to supply SEM for imaging in a permanent-magnet-based low-field portable MRI system.

Low-cost and portable magnetic resonance imaging (MRI) may make this imaging modality more accessible. Permanent-magnet-array is an option to supply a static magnetic field (B-field) with portability, low cost, and no power consumption. However, it has low field strength. Moreover, it does not have linear gradients, thus the signals and the images are not linked by the Fourier transformation as they are in a conventional system. The B-field generated by an array and called spatial-encoding-magnetic-field (SEM), is spatially non-linear and always on. Such an SEM, in terms of the field strength, direction, homogeneity, pattern and its field pattern variation, is related to the image quality. This relation is crucial because it can be used to guide the magnet and system design for high image quality and portability. However, it has not been systematically studied. In this paper, the characteristics of the SEMs from different magnet array designs are identified. Due to the non-linearity of the SEMs, local structural similarity (SSIM) index is proposed to evaluate the region-dependent image quality, and local k-space is applied to analyze the region-dependent effects of these SEMs on image reconstruction. Moreover, point spread function is applied to analyze the overall effect of the SEMs on the quality of reconstructed images. Besides the intrinsic effects of the SEMs, those of the external factors, e.g. the receive coil sensitivity, are analyzed. This study identifies the unique characteristics of the SEMs in a permanent-magnet-array-based MRI system, and offers methods to analyze the unique relation between the image quality and the field. It can not only guide the magnet designs but also trigger more design ideas, e.g., the design of the mechanical movement of the magnet array, and that of the static magnetic field shimming coils, paving the way towards a low-field MRI system with practical portability.

In this work, we propose to combine machine learning (ML) techniques with an analytical method to provide a stable and accurate electrical properties (EPs) reconstruction from MRI measurements. A dataset was created from MRI measurement simulations to train an estimator for a set of important parameters of the analytic method with a ML algorithm. The analytic method was thus optimized to produce accurate reconstruction of EPs within the framework. Current results offer a feasibility test for the new combined approach that can be used to reconstruct accurate EPs maps.

Wide bandwidth is a key requirement for Radio Frequency (RF) coils in the emerging body-part-dedicated portable Magnetic Resonance Imaging (MRI) due to the static field inhomogeneity caused by a short magnet. As the size of the magnet, either a superconducting magnet or a permanent magnet array (PMA), is reduced, the B 0 field homogeneity is reduced significantly. The lowered B 0 field homogeneity leads to an increase in the working bandwidth. A wideband RF coil helps to guarantee the excitation and reception of signals within a targeted field of view (FoV). In this paper, we propose single-tapered and dual-tapered wideband Microstrip Transmission Line (MTL) volume coil for a 1.5T MRI system with a short magnet. The fractional Full Width at Half Maximum (FWHM) bandwidth for the proposed tapered and dual tapered coils are 11.25% and 10.62%, respectively, which are 28.57% and 21.4% higher than that of the traditional non-tapered MTL volume coil, yet having a comparable B 1 field intensity.

RADAR systems are traditionally the domain of the military or large commercial entities due to technology costs. Recent emergence of affordable software defined radios (SDRs) have lowered the barriers to entry of radio-frequency developments available to the public, allowing for low-cost implementations and developments of technology that was previously inaccessible. In this work, a cost-effective passive bistatic phased array radar using the digital video broadcasting (DVB-T2) band is proposed, using only low-cost SDRs and commercially available DVB-T2 dipole antennas normally used for home television signal reception to reduce the cost of the system. By using beam-steering techniques to reduce noise and reconstruct the original signal from the transmitter, the array is used as both the reference and surveillance channels, eliminating the need for a dedicated reference channel. The working frequency is 554 MHz. The ability to detect the presence of and direction of commercial flights with respect to the array is demonstrated.

A portable magnetic resonance imaging (MRI) imager may help this medical imaging modality to reach out areas that are remote or/and hard to access, and situations that the environment is dynamic, for example, in an ambulance. Permanent magnet array is a popular option to supply the main magnetic field for imaging. It allows portability, does not consume power, and guarantees a low cost. However, the magnet field it generates does not have a linear gradient, thus the acquired signals from the system and the image are not directly linked by Fourier Transformation. There are different kind of magnet arrays that can be used in a portable system. Halbach array with a transverse magnetic field provide an option. Besides, Aubert array with a longitudinal magnetic field that was recently proposed is a good alternative [1]–[2]. For a magnet array, the field strength, field homogeneity, and field pattern are directly related to the quality of image reconstruction [3]. In this talk, different magnet arrays and the characteristics of the magnetic fields they generate for imaging in a low-field MRI system will be introduced. The effects of the magnetic fields on the image reconstruction will be analysed in detail.

In this paper, a reconfigurable slot antenna has been proposed for the fifth-generation (5G) smartphone applications to cover a wide bandwidth of 824–960 MHz, 1710–2690 MHz, 3300-3600MHz and 4800–5000 MHz. The antenna is placed at the bottom of the phone, and is designed for metal casing. The folding slot structure is used to realize the miniaturization and narrow ground clearance of the antenna. The PIN diodes are used to achieve three different working states, so as to bring about good frequency coverage and antenna miniaturization. The proposed antenna has achieved the good impedance bandwidth and acceptable total efficiency throughout the required bands. The result shows that the proposed antenna is good candidate for a 5G smartphone with metal casing.

A compact antenna with dual-band for forming the multiple-input multiple-output (MIMO) antennas in the future smartphone is presented. The proposed antenna has a planar structure of small size 7×15.5 mm2 for operating at fifth-generation (5G) band (3.3-3.6 GHz and 4.8-5.0 GHz), which is the recently identified frequency spectrum in Ministry of Industry and Information Technology of the People's Republic of China. The proposed MIMO antenna is formed by the T-ship open-slot antenna has symmetrically mirrored structures with respect to the frame that along the long side edge. The eight antennas show good isolation thereof and their envelope correlation coefficient (ECC) is much less than 0.15 in the operating band, showing very good independence of the eight antennas in their far-field radiation characteristics.

In this paper, we present the progress of the development and design of a portable low-field ( 0 field with the merits of light weight and helium free, the work done on transmit and receive RF coils, the progress on the nonlinear imaging reconstruction algorithm based on a inhomogeneous B 0 field provided by the magnet array, and the testing on a Magritek NMR spectrometer console.

Magnetic Resonance Imaging (MRI) has become one of the important biomedical modalities. However, conventional MRI system is very bulky (normally it takes two-rooms size) and expensive. A low-cost and portable MRI scanner may be useful in more diverse scenarios. A Halbach array based MRI system with flexible spatial nonlinear imaging strategy has been proposed with low cost and portability. In this paper, a Truncated Singular Value Decomposition (TSVD)-based approach is proposed for the flexible spatial nonlinear encoding strategy for a portable MRI. This method shows an improve Normalized Root Mean Square Error (NRMSE) compared to the existing solutions, such as the Kaczmarz iteration and the QR method when the system is noisy.

Preserving the content of historic handwritten manuscripts is important for a variety of reasons. On the other hand, digital libraries are rapidly expanding and thus facilitate to store this information directly in digital form. For digitising text documents, a crucial step is to binarise the captured images to separate the text from the background. In this paper, we propose an effective approach for binarisation of handwritten Arabic manuscripts which employs a whale optimisation algorithm, incorporating a fuzzy c-means objective function, to obtain optimal thresholds. Experimental results confirm the effectiveness of the proposed approach compared to earlier methods.

Investigating information credibility is an important problem in online social networks such as Twitter. Since misleading information can get easily propagated in Twitter, ranking tweets according to their credibility can help to detect rumors and identify misinformation. In this paper, we propose a Petri net model to visualise tweet credibility in Twitter. We consider the uniform resource locator (URL) as an effective feature in evaluating tweet credibility since it is used to identify the source of tweets, especially for newsworthy tweets. We perform an experimental evaluation on about 1000 tweets, and show that the proposed model is effective for assigning tweets to two classes: credible and incredible tweets, which each class being further divided into two sub-classes (“credible” and “seem credible” and “doubtful” and “incredible” tweets, respectively) based on appropriate features.

Indirect immunofluorescence (IIF) imaging is an important technique for detecting antinuclear antibodies in HEp-2 cells and therefore employed in the diagnosis of autoimmune diseases and other important pathological conditions involving the immune system. Here, HEp-2 cells are categorised into different groups, which allow to make implications about different autoimmune diseases. Traditionally, this categorisation is performed manually by an expert and is hence both subjective and time intensive. In this paper, we present an effective method for classification of HEp-2 cells in which we first extract local binary pattern (LBP) texture features in form of multi-dimensional LBP (MD-LBP) histograms and then employ a multiple kernel learning approach to classification that integrates a multitude of support vector kernels generated by sampling the feature space. We evaluate our algorithm on the ICPR 2012 HEp-2 contest benchmark dataset, and demonstrate that our employed texture features are indeed useful for the differentiation of HEp-2 cells and that our multiple kernel learning based classification approach outperforms single kernel classification schemes. Our algorithm is shown to provide super performance compared to all techniques that were entered in the competition and to rival results obtained by a human expert.

Transverse electromagnetic (TEM) coils was proposed for head imaging in a 4T magnetic resonance imaging (MRI) system1 and its feasibility for a 7T system using parallel imaging was reported2. When B0 = 10.5 T, a TEM head coil starts to show B1-field inhomogeneity because of the further increase in Larmor frequency (f L ). The reason is that an increase in f L leads to a smaller wavelength and therefore the standing wave pattern in the object under scan becomes more severe. Here, we apply the concept of metamaterial to design a TEM head coil. By doing this, the guided wavelength increases along a TEM line and the B1-field inhomogeneity at 10.5 T can be eliminated. In this abstract, the theory, a design, and the simulation results are presented and we are preparing for experiments for validations next.

Antenna miniaturization is one of the biggest challenges against the backdrop of increasing density of electronic components on the circuit board of handheld devices [1] and biomedical devices for body-centric wireless communications [2]. Especially for biomedical application, an antenna is needed in an implantable or ingestible device for both communications and power charging. However, space is always limited for the antenna in the device, e.g. a pace maker or a capsule endoscope. The current antenna designs have reached their ultimate limit of miniaturization and new design paradigms are needed in order to break the limits of antenna miniaturization. The present work is focused on the use of piezoelectric materials as antennas for antenna miniaturization for body-centric wireless communications.

This paper presents a novel digital beamforming to improve channel quality. By estimating the received channel impulse response (CIR) to calculate the arrival of angle (AOA) of received signal, and we scan the AOA to adjust the weighting vector of received signal and improve the channel quality. The performance of system with digital beamforming can improve 16 dB signal to noise ratio (SNR) in non-line of sight (NLOS).

In vehicular application, the wireless receiver not only considers the channel effect, like Doppler effect, Shadowing effect, Multipath fading, … etc., but also the impulse jamming and continuous wave (CW) jamming from the device in the vehicle. This paper presents anti-jamming automatic gain control (AGC) and packet detection for vehicular receiver. In impulse jamming and CW jamming existence, the AGC responses a suitable gain in 3.2us when packet is arriving, and the packet detection hit rate exceeds 99% hit rate under multipath fading and shadowing effect.