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The problem of detecting linear attacks on industrial systems is presented in this paper. The object is attacked by linear attack is the wireless communication process from sensors to controller with simulated mathematical model (stochastic dynamical systems and random noises). The attack matrices are calculated to ensure that Kullback-Leiber (K-L) algorithm is passed. With these matrices, the window limited cumulative SUM (WL-CUSUM) algorithm and finite moving average (FMA) algorithm are utilized to detect the changes in the sequence of residuals generated from Kalman filter method and are appreciated the ability to detect the linear attack. The simulated results show that an appropriate range of threshold of the WL-CUSUM and FMA algorithm can be chosen to detect the linear attack in case the K-L method cannot detect. Moreover, tested results using the Monte Carlo simulation also show that the evaluation performance of the FMA detection algorithm is better than that of WL-CUSUM, CUSUM, and Chi-squared (Chi2).

Introduction: This study aimed to translate the 31-item Quality of Life in Epilepsy Inventory (QOLIE-31) into Vietnamese and validate the translation. Methods: The inventory was translated through “forward – backward” translation, and culturally adapted for standardization. To ensure the reliability of the inventory, the internal consistency and the temporal consistency was determined. Clinical variables were tested for discriminant validity by comparing their scores. Results: Cronbach’s alpha coefficient ranged from 0.91 to 0.57, with the lowest in the Overall quality of life subscale. Test-retest reliability showed high reproducibility with intra-class correlation coefficients ranging from 0.72 to 0.87 (p

In this study, we present a comprehensive dual-band ambient radio-frequency (RF) energy harvesting system, consisting of rectenna and power management circuit, to harvest energy from 2.45 and 5.8 GHz Wi-Fi. The rectenna employs a metamaterial antenna based on a split-ring resonator, which possesses omni-directional radiation pattern at both frequencies and compact size (0.18λ × 0.25λ at 2.45 GHz). The dual-band rectifier yields the highest efficiency of 42% at 2.45 GHz and 1 dBm input power, 30% at 5.8 GHz and − 7 dBm input power. The maximum RF-DC efficiency for each band is 72% at − 5 dBm and 27% at − 2 dBm, respectively. The power management circuit, consisting of a storing capacitor and a boost converter, is integrated to produce a stable, sufficient output voltage. The energy harvesting system, with its comprehensiveness, is suitable for supplying low-power wireless sensor nodes for indoor applications.

This article presents a new switched beam antenna (SBA) for indoor localization applications. The SBA consists of seven circularly polarized (CP) element antennas using a novel feeding network. The...

In this letter, we propose a solution to improve efficiency and selectivity of triplexers, which operate as filters (or matching circuits) for triple-band energy harvesting. The triplexer consists of multiple higher-order open stubs of $(2n+1)\lambda /4$ length ( $n$ is an integer, $n \geq 1$ ), which is proven to yield high selectivity. With the high selectivity of the filters, the proposed triplexer achieves the efficiencies of 92%, 86%, and 83% at 1.85, 2.1, and 2.45 GHz, respectively. The triplexer is incorporated in a rectenna, yielding a final efficiency of 60% at 5 dBm input power.

This study was conducted to incorporate amine functional groups on the surface of hydroxyapatite to enhance its potential application in biomedical materials. Hydroxyapatite particles (HA) were synthesized from striped catfish (Pagasianodon hypophthalmus) bone and surface modified by grafting with (3-aminopropyl)triethoxysilane (APTES). Important factors affected grafting efficiency such as concentration of APTES, water content, reaction temperature and reaction time were studied. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were used to confirm the grafting reaction on HA surfaces. Grafting efficiency was evaluated based on intensity of characteristic absorption peaks of APTES. The experimental results showed that amine functional groups were successfully introduced on HA surface at optimal condition of 0.2 M APTES, 0.75 wt.% water content, at 60°C and 12-hour reaction time.

In this paper, a simple power - based Direction of Arrival (DoA) sensor is investigated. This sensor is applied in direction finding systems working at 2.6 GHz. The proposed sensor can determine the DoA via a simple formula compared to the algorithms – based methods. The sensor structure consists of simple components: two receiving antennas and a power dividers which have a good isolation between output ports based on hybrid couplers (HCs). With the range of simulation DoA from 0o to 35o, the proposed sensor yields the error of less than 5o.

This letter presents a novel multiband rectenna for the ambient wireless energy harvesting of an autonomous internet of thing (IoT) sensor. A bow-tie antenna with slits is proposed to obtain four frequency bands at 840 MHz, 1.86, 2.1, and 2.45 GHz, respectively. Furthermore, a multiband rectifying circuit combined of four single ring-loop rectifiers is designed with high conversion efficiency. Finally, a power management circuit with storing and converting the harvested voltage is proposed for smoothing dc output voltage. The energy harvester can be used in practical wireless sensor applications.

The free-positioning wireless power transfer (WPT) system has drawn attention in recent years. Traditionally, a WPT system can transfer energy in one or two directions on the same plane, but it leads the restrictions of angle and axis misalignment between a transmitter and a receiver coil. In this paper, we propose a free-positioning WPT system using a three-dimensional cubic-shaped transmitting coil for portable device charging. A small receiving coil is placed inside the transmitter to achieve the transferred energy through the magnetic resonant coupling. In addition, the equivalent circuit and the mutual inductance between the Tx and Rx coils are analyzed. Finally, a practical experiment is implemented to verify the transfer performance, which can reach up to about 50% power transfer efficiency. The proposed system can charge in spatial freedom.

Massive multiple-input multiple-output (MIMO) systems are considered a promising solution to minimize multiuser interference (MUI) based on simple precoding techniques with a massive antenna array at a base station (BS). This paper presents a novel approach of beam division multiple access (BDMA) which BS transmit signals to multiusers at the same time via different beams based on hybrid beamforming and user-beam schedule. With the selection of users whose steering vectors are orthogonal to each other, interference between users is significantly improved. While, the efficiency spectrum of proposed scheme reaches to the performance of fully digital solutions, the multiuser interference is considerably reduced.

Publisher Copyright: © 2022 IEEE. Megahertz-range wireless power transfer (WPT) system through inductive coupling has become increasingly popular during the past years. As a critical part of high-frequency WPT, parasitic components of the coils must be carefully considered because of their great impacts on the system's operation. In this paper, we propose an analytical method to deal with this problem by adding compensation capacitors on each side of the coils and calculating the appropriate value of these capacitors to attain the maximum load power and efficiency. This work is performed on the 6.78-MHz WPT system to illustrate the characteristics and enhance the robustness of the system.

In this paper, a compact wearable U-shaped monopole antenna operating at 2.4 GHz frequency band is proposed for Medical Body Area Network applications. The antenna has a compact size of 0.37 λ × 0.31 λ , covering a band from 2.14 GHz to 3.03 GHz with a gain of 2.3 dBi at 2.45 GHz, and an efficiency of 93% in free space. In addition, an Electromagnetic Band Gap (EBG) metamaterial is utilized to isolate the integrated antenna on the circuit and the body, reducing the Specific Absorption Rate (SAR). In consequence, an integrated circuit employing the EBG ground plane provides a safe value of SAR (0.68 W/kg) when it is attached to a human arm followed by a 74% reduction of SAR value compared to the circuit without EBG (2.57 W/kg). Furthermore, the on-body efficiency of the EBG-based antenna is improved from 54% to 73.68%. Finally, experimental results of a wearable heart rate and blood oxygen level BLE sensor based on the proposed U-shaped EBG monopole antenna exhibit an average power consumption of 108 mW, a sensitivity of -74 dBm, and a maximum Bluetooth Low Energy (BLE) transmission distance with a mobile phone of 16 m in the complex environment.

In this work toward a sustainable operation of a self-powered wireless sensor, we investigated a multiband Wi-Fi/3G/4G/5G energy harvester based on a novel wideband circularly polarized antenna, a quadplexer, and rectifiers at four corresponding bands. This proposed antenna consisted of four sequentially rotated dual-dipoles, fed by a hybrid feeding network with equal amplitude and an incremental 90° phase delay. The feeding network was composed of three Wilkinson power dividers and Schiffman phase shifters. Based on the sequential rotation method, the antenna obtained a −10 dB reflection coefficient bandwidth of 71.2% from 1.4 GHz to 2.95 GHz and a 3 dB axial ratio (AR) bandwidth of 63.6%, from 1.5 GHz to 2.9 GHz. In addition, this antenna gain was higher than 6 dBi in a wide bandwidth from 1.65 GHz to 2.8 GHz, whereas the peak gain was 9.9 dBi. The quad-band rectifier yielded the maximum AC–DC conversion efficiency of 1.8 GHz and was 60% at −1 dBm input power, 2.1 GHz was 55% at 0 dBm, 2.45 GHz was 55% at −1 dBm, and 2.6 GHz was 54% at 0.5 dBm, respectively. The maximum RF–DC conversion efficiency using the wideband circularly polarized antenna was 27%, 26%, 25.5%, and 27.5% at −6 dBm of input power, respectively.

In this paper, we present a novel millimeter-wave antenna using the Grounded coplanar waveguide (GCPW)-to- Substrate Integrated Waveguide (SIW) transition. This high-gain and wideband antenna consists of four patches and each patch is fed by the SIW and a cross-shaped aperture. The antenna operates from 27.1 GHz to 31.9 GHz (S11 ≤ -10dB) with a peak gain of 10 dBi, and an efficiency of 89%.

This paper presents a wideband (1.575 GHz-2.875GHz) printed dipole antenna design with an integrated balun. The peak antenna gain is 7.5 dBi at 2.45 GHz using a director that is placed in parallel with the dipole arms. The compact size and high efficiency are the advantages of this antenna which makes it useable for RF energy harvesters from the GSM 1800, UMTS 2100, the WLAN 2450 based IEEE 802.11b/g and LTE 2600 sources to power a wireless sensor.

In this work, we propose a novel Wi – Fi blocking window based on metamaterial microwave band – stop filter. Made of glass and fluorine – doped tin oxide (FTO), the proposed window is transparent for visible light, allows other RF waves to go though significantly while completely blocks the Wi – Fi signal. With such property, this window can be used for confidential purpose.

In this paper, the circularly polarized (CP) antenna is proposed based on the loop antenna for ambient RF energy harvesting (RFEH) applications. This loop antenna is meandered to achieve a compact size of 30 mm × 50 mm. The proposed CP meandered-loop antenna has a measured bandwidth of 150 MHz at – 10 dB with a center frequency of 2.14 GHz for 3G and 4G technologies. A maximum of 62 % RF-DC conversion efficiency is obtained using the proposed CP antenna and a load of 1.2 KΩ when the power of the incident wave is 0 dBm.

Wireless power transfer presents a robust method to provide a safe and convenient solution for powering biomedical implants. The implanted device is necessarily minimized conducive to the transfer efficiency degradation. This paper presents a wireless power transfer for retinal prosthesis using an artificial intelligent algorithm to optimize the power transfer efficiency with the minimizing implanted device dimension. A novel transmitter is designed based on the conformal strongly coupled magnetic resonator, which is proposed to attach to the glasses lens. An implanted receiver is optimized to obtain the highest efficiency with the minimal dimension of 9.7 x 9.7 x 1.9 mm3. The WPT system achieves approximately 17.5 % at the operating ISM frequency band of 433 MHz and a distance between transmitter and receiver of 20 mm.

A novel wideband circularly polarized reconfigurable antenna for 5G devices is presented in this paper. Left hand and right-hand circular polarizations were achieved using the sequential phase rotation feeding network based on 90° hybrid coupler. The proposed antenna has a bandwidth (with AR ≤ 3 dB) of 24.8% and 4% for right hand circular polarization (RHCP) and left-hand circular polarization (LHCP) mode, respectively. At 3.75 GHz, the degree of circular polarization is 42° in LHCP mode and 51° in RHCP mode showing the potential of this proposed antenna for modern 5G terminal devices.

In this work, we propose a smart shoe integrated with a very-low power wireless sensor node operating in Bluetooth Low Energy (BLE) 5.0 standard. The sensor node consists of a miniaturized printed inverted-F antenna, an accelerometer and a gyroscope being placed at the bottom of the shoe to measure footstep-length, running speed and foot landing angle. The maximum power consumption of the sensor is 11 mW and it is sustained by a triboeletric nanogenerator (TENG) which generates power from the friction causing by user's motion itself and an energy storage circuit. The triboelectric energy harvester, having the size of 6 cm × 6 cm, is made of multiple pairs of triboelectric materials can harvest up to 32 mW/m2, enough to supply the sensor node.

Midfield wireless power transfer has been proven as a solution for biomedical micro-implant that can operate at nearly any location in the body. Some previous experiments using an external patterned structure as optimal source demonstrated magnetic and current density focusing characteristic on multilayers tissue, therefore, significantly enhancing efficiency for wireless powering to miniature receivers than conventional inductively coupled coils. This paper proposed a novel compact and simple source transmitter while conserving convergence effect on human tissue.

This paper presents a novel wideband element antenna for base station application covering all frequency bands for existing cellular system from 1.65 to 2.93 GHz. The proposed antenna element has a stable gain of 8.7 ± 0.8 dBi over the entire frequency range. The horizontal beamwidth is at least 60 degrees. The performance of this antenna element is satisfied all requirements for expected wideband base station antennas. The antenna element based on magneto-electric (ME) dipoles consists of two double-bowtie shaped dipoles for two polarizations of ±45 degrees. The feeding baluns for the two dipoles have step-changed width to obtain better impedance matching, and they are simply designed for mass production. Besides, the radiators of the dipoles are double- bowtie shaped to enhance the impedance bandwidth.