The performance of the Vertical Cavity Surface Emitting Laser (VCSEL) for hybrid optical links SMF/FSO based on different data rates and MIMO configuration techniques was obtained using OptiSystem^TM which is close to the results of the experimental system. The developed system was tested with various transmission distances: 20, 30, 40, and 50 km, and in the existence of many configuration kinds and modulations. In addition to that the hybrid system was estimated with different weather cases: clear, rain, and snow. The results state that the performance of the OOK-NRZ system reveals better performance than OOK-RZ system under the same conditions. Also, the performance of the free space link is better than the fiber link formost of the link ranges considered and configurations. For OOK-NRZ of the fiber link, it was found that the MIMO 8×8 technique has better system performance than other configurations, and the Q-factor = 11.39 and BER = 5.4×10^-30 for a length of 50 Km while for the FSO link, it was found that MIMO 8×8 indicates a high performance for Q-factor = 12.7 and BER = 1.8×10^-37. The maximum FSO link distances under different weather conditions and coupling ratios were found. For BER≤10⁻⁹, in NRZ format for SMF 50 km utilizing MISO8×1 technology in clear weather for 10 Gbps, 15 Gbps, and 20 Gbps for FSO links, the maximum accessible lengths are 0.6 Km, 0.51 Km, and 0.43 Km, respectively. The process is expanded to include snow conditions for data rates of 10 Gbps, 15 Gbps, and 20 Gbps for FSO links with lengths of 0.4 Km, 0.3 Km, and 0.26 Km, respectively.

Methods of manual analysis for infrared image and temperature detection of power transmission and transformation equipment typically have problems, such as low efficiency, strong subjectivity, easy to make mistakes and poor real-time feedback. In this paper, a high temperature anomaly detection method based on SegFormer in infrared image of power transmission and transformation equipment is proposed. Many infrared images of power transmission and transformation equipment are collected and preprocessed, and the temperature information of each infrared image is read out using the DJI sdk tool to construct the temperature data matrix. In the segmentation stage, the SegFormer network is used to segment the key parts of the power transmission and transformation equipment to obtain the mask for detection. The maximum values of the temperature data in the mask area are calculated, and the high temperature anomaly detection atthe key parts of the power transmission and transformation equipment is realized. The test results on the test set show that the overall performance of the method is the highest as compared to other methods such as FCN, UNet, SegNet, DeepLabV3+, and an automatic temperature recognition can be realized, which has important practical value for the detection of high temperature anomaly at the key parts of power transmission and transformation equipment.

This paper designs a miniaturized, wide stopband microstrip filtering coupler based on coupled resonators. Firstly, a short-stub loaded uniform-impedance resonator (SSLUIR) is proposed, , and the size of the SSLUIR is reduced by adjusting the impedance ratio of the stubs and bending them. Then, the resonance performance of SSLUIR during electrical and magnetic coupling is studied. By adjusting the electrical length of the short stubs, higher harmonics are suppressed, and the upper stopband is widened. Finally, a 3 dB 180° microstrip filtering coupler is designed based on SSLUIRs. The measurement results show that the center frequency of the filtering coupler is 2.43 GHz, with a relative bandwidth of 6.6%. It can suppress harmonics within the 8.2f₀ range by more than 18 dB and has a size of 0.23λ_g×0.33λ_g. The correctness of the design method for miniaturized and wide stopband filtering coupler has been verified.

Plasmonic topological states, providing a new way to bypass the diffraction limits and against fabrication disorders, have attracted intense attention. In addition to the near-field coupling and band topology, the localized surface plasmonic resonance modes can be manipulated with far-field degrees of freedom (DoFs), such as polarization. However, changing the frequency of the topological edge states with different polarized incident waves remains a challenge, which has led to significant interest in multiplexed radiative topological devices. Here, we report the realization of polarization-wavelength locked plasmonic topological edge states on the Su-Schrieffer-Heeger (SSH) model. We theoretically and numerically show that such phenomenon is based on two mechanisms, i.e., the splitting in the spectra of plasmonic topological edge states with different intrinsic parity DoF and projecting the far-field polarizations to the parity of lattice modes. These results promise applications in robust optical emitters and multiplexed photonic devices.

This paper presents a novel design of Compact Notched Wide Band Antenna that has dual notches in the band of Wireless Local Area Network (5.15 GHz-5.825 GHz) and X-band Satellite Communication (8 GHz-12 GHz). The proposed antenna has a defective ground structure (DGS) to operate the antenna for wide band applications. Notch bands are achieved by inserting slots on the radiating patch and feed line. A horizontal S-shaped slot on patch is responsible for the notch in the band of wireless local area network, and an inverted U slot is used in feed line to get a notch in the band of Satellite Communication. The proposed antenna is fabricated using FR4 substrate of size 26 x 26 x 1.6 mm³ and tested using Vector Network Analyzer MS2037C. Although the measured results are slightly changed in comparison with simulated, they agree reasonably well. The measured result also reveals that the prototype antenna is in compact size and resonated from 4.24 GHz-12.59 GHz with two notch bands centered at 5.8 GHz and 10.3 GHz.

Wireless communication systems have developed significantly over the last few decades. Due to the saturation of lower frequencies of microwave spectrum (3-30 GHz) and the increasing need for high speed, emerging systems for consumer or professional use are progressively shifting to upper microwave and millimeter waves. Our study proposes a methodology for evaluating and classifying losses on a vertically polarized millimeter wave link at 80 GHz. To achieve this, we simulated the link budget of a Nokia 80UBT millimeter wave link operating in its real propagation space (with overground) with Pathloss 5.1 Design tool. Then we built a 3.58 km full-scale link in the Tongo-Bassa watershed of the coastal city of Douala in Cameroon. Analysing data collected over the period from December 06, 2020 to December 16, 2021 under Power BI allowed us to characterize the response of the millimeter signal in free space, during dry and rainy seasons. We then challenge ITU-R P.837-7 and ITU-R.P.838-3 Recommendations on statistical models of rainfall for propagation modeling, especially for millimeter signals propagated in an equatorial climate with heavy rainfalls. The study estimated a rainfall rate for 0.01% of the time at 110.1 mm/h, with a millimeter link cut-off for a rainfall rate greater than 64.8 mm/h, with a specific attenuation due to rain of 6.5 dB/km.

Linear Frequency Modulation (LFM) signals are widely used in radar and sonar technology. Many applications are interested in determining the source of an LFM signal. In recent years, the rapid development of machine learning has facilitated research in various fields, including signal recognition. The neural networks can extract the implicit features of the signals, which can help the system to sort and recognize the signal sources quickly and accurately. High performance of neural networks requires large amounts of high-quality labeled data. However, it is difficult and expensive to obtain a large amount of high-quality labeled data. Simultaneously, some features will be lost during data preprocessing, and feature extraction and classification tasks will be inefficient. The self supervised network is proposed in this paper for pre-training the signal waveform and fine-tuning the classification with a small amount of labeled data. The proposed method can extract more signal waveform features, save labeling costs, and has higher precision. This method can provide up to 99.7% recognition accuracy at 20 dB.

Generalized Mie theory provides a theoretical solution to the extinction cross-section curve of an electromagnetic scattering event with a multiparticle aggregate, given the configurational information of the constituent particles. However, deducing the configuration of the aggregate from the extinction cross-section curve is a non-trivial inverse problem that can be cast as a global optimization problem. To address this challenge, we propose a computational scheme that combines global optimization search algorithms with a calculator known as the Generalized Multiparticle Mie-solution The scheme is tested using mock scattering cross-section curves based on randomly generated aggregate configurations. The scheme successfully reproduces the scattering curve by minimizing the discrepancy between the two scattering curves. However, the ground-truth configuration is not reproduced, as initially expected. This is due to the inability of the global optimization algorithm scheme used in the present work to correctly locate the global minimum in the high-dimensional parameter space.Nonetheless, the partial success of the proposed scheme to reconstruct the mock curves provides an instructive experience for future attempts to solve the inverse electromagnetic scattering problem by fine-tuning the present approach.

In order to reduce the cogging torque and improve the back electromotive force (EMF) performance of the motor, a three-phase permanent magnet (PM) synchronous motor with magnetic pole eccentricity and slotting design is proposed in this paper. Firstly, the analytical expression for the cogging torque of the motor is derived based on the energy method, and the factors influencing cogging torque are analyzed. Subsequently, taking the cogging torque and the amplitude of the back EMF as the optimization objectives, the response surface method (RSM) and multi-objective genetic algorithm (MOGA) are combined to obtain the optimal values for the eccentricity distance of the PMs, slotting radius, and slot position. Finally, a finite element model is established for simulation comparison. The results show that compared with the traditional model, the optimized model effectively reduces the cogging torque while slightly sacrificing the back-EMF amplitude, and improves the sine degree of the no-load back-EMF.

This paper presents the design and implementation of a C-Band Frequency Generator developed for Space-borne Synthetic Aperture Radar. This Frequency Generator subsystem generates stable and coherent reference signals for all the sub-systems of C-Band Synthetic Aperture Radar payload. Frequency Generator based on frequency multiplication technique generates various coherent signals namely 500 MHz signal for digital clock, local oscillator (LO) signals of 900 MHz and 4500 MHz needed for receivers and chirp signal of 5400±37.5 MHz. This chirp signal is generated by direct modulation of the full bandwidth baseband signal of DC-37.5 MHz at 4500 MHz and subsequently mixing with 900 MHz signal. Frequency generator unit is realized in a compact two-tier architecture, using novel concept of full chirp modulation, resulting in 6° rmsphase error in the transmit chirp signal along with in-band spurious rejection better than 20 dBc, whereas other coherent frequencies resulting in out of band spurious rejection better than 53 dBc against the specification of 40 dBc.

The core structure of transformers and reactors is subject to stress and high-frequency excitation during operation. The core structure is made of laminated silicon steel sheets, which are subject to magnetostrictive strain under alternating magnetic fields. To investigate the comprehensive magnetic properties of oriented silicon steel sheets under the influence of harmonics and stress, this paper builds a magnetic property measurement system for electrical steel and investigates the magnetization and magnetostriction characteristics of oriented silicon steel sheets of type 30SQGD105 under working frequency, harmonic and applied stress conditions. The results show that the effects of harmonics and stress on the hysteresis characteristics of the silicon steel sheet are small, and the effects on the magnetostriction characteristics are large.

A metamaterial-inspired antenna is proposed that utilizes an artificial mu-negative (MNG) transmission line (TL) to incorporate the zeroth-order resonance (ZOR) into Wi-Fi 7 operation in the 2.4/5/6 GHz wireless local area network (WLAN) bands. The antenna comprises a meta-structured loop with periodically loaded series interdigital capacitors and a parasitic shorted strip, all formed on the same substrate layer in a coplanar structure. The 2.4 and 6 GHz bands are produced by the parasitic strip and the close-form loop strip, respectively, which are of typical right-handed antennas. The 5 GHz band caused by the ZOR mode, where the permeability is zero, can be adjusted by the series capacitance in the unit cell. The total antenna size is 5.4 mm × 19.6 mm only. In this work, the design applied to notebook computers for the upcoming Wi-Fi 7 operation is also demonstrated. Both numerical and experimental results validate our proof-of-concept design.

Pulmonary edema assessment is a key factor in monitoring and guiding the treatment of critically ill patients. To date, the methods available at the bedside to estimate the physiological correlation of pulmonary edema and extravascular pulmonary fluid are often unreliable or require invasive measurements. The aim of this article is to develop an imaging method of reliably assessing pulmonary edema by utilizing functional electrical impedance tomography. In this article, the Split-Bregman algorithm is used to solve the Total Variation (TV) minimization problem in EIT image reconstruction. A thorax model is constructed according to CT images of rats. Through simulation and experiment, the proposed method improves the quality of reconstructed image significantly compared with existing methods. A pulmonary edema experiment in rats is also carried out. The development of pulmonary edema is analyzed numerically through EIT images.

The rapid advancement of communication technology has led to an increase in electromagnetic interference (EMI), or electromagnetic (EM) pollution. This is a cause for concern, as EMI can disrupt communication services, damage electronic equipment, and pose health risks. Regulatory bodies are working to develop standards for the safe use of wireless devices, but the problem of EMI is likely to continue to grow as the number of Internet of Thing (IoT) devices continues to increase. To address this issue, this study investigated the effectiveness of carbon-coated cobalt ferrite nanoparticles as a potential material for electromagnetic shielding. The synthesis of cobalt ferrite (CoFe₂O₄) nanoparticles was successfully achieved using the co-precipitation method. Subsequently, a carbon coating was applied to the nanoparticles through a hydrothermal process using a 200 mL autoclave made of teflon-lined stainless steel. This process was carried out at a temperature of 180˚C for a duration of 12 hours, with a heating rate of 8˚C per minute. This study examined both uncoated and carbon-coated CoFe₂O₄ nanoparticles at various ratios of glucose to CoFe₂O₄ (1:1, 2:1, and 3:1) using techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and higher resolution transmission electron microscopy (HRTEM) analysis. The XRD analysis revealed distinct and well-defined peaks corresponding to CoFe₂O₄, indicating the successful synthesis of the nanoparticles. The crystallite size of the uncoated CoFe₂O₄ nanoparticles was measured to be 11.47 nm, while for the carbon-coated CoFe₂O₄, the average crystallite size was determined to be 14.15 nm through XRD analysis. The results obtained from the FTIR analysis were consistent with previous reports and confirmed the formation of spinel CoFe₂O₄ nanoparticles, as suggested by published data. The morphological and structural properties of the prepared samples were further characterized using FESEM and HRTEM analysis, which demonstrated uniformity in both particle size distribution and morphology. Overall, the research findings indicated that the structure and properties of CoFe2O4 nanoparticles were significantly influenced by the carbon coating process. Notably, the optimum ratio of carbon to CoFe₂O₄ was found to be 2:1, which resulted in the highest carbon thickness. The electromagnetic properties of the samples were evaluated using a vector network analyzer (VNA) and measured S-parameters in the frequency range of 8.2 to 12.4 GHz, known as the x-band region, suitable for radar applications. The sample with a carbon ratio of 2:1 exhibited the highest total shielding effectiveness (SE) of -17 dB at approximately 10 GHz. As a conclusion, the carbon-coated CoFe₂O₄ nanoparticles showed promising potential as an effective material for shielding against electromagnetic wave pollution, particularly when the carbon coating and filler composition reached an optimal point. Additionally, the shielding effectiveness performance of the sample could be further enhanced by incorporating a conductive polymer as an auxiliary material.

Wireless communications need antennas of different sizes, shapes, frequency-bands, bandwidths, and radiation patterns due to technical requirements, physical constraints, and FCC (Federal Communication Commission) regulations. For example, S-band antennas (2 GHz~4 GHz) are used in navigation, C-band antennas (4 GHz~8 GHz) used in Air-borne RADAR, X (8~12) band antennas used in Satellite communications, and millimeter wave (40 GHz and above) antennas used in autonomous vehicles. Ultrawide Band (UWB) antennas of different frequency bands have also applications in different fields such as medical imaging, radar imaging, software defined radios, surveillance, and health monitoring of different equipment. Microstrip patch antennas of different gains, bandwidths, shapes, and radiation patterns will play a vital role in different wireless applications of future 6G systems. In this paper, we have discussed different novel designs of patch antennas at different frequency bands: V-shaped patch antenna at 2.4 GHz, and hexagonal slotted half-circular patch antenna at 4.29 GHz. We have designed antennas of different shapes for different frequencies since some applications require UWB; some applications require narrow band but higher gain; and some applications require different gain/radiation patterns at the same frequency. We have designed a patch antenna at 2.4 GHz that can be used in Wi-Fi, and UWB patch at 4.29 GHz with omnidirectional radiation pattern that can be used in energy harvesting or biomedical applications. In this paper, we have also discussed the prototype development and testing results of the novel hexagonal slotted half-circular patch antenna at 4.29 GHz.

A wide band circularly polarized planar antenna of high radiation efficiency is proposed in the present work for future generations of wireless communications requiring circular polarization in the X-band of the microwave spectrum. The main radiating part of the antenna is a rectangular turn-shaped strip that is capacitively loaded by two corner-shaped parasitic elements. The antenna is fed through coplanar waveguide (CPW) region whose ground structure is defected by etching two rectangular annular slots. The purposes of both the corner-shaped parasitic elements and the rectangular annular slots of the CPW ground plane are to increase the impedance matching and the 3 dB axial ratio (AR) bandwidth, and to enhance the antenna efficiency. The design is achieved through complete parametric study to find the optimum dimensions of the antenna. A prototype of the proposed antenna is fabricated for experimental assessment of its performance. The results obtained by both simulation and experimental measurements show that the impedance matching bandwidth is about 5.3 GHz (8-13.3 GHz); the 3 dB AR bandwidth is about 3.1 GHz (8-11.1 GHz); the maximum gain ranges from 4.5 to 5.5 dBi; and the radiation efficiency is higher than 98% over the operational frequency band.

An optimization method utilizing a multistage genetic algorithm (MS-GA) and considering parameter variations has been proposed to obtain optimal design of one-dimensional dielectric bandgap(1D D-EBG) structures with a few periods in small packaging power distribution networks. One-dimensional finite method (1D FEM) is used to improve computational efficiency and iteration speed. MS-GA consists of 3 stages: In stage 1, the population was initialized by Hamming distance, and the fitness was calculated to determine the number of EBG period. In stage 2, genetic manipulation and sensitivity analysis were used to improve local search ability and obtain preliminary results. In stage 3, cubic spline interpolation and local integral were used to reconstruct the fitness evaluation function considering parameter deviation, adjust the results and obtain the optimal parameters. Three optimized target frequency bands with center frequencies of 2.4 GHz, 3.5 GHz and 28 GHz were optimized, and Pearson coefficient was used to analyze the correlation between the parameters to better understand the influence of parameter deviation on the optimization results. The achieved results meet the optimization object within the allowable range of parameter errors, and the parameter constraints were successfully met for all three designs, with their final dimensions below 20 mm. Three-dimensional full-wave simulation software was used to simulate and analyze the stopband bands, and the simulation results were consistent with the calculation results.

A 26 × 25 mm² arbitrary-shaped antenna is constructed in this article, and it was expanded to 2 x 2 Multiple Input Multiple Output (MIMO) antenna. It has a range of 3.1 to 8.2 GHz. A T-shaped stub is employed in this instance to reduce the mutual coupling between the two ports. The effectiveness of the MIMO aerial is demonstrated using envelope correlation coefficient and radiation pattern. Additionally, it has been shown that simulated and measured results generally agree.

In this paper, a novel magnetic gear motor (MGM) with nonuniform air gap Halbach array magnetization is proposed to study the influence of temperature change on its electromagnetic performance. The inner PM adopts the Halbach array magnetization structure, which makes the inner rotor air gap have an uneven air gap structure, thereby improving the air gap flux density. In addition, the air gap magnetic field of MGM is analyzed by the finite element method (FEM), and the 3D model of the motor is established. The main losses of the motor, including copper loss, eddy current loss, and hysteresis loss are coupled to each component as a thermal source and studied by magneto-thermal coupling. The transient variation characteristics of loss distribution during MGM operation are comprehensively considered. The temperature variation of each component of the MGM with time during load operation is studied in detail. The results show that the temperature of the PM of the MGM is close to 91.8˚C when the rated load is running, and the PM of the motor does not undergo irreversible demagnetization.

Multi-vector model predictive control (MPC) of permanent magnet synchronous motors (PMSM) has two issues: selecting the optimal voltage vector (VV) combination is very complicated, and multiple prediction calculations to minimize the cost function result in a heavy computational burden; applying a VV with a short duration may generate narrow pulses, while the effect of reducing torque ripples and stator current harmonics is not obvious. The hybrid-vector model prediction flux control (HV-MPFC) strategy considering narrow pulse suppression is proposed in this paper. First, the optimal VV combination is quickly identified by the sector where the stator flux error vector is located, which lowers the control complexity and computational burden. Secondly, by the relationship between the action time of three VVs and the set time threshold, the hybrid-vector strategy to switch among three VVs, two VVs, and a single VV is employed to prevent the generation of narrow pulses. Finally, experimental results show that, compared with the existing three-vector MPC strategy, the HV-MPFC strategy effectively suppresses the generation of narrow pulses and achieves smaller torque ripples and stator current harmonics at the same switching frequency.