The fast inverse Laplace transform (FILT) proposed by Hosono is recently applied to various transient response problems in electromagnetics. The frequency-domain methods have been the mainstream of electromagnetic simulation for many years, and a lot of knowledge has been accumulated. The FILT makes it possible to utilize frequency-domain techniques to transient analyses, and it is expected to provide reliable transient response analyses. Since the evaluation points of the image function in the conventional FILT depend on the observation time, the scope of application is sometimes limited when evaluation of the image function takes a relatively long computation time. This paper modifies the FILT so that the evaluation points are independent of the observation time, and the number of image function evaluations is reduced.

The reliability of DC-bus capacitors in six-phase drives is an important issue in multi-phase drive systems, and the influence of symmetrical and asymmetrical motor winding loads on the lifetime of DC-bus capacitors is essential. This article uses the SVPWM modulation algorithm to analyze the current and voltage ripple of DC-bus capacitors in a six phase voltage source inverter. Then, by optimizing the capacitance value when searching for the maximum stress point, the capacitance range of DC-bus capacitors is determined. At a power factor of 0.6 and modulation ratios of 0.4, 0.7, and 0.9, considering the changes in ESR, current, and voltage ripple in the capacitor, taking 80% of the rated lifespan as an example, it is found that the lifespan of the DC-bus capacitors in symmetrical configuration of the motor winding is increased by 0.20%, 1.80%, and 10.08% compared to that in asymmetric configuration, respectively. Finally, the analytical and experimental results were compared with existing methods, and the experimental results verified the effectiveness of the proposed method.

Focused arrays are attracting increased interest because of their wide range of applications. Focusing the antenna's radiation in the near field requires proper phase distribution of the array elements that must be fed through many phase shifters. This work presents a design idea for a focused circular array antenna, whose focal distance can be varied by only a single variable phase shifter. The idea is implemented on a dual-ring circular array having a six-wavelength diameter and focused at five wavelengths by using a single fixed phase shifter. Theoretical analysis and computer simulations of a sample design using MATLAB and CST Microwave Studio show that a phase change of 0.9π leads to a four-wavelength change in the focal distance. A formula for the estimation of the depth of field DOF is derived. The proposed array offers a simple method to vary the focal length continuously by a single variable phase shifter. This idea can be utilized in hyperthermia, RFID, and imaging applications, where the position of the focal spot needs to be moved along the normal to the array.

Sepsis is a life-threatening infectious disease. Mitochondrial dysfunction is widespread in severe sepsis. The myocardium contains a large number of mitochondria, and the survival rate of sepsis decreases sharply when cardiac dysfunction is involved. Vericiguat (BAY 1021189) is a novel drug for the prevention of heart failure. In this study, we evaluated the mitochondrial function of septic mice and drug-treated mice by resonance Raman spectroscopy (RRS). RRS can accurately identify the Raman characteristic peak at 750 cm^-1, 1128 cm^-1 and 1585 cm^-1 attributed to the reduced cytochrome in septic mice. We found that the intensity of the characteristic peak was significantly decreased in septic mice, indicating an imbalance of mitochondrial redox function, while the function was improved in the drug-treated group. It proves that BAY has the potential as a novel treatment for mitochondrial dysfunction in sepsis.

A coaxially pin-fed multiband fractal square antenna is proposed in this paper. The designed antenna resonates in five bands: 5 GHz, 10 GHz, 13.2 GHz, 16 GHz, and 20.5 GHz. This multibands are achieved by using a fractal square antenna. The fractal square is formed from an initial square patch and then optimized with increasing fractal iterations to resonate at these bands. The fractal property of the design also helps in the miniaturisation of the antenna. The proposed antenna has gain ranging from 4.9 dB to 9.7 dB and radiation efficiencies from 70% to 98%. The proposed antenna is simulated using the CST microwave studio. The antenna is then fabricated, and its performance parameters are measured. After finding a match between simulated and measured results, the same antenna and its array are tested in a MATLAB simulation environment for direction of arrival (DOA) and adaptive beam forming (AB) at all five bands. Using different DOA and AB algorithms, the performance of the antenna array is evaluated. The ability to accurately estimate the DOA of all signals delivered to the adaptive array antenna allows it to maximise its performance in terms of recovering the required transmitted signal and suppressing any interference signal. Then, the beam of the antenna is modified using the DOA algorithm to generate a beam in the desired direction and nulls in the unwanted direction for proposed satellite communications.

In this research work, a low-profile microstrip patch antenna has been designed with broad circularly polarized resonant bandwidth. The designed antenna consists of an equilateral triangular-shaped radiating patch with two triangular coplanar parasitic elements along with a square-shaped ground plane. The unique feature of this antenna design is a generation of circularly polarized radiation by only optimum corner truncation of the two parasitic elements along with a small portion of the driver patch. The designed antenna can be used for (5.725-5.850 GHz) WLAN and (5.85-5.925 GHz) dedicated short-range communication applications with circularly polarized radiation property. The overall resonant bandwidth for (S₁₁ ≤ -10 dB) is 1.52 GHz 24.75% with a frequency range (5.38-6.90 GHz), and the circularly polarized resonant bandwidth for (Axial ratio ≤ 3 dB) is 240 MHz 4.13% with a frequency range (5.69-5.93 GHz). The gain of the antenna is 4 dB at 5.81 GHz and almost remains the same for the entire resonant bandwidth. The complete design of the antenna has been done using theoretical calculation and HFSS ver13 simulation software. After that, it has been fabricated, and different parameters have been measured using Vector Network Analyser. It has been found that the measured results are very much similar to the simulated results.

This study investigates beamforming and optimization in Multiple-Input-Multiple-Output Orthogonal-Frequency-Division-Multiplexing (MIMO OFDM) radar systems. The objective of this research is to mitigate the range-angle coupling effect in MIMO OFDM radar systems by adopting range compensation and distance-angle decoupling methods, which is to ensure that the signal processing during radar waveform formation does not impact the aforementioned coupling effect. In distance compensation, the CVX toolbox is used to minimize peak sidelobe after distance compensation is performed in the angle dimension. A mathematical model is established, and an optimal set of transmission frequencies is achieved through the use of the Alternating-Direction-Method-of-Multipliers (ADMM) algorithm in the context of distance-angle decoupling. Both methods effectively eliminate distance-angle coupling and enhance detection and identification capabilities of MIMO OFDM radar systems.

This research extends the theory of binomial array antennas. A closed-form expression for the half-power beamwidth of the array factor of an array antenna is presented. The expression is correct for the ratios of element spacing to wavelength greater than or equal to one quarter. Also, exact equations for determining the half-power beamwidth for main-beam steering are derived. A comparison with an approximate formula for the half-power beamwidth of binomial array antennas is carried out.

In the paper, a wideband circularly polarized (CP) filtering antenna is proposed, which is composed of four bent Vivaldi elements excited with sequential-rotated feeding technique. Since the Vivaldi element has the advantages of high gain and wide bandwidth, it is selected as the radiation element. On this basis, two cross slots are etched on the Vivaldi antenna to increase the gain at lower frequency band, and bent method which has less effect on the overall performance is applied for lowing the profile of the antenna. To realize filtering characteristic, the quadrature four-feed network consisting of one modified miniaturized filtering rat race coupler (FRC) and two compact wideband quadrature couplers is utilized as the sequential-rotated feeding for the Vivaldi elements. Design procedures of the Vivaldi antenna, the modified filtering FRC and the quadrature four-feed network are given. For validation, a prototype is fabricated and measured. Results show that more than 60% fractional bandwidth (FBW) is achieved under the criterions of more than 10 dB return loss and less than 3 dB axial ratio. Within the AR bandwidth, the gain is in the range of 7.5 dBic~10.1 dBic. Out of the operation band, the gain sharply decreases to be lower than -5 dBic with a rectangle coefficient (|Normalized Gain_-10-dB/Gain_0-dB|) of 1.25, which indicates good filtering performance.

A novel miniaturized high-gain Vivaldi antenna printed on a thin substrate is proposed for operation as multi-band antenna for millimeter-wave applications. The present work proposes a novel geometrical design of the Vivaldi antenna that is printed on the opposite faces of a thin dielectric substrate. The antenna has compact size, and its dimensions are optimized to enhance the performance regarding the bandwidth of impedance matching, gain, and radiation efficiency. To maximize the gain within a desired frequency band, each arm of the Vivaldi antenna is loaded by a ring-shaped parasitic element. The results of the parametric study for antenna design optimization regarding the enhancement of the impedance matching bandwidth and the antennas gain are presented and discussed. Also, it is shown through parametric study that the size and location of the parasitic rings can be optimized to enhance the antenna gain over the desired frequency range. The multiband operation of the proposed Vivaldi antenna is explained in view of the multimode operation that is illustrated by the distributions of the surface current on the antenna arms and the electric field in tapered slot. A novel microstrip line/parallel-strip line balun structure is proposed for feeding the balanced Vivaldi antenna and to achieve wideband impedance matching. The proposed Vivaldi antenna is fabricated and subjected to performance evaluation through measurements. It is shown that the antenna impedance is matched to 50 Ω over the four frequency bands: 22.0-27.7 GHz, 32.0-37.5 GHz, 41.5-46.6 GHz, and 51.7-56.7 GHz. The corresponding bandwidths are 5.7, 5.5, 5.1, and 5.0 GHz, respectively with percent bandwidths of 23%, 16%, 11.6%, and 9.2%, respectively. In spite of its compact size, the achieved values of the maximum gain are 6 dBi, 9 dBi, 11.4 dBi, and 12 dBi over the mentioned frequency bands, respectively. Also, the corresponding values of radiation efficiency are 98%, 97%, 95%, and 93%, respectively. The proposed Vivaldi antenna is fabricated and subjected to measurement for experimental investigation of its performance. The measurement shows good agreement with the simulation results.

A novel flexible printed monopole antenna with a windmill-shaped fractal design, which is fed by co-planar waveguide (CPW) is presented in this manuscript for ultra-wideband (UWB) applications. By integrating a modified windmill-shape fractal into the conventional irregular hexagonal-patch, the antenna achieves a significantly wider impedance bandwidth extending up to 156.6% across the frequency band of 1.37-11.25 GHz. Additionally, increasing the number of the windmill-shaped fractals leads to the emergence of further resonances. The overall dimensions of the designed antenna are 50 × 70 × 0.2 mm³, and it boasts an impressive bandwidth-dimension ratio (BDR) of 4457, showcasing exceptional efficiency in utilizing its compact size. The maximum gain reaches 4.8 dBi, while the radiation efficiency attains an impressive 98%. The modified windmill-shape fractal antenna design leverages the multifractal concept, providing monopole antennas with enhanced flexibility in controlling resonances and bandwidth. This manuscript offers a comprehensive presentation and discussion of the process used to improve the impedance bandwidth, shedding light on the antenna's exceptional performance and capabilities.

Circularly polarized gap-coupled designs of corner truncated square microstrip antenna in 2400 MHz frequency spectrum are presented. The gap-coupled design on thinner substrate (~0.036λ_g) yields axial ratio bandwidth of 113 MHz (4.697%) whereas that on thicker substrate (~0.13λ_g) yields axial ratio bandwidth of 471 MHz (19.24%). Both the designs exhibit broadside radiation pattern with a peak gain above 7 dBi, thus satisfying the requirements of WLAN and Bluetooth applications. Simulated results have been experimentally verified, which show close agreement.

In this paper, reactive impedance surface metasurface (RIS-MS) and negative refractive index metasurface (NRI-MS) are used to design a wideband, high gain, circularly polarized slot loaded patch antenna (SLPA) for 5 GHz WI-FI applications. The RIS-MS is utilized to improve the antenna's bandwidth. It is composed of 6×6 metallic circular patches that are periodic. To improve bandwidth, the RIS-MS is placed between the SLPA and ground plane of a conventional antenna. A metasurface lens composed of 6×6 periodic NRI metamaterial unit cells enhances the gain of the antenna. The NRI-MS superstrate is positioned at the optimal height above the conventional antenna. A prototype of the proposed antenna has been fabricated and measured experimentally. The prototype has an impedance bandwidth (IBW) of 21.7% (5.12-6.37 GHz), a 3-dB axial ratio bandwidth (ARBW) of 18.2% (5.19-6.23 GHz), and a gain of 13.5 dBic.

A design of a series-fed antenna array without beam deterioration using miniaturized bandpass filters (BPFs) is proposed. The BPFs are connected behind branches of series feed network (SFN) to compensate the varied phase slope of paths, resulting in constant phase difference between elements across the bandwidth. Hence, the beam deterioration versus frequency is removed. The closed-form equations of the phase slopes for BPFs are deduced, and thus they can be designed quantitatively for phase slope balancing. The proposed SFN has advantages of compactness, simplicity, and low loss. For validation, an 8-element antenna array is designed and measured. The gain and sidelobe level are 12.2-12.39 dBi and 11.67-12.65 dB within the bandwidth of 5.2-5.8 GHz. As comparison, the gain and sidelobe level are 12.85-13.77 dBi and 7.18-12.75 dB using conventional feed network. Therefore, the designed antenna array has stable radiation pattern including beam direction, sidelobe level, and gain.

This paper presents a simple approach for evaluating the complex magnetic permeability of the steel fibers used in concrete according to frequency. The approach utilises the eddy current non-destructive evaluation method, where the electrical impedance is measured using a precision LCR meter and computed using a magneto-harmonic model solved in Py-FEMM software. Initially, the electrical conductivity of the steel fiber is measured using a two-contact DC method. Then, the inverse problem method is applied to identify the complex magnetic permeability. This is achieved by iteratively minimising the difference between the calculated and measured impedances using a simplex optimization algorithm. The proposed approach offers a non-contact, non-destructive, fast, and efficient procedure to evaluate the complex permeability. The obtained results provide valuable insights into evaluating the distribution of steel fibers in concrete.

The research on landslide displacement prediction can help the early warning and prevention of landslide disasters in mining areas. In view of the problem that BP neural network is prone to local convergence, and considering that the network trained based on time-series cumulative displacement may produce large errors in prediction, this paper proposes a method combining displacement increment and CS-BP (Cuckoo Search-Back Propagation) neural network to predict landslide displacement. Compared with the conventional landslide displacement prediction methods, this method uses displacement increment instead of the commonly used cumulative displacement as the network input data, and selects the CS algorithm with few parameters and easy to implement to optimize the BP network to construct the prediction model, and predicts the corresponding amount of displacement change at the next moment by the historical landslide displacement increment. Combined with the measured data of three feature points of a mine in Xinjiang, China, obtained by the micro-deformation monitoring radar, the displacement prediction accuracy of the proposed model on the three measured data sets is compared with the prediction accuracy of the BP, GA-BP (Genetic Algorithm, GA), and FA-BP (Firefly Algorithm, FA) network prediction models based on cumulative displacement and incremental displacement, respectively. The experimental results show that this method achieves superior performance with an average root mean square error of 0.3261 and an average mean absolute error of 0.2785 across the three feature points, outperforming the other models, and holds promising applications in disaster prevention and control work.

This article presents a miniaturized octa-port high gain multiple-input-multiple-output (MIMO) antenna loaded with an electromagnetic band gap (EBG) layer for the use in 5G wireless communication applications. Each resonator of the presented antenna is comprised of a rectangular-like patch with truncated side edges and a partial ground plane. A layer of EBG unit cells is introduced underneath the antenna elements to increase the gain and restrain the surface wave effects, obtaining improved isolation amongst the resonating elements. The -10 dB impedance bandwidth of the prospective antenna with EBG is 12 GHz (21-33 GHz), and it provides isolation of >28 dB. The peak gain of the EBG-backed antenna is 17 dB. The presented mm-wave MIMO antenna offer decent diversity proficiency metrics like envelope correlation coefficient (<0.36), diversity gain (~10 dB), and total active reflection coefficient (-24.75 dB). The overall size of the octa-port MIMO antenna is 27.2 mm × 27.2 mm. The presented MIMO antenna could be used for n257/n258/n261 mm-wave bands.

In standard measurement methods such as NSA 94-106, the low-frequency magnetic shielding effectiveness of a shielding enclosure is tested using the near field of loop antenna. Under this near-field configuration, there is no analytical or closed-form solution for volumetric shielding like box/cavity except for planar shielding like a sheet of infinite extension. Exploring the correlation between volumetric shielding and planar shielding can provide simple prediction methods for volumetric shielding based on planar shielding. As a taste to this end, this article explores the difference between the shielding effectiveness of a double-sheet cavity and a single sheet under the NSA 94-106 standard. We derived the exact solution in integral form for electromagnetic fields inside the cavity and calculated the curves of shielding effectiveness on the frequency with different sheet material, thickness, and sheet-to-sheet distance. The results show that when the distance from the receiving antenna to the back sheet is greater than the diameter of the loop antenna, the results of a double-sheet cavity tend to be consistent with a single-sheet configuration. When the distance is less than the diameter, the difference between the two depends on material type and sheet thickness.

A novel microstrip loop-type resonator with four resonant modes is proposed in this letter. The resonator is formed by a loop-type microstrip line loaded with four shorted stubs. It has a symmetrical structure, thus the odd-even-mode method is adopted to implement the resonant analysis. The novelty of the proposed resonator lies in two aspects. One is that its resonant frequencies can be adjusted in a more flexible way. The other is that its resonant modes have a uniform electromagnetic field distribution, which is beneficial for the excitation of resonant modes. For the purpose of demonstration, based on the novel resonator, a single-band bandpass filter with four transmission poles and a dual-band bandpass filter with two transmission poles in each passband are constructed. Additionally, source-load cross coupling is introduced, and several transmission zeros are generated in the stopband, which improves the out-of-band performance greatly. The designed single-band filter has the central frequency of 2.4 GHz and fractional bandwidth (FBW) of 4.5%, and the dual-band filter has the central frequency of 1.8/2.4 GHz and fractional bandwidth of 2.0%/2.5%. The two bandpass filters are designed, fabricated, and measured. Agreement between the simulated and measured results verifies the effectiveness of the proposed resonator and filters.

Using realistic classical models of microscopic electric-charge electric dipoles and electric-current (Amperian) magnetic dipoles, it is proven that the Einstein-Laub macroscopic electromagnetic force on a macroscopic-continuum volume of these classical dipoles equals the sum of the microscopic electromagnetic forces on the discrete classical dipoles in that volume. The internal (hidden) momentum of the discrete Amperian magnetic dipoles is rigorously derived and properly included in the determination of the macroscopic force from the spatial averaging of the microscopic forces. Consequently, the Abraham/Einstein-Laub rather than the Minkowski macroscopic electromagnetic-field momentum density gives the total microscopic electromagnetic-field momentum in that volume. The kinetic momentum is found for the volume of the macroscopic continuum from Newton's relativistic equation of motion. It is shown that the difference between the kinetic and canonical momenta in a volume of the macroscopic continuum is equal to the sum of the ``hidden electromagnetic momenta'' within the electric-current magnetic dipoles and within hypothetical magnetic-current electric dipoles replacing the electric-charge electric dipoles in the classical macroscopic continuum. To obtain the correct unambiguous value of the force on a volume inside the continuum from the force-momentum expression, it is mandatory that the surface of that volume be hypothetically separated from the rest of the continuum by a thin free-space shell. Two definitive experiments performed in the past with time varying fields and forces are shown to conclusively confirm the Einstein-Laub/Abraham formulation over the Minkowski formulation.