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The attenuation of high‐frequency seismic waves was investigated in the crust beneath Tbilisi and the surrounding territory by analysing 225 local earthquakes that occurred from 2008 to 2020 and were recorded by eight seismic stations. The quality factors of coda waves QC and direct P and S waves, QP and QS, were estimated using the single backscattering model and the extended coda normalization method, respectively. The separation of intrinsic quality factors Qi from scattering quality factor QSC was fulfilled by Wennerberg's method. Observed results show that all evaluated attenuation parameters are frequency‐dependent in the frequency range of 1‐32 Hz and increase with increasing frequency. Coda QC values increase also with increasing lapse time window from 20 s to 50 s and vary from 91 ± 5 at 1.5 Hz to 1779 ± 108 at 24 Hz, respectively. P waves attenuate slightly faster than S waves, and the ratio of QS/QP is more than unity and varies in a range of 1.5‐1.8. The intrinsic and scattering quality factors are expressed by the following power laws: Qi = (77 ± 4)f(0.930 ± 0.046) and QSC = (219 ± 6)f(0.924 ± 0.050). The results show that Qi is close to QC, but QSC is larger than Qi, which means that intrinsic attenuation has a dominant role compared with the scattering effect. Our results were compared with those obtained in two other seismically active regions of Georgia, as well as with regions of the world. In general, the observed quality factors and their frequency‐dependent relationships follow a similar trend, characterizing seismically active regions with complex tectonics. The calculated attenuation parameters characterize the entire earth's crust under Tbilisi and the surrounding area. The results obtained will be useful in future seismological studies since the Q parameters are estimated for the first time for the given region. [ABSTRACT FROM AUTHOR]

Improving indoor air quality through the use of air purifiers has become a major focus, with emphasis on developing filters with high efficiency, high holding capacity, and low-pressure drop to improve the clean air delivery rate (CADR) for air purifiers. However, although most studies focused on developing media and evaluating their performance, few studies have reached the employment for a pleated filter. In this study, we newly synthesized flat media and pleated filters by combining polytetrafluoroethylene membrane (PT) and melt-blown (MB) materials (PM) and compared its initial performance to that of other air purifier filters (MB, glass fiber, and PT). Additionally, we analyzed how the performance changed after the particles were loaded. The initial efficiency of the PM filter showed a higher quality factor (QF) than the other filters. Furthermore, when more particles were loaded, the penetration of the PM did not change. These results demonstrate the potential of the PM. However, the CADR and submicron-sized (0.02–0.113 μm) CADR (sCADR) were highest for the MB filter due to the initial pressure drop. Therefore, additional improvements are required to apply the PM in air purifiers. However, the results suggest that the PM can be a new alternative for air purifier filters used in medical centers or facilities with vulnerable populations where a high-efficiency particle air (HEPA) filter must be used. [ABSTRACT FROM AUTHOR]

Railway axle box bearing fault signal contains high Q-factor resonance and low Q-factor transient shock components with periodic transient shock features that can characterize bearing faults. However, extracting fault features is usually difficult due to noise, transmission paths, and high-amplitude accidental shocks. Therefore, to address the abovementioned problems, the multilevel feature extraction method for adaptive fault diagnosis of railway axle box bearing was proposed. This paper used the maximum second-order cyclostationary blind convolution (CYCBD) to weaken the influence of disturbances, enhancing weak transient shock components. Resonant sparse decomposition(RSSD) is used for the selection of quality factor Q due to its excellent fault feature separation property. Considering the strict fault frequency component periodicity in the envelope spectrum, the envelope spectrum multipoint kurtosis (ESMK) is proposed as a metric. The Q factor is optimized using the gray wolf optimization algorithm (GWO) to obtain an adaptive sparse decomposition method (GWO-RSSD) for extracting bearing transient fault shocks to eliminate the signal effects of high-amplitude disturbance shocks and background noise. The simulation results and measured signal analysis of railway axle box bearing show that ESMK can effectively measure periodic transient shocks under strong shock interference compared with the MED-RSSD method. Thus, GWO-RSSD can adaptively separate the optimal low-Q resonance components, verifying the methods' effectiveness and superiority. [ABSTRACT FROM AUTHOR]

Boise sandstone has a variety of grain diameter, and the heterogeneity makes it difficult to characterize. In this paper, a model of viscous squirt is used to simulate velocity and attenuation of ultrasonic P-wave in the sandstone saturated with water. Phase velocity yielding from the model is fitted against the velocity measured at frequency of 500 kHz, which determinates the quality factor due to viscous squirt ( Q p s ) as a function of frequency. The resulting Q p s appears to be 14.64 at frequency of 0.8 MHz. With the use of the measured total quality factor ( Q p ) of 6.9 at 0.8 MHz, the dry quality factor ( Q p d ) appears to be 13.0 at 0.8 MHz. The resulting dimension of the rock unit is 0.150 multiplied by 0.140 mm, pretty consistent with the mean grain diameter of 0.150 mm. The relative first and second porosities are ascertained to be 0.976 and 0.024, respectively, and the aperture distance of the second porosity is 0.84 μm. Nonetheless, the model represents analytical continuation of small rock samples. Consequently, seismic attenuation predicted by the model is far smaller than field observation. The discrepancy shows that strong seismic attenuation in the field is associated with a scale much larger than pore scale. [ABSTRACT FROM AUTHOR]

Based on the simplicity of the design method, this paper presents a new approach for developing matched subbands when splitting two mismatched dual-wideband bandpass filters (BPFs) for the fifth generation (5G), wireless access systems (WAS), wireless fidelity (Wi-Fi), worldwide interoperability for microwave access (WiMAX), wireless local area network (WLAN), radar, and other communication devices. The method's novelty involves using identical quarter-wavelength resonators terminated by alternated short-and-open stub configurations. Both configurations alternate and describe a perfect symmetry by their location from each other to make the subbands possible in the low-frequency and its harmonic (high-frequency) bandwidths (BW). A stub admittance Y 1 is defined and associated with the mainline section characteristic impedance Z 0 and an operating frequency f 0 . A quality factor Q a p is connected to Y 1 and f 0 to approach the BPF global quality factor Q g initially fixed. The stub characteristic impedance and the mainline one differ, while electric lengths (stub and mainline section) are identical. Using the operating frequency determines physical dimensions, creates harmonic frequencies and the rejected BW, mismatches the main frequency BW, matches the subbands, and creates transmission zero (TZ). Hence, a 28.118-dB stopband that separates the two bandpasses at 9.373 GHz is made. At the same time, the unmatched dual ultrawideband (UWB) covers a large panel of communication systems. The lowest (3.146–5.431) and highest (11.891–14.749) GHz BW exhibit a minimum insertion loss (IL) of 0.656 dB and 3.027 dB. The subbands return losses (RL) are better than 28 dB and 19 dB, respectively, and a flat group delay of 0.205 ns is obtained in the upper band. All subbands adaptation methodology is read from 10 dB of the RL. In that case, the four matched subbands in its lower wideband are 3.327–3.709 GHz and 4.442–5.048 GHz, and in its higher wideband are 11.922–12.486 GHz and 14.281–14.653 GHz. The 2275/2858 MHz is the dual-wideband with a fractional BW 53.282/21.456%. The fabricated prototype has validated the EM-simulations, and Anritsu MS4642B 20 GHz vector network analyzer (VNA) has been used for experimental results by scanning the frequency range 3 GHz–15 GHz. The tested prototype is made with a 1 mm FR4 HTG-175 thickness by considering a dielectric constant of 4.4, and its overall size occupies 22.45 × 5.72 m m 2 (0.32 λ 0 × 0.082 λ 0 mm 2 ). [ABSTRACT FROM AUTHOR]

This numerical work proposes two novel designs of long-range surface plasmon resonance sensors (LRSPR) using two different coupling prisms. The performance analysis of the proposed sensor has been investigated using the performance parameters like quality factor (Q), detection accuracy (DA), sensitivity (S), and full-width half maximum (FWHM). The transfer matrix method (TMM) has been employed to compute reflectance. The role of the basic recognition element (BRE) has been played by the popular two-dimensional (2D) material, black phosphorus (BP), due to its many optoelectrical features. The maximum obtained values for Q , DA, and S are 3333.25 1 / RIU , 250 degree − 1 , and 13.33333 degree/RIU for 2S2G coupled sensor design and 3055.5 1 / RIU , 83.33 degree − 1 , and 36.66667 degree/RIU for BK7 coupled sensor design. The operating wavelength of 633 nm, followed by the principle of attenuated total reflection (ATR), has been employed to carry out the theoretical investigation. [ABSTRACT FROM AUTHOR]

This paper presents a transmission line and a split ring resonator (SRR) based sensor structure with a high sensitivity capacity to discriminate various methanol mixtures. The height of the dielectric layer and thickness of copper are assigned as 1.6 mm and 0.035 mm, respectively. The overall dimensions of the sensor structure are defined as 16 mm × 16 mm × 1.6 mm. The operating frequency is selected for the ISM bands, especially around 2.45 GHz. Different methanol-water mixtures are prepared at various ratios, and then, the complex permittivity values are measured. Different sensor structures are modelled and investigated using a two-port transmission line approach. Various types of SRR based sensors are designed, and an optimum design is proposed for methanol mixture detection applications. The observed quality factor of the proposed sensor is 16.5. The resonance shifts of the transmission value ( S 21 ) are used for sensing capability around 2.45 GHz at -45 dB and 90 MHz resonance shifts. The sensitivity of the sensor has been evaluated as 1 MHz. Finally, the electric field distributions of the proposed SRR integrated transmission line are investigated. The novelty of the proposed design is to exactly sense the ratio of methanol in water with a very simple design. The proposed sensor structure can be used for methanol detection applications in medical, military, and chemical research. [ABSTRACT FROM AUTHOR]

In this article, a novel systematic method for compensation of the simultaneous amplitude and group delay (GD) flatness in the narrowband bandpass filters is proposed. The proposed technique can be used systematically in any type of filters with the possibility of resonator quality factor adjustment. This technique is presented using an RLC resonator equalizer in two steps. First, the compensation of the GD response is accomplished by tuning the external Q‐factor, then the amplitude response is compensated by adjusting the resonator Q‐factor. To verify this technique, design and fabrication of a TM dual‐mode equalizer for joint compensation of the amplitude and GD responses in a narrowband waveguide filter is presented. The simulation results for a novel TE dual mode equalizer is also presented. The passband response of an un‐equalized narrowband filter with passband flatness of 1.5 dB amplitude and 55 ns GD at the center frequency of 10.970 GHz is improved to 0.5 dB amplitude flatness and 30 ns GD flatness. This improvement is achieved at the cost of passband insertion loss. The designed equalizer is fabricated and tested and the measurement results, after and before equalization, prove the design technique capability. [ABSTRACT FROM AUTHOR]

This research study aims to measure the study analysis on the path of artisan spirit related to party education related to the ideological in colleges and universities. The image processing technology research study describes that primary data related to the artisan spirit performance were gathered using different questions related to the image processing technology. The party ideological education is the dependent variable, and image processing technology includes segmentation quality factors and performance related to the image processing technology. These are considered independent variables. For measuring, the data used AMOS software and run different results related to the party ideological education in college and universities. The character design major has more significant commercial benefits and chances for growth. The investigation and analysis can confirm that the main is appropriately orientated. It maintains continual communication with companies, scheduling, increasing students' practical competence, and also offers students internship opportunities. The overall results found that the artisan path to party ideological education significantly relates to college and universities based on the image processing technology. [ABSTRACT FROM AUTHOR]

The frequency-dependent parameters of attenuation of P and S waves in one of the most seismically active regions, of the Javakheti plateau, have been estimated using digital data for the first time. We have analyzed and processed hundred and fifty local shallow earthquakes that occurred from 2006 to 2018 and were recorded by five seismic stations. The quality factors for P waves ( Q p ) and for S waves ( Q s ) were evaluated by means of the extended coda normalization method. The obtained Q p and Q s are strongly frequency dependent in the frequency range of 1.5 to 24 Hz, and increase with frequency according to the following power laws: Q P = 17.4 ± 2.3 f 1.100 ± 0.033 and Q S = 28.8 ± 3.3 f 1.048 ± 0.039 . The observed Q s / Q p ratio was found to be greater than unity over the entire frequency range, suggesting that scattering may play the main role in the attenuation of body waves on the Javakheti plateau. The frequency dependence of the S wave is very similar to the frequency dependence of the shear wave for another seismically active region of Georgia, the Racha area. A comparison of our results to those other regions of the world shows that among the seismically active areas, the Javakheti plateau is characterized by relatively low values of Q p and Q s , but they are more than volcanic regions such as Etna and Qeshm Island, Iran. The observed results characterize the entire earth's crust in the study area and will be useful for source parameter estimation, ground motion prediction, and hazard assessment of the Javakheti plateau. [ABSTRACT FROM AUTHOR]

This article tries to address the unstable radiation pattern issue of the planar‐coupled patch antennas with two different methods. First, characteristic mode analysis (CMA) reveals that the coupled patch antennas generate three characteristic modes with distinctive radiation patterns. A slot‐loading scheme is proposed to reshape the current distribution of the higher mode and reduce its sidelobe level significantly. Then a 13.4% bandwidth with consistent radiation patterns and high gain is achieved by exciting modes 1 and 3 while suppressing unwanted modes with an aperture‐coupled feeding. Second, the radiation pattern stability of the coupled patch antennas is further improved by employing shorted parasitic patches. The presented antenna can be equivalent as the same magnetic current array model under the in‐phase and out‐of‐phase modes, and thus the radiation patterns hardly get changed. Moreover, the non‐radioative nature and high radiation quality factor of the higher mode improve the radiation performance in a new principle. It not only enhances the bandwidth up to 18.5% but also results in a sharp filtering edge of gain response. [ABSTRACT FROM AUTHOR]

A dual‐mode dielectric resonator based on printed circuit board (PCB) technology formed bandpass filter is proposed for relatively wide bandwidth under low quality factor. By using the low dielectric constant substrate itself to become the core part of the two coupled dual‐mode resonators through the PCB process, the proposed design can share the same substrate with other PCB circuits and reduce the installation error. Moreover, benefiting from the dual‐mode (TE111y mode and TM111z mode) resonator realized by low dielectric constant substrate with low quality factor, the proposed design exhibits the features of low cost and wide bandwidth. A prototype with the center frequency (f0) of 13.85 GHz was demonstrated, which shows the 3‐dB fractional bandwidth of 8.34% and the minimum insertion loss of 1.29 dB. [ABSTRACT FROM AUTHOR]

Mutual fund is one of the most popular investment programs, especially among small investors. Currently, many mobile-based applications are available, facilitating the buying and selling of mutual funds. This number of choices creates competition between application developers, pressuring them to find ways to maintain user loyalty by increasing user retention rates. However, only a few studies have currently discussed user retention in mutual fund investment applications. Furthermore, previous studies never examined the quality factor of the application but instead focused more on other factors outside the application. This study analyzed the factors influencing user retention on mutual fund investment applications in Indonesia from the application's quality and usability aspects. This study was based on the expectation-confirmation model (ECM) as the underlying theory. Data were collected using a survey questionnaire resulting in 414 responses, which were then processed and analyzed using the covariance-based structural equation modeling (CB-SEM) technique. The results of this study indicate that three variables can directly affect user retention in mutual fund investment applications: satisfaction, perceived usefulness, and perceived enjoyment. The satisfaction variable had the most significant influence of these three variables. Several factors influenced satisfaction: perceived usefulness, enjoyment, ease of use, trust, confirmation, prompt response, and security. [ABSTRACT FROM AUTHOR]

The performance of an air purifier is determined by its clean air delivery rate (CADR), expressed as the product of the air flowrate and filter collection efficiency. A high CADR in a commercial air purifier is achieved using a pleated air filter with high filtration performance at a given air flowrate. However, obtaining this high filtration performance depends on the knowledge of the manufacturer, including the optimal pleating design, which remains uncertain to date. In this study, test pleated filters were prepared by folding a flat electrostatically‐charged E12 filter medium to obtain different pleating geometries. The proper pleat geometry of the pleated filter, which has a minimum pressure drop at a fixed air flowrate, was dependent on the pleat length (PL) and pleating ratio (α = pleat height/pleat width), wherein as the PL increases, the α range required to achieve a minimum pressure drop similarly increases. Based on the filter quality factor (qF), the optimal pleat geometry of a pleated filter was between α values of 6–8, irrespective of the PL. Although both PL and α have certain influences on the qF, α has a greater influence on the pleated filter with no dead zone. [ABSTRACT FROM AUTHOR]

Silicon nanowires (SiNWs) are promising structures as resonators for applications in ultrasensitive force and mass transducers. In the present work, large-scale molecular dynamics simulations were conducted to explore the effect of gold (Au), a commonly used catalyst, on the vibrational properties of [1 0 0] and [1 1 0] SiNWs. The force field was established using the modified embedded atom method (MEAM) formalism. The parameterization focused on the properties of the hydrogen-covered SiNWs doped with Au, involving the formation energy as well as the structural and vibrational characteristics. The vibrational characteristics of a clamped-clamped SiNW were examined through excitation using a sinusoidal velocity field after energy minimization and thermal equilibration. Different doping concentrations and distributions can significantly change the frequency response, quality factor Q , and beat phenomenon. The natural frequency f 0 decreased with increasing Au concentration, whereas the effect of the impurity distribution on f 0 was negligible. Furthermore, Q was sensitive to the Au concentration and distribution, and the increased concentration led to an overall increment in Q , accompanied by considerably increased scattering. Besides, the beat period of [1 1 0] SiNWs showed a strong positive correlation with the concentration. The vibration along the elementary axes cannot produce the beat phenomenon. Deflection of the elementary axes in a very small range would lead to a higher energy dissipation rate. In addition, owing to the considerable difference between the atomic masses of Au and Si, randomly distributed Au atoms significantly disturb the symmetry of the SiNWs. However, the elementary axes of the [1 1 0] SiNWs remained stable, even in the models with extremely radial or longitudinal impurity segregation. In contrast, we failed to capture the distinguishable elementary axes for most of the doped [1 0 0] samples. The features described above indicate that the impurity Au can effectively tune the resonant frequency of the [1 1 0] SiNWs, meanwhile, causes no large frequency shift that could be potentially caused by the deflection of the elementary coordinate system. [ABSTRACT FROM AUTHOR]

In order to optimize the sensitivity and detection accuracy of Fano resonance optical sensors, a sensing model of graphene-grating composite micro-nanostructure with high sensing performance is proposed based on the optical properties of graphene and grating. By studying the reflection spectra and field distribution characteristics of the structure, the sensing mechanism of Fano resonance generated by the structure is elaborated, and the parameters affecting the Fano resonance sensing performance are analyzed to enhance the Fano resonance sensing performance by optimizing the structural parameters, and the Fano resonance reflection spectral curve with high-sensitivity and high-quality factor (FOM) value is obtained. The results show that when the grating period P = 300 nm, the grating height T1 = 110 nm, and the silver film thickness T2 = 30 nm, the sensitivity of the structure is 980 nm/RIU and the quality factor FOM is 770RIU−1 by changing the refractive index of the material to be measured. [ABSTRACT FROM AUTHOR]

The airliner cabin environment is very important to the health of passengers and crew members, and the use of high‐efficiency particulate air (HEPA) filters for recirculated air in the environmental control systems (ECS) is essential for the removal of airborne particles such as SARS CoV‐2 aerosols. A HEPA filter should be high efficiency, low‐pressure drop, high dust‐holding capacity (DHC), lightweight, and strong for use in aircraft. We conducted an experimental study on 23 HEPA filters with glass fiber media that are used in different commercial airliner models. The tested filters had a median filtration efficiency of >99.97% for particles with a diameter of 0.3–0.5 μm, a pressure drop of 134–412 Pa at rated airflow rate, and a DHC of 32.2–37.0 g/m2. The use of nanofiber media instead of glass fiber media can reduce the pressure drop by 66.4%–94.3% and significantly increase the quality factor by analysis of literature data. The disadvantages of poor fire resistance and small DHC can be overcome by the use of flame‐retardant polymers and fiber structural design. As a new lightweight and environmentally friendly filter material, nanofiber media could be used as air filters in ECS in the future. [ABSTRACT FROM AUTHOR]

In order to solve the problem of environmental pollution control in the energy ecological economic zone, this paper proposes a technology to realize environmental pollution control by using big data. The main content of this technology is based on the characteristics and application of big data technology; through the collection of online monitoring data of ecological environment pollution, the construction of the online monitoring data quality model of ecological environment pollution, and finally through the experiments in the simulation environment, the feasibility of big data technology is obtained. The experimental results show that the average quality factor data of the quality control model in the environmental scientific data supervision is 2.16, the average quality factor data of the Internet of things in the marine pollution monitoring is 5.88, and the average quality factor data of the model in the ecological environment pollution online monitoring based on the big data technology is 8.64. Big data technology has good applicability. It is proven that the research of big data technology can meet the needs of environmental pollution control in the energy ecological economic zone. [ABSTRACT FROM AUTHOR]

In this contribution, the design and analysis of an active multifunction biquad filter that provides five voltage-mode filtering configurations in the same core filtering circuit are presented. The design emphasizes using the commercially available ICs, LT1228, which are easy for off-the-shelf implementation and cheaper compared with the chip implementation. The proposed multifunction filter is realized from two commercial LT1228 ICs as the active function block, combined with five passive elements (three resistors and two capacitors) with three input voltage nodes and a single output voltage node. The following advantages are given for this design: (i) it provides high-pass (HP), low-pass (LP), band-stop (BS), band-pass (BP), and all-pass (AP) filtering functions; (ii) orthogonal and electronic tuning of the natural frequency ω 0 and bandwidth (the quality factor: Q); (iii) output voltage node of the proposed circuit is low impedance; (iv) passband voltage gain is controllable; and (v) matching condition and extra double gain voltage-mode amplifier are not required. The effect of the parasitic element in LT1228 on the filter performance is analyzed and included to strengthen the design idea. The PSpice simulation results using LT1228 with ±5 V and the experimental results tested from the hardware implementation are given to prove the validity of the designed multifunction filter. [ABSTRACT FROM AUTHOR]

Particle size removal efficiencies for 0.1–1.0 μm (PSE0.1−1.0$$ {PSE}_{0.1-1.0} $$) and 0.3–1.0 μm (PSE0.3−1.0$$ {PSE}_{0.3-1.0} $$) diameter of Minimum Efficiency Reporting Value (MERV) filters, an electrostatic enhanced air filter (EEAF), and their two‐stage filtration systems were evaluated. Considering the most penetrating particle size was 0.1–0.4 μm particulate matter (PM), the PSE0.1−1.0$$ {PSE}_{0.1-1.0} $$ as an evaluation parameter deserves more attention during the COVID‐19 pandemic, compared to the PSE0.3−1.0$$ {PSE}_{0.3-1.0} $$. The MERV 13 filters were recommended for a single‐stage filtration system because of their superior quality factor (QF) compared to MERV 6, MERV 8, MERV 11 filters, and the EEAF. Combined MERV 8 + MERV 11 filters have the highest QF compared to MERV 6 + MERV 11 filters and EEAF + MERV 11 filters; regarding 50% of PSE0.1−1.0$$ {PSE}_{0.1-1.0} $$ as the filtration requirements of two‐stage filtration systems, the MERV 8 + MERV 11 filtration system can achieve this value at 1.0 m/s air velocity, while PSE0.1−1.0$$ {PSE}_{0.1-1.0} $$ values were lower than 50% at 1.5 m/s and 2.0 m/s. EEAF obtained a better PSE0.3−1.0$$ {PSE}_{0.3-1.0} $$ in the full‐recirculated test rig than in the single‐pass mode owing to active ionization effects when EEAF was charged by alternating current. [ABSTRACT FROM AUTHOR]

Federated learning (FL) is gradually becoming a key learning paradigm in Privacy‐preserving Machine Learning (ML) systems. In FL, a large number of clients cooperate with a central server to learn a shared model without sharing their own data sets. However, since there is a great disparity between the client data sets, standard FL is often hard to tune and suffers from performance degradation due to the inharmony among local models. To this end, in this paper we propose a novel FL scheme, termed client reputation federated learning (CRFL), which dynamically assesses the reputation of the clients participating in FL. Our method leverages techniques from model explanation, and aims at precisely measure each client's impact to the global model. To be specific, we first calculate the saliency‐weighted variance on pixelwise relevance scores as the quality factor of a single sample. Then we extract activation function values at the last hidden layer to compute the divergence factor of individual data set. Finally, the server integrates these two factors as an assessment of the client reputation. By leveraging such assessment, CRFL can dynamically adjust the weights of the clients in each aggregation round, thus leading to a significant improvement over the baseline method in terms of model accuracy and convergence rate. Intensive experiments are conducted on the MNIST and CIFAR‐10 data sets, and experimental results demonstrate the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

The core objective of image steganalysis is to explore the presence of weak image steganographic signals. Extracting effective steganographic signal features will play an essential role in digital image steganalysis. However, existing networks rely more on spatial rich model kernels or random learnable kernels to obtain noise residuals during the stage of steganographic signal features extraction. In this paper, we proposed a JPEG steganalysis network which based on denoising network and attention module, mainly including a noise extract block, a noise analysis block, and a judgment block. Specifically, a professional denoising convolutional neural network is first introduced in noise extract block to obtain better steganalysis features. The noise analysis block is integrated with the attention module to finely extract the steganographic signals hidden in the complex texture regions, which is quite effective in improving the signal‐to‐noise ratio of the stego signal. The judgment block is primarily a classifier to distinguish between cover images and stego images. Comprehensive experiments show a significant improvement in performance over the state‐of‐the‐art steganalysis scheme. Moreover, the proposed network has better generalization capability than the compared steganalysis network for the case of cover‐source and quality factor mismatch, which is critical for future steganalysis systems. [ABSTRACT FROM AUTHOR]

Deep blind watermarking algorithms based on an end-to-end encoder-decoder architecture have recently been extensively studied as an important technology for protecting copyright. However, none of the existing algorithms can fully utilize the channel features of the image to improve the robustness against JPEG compression while obtaining high visual quality. Therefore, we propose firstly a mixed-frequency channel attention method in the encoder, which utilizes different frequency components of the 2D-DCT domain as weight coefficients during channel squeezing and excitation. Its essence is to suppress the useless feature maps and enhance the feature maps suitable for watermarking embedding by introducing frequency analysis in the channel dimension. The experimental results indicate that the PSNR of our method reaches over 38 and the BER is less than 0.01% under the JPEG compression with quality factor Q = 50. Besides, the proposed framework also obtains excellent robustness for a variety of common distortions, including Gaussian filter, crop, crop out, and drop out. [ABSTRACT FROM AUTHOR]

Financial institutions are confronting more complicated risks as a result of the current financial crisis. Financial auditing is an essential aspect of government auditing since it serves to protect the security and stability of the national financial system by evaluating financial systemic vulnerabilities. Therefore, this paper combines the grey relational analysis to carry out research work on the financial auditing effect and improvement evaluation. Firstly, we conducted a preliminary selection of relevant financial audit impact indicators and identified the design of the influencing factor system as well as appropriate data for the influencing factors, resulting in the first evaluation system of the evaluation indicators. Secondly, we created a factor set for evaluating the financial audit improvement effect. The completed task proportion component and the task completion quality factor are the two kinds of improvement impact evaluation factors. On this foundation, this research develops a grey correlation-based assessment model for audit effect enhancement. The residual graph fitting findings indicate that the scheme has a good implementation impact and may be utilised to assess the financial auditing improvement effect. [ABSTRACT FROM AUTHOR]

Image steganalysis has been widely studied, most of which can only complete the binary task of identifying the existence of hidden bits in an inquiry image. Currently, although some algorithms have been proposed to locate hidden bits, most of them mainly focus on the spatial domain, while usually ignoring the study of locating secret bits hidden in DCT domain for JPEG image. To address that challengeable problem, in this paper, towards two classical steganographic algorithms JSteg and F5, hiding bits in DCT domain, we propose a novel payload location method. The principal step of payload location is to estimate the cover image. We novelly propose to assign the different weights to the DCT coefficient residual in virtue of the texture of regions measured by the local variance, leading to the remarkable improvement of location results. Compared with the state of the art, the numerical experiments empirically verify that our proposed location method achieves the superior performance. In particular, when locating hidden bits in JSteg steganographic images with quality factor of 95 at the payload 0.1, the accuracy of location is remarkably improved from 46.18% to 90.22%. [ABSTRACT FROM AUTHOR]

This paper mainly concentrates on finding maximum displacement and Eigen frequency for microelectromechanical system (MEMS) inertial sensors with various beam structures. In this work, six different shapes of beams are attached with one set of electrodes to find which structure exhibits the maximum displacement with less cross-axis displacement and to observe the operating frequency. The momentum of the beams is directly proportional to the thickness and length, which provides the maximum flexibility to produce momentum on proof mass. The beam thickness is 5 um for all proposed sensors and the momentum has been observed by changing different shapes of beam structures. The momentum occurred on proof mass due to applied physical energy. The same amount of physical energy is applied to all structure and the momentum, quality factor, and displacement are measured which had been compared and the table is given. [ABSTRACT FROM AUTHOR]

In this paper, velocity and attenuation of ultrasonic S-wave in a water-saturated rock are used for calculating shear modulus and matrix permeability of the rock, via a model improved from Biot theory. The model requires two inputs, i.e., the dry velocity of S-wave and the average distance of aperture representing pores, to yield phase velocity and the quality factor as functions of frequency. By fitting the predicted velocity and quality factor against the ultrasonically measured counterparts, the dry velocity of S-wave and the average distance of aperture are ascertained, which in turn yield shear modulus and matrix permeability, respectively. The modeling results on D'Euville limestone from France show that the specimen has shear modulus of 11.35 and 11.55 GPa (under differential pressures of 3 and 5 MPa, respectively) and matrix permeability of 0.0486 Darcy (under both differential pressures). The matrix permeability appears to be approximately one half of Darcy permeability. [ABSTRACT FROM AUTHOR]

To give an insight into the path attenuation and source characteristics of the 2019 Sichuan Changning earthquake sequence, 99 strong-motion recordings at 33 stations were studied. The S-wave Fourier amplitude spectra were used to determine the path-attenuation function and key parameters of the seismic source characteristics of this sequence. The results show the following: (1) The geometric spreading effect presents hinged-trilinear characteristics, and the corresponding geometric spreading rates were −0.97, 0.29, and −0.73 with the crossover distances 90 km and 183 km. (2) The quality factor Q is correlated with frequency and expressed as 217 × f0.82 for the range from 0.1 to 10.0 Hz. (3) The seismic moment was inversely proportional to the cube of the corner frequency, and their product was 2.37 × 1016 N. m/s3. (4) The stress drop varied from 1.18 to 12.44 MPa. Both the attenuation effect and source parameters of this sequence are significantly different from those of the Lushan and the Wenchuan aftershock sequences in the Sichuan region of China. [ABSTRACT FROM AUTHOR]

Among the different energy dissipation mechanisms, thermoelastic damping plays a vital role and needs to be alleviated in vibrating resonators to mitigate parameters by improving the thermoelastic damping limited quality factor, QTED. The maximum energy dissipation is also interrelated with the critical dimension h c of the plates, and by optimizing the dimensions, the peaking of energy dissipation can be diminished. As the size of the devices is scaled down, classical continuum theories become incompetent to explain the size-effect related mechanical nature at the micron and submicron levels, and, as a result, nonclassical continuum theories have been pioneered with the inception of internal length scale parameters. In this work, an analysis of isotropic rectangular microplates based on the Kirchhoff model and a higher order theory like Modified Couple Stress Theory is utilized to study size-dependent thermoelastic damping and its impact on the quality factor and critical dimensions. The Hamilton principle is adapted to derive the governing equations of motion, and the coupled heat conduction equation is employed to formulate the thermoelastic damping limited quality factor of the plates. Five different structural materials (PolySi, diamond, Si, GaAs, and SiC) are used for optimizing QTED and hc, which depends on two material performance index parameters: the thermoelastic damping index (TDI) and the material thermal diffusion length, l T . According to this work, the maximum QTED is attained for PolySi with the lowest TDI, and hcmax is obtained for Si with the maximum l T . The impacts of the dimensionless length-scale parameters (l/h), vibration modes, and boundary conditions (clamped-clamped and simply supported) on QTED and hc are also investigated. From the current analysis, QTED can be further enhanced by selecting higher vibration modes and clamped-clamped boundary conditions. QTED can be maximized by fixing the internal length scale parameter (l) and making the thickness of the beam equal to l. The analytical study is numerically simulated by using MATLAB 2015 software. Prior knowledge of QTED and hc will help designers to produce high-performance and low-loss resonators for the futuristic technological applications. [ABSTRACT FROM AUTHOR]

A novel resonator to improve the phase noise of a Voltage‐Controlled Oscillator (VCO) utilizing double series resonances or two attenuation zeros to improve the susceptance slope parameter of the resonator circuit is proposed, and its effectiveness is demonstrated by designing a low phase noise K‐band VCO. The first series resonance is created by an additional inductor (L) in series to the capacitor (C) in the parallel branch of a conventional LC‐tank circuit, and the second one is realized by an additional capacitor in series to the whole resonator circuit. The additional L is realized by defected ground structures (DGS) so that there is no additional burden in the chip size. The proposed resonator is fabricated in 0.18 μm CMOS technology and has active quality factor of 101 and a compact size of 0.009 mm2 (0.00046 λ2). The measured return loss |S11| and insertion loss |S21| of the fabricated prototype resonator are 2.8 and 11 dB, respectively, at a center frequency of 37 GHz with 8 GHz of bandwidth. The resulting active quality (QK‐) factor of the proposed resonator is enhanced significantly that, in returns, improves the phase noise. The design is implemented in 0.18 μm CMOS technology, and the post‐layout simulation shows that VCO has a tuning range of 3.8% and phase noise of −114.4 dBc/Hz @1 MHz offset at 19.5 GHz oscillation. The VCO consumes 2.96 mW power resulting in a Figure of Merit (FoM) of −195.5 dB. The proposed resonators improve the VCO FoM by more than 5.5 dB compared to conventional LC resonator. [ABSTRACT FROM AUTHOR]

A millimeter‐wave (mm‐wave) dual‐polarized antenna achieved by stacking single patch and 2 × 2 patches with square holes is proposed to achieve low profile and wide bandwidth. The single patch and the 2 × 2 patches operate at two pairs of orthogonal modes, TM10/TM01 modes and antiphase TM20/TM02 modes, respectively. The square holes are introduced to adjust the coupling between the two layers of patches with small spacing. The appropriate coupling between two layers of patches and the low quality factor of the upper 2 × 2 patches make the proposed antenna achieve wide bandwidth with relatively low profile. A pair of perturbation slots is introduced to adjust the port‐to‐port isolation. The characteristic mode analysis (CMA) method is utilized to analyze the antenna element to reveal the modal behavior of the proposed antenna. For demonstration, a prototype of 2 × 2 array with a profile of 0.05λ0 (λ0 is the wavelength in free space at the center frequency) is designed and fabricated, which achieves the measured 10‐dB bandwidth of 24.5%, the maximum gain of 11.6 dBi, and the port‐to‐port isolation of 23.5 dB. [ABSTRACT FROM AUTHOR]

This article presents a low‐profile disk‐loaded monopole antenna specifically designed to be embedded into a manhole cover and a method to improve the bandwidth of the antenna. The antenna is placed deep inside a circular cavity formed on a manhole cover and is covered with a thick radome to protect the antenna from strong external impacts. The effect of the cavity size on the bandwidth of the antenna was studied, and as a result, it was found that the bandwidth of a low‐profile monopole antenna is greatly enhanced when the cavity diameter is about one wavelength. The bandwidth enhancement mechanism due to the cavity size is analyzed in terms of the quality factor (Q) of the antenna. A prototype was fabricated and measured; the disk‐loaded monopole antenna with a diameter of 0.2λ0 and a height of 0.04λ0 (λ0 is the free‐space wavelength at the center frequency) provides a wide impedance bandwidth of 14.3% (10‐dB return loss) when placed inside a cavity with a diameter of 0.82λ0 and a depth of 0.1λ0. The antenna radiates vertically polarized omnidirectional fields in the horizontal direction and has a stable measured peak gain that varies from 4.5 to 5.5 dBi across the measured impedance bandwidth. [ABSTRACT FROM AUTHOR]

In the aspect of gearbox fault diagnosis, the periodic pulse signal containing fault characteristics is often overwhelmed with other strong interference components, which brings a great challenge for gearbox fault detection and status identification. To address these issues, this paper develops a novel resonance-based sparse signal decomposition (RSSD) fault diagnosis method combined with support vector machine (SVM). Based on the key of the decomposition parameters in the resonant sparse decomposition method, the influence of atom search optimization (ASO) on the quality factor in the resonance-based sparse signal decomposition method is primarily studied. The vibration signal of the gearbox was decomposed by resonance sparse decomposition with the optimal quality factor, from which the high and low-resonance components were obtained. Then, the power spectrum entropy, singular spectrum entropy, and time-domain energy entropy of the low-resonance signal were calculated. Finally, the pattern recognition of gearbox fault was completed with a designed cross-validation SVM pattern recognition model. The numerical simulation and gearbox fault experiments demonstrate that the presented method can achieve great recognition accuracies and effect capacities against interference components involved in the gearbox vibration signal. [ABSTRACT FROM AUTHOR]

Remote sensing, environmental monitoring, pattern recognition, and other fields all use this critical and indispensable basic technology. The article proposes an image contrast enhancement detection algorithm based on a linear model to address the problem that the current global contrast enhancement detection algorithm does not have high classification accuracy under the low-intensity JPEG compression quality factor. To decompose the original image, use the biorthogonal wavelet transform. The improved fuzzy set enhancement algorithm is used for the low-frequency subband coefficient. The results obtained after simulating this algorithm show that it is very effective in improving contrast, enhancing image details, and suppressing noise. It has the ability to greatly improve the image's visual effect, as well as the advantages of parameter adaptation and high algorithm efficiency. [ABSTRACT FROM AUTHOR]

While considering the competition effect and market share, this study discusses how the cash flow bullwhip effect (CFBE) is impacted in two-product and two-parallel supply chain systems by comparing the situation that it has one kind of product in two-level supply chain (SC). Specifically, the study aimed to examine two-product and two-parallel SC systems that include two suppliers and two retailers. Assuming that the demand function is a linear relationship of price self-sensitivity coefficient and price cross-sensitivity coefficient, which is an AR(1) process, two retailers share the demand. After that, the quantitative equation of the CFBE was deduced from two-product and two-parallel SC systems. Finally, we get the condition that the competition effect and the market share increase or decrease the CFBE, which was in contrast to the situation without the competition effect and the market share. The paper suggested that the manager can cooperate with their partner if two products are substitutable. On the other hand, the firm should improve the forecasting accuracy of the customer's demand and improve the service quality so that it can increase the market share and reduce the CFBE in two-parallel SC systems. [ABSTRACT FROM AUTHOR]

Tensile strength, warping degree, and surface roughness are important indicators to evaluate the quality of fused deposition modeling (FDM) parts, and their accurate and stable prediction is helpful to the development of FDM technology. Thus, a quality prediction method of FDM parts based on an optimized deep belief network was proposed. To determine the combination of process parameters that have the greatest influence on the quality of FDM parts, the correlation analysis method was used to screen the key quality factors that affect the quality of FDM parts. Then, we use 10-fold cross-validation and grid search (GS) to determine the optimal hyperparameter combination of the sparse constrained deep belief network (SDBN), propose an adaptive cuckoo search (ACS) algorithm to optimize the weights and biases of the SDBN, and complete the construction of prediction model based on the above work. The results show that compared with DBN, LSTM, RBFNN, and BPNN, the ACS-SDBN model designed in this article can map the complex nonlinear relationship between FDM part quality characteristics and process parameters more effectively, and the CV verification accuracy of the model can reach more than 95.92%. The prediction accuracy can reach more than 96.67%, and the model has higher accuracy and stability. [ABSTRACT FROM AUTHOR]

Multi‐fin devices are the most reliable option for terahertz (THz) frequency applications at nano‐regime. In this work impact of spacer engineering on multi‐fin SOI FET performance is evaluated by invoking single low‐k (Air), high‐k (Si3N4, HfO2), and hybrid dual‐k (Air + Si3N4) spacer in the underlap section at nano‐regime. The simulation study reveals that the high‐k (HfO2) spacer gives a higher switching ratio (ION/IOFF) in the order of ~107, subthreshold swing (SS) = 72 mV/dec, drain induced barrier lowering (DIBL) = 22.14 mV/V and quality factor (Q) = gm/SS = 0.16 μS‐dec/mV. Furthermore, to measure the suitability of the device for high frequency applications various analog/RF parameters are studied. The high‐k (HfO2) spacer dominates DC and analog performance, whereas the low‐k (Air) spacer dominates the RF domain with fT = 1.26 THz, GBW = 0.251 THz, TFP = 29 THz range, and with smaller intrinsic delays. Hybrid dual‐k spacer (Air + Si3N4) outperforms in terms of gain (AV) and output resistance (Ro). The Air spacer exhibits lower dynamic power of 2.09 aJ/μm and power consumption of 1.04 aJ/μm. The linearity metrics for multi‐fin SOI FET parameters like gm2, gm3, HD1, HD2, THD, and VIP2 are also studied. The Air spacer followed by hybrid spacer outperforms in linearity, and harmonic distortion components and ensures its potential for RF applications at nano‐regime. [ABSTRACT FROM AUTHOR]

Consumer acceptability of vacuum dried (60 ± 2°C temperature and 6.66 kPa pressure) onion samples was tested applying the Fuzzy Reasoning approach on the sensory data. Culinary preparation using vacuum dried onion treated with 5% sodium chloride (NaCl) and 0.2% potassium metabisulfite (K2S2O5) for 15 min and untreated onion was compared using fresh onion preparation based on sensory attributes viz., Color, flavor, taste, and mouthfeel. Panelists were asked to rate the samples in terms of each sensory attribute and the relative importance of each sensory attribute in the overall acceptability of the samples. The preference levels of individual attributes for a particular sample were assessed using "Not Satisfactory," "Fair," "Medium," "Good," and "Excellent." While the contribution of a single quality factor in the overall selection process was categorized by "Not at all Important," "Somewhat Important," "Important," "Highly Important," and "Extremely Important" for the onion in general. Responses from the individuals were converted to fuzzy sets and relative weight was computed along with the importance of the quality aspects. All three samples were quite comparable; however, treated vacuum dried samples received the best response. Practical applications: The application of Fuzzy logic is an efficient way of handling linguistic data in an interpretable manner. Sensory analysis is highly relevant when any new product is being made and consumer perceptibility toward it needs to be judged. Fuzzy logic can be applied to analyze imprecise sensory data of the panellists to convert it into a measurable metric. Vacuum dried onion slices scored high in the test which supports its high consumer acceptance. [ABSTRACT FROM AUTHOR]

In recent years, the development of prefabricated building (PB) mode in China has gradually attracted the attention of stakeholders. It is of great significance to explore the adoption behavior of PB mode by Chinese construction enterprises. Using the method of combining evolutionary game theory with system dynamics and considering the multiagent interaction of the government, construction enterprises, and consumers, as well as the influence of multiple factors, this paper constructs a model of construction enterprises' adoption behavior of PB mode. The purpose is to clarify the mechanism of Chinese construction enterprises' adoption behavior of PB mode and the evolution law of market share. The research results show the following. Firstly, government subsidy plays an important role in promoting the maturity of PB market, but it plays a relatively small role in the more mature and stable market. Secondly, the higher the initial acceptance probability of the construction enterprise, the greater the peak of the PB market share and the greater the volatility, but it has no differential impact on the balance of the PB market in the later stage. Thirdly, price factors and quality factors, respectively, have an important impact on the increase of the PB market share in the early and late stages of the formation of the PB market, but the delivery waiting time factor has no significant impact on the PB market share. [ABSTRACT FROM AUTHOR]

5G technology strongly supports the development of various intelligent applications, such as intelligent video surveillance and autonomous driving. And the human detection technology in intelligent video surveillance has also ushered in new challenges. A number of video images will be compressed for efficient transmission; the resulting incomplete feature representation of images will drop the human detection performance. Therefore, in this work, we propose a new human detection method based on compressed denoising. We exploit the quality factor in the compressed image and incorporate the pixel_shuffle inverse transform based on FFDNet to effectively improve the performance of image compression denoising, then HRNet and HRFPN are used to extract and fuse high-resolution features of denoised images, respectively, to obtain high-quality feature representation, and finally, a cascaded object detector is used for classification and bounding box regression to further improve object detection performance. At last, the experimental results on PASCAL VOC show that the proposed method effectively removes the compression noise and further detects human objects with multiple scales and different postures. Compared with the state-of-the-art methods, our method achieved better detection performance and is, therefore, more suited for human detection tasks. [ABSTRACT FROM AUTHOR]

Summary: To carry out the study and simulations of anti‐islanding systems, it is necessary to take into account the generic system proposed by the IEEE 929‐2000 and IEEE 1547 standards, where the network, the RLC load, and PV inverter are connected in parallel to the PCC. The IEEE 929‐2000 standard defines the quality factor to have a standard test condition. The paper presents a modified Active Frequency Drift (AFD) algorithm to detect the islanding of grid‐connected photovoltaic (PV) systems with low harmonics levels without degrading their power factor. Severe issues such as deterioration in power quality and electric shock can occur when a PV inverter operates in islanding mode. Various islanding detection techniques have been investigated in the literature in the last two decades among which, AFD is a typical method. However, a prominent drawback of AFD is its relatively large Non‐Detection Zone (NDZ). The improved AFD method that this paper suggests allows the frequency of the inverter current to be controlled slightly lower (or higher) than the frequency of the terminal voltage. The islanding condition is detected by calculating the changing parameter that relates to the change of the chopping fraction and the line frequency periodically. The frequency deviation is then detected to determine the chopping and a changing parameter, which accumulates to the threshold value when the inverter is shut down. The proposed algorithm overcomes the conventional AFD issues by improving the accuracy of detection, eliminating the NDZ, and reducing the current harmonic distortion. The proposed method is validated with the help of simulated and experimental results of a 350 W PV inverter using IEEE Standards. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to design multiband bandpass filters (BPF) using multimode resonator topology inspired from Bamileke fractal architecture in the form of fractal shaped resonator. The proposed resonator architecture exhibits quint mode resonance behavior where resonance frequencies are determined using ABCD matrix. It offers flexibility in terms of choosing passband center frequencies precisely. Initially a second order dual band BPF is presented by suppressing higher order modes using asymmetric feed line. The same structure is used further to implement a triband and a quad band BPF where the input/output coupling circuit is modified to extract the higher order modes. Two stub loaded resonators are also embedded to improve the passband selectivity and to improve upper stopband characteristics. The design guidelines are demonstrated through the external quality factor (Qe) and coupling coefficient (k) synthesis approach. The developed filters are fabricated and measured to verify the predicted and simulated results. A close agreement is observed between them. The fabricated multiband BPFs has a very compact size, less insertion loss and good return loss profile. [ABSTRACT FROM AUTHOR]

A novel and simple design approach of compact four‐way filtering power divider (FPD) using half‐mode substrate integrated waveguide (HMSIW) cavity is investigated in this letter. The pre‐defined power division ratio of the four outputs is obtained by adjusting the external quality factor (Qe) of each output port, while the total output Qe is equal to the input Qe. The four outputs are loaded to a single HMSIW resonator, achieving a compact size. Meanwhile, both bandpass response and power division can be designed independently. For demonstration, a prototype with pre‐defined power division ratio of 1:3:3:1 is designed, fabricated, and measured. The measured results show that the FPD centered at 4.88 GHz owns a 3‐dB fractional bandwidth (FBW) of 11.3%. The insertion loss of the passband is about 1.4 dB and the return loss is better than 17 dB, meanwhile the phase differences of in‐phase four outputs are all within 5° from 4.61 to 5.16 GHz. Good agreement is observed between the simulated and measured results. [ABSTRACT FROM AUTHOR]

As electric and magnetic dipoles with inherent 90° phase difference (PD) can be easily realized by forming a circular array of the epsilon‐zero resonance and mu‐zero resonance (EZR‐MZR) resonators, high design efficiency can be expected for low‐profile, omni‐directional and circularly polarized (CP) antenna designing. However, high Q factor of the EZR‐MZR resonator makes narrow bandwidth. This research is dedicated to enhance the bandwidth. Low Q factor and multi‐resonances techniques are utilized to enhance the impedance bandwidth. While polarization compensation technique is applied to improve the axial ratio (AR) bandwidth by tuning the amplitudes and PD of the orthogonal vectors. The proposed antenna obtains a − 10 dB impedance band of 1.370 to 1.690 GHz (20.91% at 1.530 GHz) and a 3 dB axial ratio (AR) band of 1.260 to 1.580 GHz (22.53% at 1.42 GHz). The diameter and profile of the proposed antenna are 0.402 λ and 0.082 λ, respectively. [ABSTRACT FROM AUTHOR]

Summary: Renewable sources of energy are used extensively in the distribution grid to meet the need for growing electricity demand and to resolve the global heating crisis caused by traditional energy sources. They offer many advantages like better efficiency, power quality, and lower air pollution. One of the vital issues with these integrations is islanding condition arising due to the sudden disconnection of grid because of some abnormal situations; however, the distributed generation (DG) retains the power supply to the local loads. Thus, efficient detection of islanding and quick detachment of DG are vital to prevent failure of equipments, grid safety disruption, and risks to personnel safety. In this context, this article represents a comprehensive review of islanding issues and different islanding detection methods (IDMs) that provide a detailed assessment for filling the research gap and thereby highlights the various issues related to island detection. A broad classification of IDMs is established based on the conventional and modern techniques such as local (Active, Passive & Hybrid) and remote IDMs with their detailed illustrations including both intelligent and signal processing‐based IDMs. Comparison of various IDMs based on their merits, demerits, and various performance analysis including the non‐detection zone, detection time, quality factor, power quality, effect on a microgrid, implementation cost, and applicability in multi‐DG system is provided. Hence, this review will provide an insight for the new researchers interested in the area highlighting the different islanding detection techniques with their relative merits and demerits. [ABSTRACT FROM AUTHOR]

In this article, a circularly polarized (CP) microstrip patch antenna (MPA) is proposed. The antenna adopts a substrate integrated waveguide (SIW) cavity and a microstrip patch as the feed structure and the radiator, respectively. In consequence, the patch dominates the radiation and improves the radiation efficiency, while the asymmetric SIW cavity enhances the bandwidth and generates a pair of degenerate modes, which provide the quadrature phase shift that the CP radiation requires. By this mean, the proposed antenna not only brings up a novel feed structure for CP MPA and improves its effective bandwidth, but also circumvent the limitation of the SIW cavity slot antenna, which is low radiation efficiency. Plus, the presented antenna remains the advantages of SIW structure, including high Q factor, high integrate compatibility, and so forth. The antenna was fabricated and measured, and the presented antenna exhibits an impedance bandwidth of 12% (from 2.09 to 2.36 GHz), an axial ratio bandwidth of 7.73% (from 2.15 to 2.32 GHz) with a minimum gain of 7.89 dB. The experiment results indicate a good agreement with the simulation. [ABSTRACT FROM AUTHOR]

A high selectivity dual‐band filter is proposed based on the quadruple‐mode multi‐stub loaded ring resonator. The ring resonator can utmostly avoid bending the electromagnetic wave. Two external open stubs are employed to generate four transmission poles where the odd‐ and even‐mode is utilized to analyze the resonant frequencies of the BPF. The internal stub effectively reduces the insert loss (IL) by improving the external quality factor Qe of the second passband. In addition, five transmission zeros are generated due to the multipath and self‐resonance modes to improve the out‐of‐band selectivity of the proposed filter. The proposed filter centered at 2.65 and 4.84 GHz is designed, fabricated and measured. The simulated results agree well with the measured results. [ABSTRACT FROM AUTHOR]

Summary: Chemical looping hydrogen generation (CLHG) is a hydrogen production process with broad prospects for its advantages of not requiring H2 purification process and direct CO2 capture. Presently, the research on the integrated system of CLHG focuses on the impact of integrated processes and operating variables on the overall energy efficiency and exergy efficiency of the system. However, the research on the matching relationship between quantity and quality in the process of energy conversion is insufficient, and the flow direction of exergy and the specific exergy destruction process for equipment are not clear. The integrated system of coal gasification (CG) and three reactors CLHG was established in this paper with a hydrogen production efficiency of 42.55% and system exergy efficiency of 52.98%. This paper studied the exergy flow direction and efficiency of the equipment in the system, providing the improved direction for the amelioration of the system; a detailed description was present on the change process of energy quality in each equipment with energy quality factor, and the concept of energy quality factor ratio was proposed as an evaluation tool for matching the quantity and quality of energy in the system. It is calculated that the ratio of energy quality factor of the integrated system of CG and CLHG is 0.944. By comparing with the energy quality ratio of the traditional CG hydrogen production system (0.896), it can be concluded that the integrated system of CG and CLHG has a better energy matching relationship. [ABSTRACT FROM AUTHOR]

Quarter‐mode cavity resonators in substrate integrated waveguide (SIW) technology represent a good solution for the design of compact filters. However, their advantage in terms of reduced footprint is counterbalanced by possible radiation leakage, which may jeopardize the overall performance. This article presents a systematic investigation of the different contributions of losses in quarter‐mode SIW (QMSIW) cavities, considering both the standard topology and modified configurations. General guidelines for the choice of the optimal dielectric permittivity and substrate thickness are derived. Experimental results of individual cavity resonators are presented to validate the simulations. Moreover, the design and the experimental verification of a four‐pole filter based on classical and modified QMSIW cavities are reported, to illustrate a possible strategy for performance improvement. [ABSTRACT FROM AUTHOR]

Software metrics which are language-dependent are proposed as quantitative measures to assess internal quality factors for both method and class levels like cohesion and complexity. The external quality factors like reliability and maintainability are in general predicted using different metrics of internal attributes. Literature review shows a lack of software metrics which are proposed for reliability measurement and prediction. In this context, a suite of four semantic language-independent metrics was proposed by Mili et al. (2014) to assess program redundancy using Shannon entropy measure. The main objective of these metrics is to monitor program reliability. Despite their important purpose, they are manually computed and only theoretically validated. Therefore, this paper aims to assess the redundancy metrics and empirically validate them as significant reliability indicators. As software reliability is an external attribute that cannot be directly evaluated, we employ other measurable quality factors that represent direct reflections of this attribute. Among these factors, defect density is widely used to measure and predict software reliability based on software metrics. Therefore, a linear regression technique is used to show the usefulness of these metrics as significant indicators of software defect density. A quantitative model is then proposed to predict software defect density based on redundancy metrics in order to monitor software reliability. [ABSTRACT FROM AUTHOR]