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Methyl iodide (CH3I) gas as a toxic gas causes great harm to organisms due to its high volatility and high reactivity with biological nucleophiles. Unfortunately, the sensing and detection of CH3I gas are challenging because of the diffusive nature of the gases and its low concentrations in the environment. Herein, we have developed a fast, green, and sensitive CH3I gas visual sensing method based on the capture technology of toxic gases by natural deep eutectic solvents (NADESs) coupled to the halide rapid exchange capability of perovskite nanocrystals (PNCs). In this strategy, NADESs are used as an absorption solution to adsorb gaseous CH3I, while simultaneously exposing I–through the action of the nucleophilic reagent; then, CsPbBr3PNCs were synthesized in NADESs and used as sensing material to achieve I–exchange. Benefiting from the capture and enrichment of CH3I gas, the sensitivity of the gas sensor was highly improved. The sensor exhibited the lowest detection limit (limits of detection) of 164.15 μmol/m3, below the minimum safe level for human inhalation, which is 200 μmol/m3. This breakthrough offers greater possibilities for the quantitative detection of CH3I gas.

This paper presents a discussion on the method, mechanism, and application of adhesive hydrogel in enhancing epidermal signal, focusing on the interface between hydrogel and skin. Due to its excellent conductivity and high adaptability to the skin, the hydrogel is exceptionally suitable for detecting human-machine interfaces, particularly epidermal electromyographic signals. However, the detection of the high epidermal signal is hindered by the gap and low adhesion between hydrogel and skin. This paper addresses these challenges by introducing approaches to reduce the interface gap and increase interface adhesion, thereby enabling the development of hydrogel-based epidermal signal detection arrays with enhanced resolution and detection performance.

In this article, a method to realize the guidance stability of a high-speed electrodynamic suspension (EDS) and electromagnetic propulsion combined system is proposed. This method uses the normal force of the stator windings, which are placed on both sides of the mover, to control the guidance motion of the train. The null-flux coil is considered to be an EDS structure with a high floating/resistance ratio, and has been successfully used in Japanese commercial maglev trains. However, the null-flux coil structure has the disadvantage of insufficient damping coefficient for guidance at high speed, so how to achieve guidance stability of the EDS system is a very important issue. In this article, the electromagnetic force calculation models of the air-core linear synchronous motor and the null-flux coils are established; and an experimental platform is built and experiments are carried out to verify the accuracy of the models. Based on the model, the guiding characteristics of the null-flux coils are analyzed by dynamic co-simulation, and it is found that at low speeds, its guiding stiffness is small and its guiding damping coefficient is positive. At high speeds, there is sufficient guidance stiffness, but the guidance damping coefficient is negative. Thus, an active guidance control method with independent control mode of the two motors is proposed to realize the stable guidance control of the high-speed EDS and electromagnetic propulsion combined system, and the effectiveness of the active guidance control method is verified through the dynamic co-simulation and experiments.

With the aggravation of electromagnetic pollution, electromagnetic interference (EMI) shielding materials have received enormous attention. However, most of the current EMI shielding materials only focus on the shielding effectiveness (SE), neglecting the electromagnetic pollution brought by secondary reflection. In this work, a method of preparing absorption-dominated EMI shielding materials, which are also called green EMI materials, using thermally expandable microspheres (TEMs) and expanded graphite (EG), is proposed. The expansion of TEMs in the EG/waterborne polyurethane mixture can improve the impedance matching between the composite and air. When the content of TEMs is 5 wt % and the content of EG is 15 wt %, the EMI SE of the sample reaches 38.4 dB, and the average reflection power coefficient of this composite is 0.27, indicating that the material mainly shields electromagnetic waves through absorption. Meanwhile, the prepared material also exhibits good stability, maintaining outstanding EMI SE and low value of reflection power coefficient even after the compression–recovery test.

In this letter, a coplanar waveguide-fed wideband polarization-reconfigurable monopole antenna utilizing chalcogenide germanium telluride (GeTe) is proposed. The main radiation part is a rectangular loop, which is split into several symmetrical pieces. The adjacent pieces and ground plane are electrically connected by inverted GeTe chips. By electrical and thermal hybrid excitation, the states of all GeTe chips can be controlled to realize polarization reconfigurability. Additionally, two symmetrical parasitic elements are adopted to improve the impedance bandwidth and axial-ratio bandwidth. Finally, a simple, compact, and low-profile antenna prototype with zero static power is fabricated and tested. The measured results show that the proposed polarization-reconfigurable monopole antenna obtains a wide overlapped bandwidth of 35.7% from 2.62 GHz to 3.76 GHz for linear polarization, left-hand circular polarization, and right-hand circular polarization, which covers sub-6G and WiMAX frequency bands.

A novel method for estimation and optimizing structural parameters of coupled-line bandpass filters (BPFs) using transformer-based estimator (TBE) and multilayer perceptron (MLP) is proposed. Once trained, the TBE can quickly obtain the predicted values of the BPF structural parameters from desired S-parameters, while the trained MLP can replace the time-consuming electromagnetic (EM) simulation process, and establish the mapping from structural parameters to S-parameters. In order to obtain the optimal structural parameters, the trained MLP is combined with genetic algorithm (GA) for fast optimization. To demonstrate the effectiveness of the proposed method, a BPF using three pairs of coupled-line microstrip structure is designed and fabricated. The experimental results demonstrate that the proposed method can quickly and accurately obtain the optimal structural parameters from the desired frequency response of the coupled-line BPF.

• An unreported nanoribbon reinforced carbon/carbon composite is produced. • Comparison of enhancing efficiency of nanoribbons and nanowires is conducted. • Nanoribbons can simultaneously enhance strength and toughness of carbon/carbon composites. • Nanoribbons show significant advantageous in deflecting cracks compared to nanowires. Incorporating one-dimensional (1D) nanofillers into carbon/carbon composites (C/Cs) can increase their mechanical strength. However, this method is ineffective in improving the fracture toughness of C/Cs because cracks can easily pass over the 1D nanofillers, resulting in a flat fracture surface. Herein, we propose a new technique to significantly improve both the strength and toughness of C/Cs by incorporating 2D ribbon-shaped nanofillers. Silicon nitride nanoribbons (SiNNRs) are assembled into a film-like structure and inserted into each layer of a carbon fiber laminate, which is then densified with a pyrocarbon matrix. Due to the large interfacial contact area between the nanoribbon and matrix, ribbon-shaped SiNNRs can efficiently arrest and deflect cracks in both two and three dimensions, exhibiting a higher reinforcement efficiency than that of slender silicon nitride nanowires (SiNNWs). Mechanical tests show that the percentage increases in fracture toughness, flexural strength, and compressive strength of C/Cs produced by SiNNRs are approximately 9.8, 1.8, and 1.25 times higher than those produced by SiNNWs at the same volume fraction of nanofillers, respectively. This study suggests that 2D ribbon-shaped nanofillers are more effective than 1D fibrous nanofillers in enhancing the strength and toughness of C/Cs. : [Display omitted] [ABSTRACT FROM AUTHOR]

This article proposes a prescribed-time robust repetitive learning control scheme for uncertain permanent magnet synchronous motor (PMSM) servo systems. An error-tracking approach is developed through constructing a desired error trajectory, such that the exact settling time of the error convergence can be achieved without using any switching mechanism in controller design. In order to achieve high-precision steady-state tracking accuracy, a fully saturated repetitive learning law is developed to reduce the residual periodic steady-state error and drive the tracking error to converge into a sufficiently small region around the origin, such that the rapid transient response and high-precision steady-state tracking accuracy of the PMSM servo system can be both guaranteed simultaneously. Comparative experiments are provided to verify the effectiveness of the proposed method.

The advanced development of soft yet tough hydrogels with high crack resistance significantly extends their application scope from biomedical applications for tissue engineering to emerging electronics applications for soft flexible devices. We investigated the fracture toughness of agar/PAAm hybrid double-network (DN) hydrogels at various strain rates. In large deformations without precut, the loading–unloading curves of agar/PAAm hybrid DN hydrogels exhibit rate-independent hysteresis. However, the fracture toughness of the precut agar/PAAm hybrid DN hydrogel exhibits a transition region around strain rate (ε̇) as 0.12 s–1, and rate-independent toughness is observed at ε̇ < 0.12 s–1, while the fracture toughness decreases significantly if ε̇ > 0.12 s–1. We also discover that the fracture toughness scales with strain rate as Γ ∼ (dλ/dt)−0.58at a high strain rate. A possible mechanism is proposed to interpret this phenomenon. It is believed this work provides new insight into the fracture behavior of hybrid DN gels.

Microstructure and room-temperature mechanical property of TC21 titanium alloy treated by continuous multistep hydrogenation at different temperatures were studied by OM, XRD, TEM and compressive test. Results showed that the size of αphase decreased obviously and βphase became the main phase when the hydrogenation temperature exceeded 1073 K. The content of δhydride increased first and then decreased gradually with the increase of hydrogenation temperature. The strain softening phenomenon appeared during the compression process of TC21 titanium alloy when the hydrogenation temperature exceeded 1073 K and became obvious with the increase of hydrogenation temperature. The ultimate compression of TC21 titanium alloy decreased first and then increased with the increase of hydrogenation temperature, and increased by 67.51% compared with that of the as-received TC21 titanium alloy when the hydrogenation temperature was 1123 K.

Aqueous ammonium ion hybrid supercapacitor (A-HSC) is an efficient energy storage device based on nonmetallic ion carriers (NH4+), which combines advantages such as low cost, safety, and sustainability. However, unstable electrode structures are prone to structural collapse in aqueous electrolytes, leading to fast capacitance decay, especially in host materials represented by vanadium-based oxidation. Here, the Co2+preintercalation strategy is used to stabilize the VO2tunnel structure and improve the electrochemical stability of the fast NH4+storage process. In addition, the understanding of the NH4+storage mechanism has been deepened through ex situ structural characterization and electrochemical analysis. The results indicate that Co2+preintercalation effectively enhances the conductivity and structural stability of VO2, and inhibits the dissolution of V in aqueous electrolytes. In addition, the charge storage mechanisms of NH4+intercalation/deintercalation and the reversible formation/fracture of hydrogen bonds were revealed.

Zeolite-encapsulated metal nanoparticle systems have exhibited interesting catalytic performances via the hydrogen spillover process, yet how to further utilize the function of zeolite supports to promote catalytic properties in such a process is still challenging and has rarely been investigated. Herein, to address this issue, the strategy to strengthen the adsorption energy of reactant onto the zeolite surface via a simple ion exchange method has been implemented. Ion-exchanged linde type A (LTA) zeolite-encapsulated platinum nanoclusters (Pt@NaA, Pt@HA, Pt@KA, and Pt@CaA) were prepared to study the influence of ion exchange on the catalytic performance in the model reaction of hydrogenation of acetophenone to 1-phenylethanol. The reaction results showed that the Pt@CaA catalyst exhibited the best catalytic activity in the series of encapsulated catalysts, and the selectivity of 1-phenylethanol approached 100%. As revealed by density functional theory (DFT) calculations and acetophenone temperature-programmed desorption (acetophenone-TPD) experiments, in comparison with introduced cations of Na+, H+, and K+, ion-exchanged Ca2+on the zeolite maximumly enhanced the adsorption of carbonyl groups in acetophenone, playing a critical role in achieving the highest activity and excellent catalytic selectivity among the Pt@A catalysts.

Escherichia coliSeptu system, an anti-phage defense system, comprises two components: PtuA and PtuB. PtuA contains an ATPase domain, while PtuB is predicted to function as a nuclease. Here we show that PtuA and PtuB form a stable complex with a 6:2 stoichiometry. Cryo-electron microscopy structure of PtuAB reveals a distinctive horseshoe-like configuration. PtuA adopts a hexameric arrangement, organized as an asymmetric trimer of dimers, contrasting the ring-like structure by other ATPases. Notably, the three pairs of PtuA dimers assume distinct conformations and fulfill unique roles in recruiting PtuB. Our functional assays have further illuminated the importance of the oligomeric assembly of PtuAB in anti-phage defense. Moreover, we have uncovered that ATP molecules can directly bind to PtuA and inhibit the activities of PtuAB. Together, the assembly and function of the Septu system shed light on understanding other ATPase-containing systems in bacterial immunity.

In this paper, the microstructure and tensile mechanical properties of Mg-8.5Gd-4.5Y-0.8Zn-0.4Zr rare-earth (RE) magnesium alloy in the as-cast state and its solid solution state were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and the first-principles simulation. The results show that the mechanical properties were improved after solution treatment. The CS520-12 alloy, treated at 520 °C for 12 h, exhibited excellent mechanical properties, possessing an ultimate tensile strength (UTS) of 343 ± 5 MPa and an elongation of 18.9 ± 0.8 %. These main reasons for the improving of mechanical properties was attributed the formation of I1 stacking faults (SFs) and accumulated-dislocations. The Y element, originating from the melt of the eutectic phase during solution treatment, resulted in a reduction in stacking faults energy (SFE) and facilitated the formation of I1 faults. The presence of numerous SFs hindered dislocation slip. The other key factors for elongation improving were that the weaken of texture, and geometrically necessary dislocation (GND) density decreased from 1.52 × 1013m−2to 1.22 × 1013m−2. 14H-LPSO phase played an important role in the improving mechanical properties for CS480-12, CS480-24 and CS520-24 alloys. The higher elastic modulus of LPSO compared to Mg matrix, according to the first-principles calculated results, enabled its function as a short-fiber, thus strengthened the mechanical properties. Block-shaped 14H-LPSO in CS480-12 alloys, distributed at the grain boundaries (GBs), suppressed the grow of cracks. The lamellar 14H-LPSO within the grains of CS480-24 and CS520-24 alloys were parallel to the dislocations, which compared with SFs of CS520-12 alloy, can't effectively inhibit the movement of dislocations.

Understanding the vertical settlement is crucial when designing the pile and foundation type used in real estate, specifically regarding the pile settlement (Sp). This issue is of utmost importance due to the numerous variables involved in designing piles that penetrate rock. Despite multiple efforts, clear and precise theoretical explanations regarding the interactions between soil and piles are currently unclear. As a result, many studies have opted to employ artificial intelligence techniques for determining the subsidence rate of piles over time under different loading conditions. This study presents a machine learning (ML) that effectively predicts the values of Sp, namely Least Square Support Vector Regression (LSSVR). In addition, the proposed model coupled with three meta-heuristic algorithms, including the Flow Direction Algorithm (FDA), Chimp Optimization Algorithm (ChOA), and Rider Optimization Algorithm (ROA), to improve the performance and obtain the optimal results as a framework of hybrid. As a result, LSFD determined the most suitable effects with R2and RMSE values equal to 0.2503 and 0.9952, respectively. Overall, using LSSVR with FDA, ChOA, and ROA can improve the accuracy and robustness of the model in predicting pile settlement, making it a valuable tool for geotechnical engineers designing foundation systems.

A compact planar printed wideband filtering quasi-Yagi antenna without any extra external filtering circuit for vehicular communication is proposed in this article. It consists of a microstrip-to-slotline transition (MST), a coplanar stripline (CPS), driven elements and parasitic elements which act as directors and filtering elements simultaneously. The MST can inherently introduce four radiation nulls on the lower and upper stopband, and by adding a pair of exponential curved branch elements symmetrically, two radiation nulls are generated on the upper stopband. Moreover, four parasitic elements are placed around the director to enhance the end-fire radiation and the rejection levels of three radiation nulls on the upper stopband. Therefore, a wideband filtering quasi-Yagi antenna with a good endfire characteristics with the measured bandwidth of 4.46 to 11.31 GHz (∼86.9%), a peak gain of 8.3 dBi, and the out-of-band suppression larger than 14 dB is achieved, without any additional external filtering circuits. When a pair of L-shaped parasitic elements are symmetrically placed on the top layer, a notch with −20.5 dBi measured gain rejection in the working frequency band can be introduced, which guarantees good interference suppression ability. The measured results show good agreement with the simulation. The proposed antennas are good candidates for in-vehicle Wi-Fi 6E, in-vehicle satellite communication, mobile-service, V2V communication applications.

A novel filtering nonmagnetic circulator based on the spatiotemporal modulation of microstrip filtering delay network using traditional PCB processing technology is presented in this article. By utilizing switches controlled by periodic signal to realize spatiotemporal modulation of microstrip filtering delay networks with large and flat in-band group delay response, the symmetry of time reversal is broken and thus the nonreciprocity characteristic is realized. By combining the advantages of both circulators and filters, a filtering nonmagnetic circulator is thus constructed. It is worth noting that all the circuit elements are fabricated using the traditional PCB technology, which is easy to integrate with other systems. The working mechanism is investigated theoretically and numerically. Moreover, the transmission characteristics and the group delay of the microstrip filtering delay network, which play a key role in spatiotemporal modulation in the proposed nonmagnetic circulator, are analyzed in detail. The prototype of the proposed filtering nonmagnetic circulator is designed, simulated, fabricated, and measured. The measured results agree well with the simulated ones. The nonmagnetic filtering circulator operates at 930–990 MHz with a relative bandwidth of 6.25%, and good filtering characteristics are also obtained. The maximum isolation of the circulator in the passband is better than −20 dB and the insertion loss (IL) is only 2.6 dB. Due to the compact microstrip filtering delay network with large group delay is used to realize the filtering and delay function in the system, good filtering characteristics are integrated into the nonmagnetic circulator, and the oversize is also reduced.

Vienna rectifier is a boost-type rectifier with unidirectional energy flow, which is widely used in many applications. Under unbalanced grid, there will be even harmonics in dc-link voltage and odd harmonics in input current if the traditional control methods are used. Therefore, two control methods for Vienna rectifier under unbalanced grid are introduced, which are balanced positive-sequence current control and instantaneous active power control. The current zero-crossing distortion (CZCD) is an inherent issue for Vienna rectifier due to its special circuit topology. The displacement angle between the input current and the voltage is revealed, which is the essence of CZCD. The issue of CZCD is more complex under unbalanced grid than that under balanced grid, and CZCD cannot be addressed well under existing suppression method. A novel method that can minimize CZCD under unbalanced grid is also proposed. The proposed method works well under both balanced and unbalanced grid. Finally, an experimental platform is built, and the feasibility and superiority of the proposed method are verified by comprehensive experiments.

In this article, we proposed a fiber Bragg grating (FBG) based on identification of bubble collision and bounce. The FBG target sensor detects the vibration signal resulting from the multiple rebound motions of the bubble after colliding with the target. The tension, diameter, and velocity of the bubbles are related to the frequency and amplitude of the vibration signal. In the test of a single target sensor, the frequency of air bubbles is measured to be within the range of 80–100 Hz, which is higher than the frequency of oil bubbles within the range of 0–10 Hz. An annular sensing array based on a 3-D printed structure is also demonstrated for measuring the cross-sectional bubbles passing through the pipeline. The proposed sensor introduces a new multiphase sensing principle, paving a way for optical fiber holdup sensor development.

A magnetic generating device was proposed to regulate the transverse and backward flow of weld pool for high-speed gas metal arc welding (GMAW). Compound external magnetic field (EMF) was simulated to verify the feasibility of designed magnetic generating device. The highest welding speed with good weld bead appearance was 1.7 m/min with the wire feed speed of 9.0 m/min when compound EMF was applied. The effect of the compound EMF on the arc and droplet motion was studied by image acquisition system. The suppression mechanism of the compound EMF on the undercut defect of high-speed GMAW was analyzed. The mechanism of the influence of the applied compound EMF on different welding speeds and welding currents was studied by the application of the compound EMF-assisted welding process, and low-cost, high-quality, and high-speed welding technology was realized.

Zwitterionic hydrogels are electrically neutral materials with both cationic and anionic groups that impart excellent anti-fouling properties and ion channel orientations. However, pure zwitterionic hydrogels generally exhibit low strength and toughness. In this study, it has been discovered that polymerizable zwitterionic monomers in aqueous solution exhibit a unique liquid–liquid phase separation phenomenon at a high monomer concentration of ≥50 wt%, resulting in pure and commercial zwitterionic hydrogels with high compressive strength (6.5 MPa) and high toughness (2.12 kJ m−2). This phase separation and the corresponding aggregations might be caused by strong dipole–dipole interactions among residual zwitterionic monomers under the lack of free-water condition. The synergistic effect of liquid–liquid phase separation and polymer entanglement enhances the mechanical strength, toughness, self-recovery, and anti-freezing properties of pure polyzwitterionic hydrogels. Moreover, the high fracture energy of highly elongated yet tough polyzwitterionic hydrogels facilitates the development of high crack propagation resistance, which supports an expanded role in tissue engineering, soft flexible devices, and electronics applications with improved durability. A wide range of applications for the proposed polyzwitterionic hydrogels is demonstrated by the development and testing of a strain sensor and a triboelectric nanogenerator device. Our findings provide novel insights into the network structure of pure polyzwitterionic hydrogels.

In this article, a novel compact filtering power divider (FPD) with sharp frequency selectivity, high in-band isolation, and deep out-of-band suppression is proposed. The realization of filtering and power division functions is achieved by utilizing a U-shaped resonator coupled square ring resonator (UR-CSRR). The UR-CSRR configuration is proposed using a modified U-shaped resonator (UR) coupled with a modified square ring resonator (SRR). By loading a pair of open stubs at the ends and a stepped impedance open stub at the center of an SRR, the modified SRR with two controllable transmission zeros (TZs), which can be used to adjust the bandwidth and improve the upper stopband, is realized. The modified UR is formed by loading a single open stub and two pairs of open stubs with the ability to generate a controllable TZ at the right edge of the passband at the center and in the upper stopband at the ends of a UR, respectively. To generate the output signal, two output lines are inserted on both sides of the single open stub, which can also introduce two TZs. In addition, two resistors are introduced between the two output lines to obtain high in-band isolation. To validate this design concept, an FPD with a center frequency of 3 GHz is designed, simulated, and measured. Measurements indicate that the minimum in-band insertion loss is 1.1 dB, the 3-dB fractional bandwidth (FBW) is approximately 25%, the out-of-band suppressions of both upper and lower stopband are greater than 30 dB, and the in-band isolation is greater than 25 dB. The simulated and measured results are in good agreement, demonstrating the feasibility of the proposed design strategies.

Carbon dots (CDs) inevitably accumulate in soils due to their widespread use, affecting soil enzyme activities and microbial community structure. Soil microbial-mediated dissimilatory iron reduction processes will affect soil elemental cycling and heavy metal transport and transformation. Yet few studies have characterized changes in dissimilatory iron reduction and speciation transformation of heavy metals following application of CDs to the soil system. Here, the linkage between heavy-metal speciation changes and CD imposition was investigated by incubating two types of doped carbon dots (nitrogen-doped and nitrogen–phosphorus-doped) into mine soils. Results showed that the application of nitrogen–phosphorus-doped carbon dots (N,P-CDs) was beneficial to improving soil acidity. In addition, the application of CDs immobilized Pb and Zn but also increased the mobility of Cu in the soil. Furthermore, the addition of CDs increased Fe(ii) and total Fe content, suggesting that it promoted dissimilated iron reduction. The activity of dehydrogenase was activated by CDs, while the activation of catalase was not significant. The application of CDs altered the structure and diversity of soil microbial communities with a dependence on the type of CDs and the time of incubation. Combined with the redundancy analysis (RDA) results, the microbial community was tightly related to pH, residual Zn concentration, Fe(ii), and total Fe. The results of this study contribute to the understanding of the role of CDs in geochemical element cycling and remediation of heavy metal contaminated soils.

Graphene nanoribbons (GNRs), nanometre-wide strips of graphene, are promising materials for fabricating electronic devices. Many GNRs have been reported, yet no scalable strategies are known for synthesizing GNRs with metal atoms and heteroaromatic units at precisely defined positions in the conjugated backbone, which would be valuable for tuning their optical, electronic and magnetic properties. Here we report the solution-phase synthesis of a porphyrin-fused graphene nanoribbon (PGNR). This PGNR has metalloporphyrins fused into a twisted fjord-edged GNR backbone; it consists of long chains (>100 nm), with a narrow optical bandgap (~1.0 eV) and high local charge mobility (>400 cm2V–1s–1by terahertz spectroscopy). We use this PGNR to fabricate ambipolar field-effect transistors with appealing switching behaviour, and single-electron transistors displaying multiple Coulomb diamonds. These results open an avenue to π-extended nanostructures with engineerable electrical and magnetic properties by transposing the coordination chemistry of porphyrins into graphene nanoribbons.

The intelligent detection technology driven by X-ray images and deep learning represents the forefront of advanced techniques and development trends in flaw detection and automated evaluation of light alloy castings. However, the efficacy of deep learning models hinges upon a substantial abundance of flaw samples. The existing research on X-ray image augmentation for flaw detection suffers from shortcomings such as poor diversity of flaw samples and low reliability of quality evaluation. To this end, a novel approach was put forward, which involves the creation of the Interpolation-Deep Convolutional Generative Adversarial Network (I-DCGAN) for flaw detection image generation and a comprehensive evaluation algorithm named TOPSIS-IFP. I-DCGAN enables the generation of high-resolution, diverse simulated images with multiple appearances, achieving an improvement in sample diversity and quality while maintaining a relatively lower computational complexity. TOPSIS-IFP facilitates multi-dimensional quality evaluation, including aspects such as diversity, authenticity, image distribution difference, and image distortion degree. The results indicate that the X-ray radiographic images of magnesium and aluminum alloy castings achieve optimal performance when trained up to the 800th and 600th epochs, respectively. The TOPSIS-IFP value reaches 78.7% and 73.8% similarity to the ideal solution, respectively. Compared to single index evaluation, the TOPSIS-IFP algorithm achieves higher-quality simulated images at the optimal training epoch. This approach successfully mitigates the issue of unreliable quality associated with single index evaluation. The image generation and comprehensive quality evaluation method developed in this paper provides a novel approach for image augmentation in flaw recognition, holding significant importance for enhancing the robustness of subsequent flaw recognition networks.

In this letter, a cluster-centric (CC)-based cell-free massive multiple-input multiple-output (CF-mMIMO) system is considered, which realizes multi-user multiplexing in each user-cluster formed by neighboring users and served by surrounding antennas. Then, the interference suppressing multi-user zero-forcing (IS-MU-ZF) is considered to further eliminate the inter-cluster interference. But the IS-MU-ZF faces a capacity drop problem. Thus, an adaptive interfering user selection method is proposed to flexibly determine the set of interfering users for each user-cluster. It is confirmed by computer simulation that the proposed CC-based CF-mMIMO system utilizing the IS-MU-ZF with the proposed adaptive interfering user selection method outperforms the well-known user-centric (UC)-based CF-mMIMO system in terms of capacity and computational complexity when the accuracy of channel estimation is guaranteed.