Search Results (625)

The temperature regulation of nonlinear continuous stirred tank reactor (CSTR) processes remains a challenging control problem due to strong nonlinearities, time-delay effects, and sensitivity to disturbances and parameter variations. Conventional proportional–integral–derivative (PID)-based control strategies often fail to provide the robustness and precision required under such conditions, motivating the use of more flexible controller structures and advanced optimization techniques. In this study, an enhanced joint-opposition artificial lemming algorithm (JOS-ALA) is proposed for the optimal tuning of a fractional-order PID (FOPID) controller applied to CSTR temperature control. The proposed JOS-ALA incorporates a joint opposite selection mechanism into the original ALA to improve population diversity, convergence stability, and resistance to local optima stagnation. A nonlinear CSTR model is linearized around a stable operating point, and the resulting model is employed for controller design and optimization. The FOPID controller parameters are tuned by minimizing a composite cost function that simultaneously accounts for tracking accuracy, overshoot suppression, and instantaneous error behavior. The effectiveness of the proposed approach is assessed through extensive simulation studies and benchmarked against state-of-the-art and high-performance metaheuristic optimizers, including ALA, electric eel foraging optimization (EEFO), linear population size reduction success-history based adaptive differential evolution (L-SHADE), and the improved artificial electric field algorithm (iAEFA). The benchmarking set is further extended with the success rate-based adaptive differential evolution variant (L-SRTDE) to broaden the comparative evaluation. Simulation results demonstrate that the JOS-ALA-based FOPID controller consistently achieves superior performance across multiple criteria. Specifically, it attains the lowest mean cost function value of 0.1959, eliminates overshoot, and yields a normalized steady-state error of 4.7290 × 10⁻⁴. In addition, faster transient response and improved robustness under external disturbances and measurement noise are observed when compared with competing methods. Statistical reliability of the observed performance differences is additionally examined using a Wilcoxon signed-rank test conducted over 25 independent runs. The resulting p-values confirm that the improvements achieved by the proposed approach are statistically significant at the 5% level across all pairwise algorithm comparisons. These findings indicate that the proposed JOS-ALA provides an effective and reliable optimization framework for high-precision temperature control in nonlinear CSTR systems and offers strong potential for broader application in complex process control problems. Full article

High-power clutches operating under high-frequency engagement–disengagement cycles demand piston ring seals with exceptional leakage control and tribological reliability. Conventional architectures often experience lubrication failure and severe adhesive wear during transient pressure fluctuations. This research proposes an autonomous intelligent sealing strategy leveraging fluid pressure-induced morphological evolution. By strategically integrating periodic macroscopic structural relief features on the non-sealing surface, the sealing interface transforms into a micron-scale wavy topography in response to hydraulic loading. This structurally embedded intelligence significantly improves fluid pressure distribution, facilitating a transition toward a more favorable lubrication regime. Furthermore, a “self-healing and positional stagnation” logic is elucidated: upon pressure dissipation, the induced waviness elastically recovers to a planar state to ensure sealing integrity, while the ring maintains its axial position due to the predominant frictional resistance of the secondary seal. This synergistic mechanism effectively precludes deleterious dry friction during the clutch disengagement phase. High-fidelity numerical investigations, benchmarked against established experimental data, identify the rectangular groove configuration as the optimal geometry for maximizing waviness amplitude (≈1.5 µm). This research provides a robust framework for developing responsive, zero-wear intelligent seals in advanced power transmissions. Full article

The increasing penetration of converter-interfaced generation raises critical concerns for power system stability, especially during rapid transients and system split events that are not yet adequately addressed in current grid code compliance tests. This paper assesses the resilience of a Virtual Synchronous Machine (VSM) in comparison with a grid-following photovoltaic (PV) inverter through a combined framework of standardized benchmark tests and realistic system split scenarios. In benchmark testing, the VSM provided synthetic inertia by delivering a transient-power burst from a 0.30 p.u. setpoint to 0.545 p.u. (on a 20 MVA base, representing 54.5% of rated capacity) under a $-0.4$ Hz/s frequency ramp, corresponding to an equivalent inertia constant of approximately 15 s. With the limited frequency-sensitive mode–underfrequency (LFSM-U) function enabled, it sustained additional active power up to 0.61 p.u. once the frequency fell below 49.8 Hz. The PV inverter, by contrast, demonstrated compliance with conventional grid requirements: it curtailed power through LFSM-O during overfrequency conditions and injected 0.25 p.u. of reactive current during a fault ride-through (FRT) event at 1.129 p.u. voltage. In system split tests, the VSM absorbed surplus PV generation, stabilizing frequency after a transient rise to 52.8 Hz and containing voltage excursions beyond 1.2 p.u. During imbalance stress, it absorbed 1.266 MW against its 1.0 MW rating for approximately 2–3 s, corresponding to a 26.6% overload that falls within typical IGBT transient thermal capability but would require supervisory intervention (e.g., PV curtailment or load management) if sustained. These results demonstrate that while the PV inverter contributes valuable voltage support, only the grid-forming VSM maintains frequency stability and ensures secure islanded operation. The novelty of this study lies in integrating standardized compliance tests with system split scenarios, providing a comprehensive framework for evaluating grid-forming controls under both regulatory and resilience-oriented perspectives and informing the evolution of future grid codes. Full article

Intentional high-power electromagnetic (EM) interference poses a serious threat to sensitive electronic systems and often manifests as ultra-wideband (UWB) sub- and nanosecond pulses. Metallic shielding enclosures with technological apertures are commonly used for protection; however, apertures enable electromagnetic coupling into the enclosure and limit shielding performance. While most existing studies focus on transient disturbances with durations exceeding the enclosure transit time, this work addresses an ultrashort high-power subnanosecond UWB plane-wave pulse whose duration is significantly shorter than the enclosure transit time, a regime that remains insufficiently explored. A time-domain numerical analysis is performed for a low-profile rectangular metallic enclosure with a front-wall aperture, focusing on internal EM field evolution, internal pulse formation, and polarization-dependent shielding effectiveness. Three-dimensional full-wave simulations were carried out using CST Microwave Studio over a 90 ns observation window. The results show that the incident pulse excites primary subnanosecond EM waves inside the enclosure, which subsequently generate secondary waves through multiple reflections from the enclosure walls. Their interaction produces complex, long-lasting, time-varying internal field patterns. Although attenuated, the resulting internal subnanosecond pulses repeatedly traverse the enclosure interior, forming a pulse train-like sequence that may pose a cumulative electromagnetic threat to internal electronics. A key contribution of this work is the quantification of time-dependent local shielding effectiveness for both electric and magnetic fields, derived directly from the internal pulse train-like series obtained in the time domain. The concept of local, time-dependent shielding effectiveness provides physical insight that cannot be obtained from a single globally averaged SE value. In the case of ultrashort electromagnetic pulse excitation, the internal field response of an enclosure is strongly non-stationary and highly non-uniform in space, with local field maxima occurring at specific times and locations despite good average shielding performance. Time-dependent local SE enables identification of worst-case temporal conditions, repeated high-amplitude internal exposures, and critical regions inside the enclosure where shielding is significantly weaker than suggested by global metrics. Therefore, while conventional SE remains useful as a summary measurand, local time-dependent SE is essential for assessing the actual electromagnetic risk to sensitive electronics under ultrashort pulse disturbances. In addition, a global shielding effectiveness metric mapped over selected enclosure cross-sections is introduced to enable rapid visual assessment of shielding performance. The analysis demonstrates a strong dependence of internal wave propagation, internal pulse formation, and both local and global shielding effectiveness on the polarization of the incident subnanosecond EM pulse. These findings provide new physical insight into aperture coupling and shielding behavior in the ultrashort-pulse regime and offer practical guidance for the assessment and design of compact shielding enclosures exposed to high-power UWB EM threats. Full article

Driving style recognition plays a crucial role in improving the operational safety, fuel efficiency, and intelligent control of commercial vehicles. Under real-world driving conditions, Controller Area Network (CAN) bus data from commercial vehicles simultaneously contain rapid transient variations induced by pedal and braking operations, as well as long-term behavioral trends reflecting driving habits, exhibiting pronounced multi-temporal characteristics. In addition, such data are typically affected by high noise levels, high dimensionality, and highly variable operating conditions, which makes it difficult for methods relying on single-scale features or handcrafted rules difficult to maintain robust and stable performance in complex scenarios. To address these challenges, this paper proposes a driving style classification network, termed the Multi-Scale Convolution and Efficient Channel Attention Network (MSCA-Net). By employing parallel convolutional branches with different temporal receptive fields, the proposed network is able to capture fast driver responses, local temporal dependencies, and long-term behavioral evolution, enabling unified modeling of cross-scale temporal patterns in driving behavior. Meanwhile, the Efficient Channel Attention mechanism adaptively emphasizes CAN signal channels that are highly relevant to driving style discrimination, thereby enhancing the discriminative capability and robustness of the learned feature representations. Experiments conducted on real-world multi-dimensional CAN time-series data collected from commercial vehicles demonstrate that the proposed MSCA-Net achieves improved classification performance in driving style recognition. Furthermore, the potential application of the recognized driving styles in adaptive Automated Manual Transmission shift strategy adjustment is discussed, providing a feasible engineering pathway toward behavior-aware intelligent control of commercial vehicle powertrains. Full article

This study develops an analytical description of the motion of dilute solid particles in the boundary layer of laminar horizontal flows subjected to weak transverse pulsations. The analysis is formulated for dilute spherical solid particles subjected to transverse velocity pulsations in a laminar boundary-layer flow. A coupled matrix representation of the governing equations is formulated, and closed-form solutions are obtained using Laplace transformation. The analytical expressions capture transient evolution, forced oscillations, resonance effects, and long-term behaviour for particles with different density ratios. Numerical evaluation shows that light particles migrate toward faster regions of the boundary layer and accelerate longitudinally, while heavy particles move toward slower layers and decelerate. Transverse pulsations generate oscillatory trajectories whose amplitude increases near resonance. Impulsive perturbations superimposed on the continuous motion lead to discontinuous transitions consistent with the linear matrix system. The results provide a unified physical interpretation of particle redistribution mechanisms in boundary layers and offer a compact analytical tool for dilute multiphase flow modelling. Full article

Reliable bearing fault diagnosis under complex operating conditions is often hindered by the loss of critical information during feature extraction, particularly for weak fault signatures embedded in vibration signals. To address this challenge, this work proposes a parallel multi-domain deep learning framework that emphasizes the preservation and complementary exploitation of time-domain, frequency-domain, and time–frequency representations. The proposed framework integrates temporal modeling to capture long-range signal evolution, phase-aware frequency-domain analysis to preserve amplitude–phase coherence, and transient-enhanced time–frequency representations to highlight weak impulsive features in noisy environments. To effectively integrate heterogeneous representations, a dynamic self-attention-based fusion strategy is introduced, enabling adaptive interaction and importance reweighting among multi-domain features. Experimental studies conducted on bearing datasets from Huazhong University of Science and Technology and the University of Cincinnati demonstrate that the proposed method achieves diagnostic accuracies of 99.63% and 99.82%, respectively, significantly outperforming state-of-the-art deep learning and multi-domain diagnostic methods, with accuracy improvements exceeding 20% compared to representative baseline models. Furthermore, ablation and robustness analyses confirm that the coordinated preservation and fusion of multi-domain information significantly enhance diagnostic reliability and generalization performance under complex operating conditions. Full article

Integrating diamond with GaN provides an effective pathway to mitigate self-heating. However, the thermal boundary resistance (TBR) remains a persistent bottleneck for further heat dissipation. While carbon (C) diffusion into the SiNx interlayer is known to reduce TBR, the associated stress evolution and its impact on device performance remain underexplored. In this work, the synergistic regulation of heat transport and electrical performance induced by C diffusion was systematically investigated. Transmission electron microscopy (TEM) was employed to characterize the interfacial microstructure and the influence of C diffusion on the interface. To further assess the resulting impact on heat dissipation, transient thermoreflectance was utilized to precisely quantify the thermal transport within the heterostructures. Classical molecular dynamics (MD) simulations were then performed to analyze the underlying physical mechanisms, revealing that intensifying C diffusion increases the phonon density of states overlap and effectively reduces the TBR. Furthermore, the intrinsic stress was quantified through geometric phase analysis (GPA) based on TEM images, demonstrating that the stress induced during the diffusion process propagates to the AlGaN/GaN heterostructure. Crucially, this stress modulation enhances the piezoelectric polarization by approximately 32%, resulting in a 5% increase in the two-dimensional electron gas (2DEG) sheet density. These findings provide a comprehensive strategy for optimizing the thermal management and mechanical reliability of high-power GaN devices. Full article

In response to thermal failure risks in ultra-high voltage (UHV) bushing online monitoring devices and maintenance equipment—caused by high heat generation of electronic components and the intrinsically low thermal conductivity of conventional resin encapsulation materials—this study proposes a novel modification strategy based on flash Joule heating (FJH). Distinct from conventional interface modification methods, the proposed approach enables cross-scale, in situ microsoldering between multi-walled carbon nanotubes (MWCNTs) and carbon fibers (CFs), constructing a multiscale reinforcement network with integrated thermal transport and mechanical load transfer pathways. The transient ultra-high-temperature thermal shock generated by FJH not only effectively removes inert impurities on CF surfaces but also drives carbon structural reconstruction, enabling graphitic-level welding of MWCNTs onto the fiber surface. This micro-welded architecture fundamentally differs from traditional filler dispersion or interface coating strategies, which often suffer from the trade-off between interfacial thermal transport and mechanical bonding. By contrast, the FJH-induced carbon–carbon bonded nodes form a continuous conductive and load-bearing network at the micro–nano scale. Characterizations using scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) confirm successful in situ welding of MWCNTs onto CF surfaces. Meanwhile, FJH treatment effectively removes oxygen-containing functional groups and surface impurities. Analysis of carbon bonding evolution indicates that the welding efficiency reaches its maximum at 90 V. Macroscopic performance tests demonstrate that, compared with epoxy resin, the thermal conductivity of the multiscale reinforced system increases by approximately 168%, while the mechanical strength improves by 62.72%. This study provides new theoretical insights and technical pathways for the development of next-generation polymer composite materials with both high thermal conductivity and high mechanical strength. Full article

Hydroxyl-terminated polybutadiene (HTPB) propellants are widely used in aerospace applications owing to their excellent mechanical performance and storage stability, which are primarily governed by the crosslinked network formed during curing. Understanding the evolution of this network is therefore essential for optimizing propellant formulations and curing parameters. In this work, the curing behaviors of HTPB-based propellant slurries employing two representative curing agents, toluene diisocyanate (TDI) and isophorone diisocyanate (IPDI), were systematically investigated under isothermal conditions at 60 °C using low-field nuclear magnetic resonance (LF-NMR), combined with infrared spectroscopy, dynamic mechanical analysis, and macroscopic mechanical testing. The curing time and crosslink density of both propellant systems were quantitatively determined by LF-NMR crosslink densitometry, while transverse relaxation time measurements were used to monitor the mobility evolution of different molecular segments during curing. The results show that with increasing curing time, the crosslink density and crosslinked chain content progressively increased, whereas the free chain content decreased, accompanied by a transient increase and subsequent decrease in dangling chains. The curing endpoints of the HTPB/TDI and HTPB/IPDI propellants were determined to be approximately 1.25 days and 5.5 days, with corresponding final crosslink densities of 2.438 × 10⁻⁴ and 2.007 × 10⁻⁴ mol mL⁻¹, respectively. Excellent agreement between LF-NMR results and complementary characterization techniques confirms LF-NMR as an effective tool for studying curing reaction and network evolution in complex solid propellant systems. Full article

In transient high-pressure gas rock breaking, resilient sealing materials can reduce energy loss during rock breaking and ensure the effectiveness and safety of the operation. This study, utilizing experimental data and finite element analysis, investigates the impact of transient high-pressure gas on sealing methods. It compares the traditional single-layer concrete sealing with a novel three-stage concrete sealing method, highlighting its advantages. Furthermore, a three-stage approach is used to analyze the mechanical evolution of different sealing layers, and the sealing mechanism is revealed through energy-absorption analysis. Research findings indicate that the traditional single-layer concrete sealing method experiences severe damage, with a maximum damage value of 0.26. In contrast, the three-stage sealing method exhibits significantly less damage (mostly < 0.2), effectively improving sealing efficiency. The three-stage sealing method generally demonstrates lower stress levels compared to the single-layer concrete sealing method. After passing through the gravel and soil layers, the impact-induced stress becomes relatively stable, with stress levels at the center gradually approaching those at the hole’s walls. The central portion of the gravel layer shows a greater energy absorption effect than the two boundary areas, while the soil layer exhibits a linear relationship between deformation and energy absorption. The three-stage sealing method weakens the impact through a structural approach of “pressure-absorption-pressure”, where the gravel layer primarily disperses pressure, while the soil layer provides energy absorption and cushioning. The research findings have significant implications for the safe application of transient high-pressure gas rock breaking technology. Full article

To investigate the dynamic response and failure mechanism of tempered glass subjected to falling-ball impact, a controlled falling-ball impact experimental platform was established. Strain gauges were arranged at multiple locations on the glass surface to capture the transient strain responses under different impact conditions. Based on the experimental setup, a finite element model of tempered glass was developed using Abaqus to simulate the impact process and stress-wave propagation behavior. The experimental results show that falling-ball impact induces pronounced transient strain responses in tempered glass, with strain amplitudes decreasing as the distance from the impact center increases. The strain responses also exhibit clear vibration attenuation characteristics due to energy dissipation and boundary effects. The numerical simulation results are in good agreement with the experimental strain–time history curves in terms of peak strain, temporal evolution, and attenuation trends, confirming the reliability of the numerical model. Further analysis indicates that stress waves generated at the impact point propagate radially within the glass plate and undergo reflection and superposition at the boundaries, leading to localized stress amplification. When the impact energy exceeds a critical threshold, the induced stress surpasses the strength limit of tempered glass, resulting in structural failure. The findings provide theoretical and experimental support for the impact-resistant design and safety assessment of tempered glass. Full article

In the fabrication of ultrathin multilayer ceramic capacitors (MLCCs), the long-term stability of ceramic slurries is a critical yet often overlooked factor that can significantly influence coating uniformity, interfacial adhesion, and process reproducibility. Despite its industrial importance, the time-dependent evolution of slurry dispersion structures during storage and its direct impact on green sheet properties remain insufficiently understood. This study examined the time-dependent physicochemical evolution of barium titanate (BaTiO₃)-based green sheet slurries, which behave as colloidal gel-like dispersion systems, and their influence on the structural, optical, and interfacial properties of the resulting sheets. Dynamic light scattering revealed progressive yet uniform particle aggregation, while viscosity measurements indicated a gradual ~10% decrease over 960 h, reflecting reduced dispersion stability and progressive weakening of the slurry gel network during extended storage. The slurry, consisting of BaTiO₃ particles, polymeric binders, and plasticizers, forms a three-dimensional transient gel network, in which particle–particle and particle–binder interactions govern rheological behavior. The observed viscosity decrease and turbidity reduction indicate gel network relaxation and partial gel–sol–like transition behavior driven by aggregation. Cross-sectional scanning electron microscopy demonstrated that these changes produced a measurable reduction in final green sheet thickness, despite identical processing conditions. Furthermore, peel tests revealed that interfacial adhesion strength increased with storage time, attributable to localized solid enrichment within the slurry gel matrix and enhanced bonding at the release film interface. The reduced coating thickness also contributed to lower optical haze, reflecting a shortened light-transmission path. Collectively, these findings demonstrate that even moderate aggregation in a ceramic network-forming dispersion system substantially alters coating behavior, adhesion, and optical performance. The results underscore the importance of managing gel-network stability and rheology to ensure reliable green sheet fabrication and storage in MLCC manufacturing. Full article

The global challenge of antimicrobial resistance (AMR) has been framed primarily in terms of genetic resistance mechanisms. Nevertheless, bacteria can also survive antimicrobial stress through phenotypic plasticity, resulting in transient, non-genetic states such as tolerance, persistence, and population-level resilience. These phenotypic states complicate diagnostic efforts, diminish antibiotic efficacy, and contribute to the chronic nature of infections even in the absence of heritable resistance. This review evaluates phenotypic plasticity as a significant yet underrecognized factor in AMR, with a focus on responses to oxidative and photodynamic stress. Key manifestations of plasticity are discussed, including morphological and metabolic remodeling such as filamentation, small-colony variants, and metabolic rewiring, as well as envelope- and biofilm-associated heterogeneity and regulatory flexibility mediated by gene networks and horizontal regulatory transfer. The review highlights plastic responses elicited by reactive oxygen species-mediated stress and antimicrobial photodynamic inactivation, where single-cell heterogeneity, biofilm and mucus barriers, and light-dependent cues influence bacterial survival. Case studies are presented to demonstrate how photodynamic strategies can induce transient protective states and act synergistically with antibiotics, revealing mechanisms of action that extend beyond conventional single-target therapeutic models. Drawing on evidence from single-cell analyses, biofilm ecology, and experimental evolution, this review establishes phenotypic plasticity as a central element in the chemical biology of AMR. Enhanced understanding of plasticity is essential for advancing diagnostics, informing the development of adjuvant therapies, and predicting bacterial responses to novel antimicrobial interventions. Full article

To address the stringent insulation safety requirements of modern high-voltage transformers, accurately characterizing the transient electric field is critical. However, a significant problem remains: current engineering models typically rely on static capacitive distributions, failing to capture the dynamic electric field distortion induced by rapid space charge injection under lightning impulses. Therefore, a non-contact spatial electric field measurement method based on the optical Kerr effect was employed to analyze the influence of electrode material, voltage amplitude, and wavefront time. Unlike traditional simulation models that often assume constant mobility and focus solely on the shielding effect, this study reveals a non-monotonic electric field evolution driven by a ‘Static-Dynamic’ mode transition. The proposed model highlights two critical breakthroughs: (1) Mechanism Innovation: It experimentally verifies that charge injection is governed by the ion charge-to-mass ratio rather than just the work function, leading to a newly identified field enhancement phase during the wavefront that overcomes the limitations of capacitive models that underestimate transient stress. (2) Parameter Quantification: Precise spatiotemporal thresholds are established—negative charges traverse the gap within ~200 ns, while positive charges require ~10 μs to reach equilibrium. These findings provide experimentally calibrated time constants for simulation correction and offer new criteria for optimizing electrode materials in UHV transformers to mitigate transient field distortion. Full article