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Fixed-point or Newton-methods are typically employed for the numerical solution of nonlinear systems arising from discretization of nonlinear magnetic field problems. We here discuss an alternative strategy which uses Quasi-Newton updates locally, at every material point, to construct appropriate linearizations of the material behavior during the nonlinear iteration. The resulting scheme shows similar fast convergence as the Newton-method but, like the fixed-point methods, does not require derivative information of the underlying material law. As a consequence, the method can be used for the efficient solution of models with hysteresis which involve nonsmooth material behavior. The implementation of the proposed scheme can be realized in standard finite-element codes in parallel to the fixed-point and the Newton method. A full convergence analysis of all three methods is established proving global mesh-independent convergence. The theoretical results and the performance of the nonlinear iterative schemes are evaluated by computational tests for a typical benchmark problem. [ABSTRACT FROM AUTHOR]

• We develop an original method to estimate the rate of capacity utilization. • We find evidence of chronic excess capacity and hysteresis in many EU countries. • The method is robust to alternative specifications and to the end-sample bias. • The method is sufficiently flexible to allow more complex applications. We develop a structural method to estimate the rate of capacity utilization in 12 EU countries that consists of identifying the structural parameters of a Leontief production function, using a parsimonious theoretical specification. Parameters are correctly identified, stable and robust to alternative specifications. Our results provide evidence of persistent excess capacity and hysteresis in the rate of capacity utilization in many EU countries, especially after the 2008′s global financial crisis, thereby supporting the claim that larger fiscal deficits would have contributed to absorb excess capacity without producing persistent inflationary pressures or debt unsustainability. Despite the simplicity of our model, the method allows more complex macroeconomic specifications for country-specific applications. [ABSTRACT FROM AUTHOR]

The hybrid reluctance actuator (HRA) has achieved widespread application in scanning motion tasks. However, the nonlinear perturbations arising from position-dependent stiffness fluctuations, hysteresis, eddy, and flux leakage can significantly affect the control performance. To enhance the control performance of HRA-based systems in scanning motion, this paper introduces an adaptive feedforward method, known as the Chua operator-based Kalman feedforward compensator (COKFC), which aims to mitigate these nonlinear perturbations, with a PID controller serving as the central control element. In the COKFC approach, a Chua operator is employed to effectively capture the inverse hysteresis behavior. A Chua-based time-varying feedforward compensation model is then formulated to represent the inversion of the nonlinear perturbations inherent in the HRA. An improved Kalman filter is utilized for the real-time adaptation of the time-varying parameters within the feedforward compensation model. The design procedure for this control strategy is presented. Experimental evaluations are conducted on an HRA-based stage (HRA-BS), and comparisons are made between the proposed method and several advanced control methods. The experimental results demonstrate that the proposed COKFC method exhibits superior control performance for the scanning motion of the HRA-BS, highlighting its effectiveness in practical applications. [Display omitted] • A simplified Chua operator was created to capture inverse hysteresis. • A Chua operator-based feedforward compensation model was constructed for HRA. • A COKFC method was proposed for the adaptive feedforward control of HRA-BS. • Comparative experiments on HRA-BS are conducted to validate the method. [ABSTRACT FROM AUTHOR]

We present a comprehensive experimental study of the dynamics of electrostatic MEMS resonators under large excitations. We identified three frequency ranges where large oscillations occur; a non-resonant region driven by fast–slow dynamic interactions and two resonant regions. In these regions, we found a plethora of dynamic phenomena including cascades of period-doubling bifurcations, a bubble structure, homoclinic and cyclic-fold bifurcations, hysteresis, intermittencies, quasiperiodicity, chaotic attractors, odd-periodic windows within those attractors, Shilnikov orbits, and Shilnikov chaos. We encountered these complex nonlinear dynamics phenomena under relatively high dissipation levels, the quality factors of the resonators examined in this study were Q = 6.2 and 2.1. In the case of MEMS with higher quality factors (Q > 100) , it is quite reasonable to expect those phenomena to appear under relatively low excitation levels (compared to the static pull-in voltage). This calls for a new paradigm in the design of electrostatic MEMS that seeks to manage dynamic phenomena rather than attempt to avoid them and, thereby, overly restricting the design space. We believe this is feasible given the repeatable and predictable nature of those phenomena. [ABSTRACT FROM AUTHOR]

This study proposes a multi-fidelity paradigm for developing surrogates of degrading hysteretic systems under uncertainty through the use of deep operator networks (DeepONets). Instead of attempting to directly train a DeepONet on the original response, this study adopts a residual modeling approach wherein the DeepONet is trained on the discrepancy between the original (high-fidelity) data source and a relatively simpler (low-fidelity) representation of the system. Within these examples, a conventional Bouc-Wen model is treated as a "low-fidelity" representation given that it is free of any further assumptions about the nonlinear behavior, while the "high-fidelity" data is generated from different structures with various forms of complex hysteretic behavior. The results of this study show that the proposed multi-fidelity approach consistently outperforms standard surrogates trained on only the original datasets considering a variety of systems with unknown parameters. The results also show that the difference in performance grows as training data becomes more scarce, a critical consideration for many real-world engineering systems, and that the proposed multi-fidelity approach maintains its performance edge even when controlling for training time and noise in the training data. • Bi-fidelity DeepONet approach for modeling hysteretic, degrading systems is proposed. • Proposed bi-fidelity approach routinely produces lower mean validation errors. • Performance advantage of bi-fidelity network is greatest for limited training data. • Degree of "mis-match" between low- and high-fidelity models erodes performance. • Advantage of proposed network remains when controlling for computational costs. [ABSTRACT FROM AUTHOR]

A novel direct instantaneous torque control (DITC) strategy based on optimized conduction angle is proposed with the aim of reducing the torque ripple of permanent magnet-assisted switched reluctance motor (PMa-SRM) during the two-phase exchange (TpE) region in this paper. Firstly, according to the inductance characteristics, the TpE region is subdivided into TpE I and TpE II region where the turn-off angle is acted as the region separation point, and the corresponding torque hysteresis strategies are formulated in different regions. Secondly, K-fold extreme learning machine (ELM) method is used to optimize the turn-on angle in order that the current of incoming phase can quickly increase to maintain torque balance. In order to make full use of the ability of torque generation of two adjacent phases, the position where the torque of adjacent phases is equal is used as the turn-off angle of incoming phase. Finally, a 6/20 PMa-SRM prototype is simulated and verified. Compared with the conventional DITC strategy, the novel strategy not only diminish torque ripple and negative torque under different operating conditions, but also expands the operating range of the motor and improves the motor efficiency. [ABSTRACT FROM AUTHOR]

The biggest difficulty facing the grain growth (TGG) method is the compatibility between template and ceramic matrix. Different templates show great differences in texture degree. Consider the limitation of conventional single-template method, the strategy of dual-template textured ceramics and sintering aids were introduced in this work. With the addition of ST and NN templates into BNT system, the texture degree is higher than 90% and the electrostrain reach ∼ 0.5% with ultra-low hysteresis ∼ 15%, which cannot be realized in single template textured ceramics. The two templates and sintering aids play different roles in grain orientation growth, which is important for the compatibility among matrix and templates, leading to unique microstructures. Sintering processes clearly reveal the growth mechanism of textured ceramics under the joint action of two templates, and of course, the sintering aids are also indispensable. Regard to domain structure, the polar nanoregions can respond quickly under electric field, providing assistance for the realization of ultra-low hysteresis. [ABSTRACT FROM AUTHOR]

In this paper, the problem of adaptive neural network prescribed performance tracking control for a class of non-strict feedback time-delay systems constrained by full-state is studied. Radial basis function (RBF) neural networks (NNs) are integrated into the backstepping medium to deal with the uncertain functions and the barrier Lyapunov function (BLF) technique ensures that the state of the system does not exceed its limits. Subsequently, integrated with the Lyapunov–Krasovskii functional, the proposed control scheme makes the tracking errors converge to the preset region while the state constraint is not violated. Finally, the effectiveness of the scheme is supported by two simulation experiments. • An adaptive neural control scheme is proposed for nonlinear time-delay systems. • For unknown model, the proposed controller can achieve the control objective. • Coordinate transformation is used to improve system tracking performance. [ABSTRACT FROM AUTHOR]

Inferior electric field-induced strain and large hysteresis in the high-temperature (1- x)BiFeO 3 - x BaTiO 3 -based piezoceramics under low driving electric field, which restricts their practical applications, are dramatically technical bottlenecks. Herein, we successfully prepare the 0–3 type composite piezoceramics with super strain properties under a small electric field. Electric field-induced strain and normalized strain coefficient in the 0–3 composite piezoceramics have been severally increased by 161% and 215% than those of non-composite piezoceramics, and the hysteresis and remnant strain in the 0–3 composite piezoceramics have been decreased by 230% and 165% compared with non-composite piezoceramics. Superior electric field-induced strain properties originate from strain and polarization couple, promoting domain switching at low driving electric field, and the novel strategy will accelerate the development and practical applications of lead-free piezoelectric ceramics. • Electric field-induced strain in 0-3 composite ceramics has been enhanced by 161% compared to that of non-composite ceramics. • The hysteresis in 0-3 composite piezoceramics is decreased by 230% than that of non-composite ceramics. • Superior electrostrain properties under the low electric field are attributed to the strain and polarization coupling. [ABSTRACT FROM AUTHOR]

In this paper, for macro–micro composite motion platform with piezoelectric hysteresis, an finite-time adaptive robust control method based on extended hysteresis observer is proposed. The dynamic model of macro–micro system is constructed at first. An extended hysteresis observer was designed to estimate the actual displacement and speed of motion system. Then, an adaptive robust control law is designed to eliminate the uncertain hysteresis model parameters. After this, exponential convergence result of the proposed control method is given and proved. By setting the expected bandwidth of macro–micro system, the gain adjustment process of the control method can be reduced in computation. The effectiveness of the proposed control method is demonstrated by comparison with other control methods in simulation, and the proposed control method has more stable tracking effect and smaller tracking error. • Finite-time adaptive robust controller for Macro–micro composite platform. • Design and implementation of extended state observer for piezoelectric hysteresis. • Design of gain adjustment process to simplify calculation. [ABSTRACT FROM AUTHOR]

Wildfires are hazards of increasing significance in recent decades. Our ability to forecast the evolution of fire regimes is inhibited by the lack of records of key fire parameters such as fire severity. Boron isotopes in the soil clay fraction have been shown to vary with fire severity, where increased δ 11B coincides with higher fire severity. To elucidate the relationship between the B isotope composition of soil clays and fire events, we performed adsorption experiments by reacting rainwater with combusted leaves to analyse how B isotopes are fractionated during processes leading to the imparting of boron from plants to clay minerals in soil during and following combustion. We find that < 5% of B is volatilised during combustion of leaves and barks, where 11B is preferentially volatilised. No isotopic fractionation was detected during the leaching of leaves ash with rainwater, possibly due to the large water:clay ratio in our experiments. Adsorption of B from leaching solutions onto clay minerals shows isotopic fractionation, and hysteresis of the adsorbed B fraction. For experiments at pH between 7 and 9, the isotope fractionation between adsorbed and dissolved B (Δ 11B adsorbed-dissolved) ranges from −8.8 to −14.5 ‰ , indicating preferential adsorption of 10B onto clays compared to 11B. For experiments at pH > 10, the Δ 11B adsorbed-dissolved values range from +11.2 to +19.4 ‰ , indicating a preferential adsorption of 11B over 10B. Irregardless of pH, clay fractions in all experiments show increases in δ 11B, as the leaching solutions have high δ 11B relative to the soil clay minerals prior to their interaction. Ash of leaves combusted at 550 °C (highest temperature in our experiments) induce the greatest increase in solution pH and δ 11B in clays. Our experiments suggests that the higher B isotope composition of clays following a high severity fire is likely imparted by solutions that leach isotopically heavy B from the combusted canopy. [ABSTRACT FROM AUTHOR]

The high strain hysteresis has impeded lead-free piezoelectric ceramics to replace lead zirconate titanate ceramics applied in actuators. In this study, we report a significant advancement with the synthesis of a novel BiFeO 3 -BaTiO 3 -(Ba 0.6 Sr 0.4)TiO 3 (BF-BT-BST) system. The optimal composition has demonstrated a remarkable strain of 0.42 % coupled with a notably low hysteresis of 21 %. It is found that the incorporation of BST into BF-BT facilitates the transition from the rhombohedral phase to the pseudo-cubic phase, which in turn significantly enhances the relaxor ferroelectric characteristics of the ceramic. Through adjusting the composition proportion of BST, a unique ferroelectric domain structure is established for the BF-BT-0.04BST ceramic, where polar nanoregions (PNRs) are surrounded by ferroelectric macrodomains. The domain structure enables the ceramic to have the ability to respond the external electric field quickly compared to the PNRs for typical relaxor composition, thereby leading to large strain and low hysteresis simultaneously. Hence, it is inferred that the ferroelectric macrodomains simplify the response process of the PNRs under electric field. This study provides an efficient strategy to break through the bottleneck of large strain hysteresis for BF-BT ceramic, and gives a deep comprehension for the improvement of the strain characteristics. [ABSTRACT FROM AUTHOR]

Hydrogen is rapidly emerging as a clean and versatile energy carrier addressing challenges of climate change and energy sustainability. With increasing energy demand and rising application of hydrogen energy, safety while harnessing hydrogen energy is a primary concern. To enhance safety, it is critical to detect hydrogen gas during its leakage which is otherwise challenging due to its colourless, odourless and inflammable nature. Hence, there is an urgent need for the development of hydrogen sensors for rapid response, maximum absorption/desorption, high selectivity, a wide dynamic range, and a low detection limit. This review provides a comprehensive analysis of emerging nanomaterials and their composites spanning from 0D to 3D for hydrogen sensing, emphasizing the underlying mechanisms. It also deliberates on the advantages and disadvantages of a wider range of advanced materials including noble metals, metal oxide semiconductors (MOS), transition metal dichalcogenides (TMD), metal organic frameworks (MOF), Xenes and MXenes pondering over hysteresis phenomenon, commonly observed as a limitation of noble metal-based hydrogen sensors. Among these emerging materials, two dimensional nanomaterials stand out as the optimal choice for hydrogen sensing due to their large surface area, exceptional electrical properties, low operating temperatures, and ease of chemical modification. Carbon-based materials, TMDs, MOFs, and MXenes have higher gas absorption capability and excellent mechanical properties, making them suitable for low/room temperature sensing and wearable sensing platforms. The review underscores the need for reliable sensing materials and presents challenges in quantitative detection of hydrogen offering future directions for research in this field. [Display omitted] • The review features the urge to develop hydrogen sensors. • It spans a wide range of new materials used for hydrogen sensing over the last two decades. • The mechanism of hydrogen adsorption & desorption is elaborated. • The article highlights challenges & prospects of materials for hydrogen sensing. • This article is useful to researchers, scientists, and engineers working in this field. [ABSTRACT FROM AUTHOR]

In order to solve the coupled hysteresis and resonance problems in three-degree-of-freedom tip-tilt-piston piezoelectric stage, a coupled hysteresis model and a coupled integral resonance compensation model are designed. The inverse coupled hysteresis feedforward control combined multi-axis coupled resonance control and high-gain integral tracking controller are used to improve the tracking speed and positioning accuracy of the stage. Firstly, a kinematic model of the stage is built to translate the three-degree-of-freedom motion of the end-effector into the outputs of three piezoelectric actuators. Then, a coupled hysteresis model based on the rate-dependent Prandtl–Ishlinskii model is established and parameterized to simultaneously compensate for the hysteresis of a single piezoelectric actuator and the coupled hysteresis between multiple piezoelectric actuators. The effectiveness of the model is verified by open-loop and closed-loop inverse model feedforward control experiments. Afterwards, a coupled integral resonance compensation model is also established and parameterized to suppresses the resonance and expand the system bandwidth. Finally, the proposed controller is used to conduct tracking experiments on a composite signal, and the results show that the accuracy and speed of trajectory tracking are further improved, and the mechanical coupling between axes are significantly reduced. • A coupled hysteresis model and an inverse coupled hysteresis model are established. • A coupled integral resonance compensation model is established. • The coupling parameters of the two models are identified and optimized. • A composite control method including an inverse coupled hysteresis feedforward and a coupled resonance control is used. • The composite trajectory tracking experiment validates the effectiveness of the composite control methods. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) stability problem of triple-step slopes is important due to their unique profiles under natural rainfall conditions. In this paper, an innovative approach was proposed for rapidly evaluating the stability of triple-step slopes, which considers the effects of diverse hydraulic hysteresis paths caused by rainfall and drought alternation. Considering diverse hydraulic hysteresis paths, a 3D upper-bound analysis (UBA) mechanical model was developed. On this basis, a new analytical solution for the stability number (N S) of 3D slopes under the influence of hydraulic hysteresis was derived through the work and energy equation. The comparisons showed that the new analytical solution and proposed method are correct. Then, ranges of the controlling parameters of triple-step slopes were designed for practical use in slope engineering. Comprehensive discussions were presented, considering four distinct hydraulic hysteresis cases within the context of two typical scenarios involving silty and sandy soils. The results could provide a reference for the design and construction of triple-step slopes where rainy and drought conditions frequently alternate. [ABSTRACT FROM AUTHOR]

In this study, a novel estimation scheme is proposed for identifying extended Wiener–Hammerstein systems with hysteresis nonlinearity subject to quantised measurements. The proposed scheme is established in a self-error learning framework to achieve high-performance parameter estimation compared with classic error feedback learning estimation algorithms. Initially, the useful identification data can be extracted from contaminated system data by introducing an adaptive filter. Then, with the help of the filtered data, the identification error expression used to establish the estimator is derived. Subsequently, an online compensation estimation error variable is proposed to eliminate the effect of the regression vector on the convergence performance. A new adaptive law is designed with adaptive recursive gain, considering the compensation estimation error data and parameter initial error data. Under general persistent excitation (PE) condition, the PE condition of the regressor information is verified online, and the estimator convergence is strictly proven. Finally, the statistical results of two illustrated examples and a real-word example are provided to validate the positive features and effectiveness of the proposed estimation scheme. • Adaptive law is updated by using the self-error information rather than non-self-error data. • Cost function is established by right of the compensated error and initial error data. • The effect of regressor on estimator is remedied by considering a compensation matrix. • Introduced filter takes into account system prior knowledge and the performance is improved. [ABSTRACT FROM AUTHOR]

The intricate woven structure of two-dimensional woven carbon fiber-reinforced silicon carbide (2D C/SiC) poses challenges to the investigation of damage failure mechanisms and the prediction of material performance, thereby limiting its further application in aerospace engineering. In this work, static/dynamic short beam shear tests with different densities of 2D C/SiC were carried out. It was observed that high-density specimens with fewer microporous defects exhibited better strength characteristics than those with lower density. Specifically, the shear strength of 2D C/SiC with a density of 2.07 g/cm³ increased by 18.6% compared to that of the specimen with a density of 1.94 g/cm³. The transient hysteresis strengthening effect of materials at high strain rates was discovered through cross scale research methods. It was found that deformation coordination ability of 2D C/SiC under dynamic loading was weaker than that under quasi-static conditions. Moreover, the deformation hysteresis in temporal and spatial distributions induced significant fiber plucking, further accelerating dislocation movement within the internal lattice and thereby enhancing strength of the material. The failure path of materials often follows the direction of pore defects, and stress concentration leads to cracking behavior of fiber bundles. Furthermore, microcracks within the matrix, caused by residual stress, resulted in localized regions of reduced strength. This induced the matrix cracking failure with further crack expansion within the material structure under external loads. To provide technical references for practical engineering applications and design, a realistic and effective finite element prediction model was developed for 2D C/SiC composites based on their structural characteristics. • Exploring the mapping relationship between material micropore defects and density, as well as the impact mechanism on material failure forms. • The transient hysteresis strengthening effect of the specimens under dynamic loads was proposed. • A real and effective 2D C/SiC finite element performance prediction model was constructed. [ABSTRACT FROM AUTHOR]

Novel (La 0.2 Eu 0.2 Nd 0.2 Sm 0.2 Pr 0.2)(Al 0.6 Co 0.4)O 3-δ (HE-1) and (La 0.2 Eu 0.2 Nd 0.2 Sm 0.2 Ca 0.2)(Al 0.6 Co 0.4)O 3-δ (HE-2) high-entropy ceramics were synthesized via solid-phase reaction technology. These two ceramics simultaneously own excellent infrared radiation performance and low degradation. The mechanism of emissivity enhancement was investigated, and emissivity decay of ceramics heated at 1500 °C for various holding time was studied. The results verify that the synthesized ceramics have perovskite crystal structure. The emissivity values of HE-1 and HE-2 are 0.78/0.66 and 0.82/0.83 in the near/mid-infrared band, respectively. These IR emissivity values are much higher than that of pure LaAlO 3 , which is attributed to enhanced impurity absorption, free carrier absorption and lattice vibration absorption. Moreover, after heating at 1500 °C for 10 h, HE-1 and HE-2 ceramics appear extremely slower emissivity decay rate (1.2–4.5 %), in comparison with fast decay rate (25.5–36.8 %) of pure LaAlO 3. This phenomenon can be attributed to the hysteresis diffusion effect of high-entropy ceramics, which can inhibit grain growth and emissivity decay. The novel ceramics have important application prospect in long-term energy-saving for high-temperature industry. [ABSTRACT FROM AUTHOR]