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Orthotropic steel decks (OSDs) are commonly used in the construction of bridges due to their load-bearing capabilities. However, they are prone to fatigue damage over time due to the cyclic loads from vehicles. Therefore, the early structural health monitoring of fatigue damage in OSDs is crucial for ensuring bridge safety. Moreover, Lamb waves, as elastic waves propagating in OSD plate-like structures, are characterized by their long propagation distances and minimal attenuation. This paper introduces a method of emitting high-energy ultrasonic waves onto the OSD surface to capture the nonlinear Lamb waves formed, thereby calculating the nonlinear parameters. These parameters are then correlated with the fatigue damage endured, forming a damage index (DI) for monitoring the fatigue life of OSDs. Experimental results indicate that as fatigue damage increases, the nonlinear parameters exhibit a significant initial increase followed by a decrease. The behavior is distinct from the characteristic parameters of linear ultrasound (velocity and energy), which also exhibit changes but to a relatively smaller extent. The proposed DI and fatigue life based on nonlinear parameters can be fitted with a Gaussian curve, with the R-squared value of the fitting curve being close to 1. Additionally, this paper discusses the influence of rib welds within the OSDs on the DI, whereby as fatigue damage increases, it enlarges the value of the nonlinear parameters without altering their trend. The proposed method provides a more effective approach for monitoring early fatigue damage in OSDs. [ABSTRACT FROM AUTHOR]

The stability of aircraft during taxiing is an important issue in the development of landing gear and airworthiness certification. Incidents and abnormal problems consistently arise due to landing gear shimmy. The integration of a model involving tricycle landing gear and aircraft structure is a major advancement in addressing shimmy oscillations. A formulated nonlinear mathematical modeling approach integrates airframe motions with landing gear modes, which provides deep insights into their coupling effect. It effectively determines the critical speed region and types of shimmy oscillations that can occur. An increase in landing gear shimmy intensifies lateral forces on landing gear components, which affects the yaw motion of the aircraft. The optimization of aircraft mass, the critical value of torsional damping, and their influence on directional stability are investigated. This work is useful in the conceptual design of landing gears and in avoiding the potential risks associated with shimmy oscillations to extend the lifespan of landing gears. [ABSTRACT FROM AUTHOR]

Orthotropic steel decks (OSDs) are commonly used in the construction of bridges due to their load-bearing capabilities. However, they are prone to fatigue damage over time due to the cyclic loads from vehicles. Therefore, the early structural health monitoring of fatigue damage in OSDs is crucial for ensuring bridge safety. Moreover, Lamb waves, as elastic waves propagating in OSD plate-like structures, are characterized by their long propagation distances and minimal attenuation. This paper introduces a method of emitting high-energy ultrasonic waves onto the OSD surface to capture the nonlinear Lamb waves formed, thereby calculating the nonlinear parameters. These parameters are then correlated with the fatigue damage endured, forming a damage index (DI) for monitoring the fatigue life of OSDs. Experimental results indicate that as fatigue damage increases, the nonlinear parameters exhibit a significant initial increase followed by a decrease. The behavior is distinct from the characteristic parameters of linear ultrasound (velocity and energy), which also exhibit changes but to a relatively smaller extent. The proposed DI and fatigue life based on nonlinear parameters can be fitted with a Gaussian curve, with the R-squared value of the fitting curve being close to 1. Additionally, this paper discusses the influence of rib welds within the OSDs on the DI, whereby as fatigue damage increases, it enlarges the value of the nonlinear parameters without altering their trend. The proposed method provides a more effective approach for monitoring early fatigue damage in OSDs.

The assessment of motor function is critical to the rehabilitation of stroke patients. However, commonly used evaluation methods are based on behavior scoring, which lacks neurological indicators that directly reflect the motor function of the brain. The objective of this study was to investigate whether resting-state EEG indicators could improve stroke rehabilitation evaluation. We recruited 68 participants and recorded their resting-state EEG data. According to Brunnstrom stage, the participants were divided into three groups: severe, moderate, and mild. Ten quantitative electroencephalographic (QEEG) and five non-linear parameters of resting-state EEG were calculated for further analysis. Statistical tests were performed, and the genetic algorithm-support vector machine was used to select the best feature combination for classification. We found the QEEG parameters show significant differences in Delta, Alpha1, Alpha2, DAR, and DTABR (P < 0.05) among the three groups. Regarding nonlinear parameters, ApEn, SampEn, Lz, and C0 showed significant differences (P < 0.05). The optimal feature classification combination accuracy rate reached 85.3%. Our research shows that resting-state EEG indicators could be used for stroke rehabilitation evaluation. [ABSTRACT FROM AUTHOR]

In nonlinear ultrasonic damage detection, the appropriate Lamb wave mode to accurately characterise the nonlinearity attributed to the material damage should be selected important. However, an effective mode is more difficult to select practically as impacted by the dispersion and multi-mode characteristic of the Lamb wave. In this study, based on the dispersion curve of Lamb waves, the modes meeting the second harmonics and third harmonics phase velocity matching were given, and the nonlinear cumulative effects exerted by different modes on fatigue cracks were compared. In addition, an investigation was conducted on the amplitude change of the second and third harmonics signal of the identical fatigue damage. The results show that the harmonic amplitude decreases with the increase of the fatigue crack length. The third harmonics under the two modes are more sensitive to fatigue damage than the second harmonics. Moreover, the amplitude of the third harmonic excited by S1 mode exceeds that of the other mode. As the fatigue crack length increases, the relative second- and third-order nonlinear coefficients generated by S1 mode have approximately the same trend, first increasing and then decreasing. The results reveal that the third harmonic under S1 mode could more effectively characterise fatigue damage. [ABSTRACT FROM AUTHOR]

In this paper, the generalized nonautonomous Hirota equation was investigated with the help of symbolic computation. Using Darboux transformation method three soliton and four soliton solutions were developed based on Lax pair construction. The corresponding figures are plotted to show the properties of the constructed soliton solutions. By manipulating autonomous and nonautonomous profile, various soliton systems are investigated. These solitons systems have potential applications in the design of soliton compressor, soliton amplification, and high-speed optical devices in ultra large data transmission systems. In future experiments, the findings of this study are expected to be demonstrated. [ABSTRACT FROM AUTHOR]

Abstract Whale optimization algorithm, as a relatively novel swarm-based intelligence optimization algorithm, has been extensively utilized in numerous scientific and engineering fields. The intent of this work was to devise a modified WOA based on multi-strategy, named MSWOA, to address somewhat deficiencies of the original WOA, such as converging slowly, stagnating at local minima and poor stability. First, a tent map function is adopted to optimize the distribution of the initial population in problem domain. Second, new iteration-based update strategies of convergence factor and inertia weight are constructed to regulate the balance between global and local search capabilities and improve the optimization ability. Additionally, an optimal feedback strategy is presented in the search for prey stage to enhance the global search ability. Numerical experimental results based on 24 test benchmark functions reveal that the proposed MSWOA significantly improves the standard WOA in terms of solution accuracy and convergence speed, and outperforms the comparison algorithms. Furthermore, the results show that the inertia weight strategy has the greatest effect on the performance of basic WOA performance, followed by the convergence factor, and then the optimal feedback strategy.

Lithium primary batteries having high power and energy densities have irreversible energy characteristics, unlike lithium secondary batteries. Therefore, their application in experiments is limited, and capacity information is difficult to derive. The capacity information serves as the initial value in the ampere-hour counting method to estimate the battery state-of-charge (SOC). Therefore, in order to estimate the SOC of a lithium primary battery, it is necessary to predict the capacity information. In this paper, we propose a method to predict the capacity of lithium primary batteries using machine learning techniques. To predict capacity, pre-measurement factors (PMFs) for lithium primary batteries are selected and correlation with capacity is analyzed. PMFs that can be measured before the lithium primary battery operates include AC impedance and open-circuit voltage, weight, and resistance, Resistances were extracted using the closed-circuit voltage experiment. These PMFs derive a correlation coefficient through correlation analysis of the capacity of lithium primary battery. However, the correlation coefficient between individual PMFs and the capacity of lithium primary battery is lower than 0.5. That is, the relationship between PMFs and capacity is not linear. Therefore, this study implements a multilayer perceptron (MLP) model that uses multiple nonlinear parameters. A total of 300 lithium primary battery data is used for model design, and the model is verified by classifying the data into training data and test data. The capacity information predicted through the MLP model was used for the SOC estimation, and the SOC estimation accuracy was analyzed by comparing it with the SOC measurement value.

Parameter estimation is vitalfor modeling and control of fuel cell systems. However, the nonlinear parameterization is an intrinsic characteristic in the fuel cell models such that classical parameter estimation schemes developed for linearly parameterized systems cannot be applied. In this article, an alternative framework of adaptive parameter estimation is designed to address the real-time parameter estimation for fuel cell systems. The parameter estimation can be divided into two cascaded components. First, the dynamics with the unknown parameters are estimated by a new unknown system dynamics estimator (USDE). Inspired by an invariant manifold, this USDE is designed by applying simple filter operations such that the information of the state derivative is not required. Second, an adaptive law driven by the function approximation error is proposed for recovering unknown model parameters. Exponential convergence of the estimated parameters to the true values can be proved under the monotonicity condition. Finally, experimental results on a practical proton exchange membrane fuel cell system are given to verify the effectiveness of the proposed schemes. [ABSTRACT FROM AUTHOR]

As an efficient meta-heuristic algorithm, the whale optimization algorithm (WOA) has been extensively applied to practical problems. However, WOA still has the drawbacks of converging slowly, and jumping out from extreme points especially for large scale optimization problems. To overcome these defects, a modified whale optimization algorithm integrated with a crisscross optimization algorithm (MWOA-CS) is proposed. In MWOA-CS, each dimension of the optimization problem updates its position by randomly performing improved WOA or crisscross optimization algorithm during the entire iterative process. The improved WOA adopts the new nonlinear convergence factor and nonlinear inertia weight to tune the ability of exploitation and exploration. To analyze the performance of MWOA-CS, a series of numerical experiments were performed on 30 test benchmark functions with dimension ranging from 300 to 1000. The experimental results revealed that the presented MWOA-CS provided better convergence speed and accuracy, and meanwhile, displayed a significantly more effective and robust performance than the original WOA and other state of the art meta-heuristic algorithms for solving large scale global optimization problems. [ABSTRACT FROM AUTHOR]

The aim was to examine the variation of linear and nonlinear proprieties of the behavior in participants with different levels of swimming expertise among the four swim strokes. Seventy-five swimmers were split into three groups (highly qualified experts, experts and nonexperts) and performed a maximal 25m trial for each of the four competitive swim strokes. A speed-meter cable was attached to the swimmer's hip to measure hip speed; from which speed fluctuation (dv), approximate entropy (ApEn) and fractal dimension (D) variables were derived. Although simple main effects of expertise and swim stroke were obtained for dv and D, no significant interaction of expertise and stroke were found except in ApEn. The ApEn and D were prone to decrease with increasing expertise. As a conclusion, swimming does exhibit nonlinear properties but its magnitude differs according to the swim stroke and level of expertise of the performer. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Guangxi Normal University - Natural Science Edition is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • A spray pyrolysis technique was used to prepare different CdO:Al films. • EDAX, XRD, SEM, and XPS were used to determine the elemental and structural analysis. • Nonlinear parameters and optical constants were calculated and discussed. • A linear four-point probe was employed to measure the resistance of the sheet. • Applying figure of merit qualifies to analyze CdO:Al performance. In the results of this research, thin films of CdO-Al were produced using the spray pyrolysis (SP) technique. The primary aim was to explore how varying concentrations of aluminum (Al) influence the physical properties of the films. The X-ray diffraction (XRD) analysis confirmed the presence of a cubic crystal structure in the pure CdO films. Additionally, it revealed that the introduction of increased Al doping led to lattice shrinkage and a reduction in lattice parameters. Elevated levels of aluminum (Al) content were correlated with a decrease in crystallite size and an augmentation in lattice strain, as indicated by both scanning electron microscopy (SEM) and X-ray diffraction (XRD) data. Additionally, an X-ray photoelectron spectroscopy (XPS) examination revealed the presence of Al3+ ions within the films. The optical energy gap of CdO-Al films exhibited a slight increase, reaching up to 3% aluminum doping. The analysis of the refractive index dispersion and non-linear refractive index revealed a decreasing trend up to 3% aluminum content, with subsequent fluctuations at higher concentrations. The measurements of sheet resistance demonstrated a noticeable decrease with an increase in aluminum content, specifically up to 3%. [ABSTRACT FROM AUTHOR]

In this study, networks of interconnected heterogeneous micro-grids are studied. The transient dynamics is modelled as an averaging process whereby micro-grids are assimilated to dynamic agents in a network. An analysis of the convergence of the consensus dynamics is carried out under different assumptions on the damping and inertia parameters and the topology of the network. This study provides an insight into the relation between the network topology and the system's response. An analysis of the ways in which the heterogeneous inertial parameters affect the transient response of the network is also implemented. Additionally, the conditions that guarantee stability are identified when the system is under the influence of uncertain non-linear parameters. Finally, simulations are carried out based on a model calibrated on an existing network in the UK under parameter uncertainties.

Aiming at solving problems such as non-linear, time-varying parameters, and weak digital computing capability in the underground drainage system, the monitoring system is built based on a digital signal processor (DSP). Adopting DSP28335 as its control core, the hardware circuit and software program are designed in this monitoring system. The single-neuron fuzzy proportional, integration, and differential (PID) control algorithm with feedforward proportional and differential compensation is proposed in this study. The simulation results are compared and analysed with a traditional PID algorithm, fuzzy PID algorithm, and single-neuron fuzzy PID algorithm with feedforward in Matlab/Simulink, and the experimental platform is built to verify the application effect of three control algorithms. The simulation and experiment results show that the single-neuron fuzzy PID algorithm with feedforward has significant advantages such as shorter adjustment time, good adaptivity, and strong anti-interference ability, which could effectively improve the work efficiency of an underground mine drainage monitoring system.

Aiming at solving problems such as non-linear, time-varying parameters, and weak digital computing capability in the underground drainage system, the monitoring system is built based on a digital signal processor (DSP). Adopting DSP28335 as its control core, the hardware circuit and software program are designed in this monitoring system. The single-neuron fuzzy proportional, integration, and differential (PID) control algorithm with feedforward proportional and differential compensation is proposed in this study. The simulation results are compared and analysed with a traditional PID algorithm, fuzzy PID algorithm, and single-neuron fuzzy PID algorithm with feedforward in Matlab/Simulink, and the experimental platform is built to verify the application effect of three control algorithms. The simulation and experiment results show that the single-neuron fuzzy PID algorithm with feedforward has significant advantages such as shorter adjustment time, good adaptivity, and strong anti-interference ability, which could effectively improve the work efficiency of an underground mine drainage monitoring system. [ABSTRACT FROM AUTHOR]

The wave transformation over slope topography is widely studied, but most of studies are for common coastal slopes. This paper presents an experimental study of 2-D regular and irregular wave transformations on a simplified coral reef with a steep slope of 1:5 and a horizontal reef flat, focusing on the characteristics of the waves that break on the reef flat. The analyzed results show that the estimates of the wave breaking made by using the well-known previous formulae do not agree completely with the experimental results. When the waves break on a reef flat, the relative breaking wave height (H/d)b is related to the incident deep-water wave steepness and the relative water depth db/L0. Hence, a new criterion for breaking waves on a reef flat is proposed. Furthermore, in view of the fact that the local Ursell number is commonly used to parameterize the wave nonlinearity, the relationships among the skewness, the asymmetry, and the local Ursell number are also presented. Experimental data confirm that when the Ursell number is greater than 30, the absolute values of the skewness and the asymmetry on a reef flat are greater than those on a steep slope. [ABSTRACT FROM AUTHOR]

The optical properties of CdS0.9Mn0.1 thin film with different thicknesses (d = 300, 450, 600, 750, 900 and 1000 nm) were explored. The Swanepoel method was employed to calculate the thickness of the studied films. Analyses of the absorption spectra indicated the existence of allowed indirect and direct transition mechanism in the CdS0.9Mn0.1 thin films. Both the absorption coefficient and optical band gap decreased while Urbach energy increased as the film thickness increased. The Wimple–DiDomenico single oscillator model was used to describe the dispersion of the refractive index. The film thickness dependence of the dispersion parameters was studied. The optical dielectric constants, optical conductivity, electrical susceptibility, and non-liner optical parameters such as the refractive index, first-order susceptibility ( χ (1) ) and third-order susceptibility ( χ (3) ) were determined. The present results show that the film thickness is an important factor which affected the optical parameters. [ABSTRACT FROM AUTHOR]

• Nonlinear governing equations of a 5-ply graphene reinforced laminated composite plate are built. • The effects of nonlinear terms on dynamical behavior of the graphene laminated plate is investigated. • Both the cases of stronger and weaker nonlinear characteristic are compared and verified. • The influence mechanism of the nonlinear characteristic on dynamics of the plate is discussed. This research is focused on the effects of nonlinear terms on the dynamical behavior of graphene reinforced laminated composite plates. Firstly, the governing equations of the graphene reinforced composite thin plate subjected to transverse excitations are derived by using the Hamilton's principle and the von Karman deformation theory. Then numerical method is applied to investigate the nonlinear behaviors of graphene reinforced composite plates. Bifurcation diagram, waveform and phase portrait are demonstrated to analyze the nonlinear dynamics of the graphene reinforced laminated composite plates. Furthermore, the effects of nonlinear terms on the dynamical behavior are discussed in detail, where both the stronger and weaker nonlinear characteristics of lower modes of the plate are presented. Moreover, some interesting phenomena are obtained in numerical simulation. [ABSTRACT FROM AUTHOR]

Objective: The present study aimed to analyze the influence of smoking on heart autonomic control in elderly adults who did and did not smoke. Methods: In a population-based study, all community-dwelling elderly adults (≥60 years old) from Aiquara, Bahia, Brazil, were invited to participate in the study. Two-hundred-thirty-two (232) elderly adults provided information about their smoking habits and underwent 5-min recordings of successive RR intervals. Analysis of the variability of the RR intervals was performed in time and frequency domains and with nonlinear methods. The HAC parameters were adjusted for the following potential confounders: age, sex, diabetes, beta-blocker use, cardiovascular disease, body mass index and physical activity level. After exclusions, 210 elderly adults were divided into 2 groups, nonsmokers or those who stopped smoking (NSMOK [n=190]) and current smokers (SMOK [n=20]). Owing to the absence of a normal distribution, the Mann-Whitney test was used for group comparisons. Results: For unadjusted HAC parameters, a significant difference was observed (p

In this work, alizarin red S (ARS) powder is deposited into thin films using thermal evaporation technique. Subsequently, the as-deposited films are annealed. The structural properties of ARS powder and films in the as-deposited as well as annealed conditions are investigated by the Fourier transform infrared spectroscopy and X-ray diffraction. The ARS powder shows a polycrystalline nature with monoclinic structure, while the films have revealed nanocrystallites distributed in an amorphous matrix. The thermal stability of ARS films up to 398 K is confirmed via employing differential scanning calorimeter. Further, the annealing process results in an increment of both the average crystallite size and the dislocation density and reduced the microstrain. Regarding optical studies, the direct transitions in ARS films are existed with an onset and optical energy band gaps equal to 1.84 and 2.93 eV, respectively, and upon annealing, these values have increased to 1.79 and 2.98 eV, respectively. Finally, the nonlinear refractive index and the third-order nonlinear optical susceptibility are decreased upon annealing process. [ABSTRACT FROM AUTHOR]

A balanced armature receiver is a multi-physics product in which there is a coupling between the electromagnetic and mechanical domains. To come up with a more accurate analysis method, the nonlinear parameters are considered as functions of current and displacement based on the finite-element method. The current and displacement are solved using the voltage equation through the numerical iteration method. Simulation results are verified through experiments. [ABSTRACT FROM AUTHOR]

Here we report on a variety of traditional statistic and spectral parameters, and nonlinear parameters of heart rate variability (HRV) of 23 young females (19-24 yean) during 4 phases (the early and bte follicular phases, the ovulation, and the luteal phase) of the menstrual cycle (MC), in spring and autumn seasons. We found 1hat in the ovulation phase of 1he MC, unlike to other phases, most of parameters of HRV have significantly changed. In springtime, these changes were signifiantly accentuated in comparison with autumn. AD HRV parameters during ovulation shilled in the direction of decrease of the parasympathetic nervous system activity with reciprocal increase of the hormone-hypothalamic level of cardiovascular regulation and inference of the sympathetic nervous system. Additionally, we found that heart rate during 1he ovulation phase was controlled by a lesser number of regulating sensory inputs (2 in comparison with 3 characteristic of other phases of the MC).We discuss potential usability of this fmding in respect with mobile medicine applications to strengthen awareness of a woman about forthcoming ovulation that would help planning their physical and behavionl activities.

The purpose of this study was to compare the postnatal evolution of spectral-amplitude and nonlinear parameters of surface electromyogram (sEMG) in the full-term and preterm infants with regard to their biological and calendar age. In full-term infants, all sEMG parameters (dimension, entropy, mean frequency, and amplitude) are increased by 10-30% two weeks after birth. On the contrary, sEMG parameters in preterm infants were constant for six weeks after birth. This finding indicates that both postnatal and antenatal periods are important for the development of the motor system of infants. Therefore, the adaptation of the motor system to extrauterine conditions consists of two stages. The authors suppose that gravity can be a driving factor of these sEMG metamorphoses. [ABSTRACT FROM AUTHOR]

In the present work, the linear and nonlinear resonance experiments are performed on composite laminate beam with cyclic loading damage. The effect of different cyclic loading damage on the linear and nonlinear resonance response is analyzed. The nonlinear resonance studies the amplitude dependence of different modes. The frequency and the loss factor as function of the amplitude are determined for each cyclic loading damage. For the linear resonance, the specimens are tested at low amplitude excitation. The frequency and loss factor are evaluated for each cyclic damage. The nonlinear parameters are quantified as function of the damage. The linear parameters are compared with the nonlinear parameters. [ABSTRACT FROM AUTHOR]

Copyright of Financial & Credit Activity: Problems of Theory & Practice is the property of University of Banking of the National Bank of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Nano- & Electronic Physics is the property of Sumy State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of the present work is to study the vibration behavior of sandwich composites with shear damages on the foams. The effect of the densities of damage on the linear and nonlinear vibration parameters is studied. The sandwich materials used in this study is constructed with glass fiber laminates as skins and with PVC closed-cell foams with density 60 and 100 kg m−3 as core. After a serie of vibration tests, the change of natural frequencies and modal damping due to the damage and the foam densities. For an intact specimen, the resonance frequency was constant when we increase the excitation amplitude. For damaged specimens, the resonance frequencies decrease and the loss factors increase proportionally with the increasing excitation amplitude. The nonlinear parameters corresponding to the elastic modulus and damping were determined for each frequency modes and each damage and foam densities. The results showed that nonlinear dissipative parameters were more sensitive to damage than linear elastic and dissipative parameters. [ABSTRACT FROM AUTHOR]

To explore a new evaluation method for spontaneous combustion tendency of different areas in sulfide ore heap, ore samples from a pyrite mine in China were taken as experimental materials, and the temperature variations of the measuring points of simulated ore heap were measured. Combined with wavelet transform and nonlinear parameters extraction, a new method for spontaneous combustion tendency of different areas in sulfide ore heap based on nonlinear parameters was proposed and its reliability was verified by field test. The results indicate that temperature field evolution of the simulated ore heap presents significant spatial difference during self-heating process. Area with the maximum increasing extent of temperature in sulfide ore heap changes notably with the proceeding of self-heating reaction. Self-heating of sulfide ore heap is a chaotic evolution process, which means that it is feasible to evaluate spontaneous combustion tendency of different areas by nonlinear analysis method. There is a relatively strong correlation between the maximum Lyapunov exponent and spontaneous combustion tendency with the correlation coefficient of 0.9792. Furthermore, the sort of the maximum Lyapunov exponent is consistent with that of spontaneous combustion tendency. Therefore, spontaneous combustion tendency of different areas in sulfide ore heap can be evaluated by means of the maximum Lyapunov exponent method. [ABSTRACT FROM AUTHOR]

For the identification of a class of nonlinear multi‐input multi‐output (MIMO) Hammerstein systems with different types of coefficients: a matrix coefficient and scalar coefficients, it is difficult to parameterise such Hammerstein systems into an identification model to which the standard identification method can be easily applied to implement parameter estimation. By the matrix transformation and the over‐parametrisation idea, this study transforms an MIMO Hammerstein system with different types of coefficients into an over‐parametrisation regression identification model, and points out the aroused large computation problem. To overcome the large computational load of the over‐parametrisation method, by the matrix transformation and the hierarchical identification principle, this study recasts the MIMO Hammerstein system into two models, each of which is expressed as a regression form in the parameters of the nonlinear part or in the parameters of the linear part. Then a hierarchical extended stochastic gradient algorithm is presented to alternatively estimate the parameters of the nonlinear part and the parameters of the linear part. The simulation results indicate that the proposed algorithm can effectively identify the nonlinear MIMO Hammerstein system. [ABSTRACT FROM AUTHOR]

Aiming towards a better understanding of the structural response presented by multi-perforated clay brick masonry, this paper presents the results of an experimental program focused on characterizing the behavior of its constituent materials and interfaces, and on providing numerical strategies to appropriately reproduce that behavior. Different displacement controlled test set-ups were carried out in the laboratory for this purpose, giving special attention to characterizing the shear response at horizontal unit-mortar interface in order to point out the influence that mortar spikes penetrating into the perforated bricks cavities can exert. According to its detailed consideration of materials and interfaces, the detailed micro-modeling numerical approach was selected for this study. The numerical strategies proposed have led to a satisfactory reproduction of the shear triplet tests and diagonal compression tests that were performed, showing that the complex structural response of multi-perforated clay brick masonry can be appropriately reproduced from experimental evidence. [ABSTRACT FROM AUTHOR]

Lithium primary batteries having high power and energy densities have irreversible energy characteristics, unlike lithium secondary batteries. Therefore, their application in experiments is limited, and capacity information is difficult to derive. The capacity information serves as the initial value in the ampere-hour counting method to estimate the battery state-of-charge (SOC). Therefore, in order to estimate the SOC of a lithium primary battery, it is necessary to predict the capacity information. In this paper, we propose a method to predict the capacity of lithium primary batteries using machine learning techniques. To predict capacity, pre-measurement factors (PMFs) for lithium primary batteries are selected and correlation with capacity is analyzed. PMFs that can be measured before the lithium primary battery operates include AC impedance and open-circuit voltage, weight, and resistance, Resistances were extracted using the closed-circuit voltage experiment. These PMFs derive a correlation coefficient through correlation analysis of the capacity of lithium primary battery. However, the correlation coefficient between individual PMFs and the capacity of lithium primary battery is lower than 0.5. That is, the relationship between PMFs and capacity is not linear. Therefore, this study implements a multilayer perceptron (MLP) model that uses multiple nonlinear parameters. A total of 300 lithium primary battery data is used for model design, and the model is verified by classifying the data into training data and test data. The capacity information predicted through the MLP model was used for the SOC estimation, and the SOC estimation accuracy was analyzed by comparing it with the SOC measurement value. [ABSTRACT FROM AUTHOR]

To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 °C, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages: incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0 °C/min, 2.0 °C/min and 4.2 °C/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage. [ABSTRACT FROM AUTHOR]