Impulsive Period Research Articles

Parametric seismic fragility model for elephant-foot buckling in unanchored steel storage tanks

The parametric seismic fragility model of elephant-foot buckling (EFB) in the tank wall of the unanchored storage tanks is introduced by utilizing the results of a parametric study of eighteen tank-soil configurations. The model can be used to rapidly assess the seismic vulnerability to EFB for a larger number of tanks. The parametric study involved a 1D cloud-based soil response analysis to relate the ground-motion intensity measure at the bedrock with that at the free surface, and a pushover analysis of the refined finite element model of the tank to assess the engineering demand parameter in terms of axial compressive stress in the tank wall and the critical value that triggers EFB. As a consequence, the parametric seismic fragility model can be applied to intensity measures at the bedrock, as it is demonstrated for the spectral acceleration at the tank’s impulsive period, Se,bedrock,EFB, and the peak ground acceleration, PGAbedrock,EFB. The input parameters of the introduced seismic fragility model are the harmonic average shear-wave velocity in the top 30 m of soil, Vs,30, the slenderness ratio of the tank, H/R, the ratio between radius and wall thickness of the tank, R/t, and the standard deviation of log values for the intensity measure causing EFB. The model reliably predicts the median intensity measure causing the onset of EFB in the investigated tank-soil configurations, especially when Se,bedrock,EFB is selected for the intensity measure. However, further investigation is required to enhance the accuracy of predicted intensity measures that trigger EFB by considering the dynamic impact between the base plate and the foundation during an earthquake and accounting for the complete soil-structure interaction effects.

Enhanced response of thermospheric cooling emission to negative pressure pulse

Nitric oxide (NO) emission via 5.3 µm wavelength plays dominant role in regulating the thermospheric temperature due to thermostat nature. The response of NO 5.3 mm emission to the negative pressure impulse during November 06–09, 2010 is studied by using Sounding of Atmosphere by Broadband Emission Radiometry (SABER) observations onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite and model simulations. The TIMED/SABER satellite observations demonstrate a significant enhancement in the high latitude region. The Open Geospace General Circulation Model (OpenGGCM), Weimer model simulations and Active Magnetosphere and Planetary Electrodynamics Response Experiment measurements exhibit intensification and equatorward expansion of the field-aligned-currents (FACs) post-negative pressure impulse period due to the expansion of the dayside magnetosphere. The enhanced FACs drive precipitation of low energy particle flux and Joule heating rate affecting whole magnetosphere–ionosphere–thermosphere system. Our study based on electric fields and conductivity derived from the EISCAT Tromsø\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\o }$$\\end{document} radar and TIEGCM simulation suggests that the enhanced Joule heating rate and the particle precipitations prompt the increase in NO cooling emission.

A rumor propagation model in multilingual environment with time and state dependent impulsive control

In this paper we are interested in the problem of modeling, analysis and control of rumor spreading on online social networks. As the diversity of languages and the difference of user nodes in the network, a heterogeneous rumor spreading model with two language spreaders is proposed, and the impulsive isolation control strategy is considered. Firstly, the model with periodic impulsive isolation control and time-delay recovery rate is discussed. Based on the stability theory of impulsive differential equations, some conditions regarding the impulsive period and control gains are given for the rumor asymptotically disappearance and persistent existence. Secondly, a new type of event-triggered impulsive isolation control method is developed to address the tradeoff between restraining rumor and minimizing the cost of control, and some conditions are given to make the rumor disappear asymptotically. Furthermore, an improved event-triggered mechanism is established based on the fixed-time stability theory, which provides the conditions for the rumor to disappear within a fixed-time. Finally, some numerical simulations and an actual example are given to verify the rationality of the model and the effectiveness of the control methods.

Stability Analysis of SIRS Model considering Pulse Vaccination and Elimination Disturbance

It is well known that many natural phenomena and human activities do exhibit impulsive effects in the fields of epidemiology. At the same time, compared with a single control strategy, it is obvious that the multiple control strategies are more beneficial to restrain the spread of infectious diseases. In this paper, we consider pulse vaccination and pulse elimination strategies at the same time and establish an SIRS epidemic model with standard incidence. Firstly, according to the stroboscopic mapping method of the discrete dynamical system, the disease-free T periodic solution of the model under the condition of pulse vaccination and pulse elimination is obtained. Secondly, the basic reproductive number R0 is defined, and the local asymptotic stability of the disease-free T periodic solution is proved by Floquet theory for R0<1. Finally, based on the impulsive differential inequality theory, the global asymptotic stability of the disease-free T periodic solution is given for R0<1, and the disease dies out eventually. The results show that in order to stop the disease epidemic, it is necessary to choose the appropriate vaccination rate and elimination rate and the appropriate impulsive period.

Stability Analysis of a Delayed Rumor Propagation Model with Nonlinear Incidence Incorporating Impulsive Vaccination.

The presence of information asymmetry can hinder the public's ability to make well-informed decisions, resulting in unwarranted suspicion and the widespread dissemination of rumors. Therefore, it is crucial to provide individuals with consistent and dependable scientific education. Regular popular science education is considered a periodic impulsive intervention to mitigate the impact of information asymmetry and promote a more informed and discerning public. Drawing on these findings, this paper proposes a susceptible-hesitant-infected-refuting-recovered (SHIDR) rumor-spreading model to explain the spread of rumors. The model incorporates elements such as time delay, nonlinear incidence, and refuting individuals. Firstly, by applying the comparison theorem of an impulsive differential equation, we calculate two thresholds for rumor propagation. Additionally, we analyze the conditions of global attractiveness of the rumor-free periodic solution. Furthermore, we consider the condition for the rumor's permanence. Finally, numerical simulations are conducted to validate the accuracy of our findings. The results suggest that increasing the proportion of impulsive vaccination, reducing the impulsive period, or prolonging the delay time can effectively suppress rumors.

Improved Adaptive Multipoint Optimal Minimum Entropy Deconvolution and Application on Bearing Fault Detection in Random Impulsive Noise Environments.

Random impulsive noise is a special kind of noise, which has strong impact features and random disturbances with large amplitude, short duration, and long intervals. This type of noise often displays nonGaussianity, while common background noise obeys Gaussian distribution. Hence, random impulsive noise greatly differs from common background noise, which renders many commonly used approaches in bearing fault diagnosis inapplicable. In this work, we explore the challenge of bearing fault detection in the presence of random impulsive noise. To deal with this issue, an improved adaptive multipoint optimal minimum entropy deconvolution (IAMOMED) is introduced. In this IAMOMED, an envelope autocorrelation function is used to automatically estimate the cyclic impulse period instead of setting an approximate period range. Moreover, the target vector in the original MOMED is rearranged to enhance its practical applicability. Finally, particle swarm optimization is employed to determine the optimal filter length for selection purposes. According to these improvements, IAMOMED is more suitable for detecting bearing fault features in the case of random impulsive noise when compared to the original MOMED. The contrast experiments demonstrate that the proposed IAMOMED technique is capable of effectively identifying fault characteristics from the vibration signal with strong random impulsive noise and, in addition, it can accurately diagnose the fault types. Thus, the proposed method provides an alternative fault detection tool for rotating machinery in the presence of random impulsive noise.

A risk‐targeted seismic performance assessment of elephant‐foot buckling in walls of unanchored steel storage tanks

AbstractUnanchored steel storage tanks are used in industrial plants to store oil and other petrochemical liquids. In a major earthquake, such tanks may sustain different types of damage, including elasto‐plastic buckling in the shape of an elephant's foot, which is the object of the research. The methodology introduced in this paper consists of cloud‐based 1D site response analysis (SRA) and pushover‐based seismic performance assessment of the tank wall using a 3D non‐linear model of the tank. The SRA, which considers the recorded ground motions on the rock outcrop and the sample of interval shear‐wave velocity profiles, is carried out to estimate spectral accelerations at the tank impulsive period. By adopting the code‐based model of hydrodynamic pressures, the seismic demand on the tank wall is then calculated by pushover analysis. The risk‐targeted decision model is used for safety verification. The proposed methodology is demonstrated through an example of a large liquid storage tank for which it is shown that the fragility function for peak ground acceleration at the rock outcrop is on the left side of the target fragility function, indicating that the tank cannot be considered safe from elephant‐foot buckling. The introduced assessment process is relatively simple if the cloud‐based SRA is automated. However, further experimental and numerical investigations are required to confirm the validity range of the pushover analysis for the seismic performance assessment of tanks.

Effect of freezing of gait and dopaminergic medication in the biomechanics of lower limbs in the gait of patients with Parkinson’s disease compared to neurologically healthy

IntroductionThis study aims to evaluate the effects of medication, and the freezing of gait (FoG) on the kinematic and kinetic parameters of gait in people with Parkinson’s disease (pwPD) compared to neurologically healthy. MethodsTwenty-two people with a clinical diagnosis of idiopathic PD in ON and OFF medication (11 FoG), and 18 healthy participants (control) were selected from two open data sets. All participants walked on the floor on a 10-meter-long walkway. The joint kinematic and ground reaction forces (GRF) variables of gait and the clinical characteristics were compared: (1) PD with FoG (pwFoG) and PD without FoG (pwoFoG) in the ON condition and control; (2) PD with FoG and PD without FoG in the OFF condition and control; (3) Group (PD with FoG and PD without FoG) and Medication. Results(1) FoG mainly affects distal joints, such as the ankle and knee; (2) PD ON showed changes in the range of motion of both distal and proximal joints, which may explain the increase in step length and gait speed expected with the use of L-Dopa; and (3) the medication showed improvements in the kinematic and kinetic parameters of the gait of people with pwFoG and pwoFoG equally; (4) pwPD showed a smaller second peak of the vertical component of the GRF than the control. ConclusionThe presence of FoG mainly affects distal joints, such as the ankle and knee. PD presents a lower application of GRF during the impulse period than healthy people, causing lower gait performances.

Squared envelope sparsification via blind deconvolution and its application to railway axle bearing diagnostics

A sparse squared envelope is crucial for efficient and accurate diagnosis of bearing faults. Blind deconvolution (BD) is a well-established sparse feature enhancement method for the diagnostics of rolling bearings. Traditional BD methods, such as minimum entropy deconvolution (MED), are susceptible to random transients, making it difficult to enhance fault features of rolling bearings subject to strong random shocks. Deconvolution methods that take the fault characteristic frequency (or fault impulse period) of interest as an algorithm input parameter, such as maximum second-order cyclostationarity blind deconvolution (CYCBD), can alleviate this deficiency. However, bearing fault features are difficult to be enhanced by these methods when the specified characteristic frequency deviates from the actual value greatly. To overcome these problems, the modified smoothness index (MSI) of the squared envelope is proposed as the objective function of the deconvolution method, and a new BD method is developed to achieve a sparse squared envelope for fault diagnosis of rolling bearings. Furthermore, the methodology is extended to the frequency domain, and another new BD method that utilizes the MSI of the squared envelope spectrum as the objective function is established to achieve a sparse squared envelope spectrum for bearing diagnostics. These two proposed BD methods are robust to random transients and do not require characteristic frequency or impulse period as an input parameter for feature enhancement. The performance of the two proposed BD methods is verified on experimental datasets from two different railway axle bearing test rigs and compared with the state-of-the-art deconvolution methods. The results show that the two proposed methods can effectively enhance repetitive transient features in noisy vibration signals and accurately diagnose different faults of railway axle bearings.

Location estimation of subsurface fluid-filled fractures: Cepstral predominant peak analysis and numerical study

In various subsurface resource development or fluid piping transportation problems, subsurface fluid-filled fractures often appear. Fracture location determination has always been critical in the related fields. Acoustic wave reflection at the junction and boundary in the pipeline can carry information about the property of the system. By using the accompanying acoustic wave information combined with the water hammer effect, the location of subsurface fractures can be estimated. A numerical fluid flow model for instantaneous shut-in is presented based on the water hammer effect. Fluid penetration effects, wellbore storage effect, and fluid inertial effect are considered. A method for determining the locations of subsurface fractures using cepstral predominant peak (CPP) is first proposed. By cepstral, we mean the inverse Fourier transform of the logarithm of the estimated signal spectrum. Also, the relationship between instantaneous shut-in pressure and cepstrum response is investigated in detail. To improve the robustness, CPP analysis based on Kaiser windowed cepstrum is used to identify the impulse period of fracture. Compared with the original cepstrum, Kaiser windowed cepstrum has the better performance for CPP analysis. The proposed flow model is impactful as it can provide pressure data with known fracture locations. Meanwhile, the data can be used to optimize and examine the performance of CPP analysis with Kaiser windowed cepstrum. A field experiment is conducted to validate the analysis about the acoustic wave in a pipeline system with fractures. By installing a high-frequency pressure monitoring device at the pump, the actual instantaneous shut-in pressure for an oil well is obtained. The experiment results show that the CPP analysis can obtain the fracture location efficiently and accurately, which can provide insights for engineering practices.

Multi-group hybrid impulsive flocking control of heterogenous multi-agent systems

This paper studies the flocking control problem of heterogenous multi-agent systems with multi-group tracking various virtual leaders. In particular, hybrid impulsive control protocol is designed based on the partially discrete agents’ information transmission, where full information exchange only occurs at each impulsive time instant. Meanwhile, braking and gyroscopic forces are implemented for the collision avoidance purpose. Conditions for multi-group formation are established in terms of coupling strength and the length of impulse period. The designed control protocols guarantee that the multi-agent systems are able to achieve asymptotic stability as well as collision-free motions. Numerical examples and computer simulations are provided to validate the theoretical results.

In-field dynamic response of instrumented wine tanks subjected to aftershock earthquakes

An experimental investigation of the dynamic behaviour of anchored flat-based wine storage tanks in a winery located in Marlborough, New Zealand is presented herein. Six wine storage tanks with different dimensions, capacities, and anchorage systems were instrumented with accelerometers for approximately six weeks following the 2016 Kaikōura earthquake, providing an opportunity to conduct a parametric study of their dynamic response when subjected to 37 aftershock earthquakes. The largest accelerations measured in the horizontal (X and Y) and vertical (Z) axes directions at the top of the six tanks occurred in conjunction with a Mw5.48 aftershock earthquake, with analysis indicating that the peak acceleration at the tank top occurred along the horizontal (Y) axis with a value of 0.545 g.Analysis of accelerations recorded at the top of the six tanks revealed that for low-intensity earthquake shaking the largest accelerations were measured at the top of the 40kL tank. A comparison of the tank instrumentation data indicated that the 175kL tank with a shear bolt anchorage system performed better than the nominally identical 175kL tank with a necked tension anchorage system, with the maximum lateral accelerations attained in the horizontal X and Y axes directions for the tank with the necked tension anchorage system being on average 1.59 times and 1.39 times the acceleration attained for the tank with the shear bolt anchorage system. Analysis of the results for the highest intensity earthquake shaking (Mw5.48) also indicated that the two tanks with installed energy dissipation systems sustained less acceleration when compared to tanks with a traditional anchorage system. Also, good agreement was observed between the values of the impulsive period attained from the analysis of the tank instrumentation data and from finite element (FE) modal analysis.

Maximum correntropy criterion-based blind deconvolution and its application for bearing fault detection

The distortion of signal caused by transmission path always brings great difficulties to feature extraction for bearing fault diagnosis. It is thus an important work to eliminate the influence of transmission path and recover impulsive features. A novel method called maximum correntropy criterion-based blind deconvolution (MCCBD) is presented in this paper and the strong analytical connection which holds for MOMEDA and MCCBD is revealed. Maximum correntropy criterion (MCC) is used as an objective function to reduce the influence of outliers and the coefficients of the optimal deconvolution filter can be obtained. Moreover, the proposed method adopts an autocorrentropy-based strategy to automatically evaluate the impulse period, hence it can enhance the fault impulses buried by noise without any prior knowledge. Finally, the superiority of MCCBD is exhibited by comparing with some existing methods on the simulated signal and two experimental datasets.

Period-assisted adaptive parameterized wavelet dictionary and its sparse representation for periodic transient features of rolling bearing faults

Accurate extraction of fault-induced periodic transient features from noise interference containing harmonics and large-amplitude random impulses is a key to fault detection of rolling bearings. Therefore, this paper proposes a sparse representation method based on a period-assisted adaptive parameterized wavelet dictionary to extract periodic transient features of rolling bearing faults. First, considering the influence of noise and vibration transmission paths on impulse response generated by bearing faults, an asymmetric bilateral exponential attenuation wavelet is constructed according to a vibration model of impulse response, which can be more flexible to match impulse features in vibration signals. Meanwhile, an adaptive correlation filtering method and a benchmark atom obtained by a standard K-SVD are utilized to determine optimal parameters of the constructed wavelet, which is less disturbed by noise and harmonics. On this basis, by introducing a priori knowledge of an impulse period, a method of constructing a period-assisted parameterized wavelet dictionary is proposed to get a dictionary that is suitable to characterize periodic transient features. Finally, a periodic transient signal is recovered using the constructed dictionary and the orthogonal matching pursuit (OMP) algorithm. Comparisons with the K-SVD, a sparse representation method based on a db8 wavelet dictionary, spectral correlation and spectral kurtosis demonstrate that the proposed method can more accurately extract periodic transient features in simulated and experimental vibration signals, which provides an effective analysis tool for rolling bearing fault detection.

Dynamic behaviour of a predator-prey system with impulsive control strategy

In this paper, a class of predator-prey system with Beddington-DeAngelis functional response and Allee effect is studied, where impulsive effects are also considered in the model. By using small parameters perturbation skills, comparison theorem and Floquet theory for the impulsive equations, the globally asymptotical stability of the prey-eradication periodic solution and the persistence for the system are obtained. Finally, some numerical examples and simulations are presented by Matlab software to support the theoretical results. The influence of impulsive perturbation intensity and impulsive period on the persistence and periodic solution of the system are discussed.

Near‐Fault Ground Motion Impacts on High‐Speed Rail Large‐Span Continuous Girder Bridge considering Pile‐Soil Interaction

This paper examines and discusses the dynamic response of a high‐speed train‐bridge‐soil‐pile foundation system to near‐fault earthquakes. A 72 + 120 + 72 m continuous girder bridge of a high‐speed railroad was selected as the model for calculation. Based on the p‐y model for simulating pile‐soil interaction, the moment‐curvature analysis program XTRACT is used to calculate the moment and curvature of bridge piers and pile foundation sections, and the finite element (FE) software is used to establish two nonlinear global bridge models under seismic effects in the high‐intensity zone, one considering pile‐soil interaction and one without considering pile‐soil interaction. The Ap/Vp parameter, the ratio of peak acceleration to peak velocity of transverse ground shaking, is used to reflect the impulse characteristics of earthquakes and the effect of the Ap/Vp parameter on the dynamic response of bridges to earthquakes was studied. The elastic‐plastic response of the bridge system was calculated under lateral and vertical near‐fault (NF) impulse/NF nonimpulse/far‐field (FF) ground motions (GMs). The study shows that the structural displacement increases, and the internal force decreases after considering the pile‐soil interaction. The results show that the bridge piers enter the elastoplastic phase under rare earthquakes. The NF ground shaking couples with the bridge into the elastoplastic phase with a more significant impulse period than the FF ground shaking intensifies the dynamic response of the bridge structure.

New stability criteria for linear impulsive systems with interval impulse-delay

The robust stability problem for linear time-delay systems with general linear delayed impulses is investigated. Different from the previous results, the impulse-delays are allowed to be larger than the impulse period. An auxiliary state variable is introduced to construct an augmented model of the impulsive system, under which the discrete dynamics introduced by impulse-delays can be highlighted. A novel piecewise Lyapunov functional is introduced to analyze the stability of the augmented model. This functional is continuous along the trajectories of the augmented model, and is not required to be positive-definite at non-impulse instants. LMI-based exponential stability conditions are derived, which depend on both the impulse-dwell-time and the impulse-delay-interval. Numerical examples show that the obtained stability criteria are able to handle the benefit/harmful impulse-delays.

Improving energy harvesting from impulsive excitations by a nonlinear tunable bistable energy harvester

This paper proposes a novel prototype of tunable bistable energy harvester (TBEH) coupled to a grounded and weakly damped linear primary structure. Based on buckling beam theory and generalized Hamiltonian principle, the equivalent mathematical model of the proposed TBEH system is presented and numerically simulated. A thorough sensitivity analysis concerning the buckled factor, the mass ratio, magnitude of impulse and the impulse period is studied to provide design insights for dynamic optimization of the TBEH system excited by varying impulsive excitations. The influences of a single impulse and repeated impulses on the vibration suppression and energy harvesting performance of TBEH system are investigated, respectively. Furthermore, the dynamics of the primary structure and TBEH and percentage of transient total energy in the TBEH are presented. The results show that maximizing measures of vibration energy absorption and harvesting can be optimized by tuning the sensitive parameters of the TBEH system. Compared with the pure cubic case, the tunable buckled TBEH shows remarkable advances in broadband vibration absorption and fast energy transfer. Finally, the confirmatory prototype experiment is conducted to validate the theoretical results. The measured experimental results are in good agreements with the theoretical analysis. The proposed TBEH with excellent energy capture and conversion is a potential alternative for powering miniature wireless sensor networks.

Analysis of a hybrid impulsive tumor-immune model with immunotherapy and chemotherapy

Abstract In this paper, a tumour-immune model with pulsed treatment of different frequency is proposed. The globally attractive conditions of the tumour-free periodic solution are presented in views of the comparison theorem for impulsive differential equations. Furthermore, the effect of period, dosage and times of drug delivery on the critical threshold is addressed by means of computer simulation, which indicates that there exists an optimal frequency of chemotherapeutic application. In addition, a tumour-immune model with fixed-time pulsed of immunotherapy and state feedback impulsive chemotherapy is given to keep the normal cells above and toxicity below the acceptable levels. Some numerical results are also provided to investigate the effect of the initial densities, predetermined threshold, drug dose and impulsive period on the dynamical behavior of hybrid impulsive system.

Complex Dynamics of Beddington–DeAngelis-Type Predator-Prey Model with Nonlinear Impulsive Control

According to resource limitation, a more realistic pest management is that the impulsive control actions should be adjusted according to the densities of both pest and natural enemy in the field, which result in nonlinear impulsive control. Therefore, we have proposed a Beddington–DeAngelis interference predator-prey model concerning integrated pest management with both density-dependent pest and natural enemy population. We find that the pest-eradication periodic solution is globally stable if the impulsive period is less than the critical value by Floquet theorem. The condition of permanent is established, and a stable positive periodic solution appears via a supercritical bifurcation by bifurcation theorem. Finally, in order to investigate the effects of those nonlinear control strategies on the successful pest control, the bifurcation diagrams showed that the model exists with very complex dynamics. Consequently, the resource limitation may result in pest outbreak in complex ways, which means that the pest control strategies should be carefully designed.