Mode Switching Behavior Research Articles

Protocol-based SMC for singularly perturbed systems with switching parameters and deception attacks

This research paper investigates a protocol-based sliding mode control (SMC) approach for singularly perturbed systems with switching parameters and random occurring deception attacks. The mode switching behavior of the original system is regulated using a semi-Markov process, and a novel and more efficient mode monitoring method is proposed, distinct from the conventional hidden Markov model. Furthermore, to reduce the triggering rate while maintaining control performance, a probability-based event triggering protocol is introduced. By employing the proposed scheme along with Lyapunov theory, sufficient criteria for parameter correlation are established to ensure asymptotic stability. The designed sliding mode control incorporates a convergence factor to enhance the control performance. Finally, the feasibility and practicality of the proposed control strategy are verified through simulations using two practical models.

The Study of Mode-switching Behavior of PSR J0614+2229 Using the Parkes Ultra–wide-bandwidth Receiver Observations

In this paper we present a detailed single-pulse and polarization study of PSR J0614+2229 based on the archived data observed on 2019 August 15 (MJD 58710) and 2019 September 12 (MJD 58738) using the ultra−wide-bandwidth low-frequency receiver on the Parkes radio telescope. The single-pulse sequences show that this pulsar switches between two emission states, in which the emission of state A occurs earlier than that of state B in pulse longitude. We found that the variation in relative brightness between the two states varies temporally and both states follow a simple power law very well. Based on the phase-aligned multifrequency profiles, we found that there is a significant difference in the distributions of spectral index across the emission regions of the two states. Furthermore, we obtained the emission height evolution for the two emission states and found that, at a fixed frequency, the emission height of state A is higher than that of state B. What is even more interesting is that the emission heights of both states A and B do not change with frequency. Our results suggest that the mode switching of this pulsar is possibly caused by changes in the emission heights that alter the distributions of spectral index across the emission regions of states A and B, resulting in frequency-dependent behaviors, i.e., intensity and pulse width.

Neural Network-Based Sliding Mode Control for Semi-Markov Jumping Systems With Singular Perturbation.

The primary focus of this article centers around the application of sliding mode control (SMC) to semi-Markov jumping systems, incorporating a dynamic event-triggered protocol (ETP) and singular perturbation. The underlying semi-Markov singularly perturbed systems (SMSPSs) exhibit mode switching behavior governed by a semi-Markov process, wherein the variation of this process is regulated by a deterministic switching signal. To simultaneously reduce the triggering rate and uphold the system performance, a novel parameter-based dynamic ETP is established. This protocol incorporates weight estimation of a radial basis function neural network (RBFNN) and introduces two internal dynamic variables. Following the Lyapunov's theory, sufficient criteria are established for ensuring the mean-square exponential stability of the resulting system. Additionally, an SMC scheme based on the convergence factor is designed to fulfill reachability conditions. Finally, two examples are carried out to validate the solvability and applicability of the attained control methodology.

Mode switching in organisms for solving explore-versus-exploit problems

Trade-offs between producing costly movements for gathering information (‘explore’) and using previously acquired information to achieve a goal (‘exploit’) arise in a wide variety of problems, including foraging, reinforcement learning and sensorimotor control. Determining the optimal balance between exploration and exploitation is computationally intractable, necessitating heuristic solutions. Here we show that the electric fish Eigenmannia virescens uses a salience-dependent mode-switching strategy to solve the explore–exploit conflict during a refuge-tracking task in which the same category of movement (fore-aft swimming) is used for both gathering information and achieving task goals. The fish produced distinctive non-Gaussian distributions of movement velocities characterized by sharp peaks for slower, task-oriented ‘exploit’ movements and broad shoulders for faster ‘explore’ movements. The measures of non-normality increased with increased sensory salience, corresponding to a decrease in the prevalence of fast explore movements. We found the same sensory salience-dependent mode-switching behaviour across ten phylogenetically diverse organisms, from amoebae to humans, performing tasks such as postural balance and target tracking. We propose a state-uncertainty-based mode-switching heuristic that reproduces the distinctive velocity distribution, rationalizes modulation by sensory salience and outperforms the classic persistent excitation approach while using less energy. This mode-switching heuristic provides insights into purposeful exploratory behaviours in organisms, as well as a framework for more efficient state estimation and control of robots.

Detecting criticality in complex univariate time-series: A case study of the U.S. housing market crisis and other markets

The indices of asset markets are a key measure of an asset’s value and how this varies over time. However, these indices are known to switch abruptly between qualitatively different behavioural epochs underscoring the complexity of collective decision-making in large, interacting populations of economic agents. A central question in the study of index dynamics is how to represent these transitions in a way that allows for both equilibrium and non-equilibrium behaviour in a dynamical systems framework. With this in mind, we sought to detect non-equilibrium transitions between stable equilibria in housing market data across thirteen OECD countries from 1975 through to 2019. We are able to precisely locate transitions using the quadrant scan method that has been used in earlier studies to detect critical points in other dynamical systems. We then use stochastic Catastrophe Theory to reconstruct the multi-modal distributions near the U.S. housing crisis point and show mode-switching behaviour of markets transitioning from one equilibrium to another. Our results are in contrast to other recent findings for the U.S. market that were unable to find a critical point near the 2007 crisis.

Piezoelectric Lateral-Extensional Mode Resonators With Reconfigurable Electrode and Resonance Mode-Switching Behavior Enabled by a VO₂ Thin-Film.

This article presents the first two-port lateral-extensional mode zinc oxide (ZnO) piezoelectric resonator with a reconfigurable bottom electrode that is enabled by embedding a vanadium dioxide (VO2) thin film. The insulator-to-metal phase transition of VO2 is triggered by substrate heating that translates to abrupt changes in electric field patterns and piezoelectrically transduced modal vibrations, thus allowing mode-switching of piezoelectric resonators at specific frequencies. Finite element method (FEM) analysis was used to model the broadband frequency response, while frequency characteristics of the corresponding two-port resonator were measured over a temperature range between 20 °C and 95 °C with a specific focus on two resonances at 88 and 148 MHz. By leveraging the hysteretic behavior of VO2 thin film during a heating/cooling cycle, a change in both the capacitive feedthrough and resonance signal levels was observed, due to the abrupt change in the conductivity of VO2 during its phase transition. The unique switch- ON behavior of the resonance at 88 MHz starts at 70 °C during the heating cycle, while the switch- OFF transition begins at 60 °C during the cooling cycle. On the other hand, when the temperature is increased from 20 °C to 60 °C, a decrease in the insertion loss and resonance frequency of 12 dB and 0.28 MHz, respectively, were observed for the resonance at 148 MHz. Meanwhile, a resonance frequency increase of 0.42 MHz was observed during a temperature increase from 60 °C to 95 °C, which can be ascribed to VO2 phase transition from monoclinic to rutile phase. The hysteresis loops for insertion loss and resonance frequency indicate a different critical temperature for phase transition from the monoclinic (insulator) phase and rutile (metallic) phase and vice versa. The substantial variation in the temperature coefficient of frequency can be largely ascribed to electrode reconfiguration enabled by VO2 phase transition.

Exceptional point protected robust on-chip optical logic gates.

Optical logic gates are crucial components for information processing and communication using photons. Current optical logic gates typically rely on the light interference principle which requires an accurate manipulation of the dynamical phase of light, making the device quite sensitive to system disturbances such as fabrication errors. Here we introduce non-Hermitian principles into the design of optical logic gates that work in the signal transmission process. We propose an exclusive-orgate for silicon-on-insulator platform by employing the physics in the exceptional point (EP) encirclement process. The EP induced mode switching behavior is applied to manipulate the phase of light which is topologically protected by the energy surface around the EP. As a result, the performance of the device is found to be extremely robust to structural parameter disturbances. The proposed non-Hermitian principle is expected to find applications for other on-chip photonic devices toward high robust performance.

Hysteresis Control in Pump-Controlled Systems—A Way to Reduce Mode-Switch Oscillations in Closed and Open Circuits

There is growing interest in using electric motors as prime movers in mobile hydraulic systems. This increases the interest in so-called pump-controlled systems, where each actuator has its own drive unit. Such architectures are primarily appealing in applications where energy efficiency is important and electric recuperation is relevant. An issue with pump-controlled systems is, however, mode-switch oscillations which can appear when the pressure levels in the system are close to the switching condition. In this paper, the mode-switching behavior of different generalized closed and open circuit configurations is investigated. The results show that the choice of where to sense the pressures has a huge impact on the behavior. They also show that, if the pressure sensing components are properly placed, closed and open circuits can perform very similarly, but that mode-switch oscillations still can occur in all circuits. Active hysteresis control is suggested as a solution and its effectiveness is analyzed. The outcome from the analysis shows that active hysteresis control can reduce the risk for mode-switch oscillations significantly.

Modelling second-best choices from the choice-based sample: revelation of potential mode-switching behaviour from transit passenger surveys

Modelling second-best choices from the choice-based sample: revelation of potential mode-switching behaviour from transit passenger surveys

Dynamic buckling of rotationally restrained FG porous arches reinforced with graphene nanoplatelets under a uniform step load

This paper presents a dynamic buckling analysis for a rotationally restrained functionally graded (FG) graphene nanoplatelets (GPLs) reinforced composite (FG-GPLRC) porous arch under a uniform step load where GPL nanofillers are uniformly dispersed while the porosity coefficient varies along the thickness direction of the arch. The effective material properties of the FG-GPLRC porous arch are determined by the volume fraction distribution of materials. Analytical solutions for the symmetric limit point dynamic buckling and anti-symmetric bifurcation dynamic buckling loads of rotationally restrained FG-GPLRC porous arches are derived by using an energy-based approach. Critical geometric parameters that determine the dynamic buckling mode switching behavior are also identified and discussed. Depending on the geometric parameters and the rotational restraint stiffness, the FG-GPLRC porous arch can buckle in either a symmetric limit point mode or an anti-symmetric bifurcation mode dynamically. It is also found that the dynamic buckling load of the arch can be considerably improved by adding a small amount of GPLs as reinforcing nanofillers. The influences of the porosity coefficients, GPL weight fractions, arch dimensions and geometries on the dynamic buckling behavior of rotationally restrained FG-GPLRC porous arches are comprehensively investigated through extensive parametric studies.

Geometrically nonlinear buckling of graphene platelets reinforced dielectric composite (GPLRDC) arches with rotational end restraints

This paper presents an analytical investigation on the nonlinear buckling behavior of graphene platelets reinforced dielectric composite (GPLRDC) arches with rotational end restraints under applied electric and uniform radial load. The effective materials properties of GPLRDC, including the elastic modulus and dielectric permittivity, are estimated by employing effective medium theory (EMT). The analytical solutions for nonlinear equilibrium, critical load of limit point buckling and bifurcation buckling of the GPLRDC arch are derived according to the principle of virtual work. The critical geometric parameters and electric voltage governing the buckling mode switching behavior are also identified and discussed. The effects of graphene platelets (GPLs) weight fraction, size and geometry, applied DC voltage, AC frequency, as well as geometry of the arch on the buckling behavior are examined comprehensively. It is found that the dielectric property of the GPLRDC has significant effects on the buckling behavior of the GPLRDC when the GPLs concentration exceeds the percolation threshold. The nonlinear buckling behavior of the GPLRDC is quite sensitive to the AC frequency within a certain range. Furthermore, the change of the applied voltage can switch the buckling mode and even the number of limit points of the GPLRDC arch.

Dynamic buckling of functionally graded graphene nanoplatelets reinforced composite shallow arches under a step central point load

This paper presents dynamic buckling analysis for a functionally graded graphene nanoplatelets reinforced composite (FG-GPLRC) arch subjected to a step central point load at its center. The arch is composed of multiple composite layers reinforced with graphene nanoplatelets (GPLs) which are evenly distributed in each layer while the GPL weight fraction changes from layer to layer along the thickness direction. The effective materials properties are predicted by Halpin-Tsai micromechanics model for each GPLRC layer. Analytical solutions for symmetric limit point dynamic buckling load and anti-symmetric bifurcation dynamic buckling load for fixed and pinned FG-GPLRC arches are obtained by using energy-based methods. The critical geometric parameters governing the dynamic buckling mode switching behavior are also identified and discussed. It is found that the dynamic stability of the arch can be considerably improved by adding a small amount of GPLs as reinforcing nanofillers, and both symmetric limit point dynamic buckling and anti-symmetric bifurcation dynamic buckling can happen to pinned FG-GPLRC arch while the fixed FG-GPLRC arch can buckle in a symmetric mode only. The influences of GPLs distribution, concentration, dimension of GPL as well as the arch geometrical parameters on the dynamic buckling behavior of FG-GPLRC arches are comprehensively investigated through parametric studies.

Analyzing the effect of government subsidy on shippers’ mode switching behavior in the Belt and Road strategic context

The Chinese government is offering subsidies to promote the recently developed China-Europe rail freight corridor under its Belt and Road Initiative (BRI). Despite significant subsidies, the rail mode (China Railway Express) continues to struggle with low load factor. Accordingly, a competition model (rail vs. maritime) grounded on game-theoretic technique is proposed to analyze the effect of the government subsidy on shippers’ mode switching (from maritime to rail) behavior. Analytical results based on a case of China-Germany rail freight transportation describe shippers’ mode switching patterns in response to a mode subsidy and suggest a subsidy scheme for the government.

Investigating the Mode Switching Behavior from Different Non-Car Modes to Car: The Role of Life Course Events and Policy Opportunities

Life course events can lead to a habitual change of mode choice, which can sometimes be from non-car modes to the car, which is not a desirable outcome from a sustainable point of view. This research studied in depth the mode switching behavior from a range of non-car modes to the car, to identify opportunities for policy intervention to hold back such changes in habit toward car usage. Retrospective commute mode choice and various life course event data over four observation periods were collected. A mixed binary logit regression model was developed to study mode switching behavior from car to non-car modes, followed by the development of a set of “mirror models” (also mixed binary logit) that evaluated mode switches from non-car modes to the car. By observing their distinct reactions to life course events, it was found that users of different types of non-car modes display distinct mode switching behavior, especially in relation to getting married, having their first child and in response to different degrees of commute distance change. A thorough discussion on the policy implications of these findings is provided.

Will commute drivers switch to park-and-ride under the influence of multimodal traveler information? A stated preference investigation

The knowledge about en-trip mode switching behavior with presence of multimodal traveler information is very limited so far. This study investigated the impacts on commute drivers’ en-trip mode switch decisions of smartphone multimodal traveler information systems (SMTIS) which integrate dynamic information of auto-drive and subway park-and-ride (P&R). This is based on data collected from a stated preference survey in Shanghai, China. A panel mixed probit model which accounts for potential correlations of observations among a same driver and heterogeneity in preferences for travel time savings and comfort level of subway car was developed. The panel model has a much better goodness of fit than a model without consideration of panel effect and heterogeneity. The results show that SMTIS have significant impacts on commuter drivers’ decision about switching from auto drive to P&R; the impacts depend on personal attributes including gender, age, education level, income, and P&R use experience; the sensitivity to time savings in the case non-incident induced delays, and the sensitivity to comfort level of subway, both vary significantly among the driver sample.

Evidence for hot clumpy accretion flow in the transitional millisecond pulsar PSR J1023+0038

We present simultaneous optical and near-infrared (IR) photometry of the millisecond pulsar PSR J1023+0038 during its low-mass X-ray binary phase. The r'- and K_s-band light curves show rectangular, flat-bottomed dips, similar to the X-ray mode-switching (active-passive state transitions) behaviour observed previously. The cross-correlation function (CCF) of the optical and near-IR data reveals a strong, broad negative anti-correlation at negative lags, a broad positive correlation at positive lags, with a strong, positive narrow correlation superimposed. The shape of the CCF resembles the CCF of black hole X-ray binaries but the time-scales are different. The features can be explained by reprocessing and a hot accretion flow close to the neutron star's magnetospheric radius. The optical emission is dominated by the reprocessed component, whereas the near-IR emission contains the emission from plasmoids in the hot accretion flow and a reprocessed component. The rapid active-passive state transition occurs when the hot accretion flow material is channelled onto the neutron star and is expelled from its magnetosphere. During the transition the optical reprocessing component decreases resulting in the removal of a blue spectral component. The accretion of clumpy material through the magnetic barrier of the neutron star produces the observed near-IR/optical CCF and variability. The dip at negative lags corresponds to the suppression of the near-IR synchrotron component in the hot flow, whereas the broad positive correlation at positive lags is driven by the increased synchrotron emission of the outflowing plasmoids. The narrow peak in the CCF is due to the delayed reprocessed component, enhanced by the increased X-ray emission.

Guided-Wave Properties of Mode-Selective Transmission Line

The so-called mode-selective transmission line or simply “MSTL” is studied theoretically and experimentally. This low-loss and low-dispersion transmission line operates with a frequency-dependent mode-switching behavior. This self-adaptive mode-selective guided-wave structure begins with the propagation of electromagnetic waves over the lower frequency range in the form of a quasi-TEM fundamental mode similar to the microstrip line case, then followed by a fundamental quasi-TE10 mode with reference to rectangular waveguide over the higher frequency region. To gain insight into the physical mechanism and fundamental features of this mode-selective transmission line, a detailed semi-analytical hybrid-mode analysis is developed through the application of a method of lines. This method allows accurate and effective modeling of MSTL guided-wave properties. Propagation characteristics of this proposed mode-agile structure in terms of dispersion, modal, and loss properties are examined, which leads to the establishment of some basic MSTL design guidelines. Numerical results confirm the expected mode conversion and low-loss behavior through the observation of field evolutions along the structure. For experimental verification, a set of MSTL prototypes are fabricated on two different substrates through dissimilar fabrication processes. Measurements are carried out from dc-to-500 GHz using a vector network analyzer. Excellent agreement between theoretical and experimental results is observed. It is confirmed that the low-dispersion and low-loss behavior of MSTL makes it an outstanding integrated waveguide in support of high-performance super-broadband signal transmission and/or ultra-fast pulse propagation in a fully-integrated platform.

Direct experimental measurement of single-mode and mode-hopping dynamics in frequency swept lasers.

A time-resolved study is presented of the single-mode and mode-switching dynamics observed in swept source vertical cavity surfing emitting lasers and swept wavelength short external cavity lasers. A self-delayed interferometric technique is used to experimentally measure the phase and intensity of these frequency swept lasers, allowing direct examination of the modal dynamics. Visualisation of the instantaneous optical spectrum reveals mode-hop free single mode lasing in the case of the vertical cavity laser, with a tuning rate of 6.3 GHz/ns. More complex mode-switching behaviour occurs in the external cavity laser, with the mode-hopping dynamics found to be dominated by the deterministic movement of the spectral filter. Evidence of transient multi-mode operation and mode-pulling is also presented.

Modelling mode switch associated with the change of residential location

This paper presents the findings of a random parameters logit model (RPL) of mode switching behaviour as a longer-term decision using retrospective survey data. This study focuses on whether or not individuals switch their commute modes following residential relocation. The study accommodates the panel effects of the repeated mode switching decisions of individuals during their life-time and captures unobserved heterogeneity within the RPL modelling framework. This study extensively examines the effects of past travel behaviour, changes in household state due to life-cycle events, attitude, and accessibility measures. Factor analysis is performed to generate the following six attitudinal factors: pro-high density, pro-environment, travel satisfaction, travel stress, pro-car, and pro-active transportation. The model results suggest that past travel experiences significantly influence the mode switch decisions. Individuals are found to show preference in persisting with their past mode. In the case of change in household state, individuals are more likely to switch mode if household size increases. Among the attitudinal variables, pro-high density, pro-active transportation, and travel stress are found to influence mode switch. Individuals living closer to transit stops show preference to change mode; in contrast, individuals living farther from work locations reveal a lower likelihood to change mode. The model results reveal that heterogeneity exists among the individuals. For example, individuals with pro-high density attitude show significant variation during mode switching decisions. This study provides important behavioural insights, which will assist transportation planning and policy making that focuses to influence longer-term shifts in travel behaviour and choice of residential location.

Linear stability analysis of interactions between mixing layer and boundary layer flows

The linear instabilities of incompressible confluent mixing layer and boundary layer were analyzed. The mixing layers include wake, shear layer and their combination. The mean velocity profile of confluent flow is taken as a superposition of a hyperbolic and exponential function to model a mixing layer and the Blasius similarity solution for a flat plate boundary layer. The stability equation of confluent flow was solved by using the global numerical method. The unstable modes associated with both the mixing and boundary layers were identified. They are the boundary layer mode, mixing layer mode 1 (nearly symmetrical mode) and mode 2 (nearly anti-symmetrical mode). The interactions between the mixing layer stability and the boundary layer stability were examined. As the mixing layer approaches the boundary layer, the neutral curves of the boundary layer mode move to the upper left, the resulting critical Reynolds number decreases, and the growth rate of the most unstable mode increases. The wall tends to stabilize the mixing layer modes at low frequency. In addition, the mode switching behavior of the relative level of the spatial growth rate between the mixing layer mode 1 and mode 2 with the velocity ratio is found to occur at low frequency.