Dynamics Of Coupled System Research Articles

Dynamic analysis of the flexible hub-beam system based on rigid-flexible coupling mechanism

The flexible hub-beam system is a typical structure of the rigid-flexible coupling dynamic system. In this paper, the dynamic property of the flexible hub-beam system is investigated. First, based on the dynamic analysis of the flexible beam in the flexible hub-beam system, the dynamic model of a flexible hub-beam-tip mass system is established and researched. Second, the dynamic response of the flexible beam under different external loads, including end concentrated load, end sinusoidal load, and uniform load, is analyzed and calculated. Finally, the influence of magnitude, direction, and type of load on the dynamic response of the flexible beam is also discussed. This research can provide a novel strategy for controlling the maximum stress of the structural components to be lower than the yield stress of the material, and flexible components remain in the linear elastic range even under the condition of high-speed rotation.

Development of a behaviour-pattern based global sensitivity analysis procedure for coupled socioeconomic and environmental models

Dynamically Coupled Socioeconomic system dynamics models integrated with physically-based Environmental Models (DCSEM) can capture relationships between complex environmental and socioeconomic systems, and are promising tools for participatory environmental management involving the integration of various viewpoints, disciplines and processes for sustainable water resources management. However, the application of DCSEMs has been limited for many reasons, including the complexity of the model coupling process (i.e., the lack of a flexible model coupling approach), issues of over-parameterization, high parameter uncertainty, intensive computational requirements (due to many interacting parameters), and the possibility of eliciting behaviour-pattern oriented model outputs. As such, most conventional (numerical) procedures for model evaluation (i.e., analysis of point values of modelled results) that have been implemented for physically-based models are not applicable to DCSEMs. In order to address these challenges, this study developed a novel automatic behaviour-pattern global sensitivity analysis (GSA) procedure to determine the influence of input parameters on the general behaviour trends (rather than numerical point values) of coupled model outputs. The developed behaviour-pattern GSA procedure was implemented in an existing software (Tinamït), developed previously by the authors, to ensure ease-of-use. This study investigates the suitability of the proposed behaviour-pattern GSA procedure for the analysis of DCSEMs by comparing the proposed procedure with the conventional numerical procedure. The numerical and proposed behaviour-pattern procedures, coupled with the Morris (qualitative) and EFAST (quantitative) GSA methods, were applied to a DCSEM to rank and screen parameters in a water table depth simulation in Pakistan. The determination of important parameters facilitates subsequent model calibration and groundwater management. It was found that the Morris and EFAST methods achieved similar parameter ranking results in the numerical and behavioural procedures, respectively. The results also indicated that the behaviour-pattern GSA procedure offers more information about several important parameters, and a variety of parameter ranking orders, compared to the numerical GSA procedure, regardless of which GSA method (Morris or EFAST) was used. The increased information obtained through the application of the developed behaviour-pattern procedure confirms that the DCSEM model outputs are behaviour-oriented. It is recommended that the proposed behaviour-pattern GSA procedure be used with the Morris method, which has a higher computational efficiency (>150 times) than the EFAST method, to detect important parameters in DCSEMs.

Mechano-electric and mechano-chemo-transduction in cardiomyocytes.

Cardiac excitation-contraction (E-C) coupling is influenced by (at least) three dynamic systems that couple and feedback to one another (see Abstract Figure). Here we review the mechanical effects on cardiomyocytes that include mechano-electro-transduction (commonly referred to as mechano-electric coupling, MEC) and mechano-chemo-transduction (MCT) mechanisms at cell and molecular levels which couple to Ca2+ -electro and E-C coupling reviewed elsewhere. These feedback loops from muscle contraction and mechano-transduction to the Ca2+ homeodynamics and to the electrical excitation are essential for understanding the E-C coupling dynamic system and arrhythmogenesis in mechanically loaded hearts. This white paper comprises two parts, each reflecting key aspects from the 2018 UC Davis symposium: MEC (how mechanical load influences electrical dynamics) and MCT (how mechanical load alters cell signalling and Ca2+ dynamics). Of course, such separation is artificial since Ca2+ dynamics profoundly affect ion channels and electrogenic transporters and vice versa. In time, these dynamic systems and their interactions must become fully integrated, and that should be a goal for a comprehensive understanding of how mechanical load influences cell signalling, Ca2+ homeodynamics and electrical dynamics. In this white paper we emphasize current understanding, consensus, controversies and the pressing issues for future investigations. Space constraints make it impossible to cover all relevant articles in the field, so we will focus on the topics discussed at the symposium.

The effect of seasonal strength and abruptness on predator–prey dynamics

Coupled dynamical systems in ecology are known to respond to the seasonal forcing of their parameters with multiple dynamical behaviours, ranging from seasonal cycles to chaos. Seasonal forcing is predominantly modelled as a sine wave. However, the transition between seasons is often more sudden as illustrated by the effect of snow cover on predation success. A handful of studies have mentioned the robustness of their results to the shape of the forcing signal but did not report any detailed analyses. Therefore, whether and how the shape of seasonal forcing could affect the dynamics of coupled dynamical systems remains unclear, while abrupt seasonal transitions are widespread in ecological systems. To provide some answers, we conduct a numerical analysis of the dynamical response of predator–prey communities to the shape of the forcing signal by exploring the joint effect of two features of seasonal forcing: the magnitude of the signal, which is classically the only one studied, and the shape of the signal, abrupt or sinusoidal. We consider both linear and saturating functional responses, and focus on seasonal forcing of the predator’s discovery rate, which fluctuates with changing environmental conditions and prey’s ability to escape predation. Our numerical results highlight that a more abrupt seasonal forcing mostly alters the magnitude of population fluctuations and triggers period–doubling bifurcations, as well as the emergence of chaos, at lower forcing strength than for sine waves. Controlling the variance of the forcing signal mitigates this trend but does not fully suppress it, which suggests that the variance is not the only feature of the shape of seasonal forcing that acts on community dynamics. Although theoretical studies may predict correctly the sequence of bifurcations using sine waves as a representation of seasonality, there is a rationale for applied studies to implement as realistic seasonal forcing as possible to make precise predictions of community dynamics.

Research on Coordination and Driving Factors of Sports Industry and Regional Sustainable Development—Empirical Research Based on Panel Data of Provinces and Cities in Eastern China

The steady and healthy development of the sports industry can promote regional sustainable development. In order to explore the coordination situation and driving factors between the sports industry and regional sustainable development, this article builds a coupling coordination evaluation index system and dynamic factor index system for the sports industry and regional sustainable development. Using the entropy method, coupling coordination model and random effect model, this article analyzes the comprehensive level, coupling coordination relationship and driving factors of the sports industry and regional sustainable development in eleven provinces and cities in eastern China, from 2013 to 2017. The results show that the comprehensive level of the sports industry and regional sustainable development in eastern China is showing a steady growth trend, and the sports industry is growing faster than regional sustainable development. The degree of coupling coordination among provinces and cities has increased significantly, but the spillover effects of coupling coordination in each region are not obvious. The level of overall coupling coordination is primary coordination; regional innovation, industrial structure upgrade, and human capital can promote the improvement of coupling coordination. Therefore, it is necessary to strengthen cross-regional cooperation, build a cross-regional “sports+” industry group, give play to the “sports +” spillover effect, create a coupling platform for the sports industry and regional sustainable development, release the superimposed effect of multiple driving factors, and facilitate the evolution of coupling coordination to higher levels.

Vibration and elastic wave propagation in spatial flexible damping panel attached to four special springs

Investigation of the characteristics of the vibration and elastic wave propagation in the ultra-large ultra-flexible damping spatial structures is the precondition for the active control of the dynamic response of the spatial structure from the viewpoint of the wave absorption perspective. The difficulties of the analysis on the characteristics of the vibration and elastic wave propagation in the spatial structures result from the following two aspects: one is the coupling effects between the attitude control, the orbit dynamics and the structural vibration exciting the elastic waves; and another is the non-smooth factors including the on-off controllers and the geometric constraints between the components of the structure. Employing the complex structure-preserving approach, the vibration and wave propagation characteristics in the spatial flexible damping panel attached to four special springs are investigated in this paper. Considering the coupling between the structural vibration, the attitude dynamics and the orbit dynamics, a dynamic model is established for the spatial flexible damping panel-spring-mass system. Compared with the dynamic model proposed in previous work, the springs suspending the panel are considered as unilateral non-smooth constraints to describe the zero constraints when some tethers are slack during certain time periods in the tethered satellite system described by the dynamic model presented in this paper. Relying on the local structure-preserving properties of the generalized multi-symplectic method and the excellent long-term numerical behaviour of the symplectic method, the complex structure-preserving method is employed. Some novel vibration and wave propagation characteristics in the spatial flexible damping panel attached to four special springs with different initial attitude angles are revealed, which include the damping characteristics of the elastic wave propagation in the spatial panel and the interaction process of the elastic waves, especially the resonance phenomena between the elastic waves obliquely propagating in the panel. The complex structure-preserving method presented in this paper is proved as an effective approach to deal with the non-smooth coupling dynamic systems and the vibration and wave propagation characteristics revealed can be used to guide the structural design as well as the material selection for the tethered satellite system.

Existence, Stability and Controllability Results of Coupled Fractional Dynamical System on Time Scales

In this work, we establish existence, uniqueness, Hyer-Ulam (HU) stability and controllability results for a coupled fractional dynamical system on time scales. Some fixed point theorems and nonlinear functional analysis have been used to establish these results. Also, we have given an example for different time scales, to show the applications of these obtained analytical results.

Analysis of Water Management Scenarios Using Coupled Hydrological and System Dynamics Modeling

The North China Plain (NCP) has been affected by severe water scarcity over the past several decades. To address this issue, several water management plans have already been launched. Among them, the new South-to-North Water Diversion Project (SNWDP) draws the most attention. However, the effectiveness of the SNWDP is yet to be evaluated. In the present study, we developed a coupled hydrological and system dynamics (SD) model to analyze water management scenarios for the NCP: S1: business as usual, S2: less agricultural water, S3: more domestic and industrial water reuse, S4: SNWDP, and S5: combined efforts. The impact of climate change has been accounted for in all scenarios. The SD model was based on VENSIM, and the hydrological model was based on the MIKE SHE code. The results indicated that the groundwater development in the NCP will not be sustainable without exploiting the full potential of the SNWDP resource. However, the SNWDP alone can only lessen the water crisis, it is not able to stop the groundwater storage from further declining. Solving the water scarcity problem in the NCP will require a combination of highly reduced water use and a continued water supply from the SNWDP. Our results also indicated that innovative water saving technologies are urgently needed in the restructuring of the industrial sector. Furthermore, the study illustrated an added challenge to water management since the uncertainty range on climate change impacts are shown to be of the same magnitude as the impacts of combined management measures. Therefore, it requires great caution when making the future water management strategies in the NCP.

Vehicle-bridge coupling vibration of curved beam bridge under earthquake excitation

Based on the non-inertial reference system, the vehicle model of four freedom degrees is used to establish the vehicle-bridge coupling dynamic system model of the curved beam in space. Considering the vehicle-bridge coupling vibration characteristics under the non-uniform seismic excitation at the two supports of the bridge, the three-dimension space curvilinear-vehicle coupling dynamic control equation is established based on the Hamiltonian principle. Then the coupling dynamic control equation of the vehicle and bridge is numerically analyzed by the method of separating variables.

Resilience Dynamics of Urban Water Supply Security and Potential of Tipping Points

AbstractCities are the drivers of socioeconomic innovation and are also forced to address the accelerating risk of failure in providing essential services such as water supply today and in the future. Here, we investigate the resilience of urban water supply security, which is defined in terms of the services that citizens receive. The resilience of services is determined by the availability and robustness of critical system elements or “capitals” (water resources, infrastructure, finances, management efficacy, and community adaptation). We translate quantitative information about this portfolio of capitals from seven contrasting cities on four continents into parameters of a coupled system dynamics model. Water services are disrupted by recurring stochastic shocks, and we simulate the dynamics of impact and recovery cycles. Resilience emerges under various constraints, expressed in terms of each city's capital portfolio. Systematic assessment of the parameter space produces the urban water resilience landscape, and we determine the position of each city along a continuous gradient from water insecure and nonresilient to secure and resilient systems. In several cities stochastic disturbance regimes challenge steady‐state conditions and drive system collapse. While water insecure and nonresilient cities risk being pushed into a poverty trap, cities which have developed excess capitals risk being trapped in rigidity and crossing a tipping point from high to low services and collapse. Where public services are insufficient, community adaptation improves water security and resilience to varying degrees. Our results highlight the need for resilience thinking in the governance of urban water systems under global change pressures.

Correlation Dimension Detects Causal Links in Coupled Dynamical Systems

It is becoming increasingly clear that causal analysis of dynamical systems requires different approaches than, for example, causal analysis of interconnected autoregressive processes. In this study, a correlation dimension estimated in reconstructed state spaces is used to detect causality. If deterministic dynamics plays a dominant role in data then the method based on the correlation dimension can serve as a fast and reliable way to reveal causal relationships between and within the systems. This study demonstrates that the method, unlike most other causal approaches, detects causality well, even for very weak links. It can also identify cases of uncoupled systems that are causally affected by a hidden common driver.

Coupled LMDI and system dynamics model for estimating urban CO2 emission mitigation potential in Shanghai, China

In this study, both the extended logarithmic mean divisia index (LMDI) model and the system dynamics (SD) model were used to explore determinants of CO2 emission change during 1995–2016 and to predict the emission mitigation potential from 2016 to 2030 in Shanghai (China). Some novel factors (e.g., private car ownership, urban travel structure, and income level) were chosen and added to the LMDI model. The combination of the LMDI and SD models might provide a new pathway for policymakers to cope with such sophisticated issues. The results showed that: (1) GDP per capita is the main positive driving force for CO2 emission growth, followed by population, average income level per capita, and car ownership per capita. Energy intensity is the main factor for carbon mitigation, followed by economic structure, residential energy intensity, and emission coefficient. (2) The additive effect of different scenarios is essential for emission control. (3) CO2 emissions and emission per capita would peak by 2025 at the level of 218.20 Mt and 8.83 t per capita, respectively. Tertiary industry and public travel model promotion, power generation structure, and primary energy structure optimization would facilitate emission mitigation in Shanghai, which could also be a reference for other similar mega-cities in developing countries.

Dimensional-Invariance Principles in Coupled Dynamical Systems: A Unified Analysis and Applications

In this paper we study coupled dynamical systems and investigate dimension properties of the subspace spanned by solutions of each individual system. Relevant problems on \textit{collinear dynamical systems} and their variations are discussed recently by Montenbruck et. al. in \cite{collinear2017SCL}, while in this paper we aim to provide a unified analysis to derive the dimensional-invariance principles for networked coupled systems, and to generalize the invariance principles for networked systems with more general forms of coupling terms. To be specific, we consider two types of coupled systems, one with scalar couplings and the other with matrix couplings. Via the \textit{rank-preserving flow theory}, we show that any scalar-coupled dynamical system (with constant, time-varying or state-dependent couplings) possesses the dimensional-invariance principles, in that the dimension of the subspace spanned by the individual systems' solutions remains invariant. For coupled dynamical systems with matrix coefficients/couplings, necessary and sufficient conditions (for constant, time-varying and state-dependent couplings) are given to characterize dimensional-invariance principles. The proofs via a rank-preserving matrix flow theory in this paper simplify the analysis in \cite{collinear2017SCL}, and we also extend the invariance principles to the cases of time-varying couplings and state-dependent couplings. Furthermore, subspace-preserving property and signature-preserving flows are also developed for coupled networked systems with particular coupling terms. These invariance principles provide insightful characterizations to analyze transient behaviors and solution evolutions for a large family of coupled systems, such as multi-agent consensus dynamics, distributed coordination systems, formation control systems, among others.

Investigation of electromechanical coupling lateral/torsional vibration in a high-speed rotating continuous flexible shaft of PMSM

The rotor of Permanent Magnet Synchronous Motors (PMSM) is an electromechanical coupled dynamics system. The asymmetrical magnetic field-induced mechanical vibration has important effect on the operation performance of the high speed and high power density PMSM. In this paper, an electromechanical coupled lateral/torsional dynamic model caused by electromagnetic excitation is derived based on a Lagrange–Maxwell approach. The stability of the equilibrium was analyzed using a linearized matrix of the system equation. A stability criteria of coupled torsional-lateral motions was provided, and the influences of the electromagnetic and mechanical parameters on mechanical vibration stability were investigated. Finally, the vibration damping of the electromechanical coupling parameters vibration was explored. These results we represent get us better to understand the nonlinear response of the eccentric PMSM rotor system and are beneficial to control and diagnose the eccentric.

From Carbon Calculators to Energy System Analysis in Cities

Energy systems in cities need to be decarbonized and are becoming more integrated via energy sector coupling. Today, cities often use simple methods to assess their low carbon targets, e.g., carbon calculators, and these methods use annualized carbon reduction potentials. For example, reductions from heat savings in buildings or fuel demand in transport. This is done because it is simple and fast. This paper describes a methodology that goes beyond carbon calculators and assesses highly renewable energy systems. The methodology is carried out for a case city—Sønderborg, Denmark. Using a national 100% renewable energy study and a suitable energy system analysis tool (EnergyPLAN), the method accounts for inter-sector coupling and energy system dynamics. The energy system is assessed by comparing the results from the analysis tool against numerous key sustainability factors for a Smart Energy System. The paper illustrates how the method delivers a sustainable 100% renewable Smart Energy System for Sønderborg, which can be part of the Danish energy system in 2050 based on local resources. The paper discusses the broader applicability of the method within strategic energy planning.

Non-hermitian Hamiltonian description for quantum plasmonics: from dissipative dressed atom picture to Fano states

We derive effective Hamiltonians for a single dipolar emitter coupled to a metal nanoparticle (MNP) with particular attention devoted to the role of losses. For small particles sizes, absorption dominates and a non-hermitian effective Hamiltonian describes the dynamics of the hybrid emitter-MNP nanosource. We discuss the coupled system dynamics in the weak and strong coupling regimes offering a simple understanding of the energy exchange, including radiative and non-radiative processes. We define the plasmon Purcell factors for each mode. For large particle sizes, radiative leakages can significantly perturbate the coupling process. We propose an effective Fano Hamiltonian including plasmon leakages and discuss the link with the quasi-normal mode description. We also propose Lindblad equations for each situation and introduce a collective dissipator for describing the Fano behavior.

The transient response of high-speed wheel/rail rolling contact on “roaring rails” corrugation

A high-speed wheel/rail finite element model is developed to focus on the non-steady-state rolling contact. The wheel/rail contact is solved based on the surface-to-surface contact algorithm, and the explicit finite element method is used to simulate the dynamic high-speed wheel/rail rolling contact. Considering the track–vehicle coupling system dynamics and the wheel/rail geometric nonlinearities, the wheel/rail contact on the short wave rail corrugation under the high-frequency vibration and the influence of train passing frequency on the track–vehicle system dynamics are studied. The explicit finite element method can be used to simulate the non-steady-state rolling contact process of the high-speed wheel/rail. After the initial load condition, the wheel/rail contact state tends to be stable in a short period of time. The short wave corrugation causes the high-frequency vibration of the track–vehicle system; the slightly advanced phase of the wheel/rail contact force promotes the development of rail corrugation in the rolling direction. When the train passing frequency is close to the rail pinned–pinned frequency, the pinned–pinned resonance occurs. The overall vibration near the fastening is relatively large and accelerates the damage of components. The longitudinal force is clearly affected by the traction torque with a periodic wheel/rail stick-slip vibration. The pinned–pinned resonance will promote the sliding wear at the wave trough near the fastening and it will become severe with the increase of the traction.

Coupled system dynamics and computational fluid dynamics simulation of plant transients in sodium cooled fast reactors

Abstract Analysis of transient thermal hydraulic behavior of the plant during various design basis events is important for (i) demonstrating safety, (ii) design of plant protection system, (iii) deciding safety parameters, (iv) design specification on response time of systems and instruments, (v) estimation of transient thermal loading on various structures and (vi) meticulous planning of plant operating strategy. Traditionally these studies are carried out using one-dimensional system dynamics models. Due to the presence of large sodium pools in the primary circuit of prototype fast reactors, there is a possibility of significant stratification effects which may govern the transient under certain plant conditions. Traditionally, sodium pools are treated as single well mixed volumes or network of one dimensional control volumes in system dynamics models. One-dimensional models fail to simulate stratification effects leading to unrealistic transient simulation. An integrated code system with coupling of one dimensional and multi-dimensional models is an optimum approach to overcome this difficulty. This paper discusses development of multi-dimensional transient CFD code for turbulent flow simulations in stratified sodium pool of a fast reactor and integration of the same with one dimensional system dynamics models for the rest of the plant. The predictions of the improved code are compared against those of system dynamics model of entire plant.

An Information-Theoretic Approach to Self-Organisation: Emergence of Complex Interdependencies in Coupled Dynamical Systems.

Self-organisation lies at the core of fundamental but still unresolved scientific questions, and holds the promise of de-centralised paradigms crucial for future technological developments. While self-organising processes have been traditionally explained by the tendency of dynamical systems to evolve towards specific configurations, or attractors, we see self-organisation as a consequence of the interdependencies that those attractors induce. Building on this intuition, in this work we develop a theoretical framework for understanding and quantifying self-organisation based on coupled dynamical systems and multivariate information theory. We propose a metric of global structural strength that identifies when self-organisation appears, and a multi-layered decomposition that explains the emergent structure in terms of redundant and synergistic interdependencies. We illustrate our framework on elementary cellular automata, showing how it can detect and characterise the emergence of complex structures.

An Analysis of the Eco-Innovation Mechanism and Policies in the Pulp and Paper Industry Based on Coupled Game Theory and System Dynamics

The environment is the basis for the living and development of the human, and eco-innovation is the key driver of new economic growth. However, for some underdeveloped regions in China, it is still a challenge for the local government to get a balance between the goals of economic and environment. The paper selects the pulp and paper industry, which creates tremendous pollution to the environment and is closely related to the daily life. According to the particular characteristics of pulp and paper industry in Sichuan Province, the industry of pulp and paper of bamboo is redesigned to improve the local ecosystem, while increasing the income of local farmers. From the perspective of game theory, the relationships between the government, the enterprise, and the farmers are analyzed. The result shows that government increases the subsidy and penalty to the enterprise, which can increase the investment in eco-innovation, enhancing the competitiveness of enterprises and raising the income of farmers. Moreover, it can also improve the ecologically fragile areas by the utilization of bamboo park. In addition, in this paper, a system dynamics model is proposed to explore the impact of different policies on the environment. The results show that increasing the subsidy is a more efficient way to protect the environment, and is one of the important drivers to eco-innovation in some underdeveloped regions in China.