Complex Coupling System Research Articles

The Construction of Analytical Exact Soliton Waves of Kuralay Equation

Abstract The primary objective of this work is to examine the Kuralay equation, which is a complex integrable coupled system, in order to investigate the integrable motion of induced curves. The soliton solutions derived from the Kuralay equation are thought to be the supremacy study of numerous significant phenomena and extensive applications across a wide range of domains, including optical fibres, nonlinear optics and ferromagnetic materials. The inverse scattering transform is unable to resolve the Cauchy problem for this equation, so the analytical method is used to produce exact travelling wave solutions. The modified auxiliary equation and Sardar sub-equation approaches are used to find solitary wave solutions. As a result, singular, mixed singular, periodic, mixed trigonometric, complex combo, trigonometric, mixed hyperbolic, plane and combined bright–dark soliton solution can be obtained. The derived solutions are graphically displayed in 2-D and 3-D glances to demonstrate how the fitting values of the system parameters can be used to predict the behavioural responses to pulse propagation. This study also provides a rich platform for further investigation.

Research on operating characteristics of V-shaped ultrasonic motor based on improved electromechanical coupling model

Abstract As a complex electromechanical coupling system, evaluating the motion characteristics of an ultrasonic motor via an accurate theoretical model is challenging due to the strong coupling between its electrical and mechanical properties. To address this issue, the paper first establishes a complete dynamic model of the V-shaped ultrasonic motor (VUSM). In contrast to the traditional dynamic model, the proposed model incorporates the centroid vibration of the stator and applies the weighted residual method to reduce the computational complexity by simplifying the dynamic model from infinite-dimensional degrees of freedom to two degrees of freedom. Subsequently, the finite element method is employed to determine the vibration mode of the stator structure and derive the two-phase operational mode of the motor. Using these two-phase working modes, the model is then solved to predict the motor's output characteristics under any operational condition. Furthermore, an electrical model accounting for preload nonlinearity was developed based on the dynamic model and compared with the model without considering preload nonlinearity, supported by experimental verification. The findings demonstrate that the established dynamic model and electrical model can accurately simulate the changing laws of the input and output characteristics of the motor, which provides assistance for the subsequent operation status evaluation of the motor and fault diagnosis during operation.

Coupled Analysis of Risk Factor for Tailing Pond Dam Failure Accident Based on N–K Model and SNA

The failure of tailings pond dams represents a complex coupled system involving various risk factors, including human, governance, facilities, and environmental aspects. It is crucial to identify key risk factors at the system level to enhance the safety management of tailings ponds. We analyzed 74 cases of tailings pond dam failure accidents, both domestically and internationally, from the perspectives of human, governance, facility, and environment. We employed the 2–4 Model to identify and extract the causes of dam failures, summarizing these into four primary risk factors and 40 secondary risk factors, while constructing a risk coupling mechanism model. The natural killing (N–K) model was implemented to analyze the risk coupling values of primary risk factors and quantify these couplings. The N–K model facilitated an analysis of the risk coupling values of first-level risk factors, while social network analysis (SNA) was employed to visualize the relationships among second-level risk factors and assess the centrality and accessibility of nodes within the risk factor network. The out-degree of the risk nodes was corrected by integrating the N–K model with the SNA, leading to the identification of key risk factors associated with tailings pond dam failures and the formulation of corresponding safety prevention and control strategies. The findings indicate that managing multi-risk factor coupling is an effective approach to mitigating the occurrence of tailings pond dam failure accidents. Notably, unfavorable environmental risk factors significantly contribute to the coupling of human–governance–facility–environmental risks, necessitating targeted management strategies. Furthermore, inadequate safety supervision, weak safety awareness, inadequate receipt and inspection, and irregular operation represent additional key risk factors requiring focused prevention and control efforts.

Revealing the evolution of spatiotemporal patterns of urban expansion using mathematical modelling and emerging hotspot analysis

The rapid expansion of cities in developing countries has led to many environmental problems, and the mechanism of urban expansion (UE), as a more complex human-land coupled system, has always been a difficult issue to research. This paper introduces a new approach by establishing an analytical framework for spatiotemporal pattern mining, exemplified by studying the urban growth of Changsha City from 1990 to 2019. Initially, an emerging hotspot analysis model (EHA) is employed to examine the spatiotemporal changes of urban growth on a macro scale. Mathematical models are subsequently utilized to quantify the correlations between urban expansion and selected infrastructural and topographical factors. Building on these findings, the paper constructs mathematical models to further quantify the spatiotemporal evolution of various urban sprawl patterns across different regions, aiming to elucidate and quantify the significant variations in UE over time and space. The study reveals that, as an emerging city, Changsha's hotspots of urban expansion prior to 2003 were primarily concentrated in the city centre, subsequently spreading to the periphery. The radial influence of metro stations on UE is notably less than that of railway stations—approximately 3 km versus 8 km—and the impact diminishes rapidly before gradually tapering off. Moreover, UE in Changsha predominantly occurs on slopes with gradients ranging from 1.1° to 7.5°, and significant development capacity is observed at elevations between 36.1 m and 78.3 m above sea level, with a tendency for urban sprawl to migrate to lower elevations. The paper also identifies three distinct patterns of urban expansion across different regions: an initial slow-growth phase, followed by a rapid escalation to a peak, and subsequently a swift decline to near stagnation. Additionally, it highlights a significant correlation between the proportion of built-up areas at the micro-regional scale and the stages of UE. This correlation was quantitatively analysed by constructing a logistic function, which demonstrated a robust fit that effectively captures spatiotemporal heterogeneity in the dynamics of UE. These insights enhance the selection of drivers in urban simulation models and deepen the understanding of the complex dynamics that influence urban development.

The construction of exact solution and explicit propagating optical soliton waves of Kuralay equation by the new extended direct algebraic and Nucci’s reduction techniques

ABSTRACT The aim of this paper is to investigate the integrable motion of induced curves using the Kuralay equation, which is a complex integrable coupled system. The soliton solutions derived from Kuralay equation are supposed to represent the most advanced research in several significant phenomena, including optical fibers, nonlinear optics, and ferromagnetic materials. Analytical methods are used to obtain traveling wave solutions for this model as the Cauchy problem cannot be addressed by the inverse scattering transform. In order to find the solitary wave solutions, the new extended direct algebraic and Nucci’s reduction approaches are taken over. As a result, the new extended direct algebraic method provides singular, mixed singular, periodic, mixed trigonometric, complex combo, trigonometric, mixed hyperbolic, plane, and combined bright-dark soliton solutions. The Nucci’s reduction technique develops the first integral of differential equation to discuss the conservation and exact solutions. To ensure the sensitivity of the study, the effect of waves on the propagation of solitons and the sensitivity of the model is examined. To illustrate how the fitting values of the system parameters may be utilized to anticipate the behavioral reactions to pulse propagation, the resulting solutions are visually shown in 2D and 3D charts.

Systematic Errors in Weather and Climate Models: Challenges and Opportunities in Complex Coupled Modeling Systems

Abstract 6th WGNE workshop on systematic errors in weather and climate models What: Scientists, ranging from early career to highly experienced, involved in the development of weather and climate models and in the diagnosis of model errors, held an international workshop to discuss the nature, causes and remedies of systematic errors across timescales and across Earth system modeling components. When: 31 Oct - 04 Nov 2022 Where: Reading, UK and online

A Modified JFNK for Solving the HTR Steady State Secondary Circuit Problem

A nuclear power plant is a complex coupling system, which features multi-physics coupling between reactor physics and thermal-hydraulics in the reactor core, as well as the multi-circuit coupling between the primary circuit and the secondary circuit by the shared steam generator (SG). Especially in the pebble-bed modular HTR nuclear power plant, different nuclear steam supply modules are further coupled together through the shared main steam pipes and the related equipment in the secondary circuit, since the special configuration of multiple reactor modules connects to a steam turbine. The JFNK (Jacobian-Free Newton–Krylov) method provides a promising coupling framework to solve the whole HTR nuclear power plant problem, due to its excellent convergence rate and strong robustness. In this work, the JFNK method was modified and applied to the steady-state calculation of the HTR secondary circuit, which plays an important role in simultaneous solutions for the whole HTR nuclear power plant. The main components in the secondary circuit included SG, steam turbine, condenser, feed pump, high/low-pressure heat exchanger, deaerator, as well as the extraction steam from the steam turbine. The results showed that the JFNK method can effectively solve the steady state issue of the HTR secondary circuit. Moreover, the JFNK method could converge well within a wide range of initial values, indicating its strong robustness.

Effect of levitation gap feedback time delay on the EMS maglev vehicle system dynamic response

EMS maglev train uses the active control system to maintain the levitation stability, time delay is widespread in control system. However, the existing maglev dynamics studies rarely consider the effect of time delay, so these analysis results cannot directly guide the engineering design. This paper starts from a theoretical analysis of the levitation stability of a single electromagnet levitation system to obtain the theoretical critical value for the time delay. Then the model is gradually extended to a complete vehicle model and a vehicle-girder coupling dynamics model to find the time delay engineering critical values for the complex coupling system. In order to seek ways to reduce the influence of time delay on the dynamic responses, this paper analyzes the influence regularities of the running speed and control parameters on the dynamic response under the effect of time delay. The result shows that the theoretical critical value of the time delay is equal to the ratio of the differential coefficient and proportional coefficient of the PID controller. For a complex maglev system, the engineering critical value is less than the theoretical critical value. Higher running speeds lead to time delay having a more obvious effect on the maglev system’s dynamic responses. Selecting the smaller proportional coefficient and appropriate differential coefficient for the levitation control system can expand the stability region and reduce the influence of time delay on the maglev system. This analysis is helpful and meaningful to the understanding of the EMS vehicle system stability, and helpful to explore the reason of violent coupled vibration in actual engineering.

Multivariable Decoupling and Nonlinear Correction Method for Image-Based Closed-Loop Tracking of the Risley Prisms System.

Image-based closed-loop tracking (IBCLT) is an important part of the process of target tracking. The Risley prism system has a unique advantage in improving the target tracking ability because of its compact and lightweight structure. Compared with traditional target tracking equipment, the Risley prism system has two difficulties in the process of IBCLT. First, the Risley prism is a complex coupling system of double input and double output. Second, the Risley prism itself is a nonlinear system. These problems lead to decrease in dynamic response and inconsistent target tracking capabilities. Thus, this paper proposes a method to implement multivariable decoupling and reduce the nonlinear effect. First, the boresight error of IBCLT is decoupled to the azimuth and elevation directions by the rotation matrix error-decoupling (RMED) method. Second, the gains of IBCLT in azimuth and elevation directions are independent variables that comes from two functions of the target elevation angle. The experimental results show that the IBCLT error deviation of different static targets in the field of view is within 0.025 arcsec, which is 70% lower compared with the fixed gain method. Furthermore, the steady-state error deviation of moving targets is controlled within 2.5 arcsec. These experimental results prove the feasibility and effectiveness of the proposed method.

The energy release rate of crack growth in an irradiation-induced thermo-diffusion-mechanical (I-TDM) coupling system

The material cracking behavior in the reactor is generated under the irradiation effect accompanied by thermal expansion, fission product diffusion, and mechanical load. In this study, the energy release rate for crack growth under irradiation has been deduced synthetically according to the thermodynamically consistent method and numerically implemented by the finite element method (FEM). Variation in the total energy was obtained based on the principle of minimum potential energy in which the dissipative behavior can be characterized by fission energy, irreversible heat flow, and diffusion of fission products. Through calculating the variation in the total energy with respect to crack length, the energy release rate for crack propagation was analytically represented. Additionally, the total energy release rate for deflective cracks was also derived to predict the crack kinking. Furthermore, the numerical implementation of the presented model was performed by FEM and the equivalent domain integral method. Effects of irradiation on the physical fields and the energy release rate near the crack tip were investigated and analyzed in such a complex I-TDM coupling system. This study can be developed to investigate fracture problems, assess structural integrity, and evaluate material strength of irradiated materials.

Risk Propagation in Multilayer Heterogeneous Network of Coupled System of Large Engineering Project

Because of the long duration, multiplicity of technical disciplines, large number of project stakeholders, and high levels of complexity and uncertainty, project risk propagation control in large engineering projects (LEPs) is an enormous challenge for project managers. Although previous research has attained many risk propagation achievements regarding complex systems, complex coupled system modeling ignores the heterogeneity of the organizational structure of the actual LEPs, which affects the reliability of the calculated risk propagation results. To bridge this gap, this paper abstracts the LEP structure into a multilayer heterogeneous network comprising the stakeholder network and the project schedule network and proposes a method for characterizing the coupling relationship between two layers of the heterogeneous network. Then, the multiple uncertainties in risk propagation are greatly considered, and a risk propagation model is established based on the multilayer heterogeneous network and improved related schedule risk analysis model (CSRAM). Finally, the proposed model is applied to determine the delayed payment risk propagation in an actual LEP to verify the feasibility of the proposed model. The results indicate the following: (1) the delayed payment risk of a stakeholder evolves into a delay in the entire project; (2) several groups of comparative simulation experiments show that the proposed model, which considers multiple uncertainties and actual networks, includes more comprehensive and valuable risk information; (3) the multiple uncertainties of risk propagation are gradually superimposed with the increase in the number of construction activities affected by risk propagation; and (4) controlling for risk factors that have a high degree of influence and a large negative impact is an effective measure for blocking risk propagation across multilayer networks. This research lays an important foundation for risk propagation control in LEPs and contributes to the extension of the current theory of risk propagation in complex systems.

CuO with (0 0 1)-plane exposure efficiently induces peroxymonosulfate to form ≡Cu-OOSO3-intermediates directly oxidizing organic contaminants in water

Copper (Cu)/peroxymonosulfate (PMS) is a complex coupling system due to its multiple activation pathways with the formation of diverse radical and nonradical species. However, the effects of CuO with different plane exposures on the properties of the coupling system are not clear. In this research, Cu atom-terminated (001) plane-exposed CuO (CuO-10) is synthesized by a facile hydrothermal method using NH3·H2O as the structure directing agent for the first time. CuO-10 has the excellent property of inducing PMS to degrade bisphenol A (BPA) in water, and its reaction rate constant (k) reaches 14 times higher than that of commercial CuO with exposed (010) plane terminated by O atoms (CuO-C). Meanwhile, CuO-10 exhibits a wide pHinitial adaptability, and its BPA degradation exceeds 87% in the pH range of 3–9. Furthermore, compared with CuO-C/PMS, less radical and 1O2 are found in CuO-10/PMS oxidation system. Compared to the UV/PMS system, organic contaminants in CuO/PMS systems are easier to oxidize via an oxygen-atom-transfer mechanism. Therefore, the ≡Cu(II)-OOSO3- metastable intermediate is speculated to play an important role in the CuO/PMS activation process, which oxidizes organic contaminants directly through oxygen-atom-transfer and single-electron-transfer pathways. Furthermore, the CuO-10/PMS system is more likely to degrade organic pollutants through the oxygen-atom-transfer pathway than the CuO-C/PMS system. This study not only explores the influence of CuO crystal planes in efficiently inducing PMS activation but also provides new insights into the PMS activation process in the CuO/PMS oxidation system.

Galvanic corrosion based on wire beam electrode technique: progress and prospects

Abstract Galvanic corrosion is a type of localized corrosion that widely exists in all kinds of metal structures and causes severe damage, jeopardising the safety and dependability of equipment. This paper reviews the mechanism of galvanic corrosion and related influencing factors, including the material characteristics and geometric factors of the metal pair and environmental factors. As a unique surface testing technique, wire beam electrode (WBE) is widely used in various corrosion research fields represented by galvanic corrosion. On this basis, the research progress of the WBE technique in the field of galvanic corrosion is mainly reviewed from three perspectives. The experiments also proved that the WBE technique can well characterize the corrosion evolution progression and investigate the polarity reversal mechanisms. Finally, it is pointed out that the urgent scientific problems to be solved in the research of galvanic corrosion include: galvanic corrosion research in a variety of special environments; the mechanism of the galvanic couple reversal caused by the change of corrosion factors; the corrosion behavior of a complex coupling system composed of multiple metal connections; the development of corrosion prediction models.

Aeroelastic stability analysis of a pyrotechnic separation plate in subsonic airflow

Pyrotechnic separation devices are widely used in aerospace engineering. In separation process, the pyrotechnic separation device breaks into several parts, and the velocity of the separated structure changes intricately, which make the pyrotechnic separation device and the external airflow a complex fluid-structure coupling system. Since the stability of the structure is crucial for the safety, it is necessary to investigate the aerodynamic stability of the pyrotechnic separation device interacting with surrounding airflow. In the present study, the aeroelastic stability of a pyrotechnic separation plate in axial subsonic airflow is studied. The velocity of the residual plate is derived from the momentum theorem. The dynamic model of the pyrotechnic separation plate in subsonic airflow is established based on the linear potential flow theory and the von Kármán plate theory. The effects of the residual length, the pyrotechnic explosion strength and the separation velocity on the stability of the plate are investigated, and the vibration properties of the plate are discussed. From the results, the plate loses stability rapidly when it subjects to the explosion, and restores stability under the negative pressure. The displacement jumping phenomenon is observed. The amplitude of the plate in unstable period increases rapidly, which may cause damage to the structure.

Experimental Study on Coupled Motion of Floating Crane Barge and Lifted Module in Irregular Waves

Installation and decommissioning activities of offshore structures often applied a floating crane barge for a lifting operation. The excessive movement response of lifted module affected by the motion of floating crane barge in waves can increase a large amplitude. However, the coupled motions of a floating crane barge and lifted module are not easy to predict accurately due to the dynamic movement of a lifted module and the complex coupling system. The coupled motion responses of a floating crane barge and a lifted module during lifting operation were investigated based on time domain by experimental method in this study. The model tests are carried out at Manoeuvring and Ocean Basin of Indonesian Hydrodynamic Laboratory, BRIN. The experimental conditions include the load cases of without and with a load of lifted module in crane tip, and the lifting operation was evaluated under irregular wave conditions. The experimental results show in that the phenomena of shift resonant frequency for the dynamic responses are clearly observed on the coupled motion of multibody system. The dynamic oscillations of the lifted module have a significant effect on the motion response of the floating crane barge. And the hoisting of lifted module has an obstructed effect on the rolling motion of crane barge.

Modulational Instability and Position Controllable Discrete Rogue Waves with Interaction Phenomena in the Semi-Discrete Complex Coupled Dispersionless System

Modulational Instability and Position Controllable Discrete Rogue Waves with Interaction Phenomena in the Semi-Discrete Complex Coupled Dispersionless System

Kinematic Cooperative Optimization Control Algorithm for Underground Heavy-Load Robot

Because of complex and strong coupling system, the precision and adaptability of underground robots are greatly restricted. Based on the newly developed intelligent underground heavy-load robot which is still a gap to fill in current coal mine machinery, this paper proposes a new dynamic cooperative optimization control algorithm. Firstly, the complex and strongly coupled Multi-disciplinary Design Optimization system of the robot is decoupled into horizontal/vertical motion space with the idea of hierarchical target transmission, in order to weaken the strong coupling relationship between each hydraulic loop. Then, the spatial posture coefficient is introduced into main/auxiliary feedback control loop in horizontal/vertical motion space, to realize optimal collaborative control of each hydraulic loop under the premise of weak coupling between each control loop, so as to obtain the precise dynamic control signals of each hydraulic loop, and finally realize the optimal control of overall system for the robot. Lastly, the experiment and simulation verify that the DCO control algorithm presented in this paper can obtain better control results: The executive efficiency of the overall system is improved by 14.2%; The control flow is saved by 9.98%, and the executive precision meets the engineering and technical requirements. This paper provides a new efficient method and idea for the control system of intelligent underground heavy-load robots. Furthermore, the algorithm has reference value on development and design of high precise control system for the same kind of complex intelligent engineering machinery products.

Fault Diagnosis of Permanent Magnet Synchronous Motor Based on Stacked Denoising Autoencoder.

As a complex field-circuit coupling system comprised of electric, magnetic and thermal machines, the permanent magnet synchronous motor of the electric vehicle has various operating conditions and complicated condition environment. There are various forms of failure, and the signs of failure are crossed or overlapped. Randomness, secondary, concurrency and communication characteristics make it difficult to diagnose faults. Meanwhile, the common intelligent diagnosis methods have low accuracy, poor generalization ability and difficulty in processing high-dimensional data. This paper proposes a method of fault feature extraction for motor based on the principle of stacked denoising autoencoder (SDAE) combined with the support vector machine (SVM) classifier. First, the motor signals collected from the experiment were processed, and the input data were randomly damaged by adding noise. Furthermore, according to the experimental results, the network structure of stacked denoising autoencoder was constructed, the optimal learning rate, noise reduction coefficient and the other network parameters were set. Finally, the trained network was used to verify the test samples. Compared with the traditional fault extraction method and single autoencoder method, this method has the advantages of better accuracy, strong generalization ability and easy-to-deal-with high-dimensional data features.

NUMERICAL COUPLING ANALYSIS OF THE INFLUENCE OF BLOOD FLOW ON THE MECHANICAL RESPONSE FOR LIVER

As an important basis for determining the state of the liver, the mechanical responses are associated with many factors, and belong to a complex coupling system. Liver tissue has significantly complicated vascular channels. The vascular diameter, vascular deflection angle and vascular depth are defined as the key characteristic parameters. The influences of these parameters on the mechanical responses were analyzed. On the basis of the real mechanical parameters, the coupled numerical model of blood vessel, blood flow and liver tissue was established. The corresponding mechanical responses are obtained by utilizing the different vascular parameters. The effects of vascular parameters on the differences among the mechanical response difference and high strain modulus were analyzed. It was found that the blood vessels in the central area could reduce the liver mechanical response. The inner diameter parameter had main influences on the regions where the stain was more than 0.1. The mechanical difference is greater with larger inner diameter. The influences of vascular depth are greatest when the vascular depth was in the intermediate value, which would increase the liver mechanical responses. With the increment of vascular deflection angle, the liver mechanical response would also increase, and exceed the mechanical response without blood vessels. The findings after analyzing the influence of vascular parameters will provide a basis for the quantitative studies on the influence of blood vessels.

Research on Metro Power Supply System Based on New Green and Environmental Protection

Installing a ground-based super capacitor energy storage system in the subway will effectively recover the regenerative braking energy of the train, reduce the energy consumption of the system, and achieve the goal of green and environmental protection. Various substations, traction/braking trains and energy storage systems interact in real time through the traction network to form a complex multi-energy coupling system. Therefore, in order to improve the overall energy efficiency of the traction power supply system and reduce investment costs, this article proposes Comprehensive optimization method for power supply system parameters and energy storage system capacity configuration. Through research, it is found that compared to the optimization of a single energy storage system, comprehensive optimization effectively improves the energy-saving rate of the energy storage system when the investment cost is similar.