Dynamic Behavior Research Articles

Mathematical Modeling of the Transmission Dynamics of Gumboro Disease

Gumboro disease is a viral poultry disease that causes immune suppression on the infected birds leading to poor production, mortality, and exposure to secondary infections, hence a major threat in the poultry industry worldwide. A mathematical model of the transmission dynamics of Gumboro disease is developed in this paper having four compartments of chicken population and one compartment of Gumboro pathogen population. The basic reproduction number Rog is derived, and the dynamical behaviors of both the disease-free equilibrium (DFE) and endemic equilibrium are analyzed using the ordinary differential equation theory. From the analysis, we found that the system exhibits an asymptotic stable DFE whenever Rog<1 and an asymptotic stable EE whenever Rog>1. The numerical simulation to verify the theoretical results was carried out using MATLAB ode45 solver, and the results were found to be consistent with the theoretical findings.

Simulation and electrification of a conventional vehicle into a battery electric vehicle for sustainability mobility

ABSTRACT This work explores converting a conventional 1996 Honda Civic Coupe into a battery-electric vehicle (BEV). A simulation model is developed to analyze the vehicle’s dynamic behavior under various conditions, including changes in vehicle mass and road slope. The system specifications are detailed based on a 50 kW AC induction motor, controller, battery, and battery management system. The battery comprises 2,376 NCR18650B cells with a capacity of 23 kWh based on inverter requirements. Energy consumption is simulated using the New European Driving Cycle (NEDC), resulting in 1.69 kWh to travel 10.8 km. Autonomy is estimated at 147 km. The environmental impact of 19.2 g CO2/km is calculated. The results illustrate the change in maximum speed, acceleration, and distance traveled based on changes in mass and slope. It is concluded that mass variation has a lesser impact on performance than road slope. The work demonstrates the feasibility of converting a conventional vehicle to a BEV with comparable dynamic capabilities using currently available technology. Future development plans include constructing a battery prototype, electrifying the vehicle, and incorporating instrumentation for validation.

Research and Application of the Simulation Method for Product Development Process Based on System Dynamics

Product development is a complex process involving intricate components, dynamics and constantly evolving internal and external environments, as well as numerous influencing factors. In order to accurately simulate and predict the effectiveness of the development process, this paper proposes a system dynamics simulation method based on information maturity. Different types of development processes are simulated, and the discussion includes the impact of activity information correlation, information evolution coefficient, start time, and other parameters on the dynamic behavior of the process. This study examines a specific mold development process as a case study to validate the method’s feasibility, accurately predicting the duration and cost of the process. It also investigates dynamic fluctuations resulting from uncertain events such as changes in customer demand and resource shortages. The method provides support for process optimization and resource scheduling.

Analyses of Pile-Supported Structures with Base Isolation Systems by Shaking Table Tests

The dynamic behavior of a pile-supported structure with a base isolator was investigated by using 1 g shaking table model tests considering soil–structure interaction (SSI). The emphasis was placed on evaluating the effect of the with/without developed base isolator on the dynamic behavior of end-bearing piles and structures. The experiment was performed through sweep tests and sinusoidal wave tests. As a result of the tests, the developed base isolator was found to effectively reduce the structure’s resonant frequencies and damped the response acceleration under resonance frequencies. According to sweep tests, the base shear force of the pile-supported structure system tends to decrease as the relative density of the soil increases during resonance. It showed that the base isolator tends to reduce significantly the response acceleration of not only the rigid-based structure but also the pile-supported structure. It was shown that although the isolated superstructure recorded large horizontal displacements, piles experienced reduced horizontal displacement and bending moments, regardless of soil conditions.

Transient dynamic stress behavior analysis of the axial flow pump as turbine at part loads

To explore the structural dynamic characteristics of the impeller and shaft system of the axial flow pump as turbine, the variation law of impeller transient equivalent stress, deformation, and the impeller and shaft system mode are analyzed by the transient fluid-structure interaction method. Findings indicate that the equivalent stress is centralized at the blade root around the hub and tends to decrease as it moves towards the shroud. The maximum equivalent stress at 1.0Qbep and 1.1Qbep is 1.26 times and 2.0 times higher than that at 0.8Qbep. Blade deformation is significantly influenced by flow rate. The maximum deformation of the blade at 1.0Qbep and 1.1Qbep is 1.6 times and 3.6 times higher than that at 0.8Qbep. The impeller and shaft system with prestress in dry mode has an average natural frequency of the first 10 orders that is 16.7 Hz higher than without prestress. However, with the fluid adding mass and flow damping, the average natural frequency of the first 10 orders of the impeller and shaft system in wet mode is reduced by 278.08 Hz compared with dry mode. In fact, the impeller and shaft system of the axial flow pump as turbine is not prone to vibration.

New exact solutions and related dynamic behaviors of a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation

New exact solutions and related dynamic behaviors of a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation

Analysis of the Dynamical Properties of Discrete Predator-Prey Systems with Fear Effects and Refuges

This paper examines the dynamic behavior of a particular category of discrete predator-prey system that feature both fear effect and refuge, using both analytical and numerical methods. The critical coefficients and properties of bifurcating periodic solutions for Flip and Hopf bifurcations are computed using the center manifold theorem and bifurcation theory. Additionally, numerical simulations are employed to illustrate the bifurcation phenomenon and chaos characteristics. The results demonstrate that period-doubling and Hopf bifurcations are two typical routes to generate chaos, as evidenced by the calculation of the maximum Lyapunov exponents near the critical bifurcation points. Finally, a feedback control method is suggested, utilizing feedback of system states and perturbation of feedback parameters, to efficiently manage the bifurcations and chaotic attractors of the discrete predator-prey model.

Stimulus-Induced Dynamic Behavior Regulation of Flexible Crystals through the Tuning of Module Rigidity.

Introducing dynamic behavior into periodic frameworks has borne fruit in the form of flexible porous crystals. The detailed molecular design of frameworks in order to control their collective dynamics is of particular interest, for example, to achieve stimulus-induced behavior. Herein, by varying the degree of rigidity of ditopic pillar linkers, two isostructural flexible metal-organic frameworks (MOFs) with common rigid supermolecular building bilayers were constructed. The subtle substitution of single (in bibenzyl-4,4'-dicarboxylic acid; H2BBDC) with double (in 4,4'-stilbenedicarboxylic acid; H2SDC) C-C bonds in pillared linkers led to markedly different flexible behavior of these two MOFs. Upon the removal of guest molecules, both frameworks clearly show reversible single-crystal-to-single-crystal transformations involving the cis-trans conformation change and a resulting swing of the corresponding pillar linkers, which gives rise to Flex-Cd-MOF-1a and Flex-Cd-MOF-2a, respectively. Strikingly, a more favorable gas-induced dynamic behavior in Flex-Cd-MOF-2a was verified in detail by stepwise C3H6/C3H8 sorption isotherms and the corresponding in situ powder X-ray diffraction experiments. These insights are strongly supported by molecular modeling studies on the sorption mechanism that explores the sorption landscape. Furthermore, a consistency between the macroscopic elasticity and microscopic flexibility of Flex-Cd-MOF-2 was observed. This work fuels a growing interest in developing MOFs with desired chemomechanical functions and presents detailed insights into the origins of flexible MOFs.

Dynamic behavior of rack vehicle-track(rack) coupled system on super-large-slope bridges

Rack railways are mainly used in mountainous areas, where inevitably, super-large-slope bridge structures appear. The dynamic behavior of the rack vehicle-track(rack) coupled system on super-large-slope bridge is rarely studied. To address this issue, a dynamic interaction model for rack vehicle-track(rack)-bridge system is established by considering the detailed dynamic meshing behavior of gear-rack and the dynamic contact behavior of the wheel-rail. On this basis, the gear-rack meshing force and the wheel-rail contact force of rack vehicles are studied under lines with varying slopes, and the dynamic behavior of the rack vehicle and the track-bridge system with a slope of 250‰ is further analyzed. Research results show that as the slope line increases, the gear and rack meshing force increases, but the wheel-rail vertical force decreases. Concurrently, the stability index of the vehicle changed considerably, and the stability of the vehicle decreases substantially. The maximum values of the vibration acceleration of the vehicle body and bridge are 0.4 m/s2 and 0.5 m/s2, respectively, meeting the requirements of the relevant standards for the vibration acceleration of the vehicle body and bridge. Further analysis reveals that the vibration of rack is mainly affected by the meshing force, and the vibration of the bridge is mainly affected by the wheel-rail force. These research results can offer a theoretical basis for the pre-design, post-operation, and maintenance of rack railways.

Dynamical Behavior and Numerical Simulation of an Influenza A Epidemic Model with Log-Normal Ornstein–Uhlenbeck Process

Dynamical Behavior and Numerical Simulation of an Influenza A Epidemic Model with Log-Normal Ornstein–Uhlenbeck Process

Unveiling the transition of tumbling and tank-treading dynamics of star-shaped polyelectrolytes in shear flow by modulating the solution's dielectric properties.

The effects of the solution's dielectric properties on the conformation and dynamics of star-shaped polyelectrolytes in shear flow are investigated using a hybrid simulation method coupling multi-particle collision dynamics and molecular dynamics. The simulation results showed that by modulating the dielectric properties of the solution, star-shaped polyelectrolytes showed a three-step dynamic behavior transition from tumbling to tank-treading to tumbling dynamics under shear flow. The analysis indicated that this distinct transition in dynamics could be attributed to the uneven distribution of counterions induced by shear on the chain, resulting in a change in the polyelectrolyte conformation and degree of segmental alignment in arms. These findings contribute to a comprehensive understanding of the non-equilibrium dynamics of star-shaped polyelectrolytes in shear flow and offer a viable approach for controlling the dynamic behavior of star-shaped polyelectrolytes by adjusting the dielectric properties of the solution.

Weak signal detection method based on nonlinear differential equations

With the rapid development of computer network technology, it is often necessary to collect weak signals to collect favorable information. The development of signal detection technology is ongoing; however, various issues arise during the detection process. These issues include low efficiency and a high signal noise threshold. However, many problems will be encountered in the process of detection. In order to solve these problems, the nonlinear chaos theory is introduced to detect signals, and the simulation experiments of weak pulse signals and weak partial discharge signals are carried out respectively. The experimental results showed that the detection effect was remarkable in the quasi periodic state, and it had a good detection effect for weak pulse signals. At a signal-to-noise ratio of -25 dB, double coupling system, two-way ring coupling system, and single ring coupling system displayed detection success rates exceeding 98%. Meanwhile, the detection success rate of the strong coupling system was only 12%. Even at a noise signal ratio as low as -40 dB, the dual coupling system still maintained a detection success rate above 80%. The simulation results of partial discharge signal detection showed that there was a high fluctuation only at 2 ms, and the rest was basically stable at about 0 V, indicating that the system had a strong suppression effect on Gaussian white noise. When comparing the simulation results of the detection of the new chaotic system and the double coupling system, it was found that the new chaotic system has a superior impact in detecting weakly attenuated partial discharge signals. Through analysis of the system’s dynamic behavior, the research confirms its rich dynamic characteristics and sheds light on the reasons for phase state mutation and missed detection. The noise system is utilized for comparing the performance of various systems, with the goal of enhancing the system’s detection capability.

Investigating Non-Newtonian Fluid Behavior in Hydrocyclones Via Computational Fluid Dynamics

Expert researchers examine complex patterns of pressure, viscosity, and velocity in a CFD study of viscoelastic food inside hydrocyclones to obtain a detailed grasp of particle behavior and fluid dynamics. Velocity profiles show how fluids and particles flow through the hydrocyclone in complex ways, while pressure distributions show where high and low pressure is found, regions that are critical for maximizing separation efficiency. Furthermore, the analysis of viscosity fluctuations clarifies the intricate relationship between fluid rheology and flow dynamics, providing information on how food's viscoelastic characteristics affect particle trajectories and separation efficiency. Utilizing this comprehensive examination, scientists hope to optimize the design and functioning parameters of the hydrocyclones, which will in turn improve the efficacy and efficiency of particle separation procedures in viscoelastic food solutions. This will ultimately lead to improvements in food processing technology and product quality. Researchers look into the impact of geometric elements on flow patterns and separation efficiency in addition to these characteristics, such as hydrocyclone size and inlet configurations. Additionally, they investigate how different operating parameters, such rotational speed and flow rate, affect how well the hydrocyclone handles viscoelastic food items. Through the integration of these complex analyses, researchers hope to create all encompassing models that can precisely forecast and optimize the behavior of viscoelastic food flows inside hydrocyclones, opening the door to improved process control and food sector product quality.

Dynamic stress prediction for a Pump-Turbine in Low-Load Conditions: Experimental validation and phenomenological analysis

To meet the increasing demand for higher flexibility in hydropower, an operating range extension in an existing hydroelectric powerplant is considered. To this end, the dynamic flow and structural behavior of the low-head pump-turbine is investigated in turbine mode in partial load and deep partial load conditions, to evaluate the feasibility of this flexibilization due to the increased high cycle fatigue damage. In a first step, different numerical simulation approaches that combine fluid dynamics and structural dynamics are applied and compared to in-situ dynamic strain and pressure measurements on the impeller. As a result, the modelling requirements for a numerical workflow that leads to unmatched accuracy in predicting the broad-band dynamic stresses of deep partial load are identified. In a second step, the operating-point-dependent fatigue crack initiation spots are identified based on dynamic stresses. Herein, the emergence of an additional dominant critical spot near the blade leading edge is observed, which is unexpected for low-head pump turbines. Thanks to the detailed numerical flow and structural analyses, the root cause for the dynamic stress concentration is studied and the emergence of the new critical spot is understood. It turns out in deep partial load, that the main source of pressure oscillations on the impeller blade surfaces is the vortex-dominated flow detachment zone around the blade leading edge, which, in combination with the geometry of the investigated impeller, translates into the main stress oscillations. The results of this work were later used to extend the operating range of the hydroelectric powerplant from initially 25% to 100% power output to now 0% to 100%.

Empowering College Communities through Digital Innovation: The Uni-Safe App's Role in Combating Bullying

The bullying in a college is major issue in today’s educational setting, negatively affecting student’s mental health and their overall health. This research paper presents an innovative approach implemented in a college for combating bullying with the aid of digital technology platforms. The technological intervention is the creation of app called Uni-Safe, using flutter framework renowned for its dynamic nature, versatile and responsive behaviour. Uni-Safe consists of various features such as user-friendly interface, real-time reporting features, and a confidential platform for students to raise their problems without having concern for identity revelation. The application was deployed to college environments and post analysis was continuously done to assess its effectiveness in resolving the issue. Though the app significantly reduced complexities and enhanced overall wellbeing of college dynamic still there presents a disparity as it is focusing on one college only instead of broader spectrum of educational institutions that could give higher insight into societal well-being.

Understanding Unemployment Dynamics and Labor Market Behavior in South Korea: Employing Mccall Dynamic Programming Approach

This paper investigates labor market dynamics from 1990 to 2023 using the McCall dynamic programming search model, offering insights into individual decision-making, economic conditions, and policy implications. Convergence trends in wage predictions underscore the model's reliability, highlighting its utility for predicting wage outcomes over time. The policy implications emphasize the importance of balancing the duration of unemployment and the considerations of the wage level in policy design. In light of the analysis, policymakers and employers should consider the trade-offs between unemployment duration and wage level when designing policies and compensation practices. The insights provide guidance for policymakers, employers, and job seekers in navigating the complexities of the job market.

Bifurcation Analysis of a Holling–Tanner Model with Generalist Predator and Constant-Yield Harvesting

In this paper, we introduce constant-yield prey harvesting into the Holling–Tanner model with generalist predator. We prove that the unique positive equilibrium is a cusp of codimension 4. As the parameter values change, the system exhibits degenerate Bogdanov–Takens bifurcation of codimension 4. Using the resultant elimination method, we show that the positive equilibrium is a weak focus of order 2, and the system undergoes degenerate Hopf bifurcation of codimension 2 and has two limit cycles. By numerical simulations, we demonstrate that the system exhibits homoclinic bifurcation and saddle–node bifurcation of limit cycles as the parameters are varied. The main results show that constant-yield prey harvesting and generalist predator can lead to complex dynamic behavior of the model.

Dynamic Analysis of the Bolted Joint Structure with Interval Uncertainties

This paper investigates the dynamic influence of joint interfaces in bolted joint structures subjected to uncertain-but-bounded parameters. Firstly, applying the thin layer elements (TLE) represents the contact interfaces with nonuniform stiffness distribution. The stochastic model updating method is employed to identify the uncertain parameters of TLE. Secondly, the Legendre interval method (LIM) is applied to calculate the natural frequencies of bolted lap joints with uncertain parameters. By introducing the elastic modulus of TLE as interval vectors, relations between the natural frequencies and uncertain parameters could be analyzed using the LIM. Furthermore, the dependence of the dynamic response on TLE parameters can be established based on the modal superposition principle. Considering the influence of uncertain parameters, an uncertain acceleration frequency response surrogate function (UAFRSF) is proposed to predict the dynamic behavior and qualitatively analyze the parameter sensitivity of the bolted lap joints. The elastic modulus of TLE in different contact regions is selected as the interval variable. The acceleration frequency responses of the bolted lap joints under uncertain parameters are investigated. Compared with MCs simulations with 200 samples and Chebyshev interval method results, the effectiveness of the proposed method for solving the uncertain acceleration frequency response of bolted lap joints is verified. This research will provide theoretical support for improving the design of aero-engine joint structures.

Learning the effective order of a hypergraph dynamical system.

Dynamical systems on hypergraphs can display a rich set of behaviors not observable for systems with pairwise interactions. Given a distributed dynamical system with a putative hypergraph structure, an interesting question is thus how much of this hypergraph structure is actually necessary to faithfully replicate the observed dynamical behavior. To answer this question, we propose a method to determine the minimum order of a hypergraph necessary to approximate the corresponding dynamics accurately. Specifically, we develop a mathematical framework that allows us to determine this order when the type of dynamics is known. We use these ideas in conjunction with a hypergraph neural network to directly learn the dynamics itself and the resulting order of the hypergraph from both synthetic and real datasets consisting of observed system trajectories.

Optical injection effects in electrically pumped semiconductor nano-laser arrays

A theoretical analysis is performed on the response of electrically pumped nano-laser arrays to external optical injection. The response to both continuous wave and modulated optical injection is explored. Continuous wave injection is shown to excite several varieties of dynamical behaviour in the array elements including regular dynamics and quasi-periodic behaviour. The strength of the optical injection, the frequency detuning between the injected light and the target laser, and the magnitude of the Purcell spontaneous emission enhancement factor are shown to markedly affect the dynamics. When subject to modulated optical injection, the effects of frequency detuning and optical injection strength are the focus of attention. It is shown that the elements of the array subject to modulated optical injection exhibit oscillatory behaviour over broad regimes determined by the optical injection strength and the frequency detuning.