Dynamic System Model Research Articles

Steam Storage Rankine Cycle for Unutilized Applications in Distributed High-Temperature Waste Heat Recovery

In the light of increasingly valuable resources and a trend towards more efficient processes pushed by climate change, distributed Waste Heat Recovery (WHR) is an important element in the transformation of the energy supply. In recent years, however, WHR systems have often been optimized and implemented for steady-state applications. In this paper, dynamic system modeling and a Steam Rankine Cycle (SRC) pilot plant with 40 kWel are used to investigate applications unutilized thus far for the conversion of high-temperature waste heat into electricity using a shell boiler with 1.27 m3 of liquid water for short-term energy storage. In addition to experimental investigations of the storage system as an Uninterruptible Power Supply (UPS) and the input and output of +/−100% electrical power peaks for grid-assistive operation, a control concept for the use of volatile waste heat is developed from a model-based controller design up to a Model Predictive Control (MPC) with the help of a dynamic system simulation. Based on the validated model and experimental measurement data, outlooks for concrete applications with higher storage capacity and power are provided.

Establishment of the dynamic BTAP model and load-sharing analysis of herringbone gear planetary system with cracks

To reveal the influence of component cracks on the dynamic load-sharing characteristics of the herringbone gear planetary system (HGPS), a 55-DOF bending-torsional-axial-pendular (BTAP) nonlinear dynamic model of the system was constructed, taking into account parameters of different crack degrees (depth, angle, length), as well as factors such as manufacturing error (ME) and installation error (IE), time-varying mesh stiffness (TVMS), time-varying support stiffness, damping, and friction. The TVMS model of components with cracks was established using the cumulative potential energy method, and the mathematical quantification relationship between different crack parameters and TVMS was studied. Based on the theory of elastohydrodynamic lubrication (EHL), calculate the time-varying friction coefficient and friction force of each gear pair. Using the nonlinear elastic theory of rolling elements and raceways, the time-varying support stiffness of each component is obtained. Using the Runge-Kutta numerical integration method to solve the dynamic differential equations, and analyzed the load-sharing characteristics and sensitivity influence law of the system when the sun gear, planetary gear, and internal gear ring contain cracks respectively. Built a vibration test bench for the HGPS with cracks, and the experimental results were compared with the theoretical results. The results show that as the crack intensifies, the TVMS value decreases at the crack tooth. When the sun gear contains cracks, there will be obvious protruding excitation in the system’s load-sharing curve, and the internal meshing load-sharing characteristics are better than the external meshing load-sharing characteristics. At the same time, as the degree of cracks increases, the system load-sharing characteristics first improve and then deteriorate. At the same crack, as manufacturing and installation errors increase, the load-sharing characteristics of the internal and external meshing pairs deteriorate. When the internal gear ring contains cracks, the dynamic load-sharing coefficients of the internal and external meshing pairs of the system are 7.96 and 4.10, respectively, which have the highest impact on the dynamic load-sharing coefficient and sensitivity of the internal and external meshing pairs of the system. The experimental results are consistent with the theoretical results, verifying the correctness of the model.

Research on the Influence of Deep-Water Drilling Risers on Drillstring Motion Trajectory and Vibration Characteristics

The swing of the riser in deep-water drilling can significantly impact the drill string. In this study, we establish a riser model that considers the combined disturbance of periodic dynamic wind and wave loads. By coupling it with the drill string model, we develop a dynamic model for deep-water drilling systems. Through analyzing multiple sets of different drilling parameters, we examine displacements and impact forces at various positions along the drill string system. Specifically, our focus lies on velocity, acceleration, and rotational speed information of BHA. We investigate how WOB and rotational speed influence motion trajectory and vibration characteristics of the drill string within the dynamic model of deep-water drilling systems. Simulation results reveal slight differences in whirling trajectories between inside the riser and below mud line for the drill string. Rotational speed has a greater impact on the drill string compared to WOB; higher rotational speeds lead to increased collision forces between the drill string system and both riser and wellbore. Our findings identify specific combinations of WOB and rotational speed parameters that can stabilize drilling operations within dynamic models for deep-water drilling systems. These research results provide valuable insights for adjusting WOB and rotational speed parameters in deep-water drilling.

Dynamic analysis of aircraft towing slip-out system considering vertical wheel constraints

Abstract To analyze the vertical dynamic characteristics of the aircraft towing system under different constraints on the nose landing gear wheels of the aircraft during the towing slip-out mode, a dynamic model of the towing system considering the constraints between the clamping mechanism and the aircraft nose landing gear wheels was established based on the general towing system dynamic model. On this basis, an analysis was conducted to determine whether considering the aircraft wheel constraints affects the vertical vibration acceleration of the towing vehicle and the nose landing gear in low-speed (10 km/h) and high-speed (40 km/h) operating conditions. With the consideration of constraints at both ends of the aircraft wheels, the vertical acceleration of the towing vehicle's center of mass increased by 153% and 172% at low speed and high speed, respectively, compared to not considering the aircraft wheel constraints. Additionally, with the consideration of constraints at both ends of the aircraft wheels, the vertical acceleration of the nose landing gear's center of mass decreased to 20% and 57% at low speed and high speed, respectively, compared to not considering the aircraft wheel constraints. An analysis of the vertical vibration acceleration of the towing vehicle under different wheel constraint conditions found that the RMS value of the vertical vibration acceleration of the towing vehicle's center of mass was minimized when the clamping angles of the clamping mechanism to the nose landing gear wheels were 63° and 64°, respectively. Under this clamping angle, the influence of the clamping forces at both ends of the clamping mechanism on the vertical vibration acceleration of the towing vehicle was minimal. The research results provide valuable reference for the direct constraints between the clamping mechanism and the nose landing gear wheels in the aircraft towing slip-out system.

Impact of climate change on cayenne pepper availability in Sleman District, Yogyakarta with dynamic system modelling

The availability of cayenne pepper in Sleman District is influenced by cayenne pepper production factors and demand of consumers. Climate change greatly affects the demand and supply of cayenne pepper. The value of Mean Absolute Percentage Error (MAPE) in the dynamic system model is 5.18%. The simulation of Cayenne Pepper availability scenarios in the Sleman District that was made scenarios by rule of the Government to increase of planting area by 20 ha per year. The other scenarios were changing a temperature increase 1 degree Celsius and increase of 2 degrees Celsius. The result of the research showed that first scenario made the supply of cayenne pepper decrease 15 %/year. The second scenario made the supply of cayenne pepper will be decrease up to 30 %/year in 2024-2030. It means that the temperature change can influence significantly with the supply of cayenne pepper in Sleman District. Moreover, the supply has not been fulfil to the very high demand by consumers of households, Industries and Horeca (Hotel, restaurant and catering) in this district.

Design of a dynamic and robust recommender system based on item context, trust, rating matrix and rating time using social networks analysis

Collaborative filtering recommender systems type have been increasingly used in e-commerce sites both to facilitate users' decision-making and increase sales. On the one hand, the open and interactive nature of recommender systems makes them vulnerable to shilling attacks, and on the other hand, given that most recommender systems are used in dynamic environments, and this issue generates incremental data over time. One of the main obstacles of this type of recommender systems is the inability to model the dynamic behavior of users and the incremental flow of data, as well as the vulnerability to shilling attacks. Therefore, classic models do not have the necessary ability to provide suitable recommendations to the user and also to detect shilling attacks dynamically. The objective of this study was to address this gap by designing a dynamic and robust recommender system model against shilling attacks. This model was based on item context, trust, users' rating and users' rating time, and it benefits from the social networks analysis of users and items to suggest @N top items to the target user, and had a dynamic and increasing property over time and robust against shilling attacks. Finally, to assess the performance and robustness of the recommender system to shilling attacks, 4850 different tests have been performed without shilling attacks and under three average, random, and bandwagon attacks. To validate the proposed model, the results of the tests have been compared with similar methods such as TRACCF, TOTAR and T&TRS using the evaluation criteria of Precision, Recall, F1, MAE and RMSE.The results depicted that the proposed method, due to finding users and similar items in communities created by social networks, causes a reduction in the number of predicted items that are not liked by the user (FP) and the number of unpredicted items that are liked by the user (FN) and finally the F1 criterion (which is a combination of Precision and Recall criteria) performs better than the comparison methods. Also, this method is robust against the shilling attacks by detecting fake profiles and ignoring them in the recommendation process, and the evaluation criteria before and after shilling attacks show this.

DNA origami signal amplifiers for biosensing and as a model dynamic system for electrochemical impedance spectroscopy

DNA origami signal amplifiers for biosensing and as a model dynamic system for electrochemical impedance spectroscopy

Analyzing the Finnish University funding system through system-based simulation

This research explores the suitability of system-based simulation analysis for higher education (HE) policy-planning. A dynamic system model of the Finnish university funding system covering bachelor-level students is presented. The results show that the model captures the nature of the current funding system, which can be considered a zero-sum game, where the funding an individual university can only be improved at the cost of others. Based on the simulations, it seems that in the Finnish HE system increasing the importance of target time graduations in the funding model would favour the small universities. The generalizability of the used model´s and methods’ suitability outside the Finnish context is evaluated and discussed.

WATER RESOURCES MANAGEMENT MODEL BASED ON REGIONAL DEVELOPMENT: CASE STUDY OF MAGETAN REGENCY, INDONESIA

<p><strong>Background.</strong> The need for water in Magetan Regency, Indonesia, continues to increase along with regional development. <strong>Objective. </strong>To identify the condition of the water balance and water critical index in Magetan Regency; and forming a regional development-based water management model in Magetan Regency. <strong>Methodology. </strong>Formation of a water management model based on regional development, both demographically and regional economic development (agriculture, livestock, fisheries, industry, and tourism), and the environment (river and lake maintenance). This study uses water availability data from seven watersheds. The water management model uses a dynamic system model, with an analysis coverage throughout the Magetan Regency area. The annual water balance of Magetan Regency shows that the water balance and water critical index of Magetan Regency are in near critical condition. Integrated water management is needed to avoid critical water conditions in Magetan Regency in the future. <strong>Results. </strong>Based on the results of model simulations with the application of policy simulations, the water balance in Magetan Regency during the period 2016 to 2030 is still in a near critical condition, but critical water conditions only occur during the 2018-2020 period. <strong>Implications.</strong> Critical water conditions in the future can be avoided by implementing policy scenarios. The policy scenarios include: (1) reforestation, planting 500,000 tree seedlings each year, (2) maintenance of rivers and lakes twice a year, (3) construction of a reservoir with a capacity of 5000 m<sup>3</sup> each year. However, water availability is still fluctuating because the main factor for water availability is rainfall. <strong>Conclusion.</strong> the policy scenario is proven to be able to increase the availability of water in Magetan Regency.</p>

A life-cycle dynamic wear degradation model of planetary gear systems

An accurate prediction model for surface wear in planetary gear systems is essential to decipher wear fault mechanisms and facilitate model-driven failure prognosis. A high-fidelity dynamic wear model relies on the appropriate characterization and updating strategy of the tooth macro-geometry, contact parameters and dynamic load. A geometrically adaptive-loaded tooth contact analysis (GA-LTCA) method is proposed to “bridge” wear morphology and dynamic behaviours. The finite element method and run-to-failure test are adopted to verify the GA-LTCA method and wear prediction model, respectively. Based on the proposed wear model, the life-cycle wear characteristics and the updating strategy of wear geometry are investigated. Owing to the consideration of the micro-cycle of the contact stress and geometrical updating, the predicted wear profile exhibits a desirable agreement with experimental results. The tooth profile deviation vector should be updated more frequently than the finite element model of worn gears. Only the finite element grid of the sun-planet gear pair should be updated because the wear of the sun-planet is much more serious than that of the ring-planet. Numerical results indicate the potential of the proposed high-fidelity model for digital twin-based wear prediction and life cycle failure prognosis.

Dynamic modeling of spur gear system considering the coupling effect between bearing deflection and gear mesh stiffness

Bearing deflection has a direct impact on the mesh condition of gear systems via the center distance of the gear pair and corner contact. These factors need to be considered to accurately model the time-varying mesh stiffness and dynamic responses of gears. To address this issue, a spatial coordinate conversion is used to obtain the instantaneous spatial position of the gear pair under the bearing deflection. The tooth pair separation distance is derived through the geometric relationship analysis to model the corner contact effect. A dynamic model is established which employs a step-to-step time integration algorithm that considers the coupling effect between bearing deflection and time-varying mesh stiffness to obtain the dynamic response of the spur gear system. The simulation results of the proposed model show good agreement with the experimental results which demonstrate that the proposed model enables a proper analysis of the influence of bearing deflection on gear mesh behavior. This study provides an original dynamic model for analyzing the dynamic performance of the gear system considering the influence of bearing deflection.

Simulasi Sistem Dinamis Produksi Tape Ketan

<p><em>This study aims to find out what factors shape the production system of the sticky tape business, and find out how to model the dynamic system of the sticky tape business for the next 10 months. The research data were obtained from interviews with respondents who owned sticky tape businesses. Based on the research results, there are three sub-systems in the sticky tape production system, namely the raw material sub-system and raw material costs, the production sub-system and the sales value (receipt) sub-system, income and business feasibility. Dynamic system modeling in the sticky tape business for the next 10 months is carried out using a scenario approach without improvement and scenario with improvement. The average income per month in the scenario without improvement is Rp. 12,996,269, - and a scenario with an improvement of Rp. 17,200,732,-,- with a feasibility value in the scenario without improvement of 1.84 and the scenario with improvement of 2.01.</em></p><p><em>Keywords : Simulation, Dynamic, Business, Sticky, Tape</em></p>

Dynamic theory and experimental testing in ipsilateral offset dual-motor excitation system

This paper addresses unbalanced trajectories of dual-motor vibrating screens by proposing a dynamic theory and experimental testing. First, based on the Lagrange equation, the dynamic model of ipsilateral offset dual-motor excitation system is established. Subsequently, the steady response is worked out by solving the differential equation of motion of the vibrating body. Then, the synchronization condition and synchronization stability criterion of the system are determined employing the small parameter method and the Routh–Hurwitz criterion. Numerical analysis methods are given to reveal the relationship between structural parameters and synchronization characteristics of the vibration system. Moreover, an mechanical–electric coupling model is developed to study dynamic characteristics. The results demonstrate that synchronization condition can be described with capture torque and difference of output torque between motors. The synchronization ability is enhanced by improving installation distance of the motors. Additionally, increasing angle β or decreasing angle θ of the motors is in favor of optimization of centroid trajectory; swing oscillation of the box can be controlled by adjusting the main inclination angle of motors; in such a condition, equilibrium of motion trajectory of system is enhanced. Finally, the validity method for designing vibrating screen is verified through theoretical calculations, simulation analysis, and experiments.

Retracted: Dynamic Modeling and Analysis of Micro-Video Teaching System Based on Cloud Computing in College English Teaching

Retracted: Dynamic Modeling and Analysis of Micro-Video Teaching System Based on Cloud Computing in College English Teaching

Nuclear power technologies development: Historical track and future evolution

Understanding the evolution mechanism of nuclear power technology development is crucial for predicting its future path and devising a sound strategic plan. While classical economic theory provides the relationships between of technological progress and economic growth on specific assumptions, it is necessary to explore the evolutionary mechanism of technology development without prior assumptions. Furthermore, given the various forms of technological development, including basic research, patent technology, and product trade, the intricate relationship between them and economic growth necessitates further elucidation. This study aims to shed light on the evolutionary process of nuclear power technology development by constructing complex systems of “Science-Technology-Product-Economic growth,” applying Bayesian dynamic system modeling methods to establish the evolutionary equation of the complex systems and revealing the historical track and future evolution of nuclear power technology development. This study offers a fresh perspective to unravel the evolution of nuclear power technology development, facilitates a nuanced characterization of energy technology progress, and assists in developing an optimized learning curve for energy technology.

Rub-impact dynamic analysis of a dual-rotor system with bolted joint structure: Theoretical and experimental investigations

Large gas turbines often utilize dual-rotor structures to improve efficiency. To facilitate manufacture and maintenance, the large rotor systems are typically constructed by connecting components made from different materials together through the bolted joint. In this work, a dynamic model of a dual-rotor system with bolted joint included in the high-pressure (HP) rotor is established based upon the finite element theory of Timoshenko beam element, as well as taking into account the bearing forces and fixed-point rubbing fault. To evaluate the influence of rubbing faults on the dynamic behavior of a dual-rotor system, this study analyzed the response characteristics of the rotor under the cases of the LP rotor and the HP rotor subjected to the rubbing fault, respectively. In order to further reveal the effect of bolted joint structure on the system response while rubbing fault occurs, piecewise linear bending stiffness is also considered in this study. The nonlinear vibration responses of the bolted joint dual rotor-bearing system are studied through numerical simulation. Effect of rotor–stator contact stiffness and the occurrence of rubbing faults at the low-pressure (LP) rotor and the HP rotor are investigated through frequency-amplitude curves, waterfall diagrams, time-domain responses, and bending stiffness of the bolted joint. The results indicate that the presence of rubbing faults, whether occurring at the LP rotor or the HP rotor, leads to a decrease in the critical speed. Furthermore, under a rubbing fault, the bending stiffness of the bolted joint enters the stiffness softening region earlier and exhibits a wider range, which is exacerbated with increased contact stiffness. This phenomenon is considered one of the main causes of system response instability. Finally, the experimental studies are carried out on a bolted joint dual-rotor test rig to validate the numerical simulation results.

Self-tuning PID feedback control method for magnetic suspension active vibration isolation system with parameters uncertainty

A self-tuning PID (Proportion-Integral-Derivative) control method based on the adaptive mechanism was proposed for the magnetic suspension active vibration isolation system with the characteristics of nonlinear, time-varying, and model parameter uncertainty. The controller identified the controlled object parameters online and solved the controller parameters in real time. To test the effectiveness of the proposed method, a six degree-of-freedom (DOF) magnetic suspension active vibration isolation system was designed and built. The six DOF dynamic model of the vibration isolation system with uncertain model parameters was derived for control. Experiments were carried out and compared with the control effects of the tradition PID control and cascade PID control algorithm. The experimental results show that the proposed self-tuning PID controller has more outstanding practicality and effectiveness in solving the model parameter uncertainty problem compared with the existing studies at home and abroad, and it also proves that the control method has a good isolation effect on the wide band disturbances.

Solar driven liquid desiccant dehumidification system: Measurements and annual system simulations

Liquid desiccant air conditioning (LDAC) systems are used for dehumidification of air to low dew point temperatures. In the presented study a TRNSYS model of a LDAC unit is developed and validated with laboratory measurements. This model is coupled with a solar thermal system that provides heating water for the regeneration process. With this model dynamic annual system simulations can be carried out to simulate the dehumidification of a building. The solar fraction is evaluated for various infiltration rates of the building and solar collector areas with an internally cooled as well as an adiabatic absorption process.The simulation results reveal that high solar fractions of 70% to 81% can be achieved when dimensioning the solar thermal system to cover the regeneration heat demand on a good summer day. This is due to the good correlation of solar irradiance and dehumidification load. Without internal cooling of the absorption process (adiabatic conditions), the solar fraction is reduced by about 10percent points for the same size and operating conditions.

Nonlinear vibration characteristics of virtual mass systems for wind turbine blade fatigue testing

Abstract. The biaxial fatigue test of wind turbine blades is helpful to shorten the test time and is more suitable for the actual operating conditions. Adding tuning masses to the blade is a common method for blade uniaxial testing at present, and its purpose is to adjust the load distribution in one direction of the blade. However, the tuning masses on the blade will affect the load distribution in the direction of the blade flap-wise and edge-wise at the same time in the biaxial test, so the concept of “virtual masses” is proposed to realize the decoupling of the load distribution in the biaxial test. Due to the limitation of the size of the virtual mass mechanism and the complex motion trajectory of the blade, the actual inertial effect provided by the virtual masses is different from the ideal situation, which will affect the resonance characteristics of the test system and the load distribution of the blade. Therefore, in order to evaluate the effect of the nonlinear effect introduced by the virtual masses on the resonance characteristics of the test system and the blade load distribution, the equivalent dynamic model of the bladed virtual mass test system was established by using the Lagrange method. Then, the nonlinear effects of blade amplitude and virtual mass installation parameters on the test system are obtained by a numerical method. Then, based on the nonlinear vibration theory, the approximate nonlinear amplitude–frequency characteristics of the test system are obtained, that is, the resonance frequency of the test system will decrease with the increase in the blade amplitude. Through the simulation analysis of two blades over 80 m in length, the applicability of the theoretical method is verified. It can be seen from the simulation results of the simulated uniaxial test that larger amplitudes of the blade and shorter connection rods will reduce the resonance frequency of the test system. When the vibration amplitude at the excitation point is the same, a lower resonance frequency results in a smaller load distribution level, that is, the area which is actually fully tested will be reduced. In the biaxial simulation test, the resonance frequency of the test system will be further reduced because the virtual masses will be affected by the coupled motion in both directions at the same time. Furthermore, the introduction of an external mechanism of the virtual mass will also cause deformation of the envelope of the blade biaxial trajectory, which will further affect the load distribution of the blade. This work explores the nonlinear influence of virtual masses on the actual fatigue test. The theoretical analysis is helpful to provide the basis and reference for the preliminary preparation work of the test organization, including adjusting the tuning mass scheme, adjusting the load distribution and selecting the appropriate excitation equipment.

Nonlinear Dynamic Analysis of a Spur Gear Pair System with Wear Considering the Meshing Position

In this paper, a nonlinear dynamic model of a parallel shaft gear system consisting of two involute spur gears is developed to investigate the coupling effect between the gradual surface wear of gear teeth over time and nonlinear dynamic characteristics. A uniform wear model that accounts for how the volumetric wear of the gear teeth affect their meshing position, backlash, and stiffness is proposed. Additionally, a nonlinear dynamic model with six degrees of freedom is described that considers friction, time-varying gear backlash, and time-varying meshing stiffness. The proposed model significantly changes the mesh stiffness, not only in terms of value but also in terms of contact ratio. Furthermore, the nonlinear dynamic characteristics of the gear system vary significantly. It is found that the gradual wear of gear teeth affects the meshing position and further has a significant impact on the nonlinear dynamic characteristics of the spur gear system. This paper provides a basis for studying the nonlinear dynamic characteristics of the spur gear system as it experiences the gradual wear of teeth over time.