Third-order Model Research Articles

A Reduced-Order Model of Lithium–Sulfur Battery Discharge

This paper examines the problem of modeling lithium–sulfur (Li-S) battery discharge dynamics. The importance of this problem stems from the attractive specific energy levels achievable by Li-S batteries, which can be particularly appealing for applications such as aviation electrification. Previous research presents different Li-S battery models, including “zero-dimensional” models that neglect diffusion while using the laws of electrochemistry to represent reduction–oxidation (redox) rates. Zero-dimensional models typically succeed in capturing key features of Li-S battery discharge, including the high plateau, low plateau, and dip point visible in the discharge curves of certain Li-S battery chemistries. However, these models’ use of one state variable to represent the mass of each active species tends to furnish high-order models, with many state variables. This increases the computational complexity of model-based estimation and optimal control. The main contribution of this paper is to develop low-order state-space model of Li-S battery discharge. Specifically, the paper starts with a seventh-order zero-dimensional model of Li-S discharge dynamics, analyzes its discharge behavior, constructs phenomenological second- and third-order models capable of replicating this behavior, and parameterizes these models. The proposed models succeed in capturing battery discharge behavior accurately over a wide range of discharge rates. To the best of our knowledge, these are two of the simplest published models capable of doing so.

Influence of Fused Deposition Modeling Process Parameters on Constitutive Model of Hyperelastic Thermoplastic Polyurethane.

Thermoplastic polyurethanes (TPUs) are suited for fused deposition modeling (FDM) of parts that require high levels of flexibility and strength. Predicting the deformation of TPU parts produced using FDM may be difficult, especially under large deformations, as their constitutive models depend on the printing process parameters. The lack of understanding led to the absence of constitutive models for TPU parts produced using FDM. This work aims to identify accurate hyperelastic constitutive models. Six groups of uniaxial tensile specimens were produced using FDM. These groups were made with variations in two process parameters, which were infill geometry and extrusion nozzle temperature. Infill geometries either corresponded to a zero-deposition angle (wall-only) or an infill deposition of ±45° raster angle (infill-only). It was determined that a third-order Mooney-Rivlin constitutive model can accurately describe these six groups. A finite element analysis (FEA) of the experiments using the proposed constitutive models resulted in limited errors for all groups. The proposed approach was verified through a combination of experiments and FEA of FDM TPU components undergoing large deformation.

Design of a Hybrid Excitation Controller for Multimachine Infinite Bus Power System

Abstract: A significant portion of contemporary power networks is still conventional power system that uses synchronous generators to produce electricity. Conventional power systems are operated under various operating situations by means of excitation systems and turbine-governor systems of synchronous generators. This paper proposes an excitation controller for synchronous generators (SGs) in a multi machine infinite bus (MMIB) power system through combining the idea of the nonlinear backstepping (BS) and partial feedback linearization methods. The model of third-order has been linearized into a second-order linearized system that is independent of the rotor angle which is unmeasurable, using the partial feedback linearization approach. In this case, the BS is applied to the partially linearized system. The idea is to find a control input that drives the system towards a desired behaviour while ensuring the transformed states converge to their target values. Lastly, simulation research is carried out on an MMIB system to analyse how the proposed control mechanism (BS-PFLC) performs in stabilizing the system under a three phase-to-ground fault conditions of power networks. To demonstrate the effectiveness of the BS-PFLC, an existing excitation controller has been used to compare the performance.

Numerical PMM test in finite depth

This study conducted a numerical planar motion mechanism (PMM) test for a containership, considering the effects of finite depth. An OpenFOAM-based computational fluid dynamics (CFD) approach was employed to conduct the simulations. Before conducting a series of numerical computations, uncertainty analysis for the grid size and time step was performed to ensure the reliability of the computational results. Two PMM tests, static drift and pure yaw, were conducted, and the results were validated against experimental data. The comparison demonstrated good agreement between forces, moments, and hydrodynamic coefficients when compared with both experimental and other computational results. Furthermore, a comparison between a first- and second-order combination model and a first- and third-order combination model revealed that the latter showed better alignment with experimental data in deep water, while the former performed better in shallow water, emphasizing the role of crossflow. This study contributes to understanding the differences in maneuvering performance between deep and shallow water conditions.

Adaptive backstepping control for nonlinear CAVs platoon with input delays and disturbances

In recent years, the platoon control of connected autonomous vehicles (CAVs) has attracted a lot of attention in intelligent transport research. The third-order nonlinear vehicle dynamics model, due to its practicality, has been adopted in many research projects. In platoon control, controller input delays and disturbances are the significant issues that cannot be ignored. To this end, this paper investigates the cooperative control problem of third-order nonlinear CAVs platoon with controller input delays and unknown external disturbances. First, the neural network (NN) is used to approximate external disturbances with unknown bounds. Then, with the help of Pade approximation, a new variable is introduced to deal with the input delays. Subsequently, a corresponding compensation system is constructed based on the introduced variable. At last by using backstepping approach, a distributed adaptive control strategy based on vehicle-to-vehicle (V2V) communication is proposed in this paper. Additionally, Lyapunov functions and the uniformly ultimately bounded stability theorem are used to demonstrate the stability of the closed-loop systems, and the effectiveness of the control strategy is demonstrated by a simulation example.

Advanced parameter estimation for lithium-ion battery model using the information sharing group teaching optimization algorithm

Accurate battery modeling is crucial for optimizing the performance and safety of Lithium-ion batteries (LiBs), particularly in applications such as electric vehicles and smart grids. This paper introduces the Information Sharing Group Teaching Optimization Algorithm (ISGTOA), a novel human-based metaheuristic algorithm designed to estimate the 21 parameters of third-order Equivalent Circuit Model (ECM) for LiBs. Unlike existing methods, ISGTOA effectively manages the increased complexity of a model through advanced group teaching strategies and sophisticated information-sharing mechanisms inspired by classroom dynamics. We validated the effectiveness of ISGTOA using two distinct datasets—High Dynamic Profile (HDP) and Urban Dynamometer Driving Schedule (UDDS)—across various LiB chemistries (NCA and NMC) and temperature conditions (−5 °C, 25 °C and 45 °C). The results demonstrate that ISGTOA achieves superior parameter estimation accuracy and convergence speed compared to established and recent optimization methods such as TLBO, TLSBO, AISA, MTBO, and DTBO. Specifically, ISGTOA attained a minimum RMSE of 8.357 mV with rapid convergence and high stability in the HDP dataset and minimized RMSE to 10 mV within ten iterations at both 25 °C and 45 °C in the UDDS dataset. Additionally, ISGTOA exhibited high efficiency (up to 97.75 %) under varying thermal environments. This work not only introduces a novel algorithm for complex battery modeling but also sets the stage for future advancements in real-time battery management systems, emphasizing the importance of robust, versatile, and efficient parameter estimation techniques.

Active Support Pre-Synchronization Control and Stability Analysis Based on the Third-Order Model of Synchronous Machine

When traditional grid-forming converters directly participate in the grid-connected operation of the power grid, due to the lack of a pre-synchronization control system, the voltage amplitude and initial phase on both sides of the grid-connected point will deviate, resulting in voltage and current distortion during grid-connected mode. An active support phase-locked loop free pre-synchronization control strategy based on the third-order model of a synchronous generator is proposed to address the grid-connected problem of the grid-forming converter mentioned above. First, a model of active support control with frequency integral feedback at small signal levels was constructed. The root locus method was employed to examine how system parameters affect the stability of the active support control system. Second, by adding phase pre-synchronization controllers and amplitude pre-synchronization controllers to the active frequency loop and excitation voltage loop of the third-order model, it was ensured that the frequency, phase, and voltage amplitude of the unit are consistent with the power grid, achieving a fast and smooth grid-connected mode of the unit. Finally, by using a DC source to simulate all types of new energy power generation equipment, the active support pre-synchronization control system based on the three-order model of synchronous generator is built in the MATLAB/Simulink simulation environment, and the accuracy and effectiveness of the control strategy in this paper is verified.

Research on the strategy of cruise control system for urban traffic jam assistant

This paper proposes a hierarchical cruise control strategy that can adapt to urban traffic scenarios. Firstly, the perception layer defines a target selection strategy by using a novel trapezoidal dangerous area. Then, the upper controller contains speed follow mode and distance follow mode. An improved PI mode with integral separation and saturation terms is developed to achieve the desired speed following control, a safe distance mode via variable time headway is developed to facilitate the safe and smooth distance following control. The lower controller is designed based on feedforward and PI feedback. Finally, the experimental results demonstrate that the strategy can effectively select suitable target vehicles in complex urban scenarios. With the improved safe distance model and the third-order Bessel actuator response delay model, the strategy exhibits adaptability and stability. This study offers valuable suggestions and guidance for designing and applying the cruise control strategy for urban traffic scenarios.

Optimal Cascaded Terminal Sliding Mode Controller for third-order DC motor model

Applying Terminal Sliding Mode Control (TSM) for a third-order system is always challenging. Most of the cases, authors use a Cascaded type of TSM (CTSM) to control those systems. But with two separate phases of sliding mode the final results may not be optimal. This article presents the Optimal Cascaded TSM controller applying for a third-order DC motor model to enhance the convergence time of the system by avoiding twisting phenomenon. The simulation was taken in Matlab environments.

Adaptive Nonsingular Fast Terminal Sliding Mode Control for Shape Memory Alloy Actuated System

Due to its high power-to-weight ratio, low weight, and silent operation, shape memory alloy (SMA) is widely used as a muscle-like soft actuator in intelligent bionic robot systems. However, hysteresis nonlinearity and multi-valued mapping behavior can severely impact trajectory tracking accuracy. This paper proposes an adaptive nonsingular fast terminal sliding mode control (ANFTSMC) scheme aimed at enhancing position tracking performance in SMA-actuated systems by addressing hysteresis nonlinearity, uncertain dynamics, and external disturbances. Firstly, a simplified third-order actuator model is developed and a variable gain extended state observer (VGESO) is employed to estimate unmodeled dynamics and external disturbances within finite time. Secondly, a novel nonsingular fast terminal sliding mode control (NFTSMC) law is designed to overcome singularity issues, reduce chattering, and guarantee finite-time convergence of the system states. Finally, the ANFTSMC scheme, integrating NFTSMC with VGESO, is proposed to achieve precise position tracking for the prosthetic hand. The convergence of the closed-loop control system is validated using Lyapunov’s stability theory. Experimental results demonstrate that the external pulse disturbance error of ANFTSMC is 8.19°, compared to 19.21° for the comparative method. Furthermore, the maximum absolute error for ANFTSMC is 0.63°, whereas the comparative method shows a maximum absolute error of 1.03°. These results underscore the superior performance of the proposed ANFTSMC algorithm.

Battery SOC estimation based on UHIF algorithm for third-order circuit models

Battery SOC estimation based on UHIF algorithm for third-order circuit models

The shadows of quintessence non-singular black hole

In 2022, the Event Horizon Telescope (EHT) collaboration has reported the first observations of Sagittarius A*(SgrA*). Applying the EHT observational results, we find out constraints on non-singular Hayward parameter of regular dark energy black hole. Considering these constraints and different thin disk accretion, we present a detailed investigation into influence of different dark energy and Hayward parameters on shadows from non-singular Hayward black holes. In the first second-order attenuation function model, corresponding shadow radius and peak for observed intensity from direct image decrease with increasing dark energy parameter and Hayward parameter. However, for the lensing ring and photon ring, corresponding peak become bigger as dark energy parameter increase in case of fixed Hayward parameter. In the second third-order attenuation function model, significantly different from model 1, above two rings completely overlay on the direct image, resulting in two distinct peaks in the observed intensity. As increase of Hayward and dark energy parameters, the difference between the two peaks decreases, and shadows and observed intensity decrease. In the final inverse trigonometric function attenuation model, the result shows corresponding lensing ring as well as photon ring can be distinguished within the superposition region, and the superposition region becomes larger. With the increase of the dark energy parameter, the shadow radius exhibits a decreasing trend, while observed intensity increases. However, with the increase of the Hayward parameter, both decreases. Compared with the first two models, the shadow radius becomes smaller, but the observed intensity becomes larger, making the bright ring wider and brighter. Therefore, different accretion models and non-singular Hayward parameters can give rise to interesting and distinguish characteristic for the black hole shadow and rings.

Process Parameters Optimization and Numerical Simulation of AlCoCrFeNi High-Entropy Alloy Coating via Laser Cladding.

The use of laser cladding technology to prepare coatings of AlCoCrFeNi high-entropy alloy holds enormous potential for application. However, the cladding quality will have a considerable effect on the properties of the coatings. In this study, considering the complex coupling relationship between cladding quality and the process parameters, an orthogonal experimental design was employed, with laser power, scanning speed, and powder feed rate as correlation factor variables, and microhardness, dilution rate, and aspect ratio as characteristic variables. The experimental data underwent gray correlation analysis to determine the effect of various process parameters on the quality of cladding. Then, the NSGA-II algorithm was used to establish a multi-objective optimization model of process parameters. Finally, the ANSYS Workbench simulation model was employed to conduct numerical simulations on a group of optimized process parameters and analyze the change rule of the temperature field. The results demonstrate that the laser cladding coating of AlCoCrFeNi high-entropy alloy with the single pass is of high quality within the determined orthogonal experimental parameters. The powder feed rate exerts the most significant influence on microhardness, while laser power has the greatest impact on dilution rate, and scanning speed predominantly affects aspect ratio. The designed third-order polynomial nonlinear regression model exhibits a high fitting accuracy, and the NSGA-II algorithm can be used for multi-objective optimization to obtain the Pareto front solution set. The numerical simulation results demonstrate that the temperature field of AlCoCrFeNi high-entropy alloy laser cladding exhibits a "comet tail" phenomenon, where the highest temperature of the molten pool is close to 3000 °C. The temperature variations in the molten pool align with the features of laser cladding technology. This study lays the groundwork for the widespread application of laser cladding AlCoCrFeNi high-entropy alloy in surface engineering, additive manufacturing, and remanufacturing. Researchers and engineering practitioners can utilize the findings from this research to judiciously manage processing parameters based on the results of gray correlation analysis. Furthermore, the outcomes of multi-objective optimization can assist in the selection of appropriate process parameters aligned with specific application requirements. Additionally, the methodological approach adopted in this study offers valuable insights applicable to the exploration of various materials and diverse additive manufacturing techniques.

RESILIENCE OF GREEN BUILDING SUPPLY CHAIN: CAPABILITIES, RISKS AND INFLUENCE MECHANISM

ABSTRACT Green buildings are more effective in saving energy and reducing carbon dioxide emissions than conventional buildings. However, the long-term development of green buildings depends heavily on the resilience of their supply chain. This study examines how capability factors (readiness, response, and recovery) and risk factors (technological, organizational, and environmental) interact to influence the resilience of the green building supply chain, using a third-order partial least squares structural equation model. The results indicate that response capability and technological risk significantly impact resilience, while readiness capability mitigates organizational and environmental risks. The study suggests three strategies to enhance supply chain resilience: strengthening readiness capabilities and increasing resistance to organizational or environmental risks. The findings provide green building project managers with practical insights and tools to make informed decisions that improve supply chain resilience.

Characterization and optimization of waste Cucurbita maxima moschata lashes for biomass composite applications

In this paper, 5 % sodium hydroxide solution, mixed 20 % acetic acid and 5 % sodium chlorite solution, and 5 % silane coupling agent solution were successively used to soak the waste pumpkin (Cucurbita maxima moschata) lashes. Subsequently, FTIR, XRD, thermogravimetric analysis and other experimental methods were used to comprehensively characterize the properties of the discarded pumpkin lashes. On this basis, this work prepared cement mortar specimens with unadulterated pumpkin lashes, adulterated raw pumpkin lashes, and adulterated modified pumpkin lashes, and their residual mechanical properties were investigated after exposure to elevated temperatures. The experimental results indicate that the chemical modification utilized in this paper can increase the cellulose content of pumpkin lashes as well as reduce the proportion of amorphous components, and thus, improve the tensile strength, crystallinity index, grain size, thermal stability, and surface roughness of the samples. Meanwhile, the chemical treatment process can effectively reduce the water absorption and density of pumpkin lashes. The calculation outcomes of our thermal kinetics study showed that the apparent activation energies corresponding to the main pyrolysis stage of the treated pumpkin lashes were significantly enhanced. The one-dimensional diffusion model and the second-order model could better characterize the pyrolytic mechanism of the raw pumpkin lashes, while the mechanism was closer to the third-order model because of the chemical modification. Finally, the addition of chemically modified pumpkin lashes reduced the mass loss rate of cement mortar specimens at elevated temperatures while clearly increasing the residual strength of the specimens at 300 and 400 °C compared to those with referential pumpkin lashes.

Dynamic Analysis and Optimization of the Coupling System of Vibrating Flip-Flow Screen and Material Group

Vibrating flip-flow screens (VFFSs) provide an effective solution for deeply screening moist and fine-grained minerals, and an accurate dynamic model of VFFSs is critical for its dynamic analysis and optimization, thereby improving the vibration stability and symmetry of VFFSs. In this paper, uniaxial tension, uniaxial compression, plane tension, and shear stress relaxation experiments were conducted on screen panel samples to illustrate that the third-order Ogden model and the generalized Maxwell model can accurately describe the hyperelasticity and viscoelasticity of screen panels. Then, the coupling method of finite element and discrete element was adopted to establish the simulation model of the screen panel and material group coupling system, and the dynamics of the coupling system under different loading conditions were explored. Finally, the dynamic model of the coupling system of VFFSs mass, screen panel, and material group was proposed, and the non-dominated sorting genetic algorithm II was applied to optimize the system’s dynamic response. The results reveal that the use of optimized shear springs can reduce the relative amplitude change rate of the main and floating screen frame by 44.30% while maintaining the periodic motion of the VFFSs under operation conditions, greatly enhancing the stability of the VFFSs system.

The advantages behind the efforts of performing higher-order calibration methods – A case study

BackgroundAcross numerous investigations delved into second- and higher-order data, an undoubted finding emerges: models based on such data can effectively exploit the second-order advantage. However, whether further benefits can be achieved by modeling data of higher dimensions remains a subject of inquiry. In this regard, a prevailing question emerges in third-order data-based applications regarding the fundamental need to increase the data dimension and, hence, the data analysis complexity. This study aims to provide meaningful evidence to support the advantages inherent in employing third-order calibration methods despite the associated efforts, such as instrumentation and data analysis complexity. ResultsThis study compares the analytical performance achieved using a third-order calibration method with those obtained from most of the possible second-order calibration approaches derived from the same dataset. This work delves into the structural properties of the data, modeling limitations, and analytical characteristics associated with each model. Additionally, it includes a comprehensive statistical comparison of the models based on their recovery performance. First, the outcomes demonstrate the importance of capitalizing on all available chemical information and harnessing the full potential of data to maximize its benefits. Moreover, the results provide evidence that asserts the fact that third-order calibration methods bring the opportunity to increase the number of analytes that can be simultaneously determined, notwithstanding the need for more tedious experimental protocols, specialized instrumentation (sometimes), and quite complex data analysis. Significancethis research marks the first extensive comparison of third-order data calibration models with possible second-order calibration methods. Moreover, this work pioneers the incorporation of highly challenging non-multilinear data. The advancements detailed in this study emphasize the advantages of third-order data acquisition, notwithstanding the need for more tedious experimental protocols, specialized instrumentation (sometimes), and quite complex data analysis.

A new transient phenomenon caused by active current dynamics of grid-following converters during severe grid faults

Existing transient stability analysis of grid-following (GFL) converters mainly focuses on the dynamics of the phase-locked loop (PLL), while current loop dynamics are usually neglected due to their faster response than PLL. However, this article reveals that active current may not be able to track its reference quickly during severe grid faults even with high current loop bandwidth, which leads to a non-negligible impact on the transient stability of GFL converters. Furthermore, this article discusses the intrinsic mechanism of why active current cannot track its reference quickly during severe grid faults and establishes a refined third-order transient synchronization model that offers a more accurate assessment of transient stability during severe grid faults than the conventional second-order model.

Development of a γ-Al2O3-Based Heterogeneous Fenton-like Catalyst and Its Application in the Advanced Treatment of Maotai-Flavored Baijiu Wastewater

Heterogeneous Fenton technology was employed for the advanced treatment of Maotai-flavored Baijiu wastewater. Novel catalysts were prepared by loading different active ingredients (Mn, Fe, and Cu) on γ-Al2O3 using an impregnation method. The effects of active ingredient, reaction time, initial pH, H2O2 dosage, catalyst dosage, and other factors on the reaction were examined. The properties of the new catalysts were analyzed using BET analysis, XPS, and SEM. Moreover, the mechanisms of Fenton-like oxidation and its reaction kinetics were explored through experiments and analyses including GC–MS and intermediate active species scavenging by tertiary butyl alcohol (TBA) and/or para-benzoquinone. The results revealed that the most effective removal of organic matter was achieved with a Mn-Fe/Al (2:1 wt%) catalyst dosage of 30 g/100 g water, pH of 5.0, H2O2 dosage of 0.3 g/L, and reaction time of 60 min; the effluent COD value was 12 ± 1 mg/L, and the degradation rate was 65.7 ± 3%, approximately 14% higher than that of the conventional Fenton catalyst under similar conditions; moreover, the catalytic efficacy remained high after seven cycles. Kinetic analysis indicated that the heterogeneous Fenton oxidation reaction followed a third-order kinetics model, with R2 = 0.9923 and K = 0.0006 min−1.

A new pair of block techniques for direct integration of third-order singular IVPs

This paper proposes a new pair of block techniques (NPBT) for the direct solution of third-order singular initial-value problems (IVPs). The proposed method uses a polynomial and two intermediate points to approximate the theoretical solution of third-order singular IVPs, resulting in a reasonable approximation within the integration interval. The method's essential features, including stability and convergence order, are analyzed. The proposed NPBT method is improved by using an embedding-like strategy that allows it to be executed in a variable step size mode in order to gain better efficiency. The effectiveness of the proposed method is assessed using various model problems. The approximate solution provided by the proposed NPBT method is more accurate than that of the existing methods utilized for comparison. This efficient solution positions NPBT as a good numerical method for integrating third-order singular IVP models in the fields of applied sciences and engineering.