In this paper, a class of discontinuous neutral-type neural networks (NTNNs) with proportional delays is considered. The targets of the paper are to study the problem of periodic solutions and fixed-time (FXT) stabili...In this paper, a class of discontinuous neutral-type neural networks (NTNNs) with proportional delays is considered. The targets of the paper are to study the problem of periodic solutions and fixed-time (FXT) stabilization of the addressed neural networks. In order to complete the targets, based on set-valued map, differential inclusions theory, coincidence theorem and Hölder inequality technique, some new proportional delay-dependent criteria shown by the inequalities are derived. Based on the fact of the existence of solution, further by applying the FXT stability lemmas and equivalent transformation, the zero solution of closed-loop system achieves FXT stabilization and the corresponding settling-times are estimated. Some previous related works on NTNNs are extended. Finally, one typical example is provided to show the effectiveness of the established results.展开更多
This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two...This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two dynamic parameters.Specifically,a set of auxiliary variables is first introduced through state transformation.These variables combine the original system states and the two introduced dynamic parameters,facilitating the closed-loop system stability analyses.Then,the two dynamic parameters are delicately designed by utilizing the Lyapunov method,ensuring that all the closed-loop system states are globally fixed-time stable.Compared with existing results,the“explosion of complexity”problem of backstepping control is avoided.Moreover,the two designed dynamic parameters are dependent on system states rather than a time-varying function,thus the proposed controller is still valid beyond the given fixedtime convergence instant.The effectiveness of the proposed method is demonstrated through two practical systems.展开更多
In this paper,we consider the fixed-time stabilization control problem of quantum systems modeled by Schrodinger equations.Firstly,the Lyapunov-based fixed-time stability criterion is extended to finitedimensional clo...In this paper,we consider the fixed-time stabilization control problem of quantum systems modeled by Schrodinger equations.Firstly,the Lyapunov-based fixed-time stability criterion is extended to finitedimensional closed quantum systems in the form of coherence vectors.Then for a two-level quantum system with single control input,a non-smooth fractional-order control law is designed using the relative state distance.By integrating the fixed-time Lyapunov control technique and the bi-limit homogeneity theory,the quantum system is proved to be stabilized to an eigenstate of the inherent Hamiltonian in a fixed time.Comparing with existing methods in quantum system control,the proposed approach can guarantee stabilization in a fixed time without depending on the initial states.展开更多
As well-known,prescribed-time stabilizing design faces the need of using time-varying high gains which escape to infinity as time approaches the desired instant.In the presence of measurement noise,the corresponding s...As well-known,prescribed-time stabilizing design faces the need of using time-varying high gains which escape to infinity as time approaches the desired instant.In the presence of measurement noise,the corresponding state response is also significantly amplified that leads to the lack of robustness in the closedloop implementation.In order to eliminate this drawback,the implicit Euler discretization of the closed-loop in question is recently developed in where desired robustness properties are conserved beyond the prescribedtime interval while also bounded state dynamics are ensured in the presence of measurement noise.Along this line,stabilizing prescribed-observer-based output feedback algorithms and their digital implementation are reviewed.For tutorial value,the underlying state feedback and observer designs are recalled side by side in continuous-and discrete-time perspectives,followed by the desired output feedback design.Open problems,calling for future investigation,conclude the review.展开更多
This paper is dedicated to fixed-time passivity and synchronization for multi-weighted spatiotemporal directed networks.First,to achieve fixed-time passivity,a type of decentralized power-law controller is developed,i...This paper is dedicated to fixed-time passivity and synchronization for multi-weighted spatiotemporal directed networks.First,to achieve fixed-time passivity,a type of decentralized power-law controller is developed,in which only one parameter needs to be adjusted in the power-law terms;this greatly decreases the inconvenience of parameter adjustment.Second,several fixed-time passivity criteria with LMI forms are derived by using a Gauss divergence theorem to deal with the spatial diffusion of nodes and by applying the Hölder’s inequality to dispose rigorously the power-law term greater than one in the designed control scheme;this improves the previous theoretical analysis.Additionally,the fixed-time synchronization of spatiotemporal directed networks with multi-weights is addressed as a direct result of fixed-time strict passivity.Finally,a numerical example is presented in order to show the validity of the theoretical analysis.展开更多
This paper presents an adaptive multi-agent coordination(AMAC)strategy suitable for complex scenarios,which only requires information exchange between neighbouring robots.Unlike traditional multi-agent coordination me...This paper presents an adaptive multi-agent coordination(AMAC)strategy suitable for complex scenarios,which only requires information exchange between neighbouring robots.Unlike traditional multi-agent coordination methods that are solved by neural dynamics,the proposed strategy displays greater flexibility,adaptability and scalability.Furthermore,the proposed AMAC strategy is reconstructed as a time-varying complex-valued matrix equation.By introducing a dynamic error function,a fixed-time convergent zeroing neural network(FTCZNN)model is designed for the online solution of the AMAC strategy,with its convergence time upper bound derived theoretically.Finally,the effectiveness and applicability of the coordination control method are demonstrated by numerical simulations and physical experiments.Numerical results indicate that this method can reduce the formation error to the order of 10^(-6)within 1.8 s.展开更多
In this paper,a class of discontinuous Cohen-Grossberg neural networks with timevarying delays is considered.Firstly,under the extended Filippov differential inclusions framework,the problem of periodic solutions of t...In this paper,a class of discontinuous Cohen-Grossberg neural networks with timevarying delays is considered.Firstly,under the extended Filippov differential inclusions framework,the problem of periodic solutions of the considered neural networks with more relaxed conditions imposed on the amplification functions is analyzed by using set-valued mapping and Kakutani's fixed point theorem,which has rarely been used to study such problem.Secondly,the fixed-time synchronization of the error system of the considered neural networks is also investigated by designing a novel control strategy,which can improve not only the previous ones with sign function greatly,but also can reduce the chattering phenomenon.Finally,two numerical examples are presented to further illustrate the validity of the obtained results.展开更多
This paper is dedicated to solving the problem of adaptive fuzzy fault-tolerant tracking control for a class of time-varying high-order uncertain nonlinear systems.The motivation comes from how to construct a compact ...This paper is dedicated to solving the problem of adaptive fuzzy fault-tolerant tracking control for a class of time-varying high-order uncertain nonlinear systems.The motivation comes from how to construct a compact set large enough in which the approximation of any unknown continuous function by a fuzzy logic system(FLS)is effective while compensating sensor/actuator faults and external disturbances.The difficulty is to verify the boundedness of closed-loop signals on the constructed compact set and to reduce the number of the variables of the fuzzy membership functions as many as possible.By a new lemma,linear/nonlinear terms are introduced in adaptive laws to dominate unknown residual terms.With adding a power integrator method,a unified fault-tolerant controller is designed to drive the tracking error to converge to a small compact set of the origin within a fixed time,regardless of whether the system suffers from faults and disturbances.Superior to the existing results,in the presence of time-varying factors the scheme of this paper clarifies the logical relationship between the compactness of the approximation and the boundedness of the state variables.Finally,the application of control strategy is demonstrated by numerical/practical examples.展开更多
Flexibly interconnected distribution networks(FIDN)offer improved operational efficiency and operational control flexibility of power distribution systems through DC interconnection links,and have gradually become the...Flexibly interconnected distribution networks(FIDN)offer improved operational efficiency and operational control flexibility of power distribution systems through DC interconnection links,and have gradually become the main form of distribution networks.Aiming at the impact of constant power loads and converter transmission power variations in FIDN system stability,this paper presents an impedance reshaping based stability analysis and stabilization control to enhance the stability of the interconnected system and improve the system’s dynamic load response capability.Firstly,a small-single based equivalent impedance model of FIDN system,which consists flexibly interconnected equipment,energy storage,PV units,and constant power loads,is presented,and the total output and input impedance of the DC distribution network are derived.Secondly,the impacts of constant power loads and transmission power variations on the small-signal stability of FIDN system are analyzed through Nyquist stability curves using the impedance ratio criterion.Then,an impedance reshaping-based stability enhancement strategy for the FIDN system is proposed,which can significantly improve the system stability under the operating conditions of constant power loads and transmission power variations.Finally,a MATLAB/Simulink simulation model is built and tested.The results demonstrate that the proposed impedance reshaping strategy effectively mitigates voltage dips,surges,and DC bus fluctuations,shortens transient responses under power variations,and enables rapid stability recovery with reduced voltage drop during severe AC sags.展开更多
To enhance the stabilization performance of red-bedded mudstone subgrade soil,a novel synergistic technique combining microorganisms and quicklime was developed and evaluated through comprehensive physical,mechanical,...To enhance the stabilization performance of red-bedded mudstone subgrade soil,a novel synergistic technique combining microorganisms and quicklime was developed and evaluated through comprehensive physical,mechanical,and microstructural analyses.The results demonstrated that quicklime significantly improved the pore structure by increasing the proportion of pores with diameters in the range of 0.5-50μm,thereby facilitating microbial migration and calcium carbonate precipitation.The proposed technique effectively enhanced cementitious material production(cementation rate:6.83%),unconfined compressive strength(1.63 MPa),and resistance to swelling and deformation(swelling rate:0.26%).The observed synergistic effect can be attributed to two primary mechanisms.First,quicklime promotes soil particle agglomeration,resulting in larger pores that enable bacterial mobility and provide optimal microenvironments for microbial activity.Second,during curing,quicklime undergoes hydration and ionization,releasing Ca^(2+)and OH^(−)ions.The Ca^(2+)ions serve as calcium sources for microbial-induced carbonate precipitation,while the OH−ions react with SiO_(2)and Al_(2)O_(3) to form hydrated gels that develop a skeletal soil structure.Meanwhile,the exothermic reaction further accelerates calcium carbonate deposition within the agglomerated pores.展开更多
Rapid industrialization in China has caused significant environmental challenges,particularly heavy metal pollution from mine tailings.Toxic heavy metals such as lead(Pb),cadmium(Cd),and mercury(Hg)are released during...Rapid industrialization in China has caused significant environmental challenges,particularly heavy metal pollution from mine tailings.Toxic heavy metals such as lead(Pb),cadmium(Cd),and mercury(Hg)are released during the processing of mining wastewater and leaching of mine tailings.Owing to their excellent physicochemical properties,cementitious materials are widely used for the solidification/stabilization of heavy metals,immobilizing heavy metals via two distinct mechanisms.Physically,their favorable characteristics,including high mechanical strength,low porosity,and durable matrix,create effective barriers.Chemically,the alkaline environment facilitates the precipitation of metal hydroxides/carbonates.Conversely,hydration products(calcium silicate hydrate gels and ettringite)contribute to immobilization through adsorption and physical encapsulation.This study systematically investigated the migration mechanisms of heavy metal contaminants in mine tailings;further,it elucidated the multifaceted immobilization pathways of cementitious materials,which involve synergistic adsorption,precipitation,and encapsulation by hydration products combined with homocrystalline substitution.A comprehensive analysis indicated that cementitious materials significantly reduced the mobility and bioavailability of heavy metals.Nonetheless,their long-term stability and potential environmental impact require further investigation.This study aims to provide theoretical support for environmental management and sustainable resource utilization,and to explore the broader application potential of cementitious technology for heavy metal stabilization,thereby establishing a theoretical foundation for future research on heavy metals in low-cement solidified/stabilized tailings.展开更多
Lithium-rich layered oxides(LRLOs)are promising cathode materials due to their high specific capacity,energy density,and operating voltage.However,their performance is hindered by the limited redox activity of transit...Lithium-rich layered oxides(LRLOs)are promising cathode materials due to their high specific capacity,energy density,and operating voltage.However,their performance is hindered by the limited redox activity of transition metals,leading to oxygen redox instability,oxygen release,and capacity degradation.To address these issues,we propose an innovative lattice-oxygen modulation(LOM)strategy that incorporates Mn^(3+)and Ti^(4+)into the Li_(1.2)Cr_(0.3)Mn_(0.4)Ti_(0.1)O_(2) system,effectively mitigating Cr migration,stabilizing oxygen redox reactions,and reinforcing structural integrity.This results in improved electrochemical performance,as demonstrated by a 56.5 mAh g^(−1) increase in initial discharge capacity to 364.2 mAh g^(−1),with 71.3%capacity retention after 30 cycles,reflecting a 20.2%improvement in cycling stability.Density functional theory(DFT)calculations confirm enhanced Cr redox reversibility and reduced oxygen evolution,further strengthening structural stability.These synergistic effects highlight the pivotal role of the LOM strategy in optimizing both electrochemical performance and structural integrity,offering a scalable pathway to improve capacity and cycling stability in lithium-rich cathodes.展开更多
This paper explores the adaptive exponentially designated-time stabilization issue via event-triggered feedback for a kind of uncertain high-order nonlinear systems.The motivation mainly comes from the following two c...This paper explores the adaptive exponentially designated-time stabilization issue via event-triggered feedback for a kind of uncertain high-order nonlinear systems.The motivation mainly comes from the following two challenges:the undesired singularity problem arising from infinite control gains at the prescribed-time instant,the effective trade-off between the control amplitude and the triggering duration.The goal is to build an event-triggered mechanism comprising a skillful triggered rule alongside a time-dependent threshold.Utilizing the designed control strategy,the solutions'existence and the prevention of Zeno phenomenon are successfully guaranteed by using a new transformation equipped with a time-varying function and redesigning the continuous state-feedback dominance approach with an array of integral functions involving embedded sign functions.Better than existing prescribed-time methods,our approach not only ensures that state variables converge to a small compact set before a designated time and stay there henceforth,and converge to the origin exponentially,but also ensures that the controller continuously works on the whole-time horizon.Two illustrative examples are given to show the effectiveness of the devised scheme.展开更多
Unconfined Compressive Strength(UCS)is a key parameter for the assessment of the stability and performance of stabilized soils,yet traditional laboratory testing is both time and resource intensive.In this study,an in...Unconfined Compressive Strength(UCS)is a key parameter for the assessment of the stability and performance of stabilized soils,yet traditional laboratory testing is both time and resource intensive.In this study,an interpretable machine learning approach to UCS prediction is presented,pairing five models(Random Forest(RF),Gradient Boosting(GB),Extreme Gradient Boosting(XGB),CatBoost,and K-Nearest Neighbors(KNN))with SHapley Additive exPlanations(SHAP)for enhanced interpretability and to guide feature removal.A complete dataset of 12 geotechnical and chemical parameters,i.e.,Atterberg limits,compaction properties,stabilizer chemistry,dosage,curing time,was used to train and test the models.R2,RMSE,MSE,and MAE were used to assess performance.Initial results with all 12 features indicated that boosting-based models(GB,XGB,CatBoost)exhibited the highest predictive accuracy(R^(2)=0.93)with satisfactory generalization on test data,followed by RF and KNN.SHAP analysis consistently picked CaO content,curing time,stabilizer dosage,and compaction parameters as the most important features,aligning with established soil stabilization mechanisms.Models were then re-trained on the top 8 and top 5 SHAP-ranked features.Interestingly,GB,XGB,and CatBoost maintained comparable accuracy with reduced input sets,while RF was moderately sensitive and KNN was somewhat better owing to reduced dimensionality.The findings confirm that feature reduction through SHAP enables cost-effective UCS prediction through the reduction of laboratory test requirements without significant accuracy loss.The suggested hybrid approach offers an explainable,interpretable,and cost-effective tool for geotechnical engineering practice.展开更多
The application of poly(butylene adipate-co-terephthalate)(PBAT)biodegradable plastics has long been constrained by insufficient light aging resistance.Hindered amine light stabilizers(HALSs),known as eco-friendly add...The application of poly(butylene adipate-co-terephthalate)(PBAT)biodegradable plastics has long been constrained by insufficient light aging resistance.Hindered amine light stabilizers(HALSs),known as eco-friendly additives,can scavenge free radicals to enhance polymer durability.However,rough choices have resulted in wastage of resources and environmental pressure.Based on the application of plastic films as the background for use,this study systematically evaluates application effects of five HALSs.The films underwent accelerated aging for various durations and were further investigated by a combination of experiments and molecular simulation.Results showed that all HALSs mitigated PBAT light aging,with Chimassorb-944(UV-944)and Tinuvin-770(UV-770)performing the best for real applications.Quantum chemical calculation results showed that UV-944 had stronger anti migration ability.After 300 h of aging,films with UV-944 and UV-770 retained superior tensile strength and elongation at break in the transverse direction compared to neat PBAT films.Polymeric HALSs provided better long-term stability than small-molecule ones.Further spectra analysis indicated that stronger C―O bonds in HALS/PBAT composites correlated with improved photostability.This study offers valuable insights into improving weather resistance of PBAT biodegradable films and optimizing the real application of HALSs.展开更多
Rechargeable lithium–sulfur(Li–S)batteries are considered promising next-generation energy storage systems owing to their high theoretical energy density,but their application is hindered by the shuttle effect arisi...Rechargeable lithium–sulfur(Li–S)batteries are considered promising next-generation energy storage systems owing to their high theoretical energy density,but their application is hindered by the shuttle effect arising from dissolved lithium polysulfides(LiPSs).Herein,we design an optimized electrolyte to achieve long-term stability by employing an appropriate low-polarity solvent.A combination of diethyl ether(DEE)and 1,2-dimethoxyethane(DME)was selected to improve Li metal stability even in the presence of LiPSs.The DEE/DME electrolyte not only suppresses parasitic reactions between Li and LiPSs but also promotes uniform Li deposition.Moreover,operando optical microscopy was employed to directly visualize electrolyte stability and dendrite evolution in real time,while quantitative analysis was conducted via normalized hue index and contour image mapping.The enhanced anode stability of the DEE/DME electrolyte enabled excellent cycling performance,retaining 80.14%of its initial capacity after300 cycles at 3 C,while maintaining superior performance under practical conditions with high sulfur loading and a low E/S ratio.These findings highlight that solvent properties critically influence Li metal stabilization in Li–S batteries and underscore the significance of solvent engineering in electrolyte design.展开更多
Superoxide dismutase 1(SOD1)is a thermodynamically stable,zinc and copper binding homodimeric enzyme responsible for breaking down superoxide radicals.More than 200,mostly missense,mutations spread throughout the SOD1...Superoxide dismutase 1(SOD1)is a thermodynamically stable,zinc and copper binding homodimeric enzyme responsible for breaking down superoxide radicals.More than 200,mostly missense,mutations spread throughout the SOD1 gene are associated with the fatal neurodegenerative disease,amyotrophic lateral sclerosis(ALS).A unifying feature of ALS-associated SOD1 mutations is the destabilization of the SOD1 protein structure,increasing the propensity for misfolding and subsequent pathological aggregation.Post-mortem analysis of SOD1-associated ALS tissue shows the accumulation of misfolded SOD1 protein and ubiquitinated SOD1 inclusions within motor neurons.Misfolded SOD1 accumulation and aggregates are implicated in cellular dysfunction via a number of disparate but critical processes,including endoplasmic reticulum stress,oxidative damage,proteasome dysfunction,axonal transport abnormalities and synaptic dysfunction;culminating in motor neuron degeneration associated with ALS.展开更多
This paper is devoted to stabilizing the high-order uncertain nonlinear system in a fixed time by output feedback control.First,a novel settling time solution method is proposed by establishing an indirect double syst...This paper is devoted to stabilizing the high-order uncertain nonlinear system in a fixed time by output feedback control.First,a novel settling time solution method is proposed by establishing an indirect double system and using the comparison principle.Then a fixed-time observer and a neural networked based adaptive law are constructed to estimate the state and the unknown disturbance for the high-order uncertain nonlinear system.Furthermore,a fixed-time output feedback controller is proposed via the homogeneity technique.The upper bound of the settling time is analyzed for the closed-loop system under the proposed output feedback control.Finally,simulation examples are given to illustrate the effectiveness of the theoretical results.展开更多
Dear Editor,This letter embarks on an examination of fixed-time stability(FxTS)for random nonlinear systems(RNSs)governed by random differential equations.This endeavor encompasses a multifaceted analysis of FxTS,comm...Dear Editor,This letter embarks on an examination of fixed-time stability(FxTS)for random nonlinear systems(RNSs)governed by random differential equations.This endeavor encompasses a multifaceted analysis of FxTS,commencing with its rigorous definition and its integration with Lyapunov theory,along which a consequential corollary emerges.Particularly,the positive definiteness of the expectation of settling time is established,and a less conservative upper bound is derived.The effectiveness of the proposed fixed-time theorem is verified by an example.展开更多
The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has...The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has been employed as a coating agent.The SEM micrographs revealed distinct features of both pure AN and NC,contrasting with the irregular granular surface topography of the coated AN particles,demonstrating the adherence of NC on the AN surface.Structural analysis via infrared spectroscopy(IR)demonstrated a successful association of AN and NC,with slight shifts observed in IR bands indicating interfacial interactions.Powder X-ray Diffraction(PXRD)analysis further elucidated the structural changes induced by the coating process,revealing that the NC coating altered the crystallization pattern of its pure form.Thermal analysis demonstrates distinct profiles for pure and coated AN,for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6℃,and 36%,respectively.Furthermore,the presence of NC coating alters the intermolecular forces within the composite system,leading to a reduction in melting enthalpy of coated AN by~39%compared to pure AN.The thermal decomposition analysis shows a two-step thermolysis process for coated AN,with a significant increase in the released heat by about 78%accompanied by an increase in the activation barrier of NC and AN thermolysis,demonstrating a stabilized reactivity of the AN-NC particles.These findings highlight the synergistic effect of NC coating on AN particles,which contributed to a structural and reactive stabilization of both AN and NC,proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.展开更多
基金supported by Social Science Fund of Hunan province(Grant No.22JD074)the Research Foundation of Education Bureau of Hunan province(Grant No.22B0912).
文摘In this paper, a class of discontinuous neutral-type neural networks (NTNNs) with proportional delays is considered. The targets of the paper are to study the problem of periodic solutions and fixed-time (FXT) stabilization of the addressed neural networks. In order to complete the targets, based on set-valued map, differential inclusions theory, coincidence theorem and Hölder inequality technique, some new proportional delay-dependent criteria shown by the inequalities are derived. Based on the fact of the existence of solution, further by applying the FXT stability lemmas and equivalent transformation, the zero solution of closed-loop system achieves FXT stabilization and the corresponding settling-times are estimated. Some previous related works on NTNNs are extended. Finally, one typical example is provided to show the effectiveness of the established results.
基金supported by the National Natural Science Foundation of China(61821004,U1964207,20221017-10)。
文摘This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two dynamic parameters.Specifically,a set of auxiliary variables is first introduced through state transformation.These variables combine the original system states and the two introduced dynamic parameters,facilitating the closed-loop system stability analyses.Then,the two dynamic parameters are delicately designed by utilizing the Lyapunov method,ensuring that all the closed-loop system states are globally fixed-time stable.Compared with existing results,the“explosion of complexity”problem of backstepping control is avoided.Moreover,the two designed dynamic parameters are dependent on system states rather than a time-varying function,thus the proposed controller is still valid beyond the given fixedtime convergence instant.The effectiveness of the proposed method is demonstrated through two practical systems.
基金This work is supported in part by the Ministry of Education(MOE),Singapore under Grant MOE2020-T1-1-067also partially supported by the National Natural Science Foundation of China under Grants 62103352 and 61903319.
文摘In this paper,we consider the fixed-time stabilization control problem of quantum systems modeled by Schrodinger equations.Firstly,the Lyapunov-based fixed-time stability criterion is extended to finitedimensional closed quantum systems in the form of coherence vectors.Then for a two-level quantum system with single control input,a non-smooth fractional-order control law is designed using the relative state distance.By integrating the fixed-time Lyapunov control technique and the bi-limit homogeneity theory,the quantum system is proved to be stabilized to an eigenstate of the inherent Hamiltonian in a fixed time.Comparing with existing methods in quantum system control,the proposed approach can guarantee stabilization in a fixed time without depending on the initial states.
文摘As well-known,prescribed-time stabilizing design faces the need of using time-varying high gains which escape to infinity as time approaches the desired instant.In the presence of measurement noise,the corresponding state response is also significantly amplified that leads to the lack of robustness in the closedloop implementation.In order to eliminate this drawback,the implicit Euler discretization of the closed-loop in question is recently developed in where desired robustness properties are conserved beyond the prescribedtime interval while also bounded state dynamics are ensured in the presence of measurement noise.Along this line,stabilizing prescribed-observer-based output feedback algorithms and their digital implementation are reviewed.For tutorial value,the underlying state feedback and observer designs are recalled side by side in continuous-and discrete-time perspectives,followed by the desired output feedback design.Open problems,calling for future investigation,conclude the review.
基金supported by the National Natural Science Foundation of China(62373317)the Tianshan Talent Training Program(2022TSYCCX0013)+3 种基金the Key Project of Natural Science Foundation of Xinjiang(2021D01D10)the Basic Research Foundation for Universities of Xinjiang(XJEDU2023P023)the Xinjiang Key Laboratory of Applied Mathematics(XJDX1401)the Intelligent Control and Optimization Research Platform in Xinjiang University.
文摘This paper is dedicated to fixed-time passivity and synchronization for multi-weighted spatiotemporal directed networks.First,to achieve fixed-time passivity,a type of decentralized power-law controller is developed,in which only one parameter needs to be adjusted in the power-law terms;this greatly decreases the inconvenience of parameter adjustment.Second,several fixed-time passivity criteria with LMI forms are derived by using a Gauss divergence theorem to deal with the spatial diffusion of nodes and by applying the Hölder’s inequality to dispose rigorously the power-law term greater than one in the designed control scheme;this improves the previous theoretical analysis.Additionally,the fixed-time synchronization of spatiotemporal directed networks with multi-weights is addressed as a direct result of fixed-time strict passivity.Finally,a numerical example is presented in order to show the validity of the theoretical analysis.
基金supported by the National Natural Science Foundation of China under Grants 61962023,61562029 and 62466019.
文摘This paper presents an adaptive multi-agent coordination(AMAC)strategy suitable for complex scenarios,which only requires information exchange between neighbouring robots.Unlike traditional multi-agent coordination methods that are solved by neural dynamics,the proposed strategy displays greater flexibility,adaptability and scalability.Furthermore,the proposed AMAC strategy is reconstructed as a time-varying complex-valued matrix equation.By introducing a dynamic error function,a fixed-time convergent zeroing neural network(FTCZNN)model is designed for the online solution of the AMAC strategy,with its convergence time upper bound derived theoretically.Finally,the effectiveness and applicability of the coordination control method are demonstrated by numerical simulations and physical experiments.Numerical results indicate that this method can reduce the formation error to the order of 10^(-6)within 1.8 s.
基金Supported by the National Natural Science Foundation of China(62576008)University Annual Scientific Research Plan of Anhui Province(2022AH030023)。
文摘In this paper,a class of discontinuous Cohen-Grossberg neural networks with timevarying delays is considered.Firstly,under the extended Filippov differential inclusions framework,the problem of periodic solutions of the considered neural networks with more relaxed conditions imposed on the amplification functions is analyzed by using set-valued mapping and Kakutani's fixed point theorem,which has rarely been used to study such problem.Secondly,the fixed-time synchronization of the error system of the considered neural networks is also investigated by designing a novel control strategy,which can improve not only the previous ones with sign function greatly,but also can reduce the chattering phenomenon.Finally,two numerical examples are presented to further illustrate the validity of the obtained results.
基金supported by National Natural Science Foundation of China[grant number 62173208]Taishan Scholar Project of Shandong Province of China[grant number tsqn202103061]。
文摘This paper is dedicated to solving the problem of adaptive fuzzy fault-tolerant tracking control for a class of time-varying high-order uncertain nonlinear systems.The motivation comes from how to construct a compact set large enough in which the approximation of any unknown continuous function by a fuzzy logic system(FLS)is effective while compensating sensor/actuator faults and external disturbances.The difficulty is to verify the boundedness of closed-loop signals on the constructed compact set and to reduce the number of the variables of the fuzzy membership functions as many as possible.By a new lemma,linear/nonlinear terms are introduced in adaptive laws to dominate unknown residual terms.With adding a power integrator method,a unified fault-tolerant controller is designed to drive the tracking error to converge to a small compact set of the origin within a fixed time,regardless of whether the system suffers from faults and disturbances.Superior to the existing results,in the presence of time-varying factors the scheme of this paper clarifies the logical relationship between the compactness of the approximation and the boundedness of the state variables.Finally,the application of control strategy is demonstrated by numerical/practical examples.
基金supported by the key technology project of China Southern Power Grid Corporation(GZKJXM20220041)partly by theNational Key Research andDevelopment Plan(2022YFE0205300).
文摘Flexibly interconnected distribution networks(FIDN)offer improved operational efficiency and operational control flexibility of power distribution systems through DC interconnection links,and have gradually become the main form of distribution networks.Aiming at the impact of constant power loads and converter transmission power variations in FIDN system stability,this paper presents an impedance reshaping based stability analysis and stabilization control to enhance the stability of the interconnected system and improve the system’s dynamic load response capability.Firstly,a small-single based equivalent impedance model of FIDN system,which consists flexibly interconnected equipment,energy storage,PV units,and constant power loads,is presented,and the total output and input impedance of the DC distribution network are derived.Secondly,the impacts of constant power loads and transmission power variations on the small-signal stability of FIDN system are analyzed through Nyquist stability curves using the impedance ratio criterion.Then,an impedance reshaping-based stability enhancement strategy for the FIDN system is proposed,which can significantly improve the system stability under the operating conditions of constant power loads and transmission power variations.Finally,a MATLAB/Simulink simulation model is built and tested.The results demonstrate that the proposed impedance reshaping strategy effectively mitigates voltage dips,surges,and DC bus fluctuations,shortens transient responses under power variations,and enables rapid stability recovery with reduced voltage drop during severe AC sags.
基金supported by the National Natural Science Foundation of China(Grant No.U22A20600)by the Natural Science Foundation of Hubei Province(Grant No.2025AFA015).
文摘To enhance the stabilization performance of red-bedded mudstone subgrade soil,a novel synergistic technique combining microorganisms and quicklime was developed and evaluated through comprehensive physical,mechanical,and microstructural analyses.The results demonstrated that quicklime significantly improved the pore structure by increasing the proportion of pores with diameters in the range of 0.5-50μm,thereby facilitating microbial migration and calcium carbonate precipitation.The proposed technique effectively enhanced cementitious material production(cementation rate:6.83%),unconfined compressive strength(1.63 MPa),and resistance to swelling and deformation(swelling rate:0.26%).The observed synergistic effect can be attributed to two primary mechanisms.First,quicklime promotes soil particle agglomeration,resulting in larger pores that enable bacterial mobility and provide optimal microenvironments for microbial activity.Second,during curing,quicklime undergoes hydration and ionization,releasing Ca^(2+)and OH^(−)ions.The Ca^(2+)ions serve as calcium sources for microbial-induced carbonate precipitation,while the OH−ions react with SiO_(2)and Al_(2)O_(3) to form hydrated gels that develop a skeletal soil structure.Meanwhile,the exothermic reaction further accelerates calcium carbonate deposition within the agglomerated pores.
基金supported by the National Natural Science Foundation of China(No.52374121)the Henan Province Science and Technology Research and Development Joint Fund,China(No.235200810016)the National Key Research and Development Program,China(No.2023YFC2907203).
文摘Rapid industrialization in China has caused significant environmental challenges,particularly heavy metal pollution from mine tailings.Toxic heavy metals such as lead(Pb),cadmium(Cd),and mercury(Hg)are released during the processing of mining wastewater and leaching of mine tailings.Owing to their excellent physicochemical properties,cementitious materials are widely used for the solidification/stabilization of heavy metals,immobilizing heavy metals via two distinct mechanisms.Physically,their favorable characteristics,including high mechanical strength,low porosity,and durable matrix,create effective barriers.Chemically,the alkaline environment facilitates the precipitation of metal hydroxides/carbonates.Conversely,hydration products(calcium silicate hydrate gels and ettringite)contribute to immobilization through adsorption and physical encapsulation.This study systematically investigated the migration mechanisms of heavy metal contaminants in mine tailings;further,it elucidated the multifaceted immobilization pathways of cementitious materials,which involve synergistic adsorption,precipitation,and encapsulation by hydration products combined with homocrystalline substitution.A comprehensive analysis indicated that cementitious materials significantly reduced the mobility and bioavailability of heavy metals.Nonetheless,their long-term stability and potential environmental impact require further investigation.This study aims to provide theoretical support for environmental management and sustainable resource utilization,and to explore the broader application potential of cementitious technology for heavy metal stabilization,thereby establishing a theoretical foundation for future research on heavy metals in low-cement solidified/stabilized tailings.
基金support from National Key R&D Program of China(2022YFB3807200)Science and Technology Commission of Shanghai Municipality(25CL2902100).
文摘Lithium-rich layered oxides(LRLOs)are promising cathode materials due to their high specific capacity,energy density,and operating voltage.However,their performance is hindered by the limited redox activity of transition metals,leading to oxygen redox instability,oxygen release,and capacity degradation.To address these issues,we propose an innovative lattice-oxygen modulation(LOM)strategy that incorporates Mn^(3+)and Ti^(4+)into the Li_(1.2)Cr_(0.3)Mn_(0.4)Ti_(0.1)O_(2) system,effectively mitigating Cr migration,stabilizing oxygen redox reactions,and reinforcing structural integrity.This results in improved electrochemical performance,as demonstrated by a 56.5 mAh g^(−1) increase in initial discharge capacity to 364.2 mAh g^(−1),with 71.3%capacity retention after 30 cycles,reflecting a 20.2%improvement in cycling stability.Density functional theory(DFT)calculations confirm enhanced Cr redox reversibility and reduced oxygen evolution,further strengthening structural stability.These synergistic effects highlight the pivotal role of the LOM strategy in optimizing both electrochemical performance and structural integrity,offering a scalable pathway to improve capacity and cycling stability in lithium-rich cathodes.
基金supported in part by the National Natural Science Foundation of China(62173208)Taishan Scholar Project of Shandong Province of China(tsqn202103061)the National Science and Technology Council(NSTC),Taiwan,China(NSTC 113-2221-E-006-145-MY2)。
文摘This paper explores the adaptive exponentially designated-time stabilization issue via event-triggered feedback for a kind of uncertain high-order nonlinear systems.The motivation mainly comes from the following two challenges:the undesired singularity problem arising from infinite control gains at the prescribed-time instant,the effective trade-off between the control amplitude and the triggering duration.The goal is to build an event-triggered mechanism comprising a skillful triggered rule alongside a time-dependent threshold.Utilizing the designed control strategy,the solutions'existence and the prevention of Zeno phenomenon are successfully guaranteed by using a new transformation equipped with a time-varying function and redesigning the continuous state-feedback dominance approach with an array of integral functions involving embedded sign functions.Better than existing prescribed-time methods,our approach not only ensures that state variables converge to a small compact set before a designated time and stay there henceforth,and converge to the origin exponentially,but also ensures that the controller continuously works on the whole-time horizon.Two illustrative examples are given to show the effectiveness of the devised scheme.
文摘Unconfined Compressive Strength(UCS)is a key parameter for the assessment of the stability and performance of stabilized soils,yet traditional laboratory testing is both time and resource intensive.In this study,an interpretable machine learning approach to UCS prediction is presented,pairing five models(Random Forest(RF),Gradient Boosting(GB),Extreme Gradient Boosting(XGB),CatBoost,and K-Nearest Neighbors(KNN))with SHapley Additive exPlanations(SHAP)for enhanced interpretability and to guide feature removal.A complete dataset of 12 geotechnical and chemical parameters,i.e.,Atterberg limits,compaction properties,stabilizer chemistry,dosage,curing time,was used to train and test the models.R2,RMSE,MSE,and MAE were used to assess performance.Initial results with all 12 features indicated that boosting-based models(GB,XGB,CatBoost)exhibited the highest predictive accuracy(R^(2)=0.93)with satisfactory generalization on test data,followed by RF and KNN.SHAP analysis consistently picked CaO content,curing time,stabilizer dosage,and compaction parameters as the most important features,aligning with established soil stabilization mechanisms.Models were then re-trained on the top 8 and top 5 SHAP-ranked features.Interestingly,GB,XGB,and CatBoost maintained comparable accuracy with reduced input sets,while RF was moderately sensitive and KNN was somewhat better owing to reduced dimensionality.The findings confirm that feature reduction through SHAP enables cost-effective UCS prediction through the reduction of laboratory test requirements without significant accuracy loss.The suggested hybrid approach offers an explainable,interpretable,and cost-effective tool for geotechnical engineering practice.
基金supported by the Key Research and Development Task Project of Xinjiang Uygur Autonomous Region(No.2022B02033)the National Natural Science Foundation of China(Nos.42211530566 and 42311530066)+2 种基金the NSFC-FNRS Joint Program BIOAGRIFILM(No.FNRS PINT-BILATM 2022)the Science and Technology Project of Bijie Tobacco Company of Guizhou Province(No.2022520500240192)the Agricultural Science and Technology Innovation Program(ASTIP)。
文摘The application of poly(butylene adipate-co-terephthalate)(PBAT)biodegradable plastics has long been constrained by insufficient light aging resistance.Hindered amine light stabilizers(HALSs),known as eco-friendly additives,can scavenge free radicals to enhance polymer durability.However,rough choices have resulted in wastage of resources and environmental pressure.Based on the application of plastic films as the background for use,this study systematically evaluates application effects of five HALSs.The films underwent accelerated aging for various durations and were further investigated by a combination of experiments and molecular simulation.Results showed that all HALSs mitigated PBAT light aging,with Chimassorb-944(UV-944)and Tinuvin-770(UV-770)performing the best for real applications.Quantum chemical calculation results showed that UV-944 had stronger anti migration ability.After 300 h of aging,films with UV-944 and UV-770 retained superior tensile strength and elongation at break in the transverse direction compared to neat PBAT films.Polymeric HALSs provided better long-term stability than small-molecule ones.Further spectra analysis indicated that stronger C―O bonds in HALS/PBAT composites correlated with improved photostability.This study offers valuable insights into improving weather resistance of PBAT biodegradable films and optimizing the real application of HALSs.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2024-00455177)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(RS-2025-00518953)+2 种基金the National Research Council of Science&Technology(NST)grant by the Korea government(MSIT)(GTL24012-000)the support by the National Natural Science Foundation of China(T2322015)the support by The Ministry of Science and ICT in Korea via KBSI(C524100)。
文摘Rechargeable lithium–sulfur(Li–S)batteries are considered promising next-generation energy storage systems owing to their high theoretical energy density,but their application is hindered by the shuttle effect arising from dissolved lithium polysulfides(LiPSs).Herein,we design an optimized electrolyte to achieve long-term stability by employing an appropriate low-polarity solvent.A combination of diethyl ether(DEE)and 1,2-dimethoxyethane(DME)was selected to improve Li metal stability even in the presence of LiPSs.The DEE/DME electrolyte not only suppresses parasitic reactions between Li and LiPSs but also promotes uniform Li deposition.Moreover,operando optical microscopy was employed to directly visualize electrolyte stability and dendrite evolution in real time,while quantitative analysis was conducted via normalized hue index and contour image mapping.The enhanced anode stability of the DEE/DME electrolyte enabled excellent cycling performance,retaining 80.14%of its initial capacity after300 cycles at 3 C,while maintaining superior performance under practical conditions with high sulfur loading and a low E/S ratio.These findings highlight that solvent properties critically influence Li metal stabilization in Li–S batteries and underscore the significance of solvent engineering in electrolyte design.
基金Motor Neuron Disease Research Australia in the form of a Bill Gole Postdoctoral Fellowship(PDF2307)FightMND in the form of Drug Development Grants(DDG-159 and DDG137 to JSL)。
文摘Superoxide dismutase 1(SOD1)is a thermodynamically stable,zinc and copper binding homodimeric enzyme responsible for breaking down superoxide radicals.More than 200,mostly missense,mutations spread throughout the SOD1 gene are associated with the fatal neurodegenerative disease,amyotrophic lateral sclerosis(ALS).A unifying feature of ALS-associated SOD1 mutations is the destabilization of the SOD1 protein structure,increasing the propensity for misfolding and subsequent pathological aggregation.Post-mortem analysis of SOD1-associated ALS tissue shows the accumulation of misfolded SOD1 protein and ubiquitinated SOD1 inclusions within motor neurons.Misfolded SOD1 accumulation and aggregates are implicated in cellular dysfunction via a number of disparate but critical processes,including endoplasmic reticulum stress,oxidative damage,proteasome dysfunction,axonal transport abnormalities and synaptic dysfunction;culminating in motor neuron degeneration associated with ALS.
基金This research was supported partially by the National Natural Science Foundation of China under Grant Nos.62103341,61473061 and 71503206the Sichuan Science and Technology Program under Grant No.2020YFSY0012.
文摘This paper is devoted to stabilizing the high-order uncertain nonlinear system in a fixed time by output feedback control.First,a novel settling time solution method is proposed by establishing an indirect double system and using the comparison principle.Then a fixed-time observer and a neural networked based adaptive law are constructed to estimate the state and the unknown disturbance for the high-order uncertain nonlinear system.Furthermore,a fixed-time output feedback controller is proposed via the homogeneity technique.The upper bound of the settling time is analyzed for the closed-loop system under the proposed output feedback control.Finally,simulation examples are given to illustrate the effectiveness of the theoretical results.
基金supported by the National Natural Science Foundation of China(62103203).
文摘Dear Editor,This letter embarks on an examination of fixed-time stability(FxTS)for random nonlinear systems(RNSs)governed by random differential equations.This endeavor encompasses a multifaceted analysis of FxTS,commencing with its rigorous definition and its integration with Lyapunov theory,along which a consequential corollary emerges.Particularly,the positive definiteness of the expectation of settling time is established,and a less conservative upper bound is derived.The effectiveness of the proposed fixed-time theorem is verified by an example.
文摘The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has been employed as a coating agent.The SEM micrographs revealed distinct features of both pure AN and NC,contrasting with the irregular granular surface topography of the coated AN particles,demonstrating the adherence of NC on the AN surface.Structural analysis via infrared spectroscopy(IR)demonstrated a successful association of AN and NC,with slight shifts observed in IR bands indicating interfacial interactions.Powder X-ray Diffraction(PXRD)analysis further elucidated the structural changes induced by the coating process,revealing that the NC coating altered the crystallization pattern of its pure form.Thermal analysis demonstrates distinct profiles for pure and coated AN,for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6℃,and 36%,respectively.Furthermore,the presence of NC coating alters the intermolecular forces within the composite system,leading to a reduction in melting enthalpy of coated AN by~39%compared to pure AN.The thermal decomposition analysis shows a two-step thermolysis process for coated AN,with a significant increase in the released heat by about 78%accompanied by an increase in the activation barrier of NC and AN thermolysis,demonstrating a stabilized reactivity of the AN-NC particles.These findings highlight the synergistic effect of NC coating on AN particles,which contributed to a structural and reactive stabilization of both AN and NC,proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.
