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A FAS approach for stabilization of generalized chained forms: part 1. Discontinuous control laws

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Science China(Information Sciences) 2024年第2期67卷 118-143页

作者： Guang-Ren duan Center for Control Theory and Guidance Technology Harbin Institute of Technology Center for Control Science and Technology Southern University of Science and Technology

In this paper, a type of general nonholonomic systems is proposed, which contains both the Brockett’s two example systems, and their extended n-dimensional chained forms, as special cases. For the stabilization of such systems, a stabilizing controller is proposed based on the fully actuated system(FAS)approach, which is discontinuous at the origin but time-invariant when the open-loop system is time-invariant,and drives the feasible trajectories of the system to the origin exponentially. Furthermore, the proposed FAS approach is also extended to the sub-normal system case and the time-delay system case.

关键词： nonholonomic systems feedback stabilization exponential convergence sub-fully actuated systems time-delay systems

Stabilization Controller of An Extended Chained Nonholonomic System With Disturbance:An FAS Approach

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1262-1273页

作者： Zhongcai Zhang Guangren duan School of Engineering Qufu Normal UniversityRizhao 276826China Center for Control Science and Technology Southern University of Science and TechnologyShenzhen 518055 Center for Control Theory and Guidance Technology Harbin Institute of TechnologyHarbin 150001China

This study examines the stabilization issue of extended chained nonholonomic systems(ECNSs)with external disturbance.Unlike the existing approaches,we transform the considered system into a fully actuated system(FAS)model,simplifying the stabilizing controller design.We implement a separate controller design and propose exponential stabilization controller and finite-time stabilization controller under finite-time disturbance observer(FTDO)for the two system inputs.In addition,we discuss the specifics of global stabilization control design.Our approach demonstrates that two system states exponentially or asymptotically converge to zero under the provided switching stabilization control strategy,while all other system states converge to zero within a finite time.

关键词： design stabilization system

A comprehensive research on wear resistance of GH4169 superalloy in longitudinal-torsional ultrasonic vibration side milling with tool wear and surface quality

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Chinese Journal of Aeronautics 2024年第4期37卷 556-573页

作者： Baoqi CHANG Zhaoxi YI Fen ZHANG Lian duan Ji-an duan School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China State Key Laboratory of High Performance and Complex Manufacturing Central South UniversityChangsha 410083China School of Physics and Electronics Central South UniversityChangsha 410083China

To improve the service and machining performance of the workpiece, the tool wear mechanisms, surface machining quality, and wear resistance in conventional side milling(CSM)and longitudinal-torsional ultrasonic vibration side milling(LTUVSM) of GH4169 superalloy at different cutting lengths are investigated systematically. Tool wear mechanisms are revealed and the correlation between machined surface quality with tool wear is analyzed correspondingly. Tool wear patterns mainly include adhesive wear, diffusion wear, abrasive wear, and chipping sticking.Better surface quality is achieved in LTUVSM due to a maximum reduction of flank wear bandwidth and wear rate by 71.9% and 71.5%, respectively, compared to CSM. The friction coefficient,initial wear stage time, and wear volume of dry sliding wear were measured to evaluate the workpiece wear resistance. The maximum reductions in friction coefficient and wear volume in LTUVSM are 18.2% and 15.8% compared to CSM. The regular ultrasonic vibration textures suppress the friction and the growth of contact nodes in the contact area, decreasing the degree of surface wear, which is demonstrated by a 38.8% increase in initial wear stage time compared to CSM.In conclusion, the workpiece in LTUVSM exhibits higher wear resistance because of the improvement of tool wear and the guarantee of surface quality.

关键词： Dry sliding wear Surface quality Tool wear Ultrasonic vibration Wear resistance

Distributed velocity-free formation tracking control for clustered UAVs under virtual leader-follower framework

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Science China(Technological Sciences) 2024年第5期67卷 1538-1552页

作者： ZHANG ZhaoYu duan HaiBin School of Automation Science and Electrical Engineering Beihang UniversityBeijing100083China

The collective formation control problem of a cluster of rotorcraft unmanned aerial vehicles(UAVs)is investigated in this article.The consensus tracking towards formation centroid with following UAVs forming a predefined configuration around the leader is considered as the objective.Unlike prior studies,the information of the central reference trajectory,which is deemed as a virtual leader in the leader-follower topology,is not directly accessible for partial nodes through the communication network.Therefore,a novel distributed formation tracking control scheme is promoted.Besides,a decentralized saturation observer is employed to estimate the reference acceleration signal of the virtual leader.In the absence of linear velocity measurement,two sliding manifolds are proposed by introducing the relative discrepancy terms of position and velocity.Then a smooth saturation operator in the form of a sigmoid function is applied to generate the command force input.Moreover,under the dilemma of constrained capabilities of the airborne sensors equipped on the rotorcrafts,the angular velocity is difficult to acquire.Two cascaded auxiliary attitude error systems are established on each rotorcraft system to synthesize the rotating torque with no need to require the angular velocity measurement.Due to the strong coupling and nonlinearity of the rotorcraft UAV system,the command angular velocity and the derivatives of command input are hard to obtain.Then a continuous nonlinear differentiator is proposed to work with the difficulties in deriving the explicit expression of system derivatives.Thereafter,a detailed stability analysis is conducted progressively on the angular control loop,reference trajectory observer loop,and the position control loop.A simulation scheme for a cluster of four rotorcraft UAVs tracking sinusoidal trajectory are presented and the formation control results are proven advantageous in comparison with the control protocol in previous literature.

关键词： distributed formation control unmanned rotorcraft clusters velocity-free tracking nonlinear differentiator

Fabrication of porous adsorbents from eco-friendly aqueous foam for high-efficient removal of cationic dyes and sustainable utilization assessment

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Journal of Environmental Sciences 2024年第3期137卷 395-406页

作者： Fangzhi duan Yongfeng Zhu Yan Liu Aiqin Wang Key Laboratory of Clay Mineral Applied Research of Gansu Province Center of Eco-material and Green ChemistryLanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Porous materials applied in environmental remediation have received researchers'extensive attention recently,but the related green and convenient preparation method is rarely reported.Here,we recommended a green and convenient strategy for the fabrication of porous material via aqueous foam templates,which was synergistically stabilized by Codonopsis pilosula(CP)and clay minerals of attapulgite(APT).The characterization results revealed that the APT was modified by organic molecules leached from CP and anchored at the air-water interface,which improved the foam stability significantly.The novel porous material of polyacrylamide/Codonopsis pilosula/attapulgite(PAM/CP/APT)templated from the aqueous foam via a polymerization reaction had excellent adsorption capacity for the cationic dyes methyl violet(MV)and methylene blue(MB),and the adsorption capacity can reach 755.85 mg/g and557.64 mg/g,respectively.More importantly,the adsorption capacity of spent adsorbent material was still over 200 mg/g after being recycled five times through a simple carbonization process,and then it was added to the plant pot,the total biomass was increased by about86.42%.This study provided a green and sustainable pathway for the preparation,application and subsequent processing of porous materials.

关键词： Porous material Aqueous foam Atapulgite Adsorption Cationic dyes Sustainable utilization

Removal of Cr(Ⅵ)by glutaraldehyde-crosslinked chitosan encapsulating microscale zero-valent iron:Synthesis,mechanism,and longevity

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Journal of Environmental Sciences 2024年第8期142卷 115-128页

作者： Yijun duan Fang Liu Xiang Liu Miao Li School of Environment Tsinghua UniversityBeijing 100084China Transportation Institute of Inner Mongolia University Hohhot 010070China

Microscale zero-valent iron(mZVI)has shown great potential for groundwater Cr(Ⅵ)remediation.However,low Cr(Ⅵ)removal capacity caused by passivation restricted the wide use of mZVI.We prepared mZVI/GCS by encapsulating mZVI in a porous glutaraldehydecrosslinked chitosan matrix,and the formation of the passivation layer was alleviated by reducing the contact between zero-valent iron particles.The average pore diameter of mZVI/GCS was 8.775 nm,which confirmed the mesoporous characteristic of this material.Results of batch experiments demonstrated that mZVI/GCS exhibited high Cr(Ⅵ)removal efficiency in a wide range of pH(2-10)and temperature(5-35℃).Common groundwater coexisting ions slightly affected m ZVI/GCS.The material showed great reusability,and the average Cr(Ⅵ)removal efficiency was 90.41%during eight cycles.In this study,we also conducted kinetics and isotherms analysis.Pseudo-second-order model was the most matched kinetics model.The Cr(Ⅵ)adsorption process was fitted by both Langmuir and Freundlich isotherms models,and the maximum Langmuir adsorption capacity of m ZVI/GCS reached243.63 mg/g,which is higher than the adsorption capacities of materials reported in most of the previous studies.Notably,the column capacity for Cr(Ⅵ)removal of a mZVI/GCS-packed column was 6.4 times higher than that of a mZVI-packed column in a 50-day experiment.Therefore,mZVI/GCS with a porous structure effectively relieved passivation problems of mZVI and showed practical application prospects as groundwater Cr(Ⅵ)remediation material with practical application prospects.

关键词： Chitosan Glutaraldehyde mZVI Cr(Ⅵ) Groundwater

A FAS approach for stabilization of generalized chained forms: part 2. Continuous control laws

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Science China(Information Sciences) 2024年第3期67卷 114-135页

作者： Guang-Ren duan Center for Control Theory and Guidance Technology Harbin Institute of Technology Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and Technology

In this paper, continuous time-varying stabilizing controllers for the type of general nonholonomic systems proposed and treated in part 1 are designed using the fully actuated system(FAS) approach. The key step is to differentiate the first scalar equation, and by control of the obtained second-order scalar system, a proportional plus integral feedback form for the first control variable is obtained. With the solution to this designed second-order scalar system, the rest equations in the nonholonomic system form an independent time-varying subsystem which is then handled by the FAS approach. The overall designed controller contains an almost arbitrarily chosen design parameter, and is proven to guarantee the uniformly and globally exponential stability of the closed-loop system. The proposed approach is simple and effective,and is demonstrated with a practical example of ship control.

关键词： nonholonomic systems feedback stabilization fully actuated systems Lyapunov stability continuous controllers

Advances in microfluidic-based DNA methylation analysis

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Nanotechnology and Precision Engineering 2024年第1期7卷 116-134页

作者： Jiwen Li Tiechuan Li Xuexin duan State Key Laboratory of Precision Measuring Technology and Instruments Tianjin UniversityTianjin 300072China

DNA methylation has been extensively investigated in recent years,not least because of its known relationship with various diseases.Progress in analytical methods can greatly increase the relevance of DNA methylation studies to both clinical medicine and scientiﬁc research.Microﬂu-idic chips are excellent carriers for molecular analysis,and their use can provide improvements from multiple aspects.On-chip molecular analysis has received extensive attention owing to its advantages of portability,high throughput,low cost,and high efﬁciency.In recent years,the use of novel microﬂuidic chips for DNA methylation analysis has been widely reported and has shown obvious superiority to conventional methods.In this review,weﬁrst focus on DNA methylation and its applications.Then,we discuss advanced microﬂuidic-based methods for DNA methylation analysis and describe the great progress that has been made in recent years.Finally,we summarize the advantages that microﬂuidic technology brings to DNA methylation analysis and describe several challenges and perspectives for on-chip DNA methylation analysis.This review should help researchers improve their understanding and make progress in developing microﬂuidic-based methods for DNA methylation analysis.

关键词： Microﬂuidic chip DNA methylation analysis Molecular analysis High throughput Low cost

Design Optimization and Operating Performance of S-CO_(2) Brayton Cycle under Fluctuating Ambient Temperature and Diverse Power Demand Scenarios

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Journal of Thermal Science 2024年第1期33卷 190-206页

作者： YANG Jingze YANG Zhen duan Yuanyuan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce costs.Since the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand scenarios.In addition,the cycle design condition will directly affect the off-design performance.In this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced innovatively.Results show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient temperatures.The average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient temperature.With multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature period.If the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.

关键词： supercritical CO_(2)Brayton cycle ambient temperature fluctuating power demand scenarios design optimization off-design performance