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Simulation of the deformable lateral boundaries in biaxial test using DEM

Particuology 2024年第5期88卷 161-175页

作者： Ali Momeni Barry Clarke Yong sheng Ali Hassanpour WSP 3 Wellington PlaceLeedsLS1 4APUK Hull University HullHU6 7RXUK School of Civil Engineering University of LeedsLeedsLS2 9JTUK School of Computer Science University of HullHullHU6 7RXUK School of Chemical and Process Engineering University of LeedsLeedsLS2 9JTUK

Applying the discrete element method(DEM)in soil mechanics can provide abundant information at the particle-scale and facilitates illustration of the macro-mechanical behaviour of soils based on the inter-particle *** triaxial test is one of the most common laboratory methods to study the macro-mechanical behaviour of particulate materials such as ***,many problems in geotechnical design can be assumed and simplified as a plane strain *** a biaxial test can be conducted to reproduce the macro-mechanical behaviour of soil,where the sample is enclosed by two horizontal rigid platens and a vertical latex membrane,which is a deformable continuous element and allows the enclosed specimen to deform freely while maintaining confining stress during *** paper presents an algorithm to represent physical and mechanical characteristics of latex membrane in the 2D DEM simulation of biaxial test using the PFC^(2D) *** investigate the impact of the lateral boundary conditions on the micro-macro mechanical behaviours of soil samples,two sets of DEM biaxial tests are conducted,*** rigid and deformable lateral boundary *** DEM modeling results indicate that the lateral boundary conditions have a significant effect on the micro-scale fabric properties,thickness and inclination of the shear *** comparison between these two simulations also demonstrates that the lateral boundary conditions play a major role in the peak and post-peak stress-strain behaviours as well as the dilation and critical state behaviours of granular soils.

关键词： Discrete element method Biaxial test Deformable boundaries Shear band Critical state Fabric anisotropy Geometrical stability index

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Further Results on Stability Analysis for Sampled-Data Systems via Refined Semi-Looped-Functional

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Journal of Systems Science & Complexity 2024年第1期37卷 318-328页

作者： sheng Zhaoliang XU shengyuan MA Qian ZHANG Baoyong School of Automation Nanjing University of Science and TechnologyNanjing 210094China

This paper investigates the stability problem for sampled-data systems by adopting a refined semi-looped-functional,which is with the following two ***,the new functional term is with a new integral vectorη0,which contains sampling information of the systems and associates two commonly used ***,the vectorη0 is combined into various zero equations for processing the functional,especially where a new equation is derived fromη*** on the refined functional,further stability results for sampled-data systems are *** the effectiveness of the results is numerically verified through two examples at the end.

关键词： Integral vector sampled-data systems semi-looped-functional stability analysis.

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H∞ Robustness for Distributed Control in Autonomous Microgrids Considering Cyber Disturbances

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 696-706页

作者： Ge Cao Guannan Lou Wei Gu Lina sheng School of Electrical Engineering Southeast UniversityNanjing 210096China

The physical connections and logical relationships between microgrids and communication networks allow microgrids to develop into typical cyber-physical systems(CPSs).With the extensive use of open communication mechanisms,the impact of cyber disturbances in public communication networks cannot be *** this paper,a parameter optimal method for a distributed secondary controller based on the robust control theory and consensus algorithm is presented to enhance the robustness of a secondary control system under data disturbance,parameter perturbation,and time ***,a distributed secondary control strategy of microgrids is demonstrated that coordinates frequency and voltage restoration and power ***,considering the impact of cyber events on the secondary control,a distributed robust controller gain design method is proposed to satisfy the H∞ performance *** solution of the distributed robust control is transformed into a linear matrix in equation problem and latency margin is simultaneously ***,a test microgrid CPS is simulated with and without time delay to investigate the impact of cyber events on system operational states and the effectiveness and robustness of the proposed method.

关键词： Cyber disturbance cyber-physical lsystem distributed control microgrid robust H∞control

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Nitrogen-doped carbon dots as photocatalysts for organic synthesis:Effect of nitrogen content on catalytic activity

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Nano Research 2024年第6期17卷 4825-4833页

作者： Kai-Kai Niu Chao-Qun Ma Rui-Zhi Dong Hui Liu sheng-sheng Yu Ling-Bao Xing School of Chemistry and Chemical Engineering Shandong University of TechnologyZibo 255000China

Regulating the doping of carbon dots(CDs)and the generation of reactive oxygen species(ROS)is essential to selectively control their application in photocatalytic organic *** study successfully synthesized five newly developed nitrogen-doped carbon dots(CDs 1-5)with varying nitrogen content,which have the ability to generate ROS when exposed to light radiation,specifically superoxide anion radicals(O_(2)•-)and singlet oxygen(^(1)O_(2)).The utilization of the aforementioned nitrogen-doped CDs as photocatalysts enables the realization of their potential in facilitating efficient photocatalytic organic ***,it was observed that the photocatalytic efficiency exhibited a gradual decrease when the nitrogen content in the CDs *** order to provide more evidence for this claim,we employed a set of five CDs in the context of photocatalytic dehalogenation ofα-bromoacetophenone,photocatalytic oxidative coupling reaction of amines to imines,photooxidation reaction of sulfides to sulfoxides,and cross-dehydrogenation coupling(CDC)reaction,in which it was further observed that there was a steady decrease in the yields of photocatalytic organic reactions as the nitrogen content in CDs ***,CDs 1 exhibited the best photocatalytic efficiency,thereby reinforcing the hypothesis that a higher nitrogen content corresponds to a decreased catalytic *** study not only investigates the impact of the nitrogen content on the catalytic performance of CDs,but also offers valuable insights for the future utilization of CDs for photocatalytic organic reactions in water.

关键词： carbon dots nitrogen-doped reactive oxygen species photocatalysis

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Transient Stability Analysis and Design of VSGs with Different DC-Link Voltage Controllers

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 593-604页

作者： Chao Shen Wei Gu Wanxing sheng Keyan Liu School of Electrical Engineering Southeast UniversityNanjingChina Power Distribution Research Department China Electric Power Research InstituteBeijing 100192China

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

关键词： DC-link voltage dynamics equal area criterion(eac) transient synchronization stability virtual synchronous generator(VSG)

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Novel high-safety aeroengine performance predictive control method based on adaptive tracking weight

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Chinese Journal of Aeronautics 2024年第7期37卷 352-374页

作者： Qian CHEN Hanlin sheng Jie ZHANG Jiacheng LI College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Increasing attention has been attracted to the dynamic performance and safety of advanced performance predictive control systems of the next-generation *** latest research demonstrates that Subspace-based Improved Model Predictive Control(SIMPC)can overcome the difficulty in solving the predictive model in MPC/NMPC ***,applying constant design parameters cannot maintain consistent control effects in all ***,the designed system relies too much on sensor-measured data,and thus it is difficult to thoroughly validate the safety of the system because of its high *** means that any potential hardware/software faults will endanger the ***,this paper first presents a novel nonlinear mapping relationship to adaptively tune the tracking weight online with the change of Power Lever Angle(PLA)and real-time relative tracking ***,without introducing additional design parameters,an Adaptive Tracking Weight-based SIMPC(ATW-SIMPC)controller is designed to improve the control performance in all operating states ***,a Primary/Backup Hybrid Control(PBHC)strategy with the ATW-SIMPC controller as the primary system and the traditional speed(Nf)controller as the backup system is proposed to ensure *** designed affiliated switching controller and the real-time monitor therein can be used to realize reasonable and smooth switching between primary/backup systems,so as to avoid bump *** PBHC system switches to the Nf controller when the ATW-SIMPC controller is wrong because of potential hardware/software faults;otherwise,the ATW-SIMPC controller keeps acting on the *** main results prove that the ATW-SIMPC controller with the optimal nonlinear mapping relationship,compared with the existing SIMPC controller,uplifts the dynamic control performance by 32%and reduces overshoots to an allowable limit,resulting in a better control effect in full *** comparison results consistently i

关键词： Aeroengine Model predictive control Hybrid system Adaptive weight Safety

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Construction of conjugated scaffolds driven by mechanochemistry towards energy storage applications

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Green Chemical Engineering 2024年第2期5卷 155-172页

作者： Juntian Fan Zhenzhen Yang sheng Dai Department of Chemistry Institute for Advanced Materials and ManufacturingUniversity of TennesseeKnoxvilleTN37996USA Chemical Sciences Division Oak Ridge National LaboratoryOak RidgeTN37831USA

Mechanochemistry has been recognized as an efficient and sustainable methodology to provide a unique driven force and reaction environments under ambient and neat conditions for the construction of functionalized materials possessing promising *** them,highly porous conjugated scaffolds with attractive electronic conductivities and high surface areas are one of the representative categories exhibiting diverse taskspecific applications,especially in electrochemical energy *** recent years,the mechanochemistry-driven procedures have been deployed to construct conjugated scaffolds with engineered structures and properties leveraging the tunability in chemical structures of building blocks and polymerization capability of diverse ***,a thorough review of related works is required to gain an in-depth understanding of the mechanochemical synthesis procedure and property-performance relationship of the as-produced conjugated ***,the mechanochemistry-driven construction of conjugated porous networks(CPNs),the carbon-based materials(e.g.,graphite and graphyne),and carbon supported single atom catalysts(CS-SACs)are discussed and *** electrochemical performance of the afforded conductive scaffolds as electrode materials in supercapacitors and alkali-ion batteries is ***,the challenges and potential opportunities related to the construction of conjugated scaffolds driven by mechanochemistry are also discussed and concluded.

关键词： Mechanochemistry Conjugated scaffolds Porous organic networks Alkali-ion battery Supercapacitor

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Curve Classification Based onMean-Variance Feature Weighting and Its Application

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Computers, Materials & Continua 2024年第5期79卷 2465-2480页

作者： Zewen Zhang sheng Zhou Chunzheng Cao School of Mathematics and Statistics Nanjing University of Information Science and TechnologyNanjing210044China Center for Applied Mathematics of Jiangsu Province Nanjing University of Information Science and TechnologyNanjing210044China

The classification of functional data has drawn much attention in recent *** main challenge is representing infinite-dimensional functional data by finite-dimensional features while utilizing those features to achieve better classification *** this paper,we propose a mean-variance-based(MV)feature weighting method for classifying functional data or functional *** the feature extraction stage,each sample curve is approximated by B-splines to transfer features to the coefficients of the spline *** that,a feature weighting approach based on statistical principles is introduced by comprehensively considering the between-class differences and within-class variations of the *** also introduce a scaling parameter to adjust the gap between the weights of *** new feature weighting approach can adaptively enhance noteworthy local features while mitigating the impact of confusing *** algorithms for feature weighted K-nearest neighbor and support vector machine classifiers are both ***,the new approach can be well integrated into existing functional data classifiers,such as the generalized functional linear model and functional linear discriminant analysis,resulting in a more accurate *** performance of the mean-variance-based classifiers is evaluated by simulation studies and real *** results show that the newfeatureweighting approach significantly improves the classification accuracy for complex functional data.

关键词： Functional data analysis classification feature weighting B-splines

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Synthesis,Characterization of Polyethylene Ionomers and Their Antibacterial Properties

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Chinese Journal of Polymer Science 2024年第8期42卷 1077-1084页

作者： Jia-Jia Wu Fei Wang Peng-Qi Wan Li Pan Chun-sheng Xiao Zhe Ma Yue-sheng Li Tianjin Key Lab Composite&Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin 300350China Key Lab Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

Owing to its high production volume and wide range of application s,polyethylene has gained a great deal of attention,but its low surface energy and non-polar nature have limited its application in some important *** this study,ethylene/11-iodo-1-undecene copolymers were prepared and used as the intermediates to afford a series of imidazolium-based ionomers bearing methanesulfonate(CH_(3)SO_(3)^(-)),trifluoromethanesulfonate(CF_(3)SO_(3)^(-)),or bis(trifluoromethane)sulfonimide(Tf_(2)N^(-))*** tensile test results showed that the stress-at-break(7.8-25.6 MPa)and the elongation-at-break(445%-847%)of the ionomers could be adjusted by changing the counterion species and the ionic group *** importantly,the ionomers exhibited marvelous antibacterial activities against Staphylococcus aureus(***)and Escherichia coli(***).The ionomers bearing Tf_(2)N^(-)exhibited antibacterial activities>99%against both *** and *** when ionic content reached 9.1%.The imidazolium-based ionomers prepared in this work demonstrated excellent comprehensive properties,especially highefficient and broad-spectrum antibacterial ability,exhibiting the potential fo r the application as the antibacterial materials in packaging,medical,and other fields.

关键词： Polyethylene Ionomer Polymerization catalysis Imidazolium Antibacterial material

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Demixing microwave signals using system-on-chip photonic processor

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Light(Science & Applications) 2024年第3期13卷 399-401页

作者： sheng Gao Chu Wu Xing Lin Department of Electronic Engineering Tsinghua University100084 BeijingChina Beijing National Research Center for Information Science and Technology Tsinghua University100084 BeijingChina

The integrated photonic processor,co-packaged with electronic peripherals,is proposed for blind source separation of microwave signals,which separates signal-of-interest from dynamic interference with real-time adapta... 详细信息

关键词： processor microwave mixing

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