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Particle size spatial distribution in landslide dams

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Journal of Mountain Science 2024年第6期21卷 1886-1903页

作者： zhang Jingyi zhang Jianmin State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610064China

The particle composition and spatial distribution of landslide-induced dam bodies are critical geotechnical parameters for studying the hazards of dam-break ***,current research often neglects the influence of the initial particle composition and spatial distribution of the landslide on the particle composition and spatial distribution of the landslide *** study investigated the impact of initial particle size distribution,volume,and sliding length on the energy and velocity changes of characteristic particles during the sliding process and the spatial distribution of particle sizes in the landslide dam *** simulations and physical models were employed to examine the effects of sequential gradient arrangements(where particle sizes decrease from top to bottom)and four other different initial particle arrangements on the energy and velocity changes of particles and the spatial distribution of particle sizes in the dam *** study reveals the characteristics of translational and rotational energy of different particles and the laws of mechanical energy conversion,obtaining the spatial distribution patterns of particle sizes in landslide-induced *** results show that under the sequential gradient arrangement,the energy dissipation of the landslide movement is lower,with larger particles mainly distributed at the distal end and smaller particles at the proximal end of the landslide *** contrast,under the reverse gradient arrangement,the energy dissipation of the landslide movement is higher,and the distribution pattern of the dam particles is opposite to that of the sequential gradient *** the other arrangement modes,the spatial distribution of dam particles falls between the aforementioned *** is a positive correlation between particle size and translational kinetic energy within the particle flow during the landslide process,and rotational motion increases energy *** constant slope conditions,sliding

关键词： Particle size distribution Landslide Numerical simulation Discrete element method

Periodic Variation Studies of the Two Short Period W UMa-type Eclipsing Binaries: LX Lyn and V0853 Aur

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Research in Astronomy and Astrophysics 2024年第1期24卷 273-284页

作者： Xu zhang Bin zhang School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550001China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang 550025China

In this paper,new light curves(LCs) of contact eclipsing binary(CEB) systems LX Lyn and V0853 Aur are presented and analyzed by using the 2015 version of the Wilson-Devinney(W-D) *** order to explain their asymmetric LCs,cool starspots on the components were *** is suggested that their fill-out degrees are f=12.0%(LX Lyn) and f=26.3%(V0853 Aur).At the same time,we found that LX Lyn is a W-type eclipsing binary(EB) with an orbital inclination of i=84°.88 and a mass ratio of q=2.31.V0853 Aur is also a W-type CEB with a mass ratio of q=2.77 and an orbital inclination of i= 79°.*** on all available times of light minimum,their orbital period changes are studied by using the O-C *** O-C diagram of LX Lyn reveals a cyclic oscillation with a period of about 14.84 yr and an amplitude of 0.0019 days,which can be explained by the light-travel time effect(LTTE) due to the presence of a third body with a minimum mass of0.06M_⊙.For V0853 Aur,it is discovered that the O-C diagram of the system also shows a cyclic oscillation with a period of 9.64 yr and an amplitude of 0.03365 *** cyclic oscillation of V0853 Aur can be attributed to the LTTE by means of a third body with a mass no less than 3.77M_⊙.The third body may play an important role in the formation and evolution of these systems.

关键词： stars:activity (stars:)binaries(including multiple):close (stars:)binaries:eclipsing (stars:)brown dwarfs stars:evolution stars:formation

Higher-order properties and extensions for indirect MRAC and APPC of linear systems

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Science China(Information Sciences) 2024年第4期67卷 218-238页

作者： Yanjun zhang Zhipeng zhang Jian SUN Lei WANG Kangkang zhang National Key Lab of Autonomous Intelligent Unmanned Systems Beijing Institute of Technology Beijing Institute of Technology Chongqing Innovation Center College of Control Science and Engineering Zhejiang University Department of Electrical and Electronic Engineering Imperial College London KIOS Research and Innovation Center of Excellence University of Cyprus

Recently, a reference derived some new higher-order output tracking properties for direct model reference adaptive control(MRAC) of linear time-invariant(LTI) systems: limt→∞ e~((i))(t) = 0, i = 1,..., n~*-1, where n~* and e~((i))(t) denote the relative degree of the system and the i-th derivative of the output tracking error, respectively. However, a naturally arising question involves whether indirect adaptive control(including indirect MRAC and indirect adaptive pole placement control) of LTI systems still has higher-order tracking properties. Such properties have not been reported in the literature. Therefore, this paper provides an affirmative answer to this question. Such higher-order tracking properties are new discoveries since they hold without any additional design conditions and, in particular, without the persistent excitation condition. Given the higher-order properties, a new adaptive control system is developed with stronger tracking features.(1) It can track a reference signal with any order derivatives being unknown.(2) It has higher-order exponential or practical output tracking properties.(3) Finally, it is different from the usual MRAC system, whose reference signal’s derivatives up to the n~* order are assumed to be known. Finally, two simulation examples are provided to verify the theoretical results obtained in this paper.

关键词： higher-order tracking indirect adaptive control model reference adaptive control adaptive pole placement control

Shells in the cabinet:four new species of Tellinidae(Mollusca:Bivalvia:Tellinoidea)identified from existing South China Sea collections

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Journal of Oceanology and Limnology 2024年第2期42卷 627-639页

作者： Yuyan zhang Junlong zhang School of Life Sciences Qingdao Agricultural UniversityQingdao 266109China Laboratory of Marine Organism Taxonomy and Phylogeny Qingdao Key Laboratory of Marine Biodiversity and ConservationInstitute of OceanologyChinese Academy of SciencesQingdao 266071China Marine Biological Museum Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China

Four species new to science were identified in the Tellinidae museum collections in the Marine Biological Museum of Chinese Academy of *** triquetra ***.,collected in 1981,has not previously been described or *** differs from other Pinguitellina species by its trigonal shape,rose-colored valve interior,and deep and wide pallial sinus,which is confluent with the pallial *** protuberangla *** a broad and deep dorsal corner,short and straight posterodorsal margin,comparatively large adductor scars,depressed and fragile shells,and deep socket at the anterior edge of the right *** minuta *** previously misidentified as Arcopella casta in *** is a new species based on its unique characteristics,which include small,fragile,inflated,translucent,and triangularly ovate-shaped shells with acuminated and convex *** the first species described in China within the genus Abranda Iredale,1924,Abranda xui *** internal ligaments and thin,fragile,and translucent elliptical shells with fine radials on the *** this study,we reorganized the species currently contained in the two genera Pinguitellina and Abranda and created keys to the known *** believe that numerous collected bivalve specimens have been overlooked in the South China Sea,and to date,mollusk has not been adequately ***,further exploration and analysis are required to understand species diversity in this area.

关键词： Abranda morphology Pinguitellina species diversity taxonomy Tellinidae

Polarization-driven multifunctional organohydrogels with strain sensitivity toward electromagnetic wave absorption

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Nano Research 2024年第6期17卷 5688-5697页

作者： Yunfei zhang Lei zhang Bingqian Zhou Yishan Gao Baoliang zhang School of Chemistry and Chemical Engineering Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Engineering and Research Center for Functional Polymers on Adsorption and Separation Sunresins New Materials Co.Ltd.Xi’an 710072China

Rapid advancements in flexible electronics and military applications necessitate high-performance electromagnetic wave(EMW)*** huge breakthroughs in achieving high-attenuation microwave absorption,conventional EMW absorbing materials have single function and ambiguous absorption ***,numerous gel-type absorbers are fabricated by introducing“regulators”into poly(acrylamide-co-acrylic acid)(P(AM-co-AA))networks through radical polymerization in a glycerol-water mixed *** dielectric constant and EMW absorption performance of the gels are precisely predicted by adjusting monomer concentration,the ratio of glycerol/water,and the content of the ***,A_(6)G_(20)T_(20)-2 exhibits promising absorption performance with a minimum reflection loss(RL_(min))of-33.8 dB at 12.4 *** effective absorption bandwidth(EAB)covers the entire X-band(8.2-12.4 GHz)at a thickness of 2.7 mm.A_(6)G_(20)T_(20)-2 also has sensitive deformation responses and excellent tensile strength,adhesiveness,self-healing and anti-freezing ***,this work not only provides insight into the polarization loss mechanism of the gels as the result of high correlation between EMW absorbing properties and molecular polarization,but also offers an important reference for developing functional protective materials because of the rich functionalities and efficient protective capabilities of the gels.

关键词： organohydrogels molecular polarization microwave absorption strain sensor

Unveiling the protective role of biofilm formation on the photoaging of microplastics

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Science China Technological Sciences 2024年第10期67卷 3067-3078页

作者： zhang HaiYu LIU Peng zhang JiaYu DAI JiaMin zhang XinRui zhang ZiXuan JIA HanZhong Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China Ministry of AgricultureCollege of Natural Resources and EnvironmentNorthwest A&F University Key Laboratory of Organic Compound Pollution Control Engineering School of Environmental and Chemical EngineeringShanghai University

In natural water, microplastics（MPs） inevitably undergo microbial colonization to form biofilm, while the effect of biofilm formation on the photoaging of MPs remains unknown. This study systematically investigated the photoaging behavior of disposable box-derived polypropylene（PPMPs） and polystyrene（PSMPs） mediated by formed biofilm in water. After incubating in Weihe water samples for 105 d, the biofilm was validated to form in PPMPs and PSMPs, with higher formation in PSMPs. In particular, biofilm formation inhibited the photoaging of PPMPs and PSMPs, with an 11.1% and 50.6% decrease in photooxidation compared to their virgin counterparts after 20 d of ultraviolet（UV） irradiation. Moreover, the photoaging route of MPs such as the reaction priority of functional groups（e.g., C–H, C=O, and benzene ring） was altered, indicating the important role of biofilm formation in the photoaging process of MPs. The protective effect of the biofilm was mainly caused by the role of optical light filters that absorbed UV energy by sacrificing themselves. Also, as the main attacker on MPs, the production of reactive oxygen species（ROS, mainly1O2and ·OH） was inhibited by biofilm, which was mainly responsible for the decreased photoaging of MPs. This study revealed the important role of biofilm in the photoaging process of MPs and suggested a higher resistance of（micro）plastics in natural water than that in the laboratory using pure MPs, which contributed to a deeper understanding of the environmental fate and pollution of MPs.

关键词： microplastics biofilm photoaging physical shielding reactive oxygen species

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Highly cycle-stable VOPO_(4)-based cathodes for magnesium ion batteries:Insight into the role of interlayer engineering in batteries performance

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Nano Research 2024年第7期17卷 6127-6138页

作者： Jiahe zhang Jing Shang Xiaojun zhang Ke Wang Yihe zhang Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid WastesNational Laboratory of Mineral MaterialsSchool of Materials Science and TechnologyChina University of Geosciences(Beijing)Beijing 100083China

It is the sluggish ion migration kinetics that seriously affects the practical performance of the magnesium ion *** though an electrode material design using rational interlayer engineering method could effectively solve this issue,the optimal interlayer distance remains ***,various VOPO_(4)-based electrodes with expanded interlayer spacing were fabricated and the relationship between interlayer structure and battery performance was *** analysis combined with computations unveils the existence of an optimal interlayer structure,as inadequate expansion failed to fully utilization of the material performance,while excessive expansion degraded the electrode *** them,the electrode with triethylene glycol(TEG)intercalation exhibited optimized performance,maintaining excellent cycling stability(191.3 mAh·g^(−1)after 800 cycles).Density functional theory(DFT)demonstrated the effectiveness and limitations to lowering the migration energy barrier by expanding the interlayer *** addition,systematic mechanism research revealed the Mg^(2+)storage process:The stepwise shuttling of Mg^(2+)along the directions that lie in(001)plane triggers two pairs of redox processes,namely V^(5+)/V^(4+)and V^(4+)/V^(3+).This study,regulation of layer spacing to achieve the best integrated performance of electrodes,could deepen the understanding of interlayer engineering and guide the design of advanced multivalent-ion batteries.

关键词： magnesium ion batteries layered electrodes interlayer engineering energy storage mechanisms high kinetics

Recent progress in carbene-catalyzed fluoroalkylation

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Science China Chemistry 2024年第8期67卷 2448-2460页

作者： Bei zhang Xuan zhang Jian Wang Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science and TechnologyNanjing 210044China School of Pharmaceutical Sciences Tsinghua UniversityBeijing 100084China

The fluoroalkyl fragment plays a vital role in various fields such as pharmaceuticals and materials science, and has a significant impact on human life not only on the present but also in the future. The insertion of fluoroalkyl groups into the chemical skeletons can cause considerable alternations in the chemical, physical and biological properties of molecules, which has attracted numerous scientists from different fields. This review focuses on N-heterocyclic carbene(NHC)-catalyzed fluoroalkylation reactions, providing a detailed analysis and summary of the achievements in the past two decades. Many successful examples clearly indicate that NHCs can catalyze the tranformation of fluoroalkylation reagents with various electronic characteristics, whether electrophilic, nucleophilic, or radical precursors. Herein, the fluoroalkylation reactions are classified based on different catalytic modes of NHCs: Lewis base catalysis, Umploung catalysis, radical catalysis and others. Meanwhile, by refining and systematically studying the contribution of NHC catalysis in fluoroalkylation reactions, this review is expected to provide valuable insights and enlightenment for related fields.

关键词： N-heterocyclic carbene fluoroalkylation radical catalysis

A variable structure passivity control method for elastic joint robots based on cascaded high-order state estimation

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Science China(Technological Sciences) 2024年第2期67卷 395-407页

作者： zhang JieXin NIE PingYun zhang Bo State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240China

Passivity-based controllers are widely used to facilitate physical interaction between humans and elastic joint robots,as they enhance the stability of the interaction ***,the joint position tracking performance can be limited by the structures of these controllers when the system is faced with uncertainties and rough high-order system state measurements(such as joint accelerations and jerks).This study presents a variable structure passivity(VSP)control method for joint position tracking of elastic joint robots,which combines the advantages of passive control and variable structure *** method ensures the tracking error converges in a finite time,even when the system faces *** method also preserves the passivity of the ***,a cascaded observer,called CHOSSO,is also proposed to accurately estimate high-order system states,relying only on position and velocity *** observer allows independent implementation of disturbance compensation in the acceleration and jerk estimation *** particular,the observer has an enhanced ability to handle fast time-varying disturbances in physical human-robot *** effectiveness of the proposed method is verified through simulations and experiments on a lower limb rehabilitation robot equipped with elastic joints.

关键词： motion control elastic joint robot finite-time convergence high-order system state estimation physical human-robot interaction