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Numerical study of submerged bending vegetation under unidirectional flow

Water Science and Engineering 2024年第1期17卷 92-100页

作者： Pei-pei Zhang Yi-qing gong Ken Vui Chua Jie Dai Jing-qiao Mao College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China Institute of Water Science and Technology Hohai UniversityNanjing 210098China School of Engineering Cardiff UniversityCardiff CF243AAUK

Submerged vegetation commonly grows and plays a vital role in aquatic ecosystems,but it is also regarded as a barrier to the passing *** simulations of flow through and over submerged vegetation were carried out to investigate the effect of vegetation density on flow *** simulations were computationally set up to replicate flume experiments,in which vegetation was mimicked with flexible plastic *** fluid-structure interaction between flow and flexible vegetation was solved by coupling the two modules of the COMSOL *** cases with different vegetation densities were simulated,and the results were successfully validated against the experimental *** contours of the simulated time-averaged streamwise velocity and Reynolds stress were extracted to highlight the differences in mean and turbulent flow *** turbulence intensity was found to be more sensitive to vegetation density than the time-averaged *** developing length increased with the spacing between *** snapshots of the bending vegetation under instantaneous velocity and vorticity revealed that flexible vegetation responded to the effects of eddies in the shear layer by swaying *** first two rows of vegetation suffered stronger approaching flow and were prone to more streamlined *** addition,the origin of tip vortices was investigated via the distribution of *** results reveal the variation of flow properties with bending submerged vegetation and provide useful reference for optimizationofrestorationprojects.

关键词： Computational fluid dynamics Fluid-structure interaction Turbulence Flexible and submerged vegetation

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Spin‑controlled topological phase transition in non‑Euclidean space

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Frontiers of Optoelectronics 2024年第1期17卷 67-76页

作者： Zhuochen Du Jinze Gao Qiuchen yan Cuicui Lu Xiaoyong Hu Qihuang gong State Key Laboratory for Mesoscopic Physics and Department of Physics Collaborative Innovation Center of Quantum Matter and Frontiers Science Center for Nano‑OptoelectronicsBeijing Academy of Quantum Information SciencesPeking UniversityBeijing 100871China Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic SystemsSchool of PhysicsBeijing Institute of TechnologyBeijing 100081China Peking University yangtze Delta Institute of Optoelectronics Nantong 226010China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Hefei National Laboratory Hefei 230088China

Modulation of topological phase transition has been pursued by researchers in both condensed matter and optics research fields,and has been realized in Euclidean systems,such as topological photonic crystals,topological metamaterials,and coupled resonator ***,the spin-controlled topological phase transition in non-Euclidean space has not yet been ***,we propose a non-Euclidean configuration based on Mobius rings,and we demonstrate the spin-controlled transition between the topological edge state and the bulk *** Mobius ring,which is designed to have an 8πperiod,has a square cross section at the twist beginning and the length/width evolves adiabatically along the loop,accompanied by conversion from transverse electric to transverse magnetic modes resulting from the spin-locked *** 8πperiod Mobius rings are used to construct Su–Schrieffer–Heeger configuration,and the configuration can support the topological edge states excited by circularly polarized light,and meanwhile a transition from the topological edge state to the bulk state can be realized by controlling circular *** addition,the spin-controlled topological phase transition in non-Euclidean space is feasible for both Hermitian and non-Hermitian cases in 2D *** work provides a new degree of polarization to control topological photonic states based on the spin of Mobius rings and opens a way to tune the topological phase in non-Euclidean space.

关键词： Topological phase transition Non-Euclidean space Möbius ring Spin-locked effect

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Flow Field Characteristics of Multi-Trophic Artificial Reef Based on Computation Fluid Dynamics

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Journal of Ocean University of China 2024年第2期23卷 317-327页

作者： HUANG Junlin LI Jiao LI yan gong Pihai GUAN Changtao XIA Xu School of Engineering Ocean University of ChinaQingdao 266100China Yellow Sea Fisheries Research Institute Chinese Academy of Fishery SciencesKey Laboratory of Sustainable Development of Marine FisheriesMinistry of Agriculture and Rural AffairsQingdao Key Laboratory for Marine Fish Breeding and BiotechnologyQingdao 266071China Laboratory for Marine Fisheries Science and Food Production Processes Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266071China

On the basis of computational fluid dynamics,the flow field characteristics of multi-trophic artificial reefs,including the flow field distribution features of a single reef under three different velocities and the effect of spacing between reefs on flow scale and the flow state,were *** indicate upwelling,slow flow,and eddy around a single *** velocity,height,and volume of upwelling in front of a single reef were positively correlated with inflow *** length and volume of slow flow increased with the increase in inflow *** were present both inside and backward,and vorticity was positively correlated with inflow *** between reefs had a minor influence on the maximum velocity and height of *** the increase in space from 0.5 L to 1.5 L(L is the reef lehgth),the length of slow flow in the front and back of the combined reefs increased *** the space was 2.0 L,the length of the slow flow *** four different spaces,eddies were present inside and at the back of each *** maximum vorticity was negatively correlated with space from 0.5 L to 1.5 L,but under 2.0 L space,the maximum vorticity was close to the vorticity of a single reef under the same inflow velocity.

关键词： artificial reef flow field characteristics computation fluid dynamics multi-trophic structure

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Unusual photocarrier and coherent phonon dynamics behaviors of layered PdSe_(2)unveiled by ultrafast spectroscopy of the edge surface

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 143-152页

作者： Tiantian Yun Changfu Huo Jinluo Cheng Zhi-Bo Liu Xiao-qing yan Key Laboratory of Weak-Light Nonlinear Photonics Ministry of EducationSchool of PhysicsNankai UniversityTianjin 300071China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China GPL Photonics Laboratory Key Laboratory of Luminescence Science and TechnologyChinese Academy of Sciences&State Key Laboratory of Luminescence Science and ApplicationsChangchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China

Layered materials exhibit different electronic and phonon properties along in-plane and out-of-plane directions;existing studies focus on their in-plane behaviors,and the influence of such anisotropies on the dynamics of photocarriers and phonons is ***,we fabricate layered PdSe_(2)crystals with flat edge surfaces and compare the time-resolved ultrafast spectroscopies on their basal and edge *** differences in the transient reflection spectroscopies reveal the inconsistent photocarrier and phonon dynamics behaviors on the two surfaces:the slow hot carrier relaxation process is accelerated and the thermoelasticity-induced longitudinal coherent acoustic phonon oscillation completely vanishes on the edge surface,as compared with the basal *** analysis reveals that the inconsistent hot carrier dynamics originate from the anisotropic properties of low-energy phonons in PdSe_(2),and the absence of phonon oscillation on the edge surface results from the wavevector-limited sensitivity of acoustic B_(1u)***,polarization-dependent spectroscopies indicate the diverse optical anisotropies beyond the in-plane of PdSe_(2).This work provides a new method to explore unique physical properties and modulate the optical anisotropy of layered materials.

关键词： PdSe_(2) ultrafast spectroscopy edge surface carrier dynamics coherent phonon oscillation anisotropy

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Flexible assistance strategy of lower limb rehabilitation exoskeleton based on admittance model

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Science China(Technological Sciences) 2024年第3期67卷 823-834页

作者： KOU JianGe WANG YiXuan CHEN ZhenLei SHI yan GUO qing XU Meng School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China School of Aeronautics and Astronautics University of Electronic Science and Technology of ChinaChengdu 611731China Department of Musculoskeletal Tumor Senior Department of Orthopedicsthe Fourth Medical Centerof PLA GeneralHospitalBeijing 100853China

Exercise training based on exoskeleton is an effective rehabilitation method for stroke patients. However, some rehabilitation exoskeletons still have poor wearable performance and obvious human-robot impedance during training, which easily cause secondary injuries to the patients. In this study, a variable admittance control strategy is proposed to improve the operator's wearable comfort, which can adapt to different operators by regulating admittance parameters. The admittance controller has two feedback loops: the position inner-loop and the admittance outer-loop. Meanwhile, the exoskeleton Lagrange model is constructed with unknown friction disturbance. By using Lyapunov technique and backstepping with state observer, the joint position error of exoskeleton is convergence into a zero neighborhood. The effectiveness of the proposed admittance controller is verified by both simulation and experiment. The tracking error of hip and knee joint is less than 4 degrees while the human-robot interaction torque is constrained in a tolerable range of the operator.

关键词： human-robot interaction exoskeleton backstepping admittance control

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Tailoring electron vortex beams with customizable intensity patterns by electron diffraction holography

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Opto-Electronic Advances 2024年第2期7卷 14-21页

作者： Pengcheng Huo Ruixuan Yu Mingze Liu Hui Zhang yan-qing Lu Ting Xu National Laboratory of Solid-State Microstructures and Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China College of Engineering and Applied Sciences Key Laboratory of Intelligent Optical Sensing and Manipulation and Jiangsu Key Laboratory of Artificial Functional MaterialsNanjing UniversityNanjing 210093China

An electron vortex beam(EVB) carrying orbital angular momentum(OAM) plays a key role in a series of fundamental scientific researches, such as chiral energy-loss spectroscopy and magnetic dichroism spectroscopy. So far, almost all the experimentally created EVBs manifest isotropic doughnut intensity patterns. Here, based on the correlation between local divergence angle of electron beam and phase gradient along azimuthal direction, we show that free electrons can be tailored to EVBs with customizable intensity patterns independent of the carried OAM. As proof-of-concept, by using computer generated hologram and designing phase masks to shape the incident free electrons in the transmission electron microscope, three structured EVBs carrying identical OAM are tailored to exhibit completely different intensity patterns. Furthermore, through the modal decomposition, we quantitatively investigate their OAM spectral distributions and reveal that structured EVBs present a superposition of a series of different eigenstates induced by the locally varied geometries. These results not only generalize the concept of EVB, but also demonstrate an extra highly controllable degree of freedom for electron beam manipulation in addition to OAM.

关键词： electron vortex beam orbital angular momentum diffraction holography

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Enhancement of comprehensive properties of Nb-Si based in-situ composites by Ho rare earth doping

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Rare Metals 2024年第9期43卷 4508-4520页

作者： Wei Wei Qi Wang Rui-Run Chen Chao-Wen Zheng yan-qing Su National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China

This study examines the microstructure,mechanical properties(with a focus on room-temperature toughness),and oxidation resistance of Ho-doped NbDSi based in-situ *** base alloy consists of the coarse primary Nb_(5)Si_(3)phase and the Nb_(5)Si_(3)+Nbss(Nb solid solution)eutectic *** doping influences the solidification *** the Ho doping is higher than0.2 at%,the alloys transform into eutectic *** can be solid-solved in trace amounts in the Nbss ***,most of Ho forms a stable Ho oxide phase,which alleviates oxygen contamination problem to some ***,the interface separation between Ho oxide and other phases reduces the plastic deformation ***,with 0.4 at%Ho doping,the K_(Q)value is18.03 MPa·m^(1/2),which is 31.1%higher than that of the base *** strength of the Ho-doped alloys does not deteriorate with an increase in ***,the large network-like Ho_(2)O_(3)in the 0.8Ho alloy causes a decrease in toughness and *** addition,the Ho oxide phase effectively blocks the inward oxygen *** 0.8 at%Ho doping,the oxidation mass gain per unit area is 10.16 mg·cm^(2),which is 39.7%lower than that of the base alloy.

关键词： Nb-Si based composites Rare earth elements Ho Microstructure Properties

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Distributed Platooning Control of Automated Vehicles Subject to Replay Attacks Based on Proportional Integral Observers

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 1954-1966页

作者： Meiling Xie Derui Ding Xiaohua Ge qing-Long Han Hongli Dong yan Song Department of Control Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourne VIC 3122Australia Artificial Intelligence Energy Research Institute Northeast Petroleum UniversityDaqing 163318the Heilongjiang Provincial Key Laboratory of Networking and Intelligent ControlNortheast Petroleum UniversityDaqing 163318 Sanya Offshore Oil&Gas Research Institute Northeast Petroleum UniversitySanya 572024China

Secure platooning control plays an important role in enhancing the cooperative driving safety of automated vehicles subject to various security *** paper focuses on the distributed secure control issue of automated vehicles affected by replay attacks.A proportional-integral-observer(PIO)with predetermined forgetting parameters is first constructed to acquire the dynamical information of ***,a time-varying parameter and two positive scalars are employed to describe the temporal behavior of replay *** light of such a scheme and the common properties of Laplace matrices,the closed-loop system with PIO-based controllers is transformed into a switched and time-delayed ***,some sufficient conditions are derived to achieve the desired platooning performance by the view of the Lyapunov stability *** controller gains are analytically determined by resorting to the solution of certain matrix inequalities only dependent on maximum and minimum eigenvalues of communication ***,a simulation example is provided to illustrate the effectiveness of the proposed control strategy.

关键词： Automated vehicles platooning control proportional-integral-observers(PIOs) replay attacks time-delays

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Low Concentration of Wenyang Tonglin Decoction Promotes Conjugation and Transfer of Drug-Resistant Plasmids among Heterologous Strains

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Chinese Journal of Integrative Medicine 2024年第8期30卷 721-728页

作者： WANG Bi-yan BU Hong-shi XIA Li-bo JIANG Xiang-yu TONG yan-qing Department of Traditional Chinese Medicine Changchun University of Traditional Chinese MedicineChangchun130000China

Objective To investigate the effect of low concentration of Wenyang Tonglin Decoction(WTD)on the binding conditions of R45 plasmid conjugative transfer under liquid phase conjugation and its *** Escherichia coli CP9(R45)and Staphylococcus aureus RN450RF were cultured in medium containing WTD,and their minimum inhibitory concentration(MIC)values were *** promoter fusion technology,*** CP9(R45)containing a promoter fusion was obtained.β-Galactosidase activity of TrfAp and TrbBp was tested,and the mRNA expression of regulatory factors(TrbA,KorA,and KorB)was detected by real-time fluorescent quantitative polymerase chain *** The MIC of *** CP9(R45)was 400 g/L and that of *** RN450RF was 200 g/*** the drug concentration in the culture medium was 200 g/L,the highest number of conjugants was(3.47±0.20)×10^(7) CFU/mL At 90 h of conjugation,the maximum number of conjugants was(1.15±0.06)×10^(8) CFU/mL When the initial bacterial concentration was 10^(8) CFU/mL,the maximum number of conjugants was(3.47±0.20)×10^(7) CFU/*** the drug concentration was 200 g/L,theβ-galactosidase activity of TrfAp and TrbBp significantly increased;the relative quantification of TrbA,KorA and KorB were significantly *** Low concentration of WTD promoted the development of bacterial resistance by affecting promoters and inhibiting the expression of regulatory factors.

关键词： urinary tract infection Chinese medicine drug-resistant plasmid heterozygous strains conjugation transfer

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鼠尾藻hsp70基因的克隆及温度、盐度对其表达的影响

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中国海洋大学学报（自然科学版） 2017年第11期47卷 24-30页

作者：徐群刘岩宫庆礼海水养殖教育部重点实验室(中国海洋大学) 山东青岛266003

为研究温度、盐度及其处理时间对鼠尾藻(Sargassum thunbergii)hsp70表达水平的影响,以β-actin为内参基因,通过RT-qPCR测定不同处理下鼠尾藻幼苗的hsp70表达水平。温度实验设置7个处理组(5、10、15、25、30、35和40℃)、盐度实验设置5... 详细信息

为研究温度、盐度及其处理时间对鼠尾藻(Sargassum thunbergii)hsp70表达水平的影响,以β-actin为内参基因,通过RT-qPCR测定不同处理下鼠尾藻幼苗的hsp70表达水平。温度实验设置7个处理组(5、10、15、25、30、35和40℃)、盐度实验设置5个处理组(0、10、20、40和50),以温度20℃、盐度31为对照组;温度处理时间实验在温度35℃下热激不同时间(0、1、2、3、4、6、8、10和12h),盐度处理时间实验在盐度50下处理不同时间(0、1、2、3、4、6、8、10和12h)。研究显示:(1)在不同温度下处理鼠尾藻幼苗1h,40℃组的hsp70表达水平最高,是对照组(20℃)的8.6倍,恢复处理1h后,5℃组与对照组差异不显著,35、40℃组与对照组仍差异显著;(2)鼠尾藻幼苗在(0、10、20、31、40、50)盐度下处理2h,发现0、10、40、50盐度组的hsp70表达水平显著高于对照组,恢复处理2h后,0盐度组鼠尾藻幼苗的hsp70表达水平最高;(3)将鼠尾藻幼苗在35℃下热激不同时间,样品的hsp70表达水平先上升后下降,热激4h时表达量最大,不同热激时间处理组在20℃中恢复1h后,处理1、2和3h的实验组在恢复后hsp70表达水平高于相应的处理组;(4)将鼠尾藻幼苗在盐度50中培养不同时间,样品的hsp70表达水平先升高后下降,在6h时达到最高,不同盐度时间处理组在盐度31下恢复2h后,其hsp70表达水平变化情况与35℃热激不同时间各处理组的变化趋势相同。研究结果表明,在本研究中,鼠尾藻hsp70表达水平在温度40℃、盐度50、高温热激4h和高盐处理6h情况下分别达到最大值,调控效果显著,说明HSP70可能参与了各胁迫下的生物代谢和抗逆反应。

关键词：鼠尾藻 hsp70基因温度盐度胁迫荧光定量PCR

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