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Single-step-etched ultra-compact metamaterial grating coupler enabled by a hierarchical inverse design approach

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 119-126页

作者： Qiao Wang Ruiqi Luo nan liu Maojing Hou Bo Xiong Guandong liu Wei Ma Intelligent Network Research Institute Zhejiang LabHangzhou 311100China State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic EngineeringZhejiang UniversityHangzhou 310027China

With the concept of metamaterials introduced into integrated photonics,subwavelength structures have gained popularity for their ability to create devices with ultra-compact size,high performance,and versatile ***,traditional metamaterial design methods are usually based on empirical templates and physical approximations,lacking the ability to design free-form metamaterial structures and optimize entire devices *** this work,we propose a hierarchical inverse design approach that combines a conventional effective refractive index based metamaterial structures design with a follow-up global topology *** empirical metamaterial grating coupler design based on effective refractive index engineering faces inaccurate index extraction and insufficient approximation of wavevector matching conditions,which deteriorates coupling efficiency,especially for fully-etched devices with the decreased tapering ***,a subsequent overall topology optimization step can well compensate for the negative effect of the shrinking device footprint to increase the efficiency of the metamaterial grating *** demonstrate a 23μm×10μm ultra-compact metamaterial grating coupler with single-stepetched to couple light between a fiber and a 500 nm single-mode silicon waveguide in the *** measurement shows an insertion loss of 3.17 dB and a 3 dB bandwidth of 77 nm,making it the smallest footprint device ever reported.

关键词： waveguide hierarchical inverse

An analytical transient coal permeability model:Sorption non-equilibrium index-based swelling switch

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1175-1191页

作者： Xingxing liu Jishan liu Liang Chen Jinchang sheng Huimin Wang College of Civil and Transportation Engineering Hohai UniversityNanjing210098China School of Engineering The University of Western Australia35 Stirling HighwayCrawleyWA6009Australia College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing210098China

Long-term permeability experiments have indicated that sorption-induced swelling can switch from internal to bulk depending on the evolutive sorption ***,this sorption swelling switch mechanism has not been considered in current analytical permeability *** study introduces a normalized sorption non-equilibrium index(SNEI)to characterize the sorption status,quantify the dynamical variations of matrix swelling accumulation and internal swelling partition,and formulate the sorption swelling switch *** incorporation of this index into the extended total effective stress concept leads to an analytical transient coal permeability *** results show that the sorption swelling switch itself results in the permeability switch under stress-constrained conditions,while the confined bulk swelling suppresses the permeability recovery to the continuous reduction under displacement-constrained *** verifications show that current experimental observations correspond to the early stages of the transient process,and they could be extended to the whole process with these *** study demonstrates the importance of the sorption swelling switch in determining permeability evolution using simple boundary *** provides new insights into experimentally revealing the sorption swelling switch in the future,and underscores the requirement of a rigorous model for complex coupled processes in large-scale coal seams.

关键词： Coal permeability Sorption swelling switch Sorption non-equilibrium Boundary conditions

Chromosome-level genome assembly of Oncomelania hupensis: the intermediate snail host of Schistosoma japonicum

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Infectious Diseases of Poverty 2024年第1期13卷 16-26页

作者： Qin liu Lei Duan Yun-Hai Guo Li-Min Yang Yi Zhang Shi-Zhu Li Shan Lv Wei Hu nan-sheng Chen Xiao-Nong Zhou National Institute of Parasitic Diseases at Chinese Center for Disease Control and Prevention(Chinese Centerfor Tropical Diseases Research) NHC Key Laboratory of Parasite and Vector BiologyWHO Collaborating Centre for Tropical DiseasesNational Center for International Research on Tropical DiseasesNational Key Laboratory of Intelligent Tracking and Forecasting for Infectious DiseasesShanghai 200025People's Republic of China School of Global Health Chinese Center for Tropical Diseases ResearchShanghai Jiao Tong University School of MedicineShanghai 200025People's Republic of China School of Life Science Fudan UniversityShanghai 200438People's Republic of China CAS Key Laboratory of Marine Ecology and Environmental Sciences Institute of OceanologyChinese Academy of SciencesQingdaoShandong 266071People'sRepublicofChina

Background Schistosoma japonicum is a parasitic flatworm that causes human schistosomiasis, which is a significant cause of morbidity in China, the Philippines and *** hupensis (Gastropoda: Pomatiopsidae) is the unique intermediate host ofS. japonicum. A complete genome sequence ofO. hupensis will enable the fundamental understanding of snail biology as well as its co-evolution with theS. japonicum parasite. Assembling a high-quality reference genome ofO. hupehensis will provide data for further research on the snail biology and controlling the spread ofS. *** The draft genome was de novo assembly using the long-read sequencing technology (PacBio Sequel II) and corrected with Illumina sequencing data. Then, using Hi-C sequencing data, the genome was assembled at the chromosomal level. CAFE was used to do analysis of contraction and expansion of the gene family and CodeML module in PAML was used for positive selection analysis in protein coding *** A total length of 1.46 Gb high-qualityO. hupensis genome with 17 unique full-length chromosomes (2n = 34) of the individual including a contig N50 of 1.35 Mb and a scaffold N50 of 75.08 Mb. Additionally, 95.03% of these contig sequences were anchored in 17 chromosomes. After scanning the assembled genome, a total of 30,604 protein-coding genes were predicted. Among them, 86.67% were functionally annotated. Further phylogenetic analysis revealed thatO. hupensis was separated from a common ancestor ofPomacea canaliculata andBellamya purificata approximately 170 million years ago. Comparing the genome ofO. hupensis with its most recent common ancestor, it showed 266 significantly expanded and 58 significantly contracted gene families (P < 0.05). Functional enrichment of the expanded gene families indicated that they were mainly involved with intracellular, DNA-mediated transposition, DNA integration and transposase *** Integrated use of multiple sequencing technol

关键词： Schistosomiasis Schistosoma japonicum Oncomelania hupensis Chromosome-level genome

Accelerating H^(*)desorption of hollow Mo_(2)C nanoreactor via in-situ grown carbon dots for electrocatalytic hydrogen evolution

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Journal of Energy Chemistry 2024年第9期96卷 464-471页

作者： Mengmeng liu Yuanyuan Jiang Zhuwei Cao Lulu liu Hong Chen sheng Ye School of Materials and Chemistry Anhui Agricultural UniversityHefei 230036AnhuiChina

Molybdenum carbide(Mo_(2)C)is a promising non-noble metal electrocatalyst with electronic structures similar to Pt for hydrogen evolution reaction(HER).However,strong H^(*)adsorption at the Mo sites hinders the improvement of HER ***,we synthesized monodisperse hollow Mo_(2)C nanoreactors,in which the carbon dots(CD)were in situ formed onto the surface of Mo_(2)C through carburization *** to finite element simulation and analysis,the CD@Mo_(2)C possesses better mesoscale diffusion properties than Mo_(2)C *** optimized CD@Mo_(2)C nanoreactor demonstrates superior HER performance in alkaline electrolyte with a low overpotential of 57 mV at 10 mA cm^(−2),which is better than most Mo_(2)C-based ***,CD@Mo_(2)C exhibits excellent electrochemical stability during 240 h,confirmed by operando Raman and X-ray diffraction(XRD).Density functional theory(DFT)calculations show that carbon dots cause the d-band center of CD@Mo_(2)C to shift away from Fermi level,promoting water dissociation and the desorption of H^(*).This study provides a reasonable strategy towards high-activity Mo-based HER eletrocatalysts by modulating the strength of Mo–H bonds.

关键词： Mo_(2)C nanoreactor Carbon dots H^(*)desorption Electrocatalytic hydrogen evolution

A new species of Discostella guiyangensis ***.(Bacillariophyta,Stephanodiscales)from Guiyang,China:morphology and phylogeny

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Journal of Oceanology and Limnology 2024年第4期42卷 1312-1324页

作者： Yandan XIANG Fangru nan Xudong liu Shulian XIE John Patrick KOCIOLEK Qi liu School of Life Science Shanxi UniversityTaiyuan 030006China Department of Ecology and Evolutionary Biology and Museum of Natural History University of ColoradoBoulder CO 80309USA

We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular *** species is morphologically distinguished from other species by a relatively smooth and slightly recessed central area with marginal striae of unequal lengths forked near the *** fultoportulae and a single rimoportula are situated between every two costae or on the *** morphological characters and the concatenated data of rbc L and SSU rDNA indicate that Discostella guiyangensis is a unique and new *** to divergence time estimation analysis,Discostella guiyangensis is the oldest species among the Discostella species sequenced *** addition,we complement molecular data of Discostella asterocostata and Discostella stelligera.

关键词： Discostella morphology molecular analysis divergence time estimation new species

Adaptive Observer-Based Finite-Time Fault Tolerant Control for Non-Strict Feedback Systems

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Journal of Systems Science & Complexity 2024年第4期37卷 1526-1544页

作者： sheng Ning liu Yang CHI Ronghu AI Zidong College of Automation and Electronic Engineering Qingdao University of Science and TechnologyQingdao 266042China

This paper considers the adaptive finite-time control and observer design method for a class of non-strict feedback systems with unmeasurable states,unknown nonlinear dynamics and actuator *** this paper,an observer is proposed to estimate the unmeasurable states in finite-time based on adaptive technique and neural networks,while the actuator faults are not *** filter is used to solve the computational explosion and singularity problems caused by the traditional backstepping and non-strict feedback structure,*** the fault efficiency indicators in real systems are not available,two-layer neural networks are adopted,where the first network is to estimate the unknown nonlinearities of systems and the second one is to estimate fault efficiency indicators and unknown nonlinear *** proposed scheme guarantees that states are bounded through stability ***,two experiments including a numerical example and a spring-mass-damper system are given to verify the effectiveness of the proposed method.

关键词： Command filter fault tolerant control finite-time control non-strict systems two-layer neural networks

Experimental,Numerical,and Analytical Studies on the Bending of Mechanically Lined Pipe

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China Ocean Engineering 2024年第2期38卷 221-232页

作者： WEI Wen-bin YUAN Lin ZHOU Jia-sheng liu Zheng State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300072China School of Mechanical Engineering Tianjin UniversityTianjin 300072China

Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion *** installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole *** this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical *** types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,*** hydraulic expansion and bending experiments of small-scale MLPs are *** addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive *** contrast,the liner of ALP remains intact without developing any wrinkling and collapse *** addition,a dedicated numerical framework and theoretical models were also *** was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.

关键词： lined pipe bending nonlinear ring theory buckling plasticity

Hydrodynamics and OCM reaction performance in a bubbling fluidized bed reactor and a riser reactor

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Particuology 2024年第3期86卷 188-204页

作者： Min Cai Shuangzhu Kong sheng Chen Mengxi liu Chunxi Lu State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China China Special Equipment Inspection and Research Institute Beijing102249China

The reasonable reactor design is of great importance for increasing the C_(2) yield(C2H4 and C2H6)of the oxidative coupling of methane(OCM),and the OCM reactor should remove the heat released in reactions quickly and efficiently and minimize the consecutive reaction of ethylene to carbon *** fluidized bed reactor is characterized by excellent heat transfer,superior mass transport,and large handling capacity,while fewer studies focused on large-scale fluidized bed reactors for the OCM ***,large cold-model experiments and computational fluid dynamics simulations were conducted to investigate hydrodynamics and the OCM reaction performance in a large-scale bubbling fluidized bed(BFB)and a large-scale *** the BFB reactor,consecutive reactions of ethylene are acute because of the strong gas back-mixing,high solids holdup,and non-uniform solids *** the consecutive reactions of ethylene are negligible due to the plug flow structure and low solids holdup in the riser ***,both reactors can achieve isothermal operation for the OCM *** C_(2) selectivity of 45.4% and C_(2) yield of 21.1% are obtained in the riser reactor,increasing by 20.3% and 5.8% individually than that in the BFB *** study provides useful information and reference to the OCM reactor designandcommercialization.

关键词： Oxidative coupling of methane Bubbling fluidized bed reactor Riser reactor Hydrodynamics Isothermal operation

Regression Method for Rail Fastener Tightness Based on Center-Line Projection Distance Feature and Neural Network

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 356-371页

作者： Yuanhang Wang Duxin liu sheng Guo Yifan Wu Jing liu Wei Li Hongjie Wang Robotics Research Center School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China China Construction Industrial&Energy Engineering Group Co. Ltd.Nanjing 210023China

In the railway system,fasteners have the functions of damping,maintaining the track distance,and adjusting the track ***,routine maintenance and inspection of fasteners are important to ensure the safe operation of track ***,assessment methods for fastener tightness include manual observation,acoustic wave detection,and image *** are limitations such as low accuracy and efficiency,easy interference and misjudgment,and a lack of accurate,stable,and fast detection *** at the small deformation characteristics and large elastic change of fasteners from full loosening to full tightening,this study proposes high-precision surface-structured light technology for fastener detection and fastener deformation feature extraction based on the center-line projection distance and a fastener tightness regression method based on neural ***,the method uses a 3D camera to obtain a fastener point cloud and then segments the elastic rod area based on the iterative closest point algorithm *** component analysis is used to calculate the normal vector of the segmented elastic rod surface and extract the point on the centerline of the elastic *** point is projected onto the upper surface of the bolt to calculate the projection ***,the mapping relationship between the projection distance sequence and fastener tightness is established,and the influence of each parameter on the fastener tightness prediction is ***,by setting up a fastener detection scene in the track experimental base,collecting data,and completing the algorithm verification,the results showed that the deviation between the fastener tightness regression value obtained after the algorithm processing and the actual measured value RMSE was 0.2196 mm,which significantly improved the effect compared with other tightness detection methods,and realized an effective fastener tightness regression.

关键词： Railway system Fasteners Tightness inspection Neural network regression 3D point cloud processing