检索结果-南通市图书馆

Frontiers of Structural and Civil engineering 2024年第5期18卷 788-804页

作者： Dexiang Li Jingyu Huang college of Civil engineering Tongji UniversityShanghai 200092China National Maglev transportation engineering R&D Center Tongji UniversityShanghai 201804China

The high-speed maglev vehicle/guideway coupled model is an essential simulation tool for investigating vehicle dynamics and mitigating coupled *** improve its accuracy efficiently,this study investigated a hierarchical model updating method integrated with field ***,a high-speed maglev vehicle/guideway coupled model,taking into account the real effect of guideway material properties and elastic restraint of bearings,was developed by integrating the finite element method,multi-body dynamics,and electromagnetic levitation ***,simultaneous in-site measurements of the vehicle/guideway were conducted on a high-speed maglev test line to analyze the system response and structural modal *** the hierarchical updating,an Elman neural network with the optimal Latin hypercube sampling method was used to substitute the FE guideway model,thus improving the computational *** multi-objective particle swarm optimization algorithm with the gray relational projection method was applied to hierarchically update the parameters of the guideway layer and magnetic force layer based on the measured modal parameters and the electromagnet vibration,***,the updated coupled model was compared with the field measurements,and the results demonstrated the model’s accuracy in simulating the actual dynamic response,validating the effectiveness of the updating method.

关键词： high-speed maglev vehicle/guideway coupled model field measurement model updating neural network multi-objective optimization

Target Detection on Water Surfaces Using Fusion of Camera and LiDAR Based Information

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2024年第7期80卷 467-486页

作者： Yongguo Li Yuanrong Wang Jia Xie Caiyin Xu Kun Zhang college of engineering Science and Technology Shanghai Ocean UniversityShanghai201306China

To address the challenges of missed detections in water surface target detection using solely visual algorithms in unmanned surface vehicle(USV)perception,this paper proposes a method based on the fusion of visual and LiDAR point-cloud projection for water surface target ***,the visual recognition component employs an improved YOLOv7 algorithmbased on a self-built dataset for the detection of water surface *** algorithm modifies the original YOLOv7 architecture to a Slim-Neck structure,addressing the problemof excessive redundant information during feature extraction in the original YOLOv7 network ***,this modification simplifies the computational burden of the detector,reduces inference time,and maintains ***,to tackle the issue of sample imbalance in the self-built dataset,slide loss function is ***,this paper replaces the original Complete Intersection over Union(CIoU)loss function with the Minimum Point Distance Intersection over Union(MPDIoU)loss function in the YOLOv7 algorithm,which accelerates model learning and enhances *** mitigate the problem of missed recognitions caused by complex water surface conditions in purely visual algorithms,this paper further adopts the fusion of LiDAR and camera data,projecting the threedimensional point-cloud data from LiDAR onto a two-dimensional pixel *** significantly reduces the rate of missed detections for water surface targets.

关键词： Water surface target detection YOLOv7 joint calibration sensor fusion point-cloud projection

Analytical and Experimental Research on Wave Scattering by an Open-Type Rectangular Breakwater with Horizontal Perforated Plates

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of ocean University of China 2024年第5期23卷 1185-1201页

作者： HE Shuyue LIU Yong LI Huajun Fisheries college Ocean University of ChinaQingdao 266003China Shandong Province Key Laboratory of ocean engineering Ocean University of ChinaQingdao 266100China

This study proposes a novel open-type rectangular breakwater combined with horizontal perforated plates on both sides to enhance the sheltering effect of the rectangular box-type breakwaters against longer *** hydrodynamic characteristics of this breakwater are analyzed through analytical potential solutions and experimental *** quadratic pressure drop conditions are exerted on the horizontal perforated plates to facilitate assessing the effect of wave height on the dissipated wave energy of breakwater through the analytical *** hydrodynamic quantities of the breakwater,including the reflection,transmission,and energyloss coefficients,together with vertical and horizontal wave forces,are calculated using the velocity potential decomposition method as well as an iterative ***,the reflection and transmission coefficients of the breakwater are measured by conducting experimental tests at various wave periods,wave heights,and both porosities and widths of the horizontal perforated *** analytical predicted results demonstrate good agreement with the iterative boundary element method solution and measured *** influences of variable incident waves and structure parameters on the hydrodynamic characteristics of the breakwater are investigated through further calculations based on analytical *** indicate that horizontal perforated plates placed on the water surface for both sides of the rectangular breakwater can enhance the wave dissipation ability of the breakwater while effectively decreasing the transmission and reflection coefficients.

关键词： rectangular breakwater horizontal perforated plates analytical solution experimental test hydrodynamic characteristics

Effects of grain's shape-and size-polydispersities,orientation,and area fraction on tortuosity and permeability of 2D granular media

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第7期90卷 535-557页

作者： Ke Cao Huisu Chen Mohammad Iqbal Khan Mingqi Li Lin Liu Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China Department of Civil engineering College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia School of Civil and transportation engineering Hebei University of TechnologyTianjin 300401China college of Civil and transportation engineering Hohai UniversityNanjing210098China

The microstructure of granular media, including grain's shape- and size-polydispersities, orientation, and area fraction can potentially affect its permeability. However, few studies consider the coupling effects of these features. This work employs geometrical probability and stereology to establish quantitative relationships between the above microstructural features and the geometric tortuosity of the two-dimensional granular media containing superellipse, superoval, and polygon grains. Then the lattice Boltzmann method (LBM) is used to determine the permeabilities of these granular media. By combining the tortuosity model and the LBM-derived permeabilities, modified K–C equations are formulated to predict the permeability and the shape factor, considering the grain's shape- and size-polydispersities, orientation, and area fraction. The reliability of these methods can be verified by comparing them with both our simulations and available experimental, theoretical, and numerical data reported in the literature. The findings implicate that the tortuosity and permeability of the granular media are strongly correlated with the grain's shape, orientation, and area fraction but unaffected by the size polydispersity and spatial arrangement of grains. Only circularity is not enough to derive a unified formula for considering the impact of grain shape on tortuosity and permeability, other shape parameters need to be explored in the future.

关键词： Geometric tortuosity Konzey-Carman equation Shape and size ploydispersities Grain orientation Lattice Boltzmann method Granular media

Simplified design of nonlinear damper parameters and seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil engineering 2024年第7期18卷 1103-1116页

作者： Huihui LI Lifeng LI Rui HU Meng YE college of Civil and transportation engineering Shenzhen UniversityShenzhen 518060China Guangdong Provincial Key Laboratory of Durability for Marine Civil engineering Shenzhen UniversityShenzhen 518060China college of Civil engineering Hunan UniversityChangsha 410082China

Viscous dampers are widely used as passive energy dissipation devices for long-span cable-stayed bridges for mitigation of seismic load-induced ***,complicated finite element(FE)modeling,together with repetitive and computationally intensive nonlinear time-history analyses(NTHAs)are generally required in conventional design *** streamline the preliminary design process,this paper developed a simplified longitudinal double degree of freedom model(DDFM)for single and symmetric twin-tower cable-stayed *** on the proposed simplified longitudinal DDFM,the analytical equations for the relevant mass-and stiffness-related parameters and longitudinal natural frequencies of the structure were derived by using analytical and energy *** of the relationship between the nonlinear viscous damper parameters and the equivalent damping ratio was achieved through the equivalent linearization ***,the analytical equations of longitudinal seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers were *** on the developed simplified DDFM and suggested analytical equations,this paper proposed a simplified calculation framework to achieve a simplified design method of nonlinear viscous damper ***,the effectiveness and applicability of the developed simplified longitudinal DDFM and the proposed calculation framework were further validated through numerical analysis of a practical cable-stayed ***,the results indicated the following.1)For the obtained fundamental period and longitudinal stiffness,the differences between results of the simplified longitudinal DDFM and numerical analysis were only 2.05%and 1.5%,respectively.2)Relative calculation errors of the longitudinal girder-end displacement and bending moment of the bottom tower section of the bridge obtained from the simplified longitudinal DDFM were limited to less than 25%.3)The equivalent damping ratio of nonline

关键词： cable-stayed bridges viscous dampers simplified analytical model equivalent damping ratio seismic mitigation

A pressure-sensitive rheological origin of high friction angles of granular matter observed in NASA–MGM project

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第6期33卷 559-567页

作者：程晓辉肖世泽杨森赵乃峰 Alex Sixie Cao Department of Civil engineering Tsinghua UniversityBeijing 100084China college of transportation engineering Nanjing Tech UniversityNanjing 211816China Institute of Structural engineering ETH ZurichZurich 8092Switzerland

An abnormally high peak friction angle of Ottawa sand was observed in(National Aeronautics and Space Administration) NASA–(Mechanics of Granular Materials) MGM tests in microgravity conditions on the space shuttle. Previous investigations have been unsuccessful in providing a constitutive insight into this behavior of granular materials under extremely low effective stress conditions. Here, a recently proposed unified constitutive model for transient rheological behavior of sand and other granular materials is adopted for the analytical assessment of high peak friction angles. For the first time, this long-eluded behavior of sand is attributed to a hidden rheological transition mechanism, that is not only rate-sensitive, but also pressure-sensitive. The NASA–MGM microgravity conditions show that shear-tests of sand can be performed under abnormally low confining stress conditions. The pressure-sensitive behavior of granular shearing that is previously ignored is studied based on the μ(I) rheology and its variations. Comparisons between the model and the NASA microgravity tests demonstrate a high degree of agreement. The research is highly valid for pressure-sensitive and rate-dependent problems that occur during earthquakes, landslides, and space exploration.

关键词： granular matter microgravity pressure-sensitive NASA–MGM

Achieving high power factor in GaSb with intrinsically high mobility via Ge doping

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第10期43卷 5435-5441页

作者： Yan-Ci Yan Guo-Wei Wang Qi-Hong Xiong Xu Lu Peng Chen Wei Zou Deng-Feng Li Hong Wu Yun Zhou Xiao-Yuan Zhou School of Science Chongqing University of Posts and Telecommunications college of Physics Chongqing University college of ocean Science and engineering Shanghai Maritime University

The thermoelectric power factor is as crucial as their overall thermoelectric ***-based compounds are deemed to achieve high power factor owing to their intrinsically high mobility compared to classical thermoelectric ***,the carrier concentration of pristine GaSb is considerably lower than the optimum value,which hinders its ability to attain high electrical *** this paper,we present the investigations on the thermoelectric performance of p-type *** experimental results reveal that Ge doping can effectively tune the carrier concentration.

关键词： Carrier concentration

Characteristics and mechanism of Ni^(2+)and Cd^(2+)adsorption by recovered perlite from agar extraction residue

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical engineering 2024年第8期72卷 141-152页

作者： Juan Wang Yanbing Zhu Zedong Jiang Xiping Du Mingjing Zheng Lijun Li Hui Ni Yuanpeng Wang Zhipeng Li Qingbiao Li college of ocean Food and Biological engineering Jimei UniversityXiamen 361021China Fujian Provincial Key Laboratory of Food Microbiology and Enzyme engineering Xiamen 361021China Research Center of Food Biotechnology of Xiamen City Xiamen 361021China Xiamen ocean Vocational college Xiamen 361021China college of Chemistry and Chemical engineering Xiamen UniversityXiamen 361021China

Ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human *** of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the problem of resource utilization of solid waste from agar *** previous study confirmed that recovered perlite from agar extraction residue had better pore size and specific surface area than commercial ***,the adsorption efficiency and adsorption mechanism of recovered perlite were the main factors limiting its adsorption *** adsorption process of Ni^(2+)and Cd^(2+)by recovered perlite in aqueous solution was described by the pseudo-second-order kinetic equation,and the relevant adsorption mechanism was mainly *** with commercial perlite,the adsorption removal rate of Ni^(2+)and Cd^(2+)by enzymatic recovered perlite could reach 92.9%and 89.2%,respectively,and were improved by 12.63%and 13.03%.Langmuir isothermal adsorption model could better describe the isothermal adsorption process of recovered perlite on heavy metal Ni^(2+)and Cd^(2+),and the relevant adsorption mechanism was mainly monolayer *** X-ray photoelectron spectroscopy(XPS)results indicated that the decrease of Si—O Si^(2+)hydroxyl coordination bond and the increase of C—Si bond might make the binding effect of recovered perlite with heavy metals *** competitive adsorption of Ni^(2+)and Cd^(2+)by recovered perlite was still dominated by chemisorption and monolayer *** study was expected to provide a theoretical basis and technical support for the removal of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite from seaweed residue.

关键词： Agar extraction residue Recovered perlite Heavy metal ion Adsorption property

Numerical simulation of inlet placement on sewage characteristics in the rounded square aquaculture tank with single inlet

在线全文

学校读者我要写书评

暂无评论

Journal of oceanology and Limnology 2024年第4期42卷 1359-1382页

作者： Xiaozhong REN Yixuan HU Yinxin ZHOU Shupeng DU Wei SUN Hangfei LIU Chenxu ZHAO Ying LIU Key Laboratory of Environment Controlled Aquaculture(Dalian ocean University)Ministry of Education Dalian 116023China college of Marine Science and Environment Dalian Ocean UniversityDalian 116023China college of ocean and Civil engineering Dalian Ocean UniversityDalian 116023China Zhejiang University Hangzhou 310058China

To improve the self-cleaning ability of aquaculture tank and the efficiency of circulating water,physical and numerical experiments were conducted on the influence of inlet structure on sewage discharge in a rounded square aquaculture tank with a single *** on the physical model of the tank,analysis of how inlet structure adjustment affects sewage discharge efficiency and flow field characteristics was conducted to provide suitable flow field conditions for sinkable solid particle *** addition,an internal flow field simulation was conducted using the RNG k-εturbulence model in hydraulic drive *** a solid-fluid multiphase model was created to investigate how the inlet structure affects sewage collection in the rounded square aquaculture tank with single inlet and *** finding revealed that the impact of inlet structure is considerably affecting sewage *** conditions of C/B=0.07-0.11(the ratio of horizontal distance between the center of the inlet pipe and the tank wall(C)to length of the tank(B))andα=25°(αis the angle between the direction of the jet and the tangential direction of the arc angle)resulted in optimal sewage collection,which is similar to the flow field experiment in the rounded square aquaculture tank with single inlet and *** excellent correlation was revealed between sewage collection and fluid circulation stability in the aquaculture *** present study provided a reference for design and optimization of circulating aquaculture tanks in aquaculture industry.

关键词： rounded square aquaculture tank sewage collection characteristic inlet structure computational fluid dynamic

Facet effects on bimetallic ZnSn hydroxide microcrystals for selective electrochemical CO2 reduction

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2024年第8期9卷 1314-1320页

作者： Liu Han Cheng-wei Wang Shan-shan Luo Ying-tang Zhou Bing Li Ming Liu School of Chemistry and Chemical engineering Harbin Institute of Technology National engineering Research Center for Marine Aquaculture Marine Science and Technology CollegeZhejiang Ocean University

Employing crystal facets to regulate the catalytic properties in electrocatalytic carbon dioxide reduction reaction（eCO2RR） has been well demonstrated on electrocatalysts containing single metals but rarely explored for bimetallic systems. Here, we synthesize Zn Sn（OH）6（ZSO）microcrystals（MCs） with distinct facets and investigate the facet effects in eCO2RR. Electrochemical studies and in situ Fourier Transform Infrared Spectroscopy（in situ-FTIR） reveal that ZSO MCs produce mainly C1 products of HCOOH and CO. The {111} facet of the ZSO MCS exhibits higher selectivity and faradaic efficiency（FE） than that of the {100} facet over a wide range of potentials（-0.9 V ～-1.3 V versus RHE）. Density Functional Theory（DFT） calculations elucidate that the {111} facet is favorable to the adsorption/activation of CO2molecules,the formation of intermediate in the rate-determining step, and the desorption of C1 products of CO and HCOOH molecules.

关键词： ZnSn(OH) 6 Crystal facets Electrochemical carbon dioxide reduction C1 product Density functional theory