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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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Novel models for simulating maize growth based on thermal time and photothermal units: Applications under various mulching practices

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Journal of Integrative Agriculture 2023年第5期22卷 1381-1395页

作者： LIAO Zhen-qi ZHENG Jing FAN Jun-liang pei Sheng-zhao dai Yu-long ZHANG Fu-cang LI Zhi-jun Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas Ministry of EducationNorthwest A&F UniversityYangling 712100P.R.China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041P.R.China

Maize (Zea mays L.) is one of the three major food crops and an important source of carbohydrates for maintaining food security around the *** height (H),stem diameter (SD),leaf area index (LAI) and dry matter (DM) are important growth parameters that influence maize ***,the combined effect of temperature and light on maize growth is rarely considered in crop growth *** maize growth models based on the modified logistic growth equation (Mlog) and the Mitscherlich growth equation (Mit) were proposed to simulate the H,SD,LAI and DM of maize under different mulching practices based on experimental data from 2015–*** the accumulative growing degree-days (AGDD),helio thermal units (HTU),photothermal units (PTU) or photoperiod thermal units (PPTU,first proposed here) was used as a single driving factor in the models;or AGDD was combined with either accumulative actual solar hours (ASS),accumulative photoperiod response (APR,first proposed here) or accumulative maximum possible sunshine hours (ADL) as the dual driving factors in the *** model performances were evaluated using seven statistical indicators and a global performance *** results showed that the three mulching practices significantly increased the maize growth rates and the maximum values of the growth curves compared with *** the four single factor-driven models,the overall performance of the Mlog_(PTU)Model was the best,followed by the Mlog_(AGDD)*** Mlog_(PPTU)Model was better than the Mlog_(AGDD)Model in simulating SD and *** the 10 models,the overall performance of the Mlog_(AGDD–APR)Model was the best,followed by the Mlog_(AGDD–ASS)***,the Mlog_(AGDD–APR)Model performed the best in simulating H and LAI,while the Mlog_(AGDD–ADL)and Mlog_(AGDD–ASS)models performed the best in simulating SD and DM,*** conclusion,the modified logistic growth equations with AGDD and either APR,ASS or ADL as the dual driving

关键词： thermal time accumulative growing degree-days helio thermal units photothermal units growth model

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GYK运行记录智能分析系统研究

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铁道通信信号 2025年第1期61卷 42-48页

作者：杨云李辉戴博徐亮中国国家铁路集团有限公司工电部北京100844 中国铁道科学研究院集团有限公司通信信号研究所北京100081 北京华铁信息技术有限公司北京100081 高新兴创联科技股份有限公司杭州310013

针对目前GYK运行记录分析主要采用人工分析和统计方式,存在误看、漏看等人为差错,以及日渐增加的轨道车需要投入大量人力等问题,探索性地开展了GYK运行记录智能分析系统的研究。该系统由浏览器用户终端和服务平台组成,采用B/S架构,基于J... 详细信息

针对目前GYK运行记录分析主要采用人工分析和统计方式,存在误看、漏看等人为差错,以及日渐增加的轨道车需要投入大量人力等问题,探索性地开展了GYK运行记录智能分析系统的研究。该系统由浏览器用户终端和服务平台组成,采用B/S架构,基于J2EE技术框架开发,综合运用K-means聚类算法、Apriori算法等,对GYK运行记录中的关键项点进行智能分析,并自动给出分析结论,可提高GYK运行记录数据分析的工作效率,及时发现违章行为,促进标准化作业,进而加强对轨道车的安全运用管理。该系统已通过国铁集团技术评审,能够满足GYK运行记录智能分析工作的需要。

关键词：轨道车运行控制设备运行记录智能分析 K-means聚类算法 Apriori算法标准化作业

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Drag-reduction of 3D printed shark-skin-like surfaces

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Friction 2019年第6期7卷 603-612页

作者： Wei dai Masfer ALKAHTANI Philip RHEMMER Hong liang Department of Mechanical Engineering Texas A&M UniversityCollege StationTX 77843USA Institute for Quantum Science and Engineering(IQSE) Texas A&M UniversityCollege StationTX 77843USA Center for Quantum Optics and Quantum Informatics KACSTRiyadh 11442Saudi Arabia Department of Electrical and Computer Engineering Texas A&M UniversityCollege StationTX 77843USA

The marvels of the slippery and clean sharkskin have inspired the development of many clinical and engineering products, although the mechanisms of interfacial interaction between the sharkskin and water have yet to be fully understood. In the present research, a methodology was developed to evaluate morphological parameters and to enable studying the effects of scale orientation on the fluidic behavior of water. The scale orientation of a shark skin was defined as the angle between the ridges and fluid flow direction. Textured surfaces with a series orientation of scales were designed and fabricated using 3 D printing of acrylonitrile butadiene styrene(ABS). The fluid drag performance was evaluated using a rheometer. Results showed that the shark–skin-like surface with 90 degree orientation of scales exhibited the lowest viscosity drag. Its maximum viscosity reduction was 9%. A viscosity map was constructed based on the principals of fluid dynamic. It revealed that the drag reduction effect of a shark-skin-like surface was attributed to the low velocity gradient. This was further proven using diamond nitrogen-vacancy sensing where florescent diamond particles were distributed evenly when the velocity gradient was at the lowest. This understanding could be used as guidance for future surface design.

关键词： shark skin 3D printing textured surface drag reduction nitrogen vacancy

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Cenozoic tectonic and geomorphic evolution of the Longxi region in northeastern Tibetan Plateau interpreted from detrital zircon

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Science China Earth Sciences 2017年第2期60卷 256-267页

作者： WANG ZhiXiang liang MeiYan SUN YuQi dai GaoWen State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Wuhan 430074 China Laboratory of Critical Zone Evolution School of Earth Sciences China University ofGeosciences Wuhan 430074 China Department of Regional Planning and Geoinformatical Technology School of Public Administration China University of Geoscienees Wuhan 430074 China Laboratory of Geographical Environment and National Park School of Public Administration China University of Geoscience Wuhan 430074. China

The Longxi region contains different kinds of Cenozoic sediments, including eolian deposits, reworked loess, fluvial and lacustrine deposits. The provenance evolution of these sediments is of great significance in exploring the uplift, tectonic deformation and associated with geomorphic evolution of the Northeastern Tibetan Plateau. In this paper, we used the single-grain zircon provenance analysis to constrain the provenances for the Paleogene alluvial conglomerates and for the Neogene fluvial-lacustrine sediments, and compared them with results from the loess deposits since the Miocene. The results show that：（1） the Paleogene alluvial conglomerates contain a large number of detrital zircons ranging from 560 to 1100 Ma that were derived from the Yangzi Block. However, the sediments of early Miocene have much fewer zircons of this age span, which are characterized by an abundance of zircon ages in the ranges of 200 360 Ma. This indicates that the Paleogcne alluvial conglomerates mainly come from the middle and/or southern West Qinling, and the early Miocene sediments are primarily from the northern West Qinling; （2） Late Neogene fluvial sediments （11.5 Ma onward） in Tianshui-Qinan region are dominated by zircon ages of 380-450 Ma. This zircon population is similar to that of the exposed intrusive rocks of southern part of the Liupan Mountains, implying that the southern part of Liupan Mountains probably had already uplifted by 11.5 Ma; （3） Late Miocene lacustrine sediments in Tianshui region have a zircon age spectra that is remarkably different from coeval fluvial deposits, but is similar to the zircon age distributions of the Miocene loess in Qinan region, late Miocene-Pliocene Hipparion red clay and Quaternary loess. This indicates that fine particles within these Miocene lacustrine sediments in Tianshui region may be dominated by aeolian materials. This study reveals that provenance changes of Cenozoic sediments in Tianshui-Qinan region and its geomorphic evolu

关键词： Detrital zircon Provenance Tectonic uplift Geomorphic evolution Tianshui-Qinan region

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Microstructure and mechanical properties of friction stir welding joint during post weld heat treatment with different zigzag lines

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Rare Metals 2019年第11期38卷 1070-1077页

作者： Zhi-Li Hu Qiu Pang Ming-liang dai Hubei Key Laboratory of Advanced Technology of Automobile Components Wuhan University of TechnologyWuhan 430070China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of TechnologyWuhan 430070China School of Mechanical and Electrical Engineering Wuhan Donghu UniversityWuhan 430212China

Zigzag line is a common defect in friction stir welding(FSW) *** formation mechanism of the zigzag line in Al-Cu alloy FSW joint and its influence on the microstructure and mechanical properties during post weld heat treatment(PWHT) were studied by scanning electron microscopy(SEM),microhardness and tensile *** is found that the occurrence of zigzag line for PWHT joint is determined by PWHT process which in nature depends on residual stress and thermal stress of FSW *** optimization of PWHT process to reduce the residual and thermal stress can trigger for the deterioration of mechanical properties of PWHT joints with zigzag *** obvious decrease of tensile properties is observed for T6-450 and T6-495 joints although zigzag line appears in the *** determines the sizes of zigzag line cracks and consequently determines the fracture location and characteristics of FSW joint.

关键词： Friction stir welding Post weld heat treatment Zigzag line Mechanical properties

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Improved model for defect detection in photovoltaic cells based on Yolov5

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Optoelectronics Letters 2025年

作者： BAI Xinfeng XUE Yuming dai Hongli WANG Luoxin BAI Xin HU Xiaofeng Institute of New Energy Intelligence Equipment， School of Integrated Circuit Science and Engineering， Tianjin University of Technology

In order to meet the requirements of recognition speed and accuracy for complex photovoltaic (PV) cell defect detection tasks， this paper proposed an improvement strategy based on the Yolov5 network model. First， the model's ability to localize defects was enhanced by adding shallow feature inputs to strengthen the model's fusion of shallow feature information; second， the Squeeze-and-excitation (SE) attention mechanism was introduced to expand the receptive field and strengthen the dependency between feature channels; finally， a smoothing downsampling module was constructed to replace the convolutional sampling， which reduced the loss of information while retaining the important features. The experimental results show that the Yolov5 model based on this improved strategy achieved an average accuracy of 92.06% in the multiclassification defect detection task， and the average recognition speed reached 25.31 frames per second (FPS)， which took into account the requirements of performance and real-time performance， and can satisfy the needs of PV cell defect detection in industrial scenarios.

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The effects of selenization conditions on the microstructure and optoelectronic properties of CZTSSe absorber layers prepared by the sol-gel method

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Optoelectronics Letters 2025年

作者： BAI Xin XUE Yuming dai Hongli WANG Luoxin BAI Xinfeng HU Xiaofeng Institute of New Energy Intelligence Equipment， School of Integrated Circuit Science and Engineering， Tianjin University of Technology

Cu2ZnSnSSe4（CZTSSe） thin film solar cells， with adjustable bandgap and rich elemental content， hold promise in next-gen photovoltaics. Crystalline quality is pivotal for efficient light absorption and carrier transport. During the post-selenization process， understanding crystal growth mechanisms， and improving layer quality are essential. We explored the effects of ramp rate and annealing temperature on CZTSSe films， using XRD， Raman， SEM， and UV-Vis. The optimal performance occurred at 25.25 ℃/min ramp rate and 530℃ annealing. This led to smoother surfaces， higher density， and larger grains. This condition produced a single-layer structure with large grains， no secondary phases， and a 1.14 eV bandgap， making it promising for photovoltaic applications. The study has highlighted the effect of selenization conditions on the characteristics of the CZTSSe absorber layer and has provided valuable information for developing CZTSSe thin film solar cells.

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Enhancing the performance of the absorber of Cu2ZnSn（S， Se）4 photovoltaic materials by doping Cd2+

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Optoelectronics Letters 2025年

作者： YANG Shuqi XUE Yuming dai Hongli WANG Luoxin ZHANG Haiwei BAI Xin Institute of New Energy Intelligence Equipment， School of Integrated Circuit Science and Engineering， Tianjin University of Technology

Cationic doping is considered to be an effective way to improve the efficiency of Cu2ZnSn（S，Se）4（CZTSSe） photovoltaic materials. To improve the quality of the absorption layer of the crystal film， CZTSSe film was doped with some Cd to change the ratio of Cd and Zn in the precursor solution. XRD， Raman， SEM， UV-Vis spectroscopy， and other results showed that Cd successfully replaced Zn in the crystal lattice during post-selenization. The formation of harmful Zn-related defects was reduced， the grain size and crystallinity of the films were significantly increased， and the photoelectric properties of the films such as crystal quality and structural morphology were improved. As the Cd/（Cd+Zn） ratio increased from 0 to 0.35， the band gap of CZCTSSe decreased to 1.02eV. When Cd/（Cd+Zn）=0.25， the crystallinity and grain size reached the best value， and the film surface was smooth and dense， which inhibited the formation of the second phase on the surface of *** theoretical basis and experimental results showed that proper Cd doping can promote the growth of grain， so that compact CZCTSSe films with larger grain sizes and fewer holes could be prepared.

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Influence of band gap and different defects on the performance of Cu（In， Ga）Se2 solar cells

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Optoelectronics Letters 2025年

作者： LU Yahan XUE Yuming dai Hongli WANG Luoxin LI Weiwei JI Licui Institute of New Energy Intelligence Equipment， School of Integrated Circuit Science and Engineering， Tianjin University of Technology

The SCAPS-1D simulator， a one-dimensional solar cell capacitance simulator is utilized for simulating CIGS solar cells. It has been observed that the performance of solar cells can be enhanced by uniformly adjusting the band gap value of the CIGS absorption layer. Upon doing so， the solar cell's conversion efficiency reaches 22.13% when the band gap of the CIGS absorption layer is 1.3eV. Subsequently， the influence of defect type and density on photoelectric properties is analyzed by using the improved absorption band gap. The findings indicate that to heighten the photovoltaic efficiency， it is imperative to minimize the defect concentration in the absorption layer， as high-density defects significantly impact the efficiency， and can even render the conversion efficiency to zero. This study underscores the pivotal influence of band gap adjustments and defect charge types on the photoelectric properties of thin film solar cells.

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