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Gravel excavation and geomorphic evolution of the mining affected river in the upstream reach of the yangtze River,China

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International Journal of Sediment Research 2022年第2期37卷 272-286页

作者： Yi Xiao Wenjie Li shengfa yang National Inland Waterway Regulation Engineering Research Center Chongqing Jiaotong University

As economic development upstream in the yangtze River basin has progressed in recent decades,the demand for sediment has rapidly increased and contributed to an expansion in sediment excavation that may affect the river's stability and navigation safety.In the current study,the distribution of gravel mining in the upstream reach of the yangtze River was investigated using field measurements obtained from2008 to 2017.An experimental investigation was then done to analyze the bed load behavior in a typical mined channel using a physical river model.Finally,a two-dimensional hydrodynamic-sediment transport numerical model was developed to predict the evolution of the mined channel.The results indicate that gravel mining was mainly distributed among the following nine river sections:Tongluoxia-Yibin,Erlong-Xianglutan,Naxi-Jinkou,Binpangqi-Hongyanqi,Chayuqi-Shenbeizui,yangshipan-Shangbaisha,Dongxikou,Baisha-Wenzhongba,and Jiangjin-Shenzhongba.The gravel shoals near the riverbank have been destroyed,and the bed topography has been altered by up to 1.65 × 10～9 m3over the past 10 years.A bed load velocity formula was proposed to describe bed load transport in the mined channel based on dimensional analysis.The recovery process of the excavation pits was slow in both the experiments and simulations,with only 0.12% and 1.39%,respectively,of the mined amounts of gravel being restored.Finally,the recovery rate of the mining pits gradually slowed as the sediment supply from upstream decreased,suggesting that the destroyed gravel shoals rarely returned to their original forms due to the combined operation of hydro-projects in upstream areas and limited sediment storage in the channel.

关键词： Gravel mining Bed load transport Channel evolution yangtze River upstream 2D numerical model

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Theoretical & Applied Mechanics Letters 2022年第3期12卷 213-219页

作者： Peng Zhang Yanchong Duan Qiang Zhong Danxun Li shengfa yang Jiang Hu Wenjie Li National Engineering Research Center for Inland Waterway Regulation Chongqing Jiaotong UniversityChongqing 400074China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China College of Water Resources&Civil Engineering China Agricultural UniversityBeijing 100083China Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System in China Agricultural University Beijing 100083China Key Laboratory of Ministry of Education for Hydraulic and Water Transport Engineering Chongqing Jiaotong UniversityChongqing 400074China

Decelerating open-channel flow is a type of flow that gradually moves forward with decreasing velocity and increasing water depth.Although all flow parameters change along the streamwise direction,previous studies have revealed that these parameters’vertical distributions at different sections can be universally described with a single profile when being nondimensionalised by appropriate scales.This study focuses on the population trends of spanwise rotational motions at various sections along the main flow direction by particle imaging velocimetry(PIV)measurement.The wall-normal population distributions of density,radius,swirling strength,and convection velocity of the prograde and retrograde motions show similar trends in uniform open-channel flows.The dimensionless representation is invariant along the main flow direction.This study’s results indicate the self-similar characteristic of population trends of spanwise rotational motions prevails in decelerating open-channel flow.

关键词： Self-similarity Population trends Spanwise rotational motions Decelerating open-channel flow Equilibrium flow

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Ti_(3)C_(2)T_(x) MXene in-situ transformed Li_(2)TiO_(3) interface layer enabling 4.5 V-LiCoO_(2)/sulfide all-solid-state lithium batteries with superior rate capability and cyclability

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Chinese Chemical Letters 2024年第6期35卷 195-200页

作者： Yaping Wang Pengcheng Yuan Zeyuan Xu Xiong-Xiong Liu shengfa Feng Mufan Cao Chen Cao Xiaoqiang Wang Long Pan Zheng-Ming Sun Key Laboratory of Advanced Metallic Materials of Jiangsu Province School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China CALB Technology Co. Ltd.Changzhou 213200China

All-solid-state lithium batteries(ASSLBs)based on sulfide electrolytes promise next-generation energy storage with high energy density and safety.However,the sulfide electrolytes suffer from phase instability and sluggish interfacial charge transport when pairing with layered oxide cathodes at high voltages.Herein,a simple and efficient strategy is proposed using two-dimensional Ti_(3)C_(2)T_(x)MXene as starting material to in-situ construct a 15 nm Li_(2)TiO_(3) layer on a typical oxide cathode,LiCoO_(2).The in-situ transformation of Ti_(3)C_(2)T_(x)into Li_(2)TiO_(3) layer occurs at a low temperature of 500℃,avoiding the phase deterioration of LiCoO_(2).The thin Li_(2)TiO_(3) layer is Li^(+)conducting and electrochemically stable,thereby preventing the interfacial decomposition of sulfide electrolytes induced by LiCoO_(2) at high voltages and facilitating Li+transport at the interface.Moreover,Li_(2)TiO_(3) can stabilize the layer structure of LiCoO_(2) at high voltages.Consequently,the sulfide-based ASSLB using LiCoO_(2)@Li_(2)TiO_(3) cathode can operate stably at a high voltage of up to 4.5 V(vs.Li+/Li),delivering an outstanding initial specific discharge capacity of 138.8 m Ah/g with a high capacity retention of 86.2% after 100 cycles at 0.2 C.The in-situ transformation strategy may also apply to other MXenes,offering a general approach for constructing other advanced lithiated coatings for oxide cathodes.

关键词： Solid sulfide electrolyte Oxide cathode MXene In-situ transformation Li_(2)TiO_(3)interfacial layer

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Estimating instantaneous concentration of suspended sediment using acoustic backscatter from an ADV

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International Journal of Sediment Research 2019年第5期34卷 422-431页

作者： Wenjie Li shengfa yang Wei yang Yi Xiao Xuhui Fu Shuaishuai Zhang National Inland Waterway Regulation Engineering Research Center Chongqing Jiaotong University Changjiang Chongqing Harbour and Waterway Engineering Investigation and Design Institute

The measurement of instantaneous sediment concentration remains a challenging task. In this study, a three-step procedure is proposed to estimate instantaneous sediment concentration using acoustic backscatter from Acoustic Doppler Velocimeter(ADV). The influences of acoustic noise and particle diameter on an ADV’s performance was first tested in the laboratory, then the three-step procedure was verified based on field measurements in the Zhongxian and Fengjie reaches in the Three Gorges Reservoir. The first step involves reconstructing the backscatter signal time series. Due to contamination from both the noise floor and spurious spikes, the denoising-despiking method was applied instead of the traditional velocity-despiking methods, and this approach performed well based on spectrum analysis. The second step involves calibrating the sediment concentration against the backscatter signal.A linear relation, whose slope and intercept were calibrated to be dependent on particle diameter, is proposed in double logarithmic coordinates. The third step involves calculating the instantaneous sediment concentration using reconstructed instantaneous backscatter based on the proposed relation.The accuracy of the proposed method was evaluated through consideration of the concentration spectrum and sediment flux, indicating that the proposed three-step procedure is effective for the measurement of instantaneous sediment concentration.

关键词： Instantaneous sediment concentration Acoustic backscatter intensity Denoising-despiking Particle diameter Acoustic Doppler Velocimeter

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明渠湍流结构对粒子运动跟随性影响综述

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人民长江 2024年第2期55卷 179-186页

作者：张先炳丁小峰杨威杨胜发重庆交通大学国家内河航道整治工程技术研究中心重庆400074

近年来大量学者通过室内试验、现场观测以及数值模拟等方法对明渠湍流中粒子的运动规律进行了深入细致的研究,逐步揭示了明渠湍流中粒子运动复杂性的本质和规律,并将成果应用于河流泥沙输移、河流地貌演变以及生态环境保护等多个领域。... 详细信息

近年来大量学者通过室内试验、现场观测以及数值模拟等方法对明渠湍流中粒子的运动规律进行了深入细致的研究,逐步揭示了明渠湍流中粒子运动复杂性的本质和规律,并将成果应用于河流泥沙输移、河流地貌演变以及生态环境保护等多个领域。鉴于明渠湍流具有明显的分区效应,其湍流流速分布、分区结构组成以及相干结构分布特性等对水中粒子的运动过程均会产生显著影响,对水中粒子在明渠湍流结构中的整体运动规律、湍流结构内区以及外区的运动过程进行了总结;重点阐述了近壁区粒子运动规律的反常现象和原因,以及湍流结构中粒径、密度和Stokes数这3个影响粒子运动过程的主要因素。研究成果可为泥沙运动以及生态保护等研究及应用提供参考。

关键词：明渠湍流固液两相流粒子跟随性湍流分区结构

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Field measurements of settling velocities of fine sediments in Three Gorges Reservoir using ADV

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International Journal of Sediment Research 2016年第3期31卷 237-243页

作者： Wenjie Li shengfa yang Jiang Hu Xuhui Fu Peng Zhang National Inland Waterway Regulation Engineering Research Center.Chongqing Jiaotong University Key Laboratory of Ministry of Education for Hydraulic and Water Transport Engineering Chongqing Jiaotong University

The Three Gorges Reservoir(TGR) is suffering from unexpected fine sediment deposition,to better understand the fine sediment transport processes,field measurements were conducted at the Zhongxian and Fengjie reaches.A method based on the sediment diffusion equation was proposed to measure the settling velocities using the Acoustic Doppler Velocimeter(ADV).The backscatter acoustic intensities(BSI) received from the ADV were calibrated against the sediment concentrations measured via water sampling,suggesting a linear relationship in double logarithmic coordinate system.The instantaneous sediment concentration was calculated using the derived relationship,and then the settling velocity was obtained through the proposed procedure.The settling velocities of the fine particles in the TGR were found to vary with the water depth.Most of the effective settling velocities were within the range of 0.1-10 mm/s,which were larger than those of the primary particles,indicating that the flocculation was likely to occur in the TGR.Additionally,it is suggested that the turbulent motion played an important role in the flocculation in the TGR.

关键词： Settling velocity Fine sediments Acoustic Doppler Velocimeter Field measurement Three Gorges Reservoir

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情理数学视域下的高阶思维培养教学探究

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教育学术月刊 2024年第3期 80-86页

作者：郑圣发陈登连福州市鼓楼区教师进修学校福建福州350003 厦门市尚文实验学校福建厦门361013

情理数学以情和理为线索,以情驭理、情理相融,指向学生高阶思维的培养。高阶思维相对于低阶思维而言,是一种高层次的思维,包含批判性思维、创新性思维等。创新是民族进步的灵魂,是国家繁荣富强的不竭动力。创新意识培养是现代数学教育... 详细信息

情理数学以情和理为线索,以情驭理、情理相融,指向学生高阶思维的培养。高阶思维相对于低阶思维而言,是一种高层次的思维,包含批判性思维、创新性思维等。创新是民族进步的灵魂,是国家繁荣富强的不竭动力。创新意识培养是现代数学教育的基本任务,应充分体现在数学教与学的过程中。然而受到种种因素影响,学生“会听课,无兴趣;会解题,无体验;会发言,无思想;会考试,无能力”现象严重存在。情理数学通过“四环教学”,实施“三备、四放、五重、六融化”策略,激发学生学习的兴趣,高阶思维能力的培养得以在课堂真正发生,是破解长期困扰教师“四无问题”的良方。

关键词：情理数学高阶思维四环教学

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基于秘密分享的无线传感器网络多维数据安全聚合方案

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传感技术学报 2024年第4期37卷 709-715页

作者：张勇张生发刘登志江苏海洋大学计算机工程学院江苏连云港222005

无线传感器网络中的安全数据聚合方案旨在保护数据隐私、降低系统能耗,从而延长网络的生命周期。针对目前多维无线传感器网络中数据传输安全性不高、数据传输中的能量消耗过大等问题,提出一种基于阈值可变秘密分享的多维数据聚合方案(TC... 详细信息

无线传感器网络中的安全数据聚合方案旨在保护数据隐私、降低系统能耗,从而延长网络的生命周期。针对目前多维无线传感器网络中数据传输安全性不高、数据传输中的能量消耗过大等问题,提出一种基于阈值可变秘密分享的多维数据聚合方案(TCSSMDA)。首先,在本方案中,网络簇头的选择主要是依据网络节点的剩余能量以及其与基站的距离。同时,为了降低多维数据传输的能量消耗,使用预设值对多维传感器发送数据机制进行优化。最后,为了保证传感器的数据安全,使用设计了一种轻量级、高效通信的信息加密方式。安全性分析与模拟结果表明,所提出的方案在降低数据包大小、节点通信成本以及提升网络数据安全性和生存时间方面都表现出了较好的性能。

关键词：无线传感器网络数据聚合簇头选择秘密分享数据安全

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台风干扰海岸林受损及灾后恢复的影响因素研究进展

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生态学报 2024年第1期44卷 1-17页

作者：杜建会陈嘉健李升发中山大学地理科学与规划学院广州510275 广东省科学院广州地理研究所广东省地理空间信息技术与应用公共实验室广州510070 广东省遥感与地理信息系统重点实验室广州510070

随着气候变暖,台风登陆的强度及频率均呈增加趋势,其对海岸森林的影响也日益严重,从而危及沿海生态安全。但因台风登陆的不确定性、海岸森林恢复的滞后性和数据源受限等影响,当前对台风后海岸森林受损及灾后恢复的影响因素研究仍存在很... 详细信息

随着气候变暖,台风登陆的强度及频率均呈增加趋势,其对海岸森林的影响也日益严重,从而危及沿海生态安全。但因台风登陆的不确定性、海岸森林恢复的滞后性和数据源受限等影响,当前对台风后海岸森林受损及灾后恢复的影响因素研究仍存在很大的不确定性。台风登陆导致海岸森林枝叶脱落、树干折断和根系裸露等,受树种特征(冠层、树干和根系),林分结构(密度、组成),立地条件(地形、土壤)和台风特征(强度、频率)等影响,海岸森林在不同研究尺度的受损存在明显的空间异质性,单一因素难以完全解释台风后海岸森林的受损格局。台风后部分海岸森林因受损严重而死亡,其余仍以种子萌发、幼苗/幼树生长或萌生更新的方式持续恢复。海岸森林在灾后的恢复周期从几个月到几十年不等,其具体时长与树种更新策略(实生、萌生),森林类型(人工林、天然林),树木受损程度(轻度、重度)及区域水热条件(水分、热量)等有关。未来仍需借助多源遥感数据,并结合台风后的固定样方调查、野外采样和室内样品分析,对海岸森林的受损和恢复格局开展多时空尺度研究,阐明不同受损程度下树木的水分传输和光合产物分配过程及其差异,全面揭示台风干扰对海岸森林的影响机制。

关键词：海岸森林台风受损程度恢复周期影响因素

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Probing electronic structures of transition metal complexes using electron paramagnetic resonance spectroscopy

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Magnetic Resonance Letters 2023年第1期3卷 43-60,I0003页

作者： shengfa Ye State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116023China

Electron paramagnetic resonance(EPR)or electron spin resonance(ESR)has been widely employed to characterize transition metal complexes.However,because of the high degree of complexity of transition metal EPR spectra,how to extract the underlying electronicstructure information inevitably poses a major challenge to beginners,in particular for systems with S>1/2.In fact,the physical principles of transition metal EPR have long been well-established and since 1970s a series of dedicated voluminous monographs have been published already.Not surprisingly,they are not appropriate stating points for novices to grasp a panorama of the profound theory prior to scrutinizing in-depth references.The present review aims to fill this gap to provide a perspective of transition metal EPR and unveil some peculiar subtleties thereof on the basis of our recent work.

关键词： EPR Electronic structures Transition metal complexes Spin Hamiltonian

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