检索结果-南通市图书馆

中西太平洋金枪鱼延绳钓钓钩深度分布及其影响因素

在线全文

学校读者我要写书评

暂无评论

上海海洋大学学报 2024年第4期33卷 1020-1030页

作者：刘志强郭绍健王禹程周成吴峰万荣上海海洋大学海洋生物资源与管理学院上海201306 国家远洋渔业工程技术研究中心上海201306 大洋渔业资源可持续开发教育部重点实验室上海201306

为掌握中西太平洋金枪鱼延绳钓作业中钓钩深度分布及其影响因素,根据2021年8—10月随“淞航”号调查船在中西太平洋海域调查时采集的作业参数、钓钩深度和环境数据等信息,利用支持向量回归模型(Support vector machine,SVR)和广义加性模... 详细信息

为掌握中西太平洋金枪鱼延绳钓作业中钓钩深度分布及其影响因素,根据2021年8—10月随“淞航”号调查船在中西太平洋海域调查时采集的作业参数、钓钩深度和环境数据等信息,利用支持向量回归模型(Support vector machine,SVR)和广义加性模型(General additive model,GAM)分析不同作业参数和环境因素下钓钩深度的分布情况,探讨各因素对钓钩深度的影响。结果表明:(1)钓钩深度的计算值中1号钓钩深度最小,为(130.03±3.32) m;8号钓钩深度最大,为(363.25±36.52) m。实测值中1号钓钩深度最小,为(130.81±17.94) m;7号钓钩深度最大,为(329.91±54.37) m。(2)1号钓钩的SVR模型整体拟合度最小(R^(2)=0.38);6号钓钩的整体拟合度最大(R^(2)=0.77)。SVR模型训练值的均方差中6号钓钩最小,为0.138;8号钓钩最大,为0.309。测试值的均方差中4号钓钩最小,为0.086;5号钓钩最大,为0.282。(3)GAM分析显示0~64 m、128~192 m水层平均流速和投绳速度与各钓钩深度相关性最高,其次分别为64~128 m、192~256 m、256~320 m水层平均流速和船速。320~384 m水层平均流速和风速与各钓钩深度均无显著相关性。(4)SVR和GAM的钓钩深度预测值与实测值平均差异分别为1.75%和6.38%。SVR预测值与实测值随钓钩位置变化趋势一致,吻合性较好。研究结果有助于了解作业中金枪鱼延绳钓钓钩分布规律,进而为优化钓具性能提供基础参考依据。

关键词：中西太平洋金枪鱼延绳钓钓钩深度支持向量回归机模型广义加性模型

在线全文

学校读者我要写书评

暂无评论

森林粗木质残体分解研究进展

植物生态学报 2024年第5期48卷 541-560页

作者：常晨晖朱彪朱江玲吉成均杨万勤北京大学城市与环境学院生态研究中心地表过程分析与模拟教育部重点实验室北京100871 台州学院生命科学学院浙江台州318000

森林粗木质残体主要包括倒木、枯立木、大枯枝、树桩和粗根等,它们是绝大多数森林生态系统的结构性成分,在全球碳循环和生物多样性保育等方面发挥着不可替代的作用。特别是近些年,极端高温、干旱、热带气旋等极端气候事件正在加速树木死... 详细信息

森林粗木质残体主要包括倒木、枯立木、大枯枝、树桩和粗根等,它们是绝大多数森林生态系统的结构性成分,在全球碳循环和生物多样性保育等方面发挥着不可替代的作用。特别是近些年,极端高温、干旱、热带气旋等极端气候事件正在加速树木死亡,改变森林粗木质残体形成的方式和分解过程,森林生态系统功能和稳定性也会受到深刻影响,生态学家对此也越来越重视。如今,生态学家通过野外观测和控制实验,围绕粗木质残体的分解特征、调控机制和分解过程中粗木质残体上的生物多样性开展了大量研究,促进了粗木质残体生态学的快速发展。该文首先汇总了最常见的用于森林粗木质残体分解过程的研究方法,并且描述了各研究方法适用的情景。其次,从形态、物理和化学性状方面探讨了粗木质残体的分解特征。然后,围绕着影响森林粗木质残体分解的控制因素,系统梳理和总结了已取得的研究结果。具体来说,粗木质残体分解主要受到基质质量、分解者和环境条件的调控,其中基质质量和分解者在样点尺度上影响着分解过程,基质质量对分解者群落有自下而上的调控作用,环境条件在区域或更大研究尺度上发挥主导作用。粗木质残体在分解的同时孕育了数量巨大、种类丰富的生物,主要类群包括苔藓类附生植物、细菌、真菌和无脊椎动物。无脊椎动物对森林粗木质残体的利用方式最为复杂,可能将其作为栖息地、掩蔽所、繁殖地、取食场所。附生植物的演替过程与分解时间正相关,但与腐烂程度联系不紧密,其他生物类群的演替则更多地受到基质质量的影响。由于以往的综述鲜有涉及不同结构组分(树皮和木质部)分解的研究进展,该文补充和探讨了树皮和木质部的分解特征和潜在的相互作用过程。由于粗木质残体分解缓慢的特点和研究方法的限制,目前许多机理的相关研究仍不够深入,该文围绕粗木质残体分解机制和生物多样性保育功能探讨了未来需要重点关注的研究内容及可能的研究方法。

关键词：分解速率树皮木质部分解时期功能性状大小效应

基于复杂网络理论和电路模型的酒泉市生态网络优化

在线全文

学校读者我要写书评

暂无评论

应用生态学报 2024年第1期35卷 237-246页

作者：石晶石培基王梓洋万雅程番苑王丽蓉西北师范大学地理与环境科学学院兰州730070 西北师范大学甘肃省绿洲资源环境与可持续发展实验室兰州730070 甘肃省土地利用与综合整治工程研究中心兰州730070

构建科学合理的生态网络是优化国土空间开发保护格局的关键,对保障区域生态安全和促进生态系统良性循环具有重要意义。既有研究在生态网络“鲁棒性”评价中多采用节点攻击法(破坏生态源地),而现实中生态廊道相比源地更脆弱,节点攻击法... 详细信息

构建科学合理的生态网络是优化国土空间开发保护格局的关键,对保障区域生态安全和促进生态系统良性循环具有重要意义。既有研究在生态网络“鲁棒性”评价中多采用节点攻击法(破坏生态源地),而现实中生态廊道相比源地更脆弱,节点攻击法尚缺乏合理性。本研究以酒泉市为研究区,基于电路模型构建生态网络,采用复杂网络理论中的随机增边、节点度和节点介数低者优先增边3种策略对生态网络进行拓扑结构优化,并构建了边攻击策略对优化前后的生态网络“鲁棒性”进行对比,遴选最佳网络优化策略。结果表明:酒泉市共识别出生态源地65个,总面积20275.15 km^(2),草地占源地面积的89.5%。识别生态廊道179条,全长6387.16 km。识别生态障碍点共158个,总面积1385.5 km^(2),未利用地占障碍点总面积的92.2%。识别生态夹点63个,主要集中在源地边缘及廊道交汇处。其中,11处障碍点与夹点的空间分布位置较一致,是生态网络优化中需重点修复的区域。3种优化策略均显著提高了酒泉市生态网络的稳定性,按度增边优化策略的生态网络在随机攻击和蓄意攻击模式下最大连通子图相对大小和边连通率均最稳定,是酒泉市生态网络的最佳优化方案。

关键词：生态网络复杂网络理论优化策略鲁棒性酒泉市

Correlation analysis between underwater noise and Liutex for DTMB4119 propeller

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2022年第4期34卷 585-595页

作者： Lian-jie Yu Jian-wei Wu De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Wuhan Second Ship Design and Research Institute Wuhan 430205China

Propeller is an important equipment of ocean *** has characteristics of complex geometry and periodic vortex shed,which means high research *** paper takes DTMB419 propeller as the research object.A detailed study is conducted on the wake vortices in non-cavitation state and cavitation *** vortex identification methods are used to compare the vortices capture effects from downstream sections and three-dimensional *** results show that,the third-generation vortex identification technologyΩ_(R)shows obvious *** the same time,FW-H equation is used to predict propeller noise,and the relationship between nonlinear sound source distribution and vortices distribution is *** is found that the distribution of Lighthill tensor is consistent withΩ_(R),which proves the advantages and potential of third-generation vortex identification technology from acoustic perspective.

关键词： Third-generation vortex DTMB4119 propeller cavitation FW-H formulation

Numerical Simulations of Liquid-Solid Flows in A Vertical Pipe by MPS-DEM Coupling Method

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2022年第4期36卷 542-552页

作者： XIE Feng-ze MENG Qing-jie wan De-cheng Computational Marine Hydrodynamics Lab(CMHL) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Wuhan Second Ship Design and Research Institute Wuhan 430205China

In the process of deep-sea mining,the liquid-solid flows in the vertical transportation pipeline are very *** the present work,an in-house solver MPSDEM-SJTU based on the improved MPS and DEM is developed for the simulation of hydraulic ***,three examples including the multilayer cylinder collapse,the Poiseuille flow and two-phase dam-break are used to validate the precision of the DEM model,the pipe flow model and MPS-DEM coupling model,***,the hydraulic conveying with coarse particles in a vertical pipe is *** solid particle distribution is presented and investigated in ***,the coupling method is successfully applied for the simulation of the liquid-solid flows in a vertical pipe with rotating blades,which shows the stability of the solver under rotating boundary *** fully Lagrangian model is expected to be a new approach for analyzing hydraulic conveying.

关键词： liquid-solid flows MPS DEM vertical pipe rotating boundary conditions

MPS Method for Interaction Between Solitary Waves and Submerged Horizontal Plate

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2020年第3期34卷 314-327页

作者： XU Yan-zhang ZHAO Wei-wen wan De-cheng Computational Marine Hydrodynamics Lab(CMHL) State Key Laboratory of Ocean EngineeringSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The interaction between structure and wave is a typical phenomenon in naval architecture and ocean *** this paper,numerical simulation is carried out to study the interaction between a two-dimensional submerged,fixed,horizontal rigid plate and solitary wave with our in-house meshless particle CFD solver ***,the in-house CFD solver is verified by experimental results conducted at the State Key Laboratory of Coastal and Offshore Engineering,Dalian University of *** the verification,the plate is submerged under water and the solitary wave with a given amplitude is generated by a piston-type wave *** surface elevation of the wave and the pressure impacting on the plate is recorded and compared with experimental data *** predicted pressure and surface elevation agree well with the experimental *** in order to further investigate factors affecting wave-structure interaction,wave height,submerged depth and plate length are analyzed.

关键词： MPS method MLParticle-SJTU solver solitary waves submerged horizontal plate wave-plate interaction

Numerical techniques for coupling hydrodynamic problems in ship and ocean engineering

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2020年第2期32卷 212-233页

作者： Xiao-song Zhang Jian-hua wang De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) State Key Laboratory of Ocean EngineeringSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

Most hydrodynamic problems in ship and ocean engineering are complex and highly *** the trend of intelligent and digital design for ships and ocean engineering structures,comprehensive performance evaluation and optimization are of vital importance during *** this process,various coupling effects need to be accurately *** the significant progress of computational fluid dynamics(CFD),many advanced numerical models were proposed to simulate the complex coupling hydrodynamic problems in ship and ocean engineering *** this paper,five key coupling hydrodynamic problems are introduced,which are hull-propeller-rudder coupling,wave-floating structure coupling,aerodynamic-hydrodynamic coupling,fluid structure coupling and fluid-noise coupling,*** paper focuses on the numerical simulation techniques corresponding to each coupling problem,including the theories and the *** directions and conclusions are provided finally.

关键词： Coupling hydrodynamic problems numerical techniques ship and ocean engineering

Operational Reliability Modeling and Assessment of Battery Energy Storage Based on Lithium-ion Battery Lifetime Degradation

维普期刊数据库评论

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 Modern Power Systems and Clean Energy 2022年第6期10卷 1738-1749页

作者： Lin cheng Yuxiang wan Yanglin Zhou David Wenzhong Gao State Key Laboratory of Control and Simulation of Power System and Generation Equipment Department of Electrical EngineeringTsinghua UniversityBeijingChina Department of Electrical and Computer Engineering University of DenverDenverUSA IEEE

Battery energy storage(BES)systems can effectively meet the diversified needs of power system dispatching and assist in renewable energy *** reliability of energy storage is essential to ensure the operational safety of the power ***,BES systems are composed of battery *** suggests that BES performance depends not only on the configuration but also on the operating state over different lifetime *** lack of safety and reliability is the main bottleneck preventing widespread applications of BES ***,a reliability assessment algorithm and a weak-link analytical method for BES systems are proposed while considering battery lifetime ***,a novel lithium-ion battery model is proposed to identify the degradation rate of solid electrolyte interphase film formation and capacity *** impacts of different operating conditions are considered in stress factor ***,a reliability assessment algorithm for a BES system is introduced based on a universal generating *** innovative weak-link analytical method based on the reliability importance index is proposed that combines the evaluation results of state-oriented and state-change-oriented indexes through an entropy weight *** model,algorithm,indexes,and the usefulness are demonstrated in case studies based on aging test data and actual bus operating *** results demonstrate the effects of the battery status and working conditions on BES ***-link analysis is also used to assist BES systems in avoiding short-board batteries to achieve long lifetimes and efficient operation.

关键词： Battery energy storage lifetime degradation operational reliability capacity plummeting weak-link analysis

Numerical simulations of propeller cavitation flows based on OpenFOAM

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2020年第6期32卷 1071-1079页

作者： Min-sheng Zhao Wei-wen Zhao De-cheng wan Computational Marine Hydrodynamics Lab(CMHL) State Key Laboratory of Ocean EngineeringSchool of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China

In order to study the cavitation and hydrodynamic characteristics of propeller under uniform and non-uniform flows,numerical investigations are performed using interPhaseChangeDyMFoam in the open source computational fluid dynamics(CFD)software platform OpenFOAM with Schnerr-Sauer cavitation *** simulation results can be used as a reference to evaluate the working ability of a propeller in case of actual navigation.A new grid encryption method is adopted in the research to better capture the existence of vortex cavitation at the propeller *** method of function input is carried out in the study to simulate the condition of non-uniform flow and reduce the calculation *** unsteady dynamics are predicted by the Reynolds-averaged Navier-Stokes(RANS)method with a modified shear stress transport(SST)k−ωturbulence *** numerical results of the propeller such as cavitation shape and pressure distribution under uniform and non-uniform flow are analyzed and compared with each other.

关键词： OpenFOAM E779A propeller cavitation non uniform flow