检索结果-南通市图书馆

Impacts of canopy structure on the sub-canopy solar radiation under a deciduous forest based on fisheye photographs

寒旱区科学:英文版 2023年第3期15卷 150-160页

作者： yanlin zhang XiaoLin Feng XiaoLi Chang LiMin Tie School of Earth Sciences and Spatial Information Engineering Hunan University of Science and TechnologyXiangtanHunan 411201China

Forest canopy in a deciduous forest has significant sheltering effects on the sub-canopy solar radiation,significantly influencing the energy balance of snow and permafrost beneath the forest and their spatial *** study employs a digital camera mounted with a fisheye lens to acquire photographs at various times in a growth cycle of the forest canopy at three selected sites in a deciduous forest near the Greater Khingan Mountains Forest Ecological Station,Northeast *** vegetation types and conditions at the selected sites include P1 in ***,P2 in Carex ***,and P3 in Betula *** necessary image processing,these photographs were used to identify the canopy structure and its impacts on the sub-canopy solar *** show that fisheye photographs can successfully capture the forest canopy structure and are useful in estimating the sub-canopy solar *** order of sheltering effects from the largest to the smallest on sub-canopy solar radiation at three selected sites is P3,P1,and P2,highly depending on the canopy *** sub-canopy solar radiation was calculated using fisheye photographs and an algorithm validated by in-situ observed solar radiation beneath the canopy at P1 and *** results are reasonable,although the accuracy seems compromised due to the mismatch of conditions for calculation and *** also show that the mean annual solar radiation above the canopy was about 148.3 W/m2 in 2018,and the mean annual solar radiation values beneath the canopy were about 90.0,123.8,and 61.0 W/m2 at P1,P2,and P3,with only 60%,84%,and 42%of the total solar radiation penetrating through the canopy,*** in winter,when the trees are leafless,the canopy sheltering effects cannot be ignored in dense *** the limitations,fisheye photographs and related algorithms are useful in investigating the forest canopy structure and its impacts on sub-canopy s

关键词： Solar radiation Forest structure Fisheye photograph Sub-canopy Deciduous forest

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

河南鹤壁地幔捕掳体内磷灰石的发现及地幔交代作用

引用

河南理工大学学报（自然科学版） 2024年第1期43卷 61-67页

作者：秦战营姜江任栩颖齐永安张艳林侯广顺河南省有色金属矿产探测工程技术研究中心河南郑州450016 河南理工大学资源环境学院河南焦作454000 成都理工大学沉积地质研究院四川成都610059

目的地幔交代作用是岩石圈演化的重要方式之一。显性交代作用以出现交代成因的地幔矿物为特征,可为地幔交代作用提供直接证据,磷灰石是地幔中交代成因的典型矿物。中生代以来,太行山构造带东侧的华北板块岩石圈明显减薄,而西侧仍保留较... 详细信息

目的地幔交代作用是岩石圈演化的重要方式之一。显性交代作用以出现交代成因的地幔矿物为特征,可为地幔交代作用提供直接证据,磷灰石是地幔中交代成因的典型矿物。中生代以来,太行山构造带东侧的华北板块岩石圈明显减薄,而西侧仍保留较厚的岩石圈,太行山构造带是华北克拉通东部被破坏区与西部稳定区的过渡带。因此,太行山构造带的地幔包体对研究华北克拉通破坏具有重要意义。鹤壁地区位于太行山构造带上,发育有金伯利岩等深源岩浆岩。方法本文以金伯利岩携带的地幔包体为研究对象,探讨鹤壁地区岩石圈地幔的性质。通过人工重砂的方法,从地幔包体中分选出数粒磷灰石和一粒被辉石包裹的磷灰石。结果体视显微镜下,磷灰石无色,透明,具玻璃光泽,呈短柱状;扫描电镜能谱分析表明,被包裹的矿物主要由Ca,P,O,F元素组成,寄主矿物主要由Si,Fe,Mg,Al,O元素组成;电子探针结果表明,磷灰石中w(CaO)为53.525%~56.514%,w(P_(2)O_(5))为37.372%~40.851%;实验岩石学研究认为,顽火辉石+方解石→橄榄石+透辉石+CO_(2),磷灰石等作为副矿物产出。因此,辉石包裹磷灰石的矿物组合属于地幔交代成因,指示了显性交代作用。结论磷灰石这种显性地幔交代成因矿物的发现,为华北克拉通岩石圈地幔经历显性交代作用提供了直接证据。

关键词：河南鹤壁华北克拉通破坏地幔捕掳体地幔交代作用磷灰石

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

国际工程中重型罐基承载力确定及地基沉降特性分析

引用

工程勘察 2024年第5期52卷 1-6,26页

作者：吕连勋马明哲张少磊朱繁张衍林青岛中油岩土工程有限公司山东青岛266071 中国石油工程建设有限公司华东环境岩土工程分公司山东青岛266071 北京盈建科软件股份有限公司北京100010

浅基础承载力及地基沉降评估是工程勘察设计的基本问题,从事国际岩土工程有关的建设项目,应充分了解国际主要浅基础评估方法、计算公式及设计流程。以伊拉克鲁迈拉油田重型储罐工程为案例背景,进行了系统完整的浅基础案例分析,分别基于... 详细信息

浅基础承载力及地基沉降评估是工程勘察设计的基本问题,从事国际岩土工程有关的建设项目,应充分了解国际主要浅基础评估方法、计算公式及设计流程。以伊拉克鲁迈拉油田重型储罐工程为案例背景,进行了系统完整的浅基础案例分析,分别基于抗剪强度准则与沉降控制准则确定了重型罐基的地基承载力,并结合数值分析技术分析了储罐基础的沉降变形性状。结果表明:浅基础承载力的确定应兼顾地基强度与变形要求,沉降是储罐基础承载力的主要限制因素;结构荷载对储罐基础中心点的沉降影响最为显著,地基沉降随着深度以及与储罐中心距离的增加而逐渐减小,基底沉降性状总体呈“碗状”形态;相邻罐体的荷载会对基础变形产生一定的叠加影响,两罐相向部位的沉降较相离方向略大。研究可为从事类似国际岩土工程项目时确定地基承载力及地基变形提供参考。

关键词：国际工程浅基础重型罐基地基承载力地基沉降

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Development and test of hydraulic driven remote transporter

引用

International Journal of Agricultural and Biological Engineering 2021年第2期14卷 72-80页

作者： Jiaxue Li Shanjun Li yanlin zhang Mingdi Liu Zhiyuan Gao College of Engineering Huazhong Agricultural UniversityWuhan 430070China Guangdong Polytechnic college Zhaoqing 526000GuangdongChina China Agriculture(Citrus)Research System Wuhan 430070China Key Laboratory of Agricultural Equipment in Mid-lower Yangtze River Ministry of Agriculture and Rural AffairsWuhan 430070China Citrus Mechanization Research Base Ministry of Agriculture and Rural AffairsWuhan 430070China National R&D Center for Citrus Preservation Wuhan 430070China

To solve the problems of the traditional orchard conveyor,such as inflexible steering,a complex structure,poor stability and no power grid coverage,a remote-controlled rail conveyor powered by hydraulic pressure for mountainous orchards was designed and *** stress analysis was carried out on a full-load trailer to obtain the maximum traction force,which met the requirement of the climbing slope of the transport *** key components of the conveyor were developed,such as the hydraulic transmission,the control system,safety protection devices,limiting devices,the throttle and decompression actuator,the counterweight tension and the *** the theoretical calculations of key components,an orchard conveyor powered by diesel and hydraulic pressure was ***,the working performance of the transporter was tested through functionality,driving speed,system pressure and remote-controlled *** test results showed that the climbing angle of the transporter can reach 50°,the uphill load can reach 840 kg,the downhill load can reach 1100 kg,and the average running speed is 0.77 m/s;the driving speed ranges from 0.29 m/s to 1.08 m/s,and the system pressure ranges from 3.2 MPa to 10 *** driving speed and system pressure are significantly affected by the load,and the remote control distance can reach 455 *** technical specifications of the transporter meet all the design requirements,and the problem of stable operation of the transporter without power grid coverage has been *** research results can well meet the practical application requirements of mountain orchard transportation without power grid coverage and provide theoretical reference for the design of key components of mountain orchard transportation machinery.

关键词： mountain orchard conveyor hydraulic drive remote control

来源：

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

Mechanical behavior and damage constitutive model of sandstone under hydro-mechanical (H-M) coupling

引用

International Journal of Mining Science and Technology 2024年第6期34卷 837-853页

作者： Tao Tan Chunyang zhang yanlin Zhao Xiaoshuang Li School of Resources and Environmental Engineering Wuhan University of TechnologyWuhan 430070China State Key Laboratory of Safety and Health in Metal Mines Maanshan 243000China Sinosteel Maanshan General Institute of Mining Research Co. Ltd.Maanshan 243000China School of Resource&Environment and Safety Engineering Hunan University of Science and TechnologyXiangtan 411201China School of Urban Construction Changzhou UniversityChangzhouJiangsu 213164China

Underground engineering often passes through water-rich fractured rock masses, which are prone to fracture and instability under the long-term coupling of in-situ stress field and pore water(P-W) pressure, ultimately threatening the stability of underground structures. In order to explore the mechanical properties of rocks under H-M coupling, the corresponding damage constitutive(D-C) model has become the focus of attention. Considering the inadequacy of the current research on rock strength parameters,energy evolution characteristics and D-C model under H-M coupling, the mechanical properties of typical sandstone samples are discussed based on laboratory tests. The results show that the variation of characteristic stresses of sandstone under H-M coupling conforms to the normalized attenuation equation and Mohr-Coulomb(M-C) criterion. The P-W pressure mechanism of sandstone exhibits a dynamic change from softening effect to H-M fracturing effect. The closure stress is mainly provided by cohesive strength, while the initiation stress, damage stress, and peak stress are jointly dominated by cohesive strength and friction strength. In addition, residual stress is attributed to the friction strength formed by the bite of the fracture surface. Subsequently, the energy evolution characteristics of sandstone under H-M coupling were studied, and it was found that P-W pressure weakened the energy storage capacity and energy dissipation capacity of sandstone, and H-M fracturing was an important factor in reducing its energy storage efficiency. Finally, combined with energy dissipation theory and statistical damage theory, two types of D-C models considering P-W pressure are proposed accordingly, and the model parameters can be determined by four methods. The application results indicate that the proposed and modified D-C models have high reliability, and can characterize the mechanical behavior of sandstone under H-M coupling, overcome the inconvenience of existing D-C models

关键词： H-M coupling Water-saturated sandstone Mechanical mechanism Energy evolution D-C model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A coupled catalyst composed of CoFe_(2)O_(4) magnetic nanoparticle and[HMIM]Br-FeCl_(3) to intensify the oxidative desulfurization of FCC diesel

引用

Green Chemical Engineering 2021年第4期2卷 441-449页

作者： yanlin zhang Xinyu zhang Guangren Yu Xiaochun Chen Ahmed A.Abdeltawab Hany El-Hamshary Beijing Key Laboratory of Membrane Science and Technology&College of Chemical Engineering Beijing University of Chemical TechnologyBeijing100029China Department of Chemistry College of ScienceKing Saud UniversityRiyadh11451Saudi Arabia

Ionic liquids have been extensively studied as solvents or catalysts for oxidative desulfurization(ODS)of diesel fuel,but it is still a challenge to reduce the desulfurization time and *** this work,a new highly efficient desulfurization system composed of CoFe_(2)O_(4) magnetic nanoparticle,[HMIM]Br-FeCl_(3) and H_(2)O_(2) was developed for the ODS of FCC diesel *** desulfurization performances were investigated including desulfurization time,temperature,volume ratio of IL/oil,O/S molar ratio,dosage of CoFe_(2)O_(4),FeCl_(3) content in ILs,regeneration,and reuse of catalyst and *** to the coupled catalytic roles of CoFe_(2)O_(4) magnetic nanoparticle and[HMIM]Br-FeCl_(3),where Co2t and Fe3t interact with H_(2)O_(2) to produce ·OH radical that converts S-compounds into sulfone and sulfoxide compounds,such a desulfurization system is highly effective in removing S-compound in diesel *** S-content in FCC diesel fuel was reduced from the original 272.8 ppm to 0.5 ppm with 99.82%S-removal efficiency after one step within 8 minunder the optimal conditions of 25℃,8 min,V(IL/oil)=1:10,O/S=20,5 wt%CoFe_(2)O_(4) dosage and n([HMIM]Br)/n(FeCl_(3))=1:1;the desulfurization performance is much better in desulfurization time and steps than other desulfurization systems reported *** desulfurization system can be regenerated and reused without remarkable loss of desulfurization activity.A desulfurization mechanism was proposed.

关键词： CoFe_(2)O_(4)magnetic nanoparticle Ferric chloride ionic liquids Oxidative desulfurization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Initial residual stress experiment and simulation of thin-walled parts for layer removal method

引用

High Technology Letters 2018年第1期24卷 75-81页

作者：刘宇男 Wang Min Zan Tao Gao Xiangsheng zhang yanlin Beijing Key Laboratory of Advanced Manufacturing Technology College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology Beijing 100124 P. R. China Beijing Key Laboratory of Electrical Discharge Machining Technology Beiiing 100191 P. R. China Beijing Xinli Machinery Co. Ltd. Beijing 100039 P. R. China

Thin-walled parts have low stiffness characteristic. Initial residual stress of thin-walled blanks is an important influence factor on machining stability. The present work is to verify the feasibility of an initial residual stress measurement of layer removal method. According to initial residual stress experiment for casting ZL205 A aluminum alloy tapered thin-walled blank by a common method,namely hole-drilling method,three finite element models with initial residual stress are established to simulate the layer removal method in ABAQUS and ANSYS software. By analyzing the results of simulation and experiments,the cutting residual stress inlayer removal process has a significant effect on measurement results. Reducing cutting residual stress is helpful to improve accuracy of layer removal method.

关键词： initial residual stress thin-walled parts layer.removal method finite element

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

干湿循环作用下泥质红砂岩软化及崩解特性试验研究

引用

工程勘察 2024年第1期52卷 14-19页

作者：张艳林王聪汤禧龙吴远达中国水利水电第七工程局有限公司成都610081 武汉大学土木建筑工程学院武汉430072

在我国华南地区广泛分布的新近系地层中,岩体的工程性质较差,季节性降雨后易出现大变形破坏。为揭示该地层岩石特殊的水理特性,以典型的宿迁组红砂岩为研究对象,首先对其耐久性和软化性进行测定,然后开展了干湿循环试验和循环后试样的... 详细信息

在我国华南地区广泛分布的新近系地层中,岩体的工程性质较差,季节性降雨后易出现大变形破坏。为揭示该地层岩石特殊的水理特性,以典型的宿迁组红砂岩为研究对象,首先对其耐久性和软化性进行测定,然后开展了干湿循环试验和循环后试样的力学特性试验,最后通过核磁共振技术对干湿循环过程中试样的孔隙特征进行检测,分析其力学性能的劣化机理。试验结果表明:红砂岩吸水软化特征明显,但耐久性好,软化系数ω=0.75,二次崩解指数I_(d2)=0.96;干湿循环过程中试样的强度不断降低,干湿循环10次后的单轴抗压强度为饱和状态下的52.3%;干湿循环过程中红砂岩内部产生了大量的微裂隙,孔隙率增加也较为明显,胶结结构的破坏是导致干湿循环过程中红砂岩强度不断降低的主要原因。

关键词：干湿循环软化性耐崩解性 T_(2)谱

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

β-石竹烯抑制LPS刺激巨噬细胞炎症的研究

引用

生物资源 2024年第4期46卷 390-396页

作者：杨丙晔张燕琳许依红戴苑花厦门医学院药学系福建厦门361023 厦门市海洋药用天然产物资源重点实验室福建厦门361023

β-石竹烯是一种双环倍半萜类化合物。为研究β-石竹烯在体外对脂多糖诱导炎症的作用效果及作用机制,利用β-石竹烯处理被脂多糖诱导的RAW264.7细胞炎症模型,用MTT法检测β-石竹烯对细胞活力的影响,用ELISA试剂盒检测IL-6、TNF-α炎症... 详细信息

β-石竹烯是一种双环倍半萜类化合物。为研究β-石竹烯在体外对脂多糖诱导炎症的作用效果及作用机制,利用β-石竹烯处理被脂多糖诱导的RAW264.7细胞炎症模型,用MTT法检测β-石竹烯对细胞活力的影响,用ELISA试剂盒检测IL-6、TNF-α炎症因子的含量变化,用q RT-PCR技术检测IL-6、TNF-α、IL-1β、MCP-1因子的m RNA含量变化,用Western blot检测NF-κB信号通路和JNK信号通路关键蛋白表达变化。结果显示,β-石竹烯能够降低细胞中IL-6因子的含量和IL-6、TNF-α、IL-1β、MCP-1因子的表达,抑制炎症信号通路NF-κB和JNK。因此,β-石竹烯可以通过抑制NF-κB和JNK信号通路,降低炎症因子的释放起到抗炎的效果。该研究为β-石竹烯活性的开发提供数据支持,并进一步为β-石竹烯应用于抗炎治疗方面提供了理论依据。

关键词： β-石竹烯炎症小鼠腹腔巨噬细胞(RAW264.7) 炎症因子信号通路

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A distributed scheme developed for eco-hydrological modeling in the upper Heihe River

引用

Science China Earth Sciences 2015年第1期58卷 36-45页

作者： YANG DaWen GAO Bing JIAO Yang LEI Hui Min zhang yanlin YANG HanBo CONG ZhenTao State Key Laboratory of Hydro-science and Engineering Department of Hydraulic EngineeringTsinghua University School of Water Resources and Environment China University of Geosciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Modeling the hydrological processes at catchment scale requires a flexible distributed scheme to represent the catchment to- pography, river network and vegetation pattern. This study has developed a distributed scheme for eco-hydrological simulation in the upper Heihe River. Based on a 1 km x 1 km grid system, the study catchment is divided into 461 sub-catchments, whose main streams form the streamflow pathway. Furthermore, a 1 km grid is represented by a number of topographically similar ＂hillslope-valley＂ systems, and the hillslope is the basic unit of the eco-hydrological simulation. This model is tested with a simplified hydrological simulation focusing on soil-water dynamics and streamflow routing. Based on a 12-year simulation from 2001 to 2012, it is found that variability in hydrological behavior is closely associated with climatic and landscape condi- tions especially vegetation types. The subsurface and groundwater flows dominate the total river runoff. This implies that the soil freezing and thawing process would significantly influence the runoff generation in the upper Heihe basin. Furthermore, the runoff components and water balance characteristics vary among different vegetation types, showing the importance of coupling the vegetation pattern into catchment hydrological simulation. This paper also discusses the model improvement to be done in future study.

关键词： distributed scheme catchment discretization streamflow pathway hillslope parameterization the upper Heihe River

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：