检索结果-南通市图书馆

Rising utilization of stable isotopes in tree rings for climate change and forest ecology

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 Forestry Research 2024年第1期35卷 103-116页

作者： Ru Huang Chenxi Xu Jussi Grießinger Xiaoyu Feng Haifeng Zhu Achim bräuning National Institute of Natural Hazards Beijing 100085People’s Republic of China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029People’s Republic of China CAS Center for Excellence in Life and paleoenvironment Beijing 100044People’s Republic of China Institute of Geography Friedrich-Alexander-University of Erlangen-Nuremberg91058 ErlangenGermany State Key Laboratory of Tibetan plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101People’s Republic of China University of Chinese Academy of Sciences Beijing 100049People’s Republic of China

Analyses of stable isotopes(C,O,H)in tree rings are increasingly important cross-disciplinary *** rapid development in this field documented in an increasing number of publications requires a comprehensive *** study includes a bibliometric analysis-based review to better understand research trends in tree ring stable isotope ***,1475 publications were selected from the Web of Science Core Collection for *** findings are that:(1)numbers of annual publications and citations increased since *** 1974 to 1980,there were around two relevant publications per ***,from 2020 to 2022,this rose sharply to 109 publications per ***,average article citations were less than four per year before 1990,but were around four per article per year after 2000;(2)the major subjects using tree ring stable isotopes include forestry,geosciences,and environmental sciences,contributing to 42.5%of the total during 1974-2023;(3)the top three most productive institutions are the Chinese Academy of Sciences(423),the Swiss Federal Institute for Forest,Snow and Landscape Research(227),and the University of Arizona(204).These achievements result from strong collaborations;(4)review papers,for example,(Dawson et al.,Annu Rev Ecol Syst 33:507-559,2002)and(McCarroll and Loader,Quat Sci Rev 23:771-801,2004),are among the most cited,with more than 1000 citations;(5)tree ring stable isotope studies mainly focus on climatology and ecology,with atmospheric CO_(2) one of the most popular *** 2010,precipitation and drought have received increasing *** on this analysis,the research stages,key findings,debated issues,limitations and direc-tions for future research are *** study serves as an important attempt to understand the progress on the use of stable isotopes in tree rings,providing scientific guid-ance for young researchers in this field.

关键词： Tree rings Stable isotopes Web of Science Bibliometric

在线全文

学校读者我要写书评

暂无评论

长寿命UHpFRC组合钢桥面板研究综述

交通运输工程学报 2024年第1期24卷 68-84页

作者：段兰袁翊竑王春生 brÜHWILER Eugen 长安大学公路学院陕西西安710064 瑞士洛桑联邦理工学院结构维护与安全实验室沃州洛桑CH-1015

从三方面归纳与剖析了超高性能纤维增强水泥基(UHpFRC)复合材料组合钢桥面板的研究进展,包括强韧性组合层选材、界面传力机制与损伤累积机理、设计方法与工程应用;总结了纤维类型、纤维掺量对UHpFRC轴拉性能和抗弯性能的影响规律,确定... 详细信息

从三方面归纳与剖析了超高性能纤维增强水泥基(UHpFRC)复合材料组合钢桥面板的研究进展,包括强韧性组合层选材、界面传力机制与损伤累积机理、设计方法与工程应用;总结了纤维类型、纤维掺量对UHpFRC轴拉性能和抗弯性能的影响规律,确定了支撑组合钢桥面板结构分析的多种本构模型;对比分析了热连接、冷连接和混合连接组合界面设计方式的技术特点,归纳了胶粘界面、冷连接剪力键界面与混合连接界面的传力机理试验与理论研究成果;总结了基于冷连接设计理念的组合钢桥面板在合理构造、设计方法、规范规程与工程实践等方面的研究成果,并探讨了长寿命组合钢桥面板的创新与发展方向。研究结果表明:单一或混杂纤维的掺入综合提升了UHpFRC的应变强化能力、弯曲变形能力、抗断裂能力、裂缝宽度控制能力和抗疲劳性能,轴拉条件下UHpFRC三线型简化本构模型有力支撑了组合钢桥面板的设计计算,弹塑性损伤本构模型可描述不可逆疲劳损伤累积;验证了冷连接组合界面的增韧效果与可靠性,新型剪力键既可以提高组合效应,也能增韧UHpFRC层,混合连接界面具有降低界面局部应力集中、提高整体界面抗剪刚度、改善界面传力、提升施工效率等综合技术优势,内聚界面本构模型可实现冷连接界面损伤累积反演分析,界面损伤预测结果准确可靠;基于冷连接的UHpFRC组合钢桥面板可以有效提高钢桥面板的局部刚度,相关设计方法可支撑标准的编制与工程实践;应进一步提升UHpFRC的性价比和界面连接的高效性和可靠性,以支撑组合钢桥面板的长寿命、强韧性、轻量化、易维护、低能耗设计与建造。

关键词：桥梁工程长寿命 UHpFRC组合钢桥面板冷连接件组合界面设计准则免蒸养

Enhanced entropy generation and heat transfer characteristics of magnetic nano-encapsulated phase change materials in latent heat thermal energy storage systems

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1051-1070页

作者： p.S.REDDY p.SREEDEVI Department of Mathematics Rajeev Gandhi Memorial College of Engineering and TechnologyNandyal 518501India

The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEpCMs).The versatile finite element method(FEM)is implemented to numerically solve the governing *** effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the Rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEpCMs,ranging from 2%to 6%,the Stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity ***,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented *** results indicate that the time taken by the NEpCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf ***,the contours of the heat capacity ratio Cr decrease with the increase in the Stefan number Ste.

关键词： volume fraction of nano-encapsulated phase change material(NEpCM) radiation Stefan number heat capacity ratio entropy generation

A Hybrid Optimization Approach of Single point Incremental Sheet Forming of AISI 316L Stainless Steel Using Grey Relation Analysis Coupled with principal Component Analysiss

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 160-166页

作者： A Visagan p Ganesh Department of production Technology Madras Institute of TechnologyChennai-600044India

We investigated the parametric optimization on incremental sheet forming of stainless steel using Grey Relational Analysis(GRA) coupled with principal Component Analysis(pCA). AISI 316L stainless steel sheets were used to develop double wall angle pyramid with aid of tungsten carbide tool. GRA coupled with pCA was used to plan the experiment conditions. Control factors such as Tool Diameter(TD), Step Depth(SD), Bottom Wall Angle(BWA), Feed Rate(FR) and Spindle Speed(SS) on Top Wall Angle(TWA) and Top Wall Angle Surface Roughness(TWASR) have been studied. Wall angle increases with increasing tool diameter due to large contact area between tool and workpiece. As the step depth, feed rate and spindle speed increase,TWASR decreases with increasing tool diameter. As the step depth increasing, the hydrostatic stress is raised causing severe cracks in the deformed surface. Hence it was concluded that the proposed hybrid method was suitable for optimizing the factors and response.

关键词： single point incremental forming AISI 316L taguchi grey relation analysis principal component analysis surface roughness scanning electron microscopy

Cryogenic and conventional milling of AZ91 magnesium alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2024年第6期12卷 2503-2519页

作者： Vikas Marakini Srinivasa pai p Gururaj Bolar Bhaskara p Achar Department of Mechanical Engineering Nitte(Deemed to be University)NMAM Institute of Technology(NMAMIT)Nitte 574110India Department of Mechanical and Industrial Engineering Manipal Institute of TechnologyManipal Academy of Higher EducationManipal 576104India

Use of magnesium is the need of the hour due to its low density as well as its high strength-to-weight and stiffness-to-weight ratio *** study focuses on the effectiveness of liquid nitrogen(LN_(2))assisted cryogenic machining on the surface integrity(SI)characteristics of AZ91 magnesium *** milling using uncoated carbide inserts have been performed under liquid nitrogen(LN_(2))assisted cryogenic condition and compared with conventional(dry)*** are performed using machining parameters in terms of cutting speeds of 325,475,625 m/min,feed rates of 0.05,0.1,0.15 mm/teeth and depth of cuts of 0.5,1,1.5 mm *** significant surface integrity characteristics such as surface roughness,microhardness,microstructure,and residual stresses have been *** of SI characteristics with respect to milling parameters have been identified using statistical technique such as ANOVA and signal-to-noise(S/N)ratio ***,the multi criteria decision making(MCDM)techniques such as additive ratio assessment method(ARAS)and complex proportional assessment(COpRAS)have been utilized to identify the optimal conditions for milling AZ91 magnesium alloy under both dry and cryogenic *** of LN_(2)during machining,resulted in reduction in machining temperature by upto 29%with a temperature drop from 251.2℃under dry condition to 178.5℃in cryogenic *** showed the advantage of performing cryogenic milling in improving the surface integrity to a significant *** machining considerably minimized the roughness by upto 28%and maximised the microhardness by upto 23%,when compared to dry *** speed has caused significant impact on surface roughness(95.33%-dry,92.92%-cryogenic)and surface microhardness(80.33%-dry,82.15%-cryogenic).Due to the reduction in machining temperature,cryogenic condition resulted in compressive residual stresses(maximumσ║=-113 Mpa)on the alloy *** indicate no

关键词： Magnesium alloy Cryogenic machining Roughness Microhardness Microstructure Residual stress Multi criteria decision making

Stranched Internal Hernia Revealed by Occlusion of the Large Libra: A propos of a Case

在线全文

学校读者我要写书评

暂无评论

Case Reports in Clinical Medicine 2024年第1期13卷 37-42页

作者： Abdoulaye Kanté Mamady Almami Kéita Idrissa Tounkara Drissa Ouattara bréhima Bengaly Souleymane Sanogo bréhima Togola Drissa Traoré Nouhoum Ongoiba General Surgery Department of The Kati-Mali Reference Health Center Koulikoro Mali Service of Surgery “B” of The CHU Du point G Faculty of Medicine and Odontostomatology Bamako Mali

The left para-duodenal internal hernia, whose origin is generally embryological, is a rare etiology of intestinal obstruction found mainly in young adults. We report here the case of acute intestinal obstruction by left para-duodenal internal hernia in a 36-year-old young man. It was a patient who consulted urgently for occlusive syndrome with cessation of materials and gases. Abdominal percussion noted abdominal tympanism and pre-hepatic dullness was preserved. The flow and icicle signs were negative. palpation did not objectify hepatosplenomegaly and did not find any organomegaly either. On the other hand, she found an epigastric defense. The abdominal X-ray without preparation showed water levels that were wider than high, hail-like. We performed a median above and below umbilical laparotomy and intraoperatively, it was an internal hernia with incarceration of small loops in a voluminous left paraduodenal sac of 12 cm. They were not necrotic and quickly recolored after extrication. We resected the hernial sac and closed the hernial orifice with separate stitches with absorbable suture 0. The postoperative course was simple. The patient was discharged from the hospital on the 4th postoperative day. After 18 months of hindsight, he is doing well.

关键词： paraduodenal Internal Hernia Occlusion Laparotomy

On the functions of astrocyte-mediated neuronal slow inward currents

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

Neural Regeneration Research 2024年第12期19卷 2602-2612页

作者： Balázs pál Department of physiology Faculty of MedicineUniversity of DebrecenDebrecenHungary

Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extra synaptic N-met hyl-D-aspartate receptors with the contribution of *** events are significantly slower than the excitatory postsynaptic *** of slow inward currents are determined by seve ral factors including the mechanisms of astrocytic activation and glutamate release,as well as the diffusion pathways from the release site towards the extra synaptic recepto *** are stimulated by neuronal network activity,which in turn excite neurons,forming an astrocyte-neuron feedback *** as a consequence of brain edema,astrocytic swelling can also induce slow inward currents under pathological *** is a growing body of evidence on the roles of slow inward currents on a single neuron or local network *** events often occur in synchro ny on neurons located in the same astrocytic *** synchronization of neuronal excitability,slow inward currents also set synaptic strength via eliciting timing-dependent synaptic *** addition,slow inward currents are also subject to non-synaptic plasticity triggered by long-la sting stimulation of the excitatory *** note,there might be important regionspecific differences in the roles and actions triggering slow inward *** greater networks,the pathophysiological roles of slow inward currents can be better understood than physiological *** inward currents are identified in the pathophysiological background of autism,as slow inward currents drive early hypersynchrony of the neural *** inward currents are significant contributors to paroxysmal depolarizational shifts/interictal *** events are related to epilepsy,but also found in Alzheimer's disease,parkinson's disease,and stroke,leading to the decline of cognitive *** with features overlapping with slow inward currents(excitatory,N-methyl-Dasp

关键词： astrocyte cortical spreading depolarization gliotransmission glutamate neural synchronization NMDA receptor paroxysmal depolarizational shift slow inward current

An Efficient Approach to Escalate the Speed of Training Convolution Neural Networks

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第2期21卷 258-269页

作者： p pabitha Anusha Jayasimhan Department of Computer Technology Anna UniversityMadras Institute of Technology CampusChennai 600044India

Deep neural networks excel at image identification and computer vision applications such as visual product search, facial recognition, medical image analysis, object detection, semantic segmentation,instance segmentation, and many others. In image and video recognition applications, convolutional neural networks(CNNs) are widely employed. These networks provide better performance but at a higher cost of computation. With the advent of big data, the growing scale of datasets has made processing and model training a time-consuming operation, resulting in longer training times. Moreover, these large scale datasets contain redundant data points that have minimum impact on the final outcome of the model. To address these issues, an accelerated CNN system is proposed for speeding up training by eliminating the noncritical data points during training alongwith a model compression method. Furthermore, the identification of the critical input data is performed by aggregating the data points at two levels of granularity which are used for evaluating the impact on the model *** experiments are conducted using the proposed method on CIFAR-10 dataset on ResNet models giving a 40% reduction in number of FLOps with a degradation of just 0.11% accuracy.

关键词： CNN deep learning image classification model compression

Localized-states quantum confinement induced by roughness in CdMnTe/CdTe heterostructures grown on Si(111) substrates

在线全文

学校读者我要写书评

暂无评论

Journal of Semiconductors 2024年第9期45卷 28-35页

作者： Leonarde N.Rodrigues Wesley F.Inoch Marcos L.F.Gomes Odilon D.D.Couto Jr. bráulio S.Archanjo Sukarno O.Ferreira physics Department Federal University of ViçosaViçosa36570-900Minas GeraisBrazil Instituto de Física Gleb Wataghin Universidade Estadual de CampinasCampinas13083-859São PauloBrazil National Institute of Metrology Quality and Technology(Inmetro) Materials Metrology Division(DIMAT)Xerém2525-020Rio de JaneiroBrazil

This work shows that despite a lattice mismatch of almost 20%, CdMnTe/CdTe/CdMnTe heterostructures grown directly on Si(111) have surprisingly good optical emission properties. The investigated structures were grown by molecular beam epitaxy and characterized by scanning transmission electron microscopy, macro-and micro-photoluminescence. Low temperature macro-photoluminescence experiments indicate three emission bands which depend on the CdTe layer thickness and have different confinement characteristics. Temperature measurements reveal that the lower energy emission band (at 1.48 eV)is associated to defects and bound exciton states, while the main emission at 1.61 eV has a weak 2D character and the higher energy one at 1.71 eV has a well-defined (zero-dimensional, 0D) 0D nature. Micro-photoluminescence measurements show the existence of sharp and strongly circularly polarized (up to 40%) emission lines which can be related to the presence of Mn in the heterostructure. This result opens the possibility of producing photon sources with the typical spin control of the diluted magnetic semiconductors using the low-cost silicon technology.

关键词： CdMnTe/CdTe/CdMnTe heterostructure CdTe/CdMnTe quantum emitters quantum dot-like emission silicon(111)substrate