检索结果-南通市图书馆

Mesozoic mafic magmatism in North China:Implications for thinning and destruction of cratonic lithosphere

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2018年第4期61卷 353-385页

作者： Yongfei zheng zheng xu Zifu ZHAO Liqun DAI CAS Key Laboratory of Crust-Mantle Materials and Environments School of Earth and Space ScienceUniversity of Science and Technology of China

The North China Craton(NCC) has been thinned from >200 km to <100 km in its eastern part. The ancient subcontinental lithospheric mantle(SCLM) has been replaced by the juvenile SCLM in the Meoszoic. During this period, the NCC was destructed as indicated by extensive magmatism in the Early Cretaceous. While there is a consensus on the thinning and destruction of cratonic lithosphere in North China, it has been hotly debated about the mechanism of cartonic *** study attempts to provide a resolution to current debates in the view of Mesozoic mafic magmatism in North China. We made a compilation of geochemical data available for Mesozoic mafic igneous rocks in the NCC. The results indicate that these mafic igneous rocks can be categorized into two series,manifesting a dramatic change in the nature of mantle sources at ~121 Ma. Mafic igneous rocks emplaced at this age start to show both oceanic island basalts(OIB)-like trace element distribution patterns and depleted to weakly enriched Sr-Nd isotope compositions. In contrast,mafic igneous rocks emplaced before and after this age exhibit both island arc basalts(IAB)-like trace element distribution patterrs and enriched Sr-Nd isotope *** difference indicates a geochemical mutation in the SCLM of North China at^121 Ma. Although mafic magmatism also took place in the Late Triassic, it was related to exhumation of the deeply subducted South China continental crust because the subduction of Paleo-Pacific slab was not operated at that time. Paleo-Pacific slab started to subduct beneath the eastern margin of Eruasian continent since the Jurrasic. The subducting slab and its overlying SCLM wedge were coupled in the Jurassic, and slab dehydration resulted in hydration and weakening of the cratonic mantle. The mantle sources of ancient IAB-like mafic igneous rocks are a kind of ultramafic metasomatites that were generated by reaction of the cratonic mantle wedge peridotite notonly with aqueous solutions

关键词： Cratonic destruction Mafic magmas IAB-like series OIB-like series Lithospheric thinning Slab subduction

LCP method for a planar passive dynamic walker based on an event-driven scheme

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2018年第3期34卷 578-588页

作者： xu-Dong zheng Qi Wang School of Aeronautic Science and Engineering Beihang University

The main purpose of this paper is to present a linear complementarity problem （LCP） method for a planar passive dynamic walker with round feet based on an event-driven scheme. The passive dynamic walker is treated as a planar multi-rigid-body system. The dynamic equations of the passive dynamic walker are obtained by using Lagrange＇s equations of the second kind. The normal forces and frictional forces acting on the feet of the passive walker are described based on a modified Hertz contact model and Coulomb＇s law of dry friction. The state transition problem of stick-slip between feet and floor is formulated as an LCR which is solved with an event-driven scheme. Finally, to validate the methodology, four gaits of the walker are simulated： the stance leg neither slips nor bounces; the stance leg slips without bouncing; the stance leg bounces without slipping; the walker stands after walking several steps.

关键词： Passive dynamic walker Non-smooth dynamics Dry friction Linear complementarity problem Stick-slip

Mechanism of SrS∶Ce Thin Film Electroluminescence

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 1999年第2期17卷 25-28页

作者： xu, zheng xu, Chunxiang Lou, Zhidong xu, xurong Northern Jiaotong Univ Beijing China

The influence of the delocalization probability on the mixing interaction between excited levels of Ce3+ and the conduction band of SrS was analysed. The observation of emission wave forms of SrSCe thin film electroluminescence showed that only leading edge emission peak was observed for one sample and the leading and trailing edge emission peaks were observed for another in a half period of sinusoid applied voltage. This difference is related to the influences of sulphur vacancies on the excitation and emission processes. The leading edge emssion is dominated by discrete luminescence caused by direct impact excitation and the trailing edge emission and a part of leading edge emission belong to recombination luminescence caused by impact ionization and delocalization.

关键词： Rare earths Cerium Strontium sulphide Thin film Electroluminescence mechanism

Analysis of coupling mechanism between roll system crossing and liner wear of hot strip mill

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2023年第12期30卷 2425-2435页

作者： Jia-li zheng hua-gui huang Guang-lu Song Zhen-yao Lei Jing-na Sun Shi-min xu School of Mechanical Engineering Yanshan UniversityQinhuangdao066004HebeiChina Equipment Department Shougang Jingtang Iron&Steel Co.Ltd.Tangshan063000HebeiChina

Non-design roll system crossing seriously affects the plate shape and rolling mill *** problem of roll system crossing caused by liner wear was *** finite element model of rolling mill was established to analyze the relationship between roll system crossing and liner *** wear of liner was measured by laser *** range of roll system crossing angle was calculated by considering the amount of stand clearance obtained by numerical *** wear surface morphology of liner was observed and the wear mechanism was *** liner wear experiment was carried out to analyze the wear amount of the ***,based on the Archard wear theory,the prediction model of the cross angle of the roll system and the wear amount of the liner was *** there are more uncertain factors in the field production,the prediction model cannot be considered one by ***,the predicted value is smaller than the actual wear value,but it still has great reference.

关键词： Roll system crossing Wear Abrasion Reaction force Surface morphology Prediction model

HCloud:A Trusted JointCloud Serverless Platform for IoT Systems with Blockchain

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 Communications 2020年第9期17卷 1-10页

作者： zheng huang Zeyu Mi Zhichao hua Institute of Parallel and Distributed Systems Shanghai Jiao Tong UniversityShanghai 200240China

Cloud computing has been exploited in managing large-scale IoT *** cloud servers usually handle a large number of requests from various IoT *** to the fluctuant and heavy workload,the servers require the cloud to provide high scalability,stable performance,low price and necessary ***,traditional clouds usually offer computing service with the abstraction of virtual machine(VM),which can hardly meet these ***,different cloud vendors provide different performance stabilities and price models,which fluctuate according to the dynamic workload.A single cloud cannot satisfy all the requirements of the IoT scenario *** JointCloud computing model empowers the cooperation among multiple public ***,it is still difficult to dynamically schedule the workload on different clouds based on the VM *** paper introduces HCloud,a trusted JointCloud platform for IoT systems using serverless computing *** allows an IoT server to be implemented with multiple serverless functions and schedules these functions on different clouds based on a schedule *** policy is specified by the client and includes the required functionalities,execution resources,latency,price and so *** collects the status of each cloud and dispatches serverless functions to the most suitable cloud based on the schedule *** leveraging the blockchain technology,we further enforce that our system can neither fake the cloud status nor wrongly dispatch the target *** have implemented a prototype of HCloud and evaluated it by simulating multiple cloud *** evaluation results show that HCloud can greatly improve the performance of serverless workloads with negligible costs.

关键词： IoT blockchain serverless jointcloud

Macroscopic superlubricity of potassium hydroxide solution achieved by incorporating in-situ released graphene from friction pairs

在线全文

学校读者我要写书评

暂无评论

Friction 2023年第4期11卷 567-579页

作者： Hongyu LIANG Xinjie CHEN Yongfeng BU Meijuan xu Gang zheng Kaixiong GAO Xijun hua Yonghong FU Junyan ZHANG Institute of Advanced Manufacturing and Modern Equipment Technology School of Mechanical EngineeringJiangsu UniversityZhenjiang 212013China Institute for Energy Research Jiangsu UniversityZhenjiang 212013China ZhenJiang SiLian Mechatronic Technology Co. Ltd.Zhenjiang 212009China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Graphene(G),as a typical two-dimensional material,is often used as an additive for liquid ***,graphene is mostly added to liquid lubricants in a one-time manner in friction;it mainly exists in the form of multilayer agglomerated structures due to theπ–πstacking between graphene sheets,making it unable to fully exert the synergistic lubrication ***,we propose a new macroscopic superlubric system of graphene/potassium hydroxide(G/KOH)solution;and the graphene additive involved is exfoliated in-situ from graphene/epoxy(G/EP)friction pair by friction,continuously providing freshly-peeled graphene into KOH solution and minimizing the adverse effects of graphene ***,the in-situ produced graphene additive has thinner thickness and better anti-aggregation ability,which provide more graphene to accommodate OH−,form more stacked sandwich structures of OH−/graphene/OH−between friction pairs(i.e.,equivalent to a moving pulley block with more wheels),and finally realize *** study develops a new liquid superlubric system suitable for alkaline environments,and at the same time proposes a new way to gradually release graphene additives in situ,rather than adding them all at once,deepening the understanding to liquid superlubricity mechanism,and paving the experimental foundation for the practical application of macroscopic superlubricity.

关键词： liquid superlubricity concentrated potassium hydroxide(KOH)solution in-situ graphene(G)additives stacked sandwich structure electric double layer(EDL) hydrogen bonds(H-bonds)

New possible silver lining for pancreatic cancer therapy:Hydrogen sulfide and its donors

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

Acta Pharmaceutica Sinica B 2021年第5期11卷 1148-1157页

作者： xu hua Yan Xiao Jianan Sun Bao Ji Shanshan Luo Bo Wu Chao zheng Peng Wang Fanxing xu Keguang Cheng Huiming hua Dahong Li Key Laboratory of Structure-Based Drug Design&Discovery Ministry of EducationSchool of Traditional Chinese Materia MedicaShenyang Pharmaceutical UniversityShenyang 110016China School of Pharmaceutical Engineering Shenyang Pharmaceutical UniversityShenyang 110016China Key Laboratory of Cardiovascular and Cerebrovascular Medicine Nanjing Medical UniversityNanjing 211166China Molecular Imaging Laboratory MGH/MIT/HMS Athinoula A.Martinos Center for Biomedical ImagingDepartment of RadiologyMassachusetts General Hospital/Harvard Medical SchoolCharlestownMA 02129USA PET Center Department of Radiology and Biomedical ImagingYale University School of MedicineNew HavenCT 06520USA Department of Biomedical Engineering School of EngineeringChina Pharmaceutical UniversityNanjing 210009China Wuya College of Innovation Shenyang Pharmaceutical UniversityShenyang 110016China State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources School of Chemistry and PharmacyGuangxi Normal UniversityGuilin 541004China

As one of the most lethal diseases,pancreatic cancer shows a dismal overall prognosis and high resistance to most treatment ***,pancreatic cancer escapes early detection during the curable period because early symptoms rarely emerge and specific markers for this disease have not been *** combinations of new drugs,multimodal therapies,and adjuvants prolong survival,most patients still relapse after surgery and eventually ***,the search for more effective treatments for pancreatic cancer is highly relevant and *** a newly re-discovered mediator of gasotransmission,hydrogen sulfide(H2S)undertakes essential functions,encompassing various signaling complexes that occupy key processes in human *** evidence indicates that H2S exhibits bimodal modulation of cancer ***,endogenous or low levels of exogenous H2S are thought to promote cancer,whereas high doses of exogenous H2S suppress tumor ***,inhibition of endogenous H2S production also suppresses tumor ***,H2S biosynthesis inhibitors and H2S supplementation(H2S donors)are two distinct strategies for the treatment of ***,modulation of endogenous H2S on pancreatic cancer has not been studied so ***,H2S donors and their derivatives have been extensively studied as potential therapeutic agents for pancreatic cancer therapy by inhibiting cell proliferation,inducing apoptosis,arresting cell cycle,and suppressing invasion and migration through exploiting multiple signaling *** far as we know,there is no review of the effects of H2S donors on pancreatic *** on these concerns,the therapeutic effects of some H2S donors and NO-H2S dual donors on pancreatic cancer were summarized in this *** H2S donors may be promising compounds for pancreatic cancer treatment.

关键词： Pancreatic cancer Hydrogen sulfide donor Sulfur-containing compound Cell proliferation Antitumor effect Signaling pathway

An Overview of Contour Detection Approaches

在线全文

学校读者我要写书评

暂无评论

International Journal of Automation and computing 2018年第6期15卷 656-672页

作者： Xin-Yi Gong Hu Su De xu zheng-Tao Zhang Fei Shen hua-Bin Yang Research Center of Precision Sensing and Control Institute of Automation Chinese Academy of Science Beijing 100190 China University of Chinese Academy of Science Beijing 100049 China Tianjin Intelligent Technology Institute of Institute of Automation Chinese Academy of Science Co.Ltd Tianjin 300300 China

Object contour plays an important role in fields such as semantic segmentation and image classification. However, the extraction of contour is a difficult task, especially when the contour is incomplete or unclosed. In this paper, the existing contour detection approaches are reviewed and roughly divided into three categories： pixel-based, edge-based, and region-based. In addition, since the traditional contour detection approaches have achieved a high degree of sophistication, the deep convolutional neural networks （DCNNs） have good performance in image recognition, therefore, the DCNNs based contour detection approaches are also covered in this paper. Moreover, the future development of contour detection is analyzed and predicted.

关键词： Contour detection contour salience gestalt principle contour grouping active contour.

在线全文

学校读者我要写书评

暂无评论

四川兴文地区硒的地球化学特征及生物效应

广东微量元素科学 2017年第5期24卷 9-14页

作者：张华郑勇军徐克全时章亮金立新邓欢包雨函四川省地质调查院四川成都610081

四川兴文土地质量调查显示:兴文县表层土壤中硒质量分数为0.075~2.540 mg/kg,平均值为0.43 mg/kg,富硒土地面积占调查面积53.25%,合计734.75 km^2。全区大米硒质量分数平均值为0.064 mg/kg,硒含量处于较为富足水平。水稻中的硒元素含量... 详细信息

四川兴文土地质量调查显示:兴文县表层土壤中硒质量分数为0.075~2.540 mg/kg,平均值为0.43 mg/kg,富硒土地面积占调查面积53.25%,合计734.75 km^2。全区大米硒质量分数平均值为0.064 mg/kg,硒含量处于较为富足水平。水稻中的硒元素含量与根系土中硒元素呈明显正相关关系。根系土中水溶态硒和离子交换态硒含量高时,土壤容易产出富硒作物。

关键词：兴文富硒硒形态