检索结果-南通市图书馆

Sustainable production of high-energy-density jet fuel via cycloaddition reactions

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 Energy Chemistry 2024年第8期95卷 712-722,I0016页

作者： yan-cheng Hu Yingying Zhao Ning Li Jing-pei Cao School of Chemical Engineering and Technology China University of Mining and TechnologyXuzhou 221116JiangsuChina School of Education Science Jiangsu Normal UniversityXuzhou 221116JiangsuChina CAS Key Laboratory of Science and Technology on Applied Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina

Developing an energy supply-chain based on renewable biomass holds great potential to build a low carbon ***-energy-density(HED)jet fuel,featuring unique fused/strained cycloalkanes,is of great significance for volume-limited military aircrafts,as their high density and combustion heat can extend flight duration and increase the ***,the exploration of biomass-based routes towards HED fuel has drawn much attention over the past *** reaction features rapid construction of various carbocycles in an atom-and step-economical *** elegant strategy has been widely applied in the manufacture of sustainable HED *** we carefully summarize the progress achieved in this fascinating area and the review is categorized by the cycloaddition patterns including[4+2],[2+2],[4+4],and[2+1]***,the energy densities of the as-prepared biofuels and petroleumbased fuels(conventional Jet-A and advanced JP-10)are also *** review will provide important insights into rational design of new HED fuel with different ring-types/sizes and inspire the chemists to turn those literature studies into practical applications in military field.

关键词： High-energy-density fuel Biomass-based chemicals Cycloaddition Cycloalkanes Catalysis

Effectiveness of groundwater extraction in Beijing since the ingauration of the first phase of the South-to-North Water Diversion Project, China

在线全文

学校读者我要写书评

暂无评论

地下水科学与工程:英文版 2023年第3期11卷 294-307页

作者： Yuan-yuan Gao Qing-yu Sun Ai-xin Wen yan-pei cheng Bureau of South to North Water Transfer of Planning Designing and ManagementMinistry of Water ResourcesBeijing 100038China Institute of Hydrogeology and Environmental Geology Chinese Academy of Geological SciencesShijiazhuang 050061China

This study assess the effectiveness of groundwater pressure extraction in Beijing since the opening of the first phase of the South-to-North Water Diversion Project,using survey and evaluation ***,an analysis of water consumption structure and the usage of diverted river water in Beijing in recent years was ***,the volume of groundwater pressure extraction in Beijing after the 33 project's inauguration was examined,revealing a decrease from 1.96 billion m^(3) in 2014 to 1.35 billion m^(3) in *** proportion of water supply reduced from 52.3%in 2014 to 33.3%in 2020,leading to an optimized water supply *** the end of 2020,groundwater pressure extraction in Beijing is estimated at 446 million m3,with a substantial reduction in over-exploitation of *** resources have been effectively replenished,and the strategic reserve capacity has been ***,this study evaluates the change in groundwater levels as an indicator of the effectiveness of pressure *** declining trend of groundwater levels in Beijing has been effectively mitigated,and there has been a consistent rebound in groundwater levels over the past five years.

关键词： Beijing City South-to-North Water Diversion Groundwater Over-exploitation Groundwater Pressure Extraction

Research hotspots and trends of groundwater and ecology studies:Based on a bibliometric approach

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 Groundwater Science and Engineering 2023年第1期11卷 20-36页

作者： Jun Liu yan-pei cheng Feng-e Zhang Xue-ru Wen Liu yang Institute of Hydrogeology and Environmental Geology Chinese Academy of Geological SciencesShijiazhuang 050061China Key Laboratory of Groundwater Sciences and Engineering Ministry of Natural ResourcesZhengding 050803HebeiChina Comprehensive Survey and Management Center for Natural Resources China Geological SurveyBeijing 10055China

Groundwater,as a critical component of the hydrological cycle,is essential for sustainable ecosystem *** clarify the current status of domestic and overseas research,and to identify hotspots,frontier and future trends of groundwater and ecology research,this study utilizes bibliometric methods and CiteSpace software to examine relevant published articles in the Web of Science(WOS)and CNKI databases from 1978 to ***,this study analyzes(1)the annual number of published papers;(2)research institutions;(3)keywords;and(4)evolution of research *** findings reveal that the United States,China,and Germany are the top three countries in groundwater and ecology *** research hotspots mainly focus on microbial ecology,climate change,groundwater-surface water interactions in the hyporheic zone,biodiversity,and submarine groundwater discharge,while domestic research hotspots mainly focus on ecological water conveyance,ecological flow,groundwater development and utilization,groundwater pollution,and groundwater and ecological *** domestic and international research hotspots exhibit interdisciplinary features with diverse research objects and assessment *** research in this area is expected to focus on topics such as contamination,groundwater quality,framework,mechanism,spatial distribution,and dissolved organic ***,the study of ecological recharge,ecological flow,ecological protection,water intake and use will continue to be the hot topics domestically.

关键词： Ecological assessment Keywords clustering Knowledge graphing Ecological security Ecological restoration

Exponential Synchronization of Delayed Stochastic Complex Dynamical Networks via Hybrid Impulsive Control

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 785-787页

作者： Yao Cui pei cheng Xiaohua Ge the School of Mathematic Science Anhui UniversityHefei 230601China IEEE the School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourne VIC 3122Australia

Dear Editor,This letter addresses the synchronization problem of a class of delayed stochastic complex dynamical networks consisting of multiple drive and response *** aim is to achieve mean square exponential synchronization for the drive-response nodes despite the simultaneous presence of time delays and stochastic noises in node dynamics.

关键词： dynamics stochastic letter

Perioperative and long-term results of ultrasonography-guided single-and multiple-tract percutaneous nephrolithotomy for staghorn calculi

在线全文

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2024年第7期12卷 1243-1250页

作者： Rui-Xiang cheng Ni Dai yan-Min Wang pei Qi Fen Chen Department of Urology Wuhan Ninth HospitalWuhan 430081Hubei ProvinceChina Department of Urinary Pain Wuhan Hankou HospitalWuhan 430000Hubei ProvinceChina Pre-hospital Emergency Department Wuhan Puren HospitalWuhan 430081Hubei ProvinceChina Department of Orthopedic Trauma Surgery Wuhan Hankou HospitalWuhan 430000Hubei ProvinceChina Department of Ultrasound Hubei Provincial Hospital of Integrated Traditional Chinese and Western MedicineWuhan 430015Hubei ProvinceChina

BACKGROUND It is possible that this condition will lead to urosepsis and progressive deterioration of renal function in the absence of surgical *** recent clinical studies have shown that multi-tract percutaneous nephrolithotomy(MPCNL)has a similar stone free rate(SFR)as standard percutaneous nephrolithotomy(S-PCNL).As a result,M-PCNL was also recommended as a treatment option for staghorn *** To examine the perioperative and long-term results of ultrasonography-guided single-and *** This was a retrospective cohort *** March 2021 and January 2022,the urology department of our hospital selected patients for the treatment of staghorn calculi using percutaneous *** primary outcomes were com plication rate and SFR,and the characteristics of patients,operative parameters,laboratory measurements were also *** In total,345 patients were enrolled in the study(186 in the S-PCNL group and 159 in the M-PCNL group).The SFR in the M-PCNL group was significantly higher than that in the S-PCNL group(P=0.033).Moreover,the incidence rates of hydrothorax(P=0.03)and postoperative infection(P=0.012)were higher in the M-PCNL group than in the S-PCNL *** regression analysis demonstrated that post-operative white blood cell count(OR=2.57,95%CI:1.90-3.47,P<0.001)and stone size(OR=1.59,95%CI:1.27-2.00,P<0.001)were associated with a higher overall complication rate in the S-PCNL *** mass index(OR=1.22,95%CI:1.06-1.40,P=0.004)and stone size(OR=1.70,95%CI:1.35-2.15,P<0.001)were associated with increased overall complications in the M-PCNL *** Multiple access tracts can facilitate higher SFR while slightly increasing the incidence of acceptable complications.

关键词： Single-tract percutaneous nephrolithotomy Multiple-tract percutaneous nephrolithotomy Staghorn calculi Ultrasonography

Spacelike Framed Curves with Lightlike Components and Singularities of Their Evolutes and Focal Surfaces in Minkowski 3-space

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 Mathematica Sinica,English Series 2024年第6期40卷 1521-1532页

作者： Peng cheng LI Dong He pei Xin ZHAO School of Mathematics and Statistics Northeast Normal UniversityChangchun 130024P.R.China Department of Mathematics Harbin Institute of TechnologyWeihai 264209P.R.China School of Mathematics and Statistics Qingdao UniversityQingdao 266071P.R.China

In this paper,we define the evolute and focal surface of a spacelike framed curve with lightlike components in Minkowski *** is a generalization of the previous results of regular spacelike curves,since singularities are allowed in the original spacelike curves studied by spacelike framed curves with lightlike ***,we show a new geometric invariant to characterise singularities of the focal ***,the classification theorem and recognition theorem for the singularities of the focal surface in generic are also given.

关键词： Evolutes focal surfaces spacelike framed curves singularities

Effective assignment of positional isomers in dimeric shikonin and its analogs by ^(1)H NMR spectroscopy

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第5期35卷 223-226页

作者： Ling-Hao Zhao Hai-Wei yan Jian-Shuang Jiang Xu Zhang Xiang Yuan Ya-Nan yang pei-cheng Zhang State Key Laboratory of Bioactive Substance and Function of Natural Medicines Institute of Materia MedicaChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050China

An approach for distinguishing two types of positional isomers of dimeric shikonin and its analogs was explored with ^(4)JC,H long-range correlation by prolonging the acquisition time at ^(2,3)JC,H values of 2.0 and ***,the ^(1)H(proton)nuclear magnetic resonance(NMR)pattern of phenolic hydroxyl protons was developed as a“diagnosis signal”to ascertain the relative location of each side chain in DMSO-d_(6) at sample concentrations of 0.022-0.034 mol/*** chemical shift differences of 0.6ppm between OH-5' and OH-1 and between OH-8'and OH-4 are assigned to Type A and Type B,*** reported ambiguous structures were corrected by this ***,the steric structures of isolated compounds were elucidated by quantum chemical calculations of electronic circular dichroism(ECD)spectra.

关键词： Arnebia euchroma Dimeric hydroxyl naphthoquinones Positional isomers ^(1)H NMR spectroscopy Chemical shift difference

“Capture-activation-recapture” mechanism-guided design of double-atom catalysts for electrocatalytic nitrogen reduction

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2024年第9期96卷 437-447页

作者： cheng He Shiqi yan Wenxue Zhang State Key Laboratory for Mechanical Behavior of Materials School of Materials Science1nd EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina School of Materials Science1nd Engineering Chang’an UniversityXi’an 710064ShaanxiChina

Compared with the traditional industrial nitrogen fixation, electrocatalytic methods, especially those utilizing double-atom catalysts containing nonmetals, can give good consideration to the economy and environmental protection. However, the existing “acceptance-donation” mechanism is only applicable to bimetallic catalysts and nonmetallic double-atom catalysts containing boron atoms. Herein, a novel “capture-activation-recapture” mechanism for metal-nonmetal double-atom catalyst is proposed to solve the problem by adjusting the coordination environments of nonmetallic atoms and utilizing the activation effect of metal atoms on nitrogen. Based on this mechanism, the nitrogen reduction reaction (NRR) activity of 48 structures is calculated by density functional theory calculation, and four candidates are selected as outstanding electrocatalytic nitrogen reduction catalysts: Si-Fe@NG (U_(L) = –0.14 V), Si-Co@NG (U_(L)= –0.15 V), Si-Mo@BP1 (U_(L) = 0 V), and Si-Re@BP1 (U_(L) = –0.02 V). The analyses of electronic properties further confirm “capture-activation-recapture” mechanism and suggest that the difference in valence electron distribution between metal and Si atoms triggers the activation of N≡N bonds. In addition, a machine learning approach is utilized to generate an expression and an intrinsic descriptor that considers the coordination environment to predict the limiting potential. This study offers profound insight into the synergistic mechanism of TM and Si for NRR and guidance in the design of novel double-atom nitrogen fixation catalysts.

关键词： "Capture-activation-recapture"mechanism Double-atom catalyst Nitrogen reduction reaction Density functional theory

Model-driven path planning for robotic plasma cutting of branch pipe with single Y-groove based on pipe-rotating scheme

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Manufacturing 2024年第1期12卷 94-107页

作者： yan Liu Qiu Tang Xin-cheng Tian School of Control Science and Engineering Shandong UniversityJinan250061People’s Republic of China Engineering Research Center of Intelligent Unmanned System Ministry of EducationJinan250061People’s Republic of China School of Mechanical and Electronic Engineering Shandong Jianzhu UniversityJinan250101People’s Republic of China

The automatic cutting of intersecting pipes is a challenging task in *** improved automation and accuracy,this paper proposes a model-driven path planning approach for the robotic plasma cutting of a branch pipe with a single ***,it summarizes the intersection forms and introduces a dual-pipe intersection *** on this model,the moving three-plane structure(a description unit of the geometric characteristics of the intersecting curve)is constructed,and a geometric model of the branch pipe with a single Y-groove is ***,a novel mathematical model for plasma radius and taper compensation is ***,the compensation model and groove model are integrated by establishing movable ***,to prevent collisions between the plasma torch and workpiece,the torch height is planned and a branch pipe-rotating scheme is *** the established models and moving frames,the planned path description of cutting robot is provided in this novel *** accuracy of the proposed method is verified by simulations and robotic cutting experiments.

关键词： Automatic groove cutting of intersecting pipes Model-driven robot path planning Plasma beam radius and taper compensation