检索结果-南通市图书馆

Dynamic Bubble Behaviour during microscale Subcooled Boiling

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2005年第11期22卷 2881-2884页

作者：王昊彭晓峰 David m. christopher Laboratory of Phase-Change and Interracial Transport Phenomena Department of Thermal Engineering Tsinghua University Beijing 100084

Bubble cycles, including initiation, growth and departure, are the physical basis of nucleate boiling. The present investigation, however, reveals unusual bubble motions during subcooled nucleate boiling on microwires 25 or 100μm in diameter. Two types of bubble motions, bubble sweeping and bubble return, are observed in the experiments. Bubble sweeping describes a bubble moving back and forth along the wire, which is motion parallel to the wire. Bubble return is the bubble moving back to the wire after it has detached or leaping above the wire. Theoretical analyses and numerical simulations are conducted to investigate the driving mechanisms for both bubble sweeping and return. marangoni flow from warm to cool regions along the bubble interface is found to produce the shear stresses needed to drive these unusual bubble movements.

关键词： subcooled boiling ELECTRIC WIRE driving mechanism bubbles Nucleate boiling Shear stress

Strategies towards statistically robust interpretations of in situ U-Pb zircon geochronology

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2016年第4期7卷 581-589页

作者： christopher J.Spencer christopher L.Kirkland Richard J.m.Taylor The Institute of Geoscience Research(TIGeR) Department of Applied GeologyWestern Australian School of MinesCurtin UniversityWA 6102Australia Centre for Exploration Targeting-Curtin Node Department of Applied GeologyWestern Australian School of MinesCurtin UniversityWA 6102Australia Australian Research Council Centre of Excellence for Core to Crust Fluid SystemsPerthWA 6102Australia

Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablation and secondary ionization mass spectrometry） has allowed for large amounts of data to be generated in a relatively short amount of time and such large volume datasets offer the ability to address a range of geological questions that would otherwise remain intractable （e.g. detrital zircons as a sedi- ment fingerprinting method）. The ease of acquisition, while bringing benefit to the Earth science com- munity, has also led to diverse interpretations of geochronological data. In this work we seek to refocus U -Pb zircon geochronology toward best practice by providing a robust statistically coherent workflow. We discuss a range of data filtering approaches and their inherent limitations （e.g. discordance and the reduced chi-squared; mSWD）. We evaluate appropriate mechanisms to calculate the most geologically appropriate age from both 238U/206pb and 207pb/206pb ratios and demonstrate the cross over position when chronometric power swaps between these ratios. As our in situ analytical techniques become progressively more precise, appropriate statistical handing of U-Pb datasets will become increasingly pertinent.

关键词： Zircon Geochronology U-Pb Geostatistics mSWD

Bubble Coalescence Heat Transfer During Subcooled Nucleate Pool Boiling

在线全文

学校读者我要写书评

暂无评论

工程热物理学报 2012年第12期33卷 2171-2175页

作者： Abdoulaye Coulibaly LIN Xipeng Bi Jingliang David m christopher Department of Thermal Engineering Tsinghua University

Bubble coalescence during subcooled nucleate pool boiling was investigated experimentally using constant wall temperature boundary conditions while the wall heat flux was measured at a various locations to understand the effects of coalescence on the heat *** observations showed that the coalesced bubble moved and oscillated on the heater surface with significant heat transfer variations prior to *** observations also showed coalescence with no increase in the heat transfer *** heat flux for boiling with coalescence fluctuated much more than for single bubble boiling due to the vaporization of the liquid layer trapped between the bubbles.

关键词： microheater pool boiling bubble coalescence bubble dynamics

Protecting miners from coal bursts during development above historic mine workings in Harlan County,KY

在线全文

学校读者我要写书评

暂无评论

International Journal of mining Science and Technology 2021年第1期31卷 111-116页

作者： christopher mark mine Safety and Health Administration PittsburghPA 15236USA

In order to reach a large,untapped reserve of high-quality coal,D8 Cloverlick mine proposed to mine a corridor nearly 600 m deep beneath the Benham Spur of Black mountain,Kentucky’s highest peak.D8 Cloverlick mine was extracting the Owl seam,but the corridor’s route lay approximately 20 m above century-old mine workings in the C–(Darby)*** to the concern,three serious coal bursts had recently occurred in nearby Owl seam *** of the old workings seemed to indicate that the underlying C–seam had been fully ***,two of the coal bursts had occurred above areas where the C–Seam was also shown as mined *** Safety and Health Administration(mSHA)Technical Support therefore investigated the records of past mining to better understand the old mine *** conditions observed in current Owl seam workings were also compared with the maps of the old C–seam *** study concluded that the presence of hazardous underlying remnants could not be ruled *** mitigate the burst risk,D8 Cloverlick mine adopted a strategy of stress probe drilling.A self-propelled coal drill was used to auger 11.5-m-long,small diameter holes in advance of *** each hole was drilled,the cuttings were measured to detect the presence of highly stressed *** the crossing was successfully completed without incident.

关键词： Coal bursts Underground mining Room-and-pillar Destressing

melanization in living organisms: a perspective of species evolution

在线全文

学校读者我要写书评

暂无评论

Protein & Cell 2010年第9期1卷 830-841页

作者： christopher J Vavricka Bruce m.Christensen Jianyong Li CAS Key Laboratory of Pathogenic microbiology and Immunology Institute of MicrobiologyChinese Academy of Sciences(CASPMI)Beijing 100101China Department of Pathobiology University of Wisconsin-MadisonMadisonWI 53706USA Department of Biochemistry Virginia TechBlacksburgVA 24061USA

Eumelanin is a heteropolymer that is generally composed of hydroxylated indole residues and plays diverse protective functions in various *** is derived from the amino acid tyrosine and production of melanin is a highly complex oxidative process with a number of steps that can either proceed enzymatically or *** melanin plays important protective roles in many species,during melanization,particularly in steps that can proceed non-enzymatically,many toxic intermediates are produced,including semiquinones,dopaquinone,indole-quinones and moreover,the production of many reactive oxygen *** mitigate the production of reactive species,a number of proteins that regulate the biochemical process of melanization have evolved in various living species,which is closely related to adaptation and physiological *** this communication,we discuss differences between non-enzymatic and enzymatic processes of melanization and the enzymatic regulation of melanization in difference species with an emphasis on differences between mammals and *** between melanization and insect sclerotization is also emphasized which raises some interesting questions about the current models of these pathways.

关键词： melanization melanogenesis sclerotization tanning dopa tyrosinase dopachrome tautomerase

Cronkhite-Canada Syndrome:an unusual finding of gastro-intestinal adenomatous polyps in a syndrome characterized by hamartomatous polyps

在线全文

学校读者我要写书评

暂无评论

Gastroenterology Report 2015年第3期3卷 254-257页

作者： christopher m.Flannery John A.Lunn Department of Gastroenterology Loma Linda University Medical CenterLoma LindaCAUSA Department of Gastroenterology Veterans Affairs Loma Linda Healthcare System Loma LindaCAUSA

Cronkhite-Canada syndrome is a rare,hamartomatous polyposis syndrome of unknown *** gastrointestinal polyps,alopecia,onychodystrophy,cutaneous hyperpigmentation,abdominal pain,diarrhea,and complications of weight loss are typical of the *** this report,we describe a pathological finding of colonic adenomatous polyposis as opposed to hamartomatous *** also describe our treatment,long-term therapeutic plan,and the need for further research.

关键词： Cronkhite-Canada syndrome gastro-intestinal adenomatous polyps hamartomatous polyps

Influence of size effect and boundary conditions on temperature overshooting in nanoscale thermal conduction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2014年第12期59卷 1334-1339页

作者： Xuefang Li mingtian Xu David m.christopher Key Laboratory for Thermal Science and Power Engineering of ministry of Education Tsinghua University Institute of Thermal Science and Technology Shandong University

The temperature overshooting phenomenon in one-dimensional nanoscale heat conduction in thin films is studied for various boundary *** results show that when ballistic heat transport strongly affects the heat transport process,temperature overshooting is more likely to occur.A sudden increase of temperature on only one surface of a thin film cannot trigger temperature overshooting,while symmetric boundary temperature perturbations lead to the largest temperature *** heat conduction is also studied in a nanoscale *** analytic results show that Fourier’s law may severely underestimate the temperatures in nanofilms as well as in nanoareas when temperature overshooting occurs.

关键词：边界温度过冲现象边界条件纳米级热传导尺寸效应纳米薄膜热传递过程

Combined analysis of land cover change and NDVI trends in the Northern Eurasian grain belt

在线全文

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2012年第2期6卷 177-187页

作者： christopher K. WRIGHT Kirsten m. de BEURS Geoffrey m. HENEBRY South Dakota State University Geographic Information Science Center of Excellence (GIScCE) Brookings South Dakota 57007 USA The University of Oklahoma Department of Geography and Environmental Sustainability Norman OK 73019 USA

We present an approach to regional environ- mental monitoring in the Northern Eurasian grain belt combining time series analysis of mODIS normalized difference vegetation index （NDVI） data over the period 2001-2008 and land cover change （LCC） analysis of the 2001 and 2008 mODIS Global Land Cover product （mCD 12Q 1）. NDVI trends were overwhelmingly negative across the grain belt with statistically significant （p ≤0.05） positive trends covering only 1% of the land surface. LCC was dominated by transitions between three classes; cropland, grassland, and a mixed cropland/natural vegeta- tion mosaic. Combining our analyses of NDVI trends and LCC, we found a pattern of agricultural abandonment （cropland to grassland） in the southern range of the grain belt coinciding with statistically significant （p≤0.05） negative NDVI trends and likely driven by regional drought. In the northern range of the grain belt we found an opposite tendency toward agricultural intensification; in this case, represented by LCC from cropland mosaic to pure cropland, and also associated with statistically significant （p≤0.05） negative NDVI trends. Relatively small clusters of statistically significant （p ≤ 0.05） positive NDVI trends corresponding with both localized land abandonment and localized agricultural intensification show that land use decision making is not uniform across the region. Land surface change in the Northern Eurasian grain belt is part of a larger pattern of land cover land use change （LCLUC） in Eastern Europe, Russia, and former territories of the Soviet Union following realignment of socialist land tenure and agricultural markets. Here, we show that a combined analysis of LCC and NDVI trends provides a more complete picture of the complex- ities of LCLUC in the Northern Eurasian grain belt,involving both broader climatic forcing, and narrower anthropogenic impacts, than might be obtained from either analysis alone.

关键词： land cover change mODIS NDVI NorthernEurasian grain belt Kazakhstan Russia time seriesanalysis Ukraine

Automated Deep Learning Based Cardiovascular Disease Diagnosis Using ECG Signals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computer Systems Science & Engineering 2022年第7期42卷 183-199页

作者： S.Karthik m.Santhosh m.S.Kavitha A.christopher Paul Department of Computer Science&Engineering SNS College of TechnologyCoimbatore641035India Department of Information Technology Karpagam Institute of TechnologyCoimbatore641105India

Automated biomedical signal processing becomes an essential process to determine the indicators of diseased *** the same time,latest develop-ments of artiﬁcial intelligence(AI)techniques have the ability to manage and ana-lyzing massive amounts of biomedical datasets results in clinical decisions and real time *** can be employed for medical imaging;however,the 1D biomedical signal recognition process is still needing to be ***(ECG)is one of the widely used 1-dimensional biomedical sig-nals,which is used to diagnose cardiovascular *** assisted diag-nostic modelsﬁnd it difﬁcult to automatically classify the 1D ECG signals owing to time-varying dynamics and diverse proﬁles of ECG *** resolve these issues,this study designs automated deep learning based 1D biomedical ECG sig-nal recognition for cardiovascular disease diagnosis(DLECG-CVD)*** DLECG-CVD model involves different stages of operations such as pre-proces-sing,feature extraction,hyperparameter tuning,and classiﬁ*** the initial stage,data pre-processing takes place to convert the ECG report to valuable data and transform it into a compatible format for further *** addition,deep belief network(DBN)model is applied to derive a set of feature ***,improved swallow swarm optimization(ISSO)algorithm is used for the hyper-parameter tuning of the DBN ***,extreme gradient boosting(XGBoost)classiﬁer is employed to allocate proper class labels to the test ECG *** order to verify the improved diagnostic performance of the DLECG-CVD model,a set of simulations is carried out on the benchmark PTB-XL dataset.A detailed comparative study highlighted the betterment of the DLECG-CVD model interms of accuracy,sensitivity,speciﬁcity,kappa,mathew correlation coefﬁcient,and Hamming loss.

关键词： Biomedical signals 1-dimensional signal electrocardiogram artiﬁcial intelligence deep learning cardiovascular disease decision making