检索结果-南通市图书馆

Benchmark Computations of the Phase Field Crystal and Functionalized Cahn-Hilliard Equations via Fully Implicit,Nesterov Accelerated Schemes

在线全文

学校读者我要写书评

暂无评论

Communications in Computational Physics 2023年第2期33卷 367-398页

作者： jea-Hyun park Abner j.Salgado Steven M.Wise Department of Mathematics University of California Santa BarbaraCA 93106USA Department of Mathematics University of Tennessee KnoxvilleTN 37996USA.

We introduce a fast solver for the phase field crystal(PFC)and functionalized Cahn-Hilliard(FCH)equations with periodic boundary conditions on a rectangular domain that features the preconditioned Nesterov’s accelerated gradient descent(PAGD)*** discretize these problems with a Fourier collocation method in space,and employ various second-order schemes in *** observe a significant speedup with this solver when compared to the preconditioned gradient descent(PGD)*** the PAGD solver,fully implicit,second-order-in-time schemes are not only feasible to solve the PFC and FCH equations,but also do so more efficiently than some semi-implicit schemes in some cases where accuracy issues are taken into *** computations of four different schemes for the PFC and FCH equations are conducted and the results indicate that,for the FCH experiments,the fully implicit schemes(midpoint rule and BDF2 equipped with the PAGD as a nonlinear time marching solver)perform better than their IMEX versions in terms of computational cost needed to achieve a certain *** the PFC,the results are not as conclusive as in the FCH experiments,which,we believe,is due to the fact that the nonlinearity in the PFC is milder nature compared to the FCH *** also discuss some practical matters in applying the *** introduce an averaged Newton preconditioner and a sweeping-friction strategy as heuristic ways to choose good preconditioner *** sweeping-friction strategy exhibits almost as good a performance as the case of the best manually tuned parameters.

关键词： Phase field crystal functionalized Cahn-Hilliard preconditioning Nesterov acceleration nonlinear solver.

Biochar-based materials as remediation strategy in petroleum hydrocarbon-contaminated soil and water:Performances,mechanisms,and environmental impact

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 Environmental Sciences 2024年第4期138卷 350-372页

作者： Zhuo Wei YiWei Yang Liu Shuai Niu Yaxi Xu jong-Hwan park jim j.Wang Faculty of Environmental Science&Engineering Kunming University of Science&TechnologyKunming 650500China School of Plant Environment&Soil SciencesLouisiana State University AgCenter.Baton RougeLA 70803USA Department of Life Resources Industry Dong-A University37Nakdong-daero 550 beon-gilSaha-guBusan 49315South Korea

Petroleum contamination is considered as a major risk to the health of humans and *** as low-cost and eco-friendly carbon materials,have been widely used for the removal of petroleum hydrocarbon in the *** purpose of this paper is to review the performance,mechanisms,and potential environmental toxicity of biochar,modified biochar and its integration use with other materials in petroleum contaminated soil and ***,the use of biochar in oil-contaminated water and soil as well as the factors that could influence the removal ability of biochar were systematically *** addition,the modification and integrated use of biochar for improving the removal efficiency were summarized from the aspects of sorption,biodegradation,chemical degradation,and ***,the functional impacts and associated ecotoxicity of pristine and modified biochars in various environments were ***,some shortcoming of current approaches,and future research needs were provided for the future direction and challenges of modified biochar ***,this paper gain insight into biochar application in petroleum remediation from the perspectives of performance enhancement and environmental sustainability.

关键词： Petroleum contamination Adsorbent Bioremediation Biochar modification Ecotoxicity

Arabidopsis CAMTA Transcription Factors Regulate Pipecolic Acid Biosynthesis and Priming of Immunity Genes

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2020年第1期13卷 157-168页

作者： Yongsig Kim Sarah j.Gilmour Lumen Chao Sunchung park Michael F.Thomashow MSU-DOE Plant Research Laboratory Michigan State UniversityEast LansingMl 48824USA MSU Plant Resilience Institute Michigan State UniversityEast LansingMl 48824USA Department of Plant Soil and Microbial SciencesMichigan State UniversityEast LansingMl 48824USA Present address:U.S.Department of Agriculture Agricultural Research Service1636 East Alisal St.SalinasCA 93905USA

The Arabidopsis thaliana Calmodulin-binding Transcription Activator(CAMTA)transcription factors CAMTA1,CAMTA2,and CAMTA3(CAMTA123)serve as master regulators of salicylic acid(SA)-mediated immunity,repressing the biosynthesis of SA in healthy ***,we show that CAMTA123 also repress the biosynthesis of pipecolic acid(Pip)in healthy *** of CAMTA123 function resulted in the induction of AGD2-like defense response protein 1(ALD1),which encodes an enzyme involved in Pip *** of ALD1 resulted in the accumulation of high levels of Pip,which brought about increased levels of the SA receptor protein NPR1 without induction of NPR1 expression or requirement for an increase in SA ***-mediated induction of ALD1 and genes regulating the biosynthesis of SA—CBP60g,SARD1,PAD4,and EDS1—was largely dependent on ***,Pip-mediated increase in NPR1 protein levels was associated with priming of Pip and SA biosynthesis genes to induction by low levels of *** together,our findings expand the role for CAMTA123 in regulating key immunity genes and suggest a working model whereby loss of CAMTA123 repression leads to the induction of plant defense genes and initiation of SAR.

关键词： Arabidopsis thaliana pipecolic acid salicylic acid plant immunity priming CAMTA transcription factors

Carbonaceous aerosol in ambient air: Parallel measurements between water cyclone and carbon analyzer

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2019年第3期17卷 153-158页

作者： Min-Suk Bae james j. Schwab Da-jeong park Zang-Ho Shon Ki-Hyun Kim Department of Environmental Engineering Mokpo National University Muan South Korea Atmospheric Sciences Research Center University at Albany State University of New York 251 Fuller Road Albany NY 12203 USA Environmental Analysis Center Gwangju Institute of Science and Technology Gwangju South Korea Department of Environmental Engineering Dong-Eui University Busan South Korea Department of Civil and Environmental Engineering Hanyang University Seoul South Korea

A water cyclone,developed to collect and preserve biological aerosols in a small liquid flow,was interfaced with a total organic carbon analyzer to measure the aerosol organic and inorganic carbon *** total carbon was compared against parallel measurements of elemental carbon (EC) and organic carbon (OC) using a Sunset Real Time ECOC Analyzer between 12-29 january 2009.A National Institute for Occupational Safety and Health (NIOSH) like protocol for the measurements included four temperature steps ending at 840 ℃ for OC under a helium atmosphere followed by two temperature steps ramped to 850 ℃ for EC in a helium-oxygen atmosphere,Carbon data comparison between the water cyclone-TOC and the TOC measured by the analyzer indicated good agreement (r2 =0.82,linear regression slope =0.98,p < 0.001).Analyses of the relationship between total water organic carbon and OC,investigated using data sets from case studies spanning two different events,suggested it was possible to distinguish between the primary and secondary sources.

关键词： Water soluble organic carbon Total organic carbon Carbonaceous material

A study on low emittance injector and undulator for PAL-XFEL

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Power Laser Science and Engineering 2015年第3期3卷 41-49页

作者： j.Hong j.-H.Han S.j.park Y.G.jung D.E.Kim H.-S.Kang j.Pflueger Pohang Accelerator Laboratory European XFEL

For the success of PAL-XFEL, two critical systems, namely a low emittance injector and a variable gap out-vacuum undulator, are under development. In order to realize the target emittance of the PAL-XFEL injector we carried out an optimization study of various parameters, such as the laser beam transverse profile, the laser pulse length, the laser phase,and the gun energy. The transverse emittance measured at the Injector Test Facility(ITF) is εx=0.48±0.01 mm *** undulator prototype based on the EU-XFEL design and modified for PAL-XFEL was built and tested. A local-K pole tuning procedure was developed and tested. A significant reduction(90%) of the local-K fluctuation was observed. The requirement of undulator field reproducibility better than 2×10-4and the undulator gap setting accuracy below 1 μm were achieved for the prototype. The optical phase jitter after the pole height tuning at the tuning gap was calculated to be 2.6? rms, which satisfies the requirement of 5.0?.

关键词： emittance free-electron lasers(FELs) photocathode RF-gun undulator

Report of a Dicephalic Steppes Ratsnake (Elaphe dione) Collected in South Korea

在线全文

学校读者我要写书评

暂无评论

Asian Herpetological Research 2013年第3期4卷 182-186页

作者： Il-Hun KIM ja-Kyeong KIM jonathan j.FONG Daesik park Department of Biology Kangwon National University School of Biological Sciences Seoul National University Division of Science Education Kangwon National University

In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal individuals, the dicephalic snake has divided ventral scales under the necks of the bifurcated columns. The snout- vent length （SVL） and overall total length of the individual are shorter than those of normal snakes of the same age. Nevertheless, the counts of nine different scale types that are often used for classification are all within the ranges of normal individuals. As far as we know, this is the first detailed morphological description of a dicephalic E. dione in the scientific literature.

关键词： dicephalism morphology Steppes Ratsnake Elaphe dione

A Study of the Critical Nozzle for Flow Rate Measurement of High-Pressure Hydrogen Gas

在线全文

学校读者我要写书评

暂无评论

journal of Thermal Science 2007年第1期16卷 28-32页

作者： H.D.Kim j.H.Lee K.A.park T.Setoguchi S.Matsuo School of Mechanical Engineering Andong National University388Songchun-dongAndong 760-749Korea Dynamics Group Korea Research Institute of Standards and SciencePO Box 102YusongTaejon 305-606Korea Department of Mechanical Enginering.Saga University 1Honjo—machiSaga-shiSaga 840—8502Japan

The mass flow rate measurement using a critical nozzle shows the validity of the inviscid theory, indicating that the discharge coefficient increases and approaches unity as the Reynolds number increases under the ideal gas law However, when the critical nozzle measures the mass flow rate of a real gas such as hydrogen at a pressure of hundreds bar, the discharge coefficient exceeds unity, and the real gas effects should be taken into account. The present study aims at investigating the flow features of the critical nozzle using high-pressured hydrogen gas. The axisymmetric, compressible Navier-Stokes computation is employed to simulate the critical nozzle flow, and a fully implicit finite volume method is used to discretize the governing equation system. The real gas effects are simulated to consider the intermolecular forces, which account for the possibility of liquefying hydrogen gas. The computational results are compared with past experimental data. It has been found that the coefficient of discharge for real gas can be corrected properly below unity adopting the real gas assumption.

关键词： critical nozzle compressible flow hydrogen gas ideal gas law real gas effect

Geographically evaluating urban-wildland juxtapositions across 36 urban areas in the United States

在线全文

学校读者我要写书评

暂无评论

Geography and Sustainability 2022年第2期3卷 139-151页

作者： Sarah j.Hinners jeffRose Dong-ah Choi Keunhyun park University of Utah Salt Lake City 84112United States current position-University of British Columbia Vancouver V6T 1Z4Canada

As human populations become concentrated in larger,more intensely urbanized areas connected through glob-alization,the relationships of cities to their surrounding landscapes are open to social,ecological,and economic *** particular,the value of access to nature in the form of nearby undeveloped wildland to ur-ban populations implies a relatively novel type of synergistic city-region *** develop a robust and replicable metric-the urban-wildland juxtaposition(UWj)-that quantifies critical dimensions of the juxtapo-sition of the urbanicity of cities with the quantity of nearby unbuilt wildlands,based on the spatial proximity and relative intensities of these two contrasting system *** a distance-decay gravity model,this analysis provides documentation on the calculation of the UWj and its component metrics,urbanicity(U)and wildland(W)and then presents U,W,and UWj metrics for 36 urbanized areas representing all regions of the U.S.,pro-viding the basis for comparisons and *** explore the potential of the metric by testing correlations with“creative class”employment and public health *** UWj has implications and potential applications for demographic,economic,social,and quality-of-life trends across the *** internationally.

关键词： Wildland conservation Urban-proximate Urban-wildland juxtaposition

Pathophysiological mechanisms underlying gastrointestinal symptoms in patients with COVID-19

在线全文

学校读者我要写书评

暂无评论

World journal of Gastroenterology 2021年第19期27卷 2341-2352页

作者： Byungchang jin Rajan Singh Se Eun Ha Hannah Zogg Paul j park Seungil Ro Department of Physiology and Cell Biology University of Nevada School of MedicineRenoNV 89557United States Department of Medicine Renown HealthRenoNV 89557United States

Gastrointestinal(GI)symptoms,such as diarrhea,abdominal pain,vomiting,and anorexia,are frequently observed in patients with coronavirus disease 2019(COVID-19).However,the pathophysiological mechanisms connecting these GI symptoms to severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infections remain *** studies indicate that the entry of SARS-CoV-2 into intestinal cells leads to downregulation of angiotensin converting enzyme 2(ACE2)receptors resulting in impaired barrier *** intestinal ACE2 functions as a chaperone for the amino acid transporter B0AT1,the B0AT1/ACE2 complex within the intestinal epithelium acts as a regulator of gut microbiota composition and *** to the B0AT1/ACE2 complex lead to microbial dysbiosis through increased local and systemic immune *** studies have also suggested that altered serotonin metabolism may be the underlying cause of GI disorders involving *** findings of elevated plasma serotonin levels and high fecal calprotectin in COVID-19 patients with diarrhea indicate that the viral infection evokes a systemic inflammatory response that specifically involves the ***,the elevated proinflammatory cytokines correlate with elevated serotonin and fecal calprotectin levels further supporting the evidence of GI inflammation,a hallmark of functional GI ***,the finding that rectal swabs of COVID-19 patients remain positive for SARS-CoV-2 even after the nasopharynx clears the virus,suggests that viral replication and shedding from the GI tract may be more robust than that of the respiratory tract,further indicating fecal-oral transmission as another important route of viral *** review summarized the evidence for pathophysiological mechanisms(impaired barrier function,gut inflammation,altered serotonin metabolism and gut microbiota dysbiosis)underlying the GI symptoms in patients with COVID-19.

关键词： COVID-19 Gastrointestinal symptoms Gut microbiota dysbiosis Impaired barrier function Serotonin Angiotensin converting enzyme 2 receptor