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construction of conservative Numerical Fluxes for the Entropy Split Method

communications on Applied Mathematics and computation 2023年第2期5卷 653-678页

作者： Björn Sjögreen h.c.yee Multid Analyses AB GothenburgSweden NASA Ames Research center Moffett FieldCA 94035USA

The entropy split method is based on the physical entropies of the thermally perfect gas Euler equations.The Euler flux derivatives are approximated as a sum of a conservative portion and a non-conservative portion in conjunction with summation-by-parts(SBP)difference boundary closure of(Gerritsen and Olsson in J comput Phys 129:245-262,1996;Olsson and Oliger in RIAcS Tech Rep 94.01,1994;yee et al.in J comp Phys 162:33-81,2000).Sj?green and yee(J Sci comput)recently proved that the entropy split method is entropy conservative and stable.Stand-ard high-order spatial central differencing as well as high order central spatial dispersion relation preserving(DRP)spatial differencing is part of the entropy stable split methodol-ogy framework.The current work is our first attempt to derive a high order conservative numerical flux for the non-conservative portion of the entropy splitting of the Euler flux derivatives.Due to the construction,this conservative numerical flux requires higher oper-ations count and is less stable than the original semi-conservative split method.however,the Tadmor entropy conservative(Ec)method(Tadmor in Acta Numerica 12:451-512,2003)of the same order requires more operations count than the new construction.Since the entropy split method is a semi-conservative skew-symmetric splitting of the Euler flux derivative,a modified nonlinear filter approach of(yee et al.in J comput Phys 150:199-238,1999,J comp Phys 162:3381,2000;yee and Sj?green in J comput Phys 225:910934,2007,high Order Filter Methods for Wide Range of compressible flow Speeds.Proceedings of the IcOSAhOM09,June 22-26,Trondheim,Norway,2009)is proposed in conjunction with the entropy split method as the base method for problems containing shock waves.Long-time integration of 2D and 3D test cases is included to show the com-parison of these new approaches.

关键词： Finite-difference method Entropy conservation Entropy splitting Shock capturing

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Variable high Order Multiblock Overlapping Grid Methods for Mixed Steady and Unsteady Multiscale Viscous Flows

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communications in computational Physics 2009年第2期5卷 730-744页

作者： Bjorn Sjogreen h.c.yee center for Applied Scientific computing Lawrence Livermore National LaboratoryLivermoreCA 94551USA NASA Ames Research center Moffett FieldCA 94035USA

Flows containing steady or nearly steady strong shocks on parts of the flow field,and unsteady turbulence with shocklets on other parts of the flow field are difficult to capture accurately and efficiently employing the same numerical scheme,even under the multiblock grid or adaptive grid refinement framework.While sixthorder or higher-order shock-capturing methods are appropriate for unsteady turbulence with shocklets,third-order or lower shock-capturing methods are more effective for strong steady or nearly steady shocks in terms of convergence.In order to minimize the short comings of low order and high order shock-capturing schemes for the subject flows,a multiblock overlapping grid with different types of spatial schemes and orders of accuracy on different blocks is proposed.The recently developed single block high order filter scheme in generalized geometries for Navier Stokes and magnetohydrodynamics systems is extended to multiblock overlapping grid geometries.The first stage in validating the high order overlapping approach with several test cases is included.

关键词： Multiblock grid overset grids high order numerical methods blunt body hypersonic flows mixed steady and unsteady flows

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Variable high-Order Multiblock Overlapping Grid Methods for Mixed Steady and Unsteady Multiscale Viscous Flows,Part II:hypersonic Nonequilibrium Flows

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communications in computational Physics 2013年第2期13卷 583-602页

作者： Andrea Lani Björn Sjögreen h.c.yee William D.henshaw NASA Ames/Stanford centre for Turbulence Research Palo AltoCAUSA Lawrence Livermore National Laboratory LivermoreCAUSA MS 258-5 NASA Ames Research CenterMoffett FieldCAUSA

The variable high-order multiblock overlapping(overset)grids method of Sj¨ogreen&yee[cicP,Vol.5,2009]for a perfect gas has been extended to nonequilibrium flows.This work makes use of the recently developed high-order well-balanced shock-capturing schemes and their filter counterparts[Wang et al.,J.comput.Phys.,2009,2010]that exactly preserve certain non-trivial steady state solutions of the chemical nonequilibrium governing equations.Multiscale turbulence with strong shocks and flows containing both steady and unsteady components is best treated by mixing of numerical methods and switching on the appropriate scheme in the appropriate subdomains of the flow fields,even under the multiblock grid or adaptive grid refinement framework.While low dissipative sixth-or higher-order shock-capturing filter methods are appropriate for unsteady turbulence with shocklets,second-and thirdorder shock-capturing methods are more effective for strong steady or nearly steady shocks in terms of convergence.It is anticipated that our variable high-order overset grid framework capability with its highly modular design will allow for an optimum synthesis of these new algorithms in such a way that the most appropriate spatial discretizations can be tailored for each particular region of the flow.In this paper some of the latest developments in single block high-order filter schemes for chemical nonequilibrium flows are applied to overset grid geometries.The numerical approach is validated on a number of test cases characterized by hypersonic conditions with strong shocks,including the reentry flow surrounding a 3D Apollo-like NASA crew Exploration Vehicle that might contain mixed steady and unsteady components,depending on the flow conditions.

关键词： Unstructured mesh hypersonic flows thermo-chemical nonequilibrium residual distribution schemes double cone

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含激波的湍流流动高精度大涡数值模拟方法（英文）

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空气动力学学报 2016年第2期34卷 190-203页

作者： D.V.Kotov h.c.yee A.Wray A.hadjadj B.Sjogreen center for Turbulence Research Stanford UniversityStanfordCA 94305USA NASA Ames Research center Moffett FieldCA94035USA cORIA UMR 6614&-INSA de Rouen 76800 St-Etienne du RouvrayFrance Lawrence Livermore National Laboratory Box 808L-422LivermoreCA 94551USA

针对采用亚格子模型进行含激波的湍流流动模拟时会面临激波附近的精度损失问题,考虑从通过亚格子模型以及数值模拟方法两方面的改进来实现湍流流动大涡模拟的精度提高。大涡模拟采用了yee及Sjgreen(2009)提出的高阶低耗散方法。该方... 详细信息

针对采用亚格子模型进行含激波的湍流流动模拟时会面临激波附近的精度损失问题,考虑从通过亚格子模型以及数值模拟方法两方面的改进来实现湍流流动大涡模拟的精度提高。大涡模拟采用了yee及Sjgreen(2009)提出的高阶低耗散方法。该方法采用自适应的流场探测器以控制计算中所需区域的数值耗散,并考虑对动力学模型采用在激波位置使用Sagaut和Germano(2005)提出的单边亚格子过滤器和(或)直接禁用亚格子项等方法加以改进。对于标准的马赫数1.5和3条件下的激波-湍流干扰问题,上述新方法相较于全区域采用亚格子模型的方法均表现出了相似的精度提升。同时实现的数值精度改进方案采用了harten的亚单元分辨过程来定位和锐化激波,并在精确激波位置附近的网格点处采用了单边测试滤波。

关键词：高阶低耗散格式 Germao模型大涡模拟滤波直接数值模拟方法亚单元分辨格式激波湍流干扰

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Engineering behaviour of in situ cored deep cement mixed marine deposits subjected to undrained and drained shearing

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1749-1760页

作者： Wei Li chung yee Kwok Faculty of Engineering China University of GeosciencesWuhan430074China Department of civil Engineering The University of Hong Kong999000Hong Kong SARChina

The deep cement mixing(DcM)is used to improve the capacity and reduce the settlement of the soft ground by forming cemented clay columns.The investigation on the mechanical behaviour of the DcM samples is limited to either laboratory-prepared samples or in-situ samples under unconfined compression.In this study,a series of drained and undrained triaxial shearing tests was performed on the in-situ cored DcM samples with high cement content to assess their mechanical behaviours.It is found that the drainage condition affects significantly the stiffness,peak and residual strengths of the DcM samples,which is mainly due to the state of excess pore water pressure at different strain levels,i.***.being positive before the peak deviatoric stress and negative after the peak deviatoric stress,in the undrained tests.The slope of the failure envelope changes obviously with the confining pressures,being steeper at lower stress levels and flatter at higher stress levels.The strength parameters,effective cohesion and friction angle obtained from lower stress levels(c′0 andφ′0)are 400 kPa and 58°,respectively,which are deemed to be true for design in most DcM applications where the in-situ stress levels are normally at lower values of 50-200 kPa.Additionally,the computed tomography(cT)scanning system was adopted to visualize the internal structures of DcM samples.It is found that the clay pockets existing inside the DcM samples due to uneven mixing affect markedly their stress-strain behaviour,which is one of the main reasons for the high variability of the DcM samples.

关键词： Deep cement mixing(DcM) In-situ cored sample Triaxial shearing Drainage condition confining pressure computed tomography(cT)

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hepatitis B virus genotypes in precision medicine of hepatitis Brelated hepatocellular carcinoma:Where we are now

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World Journal of Gastrointestinal Oncology 2024年第4期16卷 1097-1103页

作者： caecilia h c Sukowati Sri Jayanti Turyadi Turyadi David h Muljono claudio Tiribelli Eijkman Research center for Molecular Biology Research Organization for HealthNational Research and Innovation Agency of IndonesiaJakarta 10340Indonesia Liver cancer Unit Fondazione Italiana Fegato ONLUSTrieste 34149Italy Faculty of Medicine Hasanuddin UniversityMakassar 90245South SulawesiIndonesia Faculty of Medicine and health University of SydneySydney 2050Australia

hepatitis B virus(hBV)infection is a major player in chronic hepatitis B that may lead to the development of hepatocellular carcinoma(hcc).hBV genetics are diverse where it is classified into at least 9 genotypes(A to I)and 1 putative genotype(J),each with specific geographical distribution and possible different clinical outcomes in the patient.This diversity may be associated with the precision medicine for hBV-related hcc and the success of therapeutical approaches against hcc,related to different pathogenicity of the virus and host response.This Editorial discusses recent updates on whether the classification of hBV genetic diversity is still valid in terms of viral oncogenicity to the hcc and its precision medicine,in addition to the recent advances in cellular and molecular biology technologies.

关键词： hepatitis B virus hepatocellular carcinoma Genotypes Pathogenesis Precision medicine

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Effect of radiative loss mechanisms on FIR thermometric parameters of Nd3+-doped lithium tellurite glasses

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Journal of Rare Earths 2024年第7期42卷 1250-1257页

作者： c.Y.Morassuti A.P.L Silva L.A.O.Nunes S.M.Lima L.h.c.Andrade Optical and Photothermal Spectroscopy Group (GEOF) Center for Studies in Natural Resources (CERNA)State University of Mato Grosso do Sul(UEMS) Renato Archer Information Technology center Institute of Physics of Sao carlos University of S?o Paulo

Nd3+-doped tellurite glasses are promising materials for thermometers based on the fluorescence intensity ratio（FIR） technique.Nevertheless,at high Nd3+concentrations,energy transfer（ET） processes such as optical reabsorption and cross-relaxation can affect the Nd3+emission,which has been little explored in the literature.Therefore,the present work investigated the use of Nd3+-doped tellurite glass(samples doped with Nd3+at 0.2 mol%,0.5 mol%,2.0 mol%,and 4.0 mol%) in fluorescence thermometers,in the temperature range from 299 to 371 K.The results indicate a strong dependence of the FIR parameters on the Nd3+concentration,due to changes in the emission band profiles caused by optical reabsorption of the Nd3+emissions and cross-relaxation processes.A decrease of the relative sensitivity of the ratio4F5/2→4I9/2/4F3/2→4I9/2is observed for samples doped with higher amounts of Nd3+.The maximum relative sensitivity at 299 K is 3.00%/K,which is the highest value among the reported Nd3+ions.

关键词： Fluorescence intensity ratio Judd-Ofelt Nd3+-doped tellurite glass Optical thermometry Rare earths

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Net effect of air pollution controls on health risk in the Beijing-Tianjin-hebei region during the 2022 winter Olympics and Paralympics

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Journal of Environmental Sciences 2024年第1期135卷 560-569页

作者： changqing Lin Peter K.K.Louie Alexis K.h.Lau Jimmy c.h.Fung Zibing Yuan Minghui Tao Xuguo Zhang Md.Shakhaoat hossain chengcai Li Xiang Qian Lao Division of Environment and Sustainability The Hong Kong University of Science and TechnologyHong KongChina Environmental Protection Department Hong Kong Government SARHong KongChina Department of civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina Guangdong-hongkong-Macao Joint Laboratory of collaborative Innovation for Environmental Quality The Hong Kong University of Science and TechnologyHong KongChina Department of Mathematics The Hong Kong University of Science and TechnologyHong KongChina School of Environment and Energy South China University of TechnologyGuangzhou 510006China hubei Key Laboratory of critical Zone Evolution School of Geography and Information EngineeringChina University of GeosciencesWuhan 430074China Department of Public health and Informatics Jahangirnagar UniversityDhaka 1342Bangladesh Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China Jockey club School of Public health and Primary care The Chinese University of Hong KongHong KongChina

Due to the non-linearity in ozone(O_(3))formation,reducing the emission of nitrogen oxides(NO_(x))may increase O_(3) concentration.Given the counteractive O_(3) response to NO_(x) reduction,overall impact of air pollution controls can be ambiguous when the assessments focus on the changes in pollutant concentrations.In this study,a risk-based method was used to gauge the net effect of air pollution controls on mortality risk in the Beijing–Tianjin–hebei(BTh)region during the 2022 Winter Olympics and Paralympics(WOP).This mega-event presents a unique opportunity to investigate the efficacy of deep cuts in pollutant emissions.Results show that O_(3) concentrations greatly increased as nitrogen dioxide(NO_(2))concentrations decreased in the BTh.Due to the active photochemical formations,O_(3) became the dominant pollutant that affected human health during the WOP.Despite the substantial O_(3) increases,the health benefits of NO_(2) reductions overwhelmed the adverse health effects of O_(3) increases in most regions of the BTh(at 81 out of 112 stations).After considering the impacts of particulate matter,the integrated health risk of air pollution mixtures declined almost everywhere in the BTh.Our results underscore the great necessity of changing the assessment paradigm of pollution control from using concentration-based methods to using risk-based methods.Together with the carbon neutrality policy,stringent control of NO_(x)emission from combustion sources is a promising way to achieve synergistic control solutions for air pollution and climate change.

关键词： Ozone Nitrogen dioxide health risk carbon neutrality Mega-events

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Superior antibody and membrane protein‑specific T‑cell responses to coronaVac by intradermal versus intramuscular routes in adolescents

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World Journal of Pediatrics 2024年第4期20卷 353-370页

作者： Jaime S.Rosa Duque Samuel M.S.cheng carolyn A.cohen Daniel Leung Xiwei Wang Xiaofeng Mu Yuet chung Tsun Ming Lau Manni Wang Wenyue Zhang Yanmei Zhang howard h.W.Wong Leo c.h.Tsang Sara chaothai Tsz chun Kwan John K.c.Li Karl c.K.chan Leo L.h.Luk Jenson c.h.ho Wing Yan Li Amos M.T.Lee Jennifer h.Y.Lam Sau Man chan Wilfred h.S.Wong Issan Y.S.Tam Masashi Mori Sophie A.Valkenburg Malik Peiris Wenwei Tu Yu Lung Lau Department of Paediatrics and Adolescent Medicine The University of Hong KongHong KongChina School of Public health The University of Hong KongHong KongChina hKU‑Pasteur Research Pole School of Public HealthThe University of Hong KongHong KongChina Research Institute for Bioresources and Biotechnology Ishikawa Prefectural UniversityNonoichiJapan Department of Microbiology and Immunology Peter Doherty Institute for Infectionand ImmunityUniversity of MelbourneMelbourneVICAustralia center for Immunology and Infection c2i Hong KongChina

Background Optimising the immunogenicity of cOVID-19 vaccines to improve their protection against disease is necessary.Fractional dosing by intradermal(ID)administration has been shown to be equally immunogenic as intramuscular(IM)administration for several vaccines,but the immunogenicity of ID inactivated whole severe acute respiratory syndrome coronavirus 2(SARS-coV-2)at the full dose is unknown.This study(NcT04800133)investigated the superiority of antibody and T-cell responses of full-dose coronaVac by ID over IM administration in adolescents.Methods Participants aged 11–17 years received two doses of IM or ID vaccine,followed by the 3rd dose 13–42 days later.humoral and cellular immunogenicity outcomes were measured post-dose 2(IM-cc versus ID-cc)and post-dose 3(IMccc versus ID-ccc).Doses 2 and 3 were administered to 173 and 104 adolescents,respectively.Results Spike protein(S)immunoglobulin G(IgG),S-receptor-binding domain(RBD)IgG,S IgG Fcγreceptor IIIa(FcγRIIIa)-binding,SNM[sum of individual(S),nucleocapsid protein(N),and membrane protein(M)peptide pool]-specific interleukin-2(IL-2)+cD4+,SNM-specific IL-2+cD8+,S-specific IL-2+cD8+,N-specific IL-2+cD4+,N-specific IL-2+cD8+and M-specific IL-2+cD4+responses fulfilled the superior and non-inferior criteria for ID-cc compared to IM-cc,whereas IgG avidity was inferior.For ID-ccc,S-RBD IgG,surrogate virus neutralisation test,90%plaque reduction neutralisation titre(PRNT90),PRNT50,S IgG avidity,S IgG FcγRIIIa-binding,M-specific IL-2+cD4+,interferon-γ+cD8+and IL-2+cD8+responses were superior and non-inferior to IM-ccc.The estimated vaccine efficacies were 49%,52%,66%and 79%for IM-cc,ID-cc,IM-ccc and ID-ccc,respectively.The ID groups reported more local,mild adverse reactions.conclusion This is the first study to demonstrate superior antibody and M-specific T-cell responses by ID inactivated SARScoV-2 vaccination and serves as the basis for future research to improve the immunogenicity of inactivated vaccines.

关键词： coronaVac coronavirus disease 2019 Immunity Intradermal Vaccine

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Groundwater vulnerability assessment using a GIS-based DRASTIc method in the Erbil Dumpsite area (Kani Qirzhala), central Erbil Basin, North Iraq

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Journal of Groundwater Science and Engineering 2024年第1期12卷 16-33页

作者： Masoud h hamed Rebwar N Dara Marios c Kirlas Department of Earth Sciences and Petroleum College of ScienceSalahaddin University-ErbilErbilIraq Department of Petroleum Engineering College of EngineeringKnowledge UniversityErbilIraq Department of Agriculture Faculty of AgricultureForestry and Natural EnvironmentAristotle University of Thessaloniki

Groundwater vulnerability assessment is a crucial step in the efficient management of groundwater resources,especially in areas with intensive anthropogenic activities and groundwater pollution.In the present study,the DRASTIc method was applied using Geographic Information System(GIS)to delineate groundwater vulnerability zones in the Erbil Dumpsite area,central Erbil Basin,North Iraq.Results showed that the area was classified into four vulnerability classes:Very low(16.97%),low(27.67%),moderate(36.55%)and high(18.81%).The southern,south-eastern and northern parts of the study area exhibited the highest vulnerability potential,while the central-northern,northern and north-western regions displayed the lowest vulnerability potential.Moreover,results of the single-parameter sensitivity analysis indicated that amongst the seven DRASTIc parameters,the unsaturated zone and the aquifer media were the most influencing parameters.In conclustion,the correlation of 25 nitrate concentration values with the final vulnerability map,assessed using the Pearson correlation coefficient,yielded a satisfactory result of R=0.72.

关键词： DRASTIc Erbil Iraq Groundwater vulnerability assessment Nitrate Pollution Sensitivity analysis

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