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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 *** 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 *** 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 ***-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 *** 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 *** to the construction,this conservative numerical flux requires higher oper-ations count and is less stable than the original semi-conservative split ***,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 *** the entropy split method is a semi-conservative skew-symmetric splitting of the Euler flux derivative,a modified nonlinear filter approach of(yee et *** 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 *** 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 ***-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 *** 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 *** 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 *** recently developed single block high order filter scheme in generalized geometries for Navier Stokes and magnetohydrodynamics systems is extended to multiblock overlapping grid *** 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 *** work makes use of the recently developed high-order well-balanced shock-capturing schemes and their filter counterparts[Wang et al.,***.,2009,2010]that exactly preserve certain non-trivial steady state solutions of the chemical nonequilibrium governing *** 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 *** 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 *** 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 *** this paper some of the latest developments in single block high-order filter schemes for chemical nonequilibrium flows are applied to overset grid *** 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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Design-space adaptation method for multiobjective and multidisciplinary optimization

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chinese Journal of Aeronautics 2024年第8期37卷 166-189页

作者： Jongho JUNG Kwanjung yee Shinkyu JEONG Department of Aerospace Engineering Seoul National UniversitySeoul 08826Republic of Korea Department of Mechanical Engineering Kyunghee UniversityYoungin 17104Republic of Korea

This paper developed a new method that adaptively adjusts a design space by considering the actual solution distribution of a problem to overcome the conventional design-space adaptation method that assumes the solutions distribution to be a normal distribution because the distributions of solutions are rarely normal distributions for real-world *** developed method was applied to nineteen multiobjective test functions that are widely used to evaluate the characteristics and performance of optimization *** results showed that this method adapted the design space to an appropriate design space where the solution existence probability was *** optimization performance achieved using the developed method was higher than that of the conventional ***,the developed method was applied to the conceptual design of an unmanned spacecraft to confirm its validity in real-world design and multidisciplinaryoptimization *** results showed that the Pareto solutions of the developed method were superior to those of conventional ***,the optimization efficiency with the developed method was improved by more than 1.4 times over that of the conventional *** this regard,the developed method has the potential to be applied to complicated real-world optimization problems to achieve better performance and efficiency.

关键词： Multiobjective optimization Multiobjective genetic algorithm Design-space adaptation Multidisciplinary optimization hypersonic vehicle

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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 *** investigation on the mechanical behaviour of the DcM samples is limited to either laboratory-prepared samples or in-situ samples under unconfined *** 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 *** 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,*** positive before the peak deviatoric stress and negative after the peak deviatoric stress,in the undrained *** slope of the failure envelope changes obviously with the confining pressures,being steeper at lower stress levels and flatter at higher stress *** 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 ***,the computed tomography(cT)scanning system was adopted to visualize the internal structures of DcM *** 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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Efficient guiding and focusing of intense laser pulse using periodic thin slits

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Matter and Radiation at Extremes 2024年第4期9卷 29-39页

作者： L.Xu T.W.huang K.Jiang c.N.Wu h.Peng P.c.hen R.Li h.B.Zhuo c.T.Zhou Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology Center for Intense Laser ApplicationTechnologyand College of Engineering PhysicsShenzhen Technology UniversityShenzhen 518118People’s Republic of China

Slits have been widely used in laser-plasma interactions as plasma optical components for generating high-harmonic light and controlling laser-driven particle ***,we propose and demonstrate that periodic thin slits can be regarded as a new breed of optical elements for efficient focusing and guiding of intense laser *** fundamental physics of intense laser interaction with thin slits is studied,and it is revealed that relativistic effects can lead to enhanced laser focusing far beyond the pure diffractive focusing *** addition,the interaction of an intense laser pulse with periodic thin slits makes it feasible to achieve multifold enhancement in both laser intensity and energy transfer efficiency compared with conventional *** results provide a novel method for manipulating ultra-intense laser pulses and should be of interest for many laser-based applications.

关键词： laser pulse intense

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An improved pulse coupled neural networks model for semantic IoT

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Digital communications and Networks 2024年第3期10卷 557-567页

作者： Rong Ma Zhen Zhang Yide Ma Xiping hu Edith c.h.Ngai Victor c.M.Leung School of Information Science and Engineering Lanzhou UniversityLanzhou 730000China School of Medical Technology Beijing Institute of TechnologyBeijing100081China Department of Electrical and Electronic Engineer The University of Hong KongHong Kong 999077China college of computer Science and Software Engineering Shenzhen UniversityShenzhen 518060China Department of Electrical and computer Engineering the University of British ColumbiaVancouverBC V6T 1Z4Canada

In recent years,the Internet of Things(IoT)has gradually developed applications such as collecting sensory data and building intelligent services,which has led to an explosion in mobile data ***,with the rapid development of artificial intelligence,semantic communication has attracted great attention as a new communication ***,for IoT devices,however,processing image information efficiently in real time is an essential task for the rapid transmission of semantic *** the increase of model parameters in deep learning methods,the model inference time in sensor devices continues to *** contrast,the Pulse coupled Neural Network(PcNN)has fewer parameters,making it more suitable for processing real-time scene tasks such as image segmentation,which lays the foundation for real-time,effective,and accurate image ***,the parameters of PcNN are determined by trial and error,which limits its *** overcome this limitation,an Improved Pulse coupled Neural Networks(IPcNN)model is proposed in this *** IPcNN constructs the connection between the static properties of the input image and the dynamic properties of the neurons,and all its parameters are set adaptively,which avoids the inconvenience of manual setting in traditional methods and improves the adaptability of parameters to different types of *** segmentation results demonstrate the validity and efficiency of the proposed self-adaptive parameter setting method of IPcNN on the gray images and natural images from the Matlab and Berkeley Segmentation *** IPcNN method achieves a better segmentation result without training,providing a new solution for the real-time transmission of image semantic information.

关键词： Internet of things(IoT) Semantic information Real-time application Improved pulse coupled neural network Image segmentation

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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 *** 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 *** 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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Exploring one material for dual applications:A red-emitting Mg2GeO4:Eu3+ nanophosphor for future generation energy efficient WLEDs and dosimetric applications

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Journal of Rare Earths 2024年第10期42卷 1835-1845页

作者： Akshay Arjun G.P.Darshan S.c.Sharma h.Nagabhushana D.V.Sunitha h.B.Premkumar Department of Physics Faculty of Mathematical and Physical SciencesM.S.Ramaiah University of Applied Sciences Jain University c.N.R.Rao centre for Advanced Materials Tumkur University School of Applied Sciences (Physics) REVA University

The envisaged design and developme nt of individual mate rials to excavate a broader spectrum of desired properties and offer multiple applications are highly *** this in mind,a series of forsterite-structured Mg2GeO4:Eu3+（1 mol%-9 mol%） nanophosphors was synthesized via a solution combustion method using oxalyl dihydrazide as a *** X-ray diffraction patterns confirm the orthorhombic crystal system with a Puma space *** results clearly show irregularly shaped cluster-like structures with aggregation of the *** diffuse reflectance spectra,the optical energy band gap of the Mg2GeO4:Eu3+（1 mol%-9 mol%） nanophosphors was estimated and obtained to be～4.12-4.32 *** photoluminescence emission spectra exhibit intense peaks at ～579,589,610,661,and 707 nm,which are due to characteristic5D0→7F0,5D0→7F1,5Do→7F2,5D0→7F3and5D0→7F4transitions of Eu3+ions,*** commission International de L'Eclairage color coordinates are gradually tuned from pale red（0.5980,0.4012） to a pure red（0.6385,0.3611） *** glow peaks showcase excellent super-linear response at low doses of γ-irradiations,indicating that the prepared phosphor can be used in thermoluminescent personal dosimetry which is a biological tissue *** aforementioned results demonstrate that the prepared Mg2GeO4:Eu3+（1 mol%-9 mol%） nanophosphors are considered an excellent candidate for dual applications,i.e.,red component in future generation white-light-emitting diodes（WLEDs） and personal dosimetric applications.

关键词： Dosimetry Nanophosphors Photoluminescence Photometric properties Rare earths Thermoluminescence

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