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A Sub-element Adaptive Shock Capturing Approach for Discontinuous Galerkin Methods

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Communications on Applied Mathematics and Computation 2023年第2期5卷 679-721页

作者： Johannes Markert Gregor gassner Stefanie Walch Department for Mathematics and Computer Science University of CologneWeyertal 86-9050931 CologneGermany Department for Mathematics and Computer Science Center for Data and Simulation ScienceUniversity of CologneWeyertal 86-9050931 CologneGermany I.Physikalisches Institut Center for Data and Simulation ScienceUniversity of CologneZülpicher Str.7750937 CologneGermany

In this paper,a new strategy for a sub-element-based shock capturing for discontinuous Galerkin(DG)approximations is *** idea is to interpret a DG element as a col-lection of data and construct a hierarchy of low-to-high-order discretizations on this set of data,including a first-order finite volume scheme up to the full-order DG *** dif-ferent DG discretizations are then blended according to sub-element troubled cell indicators,resulting in a final discretization that adaptively blends from low to high order within a single DG *** goal is to retain as much high-order accuracy as possible,even in simula-tions with very strong shocks,as,e.g.,presented in the Sedov *** framework retains the locality of the standard DG scheme and is hence well suited for a combination with adaptive mesh refinement and parallel *** numerical tests demonstrate the sub-element adaptive behavior of the new shock capturing approach and its high accuracy.

关键词： high-order methods Discontinuous Galerkin spectral element method Finite volume method Shock capturing Astrophysics Stellar physics

Preventing Pressure Oscillations Does Not Fix local linear Stability Issues of Entropy-Based Split-Form high-Order Schemes

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Communications on Applied Mathematics and Computation 2022年第3期4卷 880-903页

作者： hendrik Ranocha Gregor J.gassner Applied Mathematics Münster University of Münster48149 MünsterGermany Computer Electrical and Mathematical Science and Engineering(CEMSE)Division King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia Department of Mathematics and Computer Science Center for Data and Simulation ScienceUniversity of CologneCologneGermany

Recently,it was discovered that the entropy-conserving/dissipative high-order split-form discontinuous Galerkin discretizations have robustness issues when trying to solve the sim-ple density wave propagation example for the compressible Euler *** issue is related to missing local linear stability,i.e.,the stability of the discretization towards per-turbations added to a stable base *** is strongly related to an anti-diffusion mech-anism,that is inherent in entropy-conserving two-point fluxes,which are a key ingredi-ent for the high-order discontinuous Galerkin *** this paper,we investigate if pressure equilibrium preservation is a remedy to these recently found local linear stability issues of entropy-conservative/dissipative high-order split-form discontinuous Galerkin methods for the compressible Euler *** equilibrium preservation describes the property of a discretization to keep pressure and velocity constant for pure density wave *** present the full theoretical derivation,analysis,and show corresponding numerical results to underline our *** addition,we characterize numerical fluxes for the Euler equations that are entropy-conservative,kinetic-energy-preserving,pressure-equilibrium-preserving,and have a density flux that does not depend on the *** source code to reproduce all numerical experiments presented in this article is available online(https://***/10.5281/zenodo.4054366).

关键词： Entropy conservation Kinetic energy preservation Pressure equilibrium preservation Compressible Euler equations local linear stability Summation-by-parts

ORGANIC CARBON STOCKS IN A SIlTY TEXTURED SOIl FOllOWING REINTEGRATION OF A 20 YEARS OlD MISCANThUS×GIGANTEUS SITE INTO A CROP ROTATION

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Frontiers of Agricultural Science and Engineering 2023年第2期10卷 183-197页

作者： lisa ESSICh Reiner RUSER Jens hARTUNG Anne hANEMANN Meike gassner liam OBERDORFER Jörn BREUER Jürgen RECKNAGEl h.lmut NUßBAUMER Torsten MÜllER Institute of Crop Science Department Fertilization and Soil Matter DynamicsUniversity of Hohenheim70599 StuttgartGermany Institute of Crop Science Biostatistics UnitUniversity of Hohenheim70599 StuttgartGermany Center for Agricultural Technology Augustenberg(lTZ) 76227 KarlsruheGermany

Miscanthus×giganteus may play an important role in replacing fossil energy resources by bio-based *** further advantage of miscanthus production is the generally high soil organic carbon(C_(org))enrichment in *** to declining yields,miscanthus stocks are commonly reintegrated into crop rotation after approximately 20 *** there is only few information,whether these high amounts of(C_(org))can be conserved wh.le intensifying soil tillage and crop management after ***,we monitored(C_(org))stocks in a control with more than 20 years of continuous miscanthus and in a treatment with reintegration of a 20-years old miscanthus stock into an organic crop *** onδ^(13)C soil values,we calculated an annual(C_(org))enrichment of 0.98 Mg·ha^(-1)·yr^(-1)C under *** than 95%of the miscanthus-C was determined in the upper 0.25 m of *** miscanthus cultivation did not affect yields during the first five extension years and(C_(org))stocks increased *** reintegration,(C_(org))stocks remained constant during five years,which was mainly attributed to the humification and/or stabilization of high amounts of destroyed roots and rhizomes.A significant decrease in(C_(org))(-5.7 Mg·ha^(-1)C)compared to the continuing miscanthus cultivation was at first measured six years after reintegration into crop rotation,underlining the need of long-term *** data also show,that miscanthus production cycles can be extended in our region,and that sowing of the alfalfa grass mixture after rhizome/root destruction was efficient in preserving(C_(org))stocks for at least first five years after reintegration.

关键词： biobased energy crops C balance humus accumulation

Ground motion improvements in SPEAR3

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Chinese Physics C 2016年第9期40卷 164-170页

作者： James A.Safranek Yiton T.Yan Domenico Dell’Orco Georg gassner Nikita Sunilkumar SlAC National Accelerator laboratory Stanford University Northwestern University Kellogg School of Management

SPEAR3 is a third-generation synchrotron light source storage ring, about 234 meters in *** meet the beam stability requirement, our goal is to ultimately achieve an orbit variation（relative to the photon beam lines） of less than 10% of the beam size, which is about 1 micron in the vertical plane. hydrostatic leveling system（hlS） measurements show that the height of the SPEAR3 tunnel floor can vary by tens of microns daily without thermal insulation improvements. We present an analysis of the hlS data that shows that adding thermal insulation to the concrete walls of the storage ring tunnel dramatically decreased diurnal tunnel floor motion.

关键词： accelerator synchrotron radiation optics heat ground motion

Simulation of Fuel Ethanol Production from lignocellulosic Biomass

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过程工程学报 2009年第2期9卷 333-337页

作者：张素平 Franois Maréch.l Martin gassner 任铮伟颜涌捷 Daniel Favrat Center for Biomass Energy Technology East China University of Science and Technology laboratory for Industrial Energy Systems Ecole Polytechnique Fédérale de Lausanne

Models for hydrolysis,fermentation and concentration process,production and utilization of biogas as well as lignin gasification are developed to calculate the heat demand of ethanol production process and the amounts of heat and power generated from residues and wastewater of the *** the energy analysis,all relevant information about the process streams,physical properties,and mass and energy balances are *** integration is investigated for establishing a network of facilities for heat and power generation from wastewater and residues treatment aiming at the increase of energy *** the lignin to an IGCC process,the electric efficiency is increased by 4.4% compared with combustion,which.leads to an overall energy efficiency of 53.8%.A detailed sensitivity analysis on energy efficiency is also carried out.

关键词：生物能利用开发水解

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Flex 3宝典

作者： (美)David gassner

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永磁同步电机两相斩波式电流滞环控制

电工电能新技术 2014年第2期33卷 35-38,75页

作者：沈建新陆媛 Andreas gassner 浙江大学电气工程学院浙江杭州310027

电流滞环控制是永磁同步电机(PMSM)常见的控制方法。本文在传统滞环控制的基础上,提出以两相斩波替代三相斩波的改进控制方案。文中介绍了两相斩波的设计思路,阐述了其控制流程,并分析了改进方案对降低开关损耗、提高系统效率所能起到... 详细信息

电流滞环控制是永磁同步电机(PMSM)常见的控制方法。本文在传统滞环控制的基础上,提出以两相斩波替代三相斩波的改进控制方案。文中介绍了两相斩波的设计思路,阐述了其控制流程,并分析了改进方案对降低开关损耗、提高系统效率所能起到的作用。实验结果验证了改进方案的可行性与有效性。

关键词：电流滞环控制两相斩波开关损耗永磁同步电机

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SlAC Status Report

SLAC Status Report

3G/2.5G/2G无线基站的传输回程融合

第11届国际加速器校直会议

作者： Georg gassner Catherine le Cocq Robert Ruland

＜正＞～～

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电子设计应用 2006年第3期 107-108页

作者： Martin gassner 杰尔系统公司

从运营商的角度来看,由于UMTS网络的单位爱尔兰(Erl)成本低于GSM网络,因此,数据业务能够创造更多的附加值.2.5G提供的数据业务可用作3G网络中更高级、速度更快的数据业务的过渡.袖珍互联网(internet in thepocket)、移动宽带以及三重业... 详细信息

从运营商的角度来看,由于UMTS网络的单位爱尔兰(Erl)成本低于GSM网络,因此,数据业务能够创造更多的附加值.2.5G提供的数据业务可用作3G网络中更高级、速度更快的数据业务的过渡.袖珍互联网(internet in thepocket)、移动宽带以及三重业务等描述了向移动终端提供宽带数据业务的趋势.这些业务足以使用户从2G/2.5G转向3G网络,但是它们的普及取决于应用的简便性以及合理的性价比.

关键词： 3G网络无线基站 2G 宽带数据业务回程传输 UMTS网络 GSM网络移动终端