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Physics perspectives of heavy-ion collisions at very high energy

Science China(Physics,Mechanics & Astronomy) 2016年第2期59卷 1-27页

作者： Ning-bo Chang ShanShan Cao Bao-yi Chen Shi-yong Chen Zhen-yu Chen Heng-Tong Ding Min He Zhi-quan Liu Long-gang Pang Guang-you Qin Ralf Rapp bjorn schenke Chun Shen HuiChao Song Hao-jie Xu Qun Wang Xin-Nian Wang Ben-wei Zhang Han-zhong Zhang XiangRong Zhu Peng-fei Zhuang Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics Central China Normal University Wuhan 430079 China Nuclear Science Division MS70R0319 Lawrence Berkeley National Laboratory Berkeley 94720 USA Physics Department Tsinghua University Beijing 100084 China Department of Applied Physics Nanjing University of Science and Technology Nanjing 210094 China Cyclotron Institute and Department of Physics and Astronomy Texas A&M University College Station TX 77843 USA Physics Department Brookhaven National Laboratory Upton New York 11973 USA Department of Physics McGill University Montreal Quebec H3A 2T8 Canada Department of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China Department of Modern Physics University of Science and Technology of China Hefei 230026 China

Heavy-ion collisions at very high colliding energies are expected to produce a quark-gluon plasma(QGP) at the highest temperature obtainable in a laboratory setting. Experimental studies of these reactions can provide an unprecedented range of information on properties of the QGP at high temperatures. We report theoretical investigations of the physics perspectives of heavy-ion collisions at a future high-energy collider. These include initial parton production, collective expansion of the dense medium, jet quenching,heavy-quark transport, dissociation and regeneration of quarkonia, photon and dilepton production. We illustrate the potential of future experimental studies of the initial particle production and formation of QGP at the highest temperature to provide constraints on properties of strongly interaction matter.

关键词： quark-gluon plasma heavy-ion collisions QCD phase transition properties of QGP

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Adaptive State-Dependent Diffusion for Derivative-Free Optimization

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1241-1269页

作者： bjorn Engquist Kui Ren Yunan Yang Department of Mathematics and the Oden Institute The University of TexasAustinTX 78712USA Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY10027USA Department of Mathematics Cornell UniversityIthacaNY 14853USA

This paper develops and analyzes a stochastic derivative-free optimization strategy.A key feature is the state-dependent adaptive *** prove global convergence in probability with algebraic rate and give the quantitative results in numerical examples.A striking fact is that convergence is achieved without explicit information of the gradient and even without comparing different objective function values as in established methods such as the simplex method and simulated *** can otherwise be compared to annealing with state-dependent temperature.

关键词： Derivative-free optimization Global optimization Adaptive diffusion Stationary distribution Fokker-Planck theory

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Analysis of per-and polyfluoroalkyl substances(PFAS)extraction from contaminated firefighting materials:Effects of cleaning agent,temperature,and chain-length dependencies

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Emerging Contaminants 2024年第3期10卷 268-279页

作者： Sixten Dahlbom Fanny Bjarnemark bjorn Nguyen Sarunas Petronis Tove Mallin RISE Research Institute of Sweden Division Safety and TransportFire and Safety DepartmentBox 85750115BoråsSweden RISE Research Institute of Sweden Division Materials and ProductionChemistry and Applied Mechanics DepartmentBox 85750115BoråsSweden RISE Research Institute of Sweden Division Materials and ProductionMethodologyTextiles and Medical Technology DepartmentBox 85750115BoråsSweden

This investigation delves into the extraction dynamics of 22 per-and polyfluoroalkyl substances from PFAS contaminated firefighting *** distinct test sets were executed:one contrasting a commercial product with water following an elaborate decontamination procedure,and the other assessing seven washing agents on materials from firefighting installations,with one agent examined at 22℃and 50℃.A general tendency for improved desorption at the higher temperature was ***,a discernible influence of the cleaning agent's pH on the extraction of specific PFAS species was observed,elucidating the role of chemical environment in the extraction *** rebound was studied for a period of up to 157 days,this unveiled a gradual escalation in PFAS22 levels,indicative of a protracted desorption ***,PFAS with abbreviated carbon chains(C4-C6)exhibit superior desorption efficiency compared to their elongated congeners,suggesting a chain-lengthdependent decontamination potential.A comparative scrutiny between a commercially available cleaning product,featuring multiple washing and flushing steps,and a water-only treatment regimen underscores the potential efficacy of the *** exhaustive investigation furnishes nuanced insights into PFAS extraction complexities,offering a foundation for informed decontamination strategies.

关键词： PFAS Decontamination Firefighting foam Firefighting materials Cleaning

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Impacts of CO2 and H2S on the risk of hydrate formation during pipeline transport of natural gas

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Frontiers of Chemical Science and Engineering 2019年第3期13卷 616-627页

作者： Solomon A. Aromada bjorn Kvamme Department of Physics and Technology University of Bergen5007 BergenNorway Strategic Carbon LLC Vestre Holbergsallmenningen 175011 BergenNorway

Evaluation of maximum content of water in natural gas before water condenses out at a given temperature and pressure is the initial step in hydrate risk analysis during pipeline transport of natural gas, The impacts of CO2 and ELS in natural gas on the maximum mole-fractions of water that can be tolerated during pipeline transport without the risk of hydrate nucleation has been studied using our novel thermodynamic scheme. Troll gas from the North Sea is used as a reference ease, it contains very negligible amount of CO2 and no H2S. Varying mole-fractions of CO2 and INS were introduced into the Troll gas, and the effects these inorganic impurities on the water tolerance of the system were evaluated. It is observed that CO2 does not cause any distinguishable impact on water tolerance of the system, but H2S does. Water tolerance decreases with increase in concentration of H2S. The impact of ethane on the system was also investigated. The maximum mole-fraction of water permitted in the gas to ensure prevention of hydrate formation also decreases with increase in the concentration of C2H6 like H2S. H2S has the most impact, it tolerates the least amount of water among the components studied.

关键词： hydrate hydrogen Sulphide CO2 dewpoint pipeline

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Hierarchical approach for fatigue cracking performance evaluation in asphalt pavements

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Frontiers of Structural and Civil Engineering 2017年第3期11卷 257-269页

作者： Ibrahim ONIFADE Yared DINEGDAE bjorn BIRGISSON Department of Civil and Architectural Engineering KTH Royal Institute of Technology Stockholm Sweden School of Engineering and Applied Science Aston University Aston Triangle Birmingham B4 7ET United Kingdom

In this paper, a hierarchical approach is proposed for the evaluation of fatigue cracking in asphalt concrete pavements considering three different levels of complexities in the representation of the material behaviour, design parameters characterization and the determination of the pavement response as well as damage computation. Based on the developed hierarchical approach, three damage computation levels are identified and proposed. The levels of fatigue damage analysis provides pavement engineers a variety of tools that can be used for pavement analysis depending on the availability of data, required level of prediction accuracy and computational power at their disposal. The hierarchical approach also provides a systematic approach for the understanding of the fundamental mechanisms of pavement deterioration, the elimination of the empiricism associated with pavement design today and the transition towards the use of sound principles of mechanics in pavement analysis and design.

关键词： fatigue cracking energy based crack initiation mechanistic approach pavement analysis

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Interleukin 4-induced neuroprotection and regulation of microglia activation as a therapeutic approach in the MPTP model of Parkinson's disease

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Neural Regeneration Research 2017年第9期12卷 1433-1434页

作者： bjorn Spittau Institute for Anatomy and Cell Biology Department of Molecular Embryology Faculty of Medicine University of Freiburg Institute of Anatomy University of Rostock

Parkinson＇s disease （PD） has been described as one of the most common neurodegenerative diseases affecting up to 2% of the worldwide population over 60 years of age. The hallmarks of PD are progressive loss of midbrain dopaminergic （mDA） neurons and a decrease in striatal dopamine levels, which result in typ- ical clinical motor symptoms such as akinesia, resting tremor, rigidity, and gait impairments. Although the causes for PD are only partially understood and seem to be very heterogeneous, one of the common phenomenons observed in toxin-based an- imal models of PD as well as PD patients is a microglia-driven neuroinflammatory response,

关键词： T-CELLS NEURONS BRAIN CYTOKINE

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Taking Comfort in Points:The Appeal of the Norwegian Model in Sweden

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Journal of Data and Information Science 2018年第4期3卷 85-95页

作者： bjorn Hammarfelt Swedish School of Library and In formation Science University of BorasSweden

Purpose: The "Norwegian model" has become widely used for assessment and resource allocation purposes. This paper investigates why this model has becomes so widespread and influential. Approach: A theoretical background is outlined in which the reduction of "uncertainty" is highlighted as a key feature of performance measurement systems. These theories are then drawn upon when revisiting previous studies of the Norwegian model, its use, and reactions to it, in ***: The empirical examples, which concern more formal use on the level of universities as well as responses from individual researchers, shows how particular parts—especially the "publication indicator"—are employed in Swedish academia. The discussion posits that the attractiveness of the Norwegian model largely can be explained by its ability to reduce complexity and uncertainty, even in fields where traditional bibliometric measurement is less applicable. Research limitations: The findings presented should be regarded as examples that can be used for discussion, but one should be careful to interpret these as representative for broader sentiments and ***: The sheer popularity of the Norwegian model, leading to its application in contexts for which it was not designed, can be seen as a major challenge for the ***: This paper offers a novel perspective on the Norwegian model by focusing on its general "appeal", rather than on its design, use or(mis)-use.

关键词： The Norwegian model Sweden Uncertainty Bibliometric indicators Assessment systems

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2023年Abel奖获得者Luis Angel Caffarelli访谈录

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数学译林 2024年第1期43卷 8-13页

作者： bjorn Ian Dundas Christian F.Skau 陆柱家(译) 童欣(校) 挪威卑尔根大学挪威Trondheim科技大学不详

Dundas&Skau(以下简写为“D&S”):Caffarelli教授,首先我们要祝贺您获得2023年的Abel(阿贝尔)奖,因为您“对非线性偏微分方程正则性理论,包括自由边界问题和Monge-Ampere(蒙日-安培)方程的开创性贡献”.明天挪威国王下将向您颁奖,我们... 详细信息

Dundas&Skau(以下简写为“D&S”):Caffarelli教授,首先我们要祝贺您获得2023年的Abel(阿贝尔)奖,因为您“对非线性偏微分方程正则性理论,包括自由边界问题和Monge-Ampere(蒙日-安培)方程的开创性贡献”.明天挪威国王下将向您颁奖,我们将回到您的数学,但首先了解一下您的背景可能是个好主意.1948年您出生在布宜诺斯艾利斯.您如何描述您的童年?

关键词：自由边界问题非线性偏微分方程阿贝尔开创性贡献

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Evaluation of Turbulence Models in Predicting Hypersonic and Subsonic Base Flows Using Grid Adaptation Techniques

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Chinese Journal of Aeronautics 2012年第3期25卷 325-334页

作者： YOU Yancheng BUANGA bjorn HANNEMANN Volker LUDEKE Heinrich Institute of Aerodynamics and Flow Technology German Aerospace Center (DLR) Braunschweig 38108 Germam Institute of Aerodynamics and Flow Technology German Aerospace Center (DLR) Gottingen 37073 Germany Department of Aeronautics Xiamen University Xiamen 361005 China

The flows behind the base of a generic rocket, at both hypersonic and subsonic flow conditions, are numerically studied. The main concerns are addressed to the evaluation of turbulence models and the using of grid adaptation techniques. The investigation focuses on two configurations, related to hypersonic and subsonic experiments. The applicability tests of different turbu- lence models are conducted on the level of two-equation models calculating the steady state solution of the Reynolds-averaged Navier-Stokes（RANS） equations. All used models, the original Wilcox k-co, the Menter shear-stress transport （SST） and the ex- plicit algebraic Reynolds stress model（EARSM） formulation, predict an asymmetric base flow in both cases caused by the support of the models. A comparison with preliminary experimental results indicates a preference for the SST and EARSM results over the results from the older k-co model. Sensitivity studies show no significant influence of the grid topology or the location of the laminar to turbulent transition on the base flow field, but a strong influence of even small angles of attack is reported from the related experiments.

关键词： base flows turbulence models steady calculation grid adaptation numerical simulation

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Environmentally Adapted Hydropower in Sweden

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Small Hydro Power News 2006年第1期23卷 19-24页

作者： bjorn Svensson SwedPower AB Sweden

IntroductionThe alteration of watercourses has been extensive in Sweden as well as in other industrialised countries. Since the end of the last century the water table of about 2500 lakes have been lowered in order to reclaim farmland. More than 600 of these have been completely drained. This particular activity came to a halt at the end of the 1950s whereas the ditching of wetlands and dredging and channelisation of watercourses for the benefit of forestry are still ongoing activities. The regulation of rivers for the purpose of meeting differential needs of hydroelectric power commenced in the beginning of this century, At that time, the floating of timber constituted the economically most important profit from exploitation of northern Swedish rivers.

关键词：瑞典小水电水电站水资源

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