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A Local Velocity Grid Approach for BGK Equation

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Communications in Computational Physics 2014年第9期16卷 956-982页

作者： florian Bernard Angelo Iollo Gabriella Puppo Department of Mechanical and Aerospace Engineering Politecnico di Torino10129 TorinoItaly. Univ.Bordeaux IMBUMR 5251F-33400 TalenceFrance.INRIAF-33400 TalenceFrance. Dip.di Scienza ed Alta Tecnologia Universita dell’InsubriaComoItaly

The solution of complex rarefied flows with the BGK equation and the Discrete Velocity Method(DVM)requires a large number of velocity grid points leading to significant computational *** propose an adaptive velocity grid approach exploiting the fact that locally in space,the distribution function is supported only by a sub-set of the global velocity *** velocity grid is adapted thanks to criteria based on local temperature,velocity and on the enforcement of mass *** in 1D and 2D are presented for different Knudsen numbers and compared to a global velocity grid BGK solution,showing the computational gain of the proposed approach.

关键词： Kinetic models BGK model discrete velocity method

Root and leaf functional trait relations in Poaceae species: implications of differing resource- acquisition strategies

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Journal of Plant Ecology 2013年第3期6卷 211-219页

作者： florian Fort Claire Jouany Pablo Cruz INRA UMR 1248 AGIRCentre de recherche de ToulouseCS 5262731326 Castanet-TolosanCedexFrance

Aims root systems play an essential role in grassland functioning in both acquisition and storage of ***,root functional traits have not received as much attention as those measured on above-ground organs,and little is known about their *** objec-tives were to test whether morphological and root system traits allowed identification of grass species’functional strategies and to determine whether a relation exists between above-and below-ground *** Functional traits of root tissues(specific root length,diameter,tissue density and nitrogen concentration),whole root systems(root mass,root length density,root mass percentage below a depth of 20 cm and fine root%)and two major leaf traits(specific leaf area and leaf dry matter content)were determined under field conditions and their rela-tions were analysed in eleven perennial temperate Poaceae *** Findings Canonical correspondence analysis along axis 1 revealed a gra-dient of species,from those with deep,dense and coarse root systems with a large root mass to those with shallow root sys-tems,thin roots and high specific root length;this suggests strong correlations among root *** between specific root length and specific leaf area reveal two groups of species,which probably indicates different drought-tolerance *** trait syndromes enable ranking grasses along a gradient from conservative-strategy species(from stressful habitats),which display a deep and coarse root system,to acquisitive species(from rich and moist meadows),which display a shallow and thin root *** both types display similar above-ground strategies,drought-tolerant species have lower specific root lengths than drought-sensitive species,revealing more conservative root strategies.

关键词： root functional trait functional group grasses root ecology below-ground strategy

Characteristics of developing scour-holes at a sand-embedded cylinder

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International Journal of Sediment Research 2008年第3期23卷 258-266页

作者： Oscar LINK florian PFLEGER Ulrich ZANKE Dept. of Civil Engineering University of Concepción Edmundo Larenas 270 Concepción Chile.Dr.-Ing. Assistant Prof. Doctoral Research Fellow Institute for Hydromechanics Technische Universitt München Arcisstrasse 21 80333 München Germany. Institute for Hydraulic and Water Resources Engineering Darmstadt University of Technology Rundeturmstraβe 1 64283 Germany.Full Prof.

Characteristics of developing scour-holes at a sand-embedded 0.2 m diameter circular cylinder are presented. Non-intrusive, high-resolution topographic measurements of developing scour-holes were made with an experimental installation using a laser distance sensor (LDS) and precision step-motors. A clear-water experiment was conducted with bed shear stress equal to 95% of the critical bed shear stress for the initiation of sediment motion at the undisturbed plane sand bed with a d50 of 0.26 mm. During the running experiment of 21 hours duration, measurements were taken by the LDS in different azimuthal half-planes with θ = 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165 and 180o in order to study the spatio-temporal variation of geometric properties in developing scour-holes. After 21 hours, the equilibrium condition was approached, with a scour rate less than d50 per hour. Measurement of maximum scour depth in different azimuthal half-planes at different points in time during the experiment show that scour started at the cylinder side and surrounded the cylinder after about 20% of experiment time. Slopes of developing scour-holes presented three regions with different inclinations, which were attributed to vortex action. Both maximum scour depth and maximum scour radius at different azimuthal half-planes are well correlated with the maximum scour depth at plane with θ = 0o. When providing maximum scour depth at the cylinder front, the presented correlations are useful for simple calculation of scour-hole topography. This work provides an experimental database for advanced numerical simulation for loose sediment hydraulics.

关键词： Scour Bridges Piers Sediment transport Loose sediment hydraulics

Graph-based visual analytics for cyber threat intelligence

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Cybersecurity 2018年第1期1卷 279-297页

作者： Fabian Bohm florian Menges Gunther Pernul Department of Information Systems University of RegensburgUniversitatsstraBe 3193053 RegensburgGermany

The ever-increasing amount of major security incidents has led to an emerging interest in cooperative approaches to encounter cyber *** enable cooperation in detecting and preventing attacks it is an inevitable necessity to have structured and standardized formats to describe an *** formats are complex and of an extensive nature as they are often designed for automated processing and *** characteristics hamper the readability and,therefore,prevent humans from understanding the documented *** is a major problem since the success and effectiveness of any security measure rely heavily on the contribution of security *** meet these shortcomings we propose a visual analytics concept enabling security experts to analyze and enrich semi-structured cyber threat intelligence *** approach combines an innovative way of persisting this data with an interactive visualization component to analyze and edit the threat *** demonstrate the feasibility of our concept using the Structured Threat Information eXpression,the state-ofthe-art format for reporting cyber security issues.

关键词： Cyber threat intelligence Visual analytics Usable cybersecurity STIX

A High-Order Discontinuous Galerkin Solver for Helically Symmetric Flows

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Communications in Computational Physics 2021年第6期30卷 288-320页

作者： Dominik Dierkes florian Kummer Dominik Plumacher Department of Mechanical Engineering Technische Universitat DarmstadtOtto-Berndt-Straße 264287 DarmstadtGermany

We present a high-order discontinuous Galerkin(DG)scheme to solve the system of helically symmetric Navier-Stokes equations which are discussed in[28].In particular,we discretize the helically reduced Navier-Stokes equations emerging from a reduction of the independent variables such that the remaining variables are:t,r,ξwithξ=az+bϕ,where r,ϕ,z are common cylindrical coordinates and t the *** this,all three velocity components are kept non-zero.A new non-singular coordinateηis introduced which ensures that a mapping of helical solutions into the three-dimensional space is well *** that,periodicity conditions for the helical frame aswell as uniqueness conditions at the centerline axis r=0 are *** the sector near the axis of the computational domain a change of the polynomial basis is implemented such that all physical quantities are uniquely defined at the *** the temporal integration,we present a semi-explicit scheme of third order where the full spatial operator is splitted into a Stokes operator which is discretized implicitly and an operator for the nonlinear terms which is treated *** are conducted for a cylindrical shell,excluding the centerline axis,and for the full cylindrical domain,where the centerline is *** all cases we obtain the convergence rates of order O(hk+1)that are expected from DG *** addition to the first DG discretization of the system of helically invariant Navier-Stokes equations,the treatment of the central axis,the resulting reduction of the DG space,and the simultaneous use of a semi-explicit time stepper are of particular novelty.

关键词： Discontinuous Galerkin(DG) helical flows

Human-as-a-security-sensor for harvesting threat intelligence

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Cybersecurity 2018年第1期1卷 652-666页

作者： Manfred Vielberth florian Menges Gunther Pernul Universitat Regensburg Universitatstr.3193053 RegensburgDEGermany

Humans are commonly seen as the weakest link in corporate information *** led to a lot of effort being put into security training and awareness campaigns,which resulted in employees being less likely the target of successful *** approaches,however,do not tap the full potential that can be gained through these *** the one hand,human perception offers an additional source of contextual information for detected incidents,on the other hand it serves as information source for incidents that may not be detectable by automated *** approaches only allow a text-based reporting of basic incident information.A structured recording of human delivered information that also provides compatibility with existing SIEM systems is still *** this work,we propose an approach,which allows humans to systematically report perceived anomalies or incidents in a structured *** approach furthermore supports the integration of such reports into analytics ***,we identify connecting points to SIEM systems,develop a taxonomy for structuring elements reportable by humans acting as a security sensor and develop a structured data format to record data delivered by humans.A prototypical human-as-a-security-sensor wizard applied to a real-world use-case shows our proof of concept.

关键词： Cyber threat intelligence Human awareness Human-as-a-security-sensor Security information and event management(SIEM)

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High-resolution peak demand estimation using generalized additive models and deep neural networks

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Energy and AI 2023年第3期13卷 3-13页

作者： Jonathan Berrisch Michal Narajewski florian Ziel University of Duisburg-Essen Germany

This paper covers predicting high-resolution electricity peak demand features given lower-resolution *** is a relevant setup as it answers whether limited higher-resolution monitoring helps to estimate future high-resolution peak loads when the high-resolution data is no longer *** question is particularly interesting for network operators considering replacing high-resolution monitoring by predictive models due to economic *** propose models to predict half-hourly minima and maxima of high-resolution(every minute)electricity load data while model inputs are of a lower resolution(30 min).We combine predictions of generalized additive models(GAM)and deep artificial neural networks(DNN),which are popular in load *** extensively analyze the prediction models,including the input parameters’importance,focusing on load,weather,and seasonal *** proposed method won a data competition organized by Western Power Distribution,a British distribution network *** addition,we provide a rigorous evaluation study that goes beyond the competition frame to analyze the models’*** results show that the proposed methods are superior to the competition benchmark concerning the out-of-sample root mean squared error(RMSE).This holds regarding the competition month and the supplementary evaluation study,which covers an additional eleven ***,our proposed model combination reduces the out-of-sample RMSE by 57.4%compared to the benchmark.

关键词： Electricity peak load,Generalized additive models,Artificial neural networks,Prediction Combination,Weather effects,Seasonality

Universal influenza virus vaccines： what can we learn from the human immune response following exposure to H7 subtype viruses？

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Frontiers of Medicine 2017年第4期11卷 471-479页

作者： Daniel Stadlbauer Raffael Nachbagauer Philip Meade florian Krammer Department of Microbiology Icahn School of Medicine at Mount Sinai New York IVY 10024 USA Department of Biotechnology University of Natural Resources and Life Sciences 1190 Vienna Austria Graduate School of Biomedical Sciences Icahn School of Medicine at Mount Sinai New York NY 10024 USA

Several universal influenza virus vaccine candidates based on eliciting antibodies against the hemagglutinin stalk domain are in development. Typically, these vaccines induce responses that target group 1 or group 2 hemagglutinins with Httle to no cross-group reactivity and protection. Similarly, the majority of human anti-stalk monoclonal antibodies that have been isolated are directed against group 1 or group 2 hemagglutinins with very few that bind to hemagglutinins of both groups. Here we review what is known about the human humoral immune response to vaccination and infection with H7 subtype influenza viruses on a polyclonal and monoclonal level. It seems that unlike vaccination with H5 hemagglutinin, which induces antibody responses mostly restricted to the group 1 stalk domain, H7 exposure induces both group 2 and cross-group antibody responses. A better understanding of this phenomenon and the underlying mechanisms might help to develop future universal influenza virus vaccine candidates.

关键词： universal influenza virus vaccine hemagglutinin stalk H7N9

Impact of crystalline and amorphous iron-and aluminum hydroxides on mechanisms of phosphate adsorption and desorption

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Journal of Environmental Sciences 2018年第8期30卷 175-189页

作者： Stella Gypser florian Hirsch Anja M.Schleicher Dirk Freese Brandenburg University of Technology Cottbus-Senftenberg Faculty of Environment Process Engineering Biotechnology and Chemistry Department of Soil Protection and Recultivation Brandenburg University of Technology Cottbus-Senftenberg Faculty of Environment Process Engineering Biotechnology and Chemistry Department of Geopedology and Landscape Development German Research Centre for Geosciences Section 3.1 Inorganic and Isotope Geochchemistry

Fourier-transform infrared（FT-IR） spectroscopic experiments were carried out during phosphate adsorption on highly crystalline gibbsite, poorly crystalline 2-line-ferrihydrite and amorphous iron–aluminum–hydroxide mixtures in the molar ratio 1：0, 10：1, 5：1, 1：1, 1：5, 1：10 and 0：1. The OH stretching vibrational bands were utilized to analyze changes in structural and surface OH groups during adsorption, because the position of characteristic P／O vibrational bands can shift depending on reaction conditions, pH or adsorbed phosphate *** and desorption kinetics were studied at pH6 and different initial phosphate concentrations to achieve varying phosphate coverage on the mineral surfaces. For gibbsite the formation of AlHPO4 and Al2HPO4 can be assumed, while for ferrihydrite, a FeHPO4 or Fe2PO4 complex and the precipitation of FePO4 with longer equilibration time were ***2HPO4 or a Fe2PO4 surface complex was deduced for Fe-hydroxides, an AlH2PO4 surface complex was identified for Al-hydroxide, and both displayed either hydrogen bonds to neighboring hydroxyl groups or hydrogen bonds to outer-sphere complexes. Fe：Al-hydroxide mixtures with high Al ratios showed a low phosphate desorption rate, while ferrihydrite and the Fe：Al-hydroxide mixtures with high Fe ratios had almost negligible desorption rates. It was concluded that within the weakly associated amorphous FeO（OH） materials, FePO4 precipitated, which was bound by outer-sphere hydrogen bonds. With high Al ratios, desorption increased, which indicated weaker phosphate binding of both inner-sphere and outer-sphere complexes and hence, either no or minor quantities of precipitate. Ferrihydrite showed a more rigid structure and a lower extent of precipitation compared to amorphous Fe-hydroxide.

关键词： Phosphate Adsorption Desorption Surface complexation Precipitation FT-IR