221 research outputs found
Dave and Dottie Seibold : founding members of the Grand Haven Area Historical Society
No full textGrand Haven historian, author, and dentist Dave Seibold has a passionate interest in community heritage. Prior to relocating to Grand Haven, Dr. Seibold served in Hawaii at a dental clinic for children. In this interview, Dr. Seibold and his wife Dottie discuss the founding of the Grand Haven Area Historical Society, which began its existence as the Tri-Cities Historical Society in 1959, and the Tri-Cities Historical Museum. Dr. Seibold explains the efforts to save the Grand Haven railroad depot from demolition for possible use as a museum and his project to write a history of northern Ottawa County to continue the work of historian Leo C. Lillie. In 1990, Dr. Seibold authored and published Coast Guard City, U.S.A: A History of the Port of Grand Haven. The Seibolds also recall how they met in their hometown of Jackson, Michigan, married, and chose Grand Haven as their home in 1955
StaRMAP - A second order staggered grid method for spherical harmonics moment equations of radiative transfer
No full textWe present a simple method to solve spherical harmonics moment systems, such
as the the time-dependent and equations, of radiative transfer.
The method, which works for arbitrary moment order , makes use of the
specific coupling between the moments in the equations. This coupling
naturally induces staggered grids in space and time, which in turn give rise to
a canonical, second-order accurate finite difference scheme. While the scheme
does not possess TVD or realizability limiters, its simplicity allows for a
very efficient implementation in Matlab. We present several test cases, some of
which demonstrate that the code solves problems with ten million degrees of
freedom in space, angle, and time within a few seconds. The code for the
numerical scheme, called StaRMAP (Staggered grid Radiation Moment
Approximation), along with files for all presented test cases, can be
downloaded so that all results can be reproduced by the reader.Comment: 28 pages, 7 figures; StaRMAP code available at
http://www.math.temple.edu/~seibold/research/starma
Self-sustained nonlinear waves in traffic flow
No full textIn analogy to gas-dynamical detonation waves, which consist of a shock with an attached exothermic reaction zone, we consider herein nonlinear traveling wave solutions to the hyperbolic (“inviscid”) continuum traffic equations. Generic existence criteria are examined in the context of the Lax entropy conditions. Our analysis naturally precludes traveling wave solutions for which the shocks travel downstream more rapidly than individual vehicles. Consistent with recent experimental observations from a periodic roadway [Y. Sugiyama et al., N. J. Phys. 10, 033001 (2008)], our numerical calculations show that nonlinear traveling waves are attracting solutions, with the time evolution of the system converging toward a wave-dominated configuration. Theoretical principles are elucidated by considering examples of traffic flow on open and closed roadways.National Science FoundationUSAFOSR Young Investigator ProgramNSERC Discovery Grant Progra
Improving author co-citation analysis in scientific literature by using citation function classification
No full textThe concept of co-citation analysis is a possible approach for the interpretation of the relations between scientific papers or authors. Most of the previous work regarding author co-citation analysis, however, does not take the citation context into account. In this thesis, I propose a method for letting citation functions, which are functions that represent the intention of an author assigned to the corresponding references, directly influence the author co-citation analysis procedure. This approach is based on a faceted citation classification scheme, which allows comparisons between references. This should allow an easier representation of author groups, as authors, which are working together, usually share the same view on science and, therefore, are likely to be cited similarly. As there is no real gold standard for author groups, the evaluation of this approach tests the textual coherence of clusters created by this procedure based on the authors' oeuvres and compares the nationality of authors within clusters. The results indicate a correlation between author groups and similar citation functions.Die Thematik der Co-Zitation Analyse beschreibt einen möglichen generellen Ansatz zur Interpretation von Beziehungen zwischen einer Menge von wissenschaftlichen Arbeiten oder Autoren. Die meisten Methoden zur Erstellung von Autorenclustern, die bisher zu diesem Themengebiet vorgestellt wurden, nehmen keinen Bezug auf den Kontext, in welchem die jeweiligen Zitationen vorkommen. In dieser Arbeit stelle ich eine Möglichkeit vor, durch die Zitationsfunktionen direkten Einfluss auf Autorcozitationsanalyse nehmen kann. Eine Zitationsfunktion gibt die Intention des Autors wieder, welche zu einer Referenz geführt hat, und ist somit an diese Referenz gebunden. Der hier vorgestellte Vorgang bezieht sich auf eine facettiertes Zitationsklassifikationsschema, durch welches Referenzen verglichen werden können. Dies sollte eine einfachere Möglichkeit darbieten Autorengruppen darzustellen, da diese, dadurch dass sie ähnliche Ansichtspunkte auf ihre Fachgebiete haben, auf ähnliche Art und Weise zitiert werden. Da es keinen richtigen Goldstandard für Autorengruppen gibt, bezieht sich die Evaluation auf den textbezogenen Zusammenhang zwischen den Oeuvres von Autoren und die Repräsentation von Nationalitäten innerhalb von Clustern. Die Resultate, die in dieser Arbeit gefunden werden, deuten darauf hin, dass es tatsächlich einen Zusammenhang zwischen Authorengruppen und ähnlichen Zitierweisen dieser Autoren gibt
Wood decomposition is increased by insect diversity, selection effects, and interactions between insects and microbes
No full textThe data is for the publication:Jia-Yun Zou, Marc W. Cadotte, Claus Bässler, Roland Brandl, Petr Baldrian, Werner Borken, Elisa Stengel, Ya-Huang Luo, Jörg Müller, Sebastian Seibold*. 2023. Wood decomposition is increased by insect diversity, selection effects, and interactions between insects and microbes. Ecology*corresponding author: [email protected]</p
Macroscopic Coupling Conditions with Partial Blocking for Highway Ramps
No full textWe consider the Lighthill-Whitman-Richards traffic model on a network consisting of a highway with an off ramp, connected by a junction. We compare the known coupling conditions for the evolution of traffic at the junction and suggest a novel improvement to the existing conditions. That is, we resolve the spurious effects that arise in standard models, namely clogging of the main highway and vehicle destination changes. We achieve this by tracking vehicle density buildup in the form of a queue, which is modeled by an ODE. We define the solution to the Riemann problem at the junction using the supply and demand functions. The numerical approximation is carried out using a modified Godunov scheme, adjusted to take into account the effects of an emptying queue. Exact and numerical comparisons of the model with existing models verify that the number of vehicles who wish to exit are preserved and the nonphysical clogging of the main highway does not occur.Mathematic
MATHEMATICAL MODELING OF CYANOBACTERIAL DYNAMICS IN A CHEMOSTAT
No full textWe present a mathematical model that describes how cyanobacterial communities use natural light as a source of energy and water as a source of electrons to perform photosynthesis and therefore, grow and co-survive together with other bacterial species. We apply our model to a phototrophic population of bacteria, namely, cyanobacteria. Our model involves the use of light as a source of energy and inorganic carbon as a source of nutrients. First, we study a single species model involving only cyanobacteria, then we include heterotrophs in the two species model. The model consists of ordinary differential equations describing bacteria and chemicals evolution in time. Stability analysis results show that adding heterotrophs to a population of cyanobacteria increases the level of inorganic carbon in the medium, which in turns allows cyanobacteria to perform more photosynthesis. This increase of cyanobacterial biomass agrees with experimental data obtained by collaborators at the Center for Biofilm Engineering at Montana State University.Mathematic
Performance of algebraic multigrid methods for non-symmetric matrices arising in particle methods
No full textLarge linear systems with sparse, non-symmetric matrices arise in the
modeling of Markov chains or in the discretization of convection-diffusion
problems. Due to their potential to solve sparse linear systems with an effort
that is linear in the number of unknowns, algebraic multigrid (AMG) methods are
of fundamental interest for such systems. For symmetric positive definite
matrices, fundamental theoretical convergence results are established, and
efficient AMG solvers have been developed. In contrast, for non-symmetric
matrices, theoretical convergence results have been provided only recently. A
property that is sufficient for convergence is that the matrix be an M-matrix.
In this paper, we present how the simulation of incompressible fluid flows with
particle methods leads to large linear systems with sparse, non-symmetric
matrices. In each time step, the Poisson equation is approximated by meshfree
finite differences. While traditional least squares approaches do not guarantee
an M-matrix structure, an approach based on linear optimization yields
optimally sparse M-matrices. For both types of discretization approaches, we
investigate the performance of a classical AMG method, as well as an AMLI type
method. While in the considered test problems, the M-matrix structure turns out
not to be necessary for the convergence of AMG, problems can occur when it is
violated. In addition, the matrices obtained by the linear optimization
approach result in fast solution times due to their optimal sparsity.Comment: 16 pages, 7 figure
Plan d'une usine d'acide nitrique
No full textDocument(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science
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