2,461 research outputs found
On Multiscale Methods in Petrov-Galerkin formulation
In this work we investigate the advantages of multiscale methods in
Petrov-Galerkin (PG) formulation in a general framework. The framework is based
on a localized orthogonal decomposition of a high dimensional solution space
into a low dimensional multiscale space with good approximation properties and
a high dimensional remainder space{, which only contains negligible fine scale
information}. The multiscale space can then be used to obtain accurate Galerkin
approximations. As a model problem we consider the Poisson equation. We prove
that a Petrov-Galerkin formulation does not suffer from a significant loss of
accuracy, and still preserve the convergence order of the original multiscale
method. We also prove inf-sup stability of a PG Continuous and a Discontinuous
Galerkin Finite Element multiscale method. Furthermore, we demonstrate that the
Petrov-Galerkin method can decrease the computational complexity significantly,
allowing for more efficient solution algorithms. As another application of the
framework, we show how the Petrov-Galerkin framework can be used to construct a
locally mass conservative solver for two-phase flow simulation that employs the
Buckley-Leverett equation. To achieve this, we couple a PG Discontinuous
Galerkin Finite Element method with an upwind scheme for a hyperbolic
conservation law
Hedonic Consumer Decision Making And Implications For The Marketing Of Media Goods
This cumulative dissertation investigates aspects of consumer decision making in hedonic contexts and its implications for the marketing of media goods through a series of three empirical studies. All three studies take place within a common theoretical framework of decision making models, applying parts of the framework in novel ways to solve real-world marketing research problems (study 1 and 2), and examining theoretical relationships between variables within of the framework (study 3). One notable way in which the studies differ is their theoretical treatment of the hedonic component of decision making, i.e. the role and conceptualization of emotions.Die vorliegende kumulative Dissertation untersucht anhand von drei empirischen Studien Entscheidungsverhalten im Kontext des Hedonischen Konsums und dessen Implikationen für das Marketing von Mediengütern. Hedonischer Konsumer ist definiert als die Facette des Konsumentenverhaltens, die sich auf „multisensorische, fantastische und emotionale Aspekte der Produktnutzung“ bezieht. Alle drei Studien sind weitgehend in den theoretischen Bezugsrahmen des „Information Processing View“ eingebettet, der Konsumenten als begrenzt rationale Nutzenmaximierer beschreibt. Die Kapitel 1 und 2 dieser Dissertation wenden Teile der Information Processing View-Theorie in neuartiger Weise auf aktuelle Probleme der Marketing-Forschung und der Filmindustrie an, während Kapitel 3 den Information Processing View systematisch um emotionale Aspekte des Entscheidungsverhaltens ergänzt und die theoretischen Beziehungen der Modellvariablen untereinander erforscht
Extremal Codes for Speed-up of Distributed Parallel Arbitration
This paper describes a method that allows the speed up of parallel processes in distributed arbitration schemes as used in Futurebus+. It is based on special arbitration codes that decrease the maximal arbitration time to a specified value. Such codes can be applied with few, if any, minor changes of the hardware. The general structure of these codes is given
Testing Exotic Scalars with HiggsBounds
The program HiggsBounds is a well-established tool for testing
Beyond-the-Standard Model (BSM) theories with an extended Higgs sector against
experimental limits from collider searches at LEP, Tevatron and LHC. Thus far,
it could be applied to any neutral or charged Higgs bosons originating from the
modified Higgs sector. Implicitly, these particles were assumed to exhibit a
somewhat hierarchical Yukawa structure as present in the Standard Model, where
in particular the couplings to first generation fermions could be neglected. In
this work, we extend the HiggsBounds functionalities to go beyond these
restrictions, thus making the code applicable to any neutral or charged BSM
scalars. Moreover, we develop a new approach to implement experimental searches
whose kinematic acceptance depends significantly on the values of the involved
couplings. We achieve this by recasting the searches to general scalar models.
Using this approach we incorporate relevant current experimental limits from
LHC searches for exotic scalars, and present the implications of these limits
for a dark matter scalar mediator model, a flipped Two-Higgs-Doublet Model and
a supersymmetric model with R-parity violation.Comment: 28 pages, 7 figures, the FeynRules implementation of the generic
scalar model is included as an ancillary file; v2: matches version published
in EPJ
Interpreting Safety Outcomes: Waymo's Performance Evaluation in the Context of a Broader Determination of Safety Readiness
This paper frames recent publications from Waymo within the broader context
of the safety readiness determination for an Automated Driving System (ADS).
Starting from a brief overview of safety performance outcomes reported by Waymo
(i.e., contact events experienced during fully autonomous operations), this
paper highlights the need for a diversified approach to safety determination
that complements the analysis of observed safety outcomes with other estimation
techniques. Our discussion highlights: the presentation of a "credibility
paradox" within the comparison between ADS crash data and human-derived
baselines; the recognition of continuous confidence growth through in-use
monitoring; and the need to supplement any aggregate statistical analysis with
appropriate event-level reasoning
International Space Station (ISS) S-Band Corona Discharge Anomaly Consultation
The Assembly and Contingency Radio Frequency Group (ACRFG) onboard the International Space Station (ISS) is used for command and control communications and transmits (45 dBm or 32 watts) and receives at S-band. The system is nominally pressurized with gaseous helium (He) and nitrogen (N2) at 8 pounds per square inch absolute (psia). MacDonald, Dettwiler and Associates Ltd. (MDA) was engaged to analyze the operational characteristics of this unit in an effort to determine if the anomalous behavior was a result of a corona event. Based on this analysis, MDA did not recommend continued use of this ACRFG. The NESC was requested to provide expert support in the area of high-voltage corona and multipactoring in an S-Band RF system and to assess the probability of corona occurring in the ACRFG during the planned EVA. The NESC recommended minimal continued use of S/N 002 ACRFG until a replacement unit can be installed. Following replacement, S/N 002 will be subjected to destructive failure analysis in an effort to determine the proximate and root cause(s) of the anomalous behavior
A new LHC search for dark matter produced via heavy Higgs bosons using simplified models
Searches for dark matter produced via scalar resonances in final states
consisting of Standard Model (SM) particles and missing transverse momentum are
of high relevance at the LHC. Motivated by dark-matter portal models, most
existing searches are optimized for unbalanced decay topologies for which the
missing momentum recoils against the visible SM particles. In this work, we
show that existing searches are also sensitive to a wider class of models,
which we characterize by a recently presented simplified model framework. We
point out that searches for models with a balanced decay topology can be
further improved with more dedicated analysis strategies. For this study, we
investigate the feasibility of a new search for bottom-quark associated neutral
Higgs production with a final state and
perform a detailed collider analysis. Our projected results in the different
simplified model topologies investigated here can be easily reinterpreted in a
wide range of models of physics beyond the SM, which we explicitly demonstrate
for the example of the Two-Higgs-Doublet model with an additional pseudoscalar
Higgs boson.Comment: 27 pages, 8 figures, 4 table
A minimal model of peptide binding predicts ensemble properties of serum antibodies
<p/> <p>Background</p> <p>The importance of peptide microarrays as a tool for serological diagnostics has strongly increased over the last decade. However, interpretation of the binding signals is still hampered by our limited understanding of the technology. This is in particular true for arrays probed with antibody mixtures of unknown complexity, such as sera. To gain insight into how signals depend on peptide amino acid sequences, we probed random-sequence peptide microarrays with sera of healthy and infected mice. We analyzed the resulting antibody binding profiles with regression methods and formulated a minimal model to explain our findings.</p> <p>Results</p> <p>Multivariate regression analysis relating peptide sequence to measured signals led to the definition of amino acid-associated weights. Although these weights do not contain information on amino acid position, they predict up to 40-50% of the binding profiles' variation. Mathematical modeling shows that this position-independent ansatz is only adequate for highly diverse random antibody mixtures which are not dominated by a few antibodies. Experimental results suggest that sera from healthy individuals correspond to that case, in contrast to sera of infected ones.</p> <p>Conclusions</p> <p>Our results indicate that position-independent amino acid-associated weights predict linear epitope binding of antibody mixtures only if the mixture is random, highly diverse, and contains no dominant antibodies. The discovered ensemble property is an important step towards an understanding of peptide-array serum-antibody binding profiles. It has implications for both serological diagnostics and B cell epitope mapping.</p
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