Results for "Tor Arne Johansen"

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Towards autonomous ocean observing systems using Miniature Underwater Gliders with UAV deployment and recovery capabilitiesFeb 08 2019This paper presents preliminary results towards the development of an autonomous ocean observing system using Miniature Underwater Gliders (MUGs) that can operate with the support of Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vessels (USVs) ... More
SensIs - Underwater acoustic network for ice-monitoringApr 08 2016Routing for low latency underwater acoustic network-communication is investigated. The application is monitoring of ice-threats to offshore operations in the Arctic - to provide warnings that enable operators to react to such threats. The scenario produces ... More
Fault-Tolerant Control Allocation: an Unknown Input Observer based approachJun 23 2013This paper focuses on the use of unknown input observers for detection and isolation of actuator and effector faults with control reconfiguration in overactuated systems. The control allocation actively uses input redundancy in order to make relevant ... More
Regret Analysis of the Anytime Optimally Confident UCB AlgorithmMar 29 2016May 06 2016I introduce and analyse an anytime version of the Optimally Confident UCB (OCUCB) algorithm designed for minimising the cumulative regret in finite-armed stochastic bandits with subgaussian noise. The new algorithm is simple, intuitive (in hindsight) ... More
Regret Analysis of the Finite-Horizon Gittins Index Strategy for Multi-Armed BanditsNov 18 2015May 27 2016I analyse the frequentist regret of the famous Gittins index strategy for multi-armed bandits with Gaussian noise and a finite horizon. Remarkably it turns out that this approach leads to finite-time regret guarantees comparable to those available for ... More
Cohomological Degrees, Dilworth Numbers and Linear ResolutionAug 22 2010This thesis is a study of various ways of measuring the size and complexity of finitely generated modules over a Noetherian local ring. The classical example is the multiplicity or degree. Here we investigate several variants of the degree function: the ... More
R-hadron at ATLAS -Discovery Prospects and PropertiesJan 30 2007Jan 31 2007R-hadrons are massive, meta-stable particles predicted in several Super- symmetry scenarios. Studies exploring the discovery potential of R-hadrons at the ATLAS detector have mainly focused on gluino R-hadrons. These studies have shown that gluino R-hadrons ... More
On Flow Equivalence of Sofic ShiftsOct 10 2012The flow equivalence of sofic shifts is examined using results about the structure of the corresponding covers. A canonical cover generalising the left Fischer cover to arbitrary sofic shifts is introduced and used to prove that the left Krieger cover ... More
Computing accurate Horner form approximations to special functions in finite precision arithmeticAug 13 2015In various applications, computers are required to compute approximations to univariate elementary and special functions such as $\exp$ and $\arctan$ to modest accuracy. This paper proposes a new heuristic for automating the design of such implementations. ... More
Optimal Ternary Cyclic Codes from MonomialsMay 01 2013Cyclic codes are a subclass of linear codes and have applications in consumer electronics, data storage systems, and communication systems as they have efficient encoding and decoding algorithms. Perfect nonlinear monomials were employed to construct ... More
Refined Lower Bounds for Adversarial BanditsMay 24 2016We provide new lower bounds on the regret that must be suffered by adversarial bandit algorithms. The new results show that recent upper bounds that either (a) hold with high-probability or (b) depend on the total lossof the best arm or (c) depend on ... More
Flow equivalence of sofic beta-shiftsApr 20 2015The Fischer, Krieger, and fiber product covers of sofic beta-shifts are constructed and used to show that every strictly sofic beta-shift is $2$-sofic. Flow invariants based on the covers are computed, and shown to only depend on an single integer easily ... More
New Binomial Bent Function over the Finite Fields of Odd CharacteristicJul 20 2009The $p$-ary function $f(x)$ mapping $\mathrm{GF}(p^{4k})$ to $\mathrm{GF}(p)$ given by $f(x)={\rm Tr}_{4k}\big(x^{p^{3k}+p^{2k}-p^k+1}+x^2\big)$ is proven to be a weakly regular bent function and the exact values of its Walsh transform coefficients are ... More
The End of Optimism? An Asymptotic Analysis of Finite-Armed Linear BanditsOct 14 2016Stochastic linear bandits are a natural and simple generalisation of finite-armed bandits with numerous practical applications. Current approaches focus on generalising existing techniques for finite-armed bandits, notably the optimism principle and Thompson ... More
Positivity Constraints on Anomalies and SupersymmetryJul 29 1998The relation between the trace and R-current anomalies in 4D supersymmetric theories implies that the U(1)$_R$F$^2$, U(1)$_R$ and U(1)$^3_R$ anomalies which matched in studies of N=1 Seiberg duality satisfy positivity constraints. These constraints are ... More
Experiments on Internet ResponseSep 01 2005This paper suggests a generalized distribution of response times to new information $\sim t^{-b}$ for human populations in the absence of deadlines. This has important implications for psychological and social studies as well the study of dynamical networks ... More
Remarks on reply to Johansen's commentJun 25 2002Remarks on reply (cond-mat/0206368) to Johansen's comment (cond-mat/0205249)
Twisting of N=1 SUSY Gauge Theories and Heterotic Topological TheoriesMar 03 1994Mar 18 1994It is shown that $D=4$ $N=1$ SUSY Yang-Mills theory with an appropriate supermultiplet of matter can be twisted on compact K\"ahler manifold. The conditions of cancellation of anomalies of BRST charge are found. The twisted theory has an appropriate BRST ... More
Solving maximum cut problems by simulated annealingMay 09 2015This paper gives a straightforward implementation of simulated annealing for solving maximum cut problems and compares its performance to that of some existing heuristic solvers. The formulation used is classical, dating to a 1989 paper of Johnson, Aragon, ... More
Magnetization in 2+1 dimensional QED at Finite Temperature and DensityOct 24 1994We consider Dirac fermions moving in a plane with a static homogeneous magnetic field orthogonal to the plane. We calculate the effective action at finite temperature and density. The magnetization is derived and it is shown that the fermion gas exhibits ... More
Principes locaux-globaux pour certaines fibrations en torseurs sous un toreMay 03 2013Jan 11 2015Let $k$ be a number field and let $T$ be a $k$-torus. Consider a fibration in torsors under $T$, i.e. a morphism $f: X \to \mathbb{P}^1_k$ from a smooth, projective $k$-variety $X$ to $\mathbb{P}^1_k$ such that the generic fibre $X_\eta \to \eta$ is a ... More
Proof of Riemann's zeta-hypothesisSep 30 2008Oct 14 2013Make an exponential transformation in the integral formulation of Riemann's zeta-function zeta(s) for Re(s) > 0. Separately, in addition make the substitution s -> 1 - s and then transform back to s again using the functional equation. Using residue calculus, ... More
Universal Prediction of Selected BitsJul 27 2011Many learning tasks can be viewed as sequence prediction problems. For example, online classification can be converted to sequence prediction with the sequence being pairs of input/target data and where the goal is to correctly predict the target data ... More
3-Colourability of Dually Chordal Graphs in Linear TimeJun 01 2012Nov 13 2012A graph G is dually chordal if there is a spanning tree T of G such that any maximal clique of G induces a subtree in T. This paper investigates the Colourability problem on dually chordal graphs. It will show that it is NP-complete in case of four colours ... More
State symmetries in matrices and vectors on finite state spacesSep 15 2004State symmetries are defined as permutations which act on vector spaces of column vectors and square matrices, resulting in isotropy groups for specific vector spaces. A large number of properties for such objects is shown, to provide a rigorous basis ... More
Current driven spin-orbit torque oscillator: ferromagnetic and antiferromagnetic couplingJun 08 2016Sep 23 2016We consider theoretically the impact of Rashba spin-orbit coupling on spin torque oscillators (STOs) in synthetic ferromagnets and antiferromagnets that have either a bulk multilayer or a thin film structure. The synthetic magnets consist of a fixed polarizing ... More
Large Stock Market Price Drawdowns Are OutliersOct 03 2000Jul 25 2001Drawdowns are essential aspects of risk assessment in investment management. They offer a more natural measure of real market risks than the variance or other cumulants of daily (or some other fixed time scale) distributions of returns. Here, we extend ... More
Evaluation of the quantitative prediction of a trend reversal on the Japanese stock market in 1999Feb 03 2000In January 1999, the authors published a quantitative prediction that the Nikkei index should recover from its 14 year low in January 1999 and reach $\approx 20500$ a year later. The purpose of the present paper is to evaluate the performance of this ... More
Download relaxation dynamics on the WWW following newspaper publication of URLJul 23 1999Jul 24 1999A few key properties of the World-Wide-Web (WWW) has been established indicating the lack of any characteristic scales for the WWW, both in its topology and in its dynamics. Here, we report an experiment which quantifies another power law describing the ... More
Remarks on the inverse Cherednik-Opdam transform on the real lineFeb 04 2015We obtain Hausdorff-Young inequalities for the one-dimensional Cherednik--Opdam transform and its inverse, and we establish a real Paley-Wiener theorem for its inverse that generalizes an analogous result by N. B. Andersen for the Jacobi transform.
A short note on the Radon-Riesz property for continuous Banach space valued functionsJun 25 2015Jun 26 2015We present a generalization of the Radon-Riesz property to sequences of continuous functions with values in uniformly convex and uniformly smooth Banach spaces.
Frozen time in hyperbolic spacetime motionJul 25 2011Aug 24 2011According to the Lorentz transformation and clearly seen from the Minkowski diagram, hyperbolic spacetime motion of a test object relative to a stationary reference frame can be performed in a specific way such that time becomes frozen in the moving frame ... More
Protoplanetary Disk Turbulence Driven by the Streaming Instability: Linear Evolution and Numerical MethodsFeb 23 2007We present local simulations that verify the linear streaming instability that arises from aerodynamic coupling between solids and gas in protoplanetary disks. This robust instability creates enhancements in the particle density in order to tap the free ... More
Hardy--Littlewood inequalities for the Heckman--Opdam transformJan 26 2015We establish Hardy--Littlewood inequalities for the Heckman--Opdam transform associated to a general root datum $(\mathfrak{a},\Sigma,m)$ that generalizes an analogous result for the spherical Fourier transform on a Riemannian symmetric space of the non-compact ... More
Dust diffusion in protoplanetary discs by magnetorotational turbulenceJan 28 2005Aug 17 2005We measure the turbulent diffusion coefficient of dust grains embedded in magnetorotational turbulence in a protoplanetary disc directly from numerical simulations and compare it to the turbulent viscosity of the flow. The simulations are done in a local ... More
Evidence of discrete scale invariance in DLA and time-to-failure by canonical averagingMar 15 1998Discrete scale invariance, which corresponds to a partial breaking of the scaling symmetry, is reflected in the existence of a hierarchy of characteristic scales l0, c l0, c^2 l0,... where c is a preferred scaling ratio and l0 a microscopic cut-off. Signatures ... More
Log-periodic power law bubbles in Latin-American and Asian markets and correlated anti-bubbles in Western stock markets: An empirical studyJul 19 1999Twenty-two significant bubbles followed by large crashes or by severe corrections in the Argentinian, Brazilian, Chilean, Mexican, Peruvian, Venezuelan, Hong-Kong, Indonesian, Korean, Malaysian, Philippine and Thai stock markets indices are identified ... More
Protoplanetary Disk Turbulence Driven by the Streaming Instability: Non-Linear Saturation and Particle ConcentrationFeb 23 2007We present simulations of the non-linear evolution of streaming instabilities in protoplanetary disks. The two components of the disk, gas treated with grid hydrodynamics and solids treated as superparticles, are mutually coupled by drag forces. We find ... More
Forming the cores of giant planets from the radial pebble flux in protoplanetary discsAug 26 2014Apr 04 2016The formation of planetary cores must proceed rapidly in order for the giant planets to accrete their gaseous envelopes before the dissipation of the protoplanetary gas disc (<3 Myr). In orbits beyond 10 AU, direct accumulation of planetesimals by the ... More
Well-posedness of space and time dependent transport equations on a networkJun 26 2015This article is concerned with the study of weak solutions of a linear transport equation on a bounded domain with coupled boundary data for general non smooth space and time dependent velocity fields. The existence of solutions, its uniqueness and the ... More
$m$-Sequences of Different Lengths with Four-Valued Cross CorrelationDec 21 2007{\bf Abstract.} Considered is the distribution of the cross correlation between $m$-sequences of length $2^m-1$, where $m$ is even, and $m$-sequences of shorter length $2^{m/2}-1$. The infinite family of pairs of $m$-sequences with four-valued cross correlation ... More
Calculation of the Coherent Synchrotron Radiation Impedance from a WigglerJan 30 2003Most studies of Coherent Synchrotron Radiation (CSR) have only considered the radiation from independent dipole magnets. However, in the damping rings of future linear colliders, a large fraction of the radiation power will be emitted in damping wigglers. ... More
Optimal Resource Allocation with Semi-Bandit FeedbackJun 15 2014We study a sequential resource allocation problem involving a fixed number of recurring jobs. At each time-step the manager should distribute available resources among the jobs in order to maximise the expected number of completed jobs. Allocating more ... More
Concentration and Confidence for Discrete Bayesian Sequence PredictorsJun 29 2013Bayesian sequence prediction is a simple technique for predicting future symbols sampled from an unknown measure on infinite sequences over a countable alphabet. While strong bounds on the expected cumulative error are known, there are only limited results ... More
Trivariate Spline Representations for Computer Aided Design and Additive ManufacturingMar 15 2018Aug 30 2018Digital representations targeting design and simulation for Additive Manufacturing (AM) are addressed from the perspective of Computer Aided Geometric Design. We discuss the feasibility for multi-material AM for B-rep based CAD, STL, sculptured triangles ... More
Online Learning to Rank with FeaturesOct 05 2018We introduce a new model for online ranking in which the click probability factors into an examination and attractiveness function and the attractiveness function is a linear function of a feature vector and an unknown parameter. Only relatively mild ... More
Experiments in vortex avalanchesFeb 03 2004Avalanche dynamics is found in many phenomena spanning from earthquakes to the evolution of species. It can be also found in vortex matter when a type II superconductor is externally driven, for example, by increasing the magnetic field. Vortex avalanches ... More
The Electron/Muon Specific Two Higgs Doublet Model at e+ e- CollidersFeb 02 2015Recently, Kajiyama, Okada and Yagyu (KOY) proposed an electron/muon specific two Higgs doublet model. In this model, an S3 symmetry suppresses flavor changing neutral currents instead of a Z2 symmetry. In the "Type I" version of the model, the heavy Higgs ... More
Spectrum and Analytical Indices of the C*-Algebra of Wiener-Hopf OperatorsNov 07 2006Nov 05 2009We study multivariate generalisations of the classical Wiener--Hopf algebra, which is the C$^*$-algebra generated by the Wiener--Hopf operators, given by the convolutions restricted to convex cones. By the work of Muhly and Renault, this C$^*$-algebra ... More
An index theorem for Wiener--Hopf operatorsNov 07 2006Nov 05 2009We study multivariate generalisations of the classical Wiener--Hopf algebra, which is the C$^*$-algebra generated by the Wiener--Hopf operators, given by the convolutions restricted to convex cones. By the work of Muhly and Renault, this C$^*$-algebra ... More
Nonclassicality in Weak MeasurementsAug 05 2004We examine weak measurements of arbitrary observables where the object is prepared in a mixed state and on which measurements with imperfect detectors are made. The weak value of an observable can be expressed as a conditional expectation value over an ... More
On the discovery of Birkhoff's theoremAug 22 2005Sep 06 2005Birkhoff showed in 1923 that the Schwarzschild solution for the metric from a point particle was also valid in the a priori non-static case as long as the spherical symmetry was maintained. This theorem was actually discovered and published two years ... More
Radially resolved simulations of collapsing pebble clouds in protoplanetary discsJun 12 2017We study the collapse of pebble clouds with a statistical model to find the internal structure of comet-sized planetesimals. Pebble-pebble collisions occur during the collapse and the outcome of these collisions affect the resulting structure of the planetesimal. ... More
Integration of Particle-Gas Systems with Stiff Mutual Drag InteractionMar 28 2016Apr 15 2016Numerical simulation of numerous mm/cm-sized particles embedded in a gaseous disk has become an important tool in the study of planet formation and in understanding the dust distribution in observed protoplanetary disks. However, the mutual drag force ... More
Kick Motions for the NAO Robot using Dynamic Movement PrimitivesJun 02 2016In this paper, we present the probably first application of the popular \emph{Dynamic Movement Primitives (DMP)} approach to the domain of soccer-playing humanoid robots. DMPs are known for their ability to imitate previously demonstrated motions as well ... More
Uniqueness and stability result for Cauchy's equation of motion for a certain class of hyperelastic materialsFeb 04 2014Feb 05 2014We consider Cauchy's equation of motion for hyperelastic materials. The solution of this nonlinear initial-boundary value problem is the vector field which discribes the displacement which a particle of this material perceives when exposed to stress and ... More
Disturbance: It's a Feature, not a BugFeb 06 2019Results of measurements give legitimacy to a physical theory: What if acquiring these results in the first place necessitates what the same theory considers to be an interaction? In this note, we assume that theories account for interactions so that they ... More
Statistical Speech Model Description with VMF Mixture ModelAug 02 2018In this paper, we present the LSF parameters by a unit vector form, which has directional characteristics. The underlying distribution of this unit vector variable is modeled by a von Mises-Fisher mixture model (VMM). With the high rate theory, the optimal ... More
Instability of resonances under Stark perturbationsApr 16 2018Let $H^{\varepsilon}=-\frac{d^2}{dx^2}+\varepsilon x +V$, $\varepsilon\geq0$, on $L^2(\mathbf{R})$. Let $V=\sum_{k=1}^Nc_k|\psi_k\rangle\langle\psi_k|$ be a rank $N$ operator, where the $\psi_k\in L^2(\mathbf{R})$ are real, compactly supported, and even. ... More
On the linear complexity profile of some sequences derived from elliptic curvesSep 23 2015Oct 07 2015For a given elliptic curve $\mathbf{E}$ over a finite field of odd characteristic and a rational function $f$ on $\mathbf{E}$ we first study the linear complexity profiles of the sequences $f(nG)$, $n=1,2,\dots$ which complements earlier results of Hess ... More
Fluctuations in models of biological macroevolutionFeb 28 2005Fluctuations in diversity and extinction sizes are discussed and compared for two different, individual-based models of biological coevolution. Both models display power-law distributions for various quantities of evolutionary interest, such as the lifetimes ... More
Extensions of smoothing via taut stringsMar 20 2008Jan 29 2009Suppose that we observe independent random pairs $(X_1,Y_1)$, $(X_2,Y_2)$, >..., $(X_n,Y_n)$. Our goal is to estimate regression functions such as the conditional mean or $\beta$--quantile of $Y$ given $X$, where $0<\beta <1$. In order to achieve this ... More
Spin-pumping and Enhanced Gilbert Damping in Thin Magnetic Insulator FilmsMar 20 2013Precessing magnetization in a thin film magnetic insulator pumps spins into adjacent metals; however, this phenomenon is not quantitatively understood. We present a theory for the dependence of spin-pumping on the transverse mode number and in-plane wave ... More
Comptonization, the X-ray-radio correlation and the long-term periodicity in the chi-states of GRS 1915+105Jul 23 2002We analyzed 139 chi-state observations of GRS 1915+105 with RXTE from 1997 to 2000 and found i) that the observations fall into two groups with different Comptonization behavior, ii) that the slope of the hard X-ray component correlates with the radio ... More
Branching form of the resolvent at threshold for multi-dimensional discrete LaplaciansAug 12 2016Mar 15 2017We consider the discrete Laplacian on $\mathbb Z^d$, and compute asymptotic expansions of its resolvent around thresholds embedded in continuous spectrum as well as those at end points. We prove that the resolvent has a square-root branching if $d$ is ... More
Carlitz Rank and Index of Permutation PolynomialsNov 19 2016Carlitz rank and index are two important measures for the complexity of a permutation polynomial $f(x)$ over the finite field $\F_q$. In particular, for cryptographic applications we need both, a high Carlitz rank and a high index. In this article we ... More
The Measurement Problem Is the "Measurement" ProblemOct 10 2018Physics builds on two tenets: On the one hand, statements are expressed in formal languages. On the other, these statements are to be tested against experience. Observers are the nexus between experience and the account thereof. Whether this very account ... More
UBVRI photometric comparison sequences for symbiotic stars. IIMar 15 2001We present accurate and deep UBVRI photometric sequences for an additional 20 symbiotic stars. As for the 20 targets of Paper I, the sequences extend over wide brightness and color ranges, and are suited to cover both quiescence and outburst phases. The ... More
Homotopy theory of C*-algebrasNov 30 2008In this work we construct from ground up a homotopy theory of C*-algebras. This is achieved in parallel with the development of classical homotopy theory by first introducing an unstable model structure and second a stable model structure. The theory ... More
Dynamics of cosmic strings and springs; a covariant formulationApr 20 1993A general family of charge-current carrying cosmic string models is investigated. In the special case of circular configurations in arbitrary axially symmetric gravitational and electromagnetic backgrounds the dynamics is determined by simple point particle ... More
A Domain-Specific Language for Rich Motor Skill ArchitecturesFeb 26 2013Model-driven software development is a promising way to cope with the complexity of system integration in advanced robotics, as it already demonstrated its benefits in domains with comparably challenging system integration requirements. This paper reports ... More
Complex dynamics in coevolution models with ratio-dependent functional responseOct 26 2009We explore the complex dynamical behavior of two simple predator-prey models of biological coevolution that on the ecological level account for interspecific and intraspecific competition, as well as adaptive foraging behavior. The underlying individual-based ... More
Quantum Spin Tomography in Ferromagnet-Normal ConductorsFeb 12 2010We present a theory for a complete reconstruction of non-local spin correlations in ferromagnet-normal conductors. This quantum spin tomography is based on cross correlation measurements of electric currents into ferromagnetic terminals with controllable ... More
Spin and Charge Pumping by Ferromagnetic-Superconductor Order ParametersApr 24 2004Sep 06 2004We study transport in ferromagnetic-superconductor/normal-metal systems. It is shown that charge and spin currents are pumped from ferromagnetic superconductors into adjacent normal metals by adiabatic changes in the order parameters induced by external ... More
Family complexity and cross-correlation measure for families of binary sequencesAug 21 2014We study the relationship between two measures of pseudorandomness for families of binary sequences: family complexity and cross-correlation measure introduced by Ahlswede et al.\ in 2003 and recently by Gyarmati et al., respectively. More precisely, ... More
Logarithmic good reduction of abelian varietiesDec 08 2015Oct 23 2016Let $K$ be a field which is complete for a discrete valuation. We prove a logarithmic version of the N\'eron-Ogg-Shafarevich criterion: if $A$ is an abelian variety over $K$ which is cohomologically tame, then $A$ has good reduction in the logarithmic ... More
Computing the Rank and a Small Nullspace Basis of a Polynomial MatrixMay 11 2005We reduce the problem of computing the rank and a nullspace basis of a univariate polynomial matrix to polynomial matrix multiplication. For an input n x n matrix of degree d over a field K we give a rank and nullspace algorithm using about the same number ... More
Schrödinger operators on the half line: Resolvent expansions and the Fermi golden rule at thresholdsJul 14 2007We consider Schr\"odinger operators $H=- \d^2/\d r^2+V$ on $L^2([0,\infty))$ with the Dirichlet boundary condition. The potential $V$ may be local or non-local, with polynomial decay at infinity. The point zero in the spectrum of $H$ is classified, and ... More
Resolvent expansions for the Schrödinger operator on the discrete half-lineDec 05 2016Apr 14 2017Simplified models of transport in mesoscopic systems are often based on a small sample connected to a finite number of leads. The leads are often modelled using the Laplacian on the discrete half-line $\mathbb N$. Detailed studies of the transport near ... More
Almost all random graphs are amplifiers of selection for Birth-death dynamics, but suppressors of selection for death-Birth dynamicsApr 15 2015We analyze evolutionary dynamics on graphs, where the nodes represent individuals of a population. The links of a node describe which other individuals can be displaced by the offspring of the individual on that node. Amplifiers of selection are graphs ... More
Logarithmic good reduction of abelian varietiesDec 08 2015Let $K$ be a field which is complete for a discrete valuation. We prove a logarithmic version of the N\'eron-Ogg-Shafarevich criterion: if $A$ is an abelian variety over $K$ which is cohomologically tame, then $A$ has good reduction in the logarithmic ... More
Static deformation of heavy spring due to gravity and centrifugal forceJan 13 2010The static equilibrium deformation of a heavy spring due to its own weight is calculated for two cases. First for a spring hanging in a constant gravitational field, then for a spring which is at rest in a rotating system where it is stretched by the ... More
UBVRI photometric sequences for symbiotic starsAug 16 2002Deep, wide-range and accurate UBVRI photometric sequences have been established around more than 80 symbiotic stars, to assist current photometry as well as measurement of old photographic plates. Sequences for 40 symbiotic stars have already been published; ... More
Photometry of the progenitor of Nova Del 2013 (V339 Del) and calibration of a deep BVRI photometricDec 20 2013The Asiago plate archive has been searched for old plates covering the region of the sky containing Nova Del 2013 (V339 Del). The brightness of the progenitor was measured against a deep BVRI photometric sequence that we calibrated on purpose. The mean ... More
Constructing interpolating Blaschke products with given preimagesMar 31 2006We give a constructive and flexible proof of a result of P. Gorkin and R. Mortini concerning a special finite interpolation problem on the unit circle with interpolating Blaschke products. Our proof also shows that the result can be generalized to other ... More
Complex Behavior in Simple Models of Biological CoevolutionSep 08 2006We explore the complex dynamical behavior of simple predator-prey models of biological coevolution that account for interspecific and intraspecific competition for resources, as well as adaptive foraging behavior. In long kinetic Monte Carlo simulations ... More
Automatic and efficient driving strategies while approaching a traffic lightAug 23 2014Vehicle-infrastructure communication opens up new ways to improve traffic flow efficiency at signalized intersections. In this study, we assume that equipped vehicles can obtain information about switching times of relevant traffic lights in advance. ... More
Simulation Study of a Traffic Light Assistant Based on Vehicle-Infrastructure CommunicationMar 19 2014Mar 29 2014Vehicle-infrastructure communication opens up new ways to improve traffic flow efficiency at signalized intersections. In this study, we assume that equipped vehicles can obtain information about switching times of relevant traffic lights in advance, ... More
Calibrating Car-Following Models using Trajectory Data: Methodological StudyMar 28 2008The car-following behavior of individual drivers in real city traffic is studied on the basis of (publicly available) trajectory datasets recorded by a vehicle equipped with an radar sensor. By means of a nonlinear optimization procedure based on a genetic ... More
Annihilating fields of standard modules of sl(2,C)~ and combinatorial identitiesJun 19 1998We show that a set of local admissible fields generates a vertex algebra. For an affine Lie algebra $\tilde\goth g$ we construct the corresponding level $k$ vertex operator algebra and we show that level $k$ highest weight $\tilde\goth g$-modules are ... More
Fibrations with few rational pointsNov 25 2015Aug 29 2016We study the problem of counting the number of varieties in families which have a rational point. We give conditions on the singular fibres that force very few of the varieties in the family to contain a rational point, in a precise quantitative sense. ... More
Reduction formula for fermion loops and density correlations of the 1D Fermi gasApr 08 1999Fermion N-loops with an arbitrary number of density vertices N > d+1 in d spatial dimensions can be expressed as a linear combination of (d+1)-loops with coefficients that are rational functions of external momentum and energy variables. A theorem on ... More
Adding Geographical Embedding to AS Topology GenerationSep 24 2014To study large-scale effects on the Internet various mod- els have been introduced to generate Internet-like autono- mous system (AS) topologies. The models for large-scale AS topologies have been focused on replicating structural graph properties. One ... More
Polynomial quotients: Interpolation, value sets and Waring's problemFeb 09 2014For an odd prime $p$ and an integer $w\ge 1$, polynomial quotients $q_{p,w}(u)$ are defined by $$ q_{p,w}(u)\equiv \frac{u^w-u^{wp}}{p} \bmod p ~~ \mathrm{with}~~ 0 \le q_{p,w}(u) \le p-1, ~~u\ge 0, $$ which are generalizations of Fermat quotients $q_{p,p-1}(u)$. ... More
Crowding in the GAIA spectrograph focal planeJan 13 2003Superpositions of stellar tracings are present in every slitless spectrograph. The probability for such overlaps in the GAIA RVS spectrograph focal plane is estimated using photometric observations of 66 stellar fields, mostly close to the Galactic plane. ... More
Stochastic evolutionary game dynamicsNov 21 2008In this review, we summarize recent developments in stochastic evolutionary game dynamics of finite populations.
An Open-Source Microscopic Traffic SimulatorDec 22 2010We present the interactive Java-based open-source traffic simulator available at www.traffic-simulation.de. In contrast to most closed-source commercial simulators, the focus is on investigating fundamental issues of traffic dynamics rather than simulating ... More
Calibration and validation of models describing the spatiotemporal evolution of congested traffic patternsAug 10 2010We propose a quantitative approach for calibrating and validating key features of traffic instabilities based on speed time series obtained from aggregated data of a series of neighboring stationary detectors. We apply the proposed criteria to historic ... More
Self-optimization, community stability, and fluctuations in two individual-based models of biological coevolutionAug 19 2005May 03 2007We compare and contrast the long-time dynamical properties of two individual-based models of biological coevolution. Selection occurs via multispecies, stochastic population dynamics with reproduction probabilities that depend nonlinearly on the population ... More
Phase Diagram of a Lattice Microemulsion Model in Two DimensionsJul 06 1992The phase diagram of a lattice microemulsion model proposed by Ciach, H{\o}ye and Stell is studied using mean-field theory and Monte Carlo simulations. Surfactant directional degrees of freedom are summed out exactly before mean-field theory is applied, ... More