@unpublished{ZienickeSeehaferFeudel1997,
  author    = {Zienicke, Egbert and Seehafer, Norbert and Feudel, Fred},
  title     = {Bifurcations in two-dimensional Rayleigh-B{\´e}nard convection},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14534},
  year      = {1997},
  abstract  = {Two-dimensional bouyancy-driven convection in a horizontal fluid layer with stress-free boundary conditions at top and bottom and periodic boundary conditions in the horizontal direction is investigated by means of numerical simulation and bifurcation-analysis techniques. As the bouyancy forces increase, the primary stationary and symmetric convection rolls undergo successive Hopf bifurcations, bifurcations to traveling waves, and phase lockings. We pay attention to symmetry breaking and its connection with the generation of large-scale horizontal flows. Calculations of Lyapunov exponents indicate that at a Rayleigh number of 2.3×105 no temporal chaos is reached yet, but the system moves nonchaotically on a 4-torus in phase space.},
  language  = {en}
}
@unpublished{Zessin2010,
  author    = {Zessin, Hans},
  title     = {Classical Symmetric Point Processes : Lectures held at ICIMAF, La Habana, Cuba, 2010},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49619},
  year      = {2010},
  abstract  = {The aim of these lectures is a reformulation and generalization of the fundamental investigations of Alexander Bach [2, 3] on the concept of probability in the work of Boltzmann [6] in the language of modern point process theory. The dominating point of view here is its subordination under the disintegration theory of Krickeberg [14]. This enables us to make Bach's consideration much more transparent. Moreover the point process formulation turns out to be the natural framework for the applications to quantum mechanical models.},
  language  = {en}
}
@unpublished{YinHua2007,
  author    = {Yin, Yang and Hua, Chen},
  title     = {On chemotaxis systems with saturation growth},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-30254},
  year      = {2007},
  abstract  = {In this paper, we discuss the global existence of solutions for Chemotaxis models with saturation growth. If the coe±cients of the equations are all positive smooth T-periodic functions, then the problem has a positive T-periodic solution, and meanwhile we discuss here the stability problems for the T-periodic solutions.},
  language  = {en}
}
@unpublished{Yin2002,
  author    = {Yin, Huicheng},
  title     = {Formation and construction of a shock wave for 3-D compressible Euler equations with spherical initial data},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26263},
  year      = {2002},
  abstract  = {In this paper, the problem on formation and construction of a shock wave for three dimensional compressible Euler equations with the small perturbed spherical initial data is studied. If the given smooth initial data satisfies certain nondegenerate condition, then from the results in [20], we know that there exists a unique blowup point at the blowup time such that the first order derivates of smooth solution blow up meanwhile the solution itself is still continuous at the blowup point. From the blowup point, we construct a weak entropy solution which is not uniformly Lipschitz continuous on two sides of shock curve, moreover the strength of the constructed shock is zero at the blowup point and then gradually increases. Additionally, some detailed and precise estimates on the solution are obtained in the neighbourhood of the blowup point.},
  language  = {en}
}
@unpublished{Yin2002,
  author    = {Yin, Huicheng},
  title     = {Global existence of a shock for the supersonic flow past a curved wedge},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26272},
  year      = {2002},
  abstract  = {This note is devoted to the study on the global existence of a shock wave for the supersonic flow past a curved wedge. When the curved wedge is a small perturbation of a straight wedge and the angle of the wedge is less than some critical value, wwe show that a shock attached at the wedge will exist globally.},
  language  = {en}
}
@unpublished{YihongLi2001,
  author    = {Yihong, Du and Li, Ma},
  title     = {Some remarks related to De Giorgi's conjecture},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26027},
  year      = {2001},
  abstract  = {For several classes of functions including the special case f(u) = u - u³, we obtain boundedness and symmetry results for solutions of the problem -Δu = f(u) defined on R up(n). Our results complement a number of recent results related to a conjecture of De Giorgi.},
  language  = {en}
}
@unpublished{YagdjianGalstian2007,
  author    = {Yagdjian, Karen and Galstian, Anahit},
  title     = {Fundamental solutions for wave equation in de Sitter model of universe},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-30271},
  year      = {2007},
  abstract  = {In this article we construct the fundamental solutions for the wave equation arising in the de Sitter model of the universe. We use the fundamental solutions to represent solutions of the Cauchy problem and to prove the Lp - Lq-decay estimates for the solutions of the equation with and without a source term.},
  language  = {en}
}
@unpublished{Yagdjian2001,
  author    = {Yagdjian, Karen},
  title     = {Geometric optics for the nonlinear hyperbolic systems of Kirchhoff-type},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26059},
  year      = {2001},
  abstract  = {Contents: 1 Introduction 2 Main result 3 Construction of the asymptotic solutions 3.1 Derivation of the equations for the profiles 3.2 Exsistence of the principal profile 3.3 Determination of Usub(2) and the remaining profiles 4 Stability of the samll global solutions. Justification of One Phase Nonlinear Geometric Optics for the Kirchhoff-type equations 4.1 Stability of the global solutions to the Kirchhoff-type symmetric hyperbolic systems 4.2 The nonlinear system of ordinary differential equations with the parameter 4.3 Some energies estimates 4.4 The dependence of the solution W(t, ξ) on the function s(t) 4.5 The oscillatory integrals of the bilinear forms of the solutions 4.6 Estimates for the basic bilinear form Γsub(s)(t) 4.7 Contraction mapping 4.8 Stability of the global solution 4.9 Justification of One Phase Nonlinear Geometric Optics for the Kirchhoff-type equations},
  language  = {en}
}
@unpublished{XiaochunWitt2002,
  author    = {Xiaochun, Liu and Witt, Ingo},
  title     = {Pseudodifferential calculi on the half-line respecting prescribed asymptotic types},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26255},
  year      = {2002},
  abstract  = {Contents: 1. Introduction 2. Preliminaries 3. Basic Elements of the Calculus 4. Further Elements of the Calculus},
  language  = {en}
}
@unpublished{XiaochunWitt2001,
  author    = {Xiaochun, Liu and Witt, Ingo},
  title     = {Asymptotic expansions for bounded solutions to semilinear Fuchsian equations},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25912},
  year      = {2001},
  abstract  = {It is shown that bounded solutions to semilinear elliptic Fuchsian equations obey complete asymptoic expansions in terms of powers and logarithms in the distance to the boundary. For that purpose, Schuze's notion of asymptotic type for conormal asymptotics close to a conical point is refined. This in turn allows to perform explicit calculations on asymptotic types - modulo the resolution of the spectral problem for determining the singular exponents in the asmptotic expansions.},
  language  = {en}
}
@unpublished{XiaochunSchulze2004,
  author    = {Xiaochun, Liu and Schulze, Bert-Wolfgang},
  title     = {Boundary value problems in edge representation},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26746},
  year      = {2004},
  abstract  = {Edge representations of operators on closed manifolds are known to induce large classes of operators that are elliptic on specific manifolds with edges, cf. [9]. We apply this idea to the case of boundary value problems. We establish a correspondence between standard ellipticity and ellipticity with respect to the principal symbolic hierarchy of the edge algebra of boundary value problems, where an embedded submanifold on the boundary plays the role of an edge. We first consider the case that the weight is equal to the smoothness and calculate the dimensions of kernels and cokernels of the associated principal edge symbols. Then we pass to elliptic edge operators for arbitrary weights and construct the additional edge conditions by applying relative index results for conormal symbols.},
  language  = {en}
}
@unpublished{Witt2003,
  author    = {Witt, Ingo},
  title     = {Green formulae for cone differential operators},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26633},
  year      = {2003},
  abstract  = {Green formulae for elliptic cone differential operators are established. This is achieved by an accurate description of the maximal domain of an elliptic cone differential operator and its formal adjoint; thereby utilizing the concept of a discrete asymptotic type. From this description, the singular coefficients replacing the boundary traces in classical Green formulas are deduced.},
  language  = {en}
}
@unpublished{Witt2002,
  author    = {Witt, Ingo},
  title     = {Local asymptotic types},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26346},
  year      = {2002},
  abstract  = {The local theory of asymptotic types is elaborated. It appears as coordinate-free version of part of GOHBERG-SIGAL's theory of the inversion of finitely meromorphic, operator-valued functions at a point.},
  language  = {en}
}
@unpublished{Witt2002,
  author    = {Witt, Ingo},
  title     = {A calculus for a class of finitely degenerate pseudodifferential operators},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26246},
  year      = {2002},
  abstract  = {For a class of degenerate pseudodifferential operators, local parametrices are constructed. This is done in the framework of a pseudodifferential calculus upon adding conditions of trace and potential type, respectively, along the boundary on which the operators degenerate.},
  language  = {en}
}
@unpublished{Witt2001,
  author    = {Witt, Ingo},
  title     = {Asymptotic algebras},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26069},
  year      = {2001},
  abstract  = {The concept of asymptotic type that primarily appears in singular and asymptotic analysis is developed. Especially, asymptotic algebras are introduced.},
  language  = {en}
}
@unpublished{Witt1999,
  author    = {Witt, Ingo},
  title     = {On the factorization of meromorphic Mellin symbols},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-25427},
  year      = {1999},
  abstract  = {It is prooved that mermorphic, parameter-dependet elliptic Mellin symbols can be factorized in a particular way. The proof depends on the availability of logarithms of pseudodifferential operators. As a byproduct, we obtain a characterization of the group generated by pseudodifferential operators admitting a logarithm. The factorization has applications to the theory os pseudodifferential operators on spaces with conical singularities, e.g., to the index theory and the construction of various sub-calculi of the cone calculus.},
  language  = {en}
}
@unpublished{WittNeimanKurths1997,
  author    = {Witt, Annette and Neiman, Alexander and Kurths, J{\"u}rgen},
  title     = {Characterizing the dynamics of stochastic bistable systems by measures of complexity},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14556},
  year      = {1997},
  abstract  = {The dynamics of noisy bistable systems is analyzed by means of Lyapunov exponents and measures of complexity. We consider both the classical Kramers problem with additive white noise and the case when the barrier fluctuates due to additional external colored noise. In case of additive noise we calculate the Lyapunov exponents and all measures of complexity analytically as functions of the noise intensity resp. the mean escape time. For the problem of fluctuating barrier the usual description of the dynamics with the mean escape time is not sufficient. The application of the concept of measures of complexity allows to describe the structures of motion in more detail. Most complexity measures sign the value of correlation time at which the phenomenon of resonant activation occurs with an extremum.},
  language  = {en}
}
@unpublished{WenyiTianbo2005,
  author    = {Wenyi, Chen and Tianbo, Wang},
  title     = {The hypoellipticity of differential forms on closed manifolds},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-29803},
  year      = {2005},
  abstract  = {In this paper we consider the hypo-ellipticity of differential forms on a closed manifold.The main results show that there are some topological obstruct for the existence of the differential forms with hypoellipticity.},
  language  = {de}
}
@unpublished{VossKurthsSchwarz1996,
  author    = {Voss, Henning and Kurths, J{\"u}rgen and Schwarz, Udo},
  title     = {Reconstruction of grand minima of solar activity from Delta 14 C data : linear and nonlinear signal analysis},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14083},
  year      = {1996},
  abstract  = {Using a special technique of data analysis, we have found out 34 grand minima of solar activity obtained from a 7,700 years long Δ14C record. The method used rests on a proper filtering of the Δ14C record and the extrapolation of verifiable results for the later history back in time. Additionally, we use a method of nonlinear dynamics, the recurrence rate, to back up the results. Our findings are not contradictory to the record of solar maxima resp. minima by Eddy [5], but constitute a considerable extension. Hence, it has become possible to look closer at the validity of models. This way, we have tested several models for solar activity, esp. the model of Barnes et al. [1]. There are hints for that the grand minima might solely be driven by the 209 year period found in the Δ14C record.},
  language  = {en}
}
@unpublished{VolosevichMeister1998,
  author    = {Volosevich, Alexandra V. and Meister, Claudia-Veronika},
  title     = {Nonlinear interaction of Farley-Buneman waves},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14851},
  year      = {1998},
  abstract  = {The nonlinear interaction of waves excited by the modified two-stream instability (Farley-Buneman instability) is considered. It is found that, during the linear stage of wave growth, the enhanced pressure of the high-frequency part of the waves locally generates a ponderomotive force. This force acts on the plasma particles and redistributes them. Thus an additional electrostatic polarization field occurs, which influences the low-frequency part of the waves. Then, the low-frequency waves also cause a redistribution of the high-frequency waves. In the paper, a self-consistent system of equations is obtained, which describes the nonlinear interaction of the waves. It is shown that the considered mechanism of wave interaction causes a nonlinear stabilization of the high-frequency waves' growth and a formation of local density structures of the charged particles. The density modifications of the charged particles during the non-linear stage of wave growth and the possible interval of aspect angles of the high-frequency waves are estimated.},
  language  = {en}
}