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Christian Henke

Publications and source records attributed to Christian Henke.

12 recordsLinked to original sources
arXiv2022

$Λ$CDM $\cup$ MOND

It has been demonstrated that the difference between the Renormalised Brane World (RBW) model and the Lambda Cold Dark Matter ($Λ$CDM) model occurs only at sufficiently distant times. In this paper, it is shown that for spherically symmetric situations an analog deviation between the RBW model and Newton's theory occurs at large distances. More precisely, this deviation of the RBW model is nothing other than the explanation of Milgrom's hypothesis and follows from itself. Therefore, the results of this paper explains flat rotation curves of galaxies without dark matter.

physics.gen-ph↗
arXiv2021

Standard Cosmology on the Anti-de Sitter boundary

The well-known brane world model of cosmology is an alternative to the standard model of cosmology, called ΛCDM (Lambda Cold Dark Matter) model. However, the quadratical energy density of the brane universe requires an undesirable fine tuning. The paper develops a new Anti-de Sitter (AdS) brane world model without the quadratical energy density by using a second Einstein equation, which arises canonically during a holographic renormalisation. On the AdS boundary it is demonstrated that this brane model equals an effective de Sitter ΛCDM model, whereas the brane model near the AdS boundary agrees to the ΛCDM model except the earliest times. Finally, it is shown that the coincidence problem is avoided and the cosmological constant problem, if not solved, is greatly reduced.

gr-qc↗
arXiv2020

menoci: Lightweight Extensible Web Portal enabling FAIR Data Management for Biomedical Research Projects

Background: Biomedical research projects deal with data management requirements from multiple sources like funding agencies' guidelines, publisher policies, discipline best practices, and their own users' needs. We describe functional and quality requirements based on many years of experience implementing data management for the CRC 1002 and CRC 1190. A fully equipped data management software should improve documentation of experiments and materials, enable data storage and sharing according to the FAIR Guiding Principles while maximizing usability, information security, as well as software sustainability and reusability. Results: We introduce the modular web portal software menoci for data collection, experiment documentation, data publication, sharing, and preservation in biomedical research projects. Menoci modules are based on the Drupal content management system which enables lightweight deployment and setup, and creates the possibility to combine research data management with a customisable project home page or collaboration platform. Conclusions: Management of research data and digital research artefacts is transforming from individual researcher or groups best practices towards project- or organisation-wide service infrastructures. To enable and support this structural transformation process, a vital ecosystem of open source software tools is needed. Menoci is a contribution to this ecosystem of research data management tools that is specifically designed to support biomedical research projects.

cs.DL↗
arXiv2020

Conformally-modified gravity and vacuum energy

The paper deals with a modified theory of gravity and the cosmological consequences. Instead of concerning the field equations directly, we modify a conformally-related and equivalent equation, such that a spontaneous symmetry breaking at Planck scale occurs in the trace equation. As the consequence the cosmological constant problem is solved.

physics.gen-ph↗
arXiv2020

Cosmological Inflation from the dark Universe

The present work deals with the cosmological consequences of the variable cosmological term $Λ(a)=Λ_0 + Λ_1 a^{-r} + Λ_2 a^{-s},$ where $a$ is the scale factor of the Robertson-Walker space-time. An analysis of the parameters $Λ_1,Λ_2,r,s$ and $α,$ which describes the interaction between the cosmological constant and non-relativistic matter/radiation, leads to an attractive density $ρ_{\text{dm}} \sim a^{-r}$ and a repulsive density $ρ_{\text{infl}} \sim a^{-s}.$ As already known from literature, an approach of the form $Λ(a)=Λ_0 + Λ_1 a^{-r}$ and the identification of the energy density of space-time expansion with the zero-point density can avoid the scale discrepancy of the cosmological constant problem and solve the missing mass problem of dark matter. Furthermore, this works demonstrates that the additional term $Λ_2 a^{-s}$ solves the flatness, the horizon and the magnetic-monopole problem without a hypothetical scalar field, which avoids speculations about the origin of this field. As a consequence, the imaginary time concept from Hartle and Hawking appears naturally.

physics.gen-ph↗
arXiv2019

Quantum vacuum energy in General Relativity

The paper deals with the scale discrepancy between the observed vacuum energy in cosmology and the theoretical quantum vacuum energy (cosmological constant problem). Here, we demonstrate that Einstein's equation and an analogy to particle physics leads to the first physical justification of the so-called fine-tuning problem. This fine-tuning could be automatically satisfied with the variable cosmological term $Λ(a)=Λ_0+Λ_1 a^{-(4-ε)}$, $0 < ε\ll 1,$ where $a$ is the scale factor. As a side effect of our solution of the cosmological constant problem, the dynamical part of the cosmological term generates an attractive force and solves the missing mass problem of dark matter.

physics.gen-ph↗
arXiv2018

The cosmological nature of the dark Universe

This paper deals with the cancellation mechanism, which identifies the energy density of space-time expansion in an empty universe with the zero-point energy density and avoids the scale discrepancy with the observed energy density (cosmological constant problem). Using an intrinsic degree of freedom which describes the coupling of a variable cosmological term $Λ$ with non-relativistic matter and radiation, the following consequences are demonstrated by coupling only a small contribution of $Λ$ with non-relativistic matter. First, the standard model of cosmology with a positive cosmological constant can be generalised such that the missing mass problem of dark matter is solved by an overall negative variable cosmological term. Second, the model under consideration is compatible with constraints from the standard model of particle physics. Third, an equation of state parameter of dark matter is derived which agrees with observations of rotational curves of galaxies. Moreover, the creation and annihilation process of dark matter is presented.

physics.gen-ph↗
arXiv2018

Flow noise in planar sonar applications

In this paper an investigation of flow noise in sonar applications is presented. Based on a careful identification of the dominant coupling effects, the acoustic noise at the sensor position resulting from the turbulent wall pressure fluctuations is modelled with a system of hydrodynamic, bending and acoustic waves. We describe for the first time an analytical solution of the problem which is based on a biorthogonal system which can be solved in the spectral domain without the usual simplifying assumptions. Finally, it is demonstrated that the analytical solution describes the flow noise generation and propagation mechanisms of the considered sea trials.

physics.flu-dyn↗
arXiv2015

Forecasting the direction of incoming radiation based on fusion of gyroscopic and spectroscopic data

A method is shown to estimate the position of a radioactive source by fusing the data from a sodium iodide detector and a gyroscope while panning the detector. Based on simple geometry considerations, the search motion of a detector is modelled as angular panning. Correlation of both sensor streams is shown as a predictor for the direction of the incoming radiation. The method also allows for a rough distance classification, where a distant source or a homogenous radiation field can be distinguished from a single source near to the detector.

physics.ins-det↗
arXiv2015

Separation of acoustic waves in isentropic flow perturbations

The present contribution investigates the mechanisms of sound generation and propagation in the case of highly-unsteady flows. Based on the linearisation of the isentropic Navier-Stokes equation around a new pathline-averaged base flow, it is demonstrated for the first time that flow perturbations of a non-uniform flow can be split into acoustic and vorticity modes, with the acoustic modes being independent of the vorticity modes. Therefore, we can propose this acoustic perturbation as a general definition of sound. As a consequence of the splitting result, we conclude that the present acoustic perturbation is propagated by the convective wave equation and fulfils Lighthill's acoustic analogy. Moreover, we can define the deviations of the Navier-Stokes equation from the convective wave equation as true sound sources. In contrast to other authors, no assumptions on a slowly varying or irrotational flow are necessary. Using a symmetry argument for the conservation laws, an energy conservation result and a generalisation of the sound intensity are provided.

math-ph↗
arXiv2011

Interpolation, projection and hierarchical bases in discontinuous Galerkin methods

The paper presents results on piecewise polynomial approximations of tensor product type in Sobolev-Slobodecki spaces by various interpolation and projection techniques, on error estimates for quadrature rules and projection operators based on hierarchical bases, and on inverse inequalities. The main focus is directed to applications to discrete conservation laws.

math.NA↗