Ronny Ramlau
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View article: A Geometrical Acoustics based Focusing Algorithm for Layered Media in Medical Ultrasound
A Geometrical Acoustics based Focusing Algorithm for Layered Media in Medical Ultrasound Open
Ultrasound imaging is a widely used, non-invasive diagnostic tool in modern medicine. A crucial assumption is a constant sound speed in the observed medium. For large scale sound speed variations, this assumption leads to blurred and disto…
View article: A solution method for compact linear operator equations based on the Arnoldi process
A solution method for compact linear operator equations based on the Arnoldi process Open
This paper is concerned with the solution of linear operator equations with a compact operator. These operators do not have a bounded inverse and therefore these kinds of equations have to be regularized before solution. The Arnoldi proces…
View article: Predicting Interaction Phenomena in HVOF Thermal Spraying of WC-CoCr: A Hybrid Experimental–Statistical Approach
Predicting Interaction Phenomena in HVOF Thermal Spraying of WC-CoCr: A Hybrid Experimental–Statistical Approach Open
The development of thermal spray coatings for specific industrial and scientific applications is critical, particularly in the context of sustainable and economical production. This study employs a hybrid experimental–statistical approach …
View article: Wavefront super-resolution for Adaptive Optics systems on ground-based telescopes
Wavefront super-resolution for Adaptive Optics systems on ground-based telescopes Open
In ground-based astronomy, Adaptive Optics (AO) is a pivotal technique, engineered to correct wavefront phase distortions and thereby enhance the quality of the observed images. Integral to an AO system is the wavefront sensor (WFS), which…
View article: On SCD Semismooth <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mrow/> <mml:mo>*</mml:mo> </mml:msup> </mml:mrow> </mml:math> Newton methods for the efficient minimization of Tikhonov functionals with non-smooth and non-convex penalties
On SCD Semismooth Newton methods for the efficient minimization of Tikhonov functionals with non-smooth and non-convex penalties Open
We consider the efficient numerical minimization of Tikhonov functionals with nonlinear operators and non-smooth and non-convex penalty terms, which appear for example in variational regularization. For this, we consider a new class of sub…
View article: Leveraging real-time data analysis and multiple kernel learning for manufacturing of innovative steels
Leveraging real-time data analysis and multiple kernel learning for manufacturing of innovative steels Open
The implementation of thermally sprayed components in steel manufacturing presents challenges for production and plant maintenance. While enhancing performance through specialized surface properties, these components may encounter difficul…
View article: A Practical Guide to Optimizing Industrial Thermal Spraying through Comparative Multi-Objective Optimization
A Practical Guide to Optimizing Industrial Thermal Spraying through Comparative Multi-Objective Optimization Open
Achieving both high quality and cost-efficiency are two critical yet often conflicting objectives in manufacturing and maintenance processes. Quality standards vary depending on the specific application, while cost-effectiveness remains a …
View article: Heat Conduction with Phase Change in Permafrost Modules of Vegetation Models
Heat Conduction with Phase Change in Permafrost Modules of Vegetation Models Open
We consider the problem of heat conduction with phase change, that is essential for permafrost modeling in Land Surface Models and Dynamic Global Vegetation Models. These models require minimal computational effort and an extremely robust …
View article: On SCD Semismooth$^*$ Newton methods for the efficient minimization of Tikhonov functionals with non-smooth and non-convex penalties
On SCD Semismooth$^*$ Newton methods for the efficient minimization of Tikhonov functionals with non-smooth and non-convex penalties Open
We consider the efficient numerical minimization of Tikhonov functionals with nonlinear operators and non-smooth and non-convex penalty terms, which appear for example in variational regularization. For this, we consider a new class of SCD…
View article: High fidelity adaptive mirror simulations with reduced order models
High fidelity adaptive mirror simulations with reduced order models Open
In the design process of large adaptive mirrors numerical simulations represent the first step to evaluate the system design compliance in terms of performance, stability and robustness. For the next generation of Extremely Large Telescope…
View article: Improvements on speed, stability and field of view in adaptive optics OCT for anterior retinal imaging using a pyramid wavefront sensor
Improvements on speed, stability and field of view in adaptive optics OCT for anterior retinal imaging using a pyramid wavefront sensor Open
We present improvements on the adaptive optics (AO) correction method using a pyramid wavefront sensor (P-WFS) and introduce a novel approach for closed-loop focus shifting in retinal imaging. The method’s efficacy is validated through in …
View article: Predictive modelling of critical variables for improving HVOF coating using gamma regression models
Predictive modelling of critical variables for improving HVOF coating using gamma regression models Open
Thermal spray coating is a critical process in many industries, involving the application of coatings to surfaces to enhance their functionality. This paper proposes a framework for modelling and predicting critical target variables in the…
View article: On Phase Unwrapping via Digital Wavefront Sensors
On Phase Unwrapping via Digital Wavefront Sensors Open
In this paper, we derive a new class of methods for the classic 2D phase unwrapping problem of recovering a phase function from its wrapped form. For this, we consider the wrapped phase as a wavefront aberration in an optical system, and u…
View article: Singular Value and Frame Decomposition-based Reconstruction for Atmospheric Tomography
Singular Value and Frame Decomposition-based Reconstruction for Atmospheric Tomography Open
Atmospheric tomography, the problem of reconstructing atmospheric turbulence profiles from wavefront sensor measurements, is an integral part of many adaptive optics systems used for enhancing the image quality of ground-based telescopes. …
View article: High fidelity adaptive mirror simulations with reduced order models
High fidelity adaptive mirror simulations with reduced order models Open
In the design process of large adaptive mirrors numerical simulations represent the first step to evaluate the system design compliance in terms of performance, stability and robustness. For the next generation of Extremely Large Telescope…
View article: On some analytic properties of the atmospheric tomography operator: Non-Uniqueness and reconstructability issues
On some analytic properties of the atmospheric tomography operator: Non-Uniqueness and reconstructability issues Open
In this paper, we consider the atmospheric tomography operator, which describes the effect of turbulent atmospheric layers on incoming planar wavefronts. Given wavefronts from different guide stars, measured at a telescope, the inverse pro…
View article: An Inverse Problems Approach to Pulse Wave Analysis in the Human Brain
An Inverse Problems Approach to Pulse Wave Analysis in the Human Brain Open
Cardiac pulsations in the human brain have received recent interest due to their possible role in the pathogenesis of neurodegenerative diseases. Further interest stems from their possible application as an endogenous signal source that ca…
View article: Regularization of linear inverse problems with irregular noise using embedding operators
Regularization of linear inverse problems with irregular noise using embedding operators Open
In this paper, we investigate regularization of linear inverse problems with irregular noise. In particular, we consider the case that the noise can be preprocessed by certain adjoint embedding operators. By introducing the consequent prep…
View article: Enhancing Predictive Quality in HVOF Coating Technology: A Comparative Analysis of Machine Learning Techniques
Enhancing Predictive Quality in HVOF Coating Technology: A Comparative Analysis of Machine Learning Techniques Open
This paper presents a comparative analysis of the performance of machine learning techniques for enhancing predictive quality in thermal spray coating technology, with a focus on the high velocity oxygen fuel (HVOF) process. The study aims…
View article: Predictive Modelling of Critical Variables for Improving HVOF Coating using Gamma Regression Models
Predictive Modelling of Critical Variables for Improving HVOF Coating using Gamma Regression Models Open
Thermal spray coating is a critical process in many industries, involving the application of coatings to surfaces to enhance their functionality. This paper proposes a framework for modelling and predicting critical target variables in the…
View article: VISIONS: The VISTA Star Formation Atlas -- I. Survey overview
VISIONS: The VISTA Star Formation Atlas -- I. Survey overview Open
VISIONS is an ESO public survey of five nearby (d < 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Orion. The survey was carried…
View article: Off-axis Point Spread Function Reconstruction for Single Conjugate Adaptive Optics
Off-axis Point Spread Function Reconstruction for Single Conjugate Adaptive Optics Open
Modern Giant Segmented Mirror Telescopes (GSMTs) like the Extremely Large Telescope, which is currently under construction, depend heavily on Adaptive Optics (AO) systems to correct for atmospheric distortions. However, a residual blur alw…
View article: VISIONS: the VISTA Star Formation Atlas
VISIONS: the VISTA Star Formation Atlas Open
VISIONS is an ESO public survey of five nearby ( d < 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Orion. The survey was carrie…
View article: Accelerated photosynthesis routine in LPJmL4
Accelerated photosynthesis routine in LPJmL4 Open
The increasing impacts of climate change require strategies for climate adaptation. Dynamic global vegetation models (DGVMs) are one type of multi-sectorial impact model with which the effects of multiple interacting processes in the terre…