Improvement of the wear behaviour of highly-loaded components and tools by multi-combined surface treatment

This paper introduces a novel multi-combined surface treatment consisting of the individual treatments of plasma nitriding (PN), physical vapour deposition (PVD) and electron beam hardening (EBH). Using graded surface layers produced by such a combined surface treatment, it is possible to withstand the complex load conditions incurred by components and tools. It is shown, that the treatment sequences PN+EBH+PVD and EBH+PN+PVD are suitable for improving material properties. These multi-combined surface treatments lead to a significant improvement in load-supporting capacity. Critical load values of cohesive failure measured by scratch tests are tripled when compared to the individual treatment of PVD, and increased by at least 20% in comparison to the duplex treatments of EBH+PVD or PN+PVD. The metallurgical compatibility of the single treatments is essential for the success of combined treatments. Material-specific limitations are defined, which exclude failure due to crack initiation, the occurrence of retained austenite, and tempering effects. Based on the model wear-test assembly block-on-cylinder, it was proved, that the specific wear rate of multi-combined treated specimens is reduced about 20-50% while wear of counterpart components is decreased as well. The triplex surface heat treatment introduced opens up new prospects for highly-loaded components and tools

Improvement of the wear behaviour of highly-loaded components and tools by multi-combined surface treatment

This paper introduces a novel multi-combined surface treatment consisting of the individual treatments of plasma nitriding (PN), physical vapour deposition (PVD) and electron beam hardening (EBH). Using graded surface layers produced by such a combined surface treatment, it is possible to withstand the complex load conditions incurred by components and tools. It is shown, that the treatment sequences PN+EBH+PVD and EBH+PN+PVD are suitable for improving material properties. These multi-combined surface treatments lead to a significant improvement in load-supporting capacity. Critical load values of cohesive failure measured by scratch tests are tripled when compared to the individual treatment of PVD, and increased by at least 20% in comparison to the duplex treatments of EBH+PVD or PN+PVD. The metallurgical compatibility of the single treatments is essential for the success of combined treatments. Material-specific limitations are defined, which exclude failure due to crack initiation, the occurrence of retained austenite, and tempering effects. Based on the model wear-test assembly block-on-cylinder, it was proved, that the specific wear rate of multi-combined treated specimens is reduced about 20-50% while wear of counterpart components is decreased as well. The triplex surface heat treatment introduced opens up new prospects for highly-loaded components and tools

Uncharted waters: rare and unclassified cardiomyopathies characterized on cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging (CMR) has undergone considerable technology advances in recent years, so that it is now entering into mainstream cardiac imaging practice. In particular, CMR is proving to be a valuable imaging tool in the detection, morphological assessment and functional assessment of cardiomyopathies. Although our understanding of this broad group of heart disorders continues to expand, it is an evolving group of entities, with the rarer cardiomyopathies remaining poorly understood or even unclassified. In this review, we describe the clinical and pathophysiological aspects of several of the rare/unclassified cardiomyopathies and their appearance on CMR

A Short Note About the Application of Polynomial Kernels with Fractional Degree in Support Vector Learning

. In the mid 90's a fundamental new Machine Learning approach was developed by V. N. Vapnik: The Support Vector Machine (SVM). This new method can be regarded as a very promising approach and is getting more and more attention in the fields where neural networks and decision tree methods are applied. Whilst neural networks may be considered (correctly or not) to be well understood and are in wide use, Support Vector Learning has some rough edges in theoretical details and its inherent numerical tasks prevent it from being easily applied in practice. This paper picks up a new aspect - the use of fractional degrees on polynomial kernels in the SVM - discovered in the course of an implementation of the algorithm. Fractional degrees on polynomial kernels broaden the capabilities of the SVM and offer the possibility to deal with feature spaces of infinite dimension. We introduce a method to simplify the quadratic programming problem, as the core of the SVM. 1 Introduction Well known repres..

Vergleichende Untersuchungen zum Laser- und Elektronenstrahlschweißen von konventionell und additiv gefertigtem AlSi10Mg

In den letzten Jahren haben sich für die additive Fertigung von metallischen Werkstoffen mit pulver- und drahtbasierten Schmelzverfahren Hochenergiestrahlverfahren mittels Laser- und Elektronenstrahl durchgesetzt. Dabei eröffnet die additive Herstellung z.B. durch Laser powder bed fusion (LPBF), auch als Selective Laser Melting (SLM) bekannt, vollkommen neue Designmöglichkeiten und Fertigungsstrategien. Zur wirtschaftlichen Herstellung größerer Bauteile bietet sich die Hybridbauweise unter Nutzung von Fügeverfahren, wie z.B.das LB- und EB-Schweißen, an. Der vorliegende Beitrag beschäftigt sich mit vergleichenden Untersuchungen zur Schweißbarkeit von aus Pulver additiv gefertigtem Material und der konventionellen Gusslegierung aus AlSi10Mg als Referenz. Unabhängig von der verwendeten Energiequelle (10 kW Monomode Faserlaser; 15 kW Elektronenstrahl) kam es beim pulverbasierten LPBF-Material zu einer ausgeprägten Porenbildung in den Schweißnähten, die beim Elektronenstrahlschweißen durch Nutzung einer Mehrspot-Technik reduziert werden konnte.In recent years, high-energy beam processes using lasers and electron beams have gained acceptance for the additive manufacturing of metallic materials from powder- and wire-based melting processes. Additive manufacturing, e.g. by laser powder bed fusion (LPBF), also known as selective laser melting (SLM), opens up completely new design possibilities and manufacturing strategies. For the economic production of larger components, the hybrid construction method using joining processes, such as laser (LB) and electron beam (EB) welding, is a good choice. This paper deals with comparative investigations on the weldability of powder additively manufactured material and the conventional cast alloy of AlSi10Mg as a reference. Regardless of the energy source used (10 kW monomode fibre laser; 15 kW electron beam), the powder-based LPBF material showed pronounced pore formation in the weld seams, which could be reduced in electron beam welding by using a multi-spot technique

Baroreflex activation therapy in patients with prior renal denervation

Background: Both baroreflex activation therapy (BAT) and renal denervation modulate sympathetic activity. The aim of this study was to systematically investigate whether additive modulation of autonomic nervous system by BAT lowers blood pressure (BP) in patients who still suffer from uncontrolled resistant hypertension despite prior renal denervation. Methods: From 2012 to January 2015, patients treated with BAT for uncontrolled resistant hypertension, who prior received renal denervation were consecutively analyzed in four German centers for hypertension. Analyses of office BP, 24-h ambulatory BP, central hemodynamics, parameters of renal function were performed. Results: A total of 28 patients, who underwent renal denervation at least 5 months before and still suffer from uncontrolled BP, were subsequently treated with BAT. The office SBP decreased from 182 +/- 28 to 163 +/- 27 mmHg (P= 10 mmHg) at month 6, whereas the number of prescribed antihypertensive drug classes remained unchanged (6.2 +/- 1.5 vs. 6.0 +/- 1.7, P = 0.30). Serum creatinine, estimated glomerular filtration rate and cystatin C remained stable (P = 1.00, P = 0.41 and P = 0.22, respectively), whereas albuminuria was significantly reduced by a median of -29% (P = 0.02). Central SBP (-15 +/- 24 mmHg, P = 0.047) and end systolic pressure (-14 +/- 20 mmHg, P = 0.03) were significantly reduced. Conclusion: The present data demonstrate that BAT may exert BP-lowering as well as antiproteinuric effects in patients with prior renal denervation. However, precise evaluation of BAT effects in patients with prior renal denervation will need randomized controlled trials using sham procedures