LiDAR Meta Depth Completion

Depth estimation is one of the essential tasks to be addressed when creating mobile autonomous systems. While monocular depth estimation methods have improved in recent times, depth completion provides more accurate and reliable depth maps by additionally using sparse depth information from other sensors such as LiDAR. However, current methods are specifically trained for a single LiDAR sensor. As the scanning pattern differs between sensors, every new sensor would require re-training a specialized depth completion model, which is computationally inefficient and not flexible. Therefore, we propose to dynamically adapt the depth completion model to the used sensor type enabling LiDAR adaptive depth completion. Specifically, we propose a meta depth completion network that uses data patterns derived from the data to learn a task network to alter weights of the main depth completion network to solve a given depth completion task effectively. The method demonstrates a strong capability to work on multiple LiDAR scanning patterns and can also generalize to scanning patterns that are unseen during training. While using a single model, our method yields significantly better results than a non-adaptive baseline trained on different LiDAR patterns. It outperforms LiDAR-specific expert models for very sparse cases. These advantages allow flexible deployment of a single depth completion model on different sensors, which could also prove valuable to process the input of nascent LiDAR technology with adaptive instead of fixed scanning patterns.Comment: Accepted at IROS 202

Multiproxy reconstruction of oceanographic conditions in the southern epeiric Kupferschiefer Sea (Late Permian) based on redox-sensitive trace elements, molybdenum isotopes and biomarkers

The key drivers controlling the redox state of seawater and sediment pore waters in low energy environments can be inferred from redox-sensitive trace elements (RSTE), molecular biomarkers and trace metal isotopes. Here, we apply a combination these tools to the Upper Permian Kupferschiefer (T1) from the Thuringian Basin, deposited in the southern part of the semi-enclosed Kupferschiefer Sea. Enrichment patterns of the RSTEs molybdenum (Mo) and uranium (U) as well as biomarker data attest to the rapid development of euxinic conditions in basin settings during early T1 times, which became progressively less extreme during T1 deposition. The evolution of redox conditions in basinal settings, and the associated delay in the onset of euxinia at more shallow marginal sites, can be attributed to the interaction of sea-level change with basin paleogeography. Euxinia in the southern Kupferschiefer Sea did not lead to near-quantitative depletion of aqueous Mo, possibly due to short deepwater renewal times in the Thuringian Basin, low aqueous H2S concentrations, the continuous resupply of RSTE during transgression and declining burial rates of RSTEs throughout T1 times. 30 Drawdown of RSTE is, however, indicated for euxinic lagoon environments. Moreover, admixture of freshwater supplied to these lagoons by rivers strongly impacted on local seawater chemistry. The highest Mo-isotope compositions of ~1.70‰ in basin sediments allows a minimum Kupferschiefer Sea seawater composition of ~2.40‰ to be estimated. This composition is similar to the ~2.30‰ estimate for the Late Permian open ocean, and confirms a strong hydrographic connection between the epeiric Kupferschiefer Sea and the global ocean. The substantial variation in Moisotope signatures is paralleled by diagnostic shifts in biomarkers responding to oxygenation in different parts of the water column. Water column chemistry has been affected by variation in sea level, hydrodynamic restriction, riverine freshwater influx and evaporitic conditions in shallow lagoons. Elucidation of the relative role of each driving factor by a single geochemical proxy is not feasible but the complex scenario can be disentangled by a multiproxy approach

Effect of substrate pre-treatment on the low cycle fatigue performance of tungsten carbide-cobalt coated additive manufactured 316 L substrates

Numerous studies already identified that the fatigue strength of 316 L parts processed by laser beam melting (LBM) is distinctly affected by the surface integrity. Among others, surface defects as well as residual stresses are of crucial importance. Despite new findings in the field of surface engineering of laser beam melting (LBM) parts, the low cycle fatigue strength of thermally sprayed additively manufactured substrates has not been in the focus of research to date. This study aims at evaluating the effect of different pre-treatments onto 316 L substrates processed by laser beam melting (LBM) prior to the deposition of a high velocity oxy-fuel (HVOF) sprayed tungsten carbide-cobalt coating and their effect on the low cycle fatigue strength. Therefore, 316 L substrates were examined in their as-built state as well as after grit blasting with regards to the surface roughness, strain hardening effects, and residual stresses. To differentiate between topographical effects and residual stress related phenomena, stress-relieved 316 L substrates served as reference throughout the investigations. The tungsten carbide-cobalt coated and differently pre-treated 316 L substrates were mechanically tested under quasi-static and dynamic load conditions. Besides the low cycle fatigue strength, the fracture toughness as well as the fracture mechanism were identified based on fracture surface analysis

3D scanning particle tracking velocimetry

In this article, we present an experimental setup and data processing schemes for 3D scanning particle tracking velocimetry (SPTV), which expands on the classical 3D particle tracking velocimetry (PTV) through changes in the illumination, image acquisition and analysis. 3D PTV is a flexible flow measurement technique based on the processing of stereoscopic images of flow tracer particles. The technique allows obtaining Lagrangian flow information directly from measured 3D trajectories of individual particles. While for a classical PTV the entire region of interest is simultaneously illuminated and recorded, in SPTV the flow field is recorded by sequential tomographic high-speed imaging of the region of interest. The advantage of the presented method is a considerable increase in maximum feasible seeding density. Results are shown for an experiment in homogenous turbulence and compared with PTV. SPTV yielded an average 3,500 tracked particles per time step, which implies a significant enhancement of the spatial resolution for Lagrangian flow measurement

Recombinant amyloid beta-peptide production by coexpression with an affibody ligand.

BACKGROUND: Oligomeric and fibrillar aggregates of the amyloid beta-peptide (Abeta) have been implicated in the pathogenesis of Alzheimer's disease (AD). The characterization of Abeta assemblies is essential for the elucidation of the mechanisms of Abeta neurotoxicity, but requires large quantities of pure peptide. Here we describe a novel approach to the recombinant production of Abeta. The method is based on the coexpression of the affibody protein ZAbeta3, a selected affinity ligand derived from the Z domain three-helix bundle scaffold. ZAbeta3 binds to the amyloidogenic central and C-terminal part of Abeta with nanomolar affinity and consequently inhibits aggregation. RESULTS: Coexpression of ZAbeta3 affords the overexpression of both major Abeta isoforms, Abeta(1-40) and Abeta(1-42), yielding 4 or 3 mg, respectively, of pure 15N-labeled peptide per liter of culture. The method does not rely on a protein-fusion or -tag and thus does not require a cleavage reaction. The purified peptides were characterized by NMR, circular dichroism, SDS-PAGE and size exclusion chromatography, and their aggregation propensities were assessed by thioflavin T fluorescence and electron microscopy. The data coincide with those reported previously for monomeric, largely unstructured Abeta. ZAbeta3 coexpression moreover permits the recombinant production of Abeta(1-42) carrying the Arctic (E22G) mutation, which causes early onset familial AD. Abeta(1-42)E22G is obtained in predominantly monomeric form and suitable, e.g., for NMR studies. CONCLUSION: The coexpression of an engineered aggregation-inhibiting binding protein offers a novel route to the recombinant production of amyloidogenic Abeta peptides that can be advantageously employed to study the molecular basis of AD. The presented expression system is the first for which expression and purification of the aggregation-prone Arctic variant (E22G) of Abeta(1-42) is reported.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Demand for Green Fuels and Import Options for the EU

A short presention on scenario resutls of the project BENiVer and MENA Fuels on the demand for green fuels

Adhesion of HVOF-sprayed WC-Co coatings on 316L substrates processed by SLM

Different studies have been demonstrated that the surface integrity of substrate bulk materials to be coated has a significant impact on the adhesion of thermally sprayed coatings. It is known that the surface integrity of parts processed by selective laser melting (SLM) differs from those obtained from bulk materials. Although 316L stainless steel is among the most investigated material for SLM, the adhesion of thermally sprayed coatings on 316L stainless steel substrates processed by SLM has not been studied yet. This study aims at evaluating the effect of various mechanical pre-treatments onto 316L stainless steel substrates processed by SLM and their effect on the adhesion of high velocity oxy-fuel (HVOF)-sprayed WC-Co coatings. To differentiate between topographical effects and residual stress-related phenomena, a stress-relief heat treatment of the SLM substrates served as a reference throughout the investigations. The differently pre-treated SLM substrates were investigated with regard to the surface roughness and residual stresses. For the HVOF-sprayed SLM composites, Vickers interfacial indentation tests were conducted to assess the resulting coating adhesion. The findings demonstrated that the HVOF-sprayed WC-Co coatings predominantly exhibit good adhesion to the SLM 316L substrates. However, it was found that the stress state in the SLM 316L substrate surface is more likely to affect the adhesion of the WC-Co coating, while the substrate surface roughness showed a marginal effect