Online state and input force estimation for multibody models employing extended Kalman filtering

This paper discusses the use of Subsystem Global Modal Parameterization (SS-GMP) reduced multibody models in an augmented discrete extended Kalman filter (A-DEKF) to generate a general formalism for online coupled state/input estimation in mechanisms. The SS-GMP approach is proposed to reduce a general multibody model of a mechanical system into a real-time capable model without considerable loss in accuracy. In order to use these reduced models with an extended Kalman filter, the necessary derivatives of this model are provided. An exponential integration scheme is used to discretize the model in order to be compatible with discrete time filters. Finally, the augmented approach is used for the estimation, in which the unknown external forces are considered as additional states to be estimated. The proposed approach is validated numerically and compared to three other filtering approaches. The validation demonstrates that the proposed approach provides accurate results while still maintaining real-time performance.     

Response to Heethoff,Norton, and Raspotnig: Ant and Mite Diversity Drives Toxin Variation in the Little Devil Poison Frog and Erratum

Our recent publication titled “Ant and Mite Diversity Drives Toxin Variation in the Little Devil Poison Frog” aimed to describe how variation in diet contributes to population differences in toxin profiles of poison frogs. Some poison frogs (Family Dendrobatidae) sequester alkaloid toxins from their arthropod diet, which is composed mainly of ants and mites. Our publication demonstrated that arthropods from the stomach contents of three different frog populations were diverse in both chemistry and species composition. To make progress towards understanding this trophic relationship, our main goal was to identify alkaloids that are found in either ants or mites. With the remaining samples that were not used for chemical analysis, we attempted to identify the arthropods using DNA barcoding of cytochrome oxidase 1 (CO1). The critique of Heethoff, Norton, and Raspotnig refers to the genetic analysis of a small number of mites. Here, we respond to the general argument of the critique as well as other minor issues detailed by Heethoff, Norton, and Raspotnig.     

Charakterisierung zweier Karstsysteme mithilfe organischer Spurenstoffe

In the presented work the occurrence of organic micro-pollutants is discussed for two karst areas with different geological characteristics and land-use patterns. Within an urban moderately karstified catchment with a large number of local input sources (e.g. contaminated sites, sewer leakages), a greater variety of micro-pollutants is found compared to a rural area. Mostly the concentrations of these compounds decrease below quantification limits before emerging at the spring and can therefore only be detected by a comprehensive network of sampling points. Springs show the presence of micro-pollutants, either recently applied in large amounts or characterized by high persistence. At the outlet of a highly karstified and consequently highly permeable aquifer readily biodegradable compounds are detected. Due to high groundwater flow velocities investigations of micro-pollutants require a highly resolved monitoring. Therefore, beside substance properties, also hydrogeological characteristics affect the spectrum of detectable micro-pollutants.     

Impact of Different Parameters for Pulsed‐Laser Welding of the Austenitic Stainless Steel 304

For welding of delicate apparatuses made of thin sheet material, the distortion is strongly governed by the heat input. Parameter variations for pulsed‐laser welding were performed to study the influence of the energy input per unit length and per time as well as the impact of the pulse width and other parameters on the weld seam geometry. Even for a constant energy input per unit length, deviations of the cross section of the weld seam were observed due to different dissipation of the deposited energy. For the same energy input per unit length the geometry of the weld seam is strongly influenced by the pulse width. Also deviations from expected behavior were found and could be explained, e.g., by a shortfall in energy density to melt the material.     

Potential of Proapoptotic Peptides to Induce the Formation of Giant Plasma Membrane Vesicles with Lipid Domains

We have established a method of preparing giant plasma membrane vesicles (GPMVs) by using cysteine mutants of the proapoptotic peptide (PAP) Ac‐R7‐GG‐KLAKLAKKLAKLAK. A cysteine scan revealed that cytotoxicity and GPMV formation were dependent on the cysteine position within the PAP sequence. In comparison to GPMVs prepared by extensive treatment with paraformaldehyde (PFA) and dithiothreitol (DTT), our GPMVs were produced from HeLa cells at much lower concentrations of the blebbing agent. We found that only GPMVs derived from cysteine‐containing PAP showed lipid phase separation. This membrane model was applied to investigate the phase partitioning of two relevant membrane proteins: influenza virus hemagglutinin (HA) and tetherin, which clamps budding HIV to infected cells. For tetherin, we show for the first time exclusion from cholesterol‐rich domains in a GPMV model, thus documenting the potential of our approach for membrane‐partitioning studies.     

Catalytic hydrodeoxygenation of dehydrated liquid phase pyrolysis oil

Biomass has been considered as promising energy source that should be able to suffice the increasing energy demand in the future. Therefore, new biomass utilization technologies and concepts are highly desirable. This paper contributes to the understanding of liquid phase pyrolysis oil upgrading that differs from the intensively investigated fast pyrolysis oil. Two new approaches, which were never reported in literature before, where investigated in this paper. At first, the liquid phase pyrolysis oil was dehydrated to lower transportation costs and increase energy density and efficiency of further upgrading steps. At second, a catalyst screening for hydrodeoxygenation (HDO) of dehydrated liquid phase pyrolysis oil was conducted in a batch reactor. Neither the dehydration nor the HDO of dehydrated liquid phase pyrolysis oil were reported in literature by now. The activity of the HDO catalysts Ru/C, Pt/C, and Pd/C as well as a Ni‐based catalyst was compared. HDO was investigated at 250 °C and 100 bar and at 300 °C and 150 bar. HDO of dehydrated liquid phase pyrolysis oil was observed with all catalysts. The Pt/C catalyst was found to be most promising with respect to the oil yield (56 wt.%), the deoxygenation ratio (65%), and hydrogen content (8.6 wt.%). Copyright © 2014 John Wiley & Sons, Ltd.     

Influence of high-pressure on cononsolvency of poly(N-isopropylacrylamide) nanogels in water/methanol mixtures

We show that the temperature-induced collapse of poly(N-isopropylacrylamide) (PNiPAm) nanogels in water/methanol mixtures can be reversed by excess hydrostatic pressure. Small angle X-ray scattering (SAXS) results reveal that first a swollen surface layer is established and then the particles swell homogeneously. A threshold pressure needed for rewelling fully collapsed nanogels indicates that hydrophobic interactions inside the nanogel have to be compensated to form a swollen surface layer. The size change is related to a change in polymer solvation detected by infrared (IR) spectroscopy. Pressure favours polymer/water hydrogen bonds to the cost of methanol/polymer bonds so that water is enriched inside the nanogel.