Development of a wind turbine gearbox virtual load sensor using multibody simulation and artificial neural networks

A current development trend in wind energy is characterized by the installation of wind turbines (WT) with increasing rated power output. Higher towers and larger rotor diameters increase rated power leading to an intensification of the load situation on the drive train and the main gearbox. However, current main gearbox condition monitoring systems (CMS) do not record the 6‑degree of freedom (6-DOF) input loads to the transmission as it is too expensive. Therefore, this investigation aims to present an approach to develop and validate a low-cost virtual sensor for measuring the input loads of a WT main gearbox. A prototype of the virtual sensor system was developed in a virtual environment using a multi-body simulation (MBS) model of a WT drivetrain and artificial neural network (ANN) models. Simulated wind fields according to IEC 61400‑1 covering a variety of wind speeds were generated and applied to a MBS model of a Vestas V52 wind turbine. The turbine contains a high-speed drivetrain with 4‑points bearing suspension, a common drivetrain configuration. The simulation was used to generate time-series data of the target and input parameters for the virtual sensor algorithm, an ANN model. After the ANN was trained using the time-series data collected from the MBS, the developed virtual sensor algorithm was tested by comparing the estimated 6‑DOF transmission input loads from the ANN to the simulated 6‑DOF transmission input loads from the MBS. The results show high potential for virtual sensing 6‑DOF wind turbine transmission input loads using the presented method.

     

Shedding Light on Metal‐Based Nanoparticles in Zebrafish by Computed Tomography with Micrometer Resolution

Metal‐based nanoparticles are clinically used for diagnostic and therapeutic applications. After parenteral administration, they will distribute throughout different organs. Quantification of their distribution within tissues in the 3D space, however, remains a challenge owing to the small particle diameter. In this study, synchrotron radiation‐based hard X‐ray tomography (SRμCT) in absorption and phase contrast modes is evaluated for the localization of superparamagnetic iron oxide nanoparticles (SPIONs) in soft tissues based on their electron density and X‐ray attenuation. Biodistribution of SPIONs is studied using zebrafish embryos as a vertebrate screening model. This label‐free approach gives rise to an isotropic, 3D, direct space visualization of the entire 2.5 mm‐long animal with a spatial resolution of around 2 µm. High resolution image stacks are available on a dedicated internet page ( http://zebrafish.pharma-te.ch ). X‐ray tomography is combined with physico‐chemical characterization and cellular uptake studies to confirm the safety and effectiveness of protective SPION coatings. It is demonstrated that SRμCT provides unprecedented insights into the zebrafish embryo anatomy and tissue distribution of label‐free metal oxide nanoparticles.     

Untersuchung des Einflusses von Radkörperstrukturen auf das Einsatzverhalten von Zahnrädern

Forschung im Ingenieurwesen - Die steigenden technischen und wirtschaftlichen Anforderungen an Leistungsgetriebe führen zu einem kontinuierlichen Optimierungsbedarf in der Getriebeauslegung....     

Recrystallized cube grains in an Al–Mg–Si alloy dependent on prior cold rolling

This paper reports on the experimental investigation of an industrial Al–Mg–Si alloy, which was subjected to different cold rolling reductions and subsequently solution annealed. Based on large-scale electron backscatter detection (EBSD) measurements, it provides an analysis of the area fraction, size and number density of cube grains in the fully recrystallized microstructure. The area fraction and number density of recrystallized cube grains increase continuously with increasing strain, but the cube grain size equals the average grain size independent of prior strain. The recrystallization advantage of cube grains decreases rapidly with increasing misorientation from the ideal cube component. The technological relevance of this misorientation dependence and its possible micro-mechanical origins are discussed.     

Debugging formal specifications: a practical approach using model-based diagnosis and counterstrategies

Creating a formal specification for a design is an error-prone process. At the same time, debugging incorrect specifications is difficult and time consuming. In this work, we propose a debugging method for formal specifications that does not require an implementation. We handle conflicts between a formal specification and the informal design intent using a simulation-based refinement loop, where we reduce the problem of debugging overconstrained specifications to that of debugging unrealizability. We show how model-based diagnosis can be applied to locate an error in an unrealizable specification. The diagnosis algorithm computes properties and signals that can be modified in such a way that the specification becomes realizable, thus pointing out potential error locations. In order to fix the specification, the user must understand the problem. We use counterstrategies to explain conflicts in the specification. Since counterstrategies may be large, we propose several ways to simplify them. First, we compute the counterstrategy not for the original specification but only for an unrealizable core. Second, we use a heuristic to search for a countertrace, i.e., a single input trace which necessarily leads to a specification violation. Finally, we present the countertrace or the counterstrategy as an interactive game against the user, and as a graph summarizing possible plays of this game. We introduce a user-friendly implementation of our debugging method and present experimental results for GR(1) specifications.     

Optimal arc spline approximation

We present a method for approximating a point sequence of input points by a G¹$G^1$-continuous (smooth) arc spline with the minimum number of segments while not exceeding a user-specified tolerance. Arc splines are curves composed of circular arcs and line segments (shortly: segments). For controlling the tolerance we follow a geometric approach: We consider a simple closed polygon P and two disjoint edges designated as the start s and the destination d. Then we compute a SMAP (smooth minimum arc path), i.e. a smooth arc spline running from s to d in P with the minimally possible number of segments. In this paper we focus on the mathematical characterization of possible solutions that enables a constructive approach leading to an efficient algorithm.     

Semantic enhancement for media asset management systems

The socio-economic development of the World Wide Web gathered a large momentum through Web 2.0 and currently, the Web of Data is adding a further technological driver to this. The tremendous growth of media data combined with structured (linked) data promises further opportunities for digital market places. Although the integration of media content with linked data is only beginning there are already working groups and projects addressing this issue. We show how media and existing data sets can be seamlessly integrated and thus give possibilities for an extended user experience while interacting with media content on the web. We focus on automatic semantic enhancement services that can link arbitrary and open accessible data and introduce opportunities for media annotation, fragmentation and presentation. Our use case scenario is based on the Red Bull Content Pool, a media management system for videos, images and articles about Red Bull related content covering a multitude of sports events.     

Glas- und tieftemperaturrelaxation von copolyestern der terephthalsäure

The relaxation mechanisms of linear saturated copolyesters of terephthalic acid are influenced by the chemical structure of the used aliphatic, aromatic, and cyclic diols or dicarbonic acids. The glass transition temperatures of the copolyesters are in the range from -30 to 90°C. The numerical value of T_G can be calculated by the increment method with a mean error of ±5°C. Since this method can be applied also to other polymer systems or some other physical parameters a general procedure for optimizing the increments is given. With reference to known relaxation criterions the molecular motions of the copolyesters above and below T_G are identified. The two relaxation mechanisms below T_G show a statistical distribution of the different components of acids and diols along the chain. The γ′-relaxation is caused by orientational motions of carbonyl groups and depends on the chemical structure of the neighbouring segments. On the contrary the γ″-process is not influenced by the molecular environment and is caused by hindered rotation of CH₂-groups.     

Competitive MS binding assays for dopamine D2 receptors employing spiperone as a native marker

A competitive MS binding assay employing spiperone as a native marker and a porcine striatal membrane fraction as a source for dopamine D2 receptors in a nonvolatile buffer has been established. Binding of the test compounds to the target was monitored by mass-spectrometric quantification of the nonbound marker, spiperone, in the supernatant of the binding samples obtained by centrifugation. A solid-phase extraction procedure was used for separating spiperone from ESI-MS-incompatible supernatant matrix components. Subsequently, the marker was reliably quantified by LC-ESI-MS-MS by using haloperidol as an internal standard. The affinities of the test compounds, the dopamine receptor antagonists (+)-butaclamol, chlorpromazine and (S)-sulpiride obtained from the competitive MS binding assay were verified by corresponding radioligand binding experiments with [3H]spiperone. The results of this study demonstrate that competitive MS binding assays represent a universally applicable alternative to conventional radioligand binding assays.     

The Kinetics of Droplet Sedimentation in Liquid-Liquid Extraction

Liquid-liquid extraction is a major separation process in chemical industry. Beside appropriate design of mass transfer equipment, successful design of phase separation equipment is an important issue. Therefore, the separation of liquid-liquid dispersions was investigated and modeled with kinetic approaches to gain information for settler design. A modified first-order sedimentation rate model, a first-order consecutive step rate model, and a mixed-order rate model were applied and compared to the experimental data. The advantage of kinetic modeling of the rate of sedimentation, specifically addressing the impact of viscosity and electrolyte concentration, was successfully demonstrated.