259 research outputs found
Soft Sensors for Property-Controlled Multi-Stage Press Hardening of 22MnB5
In multi-stage press hardening, the product properties are determined by the thermo-mechanical history during the sequence of heat treatment and forming steps. To measure these properties and finally to control them by feedback, two soft sensors are developed in this work. The press hardening of 22MnB5 sheet material in a progressive die, where the material is first rapidly austenitized, then pre-cooled, stretch-formed, and finally die bent, serves as the framework for the development of these sensors. To provide feedback on the temporal and spatial temperature distribution, a soft sensor based on a model derived from the Dynamic mode decomposition (DMD) is presented. The model is extended to a parametric DMD and combined with a Kalman filter to estimate the temperature (-distribution) as a function of all process-relevant control variables. The soft sensor can estimate the temperature distribution based on local thermocouple measurements with an error of less than 10 °C during the process-relevant time steps. For the online prediction of the final microstructure, an artificial neural network (ANN)-based microstructure soft sensor is developed. As part of this, a transferable framework for deriving input parameters for the ANN based on the process route in multi-stage press hardening is presented, along with a method for developing a training database using a 1-element model implemented with LS-Dyna and utilizing the material model Mat248 (PHS_BMW). The developed ANN-based microstructure soft sensor can predict the final microstructure for specific regions of the formed and hardened sheet in a time span of far less than 1 s with a maximum deviation of a phase fraction of 1.8 % to a reference simulation
Recommended from our members
Effects of Tonality, Contour, Pitch Intervals, and Hemisphere on the Representation of Melodic Information
Tonality, contour, interval, and hemisphere are important predictors of melody recognition. Using forced-choice comparisons, listeners attempted to recognize the contour and interval information for diatonic and nondiatonic melodies presented to the left or right ear. For diatonic melodies, scale was more salient than contour whereas listeners relied on contour in nondiatonic melodies
Recommended from our members
Novel integrin endocytosis motif
Integrins are heterodimeric cell-surface adhesion molecules comprising one of 18 possible α-chains and one of eight possible ÎČ-chains. They control a range of cell functions in a matrix- and ligand-specific manner. Integrins can be internalized by clathrin-mediated endocytosis (CME) through ÎČ subunit-based motifs found in all integrin heterodimers. However, whether specific integrin heterodimers can be selectively endocytosed was unknown. Here, we found that a subset of α subunits contain an evolutionarily conserved and functional YxxΊ motif directing integrins to selective internalization by the most abundant endocytic clathrin adaptor, AP2. We determined the structure of the human integrin α4-tail motif in complex with the AP2 C-ÎŒ2 subunit and confirmed the interaction by isothermal titration calorimetry. Mutagenesis of the motif impaired selective heterodimer endocytosis and attenuated integrin-mediated cell migration. We propose that integrins evolved to enable selective integrin-receptor turnover in response to changing matrix conditions.We gratefully acknowledge the following funding sources: N.d.F. FinPharma Doctoral Program, Instrumentarium Foundation, Orion Research Foundation, Liv och Halsa foundation, Finsk-Norska Medicinska Stiftelsen and the Magnus Ehrnrooth Foundation; J.I. Academy of Finland CoE, European Research Council Consolidator Grant, the Sigrid Juselius Foundation, The Finnish Heart Foundation and Finnish Cancer Organizations. DJO, AGW and TW are funded by Wellcome Trust fellowship 090909 (DJO).This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/nsmb.3161
Softsensors: key component of property control in forming technology
The constantly increasing challenges of production technology for the economic and resource-saving production of metallic workpieces require, among other things, the optimisation of existing processes. Forming technology, which is confronted with new challenges regarding the quality of the workpieces, must also organise the individual processes more efficiently and at the same time more reliably in order to be able to guarantee good workpiece quality and at the same time to be able to produce economically. One way to meet these challenges is to carry out the forming processes in closed-loop control systems using softsensors. Despite the many potential applications of softsensors in the field of forming technology, there is still no definition of the term softsensor. This publication therefore proposes a definition of the softsensor based on the definition of a sensor and the distinction from the observer, which on the one hand is intended to stimulate scientific discourse and on the other hand is also intended to form the basis for further scientific work. Based on this definition, a wide variety of highly topical application examples of various softsensors in the field of forming technology are given
SDSS J1254+0846: A Binary Quasar Caught in the Act of Merging
We present the first luminous, spatially resolved binary quasar that clearly
inhabits an ongoing galaxy merger. SDSS J125455.09+084653.9 and SDSS
J125454.87+084652.1 (SDSS J1254+0846 hereafter) are two luminous z=0.44 radio
quiet quasars, with a radial velocity difference of just 215 km/s, separated on
the sky by 21 kpc in a disturbed host galaxy merger showing obvious tidal
tails. The pair was targeted as part of a complete sample of binary quasar
candidates with small transverse separations drawn from SDSS DR6 photometry. We
present follow-up optical imaging which shows broad, symmetrical tidal arm
features spanning some 75 kpc at the quasars' redshift. Numerical modeling
suggests that the system consists of two massive disk galaxies prograde to
their mutual orbit, caught during the first passage of an active merger. This
demonstrates rapid black hole growth during the early stages of a merger
between galaxies with pre-existing bulges. Neither of the two luminous nuclei
show significant instrinsic absorption by gas or dust in our optical or X-ray
observations, illustrating that not all merging quasars will be in an obscured,
ultraluminous phase. We find that the Eddington ratio for the fainter component
B is rather normal, while for the A component L/LEdd is quite (>3sigma) high
compared to quasars of similar luminosity and redshift, possibly evidence for
strong merger-triggered accretion. More such mergers should be identifiable at
higher redshifts using binary quasars as tracers.Comment: 15 pages, 5 figures, accepted to the Astrophysical Journal for the
February 2010 - 20 v710 issue. Latest version corrects author lis
Geovisual analytics for spatial decision support: Setting the research agenda
This article summarizes the results of the workshop on Visualization, Analytics & Spatial Decision Support, which took place at the GIScience conference in September 2006. The discussions at the workshop and analysis of the state of the art have revealed a need in concerted crossâdisciplinary efforts to achieve substantial progress in supporting spaceârelated decision making. The size and complexity of realâlife problems together with their illâdefined nature call for a true synergy between the power of computational techniques and the human capabilities to analyze, envision, reason, and deliberate. Existing methods and tools are yet far from enabling this synergy. Appropriate methods can only appear as a result of a focused research based on the achievements in the fields of geovisualization and information visualization, humanâcomputer interaction, geographic information science, operations research, data mining and machine learning, decision science, cognitive science, and other disciplines. The name âGeovisual Analytics for Spatial Decision Supportâ suggested for this new research direction emphasizes the importance of visualization and interactive visual interfaces and the link with the emerging research discipline of Visual Analytics. This article, as well as the whole special issue, is meant to attract the attention of scientists with relevant expertise and interests to the major challenges requiring multidisciplinary efforts and to promote the establishment of a dedicated research community where an appropriate range of competences is combined with an appropriate breadth of thinking
Insights from the STICH trial: Change in left ventricular size after coronary artery bypass grafting with and without surgical ventricular reconstruction
ObjectiveThe present analysis of the Surgical Treatment for Ischemic Heart Failure randomized trial data examined the left ventricular volumes at baseline and 4 months after surgery to determine whether any magnitude of postoperative reduction in end-systolic volume affected survival after coronary artery bypass grafting alone compared with bypass grafting plus surgical ventricular reconstruction.MethodsOf the 1000 patients randomized, 555 underwent an operation and had a paired imaging assessment with the same modality at baseline and 4 months postoperatively. Of the remaining 455 patients, 424 either died before the 4-month study or did not have paired imaging tests and were excluded, and 21 were not considered because they had died before surgery or did not receive surgery.ResultsSurgical ventricular reconstruction resulted in improved survival compared with coronary artery bypass grafting alone when the postoperative end-systolic volume index was 70 mL/m2 or less. However, the opposite was true for patients achieving a postoperative volume index greater than 70 mL/m2. A reduction in the end-systolic volume index of 30% or more compared with baseline was an infrequent event in both treatment groups and did not produce a statistically significant survival benefit with ventricular reconstruction.ConclusionsIn patients undergoing coronary artery bypass grafting plus surgical ventricular reconstruction, a survival benefit was realized compared with bypass alone, with the achievement of a postoperative end-systolic volume index of 70 mL/m2 or less. Extensive ventricular remodeling at baseline might limit the ability of ventricular reconstruction to achieve a sufficient reduction in volume and clinical benefit
Elliptical Galaxies and Bulges of Disk Galaxies: Summary of Progress and Outstanding Issues
This is the summary chapter of a review book on galaxy bulges. Bulge
properties and formation histories are more varied than those of ellipticals. I
emphasize two advances: 1 - "Classical bulges" are observationally
indistinguishable from ellipticals, and like them, are thought to form by major
galaxy mergers. "Disky pseudobulges" are diskier and more actively star-forming
(except in S0s) than are ellipticals. Theys are products of the slow
("secular") evolution of galaxy disks: bars and other nonaxisymmetries move
disk gas toward the center, where it starbursts and builds relatively flat,
rapidly rotating components. This secular evolution is a new area of galaxy
evolution work that complements hierarchical clustering. 2 - Disks of
high-redshift galaxies are unstable to the formation of mass clumps that sink
to the center and merge - an alternative channel for the formation of classical
bulges. I review successes and unsolved problems in the formation of
bulges+ellipticals and their coevolution (or not) with supermassive black
holes. I present an observer's perspective on simulations of dark matter galaxy
formation including baryons. I review how our picture of the quenching of star
formation is becoming general and secure at redshifts z < 1. The biggest
challenge is to produce realistic bulges+ellipticals and disks that overlap
over a factor of 10**3 in mass but that differ from each other as observed over
that whole range. Second, how does hierarchical clustering make so many giant,
bulgeless galaxies in field but not cluster environments? I argue that we rely
too much on AGN and star-formation feedback to solve these challenges.Comment: 46 pages, 10 postscript figures, accepted for publication in Galactic
Bulges, ed. E. Laurikainen, R. F. Peletier, & D. A. Gadotti (New York:
Springer), in press (2015
- âŠ