Semi-smooth Newton methods for mixed FEM discretizations of higher-order for frictional, elasto-plastic two-body contact problems

International audienceIn this article a semi-smooth Newton method for frictional two-body contact problems and a solution algorithm for the resulting sequence of linear systems are presented. It is based on a mixed variational formulation of the problem and a discretization by finite elements of higher-order. General friction laws depending on the normal stresses and elasto-plastic material behavior with linear isotropic hardening are considered. Numerical results show the efficiency of the presented algorithm

Parameter Identification by Deep Learning of a Material Model for Granular Media

Classical physical modelling with associated numerical simulation (model-based), and prognostic methods based on the analysis of large amounts of data (data-driven) are the two most common methods used for the mapping of complex physical processes. In recent years, the efficient combination of these approaches has become increasingly important. Continuum mechanics in the core consists of conservation equations that -- in addition to the always necessary specification of the process conditions -- can be supplemented by phenomenological material models. The latter are an idealized image of the specific material behavior that can be determined experimentally, empirically, and based on a wealth of expert knowledge. The more complex the material, the more difficult the calibration is. This situation forms the starting point for this work's hybrid data-driven and model-based approach for mapping a complex physical process in continuum mechanics. Specifically, we use data generated from a classical physical model by the MESHFREE software to train a Principal Component Analysis-based neural network (PCA-NN) for the task of parameter identification of the material model parameters. The obtained results highlight the potential of deep-learning-based hybrid models for determining parameters, which are the key to characterizing materials occurring naturally, and their use in industrial applications (e.g. the interaction of vehicles with sand).Comment: arXiv admin note: text overlap with arXiv:2212.0313

Anwendung natürlich vorkommender Gegenspieler der Kohlmottenschildlaus (KMSL) in Kohlgemüse im kombinierten Einsatz mit Kulturschutznetzen

Ziel des Verbundvorhabens war die Erarbeitung einer kombinierten Regulierungsstrategie für die Kohlmottenschildlaus Aleyrodes proletella in Ökologischem Kohlgemüse, mit den zwei Ansatzpunkten Kulturschutznetz & natürlichen Gegenspielern. Das sofortige Abdecken von Rosenkohl mit feinmaschigem Kulturschutznetz (0,8 x 0,8mm) ab dem Verpflanzen bis Ende Oktober erzielte durchgängig 77% Befallssenkung in der Hauptbefallsphase im September. Aufdecken der Netze für mechanische Unkrautbekämpfung bildet ein kritisches Zeitfenster für Initialbefall. Verzicht auf Hacken durch Anwendung einer biologisch abbaubaren Mulchfolie brachte allerdings keinen zusätzlichen Regulationserfolg. Die unter Netz eingesetzte Schlupfwespe Encarsia tricolor und der Marienkäfer Clitostethus arcuatus wurden von der Katz Biotech AG bezogen. Stetige Qualitätskontrollen und der Erarbeitung von Kenndaten zum eingesetzten Zuchtstamm von E. tricolor ermöglichten erste erfolgreiche Anpassungen im Produktionsverfahren. Im Parzellenversuch stimmten verschiedene Dosierungsstufen von E. tricolor mit den Wiederfundraten im Feld und dem jeweiligen Parasitierungsgraden gut überein. Die anfänglich schwachen Parasitierungswerte 2007/08 ließen sich in 2009 auf bis zu 33% steigern. Letzteres Parasitierungsergebnis unter Netz war befallssenkend, mit 23% Mehrertrag (+23dt/ha) gegenüber der Vergleichsvariante. C. arcuatus erwies sich in 2007/2008 als Nutznießer hoher Schädlingsdichten mit unzureichendem Regulationspotential und wurde deshalb in 2009 nicht weiter eingesetzt. Auf Praxisflächen mit Punktfreilassungen von E. tricolor lag die Parasitierung 2008/09 um bis zu 50% höher als in der Referenz ohne Freilassung. In 2009 wurde durch zeitlich vorverlegte Erstfreilassungen eine deutliche Befallreduktion von knapp 60% erzielt. Bezüglich des Einsatzes von E. tricolor wurden wesentliche Meilensteine (Etablierungsfähigkeit, Regulierungseffekt, ertragswirksame Feldeffizienz) erfolgreich abgedeckt Es besteht aber weiterer Untersuchungsbedarf hinsichtlich des Optimierungsspielraums bei Freilassungstermin, -intervall und -menge

Evaluation of the toll-like receptor 6 Ser249Pro polymorphism in patients with asthma, atopic dermatitis and chronic obstructive pulmonary disease

BACKGROUND: For allergic disorders, the increasing prevalence over the past decade has been attributed in part to the lack of microbial burden in developed countries ('hygiene hypothesis'). Variation in genes encoding toll-like receptors (TLRs) as the receptor system for the first innate immune response to microbial stimuli has been implicated in various inflammatory diseases. We evaluated here the role of a coding variation, Ser249Pro, in the TLR6 gene in the pathogenesis of asthma, atopic dermatitis (AD) and chronic obstructive pulmonary disease (COPD). METHODS: Genotyping of the Ser249Pro polymorphism in 68 unrelated adult patients and 132 unrelated children with asthma, 185 unrelated patients with COPD, 295 unrelated individuals with AD and 212 healthy control subjects was performed by restriction enzyme digestion. RESULTS: We found a weak association of the 249Ser allele with childhood asthma (p = 0.03). Yet, significance was lost after Bonferroni correction. No association was evident for AD or COPD. CONCLUSION: Variation in TLR6 might play a role in the pathogenesis of childhood asthma

The multicenter effectiveness study of inpatient and day hospital treatment in departments of psychosomatic medicine and psychotherapy in Germany

Background: Reliable outcome data of psychosomatic inpatient and day hospital treatment with a focus on psychotherapy are important to strengthen ecological validity by assessing the reality of mental health care in the field. This study aims to evaluate the effectiveness of inpatient and day hospital treatment in German university departments of Psychosomatic Medicine and Psychotherapy in a prospective, naturalistic, multicenter design including structured assessments. Methods: Structured interviews were used to diagnose mental disorders according to ICD-10 and DSM-IV at baseline. Depression, anxiety, somatization, eating disorder and posttraumatic stress disorder (PTSD) symptoms, as well as personality functioning were assessed by means of questionnaires on admission and at discharge. Results: 2,094 patients recruited by 19 participating university hospitals consented to participation in the study. Effect sizes for each of the outcome criteria were calculated for 4–5 sub-groups per outcome domain with differing severity at baseline. Pre-post effect sizes for patients with moderate and high symptom severity at baseline ranged from d = 0.78 to d = 3.61 with symptoms of PTSD, depression, and anxiety showing the largest and somatization as well as personality functioning showing somewhat smaller effects. Conclusions: Inpatient and day hospital treatment in German university departments of Psychosomatic Medicine and Psychotherapy is effective under field conditions. Clinical trial registration: https://drks.de/search/de/trial/DRKS00016412, identifier: DRKS00016412