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Thermal Stability of Residual Stresses in Differently Deep Rolled Surface Layers of Steel SAE 1045
(2021-05-07)
The stability of compressive residual stresses generated by deep rolling plays a decisive role on the fatigue behavior of specimens and components, respectively. In this regard, deep rolling at elevated temperature has proven to be very effective in stabilizing residual stresses when fatigue analysis is conducted at ambient temperature. However, since residual stresses can be affected not only by plastic deformation but also when thermal energy is provided, it is necessary to analyze the influence of temperature and ...
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Cooling rate as a process parameter in advanced roll forming to tailor microstructure,mechanical and corrosion properties of EN AW 7075 tubes
(2022-12-14)
The effects of solution heat treatment parameters and quench media as a processing tool for tailoring microstructure, mechanical and corrosion properties in roll forming of EN AW 7075 alloy were studied. The highest yield stress and ultimate tensile strength were obtained for the specimens quenched in water, while the air-cooled specimens exhibited inferior mechanical properties. Microstructural analysis of specimens showed that except water-quenched specimens, the parts cooled/quenched in oil, in direct contact with ...
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A hitchhiker’s guide: estimates of microbial biomass and microbial gene abundance in soil
(2024-03-19)
Information on microbial biomass carbon (MBC) is crucial to assess their stocks and role for plant nutrient release in soil. Next to fumigation-extraction, molecular methods are routinely used to estimate the contribution of fungi, bacteria, and archaea to the soil microbial community. However, more information on the links between these different indices would deepen the understanding of microbial processes. The current study is based on 11 datasets, which contain MBC and MBN data obtained by fumigation-extraction ...
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Gesundheit und Studienpensum von Studierenden: Ergebnisse eines Gesundheitssurveys an der Universität Kassel
(2023-04-28)
Einleitung
Über Gesundheit und Krankheit von Studierenden ist relativ wenig bekannt und die Auswirkungen auf den Studienerfolg sind kaum erforscht. Das Ziel der Studie ist, Assoziationen zwischen dem Gesundheitszustand von Studierenden und dem absolvierten Studienpensum zu analysieren.
Methoden
Es nahmen 3330 von 23.699 immatrikulierten Studierenden der Universität Kassel an der freiwilligen Befragung („computer assisted web interviews“) im März 2022 teil. Die Rücklaufquote betrug 14,1 % unter Bedingungen der ...
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Shared digital artifacts – Co-creators as beneficiaries in microlearning development
(2023-08-11)
Continuing vocational training benefits from the employees’ ability to share individual experience and expertise with their co-workers, as these assets constitute competitive advantages for companies. IT-supported systems can facilitate processes of knowledge elicitation (e. g. as part of collaborative co-creation) to ensure retainment of preferred qualitative characteristics of the resulting knowledge artifacts and provide ample opportunities to manage and configure a growing number of such artifacts in a company’s ...
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Impact of Pea necrotic yellow dwarf virus (PNYDV) on nodulation, N₂ fixation and yield in faba bean (Vicia faba, L.)
(2022-08-09)
Pea necrotic yellow dwarf virus (PNYDV) is a novel nanovirus in Europe, affecting various grain legumes. The impact of PNYDV on nodulation, symbiotic N₂ fixation and yield parameters in faba bean (Vicia faba L.) was investigated at controlled conditions in the greenhouse (2017), on-farm in natural infection foci (2018, 2019) and in a small-scale field experiment (2020). In the latter, the standard variety ‘Fuego’ was compared with the variety ‘GL Sunrise’ in early and late infections. In addition, the analogous effects ...
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Receding-Horizon Control of Constrained Switched Systems with Neural Networks as Parametric Function Approximators
(2022-11-21)
This work studies receding-horizon control of discrete-time switched linear systems subject to polytopic constraints for the continuous states and inputs. The objective is to approximate the optimal receding-horizon control strategy for cases in which the online computation is intractable due to the necessity of solving mixed-integer quadratic programs in each discrete time instant. The proposed approach builds upon an approximated optimal finite-horizon control law in closed-loop form with guaranteed constraint ...
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Reliabilität und Validität des OPD-KJ-Konfliktfragebogens bei stationär behandelten Jugendlichen
(2021-06-15)
Mit dem OPD-KJ-Konfliktfragebogen (OPD-KJ-KF) können intrapsychische Konflikte gemäß der Operationalisierten Psychodynamischen Diagnostik im Kindes- und Jugendalter (OPD-KJ-2) einfach und zeitökonomisch erfasst werden. Der Fragebogen existiert in zwei Fassungen: als Selbstbeurteilungsinstrument für Jugendliche und als Fremdbeurteilungsinstrument für Therapeutinnen und Therapeuten. In einer Stichprobe stationär behandelter Jugendlicher wurden psychometrische Gütekriterien (interne Konsistenz, Konstruktvalidität, ...
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Characterization of charcoal and firewood ash for use in African peri-urban agriculture
(2020-03-05)
Background
Ample quantities of ashes generated from domestic biomass energy combustion in Ghanaian kitchens are currently disposed of despite their potential agricultural value. This study aimed to investigate the potential agricultural value of charcoal and firewood ashes in terms of differences in the chemical and mineralogical compositions, and to identify the suitability of aqua regia, H2SO4, vinegar and distilled water to extract plant nutrients (Ca, Mg, K, Na, and P). The chemical compositions were determined ...
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Peanut monoculture-induced decline in fertility of Andosols in Nicaragua
(2022-08-23)
Background: Andosols are generally characterized by strong resilience to degradation and high soil fertility. This may decline during long-term peanut (Arachis hypogea) monoculture, as indicated by soil chemical and biological properties. Aims: The study investigated the monoculture-induced changes in soil chemical environment as driver for the decline in soil fertility. Methods: In this on-farm study, soils from seven sites cropped with peanut monoculture for different periods between 1 and 20 years were analyzed ...