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FEM shakedown analysis of structures under random strength with chance constrained programming
(2022)
Direct methods, comprising limit and shakedown analysis, are a branch of computational mechanics. They play a significant role in mechanical and civil engineering design. The concept of direct methods aims to determine the ultimate load carrying capacity of structures beyond the elastic range. In practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and constraints. If strength and loading are random quantities, the shakedown analysis can be formulated as stochastic programming problem. In this paper, a method called chance constrained programming is presented, which is an effective method of stochastic programming to solve shakedown analysis problems under random conditions of strength. In this study, the loading is deterministic, and the strength is a normally or lognormally distributed variable.
Direct methods comprising limit and shakedown analysis is a branch of computational mechanics. It plays a significant role in mechanical and civil engineering design. The concept of direct method aims to determinate the ultimate load bearing capacity of structures beyond the elastic range. For practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and onstraints. If strength and loading are random quantities, the problem of shakedown analysis is considered as stochastic programming. This paper presents a method so called chance constrained programming, an effective method of stochastic programming, to solve shakedown analysis problem under random condition of strength. In this our investigation, the loading is deterministic, the strength is distributed as normal or lognormal variables.
Das Thema „Bio“ ist auf dem Markt längst zu einem Mainstream geworden und vor allem bei jüngeren Zielgruppen sehr gefragt. Umso wichtiger ist es für Bio-Marken wie ALNATURA, sich zu definieren, um neben innovativen, nachhaltigen Start-up-Marken noch aufzufallen. Aktuell ist ALNATURA vorwiegend aufgrund der hochwertigen Produkte sowie einer transparenten Kommunikation bekannt. Jedoch fehlt es den Produkten an einheitlichem Design mit Wiedererkennungswert. Diese Arbeit zeigt einen Ansatz für ein neues, zeitgemäßes Gestaltungskonzept. Im Zuge dessen wurde das Unternehmenslogo modifiziert sowie Farben, Schrift und Gestaltungsraster neu definiert. Um das neue Image der Marke bekannt zu machen, wurde zudem eine Plakatkampagne entwickelt. Das Projekt zeigt, wie sich eine Bio-Marke weg vom Öko-Image und hin zu einer modernen Lifestyle-Marke mit Relevanz entwickeln kann.
Ocean Care ist eine politisch unabhängige Non-Profit-Organisation mit Sitz in der Schweiz. Sie setzt sich seit 1989 für den Schutz von Meeressäugern und deren Lebensraum ein. Seit 2011 ist Ocean Care außerdem UN-Sonderberaterin für Fragen im Meeresschutz. Da Ocean Care die Öffentlichkeit für das Thema Meeresschutz sensibilisieren möchte und ihre Arbeit durch Spenden finanziert wird, ist ein professionelles, vertrauenerweckendes Erscheinungsbild unerlässlich. Durch ein zeitgemäßes und seriöses Design, welches sich von anderen Organisationen abhebt, kann die Zielgruppe erweitert und die Bedeutsamkeit der Arbeit hervorgehoben werden. Das neue Erscheinungsbild beruht auf der Idee, dass sich die Informationen unter der Meeresoberfläche befinden. Die Linie, die den Meeresspiegel visualisiert, dient außerdem medienübergreifend als Orientierungshilfe.
„Work Habitat“ ist eine markenorientierte Officelösung, die auf skalierbare Weise mit einem Start-up mitwächst und in Kooperation mit dem Unternehmen academa GmbH entstanden ist. Diese Brand Experience fördert Teambuilding und Identifikation mit dem Unternehmen. Sie passt sich an die Teammitglieder an, indem sie einen ganzheitlichen Blick auf das Office-System bewahrt. Ferner stellt sie eine nahtlose Verbindung digitaler und analoger Arbeitswelten dar und bietet eine einladende Umgebung verschiedener Arten zu Arbeiten an: von Deep-Focus bis zur kooperativen Zusammenarbeit und der Anregung zwangloser Begegnungen. Die modularen Komponenten können trotz Veränderungen, Umzügen oder unerwartet rasanten Entwicklungen nachhaltig und flexibel eingesetzt werden. Eine schnelllebige Welt erfordert eine angebrachte, sich ihr anpassende New-Work-Umgebung.
Virtual Reality (VR) offers novel possibilities for remote training regardless of the availability of the actual equipment, the presence of specialists, and the training locations. Research shows that training environments that adapt to users' preferences and performance can promote more effective learning. However, the observed results can hardly be traced back to specific adaptive measures but the whole new training approach. This study analyzes the effects of a combined point and leveling VR-based gamification system on assembly training targeting specific training outcomes and users' motivations. The Gamified-VR-Group with 26 subjects received the gamified training, and the Non-Gamified-VR-Group with 27 subjects received the alternative without gamified elements. Both groups conducted their VR training at least three times before assembling the actual structure. The study found that a level system that gradually increases the difficulty and error probability in VR can significantly lower real-world error rates, self-corrections, and support usages. According to our study, a high error occurrence at the highest training level reduced the Gamified-VR-Group's feeling of competence compared to the Non-Gamified-VR-Group, but at the same time also led to lower error probabilities in real-life. It is concluded that a level system with a variable task difficulty should be combined with carefully balanced positive and negative feedback messages. This way, better learning results, and an improved self-evaluation can be achieved while not causing significant impacts on the participants' feeling of competence.
Gamification applications are on the rise in the manufacturing sector to customize working scenarios, offer user-specific feedback, and provide personalized learning offerings. Commonly, different sensors are integrated into work environments to track workers’ actions. Game elements are selected according to the work task and users’ preferences. However, implementing gamified workplaces remains challenging as different data sources must be established, evaluated, and connected. Developers often require information from several areas of the companies to offer meaningful gamification strategies for their employees. Moreover, work environments and the associated support systems are usually not flexible enough to adapt to personal needs. Digital twins are one primary possibility to create a uniform data approach that can provide semantic information to gamification applications. Frequently, several digital twins have to interact with each other to provide information about the workplace, the manufacturing process, and the knowledge of the employees. This research aims to create an overview of existing digital twin approaches for digital support systems and presents a concept to use digital twins for gamified support and training systems. The concept is based upon the Reference Architecture Industry 4.0 (RAMI 4.0) and includes information about the whole life cycle of the assets. It is applied to an existing gamified training system and evaluated in the Industry 4.0 model factory by an example of a handle mounting.
Digital twins are seen as one of the key technologies of Industry 4.0. Although many research groups focus on digital twins and create meaningful outputs, the technology has not yet reached a broad application in the industry. The main reasons for this imbalance are the complexity of the topic, the lack of specialists, and the unawareness of the twin opportunities. The project "Digital Twin Academy" aims to overcome these barriers by focusing on three actions: Building a digital twin community for discussion and exchange, offering multi-stage training for various knowledge levels, and implementing realworld use cases for deeper insights and guidance. In this work, we focus on creating a flexible learning platform that allows the user to select a training path adjusted to personal knowledge and needs. Therefore, a mix of basic and advanced modules is created and expanded by individual feedback options. The usage of personas supports the selection of the appropriate modules.
Biocompatibility, flexibility and durability make polydimethylsiloxane (PDMS) membranes top candidates in biomedical applications. CellDrum technology uses large area, <10 µm thin membranes as mechanical stress sensors of thin cell layers. For this to be successful, the properties (thickness, temperature, dust, wrinkles, etc.) must be precisely controlled. The following parameters of membrane fabrication by means of the Floating-on-Water (FoW) method were investigated: (1) PDMS volume, (2) ambient temperature, (3) membrane deflection and (4) membrane mechanical compliance. Significant differences were found between all PDMS volumes and thicknesses tested (p < 0.01). They also differed from the calculated values. At room temperatures between 22 and 26 °C, significant differences in average thickness values were found, as well as a continuous decrease in thicknesses within a 4 °C temperature elevation. No correlation was found between the membrane thickness groups (between 3–4 µm) in terms of deflection and compliance. We successfully present a fabrication method for thin bio-functionalized membranes in conjunction with a four-step quality management system. The results highlight the importance of tight regulation of production parameters through quality control. The use of membranes described here could also become the basis for material testing on thin, viscous layers such as polymers, dyes and adhesives, which goes far beyond biological applications.
Advances in polymer science have significantly increased polymer applications in life sciences. We report the use of free-standing, ultra-thin polydimethylsiloxane (PDMS) membranes, called CellDrum, as cell culture substrates for an in vitro wound model. Dermal fibroblast monolayers from 28- and 88-year-old donors were cultured on CellDrums. By using stainless steel balls, circular cell-free areas were created in the cell layer (wounding). Sinusoidal strain of 1 Hz, 5% strain, was applied to membranes for 30 min in 4 sessions. The gap circumference and closure rate of un-stretched samples (controls) and stretched samples were monitored over 4 days to investigate the effects of donor age and mechanical strain on wound closure. A significant decrease in gap circumference and an increase in gap closure rate were observed in trained samples from younger donors and control samples from older donors. In contrast, a significant decrease in gap closure rate and an increase in wound circumference were observed in the trained samples from older donors. Through these results, we propose the model of a cell monolayer on stretchable CellDrums as a practical tool for wound healing research. The combination of biomechanical cell loading in conjunction with analyses such as gene/protein expression seems promising beyond the scope published here.