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Study to compare different transmission procedures in the context of a robotic telemanipulation system
No full textData transmission frequency and latency are crucial for haptic transparency in a robotic telemanipulation system. In this work, the different data transmission methods available for the ESP32 microcontroller are tested and compared to determine the most suitable data transmission method for a real-time telemanipulation system. This system consists of two mechanically decoupled collaborative robots with a tool detecting surface vibration. Two accelerometers connected to the ESP32 measure the vibration of both, the robots and the impact on the surface. The vibrations are then sent to a Robot-Operating-system (ROS) server. Two tests are performed: frequency measurement and latency measurement, with varying data buffer lengths. The results of the tests are then compared to determine a method to use that satisfies the system frequency and latency requirements. Most of the buffered methods satisfy the frequency requirement of the system, but only the wired transmission methods satisfy the latency requirement
A new computational method for the fluid-structure interaction in random nonlinear ocean waves
No full textAn efficient computation of the fluid-structure interaction (FSI) between mechanical structures and ocean waves is an important topic in many ocean engineering and naval architecture applications. However, the numerical computation of the FSI is often very expensive. In this work, a new method is developed to calculate the FSI in random nonlinear ocean waves more efficiently. The corresponding approach is based on the nonlinear Schrödinger equation, which can be solved numerically efficiently. The new method to calculate the FSI in random nonlinear ocean waves is investigated concerning its application areas, accuracy, stability, and computational efficiency.Eine effiziente Berechnung der Fluid-Struktur-Interaktion (FSI) zwischen mechanischen Strukturen und Meereswellen ist für viele meerestechnische Anwendungen interessant. Allerdings ist die numerische Berechnung der FSI oft sehr rechenaufwändig. In dieser Arbeit wird eine neue Methode entwickelt, um die FSI in zufälligen nichtlinearen Meereswellen effizienter zu berechnen. Der entsprechende Ansatz basiert auf der nichtlinearen Schrödinger-Gleichung, die numerisch effizient gelöst werden kann. Die neue Methode zur Berechnung der FSI in zufälligen nichtlinearen Meereswellen wird hinsichtlich ihrer Anwendungsbereiche, Genauigkeit, Stabilität und Recheneffizienz untersucht
A novel method for carbon fiber reinforced thermoplastics production combining single point incremental forming and 3D printing
No full textDieless processes such as additive manufacturing or incremental sheet forming are becoming increasingly popular in manufacturing carbon fiberreinforced components. They are a promising option for producing individual parts or small lot sizes without the need for expensive molds and can thus revolutionize the creation of patient-tailored prosthetics or high-end sports equipment. In this paper, the combination of robotic singlepoint incremental forming of carbon fiber-reinforced organo sheets with carbon fiber-reinforced 3D printing is presented. Combining those dieless processes in a novel process chain, complex parts with different geometric features could be produced without the need for adhesives or fasteners. The developed method begins with designing the desired component in CAD and its division into sections to be formed incrementally and sections to be 3D printed. For incremental forming, an organo sheet is cut to the necessary shape, sandwiched between a layup of dummy metal sheets, fixed on a clamping frame, and heated to the required forming temperature. Path planning for the robot is carried out based on a selected forming strategy, and the sheet is formed. Afterward, the part is transferred and fixed onto a robotic experimental 3D printing setup. The part\x92s surface is 3D-scanned to provide the basis for the path planning algorithm. The slicer software generates non-planar layers based on the actual shape of the formed sheet and the desired geometry of the printed part section. After slicing, the code for the robot is generated and the print job is executed. Within this paper, the conceptualized process chain is presented and basic functionality is proven by manufacturing a demonstration part. The first results are promising to enable efficient manufacturing of complex components that combine different geometric features in small batch sizes. Future research will be conducted to analyze and optimize the process chain and its capabilities, especially regarding the resulting part quality.Bundesministerium für Wirtschaft und Klimaschutz (BMWK
An intelligent versatile pipeline for 6D localization of industrial components in a production environment
No full textIntegrating rainwater harvesting and organic soil amendment to enhance crop yield and soil nutrients in agroforestry
No full textMore than 90% of rainfed croplands in Sub-Saharan Africa (SSA) are severely affected by highly intermittent rainfall and frequent drought limiting crop productivity in the region. Besides, 27.1% of the population in SSA are currently food insecure and this is likely to increase with the current rapid population growth in the region. Soil erosion and water scarcity remain to be the core problem affecting agricultural productivity of smallholder farming. In the current study, we analysed rainwater harvesting assisted small-scale agroforestry system in order to mitigate both soil erosion and water scarcity issues simultaneously. The system included in-situ rainwater harvesting, soil organic amendment (raw poultry litter, poultry litter biochar, wood ash) and an agroforestry system (AFS) containing maize, barley- Eucalyptus globulus all intercropped in a holistic approach. The effect was evaluated on selected soil parameters and crop yield in a field experiment on a completely randomized design. The treatments were poultry litter (PWAFS), poultry litter biochar (BWAFS) wood ash (AWAFS) with supplementary irrigation (WAFS) and agroforestry system AFS (control). The first three treatments contained poultry litter, poultry litter biochar and wood ash along with rainwater harvesting respectively while the fourth treatment contained only rainwater harvesting. Besides, a control plot-AFS was assigned with neither rainwater harvesting nor soil organic resources. The result indicated that BWAFS increased the pH by 19.4% followed by AWAFS and PWAFS (9%). Maximum and minimum SOM (2.26%, 1.21%) were observed under BWAFS and the control (AFS) respectively. BWAFS significantly increased Av.P by 78.1% while WAFS increased by 40% compared to the control. Similarly, BWAFS and PWAFS had significant effect on maize yield with increase by 74% and 36% respectively. The study concluded that integrating rainwater harvesting and soil amendment with agroforestry systems can enhance crop yield and soil nutrient levels. Therefore, such agricultural practices should be adopted by smallholder farmers in areas with limited water and nutrients levels
Conceptual structure and thematic evolution in partial least squares structural equation modeling research
No full textStructural equation modeling (SEM) using partial least squares (PLS) has received considerable attention in recent years. We address the increasing fragmentation of PLS-SEM-related research across multiple fields of scientific inquiry by presenting a bibliometric analysis’s results of n = 9,150 documents from the Web of Science database. We identify the main themes by using bibliometric content analysis to explore the PLS-SEM knowledge structure’s definition, its main drivers, and the interplay between the methodology and the application themes over time. Furthermore, we document the dynamics of the PLS-SEM knowledge structure over four periods spanning 1995–2022, unveiling a surge in scientific production and connections among thematic areas due to topic evolution and hybridization. Finally, we investigate the driving forces behind these trends and the relationship between methodology and application themes, providing an integrative view and insights into PLS-SEM research across disciplines
Maximal mouth opening in infants and toddlers with spinal muscular atrophy: a prospective controlled study
No full textBackground: Bulbar function is frequently impaired in patients with spinal muscular atrophy (SMA). Although extremely important for the patient’s quality of life, it is difficult to address therapeutically. Due to bulbar dysfunction, maximum mouth opening (MMO) is suspected to be reduced in children with SMA. However, no published MMO values exist for SMA children younger than 24 months. This study presents a novel approach to measuring MMO in infants and toddlers with SMA and compares it with healthy controls. Methods: Children with SMA (0–24 months) who received disease-modifying therapy at a single neuropediatric center and similarly aged healthy children were prospectively recruited. MMO was measured using a cardboard scale and a custom-designed instrument. Results: A total of 115 children were included (SMA = 24, healthy controls = 91). Inter-rater reliability between two examiners was excellent (ICC = 0.987, 95% CI 0.959 to 0.995), as was the reliability between the cardboard scale and the custom-designed instrument (ICC = 0.986, 95% CI 0.968 to 0.994). A mixed linear model showed a significant increase of MMO with age, and a significantly wider mouth opening in healthy controls (p <.001). Conclusion: For future research, MMO can provide valuable information about the involvement of cranial nerves, particularly in the context of disease-modifying therapies, even at a very early age
Synthetic data generation procedures for domain-specific environments in manufacturing
No full textSynthetic data is being used lately for training deep neural networks in computer vision applications such as object detection, object segmentation and 6D object pose estimation. Domain randomization hereby plays an important role in reducing the simulation to reality gap. However, this generalization might not always be effective in specialized domains like manufacturing that involve complex assemblies. Individual parts are integrated in much larger assemblies making them indistinguishable from their counterparts. Moreover, individual parts are often partially occluded in the scene. These situations give rise to wrong detections. Target domain knowledge is vital in these cases and if conceived effectively while generating synthetic data, can show a considerable improvement in bridging the simulation to reality gap. This paper validates synthetic data generation procedures through practical experimentation ensuring that experiments are both comprehensive and reproducible. After combining domain randomization and domain adaptation procedures for parts and assemblies used in manufacturing the model performance improves by up to 15% than the state-of-the-art domain randomization techniques. Reducing the simulation to reality gap in this way can unlock the true potential of robot-assisted production using artificial intelligence
An asymptotic model of vibroadhesion
No full textA compliantly fixed hemispherical indenter in adhesive contact with an elastic sample firmly bonded to a rigid base is considered under the assumption that the rigid base undergoes small-amplitude high-frequency normal (vertical) oscillations. A general law of the rate-dependent JKR-type adhesion is assumed, which relates the work of adhesion to the contact front velocity. Using the Bogoliubov averaging approach in combination with the method of harmonic balance, the leading-order asymptotic model is constructed for steady-state vibrations. The effective work of adhesion is evaluated in implicit form. A quasi-static approximation for the pull-off force is derived. The case of rigid fixation of the indenter is considered in detail
Biodegradation of polyhydroxyalkanoates: current state and future prospects
No full textPolyhydroxyalkanoates (PHAs) are biobased and biodegradable polymers that offer a sustainable alternative to conventional plastics, addressing the escalating concerns over plastic pollution. While their environmental advantages are well-documented, the efficient degradation of PHAs in natural and engineered environments remains a critical component of their lifecycle. This review provides a comprehensive overview of PHA-degrading bacteria isolated from diverse ecosystems and highlights the pivotal role of PHA depolymerases in achieving PHA circularity. Microbial adaptation to diverse environmental conditions, such as extreme temperatures, salinity, and pH, significantly influences enzymes properties, including the stability, activity, and substrate specificity of PHA-degrading enzymes. These adaptations often enhance enzyme, performance, enabling functionality under challenging conditions. Consequently, extremophilic microorganisms are invaluable resources for discovering and engineering robust PHA depolymerases for industrial and environmental applications. This review underscores the urgent need for further research to improve the ecological and economic sustainability of PHA waste management