20005 research outputs found
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Einfluss der Anregungsform auf die mechanische Impedanz des menschlichen Hand-Arm-Systems
No full textIn the human-machine interface, hand-held devices can cause vibrations to be transmitted from the machine to the human hand-arm system (HAS). In order to develop products with reduced health effects on humans, the vibration transmission should be accurately recorded and modeled. The Mechanical Impedance (MI) is used in product development to describe the vibration behavior of the HAS.
The problem is that in the state of research, different types of excitations are currently used to determine the MI, with experimental parameters that are not kept constant. The contribution of the present work is to examine the influence of these different types of excitations on the MI of the human HAS, while keeping the experimental parameters, such as excitation force , grip and push force combinations, and frequency range constant. In a comparative study, a measuring handle was translatorily excited with four different types of excitations commonly used in research (single sine, multi-sine, sweep and random noise). The measurements were carried out according to a full factorial experimental plan with five subjects under varying grip and push forces. The results show a similar progression between the deterministic single sine and the stochastic sweep. The multi-sine signal is below both these curves. The random noise signal is positioned clearly below these curves. The results make it possible to compare the influence of the type of excitation on the MI of the HAS with the state of research and to set a benchmark for future studies. The curves differ significantly from one another, particularly in terms of qualitative values. When applying MI in the future, attention should be paid to the type of excitation and the amplitude height. Otherwise, significant deviations may occur in the design of products during product development. This influence should be included in existing standards.Deutsche Forschungsgemeinschaft (DFG
Self-stabilizing MIS computation in the beeping model
No full textWe consider self-stabilizing algorithms to compute a Maximal Independent Set (MIS) in the extremely weak beeping communication model. We assume that vertices have some knowledge about the topology of the network. We revisit the not self-stabilizing algorithm proposed by Jeavons, Scott, and Xu (2013), which computes an MIS in the beeping model. We enhance this algorithm to be self-stabilizing, and explore three different variants, which differ in the knowledge about the topology available to the vertices and the number of beeping channels. In the first variant, every vertex knows an upper bound on the maximum degree of the graph. For this case, we prove that the proposed self-stabilizing version maintains the same run-time as the original algorithm, i.e., it stabilizes after rounds w.h.p. on any n-vertex graph. In the second variant, each vertex only knows an upper bound on its own degree. For this case, we prove that the algorithm stabilizes after rounds on any n-vertex graph, w.h.p. In the third variant, we consider the model with two beeping channels, where every vertex knows an upper bound of the maximum degree of the nodes in the 1-hop neighborhood. We prove that this variant stabilizes w.h.p. after rounds
Untersuchung der Elektromethanogenese als eine mögliche Speichertechnologie für erneuerbare Energien
No full textDie Elektromethanogenese ist eine Technologie zur Umwandlung von Kohlenstoffdioxid in Methan. Bei der direkten Elektromethanogenese (-300 mV vs. SHE), ohne abiotisch erzeugten Wasserstoff, konnte keine wesentliche Methanproduktion gemessen werden. Bei der indirekten Elektromethanogenese (-700 mV vs. SHE), mit abiotisch erzeugtem Wasserstoff, konnte unter Verwendung von Methanococcus maripaludis eine tägliche Methanproduktion von 61 mmol/(m² d) mit einer coulombsche Effizienz von 73 % erreicht werden. Die Simulation eines Tag-Nacht-Zyklus einer Photovoltaikanlage zeigte die Flexibilität der Elektromethanogenese, die für zukünftige Speichertechnologien unerlässlich ist.Electromethanogenesis is a technology for converting carbon dioxide into methane. In the case of direct electromethanogenesis (-300 mV vs. SHE), without abiotically produced hydrogen, no significant methane production could be measured. In the case of indirect electromethanogenesis (-700 mV vs. SHE), with abiotically produced hydrogen, a daily methane production of 61 mmol/(m² d) with a coulombic efficiency of 73 % could be achieved using Methanococcus maripaludis. The simulation of a day-night cycle of a photovoltaic system demonstrated the flexibility of electromethanogenesis, which is essential for future storage technologies
Kennzahlen und Verbesserung von Produktionssystemen
No full textKennzahlen ermöglichen die objektive Bewertung und gezielte Verbesserung von Produktionssystemen, Arbeitsbereichen und gesamten Unternehmen. Ihre Funktion erstreckt sich nicht ausschließlich auf die Leistungsbewertung, sondern umfasst auch die Identifikation von Einflussfaktoren. Als objektive Maßstäbe ermöglichen sie eine fundierte Analyse und unterstützen Unternehmen bei der gezielten Verbesserung ihrer Prozesse. Folgender Beitrag veranschaulicht anhand der Kennzahlen Termintreue und Produktivität, wie eine systematische Verbesserung von Produktionssystemen erfolgen kann. Dazu werden die relevanten Kennzahlen und ihre Einflussgrößen definiert, Methoden zur Datenerhebung erläutert, Analyseansätze vorgestellt und konkrete Optimierungsmaßnahmen aufgezeigt
Towards semantically-aware few-shot 3D reconstruction
No full textAcquiring rich object-level information, including shape, texture, and geometry, serves as a fundamental building block across multiple domains. In this context, few-shot reconstruction has become a prominent research field due to the ability to achieve 3D reconstruction from a limited set of input images. By leveraging prior knowledge encoded within a trained neural network, these methods can recover unseen features beyond the information obtained from the recorded sensor data. However, current approaches either model the entire environment without emphasizing specific regions of interest or restrict the process to the target object by completley neglecting the surrounding context in a prepossessing step. One potential approach is to apply object masking in the images and then directly map semantic information from 2D to 3D through deep learning. Nevertheless, this task reflecs highly non-linear properties, and integrating semantic cues remains a significant challenge. In this work-in-progress paper, we explore a pipeline for semantically aware few-shot 3D reconstruction on real-world data
Atrial constitutive neural networks
No full textThis work presents a novel approach for characterizing the mechanical behavior of atrial tissue using constitutive neural networks. Based on experimental biaxial tensile test data of healthy human atria, we automatically discover the most appropriate constitutive material model, thereby overcoming the limitations of traditional, pre-defined models. This approach offers a new perspective
on modeling atrial mechanics and is a significant step towards improved simulation and prediction of cardiac health
Automated building inspections coupling building information modeling and behavior trees
No full textAutomated building inspections using robots are increasingly employed to enhance safety standards and optimize maintenance processes. However, robot-based inspection methods lack adaptability in inspection planning and BIM integration for context-aware navigation. This paper presents a BIM-based inspection framework, leveraging behavior trees for automated planning and execution of robot tasks. The framework extracts spatial and semantic data from BIM models to advance automated inspection. The BIM-based inspection framework is implemented using quadruped robots, and the framework is validated by performing inspection tasks in indoor office environments. The results demonstrate that coupling BIM and behavior trees improves the accuracy and reliability of automated building inspections
Must-have, or maybe not? A sensitivity-based extension to necessary condition analysis
No full textThe necessary condition analysis (NCA) has become a prominent method for identifying must-have factors required for an outcome. With increasing sample sizes, identifying such must-have factors becomes difficult as extreme responses are more likely to occur. Addressing this concern, we introduce a novel method, the NCA with an effect size sensitivity extension (NCA-ESSE), which allows researchers to better understand the sensitivity of the NCA results to extreme response patterns. We offer guidelines for the NCA-ESSE method’s use and illustrate its efficacy using a well-known job satisfaction model. By extending NCA’s capabilities to assess the sensitivity of necessary conditions, our research enhances the method’s practical utility and helps ensure the robustness and replicability of its outcomes and conclusions
Network simulation for future distributed aircraft cabin platforms
No full textThe evolution of aircraft cabin architectures necessitates scalable network concepts to support future high-bandwidth, low-latency applications such as active noise control, smart sensing, and real-time video streaming. This paper presents a network simulation framework using OMNeT++ and the INET library to evaluate novel cabin network architectures. By modeling dataflows, network protocols, and computing modules, the simulation enables early validation of key performance metrics, including network load, end-to-end latency, and switch utilization. An exemplary case study on video streaming demonstrates the trade-offs between centralized and decentralized architectures, highlighting critical factors for optimized resource allocation
The Pelvic Rosetta Classification project: an interdisciplinary proposal for a lymph node map of the pelvis in prostate cancer
No full textThe Pelvic Rosetta Classification (PRC) project aimed to develop an interdisciplinary, landmark-based pelvic lymph node map for patients with prostate cancer to improve communication between imaging specialists and urologists. Methods: After an intense development phase, we conducted 3 evaluation rounds including 19 clinical experts having consensus meetings after each evaluation round. Experts contoured lymph node areas (LNA) for 2 patients with prostate cancer. Contours were assessed qualitatively and quantitatively. The PRC was further validated by assignment of 30 prostate-specific membrane antigen PET/CT–positive lesions to LNAs. The interrater reliability was calculated using Fleiss κ. Based on the final PRC, a complete contour and a 3-dimensional model were created. Results: Eight pelvic (external iliac, cranial/caudal obturator fossa, dorsal internal iliac, vesico-prostatic pedicle, mesorectal/perirectal, presacral, preprostatic/retropubic) and 4 extrapelvic (common iliac, intercommon, sigmoid, inguinal) LNAs were defined using anatomic landmarks which are consistently recognizable on imaging and intraoperatively. Strong consensus between experts existed for smaller, well-defined LNAs (e.g., preprostatic/retropubic, mesorectal/perirectal LNAs) compared with regions with proportionally large borders (e.g., obturator fossa, vesico-prostatic pedicle LNAs). Overall, moderate agreement (κ = 0.53) was observed during validation. Discrepancies were mostly encountered for lesions adjacent to borders between LNAs. The final contour and 3-dimensional model were approved by all experts. Conclusion: The PRC project showed fair reproducibility and validity. Further external validation is needed to assess its influence on interdisciplinary communication and treatment outcomes