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This study presents a comprehensive evaluation of force sensors manufactured through conventional CNC machining, laser powder bed fusion (LPBF), and material extrusion (MEX) 3D printing methods. The study utilized a combination of finite element method (FEM) simulations, functional testing, durability assessments, and ultimate strength testing in order to assess the viability of additive manufacturing for sensing technology applications. The FEM simulations provided a preliminary framework for predictive analysis, closely aligning with experimental outcomes for LPBF and conventionally manufactured sensors. Nevertheless, discrepancies were observed in the performance of MEX-printed sensors during ultimate strength testing, necessitating the implementation of more comprehensive modeling approaches that take into account the distinctive material characteristics and failure mechanisms. Functional testing confirmed the operational capability of all sensors, thereby demonstrating their suitability for the intended application. Moreover, all sensors exhibited resilience during 50,000 cycles of cyclic testing, indicating reliability, durability, and satisfactory fatigue life performance. Notably, sensors produced via LPBF exhibited a significant increase in strength, nearly three times that of conventionally manufactured sensors. These findings suggest the potential for innovative sensor design and the expansion of their use into higher-loaded applications. Overall, while both LPBF and conventional methods demonstrated reliability and closely matched simulation predictions, further research is necessary to refine modeling approaches for MEX-printed sensors and fully unlock their potential in sensing technology applications. These findings indicate that additive manufacturing of metals may be a viable alternative for the fabrication of biomedical sensors.
Consequences of the consistent exact solution of Einstein{Cartan equation on the time dependence of Hubble parameter are discussed. The torsion leads to a space and time-dependent expansion parameter which results into nontrivial windows of Hubble parameter between diverging behavior.
Only one window shows a period of decreasing followed by increasing time dependence. Provided a known cosmological constant and the present values of Hubble and deceleration parameter this changing time can be given in the past as well as the ending time of the windows or universe. The comparison with the present experimental data allows to determine all parameters of the model.
Large-scale spatial periodic structures appear. From the metric with torsion outside matter, it is seen that torsion can feign dark matter.
The extended quasiparticle picture is adapted to non-Fermi systems by suggesting a Pad´e approximation which interpolates between the known small scattering-rate expansion and the deviation from the Fermi energy. The first two energy-weighted sum rules are shown to be fulfilled independent of the interpolating function for any selfenergy. For various models of one-dimensional Fermions scattering with impurities the quality of the Pad´e approximation for the spectral function is demonstrated and the reduced density matrix or momentum distribution is reproduced not possessing a jump at the Fermi energy. Though the two-fold expansion is necessary to realize the spectral function and reduced density, the extended quasiparticle approximation itself is sufficient for the description of transport properties due to cancellation of divergent terms under integration.
The T-matrix approximation leads to the delay time as the time two particles spend in a correlated state. This contributes to the reduced density matrix and to an additional part in the conductivity which is presented at zero and finite temperatures. Besides a localization at certain impurity concentrations, the conductivity shows a maximum at small temperatures interpreted as onset of superconducting behaviour triggered by impurities. The Tan contact reveals the same universal behaviour as known from electron-electron scattering.
Additive manufacturing (AM) has been growing continuously over the past 20 years, enabling unprecedented tailoring to the anatomy of each patient. In Europe, custom-made devices qualify for an exemption and pass a simplified approval process. New technologies, like AM, provoke questions about the adequacy of the current regulatory framework for custom-made devices. This article addresses the regulatory requirements for such devices in Europe and discusses the implications for AM. It concludes that the legal framework for custom-made devices entails uncertainties which need to be resolved to guide manufacturers through the regulatory requirements, highlighting the specific areas of focus for AM.
Additive manufacturing (AM) has continuously grown in recent decades. Enhanced quality, further development of technology, and fall in prices make AM applicable and capable for various industrial applications, also for the manufacture of medical devices. 3D printing offers the possibility for an unprecedented adaptation to the anatomy of each patient, generating medical devices on a case-by-case basis. In many jurisdictions, custom-made devices qualify for an exemption to pre-market approval standards. This regulation is called into question by new technologies, like AM. Therefore, this article compares the current regulatory requirements for custom-made devices in Europe, the United States, and Australia and discusses the impact on 3D printed devices. It concludes that not all jurisdictions have yet adjusted their regulatory framework for custom-made devices to technological advances. Remaining uncertainties must be eliminated in order to help manufacturers comply with the regulatory requirements, emphasizing key aspects of AM.
The use of computational modeling and simulation (CMS) as a tool for gaining insight into the technical performance and safety of medical devices has emerged continuously over the past years. However, to rely on information and decisions derived from model predictions, it is essential to establish model credibility for the specific context of use. Limited regulatory requirements and lack of consensus on the level of verification and validation activities required result in rare use of CMS as a source of evidence in the medical device approval process. The American Society of Mechanical Engineers (ASME) developed a risk-informed framework to establish appropriate credibility requirements of a computational model: the ASME V&V 40?2018 standard. This paper aims to outline the concepts of this standard and to demonstrate its application using an example from the orthotics field. The necessary steps to establish model credibility for a custom?made 3D printed wrist hand orthosis (WHO) are presented. It is shown that the credibility requirements of each verification and validation activity depend on model risk by applying two different contexts of use to the same computational model.
Objectives: In recent years, the European Union has revised its regulatory framework for medical devices, primarily to improve patient safety and public health. The Medical Device Regulation (MDR) is fully applicable since May 2021, strengthening the requirements for all stakeholders. As a result, many companies are facing enormous challenges. The aim of this study was to assess the impact of the MDR on the orthopaedic aids industry.
Methods: Two surveys were conducted: one shortly before the MDR became applicable (146 respondents) and a second survey almost two years later (233 respondents).
Results: Both surveys revealed that all businesses in the orthopaedic aids sector, regardless of size, have difficulty implementing the MDR. Key challenges include additional workload for technical documentation, increased resource expenditure and cost, and lack of clarity regarding the new requirements. Many companies are downsizing their product portfolio, resulting in potential supply shortages and a loss of competitive advantage and innovation for the medical device industry in Europe.
Conclusions: The full extent of the MDR’s impact on clinical practice is still unclear. However, many companies lack the necessary resources. The MDR can potentially be a bottleneck in the availability of medical devices.
The Anterior Fibers of the Superficial MCL and the ACL Restrain Anteromedial Rotatory Instability
(2023)
Ergonomie und Usability
(2016)