Fachhochschule Kärnten

This article examines the internal stability of an active clamp forward converter (ACFC) from a non‐linear system and arbitrary changes in the state variable's point of view. The analysis is based on the Lyapunov direct method in conjunction with the operating theory of the ACFC. The equivalent circuit with the state equations is established and their stability is assessed in consideration of the hard‐ and soft‐switching operations using the Lyapunov energy function approach in a piecewise manner. In addition, averaged switch modelling is applied explicitly to derive a more accurate small‐signal model of a low‐side ACFC. The study revealed the presence of a non‐minimum phase problem as the major adverse effect on the stability feature of the ACFC predesigned with soft‐switching capability. The instability of ACFC is related to the magnetising inductance (Lm${{L}_m}$) value (core loss resistance) which influences/determines the hard‐ or soft‐switching operations of the ACFC. Hardware prototype was developed with two different transformers having distinct values of Lm$\ {{L}_m}$ for hard‐ and soft‐switching operations. From the experimental frequency measurement, the model accurately predicts the movement of the complex zeros from the left‐half‐plane (LHP) to the right‐hand‐plane (RHP) as the ACFC changes from the hard‐switching to a soft‐switching operation.

The relationship between trust and distrust in public governance is still an open question. In the literature, three different perspectives on how trust and distrust are related are intensively debated: (1) trust and distrust as two ends of the same conceptual continuum; (2) trust and distrust as opposites, but with neutral ground in between; and (3) trust and distrust as related, yet distinct concepts. Employing a new measure for distrust and by using perceptual data on trust and distrust in regulatory agencies from multiple types of stakeholders in nine countries and three sectors, this article shows that high trust and high distrust can co-exist at the same time, and that trust and distrust are negatively correlated only to a limited extent. Moreover, while trustworthiness correlates strongly with trust, trustworthiness does not or only weakly correlate with distrust in a negative way. These findings are robust even when controlling for respondents' characteristics, different types of stakeholders, sectors and countries. This suggests that in public governance settings trust and distrust should be considered as distinct concepts, and the article calls for more research into the distinctiveness of the measurement, causes and effects of distrust, compared to trust.

This paper offers a critical discussion of the evolution and impact of an international nursing writing group, developed to support nursing faculty and academics globally. Amid the challenges posed by the COVID-19 pandemic, the writing group adapted and thrived online with a flattened power structure, and shared influence and acknowledgment of mutual capacity and contribution. The writing group attracted participants from various countries, with international members enriching collaboration, and fostering a global network of nursing scholars. By embracing diverse perspectives and promoting nonpatriarchal approaches to scholarly writing, the International Writing Group became a unique and valuable platform for academic growth and cross-cultural exchange in nursing.

mRNA vaccines have played a massive role during the COVID-19 pandemic and are now being developed for numerous other human and animal applications. Nevertheless, their potential ramifications on the environment lack scrutiny and regulation. On 14 July 2020, the EU decided to temporarily exclude the clinical trials with COVID-19 vaccines from prior environmental risk assessment. Even though billions of doses have been administered and large-scale agricultural and wildlife RNA applications are fast-tracked, there is no knowledge of their environmental impact via the dispersion of vaccine-derived material or their wastage. This knowledge gap is targeted here via a critical assessment of (1) the pharmacokinetic properties of these products; (2) their impact on the human microbiota; (3) novel risk factors exemplified by the human gut bacterium Escherichia coli resulting in pathogen evolution in the guts of wild animals, (4) findings on mRNA-LNP platforms that implicate extracellular vesicles (EVs) as superior carriers, and (5) potentials of exogenous regulatory RNAs. This analysis results in the first extrapolation of (a) the magnitude and likelihood of environmental risk as characterized by the FDA in 2015 for products that facilitate their action by transcription and/or translation of transferred genetic material or related processes, and (b) additional risks facilitated by the horizontal transfer of exogenous short RNAs. The arguments provided here establish the rationale for vaccine-derived bioactive material dispersed by EVs, impacted microbiota, and other exposed organisms to foster pathogen evolution, cross-species transfer of biological function, and driving widespread ecosystem disturbances. Evidence is emerging that vaccine-derived molecules, when ingested, could survive digestion and mediate gene expression regulation, host–parasite defense, immunity, and other responses in the consuming animals. Highlighting further unresolved questions, the comprehensive assessment provided here calls for open dialogue and more in-depth studies to get a clear picture in the EU and globally to most effectively gauge the environmental impact of existing and emerging human, livestock, and wildlife mRNA technologies or their potential as biological weapons or for other forms of misuse. Regulatory measures are urgently needed to mitigate potentially large-scale damage to public and ecosystem health as well as adverse societal, economic, and legal implications.

There is no unified method for deriving the tensile properties of fiber-reinforced ultra-high-performance cementitious composites (UHPCC). This study compares the most common material tests based on a large series of laboratory tests performed on a self-developed UHPCC mixture. The cementitious matrix, with a compressive strength of over 150 MPa and a matrix tensile strength of 8–10 MPa, was reinforced with 2% by volume of 15 mm long and 0.2 mm diameter straight high-strength steel microfibers. Over 100 uniaxial tensile tests were performed on three test configurations using cylindrical cores drilled out from larger prismatic specimens in three perpendicular directions. In addition to uniaxial tests, flexural tests on prismatic elements and flexural tests on thin plates were conducted, and the tensile properties were derived through digital image correlation (DIC) measurements and inverse analysis. Furthermore, splitting tensile tests on cylindrical specimens were employed to ascertain the tensile properties of the matrix. The outcomes of the diverse laboratory tests are presented and discussed in detail. The relationships between crack width and deflection in the context of flexural tests were developed and presented. In conjunction with compression tests and modulus of elasticity tests, the constitutive law is presented for the investigated materials.

Objectives : To evaluate the fracture resistance (FR) of polyetheretherketone (PEEK) abutments produced by additive and subtractive methods compared to milled zirconia abutments. Methods : Custom abutments were designed on Ti-base abutments and produced from three different materials, namely additively manufactured PEEK (PEEK-AM), subtractively manufactured PEEK (PEEK-SM), and zirconia (N=60). PEEK-AM abutments were printed using PEEK filaments (VESTAKEEP®i4 3DF-T, Evonik Industries AG) on a M150 Medical 3D Printer (ORION AM) by fused filament fabrication (FFF). All surface treatments were carried out according to the manufacturer's instructions. All abutments were cemented on Ti-bases with hybrid abutment cement and then restored with milled zirconia crowns. Each subgroup was divided into non-aged and aged subgroups (n=10). The aged groups were subjected to thermomechanical aging (49 N, 5-55°C, 1.2 million cycles). FR tests were performed by using a universal testing machine. Data were statistically analyzed with one-way and two-way ANOVA and t-test. Results : The survival rate of the specimens after aging was determined as 100%. It was found that both the material and aging had a significant effect on the FR (p<.001). There was a statistical difference among the fracture values of the groups (p<0.001). In both the aged and non-aged groups, PEEK-AM showed the statistically lowest FR, while the highest FR was seen in the zirconia group, which was significantly higher than the PEEK-SM (p<0.001). Conclusion : Hybrid abutments were successfully manufactured, and extrusion-based processed PEEK seems to be a good alternative to subtractive processed PEEK. However, since subtractive manufacturing still appears to be superior, further developments in additive manufacturing are needed to further improve the quality of 3D-printed PEEK parts, especially in terms of accuracy and bonding between adjacent layers. Clinical Significance : Additively manufactured PEEK abutments have the potential to be an alternative for implant-supported restorations in the posterior region. Keywords : Digital implantology, Filament extrusion, Generative manufacturing, High performance polymer, Implant abutments, PEEK

Soft and flexible capacitive tactile sensors are animportant tool to; accurately measure tactile forces in wearablehealth monitors and enable soft grasping in robots. Precise forcemeasurements in real-time pave the way for enhanced human-machine interaction, improved automation safety, and novelmedical diagnostics approaches. In this work, a parallel platesoft capacitive sensor array was fabricated using low-cost andscalable additive manufacturing-based methods (screenprinting and spin coating) with EMI shielding. Experimentalsetups were developed to evaluate the applied force on the soft,flexible sensor based on the ratio of mutual capacitance (RMC).The preciseness of the sensor array was tested with a normalforce testing setup using Zwick Roell’s benchtop testingmachine. Furthermore, a Robot was used to apply the normalforce on each sensor ranging between 1-15 N, and its values wererecorded using a force and torque sensor. IoT-based electronicswere used to measure the RMC from five contact pointssimultaneously and a Python script saved data over time. Thevalues of RMC were mapped to their corresponding force valuesusing linear regression algorithms. This work demonstrates thesuitability of the proposed sensor design for various applicationareas such as soft robotics and prosthetics for complex forcemeasurements in human-machine interaction scenarios.

Orthoses and prostheses (O&P) play crucial roles in assisting individuals with limb deformities or amputations. Proper material selection for these devices is imperative to ensure mechanical robustness and biocompatibility. While traditional manufacturing methods have limitations in terms of customization and reproducibility, additive manufacturing, particularly pellet extrusion (PEX), offers promising advancements. In applications involving direct contact with the skin, it is essential for materials to meet safety standards to prevent skin irritation. Hence, this study investigates the biocompatibility of different thermoplastic polymers intended for skin-contact applications manufactured through PEX. Surface morphology analysis revealed distinct characteristics among materials, with TPE-70ShA exhibiting notable irregularities. Cytotoxicity assessments using L929 fibroblasts indicated non-toxic responses for most materials, except for TPE-70ShA, highlighting the importance of material composition in biocompatibility. Our findings underscore the significance of adhering to safety standards in material selection and manufacturing processes for medical devices. While this study provides valuable insights, further research is warranted to investigate the specific effects of individual ingredients and explore additional parameters influencing material biocompatibility. Overall, healthcare practitioners must prioritize patient safety by meticulously selecting materials and adhering to regulatory standards in O&P manufacturing.

Nowadays, 3D printing is becoming an increasingly common option for the manufacturing of sensors, primarily due to its capacity to produce intricate geometric shapes. However, a significant challenge persists in integrating multiple materials during printing, for various reasons. In this study, we propose a straightforward approach that combines 3D printing with metal coating to create an array of resistive force sensors from a single material. The core concept involves printing a sensing element using a conductive material and subsequently separating it into distinct parts using metal-coated lines connected to the electrical ground. This post-printing separation process involves manual intervention utilizing a stencil and metallic spray. The primary obstacle lies in establishing a sufficient contact surface between the sprayed metal and the structure, to ensure effective isolation among different zones. To address this challenge, we suggest employing a lattice structure to augment the contact surface area. Through experimental validation, we demonstrate the feasibility of fabricating two sensing elements from a single-material 3D-printed structure, with a maximum electrical isolation ratio between the sensors of above 30. These findings hold promise for the development of a new generation of low-tech 3D-printed force/displacement sensor arrays.

This paper introduces the analysis of biographical interviews focusing on the negotiation of the day-to-day child-raising by Czech Roma mothers. We demonstrate the narrative reflection of ethnic identity, as well as coping strategies and ways out of the discursive subjugation of being marginalized by ethnic othering. We present coping strategies based on 1) vacillating between refusal and resigned acceptance of the negative discourse among the ethnic majority, 2) claiming normality through universal humanism, the submission of racialized microaggression, and the psychologizing of an aggressor, and 3) embracing family pride and social dissent. We find that primary socialization is an important element in tackling the discursive subjugation of ethnic othering. Further, we outline suggestions for the following research of othering mechanisms that seem to endure in European societies in terms of the reproduction of social inequalities. This article was published open access under a CC BY licence: https://creativecommons.org/licences/by/4.0 .

Rare bone diseases (RBD) cause physical and sensory disability that affects quality of life. Mobility challenges are common for people with RBDs, and travelling to gait analysis labs can be very complex. Smartphone sensors could provide remote monitoring. This study aimed to search for and identify variables that can be used to discriminate between people with RBD and healthy people by using built-in smartphone sensors in a real-world setting. In total, 18 participants (healthy: n=9; RBD: n=9), controlled by age and sex, were included in this cross-sectional study. A freely available App (Phyphox) was used to gather data from built-in smartphone sensors (accelerometer & gyroscope) at 60 Hz during a 15-minute walk on a level surface without turns or stops. Temporal gait parameters like cadence, mean stride time and, coefficient variance (CoVSt) and nonlinear analyses, as the largest Lyapunov exponent (LLE) & sample entropy (SE) in the three accelerometer axes were used to distinguish between the groups and describe gait patterns. The LLE (p=0.04) and the SE of the z-axis (p=0.01), which are correlated with balance control during walking and regularity of the gait, are sufficiently sensitive to distinguish between RBD and controls. The use of smartphone sensors to monitor gait in people with RBD allows for the identification of subtle changes in gait patterns, which can be used to inform assessment and management strategies in larger cohorts.

Fin ray soft robotic fingers are inspired by the structure and movement of fish fins, enabling flexible and adaptive grasping capabilities. Addressing the challenges of resource efficiency in terms of reduced energy consumption and material expense, this work focuses on further optimizing inherently low-energy fin-ray fingers towards lightweight design. Soft grippers are used frequently in dynamically changing environments and have become inevitable in handling tasks for delicate objects. However, these grippers generally show limited performance and payload-carrying capacity in high-force application scenarios. To address these limitations, topology optimization technique is used here to obtain both gripping capabilities and high factor of safety (FOS) of fingers. The performance of various structures of fin-ray and optimized fingers are analyzed: rectangular, trapezoidal, straight struts, and inclined struts for angles + 45°, − 45°. The topologically optimized structure has 15.2% less mass compared to considered fin-ray finger’s average mass. The deflection coefficient ( C d ) is calculated to select the best structure of the fingers based on grasping scenario, and its value should be minimum. The straight strut finger with thickness of t = 2 mm shows best wrapping capabilities compared to all fingers with C d = 0.1574. The topologically optimized finger’ C d = 0.1896 at volume fraction of 0.1. Even though the C d is slightly higher, its FOS is 1.71 times higher. An experimental setup is developed to validate the simulation results with the help of a UR3e robotic arm and an AXIA80 force sensor. The grasping demonstration of soft robotic gripper is performed on various objects: coffee cup and wooden block.