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Designing Buffalo League with Action Design Research:A Story-Based Positive Youth Development Program for U13 Handball Players
No full textFlying green:Representing ‘sustainable aviation fuels’ in the Danish media
Get PDFIn recent years, high hopes have been expressed in so-called ‘Sustainable Aviation Fuels’ (SAF) as a new technology to make aviation more environmentally friendly. This study examines public negotiations of SAF in Denmark, centering on how news media frame SAF, and how different actor groups are represented. We examine the negotiations of SAF from 2018-2023, when SAF entered the mediated public sphere as a new(s) topic. The analysis differentiates between three public arenas: national mainstream media, regional/local media, and trade journals devoted to energy and mobility. Drawing on a systematic sample and combining quantitative framing analysis with qualitative in-depth readings, the study findsthat political-regulative, technology, and optimistic climate frames are the most prevalent, across different public arenas. We identify a dominant discourse of climate tech governance, not least driven by the use of elite sources from business, politics, and science. These sources contribute to projecting SAF events into the future, magnifying SAF as potentially groundbreaking.In recent years, high hopes have been expressed in so-called ‘Sustainable Aviation Fuels’ (SAF) as a new technology to make aviation more environmentally friendly. This study examines public negotiations of SAF in Denmark, centering on how news media frame SAF, and how different actor groups are represented. We examine the negotiations of SAF from 2018–2023, when SAF entered the mediated public sphere as a new(s) topic. The analysis differentiates between three public arenas: national mainstream media, regional/local media, and trade journals devoted to energy and mobility. Drawing on a systematic sample and combining quantitative framing analysis with qualitative in-depth readings, the study finds that political-regulative, technology, and optimistic climate frames are the most prevalent, across different public arenas. We identify a dominant discourse of climate tech governance, not least driven by the use of elite sources from business, politics, and science. These sources contribute to projecting SAF events into the future, magnifying SAF as potentially groundbreaking
The impact of the limbal niche interactions on the self-renewal capability of limbal epithelial stem cells
Get PDFINTRODUCTION: The corneal homeostasis is maintained by limbal epithelial stem cells (LESCs), which reside in the limbal niche. This microenvironment comprises the cells, the extracellular matrix (ECM), and their interactions that balance the quiescent and proliferative states of LESCs. The stress caused by removing the cells from their niche triggers the quiescent stem cells to enter the proliferative state, which is beneficial for in vitro expansion, but reduces their self-renewal capability, making them less suitable for transplantation. Fibronectin (FN), a key ECM component, widely used in tissue engineering and scaffold structure, has been shown to preserve the self-renewal ability of LESCs in vitro. In parallel, paracrine growth factors are crucial for maintaining limbal niche homeostasis and promoting corneal epithelial regeneration. Limbal-niche-cells-conditioned media is a potential reservoir of limbal niche paracrine growth factors. However, whether utilizing fibronectin and limbal-niche-cells-conditioned media can sustain or enhance the stemness and proliferation ability of LESCs in vitro has not yet been investigated. METHODS: Primary cultures of limbal niche cells, including LESCs, limbal mesenchymal stromal cells (LMSCs), and limbal melanocytes (LM), were established from remnant human corneal transplant specimens, and human epidermal melanocytes (HEMn) were included as a negative control. The proliferation ability (doubling time) and self-renewal potential (as assessed by PEDF and HES1 gene expressions) of LESCs were evaluated after culture in LM-, LMSC-, and HEMn-conditioned media, as well as coating with 3, 5, and 8 µg/cm 2 concentrations of FN. RESULTS: Compared to the control group, the LMSC- and LM-conditioned media showed a clear trend towards upregulated PEDF and HES1 gene expressions. FN coating generally upregulated the expression of PEDF and HES1 genes, with this effect being most prominent at 3 µg/cm 2. CONCLUSION: These findings illustrate the potential of utilizing niche-cell-conditioned media and direct contact with FN on the self-renewal of LESCs in vitro. Further research is required to provide a more comprehensive understanding of these effects and to elucidate the underlying mechanisms of action. </p
Climate adaptation in northern communities: The value of framing, flexibility, and knowledge
No full textUdbygningsaftaler: Klimatilpasning på papir – men ikke i praksis
Get PDFEn analyse af Planlovens § 21 b’s anvendelse viser, at udbygningsaftaler kun yderst sjældent bruges til klimatilpasning til trods for lovændringer i 2023 og politiske ambitioner. Hvorfor tøver kommunerne, og hvad skal der til for at ændre det
Biological visual-cognition-inspired deep network for short-term significant wave height prediction
No full textAccurate prediction of Significant Wave Height (SWH) is essential to optimize wave energy conversion efficiency. However, ocean waves' stochastic and nonlinear characteristics make traditional models face the challenges of insufficient accuracy and limited interpretability. In this paper, we propose a deep network based on a biological visual cognitive mechanism, which significantly improves the short-term SWH prediction performance inspired by the functional principles of the human visual system's hierarchical perception, hemispheric collaboration and attentional decision-making mechanism. The model consists of three components: (1) a visual-spatial pyramid component, which gradually extracts local to global features through a multi-scale convolutional kernel; (2) a brain analysis component, which combines gated recurrent unit (GRU) and convolutional neural network (CNN) to capture spatiotemporal dependencies and enhance the stability through residual connectivity, respectively; and (3) an attention-driven prediction component, which dynamically filters the key features to improve the prediction accuracy. Experiments based on two real-world buoy sites show that the proposed method reduces the mean absolute percentage error (MAPE) to 5.56 % and 6.30 %, respectively. The energy capture error (ΔP) is reduced to 10.93 % and 13.02 %, respectively, and remains robust under extreme sea states. This work can effectively improve the prediction accuracy and operational reliability of industrial ocean energy systems under complex ocean conditions.</p
A Novel Single-phase Common-ground Rectifier with Active Power Decoupling for DC Microgrids
No full textTo suppress the leakage current in non-isolated rectifiers and reduce DC-link capacitance, this paper proposes a novel single-phase common-ground rectifier with active power decoupling as the interface between an AC power supply system and a DC load. Leakage current is minimized by connecting the ground on the AC side to the negative terminal on the DC side. By transferring dual-frequency power fluctuations to decoupling capacitors without any additional switches, the DC-link capacitance is significantly reduced, thereby decreasing the size of the rectifier. The topology derivation and the operating principle is described, the voltage across the semiconductors and decoupling capacitor, state space model and constraint are analyzed respectively. The mathematical model of the proposed rectifier is built and a voltage-current dual closed-loop controller is designed to regulate the output DC voltage. The passive component parameters are also designed. The principle and performance of the proposed rectifier are demonstrated through static and dynamic experiments. A comparison with other step up and step-down rectifiers is discussed, which reveals that the proposed rectifier offers better performance in terms of higher efficiency and lower DC-side capacitance.</p
Exploring Tailored Fiber Placement in Biocomposite Modular Structures
Get PDFTailored Fiber Placement (TFP) is an advanced additive manufacturing technology in which fibers are precisely stitched onto a 2D base material to create variable-axial preforms. Sustainable biocomposites are produced by combining natural fibers with polymeric matrices, addressing the growing demand for eco-friendly materials. However, the scalability of this process remains challenging due to the limited stitching areas of TFP machines. This paper discusses the design approach and fabrication of biocomposite gyroid modules, which, through their aggregation, can overcome the limitations of the machines and address a design-for-deconstruction approach. This project demonstrates the potential of a digitally integrated design process using TFP for fabricating lightweight modular biocomposite structures.</p
DC-Link Capacitor Design for High-Speed Integrated Motor Drives Reliability and System-Level Constraints
Get PDFThe DC link capacitor is one of the important components in Integrated Motor Drives (IMDs) in terms of reliability, and power density. This paper proposes a reliabilityoriented algorithm to select the DC link capacitor used in highspeed IMDs, considering both thermal stress and system-level performance constraints. The proposed algorithm relies on an excessive thermal load caused by the motor’s high-frequency operation that contributes to heating the self-temperature of the DC link capacitor. Additionally, torque ripple-induced vibration is treated as a key system-level constraint due to its impact on mechanical integrity in high-speed applications. The thermal analysis is based on the applied mission profile, analyzing the hot-spot temperature over a mission profile, which cover a wide speed range operation. To handle the simulation time for a long mission profile, precomputed lookup tables are employed for capacitor current, copper loss, and core loss of the electrical motor. The simulation results confirm the effectiveness of the optimized capacitor selection in meeting lifetime by doing stress-strength analysis and system specifications requirements
Reliability Analysis of SiC-MOSFET-based Integrated Motor Drives for High-speed Applications
Get PDFThe lifetime of a high-speed Integrated Motor Drive (IMD) is highly dependent on its power converter, where power devices are the most prone to failures. This paper studies the reliability of SiC-MOSFET-based high-speed IMDs, highlighting its critical role in determining the overall lifetime of the system. The proposed reliability model estimates the End of Life (EoL) of power devices by analyzing the junction temperature, which is influenced by the load conditions based on the applied mission profile. The applied mission profile, which covers all operating conditions and a wide speed range, including maximum torque per ampere and field weakening strategies, is translated into the motor current and voltage. Then, the power losses of power devices and electrical motor are obtained through three-phase currents and voltages and applied to the thermal model of the IMD. In addition to the self-thermal effect of power devices, the mutual thermal effect of the electrical motor must be considered in the IMD’s thermal model. To handle a long mission profile, the average loss model is adopted instead of using a heavy simulation. The proposed reliability model can help in designing heatsink and electrical motor cooling methods, contributing to enhanced thermal management in order to meet the lifetime requirements of specific applications for IMDs