| 1. |
- Belov, Ilja, et al.
(författare)
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Experimental and CFD evaluation of active anti-condensation methods for non-hermetic cabinets
- 2018
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Ingår i: 2018 19th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538623596 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- Experimental evaluation of several active anti-condensation methods for application in non-hermetic electronics enclosures was performed in harsh climatic conditions, including RH = 70% and T = 43 °C. The studied methods included blowing the air along the exposed surface, combination of blowing and air heating as well as local heating of the exposed surface in natural convection conditions. The purpose was to prevent/remove the dew on/from the exposed surface of a micro-condensation sensor. The difference between the methods was quantified in terms of time for dew removal. The power consumption aspects were discussed. A CFD based optimization methodology was developed to determine the heating profiles for the local anti-condensation PCB heater in a non-hermetic cabinet exposed to the quickly changing climatic conditions. The potential for 60% energy savings was revealed by simulation.
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| 2. |
- Besharat, Zahra, et al.
(författare)
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Mixed monolayers of alkane thiols with polar terminal group on gold : Investigation of structure dependent surface properties
- 2016
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 484, s. 279-290
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Tidskriftsartikel (refereegranskat)abstract
- Adsorption of thiols with cationic or anionic terminal group on gold has been studied from mixed solutions of 11-Amino-1-undecanethiol (AUT) and 3-Mercaptopropionic acid (MPA) using Quartz Crystal Microbalance with Dissipation (QCM-D), X-ray Photoelectron Spectroscopy (XPS), atomic force microscopy (AFM) and contact angles. The goal is to probe the nature of such layers, and the additivity or otherwise of the pH responsiveness, with a view to evaluate their suitability as smart materials. For each of the two pure (unmixed) cases, ordered molecular monolayers are formed with sulfur binding to gold and the alkane chain pointing out from the surface as expected. Adsorption from the thiol mixtures, however, leads to a more complex behaviour. The surface concentration of thiols from the mixtures, as determined by QCM-D, is considerably lower than for the pure cases and it reaches a minimum at a 3:1 MPA/AUT relative concentration in the solution. The XPS results confirm a reduction in adsorbed amount in mixtures with the lowest overall intensity for the 3:1 ratio. Monolayers formed from mixtures display a wettability which is much lower and less pH sensitive. Collectively these results confirm that for adsorption from mixed systems, the configuration is completely different. Complex formation in the mixed solutions leads to the adsorption of molecules parallel to the surface in an axially in-plane configuration. This parallel layer of thiols is mechanically relatively robust to nano-shaving based on AFM measurements. These results will have a significant impact on the design of biomimetic surface coatings particularly when mixtures of oppositely charged molecules are present on the surface, as is commonly the case in biological, proteinaceous surfaces (e.g. hair and skin).
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| 3. |
- Besharat, Zahra, et al.
(författare)
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Se-C Cleavage of Hexane Selenol at Steps on Au(111)
- 2018
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 34:8, s. 2630-2636
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Tidskriftsartikel (refereegranskat)abstract
- Selenols are considered as an alternative to thiols in self-assembled monolayers, but the Se-C bond is one limiting factor for their usefulness. In this study, we address the stability of the Se-C bond by a combined experimental and theoretical investigation of gas phase-deposited hexane selenol (CH3(CH2)(5)SeH) on Au(111) using photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory (DFT). Experimentally, we find that initial adsorption leaves atomic Se on the surface without any carbon left on the surface, whereas further adsorption generates a saturated selenolate layer. The Se 3d component from atomic Se appears at 0.85 eV lower binding energy than the selenolate-related component. DFT calculations show that the most stable structure of selenols on Au(111) is in the form of RSe-Au-SeR complexes adsorbed on the unreconstructed Au(111) surface. This is similar to thiols on Au(111). Calculated Se 3d core-level shifts between elemental Se and selenolate in this structure nicely reproduce the experimentally recorded shifts. Dissociation of RSeH and subsequent formation of RH are found to proceed with high barriers on defect-free Au(111) terraces, with the highest barrier for scissoring R-Se. However, at steps, these barriers are considerably lower, allowing for Se-C bond breaking and hexane desorption, leaving elemental Se at the surface. Hexane is the selenol to selenolate formed by replacing the Se-C bond with a H-C bond by using the hydrogen liberated from transformation.
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| 4. |
- Dürlich, Luise, et al.
(författare)
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Overview of the CLEF-2024 Eloquent Lab : Task 2 on HalluciGen
- 2024
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Ingår i: <em>CEUR Workshop Proceedings</em>. - : CEUR-WS. ; , s. 691-702
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Konferensbidrag (refereegranskat)abstract
- In the HalluciGen task we aim to discover whether LLMs have an internal representation of hallucination. Specifically, we investigate whether LLMs can be used to both generate and detect hallucinated content. In the cross-model evaluation setting we take this a step further and explore the viability of using an LLM to evaluate output produced by another LLM. We include generation, detection, and cross-model evaluation steps for two scenarios: paraphrase and machine translation. Overall we find that performance of the baselines and submitted systems is highly variable, however initial results are promising and lessons learned from this year’s task will provide a solid foundation for future iterations of the task. In particular, we highlight that human validation of generated output is ideally necessary to ensure the robustness of the cross-model evaluation results. We aim to address this challenge in future iterations of HalluciGen.
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| 5. |
- Engström, Jens, et al.
(författare)
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Offshore Measurements and Numerical Validation of the Mooring Forces on a 1:5 Scale Buoy
- 2023
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Ingår i: Journal of Marine Science and Engineering. - : MDPI. - 2077-1312. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Wave energy conversion is a renewable energy technology with a promising potential. Although it has been developed for more than 200 years, the technology is still far from mature. The survivability in extreme weather conditions is a key parameter halting its development. We present here results from two weeks of measurement with a force measurement buoy deployed at Uppsala University’s test site for wave energy research at the west coast of Sweden. The collected data have been used to investigate the reliability for two typical numerical wave energy converter models: one low fidelity model based on linear wave theory and one high fidelity Reynolds-Averaged Navier–Stokes model. The line force data is also analysed by extreme value theory using the peak-over-threshold method to study the statistical distribution of extreme forces and to predict the return period. The high fidelity model shows rather good agreement for the smaller waves, but overestimates the forces for larger waves, which can be attributed to uncertainties related to field measurements and numerical modelling uncertainties. The peak-over-threshold method gives a rather satisfying result for this data set. A significant deviation is observed in the measured force for sea states with the same significant wave height. This indicates that it will be difficult to calculate the force based on the significant wave height only, which points out the importance of more offshore experiments. © 2023 by the authors.
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| 6. |
- Fernandez-Anez, Nieves, et al.
(författare)
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Current Wildland Fire Patterns and Challenges in Europe : A Synthesis of National Perspectives
- 2021
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Ingår i: Air, Soil and Water Research. - : SAGE Publications. - 1178-6221. ; 14, s. 1-19
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Forskningsöversikt (refereegranskat)abstract
- Changes in climate, land use, and land management impact the occurrence and severity of wildland fires in many parts of the world. This is particularly evident in Europe, where ongoing changes in land use have strongly modified fire patterns over the last decades. Although satellite data by the European Forest Fire Information System provide large-scale wildland fire statistics across European countries, there is still a crucial need to collect and summarize in-depth local analysis and understanding of the wildland fire condition and associated challenges across Europe. This article aims to provide a general overview of the current wildland fire patterns and challenges as perceived by national representatives, supplemented by national fire statistics (2009–2018) across Europe. For each of the 31 countries included, we present a perspective authored by scientists or practitioners from each respective country, representing a wide range of disciplines and cultural backgrounds. The authors were selected from members of the COST Action “Fire and the Earth System: Science & Society” funded by the European Commission with the aim to share knowledge and improve communication about wildland fire. Where relevant, a brief overview of key studies, particular wildland fire challenges a country is facing, and an overview of notable recent fire events are also presented. Key perceived challenges included (1) the lack of consistent and detailed records for wildland fire events, within and across countries, (2) an increase in wildland fires that pose a risk to properties and human life due to high population densities and sprawl into forested regions, and (3) the view that, irrespective of changes in management, climate change is likely to increase the frequency and impact of wildland fires in the coming decades. Addressing challenge (1) will not only be valuable in advancing national and pan-European wildland fire management strategies, but also in evaluating perceptions (2) and (3) against more robust quantitative evidence.
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| 7. |
- Jabbari, Mona, et al.
(författare)
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The Pedestrian Network Concept : A Systematic Literature Review
- 2023
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Ingår i: Journal of Urban Mobility. - : Elsevier. - 2667-0917. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The design of urban spaces that foster sustainable practices requires new analytical and structural approaches to spatial planning. An appropriate pedestrian network could significantly contribute to sustainable urban development goals, particularly by promoting sustainable mobility and pedestrian friendliness. With such goals, several attempts have been made to develop suitable models for pedestrian networks. However, something that is missing from the current literature is a framework that incorporates the main findings of the various studies as an integrated concise concept of the pedestrian network. To address this knowledge gap, this paper reviews studies on pedestrian networks and evaluates this concept based on the systematic 3W1H analysis method, which asks where, what, who, and how. In essence, the following questions are thus analyzed: Where is the pedestrian network located, What criteria play a role in the pedestrian network's performance, Who uses the pedestrian network, and How can the pedestrian network be analyzed? In this context, a systematic literature review is carried out by investigating studies conducted during the period 2001 to 2023 that appear in the Scopus database. The paper presents the results of the review of a selection of 67 papers dealing with pedestrian networks. Findings show that different models have been developed based on particular characteristics. Overall, researchers aimed to identify the most suitable network based on specific criteria for optimizing the walking experience in urban areas. By synthesizing the findings reported in these papers, this paper arguably contributes to a more comprehensive understanding of pedestrian networks, provides insights into the prioritization of design phases, facilitates the use of pedestrian network assessment models for future research, and creates a bigger picture for urban planners with a multidimensional view to a new sustainable urban structure.
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| 8. |
- Katsidoniotaki, Eirini, et al.
(författare)
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Validation of a CFD model for wave energy system dynamics in extreme waves
- 2023
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Ingår i: Ocean Engineering. - : Elsevier Ltd. - 0029-8018 .- 1873-5258. ; 268
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Tidskriftsartikel (refereegranskat)abstract
- The design of wave energy converters should rely on numerical models that are able to estimate accurately the dynamics and loads in extreme wave conditions. A high-fidelity CFD model of a 1:30 scale point-absorber is developed and validated on experimental data. This work constitutes beyond the state-of-the-art validation study as the system is subjected to 50-year return period waves. Additionally, a new methodology that addresses the well-known challenge in CFD codes of mesh deformation is successfully applied and validated. The CFD model is evaluated in different conditions: wave-only, free decay, and wave–structure interaction. The results show that the extreme waves and the experimental setup of the wave energy converter are simulated within an accuracy of 2%. The developed high-fidelity model is able to capture the motion of the system and the force in the mooring line under extreme waves with satisfactory accuracy. The deviation between the numerical and corresponding experimental RAOs is lower than 7% for waves with smaller steepness. In higher waves, the deviation increases up to 10% due to the inevitable wave reflections and complex dynamics. The pitch motion presents a larger deviation, however, the pitch is of secondary importance for a point-absorber wave energy converter. © 2022 The Author(s)
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| 9. |
- Mohammadi, Zahra, et al.
(författare)
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Critical Factors in Designing of Lean and Green Equipment
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Designing production equipment considering lean and related sustainability requirements may be a major factor in achieving productiveness through lean implementation. The objective of the study is to investigate the impact of lean production requirements on equipment design and how the lean requirements affects early design phases and global footprint. Data collection method includes literature review and in depth interviews with equipment users. The results provide support to importance of considering green and lean requirements in designing of production equipment by introducing important lean design factors for production equipment. These factors are designing simple equipment, error-proofing, being portable and flexible, supporting one piece flow, supporting short setup time, easy and reliable maintenance, supporting the operator interface with machine, safety of the operator, supporting production processes and layouts, energy efficiency, easy to operate, minimum cost, visualization, straight flows, teamwork, standardization, quality assurance, using pervious experiences, easy to clean, and easy to control.
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| 10. |
- Sahlgren, Magnus, et al.
(författare)
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ELOQUENT 2024 - Robustness Task
- 2024
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Ingår i: <em>CEUR Workshop Proceedings</em>. - : CEUR-WS. ; , s. 703-707
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Konferensbidrag (refereegranskat)abstract
- ELOQUENT is a set of shared tasks for evaluating the quality and usefulness of generative language models. ELOQUENT aims to apply high-level quality criteria, grounded in experiences from deploying models in real-life tasks, and to formulate tests for those criteria, preferably implemented to require minimal human assessment effort and in a multilingual setting. One of the tasks for the first year of ELOQUENT was the robustness task, in which we assessed the robustness and consistency of a model output given variation in the input prompts. We found that indeed the consistency varied, both across prompt items and across models, and on a methodological note we find that using a oracle model for assessing the submitted responses is feasible, and intend to investigate consistency across such assessments for different oracle models. We intend to run this task in coming editions for ELOQUENT to establish a solid methodology for further assessing consistency, which we believe to be a crucial component of trustworthiness as a top level quality characteristic of generative language models.
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