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Case study: IMO minimum propulsion power to maintain the manoeuvrability of KVLCC2 tanker in adverse conditions
No full textThe introduction of the EEDI more than a decade ago, slow steaming, and the wish to reduce bunkering costs have resulted in a trend to install less powerful engines in ships. To avoid vessels becoming underpowered and thus unsafe, the International Maritime Organization (IMO) has published a guideline regarding the “Minimum Propulsion Power to Maintain the Manoeuvrability of Ships in Adverse Conditions”. This report presents a case study that follows the IMO-guideline step by step and works out the minimum engine size for the KVLCC2 tanker. Using a combination of Computational Fluid Dynamics and model tests, the parameters and assumptions behind the guideline are discussed in some detail. Results show that it is particularly important to determine the added resistance in waves correctly because it dominates the power prediction. It becomes clear, that the selection of the propulsive factors, particularly the “thrust deduction factor” has a significant influence on results. The work summarised here is part of a wider project that aims to provide experimental benchmarking data for added resistance predictions. It has been sponsored by the Swedish Transport Administration (Trafikverket) under grant number TRV 2021/53938
Malmbanan 2025 - Slutrapport
No full textFör att kunna genomföra optimeringarna krävdes viss utveckling av M2. Indata tillhandahölls dels av Trafikverket, dels av LKAB. För att hitta en bra lösning tillräckligt snabbt byggdes först en tidtabell upp genom att fler och fler tåg lades in iterativ, och sedan optimerades den giltiga tidtabellen utifrån flera olika målfunktioner. Denna metod beskrivs i ”Metod”.Resultaten var att flödena som lagts in kunde genomföras samtidigt som banarbetena fick den tid som krävdes. När LKAB utvärderade tidtabellen visade det sig dock att malmtågen flyttat på sig på ett sätt som innebär att det skulle krävas fler lok än dagens trafik. För att stoppa optimeringen från att göra sådana omflyttningar krävs nya villkor, vilka beskrivs i ”Framtida arbete”. Även villkor för att modellera hastighetsnedsättningar vore bra. Den sista men kanske viktigaste insikten från projektet är att ett närmare iterativt samarbete, där LKAB och Trafikverket i större utsträckning är med och analyserar olika optimerade tidtabeller och bestämmer hur optimeringsparametrarna ska justeras, nog hade resulterat i ett bättre slutresultat.Projektets budget vad 200 000 kr, varav 100 000 kr finansierades av Trafikverket och 100 000 kr av LKAB.</p
Software Reuse through Open Source Software in the Public Sector : A qualitative survey on Policy and Practice
No full textThis report delves into how Public Sector Organizations (PSOs) and the public sector at large facilitate software reuse, specifically through Open Source Software (OSS) as an instrument. The report is commissioned by the Danish Agency for Digital Government (Digitaliseringsstyrelsen[1]) and Local Government Denmark (KL[2]), which provide input on how Danish PSOs can specifically improve at reaping benefits by reusing existing software and creating value by developing software in a way that can be reused. A qualitative survey is conducted on a sample of 15 countries considered mature in their digital practices, as indicated through a set of digital maturity indicators. These countries are surveyed in terms of government policies, rationales, support mechanisms, means of promotion, and success stories related to software reuse. The surveyed countries exhibit diverse policies, emphasizing interoperability, digital sovereignty, transparency, and cost efficiency. Economic arguments, interoperability, and transparency are prominent goals, while digital sovereignty varies. Security concerns are discussed, acknowledging both risks and benefits of OSS. The report identifies emerging support structures, including Open Source Program Offices (OSPOs), crucial for institutional capacity. Success stories highlight the transformation to sustainable governance enabled through the use of neutral proxy organizations acting as stewards for public sector OSS projects. Recommendations are provided that focus on fostering software reuse through OSS adoption, aiming to guide policy- and decisionmakers at national, regional, and local government levels. The report contributes valuable insights for countries, like Denmark, seeking to leverage software reuse through OSS in their digital transformations. [1] https://digst.dk/[2] https://www.kl.dk/In this report, we investigate how PSOs and the public sector at large enable and facilitate software reuse, specifically through OSS as an instrument. The report is commissioned by the Danish Agency for Digital Government (Digitaliseringsstyrelsen) and Local Government Denmark (KL), providing input on how Danish PSOs can specifically become better at reaping benefits by reusing existing software and creating value by developing software in a way so that it can be reused.</p
Practical Aspects of Designing a Human-centred AI System in Manufacturing
No full textAn increasing number of manufacturing companies have initiated designing and implementing AI systems in manufacturing, however, with limited success. Within our overarching research objective of establishing a methodology for the development of AI systems in manufacturing with socio-technical system consideration, this paper focuses on the early design phase of the development life cycle and aims to identify factors that are essential in the phase but whose importance has been less addressed in the manufacturing literature. To this aim, a case study was conducted adopting a design science approach. The case company was developing an ML-based anomaly detection system for a casting process. The researcher organised an AI system design workshop where participants from the company used the Human-AI design guidelines created by a leading large software company. The workshop enabled the participants to explore a wide range of design concerns. It, however, caused the confusing experience that they had to deal with too many questions simultaneously without clear guidance. Analysing this negative experience has led to identifying four design issues requiring further attention in the research. An example of these issues is that the interdependency of design decisions on operational procedures, human-machine interfaces, ML models, pre-processing, and input data makes it challenging to design these elements in isolation. The study found that a structured approach to dealing with the identified issues was currently lacking. This paper contributes to the manufacturing research community by addressing key unresolved issues in the research through highlighting practical details of designing AI systems in manufacturing. Conference name: 5th International Conference on Industry 4.0 and Smart Manufacturing, ISM 2023; Conference date: 22 November 2023 through 24 November 2023; Conference code: 198427; All Open Access, Gold Open Access</p
Lignin-Based Wax Inhibitors
No full textThis article tested a novel concept for synthesizing green wax inhibitors. Four technical lignins were reacted with stearoyl chloride to produce esterified C18 esterified lignin. The effect of the reaction on the lignin molecular weight, characteristic FTIR spectra, and thermal degradation was surveyed. In addition, wax inhibition testing was performed by rheology on model waxy oils. The grafting reactions increased the mass-average molecular weight of the lignin and in some cases also the polydispersity index. FTIR analysis confirmed the success of esterification reactions as the O-H stretching band decreased, whereas the C-H and C═O stretching bands significantly increased. The thermal degradation was further found to occur at temperatures above 170 °C, indicating that the lignin wax inhibitors were thermally stable enough for crude oil production. The effect on waxy gelation was varied, showing that the low molecular weight waxes benefited more than the high molecular ones. A gelation point reduction of up to 6 °C was found after lignin addition. After the wax type, wax concentration, lignin concentration, and lignin type were varied, it was found that C18 esterified Kraft lignin exhibited the most beneficial effect. The results from viscometry agreed with the observations from the rheometric gelation point. Cross-polarized microscopy was used to map the effect on the wax crystal morphology. A difference was found only in the case of one esterified Kraft lignin, which yielded smaller and more finely dispersed wax crystals. In conclusion, a new wax inhibitor was synthesized by reacting technical lignin with stearoyl chloride. This lignin showed wax inhibitor activity in some of the tested cases. At this point, the length of the pendant alkyl chains (C18) is likely a limiting factor. However, this study attributes the potential for a new concept to synthesize green wax inhibitors. This work was carried out as a part of project “LignoWax – Green Wax Inhibitors and Production Chemicals based on Lignin”, grant number 326876. The authors gratefully acknowledge the financial support from the Norwegian Research Council, Equinor ASA, and ChampionX Norge AS.</p
Design, Manufacture, and Cryogenic Testing of a Linerless Composite Tank for Liquid Hydrogen
No full textThis paper describes design, manufacture, and testing of a linerless composite vessel for liquid hydrogen, having 0.3 m diameter and 0.9 m length. The vessel consists of a composite cylinder manufactured by wet filament winding of thin-ply composite bands, bonded to titanium end caps produced by additive manufacturing. The aim was to demonstrate the linerless design concept with a thin-ply composite for the cylinder. The investigation is limited to the internal pressure vessel, while real cryogenic tanks also involve an outer vessel containing vacuum for thermal insulation. Thermal stresses dominate during normal operation (4 bar) and the layup was selected for equal hoop strains in the composite cylinder and end caps during filling with liquid hydrogen. Two vessels were tested in 20 cycles, by filling and emptying with liquid nitrogen to 4 bar, without signs of damage or leakage. Subsequently, one vessel was tested until burst at almost 30 bar.Open access funding provided by RISE Research Institutes of Sweden. This work was to 92% funded by Energimyndigheten (the Swedish Energy Agency) through contract P2021-90061. Co-funding was provided by Oxeon AB. Finalisation of the manuscript has subsequently been funded by the internal development funds of RISE and Energimyndigheten (the Swedish Energy Agency) through contract P2021-90268 via the Competence Centre TechForH2</p
Metal loss and corrosion attack of FeCrAl overlay welds on evaporator tube shields of a waste-fired power plant
No full textThree FeCrAl alloys (APMT, EF100 and EF101) from Kanthal® and the reference Ni-Cr Alloy 625 were used as weld cladding materials on tube shields in the evaporator tube bank of a waste-fired combined heat and power plant. For each alloy type, the overlay welded tube shields were placed in both roof and floor positions within the evaporator for 6 months. The metal-loss rate, the microstructure and hardness of the overlay welds before and after exposure and the corrosion products were analysed. The results showed higher metal-loss rates in the welds placed in the roof position, confirming heterogeneities in the evaporator bank environment. Alloys were ranked from higher to lower erosion–corrosion resistance as follows: APMT ≈ Alloy 625 > EF101 > EF100. The analysis of the corrosion attacks showed a significant variation among the alloys, from a primarily homogeneous corrosion attack on APMT to intergranular corrosion in EF100 and pit formation in EF101. Alleima AB (formerly Sandvik Materials Technology AB), E.ON Värme Sverige AB and Kanthal AB are gratefully acknowledged for their participation and support in these research projects, and especially for providing the alloys, supporting the exposures in the boiler and valuable discussions. Eric Börjesson is acknowledged for performing valuable laboratory work at RISE and Kjell Hurtig is gratefully acknowledged for the preparation of the overlay welds at University West. Anna Jonasson is acknowledged for valuable planning and assistance regarding the exposure in the P14 plant at Händelö. This work was supported by the project, funded by the Stiftelsen för Kunskaps och Kompetensutveckling (KK‐stiftelsen) under Grant reference 20170316; and as part of the project KME‐802 , funded by the Swedish Energy Agency under Grant reference 46471‐1. HÖG‐FECRALCLAD Svetsbarhet och korrosionbeständinghet av nya FeCrAl‐legeringar Increased fuel flexibility and performance for boilers with challenging fuels</p
Glacier : guided locally constrained counterfactual explanations for time series classification
No full textIn machine learning applications, there is a need to obtain predictive models of high performance and, most importantly, to allow end-users and practitioners to understand and act on their predictions. One way to obtain such understanding is via counterfactuals, that provide sample-based explanations in the form of recommendations on which features need to be modified from a test example so that the classification outcome of a given classifier changes from an undesired outcome to a desired one. This paper focuses on the domain of time series classification, more specifically, on defining counterfactual explanations for univariate time series. We propose Glacier, a model-agnostic method for generating locally-constrained counterfactual explanations for time series classification using gradient search either on the original space or on a latent space that is learned through an auto-encoder. An additional flexibility of our method is the inclusion of constraints on the counterfactual generation process that favour applying changes to particular time series points or segments while discouraging changing others. The main purpose of these constraints is to ensure more reliable counterfactuals, while increasing the efficiency of the counterfactual generation process. Two particular types of constraints are considered, i.e., example-specific constraints and global constraints. We conduct extensive experiments on 40 datasets from the UCR archive, comparing different instantiations of Glacier against three competitors. Our findings suggest that Glacier outperforms the three competitors in terms of two common metrics for counterfactuals, i.e., proximity and compactness. Moreover, Glacier obtains comparable counterfactual validity compared to the best of the three competitors. Finally, when comparing the unconstrained variant of Glacier to the constraint-based variants, we conclude that the inclusion of example-specific and global constraints yields a good performance while demonstrating the trade-off between the different metrics. © The Author(s) 2024.This work was funded in part by the Digital Futures cross-disciplinary research centre in Sweden, and the EXTREMUM collaborative project ( https://datascience.dsv.su.se/projects/extremum.html ).</p
Assessment on Strength and Stiffness Properties of Aged Structural Timber
No full textDespite the growing popularity of wood and wood-based products in the construction industry, there has been insufficient focus on assessing the condition, preservation, and potential reuse of existing timber. While numerous standards evaluate the quality of freshly sawn timber, there is currently no standardized system for assessing the strength properties of aged and reused timber. The lack of these guidelines is also one of the reasons the results obtained in numerous research are often fluctuating, and we cannot draw clear conclusions. The matter is further complicated by the lack of data on old in-situ wood and its exploitation, which would help to evaluate its condition. Consequently, there is a real practical need to assess the condition of old timber to avoid unnecessary demolition and the loss of valuable and structurally sound building material. What sets this study apart from others is that, in addition to destructive testing, the 4-point non-destructive (ND) bending tests were conducted on all four faces of test specimens. This provided an opportunity to assess the wood visually and then find connections to associate external characteristics with real properties. This methodology aimed to determine whether it is feasible to visually assess the most practical way to use wooden elements in construction. If this question arises, which face of the beam would be better suited for the tension side and which for the compression side? The old timber used in testing originated from an old library building located on Vaksali Street, Tartu, Estonia and is estimated to be about 120 years old. This paper investigates and compares the collected data with a Nordic standard for grading fresh-sawn timber and two established Italian standards for visually assessing aged timber. This comparison contributes to developing a standardized framework for future visual assessments. ND and destructive four-point bending tests were performed to validate and find appropriate visual characteristics to determine the strength and stiffness of the timber elements. The primary goals of this study were first to compare the results obtained from existing ND methods with actual results and secondly to provide guidelines for better visual grading of wood in the future, based on Nordic Standard INSTA 142 (2010) and Italian standards UNI 11119 (2004) and UNI 11035 (2010) Contrary to previous research conclusions, the visual assessment results yielded unexpected outcomes. The results show that the grading standards significantly underestimated the real strength of the wood, and even more, none of the visual assessments overestimated the real strength of the specimens. Therefore, based on prior research and the findings derived from this study, there is evident a substantial potential for extensive development and optimization within this field.This work has been supported by the European Commission through the LIFE IP BUILDEST (LIFE20 IPC/EE/000010, by Estonian Environmental Investment Centre through the project Tartu Ringren-oveerimine (MNKE22064), and, by the Estonian Research Council through the grant PRG483.</p
Gingival fibroblast response to (hybrid) ceramic implant reconstruction surfaces is modulated by biomaterial type and surface treatment
No full textObjectives: Surface characteristics of implant reconstructions determine the gingival fibroblast (GF) response and thus soft tissue integration (STI). However, for monolithic implant reconstructions it is unknown whether the (hybrid) ceramic biomaterial type and its surface treatment affect GF response. Therefore, this investigation examined the influence of the implant reconstruction biomaterials hybrid ceramic (HC), lithium disilicate ceramic (LS), 4 and 5 mol% yttria partially stabilized zirconiumdioxide ceramics (4/5Y-PSZ) and their surface treatment - machining, polishing or glazing - on surface characteristics and GF response. Methods: After characterization of surface topography and wettability by scanning electron microscopy, interferometry and contact angle measurement, the adhesion, morphology, metabolic activity and proliferation of GFs from six donors was investigated by fluorescent staining and a resazurin-based assay at days 1, 3 and 7. Titanium (Ti) served as control. Results: Biomaterial type and surface treatment affected the GF response in a topography-dependent manner. Smooth polished and glazed surfaces demonstrated enhanced GF adhesion and earlier proliferation onset compared to rough machined surfaces. Due to minor differences in surface topography of polished and glazed surfaces, however, the GF response was similar for polished and glazed HC, LS, 4- and 5Y-PSZ as well as Ti. Significance: Within the limits of the present investigation, polishing and glazing of machined HC, LS and 4/5Y-PSZ can be recommended to support STI-relevant cell functions in GF. Since the GF response on polished and glazed HC, LS, 4- and 5Y-PSZ surfaces and the Ti control was comparable, this investigation proofed equal cytocompatibility of these surfaces in vitro. © 2024 The AuthorsThis work was funded by the German Society for Prosthetic Dentistry and Biomaterials (DGPro) and the Berta-Ottenstein-Program for Advanced Clinician Scientists, Faculty of Medicine, University of Freiburg </p