| 1. |
- Ali, Sharafat, Associate Professor, 1976-, et al.
(författare)
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
- 2024
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Ingår i: Progress in Solid State Chemistry. - : Elsevier. - 0079-6786 .- 1873-1643. ; 74
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Forskningsöversikt (refereegranskat)abstract
- The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 degrees C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (alpha). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.
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| 2. |
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| 3. |
- Karlsson, Stefan
(författare)
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Exploring API Behaviours by Example Generation
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Understanding the behaviour of complex software-intensive systems is a hard task. For developers of such systems, understanding the actual behaviours is critical in order to successfully create, extend, and maintain them.The goal of the work in this thesis is to support explorations of the behaviour of software systems through their APIs. We fulfil this goal by generating examples of behaviours the system exhibits. An example is expressed as a sequence of API operations---with parameters, if required---that conforms to a specific behaviour.Examples of behaviours, such as sequences of operations performed on the system, have been shown to be a good way to further the understanding of software systems for both end users and developers. However, manually creating examples requires effort. In addition, manually created examples only contain what a human can imagine---which might miss important cases, such as unintended behaviours.The main proposed approach in this thesis is to support users in exploring the behaviour of their software system by automatically generating examples of actual behaviour. By only interacting with the system by the exposed API, we assess the behaviours as exposed to an end user of the API. The input to the approach is a set of API operations and schema of operation parameters. Sequences of operations are generated containing these provided operations. The observed responses from executing the generated sequences are used to assess if the API show an example of a sought behaviour. Found examples go through a shrinking process---trying to find a more minimal sequence showing the same behaviour---and are then reported to the user of the approach. The approach is capable of both generating examples of faults in the system and of generating examples of general behaviours. We show evidence of this through multiple evaluations. We have evaluated the fault-finding capabilities by generating examples producing fault-indicating error codes and showing how the configuration of generators affects the interaction with the system. In addition, we evaluate the capability of the approach to generate relevant examples, both in the general API case and in the specific case of REST APIs. By conducting multiple focus group sessions, we conclude that the examples of behaviours produced by the approach indeed aid industry practitioners. The generated examples are deemed relevant for use cases such as testing, documenting, and understanding the behaviour of the system.
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| 4. |
- Karlsson, Stefan, et al.
(författare)
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Exploring API behaviours through generated examples
- 2024
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Ingår i: Software Quality Journal. - : SPRINGER. - 1573-1367 .- 0963-9314. ; 32:2, s. 729-763
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the behaviour of a system's API can be hard. Giving users access to relevant examples of how an API behaves has been shown to make this easier for them. In addition, such examples can be used to verify expected behaviour or identify unwanted behaviours. Methods for automatically generating examples have existed for a long time. However, state-of-the-art methods rely on either white-box information, such as source code, or on formal specifications of the system behaviour. But what if you do not have access to either? This may be the case, for example, when interacting with a third-party API. In this paper, we present an approach to automatically generate relevant examples of behaviours of an API, without requiring either source code or a formal specification of behaviour. Evaluation on an industry-grade REST API shows that our method can produce small and relevant examples that can help engineers to understand the system under exploration.
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| 5. |
- Karlsson, Stefan, et al.
(författare)
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Exploring behaviours of RESTful APIs in an industrial setting
- 2024
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Ingår i: Software quality journal. - : Springer. - 0963-9314 .- 1573-1367.
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Tidskriftsartikel (refereegranskat)abstract
- A common way of exposing functionality in contemporary systems is by providing a Web-API based on the REST API architectural guidelines. To describe REST APIs, the industry standard is currently OpenAPI-specifications. Test generation and fuzzing methods targeting OpenAPI-described REST APIs have been a very active research area in recent years. An open research challenge is to aid users in better understanding their API, in addition to finding faults and to cover all the code. In this paper, we address this challenge by proposing a set of behavioural properties, common to REST APIs, which are used to generate examples of behaviours that these APIs exhibit. These examples can be used both (i) to further the understanding of the API and (ii) as a source of automatic test cases. Our evaluation shows that our approach can generate examples deemed relevant for understanding the system and for a source of test generation by practitioners. In addition, we show that basing test generation on behavioural properties provides tests that are less dependent on the state of the system, while at the same time yielding a similar code coverage as state-of-the-art methods in REST API fuzzing in a given time limit.
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| 6. |
- Karlsson, Stefan, 1984-
(författare)
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Functional glasses and coatings for efficient solar energy harvesting
- 2024
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Glass materials are an essential component in solar energy applications which comprise, e.g., photovoltaics, solar thermal collectors, greenhouses, and algae reactors, by acting as a protective and light transmitting barrier [1, 2]. Adding functionalities and optimizing the glass and coatings in an intelligent way creates opportunities to enhance the properties of the cover glass material for its use. Glass as a cover material for solar energy applications constitutes a significant part of the costs and a major part of the weight. However, glass is an important component for efficient light capture and protection to the environment. The R&D of cover glass for solar energy applications have so far received limited attention even though it is an important material for our future sustainable development and will likely require an increase of the flat glass production in the future. Recent research efforts have provided knowledge of which properties that needs to be optimized - balancing efficiency, service lifetime and cost. The challenges of cover glass for different solar energy applications differs somewhat but all have in common the efficient solar light capture and protection to the environment. Thus, the know-how can be used in several different industrial sectors. The fundamentals of cover glasses for solar energy applications as well as previous and on-going project concepts will be presented. This includes i) state-of-the-art of cover materials for greenhouses [2], ii) results on optimization of cover glass for photovoltaics [3, 4], iii) initial results on how to provide both anti-reflective and anti-soiling properties, iv) results on broadband antireflective coatings for solar thermal energy [5], and v) other promising concepts. At last, will some perspective of matters for further research be presented.[1] J. Deubener, et al., Glasses for solar energy conversion systems. Journal of the European Ceramic Society, 2009. 29(7): p. 1203-1210. DOI: http://dx.doi.org/10.1016/j.jeurceramsoc.2008.08.009.[2] M. Teitel, et al., Greenhouse and screenhouse cover materials: literature review and industry perspective. Acta Horticulturae, 2018. 1227: p. 31-44. DOI: https://doi.org/10.17660/ActaHortic.2018.1227.4.[3] B.L. Allsopp, et al., Towards improved cover glasses for photovoltaic devices. Progress in Photovoltaics: Research and Applications, 2020. 28(11): p. 1187-1206. DOI: https://doi.org/10.1002/pip.3334.[4] P. Sundberg, et al., Simultaneous chemical vapor deposition and thermal strengthening of glass. Thin Solid Films, 2019. 669: p. 487-493. DOI: https://doi.org/10.1016/j.tsf.2018.11.028.[5] E. Zäll, et al., Aerosol-based deposition of broadband antireflective silica coating with closed mesoporous structure. Solar Energy Materials and Solar Cells, 2023. 250: p. 112078. DOI: https://doi.org/10.1016/j.solmat.2022.112078.
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| 7. |
- Macrelli, Guglielmo, et al.
(författare)
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Commercial glass strengthening and safety technologies : lessons learned and yet to be learned
- 2024
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Ingår i: European Journal of Glass Science and Technology. Part A: Glass Technology. - : Society of Glass Technology. - 1753-3546. ; 65:3, s. 65-88
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Tidskriftsartikel (refereegranskat)abstract
- This is the fourth in this series of “Lessons Learned and Yet to be Learned” on topics related to glass strength.(1-3) In this paper we pick up the topic of stronger glass products from our earlier publication(2) and expand to discussing commercial technologies. Included in this discussion are a brief historical perspective of the initial technologies and update to newer technologies with the aim to obtain faster production rates that focus on lightweight glass products and a sustainable future with respect to resource conservation, reduced energy consumption and reduced CO2 emissions. Also included are glass products which focus on safety mostly and less on overall strength.
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| 8. |
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| 9. |
- Nilsson, Charlotte, 1985-
(författare)
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Phosphorus recovery from sewage sludge : Implications of incineration and enrichment potential of produced ashes
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sewage sludge is a promising source for phosphorus recovery, but it also contains contaminants (organics, metals) which must be removed. The most commonly used practice is incineration, where organic contaminants are decomposed. This treatment entirely alters the chemical profile of the material, and information regarding this transformation is crucial for development of durable handling and recovery processes. The aims of this project were to; 1)study the chemical speciation of phosphorus and metals in sewage sludge and their ashes after incineration; 2)evaluate the impact of iron and aluminium on the phosphorus redistribution following incineration, and 3)investigate the potential for sewage sludge ashes to function as sorbents for phosphorus and metals. Sludge and ashes from 10 municipal wastewater treatment plants in Sweden were sampled and characterized for their elemental composition, mineral components, leachability and chemical speciation. Major elements were Fe and Al (added in the wastewater treatment process), Ca, Mg, Na and K. Phosphorus was predominantly associated with aluminium and iron in the sludge, but after incineration there was a shift to calcium associated species, which is preferred for phosphorus recovery. This alteration was hampered by high concentrations of aluminium, why its concentration should be kept at a minimum. The incineration caused changes in speciation, where more ordered mineral phases where created, hematite being the major component. The ashes were successfully used as sorbents for both metals and phosphorus. Adsorption isotherms and inter particle-diffusion modelling indicated that the sorption takes place in two stages, where the first is a rapid process on the surfaces, while the second is slower and includes interactions with the pores of the material.
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| 10. |
- Nilsson, Charlotte, 1985-, et al.
(författare)
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Phosphorus speciation in sewage sludge and their ashes after incineration as a function of treatment processes
- 2024
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Ingår i: Waste Management & Research. - : Sage Publications. - 0734-242X .- 1096-3669.
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorus (P) is a key component in agricultural fertilizers, but it is also a scarce resource, why its recycling has been thoroughly investigated and one promising resources is sewage sludge. Because of stricter regulations in terms of sludge disposal, thermal treatment (e.g. incineration) has become an attractive option. The incineration process alters the chemical speciation of P in favour to calcium-associated (apatite, apatite phosphorus (AP)) species, which is preferred for P recovery. In order to achieve qualitatively transformation, it is important to identify limiting or promoting factors. This study reports on the impact of iron, aluminium and calcium on the transformation of iron- and aluminium-phosphate (NAIP) to AP species, assessed by studying sludge and ash from 10 municipal wastewater treatment plants in Sweden. The effect of iron and aluminium added in the treatment processes was also evaluated. The obtained results show that high calcium concentration favours formation of AP species in both sludge and ashes, whereas high concentration of iron and aluminium favours formation of NAIP species in the sludge. The transformation from NAIP to AP species is hampered by aluminium, irrespectively of its origin, whereas no such correlations could be seen for iron. Therefore, in order to enable efficient P recovery from sewage sludge ash, the amount of aluminium added in the treatment process, as well as its concentration in influent streams to the treatment plants, must be limited.
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