| 1. |
- Mathern, Alexandre, 1986, et al.
(författare)
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Concrete Support Structures for Offshore Wind Turbines: Current Status, Challenges, and Future Trends
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:7
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Forskningsöversikt (refereegranskat)abstract
- Today’s offshore wind turbine support structures market is largely dominated by steel structures, since steel monopiles account for the vast majority of installations in the last decade and new types of multi-leg steel structures have been developed in recent years. However, as wind turbines become bigger, and potential sites for offshore wind farms are located in ever deeper waters and ever further from the shore, the conditions for the design, transport, and installation of support structures are changing. In light of these facts, this paper identifies and categorizes the challenges and future trends related to the use of concrete for support structures of future offshore wind projects. To do so, recent advances and technologies still under development for both bottom-fixed and floating concrete support structures have been reviewed. It was found that these new developments meet the challenges associated with the use of concrete support structures, as they will allow the production costs to be lowered and transport and installation to be facilitated. New technologies for concrete support structures used at medium and great water depths are also being developed and are expected to become more common in future offshore wind installations. Therefore, the new developments identified in this paper show the likelihood of an increase in the use of concrete support structures in future offshore wind farms. These developments also indicate that the complexity of future support structures will increase due to the development of hybrid structures combining steel and concrete. These evolutions call for new knowledge and technical know-how in order to allow reliable structures to be built and risk-free offshore installation to be executed.
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| 2. |
- Karim, Ali Naman, 1992, et al.
(författare)
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Knowledge gaps regarding the hygrothermal and long-term performance of aerogel-based coating mortars
- 2022
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618. ; 314:Part A
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Forskningsöversikt (refereegranskat)abstract
- Aerogel-based coating mortars are an emerging class of multifunctional wall finishes that stand out for their thermal insulation performance. Commercial and trial mixtures, studied under laboratory conditions, have a declared thermal conductivity of about 30–50 mW/(m∙K). This is comparable to conventional insulation ma-terials such as polystyrene and mineral wool. Aerogel-based coating mortars are primarily intended for use in existing and uninsulated building envelopes. Currently, there is a high research interest in the development of aerogel-based coating mortars. Nevertheless, the knowledge about their hygrothermal and mechanical properties have not been fully explored yet. These properties are needed to assess the moisture risks and long-term dura-bility in different applications and to justify the higher investment costs for aerogel-based coating mortars compared to conventional ones. Apart from the material properties of aerogel-based coating mortars, results from full-scale studies focusing on hygrothermal performance are scattered and representative for limited number of climate conditions and specific products. In this article, available information on hygrothermal and mechanical properties of aerogel-based coating mortars is collected and systematized. The aim is to map the missing data needed for moisture risk assessments. This study focuses on knowledge gaps regarding the hygrothermal and long-term performance of aerogel-based coating mortars, both commercial products and laboratory-based trial mixtures. In addition, economic perspective and health related concerns of the material are discussed. The results indicate that future research efforts should focus more on moisture risk assessments of the material to ensure moisture safe designs especially in areas with humid climates and freeze-thawing. More information needs to be readably available on the me-chanical and hygrothermal compatibility of aerogel-based coating mortars with other materials in multilayer wall systems. In addition, available information on the hygrothermal and mechanical properties and long-term performance of aerogel-based coating mortars need to be further explored.
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| 3. |
- Bagherbandi, Mohammad, Professor, et al.
(författare)
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Time transfer and significance of vertical land motion in relativistic geodesy applications: a review paper
- 2023
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Ingår i: Frontiers in Earth Science. - : Frontiers. - 2296-6463. ; 11
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Forskningsöversikt (refereegranskat)abstract
- Determination of the Earth’s gravity field and geopotential value is one of the fundamental topics in physical geodesy. Traditional terrestrial gravity and precise leveling measurements can be used to determine the geopotential values at a local or regional scale. However, recent developments in optical atomic clocks have not only rapidly improved fundamental science but also contributed to applied research. The latest generation of optical clocks is approaching the accuracy level of 10−18 when facilitating atomic clock networks. These systems allow examining fundamental theories and many research applications, such as atomic clocks applications in relativistic geodesy, to precisely determine the Earth’s gravity field parameters (e.g., geopotential values). According to the theory of relativistic geodesy, the frequency difference measured by an optical clock network is related to the gravity potential anomaly, provided that the effects of disturbing signals (i.e., tidal and non-tidal contributions) are filtered out. The relativistic geodesy principle could be used for a practical realization of global geodetic infrastructure, most importantly, a vertical datum unification or realization of height systems. This paper aims to review the background of relativistic (clock-based) geodesy and study the variations of optical atomic clock measurements (e.g., due to hydrology loading and land motion).
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| 4. |
- Mara, Valbona, 1986, et al.
(författare)
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Review of FRP decks: structural and in-service performance
- 2015
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Ingår i: Proceedings of the Institution of Civil Engineers: Bridge Engineering. - : Thomas Telford Ltd.. - 1478-4637 .- 1751-7664. ; 168:4, s. 308-329
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Forskningsöversikt (refereegranskat)abstract
- In the past two decades, fibre-reinforced polymer (FRP) bridge decks have attracted a great deal of attention for applications in the refurbishment of existing bridges and for the construction of new bridges. FRP decks are lighter, more corrosion resistant and easier to install than conventional concrete decks. A considerable amount of research effort has been devoted to FRP decks and numerous bridges have been rehabilitated or constructed using these decks. This paper presents a review of the structural and field performance of FRP decks. The latest research and current practices have been synthesised, and several experts and practitioners have been consulted. Aspects related to the structural behaviour of steel bridges with FRP decks, including fatigue performance, composite action between the deck and underlying girders, the performance of various connections as well as observed failure modes are reviewed and summarised. This paper concludes by identifying areas for further research.
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| 5. |
- Nilimaa, Jonny
(författare)
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Smart materials and technologies for sustainable concrete construction
- 2023
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Ingår i: Developments in the Built Environment. - : Elsevier. - 2666-1659. ; 15
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Forskningsöversikt (refereegranskat)abstract
- This paper presents a comprehensive review of current trends and opportunities for sustainable concrete construction, emphasizing the importance of adopting eco-friendly practices to mitigate the industry's environmental impact. Green concrete, supplementary cementitious materials, permeable concrete, cool concrete, and the use of local materials are explored as sustainable materials and technologies. Innovations like self-healing concrete, 3D-printed concrete, photocatalytic concrete, electrified machineries, and carbon capture, utilization, and storage principles are also discussed, highlighting their potential to improve the sustainability of construction practices. Challenges faced in implementing sustainable concrete construction practices, such as technical, economic, and social barriers, are also addressed. The roles of governments, industry, and academia in promoting sustainable concrete construction are examined, stressing the need for interdisciplinary collaboration and research. Lastly, emerging trends and technologies, including digitalization, data-driven approaches, and circular economy principles, are identified as critical factors in driving the transition towards sustainable concrete construction.
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| 6. |
- Fachrizal, Reza, 1993-, et al.
(författare)
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Smart charging of electric vehicles considering photovoltaic power production and electricity consumption : a review
- 2020
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Ingår i: eTransporation. - : Elsevier. - 2590-1168. ; 4
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Forskningsöversikt (refereegranskat)abstract
- Photovoltaics (PV) and electric vehicles (EVs) are two emerging technologies often considered as cornerstones in the energy and transportation systems of future sustainable cities. They both have to be integrated into the power systems and be operated together with already existing loads and generators and, often, into buildings, where they potentially impact the overall energy performance of the buildings. Thus, a high penetration of both PV and EVs poses new challenges. Understanding of the synergies between PV, EVs and existing electricity consumption is therefore required. Recent research has shown that smart charging of EVs could improve the synergy between PV, EVs and electricity consumption, leading to both technical and economic advantages. Considering the growing interest in this field, this review paper summarizes state-of-the-art studies of smart charging considering PV power production and electricity consumption. The main aspects of smart charging reviewed are objectives, configurations, algorithms and mathematical models. Various charging objectives, such as increasing PV utilization and reducing peak loads and charging cost, are reviewed in this paper. The different charging control configurations, i.e., centralized and distributed, along with various spatial configurations, e.g., houses and workplaces, are also discussed. After that, the commonly employed optimization techniques and rule-based algorithms for smart charging are reviewed. Further research should focus on finding optimal trade-offs between simplicity and performance of smart charging schemes in terms of control configuration, charging algorithms, as well as the inclusion of PV power and load forecast in order to make the schemes suitable for practical implementations.
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| 7. |
- Alnadish, Adham Mohammed, et al.
(författare)
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A bibliometric analysis and review on the performance of polymer-modified bitumen
- 2023
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Ingår i: Frontiers in Materials. - : Frontiers Media S.A.. - 2296-8016. ; 10
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Forskningsöversikt (refereegranskat)abstract
- The addition of polymer to a base binder has been documented as a successful approach in terms of improving physical and rheological properties of the base bitumen. However, the main drawbacks of polymer-modified bitumen are incompatibility and degradation of polymer due to aging. This article aims to introduce a bibliometric analysis and review on modifying bitumen with polymers. Additionally, this article intent to highlight the significant gaps and recommendations for future work. Furthermore, another objective of this article is to provide a worth attempt regrading reducing the negative impact of polymer’s drawbacks on the performance of polymer-modified base binder. The findings of this article demonstrated that the test of storage stability for polymer-amended bitumen should be modified, in which the softening point of aluminum tube centerpiece should be measured to introduce a better evaluation for the storage stability of polymer-amended bitumen. In addition, the effects of kinetic factors (mixing sequence, viscosity of blend, shear rate, and time of mixing) on the compatibility of polymer-amended bitumen should be investigated. Moreover, the addition of compatibilizers and stabilizers to polymer-modified binder is recommended to improve compatibility and reduce the effect of aging on degradation of polymer.
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| 8. |
- Amran, Mugahed, et al.
(författare)
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Shrinkage mitigation in alkali-activated composites: A comprehensive insight into the potential applications for sustainable construction
- 2023
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Ingår i: Results in Engineering (RINENG). - : Elsevier. - 2590-1230. ; 20
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Forskningsöversikt (refereegranskat)abstract
- The extant body of literature articulates a noticeable disparity in the susceptibility to cracking and concomitant material degradation between alkali-activated composites (AAC) and ordinary Portland cement (OPC), predominantly attributable to shrinkage and subsequent drying phenomena. This divergence derives from the nanoscopic porosity of AAC binders, which is substantially finer than their OPC counterparts. However, experimental research validates that the judicious incorporation of alternative cementitious materials and fibrous reinforcements enriches the shrinkage characteristics of AAC, thereby enhancing its overall structural performance. Given the crucial role of shrinkage in defining the material integrity of AAC, especially under constrained environmental conditions, an in-depth understanding of shrinkage mechanisms materializes as a necessity for conceiving efficient shrinkage-mitigating strategies. In light of the growing interest in optimizing AAC through various material integrations and methodological innovations aimed at shrinkage diminution, this scholarly review undertakes an extensive synthesis of the laboratorial investigations focused on AAC shrinkage behavior and mitigation. However, this article critically evaluates widespread strategies for shrinkage mitigation, explicating their operative mechanisms. Moreover, it is outlined gaps in the existing research paradigm, promoting for targeted scholarly endeavors to yield a more clear understanding of shrinkage dynamics and to facilitate the advancement of environmentally sustainable AAC composites. Meanwhile, this study intended to consolidate existing research on developing trends in order to gain a comprehensive understanding of the possible uses of AACs and identify viable strategies for addressing AAC shrinkages. By addressing the challenges related to micro-cracking and shrinkage, the long-term durability of AACs may be improved, leading to increased adoption of these materials as sustainable building options in the construction industry today.
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| 9. |
- Esmaeilikia, Mahsa, et al.
(författare)
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Bicycle helmets and risky behaviour : A systematic review
- 2019
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Ingår i: Transportation Research Part F. - : Elsevier BV. - 1369-8478 .- 1873-5517. ; 60, s. 299-310
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Forskningsöversikt (refereegranskat)abstract
- A long-standing argument against bicycle helmet use is the risk compensation hypothesis, i.e., increased feelings of safety caused by wearing a helmet results in cyclists exhibiting more risky behaviour. However, past studies have found helmet wearing is not associated with risky behaviour, e.g., committing a traffic violation was positively associated with a lower frequency of helmet use. There is a lack of consensus in the research literature regarding bicycle helmet use and the risk compensation hypothesis, although this gap in knowledge was identified in the early 2000s. This is the first study to carry out a systematic review of the literature to assess whether helmet wearing is associated with risky behaviour. Two study authors systematically searched the peer-reviewed literature using five research databases (EMBASE, MEDLINE, COMPENDEX, SCOPUS, and WEB OF SCIENCE) and identified 141 unique articles and four articles from other sources. Twenty-three articles met inclusion criteria and their findings were summarised. Eighteen studies found no supportive evidence helmet use was positively associated with risky behaviour, while three studies provided mixed findings, i.e., results for and against the hypothesis. For many of these studies, bicycle helmet wearing was associated with safer cycling behaviour. Only two studies conducted from the same research lab provided evidence to support the risk compensation hypothesis. In sum, this systematic review found little to no support for the hypothesis bicycle helmet use is associated with engaging in risky behaviour.
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| 10. |
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