| 1. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Leebens-Mack, James H., et al.
(författare)
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One thousand plant transcriptomes and the phylogenomics of green plants
- 2019
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 574:7780, s. 679-
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Tidskriftsartikel (refereegranskat)abstract
- Green plants (Viridiplantae) include around 450,000-500,000 species(1,2) of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida), including green plants (Viridiplantae), glaucophytes (Glaucophyta) and red algae (Rhodophyta). Our analysis provides a robust phylogenomic framework for examining the evolution of green plants. Most inferred species relationships are well supported across multiple species tree and supermatrix analyses, but discordance among plastid and nuclear gene trees at a few important nodes highlights the complexity of plant genome evolution, including polyploidy, periods of rapid speciation, and extinction. Incomplete sorting of ancestral variation, polyploidization and massive expansions of gene families punctuate the evolutionary history of green plants. Notably, we find that large expansions of gene families preceded the origins of green plants, land plants and vascular plants, whereas whole-genome duplications are inferred to have occurred repeatedly throughout the evolution of flowering plants and ferns. The increasing availability of high-quality plant genome sequences and advances in functional genomics are enabling research on genome evolution across the green tree of life.
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| 3. |
- Balieu, Romain, et al.
(författare)
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Life Cycle Sustainability Assessment of Electrified Road Systems
- 2019
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Ingår i: ROAD MATERIALS AND PAVEMENT DESIGN. - Abingdon, UK : Taylor & Francis. - 1468-0629 .- 2164-7402. ; 20:sup1, s. S19-S33
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Tidskriftsartikel (refereegranskat)abstract
- The widespread use of Electric Vehicles (EVs) has been one of the main directionsfor pursuing a sustainable future of road transport in which, the deployment ofthe associated charging infrastructures, static or dynamic, has been included as oneof the main cornerstones for its success. Different electrified road (eRoad) systemswhich allow for dynamic charging of EVs by transferring electrical power from theroad to the vehicle in-motion, either in a conductive or contactless way, are underactive investigation. One of the important tasks in feasibility analysis of suchinfrastructure is to quantitatively assess its environmental performance and, thus,the consequential influences to the sustainability of road electrification as a whole.Having this concern in mind, in this study, a systematic LCA study is carried out in which the environmental impacts from the different life cycle stages have beencalculated and compared among several promising eRoad systems. In a next step,suitable strategies can be accordingly made to minimize these impacts in a most effectiveway; and more importantly, the LCA results of this study can serve as one ofthe important bases for conducting a more comprehensive and objective evaluationof the potential environmental benefits EVs could bring.
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| 4. |
- Balieu, Romain, et al.
(författare)
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Multiplicative viscoelastic-viscoplastic damage-healing model for asphalt-concrete materials
- 2016
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Ingår i: RILEM Bookseries. - Dordrecht : Springer Netherlands. ; , s. 235-240
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Konferensbidrag (refereegranskat)abstract
- A viscoelastic-viscoplastic model based on a thermodynamic approach is developed under finite strain in this paper. By introducing a damage evolution, the proposed model is able to reproduce the behavior of Asphalt-Concrete materials until the complete fracture. Moreover, a recoverable part of the degradation is introduced to reproduce the self-healing observed under a sufficiently long rest period. The proposed model is implemented into a Finite Element code and good correlations between the numerical responses and the experiments have been observed.
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| 5. |
- Chen, Feng, 1987-, et al.
(författare)
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A state-of-the-art review of intrinsic and enhanced electrical properties of asphalt materials: theories, analyses and applications
- 2020
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Ingår i: Materials & design. - : Elsevier. - 0264-1275 .- 1873-4197. ; 195, s. 109067-
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Tidskriftsartikel (refereegranskat)abstract
- In pavement engineering, a variety of promising application technologies are found relying on a thorough understanding of the intrinsic (mainly dielectric) electrical properties of asphalt binder and concrete materials. Meanwhile, the electrical properties of asphalt materials can be further enhanced by introducing conductive additives into and it has been brought to light that, the electrically conductive asphalt is becoming an emerging subject of interest that caters to the concept of a multifunctional pavement future. In context of these, this paper presents a holistic overview of the intrinsic and enhanced electrical properties of asphalt materials, including the theoretical analyses, as well as the corresponding applications in the practice. From such a state-of-the-art review, it is worth noting that: i) an improved understanding of asphalt material has been achieved by an in-depth examination of its electrical properties; ii) the increased significance of the research domain as a whole and, the key importance of multidisciplinary collaborations for future successes, have been indicated.
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| 6. |
- Chen, Feng, 1987-, et al.
(författare)
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Dynamic application of the Inductive Power Transfer (IPT) systems in an electrified road : Dielectric power loss due to pavement materials
- 2017
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Ingår i: Construction and Building Materials. - : Elsevier. - 0950-0618 .- 1879-0526. ; 147, s. 9-16
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Tidskriftsartikel (refereegranskat)abstract
- Inductive Power Transfer (IPT) technology is seen as a promising solution to be applied in an electrified road (eRoad) to charge Electric Vehicles (EVs) dynamically, i.e. while they are in motion. Focus in this study was placed on the dielectric loss effect of pavement surfacing materials on the inductive power transfer efficiency, induced after the integration of the technology into the physical road structure. A combined experimental and model prediction analysis was carried out to calculate this dielectric loss magnitude, based on which some preliminary conclusions as well as a prioritization of future focus needs were summarized in detail.
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| 7. |
- Chen, Feng, 1987-, et al.
(författare)
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Electrification of Roads : Opportunities and Challenges
- 2015
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 150, s. 109-119
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Tidskriftsartikel (refereegranskat)abstract
- The Electrical Vehicle (EV) has become a potential solution for enhancing the sustainability of our road transportation, in view of the environmental impacts traditional vehicles have regarding emissions and use of fossil fuel dependence. However, the widespread use of EVs is still restrained by the energy storage technologies, and the electrification of road transportation is still in its early stages. This paper focuses on the technical aspects related to the ‘electrification of roads’ (called ‘eRoads’) infrastructure that aims to diminish the limitations for using EVs. A historical overview of the technology development towards the electrification of road transportation is presented, along with an overview of prospective technologies for implementing an eRoad charging infrastructure. Of these, the Inductive Power Transfer (IPT) technology is examined in further details. The main objective of this paper is to explore the potential knowledge gaps that need to be filled for a successful integration of IPT technology within actual road infrastructure. As such, this paper can be used as an overview of the current state-of-the-art of eRoad infrastructure and also as guidance towards future research directions in this domain.
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| 8. |
- Chen, Feng, 1987-, et al.
(författare)
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Experimental and numerical analysis of asphalt flow in a slump test
- 2019
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Ingår i: International Journal on Road Materials and Pavement Design. - : Taylor & Francis. - 1468-0629 .- 2164-7402. ; 20, s. S446-S461
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical behaviour of uncompacted asphalt mixtures is still not well understood,threatening directly to the pavement practices such as control of mixture’s workability andsegregation. This situation may become even worse due to the gradually increasing complexityand advances in paving materials and technologies. This study adopts a slump flow testbased on concrete technology and a Discrete Element (DE)-based numerical tool to investigatethe mechanical behaviour of uncompacted asphalt mixture from a microstructural point ofview, particularly focusing on the bituminous binder effects. The combined experimental andnumerical analysis indicates that bitumen distinctly influences the contact interactions withinthe mixture and thus its macroscopic flow, which can be physically interpreted as a combinedeffect of lubricated friction and bonding force. Additional case studies demonstrate that the DEmodel is capable of simulating the flow response of asphalt mixtures under changed particlecontact conditions and driven force.
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| 9. |
- Chen, Feng, 1987-
(författare)
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Inductive power transfer technology for road transport electrification
- 2020
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Ingår i: Eco-efficient Pavement Construction Materials. - : Elsevier Inc.. ; , s. 383-399
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The electrified road (eRoad) system, which allows for delivering electric power to electric vehicles (EVs) while driving, has gained worldwide interest as part of future EV-charging infrastructure network. Being one of the promising solutions in an eRoad application, the inductive power transfer technology has been under active investigation and many prototypes have been demonstrated in pilot test sites around the world. However, from the infrastructural point of view, the possible modifications of the road structural and material designs, the changes in construction and maintenance practices, and the unclear long-term environmental impacts are threatening its sustainable implementation. In order to tackle these emergent gaps, feasibility analyses are accordingly conducted in this study and, based on which, some practical recommendations are summarized.
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| 10. |
- Chen, Feng, 1987-, et al.
(författare)
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Structural performance of electrified roads: A computational analysis
- 2018
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 195, s. 1338-1349
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Tidskriftsartikel (refereegranskat)abstract
- Given its promise for enhanced sustainability, electrified road (eRoad) has become a realistic option to support the clean and energy efficient Electrical Vehicles (EVs). To investigate the structural implications, this study focuses on a promising eRoad system which is a dynamic application of the Inductive Power Transfer (IPT) to provide electrical power wirelessly to EVs in-motion. A computational study is made in which, via a series of Finite Element Modeling (FEM) analyses on the eRoad structural response under various rolling conditions, is found that eRoads could have quite different pavement performances comparing to the traditional road (tRoad). Importantly, harsh loading due to vehicle braking or accelerating could incur higher potential of premature damage to the structure, whereas sufficient bonding at the contact interfaces would improve the structural integrity and delay the damage risks. In addition, localized mechanical discontinuities could also be a critical threat to the performance of the overall structure. To ensure that eRoads fulfill their sustainability promise, it is thus recommended that more focus should be placed on the possible measures, such as new structures and materials, to improve the structural integrity and thus the overall pavement performance of the integrated system.
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| 11. |
- Chen, Feng, 1987-
(författare)
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Sustainable Implementation of Electrified Roads : Structural and Material Analyses
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Given the promise of the Inductive Power Transfer (IPT) technology for eRoad applications, the potential challenges for a successful integration of dynamic IPT technology into the physical road structure are explored extensively in this research work. The Finite Element Method (FEM) is selected for studying the structural performance of an eRoad under operational conditions. In this, an energy-based finite strain constitutive model for asphalt materials is developed and calibrated, to enable the detailed investigation of the structural response and optimization of the considered eRoad. In the context of enabling both dynamic charging and autonomous driving for future electric vehicles, the influences to the pavement (rutting) performance by the changed vehicle behaviour are investigated as well. Moreover, to study the effect on the IPT system by the integration, the potential power loss caused within eRoad pavement materials is further examined by a combined analytic and experimental analysis. The direct research goal of this Thesis is therefore to enhance the possibility of a sustainable implementation of the eRoad solutions into the real society. At the same time, it aims to demonstrate that the road structure itself is an important part of smart infrastructure systems that can either become a bottleneck or a vessel of opportunities, supporting the successful integration of these complex systems.
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| 12. |
- Chen, Feng, 1987-, et al.
(författare)
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Sustainable implementation of future smart road solutions: a case study on the electrified road
- 2017
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Ingår i: Proceedings of the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields (BCRRA 2017). - Athens, Greece : CRC Press. - 1351585789
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Konferensbidrag (refereegranskat)abstract
- An important feature of a future smart or multifunctional road is that an intrinsic integration of different new advances into the practical roads should be achieved, in terms of such as Car-to-Road communication, energy harvesting, autonomous driving or on-the-road charging. However, our current engineering and research communities do not necessarily allow for an optimal development of such integrated systems. To fill some of the knowledge gaps from infrastructure point of view, this research is focusing on a specific case of the electrified road (also called ‘eRoad’) that allows for on-the-road charging, in which the consequences and possible modifications of the road infrastructure are considered. Some preliminary analysis results are presented in this paper, from which it has been found that such kind of the integration could indeed influence the service performance of individual components of the whole system, while further studies should be carried out to ensure the implementation of these smart technologies is ultimately sustainable.
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| 13. |
- Chen, Feng, 1987-
(författare)
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The Future of Smart Road Infrastructure : A Case Study for the eRoad
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the future, physical roads will not only serve for the mobility of the vehicles but also have the capability of enabling different smart functionalities, such as car2road communication, energy harvesting or dynamic charging of electrical vehicles. To ensure the sustainability of these advances, the environmental, economic and social costs for the road infrastructure itself should not offset its possible advances. Additionally, the road infrastructure itself may also need to be modified to ensure the long-term performance of the new functionalities.This licentiate mainly focused on the electrified road (called ‘eRoad’) infrastructure, which can be a representative case of the future smart road. Specifically, a historical overview of the technology development towards the electrification of road transportation sector is presented, along with an overview of prospective technologies for implementing an eRoad’s charging infrastructure. Of these, the Inductive Power Transfer (IPT) charging technology is examined in further details.The potential knowledge gaps for a successful integration of IPT charging technology within actual road infrastructure are discussed. Some general recommendations are given throughout the licentiate thesis, regarding such as the appropriate design of eRoad structure and right selection of road materials, the cost-effective maintenance operations in the long term, and the eRoad’s role in the overall life cycle environmental impacts in the electrification of road transportation sector. This licentiate provides the basis for further focus in this field and outlines the potential research areas that need further investigation to ensure the future of systemically optimized smart road infrastructure.
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| 14. |
- Chen, Feng, 1987-, et al.
(författare)
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Thermodynamics-based finite strain viscoelastic-viscoplastic model coupled with damage for asphalt material
- 2017
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Ingår i: International Journal of Solids and Structures. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0020-7683 .- 1879-2146. ; 129, s. 61-73
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Tidskriftsartikel (refereegranskat)abstract
- A thermodynamics based thermo-viscoelastic-viscoplastic model coupled with damage using the finite strain framework suitable for asphalt material is proposed in this paper. A detailed procedure for model calibration and validation is presented, utilizing a set of experimental measurements such as creep recovery, constant creep, and repeated creep-recovery tests under different loading conditions. The calibrated constitutive model is able to predict the sophisticated time- and temperature-dependent responses of asphalt material, both in tension and in compression. Moreover, a scenario case study on permanent deformation (rutting) prediction of a practical asphalt pavement structure is presented in this work. This paper presents the main features of this new constitutive model for asphalt: (1) A thermodynamics-based framework developed in the large strain context to derive the specific viscoelastic, viscoplastic and damage constitutive equations; (2) A viscoelastic dissipation potential involving deviatoric and volumetric parts, in which Prony series representations of the Lame constants are used; (3) A modified Perzyna's type viscoplastic formulation with non-associated flow rule adopted to simulate the inelastic deformation, using a Drucker-Prager type plastic dissipation potential; (4) A specific damage model developed for capturing the evolution disparity between tension and compression. As such, the developed model presents a robust, fully coupled and validated constitutive framework that includes the major behavioral components of asphalt materials, enabling thus an optimized simulation of predicted performance under various conditions. Further development improvements to the model in continued research efforts can be to include further environmental and physico-chemical material behavior such as ageing, healing or moisture induced damage.
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| 15. |
- Chen, Feng, 1987-, et al.
(författare)
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Towards new infrastructure materials for on-the-road charging A study of potential materials, construction and maintenance
- 2014
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Ingår i: 2014 IEEE INTERNATIONAL ELECTRIC VEHICLE CONFERENCE (IEVC). - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- As a future-oriented industry, the electrified mobility has the potential to enhance the sustainability of our road transportation sector radically. With the aim to break the EV batteries' bottleneck (e.g., cost, range anxiety, long waiting time) by focusing not on the battery but on the solution to charge it conveniently, different on-the-road-charging solutions have been found under active investigation. From a road infrastructure perspective, however, little attention has been given to the practical, physical roads where these charging solutions will be enabled. In reality, good performance of E-Road infrastructure in aspects such as robustness, durability, cost-effectiveness will be crucial for the final success. Taking the Inductive Power Transfer (IPT) charging solution in a dynamic way as a basis, this paper mainly discusses about the physical infrastructural aspect i.e. the road infrastructural materials and the changed construction and maintenance principles. The paper aims to give developers in this field more awareness of the necessity and potential cross-coupling benefits from interdisciplinary collaboration, by taking the road infrastructure research into the concept development of E-Roads.
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| 16. |
- Chen, Feng, 1987-, et al.
(författare)
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Vibration-induced aggregate segregation in asphalt mixtures
- 2020
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Ingår i: Materials and Structures. - : SPRINGER. - 1359-5997 .- 1871-6873. ; 53:2
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Tidskriftsartikel (refereegranskat)abstract
- Aggregate segregation in asphalt mixture is a bothersome engineering issue during pavement construction. The practitioners have some measures to mitigate the segregation potential based on experiences which, however, can only reduce the risk to a certain extent. In this research, the authors aim to contribute to the discussion in a rational non-empirical way, by using novel experimental and numerical techniques. A case study is carried out to investigate the vibration-induced segregation in asphalt mixtures, corresponding to the circumstance arising during material transportation to the construction site. A novel experimental test is conducted for evaluating the segregation characteristics of asphalt mixtures under vertical vibration in laboratory conditions. A numerical investigation based on discrete element method is further performed to study the phenomenon from a micromechanical point of view. The obtained experimental and numerical results indicate that vibratory loading induces aggregate size segregation in asphalt mixtures, and the degree of segregation is influenced profoundly by the adhesive properties of bituminous binders and the aggregate gradation.
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| 17. |
- Fadil, Hassan, et al.
(författare)
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The viscoelastic characterisation of asphalt mixtures using the indentation test
- 2021
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Ingår i: International Journal on Road Materials and Pavement Design. - : Informa UK Limited. - 1468-0629 .- 2164-7402. ; 22:sup1, s. S411-S424
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Tidskriftsartikel (refereegranskat)abstract
- Viscoelastic characterisation of asphalt mixtures is an important component for modelling and performance prediction of flexible pavements. In this study, using spherical indentation testing for measuring the viscoelastic properties of asphalt is explored. Indentation testing may provide an interesting alternative to existing experimental techniques, as it is capable of characterising small material volumes. Thus, it may become a useful tool for the characterisation of thin asphalt layers and for the measurement of binder phase properties in-situ in asphalt mixtures. Spherical indentation tests are performed on two mastic asphalt (MA) mixtures, prepared with different mastic types. The shear relaxation moduli obtained from the indentation tests are compared with the ones measured with seismic and SuperPave Indirect Tensile (IDT) tests. A new statistical analysis methodology is proposed for viscoelastic characterisation of the mastic phase with the indentation tests performed on MA mixtures. The accuracy and sensitivity of the developed method are examined.
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| 18. |
- Ledesma, Enrique Córdoba, et al.
(författare)
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Towards an understanding of the structural integrity of electrified roads through a combined numerical and experimental approach
- 2017
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Ingår i: TRB 96th Annual Meeting Compendium of Papers.
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Konferensbidrag (refereegranskat)abstract
- The continuous growth in road transportation demands further development towards sustainable strategies. The electrification of road infrastructure (commonly referred to as ‘e-Road’) to enable wireless charging solutions for Electric Vehicles (EVs) is arising as one of the most promising and yet challenging alternatives for the future mobility by road. In this context, the introduction of charging facilities in the pavement structure and its adequate performance from an infrastructural perspective is determining for the successful implementation of these systems.This study aims to evaluate the structural integrity of e-Roads, considering the embedment in the pavement of a solid module denominated ‘Charging Unit’ (CU) in which the charging facilities are assumed to be installed. To do so, the critical locations of an e-Road pavement structure were identified through computational modelling for its further representation as small-scale e-Road samples in the laboratory. Afterwards, this structure was subjected to different loading conditions using mechanical hydraulic devices and compared with conventional road samples produced under the same conditions. Finally, e-Road samples were scanned with X-ray Computed Tomography (CT) prior to, during and after loading for additional inspection. Results provided valuable learnings of the potential mechanisms of failure of such structure and a better understanding of the e-Road infrastructure.
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| 19. |
- Manni, Giovanni Li, et al.
(författare)
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The OpenMolcas Web : A Community-Driven Approach to Advancing Computational Chemistry
- 2023
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Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 19:20, s. 6933-6991
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Tidskriftsartikel (refereegranskat)abstract
- The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in the stable branch of the package or via interfaces with other packages. These developments span a wide range of topics in computational chemistry and are presented in thematic sections: electronic structure theory, electronic spectroscopy simulations, analytic gradients and molecular structure optimizations, ab initio molecular dynamics, and other new features. This report offers an overview of the chemical phenomena and processes OpenMolcas can address, while showing that OpenMolcas is an attractive platform for state-of-the-art atomistic computer simulations.
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| 20. |
- Olsson, Erik, 1986-, et al.
(författare)
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A numerical framework for modelling settlements of railway ballast layers
- 2024
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Ingår i: Transportation Geotechnics. - : Elsevier. - 2214-3912. ; 44
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Tidskriftsartikel (refereegranskat)abstract
- Permanent deformation in ballast layers is a major contributing factor to the railway track geometry deterioration. In spite of a considerable amount of research on understanding and predicting performance of ballast layers, accurately capturing their settlements remains a challenge. In order to contribute to solving this important issue, a new numerical method for predicting ballast settlements is presented in this paper. This method is based on the finite element (FE) method combined with a constitutive model that captures permanent deformation accumulation in unbound materials under cyclic loading. This allows predicting permanent deformations of large structures and at large number of load cycles in a computationally efficient manner.The developed constitutive model is validated based on triaxial test measurements over wide range of loading conditions. Stress state in ballast layers has been examined with a 3D FE model, for several embankment structures and traffic load magnitudes. The determined stress distributions and loading frequencies were used as an input of the constitutive model to evaluate permanent strains and settlements of ballast layer. The influence of embankment structural designs and traffic loading magnitudes on the ballast layers settlements is examined and the results obtained are compared with the existing empirical performance models.
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| 21. |
- Peng, Zuosheng, et al.
(författare)
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A dual ternary system for highly efficient ITO-free inverted polymer solar cells
- 2015
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 3:36, s. 18365-18371
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Tidskriftsartikel (refereegranskat)abstract
- In this study, it has been found that a very fine nanostructure can be realized by mixing 1-chloronaphthalene (CN) - a high-boiling solvent into a binary chlorobenzene (CB) : 1,8-diiodooctane (DIO) solvent mixture to form a ternary solvent system. An improvement in energy level alignment is also obtained by doping ICBA into a binary PTB7 : PCBM[70] blend, whereby the ternary solute system provides a new pathway for charge transfer from PTB7 to the PCBM[ 70] : ICBA alloy. This is confirmed by imaging the surface morphology of the active layer using AFM and TEM, monitoring the transient film formation process and measuring the charge transfer states with Fourier transform photocurrent spectroscopy. An encouraging PCE of 7.65% is achieved from the dual ternary system, which is the highest value ever reported for an ITO-free inverted polymer solar cell with a PEDOT:PSS layer as the top semitransparent electrode - a system which is compatible with low-cost large-area roll-to-roll manufacturing.
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| 22. |
- Sun, Guoqiang, et al.
(författare)
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Low temperature self-healing character of asphalt mixtures under different fatigue damage degrees
- 2019
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Ingår i: Construction and Building Materials. - : ELSEVIER SCI LTD. - 0950-0618 .- 1879-0526. ; 223, s. 870-882
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Tidskriftsartikel (refereegranskat)abstract
- The primary objective of this study is to advance the understanding of the low temperature self-healing character of asphalt mixtures under different damage degrees, thus to determine the effective strategy of asphalt pavement maintenance. Firstly, three kinds of asphalt mixtures are selected to conduct the indirect tensile (IDT) fatigue test to a certain fatigue damage degree at low temperatures, and then the resilient modulus (Mr) at different rest time is measured to quantify the healing potential. Next, the fatigue loading with different intermittent time (0 s, 1 s and 3 s) is applied to determine the impact of intermittent time on healing potential. The results indicate that the descending order of healing potential of asphalt mixtures is: SMA-11 > AC-8 > AC-11 at 5 degrees C and -5 degrees C. The loading intermittent time has an obvious effect on the fatigue damage state of asphalt mixtures, while the longer the intermittent time, the less the effect on fatigue damage healing. Besides, the fatigue damage state has great influence on its healing potential of asphalt mixture. Under the low damage conditions, the initial healing rate is greater than the long term healing rate. However, the low temperature (-5 degrees C) dramatically reduces the healing rate of asphalt mixtures, and causes their long-term healing rate to stabilize gradually to a very low level. Especially under the high fatigue damage conditions, the healing potential of asphalt mixtures will almost disappear at -5 degrees C. Furthermore, together with meso-scale Computed Tomography (CT) scanning technique, it is found that the intemal crack distribution characteristics of different graded asphalt mixtures are different even under the same damage degree, which may explain the differences in the healing potential of asphalt mixtures. The use of a fast two-dimensional (2D) scanning technology further confirms that the crack zones inside the asphalt mixture are gradually shrinking after a period of high temperature healing. Finally, the Grey relational analysis reveals that the healing time has the most significant influence on the healing potential of asphalt mixtures. The gradation type and temperature have the similar influence level on the healing potential. The correlation degree between the fatigue damage degree and healing potential is the smallest compared with the other three factors. All rights reserved.
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| 23. |
- Zhang, Xinhai, 1987-, et al.
(författare)
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Design-Space Reduction for Architectural Optimization of Automotive Embedded Systems
- 2015
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Ingår i: High Performance Computing and Communications (HPCC), 2015 IEEE 7th International Symposium on Cyberspace Safety and Security (CSS), 2015 IEEE 12th International Conferen on Embedded Software and Systems (ICESS), 2015 IEEE 17th International Conference on. - : IEEE Computer Society. ; , s. 1103-1109
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Konferensbidrag (refereegranskat)abstract
- A key decision for the synthesis of automotiveembedded systems is the allocation of application softwarecomponents to ECUs. Design Space Exploration (DSE) supportsthe decision by automatically characterizing and evaluating alarge number of possible design alternatives, and thereby suggestingthe optimal ones. A primary challenge for applying DSEmethods to support this decision is to reduce the computationtime of the DSE process while maintaining the generality andoptimality. This paper exploits legacy system architectures andthe AUTOSAR standard to preemptively reduce the design space,because both artifacts limit the flexibility of certain designvariables. A new DES formulation incorporating the constraintsof the legacy system architectures and the AUTOSAR standardis proposed in this paper. Computation result shows a largereduction of the computation time comparing to traditionalmodeling and formulations. The scalability of our method is alsoanalyzed by testing it on a set of random problem instances.
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| 24. |
- Zhu, Xinggyi, et al.
(författare)
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Effects of surface texture deterioration and wet surface conditions on asphalt runway skid resistance
- 2021
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Ingår i: Tribology International. - : Elsevier Ltd. - 0301-679X .- 1879-2464. ; 153
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Tidskriftsartikel (refereegranskat)abstract
- The friction force for aircraft landing is mainly provided by the texture of runway surfaces. The mechanism underlying friction force generation is the energy dissipation of tire rubber materials during random excitation induced by asperities. However, the runway surface texture is deteriorated by cyclic loading and environmental effects during the service life of a runway, leading to loss of braking force and extension of landing distance. Additionally, when an aircraft lands on a wet runway at a high velocity, the hydrodynamic force causes the tires to detach from the runway surface, which is risky and may lead to the loss of aircraft control and runway excursion. Worn-out surfaces along with wet conditions increase the risk of poor control during aircraft landing. Accordingly, this study investigated three types of asphalt runways (SMA-13, AC-13, and OGFC-13). Surface texture deterioration was simulated using a surface texture wear algorithm. Kinematic friction models were established based on the viscoelastic property of rubber materials, power spectrum density, and statistics of surface textures. A finite element model was developed by considering a real rough runway surface and different water film depths (3, 7, and 10 mm). A comparison of hydroplaning speed was conducted between numerical simulation and former experiments. The effects of different factors, such as velocity, wear ratio, runway type, water film depth, and slip ratio, on the skid resistance of the runway were analyzed.
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