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| 2. |
- Burgelman, Nico, et al.
(författare)
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Influence of wheel-rail contact modelling on vehicle dynamic simulation
- 2015
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:8, s. 1190-1203
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a comparison of four models of rolling contact used for online contact force evaluation in rail vehicle dynamics. Until now only a few wheel-rail contact models have been used for online simulation in multibody software (MBS). Many more models exist and their behaviour has been studied offline, but a comparative study of the mutual influence between the calculation of the creep forces and the simulated vehicle dynamics seems to be missing. Such a comparison would help researchers with the assessment of accuracy and calculation time. The contact methods investigated in this paper are FASTSIM, Linder, Kik-Piotrowski and Stripes. They are compared through a coupling between an MBS for the vehicle simulation and Matlab for the contact models. This way the influence of the creep force calculation on the vehicle simulation is investigated. More specifically this study focuses on the influence of the contact model on the simulation of the hunting motion and on the curving behaviour.
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| 3. |
- Ekberg, Anders, 1967, et al.
(författare)
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INNOTRACK Deliverable 4.2.1 -- Simplified relation for the influence of rail/joint degradation on operational loads and subsequent deterioration
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this tentative report we present a summary of the work carried out during approximately the first nine months of the INNOTRACK project regarding the influence of rail/joint degradation on operational loads and subsequent deterioration. The focus is here on the vertical train–track interaction and related deterioration.The work within this field can be divided in two categories. The first concerns the collection of input and validation data. In this category the current deliverable includes measurements of in-field axle loads, in-field monitoring of squats and compilation of material data.The second category is the actual numerical simulation and resulting quantifications of increased operational loads and deteriorations. Here the deliverable includes a state-of-the-art study of the effect of material characteristics on material deterioration and the practical implications. Further, the deliverable contains reports of parametric studies of the influence of rail corrugation, the growth of larger rail cracks, the influence of the design of insulated joints and the influence of rail squats.
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| 4. |
- Ivo Achu, Nges, et al.
(författare)
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Physio-chemical pretreatments for improved methane potential of Miscanthus lutarioriparius
- 2016
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Ingår i: Fuel. - : Elsevier BV. - 1873-7153 .- 0016-2361. ; 166, s. 29-35
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Tidskriftsartikel (refereegranskat)abstract
- Bio-energy production from lignocelluloses biomass has gained a lot of interest in recent years. Miscanthus sp. are high lignocelluloses biomass yielding with relatively high carbohydrate content cultivable on different soils and under climatic conditions. However, the lignocellulosic nature means that cellulose and hemicellulose are cover by lignin network that might limit hydrolysis. In this study, physical pretreatments (size reduction), physiochemical (steam expulsion) and chemical pre-treatments (mild acid and alkaline) were investigated in a view to improve the anaerobic biodegradability of Miscanthus lutarioriparius for biogas production. Prior to the pretreatment and methane potential test, the compositional analyses of M. lutarioriparius was performed in order unveil the carbohydrate (cellulose and hemicelluloses), protein and lignin contents. From these analyses, the maximum theoretical methane potential was estimated. All pretreatments led to solubilisation of organic matter as was evidenced by increase dissolve COD and ammonium nitrogen. There was a positive correlation between dissolved COD and methane yields meanwhile a negative correlation was observed for reducing sugar and methane yields. The achieved methane yields ranged from 121 to 238 ml CH4/g VS. Steam explosion, 0.3 M NaOH treatment and 0.5 mm size reduction led to the highest increases in methane yields, which was in the order of 57% with regard to the untreated samples. These improvements resulted in 71% of theoretical methane yield of M. lutarioriparius. Alkaline pretreatment in particular also improve the rate of methane production as was evidenced by the fact that as high 15% of the final methane yield that was achieve on the first day as compared to only 3% for the untreated sample. Indeed, the time to reach 90% of the ultimate methane yield was reduced by 13 days following 0.3 M NaOH treatment. M. lutarioriparius may therefore represent an interesting candidate as a lignocellulosic feedstock for biogas production after suitable pretreatment. (C) 2015 Elsevier Ltd. All rights reserved.
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| 5. |
- LI, Chao, et al.
(författare)
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Changes in composition, cellulose degradability and biochemical methane potential of Miscanthus species during the growing season
- 2017
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524. ; 235, s. 389-395
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Tidskriftsartikel (refereegranskat)abstract
- The composition, cellulose degradability and biochemical methane potential (BMP) of M. sinensis, M. floridulus, Miscanthus × giganteus and M. lutarioriparius were investigated concomitantly at different growth/harvest times during their growing season. For all the four species, there was only a slight change in the compositional content. Meanwhile there was a huge change in the BMP values. At the growth time of 60 days the BMPs ranged from 247.1 to 266.5 ml g−1 VS. As growth time was prolonged, the BMPs decreased by 11–35%. For each species, the BMP was positively correlated to the cellulose degradability with the correlation coefficients (R2) ranging from 0.8055 to 0.9925. This suggests that besides the biomass yield, it is justifiable to consider cellulose degradability when selecting the suitable harvest time for biofuels production from Miscanthus, especially in tropical and subtropical regions where Miscanthus can be harvested twice or more within a year.
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| 6. |
- Li, Yuanyuan, et al.
(författare)
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Active sites of atomically dispersed Pt supported on Gd-doped ceria with improved low temperature performance for CO oxidation
- 2023
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 14:44, s. 12582-12588
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Tidskriftsartikel (refereegranskat)abstract
- “Single-atom” catalysts (SACs) have been the focus of intense research, due to debates about their reactivity and challenges toward determining and designing “single-atom” (SA) sites. To address the challenge, in this work, we designed Pt SACs supported on Gd-doped ceria (Pt/CGO), which showed improved activity for CO oxidation compared to its counterpart, Pt/ceria. The enhanced activity of Pt/CGO was associated with a new Pt SA site which appeared only in the Pt/CGO catalyst under CO pretreatment at elevated temperatures. Combined X-ray and optical spectroscopies revealed that, at this site, Pt was found to be d-electron rich and bridged with Gd-induced defects via an oxygen vacancy. As explained by density functional theory calculations, this site opened a new path via a dicarbonyl intermediate for CO oxidation with a greatly reduced energy barrier. These results provide guidance for rationally improving the catalytic properties of SA sites for oxidation reactions.
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| 7. |
- Li, Zili, et al.
(författare)
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INNOTRACK Deliverable 4.2.4 -- Improved model for loading and subsequent deterioration due to squats and corrugation
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this research a hybrid multibody-finite element model was developed and applied to the analyses of the initiation and growth of squats, and to the identification of the most influential parameters of squatting. The growth process of squats was postulated based on numerical simulation, and was subsequently validated by field monitoring. Further a critical size for small rail top geometrical defects to grow into squats has been derived and validated. This critical size may be directly applied to visual inspection and classification of squats so that false reporting of squats can be avoided. The critical size can be applied as a minimum action rule for preventive or early corrective maintenance actions, such as rail grinding. The model may also have the capability to relate the severity of some track short defects quantitatively to some measurement of the dynamic wheel-rail interaction at the defects so that automatic detection of the defects at their early stage is possible. Finally corrective and preventive measures against squats are discussed.
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| 8. |
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| 9. |
- Shen, Zhaoyan, et al.
(författare)
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A Multiagent Reinforcement Learning-Assisted Cache Cleaning Scheme for DM-SMR
- 2023
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Ingår i: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0278-0070 .- 1937-4151. ; 42:8, s. 2500-2513
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Tidskriftsartikel (refereegranskat)abstract
- To support nonsequential writes, persistent cache (PC) is constructed in drive managed SMR (DM-SMR) drive. However, PC cleaning introduces drastic performance degradation and enlarges tail latencies. In this article, we propose to utilize reinforcement learning (RL) to mitigate the longtail latency of PC cleaning. Our scheme uses the lightweight Q-learning method to monitor and learn the idle time of I/O workloads, based on which PC cleaning is intelligently guided, thus maximally exploit idle time between requests and hiding tail latency from normal requests. In addition, a multiagent RL scheme with clustering algorithm is adopted to further mitigate the tail latencies and adapt to variable workloads. We emulate a DM-SMR drive inside a Linux device driver to implement our proposed scheme. According to the experimental results, our scheme can effectively reduce the tail latency by 59.45% at the 99.9th percentile and the average latency by 48.75% compared with a typical shingled magnetic recording (SMR) design.
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| 10. |
- Ullrich, Detlev, et al.
(författare)
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INNOTRACK Deliverable D4.3.7, Innovative laboratory tests for rail steels – Final report
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a first thorough investigation of different laboratory tests for rail materials combined with numerical simulations and metallographic investigations. A specific methodology for the latter is given in the Appendix. Laboratory tests for new rail materials are desirable supplements to field tests in order to save time and money. Thus, less valuable products can be early withdrawn from expensive field tests. Within this work package, test conditions for laboratory tests of rail materials have been defined and compared to field conditions. Existing test equipment and evaluation methods of the WP partners have been exploited for the laboratory tests in order to find out the applicability to the pre-defined field conditions.The tests were performed at the SUROS twin disk test machine, at the VAS linear full-scale test rig and at DB full-scale roller rigs. The results were compared among other with respect to metallography and material deterioration.Subsequent numerical calculations showed that the full-scale tests more or less deviate systematically from the expected contact conditions due to bending of wheel and rail. In addition, predictions regarding RCF have been carried out and compared to test results.It is shown that twin disk tests as well as tests on a full-scale linear test rig are suitable for practical use. The tests on full-scale roller rigs failed due to the need for specific rail samples, which ultimately destroyed the fixtures during the tests. An evaluation of the different tests including a rough estimate of effort is given.
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