| 1. |
- Liang, Xifeng, et al.
(författare)
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On the aerodynamic loads when a high speed train passes under an overhead bridge
- 2020
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 202
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Tidskriftsartikel (refereegranskat)abstract
- The aerodynamic loads on the overhead bridge bottom surface induced by train passage are reported in this paper. Both moving model test and numerical simulation approaches at the 1:20 scale are used. The numerical work is validated through both mesh independence tests and comparison with experimental data. Typical pressure variation curves are plotted and compared with previous studies. The peak pressure values’ dependence on the Reynolds number is considered through four sets of experiments with different train running speeds. The peak pressure coefficient distribution law for the bridge bottom surface is presented. Differences in the pressure distribution in different bridge bottom areas are explained based on more detailed flow field information. The influence of the bridge height on the aerodynamic load magnitude and time interval is presented. Moreover, the application of the CEN Standard to practical engineering issues is discussed.
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| 2. |
- Berndt, Sonja I., et al.
(författare)
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Meta-analysis of genome-wide association studies discovers multiple loci for chronic lymphocytic leukemia
- 2016
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Chronic lymphocytic leukemia (CLL) is a common lymphoid malignancy with strong heritability. To further understand the genetic susceptibility for CLL and identify common loci associated with risk, we conducted a meta-analysis of four genome-wide association studies (GWAS) composed of 3,100 cases and 7,667 controls with follow-up replication in 1,958 cases and 5,530 controls. Here we report three new loci at 3p24.1 (rs9880772, EOMES, P = 2.55 x 10(-11)), 6p25.2 (rs73718779, SERPINB6, P = 1.97 x 10(-8)) and 3q28 (rs9815073, LPP, P = 3.62 x 10(-8)), as well as a new independent SNP at the known 2q13 locus (rs9308731, BCL2L11, P = 1.00 x 10(-11)) in the combined analysis. We find suggestive evidence (P<5 x 10(-7)) for two additional new loci at 4q24 (rs10028805, BANK1, P = 7.19 x 10(-8)) and 3p22.2 (rs1274963, CSRNP1, P = 2.12 x 10(-7)). Pathway analyses of new and known CLL loci consistently show a strong role for apoptosis, providing further evidence for the importance of this biological pathway in CLL susceptibility.
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| 3. |
- Cerhan, James R., et al.
(författare)
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Genome-wide association study identifies multiple susceptibility loci for diffuse large B cell lymphoma
- 2014
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 46:11, s. 1233-1238
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Tidskriftsartikel (refereegranskat)abstract
- Diffuse large B cell lymphoma (DLBCL) is the most common lymphoma subtype and is clinically aggressive. To identify genetic susceptibility loci for DLBCL, we conducted a meta-analysis of 3 new genome-wide association studies (GWAS) and 1 previous scan, totaling 3,857 cases and 7,666 controls of European ancestry, with additional genotyping of 9 promising SNPs in 1,359 cases and 4,557 controls. In our multi-stage analysis, five independent SNPs in four loci achieved genome-wide significance marked by rs116446171 at 6p25.3 (EXOC2; P = 2.33 x 10(-21)), rs2523607 at 6p21.33 (HLA-B; P = 2.40 x 10(-10)), rs79480871 at 2p23.3 (NCOA1; P = 4.23 x 10(-8)) and two independent SNPs, rs13255292 and rs4733601, at 8q24.21 (PVT1; P = 9.98 x 10(-13) and 3.63 x 10(-11), respectively). These data provide substantial new evidence for genetic susceptibility to this B cell malignancy and point to pathways involved in immune recognition and immune function in the pathogenesis of DLBCL.
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| 4. |
- Chen, Guang, et al.
(författare)
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Dynamic analysis of the effect of nose length on train aerodynamic performance
- 2019
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 184, s. 198-208
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Tidskriftsartikel (refereegranskat)abstract
- The improved delayed detached eddy simulation (IDDES) was used to study the influence of the train’s nose length on its aerodynamic performance. Both the time-averaged and instantaneous near-wake structures and the associated distribution of slipstream velocity are compared for three nose lengths. As the nose length increases, the mean and Std values of the drag and lift force are decreased. The shorter nose-length case results in a higher slipstream velocity. In particular, at the TSI track-side position, the TSI value U_2δ for the 5-m nose length case is 30% and 32% higher than the corresponding values for the 7.5-m and 10-m nose length cases, respectively. The dynamical flow topology in the wake reveals that the flow structures of the 5-m nose length are different from those of the other two cases in the tail streamline surface. As nose length increases, the longitudinal vortices are weaker, and the angle and distance between the longitudinal vortices are smaller. The shear production from the P_xy caused by the separation of the boundary layer at the lateral wall of the tail train is greater than that of the P_xz caused by the separation of the boundary layer at the top and bottom of the tail train.
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| 5. |
- Dong, Tianyun, et al.
(författare)
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Effects of simplifying train bogies on surrounding flow and aerodynamic forces
- 2019
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 191, s. 170-182
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Elsevier Ltd In this study, the numerical solution of a high-speed train with several simplified bogies is investigated. The time-averaged flow field around the train, the surface pressure, and the aerodynamic forces on the train are discussed. The results reveal that a simpler bogie structure can achieve a higher underbody flow velocity and change fluctuations beneath the train owing to the resulting turbulence level. The simplification of bogies has a smaller effect on the side slipstream velocity and pressure compare to which in underbody, and at 3 m away from the centre of the track, the simplified bogie with wheels and a simple side frame used in this study obtains similar results to cases wherein more complex bogies are used. The surface pressure under the train is affected by bogie simplification, especially in the bogie cabin end area, resulting in aerodynamic drag and lift variations. If underbody flow or aerodynamic drag and lift forces are the focus of study, then the geometry of the centre region of the bogie, i.e. its main structures features, should be maintained in simplified models.
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| 6. |
- Dong, Tianyun, 1990, et al.
(författare)
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Numerical investigation of a high-speed train underbody flows: Studying flow structures through large-eddy simulation and assessment of steady and unsteady Reynolds-averaged Navier-Stokes and improved delayed detached eddy simulation performance
- 2022
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Ingår i: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 34:1
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Tidskriftsartikel (refereegranskat)abstract
- The underbody flow of a truncated, 1:10 scaled, CRH380A model is investigated at Re = 2.78 × 105 in this paper. The large-eddy simulation (LES) is used to study the main features of the development of the underbody flow under the snowplow, in the bogie/cavity region and after the cavity (equip-cabin region). A grid independence study and a validation against experimental data have been done prior to the investigation. The snowplow region is dominated by a pair of separated counter-rotating vortices, which further affects the downstream flow. A strong shear layer is observed in the cavity region, and the turbulent flow is intensively triggered by the shear instability and the complex bogie components within the cavity region. The equip-cabin region allows the turbulent flow to develop without any disturbance, decreasing the turbulence intensity. Moreover, the steady and unsteady Reynolds-averaged Navier-Stokes (RANS, URANS) model and the improved delayed detached eddy simulation (IDDES) are used to compute the same flow, and to compare the results to LES. The solution differences, in terms of aerodynamic forces and the underbody flow state, are analyzed. Specifically, the minimum velocity discrepancy, at line2, between RANS (URANS) and LES is 14.4%, while IDDES is 3.6%. The solution accuracy vs the computational cost is also reported.
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| 7. |
- Dong, Tianyun, et al.
(författare)
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The effect of ground clearance on the aerodynamics of a generic high-speed train
- 2020
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Ingår i: Journal of Fluids and Structures. - : Elsevier BV. - 1095-8622 .- 0889-9746. ; 95
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Tidskriftsartikel (refereegranskat)abstract
- The influence of ground clearance on the flow around a simplified high-speed train is investigated in this paper. Four clearance heights are studied using IDDES. After a grid independence study, the results of the simulations are validated against experimental data present in the literature. It is found that the drag decreases when reducing the clearance gap from the baseline height to a possibly critical height, while drag remains constant when the clearance is lower than this critical height. The negative lift (downforce) increases with the decreasing of the clearance gap. The flow is particularly influenced by the gap height at the underbody and wake regions, where a lower underbody velocity and a higher wake velocity are observed with lower clearance down to case h2. Therefore, the different topologies of the wake are presented and described. Particular attention is paid to the description of the wake flow and to the position and the formation of the flow mixing region. Specifically, with decreasing clearance, the mix of the tail downwash and underbody flows happen earlier, and the core of the counter-rotating vortices in the wake tends to develop with an increasing height trend. Overall, aerodynamic performance and flow structure descriptions show positive and negative effects when decreasing gap clearances, which should be taken into account for new design strategies.
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| 8. |
- Dong, Tianyun, et al.
(författare)
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The effect of reducing the underbody clearance on the aerodynamics of a high-speed train
- 2020
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Ingår i: Journal of Wind Engineering and Industrial Aerodynamics. - : Elsevier BV. - 0167-6105. ; 204
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Tidskriftsartikel (refereegranskat)abstract
- The effect of lowering the ground clearance, on train aerodynamics is investigated using IDDES. The high speed train geometry with its full underbody complexity is used in the investigation. The clearance is reduced by installing extra panels on the track. The numerical results are verified and validated by a grid independence study and experimental data. This work shows that, when lowered the clearance, the underbody velocity at the head car decreases, while the underbody velocity at the middle and tail car increases. The reduced clearance barely affects the time-averaged slipstream at 3 m away from the center of track. However, at a closer distance to the train body, the difference in velocity is observed to reach up to 50% between the two clearance configurations and the clearance has an opposite effect on the trackside and platform slipstream. Based on the analysis of ensemble-averaged slipstream, lowering the underbody clearance, the characteristic air speed at the trackside and platform height increases by 2.0% and 6.7%, respectively. The total drag is almost unaffected by the clearance, but the changed distribution of the drag indicates a larger drag depends on the bogie structure if longer grouped train is used. The total lift decreases 25.9% after the clearance is reduced. Specifically, 4.1% of the negative lift is increased at the head car, while the positive lift decreases 92.7% and 1.8% for the middle and tail car, respectively. Overall it is shown that reducing the underbody clearance barely affect the slipstream at standard positions, but affects more aerodynamic loads of the train.
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| 9. |
- Hollestelle, Antoinette, et al.
(författare)
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No clinical utility of KRAS variant rs61764370 for ovarian or breast cancer
- 2016
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Ingår i: Gynecologic Oncology. - : Elsevier BV. - 0090-8258 .- 1095-6859. ; 141:2, s. 386-401
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Tidskriftsartikel (refereegranskat)abstract
- Objective Clinical genetic testing is commercially available for rs61764370, an inherited variant residing in a KRAS 3′ UTR microRNA binding site, based on suggested associations with increased ovarian and breast cancer risk as well as with survival time. However, prior studies, emphasizing particular subgroups, were relatively small. Therefore, we comprehensively evaluated ovarian and breast cancer risks as well as clinical outcome associated with rs61764370. Methods Centralized genotyping and analysis were performed for 140,012 women enrolled in the Ovarian Cancer Association Consortium (15,357 ovarian cancer patients; 30,816 controls), the Breast Cancer Association Consortium (33,530 breast cancer patients; 37,640 controls), and the Consortium of Modifiers of BRCA1 and BRCA2 (14,765 BRCA1 and 7904 BRCA2 mutation carriers). Results We found no association with risk of ovarian cancer (OR = 0.99, 95% CI 0.94-1.04, p = 0.74) or breast cancer (OR = 0.98, 95% CI 0.94-1.01, p = 0.19) and results were consistent among mutation carriers (BRCA1, ovarian cancer HR = 1.09, 95% CI 0.97-1.23, p = 0.14, breast cancer HR = 1.04, 95% CI 0.97-1.12, p = 0.27; BRCA2, ovarian cancer HR = 0.89, 95% CI 0.71-1.13, p = 0.34, breast cancer HR = 1.06, 95% CI 0.94-1.19, p = 0.35). Null results were also obtained for associations with overall survival following ovarian cancer (HR = 0.94, 95% CI 0.83-1.07, p = 0.38), breast cancer (HR = 0.96, 95% CI 0.87-1.06, p = 0.38), and all other previously-reported associations. Conclusions rs61764370 is not associated with risk of ovarian or breast cancer nor with clinical outcome for patients with these cancers. Therefore, genotyping this variant has no clinical utility related to the prediction or management of these cancers.
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| 10. |
- Liu, Tanghong, 1976, et al.
(författare)
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Wave effects in a realistic tunnel induced by the passage of high-speed trains
- 2019
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Ingår i: Tunnelling and Underground Space Technology. - : Elsevier BV. - 0886-7798. ; 86, s. 224-235
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Tidskriftsartikel (refereegranskat)abstract
- As a high-speed train passes through a tunnel, aerodynamic pressure waves propagate backwards and forward in the tunnel, and they persist for a long time after the train is gone. Understanding the aerodynamic characteristics influenced by various factors on a tunnel is essential for ensuring the safety of tunnel structures. Field measurements were conducted in a 2812 m-long tunnel to systematically investigate the pressure characteristics during the passage of CRH2-150C and CRH380AL high-speed trains through the tunnel, both in single-train and intersecting cases. The results reveal that as the train speed increases, the location of the maximum peak-to-peak pressure variation shifts toward the tunnel entrance, mainly driven by the change in the negative pressure peak. The train length induces significant differences in peak pressures on the tunnel wall in the middle of the tunnel, and a long train brings more massive subsequent pressure waves than a short train in the post-train stage, but they decay faster. The intersection of two trains in the tunnel not only causes a significant change in the peak pressure and its location, but also has a significant effect on damage factor (the damage level on a structure subjected to a specific load) after train leaving the tunnel, with a 65.3% of this factor during trains operating in the tunnel.
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