| 1. |
- Liu, Xiao, et al.
(författare)
-
Comparison study on LES combustion models in diffusion flame
- 2018
-
Ingår i: Harbin Gongcheng Daxue Xuebao/Journal of Harbin Engineering University. - 1006-7043. ; 39:3, s. 496-502
-
Tidskriftsartikel (refereegranskat)abstract
- This study comparatively analyzes the calculation performances of different large-eddy simulation (LES) combustion models in a diffused flame simulation to investigate the performances of different LES-turbulent combustion models. The flamelet/progress variable (FPV), partially stirred reactor (PaSR), and transport joint possibility density function (PDF) combustion model are adopted to perform a numerical simulation analysis for Flame D in the Sandia Lab. The comparison between the calculation results and the test data shows that the three models can properly simulate the diffused flame. The transport PDF model based on the Eulerian stochastic field method can realize better results, especially the forecast for the intermediate radicals (OH) and the pollutant emissions (NO). However, the calculation volume is huge. The calculation speed and precision of PaSR are acceptable. The FPV method can save much CPU time, and has great value in engineering applications.
|
|
| 2. |
- Liu, Xiao, et al.
(författare)
-
Investigation of transient ignition process in a cavity based scramjet combustor using combined ethylene injectors
- 2017
-
Ingår i: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 137, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- Large Eddy Simulation (LES) and experiment were employed to investigate the transient ignition and flame propagation process in a rearwall-expansion cavity scramjet combustor using combined fuel injection schemes. The compressible supersonic solver and three ethylene combustion mechanisms were first validated against experimental data and results show in reasonably good agreement. Fuel injection scheme combining transverse and direct injectors in the cavity provides a benefit mixture distribution and could achieve a successful ignition. Four stages are illustrated in detail from both experiment and LES. After forced ignition in the cavity, initial flame kernel propagates upstream towards the cavity front edge and ignites the mixture, which acts as a continuous pilot flame, and then propagates downstream along the cavity shear layer rapidly to the combustor exit. Cavity shear layer flame stabilization mode can be concluded from the heat release rate and local high temperature distribution during the combustion process.
|
|
| 3. |
- Wang, Tingsong, et al.
(författare)
-
Overbooking and delivery-delay-allowed strategies for container slot allocation
- 2019
-
Ingår i: Transportation Research Part E: Logistics and Transportation Review. - : Elsevier BV. - 1366-5545. ; 122, s. 433-447
-
Tidskriftsartikel (refereegranskat)abstract
- Due to uncontrollable markets and unreliable factors in liner container shipping industry, the deviation between the actual and estimated shipment demand of containers always exists, resulting in a waste of shipping capacity or unfulfilled shipping requirements. To tackle such a slot allocation problem, this paper proposes overbooking (OB) and delivery-postponed (DP) strategies to maximize profits. Then, two corresponding multi-period models are developed and solution algorithms are presented. Finally, several numerical experiments are carried on to show the applicability of the proposed models and solution algorithms. The results indicate that the OB and DP strategies can promote the profit.
|
|
| 4. |
- Xu, Hongtao, et al.
(författare)
-
Global patterns and drivers of post-fire vegetation productivity recovery
- 2024
-
Ingår i: NATURE GEOSCIENCE. - 1752-0894 .- 1752-0908.
-
Tidskriftsartikel (refereegranskat)abstract
- Wildfires cause critical shifts in ecosystem functions, such as dramatic reductions in vegetation productivity. However, how fast vegetation regains its pre-fire productivity levels and the key influencing factors remain poorly understood on a global scale. Here we present the global estimates of post-fire vegetation productivity recovery from 2004 to 2021 using gross primary productivity observations and related proxies at a spatial resolution of 10 km, employing a random forest model to identify the key factors influencing recovery time. Roughly 87% of burned vegetation regained pre-fire productivity levels within 2 years, with evergreen needleleaf forests and savannas displaying the lengthiest recovery periods. During the recovery phase, post-fire climate conditions, such as soil moisture, vapour pressure deficit and air temperature, had nonlinear impacts on recovery time globally. These climatic factors exhibited a dominant role in regional recovery time in similar to 89% of the globally assessed area. As climate aridity decreased, the areas where recovery time was dominated by soil moisture and vapour pressure deficit decreased, while the influence of temperature increased. Soil-moisture-dominated regions witnessed reduced proportions of promoting vegetation recovery as aridity decreased, whereas vapour pressure deficit and air-temperature-dominated regions saw an increase in such proportions. Regions with strong human interventions were associated with accelerated vegetation recovery compared with similar ecosystems with smaller human interventions. These findings had important implications for global carbon-cycle assessments and fire-management strategies.
|
|
| 5. |
- Zhou, Zheng, et al.
(författare)
-
Reduced intensity conditioning for acute myeloid leukemia using melphalan- vs busulfan-based regimens : a CIBMTR report
- 2020
-
Ingår i: Blood Advances. - : American Society of Hematology. - 2473-9529 .- 2473-9537. ; 4:13, s. 3180-3190
-
Tidskriftsartikel (refereegranskat)abstract
- There is a lack of large comparative study on the outcomes of reduced intensity conditioning (RIC) in acute myeloid leukemia (AML) transplantation using fludarabine/busulfan (FB) and fludarabine/melphalan (FM) regimens. Adult AML patients from Center for International Blood and Marrow Transplant Research who received first RIC allo-transplant between 2001 and 2015 were studied. Patients were excluded if they received cord blood or identical twin transplant, total body irradiation in conditioning, or graft-versus-host disease (GVHD) prophylaxis with in vitro T-cell depletion. Primary outcome was overall survival (OS), secondary end points were leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and GVHD. Multivariate survival model was used with adjustment for patient, leukemia, and transplant-related factors. A total of 622 patients received FM and 791 received FB RIC. Compared with FB, the FM group had fewer transplant in complete remission (CR), fewer matched sibling donors, and less usage of anti-thymocyte globulin or alemtuzumab. More patients in the FM group received marrow grafts and had transplantation before 2005. OS was significantly lower within the first 3 months posttransplant in the FM group (hazard ratio [HR] = 1.82, P < .001), but was marginally superior beyond 3 months (HR = 0.87, P = .05). LFS was better with FM compared with FB (HR = 0.89, P = .05). NRM was significantly increased in the FM group during the first 3 months of posttransplant (HR = 3.85, P < .001). Long-term relapse was lower with FM (HR = 0.65, P < .001). Analysis restricted to patients with CR showed comparable results. In conclusion, compared with FB, the FM RIC showed a marginally superior long-term OS and LFS and a lower relapse rate. A lower OS early posttransplant within 3 months was largely the result of a higher early NRM.
|
|
