| 1. |
- Kanai, M, et al.
(författare)
-
- 2023
-
swepub:Mat__t
|
|
| 2. |
- Niemi, MEK, et al.
(författare)
-
- 2021
-
swepub:Mat__t
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Turtelboom,, et al.
(författare)
-
The TESS-Keck Survey. XI. Mass Measurements for Four Transiting Sub-Neptunes Orbiting K Dwarf TOI-1246
- 2022
-
Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 163:6
-
Tidskriftsartikel (refereegranskat)abstract
- Multiplanet systems are valuable arenas for investigating exoplanet architectures and comparing planetary siblings. TOI-1246 is one such system, with a moderately bright K dwarf (V = 11.6, K = 9.9) and four transiting sub-Neptunes identified by TESS with orbital periods of 4.31, 5.90, 18.66, and 37.92 days. We collected 130 radial velocity observations with Keck/HIRES and TNG/HARPS-N to measure planet masses. We refit the 14 sectors of TESS photometry to refine planet radii (2.97 +/- 0.06 R (circle plus), 2.47 +/- 0.08 R (circle plus), 3.46 +/- 0.09 R (circle plus), and 3.72 +/- 0.16 R (circle plus)) and confirm the four planets. We find that TOI-1246 e is substantially more massive than the three inner planets (8.1 +/- 1.1 M (circle plus), 8.8 +/- 1.2 M (circle plus), 5.3 +/- 1.7 M (circle plus), and 14.8 +/- 2.3 M (circle plus)). The two outer planets, TOI-1246 d and TOI-1246 e, lie near to the 2:1 resonance (P (e)/P ( d ) = 2.03) and exhibit transit-timing variations. TOI-1246 is one of the brightest four-planet systems, making it amenable for continued observations. It is one of only five systems with measured masses and radii for all four transiting planets. The planet densities range from 0.70 +/- 0.24 to 3.21 +/- 0.44 g cm(-3), implying a range of bulk and atmospheric compositions. We also report a fifth planet candidate found in the RV data with a minimum mass of 25.6 +/- 3.6 M (circle plus). This planet candidate is exterior to TOI-1246 e, with a candidate period of 93.8 days, and we discuss the implications if it is confirmed to be planetary in nature.
|
|
| 7. |
- Karlsson, Oskar, et al.
(författare)
-
The human exposome and health in the Anthropocene
- 2021
-
Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 50:2, s. 378-389
-
Tidskriftsartikel (refereegranskat)
|
|
| 8. |
- Latham, John-Paul, et al.
(författare)
-
Modelling stress-dependent permeability in fractured rock including effects of propagating and bending fractures
- 2013
-
Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 57, s. 100-112
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of in-situ stresses on flow processes in fractured rock is investigated using a novelmodelling approach. The combined finite-discrete element method (FEMDEM) is used to model thedeformation of a fractured rock mass. The fracture wall displacements and aperture changes aremodelled in response to uniaxial and biaxial stress states. The resultant changes in flow properties ofthe rock mass are investigated using the Complex Systems Modelling Platform (CSMPþþ). CSMPþþisused to model single-phase flow through fractures with variable aperture and a permeable rock matrix.The study is based on a geological outcrop mapping of a low density fracture pattern that includes therealism of intersections, bends and segmented features. By applying far-field (boundary) stresses to asquare region, geologically important phenomena are modelled including fracture-dependent stressheterogeneity, the re-activation of pre-existing fractures (i.e. opening, closing and shearing), thepropagation of new fractures and the development of fault zones. Flow anisotropy is investigated undervarious applied stresses and matrix permeabilities. In-situ stress conditions that encourage a closing offractures together with a more pervasive matrix-dominated flow are identified. These are comparedwith conditions supporting more localised flow where fractures are prone to dilatational shearing andcan be more easily exploited by fluids. The natural fracture geometries modelled in this work are notperfectly straight, promoting fracture segments that dilate as they shear. We have demonstrated theintroduction of several realistic processes that have an influence on natural systems: fractures canpropagate with wing cracks; there is the potential for new fractures to connect with existing fractures,thus increasing the connectivity and flow; blocks can rotate when bounded by fractures, bent fractureslead to locally different aperture development; highly heterogeneous stress distributions emergenaturally. Results presented in this work provide a mechanically rigorous demonstration that a changein the stress state can cause reactivation of pre-existing fractures and channelling of flow in criticallystressed fractures.
|
|
| 9. |
- Moghadasi, Ramin, et al.
(författare)
-
Determining Gas Re-Mobilization and Critical Saturation : From Field Scale CO2 Injection Experiments to Pore-Scale Modelling
- 2022
-
Ingår i: Proceedings of the 16th Greenhouse Gas Control Technologies Conference (GHGT-16) 23-24 Oct 2022. - : Greenhouse Gas Control Technologies (GHGT).
-
Konferensbidrag (refereegranskat)abstract
- Residual trapping is a key mechanism in geological CO2 storage, which is quantitively characterized by residual gas saturation (Sgr). Remobilization of residually trapped CO2 can occur during pressure depletion, which can take place due to dissipation of near wellbore pressure build-up or any type of leakage. The occurrence of remobilization is characterized quantitively by critical gas saturation (Sgc). In this study, we present the first ever field-scale observations of trapped gas remobilization in the context of CO2 storage. We then present the preliminary results from pore-network modelling (PNM) study using a 3D network constructed from a series of X-ray computed tomography (CT) on Heletz sandstone. Our findings provide a multi-scale insight into the remobilization process in the context of CO2 storage and outline future work in terms of modelling the process to achieve a better assessment of stability of CO2 residual trapping in long-terms.
|
|
| 10. |
- Moghadasi, Ramin, et al.
(författare)
-
Determining residual gas remobilization and critical saturation in geological CO2 storage by pore-scale modelling
- 2022
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Remobilization of residually trapped CO2 as a result of pressure depletion occurs inherently at the pore-scale but affects the long-term stability of the residual trapping of CO2 at larger scales. In this study, pore-network modelling (PNM) is used to investigate this phenomenon under pressure depletion conditions. 3D networks of Bentheimer and Heletz sandstone as well as statistically generated generic 2D and 3D networks are used. The gas remobilization does occur at a higher gas saturation than residual saturation, so-called critical saturation. The difference is denoted as mobilization saturation, which varies according to the network properties (e.g., dimensionality) and the processes/mechanisms involved. Slightly smaller values are obtained for 3D networks due to the higher order of geometric connectivity between the pores and the effects of gravity. Regardless of the network types and properties, Ostwald ripening tends to slightly increase the mobilization saturation, thereby enhancing the security of residual trapping. Moreover, a significant hysteresis and reduction in gas relative permeability is observed during the depletion process, implying slow reconnection of the trapped gas clusters. These observations are safety enhancing features, due to which the remobilization of the residual trapped CO2 is delayed. The results, which are consistent with our previous analysis of field-scale Heletz experiments, have important implications for underground gas and CO2 storage. In the context of geological CO2 storage, they provide important insights into the fate of residual trapping in both the short and long term.
|
|
