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585 result(s) for "Chen, Hanlin"
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Vertical tearing of subducting plates controlled by geometry and rheology of oceanic plates
Lateral non-uniform subduction is impacted by continuous plate segmentation owing to vertical tearing of the subducting plate. However, the dynamics and physical controls of vertical tearing remain controversial. Here, we employed 3D numerical models to investigate the effects of trench geometry (offset by a transform boundary) and plate rheology (plate age and the magnitude of brittle/plastic strain weakening) on the evolution of shear stress-controlled vertical tearing within a homogenous subducting oceanic plate. Numerical results suggest that the trench offset geometry could result in self-sustained vertical tearing as a narrow shear zone within the intact subducting oceanic plate, and that this process of tearing could operate throughout the entire subduction process. Further, the critical trench offset length for the maturation of vertical tearing is impacted by plate rheology. Comparison between numerical modelling results and natural observations suggests that vertical tearing attributed to trench offset geometry is broadly developed in modern subduction and collision systems worldwide. Vertical tearing promotes continuous segmentation of subducting plates, but its dynamics and physical controls remain debated. This work indicates that trench geometry and plate rheology control the self-sustained process of vertical tearing.
Olefin metathesis-based chemically recyclable polymers enabled by fused-ring monomers
A promising solution to address the challenges in plastics sustainability is to replace current polymers with chemically recyclable ones that can depolymerize into their constituent monomers to enable the circular use of materials. Despite some progress, few depolymerizable polymers exhibit the desirable thermal stability and strong mechanical properties of traditional polymers. Here we report a series of chemically recyclable polymers that show excellent thermal stability (decomposition temperature >370 °C) and tunable mechanical properties. The polymers are formed through ring-opening metathesis polymerization of cyclooctene with a trans-cyclobutane installed at the 5 and 6 positions. The additional ring converts the non-depolymerizable polycyclooctene into a depolymerizable polymer by reducing the ring strain energy in the monomer (from 8.2 kcal mol–1 in unsubstituted cyclooctene to 4.9 kcal mol–1 in the fused ring). The fused-ring monomer enables a broad scope of functionalities to be incorporated, providing access to chemically recyclable elastomers and plastics that show promise as next-generation sustainable materials.Depolymerizable polymers can potentially address challenges in polymer sustainability, but most existing systems lack the useful thermomechanical properties of traditional ones. Now, it has been shown that depolymerizable polymers based on olefin metathesis show good thermal stability as well as versatile mechanical properties and that the monomers used to make them can be prepared from abundant materials.
Explainable machine learning methods for predicting electricity consumption in a long distance crude oil pipeline
Accurate prediction of electricity consumption in crude oil pipeline transportation is of significant importance for optimizing energy utilization, and controlling pipeline transportation costs. Currently, traditional machine learning algorithms exhibit several limitations in predicting electricity consumption. For example, these traditional algorithms have insufficient consideration of the factors affecting the electricity consumption of crude oil pipelines, limited ability to extract the nonlinear features of the electricity consumption-related factors, insufficient prediction accuracy, lack of deployment in real pipeline settings, and lack of interpretability of the prediction model. To address these issues, this study proposes a novel electricity consumption prediction model based on the integration of Grid Search (GS) and Extreme Gradient Boosting (XGBoost). Compared to other hyperparameter optimization methods, the GS approach enables exploration of a globally optimal solution by exhaustively evaluating all hyperparameter combinations, thereby enhancing the model's predictive performance. To improve the interpretability of the model's predictions, SHapley Additive exPlanations (SHAP) is employed to quantify the contribution of input parameters to the model's predictive outcomes. Experimental results demonstrate that the GS-XGBoost hybrid model outperforms Multilayer Perceptron, Support Vector Machine, Extreme Learning Machine, Random Forest, and Gradient Boosting Regression Tree, achieving the best predictive performance with mean absolute percentage error (MAPE) and coefficient of determination (R ) values of 4.1% and 0.98, respectively. SHAP analysis identifies the key determinants of electricity consumption in descending order of importance: daily transport volume, average pump-out pressure, next station inlet pressure, average converging pressure, ground temperature, next station inlet temperature, and average output temperature. The proposed model holds substantial practical significance for improving energy utilization efficiency, optimizing cost management, and accelerating digital transformation in pipeline operations.
Early Permian Tarim Large Igneous Province in northwest China
Tarim Large Igneous Province (TLIP) is the second Late Paleozoic LIPs in China after the recognition of Emeishan LIP, and is a hot research topic in geosciences. On the basis of the analysis of research history about TLIP, this paper summarizes the re- search result during last twenty years and suggests the key research area in the future. The residual distribution range of TLIP is up to 250000 km2, and the largest residual thickness is 780 m. The eruption of basalt happened during 290-288 Ma and be- longs to LIPs magmatic event with fast eruption of magma. The lithological units of the TLIP include basalt, diabase, layered intrusive rock, breccia pipe mica-olivine pyroxenite, olivine pyroxenite, gabbro, ultramafic dyke, quartz syenite, quartz syenite porphyry and bimodal dyke. The basalt and diabase of TLIP exhibit OIB-like trace element patterns and enrichment of LILE and HFSE, and mainly belong to high TiO2 series. There is an obvious difference in isotope among the basalt from Keping and the basalt and dibase from the northern Tarim Basin. The basalt from Keping with negative eNa and high REE value derives from enriched mantle, and the diabase and basalt from the northern Tarim Basin with positive ENa and low REE value axe re- lated to depleted mantle. The crust uplifting in the Early Permian and the development of picrite and large scale dyke and for- mation of large scale V-Ti-Magnetite deposit in Wajilitag area support the view that the TLIP is related to mantle plume. The TLIP has a temporal-spatial relationship with Permian basic to ultra-basic igneous rock, which is distributed widely in Central Asia, and they represent a tectono-magmatic event with very important geodynamic setting. This paper also suggests that the deep geological process, the relation with mantle plume, mineralization, the relation with environmental change and biological evolution, and the geodynamics of the TLIP will be the key research topics in the future.
Geometry and kinematic evolution of the Hotan-Tiklik segment of the western Kunlun thrust belt; constrained by structural analyses and apatite fission track thermochronology
The western Kunlun thrust belt defines the boundary between the stable Tarim Basin in the north and the intensely deformed Cenozoic Tibetan Plateau in the south. Because of its important tectonic position, understanding its tectonic evolution should have important implications for propagation of deformation from Tibet to its neighboring cratonal regions during India-Eurasia convergence. We here present new structural analyses based on field investigations and seismic reflection profiles across the Hotan-Tiklik segment of the western Kunlun thrust belt. The results indicate that the structural section crosses two major thrust zones: the Tiklik zone in the hinterland to the south and the Hotan zone in the foreland to the north. Within these, the Hotan thrust zone is thin skinned, with its deformation characterized by fault-bend folding and fault slipping along detachment layers, whereas the Tiklik thrust zone involves basement, with its deformation driven by the currently steeply dipping Tiklik fault. Results from apatite fission track thermochronology in combination with growth strata and balanced cross section indicate that the Hotan-Tiklik segment underwent two-stage deformation: (1) development of the Tiklik thrust during the late Oligocene–early Miocene and again since the mid- to late Miocene and (2) activity of the Hotan thrust since the mid- to late Miocene as a result of basinward propagation of thrusting. The balanced cross section, combined with the apatite fission track results, suggests that the Hotan-Tiklik segment contributes a total shortening magnitude of more than ca. 34 ± 6 km. Within this, ca. 4 ± 2 and ca. 23 ± 1 km of the shortenings were absorbed by the Hotan anticline and the Hotan detachment fault, respectively, both of which were related to detachment layers. This suggests that detachment layers played an efficient role in propagating deformation from the western Tibetan Plateau into the Tarim Basin.
Uplift history of the Eastern Pamir inferred from inversion of thermochronometric data and river profile
The Pamir salient accommodates a great amount of Cenozoic India-Eurasia convergence in the forms of thrusting, strike-slip faulting, extension, and gneiss dome formation. It thus becomes a key location for exploring the orogenic tectonic evolution. Here, we focus on the Eastern Pamir where extensional deformation dominates during the late Cenozoic. We conducted low-temperature thermochronological dating on bedrock samples collected from the footwall of the Kongur Shan normal fault together with inversion of the longitudinal river profile of the Gez River. Our new zircon and apatite (U-Th)/He (ZHe and AHe) data reveal young ages in proximity to the normal fault and older ages adjacent to the western Tarim Basin. By inverting the Gez River profile together with published and new thermochronological ages, we obtained a sustained uplift rate of ∼3 mm/yr in the Kongur Shan dome since ∼8 Ma, contrasting with no significant uplift to the east of the dome before the Pliocene. This uplift pattern can be interpreted as a result of the upward extrusion of crust materials along a flat-ramp-flat thrust fault at depth under the context of convergence.
Reconciling patterns of long-term topographic growth with coseismic uplift by synchronous duplex thrusting
How long-term changes in surface topography relate to coseismic uplift is key to understanding the creation of high elevations along active mountain fronts, and remains hotly debated. Here we investigate this link by modeling the development of growth strata and the folding of river terraces above the Pishan duplex system in the southern Tarim Basin. We show that synchronous duplex thrusting of two neighboring faults with varying slip rates, associated with in-sequence propagation of the Pishan thrust system, is required to explain the presence of opposite-dipping panels of growth strata on the duplex front, and basinward migration of terrace fold crests. Importantly, this process of synchronous thrusting within the duplex reconciles the discrepancy between the deformation of terrace folds at the 10 −1 –10 0 million-year timescale and the maximum coseismic uplift of the 2015 M w 6.4 Pishan earthquake on the frontal thrust. These results suggest that topography mismatch at different time scales can reflect the long-term kinematic evolution of fault systems. Thus, our study highlights the importance of characterizing complex subsurface fault kinematics for studying topographic growth, and motivates rethinking of the mountain building process in worldwide active fold-and-thrust belts, from short-term to long-term timescales. Deciphering the relationship between prolonged topographic growth and temporary earthquake uplift is challenging due to the mismatch in their deformation patterns. Zhang et al. introduce a novel model to address this highly hotly-debated discrepancy.
A Hierarchical Motion Planning Method for Mobile Manipulator
This paper focuses on motion planning for mobile manipulators, which includes planning for both the mobile base and the manipulator. A hierarchical motion planner is proposed that allows the manipulator to change its configuration autonomously in real time as needed. The planner has two levels: global planning for the mobile base in two dimensions and local planning for both the mobile base and the manipulator in three dimensions. The planner first generates a path for the mobile base using an optimized A* algorithm. As the mobile base moves along the path with the manipulator configuration unchanged, potential collisions between the manipulator and the environment are checked using the environment data obtained from the on-board sensors. If the current manipulator configuration is in a potential collision, a new manipulator configuration is searched. A sampling-based heuristic algorithm is used to effectively find a collision-free configuration for the manipulator. The experimental results in simulation environments proved that our heuristic sampling-based algorithm outperforms the conservative random sampling-based method in terms of computation time, percentage of successful attempts, and the quality of the generated configuration. Compared with traditional methods, our motion planning method could deal with 3D obstacles, avoid large memory requirements, and does not require a long time to generate a global plan.
Plume‐Modified Lithosphere Mantle Controlled the Cenozoic Sediment Thickness in the Tarim Basin
The Cenozoic sediments are very thick in the southwest Tarim Basin and very thin in the northwest, but what controls these variations is unclear. Here, we use two‐dimensional thermo‐mechanical models to investigate how the lateral variations in rheological strength and depletion density of cratonic lithosphere mantle affect the cratonic basin deformation. Model results show that the basin basement uplift occurs above either the region with crustal thickening or high depletion in the mantle. A model with a stronger and density‐depleted northern half of cratonic lithosphere mantle in the context of compression matches the differential Cenozoic subsidence and deformation observed in the Tarim Basin well. We propose that a Permian plume led to the lateral heterogeneity of the lithosphere mantle under the Tarim craton, and the modified lithosphere mantle characteristics caused the differential Cenozoic sediment thickness in the Tarim Basin. Plain Language Summary Tarim Basin is a typical intraplate cratonic basin in northwest China. It is bounded by the West Kunlun Shan to the south and the Tian Shan to the north, respectively. The Cenozoic sediment thickness in the Tarim Basin displays significant lateral variation, which cannot be explained by flexural bending of the Tarim lithosphere under orogenic loads of the West Kunlun Shan and Tian Shan. Recent geophysical data outlined the extent of the Permian plume head, which coincides with the region covered by thinnest Cenozoic sediments. Here, we conduct a series of 2‐D thermo‐mechanical numerical simulations to examine the correlation of the cratonic lithosphere mantle characteristics with cratonic basin's basement geometry. Model results show that a craton with a stronger and density‐depleted northern half of lithosphere mantle in the context of compression matches well with the south‐north differential Cenozoic subsidence and deformation in the Tarim Basin. Accordingly, we suggest that the differential Cenozoic sediment thickness in the Tarim Basin was likely caused by the Permian plume‐modified lithosphere mantle. Our study indicates that the plume‐modified mantle characteristics play a critical role in the basement deformation of the above sediment basin. Key Points The strength and depletion density of cratonic lithosphere mantle control the deformation of cratonic lithosphere underlying sediment basin The differential Cenozoic sediment thickness in the Tarim Basin is related to the heterogeneity of cratonic lithosphere mantle The lithosphere mantle heterogeneity under the Tarim craton was likely caused by post‐Permian plume‐driven recratonization
Mechanochemically accessing a challenging-to-synthesize depolymerizable polymer
Polymers with low ceiling temperatures ( T c ) are highly desirable as they can depolymerize under mild conditions, but they typically suffer from demanding synthetic conditions and poor stability. We envision that this challenge can be addressed by developing high- T c polymers that can be converted into low- T c polymers on demand. Here, we demonstrate the mechanochemical generation of a low- T c polymer, poly(2,5-dihydrofuran) (PDHF), from an unsaturated polyether that contains cyclobutane-fused THF in each repeat unit. Upon mechanically induced cycloreversion of cyclobutane, each repeat unit generates three repeat units of PDHF. The resulting PDHF completely depolymerizes into 2,5-dihydrofuran in the presence of a ruthenium catalyst. The mechanochemical generation of the otherwise difficult-to-synthesize PDHF highlights the power of polymer mechanochemistry in accessing elusive structures. The concept of mechanochemically regulating the T c of polymers can be applied to develop next-generation sustainable plastics. Polymers with low ceiling temperatures (Tc) are highly desirable as they can depolymerize under mild conditions, but they typically suffer from demanding synthetic conditions and poor stability. Here, the authors envision that this challenge can be addressed by developing high-Tc polymers that can be converted into low-Tc polymers on demand.