7,054 research outputs found
Morphometric study of the benthic foraminiferal clade Gaudryina in an Oligocene-Miocene Series of the Kouhsing area in central Taiwan.
No full textUnderstanding sedimentation in the Song Hong–Yinggehai Basin, South China Sea
No full textThe Cenozoic Song Hong–Yinggehai Basin in the South China Sea contains a large volume of sediment that has been used in previous studies, together with regional geomorphology, to argue for the existence of a large palaeodrainage system that connected eastern Tibet with the South China Sea. To test this and to understand the significance of sediment volumes deposited in the Song Hong–Yinggehai Basin, this study compared erosion histories of source regions with sediment volumes deposited during the two main stages in basin evolution spanning active rifting and subsidence (30–15.5 Ma) and postrift sedimentation (15.5 Ma to present). The study of basin provenance by detrital zircon U-Pb dating revealed Hainan was an important and continuous source of sediment, and a bedrock thermochronological study quantified its overall contribution to basin sedimentation. Comparison between the accumulated mass of basin sediment and volumes of eroded bedrock, calculated from apatite thermochronometry across the modern Red River drainage in northern Vietnam as well as Hainan Island, accounted for the bulk of sediment deposited since 30 Ma. Consequently, if an expanded paleodrainage ever existed it must have predated the Oligocene
Experiment on interaction of abutment, steel H-Pile and soil in integral abutment jointless bridges (IAJBs) under Low-cycle Pseudo-static displacement loads
No full textSoil-abutment or soil-pile interactions under cyclic static loads have been widely studied in integral abutment jointless bridges (IAJBs). However, the IAJB has the combinational interaction of soil-abutment and soil-pile, and the soil-abutment-pile interaction is lack of comprehensively study. Therefore, a reciprocating low-cycle pseudo-static test was carried out under an cyclic horizontal displacement load (DL) to gain insight into the mechanical behavior of the soil-abutment-pile system. Test results indicate that the earth pressure of backfill behind abutment has the ratcheting effect, which induced a large earth pressure. The soil-abutment-pile system has a favorable energy dissipation capacity and seismic behavior with relatively large equivalent viscous damping. The accumulative horizontal deformation in pile will be occurred by the effect of abutment and unbalance soil pressure of backfill. The test shows that the maximum horizontal deformation of pile occurs in the pile depth of 1.0b~3.0b of pile body rather than at the pile head due to the accumulative deformation of pile, which is significantly different from those of previous test results of soil-pile interaction. The time-history curve for abutment is relatively symmetrical and its accumulative deformation is small. However, the time-history curve of pile is asymmetrical and its accumulative deformation is dramatically large. The traditional theory of deformation applies only to the calculation of noncumulative deformation of pile, and the influence of accumulative deformation should be considered in practical engineering. A significant difference of inclinations in the positive and negative directions increases when the displacement load is relatively large. The rotation of abutment when bridge expands is larger than that when bridge contracts due to earth pressure of backfill
Buddhism and Tourism at Pu-Tuo-Shan, China
No full textThis thesis is a study of pilgrimage and religious tourism in a Chinese Buddhist context, with a focus on both the host monastic community and visitors. The selected research site is Pu-Tuo-Shan, one of the Four Buddhist Sacred Mountains of China. While the Western literature on pilgrimage and religious tourism in the context of Buddhism in China remains thin and the many studies in Chinese have their research focus primarily on how to make use of religions to develop tourism and stimulate economic growth, this thesis aims to present the perceptions of Buddhist monks and nuns towards receiving visitors and tourism. The perceptions of religious hosts towards tourism development, and how they cope with the subsequent challenges created by tourism in China, are subjects that have not been studied. Additionally the thesis analyses data derived from a survey of 777 visitors to the island; the quantitative analysis sheds light on the profile of visitors. As elsewhere in the world, the religious sites of China attract not only believers, but also leisure and cultural tourists. The popularity of Pu-Tuo as a tourist destination inevitably disturbs the serenity of the monastic life of the approximately thousand monks and nuns who live there in their monasteries and nunneries. The first objective of this research is to generate a typology of visitors, and this was done through a quantitative approach grounded in post-positivism. The visitor survey was used to construct a visitor typology. The second objective of this thesis, to address how Buddhist monks and nuns perceive receiving visitors and tourism, and their ways to manage visitors’ behaviours, is achieved by adopting a qualitative approach grounded in an interpretive-constructivist paradigm. In-depth interviews with 25 monks and nuns were conducted to capture rich contextual data of their understandings. The two objectives of the thesis are related in the sense that the impact of the visitors on the monastic community and how the monks and nuns perceive their presence in Pu-Tuo depend on the visitors’ reasons for their visits, their behaviour and the strength of their belief in Buddhism. The findings provide insight into how the concepts of ‘pilgrimage’ and ‘pilgrim’ are understood from a Buddhist perspective. The attitudes of the Pu-Tuo Buddhist monks and nuns towards receiving visitors and tourism are found to be mostly welcoming and supportive. This contrasts with the literature on sites belonging to religions other than Buddhism which indicates that tourism is perceived by religious hosts as a burden and as a threat to the sanctity of their religious/sacred sites. Yet, there are challenges created by the visitors in Pu-Tuo and these are noted by the monks and nuns. Their ‘Buddhist way’ of undertaking visitor management is found to be different from what is described in the existing literature about non-Buddhist sites. It is suggested that the empathetic nature of Buddhism is at the root of the visitor management strategies adopted at Pu-Tuo. The findings thereby contribute to the existing scholarly knowledge of how Buddhist sites are managed in the Buddhist way
RV-detected planets around M dwarfs: Challenges for core accretion models
No full textPlanet formation is sensitive to the conditions in protoplanetary disks, for
which scaling laws as a function of stellar mass are known. We aim to test
whether the observed population of planets around low-mass stars can be
explained by these trends, or if separate formation channels are needed.
We address this question by confronting a state-of-the-art planet population
synthesis model with a sample of planets around M dwarfs observed by the HARPS
and CARMENES radial velocity (RV) surveys. To account for detection biases, we
performed injection and retrieval experiments on the actual RV data to produce
synthetic observations of planets that we simulated following the core
accretion paradigm.
These simulations robustly yield the previously reported high occurrence of
rocky planets around M dwarfs and generally agree with their planetary mass
function. In contrast, our simulations cannot reproduce a population of giant
planets around stars less massive than 0.5 solar masses. This potentially
indicates an alternative formation channel for giant planets around the least
massive stars that cannot be explained with current core accretion theories. We
further find a stellar mass dependency in the detection rate of short-period
planets. A lack of close-in planets around the earlier-type stars () in our sample remains unexplained by our model and
indicates dissimilar planet migration barriers in disks of different spectral
subtypes.
Both discrepancies can be attributed to gaps in our understanding of planet
migration in nascent M dwarf systems. They underline the different conditions
around young stars of different spectral subtypes, and the importance of taking
these differences into account when studying planet formation.Comment: Accepted for publication in A&A. 19 pages, 9 figure
Modelling of hydrological response to climate change in glacierized Central Asian catchments
No full textThe arid lowlands of Central Asia are highly dependent on the water supplied by the Tien Shan mountains. Snow and ice storage make large contributions to current runoff, particularly in summer. Two runoff models with different temporal resolutions, HBV-ETH and OEZ, were applied in three glaciated catchments of the Tien Shan mountains. Scenario runs were produced for a climate change caused by the doubling of atmospheric CO2 as predicted by the GISS global circulation model and assuming a 50% reduction of glaciation extent, as well as a complete loss of glaciation. Agreement of the results was best for runs based on 50% glaciation loss, where both models predict an increase in spring and summer runoff compared to current levels. Scenarios for complete loss of glaciation predict an increase in spring runoff levels, followed by lower runoff levels for July and August. Model predictions differ concerning the degree of reduction of late summer runoff. These scenarios are sensitive to model simulation of basin precipitation, as well as to reduction of glaciation extent
Novel high performance poly(p-phenylene benzobisimidazole) (PBDI) membranes fabricated by interfacial polymerization for H 2 separation
No full text Membranes with high selectivity and permeance are needed to reduce energy consumption in hydrogen purification and pre-combustion CO 2 capture. Polybenzimidazole (PBI) is one of the leading membrane materials for this separation. In this study, we present superior novel supported PBI (poly(p-phenylene benzobisimidazole), PBDI) membranes prepared by a facile interfacial polymerization (IP) method. The effect of IP reaction duration, operating temperature and pressure on membrane separation performance was systematically investigated. The best performance was achieved for membranes prepared in a 2 h reaction time. The resulting membranes display an ultrahigh mixed-gas H 2 /CO 2 selectivity of 23 at 423 K together with an excellent H 2 permeance of 241 GPU, surpassing the membrane performance of conventional polymers (the 2008 Robeson upper bound). These separation results, together with the facile manufacture, pressure resistance, long-term thermostability (>200 h) and economic analysis, recommend the PBDI membranes for industrial use in H 2 purification and pre-combustion CO 2 capture. Besides, PBDI membranes possess high selectivities towards H 2 /N 2 (up to 60) and H 2 /CH 4 (up to 48) mixtures, indicating their potential applications in ammonia synthesis and syngas production. Accepted Author ManuscriptChemE/Catalysis EngineeringOLD ChemE/Organic Materials and InterfacesRST/Storage of Electrochemical Energ
Meso-Cenozoic growth of the eastern Qilian Shan, northeastern Tibetan Plateau margin: Insight from borehole apatite fission-track thermochronology in the Xiji Basin
No full textThe surface uplift of the Tibetan Plateau (TP) is among the most important geological events in Earth's history, but the growth of the eastern TP margin that yielded the thickened crust and abrupt topography remains controversial. In this paper, six sample apatite fission-track (AFT) analyses of three boreholes in the Xiji Basin are applied to constrain the Mesozoic-Cenozoic uplift and exhumation history of the eastern Qilian Shan, northeastern TP. Most of the AFT ages range from 134 +/- 8 Ma to 117 +/- 6 Ma, except for the shallowest sample, with a younger age of 65.9 +/- 3.2 Ma. Thermal history modeling indicates that the eastern Qilian Shan experienced a three-phase differential cooling history: (1) widespread rapid cooling during the Middle Jurassic-Early Cretaceous (ca. 174-120 Ma, Stage 1), (2) regional cooling during the Late Cretaceous-Paleocene (ca. 80-60 Ma, Stage 2) and (3) widespread cooling during the Eocene-early Miocene (ca. 40-20 Ma, Stage 3). We conclude that the Middle Jurassic-Early Cretaceous was the main stage of the growth and thickening of the northeastern TP, which was related to the upper-crustal horizontal shortening of the eastern Qilian Shan. Thermal history modeling of the youngest sample and seismic profile analysis imply significant reactivation of the Liupanshan fault zone during ca. 80-60 Ma. This locally intense uplift and deformation on the eastern margin of the Qilian Shan during the Late Cretaceous was likely induced by the closure of the Neo-Tethys and the continued shortening of the Lhasa-Qiangtang block. Late Eocene-Early Miocene (ca. 40-20 Ma) cooling of the eastern margin of the Qilian Shan records the coeval crustal extension and exhumation of the northeastern margin of the TP as the far-field effect of subduction of the western Pacific plate. Our AFT data detect no intense late Cenozoic reactivation information for the Xiji region, which indicates that the ca. 15-7 Ma rapid uplift triggered by fault reactivation was only located in the Haiyuan-Liupanshan fault zone, along the eastern margin of the Qilian Shan, northeastern TP. This multi-phase exhumation history is not beneficial for regional hydrocarbon exploration
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