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  • 1
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    Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349 (2015)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 15 (2014): 4958–4983, doi:10.1002/2014GC005567.
    Description: Combined analyses of deep tow magnetic anomalies and International Ocean Discovery Program Expedition 349 cores show that initial seafloor spreading started around 33 Ma in the northeastern South China Sea (SCS), but varied slightly by 1–2 Myr along the northern continent-ocean boundary (COB). A southward ridge jump of ∼20 km occurred around 23.6 Ma in the East Subbasin; this timing also slightly varied along the ridge and was coeval to the onset of seafloor spreading in the Southwest Subbasin, which propagated for about 400 km southwestward from ∼23.6 to ∼21.5 Ma. The terminal age of seafloor spreading is ∼15 Ma in the East Subbasin and ∼16 Ma in the Southwest Subbasin. The full spreading rate in the East Subbasin varied largely from ∼20 to ∼80 km/Myr, but mostly decreased with time except for the period between ∼26.0 Ma and the ridge jump (∼23.6 Ma), within which the rate was the fastest at ∼70 km/Myr on average. The spreading rates are not correlated, in most cases, to magnetic anomaly amplitudes that reflect basement magnetization contrasts. Shipboard magnetic measurements reveal at least one magnetic reversal in the top 100 m of basaltic layers, in addition to large vertical intensity variations. These complexities are caused by late-stage lava flows that are magnetized in a different polarity from the primary basaltic layer emplaced during the main phase of crustal accretion. Deep tow magnetic modeling also reveals this smearing in basement magnetizations by incorporating a contamination coefficient of 0.5, which partly alleviates the problem of assuming a magnetic blocking model of constant thickness and uniform magnetization. The primary contribution to magnetic anomalies of the SCS is not in the top 100 m of the igneous basement.
    Description: This research is funded by National Science Foundation of China (grant 91028007, grant 91428309), Program for New Century Excellent Talents in University, and Research Fund for the Doctoral Program of Higher Education of China (grant 20100072110036).
    Description: 2015-06-27
    Keywords: Deep tow magnetic survey ; Magnetic anomaly ; Crustal evolution ; Modeling ; International Ocean Discovery Program Expedition 349 ; South China Sea tectonics
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    Seismic stratigraphy of the central South China Sea basin and implications for neotectonics (2015)
    John Wiley & Sons
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 120 (2015): 1377–1399, doi:10.1002/2014JB011686.
    Description: Coring/logging data and physical property measurements from International Ocean Discovery Program Expedition 349 are integrated with, and correlated to, reflection seismic data to map seismic sequence boundaries and facies of the central basin and neighboring regions of the South China Sea. First-order sequence boundaries are interpreted, which are Oligocene/Miocene, middle Miocene/late Miocene, Miocene/Pliocene, and Pliocene/Pleistocene boundaries. A characteristic early Pleistocene strong reflector is also identified, which marks the top of extensive carbonate-rich deposition in the southern East and Southwest Subbasins. The fossil spreading ridge and the boundary between the East and Southwest Subbasins acted as major sedimentary barriers, across which seismic facies changes sharply and cannot be easily correlated. The sharp seismic facies change along the Miocene-Pliocene boundary indicates that a dramatic regional tectonostratigraphic event occurred at about 5 Ma, coeval with the onsets of uplift of Taiwan and accelerated subsidence and transgression in the northern margin. The depocenter or the area of the highest sedimentation rate switched from the northern East Subbasin during the Miocene to the Southwest Subbasin and the area close to the fossil ridge in the southern East Subbasin in the Pleistocene. The most active faulting and vertical uplifting now occur in the southern East Subbasin, caused most likely by the active and fastest subduction/obduction in the southern segment of the Manila Trench and the collision between the northeast Palawan and the Luzon arc. Timing of magmatic intrusions and seamounts constrained by seismic stratigraphy in the central basin varies and does not show temporal pulsing in their activities.
    Description: This research is funded by National Science Foundation of China (grants 91428309 and 91028007), Program for New Century Excellent Talents in University, and Research Fund for the Doctoral Program of Higher Education of China (grant 20100072110036).
    Description: 2015-09-16
    Keywords: South China Sea ; Seismic stratigraphy ; Seismic facies ; Neotectonism ; IODP Expedition 349 ; Core-well-seismic integration
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
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    Methane-derived authigenic carbonates from the northern Gulf of Mexico — MD02 Cruise (2008)
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © The Author(s), 2007. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Geochemical Exploration 95 (2007): 1-15, doi:10.1016/j.gexplo.2007.05.011.
    Description: Authigenic carbonates were sampled in piston cores collected from both the Tunica Mound and the Mississippi Canyon area on the continental slope of the northern Gulf of Mexico during a Marion Dufresne cruise in July 2002. The carbonates are present as hardgrounds, porous crusts, concretions or nodules and shell fragments with or without carbonate cements. Carbonates occurred at gas venting sites which are likely to overlie gas hydrates bearing sediments. Electron microprobe, X-ray diffraction (XRD) and thinsection investigations show that these carbonates are high-Mg calcite (6 - 21 mol % MgCO3), with significant presence of framboidal pyrite. All carbonates are depleted in 13C (δ13C = -61.9 to -31.5 ‰ PDB) indicating that the carbon is derived mainly from anaerobic methane oxidation (AMO). Age estimates based on 14C dating of shell fragments and on regional sedimentation rates indicate that these authigenic carbonates formed within the last 1,000 yr in the Mississippi Canyon and within 5,500 yr at the Tunica Mound. The oxygen isotopic composition of carbonates ranges from +3.4 to +5.9 ‰ PDB. Oxygen isotopic compositions and Mg2+ contents of carbonates, and present in-situ temperatures of bottom seawater/sediments, show that some of these carbonates, especially from a core associated with underlying massive gas hydrates precipitated in or near equilibrium with bottom-water. On the other hand, those carbonates more enriched in 18O are interpreted to have precipitated from 18O-rich fluids which are thought to have been derived from the dissociation of gas hydrates. The dissociation of gas hydrates in the northern Gulf of Mexico within the last 5,500 yr may be caused by nearby salt movement and related brines.
    Description: Financial support for this work was provided by the Grant-in-Aid from the Ministry of Education and Science and the Research Grant from JAPEX.
    Keywords: Methane-derived authigenic carbonates ; Gulf of Mexico ; High Mg-calcite ; Carbon and oxygen isotope ; Age of authigenic carbonates ; Dissociation of gas hydrates
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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    Format: application/vnd.ms-excel
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  • 4
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    Petroleum-related hydrocarbons in deep and subsurface sediments from South-Western Barents Sea (2011)
    Elsevier
    In:  Marine Environmental Research, 71 (5). pp. 357-368.
    Details
    Publication Date: 2015-05-27
    Description: Subsurface sediments from a pockmark area in South-Western Barents Sea have been earlier found to contain elevated levels of petroleum-related polycyclic aromatic hydrocarbons. This work describes a comprehensive analysis of various biomarkers, including the highly source-specific hopanes, in a 4.5 m long gravity core from the same area, together with subsurface sediment samples from other areas in the region without pockmarks present (“background samples”). A clear difference between the pockmark gravity core and the background sediment cores was found, both with regard to genesis and the level of transformation of organic matter. A number of indicator parameters, such as methylphenanthrene index (MPI-1), point towards a significantly higher maturity of hydrocarbons in the pockmark core throughout its length as compared to the other sampled locations. Higher contents of microbial hopanoids (hopenes) may indicate the former presence of petroleum. These findings confirm the hypothesis of a natural hydrocarbon source in the deeper strata present in the studied location with pockmarks.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.marenvres.2011.04.003
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Economic costs of biological invasions in Asia (2021)
    Pensoft
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    Publication Date: 2024-02-07
    Description: Invasive species have caused severe impacts on biodiversity and human society. Although the estimation of environmental impacts caused by invasive species has increased in recent years, economic losses associated with biological invasions are only sporadically estimated in space and time. In this study, we synthesized the losses incurred by invasions in Asia, based on the most comprehensive database of economic costs of invasive species worldwide, including 560 cost records for 88 invasive species in 22 countries. We also assessed the differences in economic costs across taxonomic groups, geographical regions and impacted sectors, and further identified the major gaps of current knowledge in Asia. Reported economic costs of biological invasions were estimated between 1965 and 2017, and reached a total of US$ 432.6 billion (2017 value), with dramatic increases in 2000–2002 and in 2004. The highest costs were recorded for terrestrial ectotherms, for species estimated in South Asia, and for species estimated at the country level, and were related to more than one impacted sector. Two taxonomic groups with the highest reported costs were insects and mammals, and two countries with the highest costs were India and China. Non-English data covered all of 12 taxonomic groups, whereas English data only covered six groups, highlighting the importance of considering data from non-English sources to have a more comprehensive estimation of economic costs associated with biological invasions. However, we found that the estimation of economic costs was lacking for most Asian countries and for more than 96% of introduced species in Asia. Further, the estimation is heavily biased towards insects and mammals and is very limited concerning expenditures on invasion management. To optimize the allocation of limited resources, there is an important need to better and more widely study the economic costs of invasive alien species. In this way, improved cost reporting and more collaborations between scientists and stakeholders are needed across Asia.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Potassium-activated wire mesh: A stable monolithic catalyst for diesel soot combustion (2016)
    Wiley-Blackwell
    Details
    Publication Date: 2016-08-26
    Description: Potassium-modified FeCrAl alloy wire mesh was developed as a catalytic diesel particulate filter (CDPF) to suppress the emission of soot from diesel engine. K species were deposited on wire mesh via a chemical vapor deposition method, in which a model soot was used to convert KOH into metallic K at high temperatures (≥ 800 °C) to subsequently activate the wire mesh. The XRF and SEM tests showed that the metallic K reacted with the enriched Al 2 O 3 component on the surface that was derived from the segregation and successive oxidation during the pre-calcination at 950 °C. The resulted layer of K-O-Al species was proved to offer a remarkable activity and stability for catalytic oxidation of diesel soot. The cyclic activity evaluation demonstrated that the K-activated wire mesh can lower the initial temperature of soot combustion to ca. 350 °C and keep the activity for five cycles. The adverse impact of water on the activities suggests that the anti-poising ability of the monolithic catalyst against water needs to be improved for the application in practice.
    Print ISSN: 0930-7516
    Electronic ISSN: 1521-4125
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Published by Wiley-Blackwell
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  • 7
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    Remote Sensing, Vol. 10, Pages 1078: Airborne LiDAR Remote Sensing for Individual Tree Forest Inventory Using Trunk Detection-Aided Mean Shift Clustering Techniques (2018)
    MDPI Publishing
    Details
    Publication Date: 2018-07-07
    Description: Remote Sensing, Vol. 10, Pages 1078: Airborne LiDAR Remote Sensing for Individual Tree Forest Inventory Using Trunk Detection-Aided Mean Shift Clustering Techniques Remote Sensing doi: 10.3390/rs10071078 Authors: Wei Chen Xingbo Hu Wen Chen Yifeng Hong Minhua Yang Airborne LiDAR (Light Detection And Ranging) remote sensing for individual tree-level forest inventory necessitates proper extraction of individual trees and accurate measurement of tree structural parameters. Due to the inadequate tree finding capability offered by LiDAR technology and the complex patterns of forest canopies, significant omission and commission errors occur frequently in the segmentation results. Aimed at error reduction and accuracy refinement, this paper presents a novel adaptive mean shift-based clustering scheme aided by a tree trunk detection technique to segment individual trees and estimate tree structural parameters based solely on the airborne LiDAR data. Tree trunks are detected by analyzing points’ vertical histogram to detach all potential crown points and then clustering the separated trunk points according to their horizontal mutual distances. The detected trunk information is used to adaptively calibrate the kernel bandwidth of the mean shift procedure in the fine segmentation stage by applying an original 2D (two-dimensional) estimation of individual crown diameters. Trunk detection results and LiDAR point clusters generated by the adaptive mean shift procedures serve as mutual references for final detection of individual trees. Experimental results show that a combination of adaptive mean shift clustering and detected tree trunk can provide a significant performance improvement in individual tree-level forest measurement. Compared with conventional clustering techniques, the trunk detection-aided mean shift clustering approach can detect 91.1% of the trees (“recall”) with a higher tree positioning accuracy (the mean positioning error is reduced by 33%) in a multi-layered coniferous and broad-leaved mixed forest in South China, and 93.5% of the identified trees are correct (“precision”). The tree detection brings the estimation of structural parameters for individual trees up to an accuracy level: −2.2% mean relative error and 5.8% relative RMSE (Root Mean Square Error) for tree height and 0.6% mean relative error and 21.9% relative RMSE for crown diameter, respectively.
    Electronic ISSN: 2072-4292
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by MDPI Publishing
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  • 8
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    Energies, Vol. 11, Pages 2240: A Variable-Structure Multi-Resonant DC–DC Converter with Smooth Switching (2018)
    MDPI Publishing
    In: Energies
    Details
    Publication Date: 2018-08-28
    Description: Energies, Vol. 11, Pages 2240: A Variable-Structure Multi-Resonant DC–DC Converter with Smooth Switching Energies doi: 10.3390/en11092240 Authors: Mengying Chen Yifeng Wang Liang Yang Fuqiang Han Yuqi Hou Haiyun Yan In this paper, a variable-structure multi-resonant soft-switching DC–DC converter and its transient smooth control method are proposed. Through the introduction of auxiliary switches, the converter can flexibly adjust its structure among three operating modes. Two switching processes can be obtained. Thus, a wide voltage gain range is achieved within a narrow frequency range. Moreover, to eliminate the large voltage fluctuation during modes switching, a drive signal gradual adjustment control method is proposed. Consequently, smooth switching between different modes can be realized and the voltage fluctuation is suppressed effectively. Finally, a 200 W experimental prototype is established to verify the theoretical analyses. Soft-switching performances for power switches and diodes are both guaranteed. The highest efficiency is 98.2%. With the proposed transient control method, a basically constant 400 V output voltage is ensured within a wide input voltage range (80 V–600 V). In particular, the transient voltage fluctuations during two switching processes decrease from 38.4 V to 10.8 V and from 37.2 V to 8.4 V, respectively.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI Publishing
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  • 9
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    Reductions in Emissions of Carbonaceous Particulate Matter and Polycyclic Aromatic Hydrocarbons from Combustion of Biomass Pellets in Comparison with Raw Fuel Burning (2012)
    American Chemical Society (ACS)
    Details
    Publication Date: 2012-05-18
    Description: Environmental Science & Technology DOI: 10.1021/es300369d
    Print ISSN: 0013-936X
    Electronic ISSN: 1520-5851
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering
    Published by American Chemical Society (ACS)
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