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        A high-resolution timescale for the Miocene Shanwang diatomaceous shale lagerstätte (China): development of Wavelet Scale Series Analysis for cyclostratigraphy

        Jifeng Yu,Xinlong Pang,Wenzhao Fu,Jason Hilton,Mingmei Liang,Zongkai Jiang,Xiuli Zhao,Wenyan Qiao,Suo Shi,Diandong Zhang,Huitao Cao,Haibo Jia,Yadong Wang,Xiaoke Hu,Rui Zhang 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.5

        The Miocene aged Shanwang Formation from the Shanwang National Geopark in China represents a succession of lacustrine diatomaceous shales containing an abundant and diverse biota with lagerstätte fossilization of soft tissues. To date, the Shanwang Formation has not been investigated for cyclostratigraphy nor has it been dated with high precision methods. Now we use thorium data as a paleoenvironmental and paleoclimatic proxy to conduct a detailed cyclostratigraphic analysis. A new and simple cyclostratigraphic method, Wavelet Scale Series Analysis (WSSA) is developed to recognize Milankovitch cycles. A total of three short eccentricity and fifteen precession cycles are identified; obliquity cycles are not apparent. In the sedimentary succession, the corresponding precession and short eccentricity cycles are 1.17 m and 4.98 m thick respectively, with this verified by Correlation Coefficient (COCO) analysis and Multitaper-Method (MTM) spectral analysis. We estimate the studied interval was deposited over a duration of 0.3 Myr with a depositional rate of c. 5.7 cm/kyr. Paleomagnetic and radio isotope dating data shows that the diatomaceous shale was deposited during Chron C5En, which places it at approximately 18.5 Ma during the Burdigalian stage of the Early Miocene, rather than in the Middle Miocene as previously thought. The Shanwang lagerstätte biota therefore predates the Middle Miocene Climate Optimum (MMCO) and did not form within it. The geological time scale with a high resolution of 20 kyr was set accordingly.

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        HDRE: Coverage Hole Detection with Residual Energy in Wireless Sensor Networks

        Yun-zhou Zhang,Xiaohua Zhang,Wenyan Fu,Zeyu Wang,Honglei Liu 한국통신학회 2014 Journal of communications and networks Vol.16 No.5

        Coverage completeness is an important indicator forquality of service in wireless sensor networks (WSN). Due to limitedenergy and diverse working conditions, the sensor nodes havedifferent lifetimes which often cause network holes. Most of the existingmethods expose large limitation and one-sidedness becausethey generally consider only one aspect, either coverage rate or energyissue. This paper presents a novel method for coverage holedetection with residual energy in randomly deployed wireless sensornetworks. By calculating the life expectancy of working nodesthrough residual energy, we make a trade-off between network repaircost and energy waste. The working nodes with short lifetimeare screened out according to a proper ratio. After that, the locationsof coverage holes can be determined by calculating the jointcoverage probability and the evaluation criteria. Simulation resultshows that compared to those traditional algorithms without considerationof energy problem, our method can effectively maintainthe coverage quality of repairedWSN while enhancing the life spanof WSN at the same time.

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        The electrocatalysis of Mn-Co3O4/CeO2@C particles with different Ce content modified Ti/PbO2 anode and its application for copper electrodeposition

        Yin Zihang,He Ruibo,Nie Fei,Wei Zhen,Jia Bo,Feng Qing,Fu Xiaolong,Zhang Wenyan 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12

        The oxygen evolution kinetics of industrial copper electrodeposition is slow, resulting in low electrocatalytic activity and high energy consumption. In this work, a quaternary composite of carbon coated active particles containing Mn, Co and Ce were prepared (Mn-Co3O4/CeO2@C), and Ti/Sb-SnO2/PbO2 electrode doped with these active particles was prepared by co-electrodeposition. The microstructure and chemical composition of the electrode was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD). Linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and Tafel polarization curve (Tafel) were used to study the electrochemical properties of anode materials. The results showed that the doping of Mn-Co3O4/CeO2@C active particles promoted the crystal transition of PbO2, decreased the average grain size, and the doping of Ce increases the average valence state of Co. The modified titanium electrode showed excellent catalytic activity of the oxygen evolution reaction (OER) characteristics. The overpotential of the doped Ti/Sb-SnO2/PbO2 anode was only 453 mV when the current density was 20 mA cm−2 in 0.5 M H2SO4 solution, which is 508 mV lower than that of the undoped Ti/Sb-SnO2/PbO2 anode. In simulated copper electro-deposition experiments, the cell voltage was reduced by about 400 mV, compared to the undoped Ti/Sb-SnO2/PbO2 electrode.

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