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Methane seepages in the northern South China Sea: evidence from in situ measurements

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Journal of Oceanology and Limnology 2018年第5期36卷 1556-1561页

作者： QIU Zhongyan HAN Xiqiu WANG Yejian Key Laboratory of Submarine Geosciences Second Institute of OceanographyState Oceanic AdministrationHangzhou 310012 China

Continental margins in world oceans contain large amounts of marine gas hydrates. Changes in the temperature and pressure of sediment may destabilize the methane hydrate, leading to its release and seepage into the sea. This process would increase the dissolved methane in the ambient seawater. In this study, a methane sensor was used to detect methane anomalies in the water column in southwestern Dongsha and Shenhu, northern slope of the South China Sea. Methane plumes were detected at stations SCS001 and T001 in the southwestern Dongsha area, and station SCS002 in the Shenhu area, respectively. The maximum methane concentrations were 8.8 nmol/L in southwestern Dongsha and 10.1 nmol/L in Shenhu, which are about 4–5 times higher than the background methane concentration. This indicates that there are active methane seepages present in both the southwestern Dongsha and Shenhu areas, which are likely related to a methane hydrate reservoir beneath the seafloor. A methane sensor with a low detection limit is a practical instrument with which to detect methane plumes in oceanic environments and to monitor methane leakage from the seafloor.

关键词： northern slope of the South China Sea methane leakage in situ measurement methane sensor

Vibrations induced by tunnel boring machine in urban areas: in situ measurements and methodology of analysis

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第1期15卷 130-145页

作者： Antoine Rallu Nicolas Berthoz Simon Charlemagne Denis Branque University of Lyon ENTPELTDS-UMR CNRS 5513CeLyAVaulx-en-VelinFrance French Centre for Tunnel Studies(CETU) BronFrance

Excavation with tunnel boring machine(TBM)can generate vibrations,causing damages to neighbouring buildings and disturbing the residents or the *** problem is particularly challenging in urban areas,where TBMs are increasingly large in diameter and shallow in *** response to this problem,four experimental campaigns were carried out in different geotechnical contexts in *** vibration measurements were acquired on the surface and inside the *** measurements are also complemented by few data in the *** original methodology of signal processing is pro-posed to characterize the amplitude of the particle velocities,as well as the frequency content of the signals to highlight the most energetic *** levels of vibrations are also compared with the thresholds existing in various European regulations concerning the impact on neighbouring structures and the disturbance to local residents.

关键词： Ground-borne vibrations Tunnel boring machine(TBM) in situ measurement Dynamic characterization Vibration levels Site spectrum

Optimizing the design of in situ sediment oxygen demand measurement chambers

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International Journal of Sediment Research 2011年第2期26卷 222-229页

作者： HE Yun and LIU Cheng 1 Senior Engineer,Dr.,China Institute of Water Resources and Hydropower Research,Beijing 100038,China, 2 Prof.,Dr.,International Research and Training Center on Erosion and Sedimentation,Beijing 100048,China [a]Senior Engineer Dr. China Institute of Water Resources and Hydropower Research Beijing 100038 China [b]Prof. Dr. International Research and Training Center on Erosion and Sedimentation Beijing 100048 China

Sediment Oxygen Demand(SOD) is a key parameter for water quality analysis and for water quality modeling in rivers,lakes,estuaries and *** SOD can be measured both in the laboratory and in ***,the in situ technique appears to be the better approach for measuring SOD,as it likely to provide more representative and accurate *** order to optimize the design of in situ SOD measurement chambers,the three-dimensional flow fields in cylindrical SOD measurement chambers, commonly used for in situ measurements,have been numerically simulated by using the RNG-based k-s double equation turbulence *** chambers with three different inflow pipe configurations were *** results show that chamberⅢpresents distinct advantages over the other designs for in situ SOD measurement,because good flow mixing can be achieved and bottom sediment suspension can be avoided in the *** numerical simulation results were validated by comparison with existing results derived from laboratory *** SOD measurement chamber designed to reflect the results of the numerical simulations was successfully tested for in situ SOD measurements in both fresh and saline waters.

关键词： Sediment Oxygen Demand(SOD) Renormalization group(RNG) Velocity field in situ measurement Field tests

in situ measurements of benthic oxygen fluxes in Hui-quan Bay of Qingdao by eddy correlation techniques:short term pattern variations in gravel beach

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Marine Science Bulletin 2020年第2期22卷 36-52页

作者： CUI Shanggong YU Xinsheng ZHAO Guangtao National Marine Data and Information Service Tianjin 300171China Key Lab.of Submarine Geosciences and Prospecting Techniques MOECollege of Marine GeosciencesOcean University of ChinaQingdao266100Shandong provinceChina

The oxygen fluxe across the sediment-water interface(SWI)in coastal region is a key measure to fully understand the regulation of biogeochemical cycles in an aquatic ***,studies on fluxes of dissolved oxygen in gravel beach are limited,because of the difficulty in sample collection and instrumentations *** this study,benthic oxygen fluxes across rocky substratum in an intertidal zone of Huiquan Bay was estimated by using noninvasive eddy correlation techniques.A total of 10 burst measurements were *** oxygen flux fluctuated from-5.7888±2.6 to+49.3344±2.6 mmol O2 m-2/d were *** cospectra analysis showed that the oxygen flux at the frequency band between 0.093 and 0.279 Hz(at a period from 3.58 to 10.75 s)contributed 50.19%to the total spectrum on *** results showed that the major contribution band moved to the high frequency region gradually and reached a steady state with increasing tidal *** is demonstrated that wave movement and wave breaking interaction resulted in the change of oxygen flux between gravel beach and shallow waters at the start and the end of a rising tide period,*** eddy correlation techniques offer an efficient means for flux measurement over a gravel or mixed sand and gravel beaches.

关键词： sediment-water interface(SWI) oxygen fluxes eddy correlation gravel beaches in situ measurement

A Universal Blown Film Apparatus for in situ X-ray measurements

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Chinese Journal of Polymer Science 2017年第12期35卷 1508-1516页

作者： Rui Zhang 纪又新 Qian-lei Zhang Jian-zhu Ju Ali Sarmad Li-fu Li Hao-yuan Zhao 李良彬 National Synchrotron Radiation Lab and College of Nuclear Science and Technology Chinese Academy of Sciences Key Laboratory of Soft Matter Chemistry University of Science and Technology of China

A setup of blown film machine combined with in situ synchrotron radiation X-ray diffraction measurements and infrared temperature testing is reported to study the structure evolution of polymers during film blowing. Two homemade auto-lifters are constructed and placed under the blown machine at each end of the beamline platform which move up and down with a speed of 0.05 mm/s bearing the 200 kg weight machine. Therefore, structure development and temperature changes as a function of position on the film bubble can be obtained. The blown film machine is customized to be conveniently installed with precise servo motors and can adjust the processing parameters in a wide range. Meanwhile, the air ring has been redesigned in order to track the structure information of the film bubble immediately after the melt being extruded out from the die exit. Polyethylene（PE） is selected as a model system to verify the feasibility of the apparatus and the in situ experimental techniques. Combining structure information provided by the WAXD and SAXS and the actual temperature obtained from the infrared probe, a full roadmap of structure development during film blowing is constructed and it is helpful to explore the molecular mechanism of structure evolution behind the film blowing processing, which is expected to lead to a better understanding of the physics in polymer processing.

关键词： Blown film machine Synchrotron radiation X-ray diffraction in situ measurement Structure evolution

In situ method for stress measurements in film-substrate electrodes during electrochemical processes:key role of softening and stiffening

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Acta Mechanica Sinica 2020年第6期36卷 1319-1335,I0004页

作者： Haimei Xie Yilan Kang Haibin Song Jiangang Guo Qian Zhang Tianjin Key Laboratory of Modern Engineering Mechanics School of Mechanical EngineeringTianjin UniversityTianjin300350China

Electrode stress is one of the main driving forces of electrochemical degradation,which is directly related to battery cycle life,thus attracting great ***,we propose an in situ method to measure bilayer stresses in film-substrate electrodes during electrochemical *** method consists of two parts:stress models featuring Li-dependent material modulus and in situ deformation measurements,through which electrode bilayer stresses evolution accompanied by Li-dependent material modulus can be quantitatively *** application of the method,typical silicon-composite and carbon-composite film-substrate electrodes are selected for in situ mechanical measurements and experimental analysis is *** show that silicon material and carbon material exhibit significant,continuous softening and stiffening,*** two film-substrate electrodes,electrode material films experience compressive stress and current collector substrates undergo a tensile-to-compressive conversion across the ***,moduli and stresses in both electrodes vary nonlinearly with capacity,presenting non-overlapping paths between lithiation and *** on experimental data,we further demonstrate the key role of Li-dependent modulus on electrode stresses,finding that silicon material softening decreases and carbon material stiffening increases electrode *** deficiencies of current stress measurement method based on Stoney equation and the applicability of our method are discussed.

关键词： in situ measurement Stress model-Bilayer film-substrate electrodes Silicon softening Carbon stiffening Lithiation-delithiation non-overlapping

In situ observation of atomic movement in a ferroelectric film under an external electric field and stress

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Nano Research 2018年第7期11卷 3824-3832页

作者： Hyeon Jun Lee Er-Jia Guo Taewon Min Seung Hyun Hwang Su Yong Lee Kathrin Dorr Jaekwang Lee Ji Young Jo School of Materials Science and Engineering Gwangju Institute of Science and Technology Gwangju 61005 Republic of Korea Quantum Condensed Matter Division Oak Ridge National Laboratory Oak Ridge TN 37830 USA Institute for Physics Martin-Luther-University Halle-Wittenberg Halle 06099 Germany Department of Physics Pusan National University Busan 46241 Republic of Korea Pohang AccelerotorLaboratory Pohang 37673 Republic of Korea

Atomic movement under application of external stimuli （i.e., electric field or mechanical stress） in oxide materials has not been observed due to a lack of experimental methods but has been well known to determine the electric polarization. Here, we investigated atomic movement arising from the ferroelectric response of BiFeO3 thin films under the effect of an electric field and stress in real time using a combination of switching spectroscop）6 time-resolved X-ray microdiffraction, and in situ stress engineering. Under an electric field applied to a BiFeO3 film, the hysteresis loop of the reflected X-ray intensity was found to result from the opposing directions of displaced atoms between the up and down polarization states. An additional shift of atoms arising from the linearly increased dielectric component of the polarization in BiFeO3 was confirmed through gradual reduction of the diffracted X-ray intensity. The electric-field- induced displacement of oxygen atoms was found to be larger than that of Fe atom for both ferroelectric switching and increase of the polarization. The effect of external stress on the BiFeO3 thin film, which was controlled by applying an electric field to the highly piezoelectric substrate, showed smaller atomic shifts than for the case of applying an electric field to the film, despite the similar tetragonality.

关键词： in situ measurement atomic displacementunder electric field time-resolved X-ray microdiffraction ferroelectrics in situ strain engineering

Tensile-WAXD Apparatus:An Improved and Accurate System for the In situ Study of Extension-induced Segmental Orientation in Highly Stretched Elastomer

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Chinese Journal of Polymer Science 2024年第12期42卷 2002-2010,I0011页

作者： Xiang Shi Center for Advanced Material Diagnostic Technology Shenzhen Technology UniversityShenzhen518118China Laboratoire de Physique des Solides CNRSUniversitéParis-SudUniversitéParis-SaclayOrsay91400France

An improved X-ray apparatus that combines tensile testing and X-ray diffraction has been designed and constructed to conduct timeresolved experiments during uniaxial *** utilizing mortise-like clamping jaws and dogbone-shaped specimens,this setup allows for the simultaneous recording of high-quality mechanical responses and 2D diffraction patterns due to the minimization of experimental errors from sample slippage or premature ***,the local extension ratio can be accurately determined based on thickness variation,and the Hermans'orientation function was demonstrated to be a reliable method with high accuracy to calculate the segmental orientation parameter〈P_(2)〉in elastomeric samples under high degree of *** summary,this innovative tensile-WAXD instrument has proven to be a promising and powerful technique for investigating the“stress-deformation-segmental orientation”relationship in elastomers with high extensibilities.

关键词： X-ray apparatus Elongation calculation Segmental orientation in situ measurement

Measured dynamic load distribution within the in situ axlebox bearing of high-speed trains under polygonal wheel–rail excitation

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Railway Engineering Science 2024年第4期32卷 444-460页

作者： Yu Hou Xi Wang Jiaqi Wei Menghua Zhao Wei Zhao Huailong Shi Chengyu Sha Frontiers Science Center for Smart High-Speed Railway System Beijing Jiaotong UniversityBeijing 100044China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China CRRC Qingdao Sifang Co. Ltd.Qingdao 266111China State Key Laboratory of Rail Tranist Vehicle System Southwest Jiaotong UniversityChengdu 610031China

The dynamic load distribution within in-service axlebox bearings of high-speed trains is crucial for the fatigue reliability assessment and forward design of axlebox bearings. This paper presents an in situ measurement of the dynamic load distribution in the four rows of two axlebox bearings on a bogie wheelset of a high-speed train under polygonal wheel–rail excitation. The measurement employed an improved strain-based method to measure the dynamic radial load distribution of roller bearings. The four rows of two axlebox bearings on a wheelset exhibited different ranges of loaded zones and different means of distributed loads. Besides, the mean value and standard deviation of measured roller–raceway contact loads showed non-monotonic variations with the frequency of wheel–rail excitation. The fatigue life of the four bearing rows under polygonal wheel–rail excitation was quantitatively predicted by compiling the measured roller–raceway contact load spectra of the most loaded position and considering the load spectra as input.

关键词： High-speed train Axlebox bearing Dynamic load distribution in situ measurement Polygonal wheel–rail excitation