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Prediction of constrained modulus for granular soil using 3D discrete element method and convolutional neural networks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第11期16卷 4769-4781页

作者： tongwei zhang Shuang Li Huanzhi Yang Fanyu zhang Key Laboratory of Mechanics on Disaster and Environment in Western China MOECollege of Civil Engineering and MechanicsLanzhou UniversityLanzhou730000China

To efficiently predict the mechanical parameters of granular soil based on its random micro-structure,this study proposed a novel approach combining numerical simulation and machine learning ***,3500 simulations of one-dimensional compression tests on coarse-grained sand using the three-dimensional(3D)discrete element method(DEM)were conducted to construct a *** this process,the positions of the particles were randomly altered,and the particle assemblages ***,besides confirming the influence of particle size distribution parameters,the stress-strain curves differed despite an identical gradation size statistic when the particle position ***,the obtained data were partitioned into training,validation,and testing datasets at a 7:2:1 *** convert the DEM model into a multi-dimensional matrix that computers can recognize,the 3D DEM models were first sliced to extract multi-layer two-dimensional(2D)cross-sectional *** information was then eliminated via gray processing,and the data were stacked to form a new 3D matrix representing the granular soil’s ***,utilizing the Python language and Pytorch framework,a 3D convolutional neural networks(CNNs)model was developed to establish the relationship between the constrained modulus obtained from DEM simulations and the soil’s *** mean squared error(MSE)function was utilized to assess the loss value during the training *** the learning rate(LR)fell within the range of 10-5e10-1,and the batch sizes(BSs)were 4,8,16,32,and 64,the loss value stabilized after 100 training epochs in the training and validation *** BS?32 and LR?10-3,the loss reached a *** the testing set,a comparative evaluation of the predicted constrained modulus from the 3D CNNs versus the simulated modulus obtained via DEM reveals a minimum mean absolute percentage error(MAPE)of 4.43%under the optimized condition,demonstrating the accuracy of thi

关键词： Soil structure Constrained modulus Discrete element model(DEM) Convolutional neural networks(CNNs) Evaluation of error

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Matched-field localization using a virtual time-reversal processing method in shallow water

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Chinese Science Bulletin 2011年第8期56卷 743-748页

作者： zhang tongwei YANG KunDe MA YuanLiang College of Marine Northwestern Polytechnical University Xi'an 710072 China

Time-reversal processing(TRP) is an implementation of matched-field processing(MFP) where the ocean itself is used to construct the replica *** paper introduces virtual time-reversal processing(VTRP) that is implemented electronically at a receiver array and simulates the kind of processing that would be done by an actual TRP during the reciprocal propagation *** is a forward propagation process,while VTRP is a back-propagation process,which exploits the properties of reciprocity and superposition and is realized by weighting the replica surface with the complex conjugate of the data received on the corresponding element,followed by summation of the processed received *** number of parabolic equation computational grids of VTRP is much smaller than that of MFP in a range-dependent *** a result,the localization surface of VTRP can be formed faster than its MFP counterpart in a range-dependent *** performance of VTRP for source localization is validated through numerical simulations and data from the Mediterranean Sea.

关键词：匹配场处理时间反转定位方法虚拟多功能一体机浅水传播过程定位表面

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Use of the Jiaolong manned submersible for accurate mapping of deep-sea topography and geomorphology

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Science China Earth Sciences 2018年第8期61卷 1148-1156页

作者： tongwei zhang Jialing TANG Zhengguang LI Yubin ZHOU Xiangxin WANG National Deep Sea Center Qingdao 266237 China Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and Technology Qingdao 266061 China Joint Laboratory for Ocean Observation and Detection Qingdao National Laboratory for Marine Science and Technology Qingdao 266237 China

High-resolution bathymetric side-scan sonar(BSSS) performs the functions of traditional side-scan sonar, while also providing a depth-sounding function that allows simultaneous measurement of seafloor topography and geomorphology. Submarine microtopography and microgeomorphology detection ability and advanced underwater acoustic digital communication are important technical capabilities of the Jiaolong manned submersible. High resolution BSSS achieved accurate detection of seafloor topography and geomorphology at a depth of 7000 m, and successful mapping of local microtopography and microgeomorphology in the Mariana Trench.

关键词： Microtopography Microgeomorphology Manned submersible Deep sea High-resolution bathymetric side scan sonar Jiaolong

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Determination of the heating efficiency of magnetotactic bacteria in alternating magnetic field

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Journal of Oceanology and Limnology 2021年第6期39卷 2116-2126页

作者： tongwei zhang Huangtao XU Jia LIU Yongxin PAN Changqian CAO Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsInnovation Academy for Earth ScienceChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China France-China Joint Laboratory for Evolution and Development of Magnetotactic Multicellular Organisms Chinese Academy of SciencesBeijing 100029China

Magnetotactic bacteria(MTB)intact cells have been applied in magnetic hyperthermia therapy of tumor,showing great efficiency in heating for tumor cell ***,the detailed magnetic hyperthermia properties and optimum heat production conditions of MTB cells are still poorly understood due to lack of standard measuring *** specific absorption rate(SAR)of MTB cells is often measured by home-made equipment at a limited frequency and magnetic field *** this study,we have used a commercial standard system to implement a comprehensive study of the hyperthermic response of Magnetospirillum gryphiswaldense MSR-1 strain under 7 frequencies of 144-764 kHz,and 8 field amplitudes between 10 and 45 kA/*** measurement results prove that the SAR of MTB cells increases with magnetic field frequency and amplitude within a certain *** combination with the magnetic measurements,it is determined that the magnetic hyperthermia mechanism of MTB mainly follows the principle of hysteresis loss,and the heat efficiency of MTB cells in alternating magnetic field are mainly aff ected by three parameters of hysteresis loop,saturation magnetisation,saturation remanent magnetisation,and *** when we culture MTB in LA-2 medium containing sodium nitrate as source of nitrogen,the SAR of MTB LA-2 cells with magnetosomes arranged in chains can be as high as 4925.6 W/g(in this work,all SARs are calculated with iron mass)under 764 kHz and 30 kA/m,which is 7.5 times than current commercial magnetic particles within similar size range.

关键词： magnetotactic bacteria(MTB) hyperthermia rock magnetism alternating magnetic field(AMF)

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Kinetic Model of Gaseous Alkanes Formed from Coal in a Confined System and Its Application to Gas Filling History in Kuqa Depression,Tarim Basin,Northwest China

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Acta Geologica Sinica(English Edition) 2011年第4期85卷 911-922页

作者： LIU Quanyou zhang tongwei JIN Zhijun QIN Shengfei TANG Yongchun LIU Wenhui Exploration and Production Research Institute SINOPECBeijing 100083China Bureau of Economic Geology The University of Texas at Austin University StationAustinTexas 78713- 8924USA Power Environmental and Energy Research InstituteCalifornia 91722USA Research Institute of Petroleum Exploration and Development PetroChinaBeijing 100083China

Based on the pyrolysis products for the Jurassic low-mature coal under programmed temperature,and chemical and carbon isotopic compositions of natural gas from the Kuqa Depression, the genetic origin of natural gas was determined,and then a gas filling model was established,in combination with the geological background of the Kuqa *** active energy of CH_4,C_2H_6 and C_3H_8 was gotten after the data of pyrolysis gas products under different heating rates（2℃/h and 20℃/h）were fitted by the Gas Oil Ratio（GOR）Isotope Model *** the frequency factor（Af）was chosen as 1×10^（14）,the active energy of CH_4,C_2H_6 and C_3H_8 was 58 kcal/mol,57 kcal/mol and 54 kcal/ mol,*** distributive ranges of theδ^（13）C_1,δ^（13）C_2 andδ^（13）C_3 values for the pyrolysis gas products are-35.9‰to-30.7‰,-26.2‰to-21.3‰and-26.4‰to-22.7‰,*** of the natural gases from the Kuqa Depression are dominated by hydrocarbon gases,with the high gas dryness（C_1/C_（1-4））at the middle and northern parts of the depression and the low values at both east and west sides and the southern *** carbon isotopes of methane and its homologs as a typical coal-type gas are enriched in ^（13）C,and the distributive range of theδ^（13）C_1,δ^（13）C_2 andδ^（13）C_3 value is-32‰to -38‰,-22‰to-24‰and-20‰to-22‰,respectively,with the carbon isotopes of gaseous alkanes being less negative with the carbon *** the ethane being enriched in ^（13）C the increasing tendency of the geological reserve of natural gas in the Kuqa Depression is *** observed change is consistent with the results of pyrolysate gas yield of coal as a potential gas source in the Kuqa Depression,suggesting natural gas was thermally derived from the humic organic matters and the carbon isotopes of gaseous alkanes would coarsely predict the geological reserve of gas in the Kuqa *** the simulation of kinetic processes of gas generation for the Jurassic coal in the Kuqa Depression,the gas in th

关键词： natural gas gas kinetic carbon isotope gas-filling history Kuqa Depression

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ARTIFICIAL REGENERATION OF KOREAN SPRUCE IN NORTHEAST CHINA

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Journal of Northeast Forestry University 1990年第1期1卷 11-15页

作者： Zhan Hongzhcn (1) zhang tongwei (1) Wang Fengyou (1) 1. Northeast Forestry University 150040 Harbin P. R. China

Korean spruce(Picea koraiensis Nakai)has been included as a Chinese regenerationspecies since the 1960’*** the 1970’s it became one of the four most important species in thenortheast forest region of China. Korean spruce is a timber species with a wide range of adaptation,high survival rate,and few diseases or *** of 30—year trials show that the regeneration ofkorean spruce is successful and has a prospective future.

关键词： Korcan spruce Forest regencration conifer regencration

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MamZ protein plays an essential role in magnetosome maturation process of Magnetospirillum gryphiswaldense MSR-1

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Journal of Oceanology and Limnology 2021年第6期39卷 2082-2096页

作者： Sha WU Qing WANG Xu WANG Ruixue GUO tongwei zhang Yongxin PAN Feng LI Ying LI Engineering Technology Research Center of Ecological Restoration and Comprehensive Utilization of Coal Mining Collapse Area Anhui ProvinceAnhui Province Key Laboratory of Pollutant Sensitive Materials and Environmental RemediationCollege of Life SciencesHuaibei Normal UniversityHuaibei 235000China State Key Laboratories for Agro-biotechnology China Agricultural UniversityBeijing 100193China Paleomagnetism and Geochronology Laboratory Key Laboratory of Earth and Planetary PhysicsInstitute of Geology and GeophysicsChinese Academy of SciencesFrance-China Joint Laboratory for Evolution and Development of Magnetotactic Multicelluar OrganismsBeijing 100029China

Based on analysis of gene structure of mamXY operon in Magnetospirillum gryphiswaldense strain MSR-1,we constructed a mamZ deletion mutant strain(ΔmamZ)and four complemented strains with different mamZ fragment *** cell phenotypic and physiological parameters were evaluated and compared among the wild-type(WT),mutant,and complemented *** growth rates were not notably different;however,magnetic response(Cmag)and iron uptake ability were significantly lower inΔ***-resolution transmission electron microscopy(HR-TEM)showed that magnetosomes inΔmamZ were small and irregular,and rock magnetic measurements suggested that they contained immature *** comparison to WT of MSR-1,intracellular iron content ofΔmamZ and the complemented strains cultured with 20mmol/L iron source was similar or slightly *** complemented strains were unable to synthesize mature or normal amounts of magnetosomes,apparently because of abnormal expression of the transmembrane domain of MamZ ***-time reverse transcription polymerase chain reaction(RTqPCR)analysis showed that relative transcription levels of mamX and ftsZ-like genes inΔmamZ were higher at 18 h than at 12 h,suggesting that MamXY proteins play cooperative functional roles in the magnetosome maturation *** level of mms6 was significantly upregulated inΔmamZ(incubated at 12 h)and the complemented strains(incubated at 12 and 18 h),refl ecting possible interaction between MamXY and Mms6 proteins during magnetosome *** findings,taken together,demonstrate the essential role of MamZ in the magnetosome maturation process in MSR-1.

关键词： Magnetospirillum gryphiswaldense mamZ deletion mamXY operon magnetosome maturation

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Impact of train speed on the mechanical behaviours of track-bed materials

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第5期9卷 818-829页

作者： Francisco Lamas-Lopez Yu-Jun Cui Nicolas Calon Sofia Costa D’Aguiar tongwei zhang Laboratoire Navier/CERMES Ecole des Ponts ParisTech Marne-la-Vallée 77455 France Département Ligne Voie et Environnement SNCF-Engineering La Plaine St. Denis 93574 France Division Auscultation Modélisation & Mesures SNCF-Research & Development Paris 75012 France

For the 30,000 km long French conventional railway lines(94% of the whole network),the train speed is currently limited to 220 km/h,whilst the speed is 320 km/h for the 1800 km long high-speed ***,there is a growing need to improve the services by increasing the speed limit for the conventional *** paper aims at studying the influence of train speed on the mechanical behaviours of track-bed materials based on field monitoring *** is put on the behaviours of interlayer and subgrade *** selected experimental site is located in Vierzon,*** sensors including accelerometers and soil pressure gauges were installed at different *** vertical strains of different layers can be obtained by integrating the records of accelerometers installed at different trackbed *** experimentation was carried out using an intercity test train running at different speeds from 60 km/h to 200 km/*** test train was composed of a locomotive(22.5 Mg/axle) and 7 'Corail'coaches(10.5 Mg/axle).It was observed that when the train speed was raised,the loadings transmitted to the track-bed ***,the response of the track-bed materials was amplified by the speed rise at different depths:the vertical dynamic stress was increased by about 10% when the train speed was raised from 60 km/h to 200 km/h for the locomotive loading,and the vertical strains doubled their quasistatic values in the shallow ***,the stressestrain paths were estimated using the vertical stress and strain for each train *** loading paths allowed the resilient modulus Mrto be *** was found that the resilient modulus(M_r) was decreased by about 10% when the train speed was increased from 100 km/h to 200 km/***,the damping ratio(D_r) kept stable in the range of speeds explored.

关键词： Field experimentation Conventional track-bed materials Train speed upgrade Mechanical behaviours Reversible modulus Damping ratio

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Multi-step geoacoustic inversion with a towed line array

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Chinese Journal of Acoustics 2012年第2期31卷 189-201页

作者： QIU Haibin YANG Kunde DUAN Rui zhang tongwei College of Marine Northwestern Polytechnieal UniversityXi'an 710072 Southwestern Institute of Electronical Equipments Chengdu 610032

Geoacoustic inversion is important for acoustic field predictions and matched field localizations in shallow water. Combing the Matched-field inversion （MFI） and the Reflectionloss inversion, a multi-step Bayesian inversion for geoacoustic parameters was presented. This method applied the posterior probability density （PPD） or inversion results from one inversion as prior information for subsequent inversion. First, the sensitive parameters were determined by the MFI. Second, the insensitive parameters were determined by the Reflection-loss inversion based on the PPD and inversion results from the MFI. The PPD results indicated that the multi-step inversion method was performed better than direct matched-field inversion, and the inversion results of some parameters were improved significantly. To demonstrate the advantages of the multi-step inversion method on the sound field prediction, the statistical properties of transmission loss based on the posterior probability were introduced. The transmission loss distribution showed that the predicted acoustic fields based on the multi-step inversion method had smaller errors.

关键词：多步反转匹配场反演拖线阵概率统计特性小额信贷反演方法传输损耗

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Controlling Gas-liquid Flow and Heat Transfer in a T-junction Microchannel by Wettability-engineered Walls

Controlling Gas-liquid Flow and Heat Transfer in a T-junctio...

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第十一届全国流体力学学术会议

作者： zhang tongwei Wu Jie Lin Xingjian Department of Aerodynamics Nanjing University of Aeronautics and Astronautics

The gas-liquid flow and heat transfer characteristics in a cross-flow T-junction microchannel with wettability-engineered walls are numerically investigated in this *** diffuse interface(DI) method is adopted to predict the hydrodynamics of two-phase *** effects of wettability(wall contact angle) on bubble driving force and flow characteristics are *** three different flow patterns are presented for different combinations of bottom and top wall contact *** this basis,two methods are proposed to enhance the heat *** one is to increase the two-phase interfacial contact area by reasonably controlling the combination of wall contact angles,which can promote the heat exchange in two-phase *** other one is to increase the velocity fluctuation intensity by alternately changing the contact angle along the channel,which can enhance the mixing between hot liquid layer adjacent to the wall and the cool liquid *** two methods are applicative for steady and unsteady problems,*** flow patterns,velocity vectors and streamlines are shown to analyze the fluid and thermal mixing ***,the quantitative comparison of wall temperature is made at a given wall heat *** obtained results indicate that the use of wettability-engineered walls is a simple and practical approach to control two-phase flow and enhance heat transfer.

关键词： microchannel wettability-engineered walls driving force model two-phase flow heat transfer

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