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A novel complex network-based deep learning method for characterizing gas-liquid two-phase flow

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Petroleum Science 2021年第1期18卷 259-268页

作者： Zhong-Ke Gao ming-xu liu Wei-Dong Dang Qing Cai School of Electrical and Information Engineering Tianjin UniversityTianjin 300072TianjinChina

Gas-liquid two-phase flow widely exits in production and transportation of petroleum *** gas-liquid flow and measuring flow parameters represent challenges of great importance,which contribute to the recognition of flow regime and the optimal design of industrial *** this paper,we propose a novel complex network-based deep learning method for characterizing gas-liquid ***,we map the multichannel measurements to multiple limited penetrable visibility graphs(LPVGs)and obtain their degree sequences as the graph *** on the degree distribution,we analyze the complicated flow behavior under different flow ***,we design a dual-input convolutional neural network to fuse the raw signals and the graph representation of LPVGs for the classification of flow structures and measurement of gas void *** implement the model with two parallel branches with the same structure,each corresponding to one *** branch consists of a channel-projection convolutional part,a spatial-temporal convolutional part,a dense block and an attention *** outputs of the two branches are concatenated and fed into several full connected layers for the classification and *** last,our method achieves an accuracy of 95.3%for the classification of flow structures,and a mean squared error of 0.0038 and a mean absolute percent error of 6.3%for the measurement of gas void *** method provides a promising solution for characterizing gas-liquid flow and measuring flow parameters.

关键词： Gas-liquid flow Gas void fraction Flow structure Limited penetrable visibility graph Deep learning

A cross-layer approach to enable multipacket transmission in MIMO-SDMA based WLAN

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第2期10卷 271-278页

作者： Sheng-bo CHEN Wei CHEN Wei-lan HUANG Li-jun ZHAI xu-ming liu Department of Electronic Engineering. Tsinghua University Beijing 100084 China Nokia Research Center Beijing 100176 China

We propose a medium access control(MAC) protocol for uplink transmissions in wireless local area networks(WLANs),where both stations and access points(APs) are equipped with multiple antennas. The protocol solves some common problems in utilizing multiple input multiple output(MIMO) under the 802.11 protocol,e.g.,how to deploy preamble(training sequence) used for channel estimation and how to enable simultaneous data transmissions,and facilitates two simultaneous uplink data transmissions via a cross-layer approach. Furthermore,we develop a 3D discrete-time Markov model to analyze the per-formance of the proposed WLAN scheme. The analytical results are verified by simulation,and numerical results show that the system throughput can be significantly improved by our proposed scheme as compared with conventional schemes.

关键词： Multiple input multiple output (MIMO) Medium access control (MAC) Cross-layer design

Effect of drying-wetting cycles on pore characteristics and mechanical properties of enzyme-induced carbonate precipitation-reinforced sea sand

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 291-302页

作者： ming Huang Kai xu Zijian liu Chaoshui xu mingjuan Cui College of Civil Engineering Fuzhou UniversityFuzhou350108China Xiamen Rail Transit Construction and Development Group Co. Ltd.Xiamen361000China School of Civil Environment and Mining EngineeringThe University of AdelaideAdelaide5005Australia

Enzyme-induced carbonate precipitation(EICP)is an emanating,eco-friendly and potentially sound technique that has presented promise in various geotechnical ***,the durability and microscopic characteristics of EICP-treated specimens against the impact of drying-wetting(D-W)cycles is under-explored *** study investigates the evolution of mechanical behavior and pore charac-teristics of EICP-treated sea sand subjected to D-W *** uniaxial compressive strength(UCS)tests,synchrotron radiation micro-computed tomography(micro-CT),and three-dimensional(3D)recon-struction of CT images were performed to study the multiscale evolution characteristics of EICP-reinforced sea sand under the effect of D-W *** potential correlations between microstructure characteristics and macro-mechanical property deterioration were investigated using gray relational analysis(GRA).Results showed that the UCS of EICP-treated specimens decreases by 63.7% after 15 D-W *** proportion of mesopores gradually decreases whereas the proportion of macropores in-creases due to the exfoliated calcium carbonate with increasing number of D-W *** micro-structure in EICP-reinforced sea sand was gradually disintegrated,resulting in increasing pore size and development of pore shape from ellipsoidal to columnar and *** gray relational degree suggested that the weight loss rate and UCS deterioration were attributed to the development of branched pores with a size of 100-1000 m m under the action of D-W ***,the results in this study provide a useful guidancee for the long-term stability and evolution characteristics of EICP-reinforced sea sand under D-W weathering conditions.

关键词： Enzyme-induced carbonate precipitation(EICP) Plant-based urease Drying-wetting(D-W)cycles Microstructure

A review of thickness-induced evolutions of microstructure and superconducting performance of REBa2Cu3O7-δ coated conductor

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Advances in Manufacturing 2017年第2期5卷 165-176页

作者： Jian-Xin Lin xu-ming liu Chuan-Wei Cui Chuan-Yi Bai Yu-ming Lu Feng Fan Yan-Qun Guo Zhi-Yong liu Chuan-Bing Cai Shanghai Key Laboratory of High Temperature Superconductors Shanghai University Shanghai 200444People's Republic of China

The research and development of high temperature superconducting （HTS） films, especially ReBa2Cu3- O7-δ （REBCO or RE123; RE=Y, Gd, or other rare earths） yttrium-based coated conductors, has generated widespread interest for the potential applications of the second generation superconducting films. In view of commercialization, however, the maximum superconducting currents for coated conductors should be increased further. Unfortunately, it has been frequently observed that the average critical current density Jc decreases with an increase in film thickness. The thickness effect is still a hurdle for largescale production, especially in pulsed laser deposition and metal organic deposition processes. An engineering current of more than 1 000 A/cm is desired owing to the high cost of 2G superconducting materials. The present work attempts to review the evolution of various issues subject to the thickness effect, including the microstructure, epitaxial texture, surface roughness, pinning force, oxygen deficiency, residual stress, copper-rich layers, and segregation of elements. Furthermore, recent progress in enhancing the performance of superconductors especially in terms of critical current density is illustrated, such as the use of heavy doping. Further understanding of the thickness effect is extremely important for large-scale commercial development of the second generation high temperature superconductors.

关键词： Thickness effect Superconducting film Critical current density Microstructure Epitaxial texture Pinning force

Experimental realization of deterministic joint remote preparation of an arbitrary two-qubit pure state via GHZ states

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Science China(Information Sciences) 2024年第3期67卷 317-318页

作者： Nachuan LI Lu xu Jin-ming liu State Key Laboratory of Precision Spectroscopy School of Physics and Electronic ScienceEast China Normal University Hefei Origin Quantum Computing Technology Co. Ltd.

Quantum teleportation(QT) [1] enables secure transfer of an unknown quantum state between remote locations without physically transmitting the initial state. Unlike QT,with the sender possessing complete knowledge of the initial state, remote state preparation(RSP) [2] exhibits a tradeoff between the amount of the entanglement resource used and the classical communication cost.

关键词： Quantum communication

Twisted Integration of Complex Oxide Magnetoelectric Heterostructures via Water‑Etching and Transfer Process

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Nano-Micro Letters 2024年第1期16卷 360-369页

作者： Guannan Yang Guohua Dong Butong Zhang xu xu Yanan Zhao Zhongqiang Hu ming liu State Key Laboratory for Manufacturing Systems Engineering Electronic Materials Research LaboratoryKey Laboratory of the Ministry of EducationEngineering Research Center of Spin Quantum Sensor ChipsUniversities of Shaanxi ProvinceSchool of Electronic Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China

Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain *** recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal ***,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical *** this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3PbTiO_(3)(011)(LSMO/PMN-PT)heterostructures with *** *** angles were assembled via water-etching and transfer *** transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°*** fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial *** work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.

关键词： Magnetoelectric heterostructures Twist angle Epitaxial lift-off Magnetic anisotropy Ferromagnetic resonance

Estimation of free core nutation parameters and availability of computing options

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Geodesy and Geodynamics 2024年第1期15卷 61-74页

作者： Weiwei Yang Xiaoming Cui Jianqiao xu Qingchao liu ming Qin State Key Laboratory of Geodesy and Earth's Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430077China University of Chinese Academy of Sciences Beijing 100049China Hubei Luojia Laboratory Wuhan 430079China

The Earth’s Free Core Nutation(FCN) causes Earth tides and forced nutation with frequencies close to the FCN that exhibit resonance ***-precision superconducting gravimeter(SG) and very long baseline interferometry(VLBI) provide good observation techniques for detecting the FCN ***,some choices in data processing and solution procedures increase the uncertainty of the FCN *** this study,we analyzed the differences and the effectiveness of weight function and ocean tide corrections in the FCN parameter detection using synthetic data,SG data from thirty-one stations,and the 10 celestial pole offset(CPO) *** results show that significant discrepancies are caused by different computing options for a single SG *** stacking method,which results in a variation of0.24-5 sidereal days(SDs) in the FCN period(T) and 10^(3)-10^(4) in the quality factor(Q) due to the selection of the weighting function and the ocean tide model(OTM),can effectively suppress this *** statistical analysis results of synthetic data shows that although different weight choices,while adjusting the proportion of diurnal tidal waves involved,do not significantly improve the accuracy of fitted FCN parameters from gravity *** study evaluated a series of OTMs using the loading correction *** fitting of FCN parameters can be improved by selecting the mean of appropriate OTMs based on the evaluation *** the estimation of the FCN parameters based on the forced nutation,it was found that the weight function P_(1) is more suitable than others,and different CPO series(after 2009) resulted in a difference of 0.4 SDs in the T and of 103 in the *** estimated the FCN parameters for SG(T=430.4±1.5 SDs and Q=1.52×10^(4)±2.5×10^(3)) and for VLBI(T=429.8±0.7 SDs,Q=1.88×10^(4)±2.1×10^(3)).

关键词： Free core nutation Superconducting gravimeter Very long baseline interferometry Weight function Ocean tide model

An improved analysis method for assessing the nuclear-heating impact on the stability of toroidal field magnets in fusion reactors

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Nuclear Science and Techniques 2024年第6期35卷 163-176页

作者： Yu-Dong Lu Jin-Xing Zheng xu-Feng liu Huan Wu Jian Ge Kun xu ming Li Hai-Yang liu Lei Zhu Fei liu Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement,a process that can be dis-rupted by various operational factors.A critical parameter for evaluating the temperature margin of superconducting magnets during normal operation is the nuclear heating caused by D-T *** study investigates the impact of nuclear heat-ing on a superconducting magnet system by employing an improved analysis method that combines neutronics and thermal *** the magnet system,toroidal field(TF)magnets are positioned closest to the plasma and bear the highest nuclear-heat load,making them prime candidates for evaluating the influence of nuclear heating on *** enhance the modeling accuracy and facilitate design modifications,a parametric TF model that incorporates heterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations.A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improves accuracy by over 12%.Considering factors such as heat load,magnetic-field strength,and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the *** selection streamlines the workload associated with thermal-hydraulic *** approach enables a more efficient and precise evaluation of the temperature margin of TF ***,it offers insights that can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.

关键词： Superconducting magnet Nuclear heating Neutronics Thermal hydraulics

Influence of erosion voids and traffic loads on buried large-diameter reinforced concrete pipes

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Underground Space 2024年第4期17卷 120-131页

作者： ming xu Dawei Shen Department of Civil Engineering Tsinghua UniversityBeijing 100084China Beijing Institute of Technology Beijing 100081China

Geotechnical centrifuge tests were conducted to examine the influence of invert voids and surface traffic loads on 1400 mm diameter reinforced concrete pipes buried with a shallow soil cover depth of 700 *** formation beneath the pipe was simulated during centrifuge *** test results revealed that before void formation,the surface load directly above the middle of the pipe caused a significant increase in not only the circumferential bending moments but also the longitudinal bending moments,the latter of which was considerable and could not be *** formation beneath the middle of the pipe led to a reduction in both the circumferential bending moments and longitudinal bending moments at all measuring positions,i.e.,crown,springline,and *** most significant reduction occurred at the invert,and there was even a reversal in the sign of the invert longitudinal bending moment.A comparison was made between centrifuge tests with erosion voids and surface loads at different horizontal positions,which had a marked influence even when the positions differed by half a pipe *** rotation played an important role in relieving large bending moments of pipe barrels in a jointed pipeline when the void and surface load were located at the joint.

关键词： Centrifuge test Erosion void Reinforced concrete pipe Traffic loading Longitudinal bending moment Joint rotation