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Research on shell-side heat and mass transfer with multi-component in LNG spiral-wound heat exchanger under sloshing conditions

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Petroleum Science 2024年第2期21卷 1333-1345页

作者： xue-ping Du Guang-Lei Yu Ya-Cheng xu zhi-Jie Chen Nai-Liang Li Huan-Guang Wang School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina Key Laboratory of Thermo-Fluid Science and Engineering MOEXi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Aerospace Propulsion Test Technology Institute Xi'an710100ShaanxiChina

The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure *** results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.

关键词： Spiral-wound heat exchanger Sloshing conditions Two-phase flow Multi-component Heat and mass transfer

Recent Progress in Arabidopsis Research in China： A Preface

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Journal of Integrative Plant Biology 2006年第1期48卷 1-4页

作者： zhi-Hong xu College of Life Sciences Peking University Beijing 100871 China Shanghai Institute of Plant Physiology and Ecology the Chinese Academy of Sciences Shanghai 200032 China

In 2002, a workshop on Arabidopsis research in China was held in Shanghai, when a small group of Chinese plant scientists was working on this model species. Since then, we have witnessed the rapid growth of Arabidopsis research in China. This special issue of Journal of Integrative Plant Biology is dedicated exclusively to the Fourth Workshop on Arabidopsis Research in China, scheduled on November 30, 2005, in Beijing. In addition to reports collected in this special issue, the Chinese Arabidopsis community has been able to make significant contributions to many research fields. Here, I briefly summarize recent advances in Arabidopsis research in China.

关键词： PREFACES & forewords BOTANY

Nonlinear Forced Vibration of Cantilevered Pipes Conveying Fluid

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Acta Mechanica Solida Sinica 2018年第1期31卷 32-50页

作者： zhi-Yuan Liu Lin Wang Xi-ping Sun Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment Wuhan 430074 China Tianjin Research Institute Water Transport Engineering M.O.T. Test Detection Center of Water Transport Engineering Tianjin 300356 China

The nonlinear forced vibrations of a cantilevered pipe conveying fluid under base excitations are explored by means of the full nonlinear equation of motion, and the fourth- order Runge-Kutta integration algorithm is used as a numerical tool to solve the discretized equations. The self-excited vibration is briefly discussed first, focusing on the effect of flow velocity on the stability and post-flutter dynamical behavior of the pipe system with parameters close to those in previous experiments. Then, the nonlinear forced vibrations are examined using several concrete examples by means of frequency response diagrams and phase-plane plots. It shows that, at low flow velocity, the resonant amplitude near the first-mode natural frequency is larger than its counterpart near the second-mode natural frequency. The second-mode frequency response curve clearly displays a softening-type behavior with hysteresis phenomenon, while the first-mode frequency response curve almost maintains its neutrality. At moderate flow velocity, interestingly, the first-mode resonance response diminishes and the hysteresis phenomenon of the second-mode response disappears. At high flow velocity beyond the flutter threshold, the frequency response curve would exhibit a quenching-like behavior. When the excitation frequency is increased through the quenching point, the response of the pipe may shift from quasiperiodic to periodic. The results obtained in the present work highlight the dramatic influence of internal fluid flow on the nonlinear forced vibrations of slender Pipes.

关键词： Pipe conveying fluid Base excitation Nonlinear dynamics Primary resonance,Superharmonie resonance Forced vibration

Quantum Neural Network for Quantum Neural Computing

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Research 2024年第1期2023卷 71-80页

作者： Min-Gang Zhou zhi-ping Liu Hua-Lei Yin Chen-Long Li Tong-Kai xu Zeng-Bing Chen National Laboratory of Solid State Microstructures School of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China MatricTime Digital Technology Co.Ltd. Nanjing 211899China

Neural networks have achieved impressive breakthroughs in both industry and *** to effectively develop neural networks on quantum computing devices is a challenging open ***,we propose a new quantum neural network model for quantum neural computing using(classically controlled)single-qubit operations and measurements on real-world quantum systems with naturally occurring environment-induced decoherence,which greatly reduces the difficulties of physical *** model circumvents the problem that the state-space size grows exponentially with the number of neurons,thereby greatly reducing memory requirements and allowing for fast optimization with traditional optimization *** benchmark our model for handwritten digit recognition and other nonlinear classification *** results show that our model has an amazing nonlinear classification ability and robustness to ***,our model allows quantum computing to be applied in a wider context and inspires the earlier development of a quantum neural computer than standard quantum computers.

关键词： quantum thereby breakthrough

Effect of relaxation time on the squeezed correlations of bosons for evolving sources in relativistic heavy-ion collisions

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Nuclear Science and Techniques 2022年第2期33卷 87-92页

作者： Wei-Ning Zhang Peng-zhi xu School of Physics Dalian University of TechnologyDalian 116024China College of Computer Science and Technology Jilin Normal UniversitySiping 136000China

The squeezed back-to-back correlation(SBBC)of a boson-antiboson pair is sensitive to the time distribution of the particle-emitting source,and the SBBC function for an evolving source is expected to be affected by the relaxation time of the *** this study,we investigated the effect of relaxation time on the SBBC *** propose a method for calculating the SBBC function with relaxation-time approximation for evolving *** functions of D^(0)D^(-0)in relativistic heavy-ion collisions were investigated using a hydrodynamic *** found that the relaxation time reduces the amplitudes of the SBBC *** becomes apparent for long relaxation times and large initial relative deviations of the chaotic and squeezed amplitudes from their equilibrium values in the temporal steps.

关键词： Relaxation time Squeezed back-to-back correlation Evolving source Relativistic heavy-ion collisions

Recent progress in the design and fabrication of MXene-based membranes

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Frontiers of Chemical Science and Engineering 2021年第4期15卷 820-836页

作者： Kai Qu Kang Huang zhi xu State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science and TechnologyShanghai 200237China State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China

Two-dimensional membranes have attracted significant attention due to their superior characteristics,and their ability to boost both flux and selectivity have led to their reputation as potential next-generation separation *** them,emerging MXene-based membranes play significant roles in the competitive membrane-separation *** this mini-review,we systematically discuss the assembly and separation mechanisms of these ***,we highlight strategies based on the crosslinking of MXene nanosheets and the construction of additional nanochannels that further enhance the permeabilities and anti-swelling properties of MXene-based membranes and meet the requirements of practical applications,such as gas-molecule sieving,ion sieving,and other small-molecule *** nanosheets can also be used as additives that introduce specific functionalities into hybrid *** addition,extended applications that use MXenes as scaffolds are also discussed.

关键词： MXene 2D materials membranes separation

Fracture characterization and permeability prediction by pore scale variables extracted from X-ray CT images of porous geomaterials

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Science China(Technological Sciences) 2020年第5期63卷 755-767页

作者： ZHAO zhi ZHOU Xiao-ping QIAN Qi-Hu School of Civil Engineering Chongqing UniversityChongqing 400045China State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact PLA University of Science and TechnologyNanjing 210014China

Pore scale variables(e.g.,porosity,grain size)are important indexes to predict the hydraulic properties of porous geomaterials.X-ray images from ten types of intact sandstones and another type of sandstone samples subjected to triaxial compression are used to investigate the permeability and fracture characteristics.A novel double threshold segmentation algorithm is proposed to segment cracks,pores and grains,and pore scale variables are defined and extracted from these X-ray CT images to study the geometric characteristics of microstructures of porous ***,novel relations among these pore scale variables for permeability prediction are established,and the evolution process of cracks is *** results indicate that the porescale permeability is prominently improved by *** addition,excellent agreements are found between the measured and the estimated pore scale variables and *** established correlations can be employed to effectively identify the hydraulic properties of porous geomaterials.

关键词： sandstones X-ray CT images pore scale variables permeability prediction cracks characterization

Microstructural evolution of titanium matrix composite coatings reinforced by in situ synthesized TiB and TiC by laser cladding

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International Journal of Minerals,Metallurgy and Materials 2010年第4期17卷 481-488页

作者： Jun Li zhi-shui Yu Hui-ping Wang Man-ping Li School of Materials Engineering Shanghai University of Engineering Science Shanghai 201620 China

Titanium-based composite coatings reinforced by in situ synthesized TiB and TiC particles were successfully fabricated on Ti6Al4V by laser cladding using Ti-B_4C-Al or Ti-B_4C-C-Al powders as the precursor *** microstructural and metallographic analyses were made by X-ray diffraction（XRD）,optical microscope（OM）,scanning electron microscopy（SEM）,and electron probe microanalysis （EPMA）.The results show that the coatings are mainly composed ofα-Ti cellular dendrites and a eutectic transformation product in which a large number of coarse and fine needle-shaped TiB and a few equiaxial TiC particles are homogeneously embedded.A thin dilution zone with a thickness of about 100μm is present at the interface,and it consists of a few TiB and TiC reinforcements and a large number of lamella grains growing parallel to the heat flux direction in which a thin needle-shaped microstructure exists due to the martensitic transformation. The microstructural evolution can be divided into four stages：precipitation and growth of primaryβ-Ti phase,formation of the binary eutecticumβ-Ti＋TiB,formation of the ternary eutecticumβ-Ti＋TiB＋TiC,and solid transformation fromβ-Ti toα-Ti.

关键词： coating laser cladding in-situ synthesis microstructure

Smooth Trajectory Planning for a Cable Driven Parallel Waist Rehabilitation Robot Based on Rehabilitation Evaluation Factors

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Chinese Journal of Mechanical Engineering 2023年第3期36卷 63-75页

作者： Yuan Li Bin Zi zhi Sun ping Zhao School of Mechanical Engineering Hefei University of TechnologyHefei 230009China

Rehabilitation robots can help physiatrists to assist patients in improving their movement *** to the interaction between rehabilitation robots and patients,the robots need to complete rehabilitation training on a safe *** paper presents an approach for smooth trajectory planning for a cable-driven parallel waist rehabilitation robot(CDPWRR)based on the rehabilitation evaluation ***,motion capture technology is used to collect the motion data of several volunteers in waist *** the impact of motion variability,the feature points at the center of the human pelvis are obtained after eliminating unreasonable data through rationality ***,point-to-point waist training trajectory planning based on quintic polynomial and cycloid functions,and multipoint waist training trajectory planning based on quintic B-spline functions are carried *** corresponding planned curves and kinematics characteristics using three methods are compared and ***,the rehabilitation evaluation factors are introduced to conduct smooth trajectory planning for waist training,and the waist trajectory with better compliance is obtained based on the safety and feasibility of waist ***,the physical prototype of the CDPWRR is built,and the feasibility and effectiveness of the proposed smooth trajectory planning method are proved by numerical analysis and experiments.

关键词： Waist rehabilitation robot Trajectory planning B-spline Rehabilitation evaluation factor