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Feasibility study on buoyancy-weight ratios of a submerged floating tunnel prototype subjected to hydrodynamic loads

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Acta Mechanica Sinica 2015年第5期31卷 750-761页

作者： xu long Fei Ge Youshi Hong School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical University State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences

The research progress of a novel traffic solution,a submerged floating tunnel（SFT）,is reviewed in terms of a study approach and loading *** existing publications,the buoyancy-weight ratio（BWR） is usually ***,BWR is a critical structural parameter that tremendously affects the dynamic behaviour of not only the tunnel tube itself but also the cable *** the context of a SFT prototype（SFTP） project in Qiandao Lake（Zhejiang Province,China）,the importance of BWR is illustrated by finite element analysis and subsequently,an optimized BWR is proposed within a reasonable range in the present *** the numerical model,structural damping is identified to be of *** damping and the corresponding Rayleigh coefficients are attained through a sensitivity study,which shows that the adopted damping ratios are fairly suitable for ***,the human sense of security is considered by quantifying the comfort index,which helps further optimize BWR in the SFTP structural parameter design.

关键词： Submerged floating tunnel Buoyancy-weight ratio Water wave and current loads Dynamic response Human security sense Comfort index

Rapid and chemoselective imidation of sulfides in aqueous buffer enabled by a novel guanidine-derived N-O reagent

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Science China Chemistry 2024年第6期67卷 1929-1934页

作者： Hanzheng Li long xu Jiajia Dong Key Laboratory of Organofluorine Chemistry Center for Excellence in Molecular SynthesisShanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai200032China Institute of Translational Medicine National Facility for Translational Medicine(Shanghai)Shanghai Jiao Tong UniversityShanghai200240China School of Chemistry and Chemical Engineering Zhangjiang Institute for Advanced StudyShanghai Jiao Tong UniversityShanghai200240China Shanghai Artificial Intelligence Laboratory Shanghai200232China

Herein we report the facile synthesis of a series of novel N-O reagents and identify N′-di-Boc-N′′-[(mesitylsulfonyl)oxy]-guanidine as an efficient imidating *** reagent is synthetically scalable and bench-stable,yet it shows unprecedented reactivity and chemoselectivity towards S(II)in buffer/hexafluoroisopropanol(HFIP)system,to generate a new class of Nguanyl *** transformation of N-guanyl sulfilimines to N-guanyl sulfoximines provides us a chance to investigate these rarely reached compounds,which are shown to be versatile precursors to a variety of N-heterocyclic and *** work provides an addition to the tool box of both sulfur imidation and guanidine synthesis,especially for the need of rapid and selective modifications of sulfur(II)center under biocompatible conditions.

关键词： sulfur imidation N-O reagent

Plasma Replacement Therapy for Alzheimer's Disease

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Neuroscience Bulletin 2020年第1期36卷 89-90页

作者： xu-long Ding Peng Lei Department of Neurology and State Key Laboratory of Biotherapy West China HospitalSichuan UniversityChengdu 610041China West China School of Basic Medical Sciences and Forensic Medicine Sichuan UniversityChengdu 610041China Collaborative Innovation Center for Biotherapy Chengdu 610041China

Alzheimer’s disease(AD)is the most common neurode-generative disease that affects memory,thinking,behavior,and the ability to perform everyday *** has been estimated that more than 35 million people worldwide suffered from AD in 2018[1],and this figure continues to ***,no cure or treatment that slows the progression of the disease has been discovered despite extensive efforts from academics and the pharmaceutical *** drug trials for AD have targeted the 13-amyloid protein[2],which accumulates in this disease,and the failure of amyloid-based drugs to impact on cognition in people with AD has led to re-questioning of the amyloid hypothesis of AD,and has provided a fresh impetus to explore alternative therapeutic strategies.

关键词： Alzheimer drugs everyday

Understanding Tunneling Ionization of Atoms in Laser Fields using the Principle of Multiphoton Absorption

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Chinese Physics Letters 2019年第4期36卷 19-23页

作者： long xu Li-Bin Fu Graduate School of China Academy of Engineering Physics

The elaborate energy and momentum spectra of ionized electrons from atoms in laser fields suggest that the ionization dynamics described by tunneling theory should be modified. Although great efforts have been carried out within semiclassical models, there are few discussions describing the multiphoton absorption process within a quantum framework. Comparing the results obtained with the time-dependent Schr?dinger equation(TDSE)and the Keldysh–Faisal–Reiss(KFR) theory, we study the nonperturbative effects of ionization dynamics beyond the KFR theory. The difference in momentum spectra between multiphoton and tunneling regimes is understood in a unified picture with virtual multiphoton absorption processes. For the multiphoton regime, the momentum spectra can be obtained by coherent interference of each periodic contribution. However, the interference of multiphoton absorption peaks will result in a complex structure of virtual multiphoton bands in the tunneling regime. It is shown that the virtual spectra will be almost continuous in the tunneling regime instead of the discrete levels found in the multiphoton regime. Finally, with a model combining the TDSE and the KFR theory,we try to understand the different effects of virtual multiphoton processes on ionization dynamics.

关键词： Laser Multiphoton Absorption ionized electrons

Physics-informed Neural Network for Force-free Magnetic Field Extrapolation

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Research in Astronomy and Astrophysics 2024年第10期24卷 159-169页

作者： Yao Zhang long xu Yihua Yan State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 101408China Faculty of Information Science and Engineering Ningbo UniversityNingbo 315211China

In this paper,we propose a physics-informed neural network extrapolation method that leverages machine learning techniques to reconstruct coronal magnetic *** enhance the classical neural network structure by introducing the concept of a quasi-output layer to address the challenge of preserving physical constraints during the neural network extrapolation ***,we employ second-order optimization methods for training the neural network,which are more efficient compared to the first-order optimization methods commonly used in classical machine *** approach is evaluated on the widely recognized semi-analytical model proposed by Low and *** results demonstrate that the deep learning method achieves high accuracy in reconstructing the semianalytical model across multiple evaluation *** addition,we validate the effectiveness of our method on the observed magnetogram of active region.

关键词： Sun:magnetic fields Sun:corona magnetohydrodynamics(MHD)

A Network Selection Scheme Based on TOPSIS in Heterogeneous Network Environment

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Journal of Harbin Institute of Technology(New Series) 2014年第1期21卷 43-48页

作者： long xu Yi Li School of Telecommunication Engineering Beijing University of Posts and Telecommunications

This paper deals with network selection problem for users in heterogeneous network environment. The main context is to improve the TOPSIS( Technique for Order Preference by Similarity to Ideal Solution) network scheme by combining the network properties and the users' requirement accurately and decrease ping-pong effect. The method of entropy and FAHP( Fuzzy Analytic Hierarchy Process) are used to calculate weight value and the sojourn time calculation is used to avoid ping-pang effect. The simulation results show that the improved scheme enhances the more accuracy of network selection than the existing methods and reduces the number of ping-pang effect.

关键词： network selection sojourn time FAHP entropy TOPSIS

Identification of Mechanical Properties of Thin-Film Elastoplastic Materials by Machine Learning

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Acta Mechanica Solida Sinica 2023年第1期36卷 13-21页

作者： xu long Changheng Lu Ziyi Shen Yutai Su School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710129China

Nanoindentation can effectively evaluate the mechanical properties of materials in the form of bulk and ***,the relationship between the indentation response and the stress–strain curve of thin-film elastoplastic materials is complex and thus difficult to be elucidated using traditional physics-based,empirical or statistical *** this study,the convolutional neural network(CNN),as a practical machine learning method,is adopted and trained to rapidly obtain the mechanical properties of thin-film elastoplastic materials using *** proposed method is targeted for efficiently predicting mechanical properties of thin-film materials from the applied load–penetration depth *** with the power-law model to describe the elastoplastic characteristics,a dataset comprising 228 nanoindentation cases with wide ranges of material properties is numerically simulated by ABAQUS and the corresponding results are adopted for the CNN training and *** addressing the important elastoplastic properties characterized by elastic modulus,yield strength,and hardening exponent,the impacts of CNN’s architecture and training epochs on the predicting performance are investigated in *** varying the number of convolutional layers,the influence of mechanical parameters of thin-film materials on the CNN prediction accuracy is *** results show that compared with the traditional reverse algorithm,CNN can greatly reduce the computational complexity and computation time and has better prediction accuracy for the constitutive parameters of thin-film elastoplastic materials.

关键词： Machine learning Nanoindentation Thin-film material Elastoplasticity Constitutive parameters

^(12)CO J=2-1 and^(12)CO J=3-2 observations toward the high-mass protostellar candidate IRAS 20188+3928

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Research in Astronomy and Astrophysics 2013年第1期13卷 39-46页

作者： Jin-long xu Jun-Jie Wang National Astronomical Observatories Chinese Academy of Sciences NAOC-TU Joint Center for Astrophysics

We have carried out observations of 12CO J=2-1 and 12CO J=3-2 to- ward the high-mass protostellar candidate IRAS 20188＋3928. Compared with previ- ous observations, the 12CO J=2-1 and 12CO J=3-2 lines both have asymmetric pro- files with an absorption dip. The velocity of the absorption dip is ~ 1.0 km s-1. The spectral shape may be caused by rotation. The velocity-integrated intensity map and position-velocity diagram of the 12CO J=2-1 line present an obvious bipolar com- ponent, further verifying that this region has an outflow motion. This region is also associated with an HII region, an IRAS source, and an H20 maser. The H20 maser has the velocity of 1.1 km s-1. Compared with the components of the outflow, we find that the H20 maser is not associated with the outflow. Using the large velocity gradi- ent model, we concluded that possible averaged gas densities of the blueshifted lobe and redshifted lobe are 1.0x 105 cm-3 and 2.0x 104 cm-a, while kinetic temperatures are 26.9 K and 52.9 K, respectively. Additionally, the outflow has a higher integrated intensity ratio （Ico J=3 - 2/Ico J=2 - 1）.

关键词： ISM: individual (IRAS 20188+3928) -- ISM: kinematics and dynamics-- ISM: molecules -- stars: formation

Submillimeter/millimeter observations of the high-mass star forming region IRAS 22506+5944

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Research in Astronomy and Astrophysics 2010年第2期10卷 151-158页

作者： Jin-long xu Jun-Jie Wang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China NAOC-TU Joint Center for Astrophysics Lhasa 850000 China

The mapping observations of CO J -- 2-1, CO J = 3- 2, 13CO J = 2-1 and 13CO J -- 3 - 2 lines in the direction of IRAS 22506＋5944 have been made. The results show that the cores in the J = 2 - i transition lines have a similar morphology to those in the J -- 3 - 2 transition lines. Bipolar molecular outflows are verified. The prior IRAS 22506＋5944 observations indicated that two IRAS sources and three H20 masers were located close to the peak position of the core. One of the IRAS sources may be the driving source of the outflows. In addition, the H20 masers may occur in relatively warm environments. The parameters of the dense core and outflow, obtained by the LTE method, indicate that IRAS 22506＋5944 is a high-mass star formation region.

关键词： ISM: jets and outflows -- ISM: kinematics and dynamics -- ISM molecules -- stars: formation