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Investigation of cracking mechanism of the first tunnel lining during double-arch tunnel construction

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Underground Space 2024年第1期14卷 1-17页

作者： Yi Sui Xiaohui Cheng Zuozhou Zhao Weibin ma Railway Engineering Research Institute China Academy of Railway Sciences Corporation LimitedBeijing 100081China School of Civil Engineering Tsinghua UniversityBeijing 100084China

To solve the engineering problem of the first tunnel lining cracking caused by the second tunnel construction of double-arch highway tunnels,a research method combining distributed optical-fibre monitoring,inversion analysis and numerical simulation that can reflect lining cracking was *** fibres were laid on opposite sides of the steel arches inside the first tunnel *** optical-fibre monitoring was conducted continuously during the second tunnel *** on the fibre-optic strain profile,the lining cracking was deduced and warned in *** mechanical behaviour of the steel arch was investigated by the inversion analysis,which took into consideration the integrated impact of axial force and flexural moment.A two-dimensional(2D)load-structure method–based numerical model was established,considering the influence of different load distributions in each construction *** total strain rotating crack constitutive model was applied to reflect the cracking behaviour of concrete lining in the simulation,and the model was calibrated and verified in the *** analysis between the simulated strain distribution and the distributed optical-fibre monitoring results was carried *** deformation mode and crack distribution of the lining were *** cracking mechanism was ***,the second tunnel construction led to the loading at the top of the middle partition wall and the release of rock pressure in the first *** these load changes,the secondary lining of the first tunnel cracked on the inner side of the top of the middle partition wall owing to tension,and compression-bending failure occurred near the right arch ***,the influence of the parameters on the lining force was analysed,and a construction optimisation scheme was proposed.

关键词： Double-arch tunnel Cracking mechanism Distributed optical-fibre sensing Inversion analysis Total strain rotating crack model Loadstructure method

The Multi-parameter Test of gravitational Wave Dispersion with Principal Component Analysis

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Research in Astronomy and Astrophysics 2024年第5期24卷 140-150页

作者： Zhi-Chu ma Rui Niu Wen Zhao CAS Key Laboratory for Research in galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

In this work, we consider a conventional test of gravitational wave(gW) propagation which is based on the phenomenological parameterized dispersion relation to describe potential departures from general Relativity(gR)along the propagation of gWs. But different from tests conventionally performed previously, we vary multiple deformation coefficients simultaneously and employ the principal component analysis(PCA) method to remedy the strong degeneracy among deformation coefficients and obtain informative posteriors. The dominant PCA components can be better measured and constrained, and thus are expected to be more sensitive to potential departures from the waveform model. Using this method we analyze ten selected events and get the result that the combined posteriors of the dominant PCA parameters are consistent with gR within 99.7% credible intervals. The standard deviation of the first dominant PCA parameter is three times smaller than that of the original dispersion parameter of the leading order. However, the multi-parameter test with PCA is more sensitive to not only potential deviations from gR but also systematic errors of waveform models. The difference in results obtained by using different waveform templates hints that the demands of waveform accuracy are higher to perform the multiparameter test with PCA. Whereas, it cannot be strictly proven that the deviation is indeed and only induced by systematic errors. It requires more thorough research in the future to exclude other possible reasons in parameter estimation and data processing.

关键词： gravitational waves-gravitation-black hole physics

Directly predicting N_(2) electroreduction reaction free energy using interpretable machine learning with non-DFT calculated features

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Journal of Energy Chemistry 2024年第10期97卷 139-148,I0004页

作者： Yaqin Zhang Yuhang Wang Ninggui ma Jun Fan Department of materials Science and Engineering City University of Hong KongHong Kong 999077China Center for Advanced Nuclear Safety and Sustainable Development City University of Hong KongHong Kong 9077China Department of Mechanical Engineering City University of Hong KongHong Kong 999077China

Electrocatalytic nitrogen reduction to ammonia has garnered significant attention with the blooming of single-atom catalysts(SACs),showcasing their potential for sustainable and energy-efficient ammonia ***,cost-effectively designing and screening efficient electrocatalysts remains a *** this study,we have successfully established interpretable machine learning(ML)models to evaluate the catalytic activity of SACs by directly and accurately predicting reaction gibbs free *** models were trained using non-density functional theory(DFT)calculated features from a dataset comprising 90 graphene-supported *** results underscore the superior prediction accuracy of the gradient boosting regression(gBR)model for bothΔg(N_(2)→NNH)andΔg(NH_(2)→NH_(3)),boasting coefficient of determination(R^(2))score of 0.972 and 0.984,along with root mean square error(RMSE)of 0.051 and 0.085 eV,***,feature importance analysis elucidates that the high accuracy of gBR model stems from its adept capture of characteristics pertinent to the active center and coordination environment,unveilling the significance of elementary descriptors,with the colvalent radius playing a dominant ***,Shapley additive explanations(SHAP)analysis provides global and local interpretation of the working mechanism of the gBR *** analysis identifies that a pyrrole-type coordination(flag=0),d-orbitals with a moderate occupation(N_(d)=5),and a moderate difference in covalent radius(r_(TM-ave)near 140 pm)are conducive to achieving high ***,we extend the prediction of activity to more catalysts without additional DFT calculations,validating the reliability of our feature engineering,model training,and design *** findings not only highlight new opportunity for accelerating catalyst design using non-DFT calculated features,but also shed light on the working mechanism of"black box"ML ***,the model provides valuable g

关键词： Nitrogen reduction Single-atom catalyst Interpretable machine learning graphene Non-DFT features

Analytical Verification of Performance of Deep Neural Network Based Time-synchronized Distribution System State Estimation

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1126-1134页

作者： Behrouz Azimian Shiva Moshtagh Anamitra Pal Shanshan ma School of Electrical Computer and Energy EngineeringArizona State UniversityTempeAZ 85281USA the School of Electrical Computer and Energy EngineeringArizona State UniversityTempeAZ 85281USA Quanta Technology RaleighNC 27607USA

Recently,we demonstrated the success of a time-synchronized state estimator using deep neural networks(DNNs)for real-time unobservable distribution *** this paper,we provide analytical bounds on the performance of the state estimator as a function of perturbations in the input *** has already been shown that evaluating perfor-mance based only on the test dataset might not effectively indi-cate the ability of a trained DNN to handle input *** such,we analytically verify the robustness and trustworthi-ness of DNNs to input perturbations by treating them as mixed-integer linear programming(MILP)*** ability of batch normalization in addressing the scalability limitations of the MILP formulation is also *** framework is val-idated by performing time-synchronized distribution system state estimation for a modified IEEE 34-node system and a real-world large distribution system,both of which are incompletely observed by micro-phasor measurement units.

关键词： Deep neural network(DNN) distribution system state estimation(DSSE) mixed-integer linear programming(MILP) robustness trustworthiness

guest-adaptive chiral coassembly of a conformationally locked host into supramolecular boxes and ladders through arene-perfluoroarene force

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Science China Chemistry 2024年第10期67卷 3482-3492页

作者： Weilong ma Xinyi Li Aiyou Hao Pengyao Xing School of Chemistry and Chemical Engineering Shandong UniversityJinan 250100China

Unveiling the role of weak non-covalent forces in chiral self-assembly is pivotal in the design and fabrication of functional chiroptical *** nature of arene-perfluoroarene(AP)force is the electrostatic attraction betweenπ-hole andπplanes of perfluoroarenes and polyaromatic hydrocarbons(PAHs),which is emerging in constructing supramolecular motifs and coassembled optical *** this work,we reveal the potential of AP forces in building diversified levels of chiral coassemblies adaptive to the geometries of *** naphthalene-F8was covalently conjugated with a chiral amine,which folded into a semi-rectangular geometry via two intramolecular F···H *** of naphthalene,anthracene,pyrene,carbazole,perylene and benzoperylene were introduced to afford coassemblies in the crystalline state.X-ray structures suggest the formation of supramolecular boxes that encapsulate the PAHs with a 2:1 stoichiometric ratio,as well as the formation of consecutive layered ladders with a 1:1 stoichiometric *** preference is adaptive to the geometries of PAHs,and experimental and computational results evidenced the ladder structures possess strong binding *** this top,the selective chiral recognition in the mixtures of PAHs was realized,which shows promising applications in the separation of PAHs and rational design of crystalline chiroptical materials.

关键词： arene-perfluoroarene force coassembly supramolecular chirality selectivity

Enhanced Flexoelectric Response from Functionally gradient Electrets Undergoing Crumpling Deformation

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Acta Mechanica Solida Sinica 2024年第4期37卷 541-554页

作者： Jianhua ma Jinrui Xu Jun Li Binglei Wang Department of Engineering Mechanics Shandong UniversityJinan250061China

Non-uniform deformation of the dielectric subjected to external forces can induce the flexoelectric effect, a phenomenon that couples electrical polarization to strain gradients. However, limited by the size effects, flexoelectricity is not significant at the macroscale and only becomes catchable at the microscale and nanoscale. In recent work, we obtained a considerable flexoelectric-like response by crumpling the dielectric embedded with charges, i.e., the electret, which significantly improved the flexoelectric effect at the macroscale. In this work, we further optimize the macroscopic performance of the flexoelectric response by applying gradient treatment to the electret films. Specifically, we analytically derive the electromechanical coupling of crumpled electret films with gradients of different thicknesses, charge densities, and Young’s moduli as key design variables. It is shown that the gradient-oriented electret film can be tuned to nearly five times that of a uniform electret film.

关键词： Functionally gradient electret Size effects Crumpling Flexoelectric-like response

Accelerated heterogenous ring-opening polymerization towards well-defined helical poly(N-allyl alanine)with clickable side chains

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Science China Chemistry 2024年第6期67卷 2056-2062页

作者： Anyao ma Xin Wang Sunting Xuan Zhengbiao Zhang College of Chemistry Chemical Engineering and Materials ScienceSoochow UniversitySuzhou215123China State Key Laboratory of Radiation Medicine and Protection Soochow UniversitySuzhou215123China

Well-defined poly(N-allyl alanine)has been synthesized by heterogenous ring-opening polymerization(HROP)of less reactive N-allyl-alanine N-carboxyanhydride,using acetic acid as the catalyst and benzylamine as the initiator,in non-polar ***,the polymerization exhibited typical features of living polymerization though both monomer(liquid)and polymer(solid)have minimal solubility in *** obtained polymer showed a stable helix structure independent of the temperatures screened,as evidenced by circular dichroism ***,the preliminary study demonstrated that the side chains can be post-functionalized through thiol-ene click chemistry with quantitative ***,this work provides guidance for the development of accelerated HROP of other liquid monomers bearing low ***,the helical and functionalizable poly(N-allyl alanine)could be a useful“clickable platform”for the design of variable biomaterials via efficient click chemistry.

关键词： heterogenous ring-opening polymerization controlled polymerization stable helix clickable N-substituted polypeptide di-substituted polypeptoid

Clathrate metal superhydrides under high-pressure conditions: enroute to room-temperature superconductivity

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National Science Review 2024年第7期11卷 33-46页

作者： Ying Sun Xin Zhong Hanyu Liu Yanming ma Key Laboratory of material Simulation Methods&Software of Ministry of Education College of Physics Jilin University State Key Laboratory of Superhard materials College of PhysicsJilin University International Center of Future Science Jilin University

Room-temperature superconductivity has been a long-held dream of mankind and a focus of considerable interest in the research field of superconductivity. Significant progress has recently been achieved in hydrogen-based superconductors found in superhydrides（hydrides with unexpectedly high hydrogen contents） that are stabilized under high-pressure conditions and are not capturable at ambient *** particular interest is the discovery of a class of best-ever-known superconductors in clathrate metal superhydrides that hold the record for high superconductivity(e.g. Tc= 250–260 K for LaH10) among known superconductors and have great promise to be those that realize the long-sought room-temperature superconductivity. In these peculiar clathrate superhydrides, hydrogen forms unusual ‘clathrate’ cages containing encaged metal atoms, of which such a kind was first reported in a calcium hexa-superhydride（CaH6） showing a measured high Tcof 215 K under a pressure of 170 gPa. In this review, we aim to offer an overview of the current status of research progress on the clathrate metal superhydride superconductors,discuss the superconducting mechanism and highlight the key features（e.g. structure motifs, bonding features, electronic structure, etc.） that govern the high-temperature superconductivity. Future research direction along this line to find room-temperature superconductors will be discussed.

关键词： clathrate superhydrides high-temperature superconductivity high-pressure conditions crystal structure prediction

Electrocatalytic coupling of anodic nitrogen oxidation and cathodic nitrate reduction for ammonia synthesis from air and water

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Nano Research 2024年第9期17卷 7824-7829页

作者： Aijing ma Jianzhou gui Yanmei Huang Yifu Yu State Key Laboratory of Separation Membranes and Membrane Processes Tianjin Key Laboratory of Green Chemical Technology and Process EngineeringSchool of Chemical Engineering and TechnologyTiangong UniversityTianjin 300387China Institute of Molecular Plus School of Chemical EngineeringTianjin UniversityTianjin 300072China

Ammonia plays a vital role in present agriculture and industry,and is also regarded as a next-generation clean energy *** development of electrocatalysis raises an opportunity to make ammonia synthesis compatible with intermittent and variable renewable energy sources such as solar and wind ***,the direct ammonia electrosynthesis from N_(2)reduction is still challenging due to the much easier hydrogen evolution competition *** this perspective,we propose a novel strategy for ammonia electrosynthesis from air and water based on the coupling of anodic nitrogen oxidation and cathodic nitrate *** methods for breaking the bottlenecks of anodic nitrogen oxidation and cathodic nitrate reduction are discussed *** that,key issues that need to be considered in the coupled system are proposed for the application of this strategy.

关键词： electrocatalysis nitrogen oxidation nitrate reduction nitrogen fixation ammonia synthesis