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Modified ground response curve(GRC)in strain-softening rock mass based on the generalized Zhang-Zhu strength criterion considering over-excavation

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Underground Space 2021年第5期6卷 585-602页

作者： Chen Xu Caichu xia Changling han Institute of Rock Mechanics Ningbo UniversityNingboZhejiangChina Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghaiChina CCCC First Highway Consultants Co. LtdXi’anShaanxiChina

The ground response curve(GRC)depicts the relationship between support reaction force and ground displacement,which improves the understanding of ground-support interaction and provides important references to the tunnel ***,it is difficult to anticipate the tunneling-induced large deformation with sufficient reliability in soft rock with high geostress since the small strain theory is not *** large deformation occurs,the tunnel needs to be ***,the GRC should be modified considering the enlarged excavation radius since the actual excavation radius is usually greater than the designed *** overcome the shortcomings of small strain theory in recognizing ground-support interaction under large deformation circumstances,a new large strain numerical approach for modifying the GRC was proposed considering over-excavation in strain-softening rock masses based on the generalized Zhang-Zhu strength criterion.A case study was conducted based on the Lianchengshan tunnel in *** modified GRC was employed to investigate the ground-support behavior for different support schemes and to explore the applicability of the stress release *** with field tests,the proposed approach was *** comparing with GRCs proposed by previous work,the present modified GRC was proved to be superior to *** studies were conducted and it is found that over-excavation,for example,reserving a very large clearance between the surrounding rock and the support,is necessary to reduce ground pressure to a large *** yielding supports which can provide high support pressure during the process of deformation are highly recommended when tunneling in high geostress ***,if the initial geostress is not very high,it is not necessary to pursue unwarranted overexcavation since the ground pressure applied on the support is mainly the loosening stress when the deformation is *** support stiffness should be provi

关键词： Ground response curve Large strain Over-excavation Strain-softening Soft rock tunnel

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GENERALIZED H-KKM TYPE THEOREMS IN H-METRIC SPACES WITH APPLICATIONS

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Applied Mathematics and Mechanics(English Edition) 2001年第10期22卷 1140-1148页

作者： DING Xie-ping(丁协平) xia Fu-quan(夏福全) Department of Mathematics Sichuan Normal University Chengdu 610066 P R China Department of Mathematics Sichuan Normal University Chengdu 610066 P R China

The new notions of H-metric spaces and generalized H-KKM mappings were introduced. Some generalized H-KKM type theorems for generalized H-K-KM mappings with finitely metrically compactly closed values and finitely metrically compactly open values were established in H-metric spaces. These theorems generalize recent results of Khamsi and Yuan. As applications, some Ky Fan type matching theorems for finitely metrically compactly open covers and finitely metrically compactly closed covers, fixed point theorems and minimax inequality are obtained in H-metric spaces. These results generalize a number of known results in recent literature.

关键词： hyperconvex space H-metric space finitely metrically compactly closed (open) set generalized H-KKM mapping admissible set

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Synthesis and Crystal Structure of a Novel Complex [Ag(NIT3Py)_3]·(ClO_4)(H_2O)

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Chinese Journal of Structural Chemistry 2005年第6期24卷 625-628页

作者： ZhanGChen-xia LIAODai-Zheng JIANGZong-Hui YANShi-ping SchoolofMaterialsScienceandEngineering TianjinUniversityTianjin300072China／／DepartmentofChemistryNankaiUniversityTianjin300071China DepartmentofChemistry NankaiUniversityTianjin300071China DepartmentofChemistry NankaiUniversityTianjin300071China／／StateKeyLaboratoryofCoordinationChemistryNanjing210093China

A novel complex [Ag(NIT3Py)3]?(ClO4)(H2O) has been synthesized and structurally characterized by X-ray diffraction method. It crystallizes in the rhombohedral system, space group R 3 with a = 15.8227(17), b = 15.8227(17), c = 31.445(3) ?, γ = 120°, V = 6817.8(12) ?3, Dc = 1.370 g/cm3, Z = 6, μ = 0.566 mm-1, Mr = 937.18, F(000) = 2916, R = 0.0715, wR = 0.2115 and GOF = 1.086. The structure consists of Ag(NIT3Py)3+ cation moiety, one water molecule and one perchloric ion. The Ag(I) ion is in a trigonal planar coordination environment formed by three nitrogen atoms from three NIT3Py ligand molecules.

关键词： crystal structure nitronyl nitroxide radical Ag(I) complex magnetism ferromagnetic interactions

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Arbitrary-oriented target detection in large scene sar images

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Defence Technology（防务技术） 2020年第4期16卷 933-946页

作者： Zi-shuo han Chun-ping Wang Qiang Fu Shijiazhuang Campus Army Engineering UniversityShijiazhuang050003China

Target detection in the field of synthetic aperture radar(SAR) has attracted considerable attention of researchers in national defense technology worldwide,owing to its unique advantages like high resolution and large scene image acquisition capabilities of ***,due to strong speckle noise and low signal-to-noise ratio,it is difficult to extract representative features of target from SAR images,which greatly inhibits the effectiveness of traditional *** order to address the above problems,a framework called contextual rotation region-based convolutional neural network(RCNN) with multilayer fusion is proposed in this ***,aimed to enable RCNN to perform target detection in large scene SAR images efficiently,maximum sliding strategy is applied to crop the large scene image into a series of sub-images before *** of using the highest-layer output for proposal generation and target detection,fusion feature maps with high resolution and rich semantic information are constructed by multilayer fusion ***,we put forwards rotation anchors to predict the minimum circumscribed rectangle of targets to reduce redundant detection ***,shadow areas serve as contextual features to provide extraneous information for the detector identify and locate targets *** results on the simulated large scene SAR image dataset show that the proposed method achieves a satisfactory performance in large scene SAR target detection.

关键词： Target detection Convolutional neural network Multilayer fusion Context information Synthetic aperture radar

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Characteristics of Endogenous Hormone Variations in the Roots of Alfalfa (Medicago sativa L.) Cultivars of Different Fall Dormancies During Spring Regrowth Stage

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Agricultural Sciences in China 2011年第7期10卷 1032-1040页

作者： han Qing-fang MENG Hai-tao JIA Zhi-kuan XU Ling-fei WU Feng-ping DING Rui-xia Chinese Research Institute of Water-Saving Agriculture in Arid Areas Northwest A＆F University/Key Laboratory of Crop Production and Ecology Minister of Agriculture Yangling 712100 P.R.China Colloge of Horticulture Northwest A＆F University Yangling 712100 P.R.China Center of Enviroment Detection in Tianjin Tianjin 300191 P.R.China

Regrowth traits of alfalfa （Medicago sativa L.） in spring are closely related to its fall dormancy before winter. In order to determine the relationship between fall dormancy （FD） grade and hormone variation pattern and provide academic references for the variety improvement and production of alfalfa, the variations of gibberellins （GA3）, indole-3-acetic acid （IAA）, and abscisic acid （ABA） in alfalfa roots during regrowth period in spring were examined by high performance liquid chromatography （HPLC）. The study involved seven alfalfa cultivars that belonged to four fall dormant grades, i.e., 2, 4, 6, and 8. The results showed that the differences in spring regrowth among the alfalfa cultivars were partially associated with their root hormone levels. The alfalfa cultivars that belonged to the same dormancy grades presented similar variation trends in endogenous hormone content in their roots during the spring regrowth stage. At the early regrowth stage, cultivars with a higher dormant grade had a higher GA3 concent and a lower ABA content in their roots than the cultivars with a lower dormant grade; and IAA content in roots of non- and semi-fall dormancy cultivars was higher than that of fall dormancy cultivars. During the whole period of spring regrowth, the root ABA content of fall dormancy alfalfa cultivar is significantly higher than those of semi- and non-fall dormancy cultivars. GA3 contents in the roots of all cultivars under study showed a double-peak dynamic curve; root IAA contents of the studied cultivars presented a downward trend. But the trend did not significantly differed among the different fall dormant cultivars. The higher GA3 content and lower ABA content in root of non-fall dormancy alfalfa lead to its earlier regrowth. Regrowth time and rate of alfalfa can be regulated by exogenous GA3 or ABA at the early regrowth stage to meet producing requirement.

关键词： alfalfa root endogenous hormone fall dormancy grade regrowth

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Multi-physics multi-scale simulation of unique equiaxed-to-columnar-to-equiaxed transition during the whole solidification process of Al-Li alloy laser welding

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Journal of Materials Science & Technology 2024年第4期171卷 235-251页

作者： Chu han ping Jiang Shaoning Geng Liangyuan Ren School of Mechanical Science and Engineering Huazhong University of Science&Technology(HUST)Wuhan430074China

In this study,a novel multi-physics multi-scale model with the dilute multicomponent phase-field method in three-dimensional(3D)space was developed to investigate the complex microstructure evolu-tion in the molten pool during laser welding of Al-Li *** accurately compute mass data within both two and three-dimensional computational domains,three efficient computing methods,including central processing unit parallel computing,adaptive mesh refinement,and moving-frame algorithm,were *** was placed on the distinctive equiaxed-to-columnar-to-equiaxed transition phenomenon that occurs during the entire solidification process of Al-Li alloy laser *** results indi-cated that the growth distance of columnar grains that epitaxially grew from the base metal(BM)de-creased as the nucleation rate *** the nucleation rate increased,the morphology of the newly formed grains near the fusion boundary(FB)changed from columnar to equiaxed,and newly formed equiaxed grains changed from having high-order dendrites to no obvious dendrite *** the nucleation rate was sufficiently high,non-dendritic equiaxed grains could directly form near the FB,and there was nearly no epitaxial growth from the ***,simulation results illustrated the com-petition among multiple grains with varying orientations that grow in 3D space near the ***,how equiaxed grain bands develop was *** equiaxed band not only hindered the growth of early columnar grains but also some of its grains could grow epitaxially to form new columnar *** predicted results were in good agreement with experimental measurements and observations.

关键词： Laser welding Al-Li alloy Equiaxed-to-columnar-to-equiaxed transition Multi-physics multi-scale model Multicomponent alloys 3D phase-field model

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Calculation Model and Allocation Strategy of Network Usage Charge for Peer-to-peer and Community-based Energy Transaction Market

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Journal of Modern Power Systems and Clean Energy 2023年第1期11卷 144-155页

作者： Dong han Lei Wu Xijun Ren Shiwei xia Electrical Engineering Department University of Shanghai for Science and TechnologyShanghai 200093China State Grid Anhui Electric Power Economic Research Institute Hefei 230022China Electrical Engineering Department North China Electric Power UniversityBeijing 102206China

The emergence of prosumers in distribution systems has enabled competitive electricity markets to transition from traditional hierarchical structures to more decentralized models such as peer-to-peer(P2P)and community-based(CB)energy transaction ***,the network usage charge(NUC)that prosumers pay to the electric power utility for network services is not adjusted to suit these energy transactions,which causes a reduction in revenue streams of the *** this study,we propose an NUC calculation method for P2P and CB transactions to address holistically economic and technical issues in transactive energy markets and distribution system operations,*** on the Nash bargaining(NB)theory,we formulate an NB problem for P2P and CB transactions to solve the conflicts of interest among prosumers,where the problem is further decomposed into two convex subproblems of social welfare maximization and payment *** then build the NUC calculation model by coupling the NB model and AC optimal power flow *** also employ the Shapley value to allocate the NUC to consumers fairly for the NUC model of CB ***,numerical studies on IEEE 15-bus and 123-bus distribution systems demonstrate the effectiveness of the proposed NUC calculation method for P2P and CB transactions.

关键词： Electricity market network usage charge distribution locational marginal prices Shapley value Nash bargaining transactive energy peer-to-peer transaction community-based transaction

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Synergetic effect of polydopamine particles and in-situ fabricated gold nanoparticles on charge-dependent catalytic behaviors

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Particuology 2019年第3期17卷 63-70页

作者： xia han xiaolu Chen Mengfei Yan Honglai Liu Key Laboratory for Advanced Materials and School of Chemistry & Molecular Engineering East China University of Science and Technology Shanghai 200237 China

The versatile catechol unit of polydopamine (PDA) endows this molecule with a broad ranging adhesive properties and *** prepared free-standing PDA particles by a simple self-polymerization and these particles served as both an effective reductant and scaffold for a hybrid *** raspberrylike nanocomposites featured a high density of AuNPs uniformly deposited on PDA particles (PDA@Au).This system was prepared in-situ with assistance from the active catechol and amine groups of the PDA *** quantify the effect of the PDA carriers,we studied the catalytic activity of the PDA and PDA@Au *** PDA particles showed a pronounced charge-dependent catalytic activity for reduction of cationic methylene blue,negatively-charged 4-nitrophenolate,and zwitterionic rhodamine B in the presence of borohydride,whereas PDA@AuNPs showed catalytic activity with a less pronounced charge-dependence of the catalytic efficiency of the *** PDA particles served as a redox mediator and adsorbent accelerator in degradation of the dyes owing to its unique chemical structure.

关键词： Poiydopamine Gold nanoparticle Hybrid catalyst Adsorbent Redox mediator

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Robust Platoon Control of Mixed Autonomous and Human-Driven Vehicles for Obstacle Collision Avoidance:A Cooperative Sensing-Based Adaptive Model Predictive Control Approach

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Engineering 2024年第11期42卷 244-266页

作者： Daxin Tian Jianshan Zhou Xu han ping Lang State Key Laboratory of Intelligent Transportation Systems Beihang UniversityBeijing 100191China Beijing Key Laboratory for Cooperative Vehicle Infrastructure Systems&Safety Control Beihang UniversityBeijing 100191China School of Transportation Science and Engineering Beihang UniversityBeijing 100191China Zhongguancun Laboratory Beijing 100094China

Obstacle detection and platoon control for mixed traffic flows,comprising human-driven vehicles(HDVs)and connected and autonomous vehicles(CAVs),face challenges from uncertain disturbances,such as sensor faults,inaccurate driver operations,and mismatched model ***,misleading sensing information or malicious attacks in vehicular wireless networks can jeopardize CAVs’perception and platoon *** this paper,we develop a two-dimensional robust control method for a mixed platoon,including a single leading CAV and multiple following HDVs that incorpo-rate robust information sensing and platoon *** effectively detect and locate unknown obstacles ahead of the leading CAV,we propose a cooperative vehicle-infrastructure sensing scheme and integrate it with an adaptive model predictive control scheme for the leading *** sensing scheme fuses information from multiple nodes while suppressing malicious data from attackers to enhance robustness and attack resilience in a distributed and adaptive ***,we propose a distributed car-following control scheme with robustness to guarantee the following HDVs,considering uncertain *** also provide theoretical proof of the string stability under this control ***,extensive simulations are conducted to validate our *** simulation results demonstrate that our method can effectively filter out misleading sensing information from malicious attackers,significantly reduce the mean-square deviation in obstacle sensing,and approach the theoretical error lower ***,the proposed control method successfully achieves obstacle avoidance for the mixed platoon while ensuring stability and robustness in the face of external attacks and uncertain disturbances.

关键词： Connected autonomous vehicle Mixed vehicle platoon Obstacle collision avoidance Cooperative sensing Adaptive model predictive control

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Numerical research on effect of overlap ratio on thermal-stress behaviors of the high-speed laser cladding coating

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Chinese Physics B 2021年第1期30卷 555-567页

作者： xiaoxi Qiao Tongling xia ping Chen School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China

High-speed laser cladding technology, a kind of surface technology to improve the wear-resistance and corrosion-resistance of mechanical parts, has the characterizations of fast scan speed, high powder utilization rate, and high cladding efficiency. However, its thermal-stress evolution process is very complex, which has a great influence on the residual stress and deformation. In the paper, the numerical models for the high-speed laser cladding coatings with overlap ratios of 10%,30%, and 50% are developed to investigate the influence rules of overlap ratio on the thermal-stress evolution, as well as the residual stresses and deformations. Results show that the heat accumulation can reheat and preheat the adjacent track coating and substrate, resulting in stress release of the previous track coating and decreased longitudinal stress peak of the next track coating. With the overlap ratio increasing, the heat accumulation and the corresponding maximum residual stress position tend to locate in the center of the cladding coating, where the coating has a high crack susceptibility. For a small overlap ratio of 10%, there are abrupt stress changes from tensile stress to compressive stress at the lap joint, due to insufficient input energy in the position. Increasing the overlap ratio can alleviate the abrupt stress change and reduce the residual deformation but increase the average residual stress and enlarge the hardening depth. This study reveals the mechanism of thermal-stress evolution, and provides a theoretical basis for improving the coating quality.

关键词： high-speed laser cladding overlap ratio thermal-stress evolution residual stress and deformation numerical simulation

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