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Microstructural characterization of titanium matrix composite coatings reinforced by in situ synthesized TiB + TiC fabricated on Ti6Al4V by laser cladding

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Rare Metals 2010年第5期29卷 465-472页

作者： li jun yu Zhishui WANG Huiping li Manping 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 between titanium and B4C were successfully fabricated on Ti6Al4V by laser cladding. Phase constituents of the coatings were predicted by thermodynamic calculations in the Ti-BnC-Al and Ti-B-C-Al systems, respectively, and were validated well by X-ray diffraction （XRD） analysis results. Microstructural and metallographic analyses were made by scanning electron microscopy （SEM） and electron probe micro-analysis （EPMA）. The results show that the coatings are mainly composed of α-Ti cellular dendrites and the eutecticum in which a large number of needle-shaped TiB and a few equiaxial TiC particles are embedded. C is enriched in α-Ti cellular dendrites and far exceeds the theoretical maximum dissolubility, owing to the extension of saturation during laser cladding. The coatings have a good metallurgical bond with the substrate due to the existence of the dilution zone, in which a great amount of lamella β-Ti grains consisting of a thin needle-shaped martensitic microstructure are present and grow parallel to the heat flux direction; a few TiB and TiC reinforcements are observed at the boundaries of initial β-Ti grains.

关键词： composite coatings laser cladding in situ synthesis microstructure thermodynamic calculation

A Spectrometric Setup for Synchronous Total Internal Reflection Fluorescence Measurement at the Solid/liquid Interface

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Chinese Chemical Letters 2002年第6期13卷 571-572页

作者： Yao Qun li Jia Ju XU Run Tang WANG li jun yu Zhao li Department of Chemistry and the Key Laboratory of Analytical Sciences of MOE Xiamen UniversityXiamen 361005

A spectrometric setup to perform total internal reflection fluorescence (TIRF) and synchronous TIRF measurements at solid/liquid interfaces is presented. The combination of TIRF and synchronous fluorescence was proposed to analyze simultaneously different components at interfaces. The TIRF excitation, emission and synchronous spectra of a watersoluble porphyrin were obtained from water/glass interface using this setup without the existence of a surfactant.

关键词： Total internal reflection fluorescence synchronous fluorescence spectrofluorimeter meso-tetra(4-sulfonatophenyl)porphyrin.

The optimal time-frequency atom search based on a modified ant colony algorithm

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Optoelectronics Letters 2008年第3期4卷 227-230页

作者： GUO jun-feng li Yan-jun yu Rui-xing ZHANG Ke College of Astronautics Northwestern Polytechnical University Xi＇ an 710072China

this paper, a new optimal time-frequency atom search method based on a modified ant colony algorithm is proposed to improve the precision of the traditional methods. First, the discretization formula of finite length time-frequency atom is inferred at length. Second; a modified ant colony algorithm in continuous space is proposed. Finally, the optimal time- frequency atom search algorithm based on the modified ant colony algorithm is described in detail and the simulation experiment is carried on. The result indicates that the developed algorithm is valid and stable, and the precision of the method is higher than that of the traditional method.

关键词：最优化频率原子计算方法

Accuracy analysis in CH4MODwetland in the simulation of CH4 emissions from Chinese wetlands

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Advances in Climate Change Research 2020年第1期11卷 52-59页

作者： ZHANG Qing li Ting-Ting ZHANG Qiang WANG Guo-Cheng yu li-jun GUO Bin HAN Peng-Fei LAPC Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai519000China Beijing Climate Center China Meteorological AdministrationBeijing100081China Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan ProvinceChengdu610072China Aba Prefecture Meteorological Station Maerkang624000China LASG Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China

Process-based models have been widely used to simulate the CH4 budget in natural wetlands,but there are still large uncenainties in ihe simulation *** analysis of process-based models is important to evaluate the reliability of model estimates for different *** this study,we analyzed the three sources of the model bias from a process-based model(CH4MODwetland)when simulating CH4 emissions from different wetland sites and types in *** a national scale,the root-mean-square error(RMSE)decreased from 70.6% at daily scale to 27.1% at annual/seasonal *** a national scale,more than 90% of the model errors were from random *** most of the sites random error contributed more than 60% to the model errors,except the Guangzhou,Haikou,Wuliangsu lake and Yancheng Estuary sites,which showed lower RMSE *** model simulated higher RMSE at the tidal marsh *** model had capability to simulate the daily and annual/seasonal CH4 emissions from all wetland types(model efficiency>0),and performed better for coastal wetlands than peatlands and marshes,with model efficiency values of 0.75 and 0.99,*** applied the model at annual/seasonal scale for peatlands,marshes,and coastal wetlands,the RMSE decreased a *** study indicated that CH4MODwetland is more accurate at annual/seasonal scale than daily scale for different wetland types across *** non-stochastic portion of CH4 emissions from peatlands,marshes and coastal wetlands can be well predicted by the model.

关键词： CH4MODwetland CH4 China Wetland Accuracy analysis Simulation

Mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions

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Journal of Central South University 2015年第3期22卷 1096-1103页

作者：熊良宵虞利军 Faculty of Architectural Civil Engineering and Environment Ningbo University State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Zhejiang Geotechnical and Foundation Company

To investigate the mechanical properties of cement mortar in sodium sulfate and sodium chloride solutions, uniaxial compression test and ultrasonic test were performed. Test results show that the relative dynamic elastic modulus, the mass variation,and the compressive strength of cement mortar increase first, and then decrease with increasing erosion time in sodium sulfate and sodium chloride solutions. The relative dynamic elastic moduli and the compressive strengths of cement mortars with water/cement ratios of 0.55 and 0.65 in sodium sulfate solution are lower than those in sodium chloride solution with the same concentration at the420 th day of immersion. The compressive strength of cement mortar with water/cement ratio of 0.65 is more sensitive to strain rate than that with water/cement ratio of 0.55. In addition, the strain-rate sensitivity of compressive strength of cement mortar will increase under attacks of sodium sulfate or sodium chloride solution.

关键词： cement mortar mechanical properties relative dynamic elastic modulus compressive strength

Research on the influence of action between fin and anti-rolling tank on the integrated stabilization effect

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Journal of Marine Science and Application 2007年第1期6卷 9-14页

作者： yu li-jun JIN Hong-zhang WANG Hui YANG Sheng College of Automation Harbin Engineering University Harbin 150001 China

Through analyzing the roll model of the integrated system of fin and anti-rolling tank, this paper uses binomial equation to simplify the module and check how the approximate parameters simulate the original function. Based on the simplified module, the influence of fin and anti-rolling tank on the coefficient items of the roll module is discussed, and the influencing factors between fin and anti-rolling tank are analysed. And through simulation, the influence of action between fin and anti-rolling tank on the static characteristics, and the integrated stabilization effect, are analyzed.

关键词： fin stabilizer anti-rolling tank integrated stabilization action each other influence

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连续交通网络设计的全局双层多项式优化模型

交通运输工程学报 2022年第2期22卷 259-267页

作者：俞礼军陈睿华南理工大学土木与交通学院广东广州510641

提出了一种面向典型连续交通网络设计问题的全局双层多项式优化模型,其函数均为多项式,且下层问题为凸问题;上层问题旨在优化网络性能,下层问题用来刻画确定性用户均衡(DUE)交通流模式;利用Fritz John条件和乘子代替下层规划,将提出的... 详细信息

提出了一种面向典型连续交通网络设计问题的全局双层多项式优化模型,其函数均为多项式,且下层问题为凸问题;上层问题旨在优化网络性能,下层问题用来刻画确定性用户均衡(DUE)交通流模式;利用Fritz John条件和乘子代替下层规划,将提出的双层多项式优化模型转换为等价单层优化问题,并利用矩半定规划(MSDP)方法得到其全局最优解;利用矩矩阵的秩作为保证全局最优性的充分条件,并估计全局最优解的个数;给出了最优道路收费问题的数值算例,用提出的双层多项式优化模型描述了算例中的最优道路收费问题,并通过Wardrop用户均衡约束调整现有路段上的交通流量,使总通行费收益最大化。研究结果表明:该简单算例的最大收益为13.5元,同时可以得到该算例的矩矩阵的秩为1,从而证明了该结果的全局最优性,提出的方法克服了均衡约束数学规划(MPEC)法和值函数法等现有求解双层优化问题的经典算法由于连续交通网络设计固有的非凸性,只能找到局部最优的问题;提出的全局双层多项式优化模型与算法为典型连续交通网络设计提供了更好的探索工具。

关键词：交通均衡网络设计双层多项式优化矩理论层次半定规划全局最优解

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Modeling of CHAMP satellite data according to the 3D surface spline model of geomagnetic fi elds

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Applied Geophysics 2020年第4期17卷 616-623页

作者： Yan Feng Huang Ya liu Shuang li yu-jun Jiang Yi The College of Mathematics and Statistics Nanjing University of Information Science&TechnologyNanjing 210044China State Key Laboratory of Lunar and Planetary Sciences(Macao University of Science and Technology) Macao 999078China State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China

Surface observations and CHAMP measurement data are employed to develop a three-dimensional surface spline(3DSS)model of China's *** magnetic field distribution at the satellite level is then demonstrated using the model *** results of this model are compared and verifi ed by deriving the corresponding two(2DTY)and threedimensional(3DTY)Taylor polynomial *** such as the removal of disruptive geomagnetic fi elds,the data gap between the surface and satellite levels,and boundary eff ects are carefully considered during *** then focus on evaluating the modeling eff ect of the satellite *** satellite points not involved in the modeling procedure are selected,and the residuals,absolute change rates,and RMSEs of these points are *** show that the distribution of the magnetic fi eld determined by the 3DSS model is highly consistent with that obtained from the IGRF12 *** for component Y,the absolute change rates of other components are less than 0.5%.Specifi cally,the RMSE of Y of 3DSS is nearly 60%lower than those of 3DTY and 2DTY;the RMSE of other components of the former are also over 90%lower than those of the *** fi nding implies that the 3DSS model has good performance for modeling satellite data and its results are ***,the modeling eff ect of 3DTY is better than that of 2DTY.

关键词： geomagnetic field three-dimensional model surface Spline Chinese Meridian Project CHAMP satellite

考虑风险爱好驾驶人的相依Weibull随机交通分配模型

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交通运输工程学报 2017年第6期17卷 76-85页

作者：俞礼军谈进舟华南理工大学土木与交通学院广东广州510641

建立了考虑风险爱好驾驶人的相依Weibull随机交通分配(Weibull-DSA)模型,分析了感知等价路径负效用的Weibull边缘生存函数,假设驾驶人总是选择感知等价路径负效用最小的路径到达目的地,采用Copula方法构建了感知等价路径负效用的联合生... 详细信息

建立了考虑风险爱好驾驶人的相依Weibull随机交通分配(Weibull-DSA)模型,分析了感知等价路径负效用的Weibull边缘生存函数,假设驾驶人总是选择感知等价路径负效用最小的路径到达目的地,采用Copula方法构建了感知等价路径负效用的联合生存函数,预测了路径选择概率;设计了模型的迭代求解算法,对模型进行了理论分析和数值验证;研究了广州市交通调查获得的风险系数,基于风险爱好和风险中立驾驶人,比较了采用Weibull-DSA模型与经典的Logit-SUE和Weibit-SUE模型计算的路径选择概率、路段交通量、饱和度与系统总出行时间。计算结果表明:随着风险系数的降低,3种分配模型的交通系统总出行时间变大;在风险中立情况下,应用Weibull-DSA模型、Logit-SUE模型和Weibit-SUE模型计算得到每OD对的所有连接路径选择概率的最大差值,分别为0.17、0.33、0.34,在风险爱好情况下,由3种模型得到的最大差值分别为0.20、0.36、0.41,因此,采用Weibull-DSA模型计算得到的不同路径选择概率的最大差值明显小于经典模型计算得到的最大差值;相对于风险中立情况,风险系数使得每OD对的所有连接路径选择概率的最大差值变大;无论是风险爱好还是风险中立驾驶人,采用Logit-SUE和Weibit-SUE模型计算得到的路段饱和度均小于0.9,采用Weibull-DSA模型计算得到路段饱和度大于0.9;与经典模型计算结果不同,采用Weibull-DSA模型得到的不同路径选择概率的最大差值相差较小,一些路径获得更多交通量,使得路径中通行能力最小的路段的饱和度大于0.9,这一特征给出了城市路网中部分瓶颈路段拥堵现象一个新的解释。

关键词：交通工程相依Weibull随机交通分配随机用户均衡路径选择 Copula函数风险爱好等价路径负效用