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Mechanical and tribological properties of graphene nanoplatelets-reinforced titanium composites fabricated by powder metallurgy

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Journal of Iron and Steel Research International 2020年第11期27卷 1357-1362页

作者： Zhen Cao Jiong-li li Hai-ping Zhang wen-bo li Xu-dong Wang AECC Beijing Institute of Aeronautical Materials Beijing 100095China Beijing Institute of Graphene Technology Beijing 100094China Beijing Engineering Research Centre of Graphene Application Beijing 100095China

Titanium matrix composite reinforced by graphene nanoplatelets(GNPs)was fabricated via powder metallurgy *** isostatic pressing and hot extrusion were used to consolidate the mixed powder of GNPs and TC4 titanium(Ti)*** microstructures,mechanical properties and sliding wear performance of Ti/GNPs composite had been researched to evaluate the rein forcing effect of GNPs on tita nium *** observation indicates that GNPs could restrain grai n growth slightly in titanium *** matrix and graphene exhibit a clean and firm interface formed by means of metallurgical bonding on atomic *** with the monolithic titanium alloy,the composite with 1.2 vol.%GNPs exhibits significantly improved elastic modulus and *** sliding wear test shows that there is an obvious enhancement in the tribological performance of Ti/GNPs composite with 1.2 vol.%*** results of this work indicate that GNP is an efficient reinforcenient material in titanium *** strengthening mechanism including precipitates strengthening,load transfer and grain refinement mechanism of GNPs in titanium matrix was discussed.A modified shear-lag model was used to analyze the reinforcement contribution of the stress transfer *** calculation shows that the stress load mechanism constitutes the main strengthening mechanism in Ti/GNPs composite.

关键词： Titanium matrix composite Graphene Mechanical testing Tribological property Powder metallurgy

Robust Variable Selection and Estimation in Threshold Regression Model

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Acta Mathematicae Applicatae Sinica 2020年第2期36卷 332-346页

作者： bo-wen li Yun-qi ZHANG Nian-sheng TANG School of Management University of Science and Technology of ChinaHefei 230026China Key Lab of Statistical Modeling and Data Analysis of Yunnan Province Yunnan UniversityKunming 650091China

We combine the robust criterion with the lasso penalty together for the high-dimensional threshold *** estimates regression coefficients as well as the threshold parameter robustly that can be resistant to outliers or heavy-tailed noises and perform variable selection *** illustrate our approach with the absolute loss,the Huber’s loss,and the Tukey’s loss,it can also be extended to any other robust *** studies are conducted to demonstrate the usefulness of our robust ***,we use our estimators to investigate the presence of a shift in the effect of debt on future GDP growth.

关键词： Threshold regression Robust estimation Lasso

Thiazole-Flanked Thiazoloisoindigo as a Monomer for Balanced Ambipolar Polymeric Field-effect Transistors

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Chinese Journal of Polymer Science 2022年第10期40卷 1131-1140,I0006页

作者： Si-Yu Lv Qi-Yi li bo-wen li Jie-Yu Wang You-Bing Mu liang li Jian Pei Xiao-bo Wan Key Laboratory of Optoelectronic Chemical Materials and Devices Ministry of EducationSchool of Optoelectronic Materials&TechnologyJianghan UniversityWuhan 430056China Beijing National Laboratory for Molecular Sciences the Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 10087iChina School of Materials Science and Engineering Wuhan Institute of TechnologyWuhan 430205China

Electron-rich thiophene-flanked thiazoloisoindigo(Th-TzII)has been reported as a building block for ambipolar polymeric field-effect transistors however with preferable hole ***,we report that by using an electron deficient thiazole as the flanked moiety,the corresponding thiazoloisoindigo(Tz-TzII)can still be synthesized,although in a more sinuous *** calculation and experimental results demonstrate that Tz-TzII is more electron-deficient than Th-TzII,and the corresponding polymer P(TzII-Tz-T-Tz)exhibits high and balanced hole/electron mobility of 0.70/0.64 cm^(2)·V^(-1)·s^(-1).

关键词： Thiazoloisoindigo Ambipolar Polymeric field-effect transistors

High-order numerical method for the derivative nonlinear Schrodinger equation

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第1期8卷 258-270页

作者： Shu-Cun li Xiang-Gui li Jun-Jie Cao wen-bo li School of Applied ScienceBeijing Information Science and Technology UniversityBeijing 100192P.R.China

In this work,a fourth-order numerical scheme in space and two second-order numerical schemes in both time and space are proposed for the derivative nonlinear Schrodinger *** verify the mass conservation for the two-level implicit *** influence on the soliton solution by adding a small random perturbation to the initial condition is *** numerical experiments are given to test the accuracy order for different schemes,*** also test the conservative property of mass and Hamiltonian for these schemes from the numerical point of view.

关键词： Derivative nonlinear Schrodinger equation finite difference soliton solution random perturbation

Exploiting Multiple Correlations Among Urban Regions for Crowd Flow Prediction

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Journal of Computer Science & Technology 2020年第2期35卷 338-352页

作者： Qiang Zhou Jing-Jing Gu Chao ling wen-bo li Yi Zhuang Jian Wang College of Computer Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Crowd flow prediction has become a strategically important task in urban computing,which is the prerequisite for traffic management,urban planning and public ***,due to variousness of crowd flows,multiple hidden correlations among urban regions affect the ***,crowd flows are also influenced by the distribution of Points-of-Interests(POIs),transitional functional zones,environmental climate,and different time slots of the dynamic urban ***,we exploit multiple correlations between urban regions by considering the mentioned factors comprehensively rather than the geographical distance and propose multi-graph convolution gated recurrent units(MGCGRU)for capturing these multiple spatial *** adapting to the dynamic mobile data,we leverage multiple spatial correlations and the temporal dependency to build an urban flow prediction framework that uses only a little recent data as the input but can mine rich internal ***,the framework can mitigate the influence of the instability of data distributions in highly dynamic environments for *** experimental results on two real-world datasets in Shanghai show that our model is superior to state-of-the-art methods for crowd flow prediction.

关键词： crowd flow prediction multi-graph convolutional network multiple correlations mining

Thiazoloisoindigo-based Polymer Semiconductors: Synthesis,Structure-Property Relationship, Charge Carrier Polarity, and Field-Effect Transistor Performance

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Chinese Journal of Polymer Science 2024年第1期42卷 24-31,I0006页

作者： bo-wen li Miao Xiong Mei-Hua liu Zhi-Gao li Long Sang Zi-Han Xiong Biao Xiao Jian Pei Xiao-bo Wan Key Laboratory of Optoelectronic Chemical Materials and Devices Ministry of EducationSchoolofOptoelectronic Materials&TechnologyJianghan UniversityWuhan430056China Bejing National Laboratoryfor Molecular Sciences the Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

Developing new polymeric semiconductors with excellent device performance is essential for organic electronics. Herein, we synthesized two new thiazoloisoindigo(Tz II)-based polymers, namely, P(Tz II-d Th-d Th) and P(Tz II-d Th-d Tz), by copolymerizing thiophene-flanked Tz II with bithiophene and bithiazole, respectively. Owing to the more electron-deficient nature of bithiazole than bithiophene, P(Tz II-d Th-d Tz)possesses deeper LUMO/HOMO levels of-3.45/-5.47 e V than P(Tz II-d Th-d Th)(-3.34/-5.32 e V). The organic field-effect transistor(OFET) devices based on P(Tz II-d Th-d Th) exhibited p-type behaviors with an average hole mobility value as high as 1.43 cm^(2)·V^(-1)·s^(-1), while P(Tz II-d Th-d Tz)showed typical ambipolar characteristics with average hole and electron mobilities of 0.38 and 0.56 cm^(2)·V^(-1)·s^(-1). In addition, we compared the performances of both polymers with other Tz II-based polymers reported in our previous work, and showed that the charge carrier polarity can be manipulated by adjusting the number of the thiophene units between the acceptor unit. As the increase of the number of thiophene rings,charge carrier polarity shifts from electron-dominated ambipolar transport to hole-dominated ambipolar transport and then to unipolar hole transport in OFETs, which provides an effective molecular design strategy for further optimization of polymer OFET performance.

关键词： Field-effect transistor Charge carrier polarity Thiazoloisoindigo

Aggregation-induced phosphorescence and mechanochromic luminescence of a tetraphenylethene-based gold(Ⅰ) isocyanide complex

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Chinese Chemical Letters 2017年第6期28卷 1300-1305页

作者： wen-bo li Wei-Jian Luo Kai-Xuan li Wang-Zhang Yuan Yong-Ming Zhang Shanghai Key Lab of Electrical Insulation and Thermal Aging Shanghai Electrochemical Energy Devices Research Center School of Chemistry and Chemical Engineering Shanghai Jiao Tong University Shanghai 200240 China

In this study,a new twisting gold（Ⅰ） isocyanide complex based on tetraphenylethene（TPE）,*** designed and *** exhibits aggregation induced phosphorescence（AIP） characteristics,owing to the incorporation of Au moiety and conformation rigidification in the aggregated ***,the emission color of the crystalline solid of TPE-NC-Au changes from blue（454 nm） to green（500 nm） in response to mechanical grinding,due to the combined effects of conformation planarization,enhanced π…π stacking,as well as the emergence of aurophilic interactions in the ground amorphous ***,the emission color can be restored upon solvent fuming,associating with the reconstruction of crystalline *** AIP and switchable mechanochromism of TPE-NC-Au make it suitable for potential applications in bioimaging,sensing,and optoelectronic devices.

关键词： Aggregation-induced phosphorescence Mechanochromism Aurophilic interaction Gold(Ⅰ) isocyanide complex

Hot Corrosion Behavior of SiO_2–Al_2O_3–Glass Composite Coating on Ti–47Al–2Cr–2Nb Alloy: Diffusion Barrier for S and Cl

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Acta Metallurgica Sinica(English Letters) 2019年第5期32卷 599-606页

作者： wen-bo li Lan-Lan liu Ying-Fei Yang Sheng-Long Zhu Fu-Hui Wang Hunan Electric Power Co. Ltd. Institute of Advanced Wear and Corrosion Resistant and Functional Material Jinan University Laboratory of Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences

Type Ⅰ hot corrosion behavior of SiO_2-Al_2O_3-glass composite coating based on Ti-47 Al-2 Cr-2 Nb substrate was investigated in the mixture salt of 25 wt%NaCl + 75 wt%Na_2SO_4 at 850 °C. The results showed that there was a bidirectional ion exchange between composite coating and the film of mixed salts, and the sodium ion in the molten salts penetrated into the glass matrix of composite coating, while the potassium ion in the glass matrix dissolved into the molten salts. A decrease in hot corrosion rate was achieved for the coated alloy in comparison with the bared substrate due to the composite coating acting as a diffusion barrier to sulfur and chlorine and preventing the molten salts from diffusing to the coating/alloy interface during the hot corrosion exposure. Additionally, the composite coating decreased the oxygen partial pressure at the coating/alloy interface and promoted the selective oxidation of Al to form a protective Al_2O_3 layer.

关键词： Corrosion Composite coating Ti–47Al–2Cr–2Nb alloy Diffusion

Interfacial Improvement of Carbon Fiber/Epoxy Composites by Incorporating Superior and Versatile Multiscale Gradient Modulus Intermediate Layer with Rigid-flexible Hierarchical Structure

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Chinese Journal of Polymer Science 2021年第7期39卷 896-905页

作者： Pei-Feng Feng Guo-Jun Song wen-Jian Zhang Hao Zheng bo-wen li Shao-Feng Zhou Ya-Qing liu Guang-Shun Wu li-Chun Ma Institute of Polymer Materials School of Material Science and EngineeringQingdao UniversityQingdao 266071China Shanxi Province Key Laboratory of Functional Nanocomposites North University of ChinaTaiyuan 030000China School of Chemistry and Materials Science Ludong UniversityYantai264025China

In order to enhance the interfacial adhesion of carbon fiber(CF)and polymer matrix,a multiscale gradient modulus intermediate layer with rigid-flexible(GO-PA)hierarchical structure was designed and fabricated between CFs and matrix by a facile and businesslike *** polarity,roughness and wettability of CFs surface as well as the thickness of intermediate layer in composite have been significantly increased after rigid-flexible hierarchical structure was *** IFSS,ILSS,compression and impact toughness manifested that the hierarchical structure could bring about a fantastic improvement(76.8%,46.4%,40.7%and 37.8%)for the interfacial and mechanical properties than other previous ***,the establishment of CF surface with gradient modulus rigid-flexible hierarchical structure via regulation of nanoparticles and polymer array would open a new,viable and promising route to obtaining high-performance composites.

关键词： Carbon fibers Polymer-matrix composites Interface Hierarchical structure Gradient modulus