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Journal of Advanced Ceramics 2021年第3期10卷 551-564页

作者： Dongxu LI Peng JIANG Renheng gao Fan SUN Xiaochao JIN Xueling FAN State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China AEEC Sichuan Gas Turbine Establishment Chengdu 610500China

Calcium-magnesium-alumino-silicate(CMAS)corrosion is a critical factor which causes the failure of thermal barrier coating(TBC).CMAS attack significantly alters the temperature and stress fields in TBC,resulting in their delamination or *** this work,the evolution process of TBC prepared by suspension plasma spraying(SPS)under CMAS attack is *** CMAS corrosion leads to the formation of the reaction layer and subsequent bending of *** on the observations,a corrosion model is proposed to describe the generation and evolution of the reaction layer and bending of ***,numerical simulations are performed to investigate the corrosion process of free-standing TBC and the complete TBC system under CMAS *** corrosion model constructs a bridge for connecting two numerical *** results show that the CMAS corrosion has a significant influence on the stress field,such as the peak stress,whereas it has little influence on the steady-state temperature *** peak of stress increases with holding time,which increases the risk of the rupture of *** Mises stress increases nonlinearly along the thick direction of the reaction ***,in the traditional failure zone,such as the interface of the top coat and bond coat,the stress obviously changes during CMAS corrosion.

关键词： thermal barrier coating(TBC) calcium-magnesium-alumino-silicate(CMAS)corrosion corrosion model temperature field stress field

Analysis of local microstructure and strengthening mechanisms in adjustable-gap bobbin tool friction stir welds of Al-Mg

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International Journal of Minerals,Metallurgy and Materials 2022年第8期29卷 1589-1595页

作者： Dong Wu Wenya Li Qiang Chu Yangfan Zou Xichang Liu Yanjun gao State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi’an 710072China Capital Aerospace Machinery Company Beijing 100076China

The bobbin tool friction stir welding process was used to join 6 mm thick 5A06 aluminum alloy *** microscope was used to characterize the *** electron backscatter diffraction(EBSD)identified the effect of non-homogeneous microstructure on the tensile *** was observed that the grain size in the top of the stir zone(SZ)is smaller than that in the centre *** lowest ratio of recrystallization and density of the geometrically-necessary dislocations(GNDs)in the SZ was found in the middle near the thermo-mechanically affected zone(TMAZ)being 22%and 1.15×10^(−13) m^(−2),*** texture strength of the heat-affected zone(HAZ)is the largest,followed by that in the SZ,with the lowest being in the *** were additional interfaces developed which contributed to the strengthening mechanism,and their effect on tensile strength was *** tensile tests identified the weakest part in the joint at the interfaces,and the specific reduction value is about 93 MPa.

关键词： friction stir welding bobbin-tool local microstructure strengthening mechanisms adjustable-gap

Effect of Interlayers on Microstructure and Properties of 2205/Q235B Duplex Stainless Steel Clad Plate

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Acta Metallurgica Sinica(English Letters) 2020年第5期33卷 679-692页

作者： Fengqiang Xiao Dongpo Wang Wenbin Hu Lei Cui Zhiming gao Lanju Zhou School of Materials Science and Engineering Tianjin UniversityTianjin 300350China Tianjin Key Laboratory of Advanced Joining Technology Tianjin UniversityTianjin 300350China Shandong High-tech Investment Corporation Jinan 250101China Shandong Iron&Steel Group Co. LTDJinan 250101China

In this research,2205/Q235 B clad plates were prepared by a vacuum hot rolling composite *** effects of adding Fe,Ni,and Nb interlayers on the bonding interface structures and the shear strengths of the clad steel plates were *** results showed that 2205 duplex stainless steel and the three interlayers produced a large amount of plastic deformation and low-angle boundaries,and the main structures were the recrystallized and deformed *** were many recrystallized grains in the microstructure of the Q235 B low-carbon steel due to the low deformation in the rolling *** Fe interlayer had better wettability with the two kinds of steel,but the lower strength led to the reduction of shear strength by about14 MPa compared with the original clad steel *** C element in the Q235 B low-carbon steel easily diffused into the Fe interlayer,and the clad steel plate attained a poor corrosion resistance because a large decarburization area was *** Nb interlayer reacted with the Mo element in the 2205 duplex stainless steel to form an Nb-Mo binary alloy,which generated long-banded *** decarburization area was also produced because the Nb reacted with the C element in the Q235 B to form hard and brittle *** a result,the shear strength was significantly reduced by about 282 MPa,and the corrosion resistance of the bonding surface was *** Ni interlayer did not react with the alloy elements in both sides,and therefore effectively prevented element diffusion and improved the corrosion resistance of the bonding *** to the low strength of the Ni interlayer and the increased number of bonding surfaces of the clad steel plates,the shear strength was reduced to some extent(about 40 MPa),but it still met the engineering application standards.

关键词： 2205/Q235B clad steel plate Fe interlayer Ni interlayer Nb interlayer Decarburization area Shear strength

Lithium film with abundant stepped structures: A promising route for homogeneous Li ion deposition to conquer lithium dendrite issue and its action mechanism

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Journal of Energy Chemistry 2022年第9期31卷 166-175,I0006页

作者： Yong Zhang Shu-Qin Song Yong gao Tian-Fu Liu Hong Zhao Department of Materials Science and Engineering Dalian Jiaotong UniversityDalian 116028LiaoningChina The Key Lab of Low-carbon Chemistry&Energy Conservation of Guangdong Province PCFM LabSchool of Materials Science and EngineeringSun Yat-sen UniversityGuangzhou510275GuangdongChina Institute of Science and Technology for New Energy Xi'an Technological UniversityXian 710021ShaanxiChina Dalian Institute of Chemical Physics Chinese Academy of SciencesDalian 116023LiaoningChina

Lithium is considered to be the ‘‘holy grail” for the application of energy storage due to its highest theoretical capacity and lowest anode potential. However, one of the grand difficulties in the development of lithium-based batteries is the lithium dendrite growth that leads to capacity fading and electrode degradation over long-term cycling. Compared with conventional electrolyte modifications, artificial solid electrolyte interfaces(SEI) synthesis and framework designing approaches, tuning surface morphology of lithium anode is the direct route to induce homogeneous Li ion deposition. Due to the high chemical activity of lithium metal, however, controllable growth of lithium micro/nanostructures by traditionally chemical approaches is still a big challenge. Herein, we have developed a facile compression route to fabricate lithium anode with abundant stepped lithium structures. The electrochemical results demonstrate that the dendritic growth issue is effectively suppressed by orderly arranged stepped lithium structures. After 90 cycles, a high discharge capacity of 954 mAh g^(-1) is achieved, which is 2.7times that of the uncompressed lithium anode(342 mAh g). First-principles calculations reveal that the orderly arranged stepped lithium structures are lithiophilic active sites to adsorb Li ion, which contributes to homogeneous deposition of Li ion on lithium anode, eventually solving the lithium dendrite issue. This work paves a new road to suppress dendritic growth, which will provide some new ideas to design long recycling sodium, potassium and zinc, and other metal anode batteries.

关键词： Lithium dendrite Steps/edges Active sites Compression

Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield tunnels

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Frontiers of Structural and Civil Engineering 2023年第6期17卷 901-914页

作者： Xiaojing gao Pengfei LI Mingju ZHANG Haifeng WANG Zenghui LIU Ziqi JIA Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing100124China Nantong Railway Construction Component Co. Ltd.Nantong226000China

The integrity and bearing capacity of segment joints in shield tunnels are associated closely with the mechanical properties of the *** study focuses on the mechanical characteristics and mechanism of a bolted circumferential joint during the entire bearing *** analytical algorithms for four stress stages are established to describe the bearing behaviors of the joint under a compressive bending load.A height adjustment coefficient,α,for the outer concrete compression zone is introduced into a simplified analytical *** affectingαare determined,and the degree of influence of these factors is investigated via orthogonal numerical *** numerical results show thatαcan be specified as approximately 0.2 for most metro shield tunnels in ***,a case study is performed to verify the rationality of the simplified theoretical analysis for the segment joint via numerical simulations and *** the proposed simplified analytical algorithms,a parametric investigation is conducted to discuss the factors affecting the ultimate compressive bending capacity of the *** method for optimizing the joint flexural stiffness is *** results of this study can provide a theoretical basis for optimizing the design and prediciting the damage of bolted segment joints in shield tunnels.

关键词： shield tunnel segment joint joint structural model failure mechanism

Array-level boosting method with spatial extended allocation to improve the accuracy of memristor based computing-in-memory chips

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Science China(Information Sciences) 2021年第6期64卷 80-88页

作者： Wenqiang ZHANG Bin gao Peng YAO Jianshi TANG He QIAN Huaqiang WU Institute of Microelectronics Beijing National Research Center for Information Science and Technology (BNRist)Tsinghua University Institute of Microelectronics Beijing National Research Center for Information Science and Technology (BNRist)Tsinghua University

Memristor based computing-in-memory chips have shown the potentials to accelerate deep neural networks with high energy efficiency. Due to the inherent filament-based conductive mechanism of the memristor, the reading and writing noises are hard to eliminate. Besides, the precision of the large-scale memristor array is still limited. However, when the noise of the memristor is large, the existing training methods to reduce the accuracy loss of memristor based computing-in-memory chips will face ***, we proposed the array-level boosting method with spatial extended allocation to reduce the accuracy loss induced by the limited precision and large noises. To optimize the spatial allocation number of each layer in the neural network, the greedy spatial extended allocation algorithm is also proposed. The image processing and classification tasks are demonstrated based on fabricated 32×128 memristor arrays to valid the performance of the proposed method. The chip-in-loop results show that the recovered accuracy of ResNet-34 on CIFAR-10 with array-level boosting method is 92.3%, which is closed to software-based accuracy of 93.2%.

关键词： memristor computing-in-memory array-level boosting neuromorphic computing RRAM

Systematic assessment of dredged sludge dewaterability improvement with different organic polymers based on analytic hierarchy process

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Journal of Environmental Sciences 2021年第5期33卷 311-321页

作者： Zhenzhen Song Hongyu gao Wanwan Liu Liqing Li Weijun Zhang Dongsheng Wang Faculty of Materials Science and Chemistry China University of GeosciencesWuhan 430074HubeiChina State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Institute for resources and environmental engineering Shanxi UniversityTaiyuan 030006ShanxiChina School of Environmental Studies China University of GeosciencesWuhan 430074HubeiChina

Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch(CS) and poly-dimethyl diallyl ammonium chloride(PDDA) on dredged sludge dewatering efficiency and residual water quality of Baiyangdian lake were comprehensively investigated and evaluated by analytic hierarchy process(AHP). The results indicated that PDDA had stronger electrical effect and flocculation performance compared with CS, resulting in more efficient dewatering performance. PDDA can reduce the pollutants of discharged residual water, while CS significantly promoted the increase of NH_(4)^(+)-N and NO_(3)^(–)-N in the residual water. The increase of NH_(4)^(+)-N in the residual water of CS was due to the release of dredged sludge, while the increase of NO_(3)^(-)-N was introduced by CS leaching. AHP showed that PDDA performed better in flocculation treatment of dredged sludge than other organic polymers. This work provides a method for optimization of flocculation treatment for dredged sludge dewaterability.

关键词： Dredge sludge dewatering Flocculation evaluation model Residual water quality Analytic hierarchy process

The Crystallization and Melting Behaviors of PDLA-b-PBS-b-PDLA Tri-block Copolymers

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Chinese Journal of Polymer Science 2020年第3期38卷 298-310,I0008页

作者： Cong-Shu Feng Yun Chen Jun Shao gao Li Hao-Qing Hou College of chemistry and chemical engineering Jiangxi Normal UniversityNanchang 330022China Jiangxi Key Laboratory of Organic Chemistry Jiangxi Science and Technology Normal UniversityNanchang 330013China Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

In this study,the poly(D-lactide)-block-poly(butylene succinate)-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA)triblock copolymers with a fixed length of PBS and various lengths of PDLA are synthesized,and the crystallization behaviors of the PDLA and PBS blocks are *** both the crystallization behaviors of PBS and PDLA blocks depend on composition,they exhibit different *** the PDLA block,its crystallization behaviors are mainly influenced by temperature and block *** crystallization signals of PDLA block appear in the B-D 2-2 specimen,and these signals get enhanced with PDLA block *** crystallization rates tend to decrease with increasing PDLA block lendth during crystallizing at 90 and 100°*** at higher temperature,the crystallization rates increase at first and then decrease with block *** crystallization rates decrease as elevating the crystallization *** melting temperatures of PDLA blocks increase with block lengths and crystallization *** the PBS block,its crystallization behaviors are mainly controlled by the nucleation and confinement from PDLA *** crystallization and melting enthalpies as well as the crystallization and melting temperatures of PBS block reduce as a longer PDLA block has been copolymerized,while the crystallization rates of the PBS block exhibit unique component dependence,and the highest rate is observed in the B-D 2-2 *** Avrami exponent of PBS crystallites is reduced as a longer PDLA block is incorporated or the sample is crystallized at higher *** investigation provides a convenient route to tune the crystallization behavior of PBS and PLA.

关键词： Poly(butylenes succinate)(PBS) Poly(D-lactide)(PDLA) Poly(D-lactide)-block-PBS-block-poly(D-lactide)(PDLA-b-PBS-b-PDLA) Crystallization behavior

Combined effect of subsurface dam and layered heterogeneity on groundwater flow and salinity distribution in stratified coastal aquifers

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Acta Oceanologica Sinica 2023年第8期42卷 49-60页

作者： Chao gao Jun Kong Jun Wang Tong Zhou Yuncheng Wen Key Laboratory of Coastal Disaster and Protection of Ministry of Education Hohai UniversityNanjing 210000China Nanjing Hydraulic Research Institute Nanjing 210000China

In this paper,for the first time,we investigated the combined effect of subsurface dams and a typical stratified aquifer(two high-permeability layers with a low-permeability layer between them)on groundwater flow and salinity distribution in a tidally influenced coastal unconfined *** dams can inhibit the invasion of saltwater,and the low-permeability layer(LPL)and tide action can increase the effect of subsurface dams and the removal rate of residual *** sensitivity analysis,it was discovered that shifting the dam location towards the inland resulted in a reduction in the effective heights of the *** upper saline plume contracted with increasing dam height,and the upper boundary of LPL was moved to shallower *** the natural removal time increased significantly with increasing dam height and the bottom boundary of LPL was moved to deeper *** addition,if the dam location was close to the sea boundary and the bottom boundary of LPL was moved to deeper regions,we could increase the subsurface dam height to reduce the risks of control of saltwater *** study provides us a comprehensive understanding of the complex hydrodynamics of saltwater intrusion and provides guides for the design of subsurface dams aimed at saltwater intrusion control in stratified coastal aquifers.

关键词： stratified subsurface dams saltwater intrusion residual saltwater natural removal

Experimental investigation on aerodynamic and noise characteristics of Fenestron

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Chinese Journal of Aeronautics 2023年第12期36卷 88-101页

作者： Bo WANG Wei ZHANG Fei WANG Qijun ZHAO Chenkai CAO Yuan gao National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China China Helicopter Research and Development Institute Jingdezhen 333001China

It is difficult to simulate the strong interference and serious flow separation of Fenestron by the CFD method based on the widely used RANS equation,and the detailed experimental data,which could be used to validate the aerodynamic and noise numerical methods,is *** experimental investigation on the aerodynamic and noise characteristics of Fenestron is carried *** view of the complex internal flow field in duct and the relative motion between the stationary duct and the rotating rotor,a comprehensive aerodynamics and pressure measurement scheme is designed based on the bottom support *** this measurement scheme,the thrust generated by the rotating rotor can be measured by the rotating shaft balance,the thrusts from Fenestron are measured by the external balance and the pressures on duct inner wall are monitored by a pressure measuring *** fully capture the noise directionality of Fenestron,a series of noise observers located at an arc array are *** terms of the Fenestron test models,the baseline model,the performance improvement model based on the high-performance tail rotor and the noise reduction model based on the non-uniform blade distribution are designed *** the designed measurement scheme,aerodynamic forces and pressure distributions and noise were measured for the three different Fenestron *** results show that the aerodynamic thrusts of the tail rotor and duct increase greatly and the noise increases slightly for the performance improvement model because of the larger *** rotor aerodynamic performance of the noise reduction model is reduced,but the modulation effect of the tail rotor improves the forces of the *** noise radiated by the noise reduction model is reduced and a good noise reduction result is obtained in frequency domain.

关键词： Helicopter Fenestron Aeroacoustic wind tunnel Noise reduction Non-uniform rotor