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Aging process design based on the morphological evolution ofγprecipitates in a 4th generation nickel-based single crystal superalloy

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Journal of Materials Science & Technology 2023年第16期147卷 176-188页

作者： Jiachen Xu Xinbao Zhao Weiqi Li Hao Liu Quanzhao Yue Huanchang Duan Yuefeng Gu Ze Zhang Institute of Superalloys Science and Technology School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027ZhejiangChina Polytechnic Institute Zhejiang UniversityHangzhou 310027ZhejiangChina

In order to meet the design requirements of the aging treatment process of a 4th generation nickel-based single crystal superalloy(Ni-SX)developed independently,the effects of aging temperatures and aging times on the precipitation and morphological evolution ofγprecipitates are *** morphological evolution behavior ofγprecipitates during the aging process is summarized subsequently and the coarsening behavior ofγprecipitates is discussed by comparing with the Lifshitz-Slyozov-Wagner model(LSW)and the trans-interface diffusion-controlled model(TIDC).It is demonstrated that primary aging temperature and secondary aging time dominate the size and squareness ofγprecipitates respectively,a narrow primary aging temperature range and a suitable secondary aging time are allowed to obtain the optimized morphology ofγ*** optimal aging process of the Ni-SX investigated in the present work is obtained for 1100-1120°C/4 h and 870°C/16 h,confirmed by the corresponding creep *** coarsening growth ofγprecipitates in short-term aging also conforms to the LSW model ***,the aging process design rules of various Ni-SXs of different generations are also summarized.

关键词： Nickel-based single crystal superalloy Aging temperature Aging time γprecipitates Creep

Patch-based variational image approximation

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Science China(Information Sciences) 2017年第3期60卷 78-87页

作者： Hao XIE Ruofeng TONG Artificial Intelligence Institute Zhejiang University College of New Media Zhejiang University of Media and Communications

Vector graphic gives us a new solution to the representation of raster images. Among many types of vectorized representations, the most popular is mesh representation, which inherits the benefits of vector graphics. Inspired by mesh, we propose a novel patch-based representation for raster images, in which pixels are partitioned into regions, and pixels belonging to the same region are converted into a 3D point cloud and approximated by a 3D planar patch with proper boundaries in a variational way. The resulting patches are then encoded via a half-edge structure for storage. The key point is that the vertices of boundaries are not located on the very positions of sample points, i.e. converted pixels, but dependent on the optimal position of the patch,which theoretically reduces the fitting errors. Experiments show that our algorithm produces better results.

关键词： image approximation vector graphics image representation plane optimization boundary extrac tion

Lithium nitrate regulated carbonate electrolytes for practical Li-metal batteries: Mechanisms, principles and strategies

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Journal of Energy Chemistry 2023年第2期77卷 581-600,I0015页

作者： Kun Wang Wenbing Ni Liguang Wang Lu Gan Jing Zhao Zhengwei Wan Wei Jiang Waqar Ahmad Miaomiao Tian Min Ling Jun Chen Chengdu Liang zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027ZhejiangChina Institute of zhejiang university-Quzhou Quzhou 324000ZhejiangChina

Li-metal batteries(LMBs)regain research prominence owing to the ever-increasing high-energy *** available carbonate electrolytes exhibit unfavourable parasitic reactions with Limetal anode(LMA),leading to the formation of unstable solid electrolyte interphase(SEI)and the breed of Li dendrites/dead ***,lithium nitrate(LiNO_(3)),an excellent film-forming additive,proves crucial to construct a robust Li_(3)N/Li_(2)O/Li_(x)NO_(y)-rich SEI after combining with ether-based ***,the given challenge leads to natural ideas which suggest the incorporation of LiNO_(3) into commercial carbonate for practical ***,LiNO_(3) demonstrates limited solubility(~800 ppm)in commercial carbonate ***,developing stable SEI and dendrite-free LMA with the incorporation of LiNO_(3) into carbonate electrolytes is an efficacious strategy to realize robust LMBs via a scalable and cost-effective ***,this review unravels the grievances between LMA,LiNO_(3)and carbonate electrolytes,and enables a comprehensive analysis of LMA stabilizing mechanism with LiNO_(3),dissolution principle of LiNO_(3) in carbonate electrolytes,and LiNO_(3) introduction *** review converges attention on a point that the LiNO_(3)-introduction into commercial carbonate electrolytes is an imperious choice to realize practical LMBs with commercial 4 V layered cathode.

关键词： Li-metal battery Carbonate electrolyte Lithium nitrate Stabilization mechanism Dissolution principle Introduction strategy

Topological Distillation by Principal Component Analysis in Disordered Fractional Quantum Hall States

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Chinese Physics Letters 2020年第11期37卷 81-86页

作者： Na Jiang Min Lu zhejiang Institute of Modern Physics Zhejiang UniversityHangzhou 310027China

We study the behavior of two-dimensional electron gas in the fractional quantum Hall(FQH)regime in the presence of disorder *** principal component analysis is applied to a set of disordered Laughlin ground state model wave function to enable us to distill the model wave function of the pure Laughlin *** increasing the disorder strength,the ground state wave function is expected to deviate from the Laughlin state and eventually leave the FQH *** investigate the phase transition from the Laughlin state to a topologically trivial state by analyzing the overlap between the random sample wave functions and the distilled ground state wave *** is proposed that the cross point of the principal component amplitude and its counterpart is the critical disorder strength,which marks the collapse of the FQH regime.

关键词： potential. function. trivial

Graph-tree-based software control flow checking for COTS processors on pico-satellites

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Chinese Journal of Aeronautics 2013年第2期26卷 413-422页

作者： Yang Mu Wang Hao Zheng Yangming Jin Zhonghe Department of Information Science and Electronic Engineering Zhejiang University School of Aeronautics and Astronautics Zhejiang University

This paper proposes a generic high-performance and low-time-overhead software control flow checking solution, graph-tree-based control flow checking （GTCFC） for space-borne commercial-off-the-shelf （COTS） processors. A graph tree data structure with a topology similar to common trees is introduced to transform the control flow graphs of target programs. This together with design of IDs and signatures of its vertices and edges allows for an easy check of legality of actual branching during target program execution. As a result, the algorithm not only is capable of detecting all single and multiple branching errors with low latency and time overheads along with a linear-complexity space overhead, but also remains generic among arbitrary instruction sets and independent of any specific hardware. Tests of the algorithm using a COTS-processor-based onboard computer （OBC） of in-service ZDPS-1A pico-satellite products show that GTCFC can detect over 90% of the randomly injected and all-pattern-covering branching errors for different types of target programs, with performance and overheads consistent with the theoretical analysis; and beats well-established preeminent control flow checking algorithms in these dimensions. Furthermore, it is validated that GTCGC not only can be accommodated in pico-satellites conveniently with still sufficient system margins left, but also has the ability to minimize the risk of control flow errors being undetected in their space missions. Therefore, due to its effectiveness, efficiency, and compatibility, the GTCFC solution is ready for applications on COTS processors on pico-satellites in their real space missions.

关键词： Branching error Commercial-off-the-shelf (COTS) Control flow checking Error injection Graph tree On-board computer Pico-satellite

Stochastic Estimations of Fermion Matrix Determinants with Unbiased Subtractions

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Chinese Physics Letters 1998年第6期15卷 401-403页

作者： YING He-ping zhejiang Institute of Modern Physics Zhejiang UniversityHangzhou 310027

The Padé-Z_(2) stochastic estimator is used to calculate the fermion matrix determinants and the determinant ratios with an unbiased variational *** results on an 8^(3)×12 lattice with Wilson action show that the determinant ratio with a relatively small number of Z_(2) noises(e.g.,400)can be estimated by using the unbiased subtractions.

关键词： determinant Fermi estimator

Stable zinc metal anodes achieved by dynamic counteracting tip effect and interfacial ion redistribution

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Journal of Energy Chemistry 2024年第12期99卷 172-181页

作者： Leilei Sun Yang Wang Kun Zhang Bin Luo Guosheng Duan Sinan Zheng Zhean Bao Jingyun Huang Zhizhen Ye State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027ZhejiangChina Institute of Wenzhou Zhejiang UniversityWenzhou 325006ZhejiangChina Institute of Thermal Science and Power Systems Zhejiang UniversityHangzhou 310027ZhejiangChina

Aqueous zinc metal batteries (AZMBs) are hindered by uncontrolled dendrites and side reactions during commercialization,despite their advantages of safety and high capacity ***,we propose the electrical feedback strategy to restrain the Zn dendrites resulting from the"tip effect"and optimize interfacial Zn^(2+)distribution to accelerate electrodeposition kinetics by using the lithium niobate (LNO) ***,at the bumps of the zinc anode,the ferroelectric LNO is polarized by the locally strong electric field,which in turn counteracts the"tip effect".In this way,the dynamic polarization of LNO can repair the uneven tip electric field to achieve uniform and flat zinc *** addition,owing to the interaction between Nb and Zn^(2+),a higher concentration of Zn^(2+)near the zincophilic LNO@Zn surface is obtained for the rapid electrochemical reaction kinetics of *** the aforementioned advantages,the LNO@Zn anode harvests stable cycling over 1200 h at 10 mA cm^(-2)with a superior cumulative capacity of 5800 mAh cm^(-2).Assembled with the a-MnO_(2) cathode,the full cell using LNO@Zn anode exhibits the slower capacity decay (0.054%per cycle) during 1000 *** strategy provides a perspective for stabilizing zinc metal anodes through dynamic electrical response and interfacial ion redistribution effect.

关键词： Zinc dendrite Tip effect Electrical feedback Ion distribution Anode optimization

Short-term traffic safety forecasting using Gaussian mixture model and Kalman filter

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Journal of zhejiang university-Science A(Applied Physics & Engineering) 2013年第4期14卷 231-243页

作者： Sheng JIN Dian-hai WANG Cheng XU Dong-fang MA College of Civil Engineering and Architecture Zhejiang University zhejiang Police College

In this paper,a prediction model is developed that combines a Gaussian mixture model(GMM) and a Kalman filter for online forecasting of traffic safety on *** time-to-collision(TTC) samples are divided into two categories:those representing vehicles in risky situations and those in safe ***,the GMM is used to model the bimodal distribution of the TTC samples,and the maximum likelihood(ML) estimation parameters of the TTC distribution are obtained using the expectation-maximization(EM) *** propose a new traffic safety indicator,named the proportion of exposure to traffic conflicts(PETTC),for assessing the risk and predicting the safety of expressway traffic.A Kalman filter is applied to forecast the short-term safety indicator,PETTC,and solves the online safety prediction problem.A dataset collected from four different expressway locations is used for performance *** test results demonstrate the precision and robustness of the prediction model under different traffic conditions and using different *** results could help decision-makers to improve their online traffic safety forecasting and enable the optimal operation of expressway traffic management systems.

关键词： Forecasting Traffic safety Gaussian mixture model Kalman filter

Effect of Oscillatory Shear on the Mechanical Properties and Crystalline Morphology of Linear Low Density Polyethylene

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Chinese Journal of Polymer Science 2015年第8期33卷 1114-1124页

作者： Zhong-bin Xu Liang-yao Su Peng-fei Wang 彭懋 College of Chemical and Biological Engineering Zhejiang University Department of Polymer Sci & Engn Zhejiang University

In this study, effects of oscillatory shear with different frequencies （0-2.5 Hz） and amplitudes （0-20 mm） on the mechanical properties and crystalline morphology of linear low density polyethylene （LLDPE） were investigated. It was found that the mechanical properties of LLDPE are improved because of the more perfect crystalline structure when LLDPE crystallizes under low-frequency and small-amplitude （0.2 Hz/4 mm） oscillatory shear. The mechanical properties can be further improved by increasing either the frequency or the amplitude of oscillatory shear. The Young＇s modulus and tensile strength of LLDPE are improved by 27% and 20%, respectively, when the frequency is increased to 2.5 Hz and the amplitude is maintained at 4 mm; while the Young＇s modulus and tensile strength are improved by 49% and 47%, respectively, when the amplitude is increased to 20 mm and the frequency is remained as 0.2 Hz. The crystallinity and microstructure of LLDPE under different oscillatory shear conditions were investigated by using differential scanning calorimetry, wide angle X-ray diffraction and scanning electron microscopy to shed light on the mechanism for the improvement of mechanical properties.

关键词： Oscillatory shear Linear low density polyethylene Shish-kebab Mechanical property Crystalline morphology.