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Crosslinking Kinetics of Polyethylene with Small Amount of Peroxide and Its Influence on the Subsequent Crystallization Behaviors

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Chinese Journal of Polymer Science 2016年第9期34卷 1117-1128页

作者：牛艳华 Wen-bin Liang yin-ling zhang Xue-lian Chen Shih-yaw Lai Guang-xian Li Du-jin Wang College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering of ChinaSichuan UniversityChengdu 610065China Performance Material Center National Institute of Clean-and-low-carbon Energy(NICE)Beijing 102209China CAS Key Laboratory of Engineering Plastics Beijing National Laboratory for Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

Crosslinking reactions of high density polyethylene with low peroxide concentrations ranging from 0.1 wt% to 1.0 wt% at temperatures of 170, 180 and 190 ℃ were monitored by rheological measurements. A critical gel forms at the peroxide concentration of 0.2 wt%, where the transition from long chain branching generation to crosslinking network formation could occur. Rheokinetics of crosslinking can be fitted well by Ding-Leonov＇s model. The curing rate k2 at the earlier stage exhibits about 3 times acceleration per 10 ~C with increasing temperature, while the equilibrium modulus G＇ at the fully cured stage is almost independent of temperature. Influences of crosslinking on the subsequent crystallization behaviors were detected by DSC measurements. Above the critical gel concentration, crystallization is largely retarded as evidenced by the lower crystallization temperature Tc and crystallinity Xc due to the network formation. The secondary crystallization valley located at the temperature near 80 ℃ can be observed above the critical concentration, which becomes more evident with the increasing peroxide concentration and curing temperature. This phenomenon provides another evidence of crystallization retardation by the crosslinking network.

关键词： Polyethylene Rheology Crosslinking kinetics Crystallization.

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Dynamic recrystallization mechanism, texture evolution development and mechanical characteristics of a Mg–8.7Gd–4.18Y–0.42Zr magnesium alloy by ECAP

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Progress in Natural Science:Materials International 2024年第02期34卷 376-388页

作者： ling zhang yinglong Li School of Materials Science and Engineering Northeastern University School of Mechanical and Engineering Ningxia Institute of Science and Technology

Equal channel angle pressing is recognized for its ability to refine alloy grains and alter grain orientation, thereby achieve better mechanical performance of the magnesium alloy. This study investigates the microstructures,dynamic recrystallization mechanism, texture development, and mechanical performance of GW94K(Mg–8.7Gd–4.18Y–0.42Zr wt. %) Mg alloy following ECAP-4 passes at 400°C and 3 mm/min. Results show that when high-temperature deformation is undertaken, twin formation is suppressed while dislocation slip is facilitated, increasing dislocation density during deformation. Following ECAP deformation, the sample displayed higher fracture elongation, TYS, and UTS than the as-solutioned GW94K alloy. In particular, the GW94K alloy performed well mechanically after ECAP-4 passes, with an ultimate TYS of 231 MPa, an UTS of 290 MPa, and an elongation of 14.8 %. DDRX and shear bands induce CDRX, both of which are important in plastic deformation. as well as in modifying microstructure and grain orientation during ECAP deformation.

关键词： Dynamic recrystallization mechanism Equal channel angular pressing Magnesium alloy Mechanical performance Mg-Gd-Y-Zr alloy Texture development

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MODIFIED STOCHASTIC EXTRAGRADIENT METHODS FOR STOCHASTIC VARIATIONAL INEQUALITY

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Journal of Computational Mathematics 2024年第2期42卷 390-414页

作者： ling zhang lingling Xu School of Management and Economic Beijing Institute of TechnologyBeijing 100081China School of Mathematical Sciences Nanjing Normal UniversityNanjing 210023China School of Mathematical Sciences and Jiangsu Key Laboratory for NSLSCS Nanjing Normal UniversityNanjing 210023China

In this paper,we consider two kinds of extragradient methods to solve the pseudo-monotone stochastic variational inequality ***,we present the modified stochastic extragradient method with constant step-size(MSEGMC)and prove the convergence of *** the strong pseudo-monotone operator and the exponentially growing sample sequences,we establish the R-linear convergence rate in terms of the mean natural residual and the oracle complexity O(1/ǫ).Second,we propose a modified stochastic extragradient method with adaptive step-size(MSEGMA).In addition,the step-size of MSEGMA does not depend on the Lipschitz constant and without any line-search ***,we use some numerical experiments to verify the effectiveness of the two algorithms.

关键词： Stochastic variational inequality Pseudo-monotone Modified stochastic ex-tragradient methods Adaptive step-size

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New structure transistors for advanced technology node CMOS ICs

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National Science Review 2024年第3期11卷 24-41页

作者： Qingzhu zhang Yongkui zhang Yanna Luo Huaxiang yin Integrated Circuit Advanced Process R&D Center Institute of Microelectronics of Chinese Academy of Sciences(IMECAS) State key Lab of Fabrication Technologies for Integrated Circuits Institute of Microelectronics of Chinese Academy of Sciences School of Integrated Circuits University of Chinese Academy of Sciences

Over recent decades, advancements in complementary metal-oxide-semiconductor integrated circuits(ICs)have mainly relied on structural innovations in transistors. From planar transistors to the fin field-effect transistor(FinFET) and gate-all-around FET(GAAFET), more gate electrodes have been added to three-dimensional(3D) channels with enhanced control and carrier conductance to provide higher electrostatic integrity and higher operating currents within the same device footprint. Beyond the 1-nm node, Moore's law scaling is no longer expected to be applicable to geometrical shrinkage. Vertical transistor stacking, e.g. in complementary FETs(CFET), 3D stack(3DS) FETs and vertical-channel transistors(VFET), for enhanced density and variable circuit or system design represents a revolutionary scaling approach for sustained IC development. Herein, innovative works on specific structures, key process breakthroughs, shrinking cell sizes and design methodologies for transistor structure research and development are reviewed. Perspectives on future innovations in advanced transistors with new channel materials and operating theories are also discussed.

关键词： transistor CMOS GAAFET CFET 3DS FET

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Multi-instance partial-label learning: towards exploiting dual inexact supervision

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Science China(Information Sciences) 2024年第3期67卷 48-61页

作者： Wei TANG Weijia zhang Min-ling zhang School of Computer Science and Engineering Southeast University Key Laboratory of Computer Network and Information Integration (Southeast University) Ministry of Education School of Information and Physical Sciences The University of Newcastle

Weakly supervised machine learning algorithms are able to learn from ambiguous samples or labels, e.g., multi-instance learning or partial-label learning. However, in some real-world tasks, each training sample is associated with not only multiple instances but also a candidate label set that contains one groundtruth label and some false positive labels. Specifically, at least one instance pertains to the ground-truth label while no instance belongs to the false positive labels. In this paper, we formalize such problems as multi-instance partial-label learning(MIPL). Existing multi-instance learning algorithms and partial-label learning algorithms are suboptimal for solving MIPL problems since the former fails to disambiguate a candidate label set, and the latter cannot handle a multi-instance bag. To address these issues, a tailored algorithm named MIPLGP, i.e., multi-instance partial-label learning with Gaussian processes, is *** first assigns each instance with a candidate label set in an augmented label space, then transforms the candidate label set into a logarithmic space to yield the disambiguated and continuous labels via an exclusive disambiguation strategy, and last induces a model based on the Gaussian processes. Experimental results on various datasets validate that MIPLGP is superior to well-established multi-instance learning and partial-label learning algorithms for solving MIPL problems.

关键词： machine learning multi-instance partial-label learning multi-instance learning partial-label learning Gaussian processes

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Nutrient transport following water transfer through the world's largest water diversion channel

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Journal of Environmental Sciences 2024年第1期135卷 703-714页

作者： Yuanhui Cheng Hong zhang Wei yin State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085 China Changjiang Water Resources Protection Institute Wuhan 430051China University of Chinese Academy of Sciences Beijing 100049China

Nutrient levels in the artificial channel constructed for the Middle Route Project are significant indicators of water quality safety and aquatic ecological integrity for this large,interbasin ***,the distribution and transport of nutrients along the channel were poorly *** on a time-series dataset as well as mass balance and material flow analysis methods,the water and nutrient transport fluxes in the Middle Route of the South-to-North Water Diversion Project were identified in this *** results indicate that the nutrient concentrations varied considerably with time,but there was no significant difference among the 30 stations of the main *** temperature difference was the major factor in the large fluctuations of water quality indicators over *** nutrient loadings varied with the water volume outputs from the main channel to the waterreceiving *** deposition was an important source of nutrients in the main channel,accounting for 9.13%,20.6%,and 0.635%of the nitrogen,phosphorus,and sulfur input from the Danjiangkou Reservoir,*** 2021,a net accumulation of 988 tons of N,29 tons of P,and 2,540 tons of S,respectively,were present in the main *** increase of these external and internal nutrient loadings would cause water quality fluctuation and deterioration in some local sections of the main *** study quantified the spatial and temporal patterns of nutrient transport in the Middle Route and revealed the ecological effects on the aquatic environment,assisting authorities on the project to develop effective water conservation strategies.

关键词： Nutrient transport Spatiotemporal patterns The Middle Route The South-to-North Diversion Project Hydro-ecological effects Water-receiving cities

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Chemoselective and Living/Controlled Polymerization of Alkenyl Methacrylates by the Phosphonium Ylide/Organoaluminum Lewis Pairs

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Chinese Journal of Polymer Science 2024年第2期42卷 159-167,I0005页

作者： Zhi-Kang Chen Wu-Chao Zhao Yi-ling Zhao Cong-Lei Liu Liu-yin Jiang Yue-Tao zhang Hong-Ping Zhu State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen361005China State Key Laboratory of Supramolecular Structure and Materials College of ChemistryJilin UniversityChangchun130012China

Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been *** P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were *** the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy *** pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)*** thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.

关键词： Phosphonium ylide Alkenyl methacrylate Chemoselectivity Living/controlled polymerization Post-functionalization

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An approach to estimate tree height using PolInSAR data constructed by the Sentinel-1 dual-pol SAR data and RVoG model

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Journal of Electronic Science and Technology 2024年第3期22卷 69-79页

作者： yin zhang Ding-Feng Duan School of Resources and Environment University of Electronic Science and Technology of ChinaChengdu611731China

We estimate tree heights using polarimetric interferometric synthetic aperture radar(PolInSAR)data constructed by the dual-polarization(dual-pol)SAR data and random volume over the ground(RVoG)*** the Sentinel-1 SAR dual-pol(SVV,vertically transmitted and vertically received and SVH,vertically transmitted and horizontally received)configuration,one notes that S_(HH),the horizontally transmitted and horizontally received scattering element,is *** S_(HH)data were constructed using the SVH data,and polarimetric SAR(PolSAR)data were *** proposed approach was first verified in simulation with satisfactory *** was next applied to construct PolInSAR data by a pair of dual-pol Sentinel-1A data at Duke Forest,North Carolina,*** to local observations and forest descriptions,the range of estimated tree heights was overall *** the heights with the ICESat-2 tree heights at 23 sampling locations,relative errors of 5 points were within±30%.Errors of 8 points ranged from 30%to 40%,but errors of the remaining 10 points were>40%.The results should be encouraged as error reduction is *** instance,the construction of PolSAR data should not be limited to using SVH,and a combination of SVH and SVV should be ***,an ensemble of tree heights derived from multiple PolInSAR data can be considered since tree heights do not vary much with time frame in months or one season.

关键词： Constructed polarimetric SAR data Dual polarization Sentinel-1 SAR data Polarimetric interferometric SAR Random volume over the ground model Tree height estimation

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Efficiently simulating the work distribution of multiple identical bosons with boson sampling

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Frontiers of physics 2024年第3期19卷 197-206页

作者： Wen-Qiang Liu zhang-qi yin Center for Quantum Technology Research and Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements(MOE) School of PhysicsBeijing Institute of TechnologyBeijing 100081China

Boson sampling has been theoretically proposed and experimentally demonstrated to show quantum computational ***,it still lacks the deep understanding of the practical applications of boson *** we propose that boson sampling can be used to efficiently simulate the work distribution of multiple identical *** link the work distribution to boson sampling and numerically calculate the transition amplitude matrix between the single-boson eigenstates in a one-dimensional quantum piston system,and then map the matrix to a linear optical network of boson *** work distribution can be efficiently simulated by the output probabilities of boson sampling using the method of the grouped probability *** scheme requires at most a polynomial number of the samples and the optical *** work opens up a new path towards the calculation of complex quantum work distribution using only photons and linear optics.

关键词： quantum simulation quantum work distribution boson sampling linear optic

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An efficient parallel algorithm of variational nodal method for heterogeneous neutron transport problems

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Nuclear Science and Techniques 2024年第4期35卷 29-45页

作者： Han yin Xiao-Jing Liu Teng-Fei zhang School of Nuclear Science and Engineering Shanghai Jiao Tong UniversityShanghai 2002040China

The heterogeneous variational nodal method(HVNM)has emerged as a potential approach for solving high-fidelity neutron transport ***,achieving accurate results with HVNM in large-scale problems using high-fidelity models has been challenging due to the prohibitive computational *** paper presents an efficient parallel algorithm tailored for HVNM based on the Message Passing Interface *** algorithm evenly distributes the response matrix sets among processors during the matrix formation process,thus enabling independent construction without *** the formation tasks are completed,a collective operation merges and shares the matrix sets among the *** the solution process,the problem domain is decomposed into subdomains assigned to specific processors,and the red-black Gauss-Seidel iteration is employed within each subdomain to solve the response matrix ***-to-point communication is conducted between adjacent subdomains to exchange data along the *** accuracy and efficiency of the parallel algorithm are verified using the KAIST and JRR-3 test *** results obtained with multiple processors agree well with those obtained from Monte Carlo *** parallelization of HVNM results in eigenvalue errors of 31 pcm/-90 pcm and fission rate RMS errors of 1.22%/0.66%,respectively,for the 3D KAIST problem and the 3D JRR-3 *** addition,the parallel algorithm significantly reduces computation time,with an efficiency of 68.51% using 36 processors in the KAIST problem and 77.14% using 144 processors in the JRR-3 problem.

关键词： Neutron transport Variational nodal method Parallelization KAIST JRR-3

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