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npj Computational Materials 2019年第1期5卷 246-253页

作者： Tibor Szilvási benjamin w.j.chen Manos Mavrikakis Department of Chemical&Biological Engineering University of Wisconsin-Madison1415 Engineering DriveMadisonWI 53706USA

The diverse coordination environments on the surfaces of discrete,three-dimensional(3D)nanoclusters contribute significantly to their unique catalytic *** the numerous adsorption sites and diffusion paths on these clusters is however tedious and time-consuming,especially for large,asymmetric ***,we present a simple,automated method for constructing approximate 2D potential energy surfaces for the adsorption of atomic species on the surfaces of 3D nanoclusters with minimal human *** potential energy surfaces fully characterize the important adsorption sites and diffusion paths on the nanocluster surfaces with accuracies similar to current approaches and at comparable computational *** method can treat complex nanoclusters,such as alloy nanoclusters,and accounts for cluster relaxation and adsorbate-induced reconstruction,important for obtaining accurate ***,its highly parallelizable nature is ideal for modern supercomputer architectures.

关键词： properties adsorption cluster

Interfacial stress engineering toward enhancement of ferroelectricity in Al doped HfO_(2)thin films

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Chinese Physics B 2024年第9期33卷 637-643页

作者： S X chen M M chen Y Liu D w Cao G j chen Department of Microelectronics Jiangsu UniversityZhenjiang 212013China Department of Physics Jiangsu UniversityZhenjiang 212013China Guangdong–Hong Kong–Macao joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology Foshan UniversityFoshan 528225China

Ferroelectric HfO_(2)has attracted much attention owing to its superior ferroelectricity at an ultra-thin thickness and good compatibility with Si-based complementary metal-oxide-semiconductor(CMOS)***,the crystallization of polar orthorhombic phase(o-phase)HfO_(2)is less competitive,which greatly limits the ferroelectricity of the as-obtained ferroelectric HfO_(2)thin ***,the crystallization of o-phase HfO_(2)can be thermodynamically modulated via interfacial stress *** this paper,the growth of improved ferroelectric Al doped HfO_(2)(HfO_(2):Al)thin films on(111)-oriented Si substrate has been *** analysis has suggested that nonpolar monoclinic HfO_(2):Al grown on(111)-oriented Si substrate suffered from a strong compressive strain,which promoted the crystallization of(111)-oriented o-phase HfO_(2)in the as-grown HfO_(2):Al thin *** addition,the in-plane lattice of(111)-oriented Si substrate matches well with that of(111)-oriented o-phase HfO_(2),which further thermally stabilizes the o-phase HfO_(2).Accordingly,an improved ferroelectricity with a remnant polarization(2P_(r))of 26.7C/cm^(2) has been *** results shown in this work provide a simple way toward the preparation of improved ferroelectric HfO_(2)thin films.

关键词： improved ferroelectricity interfacial stress engineering compressive strain HfO_(2)

Rescattering of stimulated Raman side scattering in nonuniform plasmas

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Matter and Radiation at Extremes 2024年第5期9卷 68-76页

作者： S.Tan Q.wang Y.chen w.B.Yao C.Z.Xiao j.F.Myatt School of Physics and Electronics Hunan UniversityChangsha 410082China Institute of Applied Physics and Computational Mathematics Beijing 100094China School of Electrical and Information Engineering Anhui University of Science and TechnologyHuainanAnhui 232001China Department of Electrical and Computer Engineering University of Alberta9211116 St.NWEdmontonAlberta T6G 1H9Canada

Rescattering of stimulated Raman side scattering(SRSS)is observed for the first time via two-dimensional(2D)particle-in-cell(PIC)*** construct a theoretical model for the rescattering process,which can predict the region of occurrence of mth-order SRSS and estimate its *** rescattering process is identified by the 2D PIC simulations under typical conditions of a direct-drive inertial confinement fusion *** electrons produced by second-order SRSS propagate nearly perpendicular to the density gradient and gain nearly the same energy as in first-order SRSS,but there is no cascade acceleration to produce superhot *** studies for a wide range of ignition conditions show that SRSS and associated rescatterings are robust and important processes in inertial confinement fusion.

关键词： nonuniform acceleration scattering

Surface engineering with ionic polymers on membranes for boron removal

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Frontiers of Chemical Science and Engineering 2024年第5期18卷 61-69页

作者： Xiting Zhang chenyi Fang j Paul chen Sui Zhang Department of Chemical and Biomolecular Engineering National University of SingaporeSingapore 117576Singapore Department of Civil and Environmental Engineering National University of SingaporeSingapore 119260Singapore College of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060China

Removal of boric acid from seawater and wastewater using reverse osmosis membrane technologies is imperative and yet remains inadequately addressed by current commercial *** research efforts performed post-modification of reverse osmosis membranes to enhance boron rejection,which is usually accompanied by substantial sacrifice in water *** study delves into the surface engineering of low-pressure reverse osmosis membranes,aiming to elevate boron removal efficiency while maintaining optimal salt rejection and water *** were modified by the self-polymerization and co-deposition of dopamine and polystyrene sulfonate at varying ratios and *** surfaces became smoother and more hydrophilic after *** optimum membrane exhibited a water permeability of 9.2±0.1 L·m^(-2)·h^(-1)·bar^(-1),NaCl rejection of 95.8%±0.3%,and boron rejection of 49.7%±0.1% and 99.6%±0.3% at neutral and alkaline pH,*** water permeability is reduced by less than 15%,while the boron rejection is 3.7 times higher compared to the blank *** research provides a promising avenue for enhancing boron removal in reverse osmosis membranes and addressing water quality concerns in the desalination process.

关键词： membrane low-pressure reverse osmosis boron surface engineering

A REDUCED ORDER SCHwARZ METHOD FOR NONLINEAR MULTISCALE ELLIPTIC EQUATIONS BASED ON TwO-LAYER NEURAL NETwORKS

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journal of Computational Mathematics 2024年第2期42卷 570-596页

作者： Shi chen Zhiyan Ding Qin Li Stephen j.wright Mathematics Department University of Wisconsin-MadisonMadisonWI 53706USA Department of Mathematics University of California-BerkeleyBerkeley CA 94720USA Mathematics Department and Discovery Institute University of Wisconsin-Madison MadisonWI 53706USA Computer Sciences Department University of WisconsinMadisonWI 53706USA

Neural networks are powerful tools for approximating high dimensional data that have been used in many contexts,including solution of partial differential equations(PDEs).we describe a solver for multiscale fully nonlinear elliptic equations that makes use of domain decomposition,an accelerated Schwarz framework,and two-layer neural networks to approximate the boundary-to-boundarymap for the subdomains,which is the key step in the Schwarz ***,the boundary-to-boundary map requires solution of boundary-value elliptic problems on each *** leveraging the compressibility of multiscale problems,our approach trains the neural network offline to serve as a surrogate for the usual implementation of the boundary-to-boundary *** method is applied to a multiscale semilinear elliptic equation and a multiscale p-Laplace *** both cases we demonstrate significant improvement in efficiency as well as good accuracy and generalization performance.

关键词： Nonlinear homogenization Multiscale elliptic problem Neural networks Do-main decomposition

Full-spectrum Bi@SrTiO_(3) for bi-directional promotion effects on photocatalytic redox reaction:Insight into intermediates and mechanism

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journal of Rare Earths 2024年第5期42卷 917-929,I0004页

作者： Bin Liu Nanhao Zhou jun Liu Xinglei wang Peter K.j.Robertson Xiaoyuan chen Chao chen jianmin Luo Chuanyi wang School of Chemistry and Civil Engineering Shaoguan UniversityShaoguan512005China chengdu Customs Technology Center Chengdu610041China Key Laboratory of Pollutant Chemistry and Environmental Treatment College of Chemistry and Environmental ScienceYili Normal UniversityYining835000China School of Chemistry and Chemical Engineering Queen's University BelfastStranmillis RoadBelfastBT95AGUnited Kingdom Guangzhou Institute of Industrial Intelligence(GIII) Guangzhou511400China

The development of full-spectrum photocatalysts active in the near-infrared(NIR)region has gained increasing attention for deleterious pollutant *** integration of plasmonic metals with semico nductors is an effective way to widen the light re sponse range of photocatalysts due to the strong light absorption and fast plasmonic energy transfer of the localized surface plasmon resonance(LSPR).In this work,the full-spectrum responsive Bi@SrTiO_(3) was prepared via facile solvothermal chemical *** optimal Bi@SrTiO_(3) achieves exceptional photocatalytic Cr(VI)reduction efficiency and tetracycline degradation,realizing bi-directional promotion effects on redox *** to density functional theory(DFT)simulations,the extraordinary photocatalytic performance is attributed to the tunable builtin electric field(IEF)of the Ohmic *** favorable adaptability in real water and high stability of BSTO-25 were proved by experime ntal *** the po ssible photocatalytic mechanism was proposed based on theoretical calculation and experimental ***,the non-toxicity of the BSTO-25 was evaluated by *** cultivation,which further proves the feasibility of treating wastewater with *** work provides a new perspective on constructing full-spectrum-driven photocatalysts for applications dealing with environmental remediation.

关键词： Full-spectrum photocatalysts Localized surface plasmon resonance Ohmic contact Cr(Ⅵ)reduction Antibiotic degradation Rare earths

Characterization of geological uncertainties from limited boreholes using copula-based coupled Markov chains for underground construction

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Underground Space 2024年第3期16卷 94-105页

作者： Fan wang Heng Li Gang Li Zheng-jun You Elton j.chen National Center of Technology Innovation for Digital Construction Huazhong University of Science and TechnologyWuhan 430074China Department of Civil and Hydraulic Engineering Huazhong University of Science and TechnologyWuhan 430074China Department of Building and Real Estate The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shanghai Tunnel Engineering Co. Ltd.Shanghai 200032China wuhan Metro Group Co.Ltd. Wuhan 430070China

This paper proposes an efficient method for quantifying the stratigraphic uncertainties and modeling the geological formations based on *** Markov chains are used to describe the soil transitions along different directions,and the transition probability matrices(TPMs)of the Markov chains are analytically expressed by *** copula expression is efficient since it can represent a large TPM by a few unknown *** to the analytical expression of the TPMs,the likelihood function of the Markov chain model is given in an explicit *** estimation of the TPMs is then re-casted as a multi-objective constrained optimization problem that aims to maximize the likelihoods of two independent Markov chains subject to a set of parameter *** the method which determines the TPMs by counting the number of transitions between soil types,the proposed method is more statistically ***,a random path sampling method is presented to avoid the directional effect problem in *** soil type at a location is inferred from its nearest known neighbors along the cardinal directions.A general form of the conditional probability,based on Pickard’s theorem and Bayes rule,is presented for the soil type *** proposed stratigraphic characterization and simulation method is applied to real borehole data collected from a construction site in wuhan,*** is illustrated that the proposed method is accurate in prediction and does not show an inclination during simulation.

关键词： Geological stratigraphy Markov chain Transition probability matrix Statistical method Copula

GraphFlow+:Exploiting Conversation Flow in Conversational Machine Comprehension with Graph Neural Networks

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Machine Intelligence Research 2024年第2期21卷 272-282页

作者： jing Hu Lingfei wu Yu chen Po Hu Mohammed j.Zaki School of Computer Science Central China Normal UniversityWuhan 430079China Pinterest San Francisco 94016USA Meta Mountain View 94039USA Rensselaer Polytechnic Institute Troy 12180USA

The conversation machine comprehension(MC)task aims to answer questions in the multi-turn conversation for a single ***,recent approaches don’t exploit information from historical conversations effectively,which results in some references and ellipsis in the current question cannot be *** addition,these methods do not consider the rich semantic relationships between words when reasoning about the passage *** this paper,we propose a novel model GraphFlow+,which constructs a context graph for each conversation turn and uses a unique recurrent graph neural network(GNN)to model the temporal dependencies between the context graphs of each ***,we exploit three different ways to construct text graphs,including the dynamic graph,static graph,and hybrid graph that combines the *** experiments on CoQA,QuAC and DoQA show that the GraphFlow+model can outperform the state-of-the-art approaches.

关键词： Conversational machine comprehension(MC) reading comprehension question answering graph neural networks(GNNs) natural language processing(NLP)

Granger causal representation learning for groups of time series

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Science China(Information Sciences) 2024年第5期67卷 56-68页

作者： Ruichu CAI Yunjin wU Xiaokai HUANG wei chen Tom Z.j.FU Zhifeng HAO School of Computer Science Guangdong University of Technology Peng cheng Laboratory College of Science Shantou University

Discovering causality from multivariate time series is an important but challenging *** existing methods focus on estimating the Granger causal structures among multivariate time series,while ignoring the prior knowledge of these time series, e.g., the group of the time series. Focusing on discovering the Granger causal structures among groups of time series, we propose a Granger causal representation learning method to solve this problem. First, we use the multiset canonical correlation analysis method to learn the Granger causal representation of each group of time series. Then, we model the Granger causal relationships among the learned Granger causal representations using a recurrent neural network with temporal information. Finally, we formulate the above two stages into one unified optimization problem, which is efficiently solved using the augmented Lagrangian method. we conduct extensive experiments on synthetic and real-world datasets to validate the correctness and effectiveness of the proposed method.

关键词： Granger causal discovery Granger causal representation learning time series data recurrent neural network multiset canonical correlation analysis

Lax-Oleinik-Type Formulas and Efficient Algorithms for Certain High-Dimensional Optimal Control Problems

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Communications on Applied Mathematics and Computation 2024年第2期6卷 1428-1471页

作者： Paula chen jerome Darbon Tingwei Meng Division of Applied Mathematics Brown UniversityProvidenceRIUSA Department of Mathematics UCLALos AngelesCAUSA

Two of the main challenges in optimal control are solving problems with state-dependent running costs and developing efficient numerical solvers that are computationally tractable in high *** this paper,we provide analytical solutions to certain optimal control problems whose running cost depends on the state variable and with constraints on the *** also provide Lax-Oleinik-type representation formulas for the corresponding Hamilton-jacobi partial differential equations with state-dependent ***,we present an efficient,grid-free numerical solver based on our representation formulas,which is shown to scale linearly with the state dimension,and thus,to overcome the curse of *** existing optimization methods and the min-plus technique,we extend our numerical solvers to address more general classes of convex and nonconvex initial *** demonstrate the capabilities of our numerical solvers using implementations on a central processing unit(CPU)and a field-programmable gate array(FPGA).In several cases,our FPGA implementation obtains over a 10 times speedup compared to the CPU,which demonstrates the promising performance boosts FPGAs can *** numerical results show that our solvers have the potential to serve as a building block for solving broader classes of high-dimensional optimal control problems in real-time.

关键词： Optimal control Hamilton-jacobi partial differential equations Grid-free numerical methods High dimensions Field-programmable gate arrays(FPGAs)