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Fabrication of Ag3PO4-AgBr-PTh composite loaded on Na2SiO3 with enhanced visible-light photocatalytic activity

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Frontiers of Materials Science 2018年第3期12卷 264-272页

作者： Xiaojun niu Jinling MA School of Environment and Energy South China University of Technology Guangzhou 510006 China

A novel Ag3PO4-AgBr-PTh composite loaded on Na2SiO3 was synthesized for enhanced visible-light photocatalytic activity. The photocatalyUc activity of the samples was evaluated by photodegrading rhodamine B （RhB） under visible light irradiation. The main reactive species and possible photocatalytic mechanism were also discussed. As a result, the Ag3PO4-AgBr-PTh composite loaded on Na2SiO3 exhibited enhanced photocatalytic activity for RhB compared with Ag3PO4 under visible-light irradiation. Additionally, it was demonstrated that the hole （h＋） and superoxide radical （·O2-） were the major reactive species involving in the RhB degradation. PTh played vital role for the enhanced photocatalytic activity of Ag3PO4-AgBr-PTh-Na2SiO3 composite, which offered an electron transfer expressway and accelerated the transfer of the electrons from the CB of AgBr into Ag3PO4. This work could provide a new perspective for the synthesis of Ag3PO4-based composites and the improvement of photocatalytic activity of Ag3PO4.

关键词： Ag3PO4-AgBr-PTh-Na2SiO3 composite PTh photocatalytic activity visible light

Intracranial Epileptic Seizures Detection Based on an Optimized Neural Network Classifier

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Chinese Journal of Electronics 2021年第3期30卷 419-425页

作者： GONG Chen LIU Jiahui niu Yunyun School of Information Engineering China University of Geosciences in Beijing Institute of Automation Chinese Academy of Sciences School of Artificial Intelligence University of Chinese Academy of Sciences

Automatic identification of intracranial electroencephalogram(i EEG) signals has become more and more important in the field of medical *** this paper, an optimized neural network classifier is proposed based on an improved feature extraction method for the identification of i EEG epileptic *** kinds of entropy, Sample entropy, Approximate entropy, Shannon entropy, Log energy entropy are extracted from the database as the feature vectors of Neural network(NN) during the identification *** kinds of classification tasks, namely Pre-ictal v Post-ictal(CD), Pre-ictal v Epileptic(CE), Post-ictal v Epileptic(DE), Pre-ictal v Post-ictal v Epileptic(CDE),are used to test the effect of our classification *** experimental results show that our algorithm achieves higher performance in all tasks than previous *** effect of hidden layer nodes number is investigated by a constructive approach named growth method. We obtain the optimized number ranges of hidden layer nodes for the binary classification problems CD, CE, DE, and the multitask classification problem CDE, respectively.

关键词： improved feature extraction method medical signal processing optimized neural network classifier classification method classification tasks identification process intracranial electroencephalogram signals feature extraction medical diagnostics entropy feature vectors intracranial Epileptic seizures detection optimized number ranges Approximate entropy Log energy entropy neural nets Pre-ictal v Post-ictal medical signal detection constructive approach named growth method automatic identification pattern classification Shannonentropy electroencephalography Sample entropy

Nonlinear transient responses of rotating twisted FGM cylindrical panels

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Science China(Technological Sciences) 2021年第2期64卷 317-330页

作者： niu Yan YAO MingHui ZHANG Wei Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Structures College of Mechanical EngineeringBeijing University of TechnologyBeijing 100124China

This paper develops a new structure dynamic model to investigate nonlinear transient responses of the rotating blade made of functionally graded material(FGM). The rotating blade is simplified as a rotating FGM cylindrical panel with a presetting angle and a twist angle. The geometric nonlinearity effects are taken into account in the strain-displacement relationships, which are derived by Green strain tensor. Based on the first-order piston theory and the first-order shear deformation theory, the equations of motion for the rotating twisted FGM cylindrical panel are acquired by means of Hamilton principle and Galerkin *** Differentiation Formula(BDF) and Runge-Kutta Algorithm are used to solve the nonlinear equations of motion for the system. The effects of four pulse load conditions on the system subjected to the internal pulse load or the external pulse load are fully discussed. A detailed parametric analysis is performed by considering the effects of the rotating speed, volume fraction index and temperature.

关键词： nonlinear transient responses functionally graded material rotating twisted blade cylindrical panel

基于离散元法的水泥稳定碎石微裂细观机理研究

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土木与环境工程学报（中英文） 2025年第1期47卷 196-204页

作者：刘子龙马士宾贺苗梁栋牛宗岳河北工业大学土木与交通学院天津300401

为探究水泥稳定碎石微裂细观演化机理,构建了细观非均质水泥稳定碎石数值模型,结合室内无侧限抗压强度试验和单轴压缩数值试验反演出模型细观参数,引入微裂隙网络研究不同裂隙参数对微裂程度的影响,分析不同裂隙数目下系统能量演化规律... 详细信息

为探究水泥稳定碎石微裂细观演化机理,构建了细观非均质水泥稳定碎石数值模型,结合室内无侧限抗压强度试验和单轴压缩数值试验反演出模型细观参数,引入微裂隙网络研究不同裂隙参数对微裂程度的影响,分析不同裂隙数目下系统能量演化规律。结果表明:数值模拟与室内试验结果基本吻合,构建的水泥稳定碎石离散元模型可较为准确地表征材料细观破坏特征;微裂损伤是二次振动加载后裂隙宽度增大和裂隙数目增多共同作用的结果,裂隙密度对水泥稳定碎石微裂程度起决定性作用;裂隙密度增加,材料储存弹性应变能的能力减弱,峰值点水泥稳定碎石材料的输入总能量降低。验证了早期微裂对于降低收缩应力的积极作用,揭示了水泥稳定碎石材料微裂力学特征和细观机理。

关键词：水泥稳定碎石无侧限抗压强度离散元法微裂技术细观机理

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Jackson-type inequalities on high-dimensional spheres

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Science China Mathematics 2024年第11期67卷 2571-2586页

作者： Yeli niu Feng Dai Department of Mathematics Shanghai Normal UniversityShanghai 200234China Department of Mathematical and Statistical Sciences University of AlbertaEdmontonAB T6G2G1Canada

We study Jackson's inequality on high-dimensional spheres with respect to the modulus of smoothness defined via the rotation *** obtain a version of Jackson's inequality with a dimensionfree constant,extending Newman and Shapiro's well-known results in 1964 from the case of r=1 and p=∞to more general *** results partially overcome the curse of *** also establish similar results on the equivalence of the K-functional and modulus of smoothness.

关键词： modulus of smoothness K-functional Jackson's inequality high-dimensional approximation

Efficient degradation of methyl orange via multilayer films of titanium dioxide and silicotungstic acid

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Science China Chemistry 2012年第11期55卷 2366-2372页

作者： niu Ping HAO JingCheng Key Laboratory for Colloid and Interface Chemistry Ministry of EducationShandong UniversityJinan 250100China Key Laboratory of Coordination Chemistry and Functional Materials in Universities of Shandong Province Dezhou UniversityDezhou 253023China

We report layer-by-layer （LbL） assembly of TiO2 and H4SiW12O40 （SiW12） multilayer film on silicon wafers and glass slides for photocatalytic degradation of methyl orange （MO）. The photocatalytic efficiency of the obtained multilayer film increases along with the decrease of pH and salt concentration of the incubation solution. The results show that MO can be almost re- moved in pH 2.0 solution without salt addition in the first 60 min incubation when MO concentration is lower than 15 mg/L. Different salts show an apparent inhibitory effect on photocatalytic degradation of MO with the order of ZnC12〉KCI〉 NaC1〉LiCI. The TiO2/SiW12 multilayer film maintains photocatalytic activity even after five degradation cycles. The reaction of MO photodegradation accords with an apparent first-order dynamics.

关键词： TiO2 silicotungstic acid LbL assembly photocatalytic degradation methyl orange

Least energy solutions of nonlinear Schr odinger equations involving the fractional Laplacian and potential wells

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Science China Mathematics 2017年第2期60卷 261-276页

作者： niu MiaoMiao TANG ZhongWei School of Mathematical Sciences Beijing Normal University Beijing 100875 China

We are concerned with the existence of least energy solutions of nonlinear Schrodinger equations involving the fractional Laplacian（-△）%s u（x）＋λV（x）u（x）=u（x）^（p-1）,u（x）〉=0,x∈R^N,for sufficiently large λ,2〈p〈N-2s^-2N for N≥2. V（x） is a real continuous function on RN. Using variational methods we prove the existence of least energy solution uλ（x） which localizes near the potential well int V-1 （0） for A large. Moreover, if the zero sets int V-1 （0） of V（x） include more than one isolated component, then ux（x） will be trapped around all the isolated components. However, in Laplacian case s = 1, when the parameter A is large, the corresponding least energy solution will be trapped around only one isolated component and become arbitrarily small in other components of int V^-1（0）. This is the essential difference with the Laplacian problems since the operator （-△）s is nonlocal.

关键词： nonlinear SchrSdinger equation least energy solution fractional Laplacian variational methods

An Improved Method for Web Text Affective Cognition Computing Based on Knowledge Graph

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Computers, Materials & Continua 2019年第4期59卷 1-14页

作者： Bohan niu Yongfeng Huang Department of Electrical Engineering Columbia UniversityNew YorkNY 10027USA Department of Electronic Engineering Tsinghua UniversityBeijing100084China

The goal of research on the topics such as sentiment analysis and cognition is to analyze the opinions,emotions,evaluations and attitudes that people hold about the entities and their attributes from the *** word level affective cognition becomes an important topic in sentiment *** the(attribute,opinion word)binary relationship by word segmentation and dependency parsing,and labeling those by existing emotional dictionary combined with webpage information and manual annotation,this paper constitutes a binary relationship knowledge *** using knowledge embedding method,embedding each element in(attribute,opinion,opinion word)as a word vector into the Knowledge Graph by TransG,and defining an algorithm to distinguish the opinion between the attribute word vector and the opinion word *** with traditional method,this engine has the advantages of high processing speed and low occupancy,which makes up the time-costing and high calculating complexity in the former methods.

关键词： Affective cognition fine-grained knowledge representation knowledge graph

Branch-pipe-routing approach for ships using improved genetic algorithm

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Frontiers of Mechanical Engineering 2016年第3期11卷 316-323页

作者： Haiteng SUI Wentie niu Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin University Tianjin 300072 China

Branch-pipe routing plays fundamental and critical roles in ship-pipe design. The branch-pipe-routing problem is a complex combinatorial optimization problem and is thus difficult to solve when depending only on human experts. A modified genetic-algorithm-based approach is proposed in this paper to solve this problem. The simplified layout space is first divided into three- dimensional （3D） grids to build its mathematical model. Branch pipes in layout space are regarded as a combination of several two-point pipes, and the pipe route between two connection points is generated using an improved maze algorithm. The coding of branch pipes is then defined, and the genetic operators are devised, especially the complete crossover strategy that greatly accelerates the convergence speed. Finally, simulation tests demonstrate the performance of proposed method.

关键词： branch pipe ship industry piping system optimization algorithm