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Exploring the Linear and Nonlinear Causality Between Internet Big Data and Stock Markets

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Journal of Systems Science & Complexity 2020年第3期33卷 783-798页

作者： DONG Jichang dai Wei LI Jingjing School of Economics and Management University of Chinese Academy of SciencesBeijing 100190China School of Economics and Management Beihang UniversityBeijing 100191China

In the era of big data,stock markets are closely connected with Internet big data from diverse *** paper makes the first attempt to compare the linkage between stock markets and various Internet big data collected from search engines,public media and social *** achieve this purpose,a big data-based causality testing framework is proposed with three steps,i.e.,data crawling,data mining and causality *** the Shanghai Stock Exchange and Shenzhen Stock Exchange as targets for stock markets,web search data,news,and microblogs as samples of Internet big data,some interesting findings can be obtained.1)There is a strong bi-directional,linear and nonlinear Granger causality between stock markets and investors'web search behaviors due to some similar trends and uncertain factors.2)News sentiments from public media have Granger causality with stock markets in a bi-directional linear way,while microblog sentiments from social media have Granger causality with stock markets in a unidirectional linear way,running from stock markets to microblog sentiments.3)News sentiments can explain the changes in stock markets better than microblog sentiments due to their *** results of this paper might provide some valuable information for both stock market investors and modelers.

关键词： Granger causality test internet big data investors'sentiment stock markets web search behavior

Boosting the electrochromic performance of TiO_(2) nanowire film via successively evolving surface structure

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Science China Chemistry 2021年第5期64卷 745-752页

作者： Baohu dai Changzheng Wu Yi Xie Department of Chemistry School of Chemistry and Materials ScienceUniversity of Science and Technology of ChinaHefei 230026China Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China Collaborative Innovation Center of Chemistry for Energy Materials University of Science and Technology of ChinaHefei 230026China CAS Key Laboratory of Mechanical Behavior and Design of Materials University of Science and Technology of ChinaHefei 230026China

Electrochromic transition metal oxides(ETMOs)are useful in energy saving devices and smart *** these ETMO candidates,titanium dioxide(TiO_(2))is intriguing for its abundance and environmental safety,but the low color efficiency and slow coloring rate are still barricades to promote its electrochromic ***,we demonstrate an amorphization strategy to comprehensively enhance the performance of TiO_(2) nanowire film(TNF)via atomic layer deposition(ALD)of an additional TiO_(2) conformal layer onto TNF surface,of which the layer structure evolves successively from ordered to disordered,achieving tunable electrochromism by controlling ALD *** the remarkable increment of charging efficiency by~35% and color efficiency by~40%,bleached transmittance rectified optical density(BTR density)and ion diffusion coefficient are boosted by~90% and over 15 times,respectively for TNF deposited with 150 cycles.A large number of self-doped Ti^(3+) defects and hydroxyl units together with order-disorder interconnections in the ALD TiO_(2) layer are responsible for the performance *** concept for successively evolving surface structure shares the feasibility of upgrading conventional ETMOs as well as designing new electrochromic materials.

关键词： electrochromism TiO_(2) evolving surface structure BTR density ALD

L^(2) Boundedness of the Fourier Integral Operator with Inhomogeneous Phase Functions

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Acta Mathematica Sinica,English Series 2023年第8期39卷 1525-1546页

作者： Jia Wei dai Jie Cheng CHEN School of Electronic and Information Engineering(School of Big Data Science) Taizhou UniversityTaizhou 318000P.R.China Department of Mathematics Zhejiang Normal UniversityJinhua 321004P.R.China

In this paper,we investigate the L^(2) boundedness of the Fourier integral operator Tφ,a with smooth and rough symbols and phase functions which satisfy certain non-degeneracy *** particular,if the symbol a∈L∞Smρ,the phase functionφsatisfies some measure conditions and ∇kξφ(·,ξ)L∞≤C|ξ|−k for all k≥2,ξ≠0,and some∈>0,we obtain that Tφ,a is bounded on L^(2) if m

关键词： Fourier integral operator,L^(2)boundedness inhomogeneous phase

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Ground movements modeling applying adjusted influence function

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International Journal of Mining Science and Technology 2020年第2期30卷 243-249页

作者： Agnieszka Malinowska Ryszard Hejmanowski Huayang dai AGH University of Science and Technology Al.Mickiewicza 3030059 KrakowPoland China University of Mining and Technology BeijingD11 Xueyuan Road100083 BeijingChina

Mathematical modeling of surface deformations caused by underground mining operation is commonly carried out with use of empirical,numerical or stochastic *** of the most frequently applied model for prediction of ground deformation in many countries is Knothe *** model developed by Knothe belongs to the stochastic methods and is based on the influence *** China a prediction method named Probability Integration Method(PIF)was established by Liu Baochen and Liao Guohua based on the stochastic medium *** version of that model allows to predict ground movements caused by mining operation in extremely complex technical and geological *** model is commonly applied for coal,metal ore and salt *** article presents several modifications of the mathematical model used in China and *** model is very widespread in the world,therefore the generalizations proposed in the article can be implemented for the purposes of prediction surface deformations for various types of deposits in many *** presented generalizations were then tested on specific examples of coal mining,copper ore mining and rock salt *** obtained results indicate high efficiency of methods based on the influence function in complex geological and mining conditions.

关键词： Mining operation Modeling of surface deformations Stochastic models Probability integration method Influence function Salt hard coal mining copper ore mining

Preparation, characterization and antibacterial properties of cobalt doped titania nanomaterials

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Chinese Journal of Chemical Engineering 2020年第5期28卷 1474-1482页

作者： dai Shi He Yang Xiangxin Xue Institute of Resources and Environment School of MetallurgyNortheastern UniversityShenyang 110819China The Faculty of Mechanical Engineering Shenyang Polytechnic CollegeShenyang 110045China

Cobalt-doped titania(Co-TiO2)nanomaterials were synthesized by the sol–gel method at different calcination *** Escherichia coli(a),Staphylococcus aureus(b)and Candida albicans(c)as target strains,the antibacterial activity in visible light of the nanomaterials were ***-TiO2 nanomaterials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV–Vis diffuse reflectance spectroscopy(DRS),Fourier transform infrared spectrum(FT-IR)and X-ray photoelectron spectroscopy(XPS).The Co ions in the Co-TiO2 nanomaterial exist in the form of CoTiO3 *** antibacterial properties of Co-TiO2 nanomaterials on ***(a),***(b)and ***(c)were investigated with the oscillating flask method and the inhibition zone *** nanomaterials calcined at 600°C exhibit excellent antibacterial *** bacteriostatic rates for ***,*** and *** reached 99.5%,91.3%and 93.4%*** diameters of the antibacterial rings were up to 36 mm,37 mm,30 mm respectively,and the clarity of the ring was *** antibacterial properties of Co-TiO2 nanomaterials were compared with those of traditional silver sol,zinc oxide sol and Zn-doped TiO2 nanomaterials The mechanism of the influences of Co ions doping on the antibacterial activity of TiO2 nanomaterials was also *** doping of Co ions inhibits the particle size of the antibacterial agent and extends the photocatalytic response range,thereby improving the photocatalytic performance of the antibacterial agent.

关键词： Antibactenal activity Co-doped Visible light TiO2 CoTiO3

A distribution prior model for airplane segmentation without exact template

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Journal of Systems Engineering and Electronics 2020年第1期31卷 56-63页

作者： dai Ming ZHOU Zhiheng GUO Yongfan School of Electronics and Information Engineering South China University of Technology

In many practical applications of image segmentation problems,employing prior information can greatly improve segmentation *** paper continues to study one kind of prior information,called prior *** this research,there is no exact template of the object;instead only several samples are *** proposed method,called the parametric distribution prior model,extends our previous model by adding the training procedure to learn the prior distribution of the *** this paper establishes the energy function of the active contour model(ACM)with consideration of this parametric form of prior ***,during the process of segmenting,the template can update itself while the contour *** are performed on the airplane data *** results demonstrate the potential of the proposed method that with the information of prior distribution,the segmentation effect and speed can be both improved efficaciously.

关键词： image segmentation active contour model(ACM) prior distribution level set method

Visual perception driven collage synthesis

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Computational Visual Media 2022年第1期8卷 79-91页

作者： Zuyi Yang Qinghui dai Junsong Zhang Department of Artificial Intelligence Xiamen UniversityXiamen 361005China.

A collage is a composite artwork made from the spatial layout of multiple pictures on a canvas,collected from the Internet or user ***,usually made by skilled artists,involve a complex manual process,especially when searching for component pictures and adjusting their spatial layout to meet artistic *** this paper,we present a visual perception driven method for automatically synthesizing visually pleasing *** previous works,we focus on how to design a collage layout which not only provides easy access to the theme of the overall image,but also conforms to human visual *** achieve this goal,we formulate the generation of collages as a mapping problem:given a canvas image,first,compute a saliency map for it and a vector field for each sub-region of ***,using a divide-and-conquer strategy,generate a series of patch sets from the canvas image,where the salient map and the vector field are used to determine each patch’s size and direction ***,construct a Gestalt-based energy function to choose the most visually pleasing and orderly patch set as the final ***,using a semantic-color metric,map the picture set to the patch set to generate the final *** experimental and user study results show that this method can generate visual pleasing collages.

关键词： collage gestalt psychology saliency map layout optimization human visual perception

Material Compatibility of Hexamethyldisiloxane as Organic Rankine Cycle Working Fluids at High Temperatures

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Journal of Thermal Science 2020年第1期29卷 25-31页

作者： dai Xiaoye SHI Lin QIAN Weizhong Department of Chemical Engineering Tsinghua UniversityBeijing 100084China Department of Energy and Power Engineering Tsinghua UniversityBeijing 100084China

The organic Rankine cycle(ORC)is a promising technology for industrial waste heat recovery and renewable energy *** temperature ORCs have attracted particular interest because of their high thermal efficiencies and *** material compatibility of working fluid is a significant limitation for the working fluid selection and system design for high temperature *** work presents a method for studying the material compatibility of ORC working fluids based on the calculated conditions of the ORCs and matching of components,temperatures,and ***(MM)was chosen as the test *** experimental results show that 304 stainless steel has better compatibility with MM than copper as the material of *** rubber is not a suitable sealing material for high temperature ORCs with MM as the working fluids because of the bad *** oil has better compatibility with MM than polyol ester(POE)lubricant as the lubricant for the fluid pump.

关键词： organic Rankine cycle(ORC) material compatibility high temperatures hexamethyldisiloxane(MM)

Primary amine coupling on nanocarbon catalysts: Reaction mechanism and kinetics via fluorescence probe analysis

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Green Energy & Environment 2020年第4期5卷 453-460页

作者： Fan Li Xueya dai Wei Qi Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

Non-metallic nanocarbon materials catalyzed coupling reactions of primary amines to produce imine is an efficient,green and sustainable synthetic route,which has a wide application prospect in fine chemicals or pharmaceutical *** the present study,we show firstly the relatively high catalytic activity of graphene oxide in the reaction of oxidative coupling of benzylamine(OCB),which is even comparable with typical metal-based catalysts,indicating the great potential of nanocarbon materials in this reaction *** importantly,a novel twophoton fluorescence probe molecule(N-propyl-4-hydrazinyl-1,8-naphthalimide,NA)with special chemical structure of hydrazine functionality was *** probe NA could selectively react with aldehyde or ketone compounds,leading to the photoluminescence enhancement via inhibition of photo induced electron transfer(PET)*** synthesized NA was applied as probe in carbon catalyzed OCB system to predict the existence of reaction intermediate benzaldehyde(BA),indicating the reaction pathway of oxidation-deamination-condensation in nanocarbon catalyzed OCB *** proposed luminescence-probe strategy for revealing the kinetics and mechanism may also shed light in other reaction systems concerning the intermediates or products of ketones or aldehydes.

关键词： Nanocarbon Benzylamine coupling reaction Fluorescence probe Reaction mechanism