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The rate of convergence on fractional power dissipative operator on some sobolev type spaces

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Applied Mathematics(A Journal of Chinese Universities) 2021年第3期36卷 412-419页

作者： cao zhen-bin WANG Meng Department of Mathematics Zhejiang UniversityHangzhou 310027China

In[3],Chen,Deng,Ding and Fan proved that the fractional power dissipative operator is bounded on Lebesgue spaces Lp(Rn),Hardy spaces Hp(Rn)and general mixed norm spaces,which implies almost everywhere convergence of such *** this paper,we study the rate of convergence on fractional power dissipative operator on some sobolev type spaces.

关键词： convergence speed dissipative operator sobolev type spaces

Photophysics and electrochemistry relevant to photocatalytic water splitting involved at solid–electrolyte interfaces

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Journal of Energy Chemistry 2017年第2期26卷 259-269页

作者： Tatsuya Shinagawa zhen cao Luigi Cavallo Kazuhiro Takanabe King Abdullah University of Science and Technology(KAUST) KAUST Catalysis Center and Physical Sciences and Engineering Division(PSE)4700 KAUSTThuwal 23955-6900Saudi Arabia

Direct photon to chemical energy conversion using semiconductor–electrocatalyst–electrolyte interfaces has been extensively investigated for more than a half century. Many studies have focused on screening materials for efficient photocatalysis. Photocatalytic efficiency has been improved during this period but is not sufficient for industrial commercialization. Detailed elucidation on the photocatalytic water splitting process leads to consecutive six reaction steps with the fundamental parameters involved: The photocatalysis is initiated involving photophysics derived from various semiconductor properties(1: photon absorption, 2: exciton separation). The generated charge carriers need to be transferred to surfaces effectively utilizing the interfaces(3: carrier diffusion, 4: carrier transport). Consequently, electrocatalysis finishes the process by producing products on the surface(5: catalytic efficiency, 6: mass transfer of reactants and products). Successful photocatalytic water splitting requires the enhancement of efficiency at each stage. Most critically, a fundamental understanding of the interfacial phenomena is highly desired for establishing 'photocatalysis by design' concepts, where the kinetic bottleneck within a process is identified by further improving the specific properties of photocatalytic materials as opposed to blind material screening. Theoretical modeling using the identified quantitative parameters can effectively predict the theoretically attainable photon-conversion yields. This article provides an overview of the state-of-the-art theoretical understanding of interfacial problems mainly developed in our *** water splitting(especially hydrogen evolution on metal surfaces) was selected as a topic,and the photophysical and electrochemical processes that occur at semiconductor–metal, semiconductor–electrolyte and metal–electrolyte interfaces are discussed.

关键词： Photocatalysis Interface Water splitting Modeling Electrocatalysis Hydrogen evolution

Physical activity among Chinese school-aged children:National prevalence estimates from the 2016 Physical Activity and Fitness in China The Youth Study

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Journal of Sport and Health Science 2017年第4期6卷 388-394页

作者： Xiang Fan zhen-Bo cao Department of Physical Education Shanghai Jiao Tong University Shanghai 200240 China Shanghai Research Center for Physical Fitness and Health of Children and Adolescents Shanghai University of Sport Shanghai 200438 China School of Kinesiology Shanghai University of Sport Shanghai 200438 China

Purpose: This study was to present national estimates of participating in moderate-to-vigorous physical activity(MVPA) and adherence to the recommendations of 60 min/day of MVPA among Chinese school-aged children and to assess demographic differences in ***: Cross-sectional analyses of data from the 2016 Physical Activity and Fitness in China—The Youth Study. Participants were 90,712 primary, junior middle, and junior high school children(boy: 47%; girl: 53%), recruited from 1204 rural and urban schools across 32 administrative provinces and regions in the Mainland of China. Main outcomes were(a) average MVPA minutes per day in the previous 7 days by self-reports and(b) percentage meeting MVPA ***: Average MVPA time was 45.4 min/day, with boys having more MVPA(47.2 min/day) than girls(43.7 min/day) overall and across the 3 school grade categories. About 30% of participants met MVPA recommendations, with a higher percentage of boys(32%) than girls(28%) overall and across the 3 grades categories. Urban school children outperformed rural children in terms of MVPA time. Overall, boys were more likely to meet MVPA recommendations(adjusted odds ratio(a OR) = 1.19, 95% confidence interval(CI): 1.16–1.22) compared with girls; children in higher grades(junior middle(a OR = 0.92, 95%CI: 0.87–0.98) and junior high(a OR = 0.59, 95%CI: 0.53–0.66)) were less likely to meet recommendations compared with primary school children. The odds of meeting recommendations did not differ between urban and rural children(p = 0.07),but urban boys were found to be more likely to meet recommendations compared with rural boys(a OR = 1.14, 95%CI: 1.06–1.19).Conclusion: Overall, the average MVPA minutes per day among Chinese school-aged children is low, and less than one-third of them meet MVPA recommendations. These results were most evident among junior middle and junior high school children and those living rural areas.

关键词： Children and adolescents Exercise Moderate-to-vigorous physical activity Sedentary behavior

A Feedback Correction De-noising Algorithm Based on the Wavelet Coefficients

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Chinese Journal of Electronics 2014年第3期23卷 516-520页

作者： LI Ning cao zhen DENG Zhongliang School of Electronic Engineering Beijing University of Posts and Telecommunications

The localization of satellite interference sources under the condition of low SNR has been a hot research topic at current, where the signal de-noising is important in the following positioning work. With the help of the wavelet analysis theory, this paper proposes a denoising algorithm based on the wavelet coefficients in low SNR. After correcting and reconstructing the signal by the correction coefficients, we could obtain the SNR and Root mean square error(RMSE), and then we could correct the signal for the second time. The simulation results show that this de-noising algorithm can effectively remove the noise of the signal in low SNR, which would have a good effect on the estimation of time delay parameter in the localization of satellite interference sources.

关键词： Signal processing Feedback correction algorithm Wavelet coefficients decomposition De-noising Interference sources localization

Generalized Dirichlet Normal Ordering in Open Bosonic Strings

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Communications in Theoretical Physics 2009年第1期51卷 110-114页

作者： cao zhen-Bin DUAN Yi-Shi Institute of Theoretical Physics Lanzhou University Lanzhou 730000 China

Generally, open string boundary conditions play a nontrivial role in string theory. For example, in the presence of an antisymmetric tensor background field, they will lead the spacetime coordinates noncommutative. In this paper, we mainly discuss how to build up a generalized Dirichlet normal ordered product of open bosonic string embedding operators that satisfies both the equations of motion and the generalized Dirichlet boundary conditions at the quantum level in the presence of an antisymmetric background field, as the generalized Neumann case has already been discussed in the literature. Further, we also give a brief check of the consistency of the theory under the newly introduced normal ordering.

关键词： boundary conditions normal ordering

Time-decay Estimates for Keller-Segel System

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Acta Mathematica Sinica,English Series 2021年第4期37卷 666-674页

作者： zhen Bin cao Xiao Feng LIU Meng WANG School of Mathematical Sciences Zhejiang UniversityHangzhou 310027P.R.China College of Science Institute for Nonlinear SciencesDonghua UniversityShanghai 201620P.R.China

For the Cauchy problem to Keller–Segel system,we show well-posedness and time-decay estimates in the critical scaling-invariant Besov spaces by using Littlewood–Paley analysis together with the decay estimates of he... 详细信息

关键词： Chemotaxis parabolic system global solutions long time asymptotic behavior

In situ decomposition of metal-organic frameworks into ultrathin nanosheets for the oxygen evolution reaction

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Nano Research 2016年第6期9卷 1856-1865页

作者： Kai He zhen cao Ruirui Liu Ya Miao Yi Ding Key Laboratory of Colloid and Interface Chemistry of State Education Ministry School of Chemistry and Chemical Engineering Shandong University Jinan 250100 China Tianjin Key Laboratory of Advanced Functional Porous Materials School of Materials Science and Engineering Tianjin University of Technology Tianjin 300384 China

The oxygen evolution reaction （OER） is a pivotal process for water-splitting and many other energy technologies involving oxygen electrodes. Herein, a new synthesis strategy is proposed to prepare OER catalysts based on a simple yet flexible in situ decomposition of Co-based acetate hydroxide metal-organic frameworks （MOFs）. This process allows straightforward fabrication of various 2D hydroxide ultrathin nanosheets （UNSs） with excellent component controllability. The as-obtained Co-based hydroxide UNSs demonstrate superior catalytic activity for the OER due to the exposure of numerous active sites. In particular, the CoNi hydroxide UNSs exhibit low overpotentials （r/） of 324 and 372 mV at current densities of 10 and 100 mA-cm-2, respectively; a large turnover frequency （TOF） of 0.16 s-~ at T/= 380 mV; and a small Tafel slope of 33 ***-~ in an alkaline environment. Importantly, these values are superior to those of the state-of-the- art IrO2 commercial electrocatalyst. This facile strategy enables the exploration of more efficient and economic OER electrocatalysts with various constituents and opens a promising avenue for large-scale fabrication of functional nanocatalysts for use in clean ener~：v technologies.

关键词： oxygen evolution reaction metal-organic frameworks(MOFs) in situ decomposition ultrathin nanosheets electrocatalyst

The long-term optical behavior of BL Lac object S5 0716+714

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Science China(Physics,Mechanics & Astronomy) 2010年第7期53卷 1370-1374页

作者： ZHANG BingKai DAI BenZhong ZHANG Li cao zhen Department of Physics Fuyang Normal CollegeFuyang 236041China Department of Physics Yunnan UniversityKunming 650091China Key Laboratory of Particle and Astrophysics Institute of High Energy PhysicsCASBeijing 100049China

BL Lac object S5 0716+714 is a well-studied *** this paper,the available optical(BVRI) data of this source are compiled,and the B-,V-,R-and I-band light curves are *** of them is analyzed by means of the discrete correlation function(DCF) method,the structure function(SF) method and the z-transformed discrete correlation function(ZDCF) *** results imply that there is a possible periodic variation of 1211 days in each passband light *** source varies violently and complicatedly,and exhibits a brightening trend in the light curves.

关键词： BL Lacertae objects S50716+714 optical behavior

Characteristics of array of distributed synthetic jets and effect on turbulent boundary layer

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Acta Mechanica Sinica 2020年第6期36卷 1171-1190,I0001页

作者： Lianshan Lu Dong Li zhenghong Gao zhen cao Yu Bai Jie zheng School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China

An array of distributed round synthetic jets was used to control a fully developed turbulent boundary *** study focused on the related skin friction drag reduction and mechanisms *** control effects were analyzed by measuring the streamwise velocities using a hot-wire anemometer downstream of the array.A reduction in the skin friction was observed both in the regions downstream of the orifices and in the regions between two adjacent orifices.A statistical analysis with the variable-interval time-averaging(VITA)technique demonstrated a weakened bursting intensity with synthetic jet in the near-wall *** streamwise vortices were lifted by the upwash effect caused by synthetic jet and induced less low-speed *** control mechanism acted in a way to suppress the dynamic interaction between the streamwise vortices and low-speed streaks and to attenuate the turbulence production in the near-wall *** forcing frequency was found to be a more relevant parameter when synthetic jet was applied in turbulent boundary layer flow control.A higher forcing frequency induced a higher reduction in the skin *** power spectral density and autocorrelation of the fluctuating velocities showed that the synthetic jets gradually decayed in the streamwise direction,having an effect as far as 34.5 times the displacement thickness that was on the trailing edge of the distributed synthetic jets array.

关键词： Distributed synthetic jets Flow control Turbulent boundary layer Skin friction drag reduction Hot-wire