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Influence of Bottom Inclination on the Flow Structure in a Rotating Convective Layer

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Fluid Dynamics & Materials Processing 2024年第4期20卷 739-748页

作者： Andrei Vasiliev Andrei Sukhanovskii Elena Popova laboratory of Turbulence Institute of Continuous Media Mechanics UB RASPerm614013Russia

The formation of convective flows in a rotating cylindrical layer with an inclined bottom and free surface is *** is driven by localized cooling at the center of the upper free surface and by rim heating at the bottom near the *** horizontal temperature difference in a rotating layer leads to the formation of a convective flow with a complex *** mean meridional circulation,consisting of three cells,provides a strongly non-uniform differential *** a result of the instability of the main cyclonic zonal flow,the train of baroclinic waves appears in the upper *** baroclinic waves provide most of the heat transfer in the middle radii and are responsible for strong temperature and velocity *** is shown that the inclination of the bottom is a crucial factor for the structure of the convective cells and the dynamics of the baroclinic *** increase in the inclination angle leads to a significant increase in the energy of the *** obtained results may be important for heat and mass transfer in various geophysical and industrial systems,including transport of various additives and impurities in rotating crucibles,and crystallization processes.

关键词： laboratory modeling global atmospheric circulation baroclinic waves beta-effect

Design and Implementation of a Time Synchronization Method for UOWC Networks

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Journal of communications and Information Networks 2024年第1期9卷 56-63页

作者： Weijie Liu Jingyi Zhang Nuo Huang Zhengyuan Xu CAS Key laboratory of Wireless-Optical communications School of Information Science and TechnologyUniversity of Science and Technology of ChinaHefei 230027China

Underwater optical wireless communication (UOWC) technology facilitates high-speed data transmission among multiple nodes in underwater networks. Nevertheless, the absence of a common clock poses a challenge to achieving systematic and reliable access for multiple nodes within these networks. This paper presents a time synchronization method for UOWC networks to ensure the successful execution of the media access control (MAC) protocol. In this method, the node obtains timestamps by exchanging messages with the optical access point (OAP). Subsequently, the node calculates the clock drift relative to the OAP and the propagation time,ensuring that transmitted data packets can arrive approximately at the time specified by the OAP. To validate the effect of the proposed method, an experimental UOWC prototype, including the OAP and nodes, is implemented using field programmable gate array (FPGA). The experimental results demonstrate that the maximum difference between the actual arrival times of two data packets that are expected to reach the OAP simultaneously according to the MAC protocol meets the requirements of the quasi-synchronous code division multiple access (QS-CDMA) system, thereby substantiating the effectiveness of this synchronization method.

关键词： UOWC time synchronization MAC FPGA QS-CDMA

Optical edge-to-screw singularity state conversions

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Photonics Research 2024年第8期12卷 1689-1695页

作者： HAOLIN LIN JUNHUI JIA GUOHUA LIU YANWEN HU ZHEN LI ZHENQIANG CHEN SHENHE FU Department of Optoelectronic Engineering Jinan University Guangdong Provincial Key laboratory of Optical Fiber Sensing and communications Guangdong Provincial Engineering Research Center of Crystal and Laser Technology

Optical singularity states, which significantly affect propagation properties of light in free space or optical medium, can be geometrically classified into screw and edge types. These different types of singularity states do not exhibit direct connection, being decoupled from each other in the absence of external *** we demonstrate a novel optical process in which a higher-order edge singularity state initially nested in the propagating Gaussian light field gradually involves into a screw singularity with a new-born topological charge determined by order of the edge state. The considered edge state comprises an equal superposition of oppositely charged vortex and antivortex modes. We theoretically and experimentally realize this edge-to-screw conversion process by introducing intrinsic vortex–antivortex interaction. We also present a geometrical representation for mapping this dynamical process, based on the higher-order orbital Poincaré sphere. Within this framework, the edge-to-screw conversion is explained by a mapping of state evolution from the equator to the north or south pole of the Poincaré sphere. Our demonstration provides a novel approach for manipulating singularity state by the intrinsic vortex–antivortex interactions. The presented phenomenon can be also generalized to other wave systems such as matter wave, water wave, and acoustic wave.

关键词： Bose Einstein condensates Light beams Light propagation Optical media Optical vortices Structured light

Strategies of selective electroreduction of aqueous nitrate to N_(2) in chloride-free system:A critical review

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Green Energy & Environment 2024年第2期9卷 198-216页

作者： Fukuan Li Weizhe Zhang Peng Zhang Ao Gong Kexun Li College of Environmental Science and Engineering Nankai UniversityTianjin300350China MOE Key laboratory of Pollution Processes and Environmental Criteria Tianjin Key Laboratory of Environmental Remediation and Pollution ControlTianjin Key Laboratory of Environmental Technology for Complex Trans-Media PollutionNankai UniversityTianjin300350China

Electroreduction of nitrate has been gaining wide attention in recent years owing to it's beneficial for converting nitrate into benign N_(2) from the perspective of electrocatalytic denitrification or into value-added ammonia from the perspective of electrocatalytic NH_(3) *** reason of the undesired formation of ammonia is dominant during electroreduction of nitrate-containing wastewater,chloride has been widely used to improve N_(2) ***,selective electroreduction of nitrate to N2 gas in chloride-containing system poses several *** this review,we focus on the key strategies for efficiently enhancing N_(2) selectivity of electroreduction of nitrate in chloride-free system,including optimal selection of elements,combining an active metal catalyst with another metal,manipulating the crystalline morphology and facet orientation,constructing core–shell structure catalysts,*** summarizing the strategies,four possible reaction pathways of electro-reduction of nitrate to N_(2) are ***,this review attempts to provide practical strategies for enhancing N2 selectivity without the aid of electrochlorination and highlight directions for future research for designing appropriate electrocatalyst for final electrocatalytic denitrifi-cation.

关键词： Nitrate Chloride Electroreduction Selectivity Nitrogen

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A Novel Multi-Stream Fusion Network for Underwater Image Enhancement

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China communications 2024年第2期21卷 166-182页

作者： Guijin Tang Lian Duan Haitao Zhao Feng Liu Jiangsu Key laboratory of Image Processing and Image Communication Nanjing University of Posts and TelecommunicationsNanjing 210003China Jiangsu Key laboratory of Wireless communications Nanjing University of Posts and TelecommunicationsNanjing 210003China

Due to the selective absorption of light and the existence of a large number of floating media in sea water, underwater images often suffer from color casts and detail blurs. It is therefore necessary to perform color correction and detail restoration. However,the existing enhancement algorithms cannot achieve the desired results. In order to solve the above problems, this paper proposes a multi-stream feature fusion network. First, an underwater image is preprocessed to obtain potential information from the illumination stream, color stream and structure stream by histogram equalization with contrast limitation, gamma correction and white balance, respectively. Next, these three streams and the original raw stream are sent to the residual blocks to extract the features. The features will be subsequently fused. It can enhance feature representation in underwater images. In the meantime, a composite loss function including three terms is used to ensure the quality of the enhanced image from the three aspects of color balance, structure preservation and image smoothness. Therefore, the enhanced image is more in line with human visual ***, the effectiveness of the proposed method is verified by comparison experiments with many stateof-the-art underwater image enhancement algorithms. Experimental results show that the proposed method provides superior results over them in terms of MSE,PSNR, SSIM, UIQM and UCIQE, and the enhanced images are more similar to their ground truth images.

关键词： image enhancement multi-stream fusion underwater image

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Cobalt-Catalyzed Switchable[4+1]and[4+1+1]Spirocyclization of Aromatic Amides with 2-Diazo-1H-indene-1,3(2H)-dione:Access to Spiro Indene-2,1'-isoindolinones and Spiro Isochroman-3,1'-isoindolinones

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Chinese Journal of Chemistry 2024年第4期42卷 363-369页

作者： Bin Li Mengmeng Xie Jingyu Li Nana Shen Xinying Zhang Xuesen Fan State Key laboratory of Antiviral Drugs Pingyuan LaboratoryKey Laboratory of Green Chemical Media and ReactionsKey Laboratory for Yellow River and Huai River Water Environmental Pollution ControlMinistry of EducationSchool of EnvironmentSchool of Chemistry and Chemical EngineeringHenan Normal UniversityXinxiangHenan453007 China

Herein,we report a condition-controlled divergent synthesis of spiro indene-2,1'-isoindolinones and spiro isochroman-3,1'-isoindolinones through cobalt-catalyzed formal[4+1]and[4+1+1]spirocyclization of aromatic amides with 2-diazo-1H-indene-1,3(2H)-*** the reaction is carried out under air in ethyl acetate,spiro indene-2,1'-isoindolinones are formed through Co(II)-catalyzed C—H/N—H[4+1]*** the reaction is run under O2 in CH3CN,on the other hand,spiro isochroman-3,1'-isoindolinones are generated through Baeyer-Villiger oxidation of the in situ formed spiro indene-2,1'-isoindolinones with O2 as a cheaper and environmental-friendly oxygen *** general,these protocols have advantages such as using non-precious and earth-abundant metal catalyst,no extra additive,high efficiency and regioselectivity.A gram-scale synthesis and the removal of the directing group further highlight its utility.

关键词： Spiro indene-2,1'-isoindolinones Spiro isochroman-3,1'-isoindolinones 3d Transition metals Cobalt-catalyzed C-H Activation Switchable[4+1]and[4+1+1]spirocyclization Aromatic amides 2-Diazo-1H-indene-1,3(2H)-dione

Experimental Study of Liquid Metal Flow for the Development of a Contact-Less Control Technique

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Fluid Dynamics & Materials Processing 2024年第7期20卷 1553-1564页

作者： Aleksandr Poluyanov Ilya Kolesnichenko laboratory of Technological Hydrodynamics Institute of Continuous Media Mechanics of the Ural Branch of Russian Academy of Science(ICMM UB RAS)Perm614018Russia

The article presents an experimental study on the flow of an eutectic gallium alloy in a cylindrical cell,which is placed in an alternating magnetic *** magnetic field is generated by a coil connected to an alternating current *** coil is located at a fixed height in such a way that its plane is perpendicular to the gravity vector,which in turn is parallel to the axis of the *** position of the cylinder can vary in height with respect to the *** forced flow of the considered electrically conductive liquid is generated due to the action of the localized electromagnetic *** is assumed that under the action of the alternating magnetic field,the liquid is heated uniformly,and the resulting heat is quickly absorbed by the forced flow,so that liquid free convection can be *** experiment is carried out using an ultrasonic Doppler *** transducer is installed in the axially located cylinder sluice and the other transducer is placed in the near-wall *** to the results,a velocity profile,corresponding to a two-tori flow pattern can be hardly obtained in the low frequency range of the power ***,this is possible in the high frequency *** average velocity profiles depend essentially on the location of the coil relative to the *** spectral analysis of velocity signals shows that the amplitude of the velocity pulsations is comparable to the average value of the flow *** experimental results and their verification through comparison with numerical calculations are intended to support the development of new methods for reducing the intensity of vortex flows during the electromagnetic separation of impurities through an electromagnetic induction mechanism(able to produce an electromotive force that displaces particles).

关键词： Ultrasonic doppler velocimeter electrically conductive medium azimuthal pinch experiment in liquid metal magnetohydrodynamics

Research on the Implementation Path of Labor Education in Colleges and Universities from an International Perspective

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Journal of Contemporary Educational Research 2024年第2期8卷 230-235页

作者： Rui Zhang Sichuan University of media and communications Chengdu 611730Sichuan ProvinceChina

Universities shoulder the important mission of talent cultivation,scientific research,social service,cultural heritage and innovation,and international exchange and *** exchange and cooperation have become the fifth major function of *** on the background of the globalization era,undergraduate colleges and universities should pay more attention to the cultivation of students’intercultural communication and understanding ability while cultivating their professional skills,and take expanding students’international vision and enhancing the international competitiveness of China’s education as important *** education is an important content of the national education system,which has the comprehensive nurturing value of cultivating morality,increasing intelligence,strengthening physical fitness,and cultivating *** education institutions should further optimize the system of labor education,expand students’space and field of thinking in the process of labor education,and broaden students’international perspectives.

关键词： International perspective Colleges and universities Labor education Implementation paths

Palladium-catalyzed multi components oxy-aminofluorination and aminofluorination of gem-difluoroalkenes

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Chinese Chemical Letters 2024年第2期35卷 420-425页

作者： Fen Wu Xin Li Junbiao Chang Dachang Bai State Key laboratory of Antiviral Drugs NMPA Key Laboratory for Research and Evaluation of Innovative DrugKey Laboratory of Green Chemical Media and ReactionsMinistry of EducationSchool of Chemistry and Chemical EngineeringPingyuan LaboratoryHenan Normal UniversityXinxiang 453007China State Key laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Organofluorine compounds are widely used in the realm of drug discovery and material ***,we developed palladium catalyzed intermolecular aminofluorination and oxy-aminofluorination of gem‑difluoroalkenes with N-fluorobenzenesulfonimide(NFSI),in which NFSI was used as the nitrogen source and *** reaction provides an efficient and straightforward synthesis route of a series ofα-trifluoromethyl benzylic ***,three/four components oxy-aminofluorination processes were realized to giveα-trifluoromethyl benzylic ether with a terminal amino group,which proceed through C(sp^(3))-O bond cleavage of easily available ether and simultaneous introduced a fluorine,an amino and an oxy substituent in one pot with excellent *** divergent reactivity not only included the incorporation of one ether molecular,but also much more challenged two ether insertion with excellent selectivity through succession C(sp^(3))-O bonds *** protocol allows for concise synthesis of high value amines with fluoroalkyl-substituents and selectively transformation of easily available ethers by high-valent palladium catalysis.

关键词： Palladium Multi components Aminofluorination Oxy-aminofluorination C(sp^(3))-O bond cleavage

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