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Receptivity of plane Poiseuille flow to local micro-vibration disturbance on wall

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Water Science and Engineering 2015年第2期8卷 145-150页

作者： Wei-dong Cao Qi-xiang hu Bing Liu Research Center of Fluid Machinery Engineering and Technology Jiangsu University

The receptivity of plane Poiseuille flow to local single-period micro-vibration disturbances with different phases at the top and bottom walls was investigated through direct numerical simulation of three-dimensional incompressible Navier-Stokes equations. Results show that the disturbance presents a symmetrical distribution in the spanwise direction when the micro-vibration on the wall ends, and the initial disturbance velocities and spatial distribution of the disturbance structure are different at the top and bottom walls. The disturbance＇s velocity, amplitude, and high- and low-speed streaks increase with time, and the amplitude of streamwise disturbance velocity is larger than those of spanwise and vertical disturbance velocities. However, no significant Tollmien-Schlichting wave was found in the flow field. The number of disturbance vortex cores gradually increases with the disturbance area. High-speed disturbance fluid concentrates near the wall and its normal velocity largely points to the wall, while low-speed disturbance fluid largely deviates from the wall. Furthermore, the streamwise velocity profiles near the top and bottom walls both become plump because of the existence of the disturbances, and the streamwise velocity profiles show a trend of evolving into turbulent velocity profiles. The shear stress near the wall increases significantly. The local micro-vibration disturbance on the wall in plane Poiseuille flow can induce the development of a structure similar to turbulent spots.

关键词： Poiseuille flow Disturbance Velocity profile Vortex High-and low-speed streaks

RIS-Assisted Over-the-Air Federated Learning in Millimeter Wave MIMO Networks

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Journal of Communications and Information Networks 2022年第2期7卷 145-156页

作者： Lin hu Zhibin Wang Hongbin Zhu Yong Zhou School of Information Science and Technology ShanghaiTech UniversityShanghai 201210China Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 200050China

In this paper,we propose a reconfigurable intelligent surface(RIS)assisted over-the-air federated learning(FL),where multiple antennas are deployed at each edge device to enable simultaneous multidimensional model transmission over a millimeter wave(mmWave)*** conduct rigorous convergence analysis for the proposed FL system,taking into account dynamic channel fading and analog *** by the convergence analysis,we propose to jointly optimize the receive digital and analog beamforming matrices at the access point,the RIS phase-shift matrix,as well as the transmit beamforming matrices at transmitting devices to minimize the transmission *** optimization variable coupling and non-convex constraints make the formulated problem challenging to be *** this end,we develop a low-complexity Riemannian conjugate gradient(RCG)-based algorithm to solve the unit modulus constraints and decouple the optimization *** show that the proposed RCG algorithm outperforms the successive convex approximation algorithm in terms of the learning performance.

关键词： reconfigurable intelligent surface federated learning Riemannian conjugate gradient over-the-air computation

Evaluation model for service life of dam based on time-varying risk probability

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Science China(Technological Sciences) 2009年第7期52卷 1966-1973页

作者： SU huaiZhi WEN ZhiPing hu Jiang WU ZhongRu College of Water Conservancy and Hydropower Engineering of Hohai University Nanjing 210098China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing 210098China College of Computer Engineering Nanjing Institute of TechnologyNanjing 211167China

For many dam projects in China, the 50-year designed life time is coming to an end. It is urgent to study the theory and method to evaluate the dam service life. In this paper, firstly, the probability theory of fuzzy event and time-varying effect theory are used to analyze the time-variety of various risk factors in the process of dam operations. A method is proposed to quantify the above time-variety and a model to describe the fuzzy time-varying risk probability for the dam structure is also built. Secondly, the information entropy theory is used to analyze the uncertain degree relationship between the characteristic value of membership function and fuzzy risk probability, and a mathematical method is presented to calculate the time-varying risk probability accordingly. Thirdly, the relation mode between time-varying risk probability and service life is discussed. Based on this relation mode and the acceptable risk probability of dams in China, a method is put forward to evaluate and forecast the dam service life. Finally, the proposed theory and method are used to analyze one concrete dam. The dynamic variability and mutation feature of the dam risk probability are analyzed. The remaining service life of this dam is forecasted. The obtained results can provide technology support for the project management department to make treatment measures of engineering and reasonably arrange reinforce cost. The principles in this paper have wide applicability and can be used in risk analysis for slope instability and other fields.

关键词： dam service life evaluation time-varying risk probability fuzzy probability theory information entropy theory

Morphology and Molecular Phylogeny of Two Little-Known Species of Loxodes, L. kahli Dragesco & Njiné, 1971 and L. rostrum Müller, 1786(Protist, Ciliophora, Karyorelictea)

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Journal of Ocean University of China 2019年第3期18卷 643-653页

作者： WANG Lun QU Zhishuai LI Song hu Xiaozhong Institute of Evolution and Marine Biodiversity Key Laboratory of Mariculture Ministry of Education Ocean University of China

The morphology and phylogeny of two little-known species, Loxodes kahli Dragesco & Njiné, 1971 and L. rostrum Müller, 1786, isolated from freshwater muddy sediments in China, were investigated based on live features, infraciliature, and small subunit ribosomal DNA(SSU rD NA) sequence data. Loxodes kahli is distinguished from its congeners mainly by the number and arrangement of macronuclei(6-17 in one row) and the number of right somatic ciliary rows(11-26). The Chinese populations of L. kahli also exhibit differences with other populations in terms of the body size and the number of right ciliary rows. The characteristics of L. rostrum are consistent with those of previous studies except for the number of right ciliary rows(9-10). The studied species were redefined based on the new information and previous descriptions. This study also gave a brief morphological summary of the species in the genus Loxodes by an identification key. SSU rDNA sequence-based phylogenetic analyses revealed that both species are grouped with their congeners, supporting the monophyly of the genus Loxodes.

关键词： anaerobe benthic ciliate ciliature Loxodida SSU rDNA

Rapid and Efficient Assembly of Transcription Activator-Like Effector Genes by USER Cloning

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Journal of Genetics and Genomics 2014年第6期41卷 339-347页

作者： Song Wang Wei Li Shuo Wang Baoyang hu State Key Laboratory of Reproductive Biology Institute of Zoology Chinese Academy of Sciences University of the Chinese Academy of Sciences Nanjing Agricultural University

Transcription activator-like effectors （TALEs） that were related to bacteria immune system have lately been employed in a promising approach of precise gene targeting. Because of the repetitive characteristics of TALEs, existing TALE assembly methods are either very complicated, time-consuming, or too tricky to be handled in common labs. Here, we reported a rapid, efficient and easy method for TALE assembly. This method takes advantage of uracil-specific excision reagent （USER）, an enzyme that can cleave DNA constructs and create long, unique single-strand DNA overhangs. Upon USER treatment, the overhangs on each individual TALE repeat unit can be rejoined hierarchically to form pentamers in a ligation-independent manner. Eventually, three pentamers are assembled into a full TALE construct by Golden Gate cloning. TALE nucleases （TALENs） generated with this method exhibit high genome-editing activity in human cells such as HEK293FT cells. Using this method, we have successfully synthesized three TALEN pairs targeting endogenous Tetl locus, and proved that all can specifically target Tetl gene, though in various degree. Comparing to other methods of TALEN assembly, this one is much less labor intensive and fairly faster, and positive clones can be obtained at high efficiency within only two days. We thus contribute to an easier approach for effective TALENs synthesis, which may highly facilitate the wide application of TALEN technology in genome editing, especially for human cells that require precise targeting.

关键词： TAL effector TALENs USER Tetl Golden Gate cloning

Review of applying X-ray computed tomography for imaging soil-root physical and biological processes

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International Journal of Agricultural and Biological Engineering 2015年第5期8卷 1-14页

作者： Francis Kumi Mao Hanping hu Jianping Ikram Ullah Key Laboratory of Modern Agricultural Equipment and Technology Ministry of Education and Jiangsu ProvinceJiangsu UniversityZhenjiang 212013China Department of Agricultural Engineering University of Cape CoastCape CoastGhana

Root growth process in soils has long been a matter of interest to soil and plant *** the opaque nature of the soil has been a barrier to most research attempts aimed at unraveling the full root-soil *** traditional method of separating the roots from the growth media which is common practice tends to be destructive and defeats the purpose of such *** is ineffective in monitoring the interactions within the soil medium and as a result,a fast non-destructive technique is ***,with computing and technological advancements,X-ray computed tomography(CT)has been found to be capable of meeting this need by imaging the processes which are of interest to *** the past three-four decades,the applications of the technology for imaging soil-root studies have attracted the researchers’widespread interests and the future looks more *** purpose of this review is to present an overview of CT applications in imaging root-soil *** main focus is on the use of soil-root interface researches and the way forward for such non-destructive analyses.

关键词： computed tomography soil root imaging non-destructive interactions

An Operational Precipitable Water Vapor Retrieval Algorithm for Fengyun-2F/VISSR Using a Modified Three-Band Physical Split-Window Method

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Journal of Meteorological Research 2019年第2期33卷 276-288页

作者： Juyang hu Shihao TANG Hailei LIU Min MIN Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites National Satellite Meteorological Center China Meteorological Administration Key Laboratory of Atmospheric Sounding Chengdu University of Information Technology

The Visible and Infrared Spin-Scan Radiometer(VISSR) onboard the Fengyun-2(FY-2) satellite can provide valuable thermal infrared observations to help create a precipitable water vapor(PWV) product with high spatial and temporal resolutions. The current FY-2/VISSR PWV product in operation is produced by using a traditional two-band physical split-window(PSW) method, which produces low quality results under dry atmospheric conditions. Based on the sensitivity characteristics of FY-2 F/VISSR water vapor channel and two split-window channels to atmospheric water vapor, this study developed a new, robust operational PWV retrieval algorithm for FY-2 F to improve the operational precision of the current PWV product. The algorithm uses a modified three-band PSW method, which adds a scale for the water vapor channel in the improved three-band PSW method. Integrated PWV products from the radiosonde data in 2016 are used here to validate the precision of the PWV retrieved by the modified three-band and traditional two-band PSW methods. The mean bias, root mean square error(RMSE), and correlation coefficient of the PWV retrieved by the modified three-band PSW method are 0.28 mm, 4.53 mm, and 0.969, respectively. The accuracy is much better than the PWV retrieved by the two-band method, whose mean bias, RMSE, and correlation coefficient are 12.67 mm, 29.35 mm, and 0.23. Especially, in mid-or high-latitude regions, the RMSE of the PWV is improved from 10 to 2 mm by changing the inversion in the two-band method to the modified three-band PSW method. Furthermore, the modified three-band PSW results show a better consistency with the radiosonde PWV at any zonal belt and season than the two-band PSW results. This new algorithm could significantly improve the quality of the current FY-2 F/VISSR PWV product, especially at sites where the actual PWV are lower than 15 mm.

关键词： physical split-window (PSW) method precipitable water vapor (PWV) FY-2F/VISSR thermal infrared

Seasonal variability in tropical and subtropical convective and stratiform precipitation of the East Asian monsoon

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Science China Earth Sciences 2011年第10期54卷 1595-1603页

作者： hu Liang LI YaoDong SONG Yang DENG DiFei National Satellite Meteorological Center China Meteorological Administration Beijing 100081 China Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Beijing Aviation Meteorological Institute Beijing 100085 China L M. Systems Group Satellite Meteorology and Climatology Division National Oceanic andAtmospheric Administration Washington D C USA

Seasonal variations in tropical and subtropical convective and stratiform precipitation of the East Asian monsoon are analyzed using 10-year (1998-2007) Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) rain products (2A25). Datasets from the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) 24 general circulation models (GCMs) are evaluated using TRMM PR rain products in terms of their ability to simulate convective and stratiform precipitation and their deficiencies. The results show that Asian monsoon convective and stratiform precipitation increases significantly after onset of the summer monsoon, but the percentage of convective precipitation clearly decreases over tropical areas while it increases in subtropical regions. The GCMs simulate well the seasonal variation in the contribution of Asian monsoon subtropical convective precipitation to the total rainfall; however, the simulated convective precipitation amount is high while the simulated stratiform precipitation amount is low relative to TRMM measurements, especially over the Asian monsoon tropical region. There is simultaneous TRMM-observed convective and stratiform precipitation in space and time, but GCMs cannot simulate this relationship between convective and stratiform precipitation, resulting in the deficiency of stratiform precipitation simulations.

关键词： convective precipitation stratiform precipitation Asian monsoon seasonal variability

Climate and Vegetation Drivers of Terrestrial Carbon Fluxes:A Global Data Synthesis

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Advances in Atmospheric Sciences 2019年第7期36卷 679-696页

作者： Shutao CHEN Jianwen ZOU Zhenghua hu Yanyu LU Jiangsu Key Laboratory of Agricultural Meteorology Nanjing University of Information Science and TechnologyNanjing210044China College of Resources and Environmental Sciences Nanjing Agricultural UniversityNanjing210095China School of Applied Meteorology Nanjing University of Information Science and TechnologyNanjing210044China Climate Center Anhui Weather BureauHefei230031China

The terrestrial carbon(C) cycle plays an important role in global climate change, but the vegetation and environmental drivers of C fluxes are poorly understood. We established a global dataset with 1194 available data across site-years including gross primary productivity(GPP), ecosystem respiration(ER), net ecosystem productivity(NEP), and relevant environmental factors to investigate the variability in GPP, ER and NEP, as well as their covariability with climate and vegetation *** results indicated that both GPP and ER increased exponentially with the increase in mean annual temperature(MAT)for all biomes. Besides MAT, annual precipitation(AP) had a strong correlation with GPP(or ER) for non-wetland *** leaf area index(LAI) was an important factor determining C fluxes for all biomes. The variations in both GPP and ER were also associated with variations in vegetation characteristics. The model including MAT, AP and LAI explained 53%of the annual GPP variations and 48% of the annual ER variations across all biomes. The model based on MAT and LAI explained 91% of the annual GPP variations and 92.9% of the annual ER variations for the wetland sites. The effects of LAI on GPP, ER or NEP highlighted that canopy-level measurement is critical for accurately estimating ecosystem–atmosphere exchange of carbon dioxide. The present study suggests a significance of the combined effects of climate and vegetation(e.g.,LAI) drivers on C fluxes and shows that climate and LAI might influence C flux components differently in different climate regions.

关键词： net ecosystem productivity gross primary productivity ecosystem respiration controlling factors vegetation model