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Experimental Study on Vortex-Induced Vibration of Rough Risers Coupling with Interference Effect in Tandem Arrangement

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China Ocean Engineering 2024年第3期38卷 394-407页

作者： HU Ze-bo LIU Zhen LI Peng GUO Hai-yan REN Xiao-hui HOU hao hao Lian-hong College of Civil Engineering and Architecture Shandong University of Science and TechnologyQingdao 266590China Qingdao Key Laboratory of Marine Civil Engineering Materials and Structures Qingdao 266590China College of Engineering Ocean University of ChinaQingdao 266100China

In order to study the response law of vortex-induced vibration(VIV)of marine risers under the combined action of roughness and interference effects,and to reveal the coupling mechanism of roughness and interference effects on the riser,a VIV experiment of rough risers in tandem arrangement was conducted in a wave−current combined *** experiment characterized the risers’roughness by arranging different specifications of attachments on the surface of the *** rough risers with different roughness and smooth risers were arranged in tandem arrangement,with the rough risers arranged *** experimental results indicate that the suppression of the attachments on the downstream risers’vibration are more significant both in the CF and IL directions as the reduced velocity *** the downstream riser,the amplitude response of rough riser is more significantly weakened compared with the smooth one at high reduced *** the upstream risers,changes in the roughness and spacing ratio have an impact on their‘lock-in’*** the roughness of downstream risers is relatively large(0.1300)and the spacing between risers is small(S/D=4.0),the reduced velocity range of‘lock-in’region in the CF direction of upstream risers is obviously expanded,and the displacement in the‘lock-in’region is severer.

关键词： marine riser vortex-induced vibration tandem arrangement roughness interference effect

Identification of crucial roles of transcription factor IhfA on high production of free fatty acids in Escherichia coli

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Synthetic and Systems Biotechnology 2024年第1期9卷 144-151页

作者： Lixia Fang Ziyi Han Xueru Feng Xueyan hao Mengxiao Liu hao Song Yingxiu Cao Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering(Ministry of Education) School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072China Frontiers Research Institute for Synthetic Biology Tianjin UniversityChina

Transcription factor engineering has unique advantages in improving the performance of microbial cell factories due to the global regulation of gene *** analyses and reverse engineering enable learning and subsequent incorporation of novel design strategies for further ***,we identify the role of the global regulator IhfA for overproduction of free fatty acids(FFAs)using CRISPRi-facilitated reverse engineering and cellular physiological *** the differentially expressed genes in the ihfAL􀀀strain,a total of 14 beneficial targets that enhance FFAs production by above 20% are identified,which involve membrane function,oxidative stress,and *** membrane-related genes,the engineered strains obtain lower cell surface hydrophobicity and increased average length of membrane lipid *** oxidative stress-related genes,the engineered strains present decreased reactive oxygen species(ROS)*** gene modulations enhance cellular robustness and save cellular resources,contributing to FFAs *** study provides novel targets and strategies for engineering microbial cell factories with improved FFAs bioproduction.

关键词： Free fatty acids CRISPRi ihfA Cell membrane ROS

FL-EASGD:Federated Learning Privacy Security Method Based on Homomorphic Encryption

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Computers, Materials & Continua 2024年第5期79卷 2361-2373页

作者： hao Sun Xiubo Chen Kaiguo Yuan Information Security Center State Key Laboratory ofNetworking and Switching TechnologyBeijing University of Posts and TelecommunicationsBeijing100876China

Federated learning ensures data privacy and security by sharing models among multiple computing nodes instead of plaintext ***,there is still a potential risk of privacy leakage,for example,attackers can obtain the original data through model inference ***,safeguarding the privacy of model parameters becomes *** proposed solution involves incorporating homomorphic encryption algorithms into the federated learning ***,the existing federated learning privacy protection scheme based on homomorphic encryption will greatly reduce the efficiency and robustness when there are performance differences between parties or abnormal *** solve the above problems,this paper proposes a privacy protection scheme named Federated Learning-Elastic Averaging Stochastic Gradient Descent(FL-EASGD)based on a fully homomorphic encryption ***,this paper introduces the homomorphic encryption algorithm into the FL-EASGD scheme to preventmodel plaintext leakage and realize privacy security in the process ofmodel ***,this paper designs a robust model aggregation algorithm by adding time variables and constraint coefficients,which ensures the accuracy of model prediction while solving performance differences such as computation speed and node anomalies such as downtime of each *** addition,the scheme in this paper preserves the independent exploration of the local model by the nodes of each party,making the model more applicable to the local data ***,experimental analysis shows that when there are abnormalities in the participants,the efficiency and accuracy of the whole protocol are not significantly affected.

关键词： Federated learning homomorphic encryption privacy security stochastic gradient descent

Optimal Assimilation of Microwave Upper-Level Sounding Data in CMA-GFS

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Advances in Atmospheric Sciences 2024年第10期41卷 2043-2060页

作者： Changjiao DONG hao HU Fuzhong WENG School of Atmospheric Physics Nanjing University of Information Science and Technology CMA Earth System Modeling and Prediction Centre (CEMC) China Meteorological Administration State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences

Various approaches have been proposed to minimize the upper-level systematic biases in global numerical weather prediction（NWP） models by using satellite upper-air sounding channels as anchors. However, since the China Meteorological Administration Global Forecast System（CMA-GFS） has a model top near 0.1 hPa（60 km）, the upper-level temperature bias may exceed 4 K near 1 hPa and further extend to 5 h Pa. In this study, channels 12–14 of the Advanced Microwave Sounding Unit A（AMSU-A） onboard five satellites of NOAA and METOP, whose weighting function peaks range from 10 to 2 h Pa are all used as anchor observations in CMA-GFS. It is shown that the new “Anchor” approach can effectively reduce the biases near the model top and their downward propagation in three-month assimilation cycles. The bias growth rate of simulated upper-level channel observations is reduced to ±0.001 Kd–1, compared to –0.03 Kd–1derived from the current dynamic correction scheme. The relatively stable bias significantly improves the upper-level analysis field and leads to better global medium-range forecasts up to 10 days with significant reductions in the temperature and geopotential forecast error above 10 hPa.

关键词： anchoring bias correction CMA-GFS satellite microwave data assimilation upper-level model bias

Highly efficient photocatalytic conversion of CO_(2) into CH_(4) over Cu single atom promoted heterojunction:The effect of uplifted d-band center

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Chinese Chemical Letters 2024年第2期35卷 484-488页

作者： hao Zhang Qian Liu Zhurui Shen School of Materials Science and Engineering Nankai UniversityTianjin 300350China

Photoreduction of CO_(2) to solar fuels has caused great interest,but suffers from low catalytic efficiency and poor ***,we designed a S-scheme heterojunction(Cu-TiO_(2)/WO_(3))with Cu single atom to significantly boost the photoreduction of CO_(2).Notably,the developed Cu-TiO_(2)/WO_(3) achieved the solardriven conversion of CO_(2) to CH_(4) with an evolution rate of 98.69μmol g^(−1) h^(−1),and the electron selectivity of CH_(4) reached 88.5%.The yield was much higher than those of pristine WO_(3),TiO_(2)/WO_(3) and Cu-TiO_(2) *** and theoretical analysis suggested that the S-scheme heterojunction accelerated charge migration and inhibited the recombination of electron-hole ***,the charge separation effect of the heterojunction meliorated the position of the *** uplifted d-band centers of Cu and Ti on Cu-TiO_(2)/WO_(3) not only improved the electron interaction between Cu single atoms and substrate-TiO_(2),accelerated the adsorption and activation of CO_(2) on the active sites of Cu single atom,but also optimized the Gibbs free energies of CH 4 formation pathway,leading to excellent selectivity toward CH_(4).This work provides new insights into the design of photocatalyst systems with high photocatalytic performance.

关键词： Cu single atom Heterojunction CO_(2)photoreduction d-band center DFT

MODIFIED SPLIT-STEP THETA METHOD FOR STOCHASTIC DIFFERENTIAL EQUATIONS DRIVEN BY FRACTIONAL BROWNIAN MOTION

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Journal of Computational Mathematics 2024年第5期42卷 1226-1245页

作者： Jingjun Zhao hao Zhou Yang Xu School of Mathematics Harbin Institute of TechnologyHarbin 150001China

For solving the stochastic differential equations driven by fractional Brownian motion,we present the modified split-step theta method by combining truncated Euler-Maruyama method with split-step theta *** the problem under a locally Lipschitz condition and a linear growth condition,we analyze the strong convergence and the exponential stability of the proposed ***,for the stochastic delay differential equations with locally Lipschitz drift condition and globally Lipschitz diffusion condition,we give the order of ***,numerical experiments are done to confirm the theoretical conclusions.

关键词： Stochastic differential equation Fractional Brownian motion Split-step theta method Strong convergence Exponential stability

Restricted Arc-Connectivity of Harary Digraphs

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Journal of the Operations Research Society of China 2024年第2期12卷 540-547页

作者： Jun-hao Zhang Ji-Xiang Meng College of Mathematics and System Science Xinjiang UniversityUrumqi 830046XinJiangChina

The h-restricted arc-connectivity of a digraph is an important parameter to measure fault-tolerance of interconnection *** paper determines that the h-restricted arc-connectivity of the Harary digraph D=G(n;1,2,.:,k)i... 详细信息

关键词： Restricted arc-connectivity λ_(h)(D) Super-λ_(h) λ_(h)-Atom λ_(h)-Superatom

IR-YOLO: Real-Time Infrared Vehicle and Pedestrian Detection

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Computers, Materials & Continua 2024年第2期78卷 2667-2687页

作者： Xiao Luo hao Zhu Zhenli Zhang Department of Electrical Engineering and Automation Jiangxi University of Science and TechnologyGanzhou341000China Jiangxi Provincial Key Laboratory of Maglev Technology Ganzhou341000China Graduate School of Information Production and SystemsWaseda UniversityKitakyushu-shiFukuoka808-0135Japan

Road traffic safety can decrease when drivers drive in a low-visibility *** application of visual perception technology to detect vehicles and pedestrians in infrared images proves to be an effective means of reducing the risk of *** tackle the challenges posed by the low recognition accuracy and the substan-tial computational burden associated with current infrared pedestrian-vehicle detection methods,an infrared pedestrian-vehicle detection method A proposal is presented,based on an enhanced version of You Only Look Once version 5(YOLOv5).First,A head specifically designed for detecting small targets has been integrated into the model to make full use of shallow feature information to enhance the accuracy in detecting small ***,the Focal Generalized Intersection over Union(GIoU)is employed as an alternative to the original loss function to address issues related to target overlap and category ***,the distribution shift convolution optimization feature extraction operator is used to alleviate the computational burden of the model without significantly compromising detection *** test results of the improved algorithm show that its average accuracy(mAP)reaches 90.1%.Specifically,the Giga Floating Point Operations Per second(GFLOPs)of the improved algorithm is only *** contrast,the improved algorithms outperformed the other algorithms on similar GFLOPs,such as YOLOv6n(11.9),YOLOv8n(8.7),YOLOv7t(13.2)and YOLOv5s(16.0).The mAPs that are 4.4%,3%,3.5%,and 1.7%greater than those of these algorithms show that the improved algorithm achieves higher accuracy in target detection tasks under similar computational resource *** the other hand,compared with other algorithms such as YOLOv8l(91.1%),YOLOv6l(89.5%),YOLOv7(90.8%),and YOLOv3(90.1%),the improved algorithm needs only 5.5%,2.3%,8.6%,and 2.3%,respectively,of the *** improved algorithm has shown significant advancements in balancing accuracy and computati

关键词： Traffic safety infrared image pedestrians and vehicles focal GIoU distributed shift convolution

How to achieve energy efficiency in buildings without compromising indoor air quality:A case study on enthalpy exchangers

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Science China(Technological Sciences) 2024年第9期67卷 2648-2658页

作者： LI hao ZHANG Tao LIU XiaoHua Department of Building Science Tsinghua UniversityBeijing 100084China

As a representative heat recovery device,the fixed-plate enthalpy exchanger possesses the advantages of high recovery effectiveness,low pressure drop,and small space ***,indoor contaminants may transfer to fresh air through the enthalpy exchanger simultaneously,causing cross-contamination ***,the cross-contamination risk of the fixed-plate enthalpy exchanger has been under-researched in previous *** a result,this study experimentally investigates the energy performance,formaldehyde and ammonia transfer rates of paper-based and membrane-based enthalpy *** results illustrate that the enthalpy recovery effectiveness of the plate exchangers ranges from 60%–85%.The formaldehyde transfer rate through the exchangers varies from 5%–23%,and the ammonia transfer rate is 0–15%.The high effectiveness and low contaminant transfer rates are conducive to the promising application of the fixed-plate enthalpy *** addition,the energy reclaimed increases with the increase of the absolute indoor-outdoor enthalpy *** formaldehyde and ammonia transfer rates and cross-contamination risk slightly decrease with increasing temperature but significantly increase with increasing ***,the experimental results demonstrate that the contaminant transfer rates through the membranebased exchanger are lower than those of the paper-based *** study provides a reference for the fixed-plate enthalpy exchanger design in practical applications.

关键词： building energy efficiency enthalpy recovery heat recovery effectiveness cross-contamination