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Total Synthesis of Laurane and Guaiane Sesquiterpenoids via Oxidative Nazarov Reaction

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Chinese Journal of Chemistry 2024年第11期42卷 1267-1274页

作者： Yuye chen Wenqing chen Zhiting Zhang Jing Xu Shenzhen Grubbs Institute and Department of Chemistry and Guangming Advanced Research Institute and Guangdong Provincial Key Laboratory of Catalysis and Shenzhen Key Laboratory of Small Molecule Drug Discovery and Synthesis Southern University of Science and TechnologyShenzhenGuangdong518055 China

As one of the most common structural motifs in natural products,cyclopentenones usually can be fabricated by Nazarov cyclization using divinyl ketones or functionalized tertiary divinyl carbinols(TDCs)as ***,straightforward method for transforming unfunctionalized TDCs to their corresponding cyclopentenones is currently ***,we wish to report the total syntheses of four structurally distinct terpenoids,namely laurane-type marine sesquiterpenoids isolaurene,debromoaplysin and aplysin,and guaiane sesquiterpenoid guaiadienone A,all using a novel synthetic method,named oxidative Nazarov cyclization,as the key *** work demonstrated our robust method is suitable for synthesizing various highly substituted cyclopentenones.

关键词： Total synthesis Synthetic methods Sesquiterpenoids Oxidative Nazarov reaction Electrocyclization Oxoammonium salt Pericyclic reaction Annulation

Neural networks-based iterative learning control consensus for periodically time-varying multi-agent systems

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Science China(Technological Sciences) 2024年第2期67卷 464-474页

作者： chen JiaXi LI JunMin chen WeiSheng GAO WeiFeng School of Mathematics and Statistics Xidian UniversityXi'an 710071China School of Aerospace Science and Technology Xidian UniversityXi'an 710071China

In this paper,the problem of adaptive iterative learning based consensus control for periodically time-varying multi-agent systems is studied,in which the dynamics of each follower are driven by nonlinearly parameterized terms with periodic *** networks and Fourier base expansions are introduced to describe the periodically time-varying dynamic *** this basis,an adaptive learning parameter with a positively convergent series term is constructed,and a distributed control protocol based on local signals between agents is designed to ensure accurate consensus of the closed-loop ***,consensus algorithm is generalized to solve the formation control ***,simulation experiments are implemented through MATLAB to demonstrate the effectiveness of the method used.

关键词： multi-agent systems adaptive iterative learning control nonlinearly parameterized dynamics Fourier series expansion neural networks

Research on the influences of motion characteristics of jetting projectile charge under water

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Defence Technology（防务技术） 2024年第3期33卷 411-425页

作者： Xing chen Yong-gang Lu Institute of Systems Engineering China Academy of Engineering PhysicsMianyang 621900SichuanChina

Shaped charge warhead is important for enhancing the damage performance of underwater *** paper used finite element analysis software and based on JPC water penetration experiments to examine the influence of liner parameters(wall thickness,material),charge aspect ratio,and stand-off distance on the movement characteristics of JPC in *** findings reveal that the head diameter of the JPC increases and experiences significant erosion after entering the water,the effective length of the JPC in water undergoes two distinct phases:a growth phase and a decrease phase,with the velocity of the JPC decaying *** the liner thickness,stand-off distance and the charge aspect ratio can improve the erosion resistance and the velocity retention capacity of the *** optimal ranges for liner thickness and stand-off distance are 0.0363D_(k) to 0.0545D_(k)(D_(k) is the charge diameter),the stand-off distance should be within 1.0D_(k).After the charge aspect ratio higher than 1.25,the charge structure exerts minimal influence the movement characteristics of the JPC in *** density plays a crucial role in the velocity decay pattern of the JPC during *** with higher densities exhibit superior velocity retention capabilities in water,with the velocity decay pattern converging if the densities are ***,copper,tantalum and tungsten liners are deemed appropriate for underwater shaped charge ***,the results will provide an important reference for the design of underwater shaped charge warhead.

关键词： JPC Movement characteristics Underwater penetration Numerical simulation

Anomaly Detection Algorithm of Power System Based on Graph Structure and Anomaly Attention

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Computers, Materials & Continua 2024年第4期79卷 493-507页

作者： Yifan Gao Jieming Zhang Zhanchen chen Xianchao chen Zhaoqing Power Supply Bureau of Guangdong Power Grid Co. Ltd.Zhaoqing526060China

In this paper, we propose a novel anomaly detection method for data centers based on a combination of graphstructure and abnormal attention mechanism. The method leverages the sensor monitoring data from targetpower substations to construct multidimensional time series. These time series are subsequently transformed intograph structures, and corresponding adjacency matrices are obtained. By incorporating the adjacency matricesand additional weights associated with the graph structure, an aggregation matrix is derived. The aggregationmatrix is then fed into a pre-trained graph convolutional neural network (GCN) to extract graph structure ***, both themultidimensional time series segments and the graph structure features are inputted into a pretrainedanomaly detectionmodel, resulting in corresponding anomaly detection results that help identify abnormaldata. The anomaly detection model consists of a multi-level encoder-decoder module, wherein each level includesa transformer encoder and decoder based on correlation differences. The attention module in the encoding layeradopts an abnormal attention module with a dual-branch structure. Experimental results demonstrate that ourproposed method significantly improves the accuracy and stability of anomaly detection.

关键词： Anomaly detection transformer graph structure

A Subdivision-Based Combined Shape and Topology Optimization in Acoustics

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Computer Modeling in Engineering & Sciences 2024年第4期139卷 847-872页

作者： Chuang Lu Leilei chen Jinling Luo Haibo chen CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei230027China College of Intelligent Construction Wuchang University of TechnologyWuhan430223China Henan International Joint Laboratory of Structural Mechanics and Computational Simulation School of Architecture and EngineeringHuanghuai UniversityZhumadian463000China Beijing Aerospace Technology Institute Beijing100074China

We propose a combined shape and topology optimization approach in this research for 3D acoustics by using the isogeometric boundary element method with subdivision *** existing structural optimization methods mainly contain shape and topology schemes,with the former changing the surface geometric profile of the structure and the latter changing thematerial distribution topology or hole topology of the *** the present acoustic performance optimization,the coordinates of the control points in the subdivision surfaces fine mesh are selected as the shape design parameters of the structure,the artificial density of the sound absorbing material covered on the structure surface is set as the topology design parameter,and the combined topology and shape optimization approach is established through the sound field analysis of the subdivision surfaces boundary element method as a *** topology and shape sensitivities of the approach are calculated using the adjoint variable method,which ensures the efficiency of the *** geometric jaggedness and material distribution discontinuities that appear in the optimization process are overcome to a certain degree by the multiresolution method and solid isotropic material with *** examples are given to validate the effectiveness of the presented optimization approach.

关键词： Subdivision surfaces boundary element method topology optimization shape optimization combined optimization

Single image defogging via multi-exposure image fusion and detail enhancement

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Journal of Safety Science and Resilience 2024年第1期5卷 37-46页

作者： Wenjing Mao Dezhi Zheng Minze chen Juqiang chen School of Information and Electronics Advanced Research Institute of Multidisciplinary ScienceBeijing Institute of TechnologyBeijing100081China Chinese Aeronautical Establishment Beijing100012China

Outdoor cameras play an important role in monitoring security and social *** a common weather phenomenon,haze can easily affect the quality of camera shooting,resulting in loss and distortion of image *** paper proposes an improved multi-exposure image fusion defogging technique based on the artificial multi-exposure image fusion(AMEF)***,the foggy image is adaptively exposed,and the fused image is subsequently obtained via multiple *** fusion weight is determined by the saturation,contrast,and ***,the image fused by a multi-scale Laplacian algorithm is enhanced with simple adaptive details to obtain a clearer defogging *** is subjectively and objectively verified that this algorithm can obtain more image details and distinct picture colors without a priori information,effectively improving the defogging ability.

关键词： Image defogging Multi-scale fusion Laplacian pyramid Adaptive detail enhancement

Integrating phosphorus management and cropping technology for sustainable maize production

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Journal of Integrative Agriculture 2024年第4期23卷 1369-1380页

作者： Haiqing Gong Yue Xiang Jiechen Wu Laichao Luo Xiaohui chen Xiaoqiang Jiao chen chen State Key Laboratory of Nutrient Use and Management College of Resources and Environmental SciencesCollege of Resources and Environmental SciencesChina Agricultural UniversityBeijing 100193China Department of Sustainable Development Environmental Science and Engineering(SEED)KTH Royal Institute of TechnologyStockholm SE-10044Sweden Anhui Province Key Lab of Farmland Ecological Conservation and Pollution Prevention School of Resources and EnvironmentAnhui Agricultural UniversityHefei 230036China Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering National Observations and Research Station for Wetland Ecosystems of the Yangtze EstuaryInstitute of Biodiversity Science and Institute of Eco-ChongmingCollege of Life SciencesFudan UniversityShanghai 200438China

Achieving high maize yields and efficient phosphorus(P)use with limited environmental impacts is one of the greatest challenges in sustainable maize *** plant density is considered an effective approach for achieving high maize ***,the low mobility of P in soils and the scarcity of natural P resources have hindered the development of methods that can simultaneously optimize P use and mitigate the P-related environmental footprint at high plant *** this study,meta-analysis and substance flow analysis were conducted to evaluate the effects of different types of mineral P fertilizer on maize yield at varying plant densities and assess the flow of P from rock phosphate mining to P fertilizer use for maize production in China.A significantly higher yield was obtained at higher plant densities than at lower plant *** application of single superphosphate,triple super-phosphate,and calcium magnesium phosphate at high plant densities resulted in higher yields and a smaller environmental footprint than the application of diammonium phosphate and monoammonium *** scenario analyses suggest that combining the optimal P type and application rate with a high plant density could increase maize yield by 22%.Further,the P resource use efficiency throughout the P supply chain increased by 39%,whereas the P-related environmental footprint decreased by 33%.Thus,simultaneously optimizing the P type and application rate at high plant densities achieved multiple objectives during maize production,indicating that combining P management with cropping techniques is a practical approach to sustainable maize *** findings offer strategic,synergistic options for achieving sustainable agricultural development.

关键词： maize plant density mineral phosphorus fertilizer meta-analysis substance flow analysis

Dynamic changes in physicochemical property,biogenic amines content and microbial diversity during the fermentation of Sanchuan ham

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Food Science and Human Wellness 2024年第1期13卷 506-516页

作者： Zhongai chen Hong chen Huan Du Cong chen Kaixiang Lu Qiaoli Xue Yongjin Hu College of Food Science and Technology Yunnan Agricultural UniversityKunming 650000China Institute of Food Processing Guizhou Academy of Agricultural SciencesGuiyang 550006China Editorial Department of Journal of Yunnan Agricultural University Yunnan Agricultural UniversityKunming 650000China

Sanchuan ham is appreciated in Yunnan Province,China,for its characteristic flavor and taste,while the microbial community structure and biogenic amines content remain unclear during fermentation *** this study,we explored the physicochemical property,biogenic amines concentration and microbial diversity of external and internal Sanchuan ham by high-throughput sequencing during the processing of Sanchuan *** showed that the nitrite remained at a stable level of 0.15 mg/kg which was significantly lower than the national health standard safety level of 20 mg/*** addition,compared with fresh hams,the content of total free amino acids in ripe Sanchuan ham has grown 14 folds;sour and bitter were the main tastes of Sanchuan ***,the concentration of cadaverine was the highest of all biogenic amines during the entire fermentation *** the bacterial phyla level,Firmicutes and Actinobacteria were the two main phyla,while at the genus level,Staphylococcus was a significant strain throughout the whole ***,the dry stage has a great impact on the succession change of microbial community ***,the change trends and composition of bacteria in the interior have slight discrepancies with those of the exterior of Sanchuan ham.

关键词： Sanchuan ham Nitrite cont ent Free amino acids Cadaverine Staphylococcus

Tetrathiafulvalene esters with high redox potentials and improved solubilities for non-aqueous redox flow battery applications

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Green Energy & Environment 2024年第5期9卷 899-908页

作者： Weikang Hu Jiaqi Xu Nanjie chen Zongcai Deng Yuekun Lai Dongyang chen College of Materials Science and Engineering Fuzhou UniversityFuzhou350116China College of Chemical Engineering Fuzhou UniversityFuzhou350116China

The exploitation of high performance redox-active substances is critically important for the development of non-aqueous redoxﬂow ***,three tetrathiofulvalene(TTF)derivatives with different substitution groups,namely TTF diethyl ester(TTFDE),TTF tetramethyl ester(TTFTM),and TTF tetraethyl ester(TTFTE),are prepared and their energy storage properties are *** has been found that the redox potential and solubility of these TTF derivatives in conventional carbonate electrolytes increases with the number of ester *** battery with a catholyte of 0.2 mol L^(-1) of TTFTE delivers a speciﬁc capacity of more than 10 Ah L^(-1) at the current density of 0.5 C with two discharge voltage platforms locating at as high as 3.85 and 3.60 V ***/Liþ.Its capacity retention can be improved from 2.34 Ah L^(-1) to 3.60 Ah L^(-1) after 100 cycles by the use of an anion exchange membrane to block the crossover of TTF *** excellent cycling stability of the TIF esters is supported by their well-delocalized electrons,as revealed by the density function theory ***,the introduction of more and larger electron-withdrawing groups is a promising strategy to simultaneously increase the redox-potential and solubility of redox-active ma-terials for non-aqueous redoxﬂow batteries.

关键词： Non-aqueous redox flow batteries Tetrathiofulvarene Redox potential Solubility Substituent effect