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Evaluating two stages of silicone-containing arylene resin oxidation via experiment and molecular simulation

Chinese Journal of Chemical Engineering 2024年第2期66卷 189-202页

作者： Jiangtao Cai Qingfu huang huan chen Tao Zhang Bo Niu Yayun Zhang Donghui long Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Key Laboratory of Special Functional Polymeric Materials and Related Technology(Ministry of Education) School of Chemical EngineeringEast China University of Science and TechnologyShanghai 200237China

Silicon-containing aryl acetylene resin(PSA)is a new type of high-temperature resistant resin with excellent oxidation resistance,whereas antioxidant reaction mechanism of PSA resin under ultra-high temperatures still remains ***,the oxidation behavior and mechanisms of PSA resin are systematically investigated combining kinetic analysis and Reax FF molecular dynamics(MD)*** analysis indicates that the oxidation process of PSA resin undergoes two main steps:oxidative mass gain and oxidative *** distributed activation energy model(DAEM)is employed for describing oxidation processes and the best-fit one is obtained using genetic algorithms and differential *** model demonstrates that the oxidative weight gain stage is dominated by two virtual reactants and the oxidative degradation stage consists of three virtual ***,the observation of MD reaction pathways indicates that oxygen oxidation of unsaturated structures occurs in the initial stage,which results in the formation of PSA resin ***,cracked pieces react with O_(2)to generate CO and other chemicals in the second *** resin matrix's great antioxidation resilience is illustrated by the formation of SiO_(2).The analysis based on MD simulations exhibits an efficient computational proof with the experiments and DAEM *** on the results,a two-stage reaction mechanism is proposed,which provides important theoretical support for the subsequent study of the oxidation behavior of silica-based resins.

关键词： PSA resin Oxidative degradation Thermogravimetric analysis DAEM reaction kinetics ReaxFF simulation

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Research on Wet Steam Spontaneous Condensing Flows Considering Phase Transition and Slip

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Journal of Thermal Science 2013年第4期22卷 320-326页

作者： Ke CUI huan-long chen Yan-ping SONG Hiroharu OYAMA School of Energy Science and Engineering Harbin Institute of Technology Mitsubishi Heavy Industries LTD

A new dual-fluid model considering phase transition and velocity slip was proposed in this paper and the Cunningham correction was used in the droplet resistance calculation. This dual-fluid model was applied to the numerical simulations of wet steam flow in a 2D LAVAL nozzle and in the White cascade respectively. The results of two simulations demonstrate that the model is reliable. Meanwhile, the spontaneous condensing flow in White cascade was analyzed and it infers that the irreversible loss caused by condensation accounts for the largest share (about 8.78% of inlet total pressure) in total pressure loss while the loss caused by velocity slip takes the smallest share (nearly 0.42%), and another part of total pressure loss caused by pneumatic factors contributes a less share than condensation, i.e. almost 3.95% of inlet total pressure.

关键词：凝结流动湿蒸汽双流体模型总压损失相变速度滑移数值模拟拉瓦尔喷嘴

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Formal Verification of Robot Forward Kinematics Based on DH Coordinate System

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Ruan Jian Xue Bao/Journal of Software 2024年第9期35卷

作者： Xie, Guo-Jun Yang, huan-huan Shi, Zheng-Pu chen, Gang College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 211106 China College of Computer Science and Technology National University of Defense Technology Changsha 410073 China

The DH coordinate system plays a vital role in analyzing robot kinematics. In the robot control system built upon the DH coordinate system, the robot structure complexity poses challenges to developing a secure control system. Depending solely on manual methods can introduce system vulnerabilities and security hazards, thereby endangering the overall safety of the robot. The formal method becomes a promising direction to design, develop, and verify hardware and software systems by deductive reasoning and code extraction. Based on this, this study designs a formal verification framework for robot forward kinematics based on the DH calibration, during which the robot kinematics theory is rigorously proven and the correctness of the control algorithm in Coq is verified to ensure the motion safety of the robot. First, it formally models the DH coordinate system, defines the transformation matrix among adjacent coordinate systems, and verifies the equivalence of this transformation matrix with the composite helical motion. Then, the forward kinematics of the robotic arm is formally defined, with its motion detachability verified. Subsequently, this study formally models the common connecting rod structures and robots in industrial robots and verifies their forward kinematics. Finally, the code extraction from Coq to OCaml is implemented, and the extracted code is analyzed and verified. © 2024 Chinese Academy of Sciences. All rights reserved.

关键词： Formal verification

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Impacts of information about COVID-19 on pig farmers'production willingness and behavior:Evidence from China

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Journal of Integrative Agriculture 2024年第4期23卷 1429-1441页

作者： huan chen Lei Mao Yuehua Zhang School of Public Affairs Zhejiang UniversityHangzhou 310058China School of Insurance Central University of Finance and EconomicsBeijing 100081China Innovation Center of Yangtze River Delta Zhejiang UniversityJiaxing 314100China

This paper examines the impacts of information about COVID-19 on pig farmers'production willingness by using endorsement experiments and follow-up surveys conducted in 2020 and 2021 in *** results show that,first,farmers were less willing to scale up production when they received information about *** information in 2020 that the second wave of COVID-19 might occur without a vaccine reduced farmers'willingness to scale up by 13.4%,while the information in 2021 that COVID-19 might continue to spread despite the introduction of vaccine reduced farmers'willingness by 4.4%.Second,farmers whose production was affected by COVID-19 were considerably less willing to scale up,given the access to COVID-19 ***,farmers'production willingness can predict their actual production behavior.

关键词： COVID-19 randomized experiment information treatment production willingness

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Enhanced properties of stone coal-based composite phase change materials for thermal energy storage

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 206-215页

作者： Baoshan Xie huan Ma Chuanchang Li Jian chen Key Laboratory of Renewable Energy Electric-Technology of Hunan Province School of Energy and Power EngineeringChangsha University of Science and TechnologyChangsha 410114China State Key Laboratory of Disaster Prevention and Reduction for Power Grid Changsha University of Science and TechnologyChangsha 410114China

Phase change materials (PCMs) can be incorporated with low-cost minerals to synthesize composites for thermal energy storage in building *** coal (SC) after vanadium extraction treatment shows potential for secondary utilization in composite *** prepared SC-based composite PCMs with SC as a matrix,stearic acid (SA) as a PCM,and expanded graphite (EG) as an *** combined roasting and acid leaching treatment of raw SC was conducted to understand the effect of vanadium extraction on promoting loading *** showed that the combined treatment of roasting at 900℃ and leaching increased the SC loading of the composite by 6.2%by improving the specific surface *** loading capacity and thermal conductivity of the composite obviously increased by 127%and 48.19%,respectively,due to the contribution of 3wt% *** data were supported by the high load of 66.69%and thermal conductivity of 0.59 W·m^(-1)·K-1of the designed *** obtained composite exhibited a phase change temperature of 52.17℃,melting latent heat of 121.5 J·g^(-1),and good chemical *** SC-based composite has prospects in building applications exploiting the secondary utilization of minerals.

关键词： thermal energy storage phase change material stone coal vanadium extraction secondary utilization

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Semi-supervised surface defect detection of wind turbine blades with YOLOv4

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Global Energy Interconnection 2024年第3期7卷 284-292页

作者： Chao huang Minghui chen long Wang Department of Computer and Communication Engineering University of Science and Technology BeijingBeijing 100083P.R.China Shunde Innovation School University of Science and Technology BeijingFoshan 528399P.R.China

Timely inspection of defects on the surfaces of wind turbine blades can effectively prevent unpredictable *** this end,this study proposes a semi-supervised object-detection network based on You Only Looking Once version 4(YOLOv4).A semi-supervised structure comprising a generative adversarial network(GAN)was designed to overcome the difficulty in obtaining sufficient samples and sample *** a GAN,the generator is realized by an encoder-decoder network,where the backbone of the encoder is YOLOv4 and the decoder comprises inverse convolutional *** features from the generator are passed to the defect detection *** several unlabeled images can significantly improve the generalization and recognition capabilities of defect-detection *** small-scale object detection capacity of the network can be improved by enhancing essential features in the feature map by adding the concurrent spatial and channel squeeze and excitation(scSE)attention module to the three parts of the YOLOv4 network.A balancing improvement was made to the loss function of YOLOv4 to overcome the imbalance problem of the defective *** results for both the single-and multi-category defect datasets show that the improved model can make good use of the features of the unlabeled *** accuracy of wind turbine blade defect detection also has a significant advantage over classical object detection algorithms,including faster R-CNN and DETR.

关键词： Defect detection Generative adversarial network scSE attention Semi-supervision Wind turbine

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Mathematics of multi-agent learning systems at the interface of game theory and artificial intelligence

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Science China(Information Sciences) 2024年第6期67卷 445-447页

作者： long WANG Feng FU Xingru chen Center for Systems and Control College of EngineeringPeking University Center for Multi-Agent Research Institute for Artificial IntelligencePeking University Department of Mathematics Dartmouth College Department of Biomedical Data Science Geisel School of Medicine at Dartmouth School of Science Beijing University of Posts and Telecommunications

Evolutionary game theory (EGT) and artificial intelligence(AI) are two fields that,at first glance,might seem distinct,but they have notable connections and *** former focuses on the evolution of behaviors (or strategies)in a population,where individuals interact with others and update their strategies based on imitation (or social learning).

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Generalized Inverses and Units in a Unitary Ring

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Acta Mathematica Sinica,English Series 2024年第4期40卷 1000-1014页

作者： Yu Kun ZHOU Jian long chen School of Mathematics Southeast UniversityNanjing 210096P.R.China

Let R be a unitary ring and a,b∈R with ab=*** find the 2/3 property of Drazin invertibility:if any two of a,b and a+b are Drazin invertible,then so is the third ***,we combine the 2/3 property of Drazin invertibility to characterize the existence of generalized inverses by means of *** applications,the need for two invertible morphisms used by You and chen to characterize the group invertibility of a sum of morphisms is reduced to that for one invertible morphism,and the existence and expression of the inverse along a product of two regular elements are obtained,which generalizes the main result of Mary and Patricio(2016)about the group inverse of a product.

关键词： Leftπ-regular element stronglyπ-regular element group inverse Drazin inverse inverse along an element

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Design and Control of an Autonomous Bat-like Perching UAV

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Journal of Bionic Engineering 2024年第3期21卷 1253-1264页

作者： long Bai Wei Wang Xiaohong chen Yuanxi Sun State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China

Perching allows small Unmanned Aerial Vehicles(UAVs)to maintain their altitude while significantly extending their flight duration and reducing ***,current research on flying habitats is poorly adapted to unstructured environments,and lacks autonomous capabilities,requiring ideal experimental environments and remote control by *** solve these problems,in this paper,we propose a bat-like UAV perching mechanism by investigating the bat upside-down perching method,which realizes double self-locking in the perching state using the ratchet and four-link dead point *** on this perching mechanism,this study proposes a control strategy for UAVs to track targets and accomplish flight perching autonomously by combining a binocular camera,single-point LiDAR,and pressure *** perching experiments were conducted for crossbar-type objects *** experimental results show that a multirotor UAV equipped with the perching mechanism and sensors can reliably achieve autonomous flight perching and re-flying off the target *** power consumption is reduced to 2.9%of the hovering state when perched on the target object.

关键词： Bio-inspired design Perching mechanism UAV Autonomous flight

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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

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