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Three-dimensional finite element simulation and reconstruction of jointed rock models using CT scanning and photogrammetry

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1348-1361页

作者： Yingxian Lang zhengzhao Liang Zhuo Dong State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian116024China School of Energy Science and Engineering Henan Polytechnic UniversityJiaozuo454003China

The geometry of joints has a significant influence on the mechanical properties of *** simplify the curved joint shapes in rocks,the joint shape is usually treated as straight lines or planes in most laboratory experiments and numerical *** this study,the computerized tomography (CT) scanning and photogrammetry were employed to obtain the internal and surface joint structures of a limestone sample,*** describe the joint geometry,the edge detection algorithms and a three-dimensional (3D) matrix mapping method were applied to reconstruct CT-based and photogrammetry-based jointed rock *** comparison tests,the numerical uniaxial compression tests were conducted on an intact rock sample and a sample with a joint simplified to a plane using the parallel computing *** results indicate that the mechanical characteristics and failure process of jointed rocks are significantly affected by the geometry of *** presence of joints reduces the uniaxial compressive strength (UCS),elastic modulus,and released acoustic emission (AE) energy of rocks by 37%–67%,21%–24%,and 52%–90%,*** to the simplified joint sample,the proposed photogrammetry-based numerical model makes the most of the limited geometry information of *** UCS,accumulative released AE energy,and elastic modulus of the photogrammetry-based sample were found to be very close to those of the CT-based *** UCS value of the simplified joint sample (i.e.38.5 MPa) is much lower than that of the CT-based sample (i.e.72.3 MPa).Additionally,the accumulative released AE energy observed in the simplified joint sample is 3.899 times lower than that observed in the CT-based *** scanning provides a reliable means to visualize the joints in rocks,which can be used to verify the reliability of photogrammetry *** application of the photogrammetry-based sample enables detailed analysis for estimating the mechanical properties of jointed rocks.

关键词： X-ray computerized tomography(CT)scanning Photogrammetry Parallel computing Numerical simulation Uniaxial compression test Digital image processing

Unusual Single Electron Transfer Reactions between Alkenes and Iodine Electrophiles

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Chinese Journal of Chemistry 2024年第5期42卷 471-477页

作者： zhengzhao Lou Jingyu Hu Chuanfa Ni Xiu Wang Jinbo Hu Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences345 Ling Ling RoadShanghai200032 China School of Physical Science and Technology ShanghaiTech University100 Haike RoadShanghai201210 China

The electrophilic addition to an alkene with an electrophile has been widely studied and applied in organic *** organic chemistry textbook describes the classical reaction between an alkene and an iodine electrophile(such as elemental iodine and N-iodosuccinimide(NIS))as a typical ionic reaction,in which an iodonium ion is formed and then attacked by a ***,in this article,we report a new and unusual reaction mode between an alkene and NIS;that is,a single electron transfer(SET)process occurs between these two reactants by forming an electron-donor acceptor *** only does this unusual single electron transfer reaction between an alkene and NIS add fundamentally important knowledge to organic chemistry,it also provides a valuable synthetic method as the new SET reaction mode with opposite regioselectivity as compared with the traditional ionic mode.

关键词： Electrophilic addition Radical ions Reaction mechanisms Alkenes Fluorine

Vibration properties of Paulownia wood for Ruan sound quality using machine learning methods

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JOURNAL OF FORESTRY RESEARCH 2024年第1期35卷 1-7页

作者： yang, yang Harbin Univ Coll Art & Design Harbin 150076 Peoples R China Northeast Forestry Univ Coll Mech & Elect Engn Harbin 150040 Peoples R China

As an important material for manufacturing resonant components of musical instruments, Paulownia has an important influence on the sound quality of Ruan. In this paper, a model for evaluating the sound quality of Ruan based on the vibration characteristics of wood is developed using machine learning methods. Generally, the selection of materials for Ruan manufacturing relies primarily on manually weighing, observing, striking, and listening by the instrument technician. Deficiencies in scientific theory have hindered the quality of the finished Ruan. In this study, nine Ruans were manufactured, and a prediction model of Ruan sound quality was proposed based on the raw material information of Ruans. Out of a total of 180 data sets, 145 and 45 sets were chosen for training and validation, respectively. In this paper, typical correlation analysis was used to determine the correlation between two single indicators in two adjacent pairwise combinations of the measured objects in each stage of the production process in Ruan. The vibration characteristics of the wood were tested, and a model for predicting the evaluation of Ruan's acoustic qualities was developed by measuring the vibration characteristics of the resonating plate material. The acoustic quality of the Ruan sound board wood was evaluated and predicted using machine learning model generalized regression neural network. The results show that the prediction of Ruan sound quality can be achieved using Matlab simulation based on the vibration characteristics of the soundboard wood. When the model-predicted values were compared with the traditional predicted results, it was found that the generalized regression neural network had good performance, achieving an accuracy of 93.8% which was highly consistent with the experimental results. It was concluded that the model can accurately predict the acoustic quality of the Ruan based on the vibration performance of the soundboards.

关键词： Sound quality Wood vibration performance Paulownia wood Machine learning methods YOUNGS MODULUS INTERNAL-FRICTION PREDICTION

Fresh-Keeping Decision and Coordination of Fresh Agricultural Product Supply Chain Considering Carbon Cap-and-Trade under Different Dominance

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Journal of Systems Science and Systems Engineering 2024年第1期33卷 30-51页

作者： yang yang Guanxin Yao China Institute for Agricultural Equipment Industrial Development Jiangsu UniversityZhenjiang212013China Jiangsu Modern Logistics Research Base Yangzhou UniversityYangzhou225009China

In the context of low carbon,this paper discussed the impact of the carbon cap-and-trade policy on the fresh-keeping decision-making of two-echelon fresh agricultural product supply chains under different dominance,and designed cost-sharing contracts to coordinate the supply chain of fresh agricultural products dominated by suppliers and retailers *** results showed that:dominance has no effect on the fresh-keeping decision and total revenue of fresh agricultural product supply chain,but it affects the internal income distribution,and dominance does not always bring more benefits;the implementation of carbon cap-and-trade reduces the fresh-keeping decision-making of fresh agricultural products supply chain and reduces the free-rider income of followers;the role of higher carbon trading price is twofold,which not only brings about the speculation of leading enterprises,but also promotes the application of low-carbon technologies;consumers’high preference for freshness,low-cost and high-efficiency low-carbon technology are all conducive to improving the fresh-keeping efforts and benefits of the supply chain;cost-sharing contracts can coordinate the supply chain of fresh agricultural products.

关键词： Dominant power carbon cap-and-trade policy fresh agricultural product supply chain fresh-keeping decision-making

Overview of radar detection methods for low altitude targets in marine environments

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Journal of Systems Engineering and Electronics 2024年第1期35卷 1-13页

作者： yang Yong yang Boyu School of Electronic Science National University of Defense TechnologyChangsha 410073China

In this paper,a comprehensive overview of radar detection methods for low-altitude targets in maritime environments is presented,focusing on the challenges posed by sea clutter and multipath *** performance of the radar detection methods under sea clutter,multipath,and combined conditions is categorized and summarized,and future research directions are outlined to enhance radar detection performance for low-altitude targets in maritime environments.

关键词： radar sea clutter multipath scattering detection low altitude target

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Selective nano-buckling improves the performance of graphene logic transistors

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National Science Review 2024年第2期11卷 95-96页

作者： Tong yang Ming yang Department of Applied Physics The Hong Kong Polytechnic University Research Centre for Nanoscience and Nanotechnology The Hong Kong Polytechnic University

The massive integration of silicon-based transistors into modern electronic devices greatly increases power consumption and heat generation/dissipation[1]. In this concern, transistors based on atomically-thin graphene that exhibit high electric and thermoelectric conductivities with negligible contact resistance,

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Design Optimization and Operating Performance of S-CO_(2) Brayton Cycle under Fluctuating Ambient Temperature and Diverse Power Demand Scenarios

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Journal of Thermal Science 2024年第1期33卷 190-206页

作者： yang Jingze yang Zhen DUAN Yuanyuan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce *** the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand *** addition,the cycle design condition will directly affect the off-design *** this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced *** show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient *** average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient *** multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature *** the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.

关键词： supercritical CO_(2)Brayton cycle ambient temperature fluctuating power demand scenarios design optimization off-design performance

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A physics-informed deep learning framework for spacecraft pursuit-evasion task assessment

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Chinese Journal of Aeronautics 2024年第5期37卷 363-376页

作者： Fuyunxiang yang Leping yang Yanwei ZHU College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Qualitative spacecraft pursuit-evasion problem which focuses on feasibility is rarely studied because of high-dimensional dynamics,intractable terminal constraints and heavy computational *** this paper,A physics-informed framework is proposed for the problem,providing an intuitive method for spacecraft threat relationship determination,situation assessment,mission feasibility analysis and orbital game rules *** the first time,situation adjustment suggestions can be provided for the weak player in orbital ***,a dimension-reduction dynamics is derived in the line-of-sight rotation coordinate system and the qualitative model is determined,reducing complexity and avoiding the difficulty of target set presentation caused by individual ***,the Backwards Reachable Set(BRS)of the target set is used for state space partition and capture zone ***-time analysis can eliminate the influence of changeable initial state and enable the proposed framework to analyze plural situations ***,a time-dependent Hamilton-Jacobi-Isaacs(HJI)Partial Differential Equation(PDE)is established to describe BRS evolution driven by dimension-reduction dynamics,based on level set ***,Physics-Informed Neural Networks(PINNs)are extended to HJI PDE final value problem,supporting orbital game rules summarization through capture zone evolution ***,numerical results demonstrate the feasibility and efficiency of the proposed framework.

关键词： Spacecraft pursuit-evasion Qualitative differential game Physics-Informed Neural Networks(PINNs) Reachability analysis Hamilton-Jacobi-Isaacs(HJI) Partial Differential Equations(PDEs)

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Processing,microstructure,and properties of porous ceramic composites with directional channels

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Journal of Materials Science & Technology 2024年第1期168卷 1-15页

作者： Bo Zhang yang yang Xueling Fan Key Laboratory of Service Performance and Protection Technology in Extreme Environments Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China

Porous ceramic composites with directional microchannels from micrometer to dozens of micrometer levels have attracted more and more attention in various fields including aerospace,biomedicines,and thermal insulation due to their excellent fluid permeability,mechanical properties,*** this article,we summarize the recent directional porous ceramics developments including their main processing routes and respective ***,the properties get from different processing routes have been com-pared and analyzed in terms of microstructures,mechanical properties,and *** has been given to the deeper understanding which can allow one to control the microstructural features of these porous ceramic composites to obtain the desired *** work can provide a useful reference for the development and application of porous ceramic composites with directional microchan-nels.

关键词： Porous ceramic composites Directional microchannels Processing routes Permeability