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Composition design and performance evaluation of rubber-particle cement-stabilized gravel

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Frontiers of Structural and Civil Engineering 2024年第9期18卷 1466-1477页

作者： Chaohui WANG ke YI Feng CHEN Luqing LIU xiaolei ZHOU Zhiwei GAO School of Highway Chang’an UniversityXi’an 710064China Shaanxi Transportation Technology Consulting Co. Ltd.Xi’an 710068China School of Information Engineering Xizang Minzu UniversityXianyang 71208China

To improve the mechanical properties and durability of the cement-stabilized base,rubber particles of three different sizes and with three different contents were optimally selected,the evolution laws of the mechanical strength and toughness of rubber-particle cement-stabilized gravel(RCSG)under different schemes were determined,and the optimal particle size and content of rubber particles were *** this basis,the durability of the RCSG base was *** results show that with an increase in the rubber particle size and content,the mechanical strength of RCSG gradually decreased,whereas the toughness and transverse deformation ability gradually increased.1%content and 2–4 mm sized RCSG can better balance the relationship between mechanical strength and *** 7 d unconfined compressive strength was 17.7%higher than that of the 4–8 mm *** 28 d toughness index and ultimate splitting strain can be increased by 9.8%and 6.3 times,respectively,compared with ordinary cement-stabilized gravel(CSG).In terms of durability,compared with CSG,RCSG showed a 3.7%increase in the water stability property of cement-stabilized base with 1%content and 2–4 mm rubber particles,5.5%increase in the frozen coefficient,and 80.6%and 37.9%increase in the fatigue life at 0.70 and 0.85 stress ratio levels,respectively.

关键词： pavement materials cement-stabilized gravel rubber particles material components mechanical property durability performance

A Novel Approach for Trajectory Tracking Control of an Under-Actuated Quad-Rotor UAV

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IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 2030-2032页

作者： ke Shao Kang Huang Shengchao Zhen Hao Sun Rongrong Yu School of Civil Aviation Northwestern Polytechnical UniversityXi’an 710072 School of Mechanical Engineering Hefei University of TechnologyHefei 230009China

Dear Editor,This letter presents a novel Udwadia-Kalaba(U-K)approach for the trajectory tracking control of a quad-rotor unmanned aerial vehicle(UAV).Compared to conventional control approaches,the desired trajectorie... 详细信息

关键词： letter desired constraints

Covert LEO Satellite Communication Aided by Generative Adversarial Network Based Cooperative UAV Jamming

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China Communications 2024年第9期21卷 27-39页

作者： Shi Jia Li xiaomeng liao xiaomin Tie Zhuangzhuang Hu Junfan School of Communication Engineering Xidian UniversityXi’an 710071China School of Information and Communications National University of Defense TechnologyWuhan 410073China

In this paper,we study the covert performance of the downlink low earth orbit(LEO)satellite communication,where the unmanned aerial vehicle(UAV)is employed as a cooperative *** maximize the covert rate of the LEO satellite transmission,a multi-objective problem is formulated to jointly optimize the UAV’s jamming power and *** practical consideration,we assume that the UAV can only have partial environmental information,and can’t know the detection threshold and exact location of the eavesdropper on the *** solve the multiobjective problem,we propose the data-driven generative adversarial network(DD-GAN)based method to optimize the power and trajectory of the UAV,in which the sample data is collected by using genetic algorithm(GA).Simulation results show that the jamming solution of UAV generated by DD-GAN can achieve an effective trade-off between covert rate and probability of detection errors when only limited prior information is obtained.

关键词： covert communication generative adversarial network LEO satellite UAV jammer

Towards sustainable adversarial training with successive perturbation generation

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Frontiers of Information Technology & Electronic Engineering 2024年第4期25卷 527-539页

作者： Wei LIN Lichuan liao College of Computer Science and Mathematics Fujian University of TechnologyFuzhou 350118China College of Economics and Management Xi’an University of TechnologyXi’an 710048China Fujian Provincial key Laboratory of Big Data Mining and Applications Fujian University of TechnologyFuzhou 350118China

Adversarial training with online-generated adversarial examples has achieved promising performance in defending adversarial attacks and improving robustness of convolutional neural network ***,most existing adversarial training methods are dedicated to finding strong adversarial examples for forcing the model to learn the adversarial data distribution,which inevitably imposes a large computational overhead and results in a decrease in the generalization performance on clean *** this paper,we show that progressively enhancing the adversarial strength of adversarial examples across training epochs can effectively improve the model robustness,and appropriate model shifting can preserve the generalization performance of models in conjunction with negligible computational *** this end,we propose a successive perturbation generation scheme for adversarial training(SPGAT),which progressively strengthens the adversarial examples by adding the perturbations on adversarial examples transferred from the previous epoch and shifts models across the epochs to improve the efficiency of adversarial *** proposed SPGAT is both efficient and effective;e.g.,the computation time of our method is 900 min as against the 4100 min duration observed in the case of standard adversarial training,and the performance boost is more than 7%and 3%in terms of adversarial accuracy and clean accuracy,*** extensively evaluate the SPGAT on various datasets,including small-scale MNIST,middle-scale CIFAR-10,and large-scale *** experimental results show that our method is more efficient while performing favorably against state-of-the-art methods.

关键词： Adversarial training Adversarial attack Stochastic weight average Machine learning Model generalization

Potassium ions and cyano group modified g-CNfor effective generation of HOthrough two-electron oxygen reduction

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Science China Chemistry 2024年

作者： Dongying Wang Shulan Pu Yongmin Chen ke Lei Yujie Duan Linjiao Mao Xuhui Zeng xi Luo Yuntao Zhang Yuqin Dong Jinzhong Zhang Yan Sun School of Mechanical Engineering Chengdu University Department of Chemistry and Biochemistry University of California

Potassium ions （K+） doped graphitic carbon nitride （g-C3N4） was prepared by a thermal etching method using potassium hydroxide （KOH） as an ion source. Fourier transform infrared spectroscopy （FTIR） and X-ray photoelectron spectroscopy （XPS）results showed that the generation of the cyano group was detected while introducing K+. Under simulated sunlight irradiation,the sample with a K+doping amount of 10%showed the highest hydrogen peroxide （H2O2） generation rate of 2,140.2μmol h-1g-1. The apparent quantum yield （AQY） at 400 nm and the solar-to-chemical conversion （SCC） are 4.35%and1.23%, respectively. K+acted as a bridge between g-C3N4layers, which enhanced charge transfer efficiency. Meanwhile, the cyano group enhanced the adsorption capacity of protons （H+） and promoted the yield of H2O2. The catalyst exhibited excellent photocatalytic stability based on four-cycle experiments. In addition, a mechanism study showed that superoxide radicals （·O2-）were the most important active species in the reaction system. Photocatalytic production of H2O2was achieved through consecutive single-electron steps. This study deepens the understanding of the oxygen reduction reaction process and opens up a new venue for improving H2O2generation.

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WT-FCTGN:A wavelet-enhanced fully connected time-gated neural network for complex noisy traffic flow modeling

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Chinese Physics B 2024年第7期33卷 652-664页

作者：廖志芳孙轲刘文龙余志武刘承光宋禹成 School of Computer Science and Engineering Central South UniversityChangsha 410083China National Engineering Research Center of High-speed Railway Construction Technology Changsha 410075China School of Civil Engineering Central South UniversityChangsha 410075China School of Traffic&Transportation Engineering Central South UniversityChangsha 410083China

Accurate forecasting of traffic flow provides a powerful traffic decision-making basis for an intelligent transportation system. However, the traffic data's complexity and fluctuation, as well as the noise produced during collecting information and summarizing original data of traffic flow, cause large errors in the traffic flow forecasting results. This article suggests a solution to the above mentioned issues and proposes a fully connected time-gated neural network based on wavelet reconstruction(WT-FCTGN). To eliminate the potential noise and strengthen the potential traffic trend in the data, we adopt the methods of wavelet reconstruction and periodic data introduction to preprocess the data. The model introduces fully connected time-series blocks to model all the information including time sequence information and fluctuation information in the flow of traffic, and establishes the time gate block to comprehend the periodic characteristics of the flow of traffic and predict its flow. The performance of the WT-FCTGN model is validated on the public Pe MS data set. The experimental results show that the WT-FCTGN model has higher accuracy, and its mean absolute error(MAE), mean absolute percentage error(MAPE) and root mean square error(RMSE) are obviously lower than those of the other algorithms. The robust experimental results prove that the WT-FCTGN model has good anti-noise ability.

关键词： traffic flow modeling time-series wavelet reconstruction

Degradation Behavior of Zn-Cu Stents with Different Coatings in Sodium Chloride Solution

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Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1564-1580页

作者： xingpeng liao Jialuo Huang Zhilin Liu Jingru Guo Dajiang Zheng Pengbo Chen Fuyong Cao Center for Marine Materials Corrosion and Protection Fujian Key Laboratory of Surface and Interface Engineering for High Performance MaterialsCollege of MaterialsXiamen UniversityXiamen361005China Light Alloys Research Institute College of Mechanical and Electrical EngineeringCentral South UniversityChangsha410083China First Affiliated Hospital of xi’an Jiao Tong University Xi’an710061China

The Zn0.6Cu wires are fabricated into stents for the potential biodegradable application of nasal wound *** degradation behavior of Zn0.6Cu stents in 0.9 wt%NaCl at 36.5℃ is *** shows that the untreated Zn0.6Cu stent experiences severe crevice corrosion with acceleration and autocatalytic effects within the micro-cracks and ruptures at 4.67±1.15 d,with the average corrosion rate of 0.28 mm y^(-1).Fortunately,the anodic polarization(AP)+hydrothermal(H)conversion coating,consisting of ZnCO_(3),Zn(OH)_(2) and ZnO,could inhibit the crevice corrosion significantly by reducing the cathode/anode ratio,extending the rupture time up to 16.50±2.95 d,with the average corrosion rate of 0.14 mm y^(-1).This research indicates that the biodegradable Zn-based stent has some potential applications in nasal wound recovery area.

关键词： Zn alloys wires Corrosion behavior Biodegradable stents Coating Degradation characterization

Effect of trace oxygen on plasma nitriding of titanium foil

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Chinese Physics B 2024年第6期33卷 548-551页

作者：周海涛熊希雅马可欣罗炳威罗飞申承民 Beijing Institute of Aeronautical Materials Aero Engine Corporation of ChinaBeijing 100095China Beijing National Laboratory of Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

Titanium nitride films are prepared by plasma enhanced chemical vapor deposition method on titanium foil using N_(2) as precursor. In order to evaluate the effect of oxygen on the growth of titanium nitride films, a small amount of O_(2) is introduced into the preparation process. The study indicates that trace O_(2) addition into the reaction chamber gives rise to significant changes on the color and micro-morphology of the foil, featuring dense and long nano-wires. The as-synthesized nanostructures are characterized by various methods and identified as TiN, Ti_(2) N, and TiO_(2) respectively. Moreover, the experiment results show that oxide nanowire has a high degree of crystallinity and the nitrides present specific orientation relationships with the titanium matrix.

关键词： nitride oxide nanostructure crystalline plasma-enhanced chemical vapor deposition system(PECVD)

Aerodynamic/stealth design of S-duct inlet based on discrete adjoint method

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 725-746页

作者： Jun DENG ke ZHAO Lin ZHOU Wei ZHANG Bowen SHU Jiangtao HUANG Zhenghong GAO School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Aerospace Technology Institute of China Aerodynamic Research and Development CenterMianyang 621000Sichuan ProvinceChina

It is a major challenge for the airframe-inlet design of modern combat aircrafts,as the flow and electromagnetic wave propagation in the inlet of stealth aircraft are very *** this study,an aerodynamic/stealth optimization design method for an S-duct inlet is *** upwind scheme is introduced to the aerodynamic adjoint equation to resolve the shock wave and flow *** multilevel fast multipole algorithm(MLFMA)is utilized for the stealth adjoint equation.A dorsal S-duct inlet of flying wing layout is optimized to improve the aerodynamic and stealth *** the aerodynamic and stealth characteristics of the inlet are effectively ***,the optimization results are analyzed,and it shows that the main contradiction between aerodynamic characteristics and stealth characteristics is the centerline and crosssectional *** S-duct is smoothed,and the cross-sectional area is increased to improve the aerodynamic characteristics,while it is completely opposite for the stealth *** radar cross section(RCS)is reduced by phase cancelation for low frequency *** method is suitable for the aerodynamic/stealth design of the aircraft airframe-inlet system.

关键词： S-duct inlet aerodynamic/stealth optimization design discrete adjoint upwind scheme multilevel fast multipole algorithm(MLFMA)