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EFFECT OF CERIUM ION IMPLANTATION ON THE AqUEOUS CORROSION BEHAVIOR OF ZIRCONIUM

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 812-816页

作者： D.q.Peng x.D.Bai q.G.Zhou x.W.Chen R.H.Yu x.Y.liu DepartmentofMaterialsScienceandEngineering TsinghuaUniversityBeijing100084ChinaManuscriptreceived9September2003

In order to study the influence of cerium ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted by cerium ions with a dosage range from 1×1016 to 1×1017 ions/cm2 at about 150℃, using MEVVA source at an acceler ative voltage of 40kV. The valence of the surface layer was analyzed by x-ray photo- electron spectroscopy (xPS); Three-sweep potentiodynamic polarization measurement was employed to value the aqueous corrosion resistance of zirconium in a 0.5mol/L H2SO4 solution. It was found that a remarkable decline in the aqueous corrosion behavior of zirconium implanted with cerium ions compared with that of the as-received zirconium. Finally, the mechanism of the corrosion resistance decline of the cerium-implanted zirconium is discussed.

关键词： zirconium corrosion resistance cerium ion implantation potentio- dynamic polarization x-ray photoelectron spectroscopy (xPS)

Annual and interannual variations of the Western Pacific Warm Pool volume and sources of warm water revealed by Argo data

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Science China Earth Sciences 2014年第12期57卷 2269-2280页

作者： WU xiaoFen ZHANG qiLong liu ZengHong Second Institute of Oceanography State Oceanic Administration Key Laboratory of Ocean Circulation and Waves Institute of Oceanology Chinese Academy of Sciences State Key Laboratory of Satellite Ocean Environment Dynamics State Oceanic Administration

Based on gridded Argo profile data from January 2004 to December 2010, together with the P-vector inverse method, the three-dimensional structure, annual and inter-annual variations in volume of the Western Pacific Warm Pool （WPWP） are studied. The variations of latitudinal and longitudinal warm water flowing into and out of the WPWP and the probable mecha- nism of warm water maintenance are also discussed. From the surface to the bottom, climatic WPWP tilts southward and its area decreases. The maximum depth could extend to 120 m, such that its volume could attain 1.86x10^5 m3. Annual variation of the WPWP volume shows two obvious peaks that occur in June and October, whereas its inter-annual variations are related to ENSO events. Based on a climatic perspective, the warm water flowing latitudinally into the pool is about 52 Sv, which is mainly through upper layers and via the eastern boundary. Latitudinally, warm water flowing outward is about 49 Sv, and this is mainly through lower layers and via the western boundary. In contrast, along the latitude, warm water flowing into and out of the pool is about 28 Sv and 23 Sv, respectively. Annual and inter-annual variations of the net transportation of the warm water demonstrate that the WPWP mainly loses warm water in the west-east direction, whereas it receives warm water from the north-south direction. The annual variation of the volume of WPWP is highly related to the annual variation of the net warm water transportation, however, they are not closely related on inter-annual time scale. On the inter-annual time scale, in- fluences of ENSO events on the net warm water transportation in the north-south direction are much more than that in the west-east direction. Although there are some limitations and simplifications when using the P-vector method, it could still help improve our understanding of the WPWP, especially regarding the sources of the warm water.

关键词： Western Pacific Warm Pool volume variability latitudinal flow longitudinal flow Argo data P-vector method

Sensitivity impacts owing to the variations in the type of zero-range pairing forces on the fission properties using the density functional theory

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Nuclear Science and Techniques 2024年第3期35卷 198-207页

作者： Yang Su Ze-Yu Li Li-Le liu Guo-xiang Dong xiao-Bao Wang Yong-Jing Chen China Nuclear Data Center China Institute of Atomic EnergyBeijing 102413China School of Science Huzhou UniversityHuzhou 313000China

Using the Skyrme density functional theory,potential energy surfaces of^(240)Pu with constraints on the axial quadrupole and octupole deformations(q_(20)and q_(30))were *** volume-like and surface-like pairing forces,as well as a combination of these two forces,were used for the Hartree–Fock–Bogoliubov *** in the least-energy fission path,fission barrier,pairing energy,total kinetic energy,scission line,and mass distribution of the fission fragments based on the different forms of the pairing forces were analyzed and *** fission dynamics were studied based on the timedependent generator coordinate method plus the Gaussian overlap *** results demonstrated a sensitivity of the mass and charge distributions of the fission fragments on the form of the pairing *** on the investigation of the neutron-induced fission of^(239)Pu,among the volume,mixed,and surface pairing forces,the mixed pairing force presented a good reproduction of the experimental data.

关键词： Nuclear fission Density functional theory Pairing force Potential energy surfaces Fission fragment distribution

Joint UAV trajectory and communication design with heterogeneous multi-agent reinforcement learning

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Science China(Information Sciences) 2024年第3期67卷 225-245页

作者： xuanhan ZHOU Jun xIONG Haitao ZHAO xiaoran liu Baoquan REN xiaochen ZHANG Jibo WEI Hao YIN College of Electronic Science and Technology National University of Defense Technology Systems Engineering Institute Academy of Military Sciences PLA

Unmanned aerial vehicles(UAVs) are recognized as effective means for delivering emergency communication services when terrestrial infrastructures are unavailable. This paper investigates a multiUAV-assisted communication system, where we jointly optimize UAVs’ trajectories, user association, and ground users(GUs)’ transmit power to maximize a defined fairness-weighted throughput metric. Owing to the dynamic nature of UAVs, this problem has to be solved in real time. However, the problem’s non-convex and combinatorial attributes pose challenges for conventional optimization-based algorithms, particularly in scenarios without central controllers. To address this issue, we propose a multi-agent deep reinforcement learning(MADRL) approach to provide distributed and online solutions. In contrast to previous MADRLbased methods considering only UAV agents, we model UAVs and GUs as heterogeneous agents sharing a common objective. Specifically, UAVs are tasked with optimizing their trajectories, while GUs are responsible for selecting a UAV for association and determining a transmit power level. To learn policies for these heterogeneous agents, we design a heterogeneous coordinated qMIx(HC-qMIx) algorithm to train local q-networks in a centralized manner. With these well-trained local q-networks, UAVs and GUs can make individual decisions based on their local observations. Extensive simulation results demonstrate that the proposed algorithm outperforms state-of-the-art benchmarks in terms of total throughput and system fairness.

关键词： unmanned aerial vehicle (UAV) trajectory design resource allocation multi-agent deep reinforcement learning (MADRL) heterogeneous agents

Preseismic deformation in the seismogenic zone of the Lushan MS7.0 earthquake detected by GPS observations

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Science China Earth Sciences 2015年第8期58卷 1592-1601页

作者： liu xiaoxia WU Yanqiang JIANG ZaiSen ZHAN Wei LI qiang WEI Wenxin ZOU ZhenYu Institute of Geology China Earthquake Administration Key Laboratory of Earthquake Prediction China Earthquake Administration First Crust Monitoring and Application Center China Earthquake Administration

A continuous GPS array across the southern segment of the Longmenshan fault zone recorded the deformation during the process of the Lushan MS7.0 earthquake that occurred on April 20, 2013. Such data can provide meaningful information regarding the dynamic evolution of crustal deformation in the seismogenic zone. Our studies have shown that the occurrence of the Wenchuan earthquake led to the loading of compressive and sinistral shearing strain on the southern segment of the Maoxian-Wenchuan fault, whereby the extrusion strain accumulated at a greater rate than before the Wenchuan earthquake. The strain time series in the seismogenic zone revealed that the principal compression strain rates decreased from west to east in the direction of N30°–45°W. Furthermore, the area to the east of Beichuan-Yingxiu fault behaved as a zone of compressive deformation with obvious sinistral shearing deformation. The surface strain and the first shearing strain time series decreased with time, while the area to the west of the Beichuan-Yingxiu fault behaved as a zone of dextral shear deformation that increased with time. Furthermore, the regional deformation field before the Lushan earthquake showed that the rate of extrusion strain accumulation in the southern segment of the Longmenshan fault zone was obviously larger than before the Wenchuan earthquake. Moreover, the sinistral shearing strain accumulated in the area of the southern segment of the Maoxian-Wenchuan fault. Based on the above analysis, we consider that the eastward movement of the Bayan Har block increased considerably following the Wenchuan earthquake, which enhanced the accumulation of compression strain in the southern segment of the Longmenshan fault zone.

关键词： Lushan Ms7.0 earthquake GPS observations GPS baseline time series strain time series

Dynamic Impact of High-Density Aluminum Foam

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Acta Mechanica Solida Sinica 2022年第2期35卷 198-214页

作者： q.Peng J.xie H.S.Ma x.Ling x.liu Y.G.Wei LNM Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China School of Engineering and Technology China University of GeosciencesBeijing 100083China College of Engineering Peking UniversityBeijing 100871China

High-density aluminum foam can provide higher stiffness and absorb more energy during the impact Obtaining the constitutive law of such foam requires tri-axial tests with very high pressure,where difficulty may arise because the hydrostatic pressure can reach more than 30 *** this paper,instead of using tri-axial tests,we proposed three easier tests-tension,compression and shear to obtain the parameters of constitutive model(the Deshpande-Fleck model).To verify the constitutive model both statically and dynamically,we carried out addi-tional triaxial tests and direct impact tests,*** on the derived model,we performed finite element simulation to study the impact response of the present *** dimensional analysis,we proposed an empirical equation for a non-dimensional impact time the impact time divided by the time required for plastic wave travelling from the impact surface to the bottom surface,to det ermine the deformation charac teristic of the aluminum foam after *** the case with t_(d)≤1,the deformation tends to exhibit a shock-type characteristic,while for the case with t_(d)>5,the deformation tends to exhibit an upsetting-type characteristic.

关键词： High density aluminum Foam Deshpande-Fleck model Finite element method Impact analysis Plastic wave

Thermoelectric Properties of an Indandione-Terminated quinoidal Compound:Effect of the n-Type Dopants

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Chinese Journal of Chemistry 2024年第9期42卷 997-1003页

作者： Yingying liu Cheng Wang Tianzuo Wang Fei Jiao Shaoqiang Dong Yunfeng Deng Yanhou Geng School of Materials Science and Engineering and Tianjin Key Laboratory of Molecular Optoelectronic Science Tianjin Universityand Collaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin 300072China Institute of Molecular Aggregation Science Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Molecular Optoelectronic Science Department of ChemistrySchoolof ScienceTianjin UniversityTianjin300072China Joint Schoolof NationalUniversity of Singapore and Tianjin University International Campus of Tianjin UniversityBinhai New City FuzhouFujian350207China

The investigation of n-type doping holds a significant interest for the application of ***,the doping of an indandione-terminated compound q-4F with a singlet open-shell ground state was studied using two n-dopants N-DMBI and *** of these two dopants can effectively dope q-4F due to the large offset between the singly occupied molecular orbital(SOMO)of dopants and the lowest unoccupied molecular orbital(LUMO)of q-4F.N-DMBI has a higher doping ability than LCV as demonstrated by the UV-vis-NIR and EPR ***,in comparison to N-DMBI doped q-4F,LCV doped system exhibits much higher electrical conductivity and power factor due to its unperturbed molecular packing and favorable morphology after *** optimal conductivity of LCV doped q-4F is 7.16×10^(-2)±0.16 S·cm^(-1) and the highest power factor reaches 12.3±0.85μW·m–1·K^(-2).These results demonstrate that the modulation of n-dopants is a powerful strategy to balance the doping efficiency and microstructure toward a maximum thermoelectric performance.

关键词： n-Doping Indandione quinoidal compounds Organic thermoelectrics Electron transfer Organic electronics Energy conversion

Research on Driver’s Fatigue Detection Based on Information Fusion

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Computers, Materials & Continua 2024年第4期79卷 1039-1061页

作者： Meiyan Zhang Boqi Zhao Jipu Li qisong Wang Dan liu Jinwei Sun Jingxiao Liao Harbin Institute of Technology School of Instrument Science and EngineeringHarbin150036China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong Kong100872China

Driving fatigue is a physiological phenomenon that often occurs during *** the driver enters a fatigued state,the attentionis lax,the response is slow,and the ability todeal with emergencies is significantly reduced,which can easily cause traffic ***,studying driver fatigue detectionmethods is significant in ensuring safe ***,the fatigue state of actual drivers is easily interfered with by the external environment(glasses and light),which leads to many problems,such as weak reliability of fatigue driving ***,fatigue is a slow process,first manifested in physiological signals and then reflected in human face *** improve the accuracy and stability of fatigue detection,this paper proposed a driver fatigue detection method based on image information and physiological information,designed a fatigue driving detection device,built a simulation driving experiment platform,and collected facial as well as physiological information of drivers during ***,the effectiveness of the fatigue detection method was *** movement feature parameters and physiological signal features of drivers’fatigue levels were *** driver fatigue detection model was trained to classify fatigue and non-fatigue states based on the extracted *** rates of the image,electroencephalogram(EEG),and blood oxygen signals were 86%,82%,and 71%,*** fusion theory was presented to facilitate the fatigue detection effect;the fatigue features were fused using multiple kernel learning and typical correlation analysis methods to increase the detection accuracy to 94%.It can be seen that the fatigue driving detectionmethod based onmulti-source feature fusion effectively detected driver fatigue state,and the accuracy rate was higher than that of a single information *** summary,fatigue drivingmonitoring has broad development prospects and can be used in traffic accident prevention and wearable dr

关键词： Driving fatigue information fusion EEG blood oxygen

The effects of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents:a meta-analysis

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Neural Regeneration Research 2025年第5期20卷 1513-1520页

作者： xueyun Shao Longfei He Yangyang liu Physical Education School Shenzhen UniversityShenzhenGuangdong ProvinceChina Shenzhen Institute of Neuroscience ShenzhenGuangdong ProvinceChina

Brain-derived neurotrophic factor is a crucial neurotrophic factor that plays a significant role in brain health. Although the vast majority of meta-analyses have confirmed that exercise interventions can increase brain-derived neurotrophic factor levels in children and adolescents, the effects of specific types of exercise on brain-derived neurotrophic factor levels are still controversial. To address this issue, we used meta-analytic methods to quantitatively evaluate, analyze, and integrate relevant studies. Our goals were to formulate general conclusions regarding the use of exercise interventions, explore the physiological mechanisms by which exercise improves brain health and cognitive ability in children and adolescents, and provide a reliable foundation for follow-up research. We used the Pub Med, Web of Science, Science Direct, Springer, Wiley Online Library, Weipu, Wanfang, and China National Knowledge Infrastructure databases to search for randomized controlled trials examining the influences of exercise interventions on brain-derived neurotrophic factor levels in children and adolescents. The extracted data were analyzed using Review Manager 5.3. According to the inclusion criteria, we assessed randomized controlled trials in which the samples were mainly children and adolescents, and the outcome indicators were measured before and after the intervention. We excluded animal experiments, studies that lacked a control group, and those that did not report quantitative results. The mean difference(MD;before versus after intervention) was used to evaluate the effect of exercise on brain-derived neurotrophic factor levels in children and adolescents. Overall, 531 participants(60 children and 471 adolescents, 10.9–16.1 years) were included from 13 randomized controlled trials. Heterogeneity was evaluated using the q statistic and I^(2) test provided by Review Manager software. The meta-analysis showed that there was no heterogeneity among the studies(P = 0.67,

关键词： adolescents brain-derived neurotrophic factor children exercise meta-analysis randomized controlled trials