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31p NMR study of magnetic phase transitions of MnP single crystal under 2 GPa pressure

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Science China(Physics,Mechanics & Astronomy) 2016年第5期59卷 7-10页

作者： GuoZhi Fan bo zhao Wei Wu Ping Zheng JianLin Luo Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Collaborative Innovation Center of Quantum Matter Beijing 100190 China

Superconductivity on the border of the long-range magnetic order has been discovered in Mn P under high pressures. In order to investigate the nature of the magnetic properties adjacent to the superconducting state, we performed zero-field 31 P NMR for Mn P single crystal under ambient and hydrostatic pressure of 2 GPa, respectively. Radio frequency power level was used to determine whether NMR signal originates from a helical state or not. When 2 GPa pressure was applied, the signal from helical state exists even above 160 K, while that from the ferromagnetic phase was not observed. Our NMR results indicate that the magnetic phase which is adjacent to the superconducting state is in a helical magnetic structure.

关键词： superconducting materials magnetic phase transitions nuclear magnetic resonance MnP

Low complexity robust adaptive beamforming for general-rank signal model with positive semidefinite constraint

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Frontiers of Information Technology & Electronic Engineering 2016年第11期17卷 1245-1252页

作者： Yu-tang ZHU Yong-bo zhao Jun LIU Peng-lang SHUI National Laboratory of Radar Signal Processing Xidian University

We propose a low complexity robust beamforming method for the general-rank signal model, to combat against mismatches of the desired signal array response and the received signal covariance matrix. The proposed beamformer not only considers the norm bounded uncertainties in the desired and received signal covariance matrices, but also includes an additional positive semidefinite constraint on the desired signal covariance matrix. Based on the worst-case performance optimization criterion, a computationally simple closed-form weight vector is obtained. Simulation results verify the validity and robustness of the proposed beamforming method.

关键词： Beamforming General-rank Low complexity Positive semidefinite(PSD) constraint Model mismatches

Optimal Tracking Control for Reconfigurable Manipulators Based on Critic-only Policy Iteration Algorithm 36

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Optimal Tracking Control for Reconfigurable Manipulators Bas...

Insights into some large-scale landslides in southeastern margin of Qinghai-Tibet Plateau

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作者： Hongbing Xia bo zhao Yuanchun Li Department of Control Science and Engineering Changchun University of Technology The State Key Laboratory of Management and Control for Complex Systems Institute of AutomationChinese Academy of Sciences

ISBN: (纸本)9781538629185

This paper tackles the optimal tracking control problem for reconfigurable manipulators based on critic-only policy iteration（Co PI） algorithm. By system transformation, the optimal tracking control problem is transformed into an optimal regulation problem. The optimal tracking controller is composed of the desired controller and the approximate optimal feedback one. The desired controller is developed to maintain the desired tracking performance at the steady-state, while the approximate optimal feedback controller is designed to stabilize the tracking error dynamics in an optimal manner. Then, a critic neural network is used to estimate the optimal performance index function, and the optimal feedback control is obtained by the Co PI algorithm. The convergence of the proposed method is analyzed and it is shown that the closed-loop system based on Co PI is uniformly ultimately bounded by using the Lyapunov approach. Finally, simulation studies are given to show the effectiveness of the developed method.

关键词： Adaptive dynamic programming Reconfigurable manipulators Optimal tracking control Policy iteration Neural networks

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第8期15卷 1960-1985页

作者： bo zhao Lijun Su Yunsheng Wang Weile Li Lijuan Wang Key Laboratory of Mountain Hazards and Earth Surface Processes Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu610041China China-Pakistan Joint Research Center on Earth Sciences IslamabadPakistan University of Chinese Academy of Sciences Beijing100049China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu610059China Sichuan Academy of Safety Science and Technology Chengdu610045China Major Hazard Measurement and Control Key Laboratory of Sichuan Province Chengdu610045China

The southeastern margin of Qinghai-Tibet Plateau(SMQTP)is of a typical large landslide-prone area due to intense tectonic activity,deeply incised valleys,high geostress and frequent *** gain insights into large landslides in southeastern margin of Qinghai-Tibet Plateau,an area covering 3.34×105 km2 that extends 80e150 km on both sides of the Sichuan-Tibet traffic corridors(G318)was used to examine the spatial distribution and corresponding characteristics of *** results showed that the study area contains at least 629 large landslides that are mainly concentrated on 7 zones(zones IeVII).Zones IeVII are in the southern section of the Longmenshan fault zone(with no large river)and sections with Dadu River,Jinsha River,Lancang River,Nujiang River and Yarlung Zangbo *** are more landslides in the Jinsha River section(totaling 186 landslides)than the other *** to the updated Varnes classification,408 large landslides(64.9%)were recognized and divided into 4 major types,***(275 cases),slides(58 cases),topples(44 cases)and slope deformations(31 cases).Flows,which consist of rock avalanches and iceerock avalanches,are the most common landslide *** landslide triggers(178 events,28.3%)are also recognized,and earthquakes may be the most common *** to the limited data,these landslide type classifications and landslide triggers are perhaps immature,and further systematic analysis is needed.

关键词： Southeastern margin of Qinghai-Tibet Plateau Large landslides Landslide types Landslide triggers Landslide concentration zones

An AI‑Based Method for Estimating the Potential Runout Distance of Post‑Seismic Debris Flows

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International Journal of Disaster Risk Science 2024年第4期15卷 608-621页

作者： Chenchen Qiu Lijun Su Congchao Bian bo zhao Xueyu Geng School of Engineering University of WarwickCoventry CV47ALUK Key Laboratory of Mountain Hazards and Earth Surface Process/Institute of Mountain Hazards and Environment(IMHE) Chinese Academy of Sciences(CAS)Chengdu 610041China School of Computer and Information Hohai UniversityNanjing 211100China

The widely distributed sediments following an earthquake presents a continuous threat to local residential areas and infrastructure. These materials become more easily mobilized due to reduced rainfall thresholds. Before establishing an effective management plan for debris flow hazards, it is crucial to determine the potential reach of these sediments. In this study, a deep learning-based method-Dual Attention Network(DAN)-was developed to predict the runout distance of potential debris flows after the 2022 Luding Earthquake, taking into account the topography and precipitation conditions. Given that the availability of reliable precipitation data remains a challenge, attributable to the scarcity of rain gauge stations and the relatively coarse resolution of satellite-based observations, our approach involved three key steps. First, we employed the DAN model to refine the Global Precipitation Measurement(GPM) data, enhancing its spatial and temporal resolution. This refinement was achieved by leveraging the correlation between precipitation and regional environment factors(REVs) at a seasonal scale. Second, the downscaled GPM underwent calibration using observations from rain gauge stations. Third,mean absolute error(MAE), mean square error(MSE), and root mean square error(RMSE) were employed to evaluate the performance of both the downscaling and calibration processes. Then the calibrated precipitation, catchment area, channel length, average channel gradient, and sediment volume were selected to develop a prediction model based on debris flows following the Wenchuan Earthquake. This model was applied to estimate the runout distance of potential debris flows after the Luding Earthquake. The results show that:(1) The calibrated GPM achieves an average MAE of 1.56 mm, surpassing the MAEs of original GPM(4.25 mm) and downscaled GPM(3.83 mm);(2) The developed prediction model reduces the prediction error by 40 m in comparison to an empirical equation;(3) The potential

关键词： Deep learning GPM downscaling Post-seismic debris fows Runout distance prediction 2022 Luding earthquake

Advanced System-Level Model Reduction Method for Multi-Converter DC Power Systems

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1550-1562页

作者： Lin Zhu Xueshen zhao Xialin Li Li Guo bo zhao Zhanfeng Deng Hao Lu Chengshan Wang the Key Laboratory of Smart Grid of Ministry of Education Tianjin UniversityTianjin 300072China the Research Institute of State Grid Zhejiang Electric Power Co. Ltd.Hangzhou 310014China the State Grid Global Energy Interconnection Research Institute Beijing 102209China

For dynamic stability analysis and instability mechanism understanding of multi-converter medium voltage DC power systems with droop-based double-loop control,an advanced system-level model reduction method is *** this method,mathematical relationships of control parameters(e.g.,current and voltage control parameters)between the system and its equivalent reduced-order model are ***,open-loop and closed-loop equivalent reduced-order models of current control loop considering dynamic interaction among converters are *** instability mechanism(e.g.,unreasonable current control parameters)of the system can be revealed *** guidance for adjustment of current control parameters can also be ***,considering dynamic interaction of current control among converters,open-loop and closed-loop equivalent reduced-order models of voltage control loop are *** frequency and damping factor of DC bus voltage in a wide oscillation frequency range(e.g.,10–50 Hz)can be evaluated *** importantly,accuracy of advanced system-level model reduction method is not compromised,even for MVDC power systems with inconsistent control parameters and different number of ***,experiments in RT-boX hardware-in-the-loop experimental platform are conducted to validate the advanced system-level model reduction method.

关键词： Closed-loop reduced-order model instability mechanism open-loop reduced-order model stability analysis system-level model reduction method

Controllable design of high-efficiency triboelectric materials by functionalized metal–organic frameworks with a large electronwithdrawing functional group

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Nano Research 2022年第10期15卷 9386-9391页

作者： Rongmei Wen Rui Feng bo zhao Jiangfeng Song Liming Fan Junyi Zhai Department of Chemistry College of ScienceNorth University of ChinaTaiyuan 030051China Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of SciencesBeijing 101400China College of Chemistry State Key Laboratory of Elemento-Organic ChemistryNankai UniversityTianjin 300071China

Triboelectric nanogenerator(TENG)can directly convert mechanical energy into electric ***,the triboelectric materials are limited to the triboelectric ***,for the first time,we choose the isostructural UiO-66-X(X=H,NH_(2),NO_(2),and Br)family as triboelectric materials to investigate the underlying relationships between different functional groups and the triboelectric performance of *** traditional triboelectric material organic polymers,metal–organic frameworks(MOFs)can be oriented design synthesis and functionalized with various functional *** results demonstrate that the largest output voltage and current are from UiO-66-NO_(2) TENG,and are about 23.79 V and 0.29μA,which are 3.19 and 4.14 times over that of the UiO-66 TENG,*** working mechanism of the MOF TENG was discussed in depth through experiments and theoretical *** work proves a novel strategy to obtain high output properties by functionalized MOFs with large electron-withdrawing functional groups and promising guidance for the choice of high-efficiency triboelectric materials.

关键词： triboelectric nanogenerator metal-organic frameworks UiO-66 functional group isostructural

Integrating predictive modeling techniques with geospatial data for landslide susceptibility assessment in northern Pakistan

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Journal of Mountain Science 2023年第9期20卷 2603-2627页

作者： Aamir ASGHAR SU Li-jun zhao bo Nadeem Ahmad USMANI Key Laboratory of Mountain Hazards and Earth Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of Sciences(CAS)Chengdu 610041China University of Chinese Academy of Sciences Beijing 100049China China-Pakistan Joint Research Center on Earth Sciences CAS-HECIslamabad 45320Pakistan The University of Poonch Rawalakot Rawalakot 12350Pakistan

The eastern road section of the ChinaPakistan Economic Corridor(CPEC)traverses the challenging terrain of northern Pakistan,where frequent landslides pose a significant threat to socioeconomic development and ***,the insufficient data on landslide hazards presents a substantial challenge to practical mitigation ***,we conducted an extensive study to gain insight into landslide assessment along the Mansehra-Muzaffarabad-Mirpur and Mangla(MMMM)*** study involved preparing a landslide inventory,analyzing landslide causative factors,and developing landslide susceptibility models(LSMs)using published data,remote sensing interpretations,field excursions and integrated predictive *** first used Pearson's correlation coefficient(PCC),variable importance factors(VIF),and information gain ratio(IGR)to evaluate multicollinearity among the selected landslide causative factors(LCFs).Then,the topographic roughness index(TRI)with VIF>5 and PCC>0.7 was considered a redundant factor and thus removed before the data ***,we adopted multiple machine-learning methods to analyze landslide *** results indicate that the landslide inventory contains 1,776 events,of which 674 were classified based on geometrical and lithological *** IGR results show that the rainfall,lithology,PGA,drainage density,slope,and distance to fault are the most effective *** AUC values for random forest(RF)(0.901),extreme gradient boosting(XGboost)(0.884),and K-nearest neighbor(KNN)(0.872)remained higher than evidential belief function(EBF)(0.833),weight of evidence(WoE)(0.820),and certainty factor(CF)(0.810),*** RF model outperformed all other models in terms of ***,these models are accurate but newer in the area;thus,susceptible zones were verified with comprehensive field *** northern and central regions accounted for the high and very high susceptibility classes in th

关键词： Landslides MMMM expressway Machine learning Landslide susceptibility Northern Pakistan

One-bit splitting deceptive jamming against SAR

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Defence Technology（防务技术） 2022年第10期18卷 1760-1777页

作者： bo zhao Lei Huang Bing Li Shi-qi Liu Wei-min Bao Guangdong Key Laboratory of Intelligent Information Processing College of Information EngineeringShenzhen UniversityShenzhen518060China China Aerospace Science and Technology Corporation Beijing100048China

One-bit quantization is a promising technique due to its performance retention and complexity reduction in a deceptive jammer against synthetic aperture radar(SAR).In this paper,the 1-bit quantization technology is utilized to agilely generate split false targets in the SAR imagery once the radar signal is intercepted,which reduces the complexity of the jammer significantly with guaranteed focusing quality.A single-frequency threshold is used to decompose harmonics incurred by the 1-bit quantization,and its parameters are adjusted through different pulse repetition intervals to provide steerable *** this way,the SAR signal is split into coupled false scatterers during the 1-bit *** further deploying amplitude,time-delay,and Doppler frequency modulations on the 1-bit intercepted signal,the split false targets are *** proposed approach is compared with different deceptive jamming methods to show its validity in effectiveness and cost,and numerical experiments are also presented for verification.

关键词： Synthetic aperture radar(SAR) 1-Bit quantization Multi-false-target Single-frequency threshold