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The relationship between three-dimensional coseismic displacement and distribution of coseismic landslides

Science China Earth Sciences 2023年第7期66卷 1583-1602页

作者： ru liu Teng WANG School of Earth and Space Sciences Peking UniversityBeijing 100871China Hebei Hongshan National Geophysical Observatory for Thick Sediments and Seismic Hazards Peking UniversityBeijing 100871China

In mountainous areas,landslides induced by destructive earthquakes are one of the main causes of human casualties,which is an important link in the chain of earthquake hazards.Earthquake-triggered landslides are mainly controlled by three factors,namely seismic property,topography,and geology.Many studies have been conducted on these controlling factors of earthquake-triggered landslides.However,little is known about the effect of coseismic displacement on the distribution of landslides under different slope aspects and slope angles,hindering our understanding of the mechanism of inducing landslides by the combination of surface displacement and slope geometry at the local scale and leading to controversial opinions about the abnormal number of earthquake-triggered landslides in several cases.Here,we took the 2008 Wenchuan M_(w) 7.9 earthquake in China,the 2015 Gorkha M_(w) 7.8 earthquake in Nepal,and the 2016 Kaikōura M_(w) 7.8 earthquake in New Zealand as examples to investigate the relationship between the distribution of large earthquake-triggered landslides and the three-dimensional (3D)coseismic displacement field.We divided the landslide-prone area around the epicenter into regular grids and calculated the 3D coseismic displacement in each grid according to the radar satellite images and slip distribution model.Then,the 3D coseismic displacement was projected to two coordinate systems related to the slope where the landslides were located for statistical analysis.We determined that the surface uplift perpendicular to the slope is more likely to induce landslides,particularly when combined with large slope angles.Meanwhile,the number of landslides will be significantly reduced where the subsidence occurs.Regardless of uplift or subsidence,landslides are more likely to occur when the direction of coseismic horizontal displacement is far from the slope.The larger the slope angles are,the greater the effects of horizontal displacement and slope aspect.A dominant slope aspect also exists for earthquake-triggere

关键词： Coseismic landslides Three-dimensional coseismic displacement InSAR Landslide risk assessment

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Recent advances in ultrasound-controlled fluorescence technology for deep tissue optical imaging

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Journal of Pharmaceutical Analysis 2022年第4期12卷 530-540页

作者： rui-Lin liu ru-Qian Cai School of Pharmacy Xuzhou Medical UniversityXuzhou221004China Department of Pharmaceutical Analysis School of PharmacyXi'an Jiaotong UniversityXi'an710061China

Fluorescence imaging is a noninvasive and dynamic real-time imaging technique;however,it exhibits poor spatial resolution in centimeter-deep tissues because biological tissues are highly scattering media for optical radiation.The recently developed ultrasound-controlled fluorescence(UCF)imaging is a novel imaging technique that can overcome this bottleneck.Previous studies suggest that the effective contrast agent and sensitive imaging system are the two pivotal factors for generating high-resolution UCF images ex vivo and/or in vivo.Here,this review highlights the recent advances(2015e2020)in the design and synthesis of contrast agents and the improvement of imaging systems to realize high-resolution UCF imaging of deep tissues.The imaging performances of various UCF systems,including the signal-to-noise ratio,imaging resolution,and imaging depth,are specifically discussed.In addition,the challenges and prospects are highlighted.With continuously increasing research interest in this field and emerging multidisciplinary applications,UCF imaging with higher spatial resolution and larger imaging depth may be developed shortly,which is expected to have a far-reaching impact on disease surveillance and/or therapy.

关键词： Ultrasound-controlled fluorescence imaging Temperature-sensitive NIR probes High-resolution Deep tissue Molecular diagnosis

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Potential use of large language models for mitigating students’problematic social media use:ChatGPT as an example

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World Journal of Psychiatry 2024年第3期14卷 334-341页

作者： Xin-Qiao liu Zi-ru Zhang School of Education Tianjin UniversityTianjin 300350China

The problematic use of social media has numerous negative impacts on individuals'daily lives,interpersonal relationships,physical and mental health,and more.Currently,there are few methods and tools to alleviate problematic social media,and their potential is yet to be fully realized.Emerging large language models(LLMs)are becoming increasingly popular for providing information and assistance to people and are being applied in many aspects of life.In mitigating problematic social media use,LLMs such as ChatGPT can play a positive role by serving as conversational partners and outlets for users,providing personalized information and resources,monitoring and intervening in problematic social media use,and more.In this process,we should recognize both the enormous potential and endless possibilities of LLMs such as ChatGPT,leveraging their advantages to better address problematic social media use,while also acknowledging the limitations and potential pitfalls of ChatGPT technology,such as errors,limitations in issue resolution,privacy and security concerns,and potential overreliance.When we leverage the advantages of LLMs to address issues in social media usage,we must adopt a cautious and ethical approach,being vigilant of the potential adverse effects that LLMs may have in addressing problematic social media use to better harness technology to serve individuals and society.

关键词： Problematic use of social media Social media Large language models ChatGPT Chatbots

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On Submanifolds of the Unit Sphere with Vanishing Mobius Form and Parallel Para-Blaschke Tensor

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Acta Mathematica Sinica,English Series 2022年第2期38卷 347-370页

作者： Hong ru SONG Xi Min liu School of Mathematical Sciences Dalian University of TechnologyDalian 116024P.R.China

The para-Blaschke tensor are extended in this paper from hypersurfaces to general higher codimensional submanifolds in the unit sphere S^(n),which is invariant under the Mobius transformations on Sn.Then some typical new examples of umbilic-free submanifolds in Snwith vanishing Mobius form and a parallel para-Blaschke tensor of two distinct eigenvalues,D_(1) and D_(2),are constructed.The main theorem of this paper is a simple characterization of these newly found examples in terms of the eigenvalues D_(1) and D_(2).

关键词： Parallel Blaschke tensor vanishing Mobius form constant scalar curvature parallel mean curvature vector field

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Magnetoelectric Properties of Piezoelectric—Piezomagnetic Composites with Elliptical Nanofibers

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Acta Mechanica Solida Sinica 2020年第3期33卷 368-380页

作者： ru Tian Jinxi liu Xianglin liu Department of Engineering Mechanics Shijiazhuang Tiedao UniversityShijiazhuang 050043China Institute of Engineering Mechanics Beijing Jiaotong UniversityBeijing 100044China Hebei Key Laboratory of Mechanics of Intelligent Materials and Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Based on the surface/interface theory,the effective magnetoelectric(ME)properties of piezoelectric(PE)-piezomagnetic(PM)composites with elliptical nanofibers are investigated analytically.Using the complex function theory,conformal mapping and the Mori-Tanaka mean-field method,the solutions of magneto-electro-elastic(MEE)fields are obtained,which satisfy both the interface and the single-valued conditions.The closed-form expression of the ME coefficient of the composites shows that the effect of ME coefficient is related to the interface parameters,elliptical aspect ratio,material properties of both fiber and matrix and the fiber volume fraction.Numerical calculation shows that by properly selecting some of these parameters,the effective ME coefficient could be substantially enhanced.

关键词： Surface/interface effect Effective magnetoelectric coefficient Elliptical nanofiber Piezoelectric Piezomagnetic

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Design and Aerodynamic Analysis of Dragonfly-like Flapping Wing Micro Air Vehicle

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Journal of Bionic Engineering 2022年第2期19卷 343-354页

作者： Yanjuan Hu Weiwei ru Qiang liu Zhanli Wang School of Mechatronic Engineering Changchun University of TechnologyChangchun 130012China School of Mechanical and Aerospace Engineering Jilin UniversityChangchun 130022China

Dragonflies have naturally high flying ability and flight maneuverability,making them more adaptable to harsh ecological environments.In this paper,a flapping wing bionic air vehicle with three-degrees-of-freedom is designed and manufactured by simulating the flight mode of dragonfly.Firstly,the body structure of dragonfly was analyzed,and then the design scheme of flapping wing micro air vehicle was proposed based on the flight motion characteristics and musculoskeletal system of dragonfly.By optimizing the configuration and using Adams to do kinematic simulation,it is shown that the designed structure can make the wings move in an“8”shape trajectory,and the motion in three directions can maintain good consistency,with good dynamic performance.Based on CFD simulation method,we analyzed that the wing has the conditions to achieve flight with good aerodynamic performance at the incoming flow speed of 5 m s^(-1)and frequency of 4 Hz,and studied the effects of angle of attack and flutter frequency on the aerodynamic performance of the aircraft.Finally,the force measurement test of the aircraft prototype is carried out using a force balance and a small wind tunnel.The test results show that the prototype can provide the average lift of 3.62 N and the average thrust of 2.54 N,which are in good agreement with the simulation results.

关键词： Dragonfy Flapping wing micro air vehicle Three-degrees-of-freedom Aerodynamic performance

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A Compensation Algorithm for Large Element Characterizing the Damage Evolution Process and Its Application to Structure Collisions

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Chinese Journal of Mechanical Engineering 2023年第1期36卷 315-331页

作者： Wen liu Lele Zhang Yifan ru Geng Chen Weiyuan Dou School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China National International Science and Technology Cooperation Base Beijing Jiaotong UniversityBeijing100044China

When simulating the process from elastic–plastic deformation,damage to failure in a metal structure collision,it is necessary to use the large shell element due to the calculation efficiency,but this would affect the accuracy of damage evolution simulation.The compensation algorithm adjusting failure strain according to element size is usually used in the damage model to deal with the problem.In this paper,a new nonlinear compensation algorithm between failure strain and element size was proposed,which was incorporated in the damage model GISSMO(Generalized incremental stress state dependent damage model)to characterize ductile fracture.And associated material parameters were calibrated based on tensile experiments of aluminum alloy specimens with notches.Simulation and experimental results show that the new compensation algorithm significantly reduces the dependence of element size compared with the constant failure strain model and the damage model with the linear compensation algorithm.During the axial splitting process of a circular tubular structure,the new compensation algorithm keeps the failure prediction errors low over the stress states ranging from shear to biaxial tension,and achieves the objective prediction of the damage evolution process.This study demonstrates how the compensation algorithm resolves the contradiction between large element size and fracture prediction accuracy,and this facilitates the use of the damage model in ductile fracture prediction for engineering structures.

关键词： Compensation algorithm Element size Damage model Axial splitting

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Design a Hybrid Energy-Supply for the Electrically Driven Heavy-Duty Hexapod Vehicle

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Journal of Bionic Engineering 2023年第4期20卷 1434-1448页

作者： Zhenyu Xu Haoyuan Yi Dan liu ru Zhang Xin Luo State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan430074China Research Institute Inner Mongolia First Machinery Group Co.LtdBaotou014030China

Increasing the power density and overload capability of the energy-supply units(ESUs)is always one of the most challenging tasks in developing and deploying legged vehicles,especially for heavy-duty legged vehicles,in which significant power fluctuations in energy supply exist with peak power several times surpassing the average value.Applying ESUs with high power density and high overload can compactly ensure fluctuating power source supply on demand.It can avoid the ultra-high configuration issue,which usually exists in the conventional lithium-ion battery-based or engine-generator-based ESUs.Moreover,it dramatically reduces weight and significantly increases the loading and endurance capabilities of the legged vehicles.In this paper,we present a hybrid energy-supply unit for a heavy-duty legged vehicle combining the discharge characteristics of lithium-ion batteries and peak energy release/absorption characteristics of supercapacitors to adapt the ESU to high overload power fluctuations.The parameters of the lithium-ion battery pack and supercapacitor pack inside the ESU are optimally matched using the genetic algorithm based on the energy consumption model of the heavy-duty legged vehicle.The experiment results exhibit that the legged vehicle with a weight of 4.2 tons can walk at the speed of 5 km/h in a tripod gait under a reduction of 35.39%in weight of the ESU compared to the conventional lithium-ion battery-based solution.

关键词： Heavy-duty legged vehicles Hybrid energy-supply unit Power fluctuation Optimal matching of lithium-ion battery pack and supercapacitor pack

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SBFT:A BFT Consensus Mechanism Based on DQN Algorithm for Industrial Internet of Thing

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中国通信:英文版 2023年第10期20卷 185-199页

作者： Ningjie Gao ru Huo Shuo Wang Jiang liu Tao Huang Yunjie liu State Key Laboratory of Networking and Switching Technology Beijing University of Posts and TelecommunicationsBeijing 100876China Faculty of Information Technology Beijing University of TechnologyBeijing 100124China Future Network Research Center Purple Mountain LaboratoriesNanjing 211111China

With the development and widespread use of blockchain in recent years,many projects have introduced blockchain technology to solve the growing security issues of the Industrial Internet of Things(IIoT).However,due to the conflict between the operational performance and security of the blockchain system and the compatibility issues with a large number of IIoT devices running together,the mainstream blockchain system cannot be applied to IIoT scenarios.In order to solve these problems,this paper proposes SBFT(Speculative Byzantine Consensus Protocol),a flexible and scalable blockchain consensus mechanism for the Industrial Internet of Things.SBFT has a consensus process based on speculation,improving the throughput and consensus speed of blockchain systems and reducing communication overhead.In order to improve the compatibility and scalability of the blockchain system,we select some nodes to participate in the consensus,and these nodes have better performance in the network.Since multiple properties determine node performance,we abstract the node selection problem as a joint optimization problem and use Dueling Deep Q Learning(DQL)to solve it.Finally,we evaluate the performance of the scheme through simulation,and the simulation results prove the superiority of our scheme.

关键词： Industrial Internet of Things Byzantine fault tolerance speculative consensus mechanism Markov decision process deep reinforcement learning

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NASICON solid electrolyte coated by indium film for all-solid-state Li-metal batteries

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Tungsten 2022年第4期4卷 316-322页

作者： Yi-Jie liu ru-Yi Fang David Mitlin Materials Science and Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX78712USA

The application of all-solid-state Li-metal batteries with solid oxide electrolytes is hindered by interfacial issues,especially the solid electrolyte/Li-metal interface.This work introduced a uniform indium film layer on the surface of Na^(+)super ionic conductor(NASICON)solid electrolyte Li_(1.5)Al_(0.5)Ge_(1.5)P_(3)O_(12)(LAGP),which promotes the intimate contact between Li metal and solid electrolyte and hinders the side reactions at the interface.Electrochemical impedance spectra show that the battery with coated solid electrolyte presents a smaller interfacial resistance and maintains stability after a long cycling time.By contrast,the baseline battery with a pure LAGP pellet shows a contact loss after cycling with the vibration of interfacial impedance.The Li symmetric cells with indium-modified solid electrolyte present stable cycling behavior over 400 h at 0.1 and 0.2 mA·cm^(−2).The all-solid-state Li-metal batteries with a Li anode,indium coating LAGP and two kinds of cathodes,namely carbon nanotubes(CNTs)and LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811),are prepared and tested.The CNTs cathode for Li-O2 and Li-air batteries has a higher specific capacity than traditional Li-ion battery cathodes.The Li-NCM811 batteries deliver an initial Coulombic efficiency of about 75%,with 82%capacity retention after 20 cycles.

关键词： All-solid-state batteries Solid electrolyte Li1.5Al0.5Ge1.5P3O12 Li-metal anode Interfacial chemistry

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