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Flexible assistance strategy of lower limb rehabilitation exoskeleton based on admittance model

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Science China(Technological Sciences) 2024年第3期67卷 823-834页

作者： KOU JianGe WANG YiXuan chen ZhenLei SHI Yan GUO qing XU Meng School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China School of Aeronautics and Astronautics University of Electronic Science and Technology of ChinaChengdu 611731China Department of Musculoskeletal Tumor Senior Department of Orthopedicsthe Fourth Medical Centerof PLA GeneralHospitalBeijing 100853China

Exercise training based on exoskeleton is an effective rehabilitation method for stroke patients. However, some rehabilitation exoskeletons still have poor wearable performance and obvious human-robot impedance during training, which easily cause secondary injuries to the patients. In this study, a variable admittance control strategy is proposed to improve the operator's wearable comfort, which can adapt to different operators by regulating admittance parameters. The admittance controller has two feedback loops: the position inner-loop and the admittance outer-loop. Meanwhile, the exoskeleton Lagrange model is constructed with unknown friction disturbance. By using Lyapunov technique and backstepping with state observer, the joint position error of exoskeleton is convergence into a zero neighborhood. The effectiveness of the proposed admittance controller is verified by both simulation and experiment. The tracking error of hip and knee joint is less than 4 degrees while the human-robot interaction torque is constrained in a tolerable range of the operator.

关键词： human-robot interaction exoskeleton backstepping admittance control

Cross-species transmission and host range genes in poxviruses

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Virologica Sinica 2024年第2期39卷 177-193页

作者： chen-Hui Yang A-ling Song Ye Qiu Xing-Yi Ge College of Biology Hunan Provincial Key Laboratory of Medical VirologyHunan UniversityChangsha410012China

The persistent epidemic of human mpox, caused by mpox virus (MPXV), raises concerns about the future spread ofMPXV and other poxviruses. MPXV is a typical zoonotic virus which can infect human and cause smallpox-likesymptoms. MPXV belongs to the Poxviridae family, which has a relatively broad host range from arthropods tovertebrates. Cross-species transmission of poxviruses among different hosts has been frequently reported andresulted in numerous epidemics. Poxviruses have a complex linear double-strand DNA genome that encodeshundreds of proteins. Genes related to the host range of poxvirus are called host range genes (HRGs). This reviewbriefly introduces the taxonomy, phylogeny and hosts of poxviruses, and then comprehensively summarizes thecurrent knowledge about the cross-species transmission of poxviruses. In particular, the HRGs of poxvirus aredescribed and their impacts on viral host range are discussed in depth. We hope that this review will provide acomprehensive perspective about the current progress of researches on cross-species transmission and HRGvariation of poxviruses, serving as a valuable reference for academic studies and disease control in the future.

关键词： Poxvirus Host range gene(HRG) Host spectrum Cross-species transmission

A Matching Algorithm with Reinforcement Learning and Decoupling Strategy for Order Dispatching in On-Demand Food Delivery

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Tsinghua Science and Technology 2024年第2期29卷 386-399页

作者： Jingfang chen ling Wang Zixiao Pan Yuting Wu Jie Zheng Xuetao Ding Department of Automation Tsinghua UniversityBeijing 100084China Department of Delivery Technology MeituanBeijing 100102China

The on-demand food delivery(OFD)service has gained rapid development in the past decades but meanwhile encounters challenges for further improving operation *** order dispatching problem is one of the most concerning issues for the OFD platforms,which refer to dynamically dispatching a large number of orders to riders reasonably in very limited decision *** solve such a challenging combinatorial optimization problem,an effective matching algorithm is proposed by fusing the reinforcement learning technique and the optimization ***,to deal with the large-scale complexity,a decoupling method is designed by reducing the matching space between new orders and ***,to overcome the high dynamism and satisfy the stringent requirements on decision time,a reinforcement learning based dispatching heuristic is *** be specific,a sequence-to-sequence neural network is constructed based on the problem characteristic to generate an order priority ***,a training approach is specially designed to improve learning ***,a greedy heuristic is employed to effectively dispatch new orders according to the order priority *** real-world datasets,numerical experiments are conducted to validate the effectiveness of the proposed *** results show that the proposed algorithm can effectively solve the problem by improving delivery efficiency and maintaining customer satisfaction.

关键词： order dispatching on-demand delivery reinforcement learning decoupling strategy sequence-to-sequence neural network

Thermal stability of permafrost under U-shaped crushed rock embankment of the qinghai-Tibet Railway

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Advances in Climate Change Research 2024年第1期15卷 158-169页

作者： Kun-Ming XU Guan-Li JIANG Ji chen qing-Bai WU State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Beiluhe Observation Station of Frozen Soil Environment and Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China

The U-shaped crushed rock embankment(UCRE),of which widely utilized in the permafrost regions along the qinghai-Tibet Railway,has the capability to rapidly reduce the ground temperature of the underlying ***,there remains uncertainty regarding the adaptation of UCRE to climate change and its long-term cooling *** study focuses on nine UCRE monitoring sites along the qinghai-Tibet Railway to analyze the dynamic variations of the ground temperature underlying permafrost from 2006 to *** efficiency of UCRE in stabilizing permafrost temperature in different permafrost zones is evaluated by considering the permafrost table,ground temperature,and MAGT,as well as the temperature difference between the top and bottom of the crushed rock layer and the ground temperature variation index(GTVI).The results show that UCRE is suitable for application in extremely unstable warm permafrost regions where the MAGT is higher than-0.5℃.Moreover,UCRE effectively diminishes the disparity in permafrost thermal stability between the sunny and shaded shoulders of the *** short-term and long-term effect of cooling permafrost is experiencing a change related with permafrost ***,in stable cold permafrost regions with MAGT lower than-1.5℃,the long-term cooling effect of UCRE on permafrost seems to gradually di-minishes,but UCRE continues to fulfill the role of stabilizing the underlying permafrost thermal state over the *** results show that UCRE can quickly restore and stabilize the thermal state of permafrost in the early stages of construction,and adapt to the influence of future climate *** findings provide important guidance for understanding the variations of permafrost thermal stability beneath the embankment in permafrost regions,as well as for improving the embankment stability and operational safety of the qinghai-Tibet Railway.

关键词： qinghai-Tibet Railway U-shaped crushed rock embankment Climate change Permafrost zone Ground temperature variation index Long-term coolingrole

Real-time arrival picking of rock microfracture signals based on convolutional-recurrent neural network and its engineering application

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 761-777页

作者： Bing-Rui chen Xu Wang Xinhao Zhu qing Wang Houlin Xie State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Accurately picking P-and S-wave arrivals of microseismic(MS)signals in real-time directly influences the early warning of rock mass failure.A common contradiction between accuracy and computation exists in the current arrival picking ***,a real-time arrival picking method of MS signals is constructed based on a convolutional-recurrent neural network(CRNN).This method fully utilizes the advantages of convolutional layers and gated recurrent units(GRU)in extracting short-and long-term features,in order to create a precise and lightweight arrival picking ***,the synthetic signals with field noises are used to evaluate the hyperparameters of the CRNN model and obtain an optimal CRNN *** actual operation on various devices indicates that compared with the U-Net method,the CRNN method achieves faster arrival picking with less performance *** application of large underground caverns in the Yebatan hydropower station(YBT)project shows that compared with the short-term average/long-term average(STA/LTA),Akaike information criterion(AIC)and U-Net methods,the CRNN method has the highest accuracy within four sampling points,which is 87.44%for P-wave and 91.29%for S-wave,*** sum of mean absolute errors(MAESUM)of the CRNN method is 4.22 sampling points,which is lower than that of the other *** the four methods,the MS sources location calculated based on the CRNN method shows the best consistency with the actual failure,which occurs at the junction of the shaft and the second ***,the proposed method can pick up P-and S-arrival accurately and rapidly,providing a reference for rock failure analysis and evaluation in engineering applications.

关键词： Rock mass failure Microseismic event P-wave arrival S-wave arrival Deep learning

Privacy Protection for Blockchain-Based Healthcare IoT Systems: A Survey

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IEEE/CAA Journal of Automatica Sinica 2024年第8期11卷 1757-1776页

作者： Minfeng Qi Ziyuan Wang qing-Long Han Jun Zhang Shiping chen Yang Xiang School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyHawthorn3122VictoriaAustralia Faculty of Data Science City University of MacaoMacaoChina CSIRO Data61 SydneyNew South WalesAustralia

To enable precision medicine and remote patient monitoring,internet of healthcare things(IoHT)has gained significant interest as a promising *** the widespread use of IoHT,nonetheless,privacy infringements such as IoHT data leakage have raised serious public *** the other side,blockchain and distributed ledger technologies have demonstrated great potential for enhancing trustworthiness and privacy protection for IoHT *** this survey,a holistic review of existing blockchain-based IoHT systems is conducted to indicate the feasibility of combining blockchain and IoHT in privacy *** addition,various types of privacy challenges in IoHT are identified by examining general data protection regulation(GDPR).More importantly,an associated study of cutting-edge privacy-preserving techniques for the identified IoHT privacy challenges is ***,several challenges in four promising research areas for blockchain-based IoHT systems are pointed out,with the intent of motivating researchers working in these fields to develop possible solutions.

关键词： Blockchain internet of healthcare things(IoHT) privacy-preserving techniques(PPTs).

Enhancement of comprehensive properties of Nb-Si based in-situ composites by Ho rare earth doping

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Rare Metals 2024年第9期43卷 4508-4520页

作者： Wei Wei Qi Wang Rui-Run chen Chao-Wen Zheng Yan-qing Su National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China

This study examines the microstructure,mechanical properties(with a focus on room-temperature toughness),and oxidation resistance of Ho-doped NbDSi based in-situ *** base alloy consists of the coarse primary Nb_(5)Si_(3)phase and the Nb_(5)Si_(3)+Nbss(Nb solid solution)eutectic *** doping influences the solidification *** the Ho doping is higher than0.2 at%,the alloys transform into eutectic *** can be solid-solved in trace amounts in the Nbss ***,most of Ho forms a stable Ho oxide phase,which alleviates oxygen contamination problem to some ***,the interface separation between Ho oxide and other phases reduces the plastic deformation ***,with 0.4 at%Ho doping,the K_(Q)value is18.03 MPa·m^(1/2),which is 31.1%higher than that of the base *** strength of the Ho-doped alloys does not deteriorate with an increase in ***,the large network-like Ho_(2)O_(3)in the 0.8Ho alloy causes a decrease in toughness and *** addition,the Ho oxide phase effectively blocks the inward oxygen *** 0.8 at%Ho doping,the oxidation mass gain per unit area is 10.16 mg·cm^(2),which is 39.7%lower than that of the base alloy.

关键词： Nb-Si based composites Rare earth elements Ho Microstructure Properties

Self-assembly Induced by Complexation of Diblock Copolyelectrolytes and Oppositely Charged Homopolymers

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Chinese Journal of Polymer Science 2024年第9期42卷 1321-1332,I0006页

作者： ling Zhao Zhi-Yuan Yin Jia-Di Jiang Er-Qiang chen Shuang Yang Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCenter for Soft Mater Science and EngineeringCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

We investigate the solution self-assembly of a mixture of positively charged homopolymers and AB diblock copolymers,in which the A blocks are negatively charged,and the B blocks are *** electrostatic complexation between oppositely charged polymers drives the formation of many ordered *** microstructures and phase diagrams are calculated using self-consistent field theory(SCFT)based on an ion-pair model with an equilibrium constant K to characterize the strength of binding between positively and negatively charged *** effects of the charge ratio,representing the ratio of charges from the homopolymer over all charges from polymers in the system,on the ordered structure are systematically studied,both for hydrophobic and hydrophilic A *** charge ratio plays an important role in determining the phase boundaries in the phase diagram of salt concentration versus polymer *** also provide information about the varying tendency of the domain spacing and core size of the spherical phase when the charge ratio is changed,and the results are in good agreement with *** studies provide a deep understanding of the self-assembled microstructures of oppositely charged diblock copolymer-homopolymer systems.

关键词： Self-assembly Polyelectrolyte complexation Self-consistent field theory Ion-pair

Role of adaptation measures in addressing heatwave exposure in China

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Advances in Climate Change Research 2024年第1期15卷 148-157页

作者： Qin-Mei HAN qing-chen CHAO Shao SUN Pei-Jun SHI National Climate Centre China Meteorological AdministrationBeijing 100081China State Key Laboratoryof Severe Weather Chinese Academy of Meteorological Sciences Beijing 0o08lChina Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China

Heatwave exposure has increased dramatically because of climate warming and population growth,along with their interactive ***,effective adaptation measures can reduce these ***,the dynamic changes,regional inequality in adaptive capacity and their potential contributions to reducing exposure in the future remain *** study quantifies the impact of adaptive capacity and underscores regional variations in heatwave magnitudes,population exposure and adaptation levels in *** projected the future adaptive capacity using air-conditioner penetration,factoring in climate cooling requirements and individuals'purchasing *** population and gross domestic product(GDP)data from four Shared Socioeconomic Pathways(SSP1,SSP2,SSP3 and SSP5)and daily temperature data from four SSP-based emission scenarios(SSP1-2.6,SSP2-4.5,SSP3-7.0 and SSP5-8.5),we estimated heatwave duration,population exposure and avoided impacts through adaptation across China and its *** show a substantial increase in heatwave duration in Southwest and Southern China,especially under the SSP5-8.5 scenario,with a projection of 163.2±36.7 d during *** the SSP3|SSP3-7.0 scenario,total exposure reaches 156.4±76.8 billion person d per year,which is the highest among all scenarios and 23 times greater than that in 1986-2005 without *** considering adaptation measures,a noteworthy reduction in population exposure is observed,especially in the SSP3|SSP3-7.0 and SSP5JSSP5-8.5 scenarios,with reductions of(62.6±3.9)%and(65.8±5.1)%,respectively,compared with the scenario without adaptation during *** regional disparities in avoided impacts are also evident,with variations of up to 50%across different *** implementation of effective and environmentally friendly adaptation measures can notably address climate change,thereby alleviating the profound threats posed to human well-being.

关键词： Heatwaves Population exposure Adaptation Future projection China