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Research on Anthropomorphic Obstacle Avoidance Trajectory Planning for Adaptive Driving Scenarios Based on Inverse Reinforcement Learning Theory

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Engineering 2024年第2期33卷 133-145页

作者： Jian Wu Yang Yan Yulong liu Yahui liu School of Mechanical and Automotive Engineering Liaocheng UniversityLiaocheng 252000China 2 School of Vehicle and Mobility Tsinghua UniversityBeijing 100084China

The forward design of trajectory planning strategies requires preset trajectory optimization functions,resulting in poor adaptability of the strategy and an inability to accurately generate obstacle avoidance trajectories that conform to real driver behavior *** addition,owing to the strong time-varying dynamic characteristics of obstacle avoidance scenarios,it is necessary to design numerous trajectory optimization functions and adjust the corresponding ***,an anthropomorphic obstacle-avoidance trajectory planning strategy for adaptive driving scenarios is ***,numerous expert-demonstrated trajectories are extracted from the HighD natural driving ***,a trajectory expectation feature-matching algorithm is proposed that uses maximum entropy inverse reinforcement learning theory to learn the extracted expert-demonstrated trajectories and achieve automatic acquisition of the optimization function of the expert-demonstrated ***,a mapping model is constructed by combining the key driving scenario information that affects vehicle obstacle avoidance with the weight of the optimization function,and an anthropomorphic obstacle avoidance trajectory planning strategy for adaptive driving scenarios is ***,the proposed strategy is verified based on real driving *** results show that the strategy can adjust the weight distribution of the trajectory optimization function in real time according to the“emergency degree”of obstacle avoidance and the state of the ***,this strategy can generate anthropomorphic trajectories that are similar to expert-demonstrated trajectories,effectively improving the adaptability and acceptability of trajectories in driving scenarios.

关键词： Obstacle avoidance trajectory planning Inverse reinforcement theory Anthropomorphic Adaptive driving scenarios

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Mitigate noisy data for smart IoT via GAN based machine unlearning

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Science China(Information Sciences) 2024年第3期67卷 62-78页

作者： Zhuo MA Yilong YANG Yang liu Xinjing liu Jianfeng MA School of Cyber Engineering Xidian University State Key Laboratory of Integrated Services Networks (ISN)

With the development of IoT applications, machine learning dramatically improves the utility of variable IoT systems such as autonomous driving. Although the pretrain-finetune framework can cope well with data heterogeneity in complex IoT scenarios, the data collected by sensors often contain unexpected noisy data, e.g., out-of-distribution(OOD) data, which leads to the reduced performance of fine-tuned models. To resolve the problem, this paper proposes Mu GAN, a method that can mitigate the side-effect of OOD data via the generative adversarial network(GAN)-based machine unlearning. Mu GAN follows a straightforward but effective idea to mitigate the performance loss caused by OOD data, i.e., “flashbacking” the model to the condition where OOD data are excluded from model training. To achieve the goal, we design an adversarial game, where a discriminator is trained to identify whether a sample belongs to the training set by observing the confidence score. Meanwhile, a generator(i.e., the target model) is updated to fool the discriminator into believing that the OOD data are not included in the training set but others do. The experimental results show that benefiting from the high unlearning rate(more than 90%) and retention rate(99%), Mu GAN succeeds in lowering the model performance degradation caused by OOD data from 5.88% to 0.8%.

关键词： machine unlearning generative adversarial network out of distribution data Internet of Thing neural network

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Quasi-2D weak lensing cosmological constraints using the PDF-SYM method

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 44-58页

作者： Zhenjie liu Jun Zhang Hekun Li Zhi Shen Cong liu Department of Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai 200240China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

Cosmic shear statistics,such as the two-point correlation function(2PCF),can be evaluated with the PDF-SYM method instead of the traditional weighted-sum *** makes use of the full PDF information of the shear estimators,and does not require weightings on the shear estimators,which can in principle introduce additional systematic *** work presents our constraints on S8and?mfrom the shear-shear correlations using the PDF-SYM *** data we use is from the z-band images of the Dark Energy Camera Legacy Survey(DECa LS),which covers about 10000 deg2with more than 100 million *** shear catalog is produced by the Fourier Quad method,and well tested on the real data itself with the field-distortion *** main approach is called quasi-2D as we do use the photo-z information of each individual galaxy,but without dividing the galaxies into redshift *** mainly use galaxy pairs within the redshift interval between 0.2 and 1.3,and the angular range from 4.7 to 180 *** analysis yields S8=0.762±0.026 and?m=0.234±0.075,with the baryon effects and the intrinsic alignments *** results are robust against redshift *** check the consistency of our results by deriving the cosmological constraints from auto-correlations ofγ1andγ2separately,and find that they are consistent with each other,but the constraints from theγ1component are much weaker than that fromγ*** implies a much worse data quality ofγ1,which is likely due to additional shear uncertainties caused by CCD electronics(according to the survey strategy of DECa LS).We also perform a pure 2D analysis,which gives S8=0.81_(-0.04)^(+0.03)and?m=0.25_(-0.05)^(+0.06).Our findings demonstrate the potential of the PDF-SYM method for precision cosmology.

关键词： weak lensing shear-shear correlations cosmological parameters observations analysis

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Recent advances in halide perovskite memristors:From materials to applications

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Frontiers of physics 2024年第2期19卷 73-104页

作者： Sixian liu Jianmin Zeng Qilai Chen Gang liu Department of Micro/Nano Electronics School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Aerospace Science&Industry Shenzhen(Group)Co.Ltd. Shenzhen 518000China

With the emergence of the Internet of Things(IoT)and the rapid growth of big data generated by edge devices,there has been a growing need for electronic devices that are capable of processing and transmitting data at low power and high *** Complementary Metal-Oxide-Semiconductor(CMOS)devices are nonvolatile and often limited by their ability for certain IoT applications due to their unnecessary power consumption for data movement in von Neuman architecture-based *** has led to a surge in research and development efforts aimed at creating innovative electronic components and systems that can overcome these shortcomings and meet the evolving needs of the information era,which share features such as improved energy efficiency,higher processing speeds,and increased *** are a novel type of electronic device that has the potential to break down the barrier between storage and *** storing data and processing information within the same device,memristors can minimize the need for data movement,which allows for faster processing speeds and reduced energy *** further improve the energy efficiency and reliability of memristors,there has been a growing trend toward diversifying the selection of dielectric materials used in *** perovskites(HPs)have unique electrical and optical properties,including ion migration,charge trapping effect caused by intrinsic defects,excellent optical absorption efficiency,and high charge mobility,which makes them highly promising in applications of *** this paper,we provide a comprehensive overview of the recent development in resistive switching behaviors of HPs and the underlying ***,we summarize the diverse range of HPs,their respective performance metrics,as well as their applications in various ***,we critically evaluate the current bottlenecks and possible opportunities in the future research of HP memristors.

关键词： halide perovskite memristor mechanism neuromorphic computing non-volatile memory

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Peeling of Magneto-responsive Beams with Large Deformation Mediated by the Parallel Magnetic Field

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Acta Mechanica Solida Sinica 2024年第3期37卷 457-467页

作者： Gongqi Cao Zhangna Xue Shiyang liu Yuchen Jin Jianlin liu College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao266580China

Elasto-capillarity phenomena are prevalent in various industrial fields such as mechanical engineering,material science,aerospace,soft robotics,and *** this study,two typical peeling processes of slender beams driven by the parallel magnetic field are investigated based on experimental and theoretical *** first is the adhesion of two parallel beams,and the second is the self-folding of a long *** these two cases,the energy variation method on the elastica is used,and then,the governing equations and transversality boundary conditions are *** is shown that the analytical solutions are in excellent agreement with the experimental *** effects of magnetic induction intensity,distance,and surface tension on the deflection curve and peeling length of the elastica are fully *** results are instrumental in accurately regulating elasto-capillarity in structures and provide insights for the engineering design of programmable microstructures on surfaces,microsensors,and bionic robots.

关键词： Magneto-responsive beam Adhesion and peeling Self-folding Elastica Transversality condition

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Off-Grid Compressed Channel Estimation with Parallel Interference Cancellation for Millimeter Wave Massive MIMO

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China Communications 2024年第3期21卷 51-65页

作者： liu Jinru Tian Yongqing liu Danpu Zhang Zhilong Beijing Laboratory of Advanced Information Network Beijing Key Laboratory of Network System Architecture and ConvergenceBeijing University of Posts and TelecommunicationsBeijing100876China

Millimeter wave(mmWave)massive multiple-input multiple-output(MIMO)plays an important role in the fifth-generation(5G)mobile communications and beyond wireless communication systems owing to its potential of high ***,channel estimation has become very challenging due to the use of massive MIMO antenna ***,the mmWave channel has strong sparsity in the spatial angle domain,and the compressed sensing technology can be used to convert the original channel matrix into the sparse matrix of discrete angle *** the high-dimensional channel matrix estimation is transformed into a sparse recovery problem with greatly reduced computational ***,the path angle in the actual scene appears randomly and is unlikely to be completely located on the quantization angle grid,thus leading to the problem of power ***,multiple paths with the random distribution of angles will bring about serious interpath interference and further deteriorate the performance of channel *** address these off-grid issues,we propose a parallel interference cancellation assisted multi-grid matching pursuit(PIC-MGMP)algorithm in this *** proposed algorithm consists of three stages,including coarse estimation,refined estimation,and inter-path cyclic iterative inter-ference *** specifically,the angular resolution can be improved by locally refining the grid to reduce power leakage,while the inter-path interference is eliminated by parallel interference cancellation(PIC),and the two together improve the estimation *** results show that compared with the traditional orthogonal matching pursuit(OMP)algorithm,the normalized mean square error(NMSE)of the proposed algorithm decreases by over 14dB in the case of 2 paths.

关键词： channel estimation compressed sensing inter-path interference millimeter wave massive MIMO off-grid parallel interference cancellation

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How to Construct a Lower Risk FOF Based on Correlation Network? The Method of Principal Component Risk Parity Asset Allocation

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Journal of Systems Science & Complexity 2024年第3期37卷 1052-1079页

作者： BAI Wei ZHANG Junting liu Haifei liu Kai School of Management and Engineering Nanjing UniversityNanjing 210093China Postdoctoral Workstation of Bank of Jiangsu Co. LtdNanjing 210006China College of Finance Nanjing Agricultural UniversityNanjing 210095China University of Prince Edward Island 550 University AveCharlottetownPE C1A4P3Canada

In order to build a low-risk Fund of Funds(FOF), from the perspective of correlation, the principal component factor is used to improve the traditional risk parity model. Principal component analysis is used to decompose the underlying assets and generate unrelated principal component factors,and then the authors can construct a principal component risk parity portfolio. The proposed empirical results based on China’s mutual fund market show that the performance of principal component risk parity portfolio(PCRPP) is better than that of equal weight portfolio(EWP) and traditional risk parity portfolio(RPP). That is to say, not only the PCRPP in this paper has much lower risk than EWP and RPP, but also slightly better than EWP and RPP in terms of average return. Moreover, the study of dividing the underlying assets shows that the PCRPP in this paper is not sensitive to the underlying assets. The PCRPP in this paper is better than EWP and RPP for both the better performing funds and the worse performing funds. In addition, the empirical results on dynamic portfolio adjustments show that it is not appropriate to adjust asset allocation too frequently when the expected rate of return is calculated using the arithmetic mean.

关键词： Fund of funds(FOF) mutual funds portfolio risk principal component analysis risk parity portfolio

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Modelling analysis embodies drastic transition among global potential natural vegetations in face of changing climate

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Forest Ecosystems 2024年第2期11卷 184-192页

作者： Zhengchao Ren Lei liu Fang Yin Xiaoni liu School of Earth Science and Resources Chang’an UniversityXi’an710054China Research Center of Ecological Construction and Environmental Conservation in Gansu Province Gansu Agricultural UniversityLanzhou730070China State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing100101China School of Land Engineering Chang’an UniversityXi’an710054China College of Pratacultural Science Gansu Agricultural UniversityLanzhou730070China

Potential natural vegetation(PNV)is a valuable reference for ecosystem renovation and has garnered increasing attention ***,there is limited knowledge on the spatio-temporal distributions,transitional processes,and underlying mechanisms of global natural vegetation,particularly in the case of ongoing climate *** this study,we visualize the spatio-temporal pattern and inter-transition procedure of global PNV,analyse the shifting distances and directions of global PNV under the influence of climatic disturbance,and explore the mechanisms of global PNV in response to temperature and precipitation *** achieve this,we utilize meteorological data,mainly temperature and precipitation,from six phases:the Last Inter-Glacial(LIG),the Last Glacial Maximum(LGM),the Mid Holocene(MH),the Present Day(PD),2030(20212040)and 2090(2081–2100),and employ a widely-accepted comprehensive and sequential classification sy–stem(CSCS)for global PNV *** find that the spatial patterns of five PNV groups(forest,shrubland,savanna,grassland and tundra)generally align with their respective ecotopes,although their distributions have shifted due to fluctuating temperature and ***,we observe an unexpected transition between tundra and savanna despite their geographical *** shifts in distance and direction of five PNV groups are mainly driven by temperature and precipitation,although there is heterogeneity among these shifts for each ***,the heterogeneity observed among different global PNV groups suggests that they may possess varying capacities to adjust to and withstand the impacts of changing *** spatio-temporal distributions,mutual transitions and shift tendencies of global PNV and its underlying mechanism in face of changing climate,as revealed in this study,can significantly contribute to the development of strategies for mitigating warming and promoting re-vegetation in degraded regions worldwide.

关键词： Potential natural vegetation Global warming Vegetation classification Predicted model CSCS

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High Energy Efficiency Dynamic Connected Hybrid Precoding for mm Wave Massive MIMO Systems

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China Communications 2024年第5期21卷 36-44页

作者： Du Ruiyan liu Huajing Li Tiangui liu Fulai Lab of Key Technology of Millimeter-wave Large-scale MIMO System Northeastern University at QinhuangdaoQinhuangdao066004China School of Computer Science and Engineering Northeastern UniversityShenyang 110819China

This paper considers a high energy efficiency dynamic connected(HEDC)structure,which promotes the practicability and reduces the power consumption of hybrid precoding system by lowresolution phase shifters(PSs).Based on the proposed structure,a new hybrid precoding algorithm is presented to optimize the energy efficiency,namely,HP-HEDC ***,via a new defined effective optimal precoding matrix,the problem of optimizing the analog switch precoding matrix is formulated as a sparse representation ***,the optimal analog switch precoding matrix can be readily obtained by the branch-and-bound ***,the digital precoding matrix optimization problem is modeled as a dictionary update problem and solved by the method of optimal direction(MOD).Finally,the diagonal entries of the analog PS precoding matrix are optimized by exhaustive search independently since PS and antenna is *** results show that the HEDC structure enjoys low power consumption and satisfactory spectral *** proposed algorithm presents at least 50%energy efficiency improvement compared with other algorithms when the PS resolution is set as 3-bit.

关键词： energy efficiency hybrid precoding mmWave optimized resolution phase shifter

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Cooperative Covert Communication in Multi-Antenna Broadcast Channels

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China Communications 2024年第6期21卷 246-260页

作者： Qiao Sen liu Guangjie Ji Xiaopeng liu Weiwei School of Electrical and Information Engineering Nanjing University of Information Science and TechnologyNanjing 210044China School of Automation Nanjing University of Science and TechnologyNanjing 210094China

With the gradual popularization of 5G communications,the application of multi-antenna broadcasting technology has become ***,this study aims to investigate the wireless covert communication in the two-user cooperative multi-antenna broadcast *** focus on the issue that the deteriorated reliability and undetectability are mainly affected by the transmission *** tackle this issue,we design a scheme based on beamforming to increase the reliability and undetectability of wireless covert communication in the multi-antenna broadcast *** first modeled and analyzed the cooperative multi-antenna broadcasting system,and put forward the target *** we use the SCA(successive convex approximation)algorithm to transform the target problem into a series of convex *** the convex problems are solved and the covert channel capacity is *** order to verify the effectiveness of the scheme,we conducted simulation *** simulation results show that the proposed beamforming scheme can effectively improve the reliability and undetectability of covert communication in multi-antenna broadcast channels.

关键词： beamforming covert communication multi-antenna broadcast channels OFDM

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