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Assessment of tree-ring mercury radial translocation and age effect in Masson pine:Implications for historical atmospheric mercury reconstruction

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Journal of Environmental Sciences 2024年第4期138卷 266-276页

作者： Xu Liu Xun wang Dingyong wang College of Resources and Environment Southwest UniversityChongqing 400715China State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China

The tree ring has been regarded as an emerging archive to reconstruct historical atmospheric mercury(Hg)trends,but with the large knowledge gaps in the *** this study,we comprehensively evaluated the Hg source,radial translocation and age effect of Masson pine(Pinus massoniana)tree ring at *** in Chongqing,to assess the suitability of such tree ring as the archive of atmospheric *** showed that distinct variabilities among Masson pine tree-ring Hg concentration *** Hg concentration significantly increased along with stem height(P<0.05),indicating the Hg in tree rings mainly derived from foliage uptake atmospheric *** found a distinct age effect that the tree ring of young trees had the higher Hg ***,we used the advection-diffusion model to demonstrate how Hg concentration shifted by the advection or/and diffusion in tree *** modeling results showed that the advection induced radial translocation during the young growth period of tree was a plausible mechanism to result in the tree-ring Hg record largely different from the trend of anthropogenic Hg emissions in *** finally suggest that in further Hg dendrochemistry,better discarding the tree-ring Hg profile of the young growth period to reduce impacts of the radial translocation and age effect.

关键词： Masson pine Tree-ring mercury Radial translocation Tree age effect

FlowGANAnomaly: Flow-Based Anomaly Network Intrusion Detection with Adversarial Learning

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Chinese Journal of Electronics 2024年第1期33卷 58-71页

作者： Zeyi LI Pan wang Zixuan wang School of Computer Science Nanjing University of Posts and Telecommunications School of Modern Posts Nanjing University of Posts and Telecommunications School of Internet of Things Nanjing University of Posts and Telecommunications

In recent years, low recall rates and high dependencies on data labelling have become the biggest obstacle to developing deep anomaly detection(DAD) techniques. Inspired by the success of generative adversarial networks(GANs) in detecting anomalies in computer vision and imaging, we propose an anomaly detection model called Flow GANAnomaly for detecting anomalous traffic in network intrusion detection systems(NIDS). Unlike traditional GAN-based approaches, which are composed of a flow encoder, a convolutional encoder-decoder-encoder, a flow decoder and a convolutional encoder, the architecture of this model consists of a generator(G) and a discriminator(D).Flow GANAnomaly maps the different types of traffic feature data from separate datasets to a uniform feature space,thus can capture the normality of network traffic data more accurately in an adversarial manner to mitigate the problem of the high dependence on data labeling. Moreover, instead of simply detecting the anomalies by the output of D, we proposed a new anomaly scoring method that integrates the deviation between the output of two Gs’ convolutional encoders with the output of D as weighted scores to improve the low recall rate of anomaly detection. We conducted several experiments comparing existing machine learning algorithms and existing deep learning methods(Auto Encoder and VAE) on four public datasets(NSL-KDD, CIC-IDS2017, CIC-DDo S2019, and UNSW-NB15). The evaluation results show that Flow GANAnomaly can significantly improve the performance of anomaly-based NIDS.

关键词： Deep learning Machine learning algorithms Computational modeling Network intrusion detection Imaging Telecommunication traffic Generative adversarial networks

Toward tunable shape memory effect of NiTi alloy by grain size engineering:A phase field study

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Journal of Materials Science & Technology 2024年第1期168卷 276-289页

作者： Bo Xu Chong wang Qingyuan wang Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan ProvinceSichuan UniversityChengdu 610065China Department of Mechanical Science and Engineering College of Architecture and EnvironmentSichuan UniversityChengdu 610065China Key Laboratory of Deep Underground Science and Engineering (Sichuan University)Ministry of EducationChengdu 610065China

The inelastic deformations of shape memory alloys(SMAs)always show poor controllability due to the avalanche-like martensite transformation,and the effective control for the deformation of precision de-vices has been not yet *** this work,the phase field method was used to investigate the shape memory effects(SMEs)of NiTi SMAs undergoing grain size(GS)engineering,to obtain tunable one-way and stress-assisted two-way SMEs(OWSME and SATWSME).The OWSME and SATWSME of the systems with various gradient-nanograin structures and bimodal grain structure,as well as that with geometric gradients were *** simulated results indicate that due to the GS dependences of martensite transformation and reorientation,the occurrence and expansion of martensite reorientation,martensite transformation and its reverse can be efficaciously controlled via the GS *** combining the GS engineering and geometric gradient design,since the effects of GS and stress gradient can be su-perimposed or competing,and the responses of martensite reorientation,martensite transformation and its reverse to this are different,the OWSME and SATWSME of the geometrically graded systems with various nanograin structures can exhibit different improvements in *** short,the reorienta-tion hardening modulus during OWSME is increased and the transformation temperature window during SATWSME is widened by GS engineering,indicating the improved controllability of *** optimal GS engineering schemes revealed in this work provide the basic reference and guidance for designing tun-able SMEs and producing NiTi-based driving devices catering to desired functional performance in various engineering fields.

关键词： Phase field NiTi Shape memory effect Grain size engineering Geometric gradient

Sub-Nyquist sampling-based wideband spectrum sensing:a compressed power spectrum estimation approach

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Frontiers of Computer Science 2024年第2期18卷 139-145页

作者： Jilin wang Yinsen HUANG Bin wang National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of ChinaChengdu 611731China

In this paper,we introduce a sub-Nyquist sampling-based receiver architecture and method for wideband spectrum *** of recovering the original wideband analog signal,the proposed method aims to directly reconstruct the power spectrum of the wideband analog signal from sub-Nyquist *** that power spectrum alone is sufficient for wideband spectrum *** only the covariance matrix of the wideband signal is needed,the proposed method,unlike compressed sensing-based methods,does not need to impose any sparsity requirement on the frequency *** proposed method is based on a multi-coset sampling *** exploiting the inherent sampling structure,a fast compressed power spectrum estimation method whose primary computational task consists of fast Fourier transform(FFT)is *** results are presented to show the effectiveness of the proposed method.

关键词： wideband spectrum sensing sub-Nyquist multicoset sampling FCPSE

Multiple-stage spatial-temporal cooperative guidance without time-to-go estimation

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Chinese Journal of Aeronautics 2024年第9期37卷 399-416页

作者： Chunyan wang Weilin wang Wei DONG Jianan wang Fang DENG School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China National Key Lab of Autonomous Intelligent Unmanned Systems Beiing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

This paper investigates the spatial-temporal cooperative guidance problem for multiple flight vehicles without relying on time-to-go ***,a two-stage cooperative guidance strategy,namely the cooperative guidance and the Proportional Navigation Guidance(PNG)stage strategy,is developed to realize the spatial-temporal constraints in two *** the former stage,two controllers are designed and superimposed to satisfy both impact time consensus and impact angle *** the convergent conditions are satisfied,the flight vehicles will switch to the PNG stage to ensure zero miss *** further extend the results to three dimensions,a planar pursuit guidance stage is additionally imposed at the beginning of *** to the inde-pendence of time-to-go estimation,the proposed guidance strategy possesses great performance in satisfying complex spatial-temporal constraints even under flight speed ***,several numerical simulations are implemented to verify the effectiveness and advantages of the proposed results under different scenarios.

关键词： Cooperative guidance Guided missiles Impact time consensus Impact angle constraint Spatial-temporal cooperative guidance

A novel triple periodic minimal surface-like plate lattice and its data-driven optimization method for superior mechanical properties

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 217-238页

作者： Yanda wang Yanping LIAN Zhidong wang Chunpeng wang Daining FANG State Key Laboratory for Turbulence and Complex Systems&Center for Applied Physics and Technology College of EngineeringPeking UniversityBeijing 100871China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

Lattice structures can be designed to achieve unique mechanical properties and have attracted increasing attention for applications in high-end industrial equipment,along with the advances in additive manufacturing(AM)*** this work,a novel design of plate lattice structures described by a parametric model is proposed to enrich the design space of plate lattice structures with high connectivity suitable for AM *** parametric model takes the basic unit of the triple periodic minimal surface(TPMS)lattice as a skeleton and adopts a set of generation parameters to determine the plate lattice structure with different topologies,which takes the advantages of both plate lattices for superior specific mechanical properties and TPMS lattices for high connectivity,and therefore is referred to as a TPMS-like plate lattice(TLPL).Furthermore,a data-driven shape optimization method is proposed to optimize the TLPL structure for maximum mechanical properties with or without the isotropic *** this method,the genetic algorithm for the optimization is utilized for global search capability,and an artificial neural network(ANN)model for individual fitness estimation is integrated for high efficiency.A set of optimized TLPLs at different relative densities are experimentally validated by the selective laser melting(SLM)fabricated *** is confirmed that the optimized TLPLs could achieve elastic isotropy and have superior stiffness over other isotropic lattice structures.

关键词： lattice structure triple periodic minimal surface(TPMS) plate lattice structural optimization machine learning

Adaptive Barrier-Lyapunov-Functions Based Control Scheme of Nonlinear Pure-Feedback Systems with Full State Constraints and Asymptotic Tracking Performance

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Journal of Systems Science & Complexity 2024年第3期37卷 965-984页

作者： NIU Ben wang Xiaoan wang Xiaomei wang Xinjun LI Tao Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China School of Information Science and Engineering Shandong Normal UniversityJinan 250014China School of Mathematics Southeast UniversityNanjing 211189China School of Automation Nanjing University of Information Science and TechnologyNanjing 210044China

In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state *** to the coexist of the non-affine structure and full state constraints,it is very difficult to construct a desired controller for the considered *** to the mean value theorem,the authors transform the pure-feedback system into a system with strict-feedback structure,so that the well-known backstepping method can be ***,in the backstepping design process,the BLFs are employed to avoid the violation of the state constraints,and neural networks(NNs)are directly used to online approximate the unknown packaged nonlinear *** presented controller ensures that all the signals in the closed-loop system are bounded and the tracking error asymptotically converges to ***,it is shown that the constraint requirement on the system will not be violated during the ***,two simulation examples are provided to show the effectiveness of the proposed control scheme.

关键词： Asymptotic tracking control barrier Lyapunov functions full state constraints nonlinear pure-feedback systems

The Coarse l^(p)-Novikov Conjecture and Banach Spaces with Property(H)

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Chinese Annals of Mathematics,Series B 2024年第2期45卷 193-220页

作者： Huan wang Qin wang Research Center for Operator Algebras School of Mathematical SciencesEast China Normal UniversityShanghai 200241China Key Laboratory of MEA Ministry of Educationand Shanghai Key Laboratory of PMMPEast China Normal UniversityShanghai 200241China

In this paper,for 1

关键词： The coarse l^(p)-Novikov conjecture Banach spaces with Property(H) Coarse geometry K-Theory

Improvement of the Subcooling Problem of Sodium Acetate Trihydrate by a Combination of Stirring or Internal Electric Field and Nucleating Agent

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Journal of Thermal Science 2024年第06期33卷 2235-2244页

作者： wang Chuang wang Suyaola LIU Pengcheng CHENG Xingxing wang Zhiqiang School of Energy and Power Engineering Shandong University National Engineering Laboratory for Reducing Emissions from Coal Combustion

Energy storage devices are the hub of a multi-energy complementary distributed energy *** salts are the most suitable phase change material for energy storage devices,but subcooling is the main obstacle to their *** requires a driving force so the use of nucleating agents alone does not reduce subcooling to a very low *** address this issue,this paper first screened nucleating agents and then further reduced the subcooling of sodium acetate trihydrate in conjunction with stirring or direct *** effects of rotor mass,rotational speed,direct current voltage,and electrode material on nucleation were ***,the stability of the composite phase change material in the presence of simultaneous stirring and energization was *** results showed that the addition of 1.5% in weight of disodium hydrogen phosphate dodecahydrate to sodium acetate trihydrate can reduce the subcooling to about 2.3℃.Continued addition of stirring or electricity can reduce the subcooling of sodium acetate trihydrate to within 0.5℃ or even eliminate *** higher the momentum of the stirring,the better the improvement in subcooling,phase separation,and thermal *** higher the direct current voltage,the better the nucleation effect,but the electrode life will be *** silver electrode has the best nucleation *** new material was produced in the solution after 100 cycles in the presence of both stirring and direct *** melting point of the phase change material was increased by 0.2℃ and the latent heat value decreased by 1.8%,still with good *** trace of deionized water should be added to the phase change material in subsequent studies to compensate for the consumption of water by the anodic elution.

关键词： internal electric field phase change material sodium acetate trihydrate stirring subcooling