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Tracking Nonstationary Streaming Data via Exponentially Weighted Moving Average Stochastic Gradient Descent

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Journal of Systems Science & Complexity 2024年

作者： QIAN Chengde jiang haiyan LIANG Decai School of Statistics and Data Science Nankai University Department of Machine Learning Mohamed Bin Zayed University of Artificial Intelligence (MBZUAI)

In many applications involving data streams, the sequences of data arise from highly dynamic and often unstable real-life processes, rendering untenable the standard assumption that current and future data come from the same distribution. In response, new methodologies, such as dynamic online learning, have been proposed in order to account for the nonstationary features in the data-generating process. Motivated by the stability and statistical efficiency of the notable stochastic approximation method, average stochastic gradient descent(ASGD) in time-invariant systems, the authors propose an exponentially weighted moving average(EWMA)-based stochastic gradient descent(SGD) which accommodates the dynamic structure by introducing a forgetting factor and replacing the simple averaging step in ASGD with an EWMA step. Provided that the dynamic drift is Lipschitz continuous, the mean squared tracking error rate of the proposed method achieves the optimal rate in the nonparametric statistical paradigm. The proposed framework also allows us to derive the dynamic regret bound and asymptotic normality with a path variation constraint in a natural manner. Numerical analysis has been conducted to verify the performance of the proposed method. In particular, the proposed method is much more robust to the selection of learning rates compared with the ordinary SGD method.

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Level pinning of anti-PT-symmetric circuits for efficient wireless power transfer

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National Science Review 2024年第1期11卷 215-224页

作者： Zhiwei Guo Fengqing Yang haiyan Zhang Xian Wu Qiong Wu Kejia Zhu Jun jiang Haitao jiang Yaping Yang Yunhui Li Hong Chen MOE Key Laboratory of Advanced Micro-Structured Materials School of Physics Sciences and Engineering Tongji University Department of Electrical Engineering Tongji University School of Automotive Studies Tongji University

Wireless power transfer(WPT) technology based on magnetic resonance(a basic physical phenomenon)can directly transfer energy from the source to the load without wires and other physical contacts, and has been successfully applied to implantable medical devices, electric vehicles, robotic arms and other fields.However, due to the frequency splitting of near-field coupling, the resonant WPT system has some unique limitations, such as poor transmission stability and low efficiency. Here, we propose anti-resonance with level pinning for high-performance WPT. By introducing the anti-resonance mode into the basic WPT platform, we uncover the competition between dissipative coupling and coherent coupling to achieve novel level pinning, and construct an effective anti-parity-time(anti-PT)-symmetric non-Hermitian system that is superior to previous PT-symmetric WPT schemes. On the one hand, the eigenvalue of the anti-PT-symmetric system at resonance frequency is always pure real in both strong and weak coupling regions, and can be used to overcome the transmission efficiency decrease caused by weak coupling, as brought about by, for example, a large size ratio of the transmitter to receiver, or a long transmission distance.On the other hand, due to the level pinning effect of the two kinds of coupling mechanisms, the working frequency of the system is guaranteed to be locked, so frequency tracking is not required when the position and size of the receiver change. Even if the system deviates from the matching condition, an efficient WPT can be realized, thereby demonstrating the robustness of the level pinning. The experimental results show that when the size ratio of the transmitter coil to the receiver coil is 4.29(which is in the weak coupling region), the transfer efficiency of the anti-PT-symmetric system is nearly 4.3(3.2) times higher than that of the PT-symmetric system when the matching conditions are satisfied(deviated). With the miniaturization and integration of devices in mind, a synthetic anti-PT-symmetric sy

关键词： non-Hermitian system wireless power transfer anti-PT-symmetric circuits synthetic dimension metamaterials

Heterointerface engineering of rhombic Rh nanosheets confined on MXene for efficient methanol oxidation

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Journal of Energy Chemistry 2024年第6期93卷 419-428,I0011页

作者： Qi Zhang Quanguo jiang Xiang Yang Chi Zhang Jian Zhang Lu Yang haiyan He Guobing Ying Huajie Huang College of Materials Science and Engineering Hohai UniversityNanjing 210098JiangsuChina New Energy Technology Engineering Lab of jiangsu Province College of ScienceNanjing University of Posts&Telecommunications(NUPT)Nanjing 210023JiangsuChina School of Materials Science and Engineering Southeast UniversityNanjing 211100JiangsuChina

Although metallic rhodium(Rh)is regarded as a promising platinum-alternative anode catalyst of direct methanol fuel cell(DMFC),the conventional"particle-to-face"contact model between Rh and matrix largely limits the overall electrocatalytic performance due to their insufficient cooperative effects.Herein,we report a controllable and robust heterointerface engineering strategy for the bottom-up fabrication of rhombic Rh nanosheets in situ confined on Ti_3C_(2)T_x MXene nanolamellas(Rh NS/MXene)via a convenient stereoassembly process.This unique design concept gives the resulting 2D/2D Rh NS/MXene heterostructure intriguing textural features,including large accessible surface areas,strong"face-toface"interfacial interactions,homogeneous Rh nanosheet distribution,ameliorative electronic structure,and high electronic conductivity.As a consequence,the as-prepared Rh NS/MXene nanoarchitectures exhibit exceptional electrocatalytic methanol oxidation properties in terms of a large electrochemically active surface area of 126.2 m~2 g_(Rh)~(-1),a high mass activity of 1056.9 mA mg_(Rh)-~1,and a long service life,which significantly outperform those of conventional particle-shaped Rh catalysts supported by carbon black,carbon nanotubes,reduced graphene oxide,and MXene matrixes as well as the commercial Pt nanoparticle/carbon black and Pd nanoparticle/carbon black catalysts with the same noble metal loading amount.Density functional theory calculations further demonstrate that the direct electronic interaction at the well-contacted 2D/2D heterointerfaces effectively enhances the adsorption energy of Rh nanosheets and induces a left shift of the d-band center,thereby making the Rh NS/MXene configuration suffer less from CO poisoning.This work highlights the importance of rational heterointerface design in the construction of advanced noble metal/MXene electrocatalysts,which may provide new avenues for developing the next-generation DMFC devices.

关键词： Rhodium nanosheet Ti_(3)C_(2)T_(x)MXene Heterointerface Electrocatalyst Fuel cell

A Hybrid Model Based on ResNet and GCN for sEMG-Based Gesture Recognition

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Journal of Beijing Institute of Technology 2023年第2期32卷 219-229页

作者： Xianjing Xu haiyan jiang Key Laboratory of Medical Instrumentation&Pharmaceutical Technology College of Electrical and AutomationFuzhou UniversityFuzhou 350108China

The surface electromyography(sEMG)is one of the basic processing techniques to the gesture recognition because of its inherent advantages of easy collection and non-invasion.However,limited by feature extraction and classifier selection,the adaptability and accuracy of the conventional machine learning still need to promote with the increase of the input dimension and the number of output classifications.Moreover,due to the different characteristics of sEMG data and image data,the conventional convolutional neural network(CNN)have yet to fit sEMG signals.In this paper,a novel hybrid model combining CNN with the graph convolutional network(GCN)was constructed to improve the performance of the gesture recognition.Based on the characteristics of sEMG signal,GCN was introduced into the model through a joint voting network to extract the muscle synergy feature of the sEMG signal.Such strategy optimizes the structure and convolution kernel parameters of the residual network(ResNet)with the classification accuracy on the NinaPro DBl up to 90.07%.The experimental results and comparisons confirm the superiority of the proposed hybrid model for gesture recognition from the sEMG signals.

关键词： deep learning graph convolutional network(GCN) gesture recognition residual net-work(ResNet) surface electromyographic(sEMG)signals

Enhanced carbon capture with motif-rich amino acid loaded defective robust metal-organic frameworks

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Nano Research 2024年第3期17卷 2004-2010页

作者： Qi-Ye Ju Jia-Jia Zheng Li Xu Hai-Yan jiang Zi-Qian Xue Lu Bai Yang-Yang Guo Ming-Shui Yao Ting-Yu Zhu State Key Laboratory of Multi-phase Complex Systems CAS Key Laboratory of Green Process and EngineeringBeijing Key Laboratory of Ionic Liquids Clean ProcessInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China Laboratory of Theoretical and Computational Nanoscience National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing 100190China School of Rare Earths University of Science and Technology of ChinaHefei 230026China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou 341000China University of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China Institute for Integrated Cell-Material Sciences Kyoto UniversityInstitute for Advanced StudyKyoto UniversityYoshidaUshinomiya-choSakyokuKyoto 606-8501Japan

The use of metal-organic frameworks(MOFs)as solid adsorption materials for carbon capture is promising,but achieving efficient and reversible adsorption with a balance of capacity and selectivity for carbon dioxide(CO_(2))over N_(2) remains a challenge.To take full advantage of the strong channel traffic and robustness of MOFs with relatively small pores,it is highly necessary to employ a defect-engineering strategy to construct a broader channel structure that can facilitate the loading of functional motif-rich amino acids(AAs).This strategy can greatly enhance the CO_(2) adsorption performance of MOF.In this study,motif-rich amino acids are loaded into the defective and robust porous frameworks via combined defect-engineering and post-synthetic methods.The defective Zr/Hf-MOF-808s modified with AAs,especially for the 18 mol%4-nitroisophthalic acid,generated defective products allowing for the loading of L-serine(L-Ser).This modification resulted in a significant improvement in both the adsorption capacity(248%improvement at 298 K,100 kPa)and the selectivity of CO_(2)/N_(2) using the ideal adsorbed solution theory(IAST),with the selectivity increasing to 120.55 and 38.27 at 15 and 100 kPa,respectively,while maintaining good cycling performance.Density functional theory(DFT)simulation,CO_(2) temperature-programmed desorption(CO_(2)-TPD),and in situ Fourier transform infrared spectroscopy(FTIR)were further employed to have a better understanding of the enhanced CO_(2) adsorption capacity.Interestingly,unlike the AAs loaded pristine MOF-808s that showed the best CO_(2) adsorption capacity with the loading of short and small glycine(Gly),the broadened channel size in our work enables the loading of functional motif-rich L-serine,which brings more active binding sites,improving CO_(2) adsorption.

关键词： carbon capture and storage metal-organic framework(MOF) amino acids(AAs) defect-engineering motif-rich

The effect of protic ionic liquids incorporation on CO_(2) separation performance of Pebax-based membranes

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Chinese Journal of Chemical Engineering 2022年第3期35卷 169-176页

作者： haiyan jiang Lu Bai Bingbing Yang Shaojuan Zeng Haifeng Dong Xiangping Zhang CAS Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex SystemsBeijing Key Laboratory of Ionic Liquids Clean ProcessInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Future Technology University of Chinese Academy of SciencesBeijing 100049China Advanced Energy Science and Technology Guangdong Laboratory Huizhou 516003China

The separation of carbon dioxide(CO_(2))is of great importance for environment protection and gas resource purification.The ionic liquids(ILs)-based gas separation membrane provides a new chance for efficient CO_(2)separation,while high permeability and selectivity of membranes is a great challenge.In this study,the influence of two protic ILs with different anion([TMGH][Im]and[TMGH][PhO])on the CO_(2)separation performance of the prepared ILs/Pebax blended membranes were systematically investigated at different temperature.The results showed the CO_(2)permeability exhibits the rising trend for ILs/Pebax blended membranes with the increment of IL content.Especially,the[TMGH][Im]with low viscosity and high CO_(2)absorption capacity leads to the blended membranes showing better CO_(2)permeability and ideal CO_(2)selectivity than that of membranes with[TMGH][PhO]at high IL content.Besides,with operating temperature increasing,the gas permeability of 20%(mass)[TMGH][Im]/Pebax blended membrane increases due to the decreasing viscosity of IL and the rising chain mobility of polymer.Inversely,the gas selectivity shows decreasing trend because CO_(2)absorption capacity obviously decreased at higher temperature.

关键词： CO_(2) Protic ionic liquids Membranes Pebax

Effective inhibition of anomalous grain coarsening in cast AZ91 alloys during fast cooling via nanoparticle addition

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Journal of Magnesium and Alloys 2023年第12期11卷 4575-4588页

作者： Haonan Li Kui Wang Gaopeng Xu haiyan jiang Qudong Wang Yingxin Wang National Engineering Research Center of Light Alloy Net FormingShanghai Jiao Tong University200240ShanghaiP.R.China State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University200240ShanghaiP.R.China

In this work, the effects of Ti CN and γ-Al_(2)O_(3) nanoparticle(NP) addition on the microstructural evolution of cast AZ91 alloys at the cooling rate ranging from 15 to 120 K/s have been systematically investigated. Experimental results reveal that grain coarsening occurs in cast AZ91 alloys when the cooling rate exceeds 90 K/s, while it can be effectively inhibited upon addition of NPs. The marked inhibition effect may originate from the formation of Ti CN or γ-Al_(2)O_(3) NP-induced undercooling zone ahead of solid/liquid(S/L) front of α-Mg, which not only can restrict grain growth effectively, but also can reactivate the native nucleants that are inactive in AZ91 melts to participate in nucleation events. And if possessing high nucleation potency, NPs can also promote further nucleation events and lead to significant grain refinement. An analytical model has been established to quantitatively account for the restriction effect of NPs on grain growth. The present work may shed a new light on the grain coarsening of cast alloys during fast cooling and provide an effective approach to circumvent it.

关键词： Grain coarsening Nanoparticles Undercooling zone Fast cooling

Controllable chemical redox reactions to couple microbial degradation for organic contaminated sites remediation:A review

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Journal of Environmental Sciences 2024年第5期139卷 428-445页

作者： Bin Chen jiang Xu Lizhong Zhu College of Environmental and Resource Sciences Zhejiang UniversityHangzhou 310058China Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control Zhejiang UniversityHangzhou 310058China Zhejiang Agriculture&Forest University Lin'an 311300China

Global environmental concern over organic contaminated sites has been progressively conspicuous during the process of urbanization and industrial restructuring.While traditional physical or chemical remediation technologies may significantly destroy the soil structure and function,coupling moderate chemical degradation with microbial remediation becomes a potential way for the green,economic,and efficient remediation of contaminated sites.Hence,this work systematically elucidates why and how to couple chemical technology with microbial remediation,mainly focused on the controllable redox reactions of organic contaminants.The rational design of materials structure,selective generation of reactive oxygen species,and estimation of degradation pathway are described for chemical oxidation.Meanwhile,current progress on efficient and selective reductions of organic contaminants(i.e.,dechlorination,defluorination,-NO_(2) reduction)is introduced.Combined with the microbial remediation of contaminated sites,several consideration factors of how to couple chemical and microbial remediation are proposed based on both fundamental and practical points of view.This review will advance the understanding and development of chemical-microbial coupled remediation for organic contaminated sites.

关键词： Soil remediation Groundwater remediation Rational design Reactive species Environmental nanotechnology

Response of ocean acidification to atmospheric carbon dioxide removal

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Journal of Environmental Sciences 2024年第6期140卷 79-90页

作者： Jiu jiang Long Cao Xiaoyu Jin Zechen Yu Han Zhang Jianjie Fu Guibin jiang School of Environment Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Key Laboratory of Geoscience Big Data and Deep Resources of Zhejiang Province School of Earth SciencesZhejiang UniversityHangzhou 310058China Zhejiang Climate Center Hangzhou 310052China

Artificial CO_(2)removal from the atmosphere(also referred to as negative CO_(2)emissions)has been proposed as a potential means to counteract anthropogenic climate change.Here we use an Earth system model to examine the response of ocean acidification to idealized atmospheric CO_(2)removal scenarios.In our simulations,atmospheric CO_(2)is assumed to increase at a rate of 1%per year to four times its pre-industrial value and then decreases to the pre-industrial level at a rate of 0.5%,1%,2%per year,respectively.Our results show that the annual mean state of surface ocean carbonate chemistry fields including hydrogen ion concentration([H^(+)]),pH and aragonite saturation state respond quickly to removal of atmospheric CO_(2).However,the change of seasonal cycle in carbonate chemistry lags behind the decline in atmospheric CO_(2).When CO_(2)returns to the pre-industrial level,over some parts of the ocean,relative to the pre-industrial state,the seasonal amplitude of carbonate chemistry fields is substantially larger.Simulation results also show that changes in deep ocean carbonate chemistry substantially lag behind atmospheric CO_(2)change.When CO_(2)returns to its pre-industrial value,the whole-ocean acidity measured by[H^(+)]is 15%-18%larger than the pre-industrial level,depending on the rate of CO_(2)decrease.Our study demonstrates that even if atmospheric CO_(2)can be lowered in the future as a result of net negative CO_(2)emissions,the recovery of some aspects of ocean acidification would take decades to centuries,which would have important implications for the resilience of marine ecosystems.

关键词： Carbon dioxide removal Net negative CO_(2)emission Ocean acidification Climate change Earth system modeling