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Preface to the special issue on diverse applications of tungsten and related metals

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Tungsten 2021年第3期3卷 243-244页

作者： Cheng Zhong Key Laboratory of Advanced Ceramics and Machining Technology(Ministry of Education) School of Materials Science and EngineeringTianjin UniversityTianjin 300072China Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin 300072China

Tungsten(W)is an exceptionally strong refractory metal,which is an important chemical element used in lamp filaments and in steel to increase hardness and strength.Recently,tungsten and related metals,including molybdenum,cobalt,vanadium,tantalum,niobium,rhenium,zirconium,hafnium as well as their alloys and compounds,are also found to be effective in preparing novel energy storage materials.The present issue consists of nine contributions with six review papers and three original research articles.

关键词： steel metals preparing

ST-Trader:A Spatial-Temporal Deep Neural Network for Modeling Stock Market Movement

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IEEE/CAA Journal of Automatica Sinica 2021年第5期8卷 1015-1024页

作者： Xiurui Hou Kai Wang Cheng Zhong Zhi Wei the Department of Computer Science New Jersey Institute of TechnologyNewarkNJ 07102 USA the School of Business Stevens Institute of TechnologyHobokenNJ 07030 USA

Stocks that are fundamentally connected with each other tend to move together.Considering such common trends is believed to benefit stock movement forecasting tasks.However,such signals are not trivial to model because the connections among stocks are not physically presented and need to be estimated from volatile data.Motivated by this observation,we propose a framework that incorporates the inter-connection of firms to forecast stock prices.To effectively utilize a large set of fundamental features,we further design a novel pipeline.First,we use variational autoencoder(VAE)to reduce the dimension of stock fundamental information and then cluster stocks into a graph structure(fundamentally clustering).Second,a hybrid model of graph convolutional network and long-short term memory network(GCN-LSTM)with an adjacency graph matrix(learnt from VAE)is proposed for graph-structured stock market forecasting.Experiments on minute-level U.S.stock market data demonstrate that our model effectively captures both spatial and temporal signals and achieves superior improvement over baseline methods.The proposed model is promising for other applications in which there is a possible but hidden spatial dependency to improve time-series prediction.

关键词： Graph convolution network long-short term memory network stock market forecasting variational autoencoder(VAE)

Exploiting Flexibility of Integrated Demand Response to Alleviate Power Flow Violation During Line Tripping Contingency

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Journal of Modern Power Systems and Clean Energy 2023年第6期11卷 1971-1981页

作者： Tong cheng Zhenfei Tan Haiwang zhong IEEE State Key Laboratory of Power Systems the Department of Electrical EngineeringTsinghua UniversityBeijingChina

Multi-energy integrations provide great opportunities for economic and efficient resource utilization. In the meantime, power system operation requires enough flexible resources to deal with contingencies such as transmission line tripping. Besides economic benefits, this paper focuses on the security benefits that can be provided by multi-energy integrations. This paper first proposes an operation scheme to coordinate multiple energy production and local system consumption considering transmission networks. The integrated flexibility model, constructed by the feasible region of integrated demand response(IDR), is then formulated to aggregate and describe local flexibility. Combined with system security constraints, a multi-energy system operation model is formulated to schedule multiple energy production, transmission, and consumption. The effects of local system flexibility on alleviating power flow violations during N-1 line tripping contingencies are then analyzed through a multi-energy system case. The results show that local system flexibility can not only reduce the system operation costs, but also reduce the probability of power flow congestion or violations by approximately 68.8% during N-1 line tripping contingencies.

关键词： Multi-energy system integrated flexibility feasible region integrated demand response N-1 security

Online prediction of network-level public transport demand based on principle component analysis

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Communications in Transportation Research

Communications in Transportation Research 2023年第1期3卷 62-71页

作者： Cheng Zhong Peiling Wu Qi Zhang Zhenliang Ma Department of Civil and Architectural Engineering KTH Royal Institute of TechnologyStockholm10044Sweden

Online demand prediction plays an important role in transport network services from operations,controls to management,and information provision.However,the online prediction models are impacted by streaming data quality issues with noise measurements and missing data.To address these,we develop a robust prediction method for online network-level demand prediction in public transport.It consists of a PCA method to extract eigen demand images and an optimization-based pattern recognition model to predict the weights of eigen demand images by making use of the partially observed real-time data up to the prediction time in a day.The prediction model is robust to data quality issues given that the eigen demand images are stable and the predicted weights of them are optimized using the network level data(less impacted by local data quality issues).In the case study,we validate the accuracy and transferability of the model by comparing it with benchmark models and evaluate the robustness in tolerating data quality issues of the proposed model.The experimental results demonstrate that the proposed Pattern Recognition Prediction based on PCA(PRP-PCA)consistently outperforms other benchmark models in accuracy and transferability.Moreover,the model shows high robustness in accommodating data quality issues.For example,the PRP-PCA model is robust to missing data up to 50%regardless of the noise level.We also discuss the hidden patterns behind the network level demand.The visualization analysis shows that eigen demand images are significantly connected to the network structure and station activity variabilities.Though the demand changes dramatically before and after the pandemic,the eigen demand images are consistent over time in Stockholm.

关键词： Network-level demand prediction Data quality issues Eigen demand image Pattern recognition Principle component analysis

Simple sulfone-bridged heterohelicene structure realizes ultraviolet narrowband thermally activated delayed fluorescence,circularly polarized luminescence,and room temperature phosphorescence

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Science China Chemistry 2022年第9期65卷 1715-1719页

作者： Weimin Ning Han Wang Shaolong Gong Cheng Zhong Chuluo Yang Department of Chemistry Hubei Key Lab on Organic and Polymeric Optoelectronic MaterialsWuhan UniversityWuhan 430072China Shenzhen Key Laboratory of New Information Display and Storage Materials College of Materials Science and EngineeringShenzhen UniversityShenzhen 518060China

Due to narrowband emission and high quantum efficiencies,polycyclic aromatic heterocycles with multi-resonance thermally activated delayed fluorescence(MR-TADF)properties have recently gained considerable attention in the organic optoelectronic field.Albeit their great promise in the full visible region covering from blue to red,MR-TADF emitters with ultraviolet emission have been rarely reported.Through locking the two ortho-positions of a triphenylamine core by sulfone groups,a simple polycyclic aromatic heterocycle,BTPT,was facilely constructed,exhibiting 368 nm ultraviolet emission with a narrow full width at half maximum(FWHM)of 33 nm.Its neat film exhibited distinct TADF property with a main emission peak at 388 nm.Noteworthily,the enantiomeric crystals of BTPT not only demonstrated significant circularly polarized luminescence(CPL)with large luminescence dissymmetry factor in the 10^(-3) order but also displayed obvious room temperature phosphorescence(RTP).The relationship between this innovative helical unit and unique photophysical properties,including ultraviolet MR-TADF,CPL,and RTP,was reasonably revealed.

关键词： polycyclic aromatic heterocycles thermally activated delayed fluorescence multi-resonance effect ultraviolet emission circularly polarized luminescence room temperature phosphorescence

The Origin of The Soft X-Ray Excess in the Seyfert 1.5 Galaxy ESO 362-G18

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Research in Astronomy and Astrophysics 2022年第3期22卷 10-32页

作者： Xiao-Gu zhong Jian-cheng Wang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China University of Chinese Academy of Sciences Beijing 100049China

We review the Seyfert 1.5 Galaxy ESO 362-G18 for exploring the origin of the soft X-ray excess.The Warm Corona and Relativistic Reflection models are two main scenarios to interpret the soft X-ray excess in active galactic nuclei at present.We use the simultaneous X-ray observation data of XMM-Newton and Nu STAR on2016 September 24 to perform spectral analysis in two steps.First,we analyze the time-average spectra by using Warm Corona and Relativistic Reflection models.Moreover,we also explore the Hybrid model,Double Reflection model and Double Warm Corona model.We find that both the Warm Corona and Relativistic Reflection models can interpret the time-average spectra well but cannot be distinguished easily based on the time-averaged spectra fit statistics.Second,we add the rms and covariance spectra to perform the spectral analysis with time-average spectra.The result shows that the warm corona could reproduce all of these spectra well.The hot,optical thin corona and neutral distant reflection will increase their contribution with the temporal frequency,meaning that the corona responsible for X-ray continuum comes from the inner compact X-ray region and the neutral distant reflection is made of some moderate scale neutral clumps.

关键词： galaxies:active galaxies:individual(ESO 362-G18) galaxies:Seyfert

Room temperature phosphorescence achieved by aromatic/perfluoroaromatic interactions

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Science China Chemistry 2022年第5期65卷 918-925页

作者： Qunhua Zhang Yuanyuan Fan Qiuyan Liao Cheng Zhong Qianqian Li Zhen Li Hubei Key Lab on Organic and Polymeric Opto-Electronic Materials Sauvage Center for Molecular SciencesDepartment of ChemistryWuhan UniversityWuhan 430072China Institute of Molecular Aggregation Science Tianjin UniversityTianjin 300072China

Room temperature phosphorescence(RTP) has attracted much attention for the applications in information encryption,bioimaging,displaying,and so on.In this work,persistent RTP emission is mainly achieved by the compact face-to-face packing modes with aromatic/perfluoroaromatic interactions.Moreover,it can be further optimized by halogen substitutions with heavy atom effect,electron-withdrawing property,and steric hindrance,resulting in the prolonged RTP lifetime.Furthermore,the multiple fluorine substitutions endowed these luminogens with the water-resistant property,resulting in the maintained RTP emission with water droplets.Therefore,the aromatic/perfluoroaromatic interactions are not only the efficient approach to achieve persistent RTP,but also extend their application to a humid environment or even in water.

关键词： room temperature phosphorescence aromatic/perfluoroaromatic interaction face-to-face packing

Revealing the Precise Role of Calretinin Neurons in Epilepsy: We Are on the Way

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Neuroscience Bulletin 2022年第2期38卷 209-222页

作者： Yingbei Qi Heming cheng Yi Wang zhong Chen Institute of Pharmacology and Toxicology College of Pharmaceutical SciencesZhejiang UniversityHangzhouChina Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province School of Pharmaceutical SciencesZhejiang Chinese Medical UniversityHangzhouChina

Epilepsy is a common neurological disorder characterized by hyperexcitability in the brain.Its pathogenesis is classically associated with an imbalance of excitatory and inhibitory neurons.Calretinin(CR)is one of the three major types of calcium-binding proteins present in inhibitory GABAergic neurons.The functions of CR and its role in neural excitability are still unknown.Recent data suggest that CR neurons have diverse neurotransmitters,morphologies,distributions,and functions in different brain regions across various species.Notably,CR neurons in the hippocampus,amygdala,neocortex,and thalamus are extremely susceptible to excitotoxicity in the epileptic brain,but the causal relationship is unknown.In this review,we focus on the heterogeneous functions of CR neurons in different brain regions and their relationship with neural excitability and epilepsy.Importantly,we provide perspectives on future investigations of the role of CR neurons in epilepsy.

关键词： Calretinin Epilepsy Calcium-binding protein Neuronal excitability

A Vanishing Theorem on a Class of Hartogs Domain

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Acta Mathematica Sinica,English Series 2023年第1期39卷 1-12页

作者： cheng Chen zhong An WANG Li Shuang PAN School of Mathematical Sciences Peking UniversityBeijing 100871P.R.China School of Mathematical Sciences Capital Normal UniversityBeijing 100048P.R.China Science College Shijiazhuang UniversityHebei 050035P.R.China

In this paper,we consider the d-boundedness of the Bergman metric and a vanishing theorem of L2-cohomology on a class of Hartogs domain,whose base domain is the production of two irreducible bounded symmetric domains ... 详细信息

关键词： d-bounded vanishing theorem Bergman metric