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STDNet: A Spatio-Temporal Decomposition Neural Network for Multivariate Time Series Forecasting

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Tsinghua Science and Technology 2024年第4期29卷 1232-1247页

作者： Zhuolun Jiang Zefei Ning hao miao Li Wang College of Computer Science and Technology(College of Data Science) Taiyuan University of TechnologyJinzhong 030600China

Long-term multivariate time series forecasting is an important task in engineering applications. It helps grasp the future development trend of data in real-time, which is of great significance for a wide variety of fields. Due to the non-linear and unstable characteristics of multivariate time series, the existing methods encounter difficulties in analyzing complex high-dimensional data and capturing latent relationships between multivariates in time series, thus affecting the performance of long-term prediction. In this paper, we propose a novel time series forecasting model based on multilayer perceptron that combines spatio-temporal decomposition and doubly residual stacking, namely Spatio-Temporal Decomposition Neural Network (STDNet). We decompose the originally complex and unstable time series into two parts, temporal term and spatial term. We design temporal module based on auto-correlation mechanism to discover temporal dependencies at the sub-series level, and spatial module based on convolutional neural network and self-attention mechanism to integrate multivariate information from two dimensions, global and local, respectively. Then we integrate the results obtained from the different modules to get the final forecast. Extensive experiments on four real-world datasets show that STDNet significantly outperforms other state-of-the-art methods, which provides an effective solution for long-term time series forecasting.

关键词： time series forecasting multivariate time series spatio-temporal decomposition

Preparation of AlN thin films for film bulk acoustic resonator application by radio frequency sputtering

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第3期10卷 464-470页

作者： Kan LI hao JIN De-miao WANG Yi-fei TANG Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

Aluminum nitride （AlN） thin films with high c-axis orientation have been prepared on a glass substrate with an Al bottom electrode by radio frequency （RF） reactive magnetron sputtering. Based on the analysis of Berg＇s hysteresis model, the improved sputtering system is realized without a hysteresis effect. A new control method for rapidly depositing highly c-axis oriented AlN thin films is proposed. The N2 concentration could be controlled by observing the changes in cathode voltage, to realize the optimum processing condition where the target could be fixed stably in the transition region, and both stoichiometric film composition and a high deposition rate could be obtained. Under a 500 W RF power of a target with a 6 cm diameter, a substrate temperature of 450 ℃, a target-substrate distance of 60 mm and a N2 concentration of 25%, AlN thin film with preferential （002） orientation was deposited at 2.3 μm/h which is a much higher rate than previously achieved. Through X-ray diffraction （XRD） analysis, the full width at half maximum （FWHM） of AlN （002） was shown to be about 0.28°, which shows the good crystallinity and crystal orientation of AlN thin film. With other parameters held constant, any increase or decrease in N2 concentration results in an increase in the FWHM of AlN.

关键词： Aluminum nitride (A1N) Piezoelectric thin film Radio frequency (RF) reactive sputtering Preferred orientation,Film bulk acoustic resonator (FBAR)

Numerical investigation of separation efficiency of the cyclone with supercritical fluid-solid flow

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Particuology 2022年第3期20卷 36-46页

作者： Zeyu Li Zhenbo Tong Aibing Yu hao miao Kaiwei Chu hao Zhang Gang Guo Jiang Chen School of Energy and Environment Southeast UniversityNanjing 210096China Southeast University-Monash University Joint Research Institute Suzhou215123China Department of Chemical Engineering Monash UniversityClaytonVic 3800Australia School of Qilu Transportation Shandong UniversityJinan250002China School of Metallurgy Northeastern UniversityShenyang110819China

The utilization of hydrogen is gaining increasing attention due to its high heating value and environmentally friendly combustion *** supercritical water circulating fluidized bed reactor is a promising and potentially clean technology that can generate hydrogen from coal *** is a vital part of the reactor which can separate incomplete decomposition of pulverized coal particles from mixed working *** paper aims to gain in-depth understanding of the cyclone separation mechanisms under supercritical fluid by computational fluid dynamics(CFD).Although the amount of supercritical carbon dioxide in mixed working fluid is minor,it obviously influences the flow fields and separation efficiency of a *** simulation results suggest that both the decreasing content of supercritical carbon dioxide and adding the extra dipleg cause the promoting performance of *** findings could refine the design of supercritical fluid-solid cyclones.

关键词： Cyclone Supercritical fluid-solid flow Computational fluid dynamics

Big-data analysis of phase-formation rules in high-entropy alloys

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Journal of Iron and Steel Research International 2017年第4期24卷 358-365页

作者： Wan-li Zhao Ding-hao miao Yong Zhang Zhan-bing He State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

Big-data analysis of phase-formation rules of high-entropy alloys（HEAs）was conducted and a phase formation rule from a dynamic view was *** was indicated in literatures that cooling rate has a strong influence on the phase formation of *** cooling rate may promote the generation of amorphous phase,and accordingly suppress the formation of ***,it was also shown that cooling rate had little impact on the formation of solid-solution *** demonstrate this rule,a series of FeCoNi（AlSiB）xHEAs ribbons were fabricated by a melt-spinning technique,and the microstructure,mechanical,and magnetic properties were also *** results show that all ribbons exhibit disordered solid-solution *** addition of boron changes the alloy from ductility to brittleness,but without evident change of magnetic *** alloy in the nominal composition of FeCoNi（AlSi）0.2has the best combination of mechanical and magnetic properties.A distinct feature of HEAs in magnetization was noticed and explained.

关键词： High-entropy alloys Ribbon Magnetic property Melt spinning Phase formation rule

Facile Synthesis of 3D Porous Flower-like ZnO Micro/nanostructure Films and Their Photocatalytic Performance

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Chinese Journal of Chemical Physics 2012年第3期25卷 339-344,374页

作者： Jin-ling Yang Guang Tao Fei Hui Li hao-miao Ouyang Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology Institute of Solid State Physics Hefei Institutes of Physical Science Chinese Academy of SciencesHefei 230031 China

3D porous flower-like ZnO micro/nanostructure films grown on Ti substrates are synthesized via a very facile electrodeposition technique followed by heat treatment process. The ZnO architecture is assembled with ultra thin sheets, which consist of numbers of nanoparticles and pores, and the size of the nanoparticles can be controlled by adjusting the electrodepo- sition time or calcination temperature. It is worth noting that this synthetic method can provide an effective route for other porous metal oxide nanostructure films. Moreover, the photocatalytic performance shows the porous ZnO is an ideal photocatalyst.

关键词： Zinc oxide porous film Photocatalyst Micro/nanostructure Electrodeposition

Characterization of cloud microphysical properties in different cloud types over East Asia based on CloudSat/CALIPSO satellite products

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Atmospheric and Oceanic Science Letters 2021年第5期14卷 1-7页

作者： hao miao Xiaocong Wang Yimin Liu Guoxiong Wu College of Atmospheric Science Nanjing University of Information Science and TechnologyNanjingChina State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric Physics(IAP)Chinese Academy of Sciences(CAS)BeijingChina College of Earth and Planetary Science University of Chinese Academy of SciencesBeijingChina

By using four-year CloudSat/CALIPSO satellite data,the authors investigated cloud microphysical properties in three representative regions over East Asia,where models commonly suffer from great biases in simulations of cloud radiative *** study aims to provide an observational basis of cloud microphysical properties for the modeling community,against which the model simulations can be *** analyzed cloud microphysical properties include mass,number concentration,and effective radius for both liquid and ice *** liquid clouds,both cloud mass and number concentration gradually decrease with height,leading to the effective radius being nearly uniformly spread in the range of 8-14μ*** ice clouds,the cloud mass and effective radius decrease with height,whereas the number concentration is nearly uniform in the *** cloud microphysical properties show remarkable differences among different cloud *** mass and number concentration are larger in cumuliform clouds,whereas smaller in cirrus *** comparing cloud properties among the Tibetan Plateau,East China,and the western North Pacific,results show the values are overall smaller for liquid clouds but larger for ice clouds over the Tibetan Plateau.

关键词： Cloud mass Number concentration Effective radius Cloud types CloudSat/CALIPSO Tibetan Plateau

AN EME BLIND SOURCE SEPARATION ALGORITHM BASED ON GENERALIZED EXPONENTIAL FUNCTION

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Journal of Electronics(China) 2008年第2期25卷 262-267页

作者： miao hao Li Xiaodong Tian Jing Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China

This letter investigates an improved blind source separation algorithm based on Maximum Entropy （ME） criteria. The original ME algorithm chooses the fixed exponential or sigmoid ftmction as the nonlinear mapping function which can not match the original signal very well. A parameter estimation method is employed in this letter to approach the probability of density function of any signal with parameter-steered generalized exponential function. An improved learning rule and a natural gradient update formula of unmixing matrix are also presented. The algorithm of this letter can separate the mixture of super-Gaussian signals and also the mixture of sub-Gaussian signals. The simulation experiment demonstrates the efficiency of the algorithm.

关键词： Blind source separation Maximum Entropy (ME) Generalized exponential function

Microstructure, mechanical properties, and corrosion resistance of Mg–9Li–3Al–1.6Y alloy

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Rare Metals 2016年第5期35卷 374-379页

作者： hao-miao Yang Nan-Yi Zhang Na Liu Wei-Dong Xie Xiao-Dong Peng College of materials Science and Engineering Chongqing University School of Physics & Electron Engineering Yangtze Normal University

Mg–9Li–3Al–1.6Y alloys were prepared through mixture method. The microstructure, mechanical properties, and corrosion resistance of the as-cast and asextruded alloys were studied by optical microscopy（OM）,scanning electronic microscopy（SEM）, X-ray diffraction（XRD）, mechanical properties testing, and electrochemical measurement. The as-cast Mg–9Li–3Al–1.6Y alloy with the average grain size of 325 lm is composed of b-Li matrix, block a-Mg, and granule Al2Y phases. After extrusion, the grain size of the as-cast alloy is obviously refined and reaches to 75 lm; the strength and elongation of the extruded alloy are enhanced by 17.20 % and49.45 %, respectively, owing to their fine microstructure and reduction of casting defects. The as-extruded alloy shows better corrosion resistance compared to the as-cast one, which may be related to the low stored energy and dislocation density in the extruded alloy, also the homogenization treatment before extrusion.

关键词： Magnesium alloy Microstructures Mechanical properties Corrosion resistance

Nitrogen-rich three-dimensional porous carbon mosaicked Na_(4)Ge_(9)O_(20)as anode material for high-performance lithium-ion batteries

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Rare Metals 2023年第2期42卷 438-448页

作者： hao-miao Zhang Jing Chen Rou Lu Cong-Ge Lu Shuang Zhou Zhi Chang An-Qiang Pan School of Materials Science and Engineering Central South UniversityChangsha410083China School of Physics and Materials Nanchang UniversityNanchang330031China

Germanium-based material has attracted numerous attentions and been regarded as a promising anode material for lithium-ion batteries due to its high theoretical ***,drastic pulverization and rapid capacity fading caused by large volume variation during cycling limit its practical *** this work,three-dimensional N-doped carbon framework-wrapped Na_(4)Ge_(9)O_(20)nanoparticles(3D Na_(4)Ge_(9)O_(20)@N-C)have been synthesized via freeze-drying approach with NaCl as both template and sodium source for *** employment of NaCl has two special roles:on the one hand,the NaCl crystals act as template and facilitate the formation of 3D porous structure,while on the other hand,the NaCl crystals serving as sodium source and support the ion exchange between NaCl and GeO_(2)promote the formation of Na_(4)Ge_(9)O_(20).Benefiting from the unique method,the prepared 3D Na_(4)Ge_(9)O_(20)@N-C not only suppresses the volume change by using carbon as buffer layers but also demonstrates an improved electronic conductivity and a shortened ionic *** utilized as an anode material for LIBs,the 3D Na_(4)Ge_(9)O_(20)@N-C composites deliver high reversible capacity(896.2 mAh·g^(-1)at0.1 A·g^(-1)after 100 cycles),good cycling stability(520.8 mAh·g^(-1)at 2.0 A·g^(-1)after 400 cycles)and excellent rate performance(636.0 mAh·g^(-1)at 2.0 A·g^(-1)).This work provides a strategy to improve the electrochemical performance of germanium-based anode materials for lithium-ion batteries.

关键词： Germanium-based anode Na_(4)Ge_(9)O_(20) Ndoped carbon Porous nanostructure Lithium-ion batteries(LIBs)