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Science China(Information Sciences) 2011年第6期54卷 1283-1292页

作者： CUI Dong 1 , LI XiaoLi 2 , JI XueQing 3 & LIU LanXiang 3 1 Institute of Information Science and Engineering, Yanshan university, qinhuangdao 066004, China 2 Institute of Electrical Engineering, Yanshan university, qinhuangdao 066004, China 3 The No.1 Hospital of qinhuangdao, qinhuangdao 066000, China 1. Institute of Information Science and Engineering Yanshan University Qinhuangdao 066004 China2. Institute of Electrical Engineering Yanshan University Qinhuangdao 066004 China3. The No.1 Hospital of Qinhuangdao Qinhuangdao 066000 China

Multi-channel neural signals generated by a computational model can help understand the mechanism of EEG rhythms, analyze brain functional connectivity and evaluate neural signal processing methods. In this study, a two-kinetics lumped-parameter neural mass model is extended to a multi-kinetics and multi-channel coupled model. This new model can effectively simulate the coupled dynamics activities between different areas in the brain. The simulation results show that the proposed model can generate neural signals with various frequency bands, from delta wave (1-4 Hz) to gamma wave (30-70 Hz), and the dynamics of the simulated neural signals is more complicated. The simulation analysis can also reveal the relationship between the coupled neural networks and the rhythm of neural populations, and the simulated neural signals can present the bi-modal and uni-modal phenomenon in the frequency domain when the coupling strength of models increases. Finally, analysis of an epileptic EEG signal from a rat demonstrates that the coupling among the neural populations can induce a large-scale seizure.

关键词： multi-channel neural mass model coupling spectrum synchronization epilepsy

Effect of Pre-treatment on the Bi-2223/Ag Tapes Fabricated with Different Powders

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稀有金属材料与工程 2011年第S3期40卷 325-328页

作者： Li Mingya1, Chen Xingpin2, Ye Chengli1, Yu Liang1, Zhu Xu1 1 northeastern university at qinhuangdao, qinhuangdao 066004, China 2 Chongqing university, Chongqing 400044, China NE Univ qinhuangdao Dept Mat Sci & Engn Qinhuangdao 066004 Peoples R China Chongqing Univ Chongqing 400044 Peoples R China

Samples of Bi-2223/Ag tapes fabricated with powders contained different lead oxide compounds were annealed at a temperature lower than the formation temperature of Bi-2223 phase before traditional heat treatment, which was called pretreatment. In pre-treatment stage, samples were heat treated at 780 ℃ in 8.5% O2, and the dwelling time is different. Experimental results show that pre-treatment had different influence on the formation and size of the Bi-2223 grains for tapes fabricated with powders contained different lead oxide compounds. For tapes contained both Ca2PbO4 and the 3321 phase, the decomposition of the 3321 phase enhanced the growth of Bi-2212 grains during pre-treatment process, which promoted the formation of Bi-2223 phase and enhanced the superconducting properties of Bi-2223/Ag tapes.

关键词： pre-treatment Bi-2223/Ag tapes lead oxide compounds critical current

Synthesis of Self-assembled Mesoporous Zirconia with Rheological Phase Reaction

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稀有金属材料与工程 2011年第S3期40卷 263-265页

作者： Wang Xiaoqiang1, Xia Wang1, Lu Baoqiang1, Zhen Congmian2 1northeastern university at qinhuangdao Branch, qinhuangdao 066004, China 2Hebei Normal university, Shijiazhuang 050016, China northeastern Univ Dept Mat Sci & Engn Qinhuangdao Branch Qinhuangdao 066004 Peoples R China Hebei Normal Univ Shijiazhuang 050016 Peoples R China

The rheological phase reaction method was used to obtain the zirconia spherical particles with monodispersity and single-scale. And based on this, we got the colloidal dispersion of Zirconia (ZrO2). Mesoporous zirconia were successfully synthesized by vacuum filtration or gravitational deposition as assembly methods using monodispersed PMMA as template. The precursor was studied by FT-IR, TG and DTA, these results further revealed that the precursor is ZrO(C6H5COO)2·2H2O. By the phase analysis in the XRD patterns it was proved that the ZrO2 crystallites have monoclinic phase structure. SEM results indicated that the aperture size is from 50-500 nm and increases with the process conditions changing, moreover, the sample has good thermal stability. This study shows the controllability of ZrO2 macroporous materials’ aperture size was realized at some extent.

关键词： ZrO2 mesoporous rheological phase reaction self-assemble

Thermodynamic properties of under-cooled silver melts

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Science China(Physics,Mechanics & Astronomy) 2010年第1期53卷 76-80页

作者： ZHU YuYing 1 , LI Qiang 1,2,3, WANG Ge 1 , JING Qin 2 , WANG Xu 1 , GAO Ying 3 & GAO JingNa 3 1 Department of Mechanical Engineering, Yanshan university, qinhuangdao 066004, China 2 Key Laboratory of Metastable Materials Science & Technology, Yanshan university, qinhuangdao 066004, China 3 Department of Materials Science & Engineering, Hebei university of Science and Technology, Shijiazhuang 050018, China 1. Department of Mechanical Engineering Yanshan University Qinhuangdao 066004 China2. Key Laboratory of Metastable Materials Science & Technology Yanshan University Qinhuangdao 066004 China3. Department of Materials Science & Engineering Hebei University of Science and Technology Shijiazhuang 050018 China

Differential scanning calorimeter technique combined with the traditional fluxing treatment was used to investigate the specific heat and related thermodynamic properties of under-cooled pure silver melts. The specific heat of the under-cooled melt showed a linear dependence on the temperature in the range of the obtained under-cooling from 0 to 198 K. The related thermodynamic properties of silver, such as the entropy change, the enthalpy change and the Gibbs free energy difference between the under-cooled melt and the solid phase, were derived from the measured specific heat. The relations between the temperature and the thermal diffusion or the thermal conductivity of the under-cooled melt were analyzed respectively.

关键词： under-cooled silver melts specific heat thermodynamic properties

Unitary cyclic ESPRIT-like direction finding

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Science China(Information Sciences) 2010年第10期53卷 2087-2096页

作者： LIU ZhiGang & WANG JinKuan Department of Electronic Information, northeastern university, qinhuangdao 066004, China 1. Department of Electronic Information Northeastern University Qinhuangdao 066004 China

A unitary formulation of cyclic ESPRIT algorithm, with uniform linear array (ULA) configuration, is proposed by constructing the forward backward cyclic autocorrelation matrix by Hermitian mapping. This approach not only substantially reduces the computational complexity via real-valued decomposition, but also outperforms the forward backward spatial smoothing algorithm for uncorrelated or correlated sources. In addition, this method allows to select desired signals and to ignore interferences because of its signal-selective property. The performance analysis shows that for uncorrelated or correlated sources, the Hermitian mapping approach has a lower RMSE and a higher output SNR than the FBSS method. Finally, simulation results show the effectiveness of the proposed methods.

关键词： array signal processing cyclostationary signals direction of arrival cyclic ESPRIT unitary ESPRIT

NeurstrucEnergy:A bi-directional GNN model for energy prediction of neural networks in IoT

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Digital Communications and Networks 2024年第2期10卷 439-449页

作者： Chaopeng guo Zhaojin Zhong Zexin Zhang Jie Song Software Campus Northeastern UniversityShenyang110000LiaoningChina

A significant demand rises for energy-efficient deep neural networks to support power-limited embedding devices with successful deep learning applications in IoT and edge computing *** accurate energy prediction approach is critical to provide measurement and lead optimization ***,the current energy prediction approaches lack accuracy and generalization ability due to the lack of research on the neural network structure and the excessive reliance on customized training *** paper presents a novel energy prediction model,*** treats neural networks as directed graphs and applies a bi-directional graph neural network training on a randomly generated dataset to extract structural features for energy *** has advantages over linear approaches because the bi-directional graph neural network collects structural features from each layer's parents and *** results show that NeurstrucEnergy establishes state-of-the-art results with mean absolute percentage error of 2.60%.We also evaluate NeurstrucEnergy in a randomly generated dataset,achieving the mean absolute percentage error of 4.83%over 10 typical convolutional neural networks in recent years and 7 efficient convolutional neural networks created by neural architecture *** code is available at https://***/NEUSoftGreenAI/***.

关键词： Internet of things Neural network energy prediction Graph neural networks Graph structure embedding Multi-head attention

Simulation of Temperature and Flow Field by Three Dimension Finite ElementMethod for Castex Process of AS Wire

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 262-267页

作者： Zhiyuan Shi1 Wanjun Wang1 Zhigang Kan2 Jinglin Wen3 Xinhua Wang1(l Metallurgy School, university of Science and Technology Beijing, Beijing 100083, China2 university of AViation and Spaceflight Beijing, Beijing 100083, China3 northeastern university, Metallurgy School University of Science and Technology Beijing Beijing 100083 China university of Aviation and Spaceflight Beijing Beijing 100083 China northeastern university Shenyang China

Castex of AS wire is a new technology of near net shape. To study the variation of temperature and velocity of liquid (or semisolid) aluminum during dynamic solidification the numerical simulation was carried out with the theory of heat-transfer and hydrodynamics by means of 3-dimensional finite element method. From simulation results, it is found that the variation of temperature and velocityis mainly influenced by the casting temperature of aluminum, rotating speed of Castex wheel and flow of cooling water. Among theseinfluencing factors, the casting temperature distributes most to the length of liquid phase metal. Moreover, the faster the metal solidifies,the higher the metal there moves with the overall trend of descending from the bottom of the wheel to the shoe wall as well as from sidewalls to the center of wheel groove. In comparison with the practical value, the simulation is reliable.

关键词： Castex dynamic solidification AS wire temperature and flow field, finite element method

Undercooling and solidification of germanium melts studied by differential scanning calorimeter

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Science China(Physics,Mechanics & Astronomy) 2004年第5期47卷 581-587页

作者： LI Qiang1,2,ZHU Yuying2,HE Yunha3,WANG Xu2,LI Gong1,YU Jinku1 & SU Zhibin1 1.Key Laboratory of Metastable Materials Science &Technology,Yanshan university,qinhuangdao 066004,China 2.Department of Mechanical Engineering,Yanshan university,qinhuangdao 066004,China 3.Department of Environmental & Chemical Engineering,Yanshan university,qinhuangdao 066004. China 1. Key Laboratory of Metastable Materials Science & Technology Yanshan University 066004 Qinhuangdao China 2. Department of Mechanical Engineering Yanshan University 066004 Qinhuangdao China 3. Department of Environmental & Chemical Engineering Yanshan University 066004 Qinhuangdao China

Differential scanning calorimeter combined with flux(dehydrated B2O3) processing was used to realize and precisely measure the undercooling of germanium *** highest undercooling obtained in this way was 190 *** between the undercooling and cooling rate or overheating tem-perature are analyzed *** undercooling obtained is found to be increased with increasing of the cooling rate in the range from 5 to 40 K/*** a given cooling rate,the undercooling reached is increased with the increasing of the overheating temperature of the melt,but tends to be constant at *** of the undercooled germanium melt is investigated at the same *** is clearly shown that,the higher the cooling rate,the shorter time is needed for crystallization.

关键词： germanium, undercooling, solidification, differential scanning calorimeter.

Prescribed Performance Tracking Control of Time-Delay Nonlinear Systems With Output Constraints

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1557-1565页

作者： Jin-Xi Zhang Kai-Di Xu Qing-guo Wang IEEE the State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China Institute of Artificial Intelligence and Future Networks Beijing Normal UniversityZhuhai 519087 Guangdong Key Laboratory of Artificial Intelligence and Multi-Modal Data Processing Beijing Normal University-Hong Kong Baptist University United International CollegeZhuhai 519087

The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requirements, i.e., boundedness and the local Lipschitz condition, are assumed for the allowable time delays. Moreover, we focus on the case where the reference is unknown beforehand, which renders the standard prescribed performance control designs under output constraints infeasible. To conquer these challenges, a novel robust prescribed performance control approach is put forward in this ***, a reverse tuning function is skillfully constructed and automatically generates a performance envelop for the tracking error. In addition, a unified performance analysis framework based on proof by contradiction and the barrier function is established to reveal the inherent robustness of the control system against the time delays. It turns out that the system output tracks the reference with a preassigned settling time and good accuracy,without constraint violations. A comparative simulation on a two-stage chemical reactor is carried out to illustrate the above theoretical findings.

关键词： Nonlinear systems output constraints prescribed performance reference tracking time delays