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An Automatic Forecasting Method for Time Series

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Chinese Journal of Electronics 2017年第3期26卷 445-452页

作者： liu Shufen GU Songyuan bao Tie College of Computer Science and Technology Jilin University

An automatic forecasting method is proposed concerning automation problem in the field of linear time series forecasting. The method is on the basis of econometric theory and overcomes the difficulty to mine and forecast automatically with econometric models. The proposed algorithm is divided into 4 stages, i.e. preprocessing, unit root testing and stationary processing, modeling,and ultimately forecasting. Future values and trends would be estimated and forecasted precisely through the 4 stages of the algorithm according to input data without manual intervention. Experimental comparisons were made between the proposed algorithm and the 2 data driven forecasting algorithms, i.e. moving average method and Holt exponential smoothing method. It was demonstrated with the experimental results that automatic forecasting is feasible utilizing the proposed algorithm and higher accuracy can be acquired than these 2 data driven-based methods.

关键词： Time series Automatic forecasting Unit root test Autoregressive integrated moving average(ARIMA) model

Electrodeposited 3D hierarchical NiFe microflowers assembled from nanosheets robust for the selective electrooxidation of furfuryl alcohol

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Green Energy & Environment 2023年第3期8卷 874-882页

作者： Biying liu man Zhang Yaoyu liu Yuchen Wang Kai Yan Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology School of Environmental Science and EngineeringSun Yat-sen University135 Xingang Xi RoadGuangzhou510275China

A robust and green strategy for the selective upgrading of biomass-derived platform chemicals towards highly valuable products is important for the sustainable ***,the efficient electrocatalytic oxidation of biomass-derived furfuryl alcohol(FFA)into furoic acid(FurAc)catalyzed by the electrodeposited non-precious NiFe microflowers was successfully reached under the low temperature and ambient *** 3D hierarchical NiFe microflowers assembled from ultrathin nanosheets were controllably synthesized by the electrodeposition method and uniformly grown on carbon fiber paper(CFP).Electrochemical analysis confirmed that NiFe nanosheets more preferred in the selective oxidation of FFA(FFAOR)than oxygen evolution reaction(OER).The linear sweep voltammetry(LSV)in FFAOR displayed a clear decrease towards lower potential,resulting in 30 mV reduction of overpotential at 20 mA cm^(-2) compared with that of *** optimal catalyst Ni_(1)Fe_(2) nanosheets exhibited the highest selectivity of FurAc(94.0%)and 81.4%conversion of FFA within 3 ***,the influence of various reaction parameters on FFAOR was then explored in *** that,the reaction pathway was investigated and rationally *** outstanding performance for FFAOR can be ascribed to the unique structure of 3D flower-like NiFe nanosheets and oxygen vacancies,resulting in large exposure of active sites,faster electron transfer and enhanced adsorption of *** findings highlight a facile and convenient mean with a promising green future,which is promising for processing of various biomass-derived platform chemicals into value-added products.

关键词： Electrodeposition Microflowers assembled by nanosheets NiOOH Oxygen vacancies Electrochemical oxidation Furfuryl alcohol Furoic acid

New chaotic system and its hyperchaos generation

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Journal of Systems Engineering and Electronics 2009年第6期20卷 1179-1187页

作者： bao Bocheng liu Zhong Xu Jianping Dept. of Electronic Engineering Nanjing Univ. of Science and Technology Nanjing 210094 P. R. China School of Electrical and Information Engineering Jiangsu Teachers Univ. of Technology Changzhou 213001 P. R. China School of Electrical Engineering Southwest Jiaotong Univ. Chengdu 610031 P. R. China

To seek for lower-dimensional chaotic systems that have complex topological attractor structure with simple algebraic system structure, a new chaotic system of three-dimensional autonomous ordinary differential equations is presented. The new system has simple algebraic structure, and can display a 2-scroll attractor with complex topological structure, which is different from the Lorenz＇s, Chen＇s and Lu¨＇s attractors. By introducing a linear state feedback controller, the system can be controlled to generate a hyperchaotic attractor. The novel chaotic attractor, hyperchaotic attractor and dynamical behaviors of corresponding systems are further investigated by employing Lyapunov exponent spectrum, bifurcation diagram, Poincar′e mapping and phase portrait, etc., and then verified by simulating an experimental circuit.

关键词： chaotic system attractor chaos hyperchaos.

A 1556 year-long early summer moisture reconstruction for the Hexi Corridor, Northwestern China

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Science China Earth Sciences 2019年第6期62卷 953-963页

作者： bao YANG Jianglin WANG Jingjing liu Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences

We report a 1556 year-long tree-ring width chronology for the Hexi Corridor, in the arid Northwestern China,established by applying the signal-free regional curve standardization method to 416 juniper ring-width series. We found that drought in early summer(May–June) is the primary controlling factor for tree growth in this area. We then developed an early summer moisture(i.e., scPDSI) reconstruction from 455 CE to present. Our reconstruction captures multi-centennial scale moisture variations, showing two long-term dry periods during 800–950 CE and 1000–1200 CE, and two long-term wet periods during 1200–1450 CE and 1510–1620 CE. We found strong similarities between hydroclimatic changes in the Hexi Corridor and Qaidam Basin from interannual to centennial timescales; however, at multi-centennial(>300 years) timescales, hydroclimatic variations in the two regions showed significant regional differences. The Hexi Corridor witnessed a generally dry Medieval Climate Anomaly(MCA, here 800–1200 CE) and the drying 20 th century, whereas the Qaidam Basin experienced highprecipitation periods during the MCA and 20 th century. The different correlation pattern with Northern Hemisphere temperature suggest that the Qaidam Basin will receive more precipitation under global warming, whereas the Hexi Corridor will become dryer in the future.

关键词： Hexi Corridor Tree-ring index Early-summer Hydroclimate reconstruction

Electrolytic groundwater circulation well for trichloroethylene degradation in a simulated aquifer

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Science China(Technological Sciences) 2021年第2期64卷 251-260页

作者： YUAN SongHu liu Yang ZHANG Peng TONG man liu Hui State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China

An in situ groundwater remediation process, termed EGCW, was developed in this study by integrating in-well groundwater electrolysis into groundwater circulation well. Groundwater circulation carries electrolytically generated O2 and H2 into the impacted aquifer for in situ biodegradation of contaminants. In a two-dimensional tank filled with field sandy sediments,simulated trichloroethylene(TCE)-contaminated groundwater was circulated between an injection well with electrodes inside and a pumping well. Results from a 50-day EGCW experiment show that in-well electrolysis oxygenated most region near the injection well, and 10 mg/L TCE was mainly biodegraded aerobically to about 2.7 mg/L(73% removal) by the indigenous microbes. Aerobic TCE degradation was enhanced by the pulsed addition of acetate. Together with the proofs of stable carbon isotope fractionation(enrichment factor:-0.57‰–-1.53‰) and microbial community variation after EGCW treatment, aerobic cometabolism was proposed to be the most likely mechanism for TCE degradation. It is interesting to find that the intrinsic organic carbon in aquifer matrix could fuel the aerobic TCE degradation, particularly at low TCE concentrations. EGCW treatment is advantageous in terms of supplying appropriate dosages of electron acceptor(O_(2)) and donor(H_(2)) for in situ bioremediation because groundwater electrolysis and circulation are expedient and controllable.

关键词： electrolytic remediation groundwater circulation wells chlorinated solvents biodegradation

Littlewood–Paley Operators on Spaces with Variable Exponent on Homogeneous Groups

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Acta Mathematica Sinica,English Series 2020年第5期36卷 535-558页

作者： Dong Li liu Ji man ZHAO Key Laboratory of Mathematics and Complex Systems Ministry of Education Institution of Mathematics and Mathematical Education School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

In this paper,on homogeneous groups,we study the Littlewood–Paley operators in variable exponent ***,we prove that the weighted Littlewood–Paley operators are controlled by the weighted Hardy–Littlewood maximal function,and obtain the vector-valued inequalities of the Littlewood–Paley operators,including the Lusin function,Littlewood–Paley g function and gλ* ***,we prove the boundedness of multilinear Littlewood–Paley gψ,λ* function.

关键词： Littlewood–Paley operators variable Lebesgue spaces homogeneous groups

Reactor protection system testing for the solid fuel thorium molten salt reactor

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Nuclear Science and Techniques 2016年第5期27卷 238-246页

作者： Zhen-bao liu Ye liu Gui-Min liu Jie Hou Shanghai Institute of Applied Physics Chinese Academy of Sciences Jiading campus Shanghai 201800 China University of Chinese Academy of Sciences Beijing 100049China

Safety system testing is one of the most rigorous and time-consuming requirements in the verification and validation process for reactor protection systems(RPSs).This paper presents the development of a test system for the fully digital and field-programmable gate array-based RPS of the solid fuel(SF) thorium-breeding molten salt pebble bed fluoride salt-cooled reactor(TMSR),denoted as the TMSR-SF1 project,developed by the Chinese Academy of *** test system is applied to the RPS to ensure that it fully meets its designed functions and system *** first introduce the testing principles and ***,the hardware component designs and the software program development of the test system are ***,the test process and test results are discussed and summarized.

关键词：反应堆保护系统试验过程固体燃料熔盐现场可编程门阵列测试系统钍设计功能

Mechanism for transmittance light tunable property of nanocrystalline Eu-doped SmB_(6):Experimental and first-principles study

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Journal of Rare Earths 2021年第9期39卷 1100-1107页

作者： Lihong bao Jun Ning Narengerile Zizhong liu College of Physics and Electronic Information.Inner Mongolia Normal University.Hohhot 010022 China Inner Mongolia Key Laboratory for Physics and Chemistry of Functional Materials.Inner Mongolia Normal University Hohhot 010022.China College of Chemistry and Enviormental Science

Binary nanocrystalline rare-earth hexaboride is regarded as one of the promising optical absorption materials that possess the high transparency for visible light and the strong absorption for NIR due to the effects of localized surface plasmon *** present work,we experimentally investigated the structural and optical absorption of ternary nanocrystalline Eu-doped SmB6 *** a result,it is found that the reaction temperature as an important factor not only refines the grain size,but also improves the powder dispersion of synthesized *** optical absorption results reveal that the transmittance wavelength of nanocrystalline SmB6 increases from 696 nm to exceeding 1000 nm with the Eu doping content increasing to x=*** retically,in order to study the transmittance wavele ngth tunable mechanisms of nanocrystalline Eu-doped SmB6,the electronic structure,density of states and energy loss function were calculated by first-principle *** shows that the En2+doping into SmB6 effectively reduces the plasma frequency excitation energy from 1.48 to 1.25 eV and leads to the transmittance wavelength redshift toward a higher *** on above meaningful studies,present work is helpful for extension of optical applications of nanocrystalline SmB6 powder.

关键词： Nanocrystalline SmB_(6) Optical property First-principles calculation Rare earths

Influence of shaped charge structure parameters on the formation of linear explosively formed projectiles

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Defence Technology（防务技术） 2022年第10期18卷 1863-1874页

作者： Tian-bao Ma Jing liu Qi Wang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

The research of LEFP(linear explosive forming projectile)is of great value to the development of new warhead due to its excellent *** further improve the damage ability of the shaped charge warhead,a special shell overhanging structure was designed to increase the charge based on the traditional spherical charge,in which case the crushing energy of LEFP could be ***-DYNA was used to simulate different charge structures obtained by changing the number of detonation points,the length of shell platform,the radius of curvature and the thickness of *** RSM(response surface model)between the molding parameters of LEFP and the structural parameters of charge was *** on RSM model,the structure of shaped charge was optimized by using multi-objective genetic ***,the formation process of jet was analyzed by pulsed X-ray *** results show that the velocity,length-diameter ratio and specific kinetic energy of the LEFP were closely related to the structural parameters of the shaped *** the optimization of charge structure,the forming effect and penetration ability of LEPP had been significantly *** experimental data of jet velocity and length were consistent with the numerical results,which verifies the reliability of the numerical results.

关键词： LEFP Numerical simulation Shaped charge Structure optimization