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Acta Mathematicae Applicatae Sinica 2008年第4期24卷 691-705页

作者： wei-guo Zhang Shao-wei Li wei-zhong Tian Lu Zhang College of Science University of Shanghai for Science and Technology Shanghai 200093 China School of mathematics and information engineering Taizhou university Zhejiang 317300 China

By means of the undetermined assumption method, we obtain some new exact solitary-wave solutions with hyperbolic secant function fractional form and periodic wave solutions with cosine function form for the generalized modified Boussinesq equation. We also discuss the boundedness of these solutions. More over, we study the correlative characteristic of the solitary-wave solutions and the periodic wave solutions along with the travelling wave velocity＇s variation.

关键词： Generalized modified Boussinesq equation exact solitary-wave solution periodic wave solution

Optimal stopping time on discounted semi-Markov processes

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Frontiers of Mathematics in China 2021年第2期16卷 303-324页

作者： Fang CHEN Xianping GUO zhong-wei LIAO School of Mathematics Sun Yat-Sen UniversityGuangzhou 510275China College of Education for the Future Beijing Normal UniversityBeijing 100875China

This paper attempts to study the optimal stopping time for semi- Markov processes (SMPs) under the discount optimization criteria with unbounded cost rates. In our work, we introduce an explicit construction of the equivalent semi-Markov decision processes (SMDPs). The equivalence is embodied in the expected discounted cost functions of SMPs and SMDPs, that is, every stopping time of SMPs can induce a policy of SMDPs such that the value functions are equal, and vice versa. The existence of the optimal stopping time of SMPs is proved by this equivalence relation. Next, we give the optimality equation of the value function and develop an effective iterative algorithm for computing it. Moreover, we show that the optimal and ε-optimal stopping time can be characterized by the hitting time of the special sets. Finally, to illustrate the validity of our results, an example of a maintenance system is presented in the end.

关键词： Optimal stopping time semi-Markov processes(SMPs) value function semi-Markov decision processes(SMDPs) optimal policy iterative lgorithm

Microtextural evolution of different TRC AA8006 alloy sections with homogenization

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International Journal of Minerals,Metallurgy and Materials 2015年第3期22卷 292-301页

作者： zhong-wei Chen Long-fei Shen Jing Zhao State Key Laboratory of Solidification Processing Northwestern Polytechnical University

Grain microtexture evolution in twin-roll cast AA8006 alloy sheets subjected to different treatments was investigated using elec- tron backscatter diffraction. The textures of rolling-transverse and normal-transverse sections were characterized in original as-cast twin-roll casting and cold-rolled samples as well as samples homogenized at 500℃for 8 h and at 580℃ for 4 h. It is found that grains on both the rolling-transverse and normal-transverse sections of cold-rolled samples are made fmer by rolling deformation and coarsened after homog- enization. Annealing temperature has a stronger effect on the microstructural evolution than annealing time. The grain growth direction is parallel to the normal-transverse section, while grain deformation is more stable on the rolling direction than on the normal direction. The rolling orientations display more obvious anisotropy on the normal-transverse sections than on the rolling-transverse sections. Grain recrys- tallization and growth occur much easier on the normal-transverse section than on the rolling-transverse section for samples homogenized at 500℃ for 8 h. A special misorientation relationship between cold deformation texture, such as S orientation { 123 } 〈634〉 and cube orienta- tion 〈110〉Xaxis [cubic], and recrystallization texture after homogenization, such as R orientation { 124}〈211〉 and P orientation {011 }〈122〉, is observed.

关键词： aluminum alloys textures twin-roll casting homogenization

Climatic warming in Shanghai during 1873-2019 based on homogenised temperature records

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Advances in Climate Change Research 2022年第4期13卷 496-506页

作者： Ping LIANG zhong-wei YAN Zhen LI Key Laboratory of Cities'Mitigation and Adaptation to Climate Change in Shanghai Shanghai Regional Climate CenterShanghai 200030China Key Laboratory of Regional Climate-Environment for East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

Xujahui(XJH)station in downtown Shanghai holds the longest continuous daily temperature series in China,which is unique for assessing modern climate change and impacts but must be *** present work established a set of homogenised monthly and daily surface air temperature(SAT)series during 1873-2019 at *** major inhomogeneous break points(around 1954 and 1993)were identified in the original SAT series,which had been overlooked in previous *** inhomogeneous biases were adjusted via the inter-station deviation *** adjusted SAT series shows a warming trend of 1.9℃ per century compared with 1.7℃ per century in the original *** multi-decadal variations of quasi-32-year and quasi-64-year periods are weaker in the adjusted series than in the original series,suggesting overestimated multi-decadal variability in the original data due to inhomogeneous *** to the early period 1873-1900,the recent decade(the 2010s)is warmer by 2.2℃.Urbanisation has been responsible for approximately 19.3%of the rapid warming since the *** high and low SAT extremes exhibit significant warming,especially after the *** trend in the low SAT extremes in the adjusted series is substantially larger than that in the original series,implying that previous studies might underestimate the warming in cold extremes.

关键词： Homogenised temperature series Long-term climate warming Effect of urbanisation Muli-decadal variability

Microstructure and microhardness of nanostructured Al-4.6Cu-Mn alloy ribbons

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International Journal of Minerals,Metallurgy and Materials 2015年第8期22卷 860-867页

作者： zhong-wei Chen Qin-ying Fan Kai Zhao State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The microstructural characteristics and microhardness of nanostructured Al-4.6Cu-Mn ribbons produced by melt spinning were investigated using field-emission gun scanning electron microscopy, transmission electron microscopy, and hardness testing, and the results were compared to those of similar ribbons manufactured by direct-chill casting. It is shown that the nanostructure of the as-melt-spun ribbons consists of α-Al dendrites with a secondary dendrite arm spacing of approximately 0.55-0.80 μm and ultrafine eutectic crystals of a nanosized scale of approximately 100-200 nm on dendritic boundaries. The solidification time and cooling rate of 46-μm-thick ribbons were estimated to be 1.3 × 10-6 s and 4.04 × 106 K·s-1, respectively. At an aging temperature of 190°C, the coherent θ″ phase in aged ribbons gradually transforms into nanoscale θ′-phase platelets as the aging time is extended from 2 to 8 h; the rod-like morphology of the T(Al20Cu2Mn3) dispersoid with 120-160-nm diameter also forms, which results in peak aging hardness. The precipitation behaviors of aged ribbons cannot be changed at the high cooling rates of as-cast ribbons. However, a finer and more uniformly distributed microstructure and a supersaturated solid solution at a high cooling rate can shorten the time required to obtain a certain aging hardness before peak hardness.

关键词： aluminum-copper-manganese alloys nanoribbons melt

Microstructure and texture evolution of TRC A8006 alloy by homogenization

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International Journal of Minerals,Metallurgy and Materials 2013年第5期20卷 433-439页

作者： zhong-wei Chen Jing Zhao Xiao-lei Hao State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The microstructure and texture evolution of twin-roll cast A8006 alloy by homogenization were characterized using scanning and transmission electron microscopy, and the microhardness was tested as well. According to the relation- ship between dendritic arm spacing and cooling rate the cooling rate of the as-cast twin-roll cast A8006 sheet of 6 mm in thickness was estimated as 1.48×10^3 K·s^-1. It is found that the grains and the nanostructural precipitates of the twin-roll cast sheet become coarser after homogenization at 580℃ for 4 h in comparison with those after homogenization at 500℃ for 8 h. The textures formed after cold rolling and became weaker during homogenization. The increase in hardness of the as-cast twin-roll cast sheets is related in hardness after homogenization can to the supersaturated a-A1 solid solution and be attributed to the coarsening of grains and fine microstructure, but the decrease Al6Fe（Mn） precipitates.

关键词： aluminum alloys homogenization microstructure textures hardness

Effect of rare earth samarium addition on the kinetics of precipitation in Al-Cu-Mn casting alloy

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 155-161页

作者： zhong-wei Chen Ming-jun Tang Kai Zhao State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The mechanical properties of Al-Cu-Mn casting alloy mainly depend on the morphology, distribution, size, and number ofθ′（Al2Cu） precipitates. In this study, we have analyzed the effect of rare earth samarium （Sm） addition on the kinetics of precipitation in the Al-Cu-Mn casting alloy by using differential scanning calorimetry （DSC） and high-resolution transmission electron microscopy. Thermal ef-fect peaks that are attributed to the formation and the dissolution of Guinier-Preston （GP） zone andθ′phase were identified from the DSC curves. The activation energy ofθ′formation was calculated by using both the Kissinger method and the analytical model, and the corre-sponding results were compared. Results suggest that the activation energy ofθ′formation in Al-Cu-Mn alloy is dramatically higher than that in Al-Cu-Mn-Sm alloy. Accordingly, it is concluded that the addition of rare earth Sm decreases the activation energy ofθ′formation and promotes the formation ofθ′precipitates.

关键词： aluminum copper alloys rare earth additions samarium precipitation kinetics

XML-based Data Processing in Network Supported Collaborative Design

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International Journal of Automation and computing 2010年第3期7卷 330-335页

作者： Qi Wang zhong-wei Ren zhong-Feng Guo School of Mechanical Engineering Shenyang University of Technology Shenyang 110870 PRC

In the course of network supported collaborative design, the data processing plays a very vital role. Much effort has been spent in this area, and many kinds of approaches have been proposed. Based on the correlative materials, this paper presents extensible markup language （XML） based strategy for several important problems of data processing in network supported collaborative design, such as the representation of standard for the exchange of product model data （STEP） with XML in the product information expression and the management of XML documents using relational database. The paper gives a detailed exposition on how to clarify the mapping between XML structure and the relationship database structure and how XML-QL queries can be translated into structured query language （SQL） queries. Finally, the structure of data processing system based on XML is presented.

关键词： Extensible markup language (XML) network supported collaborative design standard for the exchange of product model data (STEP) data analysis data processing relational database

DRY-WET EVOLUTION IN GUANGDONG PROVINCE DURING LAST 500 YEARS

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Chinese Geographical Science 2006年第1期16卷 63-69页

作者： XUE Ji-bin zhong wei ZHEN Zhi-guo LIU wei School of Geography Science South China Normal University Guangzhou 510631 P.R. China

Based on the historical records in Guangdong Province during the last 500a, the moist index sequence was reconstructed and analyzed by the correlation analysis, wavelet analysis and the power spcctrum analysis. The resuits indicate that： 1 ） The El Nino events have evident correlations with the droughts happened in the west and north of Guangdong Province, which intensified the dryness and wetness distribution patterns in these areas in a certain degree. 2） Good correspondence relations exist among the moist index sequence, Greenland ice core oxygen isotope record and the winter-half-year temperature sequence in the eastern China, which showed pattern of moisture and temperature. 3） By applying the wavelet analysis to deal with icities are revealed, among which some can be attributed to the solar activities. At monsoon （especially the East Asian monsoon） activity and the human activity may an apparent monsoonal disposal the data, several apparent period. the same tithe, the ENSO event, also have some influences on the periodicities of the climatic changes in Guangdong Province. 4） Guangdong will persist in dry period before 2040 （±5 years） though some little waterlogged period will also exist in this interval, and after that great floods maybe take place in Guangdong. We think that the variety range of the dryness and wetness has increasing tendency in Guangdong Province in future several even hundred years.

关键词： dry-wet evolution El Nino monsoon solar activity Guangdong Province

Applying Big Data Based Deep Learning System to Intrusion Detection

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Big Data Mining and Analytics 2020年第3期3卷 181-195页

作者： wei zhong Ning Yu Chunyu Ai Division of Math and Computer Science University of South Carolina UpstateSpartanburgSC 29303USA Department of Computing Sciences State University of New York College at BrockportBrockportNY 14420USA

With vast amounts of data being generated daily and the ever increasing interconnectivity of the world’s internet infrastructures,a machine learning based Intrusion Detection Systems(IDS)has become a vital component to protect our economic and national *** shallow learning and deep learning strategies adopt the single learning model approach for intrusion *** single learning model approach may experience problems to understand increasingly complicated data distribution of intrusion ***,the single deep learning model may not be effective to capture unique patterns from intrusive attacks having a small number of *** order to further enhance the performance of machine learning based IDS,we propose the Big Data based Hierarchical Deep Learning System(BDHDLS).BDHDLS utilizes behavioral features and content features to understand both network traffic characteristics and information stored in the *** deep learning model in the BDHDLS concentrates its efforts to learn the unique data distribution in one *** strategy can increase the detection rate of intrusive attacks as compared to the previous single learning model *** on parallel training strategy and big data techniques,the model construction time of BDHDLS is reduced substantially when multiple machines are deployed.

关键词： intrusion detection deep learning convolution neural network fully connected feedforward neural network multi-level clustering algorithm