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Modeling and simulation of material distribution in the sequential co-injection molding process

Chinese Journal of Chemical Engineering 2022年第4期35卷 507-520页

作者： qingsheng liu Youqiong liu Chuntao Jiang School of Mathematics and Statistics Xinyang Normal UniversityXinyang 464000China

In co-injection molding,the properties and distribution of polymers will affect the application of *** focus of this work is to investigate the effect of molding parameters on the skin/core material distribution based on three-dimensional(3-D)flow and heat transfer model for the sequential coinjection molding process,and the flow behaviors and material distributions of skin and core melts inside a slightly complex cavity(dog-bone shaped cavity)are predicted *** governing equations of fluids in mold are solved by finite volume method and Semi-Implicit Method for Pressure Linked Equations(SIMPLE)algorithm on collocated meshes,and the domain extension technique is employed in numerical method for this cavity to assure that the numerical algorithm is implemented *** level set transport equation which is used to trace the free surfaces in co-injection molding is discretized and solved by the 5 th-order Weighted Essentially Non-Oscillatory(WENO)scheme in space and 3 rd-order Total Variation Diminishing Runger-Kutta(TVD-R-K)scheme in time *** simulations are conducted under various volume fraction of core melt,skin and core melt temperatures,skin and core melt flow *** predicted results of material distribution in length,width and thickness directions are in close agreement with the experimental results,which indicate that volume fraction of core melt,core melt temperature and core melt flow rate are principal factors that have a significant influence on material *** results demonstrate the effectiveness of the 3-D model and the corresponding numerical methods in this work,which can be used to predict the melt flow behaviors and material distribution in the process of sequential co-injection molding.

关键词： Co-injection molding Finite volume method Simulation Level set Material distribution

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Monitoring desertification processes in Mongolian Plateau using MODIS tasseled cap transformation and TGSI time series

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Journal of Arid Land 2018年第1期10卷 12-26页

作者： liu qingsheng liu Gaohuan HUANG Chong State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100111China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China

Most remote sensing studies assess the desertification using vegetation monitoring method. But it has the insufficient precision of vegetation monitoring for the limited vegetation cover of the desertification region. Therefore, it offers an alternative approach for the desertificafon research to assess sand dune and sandy land change using remote sensing in the desertification region. In this study, the indices derived from the well-known tasseled cap transformation （TCT）, tasseled cap angle （TCA）, disturbance index （DI）, process indicator （PI）, and topsoil grain size index （TGSI） were integrated to monitor and assess the desertification at the thirteen study sites including sand dunes and sandy lands distributed in the Mongolian Plateau （MP） from 2000 to 2015. A decision tree was used to classify the desertification on a regional scale. The average overall accuracy of 2000, 2005, 2010 and 2015 desertification classification was higher than 90%. Results from this study indicated that integration of the advantages of TCA, DI and TGSI could better assess the desertification. During the last 16 years, Badain Jaran Desert, Tengger Desert, and Ulan Buh Desert showed a relative stabilization. Otindag Sandy Land and the deserts of Khar Nuur, Ereen Nuur, Tsagan Nuur, Khongoryn Els, Hobq, and Mu Us showed a slow increasing of desertification, whereas Bayan Gobi, Horqin and Hulun Buir sandy lands showed a slow decreasing of desertification. Compared with the other 11 sites, the fine sand dunes occupied the majority of the Tengger Desert, and the coarse sandy land occupied the majority of the Horqin Sandy Land. Our findings on a three or four years＇ periodical fluctuated changes in the desertification may possibly reflect changing precipitation and soil moisture in the MR Further work to link the TCA, DI, TGSI, and PI values with the desertification characteristics is recommended to set the thresholds and improve the assessment accuracy with field investigation.

关键词： desertification MODIS desert sand dune sandy land Mongolian Plateau

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Effects of land use changes for ecological restoration on soil moisture on the Chinese Loess Plateau:a meta-analytical approach

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Journal of Forestry Research 2020年第2期31卷 443-452页

作者： Bowei Yu Gaohuan liu qingsheng liu State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101People’s Republic of China University of Chinese Academy of Sciences Beijing 100049People’s Republic of China

Soil moisture is an important resource for plant growth on the arid and semi-arid Loess Plateau of China where the‘‘Grain for Green’’project was launched in 1999,but there has been no systematic evaluation of soil moisture from the effects of ecological restoration at a regional *** systematically assessed 63 published studies during 2000-2015,including 2050 observations at 68 sites on the Loess Plateau with the aim of determining soil moisture changes and the factors influencing those *** found that,after land use conversion,soil moisture decreased by 17%in the upper 100 cm soil layer and that tree plantations and shrub lands appeared to cause soil moisture depletion which became increasingly serious with soil *** decrease of soil moisture was significantly influenced by the planting species in all restoration types(tree plantations,shrub lands,and grasslands).We also found that tree plantations and grasslands converted from farmlands consumed more soil moisture than from wasteland(including bare land,abandoned land and wild grasslands).Artificial restoration led to significant soil moisture reduction,but natural restoration had little effect on soil ***,natural restoration should be an alternative restoration practice on the Loess *** results will provide helpful information for artificial afforestation and planning ecological restoration campaigns for policy makers on water-limited regions.

关键词： Soil moisture Ecological restoration Land conversion Vegetation type Artificial afforestation

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Genetic algorithms for determining the parameters of cellular automata in urban simulation

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Science China Earth Sciences 2007年第12期50卷 1857-1866页

作者： LI Xia YANG qingsheng liu XiaoPing School of Geography and Planning Sun Yat-sen University Guangzhou 510275 China School of Geography and Planning Sun Yat-sen University Guangzhou 510275 China School of Geography and Planning Sun Yat-sen University Guangzhou 510275 China

This paper demonstrates that cellular automata(CA) can be a useful tool for analyzing the process of many geographical *** are many studies on using CA to simulate the evolution of *** dynamics is determined by many spatial *** contribution of each spatial variable to the simulation is quantified by its parameter or *** procedures are usually required for obtaining a suitable set of parameters so that the realistic urban forms can be *** pa-rameter has a unique role in controlling urban morphology in the *** this paper,these pa-rameters for urban simulation are determined by using empirical *** algorithms are used to search for the optimal combination of these *** are spatial variations for urban dynam-ics in a large *** sets of parameters can be used to represent the unique features of urban dynamics for various subregions.A further experiment is to evaluate each set of parameters based on the theories of compact *** is considered that the better set of parameters can be identified ac-cording to the utility function in terms of compact *** set of parameters can be cloned to other regions to improve overall urban *** original parameters can be also modified to produce more compact urban forms for planning *** approach can provide a useful ex-ploratory tool for testing various planning scenarios for urban development.

关键词： Cellular automata, genetic algorithms, planning scenarios, compact development

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New approach to develop a 3D non-isothermal computational framework for injection molding process based on level set method

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Chinese Journal of Chemical Engineering 2016年第7期24卷 832-842页

作者： Xin Zhuang Jie Ouyang Chuntao Jiang qingsheng liu Department of Applied Mathematics Northwestern Polytechnical University

The simulation of three-dimensional （3D） non-isothermal, non-Newtonian fluid filling process is an extremely difficult task and remains a challenging problem, which includes polymer melt flow with free surface coupled with transient heat transfer. This paper presents a full 3D non-isothermal two-phase flow model to predict the complex flow in melt filling process, where the Cross-WLF model is applied to characterize the rheological behav- ior of polymer melt. The governing equations are solved using finite volume method with SIMPLEC algorithm on collocated grids and the melt front is accurately captured by a high resolution level set method. A domain exten- sion technique is adopted to deal with the complex cavities, which greatly reduces the computational burden. To verify the validity of the developed 3D approach, the melts filling processes in two thin rectangular cavities （one of them with a cylindrical insert） are simulated. The predicted melt front interfaces are in good agreement with the experiment and commercial software prediction. For a case with a rather complex cavity, the dynamic filling process in a hemispherical shell is successfully simulated. All of the numerical results show that the developed numerical procedure can provide a reasonable orediction for injection molding process.

关键词： Injection moldingNon-isothermalFinite voIume/SIMPLEC methodDomain extension techniqueHigh resolution level set method

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Remote Sensing Monitoring of Surface Characteristics in the Badain Jaran, Tengger, and Ulan Buh Deserts of China

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Chinese Geographical Science 2019年第1期29卷 151-165页

作者： liu qingsheng liu Gaohuan HUANG Chong LI He State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application

Deserts and sandy land in northern China are very susceptible to sandy desertification and are the main source of sand-dust storms of Asian dust. However, because of the complex factors involved, descriptions of the relationship between sandy desertification and surface characteristics in these regions are lacking. We monitored the surface characteristics and their changes in time using information about soil, vegetation, and landforms in the Badain Jaran Desert(BJD), Tengger Desert(TD), and Ulan Buh Desert(UBD) in the northern China. The monitoring was done using tasseled cap angle(TCA), disturbance index(DI), and topsoil grain size index(TGSI) from Moderate Resolution Imaging Spectroradiometer(MODIS) images combined with a decision tree classification. Results showed that the TD had higher topsoil fine sand content, and the ratio of non-vegetated to vegetated areas was similar with that in the UBD. Northeast-southwest coarse sand dunes with thin interdune(NECTI) dominated the BD, fine sand dunes(FSD) dominated the TD, and a combination of northeast-southwest coarse sand dunes with wide interdune(NECWI) and northwest-southeast coarse sand dunes with wide interdune(NWCWI) dominated the UBD. From 2000 to 2015, in the BJD the area of the NECTI, non-sand dune(Non) and potential sand sources(PSS) increased, whereas the area of the NECWI, FSD and NWCWI decreased, indicating a improve process in the BJD. In the TD, the area covered by Non increased, whereas the area covered by PSS, NECWI, NECTI, FSD, and NWCWI decreased from 2000 to 2015. The area covered by the various surface characteristic types fluctuated annually in the UBD from 2000 to 2015. Changes in surface characteristics reflect the combined effects of natural conditions and human activity. The findings of our study will assist scientists and policy makers in proposing different management techniques to combat sandy desertification for the different surface characteristics of these regions.

关键词： surface characteristics MODIS desert tasseled cap angle disturbance index topsoil grain size index

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High-efficiency simultaneous extraction of rare earth elements and iron from NdFeB waste by oxalic acid leaching

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Journal of Rare Earths 2021年第3期39卷 323-330,I0004页

作者： qingsheng liu Tao Tu Hao Guo Huajin Cheng Xuezhong Wang Faculty of Materials Metallurgy and Chemitry Jiangxi University of Science and TechnologyGanzhou 341000China Science School Jiangxi University of Science and TechnologyGanzhou 341000 China College of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013China

Iron can not be recovered at high value because only rare earth elements are effectively recovered from NdFeB waste via oxidation roasting-hydrochloric acid leaching *** this study,a new method for leaching NdFeB waste with oxalic acid was *** high-efficiency,simultaneous and high-value recovery of rare earth elements and iron was realized to simplify the process and improve the economic *** of the oxalic acid leaching experiments show that under the optimum leaching conditions at 90℃ for 6 h in the aqueous solution of oxalic acid(2 mol/L) with a liquid-solid ratio of60 mL/g,the iron leaching efficiency and precipitation rate of rare earth oxalate reach 93.89% and 93.17%,*** earth oxalate and Fe(C_(2)O_(4))3^(3-) were left in the residue and the leaching solution,*** leaching mechanism was further analyzed by characterising the leach residues obtained through X-ray powder diffraction(XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDS).Results of the leaching kinetics study indicate that the process of oxalic acid leaching follows the shrinking nucleus model,and the leaching kinetics model is controlled by the mixed factors of diffusion and chemical *** leaching residue was calcined at 850℃ for 3 h and then decomposed into rare earth oxide,which can be directly used to prepare rare earth alloy via molten salt *** the leaching solution,ferric oxalate solution was reduced using Fe powder to prepare the ferrous oxalate(FeC_(2)O_(4)-2H_(2)O).

关键词： NdFeB waste Oxalic acid Orthogonal experiment Leaching kinetics Reduction precipitation Rare earths

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Spatial Pattern Induced by Cross-Diffusion in a Chemostat Model with Maintenance Energy

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Journal of Donghua University(English Edition) 2018年第6期35卷 469-472页

作者： liu qingsheng PENG Yahong College of Science Donghua University

A chemostat model with maintenance energy and crossdiffusion is considered,and the formation of patterns is caused by the cross-diffusion. First, through linear stability analysis, the necessary conditions for the formation of the spatial patterns are given. Then numerical simulations by changing the values of crossdiffusions in the unstable domain are performed. The results showthat the cross-diffusion coefficient plays an important role in the formation of the pattern, and the different values of the crossdiffusion coefficients may lead to different types of pattern formation.

关键词： pattern formation chemostat model cross-diffusion Turing instability stability

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Schematic Road Network Map Progressive Generalization Based on Multiple Constraints

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Geo-Spatial Information Science 2008年第3期11卷 215-220页

作者： DONG Weihua GUO qingsheng liu Jiping Institute of Geography and Remote Sensing Beijing Normal University 19 Xinjiekouwai Street Beijing 100875 China.

Multiple constraints for schematic road network map cartographic design are analyzed and summarized. Based on this, a set of quantitative criteria are set up and a new road network generalization method including progressive selection and displacement is proposed. Furthermore, topological checking methods for road networks are researched. Based on these constraints, the points in a road network are classified, and a satisfactory and effective schematic map is designed in a con- crete experiment while maintaining topological consistency of the road network between the original and the schematic map

关键词： schematic map spatial cognition progressive cartographic generalization graphic simplification

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Interpretation of Aeromagnetic Anomalies of the Sulu Ultrahigh-Pressure(UHP) Metamorphic Belt,Eastern China

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地学前缘 2009年第S1期16卷 214-215页

作者： Ning Qiu,qingsheng liu Institute of Geophysics and Geomatics,China University of Geosciences(Wuhan),Wuhan 430074,China.

The Sulu ultra-high pressure(UHP)metamorphic belt in Eastern China is well known as the eastern extension of the Qingling-Dabie orogenic belt formed by subduction and collision between the Sino-Korean and Yangtze *** main hole of the Chinese Continental Scientific Drilling(CCSD)project is located at the southern segment of the Sulu UHP metamorphic belt(34°25′N/118°40′E),about 17 km southwest of Donghai *** geophysical investigations using gravity,magnetic,deep

关键词： aeromagnetic ultrahigh-pressure(UHP) metamorphic belt Chinese Continental Scientific Drilling(CCSD) Sulu

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