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COUPLED SIMULATION OF 3D ELECTRO-MAGNETO-FLOW FIELD IN HALL-HEROULT CELLS USING FINITE ELEMENT METHOD

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 105-116页

作者： J. Li W. Liu Y.q. lai q.Y. Li Y.x. Liu School of Metallurgy Science and Engineering Central South University Changsha 410083 China Chemistry Department Guangxi Normal University Guilin 531400 China

Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.

关键词： coupled simulation electromagnetic field flow field aluminum reduction cell finite element analysis

THERMAL STRESSES RELAxATION DESIGN OF Ni/NiFe_(2)O_(4) SYSTEM FUNCTIONALLY GRADED CERMET INERT ANODE

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Acta Metallurgica Sinica(English Letters) 2005年第5期18卷 635-641页

作者： J. Li q.S. Zhang Y.q. lai S.L. Ye Y.x. Liu School of Metallurgy Science and Engineering Central South University Changsha 410083 China

The thermal stresses relaxation of Ni/NiFe2O4 system functionally graded cermet inert anode for aluminum electrolysis was optimally designed. The transient thermal stresses of the inert anode under complex boundary condition during high-temp （955℃） electrolysis were calculated using the finite-element software ANSYS, the influence of different parameters on the distribution of the thermal stresses were analyzed. The results showed that, during the process of thermal shock, the thermal hoop tensile stress on the surface of the anode is very large, which is possibly the major cause of anode crack; when the radius of the anode is between 0.05-0.15m, a range that can be realized by recent manufacturing technology, the optimum composition distribution exponent p is 0.25; The hoop tensile stresses reduce with the decrease of anode scale and also decrease with the decrease of the convection coefficient between the electrolyte and the anode.

关键词： functionally graded material (FGM) transient thermal stresses ANSYS inert anode aluminum electrolysis

EFFECT OF Cu-Ni CONTENT ON THE CORROSION RESISTANCE OF(Cu-Ni)/(10NiO-90NiFe_2O_4)CERMET INERT ANODE FOR ALUMINUM ELECTROLYSIS

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 72-78页

作者： Z.L. Tian Y.q. lai J. Li Y.x. Liu School of Metallurgical Science and Engineering Central South University Changsha 410083 China

（Cu-Ni）/（10NiO-90NiFe204） cermet inert anodes containing metal Cu-Ni0, 5, 10, 15 and 20 wt pct were prepared and their corrosion resistance to Na3AlF6-Al2O3 melts was investigated. The results indicate that the content of metal Cu-Ni has little effect on the steady-state concentration of Ni in the electrolyte and the values could not be used to effectively differentiate their corrosion resistance. The steady-state concentration of Fe decreases from 304×10^-6 to 168×10^-6 and that of Cu increases from 21×10^-6 to 71×10^-6 with the content of metal Cu-Ni increasing from 0 to 20 wt pct. Post-examination shows that metallic phase Cu-Ni is corroded preferentially during electrolysis and many pores are left at the anode surface. Considering the corrosion resistance and electrical conductivity, the cermet containing metal Cu-Ni 5 wt pct should be selected and studied further.

关键词： Aluminum electrolysis Inert anode NiFe2O4 based cermet Corrosion resistance

FREEZE PROFILE AND HEAT BALANCE CALCULATION OF THE 160kA DRAINED CELL

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Acta Metallurgica Sinica(English Letters) 2004年第2期17卷 215-220页

作者： x.P. Li J. Li Y.q. lai H.q.Zhao Y.x.Liu School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China School of Metallurgical Science and Engineering Central South UniversityChangsha 410083China

A 2D full cell thermo-electric model of 160kA drained cell was set up using finiteelement code to calculate its freeze profile, then the drained cell model was modifiedaccording to the freeze profile computed and its heat balance was calculated. Comparedwith that of a 160kA conventional Hall-Heroult cell (H-H cell), though the melts vol-ume of the drained cell reduced greatly, the whole heat loss from it didn't drop downapparently, and an analysis was presented in the paper. On the other hand, the anode-cathode distance (ACD) of a drained cell was much less than that of a H-H cell, sothe voltage drop on it and heat produced decreased too, steps should be taken to keepa workable heat balance on a drained cell.

关键词： drained cell freeze profile heat balance finite element code

An Application of Double Exponential Smoothing Technique to quality Control

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数理统计与管理 1993年第5期 43-48页

作者： C.D.lai D.q.Wang Dapartment of Statistics Massey University New Zealand

休哈特控制图和ＳＵＳＵＭ控制图技术，在制造业得到广泛应用．Ｊ．Ｓ．Ｈｕｎｔｅｒ提出用指数加权滑动平均（ＥＷＭＡ）作为质量管理工具．然而，众所周知存在趋势项的情况下，用ＥＷＭＡ预测往往不是过低就是过高．本文的目的是表明... 详细信息

休哈特控制图和ＳＵＳＵＭ控制图技术，在制造业得到广泛应用．Ｊ．Ｓ．Ｈｕｎｔｅｒ提出用指数加权滑动平均（ＥＷＭＡ）作为质量管理工具．然而，众所周知存在趋势项的情况下，用ＥＷＭＡ预测往往不是过低就是过高．本文的目的是表明利用双指数平滑（ＤＥＳ）技术可以减少此缺点．文中给出一个例子，它表明双指数平滑法比单指数平滑法，能更好地监控对于目标的偏离．

关键词： Exponential moving average double exponential smoothing Shewhart control limits.

A robust online path planning approach in cluttered environments for micro rotorcraft drones

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Control Theory and Technology 2016年第1期14卷 83-96页

作者： Shupeng lai Kangli WANG Hailong qIN Jin q. CUI Ben M. CHEN NUS Graduate School for Integrative Sciences & Engineering National University of Singapore Singapore 117456 Department of Electrical & Computer Engineering National University of Singapore Singapore 117583 Temasek Laboratories National University of Singapore Singapore 117411

We present in this paper a robust online path planning method, which allows a micro rotorcraff drone to fly safely in GPS-denied and obstacle-strewn environments with limited onboard computational power. The approach is based on an effi- ciently managed grid map and a closed-form solution to the two point boundary value problem （TPBVP）. The grid map assists trajectory evaluation whereas the solution to the TPBVP generates smooth trajectories. Finally, a top-level trajectory switching algorithm is utilized to minimize the computational cost. Advantages of the proposed approach include its conservation of com- putational resource, robustness of trajectory generation and agility of reaction to unknown environment. The result has been realized on actual drones platforms and successfully demonstrated in real flight tests. The video of flight tests can be found at： http：//***/***.

关键词： Unmanned aerial vehicles mapping path planning trajectory generation

EFFECT OF STRUCTURAL PARAMETERS ON THE THERMAL STRESS OF A NiFe_(2)O_(4)-BASED CERMET INERT ANODE IN ALUMINUM ELECTROLYSIS

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Acta Metallurgica Sinica(English Letters) 2007年第2期20卷 139-147页

作者： J. Li Z.G. Wang Y.q. lai Y.Y. Wu S.L. Ye School of Metallurgy Science and Engineering Central South University Changsha 410083 China

Inert anode has been a hot issue in the aluminum industry for many decades. With the help of FEA （finite element analysis） software ANSYS, a model was developed to simulate the thermal stress distribution working condition of an inert anode. To reduce its thermal stress, the effect of some parameters on the thermal stress distribution was investigated, including the anode height, the anode radius, the hole depth, the hole radius, and the radius of inner chamfer and outer chamfer. The results showed that in the actual working condition of an inert anode, there existed a large axial tensile stress near the tangent interface between the anode and bath, which was the major cause of anode breaking. Increasing the anode height and reducing the hole depth properly seemed to be beneficial for the stress distribution. With the increase of anode radius, the stress distribution became better first and then deteriorated, the reasonable value was between 0.045 to 0.06m. The hole radius had a significant effect on the stress and a smaller radius would reduce the thermal stress. The effect of the radius of the inner chamfer and the outer chamfer was less than other parameters.

关键词： inert anode thermal stress structural parameter aluminum electrolysis

Coupled effects of climate change and human activities on vegetation dynamics in the Southwestern Alpine Canyon Region of China

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Journal of Mountain Science 2024年第10期21卷 3234-3248页

作者： lai Jinlin qI Shi School of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083China

The driving effects of climate change and human activities on vegetation change have always been a focal point of ***,the coupling mechanisms of these driving factors across different temporal and spatial scales remain *** Southwestern Alpine Canyon Region of China(SACR),as an ecologically fragile area,is highly sensitive to the impacts of climate change and human *** study constructed a vegetation cover dataset for the SACR based on the Enhanced Vegetation Index(EVI)from 2000 to *** autocorrelation,Theil-Sen trend,and Mann-Kendall tests were used to analyze the spatiotemporal characteristics of vegetation cover *** main drivers of spatial heterogeneity in vegetation cover were identified using the optimal parameter geographic detector,and an improved residual analysis model was employed to quantify the relative contributions of climate change and human activities to interannual vegetation cover *** main findings are as follows:Spatially,vegetation cover exceeds 60%in most areas,especially in the southern part of the study ***,the border area between Linzhi and Changdu exhibits lower vegetation *** factors are the primary drivers of spatial heterogeneity in vegetation cover,with temperature having the most significant influence,as indicated by its q-value,which far exceeds that of other ***,the interaction q-value between the two factors significantly increases,showing a relationship of bivariate enhancement and nonlinear *** terms of temporal changes,vegetation cover shows an overall improving trend from 2000 to 2020,with significant increases observed in 68.93%of the study *** these,human activities are the main factors driving vegetation cover change,with a relative contribution rate of 41.31%,while climate change and residual factors contribute 35.66%and 23.53%,*** thoroughly exploring the coupled mechanisms of vegetation change,this

关键词： Enhanced vegetation index Climate change Human activities Spatial heterogeneity Coupled mechanisms

Relationship between Atmospheric Heat Source over the Tibetan Plateau and Precipitation in the Sichuan–Chongqing Region during Summer

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Journal of Meteorological Research 2017年第3期31卷 555-566页

作者： xin lai Yuanfa GONG College of Atmospheric Sciences Chengdu University of Information Technology (CUIT)/Plateau Atmosphere and Environment Key Laboratory of Sichuan Provinceand Joint Laboratory of Climate and Environment Change of CUIT

NCEP-NCAR reanalysis data and a 47-yr daily precipitation dataset from a network of 42 rain gauges are used to analyze the atmospheric heat source （〈q1〉） anomaly over the Tibetan Plateau （TP） and its influence on the summer precipitation anomaly in the Sichuan-Chongqing region. Results show that the vertical advection of 〈ql〉 over the central TP is a major factor affecting summer precipitation in the Sichuan-Chongqing region. When the vertical ad- vection of〈q1〉 over the central TP is strengthened, the South Asian high shifts further than normal to the south and east, the western Pacific subtropical high shifts further than normal to the south and west, and the Indian low weak- ens. This benefits the transport of warm moist air from the low latitude oceans to the Sichuan-Chongqing region. Correspondingly, in the high latitudes, two ridges and one trough form, which lead to cool air moving southward. These two air masses converge over the Sicbuan -chongqing region, leading to significant precipitation. In contrast, when the vertical advection of 〈q1〉 over the central TP is weakened, the South Asian high moves to the north and west, the subtropical high moves eastward and northward, and the Indian low strengthens. This circulation pattern is unfavorable for warm air advection from the south to the Sichuan-Chongqing region, and the cool air further north cannot move southward because of the presence of two troughs and one ridge at high latitude. Thus, ascent over the Sichuan-Chongqing region is weakened, resulting in less precipitation.

关键词： Tibetan Plateau atmospheric heating source/sink Sichuan-Chongqing region precipitation variability