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Ultra-large aluminum shape casting:Opportunities and challenges

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China Foundry 2024年第5期21卷 397-408页

作者： Qi-gui wang Andy wang Jason Coryell Advanced Materials Technology&Virtualization GM Global Technical CenterWarrenMI USA

Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost *** most of them are structural components subject to both quasi-static,dynamic and cyclic loading,the quality and quantifiable performance of the ultra-large aluminum shape castings is critical to their success in both design and *** paper briefly reviews some application examples of ultra-large aluminum castings in automotive industry and outlines their advantages and *** affecting quality,microstructure and mechanical properties of ultra-large aluminum castings are evaluated and discussed as aluminum shape casting processing is very complex and often involves many competing mechanisms,multi-physics phenomena,and potentially large uncertainties that significantly influence the casting quality and *** analysis and mechanical property assessment of an ultra-large aluminum shape casting are *** are highlighted and suggestions are made for robust design and manufacturing of ultra-large aluminum castings.

关键词： ultra-large castings aluminum light-weighting quality microstructure materials properties

A Remark on General Solution for Motion of Relativistic Strings in Minkowski Space ■^(1+n)

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Communications in Theoretical Physics 2009年第11期52卷 914-918页

作者： wang Zeng-gui Department of Mathematics Shanghai Jiao Tong University Shanghai 200240 China Department of Mathematics Liaocheng University Liaocheng 252059 China

This note concerns the motion of relativistic strings in the Minkowski space R^(1+n).We rederive the generalsolution formula in closed form for the equation for the motion of relativistic *** method is different compl... 详细信息

关键词： space-time the equations for the motion of relativistic string general solution formula

基于无人机多光谱数据和氮素空间分异的玉米冠层氮浓度估算

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作物学报 2025年第1期51卷 189-206页

作者：郝琪陈天陆王富贵王振白岚方王永强王志刚内蒙古农业大学农学院内蒙古呼和浩特010010

作物冠层氮素营养的遥感诊断对指导作物精准施氮,提高作物氮效率和产量具有重要意义。本研究针对玉米冠层纵深大影响无人机估算氮浓度精度的问题,基于2022年和2023年不同氮肥运筹处理下田间无人机多光谱数据和氮浓度实测数据,分析玉米... 详细信息

作物冠层氮素营养的遥感诊断对指导作物精准施氮,提高作物氮效率和产量具有重要意义。本研究针对玉米冠层纵深大影响无人机估算氮浓度精度的问题,基于2022年和2023年不同氮肥运筹处理下田间无人机多光谱数据和氮浓度实测数据,分析玉米冠层氮浓度空间分布特征,并利用随机森林算法确定估算冠层氮浓度的有效叶层。进一步结合随机森林算法和多光谱植被指数构建有效叶层氮浓度估算模型,最终将有效叶层氮浓度转换到冠层尺度实现冠层氮浓度的估算。结果表明:(1)九叶展期和大喇叭口期玉米冠层氮浓度表现为上层叶片>中层叶片>下层叶片,吐丝期和乳熟期表现为中层叶片>上层叶片>下层叶片。(2)各时期估算冠层氮浓度的有效叶层分别为下层、中层、中层和中层。与支持向量回归模型相比,随机森林回归估算冠层氮浓度的精度较高。(3)结合随机森林算法,基于有效叶层氮浓度估算冠层氮浓度的平均RMSE、NRMSE和MAE分别为0.10%、4.41%和0.07%,而直接基于植被指数估算冠层氮浓度的平均RMSE、NRMSE和MAE分别为0.19%、9.00%和0.15%。综上,玉米冠层氮浓度存在空间分异特征,估算冠层氮浓度时考虑基于随机森林和植被指数估算的有效叶层氮浓度能明显提高冠层氮浓度的估算精度。本研究确定的考虑空间分异的冠层氮浓度估算框架可为玉米氮素营养实时诊断提供理论支撑。

关键词：玉米冠层氮浓度氮素空间分异多光谱数据机器学习

Microstructure and mechanical properties of lost foam cast 356 alloys

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China Foundry 2015年第3期12卷 214-221页

作者： Qi-gui wang Materials Technology Global Powertrain Engineering General Motors Company

Microstructure and mechanical properties of lost foam cast aluminum alloys have been investigated in both primary A356(0.13% Fe) and secondary 356(0.47%). As expected, secondary 356 shows much higher content of Fe-rich intermetallic phases, and in particular the porosity in comparison with primary A356. The average area percent and size(length) of Fe-rich intermetallics change from about 0.5% and 6 μm in A356 to 2% and 25 μm in 356 alloy. The average area percent and maximum size of porosity also increase from about 0.4% and 420 μm to 1.4% and 600 μm, respectively. As a result, tensile ductility decreases about 60% and ultimate tensile strength declines about 8%. Lower fatigue strength was also experienced in the secondary 356 alloy. Low cycle fatigue(LCF) strength decreased from 187 MPa in A356 to 159 MPa in 356 and high cycle fatigue(HCF) strength also declined slightly from 68 MPa to 64 MPa.

关键词： lost foam casting aluminum alloys microstructure mechanical properties fatigue Weibull linear elastic fracture mechanics 356 alloy

A Chiral Helical Compound Based on Achiral Components

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Chinese Journal of Structural Chemistry 2007年第5期26卷 551-554页

作者： ZHANG Qi-Wei wang gui-Xian Department of Chemistry Lishui University Lishui Zhejiang 323000 China

The title compound, [Cu（dpa）（2,2＇-bipy）（H2O）2]n 1 （H2dpa = diphenic acid and 2,2＇- bipy = 2,2＇-bipyridine）, has been synthesized and its structure was determined by single-crystal X-ray diffraction. The crystal is of orthorhombic, space group P212121 with a = 10.597（4）, b = 11.317（4）, c = 17.630（7）A, V = 2114.3（14）A^3, C24H20CuN2O6, Mr = 495.97, Z = 4, Dc = 1.558 g/cm^3, μ = 1.079 mm^-1, F（000） = 1020, Flack value = 0.052（18）, R = 0.0430 and wR = 0.1016 for 3381 observed reflections （Ⅰ 〉 2σ（Ⅰ））. In compound 1, the dpa ligands link metal ions into helical structures in the same direction.

关键词： crystal structure chiral hydrogen bond diphenic acid helix

Chemical diversity and biological function of indolediketopiperazines from marine-derived fungi

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Marine Life Science & Technology 2020年第1期2卷 31-40页

作者： Jin Cao Bin-gui wang Key Laboratory of Experimental Marine Biology Institute of OceanologyChinese Academy of Sciences and Laboratory of Marine Biology and BiotechnologyQingdao National Laboratory for Marine Science and TechnologyQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China

Natural products from marine-derived fungi have attracted considerable attention in the recent two *** are one of the most important classes of marine natural products,mainly discovered from the fungal genera Penicillium,Aspergillus and *** compounds span a wide range of chemical structures and *** review summarizes 155 indolediketopiperazines that were discovered from marine-derived fungi from 2000 to early 2019 and primarily focuses on their chemical diversity and biological function.

关键词： Indolediketopiperazines Marine-derived fungi Natural products Chemical diversity Biological function

On Two-stage Estimate Based on Independent Estimate of Covariance Matrix

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Acta Mathematica Sinica,English Series 2006年第1期22卷 283-288页

作者： Su Ju YIN Song gui wang College of Applied Sciences Beijing University of Technology Beijing 100022 P. R. China

When an independent estimate of covariance matrix is available, we often prefer two-stage estimate （TSE）. Expressions of exact covarianee matrix of the TSE obtained by using all and some covariables in eovariance adjustment approach are given, and a necessary and sufficient condition for the TSE to be superior to the least square estimate and related large sample test is also established. Furthermore the TSE, by using some covariables, is expressed as weighted least square estimate. Basing on this fact, a necessary and sufficient condition for the TSE by using some covariables to be superior to the TSE by using all eovariables is obtained. These results give us some insight into the selection of covariables in the TSE and its application.

关键词： two-stage estimate covariance adjusted estimate canonical correlation coefficients

The Minimax Estimator of Stochastic Regression Coefficients and Parameters in the Class of All Estimators

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Acta Mathematica Sinica,English Series 2007年第3期23卷 497-506页

作者： Li Wen XU Song gui wang Department of Mathematics Tsinghua University Beijing 100084 P. R. China College of Applied Sciences Beijing University of Technology Beijing 100022 P. R. China College of Applied Sciences Beijing University of Technology Beijing 100022. P. R. China

In this paper, the authors address the problem of the minimax estimator of linear combinations of stochastic regression coefficients and parameters in the general normal linear model with random effects. Under a quadratic loss function, the minimax property of linear estimators is investigated. In the class of all estimators, the minimax estimator of estimable functions, which is unique with probability 1, is obtained under a multivariate normal distribution.

关键词： minimax estimator stochastic regression coefficients quadratic loss function normal linear model

Prediction of Cuttings-Induced Annular-Pressure Loss in Extended-Reach Wells

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Fluid Dynamics & Materials Processing 2023年第11期19卷 2877-2890页

作者： Long wang Qingyun Shen gui wang Key Laboratory of Enhanced Oil Recovery in Fracture-Vug Reservoir SINOPECUrumuqi830011China State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China

Drill cuttings are broken bits of solid material removed from a borehole drilled by rotary,percussion,or auger methods and brought to the surface in the drilling *** these cuttings enter the annulus,they have an effect on the drillingfluid rheology and density,which is,in general,quite difficult to *** introducing an empirical correlation for the rheological properties of cuttings-laden drillingfluids,this study proposes a pres-sure-loss prediction method for an extended-reach well(ERW).After verifying the accuracy of this method,a case study is considered and a sensitivity analysis is conducted assuming a yield-power *** results show that an increased concentration of cuttings in the annulus contributes to an increased annular pressure ***-pared to their effect on the drillingfluid density,cuttings have a greater impact on the drillingfluid rheology.A larger rate of penetration contributes to an increased annular pressure *** higher drillingfluidflow rates,the annular pressure lossfirst decreases and then it *** addition,the annular pressure loss becomes high-er as the cuttings’particle size decreases and the cuttings’concentration grows.

关键词： Pressure loss cuttings extended-reach well yield-power law model drillingfluid