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IntroductionItiswell-knownthatland-atmosphereinteractionexertsgreatinfluencesonglobalandregionalenvironment(Woodfool,Yih1994).Inordertodeterminethefluxesandtheparameterizationschemeattheland-atmosphereinterface,itisnecessaryforustoinvestigateterrestrialprocessesontypicalunderlyingsurface.Aridarea(includingextremelyarid,aridandsend-aridareas)ofsabillionklnZ,occupiesalmostonethirdofthelandsurface,mainlyinNorthAfrica,CentralAsia,AustraliaandNorthAInerica.Amongthemdesertcoversnearly6millionkl… 相似文献
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植物固沙区土壤水热运移耦合模型研究 总被引:1,自引:0,他引:1
根据Philip与Vries提出的土壤中水热交换的耦合理论,建立了植物固沙区土壤水热运移的耦合模型,考虑了液态水和汽态水运移对温度的变化,分析了植物根系吸水对土壤水热交换的影响,给出了植物蒸腾量、土壤蒸发量、根系汲水率及土壤表面热通量等有关变量的计算公式.利用本模式并采用具有二阶精度的Crank-Nicolson格式对非线性扩散方程进行离散,对沙坡头植物固沙区土壤水热交换过程进行了数值模拟,模拟结果和实测值进行了比较,总体上符合较好,证明本模型具有实用价值,可为改造沙漠提供科学依据 相似文献
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In accordance with the recent experimental research for flow visualization,theunsteady behavior of the starting period is investigated numerically for flow past bluntbodies.Finite difference methods are employed to solve the unsteady two-dimensionalincompressible Navier-Stokes equations.A short discussion is presented of explicit,implicit and ADI methods.Finally,the explicit and ADI schemes are used to study the flowfield in the starting period for flow past mountain-shaped and rectangular bodies. 相似文献
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本文按照气体动力学理论,对圆盘形和圆环形压膜轴承的气动力作了详细的分析;给出了这两种轴承的压力分布的解析表达式,并用该方法修正了圆盘形压膜轴承的部分计算公式;还给出了这两种轴承的压力分布和承载能力的计算结果,可供设计者参考. 相似文献
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A production representation of partial-wave S matrix is utilized to construct low-energy elastic pion-nucleon scattering amplitudes from cuts and poles on complex Riemann sheets. Among them, the contribution of left-hand cuts is estimated using the ■(p~3) results obtained in covariant baryon chiral perturbation theory within the extendedon-nass-shell scheme. By fitting to data on partial-wave phase shifts, it is indicated that the existences of hidden poles in S11 and P11 channels, as conjectured in our previous paper [Eur. Phys. J. C, 78(7): 543(2018)], are firmly established. Specifically, the pole mass of the S11 hidden resonance is determined to be(895±81)-(164±23)i MeV,whereas,the virtual pole in the P11 channel locates at(966±18) MeV. It is found that analyses at the■ (p~3) level improves significantly the fit quality, comparing with the previous■ (p~2) one. Quantitative studies with cautious physical discussions are also conducted for the other S-and P-wave channels. 相似文献