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61.
Simulation of water and nitrogen dynamics in soils during wastewater applications by using a finite-element model 总被引:4,自引:0,他引:4
Vassilis Z. Antonopoulos 《Water Resources Management》1993,7(3):237-251
A mathematical model was developed to simulate water movement, mass transport, and nitrogen transformations in soils during wastewater applications. The model is one-dimensional and based on the Galerkin finite-element method. The submodel of mass transport of nitrogen incorporates the convection-dispersion processes of ammonium and nitrate nitrogen, nitrification, denitrification, ammonium exchange and uptake of ammonium and nitrate ions. The accuracy and validity of the proposed model was examined by comparison with an explicit-implicit finite-difference model results. The model was used for simulation of water and nitrogen dynamics during wastewater application in homogeneous and multi-layered soils under different N concentration, rate, duration and scheduling of application. 相似文献
62.
Aerodynamic loads on a multi-bladed helicopter rotor in hovering flight were calculated by solving the three-dimensional incompressible Navier-Stokes equations. The rotor wake effects were accounted by the correction of local geometric angle of attack according to a free-wake modeling in addition to an empirical modification for the tip flow effect. The validity and efficiency of the present method were verified by the comparisons between numerical results and experimental data. 相似文献
63.
64.
Guojie Zhao" Tianjin Zhiyong Shi Guojie Zhao 《美中经济评论(英文版)》2006,5(2):9-12
The selective principle of mutually exclusive project is the maximum of net present value, It is difficult to make decision when NPVA is equal to NPVLB. Some assistant analyses are put forward in "Enterprise Investment Decision Management". The scientific marginal analysis shows that the assistant analyses including the duration analysis are wrong. This problem can be solved by the classical marginal analysis. 相似文献
65.
Abstract: We explore to what extent firms deliberately manage their financial reports by exploiting the flexibility of generally accepted accounting principles. Using a sample of Oslo Stock Exchange-listed firms with 20–50% equity holdings in other firms, we find that firms with high financial leverage tend to maximize reported earnings from these investments through their choice between the cost method and the equity method, possibly in an attempt to reduce debt renegotiation costs or to avoid regulatory attention. In contrast, managers do not systematically bias reported earnings to extract private benefits or to signal revised expectations about future cash flows. Firms use different earnings management tools in a consistent way, as the earnings effect of the cost/equity choice is not offset by discretionary accruals. 相似文献
66.
Guojie Zhao Dali Xu Shumei Ren 《美中经济评论(英文版)》2006,5(2):79-81
The book of Modem Consulting Method and Practice is the appointed teaching material for registered consulting engineer qualification examination (investment) of China. Its Lowest Price method in evaluating mutually exclusive project has some problems, which contradict the delta IRR and NPV methods. We improve the method and recommend Good-Bad Boundary Price Method to solve problem of this type. 相似文献
67.
浅析石油化工项目产品市场分析 总被引:2,自引:0,他引:2
谭国林 《石油化工技术经济》2002,18(5):39-43,60
市场分析是项目前期的重要工作之一,目前尚未赢得人们足够的重视。国外的投资咨询公司对石油化工项目的产品市场分析有其一套比较完整的操作程序和评估体系,以BOPP为案例介绍了市场分析的思路和方法,并且指出市场分析作为一种新的理念,必须进一步深化和细化,逐步加以完善。 相似文献
68.
以油藏监测工作中的油藏压力监测为例,介绍了标准化工作在压力资料录取及解释分析中的作用。并用实例说明了标准化作业在油田开发方案的制定及油藏压力监测中的应用。 相似文献
69.
应用突变多准则评价法对南水北调中线水源工程项目的多方案比选作出评价决策。该方法为专家决策系统提供一种数学方法 ,以便用计算机实现多目标、多层次、多方案的评价决策。 相似文献
70.