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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Streeter–Phelps equation ： ウィキペディア英語版 Streeter–Phelps equation The Streeter–Phelps equation is used in the study of water pollution as a water quality modelling tool. The model describes how dissolved oxygen (DO) decreases in a river or stream along a certain distance by degradation of biochemical oxygen demand (BOD). The equation was derived by H. W. Streeter, a sanitary engineer, and Earle B. Phelps, a consultant for the U.S. Public Health Service, in 1925, based on field data from the Ohio River. The equation is also known as the DO sag equation. == Streeter-Phelps equation == The Streeter–Phelps equation determines the relation between the dissolved oxygen concentration and the biological oxygen demand over time and is a solution to the linear first order differential equation〔Streeter H. W., Phelps E. B., 1925, A Study of the pollution and natural purification of the Ohio river. III. Factors concerned in the phenomena of oxidation and reaeration, Public Health Bulletin no. 146, Reprinted by U.S. Department of Health, Education and Welfare, Public Health Service, 1958, ISBN B001BP4GZI, http://dspace.udel.edu:8080/dspace/bitstream/handle/19716/1590/C%26EE148.pdf?sequence=2〕 :$\backslash frac\; =\; k\_1\; L\_t\; -k\_2\; D$ This differential equation states that the total change in oxygen deficit (D) is equal to the difference between the two rates of deoxygenation and reaeration at any time. The Streeter–Phelps equation, assuming a plug-flow stream at steady state is then :$D\; =\backslash frac\; (e^-e^)\; +\; D\_a\; e^$ where *$D$ is the saturation deficit, which can be derived from the dissolved oxygen concentration at saturation minus the actual dissolved oxygen concentration ($D\; =\; DO\_\; -\; DO$). $D$ has the dimensions $\backslash tfrac$. *$k\_1$ is the deoxygenation rate, usually in $d^$. *$k\_2$ is the reaeration rate, usually in $d^$. *$L\_a$ is the initial oxygen demand of organic matter in the water, also called the ultimate BOD (BOD at time t=infinity). The unit of $L\_a$ is $\backslash tfrac$. *$L\_t$ is the oxygen demand remaining at time t, $L\_t=L\_a\; e^$. *$D\_a$ is the initial oxygen deficit . $k\_1$ lies typically within the range 0.05-0.5 $d^$ and $k\_2$ lies typically within the range 0.4-1.5 $d^$.〔Schnoor J., 1996, Environmental Modeling, Fate and Transport of Pollutants in Water, Air and Soil, Wiley-Interscience, ISBN 978-0-471-12436-8〕 The Streeter–Phelps equation is also known as the DO sag equation. This is due to the shape of the graph of the DO over time. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Streeter–Phelps equation」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.