数学建模实习报告3

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西北农林科技大学试验报告

学院名称：理学院姓名：xxx

1试验题目：池水含盐问题2试验问题陈述：

池中有水2000m3，含盐2kg，以6m3/min的速率向池中注入浓度为0.5kg/m3的盐水，又以4m3/min的速率从池中流出混合后的盐水。假使池中盐水浓度达到0.2kg/m时将注入池中的盐水改变为清水，问何时池中盐水浓度能够被稀释到这个浓度的50%，即达到0.1kg/m3？

3试验目的:

仿真池中盐水浓度的变化，给出达到给定浓度的时间。4试验内容:问题分析：池中有盐水，匀速注入浓盐水，

匀速流出混合后的盐水，池中盐水的浓度变化。变量、参量

时间t，体积V(t),盐量S(t),浓度p(t);流入流速rI=6,流入浓度pI=0.5,流出流速rO=4,

改变时候的盐水浓度p*=0.2，改变的时刻t*，终止时候的盐水浓度p*=0.1，终止的时刻t**。时间步长Δt,打印步长T.

在时间间隔[t,t+Δt]内将有如下的转换关系

3

专业年级：2023级信计1班

学号：xxx

报告日期：2023年11月23日

课程：数学模型与数学建模

考虑到系统运行过程中输入参数的变化，设置指标ind来标志输入条件的转换，令ind=1表示输入池中盐水的浓度为pI（≠0）ind=0表示流入池中的水为清水（pI=0）

在仿真的过程，可以每运行m个时间步长打印输出一次计算的结果。

5试验结果分析与探讨:P=

Columns1through9

0.00100.02980.05640.08110.10400.12520.14490.16330.1804

Columns10through11

0.19640.2023P=

Columns1through9

0.00100.02980.05640.08110.10400.16330.1804

Columns10through12

0.19640.20230.1964P=

Columns1through9

0.00100.02980.05640.08110.10400.16330.1804

Columns10through13

0.19640.20230.19640.1928P=

Columns1through9

0.00100.02980.05640.08110.10400.16330.1804

Columns10through14

0.19640.20230.19640.19280.1835P=

Columns1through9

0.12520.14490.12520.14490.12520.1449

0.00100.02980.05640.08110.10400.12520.14490.16330.1804

Columns10through15

0.19640.20230.19640.19280.18350.1748P=

Columns1through9

0.00100.02980.05640.08110.10400.12520.16330.1804

Columns10through16

0.19640.20230.19640.19280.18350.17480.1666P=

Columns1through9

0.00100.02980.05640.08110.10400.12520.16330.1804

Columns10through17

0.19640.20230.19640.19280.18350.17480.1589P=

Columns1through9

0.00100.02980.05640.08110.10400.12520.16330.1804

Columns10through18

0.19640.20230.19640.19280.18350.17480.15890.1516P=

0.14490.14490.16660.14490.1666

Columns1through9

0.00100.02980.05640.08110.10400.12520.14490.16330.1804

Columns10through18

0.19640.20230.19640.19280.18350.17480.16660.15890.1516

Column19

0.1449P=

Columns1through9

0.00100.02980.16330.1804

Columns10through18

0.19640.20230.15890.1516

Columns19through20

0.14490.1385P=

Columns1through9

0.00100.02980.16330.1804

Columns10through18

0.19640.20230.15890.1516

Columns19through21

0.05640.08110.19640.19280.05640.08110.19640.19280.10400.12520.18350.17480.10400.12520.18350.17480.14490.16660.14490.1666

0.14490.13850.1324P=

Columns1through9

0.00100.02980.05640.08110.10400.12520.14490.16330.1804

Columns10through18

0.19640.20230.19640.19280.18350.15890.1516

Columns19through22

0.14490.13850.13240.1268P=

Columns1through9

0.00100.02980.05640.08110.10400.16330.1804

Columns10through18

0.19640.20230.19640.19280.18350.15890.1516

Columns19through23

0.14490.13850.13240.12680.1214P=

Columns1through9

0.00100.02980.05640.08110.10400.16330.1804

Columns10through18

0.17480.16660.12520.14490.17480.16660.12520.1449

0.19640.20230.19640.19280.18350.17480.16660.15890.1516

Columns19through24

0.14490.13850.13240.12680.12140.1163P=

Columns1through9

0.00100.02980.05640.08110.10400.12520.16330.1804

Columns10through18

0.19640.20230.19640.19280.18350.17480.15890.1516

Columns19through25

0.14490.13850.13240.12680.12140.11630.1116P=

Columns1through9

0.00100.02980.05640.08110.10400.12520.16330.1804

Columns10through18

0.19640.20230.19640.19280.18350.17480.15890.1516

Columns19through26

0.14490.13850.13240.12680.12140.11630.1070P=

Columns1through9

0.14490.16660.14490.16660.1116

0.00100.02980.05640.08110.10400.12520.14490.16330.1804

Columns10through18

0.19640.20230.19640.19280.18350.17480.16660.15890.1516

Columns19through27

0.14490.13850.13240.12680.10700.1027a=

02.00002.00000.100020.00002.040060.81012.980940.00002.0800117.39955.644260.00002.1200171.93468.110180.00002.1600224.566310.3966100.00002.2000275.431912.5196120.00002.2400324.656614.4936140.00002.2800372.354716.3313160.00002.3200418.630718.0444180.00002.3600463.580419.6432185.00002.3700474.621020.0262180.00002.3600463.580419.6432200.00002.4000462.815019.2840220.00002.4400447.746718.3503240.00002.4800433.402517.4759260.00002.5200419.736816.6562280.00002.5600406.707315.8870300.00002.6000394.275315.1644320.00002.6400382.404714.4850340.00002.6800371.062213.8456360.00002.7200360.217013.2433380.00002.7600349.840412.6754400.00002.8000339.905712.1395420.00002.8400330.388411.6334440.00002.8800321.265211.1550460.00002.9200312.514810.7026480.00002.9600304.117110.2742494.00002.9880298.43849.9879

0.12140.11630.1116

盐水浓度变化曲线：

结论：

需要t1=186分将水池中盐水浓度从0.001提高到0.2。又需要t2-t1=312分水将池中盐水浓度从0.2恢复到0.1。

6试验程序（Matlab或者其它软件语言陈述）：t=1;v=[2000];s=[2];p=[1/1000];%初始状态ri=6;ro=4;po=0.5;p1=0.2;p2=0.1;%参数

V=[v(end)];S=[s(end)];P=[p(end)];x=[0];%打印记录whilep(end)p1;%调整输入前动态t=t+1;%时钟步进

v=[v,1];s=[s,1];p=[p,0];%变量步进

v(