rabbit crowding i ni ti al rabb i t
p op ul ati on fo x foo d requ irement s fo x rab bi t co nsu mpt io n carry in g cap aci ty l oo ku p
fox food availability
1 2
3
1 2 1 2
4
5 6 Time (Month)
1 2 1 2 1 2 1 2
7
1 2 1 2
8
1 2
9
1 2 1
10
红方人数 : Current 蓝方人数 : Current
6.没有狐狸的情况下，兔子数量R年增长10%；没有兔 子情况下，狐狸数量F年减少15%。当他们处于同一 栖息地，狐狸吃兔子，兔子数减少，狐狸数增加。 模型：R‘=1.1R-0.15F，F’=0.85F+0.1R。建立SD模 型，并模拟生态系统平衡的条件。(3:2)
软件消费者行为分析
转变周期 道德水平
盗版打击力度
盗版成本
脱离系数
潜在软件 用户增加
潜在软件 用户
盗版用户 盗版用户增加 盗版外部性
网络外部性系数
(05) (06) 少 (07)
(08) (09) (10) (11) (12) (13) (14) (15) (16) (17) (18)
(01) average fox life = 4 Units: Year (02) average rabbit life = 2 Units: Year (03) carrying capacity = 500 Units: Rabbit (04) effect of crowding on deaths lookup ([(0,0)(10,20)],(0,0.75),(1,1),(2,1.25),(5,2),(10,20) ) Units: Dmnl (05) FINAL TIME = 50 Units: Year The final time for the simulation. (06) fox birth rate = 0.25 Units: 1/Year (07) fox births = Fox Population * fox birth rate Units: Fox/Year (08) fox deaths = Fox Population / average fox life * fox mortality lookup (fox food availability) Units: Fox/Year
正版用户= INTEG (正版用户增加, 100) 正版用户增加=(潜在软件用户-盗版用户增加)*0.2+盗版用户减
潜在软件用户= INTEG ( 潜在软件用户增加-正版用户增加-盗版用户增加,1000) 潜在软件用户增加= IF THEN ELSE(网络外部性<=1000, 网络外部性, 1000) 盗版成本= 10000*盗版打击力度 盗版打击力度= 1 盗版用户= INTEG (盗版用户增加-盗版用户减少,100) 盗版用户减少= 脱离系数*盗版用户 盗版用户增加= 潜在软件用户*盗版用户/盗版成本 网络外部性= (正版用户+盗版用户)*网络外部性系数 网络外部性系数= 0.1 脱离系数= 道德水平/转变周期 转变周期= 5 道德水平= 1
蓝方人数 蓝方人数减少
(6) 红方人数减少=蓝方人数*0.2 (7) 蓝方人数= INTEG (-蓝方人数减 少,150) (8) 蓝方人数减少=红方人数*0.1
Selected Variables
200 200
1 1 2
100 100
2
1 2 1 2 1 2 1 2
2 1
2 1
2 1
2 1
0 0 0 1 2
(09) fox food availability = fox rabbit consumption/(Fox Population * fox food requirements) Units: Dmnl A lookup table showing the relationship between the input (crowding) along the x axis and the output (the effect that crowding has on the death rate) along the y-axis. (10) fox food requirements = 25 Units: Rabbit/Year/Fox (11) fox mortality lookup ([(0,0)-(2,20)],(0,20),(0.5,2),(1,1),(2,0.5) ) Units: Dmnl (12) Fox Population = INTEG (fox births-fox deaths, initial fox population) Units: Fox (13) fox rabbit consumption = Fox Population * fox food requirements * fox rabbit consumption lookup (rabbit crowding) Units: Rabbit/Year (14) fox rabbit consumption lookup ([(0,0)-(6,6)],(0,0),(1,1),(2,2),(6,2) ) Units: Dmnl Relating rabbits to foxes (15) initial fox population = 40 Units: Fox (16) initial rabbit population = 500 Units: Rabbit
fox deaths
rabbit deat hs fox rabbit consumption
Rabbit Populatio n
rabbit births
rabb it bi rt h rat e
i ni ti al fo x p op ul ati on
av erag e fox l ife fo x mortal it y l oo ku p
FINAL TIME = 1000 INITIAL TIME = 0 SAVEPER = TIME STEP TIME STEP = 1 传销者= INTEG (传销者增加-传销者减少,100) 传销者减少=0.002*传销者 传销者增加=1e-005*潜在传销者人数*传销者 潜在传销者人数= INTEG (-传销者增加, 1000) 脱离传销者= INTEG (传销者减少,0)
兔子数量 兔子增长 兔子减少
狐狸数量 狐狸增长 狐狸减少
7.Fox-Rabbit Ecology**
effect of crow di ng on d eath s lo ok u p
av erag e rabb it li fe
fox births
fo x bi rt h rate
Fox Populatio n
4. 对于第四讲-3里的传销模型，用Vensim画出 流图，并用以下参数进行模拟，验证传销网不能 发展的条件。 S(0)＝1000，I(0)＝100，R(0)＝0； =0.002，=0.00001
潜在传销 者人数
传销者增加
传销者
脱离传销者 传销者减少
(01) (02) (03) (04) (05) (06) (07) (08) (09)
5. 用Vensim软件模拟第三讲练习3中的Lanchester战争 模型
(1) FINAL TIME = 10
红方人数 红方人数减少
(2) INITIAL TIME = 0 (3) SAVEPER = TIME STEP
(4) TIME STEP = 1
(5) 红方人数= INTEG (-红方人数减 少,200)