WOLFRAM SYSTEM MODELER
Scenario_22nd Scenario |
 |
Diagram
Wolfram Language
In[1]:=
SystemModel["SystemDynamics.WorldDynamics.World2.Scenario_2"]
Out[1]:=
Information
This is the first modification proposed by Jay Forrester in his WORLD2 model. The utilization of natural resources is reduced in 1970 to 25% of their former value in order to extend their availability.
References:
- Cellier, F.E. (1991), Continuous System Modeling, Springer-Verlag, New York, ISBN: 0-387-97502-0, 755p.
- Forrester, J.W. (1971), World Dynamics, Pegasus Communications, 160p.
Simulate the model across 200 years, and plot the state variables as well as the quality of life as functions of the calendar years:
I had to artificially extend some of the tabular functions, because our software complains when an interpolation function attempts an extrapolation.
Parameters (20)
| Population_0 |
Value: 1650000000.0 Type: Real Description: World population in 1900 |
|---|---|
| Pollution_0 |
Value: 200000000.0 Type: Real Description: Pollution in 1900 |
| Nat_Resources_0 |
Value: 900000000000.0 Type: Real (ton) Description: Unrecoverable natural resources in 1900 |
| Cap_Invest_0 |
Value: 400000000.0 Type: Real (dollar) Description: Capital investment in 1900 |
| CIAF_0 |
Value: 0.2 Type: Real Description: Proportion of capital investment in agriculture in 1900 |
| BRN |
Value: 0.04 Type: Real (1/yr) Description: Normal birth rate |
| CIAFN |
Value: 0.3 Type: Real (dollar) Description: CIAF normalization |
| CIAFT |
Value: 15.0 Type: Real (yr) Description: CIAF time constant |
| CIDN |
Value: 0.025 Type: Real (dollar/yr) Description: Normal capital discard |
| CIGN |
Value: 0.05 Type: Real (dollar/yr) Description: Normal capital generation |
| DRN |
Value: 0.028 Type: Real (1/yr) Description: Normal death rate |
| ECIRN |
Value: 1.0 Type: Real (dollar) Description: Capital normalization |
| FC |
Value: 1.0 Type: Real (kg/yr) Description: Food coefficient |
| FN |
Value: 1.0 Type: Real (kg/yr) Description: Food normalization |
| Land_Area |
Value: 135000000.0 Type: Real (hectare) Description: Area of arable land |
| NRI |
Value: 900000000000.0 Type: Real (ton) Description: Initial natural resources |
| POLN |
Value: 1.0 Type: Real (1/yr) Description: Normal pollution |
| POLS |
Value: 3599900000.0 Type: Real Description: Standard pollution |
| Pop_dens_norm |
Value: 26.5 Type: Real (1/hectare) Description: Normal population density |
| QLS |
Value: 1.0 Type: Real Description: Standard quality of life |
Outputs (6)
| Pop |
Type: Real Description: World population |
|---|---|
| Pol |
Type: Real Description: Pollution |
| Pol_rat |
Type: Real Description: Pollution ratio |
| Cap_inv |
Type: Real (dollar) Description: Capital investment |
| Qual_life |
Type: Real Description: Quality of life |
| Nat_res |
Type: Real (ton) Description: Natural unrecoverable resources |
Components (78)
 |
Source1 |
Type: Source Description: This is the (dummy) source model of System Dynamics |
|---|---|---|
 |
Birth_Rate |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
 |
Population |
Type: Level Description: General System Dynamics level |
|
Death_Rate |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
 |
Sink1 |
Type: Sink Description: This is the (dummy) sink model of System Dynamics |
|
Source2 |
Type: Source Description: This is the (dummy) source model of System Dynamics |
|
Generation |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
Natural_Resources |
Type: Level Description: General System Dynamics level |
|
Depletion |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
Sink2 |
Type: Sink Description: This is the (dummy) sink model of System Dynamics |
 |
Gen_Const |
Type: Const Description: A constant factor |
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BRMM |
Type: Tabular Description: Tabular function |
|
DRMM |
Type: Tabular Description: Tabular function |
 |
BR_norm |
Type: Gain Description: Gain factor |
 |
Prod_5_1 |
Type: Prod_5 Description: Product of five influencing factors |
|
DR_norm |
Type: Gain Description: Gain factor |
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Prod_5_2 |
Type: Prod_5 Description: Product of five influencing factors |
|
BRFM |
Type: Tabular Description: Tabular function |
|
BRPM |
Type: Tabular Description: Tabular function |
|
BRCM |
Type: Tabular Description: Tabular function |
|
DRCM |
Type: Tabular Description: Tabular function |
|
DRPM |
Type: Tabular Description: Tabular function |
|
DRFM |
Type: Tabular Description: Tabular function |
|
Crowd_Rat |
Type: Gain Description: Gain factor |
 |
Prod_2_1 |
Type: Prod_2 Description: Product of two influencing factors |
|
NRMM |
Type: Tabular Description: Tabular function |
|
Source3 |
Type: Source Description: This is the (dummy) source model of System Dynamics |
|
CI_Generation |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
Capital_Investment |
Type: Level Description: General System Dynamics level |
|
CI_Discard |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
Sink3 |
Type: Sink Description: This is the (dummy) sink model of System Dynamics |
|
CIG_norm |
Type: Gain Description: Gain factor |
|
Prod_2_2 |
Type: Prod_2 Description: Product of two influencing factors |
|
CID_norm |
Type: Gain Description: Gain factor |
|
CIM |
Type: Tabular Description: Tabular function |
|
MSL |
Type: Gain Description: Gain factor |
|
NRFR |
Type: Gain Description: Gain factor |
|
ECIR |
Type: Gain Description: Gain factor |
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Prod_3_1 |
Type: Prod_3 Description: Product of three influencing factors |
|
NREM |
Type: Tabular Description: Tabular function |
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CIR |
Type: Division Description: Output first input divided by second input |
|
Source4 |
Type: Source Description: This is the (dummy) source model of System Dynamics |
|
P_Generation |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
Pollution |
Type: Level Description: General System Dynamics level |
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P_Absorption |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
Sink4 |
Type: Sink Description: This is the (dummy) sink model of System Dynamics |
 |
NotCIAF |
Type: Linear Description: Linear function |
|
Pol_Ratio |
Type: Gain Description: Gain factor |
|
FCM |
Type: Tabular Description: Tabular function |
|
Prod_3_2 |
Type: Prod_3 Description: Product of three influencing factors |
|
Food_Ratio |
Type: Gain Description: Gain factor |
|
Source5 |
Type: Source Description: This is the (dummy) source model of System Dynamics |
|
CIAFG |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
CIAF |
Type: Level Description: General System Dynamics level |
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CIAFD |
Type: Rate_1 Description: Unrestricted rate element with one influencing variable |
|
Sink5 |
Type: Sink Description: This is the (dummy) sink model of System Dynamics |
|
CIAF_D |
Type: Gain Description: Gain factor |
|
CIAF_G |
Type: Gain Description: Gain factor |
|
Prod_2_3 |
Type: Prod_2 Description: Product of two influencing factors |
|
P_Abs |
Type: Division Description: Output first input divided by second input |
|
Pol_norm |
Type: Gain Description: Gain factor |
|
Prod_2_4 |
Type: Prod_2 Description: Product of two influencing factors |
|
POLCM |
Type: Tabular Description: Tabular function |
|
POLAT |
Type: Tabular Description: Tabular function |
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CFIFR |
Type: Tabular Description: Tabular function |
|
FPM |
Type: Tabular Description: Tabular function |
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Prod_2_5 |
Type: Prod_2 Description: Product of two influencing factors |
|
CIRA |
Type: Gain Description: Gain factor |
|
FPCI |
Type: Tabular Description: Tabular function |
|
CIQR |
Type: Tabular Description: Tabular function |
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QLMF |
Type: Division Description: Output first input divided by second input |
|
QLM |
Type: Tabular Description: Tabular function |
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QLF |
Type: Tabular Description: Tabular function |
 |
Prod_4_1 |
Type: Prod_4 Description: Product of four influencing factors |
|
QLC |
Type: Tabular Description: Tabular function |
|
QLP |
Type: Tabular Description: Tabular function |
|
Quality_of_Life |
Type: Gain Description: Gain factor |
 |
NR_norm |
Type: Parameter_Change Description: Parameter variation of WORLD2 model |