WOLFRAM SYSTEM MODELER

Scenario_2

2nd 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:

  1. Cellier, F.E. (1991), Continuous System Modeling, Springer-Verlag, New York, ISBN: 0-387-97502-0, 755p.
  2. 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

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

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

Prod_3_1

Type: Prod_3

Description: Product of three influencing factors

NREM

Type: Tabular

Description: Tabular function

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

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

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

CFIFR

Type: Tabular

Description: Tabular function

FPM

Type: Tabular

Description: Tabular function

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

QLMF

Type: Division

Description: Output first input divided by second input

QLM

Type: Tabular

Description: Tabular function

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