//带初值的一阶微分方程求解
within ModelicaByExample.BasicEquations.SimpleExample;
model FirstOrderInitial "First order equation with initial value"
Real x "State variable";
initial equation //变量x的初始化方程
x = 2 "Used before simulation to compute initial values";
equation
der(x) = 1-x "Drives value of x toward 1.0";
//变量微分方程
annotation(experiment(StartTime=0,StopTime=8));
//定义仿真开始时间和仿真终止时间，单位为秒（s）
end FirstOrderInitial;
//稳态起始的一阶微分方程求解
within ModelicaByExample.BasicEquations.SimpleExample;
model FirstOrderInitial "First order equation with initial value"
Real x "State variable";
initial equation //变量x的初始化方程
der(x) = 0 "Initialize the system in steady state";
//变量的初始切线为水平线
equation
der(x) = 1-x "Drives value of x toward 1.0";
//变量微分方程
annotation(experiment(StartTime=0,StopTime=8));
//定义仿真开始时间和仿真终止时间，单位为秒（s）
end FirstOrderInitial;
//一维牛顿冷却方程
within ModelicaByExample.BasicEquations.CoolingExample;
model NewtonCooling "An example of Newton's law of cooling"
parameter Real T_inf "Ambient temperature";//环境温度
parameter Real T0 "Initial temperature";//初始温度
parameter Real h "Convective cooling coefficient";//热对流系数
parameter Real A "Surface area";//表面面积
parameter Real m "Mass of thermal capacitance";//物体质量
parameter Real c_p "Specific heat";//物体的比热容
Real T "Temperature";//物体温度
initial equation
T = T0 "Specify initial value for T";
//物体温度
equation
m*c_p*der(T) = -h*A*(T - T_inf) "Newton's law of cooling";
end NewtonCooling;
//带类型定义的一维冷却牛顿方程
within ModelicaByExample.BasicEquations.CoolingExample;
model NewtonCoolingWithTypes "Cooling example with physical types"
// Types
type Temperature=Real(unit="K", min=0);//定义新的类型；
type ConvectionCoefficient=Real(unit="W/(m2.K)", min=0);
type Area=Real(unit="m2", min=0);
type Mass=Real(unit="kg", min=0);
type SpecificHeat=Real(unit="J/(K.kg)", min=0);
// Parameters
parameter Temperature T_inf=298.15 "Ambient temperature";
parameter Temperature T0=363.15 "Initial temperature";
parameter ConvectionCoefficient h=0.7 "Convective cooling coefficient";
parameter Area A=1.0 "Surface area";
parameter Mass m=0.1 "Mass of thermal capacitance";
parameter SpecificHeat c_p=1.2 "Specific heat";
// Variables
Temperature T "Temperature";
initial equation
T = T0 "Specify initial value for T";
equation
m*c_p*der(T) = h*A*(T_inf-T) "Newton's law of cooling";
end NewtonCoolingWithTypes;