{ diff(x1, t) = (1*k28*x37*k22 + (-1)*k39*x3*x1*k22 + 1*k64*x23*k22)/k22,
  diff(x2, t) = ((-1)*(k46*x23*x2 + (-k47*x37))*k22 + (-1)*(k48*x2*x9 + (-k49*x31))*k22 + 1*piecewise((k18 + (-x2))*1/k19, t > k17, 0)*k22)/k22,
  diff(x3, t) = (1*k38*x4*k22 + (-1)*k39*x3*x1*k22)/k22,
  diff(x4, t) = (1*k28*x37*k22 + (-1)*k38*x4*k22 + (-1)*(k57*x4*x19 + (-k58*x25))*k22 + 1*k64*x23*k22)/k22,
  diff(x5, t) = (1*k31*(x31 + x37)*k22 + (-1)*k59*x5*k22)/k22,
  diff(x6, t) = (1*(k36*x7*x24 + (-k37*x6))*k22 + (-1)*k65*x6*k22)/k22,
  diff(x7, t) = ((-1)*(k36*x7*x24 + (-k37*x6))*k22 + (-1)*(piecewise(1000, t > 1000, 0)*x7*x26 + (-piecewise(30000, t > 1000, 0)*x27))*k22 + 1*k65*x6*k22)/k22,
  diff(x8, t) = 0,
  diff(x9, t) = ((-1)*(k25*x16*x9 + (-k26*x17))*k22 + (-1)*(k34*x9*x10 + (-k35*x23))*k22 + (-1)*(k44*x13*(x37 + x9 + x31) + (-k45*x30))*k22 + (-1)*(k48*x2*x9 + (-k49*x31))*k22 + 1*k64*x23*k22)/k22,
  diff(x10, t) = ((-1)*(k29*x10*x31 + (-k30*x37))*k22 + (-1)*(k34*x9*x10 + (-k35*x23))*k22 + 1*k39*x3*x1*k22)/k22,
  diff(x11, t) = (1*(k32*x14*x24 + (-k33*x11))*k22 + (-1)*(k50*x11 + (-k51*x12*x13))*k22)/k22,
  diff(x12, t) = 1*(k50*x11 + (-k51*x12*x13))*k22/k22,
  diff(x13, t) = (1*(k50*x11 + (-k51*x12*x13))*k22 + (-1)*(k52*x13*x20 + (-k53*x21))*k22 + (-1)*(k60*x32*x13 + (-k61*x15))*k22 + 1*k63*x15*k22)/k22,
  diff(x14, t) = ((-1)*(k32*x14*x24 + (-k33*x11))*k22 + 1*(k54*x22*x24 + (-k55*x14))*k22)/k22,
  diff(x15, t) = (1*(k60*x32*x13 + (-k61*x15))*k22 + (-1)*k63*x15*k22)/k22,
  diff(x16, t) = ((-1)*(k25*x16*x9 + (-k26*x17))*k22 + 1*piecewise((k14 + (-x16))*1/k15, t > k13, 0)*k22)/k22,
  diff(x17, t) = 1*(k25*x16*x9 + (-k26*x17))*k22/k22,
  diff(x18, t) = 0/k22,
  diff(x19, t) = ((-1)*(k40*x19*x28 + (-k41*x29))*k22 + (-1)*(k57*x4*x19 + (-k58*x25))*k22)/k22,
  diff(x20, t) = (-1)*(k52*x13*x20 + (-k53*x21))*k22/k22,
  diff(x21, t) = 1*(k52*x13*x20 + (-k53*x21))*k22/k22,
  diff(x22, t) = (-1)*(k54*x22*x24 + (-k55*x14))*k22/k22,
  diff(x23, t) = (1*(k34*x9*x10 + (-k35*x23))*k22 + (-1)*(k46*x23*x2 + (-k47*x37))*k22 + (-1)*k64*x23*k22)/k22,
  diff(x24, t) = (1*k1*x25*k66*1/(k24 + k66)*k22 + 1*k27*(piecewise(1, and(t > k3, t < k4), 0) + piecewise(x18, and(t > k5, t < k6), 0))*x36*k22 + (-1)*(k32*x14*x24 + (-k33*x11))*k22 + (-1)*(k36*x7*x24 + (-k37*x6))*k22 + (-1)*(k54*x22*x24 + (-k55*x14))*k22 + 1*k8*x29*k66*1/(k56 + k66)*k22)/k22,
  diff(x25, t) = 1*(k57*x4*x19 + (-k58*x25))*k22/k22,
  diff(x26, t) = (-1)*(piecewise(1000, t > 1000, 0)*x7*x26 + (-piecewise(30000, t > 1000, 0)*x27))*k22/k22,
  diff(x27, t) = 1*(piecewise(1000, t > 1000, 0)*x7*x26 + (-piecewise(30000, t > 1000, 0)*x27))*k22/k22,
  diff(x28, t) = (-1)*(k40*x19*x28 + (-k41*x29))*k22/k22,
  diff(x29, t) = 1*(k40*x19*x28 + (-k41*x29))*k22/k22,
  diff(x30, t) = 1*(k44*x13*(x37 + x9 + x31) + (-k45*x30))*k22/k22,
  diff(x31, t) = (1*k28*x37*k22 + (-1)*(k29*x10*x31 + (-k30*x37))*k22 + (-1)*k31*(x31 + x37)*k22 + 1*(k48*x2*x9 + (-k49*x31))*k22 + 1*k59*x5*k22)/k22,
  diff(x32, t) = ((-1)*(k60*x32*x13 + (-k61*x15))*k22 + 1*k62*x35*k22)/k22,
  diff(x33, t) = ((-1)*(k42*x34*x33 + (-k43*x35))*k22 + 1*k63*x15*k22)/k22,
  diff(x34, t) = ((-1)*(k42*x34*x33 + (-k43*x35))*k22 + 1*k62*x35*k22)/k22,
  diff(x35, t) = (1*(k42*x34*x33 + (-k43*x35))*k22 + (-1)*k62*x35*k22)/k22,
  diff(x36, t) = (-1)*k27*(piecewise(1, and(t > k3, t < k4), 0) + piecewise(x18, and(t > k5, t < k6), 0))*x36*k22/k22,
  diff(x37, t) = ((-1)*k28*x37*k22 + 1*(k29*x10*x31 + (-k30*x37))*k22 + 1*(k46*x23*x2 + (-k47*x37))*k22)/k22 }