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vaddya
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Apr 23, 2017
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# coding=utf-8 | ||
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import math | ||
import numpy as np | ||
import matplotlib.pyplot as plt | ||
from matplotlib import cm | ||
from matplotlib.ticker import LinearLocator, FormatStrFormatter | ||
from mpl_toolkits.mplot3d import Axes3D | ||
from scipy import integrate, interpolate, optimize | ||
from matplotlib import rc | ||
from matplotlib.ticker import FormatStrFormatter | ||
font = {'family': 'Arial', 'weight': 'normal'} | ||
rc('font', **font) | ||
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# Нахождение длины балки | ||
def fun(x: float): | ||
def inner(z: float): | ||
return math.exp(-0.9 * z)/(z + x) | ||
return integrate.quad(inner, 0, 20)[0] - 0.1957981 * x; | ||
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x_star, = optimize.fsolve(fun, (4 - 1) / 2) | ||
print('x* = {x}'.format(x=x_star)) | ||
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l = 50 * x_star | ||
print('Длина балки l = {l}'.format(l=l)) | ||
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# Начальные условия | ||
def get_y0(p: int): | ||
y0_1 = 0 | ||
y0_2 = 0 | ||
y0_3 = p * l / 75 * 10 ** (-7) | ||
y0_4 = p * 3.8 / 75 * 10 ** (-7) | ||
return np.array([y0_1, y0_2, y0_3, y0_4]) | ||
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# Значения нагрузки на балку | ||
def get_p(): | ||
return np.arange(500, 1000 + 1, 100) | ||
p0 = 750 | ||
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# Вычисление значения в точке t | ||
def evaluate(y: np.array, t: float, a: float, b: float): | ||
i = a * (1 + 4 * math.exp(-b * t/l)) | ||
di1 = 4 * a * (-b) * math.exp(-b * t/l) / l | ||
di2 = 4 * a * (-b) * (-b) * math.exp(-b * t/l) / l | ||
y41 = -1 * di2 / i | ||
y42 = -2 * di1 / i | ||
y4 = y41 * y[2] + y42 * y[3] | ||
return np.array([y[1], y[2], y[3], float(y4)]) | ||
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# Решение дифференциального уравнения | ||
# Пределы поиска значений y(t) | ||
t0 = l - 5 | ||
tn = l + 5 | ||
th = 0.01 | ||
t = np.arange(t0, tn, th) | ||
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# Итерация по всем значениям P | ||
values = [] | ||
for p in get_p(): | ||
y0 = get_y0(p) | ||
res, info = integrate.odeint(evaluate, y0, t, args=(5,6), atol=1e-8, full_output=True) | ||
y = np.transpose(res)[0] | ||
values.append(y) | ||
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# График y(t) | ||
axes = plt.figure(figsize=(10,7)).gca() | ||
for i in range(len(get_p())): | ||
axes.plot(t, values[i], linewidth=1.5, label='$P = {p}$'.format(p=get_p()[i])) | ||
axes.plot([l, l], [0, 0.008], color='0.7', linewidth=1.5, linestyle='--', label='$t = l \simeq {l}$'.format(l=math.ceil(l))) | ||
axes.legend(loc='upper left', fontsize=15) | ||
axes.set_xlabel('$t$', fontsize=20, labelpad=20) | ||
axes.set_ylabel('$y(t)$', fontsize=20, labelpad=20) | ||
axes.tick_params(labelsize=15, pad=10) | ||
axes.set_xlim([l-5, l+5]) | ||
plt.tight_layout() | ||
plt.savefig('./pics/p.png') | ||
plt.show() | ||
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# Зависимость значения y(l) от P | ||
p_interps = np.array([]) | ||
l_values = [] | ||
for i in range(len(values)): | ||
p_interp = interpolate.interp1d(t, values[i]) | ||
p_interps = np.append(p_interps, p_interp) | ||
l_value = p_interp(l) | ||
l_values.append(l_value) | ||
print('P = {p}, f(l) = {value}'.format(p=get_p()[i], value=l_value)) | ||
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# График S(P) | ||
axes = plt.figure(figsize=(10,7)).gca() | ||
axes.plot(get_p(), l_values, linewidth=1.5, marker='s', label='$f(l) = f(P)$') | ||
axes.plot([p0, p0], [0.0008, 0.0018], linewidth=1.5, color='0.7', linestyle='--', label='$P = P_0 = {p0}$'.format(p0=p0)) | ||
axes.legend(loc='upper left', fontsize=20) | ||
axes.set_xlabel('$P$', fontsize=20, labelpad=20) | ||
axes.set_ylabel('$f(l)$', fontsize=20, labelpad=20) | ||
axes.tick_params(labelsize=15, pad=10) | ||
axes.set_xlim([450,1050]) | ||
plt.tight_layout() | ||
plt.savefig('./pics/l.png') | ||
plt.show() | ||
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# Поиск значения S(P0) = S(750) | ||
l_interp = interpolate.interp1d(get_p(), l_values, kind='cubic') | ||
l_p0 = l_interp(p0) | ||
print('P = {p}, S(P) = {value}'.format(p=p0, value=l_p0)) | ||
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# Анализ влияния погрешности начальных условий на решение | ||
# Пределы варьирования коээфициентов | ||
a0 = 5 | ||
b0 = 6 | ||
h = 0.01 | ||
a = np.arange(0.9 * a0, 1.1 * a0 + h, h) | ||
b = np.arange(0.9 * b0, 1.1 * b0 + h, h) | ||
g = np.meshgrid(a, b, indexing='ij') | ||
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# Итерация по всем значения alpha и beta | ||
values = [] | ||
for alpha in a: | ||
tmp = [] | ||
for beta in b: | ||
y0 = get_y0(p0) | ||
res = integrate.odeint(evaluate, y0, t, args=(alpha,beta), atol=1e-8) | ||
y = np.transpose(res)[0] | ||
p_interp = interpolate.interp1d(t, y) | ||
l_value = p_interp(l) | ||
tmp.append(np.abs((l_value - l_p0))) | ||
values.append(tmp) | ||
values = np.array(tmp) | ||
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# График epsilon(alpha, beta) | ||
axes = plt.figure(figsize=(12,8)).gca(projection='3d') | ||
axes.plot_surface(g[0], g[1], values, alpha=0.4, cmap=cm.coolwarm) | ||
axes.view_init(elev=30., azim=12) | ||
axes.zaxis.set_major_formatter(FormatStrFormatter('%.0e', )) | ||
axes.set_xlabel(r'$\alpha$', fontsize=25, labelpad=20) | ||
axes.set_ylabel(r'$\beta$', fontsize=25, labelpad=25) | ||
axes.set_zlabel(r'$\varepsilon(\alpha, \beta)$', fontsize=25, labelpad=35) | ||
axes.set_xlim(min(a), max(a)) | ||
axes.set_ylim(min(b), max(b)) | ||
axes.tick_params(labelsize=15, pad=10) | ||
axes.tick_params('z', labelsize=15, pad=15) | ||
plt.tight_layout() | ||
plt.savefig('./pics/ab.png') | ||
plt.show() |
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