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北京迪捷姆空运技术开发有限公司

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MSDS、UN38.3、DGM、航空运输鉴定报告都是些什么 - 知乎

MSDS、UN38.3、DGM、航空运输鉴定报告都是些什么 - 知乎首发于外贸物流方案切换模式写文章登录/注册MSDS、UN38.3、DGM、航空运输鉴定报告都是些什么物流仔陈小曦​​航空运输行业 销售经理 电池,或者带电产品,要空运或者海运,最终的目的是要做一份空运鉴定报告或者海运鉴定报告,那么怎么做这两种报告呢,这就需要先做一份UN38.3检测报告,拿这个报告才能去申请空运鉴定报告、海运鉴定报告。空运鉴定全称为《航空运输条件鉴定报告书》,是根据委托方要求,由我国民航管理当局认可的有资质的专业鉴定公司做出的鉴定。航空货物运输对安全的要求非常高,特别是利用客机机腹舱进行货物运输时,一些被国际航空协会认定为不确定是否给航空运输带有危害的货物,需要在出运前做一份空运鉴定书,来鉴定此货物是否有危险以及危险等级系数。空运鉴定全称:《航空运输条件鉴别报告书》英语:Identification and Classification Report for Air Transport of Goods俗称:空运鉴定或鉴定需要注意海运没有这种鉴定,海运通常需要MSDS,其实MSDS不是检测报告或鉴定报告,也不是认证项目,只是一份侧重安全操作指引的技术性说明书,和《航空运输条件鉴别报告书》(空运鉴定)有根本的区别。MSDS是没有具体的有效期,只要是符合MSDS上的货物,这份报告就是有效的。而空运鉴定报告是由民航管理当局认可的有资质的专业鉴定,有效期一般是当年,过期就失效了。空运鉴定一般只能由本国民航管理当局认可的有资质的专业鉴定公司出具,而且一般需要寄送样品给鉴定公司进行专业检测,然后出具鉴定报告。不方便寄送样品的,就由鉴定公司的专业人员进行现场检测,然后出具鉴定报告。鉴定报告的有效期一般本年度使用,跨年之后,一般要重新做。空运鉴定报告和UN38.3检测认证是什么关系?电池要空运或者海运,最终的目的是要做一份空运鉴定报告或者海运鉴定报告,那么怎么做这两种报告呢,这就需要先做一份UN38.3检测报告,且需要提交测试概要,拿这份完整报告才能去申请空运鉴定报告、海运鉴定报告。UN38.3认证是指在联合国针对危险品运输专门制定的《联合国危险物品运输试验和标准手册》的第3部分38.3款,即要求锂电池运输前, 必须要通过高度模拟、高低温循环、振动试验、冲击试验、 55℃外短路、撞击试验、过充电试验、强制放电试验,才能保证锂电池运输安全。PS,这个证书基本出证要1个月左右,厂家最好提前准备。根据IATA 902国际航空运输协议要求, 距被测物品表面2.1m处的任意磁场强度应小于0.159A/m(200nT) 才可作普货运输(出普货鉴定) 。凡是物品中含有磁性材料的货物均会在空间产生磁场,需进行磁性货物的安全检测,以保证飞行安全。更多运输鉴定报告请参考之前文章:国际物流运输是最容易出问题的环节,有货出运一定要提前做好出货计划。分享最新国际空海运物流情况及海关新规,以便让客户了解最新国际物流环境,驿传一直在努力!深圳(珠三角)出货,欢迎交流~编辑于 2022-08-09 11:57MSDS鉴定航空运输​赞同 1​​添加评论​分享​喜欢​收藏​申请转载​文章被以下专栏收录外贸物流方案进出口国际空、海运、快递等物流资讯与操

鉴定 北京迪捷姆空运技术开发有限公司

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航空运输条件鉴定

依据国际航空运输协会《危险物品规则》、联合国《试验与标准手册》等,开展航空运输危险品运输条件鉴定业务,涉及的物品包括化工品、磁性物质、机械类设备、电池及含电池的设备等(空运鉴定委托书)

海运运输条件鉴定

依据国际海事组织《国际海运危险货物规则》(IMDG CODE)、联合国《试验与标准手册》等,开展海运危险品运输条件鉴定业务(海运鉴定委托书)

安全技术说明书

依据国际海事组织《国际海运危险货物规则》(IMDG CODE)、国际航空运输协会《危险物品规则》(DGR)、《全球化学品统一分类和标签制度》(GHS),开展化学品安全数据说明书(MSDS)编制业务(MSDS编制业务委托单)

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DGM和MSDS的区别 - 知乎

DGM和MSDS的区别 - 知乎切换模式写文章登录/注册DGM和MSDS的区别货代是怎样炼成的让世界没有困难的物流不知道是否有货代朋友遇到过这样的情况,在空运化工品过程中,问客户要DGM 时,客户下意识的提供MSDS,却嫌少有人知道DGM。 下面INTERMAX来为大家讲解下这两者的区别。MSDS:即物质安全数据单( Material Safety Date Sheet )的英文简写,也常被翻译成化学品安全说明书。它是化学品生产、贸易、销售企业按法律要求向下游客户和公众提供的有关化学品特征的一份综合性法律文件,提供化学品的理化参数、燃爆性能、对健康的危害、安全使用贮存、泄漏处置、急救措施及有关的法律法规等十六项内容。DGM :DGM鉴定是一份产品安全运输的分析报告,来指导空运的操作。主要是检测空运货物是否为危险品的,在货物装上飞机前先要到DGM公司做鉴定(检测)是否为危险品,对于航空公司来说是个参照,有了DGM鉴定航空公司就可以根据货物的具体情况选择装运方式综上所述,DGM 是空运的唯一报告文件,MSDS 则是海运用的。MSDS和DGM两者应用的场合不同,在化工品运输过程中,需要根据不同的运输方式选择适合的报告。发布于 2022-05-30 10:32化学​赞同 1​​添加评论​分享​喜欢​收藏​申请

深度学习求解偏微分方程系列一:Deep Galerkin Method - 知乎

深度学习求解偏微分方程系列一:Deep Galerkin Method - 知乎首发于Kawayikiwi切换模式写文章登录/注册深度学习求解偏微分方程系列一:Deep Galerkin MethodKawayikiwi 我们接下来将用一个系列的文章,介绍使用神经网络的办法求解偏微分方程。这是本系列的第一篇,介绍Deep Galerkin Method (DGM)。我们首先介绍DGM的理论。最后我们使用Python求解一个热传播方程。1. 简介偏微分方程被广泛地应用到自然科学的各个领域,用于对自然或者社会领域问题的建模,例如热传导方程建模热的传播过程,Black-Scholes建模期权的价格,空间的SIR方程建模疾病的传播等。在复杂的场景下,偏微分方程的解是很难用显示的公式来表示。因此,我们只能求助于数值计算。偏微分方程的数值求解方法一直是非常前沿的研究热点,常用的方法包括有限差分、有限元、有限体等。一般地,这些方法需要使用网格来近似偏微分方程的定义空间。网格越细,那么求解得到的解越精确。但相应地,越细的网格需要更高的计算代价与更大的存储空间。因此,这些方法能在低维度的时候得到很好的对原方程解的近似,但受到维度诅咒,在高维度的情况下,计算代价相当大。所以,在高维度的情况下,我们要求助无网格的办法。据我们所知,目前无网格的思想下主要有两类方法。其中一种是蒙特卡洛方法,在某些情况下,可以使用Feynman-Kac公式,将偏微分方程中的待求函数表示成某种随机过程中的随机变量的数学期望,再通过蒙特卡洛求期望的办法求解偏微分方程。蒙特卡洛法的收敛性依赖于空间中采样的点的个数,采样的点越多,我们能得到越精确的解。但相应地,采样点越多,我们的计算时间越长和存储空间越大,在非常高维的情况下,仍然需要很大的计算量。最近,基于深度学习的方法求解偏微分方程得到了越来越多的关注。我们可以使用神经网络来表示偏微分方程中的待求函数,通过学习神经网络的参数来求得偏微分方程的近似解。相较于有网格的方法,深度学习的方法能使得参数的数量大量地降低,从而有更少的计算消耗。同时,由于目前深度学习框架的普及,使用深度学习求解偏微分方程的编程难度也会比有网格的办法更低。目前,基于深度学习的办法求解偏微分方程已经有了很多的研究。关于深度学习,我们之前写过几篇介绍文章,见《深度学习(Deep Learning)系列一:神经网络简介》,《深度学习(Deep Learning)系列二:随机梯度下降与反向传播》,和《深度学习(Deep Learning)系列三:使用伴随法推导反向传播》。这里,我们将做一个系列的文章来介绍神经网络求解偏微分方程的方法。本篇是本系列的第一篇。我们介绍《DGM: A deep learning algorithm for solving partial differential equations》这篇文章中提出的DGM方法。2. 神经网络回顾这里,我们简要回顾一下深度学习的知识。概况地说,深度学习的方法使用神经网络来表达函数,该函数能表示我们需要完成的某个任务的功能。例如,在猫的图片识别的任务中,深度学习能够生成出一张神经网络,该网络能准确判断出用户提供的图片是否是猫。典型地,神经网络由若干层组成,如图1所示。第一层为输入层(图1中的绿色节点),表示了整个网络的输入变量。最后一层为输出层(图1中的红色节点),表示了网络的处理结果。中间的所有层为隐藏层(图1中的蓝色节点)。每一个层又由若干节点组成。隐藏层的每个节点接受上一层的输出,处理后将结果输出到下一层。因此,图1中的每个神经网络的节点都表示一个处理函数。每个节点表示的处理函数都包含了若干个待确定的参数,一旦我们确定了参数,那么整个神经网络就确定了。确定参数的过程就是“学习”的过程。这个“学习”的过程通常来自于对某个优化问题的求解。一般地,我们可以使用符号u_\theta(x)来表示一个神经网络。为了便于叙述,我们仍然使用猫的图片识别任务来作为例子。我们期望函数u_\theta表达的神经网络能处理图片识别任务。函数u_\theta的参数x表达了神经网络的输入,即猫的图片。参数\theta即为整个神经网络的每个节点的函数的参数的集合。我们的目标就是要确定参数\theta从而确定函数u_\theta,这样,我们就有了能判断给定的图像是否是猫的图片的智能工具。为了达到此目的,我们得训练该神经网络。我们给定一些已经标识好有N个样本点的训练集,\{(x_i, y_i)\}_{i=1}^N,其中x_i表示了第i张图片,y_i表示x_i是否为猫的图片。我们的目标是想要u_\theta(x_i),即神经网络对图片x_i的判断,与y_i的结果接近。为此,我们需要求解下面的优化问题\min_\theta \frac{1}{N}\sum_{i=1}^N\|u_\theta(x_i)-y_i\|^2。\qquad (2.1) \\学习的过程即为求解(2.1)优化问题的过程。3. DGM 方法从第2节的描述我们可以看出,本质上,神经网络可以看做一个函数,u_\theta。神经网络的输入层为u_\theta的输入,而输出层为u_\theta的输出。因此,我们可以使用u_\theta来近似偏微分方程中的函数,一旦确定\theta,我们就得到了偏微分方程的解。在本文中,我们介绍《DGM: A deep learning algorithm for solving partial differential equations》中的Deep Galerkin Method (DGM)。本节后面的”我们“可以被理解为使用该篇文章的口吻。具体地,我们考虑下列的偏微分方程的求解\begin{cases} \partial_tu(t,x)+\mathcal{L}u(t,x)=0, (t,x)\in [0,T]\times \Omega,\\ u(0,x)=u_0(x), x\in \Omega,\\ u(t,x)=g(t,x), x\in [0, T]\times \partial \Omega, \end{cases}\qquad (3.1) \\其中,u为未知函数,依赖于时间变量t与空间变量x,\partial \Omega为空间\Omega的边界。因此,方程组(3.1)中,给定了函数u的在t=0时刻的初始条件与在空间\Omega的边界条件。我们需要求解函数u在整个空间中的值。为此,我们使用神经网络u_\theta来近似函数u,其中\theta为神经网络的参数。因此,与第2节中介绍的图片识别的任务类似,我们需要训练神经网络,寻找参数\theta。为此,我们要构造类似(2.1)中的优化问题,使得对每一个输入参数(t,x),u_\theta(t,x)与u(t,x)的值都很接近。因此,我们需要u_\theta尽可能地满足方程组(3.1)。我们定义消耗函数\begin{align*} J(u_\theta)=&\|\partial_tu_\theta+\mathcal{L}u_\theta\|^2_{[0,T]\times\Omega,\nu_1}\\ &+\|u_\theta(t,x)-g(t,x)\|^2_{[0,T]\times\partial\Omega,\nu_2}\\ &+\|u_\theta(0,x)-u_0(x)\|^2_{\Omega,\nu_3}, \end{align*}\qquad (3.2) \\其中,\|f\|^2_{\Omega, \nu}=\int_\Omega f^2\nu dx, \nu为\Omega上的概率密度函数。J(u_\theta)表示了u_\theta对原方程解u的近似误差,如果J(u_\theta)的值很小,那么表示u_\theta大致满足(3.1)中的偏微分方程、初始条件和边界条件。因此,求解偏微分方程(3.1)的解的过程,即为训练神经网络u_\theta的过程,即为求解下列优化问题\min_\theta J(u_\theta)。\qquad (3.3) \\一般情况下,目标函数J(u_\theta)为高维度的非凸函数,且其中包含了高维的积分,直接求解(3.3)是非常困难的。因此,我们使用机器学习中的随机梯度下降方法。具体地,算法的步骤如下:按照概率密度函数\nu_1从 [0,T]\times \Omega中生成样本点(t_n, x_n)。同样地,以\nu_2的概率密度从[0,T]\times\partial\Omega中生成样本点(\tau_n,z_n),按\nu_3的概率密度从\Omega中生成样本点w_n。记\theta_n为第n步迭代的\theta的值,计算平方根误差G(\theta_n,s_n),其中s_n为样本点,即s_n=\{(t_n,x_n), (\tau_n, z_n), w_n\},且\begin{align*} G(\theta_n, s_n)=&\bigg(\partial_tu_{\theta_n}(t_n,x_n)+\mathcal{L}u_{\theta_n}(t_n,x_n)\bigg)^2\\ &+\bigg(u_{\theta_n}(\tau_n,z_n)-g(\tau_n,z_n)\bigg)^2\\ &+\bigg(u_{\theta_n}(0,w_n)-u_0(w_n)\bigg)^2, \end{align*}\qquad (3.4) \\进行梯度下降,更新\theta的值\theta_{n+1}=\theta_n-\alpha_n\nabla_{\theta}G(\theta_n,s_n), \qquad (3.5) \\其中,\alpha_n为下降步长,即也被称为学习率。重复上述步骤直到收敛 注: 在论文《DGM: A deep learning algorithm for solving partial differential equations》中,为了使得计算更有效率,作者给出了使用蒙特卡洛的方法来近似二阶导数,详情可以参考原文。论文《DGM: A deep learning algorithm for solving partial differential equations》也给出了DGM算法在单隐藏层无限宽度网络的情况下的收敛性证明,感兴趣的读者可以参考原文。 4. Python 求解代码在这一节中,我们介绍使用Pytorch来求解下面的热传导方程\begin{cases} u_t - u_{yy}-u_{yy} = (\pi + 2\pi^2)(\cos(\pi t) + \sin(\pi t))\sin(\pi x)\sin(\pi y),\ \text{on}\ [0,4]\times [0,1]\times [0,1],\\ u(0,x,y)=0, \ \text{on}\ [0,1]\times[0,1]\\ u(t,0,y)=u(t,1,y)=0, \ \text{on}\ [0,4]\times[0,1],\\ u(t,x,0)=u(t,x,1)=0, \ \text{on}\ [0,4]\times[0,1]。 \end{cases} \qquad (4.1) \\很容易验证,(4.1)的分析解为u(t,x,y)=\sin(\pi t)\sin(\pi x)\sin(\pi y)。\qquad (4.2) \\下面,我们介绍使用DGM求解(4.1)的Pytorch代码。源代码主要有四个文件组成:libs.py,net.py, heat.py, train.py, 和main.py。其中,libs.py中主要包含了我们要加载的所有包的引入代码,如下:import torch

import matplotlib.pyplot as plt

import numpy as np

from torch.autograd import Variable

import torch.nn as nn

import torch.nn.functional as F

import torch.optim as optim

import matplotlib.pyplot as plt

from mpl_toolkits.mplot3d import Axes3D

from scipy.stats import norm

from matplotlib import cm

神经网络的搭建主要在文件Net.py中。Net.py中包含了Net类,通过给Net的构造函数传递隐藏层的数目与每一层的节点数,就能构造一个神经网络。Net.py的源代码如下:from libs import *

class Net(nn.Module):

# NL: the number of hidden layers

# NN: the number of vertices in each layer

def __init__(self, NL, NN):

super(Net, self).__init__()

self.input_layer = nn.Linear(3, NN)

self.hidden_layers = nn.ModuleList([nn.Linear(NN, NN) for i in range(NL)])

self.output_layer = nn.Linear(NN, 1)

def forward(self, x):

o = self.act(self.input_layer(x))

for i, li in enumerate(self.hidden_layers):

o = self.act(li(o))

out = self.output_layer(o)

return out

def act(self, x):

return x * torch.sigmoid(x)

我们把与方程(4.1)相关的代码放在文件heat.py中。其中包含Heat类,用来计算根据(4.1)得到的神经网络的损失函数。Heat.py的源代码如下:from libs import *

class Heat():

def __init__(self, net, te, xe, ye):

self.net = net

self.te = te

self.xe = xe

self.ye = ye

def sample(self, size=2**8):

te = self.te

xe = self.xe

ye = self.ye

x = torch.cat((torch.rand([size, 1]) * te, torch.rand([size, 1]) * xe, torch.rand([size, 1]) * ye), dim=1)

x_initial = torch.cat((torch.zeros(size, 1), torch.rand([size, 1]) * xe, torch.rand([size, 1]) * ye), dim=1)

x_boundary_left = torch.cat((torch.rand([size, 1]) * te, torch.zeros([size, 1]), torch.rand(size, 1) * ye), dim=1)

x_boundary_right = torch.cat((torch.rand([size, 1]) * te, torch.ones([size, 1]) * xe, torch.rand(size, 1) * ye), dim=1)

x_boundary_up = torch.cat((torch.rand([size, 1]) * te, torch.rand([size, 1]) * xe, torch.ones(size, 1) * ye), dim=1)

x_boundary_down = torch.cat((torch.rand([size, 1]) * te, torch.rand([size, 1]) * xe, torch.zeros(size, 1)), dim=1)

return x, x_initial, x_boundary_left, x_boundary_right, x_boundary_up, x_boundary_down

def loss_func(self, size=2**8):

x, x_initial, x_boundary_left, x_boundary_right, x_boundary_up, x_boundary_down = self.sample(size=size)

x = Variable(x, requires_grad=True)

d = torch.autograd.grad(self.net(x), x, grad_outputs=torch.ones_like(self.net(x)), create_graph=True)

dt = d[0][:, 0].reshape(-1, 1) # transform the vector into a column vector

dx = d[0][:, 1].reshape(-1, 1)

dy = d[0][:, 2].reshape(-1, 1)

# du/dxdx

dxx = torch.autograd.grad(dx, x, grad_outputs=torch.ones_like(dx), create_graph=True)[0][:, 1].reshape(-1, 1)

# du/dydy

dyy = torch.autograd.grad(dy, x, grad_outputs=torch.ones_like(dy), create_graph=True)[0][:, 2].reshape(-1, 1)

f = np.pi * (torch.cos(np.pi*x[:, 0])) * (torch.sin(np.pi*x[:, 1])) * (torch.sin(np.pi*x[:, 2]))\

+ 2 * np.pi * np.pi * (torch.sin(np.pi*x[:, 0])) * (torch.sin(np.pi*x[:, 1])) * (torch.sin(np.pi*x[:, 2]))

diff_error = (dt - dxx - dyy - f.reshape(-1, 1))**2

# initial condition

init_error = (self.net(x_initial)) ** 2

# boundary condition

bd_left_error = (self.net(x_boundary_left)) ** 2

bd_right_error = (self.net(x_boundary_right)) ** 2

bd_up_error = (self.net(x_boundary_up)) ** 2

bd_down_error = (self.net(x_boundary_down)) ** 2

return torch.mean(diff_error + init_error + bd_left_error + bd_right_error + bd_up_error + bd_down_error)

我们将整个的训练过程放在了train.py中。我们使用Adam算法进行训练,源代码如下:from libs import *

class Train():

def __init__(self, net, heateq, BATCH_SIZE):

self.errors = []

self.BATCH_SIZE = BATCH_SIZE

self.net = net

self.model = heateq

def train(self, epoch, lr):

optimizer = optim.Adam(self.net.parameters(), lr)

avg_loss = 0

for e in range(epoch):

optimizer.zero_grad()

loss = self.model.loss_func(self.BATCH_SIZE)

avg_loss = avg_loss + float(loss.item())

loss.backward()

optimizer.step()

if e % 50 == 49:

loss = avg_loss/50

print("Epoch {} - lr {} - loss: {}".format(e, lr, loss))

avg_loss = 0

error = self.model.loss_func(2**8)

self.errors.append(error.detach())

def get_errors(self):

return self.errors

最后,我们在main.py中,将各个类的功能结合在一起,生成并训练网络,得到结果后,我们画出训练误差的变化以及训练出的函数的绘图,源代码如下:import os

os.chdir(os.path.dirname(os.path.abspath(__file__)))

from libs import *

from train import *

from net import *

from heat import *

net = Net(NL=2, NN=20)

te = 4

xe = 1

ye = 1

heatequation = Heat(net, te, xe, ye)

train = Train(net, heatequation, BATCH_SIZE=2**8)

train.train(epoch=10**5, lr=0.0001)

torch.save(net, 'net_model.pkl')

errors = train.get_errors()

#plot errors

fig = plt.figure()

plt.plot(np.log(errors), '-b', label='Errors')

plt.title('Training Loss', fontsize=10)

path = "./pictures/trainingloss.png"

plt.savefig(path)

plt.close(fig)

# net = torch.load('net_model.pkl')

t_range = np.linspace(0, te, 100, dtype=np.float64)

x_range = np.linspace(0, xe, 100, dtype=np.float64)

y_range = np.linspace(0, ye, 100, dtype=np.float64)

data = np.empty((3, 1))

k = 0

for _t in t_range:

TrueZ = []

Z = []

data[0] = _t

for _x in x_range:

data[1] = _x

for _y in y_range:

data[2] = _y

indata = torch.Tensor(data.reshape(1, -1))

Zdata = net(indata).detach().cpu().numpy()

Z.append(Zdata)

TrueZ.append(np.sin(np.pi*_t)*np.sin(np.pi*_x)*np.sin(np.pi*_y))

_X, _Y = np.meshgrid(x_range, y_range, indexing='ij')

Z_surface = np.reshape(Z, (x_range.shape[0], y_range.shape[0]))

True_Z_surface = np.reshape(TrueZ, (x_range.shape[0], y_range.shape[0]))

# plot the approximated values

fig = plt.figure()

ax = fig.gca(projection='3d')

ax.set_zlim([-1, 1])

ax.plot_surface(_X, _Y, Z_surface, cmap=cm.RdYlBu_r, edgecolor='blue', linewidth=0.0003, antialiased=True)

ax.set_xlabel('x')

ax.set_ylabel('y')

ax.set_zlabel('u')

path = "./pictures/%i.png" % k

plt.savefig(path)

plt.close(fig)

# plot the exact solution

fig = plt.figure()

ax = fig.gca(projection='3d')

ax.set_zlim([-1, 1])

ax.plot_surface(_X, _Y, True_Z_surface, cmap=cm.RdYlBu_r, edgecolor='blue', linewidth=0.0003, antialiased=True)

ax.set_xlabel('x')

ax.set_ylabel('y')

ax.set_zlabel('u')

path = "./Sol/%i.png" % k

plt.savefig(path)

plt.close(fig)

k = k + 1

在下面的图2中,我们画出了训练过程中的误差的减小与收敛情况(纵轴为误差的自然对数,横轴为训练的epoch值,即时期数目)。在图3中,显示了(4.2)中的函数的分析解,图4显示了神经网络的数值结果。我么可以看出,神经网络对于偏微分方程(4.1)得出了很好的近似结果。感兴趣的朋友可以试着增加层的深度和宽度看是否能得到更好的结果。发布于 2021-03-23 17:50偏微分方程深度学习(Deep Learning)数值优化​赞同 634​​149 条评论​分享​喜欢​收藏​申请转载​文章被以下专栏收录Kawayikiwi数学与编程知识分享BluehomseGreek Inc.物理信息驱动的深度学习方法本专栏主要追踪物理信息驱动的深度学习研

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  意大利前卫力量金属 DGM ,有乐队前任成员Diego Gianfranco Maurizio组建,因此成为DGM,1994年成立至今共出版7张全长专辑。 队名DGM就是吉他手Diego、鼓手Gianfranco、贝斯手Maurizio这三位乐队创建人的首字母缩写。 鼓手Fabio Constantino 应该是目前团里最元老级的乐手了,也是在2000年加入的,而DGM则始建于1997年。前任主唱Titta Tani 于2006年退出,接替他的是Mark Basile。前任吉他手Diego Reali也在2005年退出,他的技术可谓出神入化,而新来接班的Simone ...(展开全部)

  意大利前卫力量金属 DGM ,有乐队前任成员Diego Gianfranco Maurizio组建,因此成为DGM,1994年成立至今共出版7张全长专辑。 队名DGM就是吉他手Diego、鼓手Gianfranco、贝斯手Maurizio这三位乐队创建人的首字母缩写。 鼓手Fabio Constantino 应该是目前团里最元老级的乐手了,也是在2000年加入的,而DGM则始建于1997年。前任主唱Titta Tani 于2006年退出,接替他的是Mark Basile。前任吉他手Diego Reali也在2005年退出,他的技术可谓出神入化,而新来接班的Simone Mularoni 被人成为六弦天才,绝非等闲之辈。同时键盘手Emanuele Casali 也取代了前任键盘的位置,bass手也有换过。这样一来,现在的DGM可以说已经是另一个乐队了,所以他们的曲风必然会产生较大变化,以前卫金属出道的DGM如今已经是不折不扣的力量金属乐队了。

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[1708.07469] DGM: A deep learning algorithm for solving partial differential equations

[1708.07469] DGM: A deep learning algorithm for solving partial differential equations

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Quantitative Finance > Mathematical Finance

arXiv:1708.07469 (q-fin)

[Submitted on 24 Aug 2017 (v1), last revised 5 Sep 2018 (this version, v5)]

Title:DGM: A deep learning algorithm for solving partial differential equations

Authors:Justin Sirignano, Konstantinos Spiliopoulos Download a PDF of the paper titled DGM: A deep learning algorithm for solving partial differential equations, by Justin Sirignano and Konstantinos Spiliopoulos

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Abstract:High-dimensional PDEs have been a longstanding computational challenge. We propose to solve high-dimensional PDEs by approximating the solution with a deep neural network which is trained to satisfy the differential operator, initial condition, and boundary conditions. Our algorithm is meshfree, which is key since meshes become infeasible in higher dimensions. Instead of forming a mesh, the neural network is trained on batches of randomly sampled time and space points. The algorithm is tested on a class of high-dimensional free boundary PDEs, which we are able to accurately solve in up to $200$ dimensions. The algorithm is also tested on a high-dimensional Hamilton-Jacobi-Bellman PDE and Burgers' equation. The deep learning algorithm approximates the general solution to the Burgers' equation for a continuum of different boundary conditions and physical conditions (which can be viewed as a high-dimensional space). We call the algorithm a "Deep Galerkin Method (DGM)" since it is similar in spirit to Galerkin methods, with the solution approximated by a neural network instead of a linear combination of basis functions. In addition, we prove a theorem regarding the approximation power of neural networks for a class of quasilinear parabolic PDEs.

Comments:

Deep learning, machine learning, partial differential equations

Subjects:

Mathematical Finance (q-fin.MF); Numerical Analysis (math.NA); Computational Finance (q-fin.CP); Machine Learning (stat.ML)

Cite as:

arXiv:1708.07469 [q-fin.MF]

 

(or

arXiv:1708.07469v5 [q-fin.MF] for this version)

 

https://doi.org/10.48550/arXiv.1708.07469

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arXiv-issued DOI via DataCite

Related DOI:

https://doi.org/10.1016/j.jcp.2018.08.029

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Submission history From: Konstantinos Spiliopoulos [view email] [v1]

Thu, 24 Aug 2017 15:50:24 UTC (10 KB)

[v2]

Tue, 5 Dec 2017 13:56:45 UTC (2,452 KB)

[v3]

Sat, 16 Dec 2017 19:19:32 UTC (2,452 KB)

[v4]

Fri, 27 Jul 2018 18:16:30 UTC (5,503 KB)

[v5]

Wed, 5 Sep 2018 19:39:17 UTC (5,498 KB)

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