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2019年美国大学生数学建模比赛 E题.pdf
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Contents
1 Introduction ............................................................................................................... 1
1.1 Background .......................................................................................................... 1
1.2 Problem description ........................................................................................... 1
1.3 Our work .............................................................................................................. 1
2 Assumptions and Justifications ............................................................................. 2
3 Symbols and Descriptions ...................................................................................... 2
4 Model I : STARMA-network model .................................................................... 3
4.1 Flow chart .............................................................................................................. 3
4.2 Spatio-temporal prediction model of opioid use................................................... 3
4.2.1 Space-time data analysis and processing ................................................... 3
4.2.2 Spatial weight matrix and adjacent hierarchy division ............................... 4
4.2.3 Modeling ..................................................................................................... 5
4.2.4 Model Solution ........................................................................................... 6
4.2.5 Result analysis and conclusion .................................................................... 7
5 Model II: Projection pursuit model ................................................................... 10
5.1 Data Processing .................................................................................................... 10
5.2 Establish of Projection pursuit model’s ............................................................... 11
5.2.1 Modeling ................................................................................................... 11
5.2.3 Result analysis and conclusion .................................................................. 13
5.3 Adjustment of model I ......................................................................................... 14
6 How to fight against the opioid crisis .................................................................. 15
6.1 Governance Strategy ............................................................................................ 15
6.2 Validity of the test model strategy ....................................................................... 16
7 Sensitivity Analysis ................................................................................................. 18
8 Strengths and Weaknesses ..................................................................................... 19
7.1 Strength .............................................................................................................. 19
7.2 Weaknesses ........................................................................................................ 19
MEMORANDUM .......................................................................................................... 20

Team # 1921203 Page 1 of 22
1 Introduction
1.1 Background
According to the New York Times’ estimation in June 2017 after integrated data of
American states, the number of opioid overdose deaths in America is likely to exceed
59,000, which is more than the death toll of shootings and traffic accidents across the
country[1]. Opioid abuse also affects the quantity and quality of the American workforce
and the prospects for U.S. economic growth. Goldman Sachs’ recent report showed that
the opioid abuse had become the key factor of why workers of prime age, mainly male,
unable or unwilling to find employment. President Trump told the media in 2017 that the
opioid crisis is one of the biggest challenges America met. The media called the northwest
corner of West Virginia, which borders Kentucky, Huntington, as the epicenter of the
opioid crisis. The five states around the epicenter are the “disaster zone” of drug abuse:
Ohio, Kentucky, West Virginia, Virginia, and Pennsylvania.
1.2 Problem description
According to the requirements of the problem,We need to solve the following
problems:
➢ Use the data provided by NFLIS to model the data over time.
➢ Describe the evolutionary characteristics of synthetic opioid and heroin events
between five states and their counties based on our models.
➢ Use the established models to predict the origins of opioid abuse in five states.
➢ Identify the threshold at which the drug abuse has a significant impact on society
based on the patterns of spread and characteristics the established models obtained.
➢ Use the established models to predict which state will reach the threshold we
determined at what time.
➢ Use data from the U.S. census to position the characteristics of opioid abuse
populations.
➢ Identify what factors caused the use of opioids and the growth of drug addiction, and
why many people still use opioids despite knowing their perniciousness.
➢ Modify the first part of the models based on important factors in the data set.
➢ Integrate previous conclusions to identify possible strategies to combat the opioid
crisis and model to test the effectiveness of the proposed strategies and identify any
significant parameters that result in the success (or failure) of the strategies.
1.3 Our work
In this paper, we break our work into sections as follows:
➢ Process the primary data .
➢ Establish a spatio-temporal hybrid model of neural network and STARMA (time-
space autocorrelation moving average model), and solve the synthesis of opioid and
heroin events over time.
➢ Establish a projection pursuit evaluation model, and analyze the characteristics of
opioid abusers.
➢ 4. Establish a probability model in order to verify the rationality of the model.

Team # 1921203 Page 2 of 22
➢ Set reasonable strategies based on our model results and provide effective advice to
the lead administrator.
2 Assumptions and Justifications
1. Assume that opioid users cannot completely quit drug addiction in the short term.
2. Before the governing policies are introduced, each state's trend of drug abusing
remains unchanged.
3. Regardless of the period between the proposition of the governing policies and their
implementation, that is, the policies can be implemented immediately after it is
proposed.
4. Assume that there is only one drug user per Drug Reports, that is, the number of drug
users is equal to the number of Drug Reports.
3 Symbols and Descriptions
Symbol
Definition
Symbol
Definition
W
Weight matrices
k
Number of periods of time delay
ij
w
The neighborhood relationship
between i and j
p
Autoregressive order of time
ij
d
The distance between I and j
q
Average number of time moves
i
w
The sum of the ith row
elements
k
Order of space
()n
W
Order n space weight matrix
( )
t
The error vector for the random
normal distribution
( )
zt
Time and space variables
n
Number of samples
I
The order of the spatial delay
( , )x i j
The jth index value of the ith
sample
Comprehensive weight matrix
Q(a)
The objective function
()zi
The projection values

Team # 1921203 Page 3 of 22
4 Model I : STARMA-network model
4.1 Flow chart
Time-space
sequence of Drug
Report
Determine the correlation and
stability of spatiotemporal sequences
Establish a spatial
weight matrix
Y
STARMA model
identification
Neural network processing
Time and space
trend item
Residual
Parameter
Estimation
Model checkingN
Forecast result
Y
Prediction model for Drug Report based on time series hybrid model
4.2 Spatio-temporal prediction model of opioid use
4.2.1 Space-time data analysis and processing
We studied related datas of 5 American states (VA、PA、WV、OH、KY) from 2010 to
2017, and we processed the column of data in the Drug Reports first. We added up the
Drug Reports’ data of each county in each state, and we obtained the Drug Reports for
each state, which we called SUM Drug Reports. On this basis, according to space-time
attributes, we obtained the space-time plane data of the SUM Drug Reports through
counting 5 states in 8 years from 2010 to 2017. We could see from figure 1 that VA 、WV
and KY’s data series are nonstationary sequences, and OH、PA are steady array。
2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
6000
7000
8000
9000
10000
11000
12000
VA
KY
SUM Drug Reports
2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
20000
25000
30000
35000
40000
45000
50000
OH
SUM Drug Reports
2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
20000
22000
24000
26000
28000
PA
SUM Drug Reports
2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
1500
2000
2500
3000
3500
4000
WV
SUM Drug Reports
Figure 1 The trends of the space-time plane data of SUM Drug Reports

Team # 1921203 Page 4 of 22
In order to dealing with nonstationary sequences,we decided to use neural network
to extract the large-scale trend term. The neural network sets a hidden layer. The input
layer includes 4 variables: latitude of the state, longitude of the state, time, and quantity of
Drug Reports. The hidden layer includes 3 nodes, and each node is a nonlinear function:
sigmoid function[2]. The activation function is a linear regression function. The final
output of the predicted number of crimes is the trend term of the space-time sequence.
The parameters of the neural network model are shown in table 1. The test result of the
neural network extraction of global space-time trend term shows that the root mean square
error (RMSE) was 0.222, and the relative square root error (RSE) is 0.049. Both errors are
small, so it can be considered that the predicted values of the neural network are the trend
terms of the space-time sequence.
Table 1 The parameters of neural network model
Node1(sigmoid)
Node2(sigmoid)
Node3(sigmoid)
Regression(linear)
X: 1.105
X: 4.318
X: -18.60
Node1: -1.077
Y: 2.834
Y: -5.110
Y: 3.586
Node2: -1.370
t: 0.055
t: -0.076
t: -0.488
Node3: -1.062
Bias :-1.355
Bias: -8.475
Bias: -2.876
Threshold: 0.446
4.2.2 Spatial weight matrix and adjacent hierarchy division
According to the topology of spatial unit, there are three principles of spatial
proximity determination mentioned in the literature: Rooks、Bishops and Queens. No
matter which principle is used, the nearest neighbor is called the direct nearest neighbor
of the central unit X (n-order nearest neighbor), and on this basis, the direct nearest
neighbor forms the second order nearest neighbor of X, which can also be extended to the
n-order nearest neighbor.
Through spatial weight matrix W, we can quantify the spatial proximity between n
spatial units.
W
is as follows:
11 12 1
2
21 22
31 32
n
n
nn
w w w
w
ww
W
w w w
=
(1)
The element
ij
w
in W shows the neighborhood relationship between spatial unit
i
and spatial unit
j
. If the principle of spatial proximity determination is true, the value is
1/d
ij
2
; otherwise, the value is 0, that is:
22
1/ ,
0,
ij ij
ij
r
w
h
dd
ot e
=
(2)
In response to the n-order nearest neighbor, there are also partitions of n-order
neighbor (n-order spatial weight matrix). We made following definitions and extended
them: the spatial unit
i
itself is defined as zero-order, and the zero-order spatial weight
matrix is denoted as
(0)
W
; the first-order refers to the direct nearest neighbor region of
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