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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Technology Convergence Prediction From a Timeliness Perspective: An Improved Contribution Index in a Dynamic Network⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Jinzhu Zhang</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Bing Yan</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Department of Information Management, School of Economics and Management, Nanjing University of Science and Technology</institution>
          ,
          <addr-line>Nanjing</addr-line>
          <country country="CN">China</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Technology convergence prediction can identify potential trends and directions in technological development, as well as providing valuable guidance for innovation strategies, research investment, and industrial development. Current methods often construct a technological co-occurrence network to explore the potential associations between technologies for technology convergence prediction. However, its calculation of node importance is often based on quantity statistics of frequencies, failing to break down and distinguish the technological features in each co-occurrence, and assuming equal importance for each technology in every convergence. In addition, the current approach for assessing technological timeliness is too broad, making it difficult to accurately capture technological change. The perspective needs to shift from the life cycle to more specific points in time. Therefore, this paper introduces a contribution index designed to measure changes in the importance of technology convergence from a timeliness perspective. Firstly, we extract and filter valid technical topics to represent technology categories. Secondly, we use dynamic time weights to calculate the semantic similarity between technical topics and patent texts, to indicate the contribution of the technology in each convergence. Thirdly, this paper labels the contributions in technology co-occurrence network to build a dynamic technology network that records changes in technology importance. Finally, we utilize a graph neural network to generate node embeddings for link prediction. In experiments within the field of new energy vehicles, the dynamic network prediction model based on contribution features improved the AUC by 8.92%, 3.52%, and 1.11%, compared to the frequency feature network. It proves that the proposed technological contribution index can effectively enhance the accuracy and effectiveness of technology convergence prediction.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;technology convergence</kwd>
        <kwd>timeliness</kwd>
        <kwd>semantic similarity</kwd>
        <kwd>graph neural network 1</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>The convergence of technologies from different
disciplines can solve increasingly complex technical
problems and social needs. At the same time, it is a key
factor to ensure technological timeliness for increasing
competitiveness in research and investment. Therefore,
how to efficiently and accurately predict the potential
direction of technology convergence from the mass of
existing technologies has become a significant task.</p>
      <p>
        Research often explores the co-occurrence of
technologies to analyze the current state of
technological convergence. And the technology
networks are constructed to explore the potential
correlation between technologies. Current methods for
technological convergence using patent data include
approaches based on patent co-classification [
        <xref ref-type="bibr" rid="ref1 ref2">1, 2</xref>
        ],
patent cross-referencing [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ], and text mining methods
[
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. In these methods, technology categories are
typically identified by patent classification numbers [
        <xref ref-type="bibr" rid="ref5 ref6">5, 6</xref>
        ]
and technical topics [
        <xref ref-type="bibr" rid="ref7 ref8">7, 8</xref>
        ]. In addition, scholars have
expanded the research on technology convergence to a
broader perspective, such as the construction of market
characteristics [
        <xref ref-type="bibr" rid="ref10 ref9">9, 10</xref>
        ], social impacts [
        <xref ref-type="bibr" rid="ref11 ref12">11, 12</xref>
        ] and time
characteristics [
        <xref ref-type="bibr" rid="ref13 ref14">13, 14</xref>
        ], etc., to further improve the
prediction index system of technology convergence.
      </p>
      <p>
        However, these methods do not consider differences
in the importance of technologies in each convergence
and changes in timeliness. They assume that the
importance of each technology is the same in each case
of technological convergence. In addition, the
technology timeliness is often distinguished by
technology lifecycle segmentation [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ] and linear weight
assignment [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ], which are too broad and difficult to
capture small differences between different
technologies. In this paper, a technological combination
co-occurring within a same patent is considered a
convergence event. As shown in Figure 1(a), if
technologies  1  2  3 co-occur with the same frequency,
their importance is considered equal, and there is no
distinction made among the timeliness of their
cooccurrence at different points in time. Actually, different
technologies contribute differently to the overall
technological combination and have different timeliness
with each co-occurrence. As a result, their impact within
the technological network differs in scope and extent.
For example, as shown in Figure 1(b), although
technology  1 is present in each convergence, its
contribution declines over time, indicating declining
importance and possibly gradual obsolescence. On the
other hand, technology  2 maintains a stable
contribution, suggesting that it may be a foundational
technology or in a phase of steady development.
Meanwhile, technology  3 shows a higher contribution,
indicating a greater impact or greater timeliness within
the technology combination, making it more likely to
combine with other technologies.
      </p>
      <p>Therefore, this paper proposes an index designed
from a timeliness perspective to measure changes in the
importance of technology. We obtain the contribution of
the technology in each co-occurrence by calculating the
semantic similarity between the technical topic and the
patent, and then combining the dynamic time weights to
obtain the final value. To capture changes in the
importance of technology in each convergence, we
improve the timeliness of technology by refining it from
the lifecycle and dates to more precise convergence time
points, constructing a dynamic technological
cooccurrence network. Finally, we use link prediction to
explore the prediction of technology convergence,
aiming to better evaluate the timeliness of technology
and its impact on convergence.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Data and Method</title>
      <p>The method for predicting technology convergence
from a timeliness perspective includes three parts, as
shown in Figure 2. Firstly, this paper extracts and filter
out the valid technical topics characterizing the technical
categories in patent texts. Then, cosine similarity is used
for semantic similarity computation on the patent texts
and technical topics to measure the contribution of
different technical topics in each co-occurrence. To
obtain the total contribution score for technical topics,
this study introduces dynamic time weights and follows
the principle of time decay to sum the contributions
from each co-occurrence. Then we extract
cooccurrence relationships to construct a technological
network. Label the contribution of each technical topic
on the matching nodes to build a dynamic technical topic
co-occurrence network. Finally, graph neural networks
are used to learn the node representations of technical
topics, and quantitative evaluation is performed by link
prediction.</p>
      <sec id="sec-2-1">
        <title>2.1. Data collection</title>
        <p>In this paper, the full text data of patent applications
were batch downloaded from the USPTO (United States
Patent and Trademark Office) patent search platform in
December 2023, parsed and stored in a PostgreSQL
database. We use SQL queries to search for relevant
patents in the field of new energy vehicles, as shown in
Figure 3. A total of 23,792 relevant patents were
retrieved and the titles, abstracts and application time of
the patents were extracted as the data source for the
study. A total of 16,975 patents were used as training
data from 2012-2021 and 6,817 patents were used as
test data from 2022-2023. The training set contains
192,602 co-occurring relationships. Relationships that
were not present in the training set were filtered out to
create the actual test set. An equal number of negative
samples</p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. Construction of Contribution Index and</title>
      </sec>
      <sec id="sec-2-3">
        <title>Dynamic Network</title>
        <p>Firstly, this paper extracts technical topics from
patent text, representing specific technical categories.
Secondly, we sum the semantic similarity between
technical topics and patent texts using dynamic time
weights, to represent the contribution of the technology.
Then, we construct a dynamic network of technical
topics by integrating the technological contribution
index. This will help the network to reflect changes in the
contribution of technology over time and provide more
technical clues.</p>
        <sec id="sec-2-3-1">
          <title>2.2.1. Extraction of technical topics</title>
          <p>Technical topics offer a more flexible and
comprehensive expression of technical content, making
them more explainable. Therefore, we choose to use
technical topics to represent different technical
categories.</p>
          <p>This paper determines the optimal number of topics
based on the topic coherence score. And each technical
topic has 20 representative keywords to reduce overlap
between topics. As shown in Figure 4, u_mass and c_v
gradually converged when the number of topics was
around 500. After comparing extreme values, 507 was
identified as the optimal number of topics for this paper.
Secondly, the TF-IDF weighting is applied to improve the
LDA model's process of generating feature words for
technical topic extraction, with the aim of improving the
representativeness of the topic words.</p>
        </sec>
        <sec id="sec-2-3-2">
          <title>2.2.2. Calculation of technical contribution index</title>
          <p>
            As the technical topics and patents in this paper are
both textual content, and the higher the similarity
between technical topics and patent texts, the higher
the weight of that technology in the patent. Therefore,
we use the semantic similarity between technical topics
and patent texts to represent the contribution of
technology in each co-occurrence. The study uses
Doc2vec [
            <xref ref-type="bibr" rid="ref17">17</xref>
            ] to obtain semantic representations of
technical topics and patent texts respectively. Then, it
applies cosine similarity to calculate the semantic
similarity between them, obtaining the contribution
values of different technologies in each co-occurrence,
as shown in Formula (1). Thirdly, it is important to
consider the timeliness of technology. The further away
from the current moment, the lower the timeliness
tends to be. To address this, dynamic time weights are
introduced, based on the retention function of memory
capacity [
            <xref ref-type="bibr" rid="ref18">18</xref>
            ]. This assigns weighted sums to the
contribution of technical topics in each convergence,
resulting in the final contribution index score for the
given technical topic, as shown in Formula (2).
,
(1)
Formula (1) defines 
   as the contribution of
technical topic   in the nth co-occurrence. The semantic
representation m-dimensional vectors of patent i and
technical topic i are denoted as   and   , respectively.
          </p>
          <p>In Formula (2),</p>
          <p>represents the weighted sum
of contributions of technical topic   in all
cooccurrences,</p>
          <p>ℎ is the dynamic time weight,  0

1

is the current year, and   is the year when the nth
convergence occurs.</p>
        </sec>
        <sec id="sec-2-3-3">
          <title>2.2.3. Construction of the dynamic technical topic co-occurrence network</title>
          <p>
            A dynamic technical topic co-occurrence network
construction primarily involves the following two steps.
The first step is to identify the technical topics present in
the patent, we set the probability distribution threshold
to 0.2 [
            <xref ref-type="bibr" rid="ref15">15</xref>
            ]. Technical topics exceeding this threshold are
considered to be present in the patent, resulting in the
generation of a technology co-occurrence matrix. Then
we extract co-occurrence relationships using the
networkx package, forming node pairs that represent
technical topics. Finally, we mark the obtained technical
topic contributions from Section 2.2.2 on the matching
nodes, establishing a dynamic co-occurrence network of
technical topics.
          </p>
        </sec>
      </sec>
      <sec id="sec-2-4">
        <title>2.3. Prediction of technology convergence based on graph neural networks</title>
        <p>We initially employ a graph neural network model to
aggregate the structural and nodal attribute information
of the technological co-occurrence network. This helps
to address the issue of sparse feature dimensions in
technology convergence prediction, resulting in a more
accurate representation of node features. Secondly, we
transform</p>
        <p>the research on predicting technology
convergence into a link prediction problem. Probability
scores
are then
calculated
for the
technology
combinations formed between technical topic nodes,
and the model's performance is evaluated using the AUC
metric.</p>
        <sec id="sec-2-4-1">
          <title>2.3.1. Node embedding based on graph neural network model</title>
          <p>Graph neural network model can automatically
capture high-level abstract representations of networks
by aggregating low-level information, avoiding the need
for complex feature engineering. These models combine
both topological structure and attribute information for
learning, effectively aggregating attribute features and
topological structure information from
neighboring
nodes, to obtain a more accurate feature representation
for the target node.</p>
          <p>This paper uses technical topics in patents as nodes,
with co-occurrence relationships between topics serving
as edges in the graph. The technical contribution
features are combined and used as node attribute
information. Specifically, we first use the co-occurrence</p>
          <p>0.42
( 0 +   )0.0225 ,
(2)
(3)
relationships in the training set as the graph structure.
The contribution index of corresponding nodes is input
as node attribute information into the graph neural
network for training, thereby obtaining the embedding
vectors of known technical topics. Secondly, using a link
prediction model, we calculate the probability of fusion
between technical nodes, obtaining fusion scores
between nodes. The link prediction model is introduced
in Section 2.3.2. Additionally, different graph neural
network models have their own characteristics. This
paper will compare models and choose the one most
suitable for prediction of technology convergence.</p>
        </sec>
        <sec id="sec-2-4-2">
          <title>2.3.2. Link prediction model based on probability ranking</title>
          <p>The prediction of technology convergence can be
simplified as predicting the emergence of a new link
edge. In this context, technologies can be seen as nodes,
and the relationships between them as convergence
links. Thus, this paper transforms the task of predicting
technology convergence opportunities into a link
prediction problem for research.</p>
          <p>The link prediction method proposed in this paper
relies on a co-occurrence graph of technical topics,
where the relationships between technical topics serve
as edges. The technology contribution is trained as node
features on the co-occurrence relationships of technical
topics. Once the representations of the technical topic
nodes are obtained, the probability score for the
technology combination formed by two points is
calculated. This probability score can be regarded as the
link prediction score. The higher the score, the greater
the possibility of a future link between the two nodes,
indicating a higher probability of convergence between
these two technical topics. Finally, we choose AUC as the
evaluation metric to assess the performance of the
prediction model based on graph neural networks.</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Results</title>
      <p>This paper generated three co-occurrence networks
with different features, to compare and validate the
effectiveness of the proposed method. The first network,
T-Co1, only considers the frequency of co-occurrence of
technical topics. The second network, T-Co2, includes
centrality indices as features for technical topic nodes.
The third network, T-Co3, integrates technical
contribution as features for technical topic nodes. The
centrality measure chosen here is degree centrality,
which reflects the number of connections a node has. A
higher degree centrality indicates a stronger node
centrality, signifying greater importance.</p>
      <p>For the three types of co-occurrence networks, we
use three graph neural network models, namely GCN,
GNN and GAT, to learn node representations, using link
prediction for quantitative evaluation. The main
difference between GCN and traditional GNN lies in the
use of convolutional operators for information
aggregation, while GAT uses self-attention mechanisms
for node weight allocation. The results for different
feature networks and methods are shown in Table 1.</p>
      <p>The results show that the performance of T-Co3 is
generally superior to T-Co1 and T-Co2 across different
model representations, with GCN performing best on
TCo3. In the GCN model, the AUC value of T-Co3 has
increased by 8.78% compared to T-Co1 and 8.92%
compared to T-Co2. In the GNN and GAT models, the
AUC value of T-Co3 has also increased by 1.3% and 3.52%,
respectively. Compared to other indicators of
importance, the contribution index reflecting
technological timeliness provides better, more
comprehensive, and accurate clues for predicting
technological convergence. And in this experiment, the
GCN model performed better and showed better
discriminative capabilities for different features. It is
more suitable for the technology convergence prediction
task in this paper.</p>
    </sec>
    <sec id="sec-4">
      <title>4. Conclusion</title>
      <p>This paper refines the assessment of technological
importance from a timeliness perspective, shifting from
traditional distinctions based on lifecycle and dates to a
more precise measurement within each convergence
event. We replace frequency indicators in the
cooccurrence network with the technological contribution
index for building dynamic technology networks. The
results show that this approach outperforms
frequencybased models. As a next step, we aim to improve the
technological timeliness index by incorporating
additional temporal cues. In addition, the exploration of
more efficient embedding models is expected to
improve predictive performance.</p>
    </sec>
    <sec id="sec-5">
      <title>Acknowledgements</title>
      <p>This work is supported by the National Natural
Science Foundation of China (No. 72374103, 71974095)
and the Postgraduate Research &amp; Practice Innovation
Program of Jiangsu Province (No. SJCX23_0161).</p>
    </sec>
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