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    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Time Series Error Detection Solution based on REFII Model and Concept of Nontemporal Expansion</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Goran Klepac</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Algebra University</institution>
          ,
          <addr-line>Gradišćanska 24 10000 Zagreb, Croatia; Hrvatski Telekom, 10 000 Zagreb</addr-line>
          ,
          <country country="HR">Croatia</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>Paper describes novel approach in error detection in technical systems, where errors can be represented as time series. Novelty is in usage of REFII model combined with concept of non -temporal expansion which gives opportunity for recognition of events and attributes which in certain conditions mostly contribute to errors. Technical systems mostly provide their data in shape of time series. Current states of systems like base station can be represent in such form. Signal quality metrics, such as Signal-to-Noise Ratio (SNR) and Bit Error Rate (BER), are fundamental parameters used for error detection in base stations. SNR measures the ratio of the desired signal to the background noise, providing an indication of signal clarity. A high SNR signifies a clear signal with minimal interference, while a low SNR suggests potential errors. BER, on the other hand, quantifies the rate at which errors occur in the transmitted data, serving as a direct measure of communication integrity. All mentioned metrices and more, can be represented through time series. Potential of time series are huge, but it demands analytical solution which will release all potential of time series. Proposed solution will release opportunity for applying methods like time decision trees and associative algorithms directly on time series enriched by temporal expansion with non-temporal components. Rare events, though infrequent, can have profound implications on the systems they occur within. Recognizing these events is crucial for several reasons: • Early Error Detection: Identifying rare events allows for the early detection of errors or anomalies that may indicate system malfunctions. Early intervention can mitigate potential damage, reduce downtime, and save costs associated with repairs and lost productivity. • Enhanced Predictive Maintenance: In industrial settings, recognizing rare events can aid in predictive maintenance. By predicting when machinery or equipment is likely to fail, maintenance can be scheduled proactively, thereby extending the lifespan of assets and reducing unexpected breakdowns. • Improved Decision Making: In financial markets, the ability to detect rare events such as market crashes or sudden price spikes is invaluable. These events can inform decision-making processes, allowing for more robust risk management strategies and better investment decisions.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Time series</kwd>
        <kwd>REFII</kwd>
        <kwd>nontemporal expansion</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
    </sec>
    <sec id="sec-2">
      <title>2. Literature Review</title>
      <p>The study of error predictions in technical systems using time series analytics is a critical area of
research with profound implications for the reliability and eficiency of various technologies.</p>
      <p>
        There are diferent approaches in time series analytics according to error prediction, Shumway at
al. [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] introduces the principles and applications of time series analysis, ofering comprehensive coverage
of techniques essential for error prediction in technical systems. Hyndman [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ] emphasizes forecasting
methods, including those used in predicting system errors, with reference to current methodology for
time series analytics. It is visible that event inclusion is not something which is subject of time series
analysis. Chandola [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] explores methods for detecting anomalies in time series data, which is crucial for
identifying potential errors in technical systems, and event inclusion is not something which is subject
of time series analysis.
      </p>
      <p>
        Zhang [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] provides a comprehensive review of various time series analysis and forecasting techniques,
highlighting their applications in error prediction. Paper [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ] discusses the application of machine
learning algorithms to time series forecasting, with a focus on predicting system errors, describing
mostly well-known methodology from perspective of potential usage and can be applicable for error
detection purposes.
      </p>
      <p>
        Zhang [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] explores the use of neural networks in forecasting time series data, providing insights
into their efectiveness for error prediction. Book [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ] ofers an in-depth look at statistical methods
for time series forecasting, essential for predicting errors in technical systems. Mobley [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ] discusses
the application of time series analysis in predictive maintenance, a key aspect of error prediction in
technical systems.
      </p>
      <p>
        Elsayed [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] explores the use of deep learning techniques for forecasting time series data, with a focus
on error prediction in technical systems. Box [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ] introduces ARIMA models, which are widely used
for time series forecasting and error prediction. In [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ] authors propose a novel method for anomaly
detection in time series, which is essential for predicting errors. Wang [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] presents a multi-scale
approach using convolutional neural networks to classify and predict time series data. Hochreiter
and Schmidhuber [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ] explore the use of Long Short-Term Memory (LSTM) networks for time series
prediction.
      </p>
      <p>
        Dietterich [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ] provides a comparative analysis of various time series prediction techniques, assessing
their efectiveness for error prediction. Gelman [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ] discusses the application of Bayesian methods to
time series forecasting, highlighting their advantages for error prediction.
      </p>
      <p>
        Breiman [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ] explores the use of ensemble methods to improve time series forecasting accuracy.
Vapnik [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] introduces the use of support vector machines for time series forecasting, with a focus
on error prediction. In his paper Castro [18] discusses real-time anomaly detection techniques for
streaming data, essential for predicting errors in technical systems. Kumar and Singh [19] explore
hybrid approaches that combine diferent time series analysis techniques for improved error prediction.
Liu and Lijang [20] evaluates various time series models for their efectiveness in forecasting errors in
technical systems.
      </p>
    </sec>
    <sec id="sec-3">
      <title>3. Conceptual solution of time series error detection solution</title>
      <p>In the realm of technical systems, error detection is of paramount importance to ensure reliability,
performance, and safety. This document presents a conceptual solution that leverages the Time Series
Model REFII and event integration to enhance the accuracy and eficiency of error detection.
• Advanteges: High Accuracy: REFII’s ability to learn complex temporal relationships results in
precise anomaly detection.
• Real-time Processing: The model can process data streams in real-time, allowing for immediate
error detection and response.
• Adaptability: REFII can be retrained with new data to adapt to changing system behaviors,
ensuring continued accuracy.</p>
      <p>Event integration involves the synthesis of diverse events and signals within a technical system to
provide a comprehensive understanding of its state. By integrating events, the system can correlate
anomalies detected by the time series model with specific operational occurrences, ofering a holistic
view of potential errors.</p>
      <p>Event integration is achieved through nontemporal expansion. The synergy between the Time Series
Model REFII and event integration forms a robust framework for error detection in technical systems.</p>
      <sec id="sec-3-1">
        <title>3.1. Value transformation into REFII model</title>
        <p>If values such as Signal-to-Noise Ratio (SNR) and Bit Error Rate (BER), on each individual attribute is
observed as time series (1, . . . , ) first step is normalization</p>
        <p>The normalization procedure implies the transformation of a time series (1, . . . , ) into a time
series  (1, . . . , ) where each element of the array is subject to a min-max normalization procedure
to the &lt;0,1&gt; interval.</p>
        <p>Time series  is made up of elements (1, . . . , ), where  is calculated as
 =</p>
        <p>− ()
() − ()
(1)
where min() and max() are the minimum and maximum values of time series  .</p>
        <p>Next step is transformation to REF notation according to the formula:
 = +1 − ,  &gt; 0 → ;  &lt; 0 →  ;  = 0 → ; where the  elements are members of the
 series.</p>
        <p>After that, slope calculation based on the angle should be performed for calculating angular deflection
coeficients:
•  &gt; 0 →  Coeficient = (+1 − 
•  &lt; 0 →  Coeficient =  − +1
•  = 0 →  Coeficient = 0</p>
        <p>Area below curve is next calculation which can be performed with usage of numerical integration by
rectangle theory on following way ( is a time span in this case can be arbitrary defined):
 = ( * ) + ( * )</p>
        <p>2</p>
        <p>REF notation together with angular deflection coeficients and area below curve are base for pattern
description among values. Table 1. Shows example of description based on presented methodology.</p>
        <p>This is the first step in time series transformation, which is the base for non temporal expansion
concept.
(2)</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Non temporal expansion concept</title>
        <p>The non-temporal expansion concept is a sophisticated approach to enhancing traditional time series
data by incorporating events and facts that lack inherent temporal markers. This process is executed
through a methodology known as interpolation, where non-temporal data is systematically associated
with the existing timeline, thus enriching the overall dataset.</p>
        <p>Interpolation, in this context, involves the insertion of non-temporal data points into the chronological
sequence of a time series. The REFII model employs advanced algorithms to determine the most suitable
positions within the time series where these data points should be placed. This is achieved through
associative techniques that analyze the characteristics and relationships of the events and facts with
existing temporal data</p>
        <p>The core of proposed methodology is the association process. This involves establishing connections
between non-temporal events and facts and the relevant segments of the time series.</p>
        <p>Non-temporal events and facts are mapped onto the time series based on their contextual relevance,
ensuring that their inclusion enhances the overall narrative and analytical value of the data. The
application of the non-temporal expansion concept via the REFII model ofers several notable benefits:</p>
        <p>Enhanced Data Completeness: By integrating non-temporal data, the time series becomes more
comprehensive, capturing a wider array of information and insights. Improved Analytical Accuracy:
The inclusion of related events and facts allows for more precise and nuanced analyses, as the data
reflects a broader spectrum of influencing factors.</p>
        <p>Richer Contextual Understanding: The contextual mapping of non-temporal data provides deeper
insights into the temporal dynamics, revealing underlying patterns and trends that might otherwise be
overlooked.</p>
        <p>The non-temporal expansion concept represents a significant advancement in the field of time series
analysis. Through the interpolation of events and facts using the REFII model, it is possible to create
a more detailed and accurate representation of temporal data. This approach not only enhances the
depth and breadth of the dataset but also improves the quality of insights derived from it, ultimately
leading to more informed and efective decision-making processes.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Empirical Results</title>
      <p>Time series data are transformed into REFII model with nontemporal expansion characterized by
observations indexed in time order, can be complex and challenging to analyze. When integrated with
non-temporal events, the complexity increases, requiring sophisticated algorithms to derive meaningful
insights. Decision trees and associative algorithms can help in reducing that complexity. They can
produce results in the form of rules with associated certainty factors.</p>
      <p>When decision trees are applied to integrated time series and non-temporal data, the results are
typically expressed as a set of rules. Each rule has a certainty factor, indicating the confidence level in
the rule’s predictive power. The certainty factor is derived from the proportion of correct predictions
made by the rule during training on the dataset.</p>
      <p>For example:
• Rule: If SNR rise than Weather=“BAD”, New integration=“Yes”.</p>
      <p>Certainty Factor: 0.65 (65% confidence)
• Rule: If SNR =“Low” than Weather=“Sunny”, New integration=“No”.</p>
      <p>Certainty Factor: 0.98 (98% confidence)</p>
      <p>Associative algorithms are also applied on data set and used to find frequent patterns and associations
within datasets. When applied to integrated time series and non-temporal events, they can reveal
complex relationships and dependencies. The results of associative algorithms are often presented as
association rules, each with a support and confidence metric. Support indicates the frequency of the
rule within the dataset, while confidence measures the likelihood that the rule holds true given the
antecedent. beyond, demonstrating the power of these algorithms in handling complex, integrated
datasets.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusion</title>
      <p>Usage of the REFII model and inclusion nontemporal expansion within REFII model marks a profound
advancement in analytical methodologies. By incorporating nontemporal expansion, utilizing decision
trees, and leveraging associative algorithms, this model introduces new dimensions of precision in data
analysis. The REFII model’s sophisticated approach allows for more accurate forecasting, enhanced
pattern recognition, and improved decision-making processes.</p>
      <p>Through nontemporal expansion, the model extends the analytical framework beyond traditional
temporal constraints, enabling a more comprehensive examination of underlying data patterns. The use
of decision trees further refines this process by providing clear, interpretable structures that facilitate
the identification of critical factors and their interactions.</p>
      <p>Additionally, associative algorithms enhance the model’s capability to uncover complex relationships
within the data, contributing to a deeper and more nuanced understanding of time series dynamics.</p>
    </sec>
    <sec id="sec-6">
      <title>Declaration on Generative AI</title>
      <p>The author has not employed any Generative AI tools.
[18] P. Castro, D. Kreutz, Real-time anomaly detection for streaming analytics, ACM Transactions on</p>
      <p>Management Information Systems (TMIS) 7 (2016) 1–22.
[19] M. Kumar, R. Singh, Hybrid approaches for time series analysis and prediction, Journal of Statistical</p>
      <p>Computation and Simulation 91 (2001) 3293–3310.
[20] H. Liu, B. Jiang, Evaluating the performance of time series models for forecasting errors, Applied
Soft Computing 82 (2019) 105–113.</p>
    </sec>
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