<?xml version="1.0" encoding="UTF-8"?>
<article article-type="Research Article">
  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher">journal-of-dynamical-systems-and-geometric-theories</journal-id>
      <journal-title-group>
        <journal-title>Journal of Dynamical Systems and Geometric Theories</journal-title>
      </journal-title-group>
      <issn publication-format="electronic">2169-0057</issn>
      <issn publication-format="print">1726-037X</issn>
      <publisher>
        <publisher-name>Taru Publications</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="doi">10.47974/JDSGT-2025-11003</article-id>
      <title-group>
        <article-title>An LMI-based framework for observer design in nonlinear systems with delayed measurements</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author" corresp="yes">
          <name>
            <surname>Echi</surname>
            <given-names>Nadhem</given-names>
          </name>
          <aff>Department of Mathematics, Faculty of Sciences of Gafsa, Gafsa University, Gafsa, 2112, Tunisia</aff>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Zaidi</surname>
            <given-names>Imen</given-names>
          </name>
          <aff>Department of Mathematics, Faculty of Sciences of Sfax, Sfax University, Sfax, 3000, Tunisia</aff>
        </contrib>
      </contrib-group>
      <volume>24</volume>
      <issue>1</issue>
      <fpage>71</fpage>
      <lpage>86</lpage>
      <pub-date date-type="pub">
        <day>11</day>
        <month>07</month>
        <year>2026</year>
      </pub-date>
      <abstract>
        <p>In this paper, we address the problem of observer design for time-delay systems with delays in both the state and the input, under the global Lipschitz condition on the system nonlinearity, using a Linear Matrix Inequality (LMI) approach. Utilizing the recent results from Nguyen, Zemouche, and Trinh [28], this work further elaborates and expands upon them. The aim of this study is to present a novel design approach. Utilizing advanced mathematical techniques, the reformulation of the Lipschitz property enhances its practicality and reduces conservatism. Furthermore, the exponential stability of the augmented closed-loop system and the estimation error dynamics is established through a Halanay-inequality-based method. A numerical example, based on the dynamics of a directional antenna in a telecommunications system, is provided to illustrate the effectiveness of the proposed results. </p>
      </abstract>
      <kwd-group>
        <kwd>Observer design</kwd>
        <kwd>Time-delay systems</kwd>
        <kwd>Halanay-inequality</kwd>
      </kwd-group>
      <custom-meta-group>
        <custom-meta>
          <meta-name>access</meta-name>
          <meta-value>open</meta-value>
        </custom-meta>
        <custom-meta>
          <meta-name>retracted</meta-name>
          <meta-value>no</meta-value>
        </custom-meta>
      </custom-meta-group>
    </article-meta>
  </front>
</article>
