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<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="ru"><front><journal-meta><journal-id journal-id-type="publisher-id">izmertech</journal-id><journal-title-group><journal-title xml:lang="ru">Измерительная техника</journal-title><trans-title-group xml:lang="en"><trans-title>Izmeritel`naya Tekhnika</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">0368-1025</issn><issn pub-type="epub">2949-5237</issn><publisher><publisher-name>ФГУП "ВНИИФТРИ"</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.32446/0368-1025it.2024-12-22-29</article-id><article-id custom-type="elpub" pub-id-type="custom">izmertech-2241</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>ТЕПЛОФИЗИЧЕСКИЕ ИЗМЕРЕНИЯ</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>THERMOPHYSIC MEASUREMENTS</subject></subj-group></article-categories><title-group><article-title>Применение рациональных функций в первичной и вторичной термометрии</article-title><trans-title-group xml:lang="en"><trans-title>Application of rational functions in primary and secondary thermometry</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Кытин</surname><given-names>В. Г.</given-names></name><name name-style="western" xml:lang="en"><surname>Kytin</surname><given-names>V. G.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Владимир Геннадьевич Кытин</p><p>г. п. Менделеево, Московская обл., </p><p>Москва</p></bio><bio xml:lang="en"><p>Vladimir G. Kytin</p><p>Mendeleevo, Moscow region,</p><p>Moscow</p></bio><email xlink:type="simple">kyt35@mail.ru</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Потапов</surname><given-names>Б. Г.</given-names></name><name name-style="western" xml:lang="en"><surname>Potapov</surname><given-names>B. G.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Борис Геннадьевич Потапов</p><p>г. п. Менделеево, Московская обл.</p></bio><bio xml:lang="en"><p>Boris G. Potapov</p><p>Mendeleevo, Moscow region</p></bio><email xlink:type="simple">potapov@vniiftri.ru</email><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Петухов</surname><given-names>А. А.</given-names></name><name name-style="western" xml:lang="en"><surname>Petukhov</surname><given-names>A. A.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Алексей Анатольевич Петухов</p><p>г. п. Менделеево, Московская обл.</p></bio><bio xml:lang="en"><p>Alexey A. Petukhov</p><p>Mendeleevo, Moscow region</p></bio><email xlink:type="simple">petukhov@vniiftri.ru</email><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Асланян</surname><given-names>Э. Г.</given-names></name><name name-style="western" xml:lang="en"><surname>Aslanyan</surname><given-names>E. G.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Эдуард Георгиевич Асланян</p><p>г. п. Менделеево, Московская обл.</p></bio><bio xml:lang="en"><p>Eduard G. Aslanyan</p><p>Mendeleevo, Moscow region</p></bio><email xlink:type="simple">aslanyan@vniiftri.ru</email><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Щипунов</surname><given-names>А. Н.</given-names></name><name name-style="western" xml:lang="en"><surname>Shchipunov</surname><given-names>A. N.</given-names></name></name-alternatives><bio xml:lang="ru"><p>г. п. Менделеево, Московская обл.</p><p> </p></bio><bio xml:lang="en"><p>Andrey N. Shchipunov</p><p>Mendeleevo, Moscow region</p></bio><email xlink:type="simple">schipunov@vniiftri.ru</email><xref ref-type="aff" rid="aff-2"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Всероссийский научно-исследовательский институт физико-технических и радиотехнических измерений, Московский государственный университет имени М.В. Ломоносова;&#13;
Московский государственный университет им. М. В. Ломоносова</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Russian Metrological Institute of Technical Physics and Radio Engineering;&#13;
M. V. Lomonosov Moscow State University</institution><country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-2"><aff xml:lang="ru"><institution>Всероссийский научно-исследовательский институт физико-технических и радиотехнических измерений</institution><country>Россия</country></aff><aff xml:lang="en"><institution>Russian Metrological Institute of Technical Physics and Radio Engineering</institution><country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2024</year></pub-date><pub-date pub-type="epub"><day>13</day><month>01</month><year>2025</year></pub-date><volume>73</volume><issue>12</issue><issue-title>Юбилей ВНИИФТРИ - 70 лет</issue-title><fpage>22</fpage><lpage>29</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; ФГУП "ВНИИФТРИ", 2025</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="ru">ФГУП "ВНИИФТРИ"</copyright-holder><copyright-holder xml:lang="en">ФГУП "ВНИИФТРИ"</copyright-holder><license xlink:href="https://www.izmt.ru/jour/about/submissions#copyrightNotice" xlink:type="simple"><license-p>https://www.izmt.ru/jour/about/submissions#copyrightNotice</license-p></license></permissions><self-uri xlink:href="https://www.izmt.ru/jour/article/view/2241">https://www.izmt.ru/jour/article/view/2241</self-uri><abstract><p>Для определения частот акустического и электромагнитного резонанса в акустической газовой термометрии разработан метод аппроксимации частотных зависимостей акустического сигнала и комплексного коэффициента пропускания резонатором электромагнитного излучения, не требующий задания начального приближения параметров аппроксимации. Метод основан на представлении функции, используемой для аппроксимации частотных зависимостей в акустической газовой термометрии, в виде рациональной функции. Аппроксимация экспериментальной частотной зависимости рациональной функцией сводится к быстро сходящейся последовательности линейных аппроксимаций, которая легко реализуется на персональном компьютере. Отсутствие необходимости задания начального приближения параметров аппроксимации значительно упрощает и ускоряет апроксимацию частотных зависимостей и определение резонансных частот. Проведена аппроксимация рациональной функцией температурных зависимостей сопротивления эталонных родий-железных термометров в диапазоне температур 0,5–273 К как альтернатива традиционной аппроксимации полиномами двух разных типов в двух температурных поддиапазонах 0,5–26 К, 26–273 К. Показано, что при аппроксимации температурной зависимости сопротивления родий-железного термометра единой рациональной функцией в диапазоне температур 0,5–273 К отклонение аппроксимирущей функции от экспериментальных значений температуры не превышает 0,5 мК. Количество параметров аппроксимации рациональной функции меньше, чем при аппроксимации полиномами двух типов с сопоставимым отклонением аппроксимирующей функции в экспериментальных точках. Полученный результат значительно упрощает перевод сопротивления в температуру при использовании родий-железных термометров сопротивления.</p></abstract><trans-abstract xml:lang="en"><p>Method has been developed for determination of acoustic and microwave resonance frequences in acoustic gas thermometry by fitting of frequency dependencies of acoustic signal and complex transmission coefficient of the resonator by microwave radiation. The method does not require setting of initial parameters. The method is based on the representation of fitting function used for approximation of frequency dependence in acoustic gas thermometry by rational function. Then approximation of experimental frequency dependence by rational function is performed by quickly converged series of linear approximations. This series can be easily implemented on PC. Method eliminates setting of initial parameters. This simplifies and accelerates approximation of frequency dependences and determination of resonant frequences. Approximation of temperature dependencies of resistivity of standard rhodium-iron resistance thermometers was performed by rational function in the temperature range from 0.5 to 273 K as an alternative for traditional approximation by two different polynomial functions in temperature subranges from 0.5 to 26 K and from 26 to 273 K. It has been shown that the approximation of the temperature dependence of resistivity of rhodium-iron thermometer by single rational function provides deviation of fitting function from experimental points less than 0.5 mK in the range from 0.5 to 273 K. Amount of parameters of such rational function is less than amount of parameters of two polynomial functions providing comparable deviation at experimental points. Obtained result significantly simplifiers resistance to temperature transfer for rhodium-iron standard thermometers.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>измерения температуры</kwd><kwd>аппроксимация экспериментальных данных</kwd><kwd>родий-железные термометры сопротивления</kwd><kwd>рациональные функции</kwd><kwd>акустический газовый термометр</kwd></kwd-group><kwd-group xml:lang="en"><kwd>temperature measurements</kwd><kwd>approximation of experimental data</kwd><kwd>rhodium-iron resistance thermometers</kwd><kwd>rational functions</kwd><kwd>acoustic thermometry</kwd></kwd-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Калиткин Н. Н. Численные методы. Под. ред. А. А. Самарского. Наука, Москва (1978).</mixed-citation><mixed-citation xml:lang="en">Kalitkin N. N. Numerical methods. Ed. A. A. Samarskyi. 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