En créant deux nouvelles commandes correspondant respectivement à la version courte et à la version longue de l'institut (`\newcommand{\shortinstitute}{\acrshort{inst}}` et `\newcommand{\longinstitute}{\acrlong{inst}}`), il suffit de les appeler au bon endroit dans la création de la page de titre.
Remarque : Je je n'ai pas fait les modifications nécessaires en cas de co-institut.
\documentclass{yathesis}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[xindy]{glossaries}
%
\makeglossaries
%
\makeatletter
\renewcommand{\maketitle}[1][]{%
\booltrue{YAD@maketitle@used}%
\yadsetup{#1}
\setlength{\fboxsep}{10pt}%
\setlength{\YAD@titleboxwidth}{\linewidth-2\fboxsep-2\fboxrule}%
\renewcommand*{\do}[1]{%
\pagestyle{titles}%
\begingroup%
\expandafter\selectlanguage\expandafter{##1}%
\begin{lrbox}{\YAD@titlebox}
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{none}}{%
}{%
\tcbset{colback=white,boxsep=3pt,boxrule=0.4pt,arc=0mm}%
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{shadowbox}}{%
\tcbset{enhanced,drop shadow southeast={black,opacity=1}}%
}{%
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{ovalbox}}{%
\tcbset{arc=3mm}%
}{%
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{fbox}}{%
}{%
\tcbset{code={\expandafter\pgfkeysalsofrom{\cmdKV@YAD@frametitle}}}%
}%
}%
}%
\begin{tcolorbox}
}%
\noindent%
\begin{minipage}{\linewidth-2\fboxsep-2\fboxrule}
\onehalfspacing%
\noindent%
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{none}}{%
}{%
\ifYAD@hdr
\YAD@translation{thesistitle-hdr}%
\else%
\YAD@translation{thesistitle}%
\fi
}%
\par%
\centering%
\Huge\bfseries%
\YAD@ifemptyorundef{\printtitle}{%
\YAD@generic@argument@translate{title}%
\ifbool{YAD@notitle}{%
}{%
\YAD@ClassError[notitle]{%
Titre de la these non specifie%
}{%
La commande \protect\title\space n'a pas ete utilisee\MessageBreak%
(celle-ci est requise) ou son argument obligatoire est vide\MessageBreak%
(celui-ci doit etre renseigne).%
}%
}%
}{%
\printtitle%
}%
\ifundef{\printsubtitle}{%
}{%
\ifdraft{}{\vspace*{\stretch{.15}}}%
% \vspace*{\stretch{.15}}%
\par%
\centering%
\Large\printsubtitle%
}%
\end{minipage}%
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{none}}{%
}{%
\end{tcolorbox}
}%
\end{lrbox}
\settototalheight{\YAD@titleboxheight}{\YAD@titlebox}%
\setlength{\YAD@otherboxheight}{0.3\paperheight-\YAD@titleboxheight}%
%\YAD@astuce@expressioncle%
\noindent%
\ifcsdef{printordernumber}{%
\ifboolexpr{%
bool {YAD@cover@page}%
or (bool {YAD@nofrontcover} and test {\IfLanguageName{\YAD@mainlanguage}})%
}{%
\ifdraft{}{\vspace*{\stretch{1}}}%
% \vspace*{\stretch{1}}%
\raggedleft{%
\itshape%
\sffamily%
\YAD@translation{ordernumber}%
\IfLanguageName{french}{%
\FBcolonspace%
}{%
}: \printordernumber%
}%
}{%
}%
\ifdraft{}{\vspace*{\stretch{.5}}}%
% \vspace*{\stretch{.5}}%
\par%
}{%
}%
% \begin{minipage}[c][\YAD@otherboxheight][c]{\YAD@titleboxwidth}
% \ifdraft{}{\vspace*{\stretch{.25}}}%
\begin{center}
\YAD@ifemptyorundef{\printinstitute}{%
\YAD@generic@argument@translate{institute}%
\ifbool{YAD@noinstitute}{%
}{%
\YAD@ClassError[noinstitute]{%
Institut de la these non specifie%
}{%
La commande \protect\institute\space n'a pas ete
utilisee\MessageBreak%
(celle-ci est requise) ou son argument obligatoire est
vide\MessageBreak%
(celui-ci doit etre renseigne).%
}%
}%
}{%
\YAD@translation{institute} \textbf{\textsc{\Large\longinstitute}}%
}%
\ifundef{\printcoinstitute}{%
}{%
\ifdraft{}{\vspace*{\stretch{.5}}}%
% \vspace*{\stretch{.5}}%
\par%
\YAD@translation{coinstitute} \textbf{\textsc{\Large\printcoinstitute}}%
}%
\ifundef{\printcompany}{%
}{%
\ifdraft{}{\vspace*{\stretch{.5}}}%
% \vspace*{\stretch{.5}}%
\par%
\YAD@translation{company} \textbf{\textsc{\Large\printcompany}}%
}%
\ifdraft{}{\vspace*{\stretch{1.5}}}%
% \vspace*{\stretch{1.5}}%
\par%
\YAD@translation{doctoralschool}
\YAD@ifemptyorundef{\printdoctoralschool}{%
\YAD@generic@argument@translate{doctoralschool}%
\ifbool{YAD@nodoctoralschool}{%
}{%
\YAD@ClassError[nodoctoralschool]{%
Ecole doctorale de la these non specifiee%
}{%
la commande \protect\doctoralschool\space n'a pas ete
utilisee\MessageBreak%
(celle-ci est requise) ou son argument obligatoire est
vide\MessageBreak%
(celui-ci doit etre renseigne).%
}%
}%
}{%
\textbf{\printdoctoralschool}%
}%
\ifdraft{}{\vspace*{\stretch{.5}}}%
% \vspace*{\stretch{.5}}%
\par%
\YAD@translation{universitydepartment}
\ifdefstring{\YAD@main@laboratory@nonamelink}{true}{%
\textbf{\printlaboratory{\YAD@main@laboratory@name}}%
}{%
\textbf{\printlaboratory[\YAD@main@laboratory@url]{\YAD@main@laboratory@name}}%
}%
\ifdraft{}{\vspace*{\stretch{1.5}}}%
% \vspace*{\stretch{1.5}}%
\par%
{\large%
\ifYAD@hdr%
\YAD@translation{thesisdefendedby-hdr} %
\else%
\YAD@translation{thesisdefendedby} %
\fi%
\YAD@ifemptyorundef{\printauthor}{%
\YAD@generic@argument@translate{author}%
\ifbool{YAD@noauthor}{%
}{%
\YAD@ClassError[noauthor]{%
Auteur de la these non specifie%
}{%
La commande \protect\author\space n'a pas ete utilisee (celle-ci
est requise)\MessageBreak%
ou ses 2 premiers arguments obligatoires sont vides\MessageBreak%
(ceux-ci doivent etre renseignes).%
}%
}%
}{%
\textbf{\printauthor}%
}%
\ifboolexpr{%
bool {YAD@submitted@work}%
or bool {YAD@submitted@work@star}%
}{%
% \ifdraft{}{\vspace*{\stretch{1}}}%
% \par%
% \YAD@translation{estimateddefensedate}
% \YAD@ifemptyorundef{\printdate}{%
% \YAD@generic@argument@translate{date}%
% }{%
% \textbf{\printdate}%
% }%
}{%
\ifdraft{}{\vspace*{\stretch{1}}}%
% \vspace*{\stretch{1}}%
\par%
\YAD@translation{defendedon}
\YAD@ifemptyorundef{\printdate}{%
\YAD@generic@argument@translate{date}%
}{%
\textbf{\printdate}%
}%
}%
}%
\ifYAD@hdr%
\else%
\ifdraft{}{\vspace*{\stretch{1}}}%
% \vspace*{\stretch{1}}%
\par%
\YAD@translation{aim}%
\ifundef{\printinstitute}{%
\YAD@generic@argument@translate{institute}%
}{%
% \printinstitute*%
\shortinstitute
}%
\ifundef{\printcoinstitute}{%
}{%
\YAD@translation{aimand}%
\printcoinstitute*%
}%
\fi%
\ifdraft{}{\vspace*{\stretch{1}}}%
% \vspace*{\stretch{1}}%
\par%
\large%
\YAD@translation{academicfield}
%
\YAD@ifemptyorundef{\printacademicfield}{%
\YAD@generic@argument@translate{academicfield}%
\ifbool{YAD@noacademicfield}{%
}{%
\YAD@ClassError[noacademicfield]{%
Champ disciplinaire de la these non specifie%
}{%
La commande \protect\academicfield\space n'a pas ete utilisee
(celle-ci est requise)\MessageBreak%
ou son argument obligatoire est vide (celui-ci doit etre renseigne).%
}%
}%
}{%
\textbf{\printacademicfield}%
}%
\ifundef{\printspeciality}{%
}{%
\ifdraft{}{\vspace*{\stretch{.5}}}%
% \vspace*{\stretch{.5}}%
\par%
\large%
\YAD@translation{speciality} \textbf{\printspeciality}%
}
\end{center}
% \end{minipage}%
\vspace*{\stretch{1}}%
\begin{center}
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{none}}{%
}{%
\ifdraft{}{\vspace*{\stretch{2}}}%
% \vspace*{\stretch{2}}%
}{%
\ifdraft{}{\vspace*{\stretch{.25}}}%
% \vspace*{\stretch{.25}}%
}%
\usebox{\YAD@titlebox}%
% \ifdraft{}{\vspace*{\stretch{2}}}%
\vspace*{\stretch{2}}%
\end{center}
\noindent%
\begin{minipage}[c][\YAD@otherboxheight][c]{\YAD@titleboxwidth}
\YAD@supervisors@tabular%
\par%
\ifboolexpr{%
bool {YAD@submitted@work}%
or bool {YAD@submitted@work@star}%
}{%
\vphantom{\YAD@committee@tabular}%
}{%
\YAD@committee@tabular%
}%
\ifdraft{}{\vspace*{\stretch{.1}}}%
% \vspace*{\stretch{.1}}%
\end{minipage}
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{none}}{%
}{%
% \ifdraft{}{\vspace*{\stretch{2}}}%
\vspace*{\stretch{2}}%
}{%
}%
\ifbool{YAD@supervisor@specified}{%
}{%
\ifbool{YAD@nosupervisor}{%
}{%
\YAD@ClassError*[nosupervisor]{%
Directeur de these non specifie%
}{%
La commande \protect\supervisor\space n'a pas ete utilisee\MessageBreak%
(celle-ci est requise) ou ses arguments obligatoires sont
vides\MessageBreak%
(ceux-ci doivent etre renseignes).%
}%
}%
}%
\endgroup%
\boolfalse{YAD@cover@page}%
}%
\expandafter\docsvlist{\YAD@mainlanguage}%
\ifbool{YAD@two@titles}{%
\booltrue{YAD@second@title}%
\ifthenelse{\equal{\YAD@mainlanguage}{french}}{%
\ifbool{YAD@nofrontcover}{%
\docsvlist{english}%
}{%
\docsvlist{french,english}%
}%
}{%
\ifbool{YAD@nofrontcover}{%
\docsvlist{french}%
}{%
\docsvlist{english,french}%
}%
}%
}{%
}%
\ifthenelse{\equal{\cmdKV@YAD@frametitle}{shadowbox}}{%
\let\tcb@shadow@prepare=\origtcb@shadow@prepare%
}{%
}%
\expandafter\selectlanguage\expandafter{\YAD@mainlanguage}%
\pagestyle{preliminary}%
}%
\AtEndDocument{%
\ifboolexpr{%
bool {YAD@maketitle@used}%
or bool {YAD@nomaketitle}%
}{%
}{%
\YAD@ClassError*[nomaketitle]{%
Commande \protect\maketitle\space non utilisee%
}{%
La commande \protect\maketitle\space n'a pas ete utilisee. Celle-ci est
requise.%
}%
}%
}%
\makeatother
\newacronym{inst}{INST}{Institut avec un long nom}
%
\institute[logo=example-image-a]{\gls{inst}}
\newcommand{\shortinstitute}{\acrshort{inst}}
\newcommand{\longinstitute}{\acrlong{inst}}
\laboratory{Labo}{Adresse du laboratoire}
%
\begin{document}
\title[Title]{Titre}
\maketitle
\end{document}
**EDIT : — ** Plutôt plutôt que de redéfinir complètement la commande `\maketitle`, @touhami propose de chercher et remplacer les parties qui nous intéressent ici en utilisant la commande `\xpatchcmd` du package `xpatch` chargé automatiquement par `yathesis`
`yathesis` :
\xpatchcmd\maketitle{\Large\printinstitute}{\Large\longinstitute}{}{\errmessage{some thing bad happen}}
\xpatchcmd\maketitle{\printinstitute*}{\shortinstitute}{}{\errmessage{some thing bad happen}}
Un MWE donnerait :
\documentclass{yathesis}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[xindy]{glossaries}
%
\makeglossaries
%
\xpatchcmd\maketitle{\Large\printinstitute}{\Large\longinstitute}{}{\errmessage{some thing bad happen}}
\xpatchcmd\maketitle{\printinstitute*}{\shortinstitute}{}{\errmessage{some thing bad happen}}
%
\newacronym{inst}{INST}{Institut avec un long nom}
%
\institute[logo=example-image-a]{\gls{inst}}
\newcommand{\shortinstitute}{\acrshort{inst}}
\newcommand{\longinstitute}{\acrlong{inst}}
\laboratory{Labo}{Adresse du laboratoire}
%
\begin{document}
\title[Title]{Titre}
\maketitle
\end{document}
Aussi, si pour le nom long de l'institut on veut y ajouter son abréviation entre parenthèses, il suffit de remplacer `\newcommand{\longinstitute}{\acrlong{inst}}` par `\newcommand{\longinstitute}{\acrfull{inst}}`
`\newcommand{\longinstitute}{\acrfull{inst}}`.
Un grand merci à @touhami pour la contribution dans son commentaire que j'ai ajouté à cette réponse pour une meilleure lisibilité.