le diagramme trace une courbe en forme de botte : https://tinyurl.com/boot-profile-2

--------------------------------------------------
Note added at 25 mins (2019-08-28 11:36:29 GMT)
--------------------------------------------------

"profile of the valve lift diagram is a so-called \"boot profile"

le profil du diagramme de levée des soupapes est un "profil en forme de botte". Pas de "diagramme" dans la question de l'asker. "diagramme" est au début de la phrase déjà.

--------------------------------------------------
Note added at 2 hrs (2019-08-28 13:35:46 GMT)
--------------------------------------------------

"Piezoelectric actuators have very fast response times enabling the creation of a
variety of injection events [6], including rate shaping [7]. For the purposes of reduced
emissions and improved fuel economy, a special type of rate shape known as the
“boot profile” is of interest [8–10]. Fig. 1.2 shows an example of a boot-shaped
injection profile, and while it will be discussed in detail later in this thesis, it should
be mentioned here that its generation poses a unique set of problems compared to
conventional pulse-shaped fuel injections. Because the injector is hovering somewhere
Figure 1.2. Example of boot-shaped fuel injection profile.
between fully on and fully off during the “toe” portion of a boot shaped injection
event, injector models which account for complex phenomena including piezostack
hysteresis and needle compliance must be used. Additionally, parameter variations
with time and from injector-to-injector become more significant. The development of
the parameter estimation algorithm presented in this thesis improves the closed-loop
control of fuel injection rate in piezoelectric injectors."
Algorithm Development and Analysis for Advanced ... - Purdue e-Pubs
https://docs.lib.purdue.edu › cgi › viewcontent