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Concept

Histoire de la mesure du temps

Publications associées (13)

Triple Crossed Flexure Pivot Based on a Zero Parasitic Center Shift Kinematic Design

Simon Nessim Henein, Etienne Frédéric Gabriel Thalmann

Thanks to their absence of play, absence of contact friction and possible monolithic fabrication, flexure pivots offer advantages over traditional bearings in small-scale, high accuracy applications and environments where lubrication and wear debris are pr ...

2022

Shaking force balancing of a 2-DOF isotropic horological oscillator

Simon Nessim Henein, Etienne Frédéric Gabriel Thalmann, Hubert Pierre-Marie Benoît Schneegans

Despite centuries of research and significant advances, the escapement mechanism used to count and maintain oscillations of mechanical time bases remains a complex mechanism and a major source of energy losses. We showed in previous work that, instead of t ...

2021

Rocker oscillator time bases

Simon Nessim Henein, Ilan Vardi

Since the invention of the pendulum clock by Christiaan Huygens in 1657, precision timekeepers have been regulated by oscillators. Although the pendulum is not an isochronous oscillator, its introduction as a time basis for clock regulation led to a signif ...

2021

Optical measurement method for mechanical time base characterization

Simon Nessim Henein, Etienne Frédéric Gabriel Thalmann

The recent adoption of silicon components by the mechanical watch industry has triggered the search for new time bases to advantageously replace the traditional balance and hairspring oscillator. In particular, flexure-based oscillators manufactured in sil ...

euspen2021

Flexure Pivot Oscillators for Mechanical Watches

Etienne Frédéric Gabriel Thalmann

It appears that the concerted efforts of the watchmaking industry are leading towards a limit in mechanical watch accuracy. The general consensus in horology is that the time base's quality factor, a dimensionless number that characterizes the oscillator d ...

EPFL2020

Design of a Flexure Based Low Frequency Foucault Pendulum

Simon Nessim Henein, Ilan Vardi, Patrick Robert Flückiger

The Foucault pendulum is a well-known mechanism used to demonstrate the rotation of the Earth. It consists in a pendulum launched on linear orbits and, following Mach’s Principle, this line of oscillation will remain fixed with respect to absolute space bu ...

2020

Programmable Multistable Mechanisms: Design, modeling, characterization and applications

Mohamed Gamal Abdelrahman Ahmed Zanaty

Multistable Mechanisms are mechanical devices having more than one stable state. Since these mechanisms can maintain different deformations with zero force, they are advantageous for low power environments such as wristwatches and medical devices. In this ...

EPFL2018

Gravity-Insensitive Flexure Pivot Oscillators

Simon Nessim Henein, Ilan Vardi, Etienne Frédéric Gabriel Thalmann, Mohammad Hussein Kahrobaiyan, Lennart Rubbert

Classical mechanical watch plain bearing pivots have frictional losses limiting the quality factor of the hairspring-balance wheel oscillator. Replacement by flexure pivots leads to a drastic reduction in friction and an order of magnitude increase in qual ...

2018

Escapement-Based Movements as Positioning Mechanisms: Design and Modelling

Romain David Besuchet

This work has been triggered by an industrial project targeting the design of a mechatronic injector for the medical field. Injections are usually performed using a syringe, a quite clumsy tool that transforms the injection task in a positioning one. The q ...

EPFL2016

Consistency Models in Distributed Systems with Physical Clocks

Jiaqing Du

Most existing distributed systems use logical clocks to order events in the implementation of various consistency models. Although logical clocks are straightforward to implement and maintain, they may affect the scalability, availability, and latency of t ...

EPFL2014

Conception acoustique de systèmes microtechniques

Considered as one of the most difficult complications in horology, the mechanical chiming watch, known as the striking watch, has today become one of the symbols of high craftsmanship. When it chimes the hour the sound of a striking watch must not only be ...

EPFL2011

Analyse et mise en oeuvre d'un moteur électromagnétique microfabriqué

Sebastiano Merzaghi

Until now, the preferred solution for MEMS (Micro Electro Mechanical Systems) actuation is the electrostatic one. The main reason is that this kind of actuators can be easily manufactured following the microfabrication rules, as their geometry perfectly fi ...

EPFL2010

Particle shape versus friction in granular jamming

Thomas Liebling, Lionel Pournin, Michel Tsukahara

What is the influence of sand grain shapes on an hourglass accuracy, and how does it affect the jamming probability? We study such a question using numerical simulation and our recently introduced spheropolyhedral particles. Spheropolyhedra constitute a ve ...

AIP2009