Search results for "Mechanical engineering"

Porous architecture and thermal properties of thermal barrier coatings deposited by suspension plasma spray

2020

Abstract Besides the intrinsic low heat transfer capability of material, the thermal insulation property of thermal barrier coatings (TBCs) also relies on their microstructures. For better understanding the relationship between process parameters, porous architecture, and thermal properties of coatings, YSZ coatings were firstly manufactured by suspension plasma spray (SPS). Afterwards their total porosities were characterized by using the technique of X-ray transmission, the nano/submicro pores in those coatings were detected with Ultra-Small Angle X-ray Scattering (USAXS), and the thermal properties of coatings were measured using the laser flash method. The results indicated that: i) the…

Multi-scale analysis of surface topographies by modal filtering

2012

International audience; This work introduces an innovative method for the multi-scale analysis of surface topographies, which consists of applying a method based on a new parameterization. This kind of surface parameterization refers to natural modes of vibration, and is therefore named modal parameterization. It allows us to characterize the form, waviness and roughness defects of a surface. This parameterization opens up new fields of analysis, such as the appearance quality of surfaces. It is thereby possible to decompose a measured surface in a vector basis, of which vectors are represented by plane natural eigenmodes sorted by frequency and complexity. Different filtering operations ca…

Good practices and uncertainty assessment process on AACMM

2017

International audience; This paper presents a methodology of evaluating the performance of Articulated Arm Coordinate Measuring Machines (AACMM) for general acceptance-based on the manufacturer's specifications, and on site-based mainly on the application requirements. The first part of this paper takes stock of ISO 10360-12: 2016 standard, which defines the tests that the AACMM user should perform to validate or not the performance of his machine. The various tests recommended by the standard are analyzed and their practical usefulness is explained. In the second part of the paper, an on-site uncertainty estimation methodology is proposed. The interest of the on-site verification methodolo…

PROPOSITION OF AN INTERIM STANDARDIZED TEST FOR ARTICULATED ARM COORDINATE MEASURUNG MACHINE

2018

International audience; Improving the kinematic calibration of a coordinate measuring arm using configuration analysis Precis. Eng. 50 171-82 1. Comparison of the AACMM mechanical deformation during the ISO 10360-12 test and the interim test. 2. Study the possibility of calibration of an AACMM with the proposed interim test, or a similar test (study already engaged). Note: The recommendations concerning the repetition and calculation were detailed in [1] and the recommendations concerning the length of the small artifact and the directions of measurement will be detailed in our coming work.

Modèle théorique pour estimer les incertitudes de positionnement de l'effecteur d'un robot parallèle à câble plan

2018

International audience; Les robots parallèles à câbles se développent de plus en plus pour diverses applications. Leur principal avantage réside dans leur capacité de déplacement très rapide sur des distances qui peuvent être importantes. Les déplacements s'effectuent grâce à l'enroulement du câble sur un cabestan. La commande de ces robots est réalisée en pilotant le couple appliqué à chaque câble la position d'équilibre dynamique repose donc sur l'équilibre des efforts appliqués à l'effecteur. La mesure de la position se fait donc de manière indirecte et sans boucle de retour. Pour intégrer ces robots dans un dispositif métrologique, il est nécessaire d'estimer les incertitudes de positio…

Target 5G visible light positioning signal subcarrier extraction method using particle swarm optimization algorithm

2021

International audience; With the explosive growth of demand for Internet of Things (IoT) applications and the increasing dependence of users on wireless connections, indoor location based service(LBS) under 5G-Public-Private Partnership (5G-PPP) using cases have received more attention and get rapid development. Thanks to the safty, security and customization of 5G network pointed by 5G forum white paper, indoor positioning systems using unified 5G New Radio (NR) signals have become the focus of the next generation of visible light positioning (VLP) systems. In 5G New Radio(NR) frame, totally 192 subcarriers are used to carry positioning reference signal(PRS). In order to improve the positi…

Combustion wave structure during the MoSi2 synthesis by Mechanically-Activated Self-propagating High-temperature Synthesis (MASHS): In situ time-reso…

2006

Abstract In situ synchrotron time-resolved X-ray diffraction experiments coupled with an infrared imaging camera have been used to reveal the combustion wave structure during the production of MoSi2 by Mechanically Activated Self-propagating High-temperature Synthesis (MASHS). The fast combustion front exhibits a form described as an ‘equilibrium structure’ where the chemical reaction is the sole major driving force. In the MASHS process, oxide-free interfaces between Mo and Si nanocrystallites enhance the reaction Mo+2Si→MoSi2. Exhaustive time-resolved investigations show a possible solid-state process in the first second of the reaction within the combustion front. If preheating is added,…

Conception basée sur les origamis pour l'impression 4D de structures déployables

2020

Deployable structures can be deformed between the different configurations through predetermined mechanisms, showing the great potential in many engineering applications. However, their exquisite and intricate mechanisms also bring a great difficulty to the design of its structure. With the growing 4D printing efforts, its self-transforming characteristics under external stimuli provide new possibilities for deploying complex and challenging driving structures. Furthermore, origami-based engineering has provided tremendous technical support for structural conversion, especially from 2D to 3D states, leading to many design studies based on origami-inspired deployable structures. However, the…

Solving the riddle of the high-temperature chemistry of 1,3-dioxolane

2022

Modélisation numérique de structures composites réparées par collage de patchs externes en traction

2014

National audience; Request PDF on ResearchGate \textbar On Dec 30, 2014, Lingling Peng and others published Modélisation numérique de structures composites réparées par collage de patchs externes en traction