Since a few years, a new wind measurement instrument has been competing with standard cupanemometers: the LiDAR. The performances of this instrument over complex terrain are stilla matter of debate and this is mainly due to the flow homogeneity assumption made by theinstrument. In this work, the error caused by this hypothesis was evaluated with the helpof OpenFOAM 1.7, MeteoDyn WT 4.0 and WAsP Engineering for a LiDAR deployed on a complexsite covered with dense forest. The assessment of the CFD model firstly revealed thesignificant impact of both the location and nature of the inlet boundary condition.Despite the presence of terrain complexity within a radius of 340 m around the remotesensor, an averaged error of less than 3% was observed, suggesting that the LiDAR is onlyaffected by topographic variations in the immediate vicinity of the scanned volume.

An experimental investigation of the Marangoni convection around a single vapor bubble ofFC-72 on a downward-facing heated surface was reported. The boiling cell used for thisstudy was equipped with an optical measurement system which was dedicated to the ParticleTracking Velocimetry (PTV) method. This method allowed us to obtain the velocity fields inthe liquid around the vapor bubble. From the velocity fields obtained, we verified thepresence of Marangoni convection rolls in the vicinity of the liquid-vapor interface.Lastly, the influence of levels of subcooling on the velocity of convective rolls relatedto the Marangoni effect was investigated.

For the unsteady simulation of compressible subsonic flows (Large Eddy Simulation orDirect Numerical Simulation), the proper handling of the inlet boundary is a challengingtask. Indeed, inflow generation through imposition of the velocity may lead to anon-physical reflection of the upstream acoustic waves. In the present contribution, amethod that allows both filtering of these waves and proper imposition of the requiredvariables is proposed. This method is based on identification of the roles of the temporalrate of change of wave amplitudes at the inlet in the low Mach number regime. Theformulation obtained is tested numerically on unsteady one-dimensional flows at low Machnumber for which the unsteady inlet velocity signal is purely harmonic or harmonic withthe superimposition of synthetic turbulence.

This paper presents the analysis of the instabilities inception in a transoniccentrifugal compressor for different rotation speeds. The analysis was conducted fromexperimental results obtained with unsteady pressure sensors implanted in the inducer,vaneless diffuser and vaned diffuser. Beyond the stability limit the compressor entersinto a deep surge without any precursor, whatever the speed. The surge process isinitiated in the vaned diffuser by a massive boundary layer separation. For low speeds,together with the surge which remains triggered in the diffuser, aerodynamic instabilitiesare detected in the inducer. These instabilities can be understood as “tip clearancerotating disturbances” because they are generated at the leading edge of the impeller mainblades and move along the tip clearance trajectory.

Water-lubricated bearings are expected to be widely used because of convenience, green,safe and energy saving. The purpose of this study is to provide references for designinghydrodynamic water-lubricated step thrust bearings. The numerical analysis is undertakenunder the condition of different pad dimensions, step heights, step positions, water filmthicknesses and rotational speeds of thrust rings based on computational fluid dynamics(CFD). The results including pressure distribution, load carrying capacity, frictiontorque and friction coefficient are gained and compared for optimizing geometryparameters. A reference to determine water-lubricated step thrust bearing dimensions and aformula to check the minimum water film thickness are proposed.

Today, to cope with the complexity of the global organization, the industrial companyneeds to be more structured. New processes have to be developed due to more and moreambitious quality requirements. A new problematic arises: what is needed to offer to allcustomers a product that meets the quality requirements of a local market? The mainobjective of this paper is to propose a quality requirements allocation method thatmatches the market specifications and the customer satisfaction. This is in contrast withthe traditional allocation methods which are often time-consuming to implement or do notfocus on the customer satisfaction for the definition of the quality targets. The proposedmethod is inspired from reliability allocation method and is formulated as a feasibilityproblem. In this context the notion of optimality of the solution is not being sought, theobjective is “only” to find out a solution that satisfies the global target quality. Thisallows determining some local quality targets in accordance with industrial data.

The objective of this article is to present the dimensional synthesis of serial andparallel spherical wrists, an important step in the design process of medical robots. Thisstep is carried out to obtain optimal dimensions of tool-guidance medical robots. Withthis goal, we have first studied the specifications of two robots with different medicalapplications: one for tele-echography examination and one for minimally invasive surgery.Then, we have established that the medical needs expressed by the doctors were verydifferent but the specifications in robotic terms have a lot of common points (kinematics,workspace, bulkiness). For both applications studied, robots need a mobility of threerotations around a fixed point (probe contact point on the patient’s skin or trocarincision). So, a spherical wrist architecture is adapted to their needs. An importantconstraint related to medical applications is that the robot must be compact in order tonot obstruct or collide with its environment (medical personnel or patient). We performdimensional synthesis allowing determination of dimensions of the mechanism for serial andparallel spherical wrists, for a tele-echography robot, and a serial wrist for a minimallyinvasive surgery robot. We use multi-criteria optimization methods minimizing a costfunction to obtain both good kinematic performance and compactness for the architecture.The difficulty/challenge of this design process, depending of the studied applications, isthe choice of efficient criteria describing the performances and the constraints of therobot. The design variables must faithfully represent the specifications of the robot sothat its performance can respond to the medical requirements. We show, here, the differentmethods used for optimizing the chosen kinematic architecture for the particular medicalapplication. These studies lead to prototypes which are validated after medicalexperiments. This process of dimensional synthesis will be applied to other medicalapplications with different sets of specified constraints.

In this paper, a Levy-type solution based on the modified couple stress theory isdeveloped to study the buckling behaviors of micro-plates. Based on this theory, lengthscale parameter is considered to capture the size effect of rectangular micro-plates.Minimum potential energy and adjacent-equilibrium criteria are exploited to obtain thestability equations and corresponding boundary conditions. Different boundary conditionswith two opposite edges simply supported and arbitrary boundary conditions along the otheredges are considered. To illustrate the new model, both uniaxial and biaxial loads areapplied and the critical buckling loads are defined for over a wide range of thickness,different length scale parameters and various boundary conditions. To show the accuracy ofthe formulations, present results are compared with available results in literature forspecific cases and a very good agreement is observed. Results reveal that the criticalbuckling load increases as the length scale parameter increases especially when thethickness of the micro-plates becomes in order of length scale parameter and this effectis more significant for free boundary condition.

In this paper, we present techniques for fatigue damage evaluation using spectral methodsand a model taking into account confined elasto-plastic behavior. The model is associatedwith a local fatigue approach, covering the whole endurance domain (low cycle and highcycle fatigue). It uses Neuber’s method and is valid for limited plasticity. To validatethis modeling, we perform a correlation between spectral methods, modified spectralmethods and experimental tests. Results presented here are focused on the uniaxial loadingcase.