Olivier Robin

Bio: Olivier Robin is an academic researcher from Université de Sherbrooke. The author has contributed to research in topics: Boundary layer & Wind tunnel. The author has an hindex of 14, co-authored 53 publications receiving 433 citations.

A Plane and Thin Panel with Representative Simply Supported Boundary Conditions for Laboratory Vibroacoustic Tests

Abstract: A technique to setup a simply supported rectangular plane panel for laboratory vibroacoustic tests is described and validated. For a given panel fixed to thin vertical supports, a dimensionless parameter is proposed to size these supports following a desired frequency precision compared to theoretical eigenfrequencies of a panel with such boundary conditions. A numerical study confirms the potential of this design parameter. Detailed instructions for assembling a panel with adequate thin vertical supports on a rigid frame are then given. Finally, three laboratory cases are described which illustrate possible experimental vibroacoustic applications using a panel assembled following previous guidelines. The design parameter viability is experimentally confirmed, and all obtained results depicted good agreement with analytical solutions and numerical predictions.

Improving sound transmission loss at ring frequency of a curved panel using tunable 3D-printed small-scale resonators

Abstract: An important dip in the sound transmission loss of curved panels occurs at the ring frequency. The relevance of using small-scale resonators to solve this issue is experimentally demonstrated on an aircraft sidewall panel. The effect of varying the spatial distribution of single frequency resonators (including combination with a broadband soundproofing treatment), as well as using multi-frequency resonators with a fixed spatial distribution is studied. Large improvement of the measured sound transmission loss under a diffuse acoustic field excitation is obtained around the ring frequency with limited added mass and very small alteration of the overall sound insulation performance.

Experimental prediction of the vibration response of panels under a turbulent boundary layer excitation from sensitivity functions.

Abstract: This study aims at validating an experimental method for characterizing the vibration behavior of panels excited by a turbulent boundary layer (TBL) excitation as a possible alternative to standard means like wind tunnels or in situ tests. The approach takes advantage of an explicit separation of the excitation contribution from the dynamic behavior of the panel. Based on the measurement of deterministic transfer functions on the panel, called "sensitivity functions," which are then combined with either measurements or a model of the wall-pressure fluctuations induced by the TBL excitation, the vibration response under such an excitation can be retrieved. For validation purposes, the wall-pressure fluctuations of the turbulent flow generated in an anechoic wind tunnel are measured with a flush-mounted microphone array. The decay rates and the convection velocity, which mainly characterize the excitation, are extracted from these measurements. The plate velocity response to this excitation is estimated following the proposed method using the measured sensitivity functions and the model of Mellen fed with experimentally estimated decay rates and convection velocity. A comparison between a directly measured vibration auto-spectrum under the actual flow and the one predicted following the suggested method shows satisfactory agreement.

A User’s Guide

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A review of acoustic imaging methods using phased microphone arrays

Abstract: Phased microphone arrays have become a well-established tool for performing aeroacoustic measurements in wind tunnels (both open-jet and closed-section), flying aircraft, and engine test beds. This paper provides a review of the most well-known and state-of-the-art acoustic imaging methods and recommendations on when to use them. Several exemplary results showing the performance of most methods in aeroacoustic applications are included. This manuscript provides a general introduction to aeroacoustic measurements for non-experienced microphone-array users as well as a broad overview for general aeroacoustic experts.

A Simplified Method

Abstract: A simplified method for the determination of the rate of synthesis of albumin after the i. v. injection of 14C-carbonate is described. A number of experiments to check the accuracy of the 14CO2 measurements is reported. Good agreement is obtained between the specific activity of urinary urea, measured by means of our method and by the manometric method. Recoveries of 101.9 and 101.1% respectively are found for 14C-urea added to plasma or urine. Endogenously formed 14C-urea shows a maximal specific activity 2—3 h after the i. v. injection of 14C-carbonate. Thereafter the specific activity of 14C-urea gradually decreases. Enzymic conversion with arginase and urease and analysis with an amino-acid analyser give the same values for the arginine content of an albumin hydrolysate. Good agreement between the rates ot synthesis and catabolism of albumin, determined respectively with 14C-carbonate and 131I-albumin, was obtained in individual patients. In a group of 6 patients an average rate of synthesis of 10.6 mg/kg · h and an average catabolic rate of 9.5 mg/kg · h were measured. The difference between this simplified method and the manometric technique lies in a direct measurement of the concentration of urea and arginine in the method described here in contrast to the conversion of urea and arginine to CO 2 in the manometric method. Advantages of the simplified method for the determination of the rate of synthesis of albumin are discussed. Es wird eine einfache Methode zur Bestimmung der Synthesegeschwindigkeit von Albumin nach i. v. Injektion von 14C-Carbonat beschrieben. Dazu wurden verschiedene Untersuchungen zur Prufung der Genauigkeit der 14CO2-Messungen durchgefuhrt. Wir fanden eine gute Ubereinstimmung zwischen unserer und der manometrischen Methode bei der Bestimmung der spezifischen Aktivitat des UrinharnstofFs. Es wurden Wiederfindungswerte von 101,9 und 101,1% erzielt, falls 14C-Harnstoff entweder Plasma oder Urin zugefugt wurde. Endogen gebildeter 14C-HarnstofF zeigte 2—3 h nach der i. v. Injektion von 14C-Carbonat eine maximale spezifische Aktivitat. Danach nahm die spezifische Aktivitat des 14C-HarnstofFs langsam ab. Sowohl die enzymatische Umwandlung durch Arginase und Urease als auch die Analyse mittels Aminosaure-Analysator ergaben gleiche Werte fur den Arginingehalt eines Albuminhydrolysats. Bei den einzelnen Patienten wurde eine gute Ubereinstimmung zwischen der Synthese- und Abbaurate von Albumin, bestimmt durch die Untersuchung mittels 14C-Carbonat bzw. 131J-Albumin,

Comparative analysis of building insulation material properties and performance

Abstract: Building envelope insulation is crucial for an energy-efficient and comfortable indoor environment because the envelope accounts for 50–60% of total heat gain/loss in a building. Previous studies mostly used lifecycle cost as the criteria to select the optimum insulation materials with little or no consideration of embodied energy, emission, and summer overheating potential. This study presents a comparative analysis of building insulation materials properties (thermal, hygroscopic, acoustic, reaction to fire, environmental, and cost) and their performance in different climate zones and proposed an optimization framework. Insulation materials can be primarily categorized as conventional, state-of-the-art and sustainable. State-of-the-art insulation materials have the lowest thermal conductivity value amongst the three insulation types. However, their life cycle cost is higher compared to the other types. Sustainable insulation materials could be useful to delay and minimize indoor peak temperature and reduce overheating risk during the hot summer period. The analysis also showed that building walls with comparatively lower thermal resistance are more cost-effective for the cooling dominated region, but walls with higher thermal resistance are more cost-effective in heating-dominated regions. However, highly insulated and airtight houses may also lead to increased overheating risk and peak cooling demand during a hot summer period. In addition, hygroscopic, acoustic, and fire retardancy properties of insulation materials are critical to control indoor relative humidity in a humid region, to maintain a minimum noise level in a zone, and to reduce fire destruction. Hence, the optimization should include four criteria 1) Energy, 2) Environment, 3) Economic, and 4) Comfort.

Time-domain Galerkin method for dynamic load identification

Abstract: Summary This paper proposes a new method called time-domain Galerkin method (TDGM) for investigating the structural dynamic load identification problems. Firstly, the shape functions are adopted to approximate three parameters, such as the dynamic load, kernel function response, and measured structural response Secondly, defining a residual function could be expressed as the difference of the measured response and the computational response. Thirdly, select an appropriate weighting function to multiply the defined residual function and make integral operation with respect to time to be zero. Finally, when the shape functions are chosen as the weighting function, it establishes the forward model called TDGM. Furthermore, the regularization method could have effectiveness in solving the ill-posed matrix of load reconstruction and obtaining the accurate identified results of the dynamic load. Compared with the traditional Green kernel function method (GKFM), TDGM can effectively overcome the influences of noise and improve the accuracy of the dynamic load identification. Three numerical examples are provided to demonstrate the correctness and advantages of TDGM. Copyright © 2015 John Wiley & Sons, Ltd.