Complex resonance frequencies of a finite, circular radiating duct with an infinite flange

Radiation by solid or fluid bodies can be characterized by resonance modes. They are complex, as well as resonance frequencies, because of the energy loss due to radiation. For ducts, they can be computed from the knowledge of the radiation impedance matrix. For the case of a flanged duct of finite length radiating on one side in an infinite medium, the expression of this matrix was given by Zorumski, using a decomposition in duct modes. In order to calculate the resonance frequencies, the formulation used in Zorumski's theory must be modified as it is not valid for complex frequencies. The analytical development of the Green's function in free space used by Zorumski depends on the integrals of Bessel functions which become divergent for complex frequencies. This paper proposes first a development of the Green's function which is valid for all frequencies. Results are applied to the calculation of the complex resonance frequencies of a flanged duct, by using a formulation of the internal pressure based upon cascade impedance matrices. Several series of resonance modes are found, each series being shown to be related to a dominant duct mode. Influence of higher order duct modes and the results for several fluid densities is presented and discussed

De nouvelles perspectives pour les archives en région

Les archives et cinémathèques en région sont nombreuses en France. Leur thématique est le plus souvent associée à des fonds, consultables sur place, centrés sur la composante géographique dont elles constituent la mémoire. La valorisation de ces fonds d’archives passe par l’amélioration du service fourni aux utilisateurs qui souhaitent un accès simple et rapide et une source de renseignements décrivant les fonds. Dans l’immédiat, les nouvelles technologies via Internet et Intranet, peuvent él..

Musique et patrimoine : les archives corses

Au lendemain de la Première Guerre mondiale, un phénomène marquant se produit dans le paysage culturel français : la tendance à la convergence de tous les modes d’expression artistique. La musique française, en plein renouvellement, entre dans une de ses périodes les plus brillantes et l’on va la voir participer à son tour à ce mouvement. Des musiciens « sérieux » accepteront de se mettre au service du cinéma. Cette collaboration s’amorce alors que le septième art est encore muet. Elle s’acce..

Smartphone Based Tele-Rehabilitation

Lefebvre Thierry, Mattei Jean-Pierre, Marie Michel, Bleys Jean-Pierre. Les Journées du cinéma muet de Pordenone. In: 1895, revue d'histoire du cinéma, n°14, 1993. pp. 103-113

Antinuclear Antibodies in Patients with Psoriatic Arthritis Treated or Not with Biologics

International audienceBackground:With the emergence of biotherapies, accurate diagnosis in early arthritis is needed. At this time, there is no biological marker of psoriatic arthritis.Objective:To test whether antinuclear antibodies (ANA) can be used as a diagnostic tool in psoriatic arthritis (PsA), we evaluated the prevalence of ANA in biologic-naïve PsA patients and in healthy blood donors.Methods:232 patients from the Rheumatology department, St Marguerite's Hospital, Marseilles, who fulfilled the CASPAR criteria for PsA, underwent clinical and laboratory investigations. Antinuclear antibodies (ANA), anti-extractable nuclear antigen antibodies (ENA), rheumatoid factor (RF), anti-citrullinated protein antibodies (ACPA) were assayed. Ninety-one healthy blood donors were also tested.Results:Detection of ANA by indirect immunofluorescence was significantly more frequent in sera from PsA patients than those from controls at serum dilution of 1:100 (57% compared with 40%, Odds Ratio (OR) 1.98 (1.2-3.4) p<0.02) and 1:160 (52% compared with 24%, OR 3,7 (1.9-7.2) p<0.001). No patients had lupus specific autoantibodies, 15 % had RF (34/232), and 1.7 % had ACPA (4/232).Conclusions:Detection of ANA was more frequent in sera from PsA patients than in those from healthy controls. This suggests that ANA could be a diagnosis orientation tool in PsA. Nevertheless, the specificity of these antibodies still remains to be investigated

Experimental analysis of the whistling of an industrial riser

International audienceThe acoustic field induced by a flow in a corrugated pipe has been studied for a long time. There has been renewed interest in the development of offshore gas exploitation using long riser lengths for gas transport. On such installations, the phenomenon can lead to a failure of the equipment adjacent to the risers. In this context, a Flow-Induced Pulsations (FLIP) test was performed in a 6" internal diameter and 18-meter-long flexible pipe. This riser was equipped with upstream and downstream measuring couplers on which were fixed hot wire velocity sensors, pressure sensors and microphones. A series of tests was conducted for various internal pressures and flow rates. We present a time-frequency analysis of the signals resulting from these tests as well as a correlation study between the various sensors. We observed that the signals measured in the whistling condition showed significant temporal and frequency fluctuations. We were able to show that the frequency fluctuations were related to the geometry of the riser. In addition, these analyses made it possible to show that the whistling exists at transverse acoustic frequencies of the riser while propagating at the convective velocity of the flow

Flow Induced Pulsations (FLIP) in 6-inch rough bore gas flexible pipes Test

International audienceSince the beginning of the 21 st century FLow-Induced Pulsations (FLIP) has been more and more experienced. The phenomenon is characterized by an acoustic wave that is created inside of the flexible pipe and that may lead to significant fatigue failure of the adjacent equipment. Flexible pipe integrity is not called into question regarding this phenomenon. In this context, a FLIP joint test involving an Oil Company, a Flexible Pipe supplier and a French research center was conducted end of 2016 at French laboratory in Poitiers. The test was performed in a 6'' internal diameter and 18-meter-long flexible pipe. Both flow directions were tested to assess the influence of the rounded edges of the carcass. On the one hand, this paper presents the experimental test setup and the main results that came out of the test. On the other hand, this paper also presents the comparison between tests results and analytical model outcome. Moreover, combining experiments and theoretical point of view enabled reproducing the phenomenon. A better understanding of the phenomenon will allow flexible pipes suppliers to propose mitigations or cancellation of FLIP to companies

IoT and information processing in smart energy applications.

The articles in this special section address smart energy applications from the perspective of the Internet of Things (IoT). For smart grid applications, we need to predict the electrical load so that the underlying smart grid can effectively balance the power supply and demand. In general, predictions are made based on the data obtained using IoT and smart meter technologies. The (IoT) could accelerate establishment of such infrastructures. With IoT technologies, many more devices could be controlled and managed through the Internet; data pertaining to the grid, commercial buildings, and residential premises can readily be collected and utilized. To derive valuable information from the data, further information and data processing become essential

Kidd Blood Group and Urea Transport Function of Human Erythrocytes Are Carried by the Same Protein

International audienc