417 research outputs found
DNS of inertial wave attractors in a librating annulus with height-dependent gap width
No full textDirect numerical simulations (DNS) of inertial wave attractors have been carried out in a librating Taylor-Couette system with broken mirror symmetry in the radial-axial cross-section. The inertial wave excitation mechanism and its localisation at the edges was clarified by applying boundary layer theory. Additional resonance peaks in the simulated response spectra were found to agree with low-order wave attractors obtained by geometric ray tracing. Numerics and theory are in qualitative agreement with recent lab experiments
Intradermal immunization with a bovine herpesvirus-1 DNA vaccine induces protective immunity in cattle
No full textAlthough intramuscular (i.m.) injection of DNA encoding glycoprotein D (gD) of bovine herpesvirus-1 (BHV-1) induces immune responses in cattle, this route of delivery is inefficient. Here we assessed three parameters that may enhance the efficacy of a gD DNA vaccine in cattle. First, the immune response generated by i.m. injected plasmid expressing a secreted form of gD (tgD) was determined and found to be very similar in magnitude to the response induced by gD-expressing plasmid. Secondly, gD- and tgD-expressing plasmids were administered by intradermal (i.d.) immunization, which resulted in a superior immune response to the secreted form, but no improvement in the response to the membrane-associated form. However, the form of gD used for immunization did not influence the immunoglobulin subtype, the ratio of antigen-specific IgG1 to IgG2 being approximately 4:1. Finally, the effect of promoter strength was assessed by replacing the Rous sarcoma virus (RSV) promoter, which was used in the original experiments, with the human cytomegalovirus immediate early promoter and first intron A (HCMV/IA). Although upon transfection in vitro the HCMV/IA promoter appeared to be stronger than the RSV promoter, there was only a 2-fold higher antibody response in vivo upon i.d. injection of cattle. Protection against virus challenge was obtained in the calves immunized i.d. with tgD-encoding plasmid, as shown by a significant reduction in weight loss, virus excretion, temperature response and clinical disease. No significant protection was observed in the animals vaccinated i.d. with the gD-expressing plasmid, which correlates with the lower level of immunity pre-challenge.ID: 3643; LR: 20081121; JID: 0077340; 0 (Antibodies, Viral); 0 (Immunoglobulin G); 0 (Vaccines, DNA); 0 (Viral Proteins); 0 (Viral Vaccines); 0 (bovine herpesvirus type-1 glycoproteins); 82115-62-6 (Interferon-gamma); ppublishSource type: Electronic(1
Gas path analysis for the MTT micro turbine
No full textGas turbine diagnostics is as old as the gas turbine itself. Over the years, performance based diagnostics allowed for a shift from time-based maintenance to more economical condition based maintenance playing a fundamental role in enhancing the availability and reliability of gas turbines. By monitoring the condition of the engine over time, maintenance actions can be taken based on information collected from the field. MTT (Micro Turbine Technology) is currently developing a low cost 3kWe micro-turbine CHP (Combined Heat and Power)-system by using off-the-shelf technologies. Once the system will be launched on the market an organized, cost-effective maintenance procedure will be required. The objective of this M. Sc. thesis project was to develop and demonstrate a Gas Path Analysis diagnostic concept for the micro-turbine. Gas Path Analysis (GPA) is a method to assess the condition of the gas turbine by using performance measurements from the gas path. The feasibility of the diagnostic concept was demonstrated by some case studies using data from the first generation field test units. After reviewing a number of gas turbine diagnostic techniques, a non-linear model based gas path analysis approach was chosen. For the development of the diagnostic concept, a non-linear model of a healthy reference engine was used to simulate the off-design behaviour of the engine and derive healthy performance parameter baselines. These baselines are used to compare the performance of field engines against. A component based modelling environment called GSP or the Gas turbine Simulation Program was used to simulate the effect of ambient conditions and deterioration on performance. The diagnostic concept relies on the principle that deterioration causes corrected measurement parameters to shift from the healthy reference baselines. Measurement performance parameters are first corrected to standard ISA conditions before being compared against the healthy baselines. By modelling specific types of deterioration in GSP, signature parameter shifts could be recorded for each of the deterioration modes. These signature parameter shifts are used to compare shifts in performance parameters against and determine the closest pattern-match which can be used to identify the most probable cause of deterioration. The proposed concept is capable of performing engine level diagnostics and partially component level diagnostics. Multiple fault diagnostics and quantifying the level of deterioration are more difficult due to the limited number of sensors and the relatively large impact of second-order effects such as heat-loss, auxiliary power take-off, mechanical losses, etc. The performance parameter baselines together with the derived rulesets can easily be implemented in a maintenance tool making the concept flexible and easy to use.MastersFlight performance and propulsionAerospace Engineerin
Parallel implementation of interior-point methods for semidefinite optimization
No full textElectrical Engineering, Mathematics and Computer Scienc
Ruth Kundrats Identification Card
No full textRuth KundratsImmigration I.D. Card juaranteeing passge aboard the passenger ship the 'Samaria"4.0 Latvian Immigration Into Canad
Des données numériques aux connaissances pluridisciplinaires : enjeux de documentation et de formalisation
No full textContributeurs : Violette Abergel, Pierre Arese, Florent Comte, Iwona Dudek, Anaïs Guillem, Antoine Gros, Kévin Réby, Livio De Luca, Aurore Pfitzmann, Pascal Bénistant //Author contributions : Conceptualization: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Data curation: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Formal analysis: ; Funding acquisition: L.D.L.; Investigation: ; Methodology: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Project administration: L.D.L., A.P.; Resources: P.B.; Software: ; Supervision: L.D.L.; Validation: L.D.L.; Visualization: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Writing – original draft: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Writing – review & editing: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.International audiencePrésentation des procédés de gestion et de structuration des données acquises lors du Chantier Scientifique de Notre-Dame de Pari
Des données numériques aux connaissances pluridisciplinaires : enjeux de documentation et de formalisation
No full textContributeurs : Violette Abergel, Pierre Arese, Florent Comte, Iwona Dudek, Anaïs Guillem, Antoine Gros, Kévin Réby, Livio De Luca, Aurore Pfitzmann, Pascal Bénistant //Author contributions : Conceptualization: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Data curation: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Formal analysis: ; Funding acquisition: L.D.L.; Investigation: ; Methodology: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Project administration: L.D.L., A.P.; Resources: P.B.; Software: ; Supervision: L.D.L.; Validation: L.D.L.; Visualization: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Writing – original draft: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.; Writing – review & editing: V.A., P.A., F.C., I.D., A.Gu., A.Gr., K.R.International audiencePrésentation des procédés de gestion et de structuration des données acquises lors du Chantier Scientifique de Notre-Dame de Pari
Maximum likelihood amplitude scale estimation for quantization-based watermarking in the presence of Dither
No full textQuantization-based watermarking schemes comprise a class of watermarking schemes that achieves the channel capacity in terms of additive noise attacks.1 The existence of good high dimensional lattices that can be efficiently implemented2–4 and incorporated into watermarking structures, made quantization-based watermarking schemes of practical interest. Because of the structure of the lattices, watermarking schemes making use of them are vulnerable to non-additive operations, like amplitude scaling in combination with additive noise. In this paper, we propose a secure Maximum Likelihood (ML) estimation technique for amplitude scaling factors using subtractive dither. The dither has mainly security purposes and is assumed to be known to the watermark encoder and decoder. We derive the probability density function (PDF) models of the watermarked and attacked data in the presence of subtractive dither. The derivation of these models follows the lines of,5 where we derived the PDF models in the absence of dither. We derive conditions for the dither sequence statistics such that a given security level is achieved using the error probability of the watermarking system as objective function. Based on these conditions we are able to make approximations to the PDF models that are used in the ML estimation procedure. Finally, experiments are performed with real audio and speech signals showing the good performance of the proposed estimation technique under realistic conditions.Electronic InstrumentationElectrical Engineering, Mathematics and Computer Scienc
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