Design of the Prototypical Cryomodule for the EUROTRANS Superconducting Linac for Nuclear Waste Transmutation

International audienceOne task of the accelerator workpackage of the EUROTRANS program for the design of a nuclear waste transmutation system is dedicated to the engineering and realization of a prototype cryomodule of the high energy section of the linac, equipped with elliptical superconducting niobium cavities. We review here the present status of the design and the planned program that foresees the experimental characterization of the fully equipped cavity and RF system under its nominal operating conditions

Symmetrization Procedure for Structure-Fluid Cavity System Involving Pseudostatic Correction

International audienceThis paper deals with a pressure-displacement formulation based on the finite-element method of an elastoacoustic coupling problem. Since directly solving the resulting system isCPU intensive for large models, the solution is usually based on only a few uncoupled structural modes in vacuum and rigid cavity modes. However this classical pressuredisplacement formulation leads to nonsymmetric eigenvalue problems. Furthermore, if this method is accurate for weak coupling models, significant errors occur when the truncated modes are coupled to the ones used in the analysis. The present paper suggests a method combining the pseudostatic correction of the truncated modes in modal analysis with a symmetrization technique of the eigenvalue problems. It allows the calculation of the real coupled modes and frequencies, as well as the computation of an accurate elastoacoustic response, even for the strong coupling of a structure with a heavy fluid (liquid). It is less CPU expensive than the classical method, because it leads to a diagonalized system

SPH and ALE Formulations for Fluid Structure Coupling

Simulation of Fluid Structure Interaction FSI, problems becomes more and more the focus of computational engineering, where FEM (Finite element Methods) for structural mechanics and Finite Volume for CFD are dominant. New formulations have been developed for FSI applications using mesh free methods as SPH method, (Smooth Particle Hydrodynamic). Up to these days very little has been done to compare different methods and assess which one would be more suitable. For small deformation, FEM Lagrangian formulation can solve structure interface and material boundary accurately; the main limitation of the formulation is high mesh distortion for large deformation and moving structure. One of the commonly used approach to solve these problems is the ALE formulation which has been used with success in the simulation of fluid structure interaction with large structure motion such as sloshing fuel tank in automotive industry and bird impact in aeronautic industry. For some applications, including bird impact and high velocity impact problems, engineers have switched from ALE to SPH method to reduce CPU time and save memory allocation. In this paper the mathematical and numerical implementation of the ALE and SPH formulations are described. From different simulation, it has been observed that for the SPH method to provide similar results as ALE or Lagrangian formulations, the SPH meshing, or SPH spacing particles needs to be finer than the ALE mesh. To validate the statement, we perform a simulation of a shock wave propagation generated by explosive detonation. For this simple problem, the particle spacing of SPH method needs to be at least two times finer than ALE mesh. A contact algorithm is performed at the fluid structure interface for both SPH and ALE formulations

Lagrangian and ALE Formulations For Soil Structure Coupling with Explosive Detonation

Simulation of Soil-Structure Interaction becomes more and more the focus of computational engineering in civil and mechanical engineering, where FEM (Finite element Methods) for soil and structural mechanics and Finite Volume for CFD (Computational Fluid Dynamics) are dominant. New advanced formulations have been developed for FSI (Fluid Structure Interaction) applications using ALE (Arbitrary Lagrangian Eulerian), mesh free and SPH (Smooth Particle Hydrodynamic) methods. In defence industry, engineers have been developing protection systems for many years to reduce the vulnerability of light armoured vehicles (LAV) against mine blast using classical Lagrangian FEM methods. To improve simulations and assist in the development of these protections, experimental tests and new numerical techniques are performed. Initial conditions such as the loading prescribed by a mine on a structure should be simulated adequately in order to conduct these numerical calculations. The effects of blast on structures often depend on how the initial conditions are estimated and applied. This article uses two methods to simulate a mine blast, namely the classical Lagrangian as well as the ALE formulations. The comparison was carried out for a simple and also a more complex target. Particle methods as SPH method can also be used for soil structure interaction

Evaluating synergy between marbofloxacin and gentamicin in Pseudomonas aeruginosa strains isolated from dogs with otitis externa

The aim of this study was to determine antimicrobial susceptibility of Pseudomonas aeruginosa strains to marbofloxacin and gentamicin, and investigate the possible synergistic, additive, indifferent or antagonistic effects between the two agents. P. aeruginosa strains can develop resistance quickly against certain antibiotics if used alone, thus the need emerges to find synergistic combinations. A total of 68 P. aeruginosa strains isolated from dogs were examined. In order to describe interactions between marbofloxacin and gentamicin the checkerboard microdilution method was utilized. The MICs (minimum inhibitory concentrations) for marbofloxacin and gentamicin were in the range 0.25–64 mg/L and 0.25–32 mg/L, respectively. The combination of marbofloxacin and gentamicin was more effective with a MIC range of 0.031–8 mg/L and a MIC90 of 1 mg/L, compared to 16 mg/L for marbofloxacin alone and 8 mg/L for gentamicin alone. The FIC (fractional inhibitory concentration) indices ranged from 0.0945 (pronounced synergy) to 1.0625 (indifference). Synergy between marbofloxacin and gentamicin was found in 33 isolates. The mean FIC index is 0.546, which represents a partial synergistic/additive effect close to the full synergy threshold. In vitro results indicate that marbofloxacin and gentamicin as partially synergistic agents may prove clinically useful in combination therapy against P. aeruginosa infections. Although marbofloxacin is not used in the human practice, the interactions between fluoroquinolones and aminoglycosides may have importance outside the veterinary field

Deployment of a Neo-Hookean membrane: experimental and numerical analysis

The aim of this research is to assess the response of a thin membrane subjected to high-pressure gas loading for inflation. This procedure is applied during the design process of the membrane structure to allow the product to resist high-pressure loading and to further characterize the hyper-elastic material. The simulation in this work considers the standard procedures used in the LS-DYNA software, which applies such assumptions as a uniform airbag pressure and temperature in addition to a more recently developed procedure that takes into account the fluid-structure interaction between the inflation gas source and the hyper-elastic membrane; this approach is referred to as the Arbitrary Lagrangian Eulerian (ALE) formulation. Until recently, to simulate the inflation of the hyperelastic membrane, a uniform pressure based on a thermodynamic model or experimental test has been applied to the structure as the boundary conditions. To conserve CPU time, this work combines both methods; the fluid structure coupling method is used at an earlier stage in which the fluid is modeled using full hydrodynamic equations, and at the later stage, the uniform pressure procedure is applied, and the fluid mesh and analysis are removed from the computation. Both simulations were compared to test data, indicating satisfactory correlation with the more recently developed procedure, the ALE theory, which showed the greatest accuracy both in terms of graphical and schematic comparison, particularly in the early stages of the inflation process. As a result, the new simulation procedure model can be applied to research on the effects of design changes in the new membrane

Fungitoxicity of some fungicides against to pathogens responsible of olive trees decline in the Chebika’s area in Tunisia

The incidence of the disease seems very important on young trees and tends to bemoderate with the aging of the tree. In fact, olive trees have a shallow root system and arestill vulnerable to pathogens especially the irrigated varieties. Chemical and biological control against Fusarium solani, Fusarium oxysporum, Rhizoctonia solani and Verticillium dahliae have revealed that the application in vitro of Prodazim and of Methyl-thiophanatehave showed a very good efficacy up to 100%. Ridomil and Tachigaren have indicated aregular efficiency, while the two bio-fungicides Fungstop and the compost juice havedemonstrated a low efficiency. The two bio-control agents Trichoderma harzianum and Gliocladium virens have showed a relatively high effectiveness in vitro. In vivo, obtainedresults have revealed that the nature of the product, the doses applied and the condition ofthe olive trees are highly correlated factors. The treatment doesn’t appear to have apositive effect on the beginning of stage 1 and on plots presented a good structured soil.Going beyond this stage, whatever the product and the doses used, the attack isirreversible

Morphological and Biological Characterization of Monosporascus cannonballus isolates, responsible of watermelon decline in Kairouan's area

Watermelon grown in Kairouan's region is infected by vine decline disease caused by M. cannonballus. In vitro tests showed that this pathogen produces perithecia with a diameter of 495 μm releasing ascospores with a diameter of 44 μm. The mycelium is very fine, rarely visible in the media KOMADA and TANAKA. The colony of different isolates on substrate culture such as Malt, MS and S, appears very dense. On PDA, the grayish brown color characteristic of this ascomycete was observed. The perithecia production in vitro test for this fungus requires relatively long period of incubation (45 days). The effect of culture media showed that the PDA, MS and Malt are the best for the mycelia development of M. cannonballus. The most favorable culture media for fructification arein descending order MS, S, PDA, Malt. M. cannonballus isolates tested in this study showed an optimum temperature of mycelial growth and reproduction of 30°C. MT15 andMT12 isolates originated from Chebika (Kairouan government) showed a significantmycelial growth at all temperatures of incubation. MT7 and MT14 isolates from the sameregion were the most fertile. The results of pH effect on M. cannonballus developmenthave revealed that the maximum mycelial growth occurred at pH 6 for most of isolates andfor the fructification occurred at pH 4 and pH 8. For the osmotic pression with the addition of NaCl and KCl, the optimal development for majority of isolates is registeredat -0.5 MPa and -2 MPa, with a minimum at -4MPa. The inhibition of the fructification of the M. cannonballus isolates occurred beyond -2MPa

Changes in the composition and fatty acid profile of Najdi ewes’ milk before and after weaning

This trial aimed to study the changes in the yield, composition, and fatty acid (FA) profile of ewes’ milk during suckling and milking periods. Nineteen multiparous Najdi ewes were kept under identical management and feeding conditions during a 12-week trial that was divided into two periods. Milk samples were collected on each sampling day from the total yield during the suckling (3rd, 6th, and 9th week) and milking (12th week) periods. The milk yield and the total solids, fat, protein, and lactose contents of the milk remained constant throughout the suckling weeks, but the protein content increased and milk yield and lactose content decreased after weaning. There were no differences in milk saturated FA (SFA), unsaturated FA (UFA), and monounsaturated FA (MUFA) contents during the suckling and milking periods, whereas the polyunsaturated FA content increased during the milking period. There were no differences in the individual milk SFA during the weeks of suckling, but the contents of caproic acid (C6:0), caprylic acid (C8:0), margaric acid (C17:0), and stearic acid (C18:0) decreased. However, myristic acid (C14:0), lauric acid (C12:0), and isomers of pentadecanoic (C15:0) acid increased during the milking period. The percentage of vaccenic acid (C18:1△11t), rumenic acid (C18:2△9c,11t; conjugated linoleic acid (CLA)), ω-3 FA group, and the atherogenicity index did not differ during the suckling period, but increased after weaning in the 12th week of lactation. This study demonstrated that weaning lambs in Najdi ewes is probably a factor that strongly affects milk traits by changing yield, composition, and FA profile.Keywords: CLA, dairy ewes, milk fat, milk yield, stage of lactatio

Screening of fungi implicated in the dieback of olive trees (Olea europea) in Chebika’s area

Several surveys were conducted during spring 2008 in Chebika’s area in Tunisia. Samples were collected from infected plants showed different types of symptoms and they have been the subject of mycological analysis. The morphological identification of fungal colonies isolated from roots, crown and stems of two olive varieties Koroneiki and Chemlali Sfax, revealed the presence of a fungi complex including Fusarium oxysporum, Fusarium solani, Rhizoctonia solani, Verticillium dahliae, Cladosporium fulvum, Alternaria solani, Alternaria tenuis, Bispora punctata. and Cylindrocarpon .sp; Although,those fungi Fusarium oxysporum, Fusarium solani, Rhizoctonia solani and Verticillium dahliae are ubiquitous and the predominant one. Pathogenicity results revealed that the fungi isolated from olive trees exhibited typical symptoms on Koroneiki variety incontrolled conditions