Data completion via an energy error functional

We propose, in this Note, a new procedure for data completion based on the minimization of an energy like error functional. The efficiency of the proposed method is illustrated by a thermostatic application. To cite this article: S. Andrieux et al., C. R. Mecanique 333 (2005).     

H(2)-Broadening Coefficients in the nu(4) Band of NH(3)

H(2)-broadening coefficients have been measured for 66 rovibrational lines of NH(3) at room temperature in the (P)P and (R)P branches of the nu(4) band in the range 1470-1600 cm(-1), using a high-resolution Fourier transform spectrometer. The collisional widths are obtained by fitting Voigt profiles to the measured shapes of the lines. The broadening coefficients are found to decrease on the whole as J increases and they increase with K for a given J value. The results are compared with those calculated from a semiclassical model in which the inversion vibration of NH(3) and collision-induced transitions with DeltaK = 0 and DeltaK = +/- 3 are taken into account. The intermolecular potential used includes electrostatic, induction, and dispersion energy contributions. The calculations performed by considering only DeltaK = 0 transitions provide significantly lower broadenings but with a satisfactory J and K dependence. The same trends are obtained for the broadening coefficients in inversion-rotation transitions and in the Q branch of the nu(1) parallel band of NH(3). Copyright 2001 Academic Press.     

Flow characteristics of an underexpanded jet and its application to the study of droplet breakup

The jet from an axiymmetric convergent nozzle has been investigated at pressure ratios of 1.9 and 3.6 corresponding to exit Mach numbers of unity and 1.49. Velocity characteristics were measured with a laser-Doppler velocimeter and complemented by shadography which showed the structure of the expansion-compression waves. The sinuous longitudinal variations of the axial velocity are shown to be large at the higher pressure ratio with amplitudes which decreased with increasing distance from the jet exit and from the axis. The use of the jet for the quantification of droplet breakup is considered and it is evident that the higher pressure ratio requires careful consideration of the location at which a droplet is allowed to fall into the jet.Financial support from the Ministry of Defence under agreement 2037/001/CBDE is gratefully acknowledged.     

Sound transmission through laminated composite cylindrical shells using analytical model

Composite structures are often used in aircraft because of advantages offered by a high strength to weight ratio. Sound transmission through an infinite laminated composite cylindrical shell is studied in the context of the transmission of airborne sound into aircraft interior. The shell is immersed in an external fluid medium and contains an internal fluid, and airflow in an external fluid medium moves with a constant velocity. The different parameters were used to see how laminate specification affected noise transmission. An exact solution is obtained by solving the vibration equation of laminated composite shell and acoustic wave equations simultaneously. Transmission losses (TLs) obtained from numerical solution are compared with those of other authors. The effects of different source condition, structural properties and flight conditions on TL are studied for a range of values, especially, incident angle of the plane wave, Mach number and flight altitude of aircraft, stack sequences, angle of warp and damping.     

Analytic solutions to a strongly nonlinear Vlasov equation

We prove the existence for short times of analytic solutions to a Vlasov type equation. The corresponding model is one-dimensional but uses a quite singular force term which involves a full derivative in x of the macroscopic density, making the existence of solutions a difficult question.     

Generalized Modal Scattering Matrix of Bandpass Filters Using Ridged Waveguides

Simple and accurate integral equation formulation using a three dimensional finite element (3DFEM) to determine the propagation of microwave passive structures is presented. This technique is applied to solve the scattering problems due to various forms of irises in lossless rectangular waveguide.The analysis of these components is highly dependent of the numbers of modes considered in the neighbourhood of the discontinuity. The theoretical model is compared with measurements and Mode Matching Method (MMM). Results are found to be good agreement.     

Synthesis and magnetic properties of new mono- and binuclear iron complexes with salicyloylhydrazono dithiolane ligand

We report here experimental evidence for the formation in the solid state of a new binuclear Fe (III) 2(mu-OMe) 2(HL) 4 complex (H 2L is 2-salicyloylhydrazono-1,3-dithiolane). The isostructural Mn (III) 2(mu-OMe) 2(HL) 4 complex has provided the strongest ferromagnetic interaction value (J approximately 20 cm (-1)) between Mn (III) ions to date. The new iron binuclear compound presented in this study shows antiferromagnetic intramolecular coupling, which agrees with the theoretical study that we previously proposed. During our synthetic work, we also observed an unexpected spontaneous reduction of the new Fe (III)(HL) 2Cl,S complex to the new Fe (II)(H 2L) 2Cl 2 high-spin mononuclear complex. This process has been checked by cyclo-voltammetry as well as pseudosteady voltammetry.     

Ultrasonication-assisted sorption of cadmium from aqueous phase by wheat bran

In the present study, the sorption of cadmium from aqueous phase by wheat bran was investigated with and without the assistance of ultrasound. Kinetic data and sorption equilibrium isotherms were carried out in batch conditions. The influence of different operating parameters such as ultrasonic power, cadmium initial concentration, sorbent mass, temperature, and the combination of ultrasound and mechanical stirring on the kinetics of cadmium removal was studied. The obtained results show that the ultrasonic irradiation significantly enhances and improves the efficiency of the removal of cadmium, especially in the combined method. The sorption kinetic data were found to be well-represented by the pseudo-second-order rate equation, both in the absence and presence of ultrasound as well as in the combined process (stirring and ultrasonication). Ultrasonic power played a key role in the removal of cadmium. Equilibrium isotherm results could be well described by the Langmuir model both with and without the assistance of ultrasound. The effect of temperature on the sorption isotherms of cadmium in the absence and presence of ultrasound has been also studied and the thermodynamic parameters DeltaG degrees, DeltaH degrees, and DeltaS degrees were determined. The monolayer sorption capacities were 51.81, 35.09, and 22.78 mg g(-1) for experiments conducted by the combined process, in the presence of ultrasound, and in passive conditions, respectively. The combination ultrasound-stirring for the sorption process was shown to be of interest for the treatment of wastewaters contaminated with cadmium.     

Optimization and characterization of electrospun chitosan/poly(vinyl alcohol) nanofibers as a phenol adsorbent via response surface methodology

Fabrication and characterization of chitosan/poly(vinyl alcohol) electrospun nanofibers for adsorption of phenol from water were investigated. The effects of voltage (15–30 kV), solution injection flow rate (0.5–1.5 ml/hr), distance of needle and collector (10–20 cm) and chitosan/poly(vinyl alcohol) ratio (25/75, 50/50, 75/25) were studied to obtain the optimum electrospinning conditions for the maximum adsorption capacity of phenol. Central composite design (CCD) was used to investigate and optimize the processing factors for production of chitosan/poly(vinyl alcohol) nanofibers from aqueous solutions. The nanofibers were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR). Uniform beadless nanofibers with the minimum diameters of 3–11 nm were obtained at chitosan/poly(vinyl alcohol) ratio of 50/50, voltage of 22.5 kV, distance of 15 cm and injection flow rate of 1.99 ml hr^?1. Fourier transform infrared spectrum of chitosan/poly(vinyl alcohol) exhibited the existence of relevant functional groups of both poly(vinyl alcohol) and chitosan in the blends. Results of CCD show that among all processing factors, rate of electrospinning will highly affect the nanofiber adsorption. The response surface quadratic order model presented correlation coefficient explaining 69.5% of the variability in the adsorption. Copyright © 2017 John Wiley & Sons, Ltd.