Forces, moment and wave pattern for surface combatant in regular head wavesPart II. Measurement results and discussions

Unsteady resistance, heave force, pitch moment and free-surface elevations for DTMB 5512 at steady forward speed and in regular head waves are investigated with different measurement systems for a fairly wide range of test conditions in the IIHR towing tank. Test data are procured for validation of Reynolds-averaged Navier–Stokes computational fluid dynamics codes and for understanding the physics of unsteady ship hydrodynamics. The second part of the paper presents the measurement results and discussions. Received: 4 October 2000 / Accepted: 23 April 2001 Published online: 29 November 2001     

Grain shear flow in a rotating drum

 In the present paper we report on the experimental activities carried out on a rotating drum partially filled with grains or glass beads. The experiments give information about rheology through velocity profiles and through the velocity covariance tensor structure. We used a LDV system to measure the velocity of the grains at several points along three vertical sections. The data were also used to obtain the grain volume concentration, with encouraging results. Instantaneous velocity data were elaborated in order to obtain velocity and pseudotemperature profiles for all the experiments; for a subset of the experiments a large set of data were elaborated to obtain the velocity covariance. The velocity covariance is not collinear with the rate of deformation tensor. An attempt to justify the rotation of the tensor axes as a consequence of the kinetically induced anisotropy and of some free surface perturbations slowly moving upstream was partially successful. Received: 23 April 1999 / Accepted: 15 July 2001     

A New Recurrence Relation and Related Determinantal form for Binomial Type Polynomial Sequences

For polynomial sequence of binomial type we propose a new recurrence formula equivalent to a determinantal form of the sequence, from which known and unknown properties are deducted. Relationships whit \({\delta}\)–functionals, \({\delta}\)–operators and generating function are pointed out. Finally, some classical examples are studied, highlighting interesting determinantal identities.     

Theoretical studies on microscopic and macroscopic nonuniformities in electric-discharge-excited XeCl lasers

The satbilit r of the pumping discharge for XeCI (Ne/Xe/HCI) lasers is investigated by using different one-dimensional models, considering both bulk discharge instabilities and filamentary ones. It is found that the bulk stability in a XeCl laser discharge can he improved, under certain conditions, due to the vihrational excitation of HCl molecules: this effect is studied by using different models for the HCl vihrational kinetics. It is established that the very short instability time found in experiments cannot he explained as a result of hulk instability of the discharge. On the other hand, a satisfactory comparison with experiments can he obtained by adding to the model a simplified microinstability which develops in the discharge.     

Determination of N-acetylcysteine in human plasma by gas chromatography-mass spectrometry

An automatic mass spectrometric method for the quantitation of N-acetylcysteine (NAC) in human plasma has been developed. NAC was extracted from plasma with ethyl acetate and derivatized in two steps with 2-propanol and pentafluoropropionic anhydride. The volatile derivative obtained was ideal for gas chromatographic-mass spectrometric analysis. Data obtained by analysing the plasma of healthy volunteers to whom 600 mg of NAC had been orally given are reported.     

On perturbed derivations of C1 algebras

Given a C¹ algebra $\text{U}$, the generator of a group of automorphisms δ, and a derivation D, we examine some situations in which δ+λD is a generator for small real λ.     

A density-functional study of the structures, binding energies and total spins of Ni-Fe clusters using nonlocal norm-conserving pseudopotentials and the generalized gradient approximation

We report ab initio calculations of the structures, binding energies, and total spins of the clusters Ni(13), Ni(19), Ni(23), Ni(26), Ni(12)Fe, Ni(11)Fe(2), Ni(18)Fe, Ni(17)Fe(2), Ni(22)Fe, Ni(20)Fe(3), and Ni(25)Fe using a density-functional method that employs linear combination of atomic orbitals as basis sets, nonlocal norm-conserving pseudopotentials, and the generalized gradient approximation for exchange and correlation. Our results show that the Fe-doped Ni clusters, which have icosahedral or polyicosahedral ground-state structures similar to those of the corresponding pure Ni clusters, are most stable with the Fe atoms occupying internal positions, as has also been inferred from experimental results on the adsorption of molecular nitrogen on the cluster surfaces. We also rule out the possibility that the experimentally observed difference between the (nonpolyicosahedral) configurations of N(2)-saturated Ni(26) and N(2)-saturated Ni(25)Fe be due to the influence of the Fe atom on the energy of the underlying metal cluster.