History of accelerator neutrino beams

Neutrino beams obtained from proton accelerators were first operated in 1962. Since then, neutrino beams have been intensively used in particle physics and evolved in many different ways. We describe the characteristics of various neutrino beams, relating them to the historical development of the physics studies and discoveries. We also discuss some of the ideas still under consideration for future neutrino beams.

     

Explicit gradient information in multiobjective optimization

This work presents an algorithm that converges to points that satisfy a first-order necessary condition of weakly Pareto solutions of multiobjective optimization problems. Hints on how to include second-order information are given. Preliminary numerical results are encouraging.     

New seven membered palladacycles: C-Br bond activation of 2-bromo-pyridine derivative by Pd(II)

C-Br bond activation followed by a C-C coupling reaction of the 2-bromo-pyridyl unit of [1-phenyl-2-(6-bromopyridin-2-yl)-benzoimidazole] was performed by Pd(CH(2)CMe(2)-o-C(6)H(4))(η(4)-COD). Two new seven membered palladacycles were obtained. A combined experimental and theoretical DFT study elucidates the mechanism for this reaction.     

A method for the low frequency qualification of reverberation test rooms using a validated finite element model

Low frequency behavior in small rooms is always a critical issue, but the recent extension of several standards to frequencies as low as 50 Hz opened an interesting debate in the scientific community as to which is the best (and most reliable) method to perform measurements. The present paper discusses the low frequency qualification of a typical reverberant test room in order to perform sound power measurements (carried out according to ISO 3741), by taking advantage of a finite element model of the room. Experimental measurements were first carried out in a standard reverberant chamber to demonstrate that the model provides accurate results in the range below 100 Hz. Statistical analysis of the results from measurements and simulations confirmed that, despite some small inaccuracies, the predicted results are in very good agreement with those measured both in terms of spectra and spatial distribution of the sound pressure level. Finally, the different steps of the low-frequency qualification of a reverberant test room are discussed. A selection procedure of the most suitable microphone positions is proposed, based on the results of the simulation, and, finally, on site measurements were carried out to validate the procedure.     

Osmotic propulsion: the osmotic motor

A model for self-propulsion of a colloidal particle--the osmotic motor--immersed in a dispersion of "bath" particles is presented. The nonequilibrium concentration of bath particles induced by a surface chemical reaction creates an osmotic pressure imbalance on the motor causing it to move. The ratio of the speed of reaction to that of diffusion governs the bath particle distribution which is employed to calculate the driving force on the motor, and from which the self-induced osmotic velocity is determined. For slow reactions, the self-propulsion is proportional to the reaction velocity. When surface reaction dominates over diffusion the osmotic velocity cannot exceed the diffusive speed of the bath particles. Implications of these features for different bath particle volume fractions and motor sizes are discussed. Theoretical predictions are compared with Brownian dynamics simulations.     

Dynamic structure of He-Ne mixtures by molecular dynamics simulation: from hydrodynamic to fast and slow sound modes

Molecular dynamics (MD) results for the dynamic structure of a He(0.77)Ne(0.23) gas mixture at two densities (15.8 and 36.1 nm(-3)) show a clear crossover from hydrodynamic modes to distinct excitations for the two species. The higher density dispension curve neatly shows high- and low-frequency branches setting on with a rather localized transition. The lower density results agree very well with existing neutron scattering data and, in particular, display hydrodynamic behavior up to k approximately 2 nm(-1), in contrast with the conclusions of previous simulation studies. A smooth transition to fast sound is shown to take place for 2相似文献   

Incomplete projection algorithms for solving the convex feasibility problem

We present a general scheme for solving the convex feasibility problem and prove its convergence under mild conditions. Unlike previous schemes no exact projections are required. Moreover, we also introduce an acceleration factor, which we denote as the factor, that seems to play a fundamental role to improve the quality of convergence. Numerical tests on systems of linear inequalities randomly generated give impressive results in a multi-processing environment. The speedup is superlinear in some cases. New acceleration techniques are proposed, but no tests are reported here. As a by-product we obtain the rather surprising result that the relaxation factor, usually confined to the interval (0,2), gives better convergence results for values outside this interval.