Il Nuovo Cimento C

A numerical model is proposed to describe the transient behaviour of a porous bed thermal accumulator. Attention has been focused on power production applications where minimum entropy generation in the charge process has to be considered a leading design criterium. The model is solved and the influence of various design parameters on the performances of the storage system are analysed.

Diffusion rates during calm conditions have been determined in dependence of stability. Similarity laws in an unstable and neutral atmosphere can be applied to calms provided the wind velocityu is substituted by the «critical» wind velocityu c which defines the onest of a calm. For a stable stratification vertical diffusion rates may be estimated by means ofP-G curves and the same procedure was applied to the horizontal diffusion as well.

The mechanism of sediment transport in the shallow water of lagoons is discussed. If capable to lift up the sediments, the tidal currents are shown to tend to fill up the lagoon. The main mechanism for sediment suspension is found in wind waves, caused by intermittent strong winds. Tidal current acts then as a carrier. This argument is discussed both theoretically and on the basis of experimental data.

This rapporteur paper discusses some achievements in the understanding of cosmic-ray solar modulation with ground-based observations presented at the XXIV International Cosmic Ray Conference.

In this paper the main scientific activities, over 20 years, of our group at Mt. Blanc Laboratory are described on the basis of three experiments: SCE (Spark Chamber Experiment), NUSEX (Nucleon Stability Experiment) and LSD (Liquid Scintillation Detector). A first noteworthy step to the muon physics deep underground has been done by SCE in the 70's, while at the present time a very important impact is given by NUSEX and LSD experiments, now fully running, playing a heavy role both on the elementary particle and astrophysics research. The results of these experiments are discussed focusing expecially on the physics of muons of atmospheric origin and of those locally originated at Mt. Blanc Laboratory, 5000 m w.e. deep underground.

In a model solar dwelling described elsewhere, the temperature of the interior is controlled with the objective of making that temperature as nearly constant as possible simply by controlling the heat conductance between the heat-storing walls and the interior. This discussion examines the production of entropy in such a system, and how that entropy production is affected by how the control is used. The problem is described by three unknown functions, governed by a system of two nonlinear differential equations plus a variational equation. The functioning of the control appears as a modification of the entropy production and can be measured by an entropy-efficiency defined here. The system analyses the geophysical periodic inputs, solar radiation and terrestrial temperature, by a set of control bits to which belongs a welldefined entropy profile.

The solar contribution to space heating and cooling is evaluated through an analytical procedure. The method used simulates the building as a thermal network in which each node corresponds to the centre of a room and each mesh arm to a wall; building materials and frames are explicitly taken into account. The network is excited by a set of generators corresponding to external excitations (e.g. environmental temperature, solar flux, etc.) which are described by a truncated Fourier series. The network is resolved by an analytical method through the matrix formalism and gives either the time diagrams of indoor temperatures in each room, or the diagrams of the auxiliary energy required to maintain a set room temperature. The application to a residential environment is presented as an example and is discussed in relation to a passive retrofitting design. The results are briefly compared with those obtained through established procedures, to give evidence of the occurrence of strong fluctuations on the average values which significantly influence the conditions of comfort. The method can be implemented at the level of microcomputers.