Filtyp
We present an analytical model of the relation between the surface density of gas and star formation rate in galaxies and clouds, as a function of the presence of supersonic turbulence and the associated structure of the interstellar medium (ISM). The model predicts a power-law relation of index 3/2, flattened under the effects of stellar feedback at high densities or in very turbulent media, and
The latest version of the Swiss standard for building acoustics (SIA181) introduced a new measurement method, based on a balanced- Arm hammer, for evaluating the decoupling performance of service equipment. This method was developed for reproducing in a standard manner the manipulation of service equipment in bathrooms and kitchens. In this study, we are investigating the relevance of such method
Long tails and streams of stars are the most noticeable traces of galaxy collisions. However, their tidal origin was recognized only less than 50 years ago and more than 10 years after their first observations. This review describes how the idea of galactic tides has emerged thanks to advances in numerical simulations, from the first simulations that included tens of particles to the most sophisti
We present smoothed particle hydrodynamic models of the interactions in the compact galaxy group, Stephan's Quintet. Adding thermohydrodynamic effects to the earlier collisionless N-body simulations of Renaud et al., we further investigate the dynamical interaction history and evolution of the intergalactic gas of Stephan's Quintet. Specifically, we reproduce the major stellar and gas features of
Soundscape management in a city implies mitigating harmful sounds and promoting useful ones, according to their environmental, social or cultural significance and considering a more human centered paradigm. The Soundscape approach does not consider sound as a waste but a resource and its application may reach more benefits than solely noise control actions. This conception conveys an emerging para
Gravitational tides are widely understood to strip and destroy galactic substructures. In the course of a galaxy merger, however, transient totally compressive tides may develop and prevent star-forming regions from dissolving after they condensed to form clusters of stars. We study the statistics of such compressive modes in an N-body model of the galaxy merger NGC 4038/39 (the Antennae) and show
The latest edition of the Swiss standard SIA181(2006) Protection against noise in Buildings [1], introduces a new methodology regarding the tests to be performed in new constructions for noise induced by human using service equipment in bathroom and kitchen. In this method, a specific pendling hammer has been developed especially for evaluating the decoupling efficiency of service equipment. The g
Many multifamily houses are produced by small or medium size enterprises (SME's). These developers produce a substantial number of residential units per year. They have normally limited resources and need to have easy access to cost - effective structural solutions. Typical buildings comprise two storeys and four to eight flats. Due to costs and production efficiency these buildings are produced i
The latest Swiss standard SIA181 (6-2006 edition [1]) introduces a new methodology regarding the tests to be performed in new constructions for assessing noise induced by the manipulation of service equipment in bathrooms and kitchens. However, this method has been developed especially for massive constructions. In this study, we are investigating the relevance of such method for timber frame buil
Various modal methods are frequently used to investigate the vibration pattern in construction elements of a building in the low frequency range. The experimental determination of time average transmission and reflection coefficient has been developed for the large scale building structures. In this study, we investigate a mock up of a wall/floor junction. The wave approach is combined with the co
Acoustically robust light weight constructions in multifamily houses require that the building processes are taken into account, i.e. it is necessary to describe in detail how to erect the house on site in order to fulfill the final result. Performance of details necessary for stability reasons, connections in joints, fixing of final strips etc have to be described clearly in order to achieve the
MAX-lab is a national laboratory operated jointly by the Swedish Research Council and Lund University. As of today, the MAX project consists of three facilities, (three storage rings): MAX-I, MAX-II, MAX-III and one electron pre-accelerator called MAX-Injector. A new storage ring is needed at the benefit of material science, such as nanotechnology. MAX-IV will be 100 times more efficient than exis
In Sweden a new research project started in December 2009. The project focuses on light weight constructions and its sound insulation characteristics with respect to subjective response, and it will be carried out during the period of December 2009 to December 2012. The main goal is to develop new evaluation criteria proposals, for the low frequency range and vibrations and their mutual interactio
Lightweight constructions of timber material are cost effective and demands relatively short production duration. One of the main drawbacks of lightweight structures, however, is related to the sound transmission. More and more complains arise against this type of structures, related to the propagation of low frequency vibrations induced by human activities. Most problems are caused by human walki
Each person has a very individual way of walking, though persons having the same sex and the same height, weight and age are likely to have similarities in the angle of the feet and the length of the stride. To simulate this, a number of Markov chains, that describe the stride, were created from experiments with 150 different males. The Markov chains were then used to create an artificial person f
Timber floors receive a lot of attention nowadays because of their advantages, such as cost effectiveness, recyclability. On the other hand, more and more complains arise again this type of structures, related to the propagation of low frequency vibrations induced by human activities. Most problems are caused by human walking, more exactly foot impacts, which generate a harmonic force whose freque
Multitone signals are often used as excitation for the characterization of audio systems. The frequency spectrum of the response consists of harmonics of the frequencies contained in the excitation and intermodulation products. Beside the choice of frequencies, in order to avoid frequency overlapping, there is also the need to choose adequate magnitudes and phases for the different components that
