5 Pezzi facili. Cantiere Milano, avanzamento lavori

stato della trasformazione urbana di Milano e area metropolitan

An Exemplary Case Study of Post-WWII Reconstruction in Milan

The paper deals with the use of proportional systems in architecture applied to the case study of the “modern” reconstruction of a fifteenth-century cloister heavily damaged during the Second World War bombing in Milan. First detailed analysis of the regulating lines underlying the typical vault spans of the four cloisters composing the architectural complex is carried out. Afterward, a thorough comparison is conducted of the proportional relation of the new span of the reconstruction designed by the rationalist architects Ignazio Gardella and Giovanni Romano in order to emphasize the role of the span as a proportional system that becomes the base “module” of the project. Finally, the correlation between geometrical proportions and structural conception is investigated, highlighting the differences between the existing masonry structures with a cross-vault arch system and reinforced concrete structural frames of the new intervention

MODEL TO DESIGN AND BUILD: THE AIRPLANES HANGARS OF PIER LUIGI NERVI

Between 1935 and 1942 Pier Luigi Nervi designed and built different hangars made by reinforced concrete that were very important structures from both architectural and engineering point of view. In detail, 8 different structures were created divided into two different typologies. The research presented in the paper is enclosed in the framework of the exhibition entitled "Pier Luigi Nervi, il modello come strumento di progetto e costruzione" that gathers researches from Università degli Studi di Bologna, Università di Roma Tor Vergata e Politecnico di Milano. In the paper the principal aim is comparing experiences in structural and architectural design about the “model” as representation issue in the architectural design process. Furthermore, the exhibition itself was used as a starting point for a general discussion about the meaning of the logical passage that leads engineers and architects from physical scaled to numerical structural models. The Politecnico di Milano contributed to re-writing the first experiences of collaboration between Nervi and Danusso in the creation of scaled models, used as a support for structural design. Indeed, scale models were widely used in the past for the understanding of the structural behaviour of complex structures. Unfortunately, many of these masterpieces have been destroyed over the years (as happened to the two original models that were used in the past in the study of hangars and that have been faithfully reproduced in the exhibition). In the final part of the paper the structural behaviour of the two types of hangars is discussed, underlining all the principal strengths and weaknesses of these complex structures

Power Boosting and Compensation During OTA Testing of a Real 4G LTE Base Station in Reverberation Chamber

A fully operational 4G long-term evolution (LTE) base station is tested in a reverberation chamber to analyze its performance in the presence of a multipath environment, typical of wireless and vehicular communications. Transmission quality parameters are measured ranging from the empty chamber situation (very rich multipath channel) to a very high loading condition to mitigate multipath. In that way, both outdoor and indoor propagation are accounted for. A large attenuation is inserted between the transmitter and the antenna to reduce the signal received by the user to real-life values encountered in both outdoor and indoor environments. In these scenarios, operators may choose to transmit a constant power spectral density throughout all LTE spectrum, or to increase the energy of control channels at the expense of data channels in order to enforce transmission and provide better quality to the user, especially in poor radio conditions. This is called “power boosting,” and its effect is analyzed in this paper

Reverberation chambers for testing LTE wireless communication systems

Reverberation chambers are successfully adopted to test last generation wireless communication systems. The aim is the replication of realistic propagation condition in outdoor and indoor situations where the multipath contribution statistically overlaps to the direct path between the base station and the user terminal. The insertion of quantified absorbing materials allows to tune the power delay profile, the Rician K-factor, and the coherence bandwidth according to real life situations

Reverberation chambers for testing wireless devices and systems

Testing of wireless devices and systems is becoming increasingly important in the technological development of Long Term Evolution (LTE) and 5G mobile networks. Both mobile and base station manufacturers are interested in assessing system performance and user perceived quality in realistic propagation environments, including indoor and outdoor conditions. Real-life electromagnetic environments exhibit rich multipath propagation and a strong attenuation of the wireless signal over the propagation channel. Emulating those conditions in anechoic chambers requires the careful arrangement of many interference sources in multiple configurations, which leads to complex and time-consuming measurements. The reverberation chamber (RC) is a metallic cavity where the signal created by a single source is reflected and diffused to create multipath fading. This paper gives an overview of how an RC can be tuned to emulate channel parameters, e.g., power delay profile, time delay spread, coherence bandwidth and Rician K-factor, of real-life environments The addition of absorbing material inside the RC allows for varying those parameters, thus recreating line of sight and imperfect propagation conditions experienced by the user equipment (UE). Compliant electromagnetic compatibility downlink and uplink tests are shown for selected MIMO configurations as well as for Internet of Things devices. The tests are carried out using a commercial base station connected to the live national mobile network of a mobile operator. Evaluated network parameters are throughput, signal to noise ratio, modulation schemes and other settings of both the base station and of the UE to assess the quality of the digital communication