Experimental calculation of the damping ratio in buildings hosting permanent GPS stations during the recent Italian earthquakes

During the recent earthquakes in Italy, the contemporary presence of about 40 permanent GPS and 40 accelerometric stations of the national seismic network made it possible to estimate the value of the damping ratio of the buildings hosting the GPS stations. This value was calculated as the minimum of a function (parabola) constructed step by step from the relations between the ordinates of the pseudo-acceleration spectra extracted from the GPS and accelerometric measurements. For both construction material and building geometry, the results indicate values that differ by at least two percentage points from the values imposed by the technical regulations

Building resilient and innovative business models in the era of Covid-19: a process approach

The role that the Business Model (BM) concept and BM-related tools may play during times of crisis have been insufficiently investigated. This paper presents a process aimed at supporting companies in building resilient and original BMs through continuous innovation based on the existing BM literature. The present study highlights the role that BM tools may play during crisis situations, providing managers and entrepreneurs with an alert system (i.e., BM measurements) capable of signaling when a change should be implemented; a “library” of potential changes (i.e., BM pivots) to be generated in the BM; and a portfolio of potential available options when considering how the BM should be changed (i.e., BM configurations). The paper additionally highlights how tools for BM mapping, control, and innovation can provide one another with information and can be connected in a way that allows companies to achieve a synergetic effect in the face of instability and uncertainty

Relation between dynamic amplification, structural height and damage in buildings affected by the recent Italian earthquakes

To exploit the purely geometric link between the elastic period of vibration T and the height H (or number of stories) of a building, T was varied from 0 to 0.5 s coinciding with a height between 0 and 12 m (at most the four stories typical of Italian buildings) in order to estimate the spectral accelerations corresponding to acceleration measurements recorded during the earthquakes of L'Aquila, Emilia and central Italy. These estimates were used to calculate the maximum dynamic amplification factors and corresponding heights, called critical heights, that can generate either resonance or appreciable dynamic amplification values. The results showed dynamic amplification values close to 3 for reinforced concrete buildings and 2.5 for masonry buildings independently of the characteristics of the earthquakes. There was a significant coincidence between the structural height of the buildings with greatest recorded damage and the critical height. The basis of the study lies in simple numerical steps carried out with easily obtainable data: for this reason, it can be easily applied to determine the vulnerability of a building according to its structural height

Truthful Learning Mechanisms for Multi-Slot Sponsored Search Auctions with Externalities

Sponsored search auctions constitute one of the most successful applications of microeconomic mechanisms. In mechanism design, auctions are usually designed to incentivize advertisers to bid their truthful valuations and to assure both the advertisers and the auctioneer a non-negative utility. Nonetheless, in sponsored search auctions, the click-through-rates (CTRs) of the advertisers are often unknown to the auctioneer and thus standard truthful mechanisms cannot be directly applied and must be paired with an effective learning algorithm for the estimation of the CTRs. This introduces the critical problem of designing a learning mechanism able to estimate the CTRs at the same time as implementing a truthful mechanism with a revenue loss as small as possible compared to an optimal mechanism designed with the true CTRs. Previous work showed that, when dominant-strategy truthfulness is adopted, in single-slot auctions the problem can be solved using suitable exploration-exploitation mechanisms able to achieve a per-step regret (over the auctioneer's revenue) of order $O(T^{-1/3})$ (where T is the number of times the auction is repeated). It is also known that, when truthfulness in expectation is adopted, a per-step regret (over the social welfare) of order $O(T^{-1/2})$ can be obtained. In this paper we extend the results known in the literature to the case of multi-slot auctions. In this case, a model of the user is needed to characterize how the advertisers' valuations change over the slots. We adopt the cascade model that is the most famous model in the literature for sponsored search auctions. We prove a number of novel upper bounds and lower bounds both on the auctioneer's revenue loss and social welfare w.r.t. to the VCG auction and we report numerical simulations investigating the accuracy of the bounds in predicting the dependency of the regret on the auction parameters