Search results for " Modeling"

Diffusion modeling of COVID-19 under lockdown

2021

Viral immune evasion by sequence variation is a significant barrier to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine design and coronavirus disease-2019 diffusion under lockdown are unpredictable with subsequent waves. Our group has developed a computational model rooted in physics to address this challenge, aiming to predict the fitness landscape of SARS-CoV-2 diffusion using a variant of the bidimensional Ising model (2DIMV) connected seasonally. The 2DIMV works in a closed system composed of limited interaction subjects and conditioned by only temperature changes. Markov chain Monte Carlo method shows that an increase in temperature implicates reduced virus diffusi…

Il dynamic business modelling per lo sviluppo e la prevenzione delle crisi delle piattaforme multi-sided

2021

Over the last few decades, the sharing economy diffusion has implemented continu- ous changes in business model opportunities with multi-sided platforms (MSPs). MSPs are digital exchange platforms that connect unmatched demand and supply side participants through internet technology. Success examples of such businesses are Airbnb, Amazon, Uber, and Just Eat. How- ever, in many cases, such initiatives also experience high growth followed by a rapid failure. Due to MSPs peculiar and complex characteristics, this study suggests adopt- ing the dynamic business modeling (DBM) perspective. The DBM aims to make explicit reinforcing and balancing cause-and-effect relationships among strategic re- s…

Using System Dynamics to Enhance Performance Management in Local Government: An Application to Residential Refuse Collection

2012

While some scholars have suggested that the forces of New Public Management are now in decline (Hughes, 2003), a clear success story of this reform is the use of performance measurement in the public sector for tracking the outputs and outcomes of service delivery. In fact, research has demonstrated that well-managed performance measurement systems are critical for accurately and systematically demonstrating operational accountability in governmental organizations (Rivenbark, 2007). However, we must be cautious in how we think about the use of performance measurement systems because of their two distinct parts as described by de Lancer Jules and Holzer (2001). The first part involves adopti…

Combing System Dynamics Modeling and Performance Management Systems to Frame the One Stop Shop Service: a Case Study Based on Palermo's Municipality

The Italian public sector is characterized by a great number of stakeholders, both public and private. That’s the reason why, in the past, dealing with public issues meant to face different actors and administrations, to solve the several number of bureaucratic requirements. In particular, the field of new business activities was very complex. This area was characterized by huge fragmentations among the public bodies involved. In fact, if an entrepreneur wanted to open a new business, it was necessary to deal with different subjects to obtain the mandatory permits, license and authorizations. Accomplishing all the steps, without any support from the public sector, implied an increase of cos…

Analysing Tourist Destination Image through Topic Modeling

2019

Topic modeling has become one of the most used methods to analyse textual data, proving able to “discover” hidden dimensions (topics) which characterise a corpus. This methodology can be used fruitfully to analyse complex phenomena like tourist destination image. With this aim in mind, this paper discusses the use of topic modeling over TV commercials which have been broadcast by four of the major cruise lines operating in Italy in recent years.

Low cost survey techniques aimed to the Cultural Heritage conservation.

2017

Thanks to SfM (Image Based Modeling) survey techniques, is possible to realize 3D models of every object, in a very short time and with limited economical and training resources, today. These semi-automated SfM software allow users to simply upload photos and follow a mediated workflow, without any complex inner workings of SfM and this can be especially advantageous to users in non-technical fields or to those with limited resources. Every year there is an international Event, #digitalinvasion, that involves the Italian museums and that reckons on to allow to take pictures and video to the whole museum collections. This event is present in Palermo since 2014 and the Engineering first year …

Inverse procedural modeling of 3D models for virtual worlds

2016

This course presents a collection of state-of-the-art approaches for modeling and editing of 3D models for virtual worlds, simulations, and entertainment, in addition to real-world applications. The first contribution of this course is a coherent review of inverse procedural modeling (IPM) (i.e., proceduralization of provided 3D content). We describe different formulations of the problem as well as solutions based on those formulations. We show that although the IPM framework seems under-constrained, the state-of-the-art solutions actually use simple analogies to convert the problem into a set of fundamental computer science problems, which are then solved by corresponding algorithms or opt…

Present-day use of an empirical wave prediction method

2016

Knowledge of the offshore wave climate is key to the design of coastal engineering structures and to the study of shoreline evolution. To date, the available wave data have been limited both in time and space; even though there are several options for obtaining wave data calculated using complex numerical models at basin scale, design issues can in some cases be solved by means of simpler models. This paper shows whether, under certain conditions and in an enclosed basin, an old empirical model can provide results that are good enough to determine the design condition necessary for engineering purposes. The empirical model chosen to answer this question is called Sverdrup–Munk–Bretschneide…

A Shoreline model for breaking waves

2011

In order to simulate the wave motion and, in turn, the flow, within the nearshore region, in the last decades the derivation and the application of depth-integrated type of models have been widely investigated and developed. However, in such models, the problems of facing wave breaking and the moving shoreline are not trivial and therefore several approaches have been proposed. About wave breaking, approaches both based on the adoption of an artificial eddy viscosity Zelt (1991) and on the concept of roller Veeramony (2000), Karambas (2003), Musumeci (2005) have been implemented. As regards the shoreline boundary condition, a couple of numerical techniques have been mainly adopted, namely t…

On the hidden significance of differing micro-sites on tree-ring based climate reconstructions

2015

Tree-ring chronologies are commonly extended back in time by combining samples from living trees with relict material preserved in man-made structures or natural archives (e.g. lakes). Although spatially close, these natural archives and living-tree-sites often comprise different micro-climates. Inhomogeneous growth conditions among these habitats, which may yield offsets in growth-rates, require caution in data processing. Here we assess species-specific growth dynamics in two micro-habitats and their potential effects on long chronologies by combining tree-ring data from different living-tree-sites with an “artificial” subfossil dataset. Well replicated (n > 80) Norway spruce (…