4,747 research outputs found
Welfare and excess volatility of exchange rates
We study the properties of a GEI model with nominal assets, outside money (injected into the economy as in Magill and Quinzii), and multiple currencies. We analyze the existence of monetary equilibria and the structure of the equilibrium set under two different assumptions on the determination of the exchange rates. If currencies are perfect substitutes, equilibrium allocations are indeterminate and, generically, sunspot equilibria exist. Generically, given a nonsunspot equilibrium, there are Pareto improving (and Pareto worsening) sunspot equilibria associated with an increase in the volatility of the future exchange rates. We interpret this property as showing that, in general, there is no clear-cut effect on welfare of the excess volatility of exchange rates, even when due to purely extrinsic phenomena.
CHARACTERIZATION OF A MOBILE MAPPING SYSTEM FOR SEAMLESS NAVIGATION
Abstract. Mobile Mapping Systems (MMS) are multi-sensor technologies based on SLAM procedure, which provides accurate 3D measurement and mapping of the environment as also trajectory estimation for autonomous navigation. The major limits of these algorithms are the navigation and mapping inconsistence over the time and the georeferencing of the products. These issues are particularly relevant for pose estimation regardless the environment like in seamless navigation. This paper is a preliminary analysis on a proposed multi-sensor platform integrated for indoor/outdoor seamless positioning system. In particular the work is devoted to analyze the performances of the MMS in term of positioning accuracy and to evaluate its improvement with the integration of GNSS and UWB technology. The results show that, if the GNSS and UWB signal are not degraded, using the correct weight to their observations in the Stencil estimation algorithm, is possible to obtain an improvement in the accuracy of the MMS navigation solution as also in the global consistency of the final point cloud. This improvement is measured in about 7 cm for planimetric coordinate and 34 cm along the elevation with respect to the use of the Stencil system alone
Accountability and music: accounting, emotions and responses to the 1913 concert for Giuseppe Verdi
Purpose: This study aims to explore the engagement between accounting and music in the social and relational construction of accountability. The authors conceive this construction as a dynamic and recursive interplay between the giving of different accounts and the responses that these accounts provoke. The authors investigate the emotional dimension of this interplay, as it is also triggered by music, feeding back into how accountability is constructed and evolves over time. Design/methodology/approach: This study relies upon a historical analysis of archival and secondary sources about the main music concert organized in 1913 by the founder of “Accademia Chigiana”, one of the leading music academies in Italy. The concert celebrated the first centenary of the birth of Giuseppe Verdi, a worldwide famous Italian music composer, and icon of Italian national sentiment. Findings: This study shows that music and accounting were profoundly intertwined in the social and relational construction of accountability for the 1913 concert. Accountability evolved through different accounts, also linked to music, and the complex emotional reactions these accounts provoked in the audiences, citizens, media and institutions, leading to always further responses and accounts in the ongoing construction of accountability. Originality/value: This study extends prior literature on the chameleonic nature of accountability, as well as on its relational and emotional dimensions. The study shows that accountability is relationally constructed and evolves over time through the giving of accounts and the emotional reaction they provoke from others, feeding into further responses and accounts of the accountable subject. The authors show how the chameleonic nature of accountability permeates not only the accounts and the relations of accountability but also the subjects giving and demanding the accounts: these subjects change as chameleons through their interactions and emotions, feeding into the dynamic construction of accountability. The authors also show how arts, like music, can participate in the chameleonic nature of accountability and of its subjects, precisely by engaging with their emotional reactions and responses
Monocular Visual Odometry with Unmanned Underwater Vehicle Using Low Cost Sensors
The positioning in underwater environments is today a strong necessity for many purposes, such as construction, communication, localization, and environmental monitoring. The use of underwater rover allows to perform visual inspections, maintenance and repair of many infrastructures, like dams, pipes, tunnels, structures as well as the analyses of the underwater environments in lakes, rivers and seas. This work deals with interesting results about monocular visual odometry for unmanned underwater navigation systems. Interesting results have been obtained considering low-cost sensors simulating the real-time, challenging operational conditions, applied for a dedicated archaeological situation. Particular algorithms for navigation procedures and outliers' rejections have been written and will presented in this paper: these aspects have a great importance especially for autonomous navigation solutions in underwater complex environments, such as for archaeological applications
GNSS positioning using mobile devices with the android operating system
The access and the use of the global navigation satellite system (GNSS) pseudo-range and carrier-phase measurements mobile devices as smartphones and tablets with an Android operating system has transformed the concept of accurate positioning with mobile devices. In this work, the comparison of positioning performances obtained with a smartphone and an external mass-market GNSS receiver both in real-time and post-processing is made. Particular attention is also paid to accuracy and precision of positioning results, also analyzing the possibility of estimating the phase ambiguities as integer values (fixed positioning) that it is still challenging for mass-market devices. The precisions and accuracies obtained with the mass-market receiver were about 5 cm and 1 cm both for real-time and post-processing solutions, respectively, while those obtained with a smartphone were slightly worse (few meters in some cases) due to the noise of its measurements
GNSS Positioning using Android Smartphone
The possibility to manage pseudorange and carrier-phase measurements from the Global Navigation Satellite System (GNSS) chipset installed on smartphones and tablets with an Android operating system has changed the concept of precise positioning with portable devices. The goal of this work is to compare the positioning performances obtained with a smartphone and an external mass-market GNSS receiver both in real-time and post-processing. The attention is also focused not only on the accuracy and precision, but also on the possibility to determine the phase ambiguity values as integer (fixed positioning) that it is still a challenging aspect for mass-market devices: if the mass-market receiver provides good results under all points of view both for real-time and post-processing solutions (with precisions and accuracies of about 5 cm and 1 cm, respectively), the smartphone has a bad behaviour (order of magnitude of some meters) due to the noise of its measurements
On the novel free porphyrins corallistin B, C, D, and E : isolation from the demosponge Corallistes sp. of the Coral Sea and reactivity of their nickel (2) complexes toward formylating reagents
Reported here are the novel free corallistin B, C, D, and E, isolated as methyl esters 2a, 3a, 4a, and 5a, respectively, from the sponge #Corallistes sp.(#Lithistida) collected at the basis of the South New Caledonian coral reef. A protocol is also established for formulation of their NiII complexes, which show a different reactivity pattern toward DMF/POCI3 from metal complexes of deuteroporphyrin IX (isolate as 6a) also present in the sponge, the new corallistins, which may be thought to derive from protoporphyrin via heme, account for an amazing 60% of the etOH extract from the sponge. (Résumé d'auteur
Seamless Navigation using UWB-based Multisensor System
This work presents an Ultra-wideband-based (UWB) approach to seamless positioning and navigation applied in a real test-bed. It deploys two different solutions for positioning estimation in function of the operational environment. Outdoors, a classical hybridization between Global Navigation Satellite System (GNSS) and Inertial Measurement Unit (IMU) is applied while indoors, an UWB/INS integration is performed relying on a low-cost commercial platform which integrates both UWB unit and IMU. The implementation of this procedure will be presented with more details in the paper. The aim of the work is to validate the performances in term of accuracy, precision and seamlessness behavior of the low-cost UWB technology available today. The results shown an overall accuracy of about 60 cm considering the entire path walked, both outdoor and indoors
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