Data Bit-Rate Instability in Wireless Multi-Rate Ad Hoc Networks

Wireless Ad-hoc single-rate environments typically use a Distance Vector routing with a metric based on the minimization of the hop-count. In practice, the technique of minimizing the distance does not reward in the case of multi-rate, therefore it may be prefereable touse protocols privileging the link's transmission speed instead of the minimum distance. Our study aims toward the stability of the link in a wireless high mobility environment; we explore and hypothesize how to privilege, in the choice of routes, the stablest link.Ad Hoc Networks; Routing; Stability.

Sovereign debt and CRAs: where does the power lie?

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and EconomicsThis work project analyzes how changes in sovereign debt rating within Europe can affect the stock performance of the event country, and wich are the factors that influence this impact. We found a significant impact made in both positive and negative watchlisting, while upgrades entail a significant downward reaction when they are preceded by watchlist activity. A further analysis of this impact allowed us to identify a surprise effect, composed by the presence of warning, the level of discussion and whether other agencies previously implemented the same action. Assuming the semistrong form of market efficiency holds, these findings suggestCRAs are considered to disclose provate information

Measuring passenger satisfaction: a strategy based on Rasch Analysis and the ANOM

Measuring passenger satisfaction presents several difficulties since customer satisfaction in the public transport sector is subject to different conditions which are different than those that affect other sectors. In this work, a strategy based on Rasch analysis and the Analysis of Means (ANOM) is proposed. This study is based on the idea that the Rasch rating scale model gives ‘sufficient statistic’ for an underlying unidimensional latent trait such as the satisfaction generated by local transport operators. Furthermore, the ability of passengers, measured by the rating scale model, is studied by means of ANOM decision charts to verify if there are different levels of satisfaction between the different groups of passengers

CoDa in three-way arrays and relative samples spaces

The object of these short notes is to give a set of convenient symbols to define the sample space for the different compositional vectors that can be arranged into a three-way array. For the exploratory analysis of three-way data, Parafac/Candecomp and Tucker3 are some of the most applied models for low-rank decomposition of three-way arrays. Here, in addition to the relative geometry, is presented a concise overview as to how the elements of a three-way array can be transformed into compositional form and the relative geometry is given

An Analisys of Business VPN Case Studies

A VPN (Virtual Private Network) simulates a secure private network through a shared public insecure infrastructure like the Internet. The VPN protocol provides a secure and reliable access from home/office on any networking technology transporting IP packets. In this article we study the standards for VPN implementation and analyze two case studies regarding a VPN between two routers and two firewalls.VPN; Network; Protocol.

Data Warehouse Design and Management: Theory and Practice

The need to store data and information permanently, for their reuse in later stages, is a very relevant problem in the modern world and now affects a large number of people and economic agents. The storage and subsequent use of data can indeed be a valuable source for decision making or to increase commercial activity. The next step to data storage is the efficient and effective use of information, particularly through the Business Intelligence, at whose base is just the implementation of a Data Warehouse. In the present paper we will analyze Data Warehouses with their theoretical models, and illustrate a practical implementation in a specific case study on a pharmaceutical distribution companyData warehouse, database, data model.

Link Stability inWireless Multi-Rate Ad Hoc Networks

Wireless ad hoc single-rate environments typically use a Distance Vector routing with a metric based on hop-count minimization. In practice, the technique of minimizing the distance does not reward in the case of multirate, therefore it may be prefereable to use protocols privileging link stability instead of speed and minimum distance. We study link stability in a wireless high mobility environment and propose a Route Discovery mechanism privileging the stablest link.VPN; Network; Protocol.

Discriminant Partial Least Square on Compositional Data: a Comparison with the Log-Contrast Principal Component Analysis

EnDiscriminant Partial Least Squares for Compositional data (DPLS-CO) was recently proposed by Gallo (2008). The aim of this paper is to show that DPLS-CO is a better dimensionality reduction technique than the LogContrats Principal Component Analysis (LCPCA) for dimensional reduction aimed at discrimination when a compositional training dataset is available