Search results for "computer network"
showing 10 items of 1634 documents
Tarifas Portuárias: Um Estudo Comparativo entre os Sistemas Portuário Brasileiro e Espanhol
2014
The objective of this study is to investigate and document the system of port taxes in Brazil and Spain. To achieve this, we consulted the laws, rules and documents, and the websites of the main Brazilian and Spanish ports. The study is unprecedented and brings out a little researched topic in Brazil, which is the port taxes. The results show that the Spanish system is structured by defining the different types of taxes to be charges. While the tax for Brazilian ports is confusing to present a diversity of shapes and charging models. This study has practical implications as they search alercar and present a system that can serve as a model for Brazil. This is because the port rates have a d…
Benchmarking open data efforts through indices and rankings: Assessing development and contexts of use
2022
Abstract This paper aims to provide a broad perspective on the development of benchmarking open data efforts through indices and rankings over the years, both at the level of countries and allowing for a cross-country comparison. The methodology follows a systematic search for the relevant resources, their classification and identification of six open data benchmarks to be further analyzed, the identification of their key components through decomposition, their description, and identifying the similarities and differences. Three major groups of indices and four periods that characterize the efforts to benchmark and measure the development of open data are identified, where the first measure…
Experimental realization of a Persistent Identifier Infrastructure stack for Named Data Networking
2015
The continuation of Persistent Identifier Infrastructures is crucial when next-generation Internet architectures based on Information-Centric Networking (ICN) arise. When moving to ICN, we must ensure the resolution of Persistent Identifiers (PID), such as the billions of Digital Object Identifiers (DOI) used today, to provide continued access to scientific literature and research data. It provides the base for the necessary transformations in the Handle System architecture and protocol for running a PID system on the Named Data Networking (NDN) architecture, which is a recent incarnation of ICN. Furthermore, it examines the PID-specific resolution access patterns, investigates the expected…
The Design of Secure and Efficient P2PSIP Communication Systems
2010
Recently, both academia and industry have initiated research projects directed on integration of P2PSIP paradigm into communication systems. In this paradigm, P2P network stores most of the network information among participating peers without help of the central servers. The concept of self-configuration, self-establishment greatly improves the robustness of the network system compared with the traditional Client/Server based systems. In this paper, we propose a system architecture for constructing efficient and secure P2PSIP communication systems. The proposed approach includes three-layer hierarchical overlay division, peer identifier assignment, cache based efficiency enhancement, proxy…
Collaboration and collaborative information technologies
1999
Collaborative information technologies have been claimed to enhance collaboration in organizations, under certain conditions. This claim was found problematic in several respects, also in the light of the results of 18 case studies of Lotus Notes use, taken from the literature. The cases may be split into three groups: (1) exploratory, conservative, or cautious use; (2) planned and expanding use; and (3) extensive and engaged use of Notes. In the first group, no changes in work arrangements due to Notes use could be found. In the second group, the planned Notes applications supported the established work arrangements, both collaborative and hierarchical. Only in the third group were there s…
On the Statistical Properties of Phase Crossings and Random FM Noise in Double Rayleigh Fading Channels
2016
In this paper, we study the statistics of phase processes and random frequency modulation (FM) noise encountered in double Rayleigh fading channels. The Rayleigh processes making up the double Rayleigh channel are assumed to be independent but not necessarily identically distributed. The Doppler power spectral densities of these processes are supposed to be symmetric about the carrier frequency. Under these fading conditions, we derive first an expression for the joint probability density function (jpdf) of the phase process and its rate of change. Capitalizing on this jpdf formula, we then investigate the probability density function (pdf) and cumulative distribution function (cdf) of rand…
Do shippers’ characteristics influence port choice criteria? Capturing heterogeneity by using latent class models
2022
Abstract This paper focuses on the study of Spanish ceramic tile exporters' port choice criteria, an industry that is characterized by a low unit value index. Thus, transport costs highly influence the competitiveness of their products in international markets, representing a relatively high percentage of the value of the shipment. It is therefore critical for this type of industry to have access to efficient door-to-door maritime chains. Determinants of port choice are analysed through a latent class model allowing to link class membership to specific characteristics of the shippers and their shipments such as the size of the company, the value of the shipment, the destination market and t…
Improving RF Fingerprinting Methods by Means of D2D Communication Protocol
2019
Radio Frequency (RF) fingerprinting is widely applied for indoor positioning due to the existing Wi-Fi infrastructure present in most indoor spaces (home, work, leisure, among others) and the widespread usage of smartphones everywhere. It corresponds to a simple idea, the signal signature in a location tends to be stable over the time. Therefore, with the signals received from multiple APs, a unique fingerprint can be created. However, the Wi-Fi signal is affected by many factors which degrade the positioning error range to around a few meters. This paper introduces a collaborative method based on device-to-device (D2D) communication to improve the positioning accuracy using only fingerprin…
Multiple viewpoints increase students' attention to source features in social question and answer forum messages
2016
International audience; Social question & answer forums offer great learning opportunities, but students need to evaluate the credibility of answers to avoid being misled by untrustworthy sources. This critical evaluation may be beyond the capabilities of students from primary and secondary school. We conducted 2 studies to assess how students from primary, secondary, and undergraduate education perceive and use 2 relevant credibility cues in forums: author's identity and evidence used to support his answer. Students didn't use these cues when they evaluated forums with a single answer (Experiment 1), but they recommended more often answers from self‐reported experts than from users with a …
Behavior-based personalization in web search
2016
Personalized search approaches tailor search results to users' current interests, so as to help improve the likelihood of a user finding relevant documents for their query. Previous work on personalized search focuses on using the content of the user's query and of the documents clicked to model the user's preference. In this paper we focus on a different type of signal: We investigate the use of behavioral information for the purpose of search personalization. That is, we consider clicks and dwell time for reranking an initially retrieved list of documents. In particular, we (i) investigate the impact of distributions of users and queries on document reranking; (ii) estimate the relevance …