1,721,358 research outputs found
Aspectos a tener en cuenta en la endodoncia en el adulto mayor
No full textFil: Fazio, P..
Universidad Nacional de Cuyo. Facultad de Odontologí
Markov chain channel modeling based on degradation level concept for ultra wideband WPAN
No full textUWB technology is defined as any transmission scheme employing a fractional band greater than 25%. The unique UWB physical characteristics required alternative approach to model wireless channel, so in last few years the academic research increases around this aspect. In fact, in the literature many channel modeling have been carried out, but greater of them work at the physical level or it investigates only some aspects of channel interaction, instead in our work we provide a high level channel model based on Discrete Time Markov Chain modeling useful in every simulation context. In particular, our model is based on the concept of error trace analysis and on degradation level of given observation windows: we do not analyze the single packet, but we fix an observation window and we evaluate the degradation level of the link computing the PER relative to the specific window. This new approach is more accurate than classic Gilbert-Elliot model as comparative analysis showed
A new Markov-based mobility prediction scheme for wireless networks with mobile hosts
No full textRecently, mobile communications need to benefit a good level of Quality of Service (QoS), since communications guarantees are mandatory during active flows. Passive resources are used to ensure service continuity when mobile hosts are moving among different coverage cells. In this work the attention is focused on wireless services in cellular networks, where the hand-over effects need to be mitigated, through an appropriate reservation policy. The whole considered system is modeled through a distributed set of Hidden Markov Chains (HMC) and the related theory is used to design a mobility predictor, as the main component of the proposed idea, which does not depend on the considered transmission technology (GSM, UMTS, WLAN, etc.), mobility model or vehicular scenario (urban, suburban, etc.). MRSVP has been used in order to realize the active/passive bandwidth reservation in the considered network topology and many simulation campaigns have been carried out in order to estimate the correctness of the proposed algorithm, also in terms of CDP and CBP. © 2012 Society for Modeling & Sim
Evaluation of TCP versions over GEO satellite links
No full textIn this paper an attempt to evaluate the performance of different versions of TCP over satellite link has been performed. The throughput of the protocols has been graphed and considerations have been carried out. The considered protocols can be divided in two main categories: terrestrial protocols and satellite protocols. In the terrestrial category the well performing TCP Sack protocol has been illustrated together with TCP WestWood and his modified version, TCP WestWood+, while in the satellite category Satellite Communication Transport Protocol (SCPS-TP), and Satellite Transmission Protocol (STP) have been shown and compared. The considered protocols have been analyzed on well-known satellite link: GEO satellite link. In particular, a classical GEO satellite link and a single connection between two terminals have been considered
A new threshold switching scheme for a DVB-RCS+M return link in a terrestrian scenario
No full textThe new standard for DVB-RCS includes guidelines for mobile user in the market of aircraft, maritime and terrestrial. The standard suggests the possibility of using, in this scenario, a continuous carrier operation mode in the return channel beside the classical MF-TDMA mode. In this context it can be important a mechanism for switching between these two modalities in order to exploit in a better way the satellite resources. In this paper, after showing the typologies of applications considered in the simulation, a proposal of a novel switching mechanism is presented and the simulation results are reported in order to provide some guidelines to the satellite operators that want to adopt in their satellite system this hybrid mode. © 2012 IEEE
A Simulator for Creating Drones Networks and Providing Users Connectivity
Full text linkUnmanned aerial vehicles are devices able to perform many different tasks that can help human activity in many processes. One of the most important use regards the possibility of giving wireless connectivity to user in a specific area. These new typologies of networks are called Flying Adhoc Network. Their use benefit all those situations of emergency where the traditional communications may have many issues, due to the specific event. Different types of natural disasters (such as climatological, meteorological, hydrological, geophysical) can result in many deaths and many economic damages. In these situations, drones can provide an additional or complementary access network, supporting web services and multimedia traffic, helping people involved in the rescue. Hence, it is clear that the possibility of using a simulator can result in a huge help to the research community. So, in this work, a Flying Ad-hoc Network simulator is proposed, able to simulate different scenarios with different coverage areas. In particular, emphasis is given to new coverage and human mobility models, in order to support more realistic situations. Some simulations have been led out to show how the simulator works
Routing optimization in dynamic networks based on a new entropy metric
No full textA key role in the modern telecommunication networks is played by routing aspects as the great number of works present in literature proves. In particular, in the mobile ad-hoc networks routing is a fundamental aspects because the mobile devices nature and their elevate dynamism. In fact, it is important to have the possibility of finding the minimum overhead for connectivity in the network and, calculate the communication potential through the analysis of different parameters. The focus of this paper is represented by the analysis of the entropy in this type of mobile networks. The entropy gives the possibility of studying and predicting the dynamics of mobile nodes. The knowledge of these aspects can help to optimise some key features of wireless mobile communications, such as nodes stability, channel failures, and routing costs. Many simulation campaigns have been carried out by taking into account the movement of the real nodes, obtaining beneficial results, which confirm the effectiveness of the proposed study
Ipotesi di valori percentuali da perdite dentarie e comparazione con altri barémes
No full textAttraverso l’analisi comparativa dei maggiori barèmes ufficiali e delle principali espressioni percentuali della letteratura, si perviene ad una situazione critica degli orientamenti valutativi in tema di danno da perdite dentarie in responsabilità civile.
Sui più validi di tali orientamenti viene imposta una nuova ipotesi di stima tabellare del danno improntata alle più recenti acquisizioni di gnatologia e di cinematica mandibolare ed in riferimento all’efficienza psico-fisica del leso, secondo gli attuali rinnovati orientamenti di dottrina
Thermal and mechanical characterization of panels made by cement mortar and sheep's wool fibres
No full textGreen building and environmental sustainability are two important concepts for technicians and engineers. Among natural materials, usually considered as waste, sheep wool plays a fundamental role. This paper is intended to learn more about the potential of these fibres inserted in cement mortar panels, investigating both the insulation properties and mechanical strength, trying to achieve an optimal compromise between these two aspects. Therefore, in the laboratory of materials ENEA Research Centre Trisaia, several panels with different percentages of sheep wool were manufactured, tested and characterized according to technical standards. © 2017 The Authors
- …
