Browsing by Issue Date, starting with "1998-06"
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- Influence of Traffic from Mobility on the Microcellular Coverage Distance in Mobile Broadband SystemsPublication . Velez, Fernando J.; Correia, Luis M.Models allowing the study of the influence of coverage distance and velocity on the supported traffic and on the new calls traffic linear density are examined, and results are obtained for typical scenarios in a Mobile Broadband System (MBS) with a linear coverage geometry. For situations without using guard channels for handover, for a fixed bounding value for the blocking probability, the new calls traffic linear density has been analyzed, increasing with the decrease of the coverage distance R, and being upper limited by a value which depends on the characteristics of the mobility scenario. However, call-dropping probability requirements also need to be fulfilled, leading to a new calls traffic linear density that only increases with the decrease of R down to an optimum value of R, and being lower for scenarios with higher mobility. This situation leads to limitations in system capacity for lower values of the coverage distance, mainly for high mobility scenarios.
- Microcellular Design and System capacity determination for Outdoors Urban Mobile Broadband Communication Systems in the Millimetrewave BandsPublication . Velez, Fernando José; Brazio, José M.This paper addresses lhe cellular design of mobile microcellular communications systems operating in lhe millimetrewave bands in outdoor urban environments. ln such systems and environments lhe shape of cells and lhe interference among them are highly dependent on lhe geomctry of lhe surrounding obstacles (c.g., buildings) and lhe classical regular geametry based approaches to frequency reuse and capacity evaluation eannat be used. In lhe paper is described an approach to frequency reuse and system capacity evaluation where canclusions are drawn frem cellular layouts obtained, via an interactive computer graphical tool, for specific urban environments. Numerical examples are presented for coverage in lhe 40 and 60 GHz bands showing that, depending on lhe celI size, reuse factors in lhe range 5-11 are achievable. It is also concluded that, in interference límited scenarios, if cells with similar coverage length are used, equal values are obtained for lhe reuse factor and system eapacity in both bands.
- Evaluation of In-place Concrete Strength by Near-to-surface TestsPublication . Lopes, Sérgio Manuel Rodrigues; Nepomuceno, MiguelThe near-to-surface tests, as described by British Standard BS 1881: Part 207: 1992, comprises different techniques which were developed to evaluate in-situ strength of concrete, and it includes: internal fracture, pull-out, pull-off, penetration resistance and break-off tests. Since these tests measure only a property of concrete close to the surface, the evaluation of in-situ strength of concrete mass has to be obtain by a experimentally correlation between the near-to surface test results and the compressive strength of concrete mass. This paper discusses the reliability of two of this techniques, penetration resistance test and pull-out tests, as a construction tool for the evaluation of the in-place concrete strength both in normal and high strength concrete. For penetration resistance test applied to high-strength concrete an alternative firing apparatus to the standard apparatus, Windsor Probe Test System, is used. The obtained correlations are also presented and compared to those obtain by other research works.
- Programa, Conteúdos e Métodos de Ensino da disciplina de Antropologia Cultural I da Licenciatura em SociologiaPublication . Schouten, Maria Johanna ChristinaPrograma da unidade curricular Antropologia Cultural 1 integrada no curso da licenciatura de Sociologia, Universidade da Beira Interior 1997-1998.Documento submetido para efeitos do concurso documental a Professor Associado da área disciplinar de Sociologia e Comunicação Social (Sociologia). Contém o enquadramento desta disciplina no curso, bem como introduções às áreas de Antropologia Económica e Antropologia Política. Document submitted in the recruitment process of associate professor in sociology, at the University of Beira Interior, Covilhã, 1998.