Browsing by Issue Date, starting with "2000-09"
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- Numerical study of spray dispersion in a premixing chamber for Low-NOx enginesPublication . Barata, Jorge M M; Silva, AndréThe present work describes a numerical study of a confined two-phase flow under high-pressure conditions, typical of gas turbine combustors. An Eulerian frame was used for the gas phase together with a Lagrangian approach to describe the dispersed phase. The computational method was extended to high-pressure environments, which are more representative of the practical gas turbine operating conditions. The results are compared with experimental data, and revealed the ability of the model to increase the knowledge of the turbulent dispersion phenomena for this type of practical conditions (high pressure and confined flow).
- Deployment scenarios for mobile broadband communicationsPublication . Velez, Fernando J.; Correia, Luis M.The multi-service traffic analysis of a mobile broadband system (MBS), with a given mixture of applications, requires the definition of their main operation environments, corresponding to the residential, the mixed (half business/half residential), the business and the industrial markets. In this work, the respective deployment scenarios are defined by the values for the usage of a set of 26 applications. The usage of broadband applications (>2 Mb/s) increases from the residential market (17%) to the business one (25%), corresponding to a decrease in the usage of wideband (<2 Mb/s) ones (from 50 down to 42%), and to a constant value for the usage of low-MBS ([128, 384] kb/s) ones (33%); slight differences exist from the business to the industrial market. The actual number of users also depends on the density factor, varying from 0.004 users/m/sup 2/ in the industrial scenario to 0.150 users/m/sup 2/ in hotspots, e.g., offices.
- Classification and characterisation of mobile broadband servicesPublication . Velez, Fernando J.; Correia, Luis M.The available data about mobile broadband services / applications is put together, and their characterisation parameters are identified, enabling some insight into new approaches for multi-service traffic analysis in MBS. On one hand, a classification of services and applications is proposed based on the 1.21 1 ITU-T Recommendation. It distinguishes between interactive and distribution services, and also identifies the types of information supporting each one. On the other hand, a taxonomy is proposed for applications’ characterisation parameters, which are divided into five different types: main ones, traffic and communications parameters, service components and operation environments as well. Examples are given for the range of variation of each type of parameters.