5 research outputs found
The UK silicon photonics project
No full textThe project is a consortium based activity involving researchers from the UK institutions of the Universities of Surrey, St. Andrews, Leeds, Warwick, and Southampton, as well as the commercial research institution QinetiQ. The aims of the project are to progress the state of the art in Silicon Photonics, in the areas of waveguides, modulators, couplers, detectors, Raman processes, and integration with electronics. Thus the field is vast, and impossible to cover comprehensively in one project, nor indeed in one paper. The programme is run on a truly collaborative basis, with members from each institution running one or more work packages within the project, each co-ordinating work from their own plus other institutions. To date, the most well developed work has emerged from the activity on basic waveguides and their characteristics, the modulator activity, optical filters, and work on Raman Amplifiers. This work will be the main focus of this paper, but an attempt will be made to update the audience on the remaining activities within the project. By the nature of the project, much of the work is medium term, and hence some activities are not expected to yield viable results until at least next year, hence the concentration on some activities rather than all activities at this stage
UML and Petri Nets for Design and Analysis of Distributed Systems
Get PDFThis paper presents a modification to UML to improve the modelling and analysis of discrete-event dynamic system (DEDS) representations of manufacturing systems. It shows how Petri nets can be used to improve the representation and analysis of the dynamic model of a system specified using UML. Finally the technique is illustrated by its application to a simplified production line
Macromodel of the Romanian market economy (version 2005)
Get PDFThe macromodel will be used to investigate short and medium–run economic implications of internal policies and of changes in the international context. This new version of the Romanian macromodel benefites from the experience gained by the author during the utilisation of its previous forms - either experimental (tested during 1991-1995) or operational (developed during 1996-2003). At the same time, this model introduces some methodological and informational improvements, in comparison to previous versions. The most significant of them is the structural decomposition of economy, according to the input-output techniques. Output and absorption are divided into: a) agriculture, sylviculture, forestry, hunting, and fishing; b) mining and energy; c) manufacturing industry; d) construction; e) transport, post and communications; f) trade and services. These categories can be easily translated into the classical three-sectors classification: primary (a+b), secondary (c+d), and tertiary (e+f). Due to the relatively advanced stage of the transitional processes in Romania, the behavioural functions were modelled - as much as possible - by the standard relationships. Besides, unlike the previous versions, that used statistical series beginning with 1980, the present one is based exclusively on information regarding the period 1989-2004. Therefore, we have considered more adequate to name this variant the macromodel of the Romanian market (not transition, as before) economy. Since the input-output tables are defined yearly, the model contains only annual indicators. They are expressed in denominated local currency (RON). When there were several informational sources for the same indicator, we preferred the data extracted or derived from national accounts. The statistical series are relatively short and often fractured (because of the transforming processes of transition). Although, it is known that ADF test of stationarity does not offer reliable results in the case of limited number of observations, generally the series satisfying it were used. The Granger causality test was computed for one, two, and three lags. The simplest methods of estimation were also preferred. The structural breaks in the evolution of some indicators have been dealt by the inclusion of dummies. Obviously, all these circumstances weaken the stability of econometric coefficients that must be continuously updated. The main relationships are grouped in seven sections: input-output block; labour market, production function; domestic absorption, foreign trade, prices and exchange rate, and interest rate. The first two chapters present conceptual framework of macromodel and econometric analysis on which it is based. The next one describes a possible scenario for the Romanian economy during 2005-2010 years. The final part of paper contains a set of simulations revealing some operational features of the macromodel.model, input-output analysis, econometric relationships, simulations
Integration of macroeconomic behavioural relationships and the input-output block: Romanian modelling experience
Get PDFThe last version of the Romanian macromodel (Dobrescu 2005b) incorporates the experience accumulated through the utilisation of its previous forms - either experimental (Dobrescu 1991-1994) or operational (Dobrescu 1996-2005a). At the same time, it introduces some methodological and informational improvements. The most significant of them is the structural decomposition of economy, according to the input-output techniques. Output and absorption are divided into: a) agriculture, sylviculture, forestry, hunting, and fishing; b) mining and energy; c) manufacturing industry; d) construction; e) transport, post and communications; f) trade and services. These categories can be easily translated into the classical three-sectors classification: primary (a+b), secondary (c+d), and tertiary (e+f). Due to the relatively advanced stage of the transitional processes in Romania, the behavioural functions were modelled - as much as possible - by the standard relationships. Besides, unlike the previous versions (that used statistical series beginning with 1980) the present one is based exclusively on information regarding the period 1989-2004. Since the input-output tables are defined yearly, the model contains only annual indicators. They are expressed in denominated local currency (RON). The export, import, and exchange rate series were transformed in Euro. When there were several informational sources for the same indicator, the data extracted or derived from national accounts have been adopted. The statistical series are relatively short and often fractured (because of the transforming processes of transition). Although, it is known that ADF test of stationarity does not offer reliable results in the case of limited number of observations, generally the series satisfying it were used. The simplest regression methods were also preferred. The structural breaks in evolution of some series have been dealt by the inclusion of dummies. Obviously, all these circumstances weaken the stability of econometric coefficients that must be continuously updated. The first two chapters of the paper characterise the main macroeconomic behavioural relationships and input-output coefficients. The third one discusses a possible scenario for the Romanian economy during 2005-2010. A set of simulations is presented in the final part of the paper; these reveal some operational features of the macromodel.model, input-output analysis, econometric relationships, simulations
