Performance Analysis of Publish/Subscribe Systems

The Desktop Grid offers solutions to overcome several challenges and to answer increasingly needs of scientific computing. Its technology consists mainly in exploiting resources, geographically dispersed, to treat complex applications needing big power of calculation and/or important storage capacity. However, as resources number increases, the need for scalability, self-organisation, dynamic reconfigurations, decentralisation and performance becomes more and more essential. Since such properties are exhibited by P2P systems, the convergence of grid computing and P2P computing seems natural. In this context, this paper evaluates the scalability and performance of P2P tools for discovering and registering services. Three protocols are used for this purpose: Bonjour, Avahi and Free-Pastry. We have studied the behaviour of theses protocols related to two criteria: the elapsed time for registrations services and the needed time to discover new services. Our aim is to analyse these results in order to choose the best protocol we can use in order to create a decentralised middleware for desktop grid

Applying ArchOptions to value the payoff of refactoring

ArchOptions is a real-options based model that we have pro-posed to value the flexibility of software architectures in response to future changes in requirements. In this paper, we build on ArchOptions to devise an options-based model, which values the architectural flexibility that results from a refactoring exercise. This value assists in understanding the payoff of investing in refactoring: if the refactored system results in an architecture that is more flexible, such that the expected added value (in the form of options) due to the en-hanced flexibility outweighs the cost of investing in this exer-cise, then refactoring is said to payoff. We apply our model to a refactoring case study from the literature

Regulating excessive speculation: commodity derivatives and the global food crisis

Evidence suggests that commodity derivatives speculation contributed to extraordinary patterns of grain price volatility that led to a global food crisis in 2007–11. People in countries throughout the world are increasingly dependent on international commodity markets for access to food. Almost everywhere, now, the value of food is determined by a single condensed symbol of its worth—its price. Persuaded of the need to ensure that this measure of value is not put at risk of distortion in the pursuit of financial profit, governments in the US and in the EU are now implementing new regulations designed to curb ‘excessive’ levels of speculation in derivative markets. Carrying out an analysis of these regulatory measures, the article demonstrates that both sets of reforms suffer from a critical limitation: They are predicated on an inaccurate understanding of how activity in commodity derivative markets can impact on underlying food prices. If the new regulations for commodity derivative markets are not up to the task, as this article argues that they are not, a more fundamental revision of global economic structures may be required if the basic needs of human beings are not to be subsumed to the interests of financial capital in the years to come

The Economics of Electronics Industry: Competitive Dynamics and Industrial Organization

This entry highlights fundamental changes in the electronics industry that have transformed its competitive dynamics and industrial organization: a high and growing knowledge intensity; the rapid pace of change in technologies and markets; and extensive globalization. That explosive mixture of forces has created two inter-related puzzles. The first puzzle is that a high degree of globalization may well go hand in hand with high and increasing concentration. This runs counter to the dominant view, based on the assumption of neo-classical trade theory, that globalization will increase competition and hence will act as a powerful equalizer both among nations and among firms. Multinational corporations, after all, may not be such effective "spoilers of concentration", as claimed by Richard Caves (1982). The second related puzzle is that this industry fails to act like a stable global oligopoly, even when concentration is extremely high: a market positions are highly volatile, new entry is possible, and not even market leaders can count on a guaranteed survival.

Determinants of power spreads in electricity futures markets: A multinational analysis. ESRI WP580, December 2017

The growth in variable renewable energy (vRES) and the need for flexibility in power systems go hand in hand. We study how vRES and other factors, namely the price of substitute fuels, power price volatility, structural breaks, and seasonality impact the hedgeable power spreads (profit margins) of the main dispatchable flexibility providers in the current power systems - gas and coal power plants. We particularly focus on power spreads that are hedgeable in futures markets in three European electricity markets (Germany, UK, Nordic) over the time period 2009-2016. We find that market participants who use power spreads need to pay attention to the fundamental supply and demand changes in the underlying markets (electricity, CO2, and coal/gas). Specifically, we show that the total vRES capacity installed during 2009-2016 is associated with a drop of 3-22% in hedgeable profit margins of coal and especially gas power generators. While this shows that the expansion of vRES has a significant negative effect on the hedgeable profitability of dispatchable, flexible power generators, it also suggests that the overall decline in power spreads is further driven by the price dynamics in the CO2 and fuel markets during the sample period. We also find significant persistence (and asymmetric effects) in the power spreads volatility using a univariate TGARCH model

Towards a Strategy for Economic Growth in Uruguay

The Uruguayan economy is recovering from the 2002 financial crisis that disrupted its banking system, caused a collapse of its currency and seriously affected its fiscal solvency. The crisis was clearly associated with the collapse of the Argentine economy and its concomitant currency, banking and debt crises. Both were also related to the sudden stop that followed the Russian crisis of 1998, which prompted an important realignment of the real in January 1999, a fact that had exerted enormous pressure on bilateral exchange rates within Mercosur. In this post-crisis period, Uruguay now faces several challenges to attain a sustainable growth path. This report proposes a series of recommendations towards this end. Implementing a strategy to accelerate growth inevitably involves interventions at both the macro and the micro level. The macro level involves the maintenance of a stable and competitive real exchange rate, so as to create a stable and encouraging environment for export growth. The authors take up each of these elements of the growth strategy. They first focus on the design of incentive policies for economic diversification and promotion. Then they discuss next the macroeconomic complements, with special emphasis on maintaining a competitive and stable real exchange rate.Economic Development & Growth

Using real options to select stable Middleware-induced software architectures

The requirements that force decisions towards building distributed system architectures are usually of a non-functional nature. Scalability, openness, heterogeneity, and fault-tolerance are examples of such non-functional requirements. The current trend is to build distributed systems with middleware, which provide the application developer with primitives for managing the complexity of distribution, system resources, and for realising many of the non-functional requirements. As non-functional requirements evolve, the `coupling' between the middleware and architecture becomes the focal point for understanding the stability of the distributed software system architecture in the face of change. It is hypothesised that the choice of a stable distributed software architecture depends on the choice of the underlying middleware and its flexibility in responding to future changes in non-functional requirements. Drawing on a case study that adequately represents a medium-size component-based distributed architecture, it is reported how a likely future change in scalability could impact the architectural structure of two versions, each induced with a distinct middleware: one with CORBA and the other with J2EE. An option-based model is derived to value the flexibility of the induced-architectures and to guide the selection. The hypothesis is verified to be true for the given change. The paper concludes with some observations that could stimulate future research in the area of relating requirements to software architectures

An Overhaul of a Doctrine: Has Inflation Targeting Opened a New Era in Developing-country Peggers?

The aim of this paper is to empirically examine the effect of a regime switch, from exchange-rate targeting (fixed exchange rate) to inflation targeting, on monetary policy in developing economies, hence adding to evidence on whether inflation targeting along with a managed float provides a better monetary policy compared to exchange-rate targeting. For this purpose, a group of developing countries that have historically experienced such a switch is analysed. This is done by an augmented interest-rate rule a-la Taylor (1993; 2001). Two methodological approaches are used: switching regression and Markov-switching method. Although both approaches have different drawbacks which compensate, still both lead to the conclusion that inflation targeting represented a real switch in developing countries. The period of inflation targeting was characterized by: a more stable economic environment; by more independent monetary-policy conduct; and by strict focus on inflation. Estimates suggest that the switch to a new monetary regime explains these results.inflation targeting, exchange-rate targeting, monetary regime switch, developing economies

Deriving Models for Software Project Effort Estimation By Means of Genetic Programming

Software engineering, effort estimation, genetic programming, symbolic regression. This paper presents the application of a computational intelligence methodology in effort estimation for software projects. Namely, we apply a genetic programming model for symbolic regression; aiming to produce mathematical expressions that (1) are highly accurate and (2) can be used for estimating the development effort by revealing relationships between the project’s features and the required work. We selected to investigate the effectiveness of this methodology into two software engineering domains. The system was proved able to generate models in the form of handy mathematical expressions that are more accurate than those found in literature.