Ensuring efficiency and robustness in MANET

This paper introduces a joint load balancing and hotspot mitigation protocol for mobile ad-hoc network (MANET) termed by us as 'load_energy balance + hotspot mitigation protocol (LEB+HM)'. We argue that although ad-hoc wireless networks have limited network resources - bandwidth and power, prone to frequent link/node failures and have high security risk; existing ad hoc routing protocols do not put emphasis on maintaining robust link/node, efficient use of network resources and on maintaining the security of the network. Typical route selection metrics used by existing ad hoc routing protocols are shortest hop, shortest delay, and loop avoidance. These routing philosophy have the tendency to cause traffic concentration on certain regions or nodes, leading to heavy contention, congestion and resource exhaustion which in turn may result in increased end-to-end delay, packet loss and faster battery power depletion, degrading the overall performance of the network. Also in most existing on-demand ad hoc routing protocols intermediate nodes are allowed to send route reply RREP to source in response to a route request RREQ. In such situation a malicious node can send a false optimal route to the source so that data packets sent will be directed to or through it, and tamper with them as wish. It is therefore desirable to adopt routing schemes which can dynamically disperse traffic load, able to detect and remove any possible bottlenecks and provide some form of security to the network. In this paper we propose a combine adaptive load_energy balancing and hotspot mitigation scheme that aims at evenly distributing network traffic load and energy, mitigate against any possible occurrence of hotspot and provide some form of security to the network. This combine approach is expected to yield high reliability, availability and robustness, that best suits any dynamic and scalable ad hoc network environment. Dynamic source routing (DSR) was use as our underlying protocol for the implementation of our algorithm. Simulation comparison of our protocol to that of original DSR shows that our protocol has reduced node/link failure, even distribution of battery energy, and better network service efficiency.

Modelling, simulation and validation of a twelve-pulse autotransformer rectifier for aerospace applications

A microcap SPICE circuit-level model of a 12-pulse autotransformer based rectifier for an aircraft fuel-pump motor drive is described. The importance of including the nonlinear magnetising inductance of the interphase transformers is illustrated. Small supply voltage distortions are seen to result in current imbalance in the interphase transformers, degrading the rectifier input current, and may lead to infringement of the power quality specification. The model has been validated for various operating supply voltages, frequencies and output powers, against measurements from a 3.75 kW unit.

Exploiting Learning Technologies for World Wide Web Agents

Postprint

Gendered Responses to Global Crisis: Circular Migration and Return among Ecuadorian Families in Spain and Ecuador

This paper analyzes the impact of Spain’s economic crisis on social reproduction strategies of Ecuadorian migrant families in Madrid and Quito. The paper analyzes circular migration experiences and more permanent returns to Ecuador. I argue that these strategies and migrants' greater or lesser capabilities to move between different migration destinations show significant gender differences. On the one hand, men and women make a differential use of their migratory status to deploy transnational strategies and expand their mobility. On the other hand, migrants’ degree of mobility and flexibility with regard to the labor market and transnational social reproduction are derivative of a specific gendered order and sexual division of labor.

High-resolution image reconstruction from multiple low-resolution images.

In this paper, we demonstrate a digital signal processing (DSP) algorithm for improving spatial resolution of images captured by CMOS cameras. The basic approach is to reconstruct a high resolution (HR) image from a shift-related low resolution (LR) image sequence. The aliasing relationship of Fourier transforms between discrete and continuous images in the frequency domain is used for mapping LR images to a HR image. The method of projection onto convex sets (POCS) is applied to trace the best estimate of pixel matching from the LR images to the reconstructed HR image. Computer simulations and preliminary experimental results have shown that the algorithm works effectively on the application of post-image-captured processing for CMOS cameras. It can also be applied to HR digital image reconstruction, where shift information of the LR image sequence is known.

Relação entre a inteligência emocional e a liderança transformacional

No que concerne às competências e sucesso do líder a importância da Inteligência Emocional, está referenciada desde 1920, através do psicólogo Edward Thorndike, que salientou que o “melhor operário de uma fábrica pode não ser um bom capataz, por lhe faltar Inteligência social” (Goleman & Boyatzis, 2008). Com o decorrer dos anos, esta ideia foi-se tornando mais sustentada, reforçando a importância destas competências no líder, e não tanto as competências técnicas. Como concluído por Goleman, Boyatzis e McKee (2002), com base na investigação de anos, cerca de 500 modelos de competências de empresas globais. Esta ideia é também partilhada por Bass e Avolio (1994) (cit. in Megerian & Sosik, 1996), que referem que líderes que exibem níveis elevados de Inteligência Emocional, estão mais predispostos a apresentar comportamentos de Liderança Transformacional que líderes com níveis de Inteligência Emocional baixos. O estudo tem como objetivo analisar a influência da Inteligência Emocional na Liderança Transformacional percecionada pelos colaboradores em relação aos líderes, assim como na Liderança auto percecionada pelos managers. A amostra deste estudo foi de 41 reports e 12 managers da empresa Pepsico Portugal, que operam na sede. Os dados de Inteligência Emocional foram recolhidos através da escala de Rego e Fernandes (EIE) e a Liderança através do questionário MLQ de Bass e Avolio. Os resultados obtidos confirmam a existência de relação entre Inteligência Emocional e Liderança Transformacional auto percecionada, assim como com algumas das suas dimensões (Influência Idealizada e Consideração individual). No que concerne à Liderança Transformacional percecionada, apenas se verificou relação entre Inteligência Emocional e a dimensão Influência Idealizada.